JP2004050158A - Heavy metal immobilizing material and method for treating contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for processing soil contaminated with heavy metals to an immobilized compound which does not stably emit the heavy metals for a long period of time in spite of contact with a solution exhibiting a pH of 4 to 9 which acidic rain may bring by treating the soil on site of ordinary temperature. <P>SOLUTION: The immobilizing material (S) is composed of a powdery one-pack composite composition (PS) prepared by homogeneously mixing active silica (SS) having a silanol group, reactive alumina (SA), sodium hydroxide (SN), and calcia composition (SC), and further mixing a powder addition assisting composition (ST). The soil is treated in an immobilization treatment step in which reacting/curing conditions are applied to the mixture prepared by intimately mixing the immobilizing material (S) with a device for adding water to the contaminated soil. <P>COPYRIGHT: (C)2004,JPO

Description

【００５８】
汚染土壌に関しては、「土壌・地下水汚染に係る調査・対策指針運用基準」の中で環境基準にある重金属等（シアン、ＰＣＢ、農薬を含む）と揮発性有機化合物の２種類に分類されている。したがって、一部例外的ではあるが、不揮発性ならびに揮発性を軸に分類され、調査や対策において区別されている。
【００５９】
本発明においては、重金属類で汚染されている地盤や土壌を対象としている。しかし、本発明の技術は、ケイ酸塩を主成分として重金属類で汚染されている素材である廃棄物類の焼却灰、火力発電所から排出されるフライアッシュ、海・河川・沼・湖・ダム等に堆積しているヘドロ等を対象として重金属類の固定化ならびに不溶性化を行うこともできる。
【００６０】
［固定化材（Ｓ）］
本発明で採択される固定化材（Ｓ）は、シラノール基を有する活性シリカ（ＳＳ）、反応性アルミナ（ＳＡ）、水酸化ナトリウム（ＳＮ）ならびにカルシヤ組成物（ＳＣ）の基礎的な必須四成分構成の粉末状複合組成物（ＰＳ）、さらに付加補助組成物（ＳＴ）ＷＰ加えた五成分構成の粉末状複合組成物（ＰＳ）として調製されている。さらに固定化材（Ｓ）は、必須四成分構成および五成分構成の粉末状複合組成物（ＰＳ）に水が加わってスラリー状に予め調製されているスラリー状複合組成物（ＬＳ）として調製されている。
【００６１】
本発明のシラノール基を有する活性シリカ（ＳＳ）としては、シリカ（ＳｉＯ_２）を主成分とする非晶質ケイ酸（ＳＳ１）、ケイ酸アルカリ（ＳＳ２）、さらにケイ酸アルミニウムを主骨格とするフェロケイ酸塩の層状粘土鉱物（ＳＳ３）等、またシリカとアルミナを複合主成分とするスラッジケーキ等のシリカ−アルミナ複合組成物（ＳＳ４）、さらにまた、ケイ酸ならびにケイ酸塩に水酸化ナトリウム等のアルカリを反応せしめてシラノール基を保有させたアルカリ変性ケイ酸塩（ＳＳ５）を挙げることができる。
【００６２】
活性シリカ（ＳＳ）の非晶質ケイ酸としては、ヒドロゲル状で非晶質のケイ酸を好適に挙げることができる。一般に非晶質ケイ酸は、ケイ酸アルカリ等を酸中和して脱アルカリすることで調製される。また、熔融シリカをメカノケミカル的に部粉砕する工程で調製される非晶質のケイ酸も本発明では採択することができる。
【００６３】
また、活性シリカ（ＳＳ）のケイ酸アルカリとしては、下記組成式（１）
Ｍ^１ _２Ｏ・ａＳｉＯ_２・ｗＨ_２Ｏ　………　（１）
（式中：Ｍ^１はアルカリ金属元素、ａは零を含む２０以下の数、ｗは１，６ないしは５０．０以下の数）で表される粉状ないしは液状のケイ酸アルカリの群より選ばれた単独ないしは２種以上の組み合わせで構成されるケイ酸アルカリを好適に挙げることができる。
【００６４】
ケイ酸アルカリにおけるアルカリ金属Ｍは、一般に入手が容易であり安価であることからナトリウム（Ｎａ）が好適である。しかし、固定化材（Ｓ）の使用目的・用途ならびに作業性から、アルカリ金属にカリウムやリチウムを単独にもしくはナトリウムと複合せしめた複合ケイ酸塩を採択することもできる。中でもケイ酸ナトリウムは、水ガラスとしてＪＩＳ化されて工業的に大量生産されて安価であり好適に採択することができる。
【００６５】
しかも、ケイ酸ナトリウムは、本発明固定化材（Ｓ）の必須構成成分であるナトリウム成分を共存しており、本発明の固定化材（Ｓ）用活性シリカ（ＳＳ）として好適である。また、本発明の固定化材（Ｓ）が粉末状のワンパック複合組成物（ＰＳ）であるときは、粉末状のケイ酸アルカリを選択すればよく、スラリー状のワンパック複合組成物（ＳＳ））であるときは、液状のケイ酸アルカリを選択すればよい。
【００６６】
また、活性シリカ（ＳＳ）のケイ酸アルミニウムを主骨格とするフェロケイ酸塩の層状粘土鉱物としては、一般に非晶質のアロフェンやヒシンゲル石ならびに結晶性フェロケイ酸塩（２：１層型のパイロフェライト、タルク、雲母群、モンモリロナイト石群、バーミキュル石；２：２層型のリョクデイ石群；１：１層型のカオリナイト）とイノケイ酸塩（パルゴルスカイト群）等を挙げることができる。
【００６７】
本発明においては、上記いずれの層状粘土鉱物も採択できるが、入手の容易さ等から、含水のフェロケイ酸塩鉱物である２：１層型で２八面体型もしくは３八面体型のスメクタイ族の含水フェロケイ酸塩鉱物である層状粘土鉱物（Ａ１）を好適に選ぶことができる。含水フェロケイ酸塩鉱物の層状粘土鉱物は、ケイ酸アルミニウムを中心とするポリシロキサン結合中に豊富なシラノール基を確保している粘土類であり、本発明における固定化材（Ｓ）用活性シリカ（ＳＳ）として好適である。
【００６８】
特にスメクタイト族に分類されるモンモリロナイトは、反応性に富んでおり、日本における入手が容易であることから好適である。モンモリロナイトとは、（Ｎａ，Ｃａ_１／２）_０．３３（Ａｌ_１．６７Ｍｇ_０．３３）Ｓｉ_４Ｏ（ＯＨ）_２の組成構造式（但し、層間水は省略）で示される。モンモリロナイトは、正負の電荷間の距離は大で、相互作用の力は弱く容易に陽イオン交換を起こし、シラノール基を豊富に保有することから好ましい。
【００６９】
しかし、含水のフェロケイ酸塩鉱物は天然の鉱物であることから、各種不純物が共存している。したがって、不純物を共存している含水の層状粘土鉱物の場合、層状粘土鉱物、例えばモンモリロナイトを有効成分として少なくとも５０質量％以上含有している粘土鉱物であれば、本発明の目的を損なうことなく層状粘土鉱物として採択することができる。
【００７０】
一般にフェロケイ酸塩鉱物からなる層状粘土鉱物（は、水分２０ないしは３５質量％含有している。しかし、層状粘土鉱物（Ａ１）は、乾燥粉末であることが好ましい。したがって含有水分量が２５質量％以下、好ましく２０質量％以下の量で粉末状態にあることが好ましい。この時の粉末度は、実質的に６５メッシュ篩を少なくとも８０質量％以上通過する粉末に粉砕・分級されていることが反応性ならびに作業性等から好ましい。
【００７１】
また、活性シリカ（ＳＳ）のシリカ−アルミナ複合組成物（ＳＳ４）としては、上水処理場で河川等の水を上水用に浄水処理した際に排出するスラッジケーキ［主成分の例（質量％）：水分６３、ＳｉＯ_２２７、Ａｌ_２Ｏ_３２８、Ｆｅ_２Ｏ_３５．５、ＣａＯ　０．７４、Ｍｇｏ　１．１、Ｃ８．２］、さらには窯業製品生産現場より排出される窯業製品のクズ等を挙げることができる。
【００７２】
これらのシリカ−アルミナ複合組成物（ＳＳ４）は、水酸化ナトリウム等のアルカリと容易に反応して、シリカ−アルミナ複合組成物に本発明の活性シリカにとして有効なシラノール基を保有せしめることができ、しかも産業廃棄物の再利用を可能にする面からも有効である。
【００７３】
さらにまた、活性シリカ（ＳＳ）のアルカリ変性ケイ酸塩（ＳＳ５）としては、ケイ酸ならびにケイ酸塩に予め水酸化ナトリウム等のアルカリを反応せしめて本発明の活性シリカに有効なシラノール基を保有せしめたアルカリ変性ケイ酸塩（ＳＳ５）を挙げることができる。
【００７４】
このときのケイ酸ならびにケイ酸塩としては、火山灰、粘土鉱物、含水泥土、ヘドロならびに各種の廃棄物類等を好適に挙げることができる。これらのケイ酸ならびにケイ酸塩をアルカリ変性ケイ酸塩（ＳＳ５）に調製するためには、水酸化ナトリウム等の水酸化アルカリと水を介して均質混和して、常温もしくは加熱下に反応せしめることによって、容易に原料のケイ酸もしくはケイ酸塩にシラノール基を確保することができる。
【００７５】
本発明における反応性アルミナ（ＳＡ）としては、下記組成式（２）
ｂＭ^Ｉ _２Ｏ・ｃＭ^ＩＩＯ・Ａｌ_２Ｏ_３・ｗＨ_２Ｏ　………　（２）
（式中：Ｍ^Ｉはアルカリ金属元素族、Ｍ^ＩＩはカルシウム、マグネシウム、ないしは亜鉛元素群の単独ないしは２種以上の組み合わせ元素、ｂは零を含む１０以下の数、ｃは零を含む１０以下の数、ｗは零を含む９．０以下の数）で表されるアルカリ金属もしくはアルカリ土類金属のアルミン酸塩またはアルミナの水和物群より選ばれた単独ないしは２種以上の組み合わせのアルミニウム化合物で構成される反応性アルミナ（ＳＡ）として好適に挙げることができる。
【００７６】
本発明で採択する反応性アルミナ（ＳＡ）とは、アルミナ成分を少なくとも１／１０規定の水酸化ナトリウム溶液により常温で反応当量以下の濃度で分散せしめた時アルミン酸イオンを形成するアルミニウム成分をいう。
本発明で採択される反応性アルミナ（ＳＡ）の具体例としては、イオン性アルカリに可溶なアルミナ含有化合物が好適であり、工業薬品である水酸化アルミニウムを好適に挙げることができる。さらにイオン性アルカリに可溶なボーキサイトや石炭灰等のアルミニウム含有各種化合物や鉱物類を選ぶこともできる。
【００７７】
本発明において水酸化ナトリウム（ＳＮ）は、重金属類を水不溶性化合物として固定化するアルミノケイ酸のナトリウム塩であるゼオライト類の構成成分として重要である。水酸化ナトリウム（ＳＮ）としては、工業薬品として汎用されている苛性ソーダを好適に選ぶことができる。勿論、スラリー状の固定化材（Ｓ）を選択するときは、予め必要な水が加えられた溶液状態の苛性ソーダで複合組成物（ＬＳ）を調製することもできる。
【００７８】
本発明におけるカルシヤ組成物（ＳＣ）としては、基本的に乾燥物基準換算で、カルシヤをＣａＯで表して少なくとも２５質量％含有しているカルシヤもしくはカルシウム塩化合物であることが好ましい。本発明の固定化材（Ｓ）において、カルシヤ組成物（ＳＣ）を複合共存せしめる理由は、共存カルシウムイオンが触媒的役割を果たして活性シリカを刺激し、アルミノケイ酸のナトリウム塩であるゼオライト構造形成を支援して、効果的にゼオライト類構造を形成せしめところにある。
【００７９】
本発明で採択されるカルシヤ組成物（ＳＣ）は、下記に示す７種類が好適である。
▲１▼　カルシウムの酸化物や水酸化物であるカルシヤ標準組成物（ＳＣ１）
▲２▼　カルシウムのオキシ酸塩化合物類であるオキシ酸塩組成物（ＳＣ２）
▲３▼　カルシウムのハロゲン塩化合物類であるハロゲン塩組成物（ＳＣ３）
▲４▼　高炉スラグ、焼却灰等の廃棄物類である廃棄物粉体組成物（ＳＣ４）
▲５▼　アルミナセメント・セメント類であるセメント粉体組成物（ＳＣ５）
▲６▼　ケイ酸カルシムをアルカリで変性したアルカリ変性組成物（ＳＣ６）
▲７▼　石灰岩や貝殻等の炭酸塩を脱炭酸した炭カル酸変性組成物（ＳＣ７）
【００８０】
本発明におけるカルシヤ組成物（ＳＣ）は、固定化材（Ｓ）による重金属類固定化機能を発揮させる目的・作業性等に応じて、天然鉱物資源、工業薬品、石灰岩や貝殻等の炭酸カルシウムを脱炭酸させたカルシヤ類、セメント類、さらにカルシウム塩化合物を含有する廃棄物類等、さらにこれらカルシウム原料を加工変性処理した組成物の中から適宜選択して採択することができる。
【００８１】
本発明で採択されるカルシヤ組成物（ＳＣ）としては、カルシヤ成分をＣａＯで表して２５質量％以上、好適には３５質量％以上、さらに好適には５０質量％含有している反応活性の高いカルシヤを主成分とする粉末状の酸化カルシウムや水酸化カルシウムが好適である。但し、カルシヤ（生石灰）は、水と激しく反応して多量の熱量（１モルで１５５４０ｃａｌ．）を発生するので取扱いに注意を要する。
【００８２】
カルシヤ組成物（ＳＣ）を構成するカルシウム化合物は、天然または合成のカルシウムの酸化物や水酸化物であることが好ましい。しかし、これらのカルシウム化合物は、空気中に存在する炭酸や水との反応に敏感で、一般に一部が炭酸塩に変質しており、また天然品では各種不純物を含有している。したがって、固定化材（Ｓ）に採択する時、その施工仕様等により適宜選択して必要に応じて予め精製処理して採択することが望ましい。
【００８３】
勿論、本発明で採択されるカルシヤ組成物（ＳＣ）は、カルシウム元素と周期律表上同族元素であるアルカリ土類金属のマグネシウム、亜鉛、ストロンチウムならびにバリリウム元素等が混在共存している場合があるが、１０質量％以下の量で混在する限り、カルシヤ組成物（ＳＣ）として本発明の基本的化学反応ならびに特定される効果を損なうものではない。
【００８４】
カルシヤ組成物（ＳＣ）の代表的な組成物として、下記組成物式（３）
ＣａＯ・ｗＨ_２Ｏ　………………　（３）
（式中；ｗは零を含む２以下の数）で表される酸化カルシウムまたは水酸化カルシウム群より選ばれた単独ないしは２種以上の組み合わせで構成されるカルシヤ成分をＣａＯで表して５０質量％以上含有している粉末状カルシヤを主成分とするカルシヤをカルシヤ標準組成物（ＳＣ１）として好適に挙げることができる。
【００８５】
カルシヤ標準組成物（ＳＣ１）を構成する酸化カルシウム（別名：カルシヤ、生石灰）は、天然の石灰岩、霞石、方解石、大理石等さらには貝殻等の炭酸カルシウム（ＣａＣＯ_３）を約９００℃以上の熱雰囲気下で脱炭酸して生石灰として大量に生産されており、鉄鋼、化学工業、紙、建材、肥料、農薬、土壌改良等の広い分野で使用されており、安価で入手が容易である。
【００８６】
特に、ホタテや牡蠣等の貝殻は、カルシウム成分原料として宝庫である。しかし、貝殻の主成分が安定した炭酸カルシウムであることから有効利用されずに放置され処分に窮している。処理処分に窮している貝殻を本発明のカルシヤ組成物（ＳＣ）原料として採択することは、貝殻の再利用につながり有効である。しかも、貝殻を原料として海底汚染土壌であるヘドロ等の固定化固化再利用に応用することは、海からの産物により海の環境を改善できることから好ましい。
【００８７】
また、水酸化カルシウム（消石灰）は、生石灰として調製された酸化カルシウムに水を加えて消化させることにより生産されており、化学工業（砂糖、皮革、晒粉）、建築・建材、肥料、農薬、土壌安定処理等の広い分野で大量に使用されており、安価で入手が容易であり、本発明の標準的カルシヤ組成物（ＳＣ）として好適に採択することができる。
【００８８】
本発明の固定化材（Ｓ）に採択されるカルシヤ組成物（ＳＣ）の他の態様として、下記組成（４）
Ｃａ_ｎＴＯ_ｍ・ｗＨ_２Ｏ　………………　（４）
（式中；Ｔはアルミニウム、ケイ素、硫黄、窒素元素の群の単独ないしは２種以上の組み合わせ元素、ｎは１．０ないしは６．０の数、ｍは０．５ないしは６．０の数、ｗは零を含む２８，０以下の数）で表されるカルシウムの各元素の正塩または塩基性塩のオキシ酸塩化合物群より選ばれた単独ないしは２種以上の組み合わせで構成され、カルシウムをＣａＯの酸化物基準で少なくとも２５質量％を含有するカルシヤの各元素のオキシ酸塩化合物の粉末をオキシ酸塩組成物（ＳＣ２）として好適に挙げることができる。
【００８９】
本発明におけるオキシ酸塩組成物（ＳＣ２）の具体的な例は、アルミン酸カルシウム、ケイ酸カルシウム、硫酸カルシウム、亜硫酸カルシウム、亜硝酸カルシウム、硝酸カルシウム等の各元素のオキシ酸塩化合物類の正塩もしくは塩基性塩、さらに結晶水を伴ったカルシウムのオキシ酸塩化合物を天然鉱物類ならびに工業薬品等の中から適宜選んで好適に採択することができる。
【００９０】
本発明のオキシ酸塩組成物（ＳＣ２）としてアルミン酸カルシウムを採択する時は、水硬性硬化固定組成物（Ｗ）により形成される結着体（Ｈ）に生成するゼオライトのアルミナ成分の補給原料としても好適である。しかもアルミン酸カルシウムは水和力を有する化合物である。したがって、本発明の固定化材（Ｓ）を採択して重金属類の固定化と同時に硬化体を形成せしめようとするときは有利である。
【００９１】
本発明固定化材（Ｓ）に採択されるカルシヤ組成物（ＳＣ）の他の態様として、下記組成式（５）
ＣａＺ・ｗＨ_２Ｏ　………………　（５）
［式中：Ｚはハロゲン元素、ｗは６以下の数］で表されるカルシウムのハロゲン塩群より選ばれた単独ないしは２種以上の組み合わせで構成されるカルシウムのハロゲン塩をハロゲン塩組成物（ＳＣ３）として好適に挙げることができる。
【００９２】
カルシウムのハロゲン塩化合物である粉末ハロゲン塩酸塩組成物（ＳＣ３）が活性ケイ酸組成物（Ｂ）と共存する時、ハロゲン塩酸塩組成物（ＳＣ３）のハロゲンイオンが活性ケイ酸組成物（Ｂ）に対して、アルカリ反応の触媒的役割を果たすことから、本発明のカルシヤ組成物（ＳＣ）として好適に採択することができる。しかも、カルシウムのハロゲン塩化合物は、工業薬品として安価であり、入手が容易であり、本発明の固定化材（Ｓ）の構成原料として好適である。
【００９３】
本発明におけるハロゲン塩酸塩組成物（ＳＣ３）の具体的な例は、フッ化カルシウム、塩化カルシウム、臭化カルシウム等の無水物、結晶水を伴った化合物を試薬ならびに工業薬品から挙げることができる。一般には塩化カルシウムが工業的に大量に生産されて安価であり好適である。
【００９４】
本発明の固定化材（Ｓ）に採択されるカルシヤ組成物（ＳＣ）の他の態様として、廃棄物粉体組成物（ＳＣ４）を挙げることができる。特に産業廃棄物の中には、活性なカルシウム成分を多量含有している粉体廃棄物がある。また、これらカルシウム成分を含有する粉体廃棄物は、一般に固定化材（Ｓ）の必須成分である活性アルミナも含んでいることから好適である。
【００９５】
たとえば、製鉄所から排出される高炉スラッグ、製紙業界から排出される石灰中和スラッジ、建築業界から排出される廃石こうボード、各種の廃棄物類を焼却して排出される焼却灰類、石炭火力の電力業界から排出されるフライアッシュ、断熱・保温材の廃材として排出されるケイ酸カルシウム粉体、上水用浄水処理所から排出される処理スラッジ、また産業工場の廃水処理や石油を燃料としたときに排出される排煙から脱硫処理で副生回収された石こう等のカルシウム成分を主成分とする粉末状の廃棄物類を好適に挙げることができる。
【００９６】
本発明のカルシヤ組成物（ＳＣ）の廃棄物粉体組成物（ＳＣ４）として採択される粉末のケイ酸カルシウムは、調製される固定化材（Ｓ）のシリカ濃度を落とすことなく調製できることから好適である。具体的には結晶性ウオラストナイトやゾーノトライト等、非晶質のケイ酸カルシウムとして保温・断熱材として使用された廃材のケイ酸カルシウムが好適である。
【００９７】
さらにまた、本発明における廃棄物粉体組成物（ＳＣ４）として、有機質含有廃棄物類（間伐材、剪定廃材、農業・畜産・水産における廃棄物類、各種発酵残渣、食品加工残渣、残飯、ペーパースラッジ等）を焼却処理した灰もしくは乾留処理した炭含有灰類をも好適に挙げることができる。
【００９８】
本発明の固定化材（Ｓ）に採択されるカルシヤ組成物（ＳＣ）の他の態様として、セメント粉体組成物（ＳＣ５）を挙げることができる。本発明のセメント粉体組成物（ＳＣ５）としては、工業的に大量生産されており、安価に汎用されているポルトランドセメントが入手容易であり好適である。
【００９９】
ポルトランドセメントは、ＪＩＳ　Ｒ　５２００に規定されており、普通、早強、超早強、中庸熱、耐硫酸等に分類されている。さらに、混合セメント（高炉セメント、シリカセメント、フライアッシュセメント等がある。さらにまた、各種の特殊セメント（白色セメント、アルミナセメント，超速硬性セメント、コロイド状セメント、油井セメント、地熱セメント、膨潤セメント、その他の特殊セメント等）の水硬性セメント鉱物類の粉体を好適に挙げることができる。
【０１００】
本発明のセメント粉体組成物（ＳＣ５）は、それ自体が水硬性機能を有するセメント鉱物であることから、水との混和で水和物を生成して固化体を形成する。しかし、セメント粉体組成物（ＳＣ５）に対する期待は、セメント自体の固化体形成機能でなく、活性ケイ酸組成物（Ｂ）が有するシラノール基によるポリマー化反応を促進せしめ、固定化材（Ｓ）としての機能を発揮させるところにある。
【０１０１】
本発明の固定化材（Ｓ）に採択されるカルシヤ組成物（ＳＣ）の他の態様として、アルカリ変性組成物（ＳＣ６）を挙げることができる。アルカリ変性組成物（ＳＣ６）としては、ケイ酸塩含有カルシヤ化合物類（例えば、ケイ酸カルシウム、高炉スラッグ、フライアッシュ、焼却灰、セメント類等）１００質量部に対して、アルカリ金属の水酸化物（ＭＯＨ、Ｍはアルカリ金属）を１ないしは３０質量部、さらに水を５０質量部以下の量で加えて反応せしめたアルカリシラノール基を持つケイ酸塩含有のカルシヤ化合物類を挙げることができる。
【０１０２】
本発明のカルシヤ組成物（ＳＣ）として、ケイ酸塩含有カルシヤ化合物類、例えば断熱・保温材等で使用されるケイ酸カルシウム等にアルカリ金属の水酸化物を加えて処理変性せしめて、固定化材（Ｓ）の必須四成分であるアルカリ金属成分をシラノール基含有のシリカやカルシヤ、さらに選択される原料によってはアルミナに加えて構成させ、固定化材（Ｓ）の構成成分としてアルカリ変性組成物（ＳＣ６）とすることは大変好ましい。
【０１０３】
アルカリ変性組成物（ＳＣ６）の原料とするケイ酸塩含有カルシヤ化合物類としては、廃棄物粉体組成物（ＳＣ４）でもあって、カルシヤと共に活性シリカならびに反応性アルミナをも含んである製鉄所から排出される高炉スラッグ、火力発電所から排出されるフライアッシュならびに浄水処理場から排出される上水処理スラッジ等が、廃棄物類を有効利用できることから好適に挙げることができる。
【０１０４】
ここで予め調製されるアルカリ変性組成物（ＳＣ６）は、粉状ワンパック複合組成物である固定化材（Ｓ）の構成成分とするため、粉状体であることが必須である。ケイ酸塩含有カルシヤ化合物類に反応せしめて回収した反応物がペースト状ないしは可塑状であるときは、乾燥等により予め脱水処理を行ってから粉状ワンパック複合組成物とする必要がある。
【０１０５】
本発明の固定化材（Ｓ）に採択されるカルシヤ組成物（ＳＣ）の他の態様として、炭カル酸変性組成物（ＳＣ７）を挙げることができる。カルシヤ標準組成物（ＳＣ１）の場合のように炭酸カルシウムは約９００℃で加熱脱炭酸されてカルシヤとして回収されている。しかし、活性化処理された活性ケイ酸組成物（Ｂ）は、遊離の硫酸を残した酸性サイドにある。この硫酸等により、炭酸カルシウムを分解せしめてカルシウム原料とする場合も、本発明の固定化材（Ｓ）の原料として活用できることから好ましい。
【０１０６】
本発明の固定化材（Ｓ）に採択されるカルシヤ組成物（ＳＣ）の他の態様として、以上カルシヤ組成物（ＳＣ）類であるカルシヤ標準組成物（ＳＣ１）、オキシ酸塩組成物（ＳＣ２）、ハロゲン塩組成物（ＳＣ３）、廃棄物粉体組成物（ＳＣ４）、セメント粉体組成物（ＳＣ５）、アルカリ変性組成物（ＳＣ６）、ならびに酸変性組成物（ＳＣ７）群の２種以上の組み合わせで構成される粉末状のカルシヤを主成分とする複合せしめた粉末状のカルシヤ複合組成物（ＳＣ８）が、各カルシヤ組成物が有する多機能性をそれぞれ複合的に発揮させることができることから好適に挙げることができる。
【０１０７】
本発明の汚染土壌の処理工法において、処理された処理土壌に求められる目的・用途・現場状況、作業性・物性・性能等に応じて、汚染土壌中の重金属の固定化と合わせて各種機能性を付与した処理工程が要求される。この時、本発明の固化材固定化材（Ｓ）の必須四成分［活性シリカ、反応性アルミナ、水酸化ナトリウム、カルシヤ組成物］に各種の付加補助組成物（ＳＴ）を付加配合せしめて多機能性を有する複合組成物（ＰＳ＆ＬＳ）として固定化材（Ｓ）を調製とすることができる。
【０１０８】
本発明の固定化材（Ｓ）に附加配合さて多機能性を発揮する好適な付加補助組成物（ＳＴ）としては、ゼオライト形成の核となる結晶タネ、硫酸根ならびに燐酸根からなる配合カルシヤ組成物（ＳＣ）の調整剤、バリウム塩からなる反応調整剤、鉄塩からなる砒素やクロム等の捕捉補助剤、吸着性を有する担持補助剤ならびに固定化材（Ｓ）の汚染土壌への分散を助ける機能性能を発揮する付加配合材料類を挙げることができる。
【０１０９】
したがって、本発明における付加補助組成物（ＳＴ）としては、次に示す７種類を好適に挙げることができる。
▲１▼　ゼオライト類の結晶を成長させるタネである結晶タネ組成物（ＳＴ１）
▲２▼　カルシウム組成物（ＳＣ）の活性力等を調節させる硫酸根組成物（ＳＴ２）▲３▼　カルシウム組成物（ＳＣ）の活性力等を調節させる燐酸根組成物（ＳＴ３）▲４▼　混和処理工程における作業性等を調節するバリウム塩組成物（ＳＴ４）
▲５▼　砒素やクロム等重金属類の固定化を補助する鉄塩補充組成物（ＳＴ５）
▲６▼　イオン性重金属を担持捕捉して固定化助ける担持補助組成物（ＳＴ６）
▲７▼　固定化材の土壌への接触効果を向上せしめる分散媒質組成物（ＳＴ７）
【０１１０】
本発明における付加補助組成物（ＳＴ）は、本発明の必須四成分構成［活性シリカ（ＳＳ）、反応性アルミナ（ＳＡ）、水酸化ナトリウム（ＳＮ）、カルシヤ組成物（ＳＣ）］に予め混合させて粉末状の複合組成物としてワンパックさせておくことが取り扱い上ならびに作業性から好適である。そのためにも、本発明で採択される付加補助組成物（ＳＴ）は、浹雑物を取り除き予め粉末状に精製・調製されていることが好ましい。
【０１１１】
本発明の付加補助組成物（ＳＴ）として好適な結晶タネ組成物（ＳＴ１）は、本発明の固定化材（Ｓ）から形成されるアルミノケイ酸塩であるゼオライト類の結晶を生成させる核として存在し、ゼオライト類を速やかに成長させるタネとして固定化材（Ｓ）に共存せしめておくことは好ましい。
【０１１２】
本発明の固定化材（Ｓ）に添加配合される結晶タネ組成物（ＳＴ１）としては、下記に示す単位格子の化学組成式（６）
Ｍ_ｘ／ｎ・［（ＡｌＯ_２）_ｘ・（ＳｉＯ_２）_ｙ］・ｗＨ_２Ｏ………（６）
［式中：Ｍは原子価ｎ：の金属陽イオン、Ｘ＋Ｙは単位格子当りの四面体数］で表されるアルミノケイ酸の金属塩［Ｍは、ナトリウムならびにカルシウムが一般的］のゼオライト構造を有するゼオライトを結晶成長用タネとして好適である。
【０１１３】
特に本発明における結晶タネ組成物（ＳＴ１）としては、天然品を選ぶこともできるが、工業的に生産される結晶型の定まっているゼオライト、例えば４Ａタイプの合成ゼオライト等が好適である。これらのタネとなるゼオライトは、粒径が１０μ以下、好むらくは６μ以下の微細粒子であることがタネとして好ましい。
【０１１４】
本発明の付加補助組成物（ＳＴ）として好適な硫酸根組成物（ＳＴ２）は、本発明の固定化材（Ｓ）を構成しているカルシヤ組成物（ＳＣ）を中和して、処理土壌のｐＨ値をいたずらに向上させないｐＨ調整剤として重要である。特に、本発明においては、固定化材（Ｓ）によりアルミのケイ酸塩のナトリウム塩が形成され、含有ナトリウム元素がイオンとならず、固定化される。
【０１１５】
しかし、このアルミのケイ酸塩のナトリウム塩の形成に配合されているカルシウム組成物（ＳＣ）のカルシウムイオンが果たす触媒的役割は重要でるが、硫酸根組成物（ＳＴ２）が共存することは、アルミのケイ酸塩のナトリウム塩であるゼオライト類が形成された後は、カルシウムイオンによる処理土壌が示すアルカリ性を回避することができることから、硫酸根組成物（ＳＴ２により）硫酸カルシウムの結晶形成は有効である。
【０１１６】
本発明の固定化材（Ｓ）に付加配合される硫酸根組成物（ＳＴ２）は、下記組成式（７）
ａＭ^Ｉ _２Ｏ・ｂＭ^ＩＩＯ・ｃＭ^ＩＩＩ _２Ｏ_３・ＳＯ_ｎ・ｗＨ_２Ｏ………（７）
［式中：Ｍ^Ｉはアルカリ金属元素、Ｍ^ＩＩはアルカリ土類金属元素、Ｍ^ＩＩＩは３価のアルミニウムないしは鉄、ａ、ｂおよびｃは零を含む２０以下の数、ｗは零を含む２５以下の数］で表される塩基性塩や正塩のアルカリ金属を含むアルミニウムもしくは鉄の硫黄のオキシ酸塩化合物群より選ばれた単独ないし２種以上の組み合わせで構成される硫酸根組成物（ＳＴ２）を挙げることができる。
【０１１７】
本発明に好適な硫酸根組成物（ＳＴ２）としては、硫酸アルミニウムを主成分とする明礬型組成物（ＳＴ２−ａ）ならびに硫酸ナトリウムを主成分とする芒硝型組成物（ＳＴ２−ｂ）、さらにこれらの硫酸塩類を複合させた複合型組成物（ＳＴ２−ｃ）に分類して挙げることができる。
【０１１８】
硫酸根組成物（ＳＴ２）である明礬型組成物（ＳＴ２−ａ）としては、下記組成式（７−ａ）
ａＭ^Ｉ _２Ｏ・ｃＭ^ＩＩＩ _２Ｏ_３・ＳＯ_ｎ−ｗＨ_２Ｏ………（７−ａ）
［式中：Ｍ^Ｉはアルカリ金属元素、Ｍ^ＩＩＩは３価のアルミニウムないしは鉄、ａは０．２ないしは２０の数、ｃは１ないしは２０の数、ｗは零を含む２５以下の数、ｎは２または３の数］で表される塩基性塩もしくは正塩のアルカリ金属を含むアルミニウムまたは鉄の硫黄のオキシ酸塩化合物群より選ばれた単独ないしは２種以上の組み合わせで構成される明礬型組成物（ＳＴ２−ａ）を挙げることができる。
【０１１９】
明礬型組成物（ＳＴ２−ａ）であるアルカリ金属のアルミニウムまたは鉄の硫黄のオキシ酸塩としては、硫酸アルミニウムと硫酸カリウム等との混合溶液から生成する正八面体のＫ_２ＳＯ_４・Ａｌ_２（ＳＯ_４）_３・２４Ｈ_２Ｏの複塩結晶が代表的である。なお、本発明における硫酸根組成物（ＳＴ２）として、（７−ａ）式におけるａが零の場合の硫酸アルミニウムならびに硫酸鉄も有効に採択することができる。
【０１２０】
さらに本発明の固定化材（Ｓ）においては、ゼオライト類の生成を期待することから、ゼオライト類の構成成分であるアルミニウム成分の共存は有効である。四成分構成の複合組成物（ＰＳ＆ＬＳ）にはアルミニウムを含有しているが、明礬型組成物（ＳＴ２−ａ）である硫酸アルミニウムのアルミニウム成分はゼオライト類のアルミニウム成分としても有効である。
【０１２１】
さらにまた、本発明の固定化材（Ｓ）によりゼオライト類が形成されて汚染土壌含有の重金属類は固定化されるが、このとき、重金属類である砒素やクロムは、鉄イオンが共存していることにより有効に固定化されることが知られており、明礬型組成物（ＳＴ４−ａ）が鉄イオンを含有していることは有効である。
【０１２２】
硫酸根組成物（ＳＴ２）である芒硝型組成物（ＳＴ２−ｂ）としては、下記組成式（７−ｂ）
ａＭ^Ｉ _２Ｏ・ＳＯ_ｎ・ｗＨ_２Ｏ　………　（７−ｂ）
［式中：Ｍ^Ｉはアルカリ金属元素、ａは１ないしは２０の数、ｗは零を含む２０以下の数、ｎは２または３の数］で表される塩基性塩もしくは正塩のリチウム、ナトリウムもしくはカリウムであるアルカリ金属の硫黄のオキシ酸塩化合物群より選ばれた単独ないしは２種以上の組み合わせで構成される芒硝型組成物（ＳＴ２−ｂ）を好適に挙げることがきる。
【０１２３】
芒硝型組成物（ＳＴ２−ｂ）であるリチウム、ナトリウムもしくはカリウムであるアルカリ金属の硫黄のオキシ酸塩化合物の代表化合物は、芒硝（Ｎａ_２ＳＯ_４・１０Ｈ_２Ｏもしくは無水塩）として天然に産し、また石灰芒硝である石こうとの複塩として岩塩産地で産する。工業的には廃液処理時の副生芒硝等として副生されている。
【０１２４】
本発明においては、不純物を含む天然ならびに合成・副生のいずれの芒硝も好適に採択することができる。またカリウムを含む複塩や塩基性塩、アルカリ土類金属の塩類化合物、炭酸塩が共存している混合複合塩等の化合物類も、芒本発明の硝型組成物（ＳＴ２−ｂ）として好適に採択することができる。
【０１２５】
硫酸根組成物（ＳＴ２）である複合型組成物（ＳＴ２−ｃ）として、明礬型組成物（ＳＴ２−ａ）および芒硝型組成物（ＳＴ２−ｂ）群の２種以上の組み合わせで構成される複合された硫酸根組成物（ＳＴ２）を挙げることができる。複合型組成物（ＳＴ２−ｃ）は、本発明の固定化材（Ｓ）の用途・目的等や作業性等により選択して採択することができる。
【０１２６】
本発明の付加補助組成物（ＳＴ）として好適な燐酸根組成物（ＳＴ３）は、本発明の固定化材（Ｓ）を構成しているカルシヤ組成物（ＳＣ）を中和して、処理土壌のｐＨ値をいたずらに向上させない調整剤として硫酸根組成物（ＳＴ２）の場合と同様な理由により重要である。
【０１２７】
特に、アルミのケイ酸塩のナトリウム塩であるゼオライト類が形成された後は、遊離しているカルシヤ組成物（ＳＣ）により処理土壌が高いアルカリ性を示し、二次公害を発せ留真φがあるが、燐酸カルシウム結晶の形成により、その心配が回避することができることから有効である。
【０１２８】
本発明の固定化材（Ｓ）である燐酸根組成物（ＳＴ３）としては、下記組成式（８）
ｈＧＯ_ｔ・Ｐ_２Ｏ_５・ｗＨ_２Ｏ　………　（８）
［式中：Ｇはナトリウム、カリウム、マグネシウム、カルシウム、バリウム、アルミニウム、チタン、ケイ素ならびに鉄の群の単独ないしは２種以上の組み合わせ元素、ｈは１．０ないしは８．０の数、ｔはＧ元素原子価÷２の数、ｗは零を含む１０以下の数］で表される各金属元素のリンのオキシ酸塩化合物群より選ばれた単独ないしは２種以上の組み合わせで構成されるホウ素のオキシ酸塩化合物類を好適に挙げることができる。
【０１２９】
本発明で採択される燐酸根組成物（ＳＴ３）の具体的な例としては、試薬もしくは工業薬品の中から、リン酸ナトリウム、リン酸カリウム、リン酸マグネシウム、リン酸カルシウム、リン酸バリウム、リン酸アルミニウム、リン酸チタン、リン酸ケイ素、リン酸鉄等の中から適宜選択することができる。
【０１３０】
さらに、本発明の燐酸根組成物（ＳＴ３）においては、金属製品（自動車、車輌、建材、家電等）の表面処理剤（パーカーライジング処理剤）として汎用されているリン酸系薬品による処理後、産業廃棄物として排出されるリン酸塩を多量に含んだスラッジを有効に利用することができる。
【０１３１】
さらにまた、本発明の燐酸根組成物（ＳＴ３）として、アルカリ性条件の中でリン酸分の徐放性を示す粉末状のリン酸ケイ素を好適に挙げることができる。
リン酸ケイ素は、下記組成式（８−ａ）
ｊＳｉＯ_２・Ｐ_２Ｏ_５　………　（８−ａ）
［式中：ｊは１．０ないしは８．０の数］で表される燐酸ケイ素群より選ばれた単独ないしは２種以上の組み合わせで構成されるケイ素のリンであり、下記に示す「リン酸分の徐放性」を有するオキシ酸塩化合物を好適に挙げることができる。
【０１３２】
リン酸ケイ素における「リン酸分の徐放性」は、下記する試験方法により評価することができ、下記式（Ｔ−１）
Ｙ＝ａＸ＋ｂ　………　（Ｔ−１）
［式中：Ｘはリン酸ケイ素１ｇを４Ｎ（規定）苛性ソーダ溶液１００ｍｌ中に撹拌分散せしめて経過した時間（分）、Ｙは４Ｎ（規定）苛性ソーダ溶液中に溶出したリン酸（Ｐ_２Ｏ_５）量（ｍｇ／１００ｍｌ）］で表されるリン酸ケイ素のリン酸分がアルカリ性溶液中に溶出する初期溶出量（ｂ）が２００以下であり、式中のａに相当する平均加水分解速度定数（ａ）が０．２以上の範囲にあるリン酸分の溶出状態をいう。
【０１３３】
本発明におけるリン酸ケイ素は、強いアルカリサイドの条件下においても簡単に加水分解することなくゼオライト類の形成に当たりリン酸分を徐放させる安定な化合物であることが好ましい。したがって、リン酸ケイ素は、組成式（８−ａ）のｊが１．０ないしは８．０の数の範囲にあって５００ないしは１１００℃の温度範囲で加熱合成されていることが、リン酸分の徐放性を可能にして好適である。
【０１３４】
組成式（８−ａ）のｊが１．０より小さくて７００℃以下で加熱合成されるときは、未反応の潮解性リン酸ケイ素しか合成されずアルカリ調整を期待することはできない。また、ｊが８．０より大きくて１１００℃以上で加熱合成されるときは、含有リン酸が揮散してしまいリン酸ケイ素としての効果を期待することはできない。
【０１３５】
本発明のリン酸ケイ素は、保存中の安定性ならびにリン酸分の徐放性を確保するために当業界で公知・公用のコーティング剤で表面処理が施されていることが好ましい。この場合、コーティング剤としては、アルカリ性溶液中で可溶性の脂肪酸（ステアリン酸等）や脂肪酸塩（ステアリン酸カルシウム等）、さらにはカップリング剤（オルガノシロキサン、チタンカップリング剤等）が常法により０．０１ないしは６．０質量％でコーティング処理されていることが好ましい。
【０１３６】
本発明の固定化材（Ｓ）に添加配合されるバリウム塩組成物（ＳＴ４）としては、下記組成式（９）
ＢａＯ・ｆＳｉＯ_２・ｗＨ_２Ｏ　………　（９）
［式中：ｆは４．０以下の数、ｗは零を含む１０以下の数］で表されるアルカリ溶液に可溶なバリウム塩化合物群より選ばれた単独ないしは２種以上の組み合わせで構成される粉末状のバリウム塩化合物を好適に挙げることができる。
【０１３７】
本発明において、バリウム塩組成物（ＳＴ４）として採択される粉末状のバリウム塩化合物における作業性等の整機能は、「バリウムイオンのアルカリ溶液への可溶分」によって推定することができる。「バリウムイオンのアルカリ溶液への可溶分」は、下記する試験方法により評価することができる。
【０１３８】
「バリウムイオンのアルカリ溶液への可溶分」は、バリウム塩化合物１０ｇを２５℃の１Ｎ（規定）苛性ソーダ溶液１００ｍｌ中に１０分間撹拌分散せしめた試料溶液を濾別した採取溶液中のバリウムイオン量をＢａＯとして測定し、試料バリウム塩化合物中の全バリウム元素をＢａＯで換算した量に対する％で表示して、アルカリ溶液への可溶するバリウム量を求めることによって評価できる。
【０１３９】
本発明の固定化材（Ｓ）により調整したゼオライト類の形成を管理するために、バリウム塩組成物（ＳＴ４）であるバリウム塩化合物の「アルカリ溶液への可溶分」は、１０％以上であることが好適である。「アルカリ溶液への可溶分」が１０％以下であるときは、固定化材（Ｓ）の施工作業性管理が困難となり好ましくない。
【０１４０】
一般に上記の「アルカリ溶液への可溶分」を満足し、安価で入手容易なバリウム塩化合物としては、工業薬品の水酸化バリウム［Ｂａ（ＯＨ）・８Ｈ_２Ｏ］もしくは酸化バリウム［ＢａＯ］が好適である。しかし、形成されるゼオライト類に悪影響を与えず、ゼオライト類の形成に充分な作業可使時間を確保できるバリウム塩組成物（ＳＴ４）としてのバリウム塩化合物としては、ケイ酸バリウムが好適である。
【０１４１】
バリウム塩補６組成物（ＳＴ４）としてのケイ酸バリウムは、組成式（１０）のｋが４．０以下の数であることが良く、４．０以上の数ではバリウムイオンの活性を有効に利用することができない。ま，た、組成式（１０）のｗの数が９．０以下であることが良く、９．０以上の数ではバリウム塩化合物の保存安定性が確保されず、本発明の国定を達成することができない。
【０１４２】
本発明の付加補助組成物（ＳＴ）として好適な鉄塩補充組成物（ＳＴ５）は、汚染土壌に含有される重金属類を水不溶性に固定化せしめるに際し、特に砒素やクロムに対しては、鉄塩を共存せしめておくことは固定化を有効に発揮し、本発明の固定化を効果的に達成する上で好ましい。
【０１４３】
本発明で採択される鉄塩補充組成物（ＳＴ５）としては、２価もしくは３価の水酸化鉄化合物が特に有効である。しかし、工業薬品もしくは廃棄物類として入手容易な面から、２価もしくは３価の塩化鉄や硫酸鉄、さらに金属鉄分を好適に挙げることができる。
【０１４４】
これらの金属鉄分ならびに塩化鉄や硫酸鉄も固定化材（Ｓ）中に配合されているカルシヤ組成物（ＳＣ）との反応、さらに大気中の酸素ならびに水分との反応により容易に２価もしくは３価の水酸化鉄化合物を生成し、重金属類の固定化の補助的効果を充分に発揮することができる。
【０１４５】
本発明の付加補助組成物（ＳＴ）として好適な担持補助組成物（ＳＴ６）は、本発明の固定化材（Ｓ）に配合されている可溶性材料である水酸化ナトリウム（ＳＮ）等を充分に担持もしくは吸着により捕捉していて、汚染土壌中に本発明の固定化材（Ｓ）を混和せしめたときに、配合されている可溶性材料を反応系外に放出させることなく、効果的にゼオライト類を形成せしめる上で重要である。
【０１４６】
本発明における好適な担持補助組成物（ＳＴ６）としては、各種の有機化合物や有機質素材を含有している動物・植物類、ならびに農業・畜産・水産の各分野で回収・生産・加工される天然品やその廃棄物、また各種天然品素材の発酵による製品や発酵残渣、紙・パルプ・繊維布類の製造・加工メーカーから排出される廃棄物類、さらにまた、各種プラスチックやその加工現場から排出される有機質素材等を４０００ないしは１０００℃で乾留処理して回収される炭を主成分とする炭類、また場合によりシリカやアルミナを含有している炭−ケイ酸塩の複合品を挙げることができる。
【０１４７】
本発明の付加補助組成物（ＳＴ）として好適な分散媒質組成物（ＳＴ７）は、汚染土壌に本発明の固定化材（Ｓ）を効果的に均質接触せしめるために分散せしめておく媒質として重要である。本発明の固定化材（Ｓ）に効果的な媒質としては、１００μ以下の粉末、好むらくは１０μ以下の微粉末の無機系化合物が有効であり、特にケイ酸塩系素材は、本発明の固定化材（Ｓ）と相溶性が良く好適である。
【０１４８】
具体的な分散媒質組成物（ＳＴ７）としては、工業的に大量に生産され安価である材料が本発明の分散媒質組成物（ＳＴ７）として好適である。例えば、天然産物では、カオリン、酸性白土、ベントナイト、ボーキサイト、ケイソー土、タルク、ゼオライト、石灰粉、ボーキサイト、パーライト、石膏、火山灰等を挙げることができる。
【０１４９】
さらにまた、大量に排出されている工業会からの廃棄性副産物屋は器物類を上げることができる。例えば、火力発電所から排出されるフライアッシュ、鉄鋼業界等から排出されるスラッグ類、排煙脱硫ならびにチタン工業等より副生する石膏類、ホタテやかきの貝殻の粉砕品等が大量に安価に入手用意であることから好ましい。
【０１５０】
本発明の付加補助組成物（ＳＴ）として好適な複合補助組成物（ＳＴ７）は、本発明の固定化材（Ｓ）にそれぞれの付加補助組成物（ＳＴ）が有する機能性を複合せしめて固定化材（Ｓ）として複数の機能性を複合して発揮させる上で重要である。これら複合させる種類・配合等の条件は、本発明の固定化材（Ｓ）が採択される用途、効果、現地状況、作業性等により異なるので、それぞれの目的に応じて予め行う予備実験により決定する必要がある。
【０１５１】
本発明の複合補助組成物（ＳＴ７）としては、前記した結晶タネ組成物（ＳＴ１）、硫酸根組成物（ＳＴ２）、燐酸根組成物（ＳＴ３）、バリウム塩組成物（ＳＴ４）、鉄塩補充組成物（ＳＴ５）、担持補助組成物（ＳＴ６）ならびに分散媒質組成物（ＳＴ７）郡より選ばれた単独ないしは２種以上の組み合わせで構成される複合補助組成物が好適であり、配合種ならびに配合量は目的・用途に応じて予め行う予備実験により決定される。
【０１５２】
本発明の複合補助組成物（ＳＴ７）は、形成されゼオライト類により重金属類固定化求められる目的・用途・現地状況ならびに作業性等に応じて複合され、補助効果における相乗性が期待される。したがって、本発明の複合補助組成物（ＳＴ７）に選択される種類ならびに配合量等は、目的・用途・現地状況ならびに作業性等に応じて予め行われる予備的実験により確認して採択決定することが好ましい。
【０１５３】
本発明における汚染土壌の処理工法では、水を介して固定化材（Ｓ）を汚染土壌に混和し、含有重金属類を固定化せしめると共に、処理された土壌が硬化・固化することなく、外圧に対して変形性を有する処理土壌に変質せしめることが重要である。このときの固定化材の種類ならびに配合割合は、目的・用途・現地状況ならびに作業性等に応じて選択される。
【０１５４】
本発明の固定化材（Ｓ）で必須四成分構成の粉末状複合組成物（ＰＳ）における配合割合は、シラノール基を有する活性シリカ（ＳＳ）１００質量部に対して、反応性アルミナ（ＳＡ）を５０ないし２００質量部、水酸化ナトリウム（ＳＮ）を１５ないし８０質量部およびカルシヤ組成物（ＳＣ）：を２０ないし３００質量部で均質混合されてワンパック化されていることが、ゼオライト類の形成に効果的で好ましい。
【０１５５】
本発明の必須四成分構成の粉末状複合組成物（ＰＳ）において、活性シリカ（ＳＳ）１００質量部に対して、反応性アルミナ（ＳＡ）が５０質量部より少ないときは、ゼオライト類の形成率が低下する。反応性アルミナ（ＳＡ）が２００質量部以上の場合には未反応アルミナが残り、効果的なゼオライト類の生成が期待できない。
【０１５６】
水酸化ナトリウム（ＳＮ）が１５質量部より少ないときもゼオライト類の形成率が低下し本発明の効果機能が期待できない。また、水酸化ナトリウム（ＳＮ）が８０質量部より多い場合は、処理された土壌にアルカリ成分が遊離して残り、処理土壌をアルカリ性とすることから好ましくない。
【０１５７】
さらに、カルシヤ組成物（ＳＣ）：が２０質量部より少ないときは、常温におけるゼオライト類の形成に及ぼすカルシウムイオンの触媒効率が低下し、ゼオライト類の形成を低下させる。また、カルシヤ組成物（ＳＣ）：が３００質量部より多い時は、固定化材（Ｓ）の増量になるのみで本発明の重金属類の固定化に特段の向上した効果を見ることはできない。
【０１５８】
さらに、本発明固定化材（Ｓ）で五成分構成の粉末状複合組成物（ＰＳ）における配合割合は、必須四成分構成の複合組成物（ＰＳ）１００質量部に対して、付加補助組成物（ＳＴ）を１ないし２００質量部で均質混合されてワンパック化されていることが、目的・用途に応じて多機能性の付加されたゼオライト類の形成に特長ある効果を発揮して好ましい。
【０１５９】
本発明の五成分構成の粉末状複合組成物（ＰＳ）における配合割合において、その配合割合は、目的・用途・作業性等ならびに求められる機能性に応じて、必須四成分構成複合組成物（ＰＳ）１００質量部に対して付加補助組成物（ＳＴ）を２００質量部以内の範囲で付加配合すればよく、付加補助組成物（ＳＴ）を２００質量部以上配合してもゼオライト類を形成させて、さらに特段の機能性向上を期待することはできない。
【０１６０】
さらにまた、本発明の固定化材（Ｓ）で必須四成分ないしは五成分構成のスラリー状複合組成物（ＰＳ）１００質量部に対して、水を６０ないし１２０質量部の範囲で加えて予め均質なスラリー状の複合組成物（ＳＳ）に調製しておくことが、汚染土壌と固定化材（Ｓ）との混和による混和処理工程における特定される混和装置において、本発明の複合組成物（ＳＳ）を汚染土壌に均質接触ける作業性を効果的に向上せしめる上で好ましい。
【０１６１】
なお、本発明の固定化材（Ｓ）である複合組成物（ＰＳ）は、水の共存により反応を開始することから、固定化材（Ｓ）の保存中は、水との接触は極力避ける方向であることが好ましく。また、固定化材（Ｓ）は反応性のカルシヤを含んでいることから、炭酸ガス等との接触も極力避ける方向で保管管理されることが好ましい。
【０１６２】
［固定化処理工程］
本発明においては、含有重金属類を効率よく不溶性に固定化し、しかも固定化された処理土壌を硬化・固化させることなく変形性処理土壌とすることを目的としている。その目的を達成するためには、汚染土壌に対して水を介して固定化材（Ｓ）を均質に接触せしめて混和物を形成させる必要がある。このとき、処理される土壌の使用目的・用途、現場状況、経済性を含めた作業性等に応じて、形成される混和物を可塑性ないし流動性混和物に調製する工程が重要である。
【０１６３】
当然、汚染土壌における重金属類の固定化と並行して処理された土壌の地盤に一定の硬さ・強度が確保された地力を要求される場合は、本発明者らの出願特許（特開平１１−２４６２６１、特願２０００−３５１９３１、特願２００１−０８３８１６、特願２００１−２３４１８３等）に開示されている技術と公知・公用の地盤改良、もしくは本発明技術と組み合わせて実行することにより目的を達成することができる。
【０１６４】
また、本発明の汚染土壌処理工法によれば、固定化材（Ｓ）により汚染土壌を一旦採掘移動するか、もしくは表層部もしくは深層部の原位置で含有重金属類が水不溶性に固定化された処理土壌に変質せしめることができる。このとき固定化処理された処理土壌を土地活用地盤として再利用することもできるが、処理土壌を他の用途に利用活用することもできる。
【０１６５】
本発明による処理土壌を他の用途に活用するに際して、処理土壌を取り扱い易い顆粒状に予め造粒しておくことは有効である。前述した本発明者らの出願特許では、重金属類の固定化機能と共に、含水土壌を硬化・固化させる機能を併せ発揮させる技術が開示されている。具体的には、固化機能と並行して重金属類固定化機能を有する固化材を汚染土壌に加えて可塑性ないし流動性混和物に処理し、次いで当業界で土壌やケイ酸塩系粉体等を造粒・顆粒化する装置を用いて、混和物を粒径が０．５ないしは３５ｍｍφの希望形態の顆粒状に造粒し、必要に応じて大気中または加熱で乾燥して顆粒品とすることで有効に利用することができる。
【０１６６】
さらにまた、処理対象とする汚染土壌が有機質物質、例えばダイオキシン類や有機質環境ホルモン等を重金属類と併せて含有していて複合汚染されている汚染土壌もある。この場合、含有するが有機質物質が重金属類を固定化するゼオライト類の形成を妨げるものでない。しかし、本発明の工法により重金属類を処理するに先立って有機質物質を公知・公用の分解除去方法、例えば加熱処理等により有機質物質を分解除去してから、引き続き本発明の処理工法に付することにより複合汚染の土壌を完全に修復・再生できることから有効である。
【０１６７】
本発明において、形成される混和物が可塑性であることは、流れ性のない混和物に外圧を加えて弾性限界を超えて変形を与えるとき、外圧を取り去っても歪がそのまま残る状態をいう。このときの可塑性混和物の形状は、大きい塊の集合である場合もあれば、整粒された細かい砂粒である場合もあり、またさまざまな形状・大きさが混在している混和物である場合もある。
【０１６８】
また、本発明において、形成される混和物が流動性であることは、混和物を傾斜のあるに滑り性の良い板上にセットしたときに、下方に向かって流れ移動する状態にあることをいう。したがって、この時の流動性混和物は、保有する流れ性を利用して、形成された流動性混和物を例えば狭い箇所に注入することもできる。また、流れ性を利用して、汚染土壌を採掘した場所やその他の場所に流しながら移動せしめて重金属類を固定化することができる。
【０１６９】
実際の土壌においては、土壌に水分が含まれている場合が多い。したがって、混和物の調製に際しては、対象土壌に含まれている水分を測定し、このときの水分量を換算し、しかも処理された変形性処理土壌の使用目的・用途、現場状況等を勘案して、本発明の混和物とするときの配合量を決定する必要がある。
【０１７０】
本発明の可塑性混和物は、乾燥物基準換算で含有汚染土壌１００質量部に対して、固定化材（Ｓ）を５ないし３０質量部および水を６０質量部未満の量割合で均質混和することによって達成される。この時、固定化材（Ｓ）の量割合が５質量部より少ないときは、固定化材（Ｓ）としての機能性を発揮することができず、また３０質量部より多くの固定化材（Ｓ）を加えても格別な効果の向上は見られず経済性がない。
【０１７１】
水を少なめに介在せしめて可塑性混和物を形成せしめたときは、汚染土壌の原位置での固定化処理に有効であり、簡易な混和処理装置を現地に運び込み作業をすることができることから、汚染土壌の固定化処理のみを目的として経済性のある工法を選択できることから有利である。もちろん汚染土壌を一旦採掘して、採掘汚染土壌を可塑性混和物形成可能な混和装置に移動せしめ、均質に接触混和して汚染土壌の固定化処理を施すこともできる。
【０１７２】
本発明の流動性混和物は、乾燥物基準換算で重金属類含有汚染土壌１００質量部に対して、固定化材（Ｓ）を５ないし３０質量部および水を６０ないしは１４０質量部の量割合で均質混和することによって達成される。水の量割合が、６０質量部よりも少ないときは、混和物は流動性を失う。また水の量割合が、１４０質量部よりも多いときは、混和物はしゃぶしゃぶ状態となり土壌としての性質を失う。
【０１７３】
本発明の汚染土壌に対して、水を介して固定化材（Ｓ）を接触せしめて均質に混和せしめる方式を可能とする混和装置としては、一般に土木工事における地盤改良工法において、地盤土壌とセメントや生石灰、さらに固化薬剤等の固化材等を接触混合せしめる各種の方式・工法、さらにはそれら方式・工法の改良方式・工法において採択されている混和装置類が、本発明の固定化処理工程における接触混合を可能にする混和装置としても好適に採択することができる。
【０１７４】
汚染土壌と固定化材（Ｓ）との混和処理工程を可能とする接触混合方式としては、可塑性もしくは流動性混和物のいずれを混和物を選ぶかにより異なるが、下記の４種類の方式をそれぞれ代表的に好適方式として挙げることができる。
▲１▼　汚染土壌を撹拌混合可能な容器に移動して混合す事前混合方式
▲２▼　地盤表面より１ｍ未満の原位置表層部で混合する掘削撹拌方式
▲３▼　地盤表面より１ｍ以下の原位置深層部で混合する機械撹拌方式
▲４▼　地盤表面より１ｍ以下の原位置深層部で混合する高圧噴射方式
【０１７５】
混和処理工程における事前混合方式では、撹拌機を具備した容器に汚染土壌が存在する地盤より採掘した土壌を移動搬入せしめ、本発明の固定化材（Ｓ）を所定量、さらに必要に応じて水を加えて混合撹拌し、汚染土壌と固定化材（Ｓ）を均質に接触混合せしめることにより達成される。このとき、採掘土壌の含有水分量が１０質量％以下の乾燥されている場合は、少なくとも１５ないしは５０質量％の範囲で水を追加して加えてから、混合撹拌せしめることが、均質接触せしめるための撹拌効率を向上させ、ゼオライト類形成のために好適である。
【０１７６】
本発明の混和処理工程における掘削撹拌方式では、汚染土壌の地盤表面より１ｍ未満の原位置表層部において、汚染土壌と固定化材（Ｓ）を現地で混和接触せしめることを可能とする混和装置が必要である。この混和装置としては、土木工事における地盤改良工法で採択されている掘削撹拌を可能とする混和装置すべてを本発明の掘削撹拌方式で採択することができる。
【０１７７】
本発明の掘削撹拌方式で採択される具体的な混和装置の例としては、スタビライザー式のかき混ぜ工法、バックホウ式の掻き上げ混合工法、撹拌機能具備したバックホウ工法等を挙げることができる。これら混和装置は現場への持込が容易であり、操作が簡易で経済性があり、地盤表層部において粉末状ないしはスラリー状の固定化材（Ｓ）を接触混合せしめることが可能であり、好適である。
【０１７８】
本発明混和処理工程における機械撹拌方式では、汚染土壌の地盤表面より１ｍ以下の原位置深層部において、汚染土壌と固定化材（Ｓ）を現地で混和接触せしめることを可能とする混和装置が必要である。この混和装置としては、土木工事における深層部の地盤改良工法で採択されている機械撹拌を可能とする混和装置すべてを本発明の掘削撹拌方式で採択することができる。
【０１７９】
本発明の機械撹拌方式で採択される具体的な混和装置の例としては、三点式パイルドライバー（杭打機）等を使用したスパイラル挿入式のアースオーガ工法、ケーシングパイプ強制昇降式の回転圧入工法等を挙げることができる。これら工法に必要な装置は、現地土壌地盤の深層部に固定化材（Ｓ）を送り込み土壌と接触せしめる機械撹拌方式であり、大掛かりであるが、深層部までの大量土壌を処理することが可能であり、それぞれの混和装置に応じて粉末状ないしはスラリー状の固定化材（Ｓ）を接触混合せしめことが可能であり、好適である。
【０１８０】
本発明混和処理工程における高圧噴射方式では、機械撹拌方式と同様に汚染土壌の地盤表面より１ｍ以下の原位置深層部において、汚染土壌と固定化材（Ｓ）を現地で混和接触せしめることを可能とする混和装置が必要である。混和装置としては、土木工事における深層部の地盤改良工法で採択される高圧噴射で土壌と固定化材（Ｓ）の接触混合を可能とする混和装置すべてを本発明の掘削撹拌方式で採択することができる。
【０１８１】
本発明の高圧噴射方式で採択される具体的な混和装置の例としては、粉体噴射撹拌式もしくはスラリー噴射撹拌式の高圧噴射撹拌工法等を挙げることができる。これら工法は、地中に粉末状ないしはスラリー状の固定化材（Ｓ）を回転ノズルにより高圧噴射し、パイル状もしくは噴射したパイル周辺の土壌粒子と固定化材（Ｓ）を接触混合せしめ、本発明の目的を達成させる工法・装置である。
【０１８２】
これら工法に必要な混和装置は、現地土壌地盤の深層部に固定化材（Ｓ）を送り込み土壌と接触せしめる高圧噴射撹拌拌方式であることから、混和装置も大掛かりであるが、深層部までの大量土壌を処理することが可能であり、それぞれの高圧噴射撹拌拌方式の混和装置に応じて粉末状ないしはスラリー状の固定化材（Ｓ）を汚染土壌に接触混合せしめことが可能であり好適である。
【０１８３】
本発明の混和処理工程において、本発明の固定化材（Ｓ）を汚染土壌に均質に接触せしめる工程・方法は、上記した工程・方法に限定されるものでない。実際には、汚染土壌の汚染状況、例えば、有機質汚染物との併汚染、汚染重金属の種類、汚染濃度、ばらつき、汚染箇所の深さ等に応じて、工程・方法はそれぞれに適応した方式・工法が選択されるべきである。
【０１８４】
本発明における特徴は、本発明技術により改質された処理土壌が、汚染土壌に水を介して固定化材（Ｓ）を加えて可塑性ないしは流動性のある混和物として、固定化処理工程に付することによって、含有重金属類がゼオライト類として固定化され、しかも固定化されたゼオライト類がｐＨ４ないし９の範囲にある水系溶媒に接触しても分解することなく安定しており、固定化した重金属類を系外に溶出せしめない点にある。
【０１８５】
この時のｐＨ４ないし９の範囲にある水系溶媒に接触しても分解しない状態を評価するために、下記に示す３種類の重金属類溶出試験方法により評価した。
▲１▼　環境庁告示第４６号溶出試験法［略記：ｐＨ７溶出試験法：］
▲２▼　オランダＮＥＮ７３４１溶出試験法［略記：ｐＨ４溶出試験法：］
▲３▼　アルカリ溶液による溶出試験法［略記：ｐＨ９溶出試験法：］
【０１８６】
さらに、本発明における特徴は、汚染土壌に水を介して固定化材（Ｓ）を加えて可塑性ないしは流動性のある混和物として、固定化処理工程に付することによって、硬化・固化してない外圧により変形性を示す処理土壌とするところにある。このときの変形性を有する処理土壌を評価する手段として、土木・地盤業界において実施されている『標準貫入試験』が標準的である。
【０１８７】
しかるに、「標準貫入試験」は、土木業界におけるにおいて、土壌の相対的硬軟および締まり具合を知る指針であるＮ値を求める試験方法であり、ＪＩＳ　Ａ１２１９　１９９５に規定されており、ボウリング孔を利用して、ロッドの先端に直径５．１ｃｍ、長さ８１ｃｍの標準試験用サンプラーを付けたものを、質量６３．５ｋｇのハンマーで７５ｃｍの高さから自由落下させ、サンプラーを３０ｃｍ貫入させるのに要する打撃回数Ｎ（Ｎ値）を測定する試験方法である。
【０１８８】
したがって、「標準貫入試験」は、地盤原位置におけるボウリング孔を利用して測定する方法であり、実用には即している。しかるに、試験的に行う小規模の処理土壌に関して評価するには適さないことから、本発明においては、「標準貫入試験」に匹敵して替わる評価方法として、簡易型の下記の物性評価試験方法の項に示す「変形性測定試験」を採択した。
【０１８９】
なお、本発明により処理した処理土壌を変形性測定試験方法により測定した強度が８０Ｎ／ｃｍ^２以下、好ましくは５０Ｎ／ｃｍ^２以下である場合の処理土壌が変形性を示しており、一般的な土壌と同様に硬化・固化してない利用しやすい土壌とした。因みに、「標準貫入試験」により測定され土壌地盤における上限Ｎ値５０は、本変形性測定試験で示すと約８０Ｎ／ｃｍ^２に相当する。
【０１９０】
［本発明の物性評価試験方法］
本発明で採択した土壌中の主たる組成分析は、土壌分析法における底質調査方法ＩＩに準拠して、主成分の分析は蛍光Ｘ線分析法により分析した。また、微量重金属類は、底質調査方法に示されている分析方法に準拠した。さらに重金属類溶出試験は、下記に示す各ｐＨ域での溶出試験方法にしたがった。
【０１９１】
採取土壌の取扱い［共通］
採取した土壌は、ガラス容器または測定の対象となる物質が吸着しない容器に収める。試験は、土壌採取後直ちに行う。試験を直ちに行えない場合は、暗所に保管し、できるだけ速やかに試験を行う。
【０１９２】
▲１▼　環境庁告示第４６号溶出試験法（抜粋）［略記：ｐＨ７溶出試験法：］
１−１試料の作成
採取した土壌を風乾し、中小礫、木片等を取り除き、土塊、団粒を粗砕した後、非金属製の２ｍｍの目のふるいを通過させて得た土壌を十分混合する。
１−２試料液の調製
試料（単位ｇ）と溶媒（純粋に塩酸を加え、水素イオン濃度指数が５．８以上６．３以下となるようにしたもの）（単位）とを重量体積比１０％の割合で混合し、かつ、その混合液が５００ｍＬ以上となるようにする。
【０１９３】
１−３溶　出
調製した試料液を常温（おおむね２０℃）常圧（おおむね１気圧）で振とう機（あらかじめ振とう回数を毎分約２００回に、振とう幅を４ｃｍ以上５ｃｍ以下に調整したもの）を用いて、６分間連続して振とうする。
１−４検液の作成
以上の操作を行って得られた試料液を１０分から３０分程度静置後、毎分約３，０００回転で２０分間遠心分離した後の上澄み液を孔径０．４５μｍのメンブランスフィルターでろ過してろ液を取り、定量に必要な量を正確に計り取って、これを検液とする。
【０１９４】
▲２▼　オランダＮＥＮ７３４１溶出試験法（抜粋）［略記：ｐＨ４溶出試験法：］
２−１試料の作成
採取した土壌を風乾し、中小礫、木片等を取り除き、土塊、団粒を粗砕した後、非金属製の２ｍｍの目のふるいを通過させて得た土壌を十分混合する。
【０１９５】
２−２試料液の調製
試料１６ｇに蒸留水８００ｇを加え、１ｍｏｌ／ｌの硝酸でｐＨ７に調製しながら維持して３時間撹拌する。次いで、孔径０．４５μｍのメンブランスフィルターでろ過してろ液を取り、定量に必要な量を正確に計り取って、これをｐＨ７溶出液とする。さらに、ｐＨ７溶出のろ過残渣に蒸留水８００ｇを加え、今度は１ｍｏｌ／ｌの硝酸でｐＨ４に調製しながら維持して３時間撹拌する。次いで、孔径０．４５μｍのメンブランスフィルターでろ過してろ液を取り、これをｐＨ４溶出液とする。
２−３検液の作成
以上の操作を行って得られたｐＨ７溶出液とｐＨ４溶出液とを加え混合して、定量に必要な量を正確に計り取って、これを検液とする。
【０１９６】
▲３▼　アルカリ溶液による溶出試験法［略記：ｐＨ９溶出試験法：］
３−１試料の作成
採取した土壌を風乾し、中小礫、木片等を取り除き、土塊、団粒を粗砕した後、非金属製の２ｍｍの目のふるいを通過させて得た土壌を十分混合する。
３−２試料液の調製
試料１６ｇに蒸留水８００ｇを加え、１ｍｏｌ／ｌの水酸化ナトリウム溶液でｐＨ９に調製しながら維持して３時間撹拌する。次いで、孔径０．４５μｍのメンブランスフィルターでろ過してろ液を取り、これをｐＨ９溶出液とする。
２−３検液の作成
以上の操作を行って得られたｐＨ９溶出液を定量に必要な量を正確に計り取って、これを検液とする。
【０１９７】
各重金属の検出測定方法：
Ｃｄ　　ＪＩＳ　Ｋ　０１０２・１９９８　５５．３　ＩＣＰ発光分光分析法
Ｐｂ　　ＪＩＳ　Ｋ　０１０２・１９９８　５４．３　ＩＣＰ発光分光分析法
Ｃｒ　　ＪＩＳ　Ｋ　０１０２・１９９８　６５．２．１　ＩＣＰジフェニル
カルバジド吸光光度法
Ａｓ　　ＪＩＳ　Ｋ　０１０２・１９９８　６１．２　ＩＣＰ水素化物発生原子吸光光度法
Ｈｇ　　昭和４６年１２月環境庁告示第５９号付表１に掲げる方法
【０１９８】
簡易型の変形性測定試験方法：
本発明による処理土壌が有する変形性を評価するために、「標準貫入試験」に替えて、簡易型の変形性測定試験を採択した。本試験は、基本的にモルタル試験で採択されているＪＳＣＥ　Ｆ　５０６ならびにＪＳＣＥ　Ｇ　５０５の記載に準拠して、本発明の混和物を円柱状試験体（φ５×１０ｃｍ：ｎ＝３）に作成し、密閉状態で７日間常温に放置後、一軸方向の圧縮破壊強度試験で測定し、この時の圧縮破壊強度をＮ／ｃｍ^２単位で測定して表示した。
【０１９９】
【実施例】
本実施例において、重金属類で汚染された土壌に固定化材（Ｓ）を加えて混和物とし、汚染土壌が含有する重金属類を固定化してｐＨ４ないし９の範囲にある水系溶媒に対して不溶性化合物に変質せしめて変形性処理土壌とする重金属類固定化材（Ｓ）と汚染土壌の処理工法に関して具体的例を以って説明する。本発明は、本実施例に限定されるものでない。
【０２００】
［実施例１］
本実施例において、複合組成物（ＰＳ）を構成する各成分［活性シリカ（ＳＳ）、反応性アルミナ（ＳＡ）、水酸化ナトリウム（ＳＮ）、カルシヤ組成物（ＳＣ）、付加補充組成物（ＳＴ）］、ならびに各成分で調製される固定化材（Ｓ）、さらに調製した固定化材（Ｓ）による汚染土壌含有重金属類の固定化ならびに処理土壌の状態を示す変形性について説明する。
【０２０１】
複合組成物（ＰＳ＆ＬＳ）の調製原料となる活性シリカ（ＳＳ）としては、ケイ酸ソーダから製造される微粉末非晶質シリカ［水澤化学工業（株）製：「ミズカシル」］、天然の粘土鉱物であって層状構造のフェロケイ酸塩であるスメクタイト系粘土鉱物で２−八面体型モンモリロナイト族の酸性白土およびＪＩＳ規格品の水ガラス３号［ケイ酸ナトリウム］の３種類を選び、主たる組成成分を表２に併せて表示する。
【０２０２】

【０２０３】
反応性アルミナ（ＳＡ）としては、工業薬品として汎用されている水酸化アルミニウム（Ａｌ_２Ｏ_３：ＳＡ−１）．を選んだ。
また、水酸化ナトリウム（ＳＮ）苛性ソーダ（ＮａＯＨ：ＳＮ−１）を選んだカルシヤ組成物（ＳＣ）としては、市販の試薬、工業薬品、廃棄物類の処理品等の粉末よりを選び、主たる組成成分を表２に併せて表示する。
【０２０４】

【０２０５】
複合組成物（ＰＳ＆ＬＳ）の配合原料となる付加補助組成物（ＳＴ）としては、下記に示す市販の試薬、工業薬品、廃棄物類、合成品の粉末より選んだ。
結晶タネ組成物（ＳＴ１）としては、工業薬品のアルミノケイ酸塩でＡｌ／Ｓｉ原子比が４．２で環員数８で２次粒径が２０μ以下の４Ａ型粉末を選んだ。
【０２０６】
硫酸根組成物（ＳＴ２）としては、市販の試薬ならびに工業薬品より硫酸ナトリウム、硫酸鉄、硫酸アルミニウムならびにカリ明礬を選んだ。燐酸根組成物（ＳＴ３）としてリン酸ケイ素　［ＳｉＯ_２：：Ｐ_２Ｏ_５モル比＝３．０：１．０９５０℃焼成・粉砕品］、リン酸ソーダ、リン酸亜鉛ならびにリン酸塩スラッジ［主成分（質量％）：リン酸鉄２５．０リン酸亜鉛７．５シリカ１０．５アルミナ８．４水分３５．０］を選んだ。
バリウム塩組成物（ＳＴ４）としては、簡易反応型で調製したケイ酸バリウム［ＢａＯ：ＳｉＯ_２：モル比＝１．０：１．０　２５０℃反応・粉砕品］、ならびに水酸化バリウムを選んだ。
【０２０７】
鉄塩補充組成物（ＳＴ５）としては酸化鉄（ＩＩ）を選んだ。担持補助組成物（ＳＴ６）としては、吸着性を有するシリカゲル、アルミゲルならびに炭−ケイ酸アルミニウム複合物［主成分（質量％）：Ｃ：２５．５　ＳｉＯ_２３５．６　Ａｌ_２Ｏ_３２７．５　ＣａＯ　１１．４］を選んだ。
選んだ付加補助組成物（ＳＴ）の主たる化学組成を表４に併せ表示する。
【０２０８】

【０２０９】
本実施例固定化材（Ｓ）は、上記の活性シリカ（ＳＳ）、反応性アルミナ（ＳＡ）、水酸化ナトリウム（ＳＮ）、カルシヤ組成物（ＳＣ）および付加補助組成物（ＳＴ）の中から表５に示す種類ならびに量割合で均質混和し、必須四成分ないしは五成分でワンパック粉末状複合組成物（ＰＳ）を調製して供試料とした。
【０２１０】

【０２１１】
本実施例で採択した汚染土壌は、工場跡地にあった土壌Ａならびに土壌Ｂの２種類を選んだ。土壌Ａならびに土壌Ｂの含有水分と主成分（乾燥物基準）、ならびに汚染重金属類の含有量を表６に示す。なお、本実施例では、汚染土壌に共存している浹雑物（木切れ、草木、砂、礫等）は分級除去した精製汚染土壌を供試料とした。
【０２１２】

【０２１３】
本発明の固定化処理工程において、混和物の調製に採択する混和装置としては、事前混和方式であるビーター型撹拌機（回転数：２０５ｒ．ｐ．ｍ．）が具備されたステンレス製２０ｌ容器を本体とするモルタルミキサー［愛工舎製作所製：マイティ３０（形式ＭＴ−３０／２０）］を選んだ。
【０２１４】
本実施例における混和物は、モルタルミキサー容器に汚染土壌４ｋｇを移動投入し、次いで汚染土壌を投入したモルタルミキサー容器に表５に示す粉末固定化材（Ｓ）の中から試料番号Ｓ−１の固定化材（Ｓ）１ｋｇと水１ｋｇを２段階で加える場合と、試料番号Ｓ−１の固定化材（Ｓ）１ｋｇと水１ｋｇで予めスラリー状に調製して１段で加える場合の二方式でそれぞれ添加配合し、６０秒間撹拌して表７に示す可塑性混和物を調製した。
【０２１５】
ここで調製した可塑性混和物を密封した容器に採り、２４時間常温にてそれぞれ放置養生して表７に示す４種類の処理土壌とする。
調製した４種類の処理土壌をｐＨ４溶出試験、ｐＨ７溶出試験ならびにｐＨ９溶出試験に付して含有重金属類の固定化状況を評価した。また、簡易型変形性測定試験に付して、処理土壌の外圧に対する変形性を評価した。その結果を表８に併せ表示する。
【０２１６】

【０２１７】
本発明の比較例として、本発明固定化材（Ｓ）に替えて汎用されているポルトランドセメントを表７に示す処理条件と同じ条件で処理土壌とした場合を比較例とした。また、本発明固定化材（Ｓ）を加えない無処理の汚染土壌土も比較例とした。各比較例の土壌を各溶出試験に付して、本発明との比較評価を行った。その結果を表８に併せ表示する。
【０２１８】

【０２１９】
なお、参考までに、本実施例で実施した重金属類［カドミ（Ｃｄ）、鉛（Ｐｂ）、六価クロム（Ｃｒ）、砒素（Ａｓ）、総水銀（Ｔ−Ｈｇ）］の溶出試験における分析定量下限界値ならびに環境省より示されている環境基準値を参考までに表９に併せて示す。
【０２２０】

【０２２１】
以上の結果、無処理の土壌ならびにセメントを固定化材とした処理土壌と比較して、本発明による固定化材（Ｓ）により汚染土壌を固定化処理した処理土壌は、硝酸で調製されたｐＨ４の溶液での溶出試験でも、中性ｐＨ７水での溶出試験でも、またアルカリの溶出試験でも、含有重金属類、特にクロムも固定化されて溶出せず、しかも処理土壌が外圧に対して変形性を有していることが良く理解される。
【０２２２】
［実施例２］
本実施例において、実施例１の表５に示した固定化材（Ｓ）を採択して、事前混和方式による混和装置により、汚染土壌を含有重金属類の固定化処理に付した時の重金属類の固定化状況と処理土壌の変形性について説明する。
【０２２３】
固定化処理工程は、実施例１に示した事前混和方式であるモルタルミキサー混和装置［マイティ３０（形式ＭＴ−３０／２０）］を選んだ。
本実施例における混和物は、モルタルミキサー容器に実施例１に示した汚染土壌である土壌Ａもしくは土壌Ｂと実施例１の表５に示した固定化材（Ｓ）と水を表１０に示す量割合で移動投入し、次いで６０秒間撹拌して可塑性混和物を調製した。
【０２２４】

【０２２５】
ここで調製した可塑性混和物を密封した容器に採り、２４時間常温にてそれぞれ放置養生して処理土壌とする。
調製した処理土壌をｐＨ４溶出試験、ｐＨ７溶出試験ならびにｐＨ９溶出試験に付して含有重金属類の固定化状況を評価した。また、簡易型変形性測定試験に付して、処理土壌の外圧に対する変形性を評価した。その結果を表１０に併せ表示する。
【０２２６】
以上の結果、本実施例に示した各種の固定化材（Ｓ）を用いて、事前混和方式による混和装置により本発明の固定化処理を施した処理土壌は、ｐＨ４、ｐＨ７、ｐＨ９の各溶出試験において含有重金属類を不溶出化合物として固定化されており、また処理土壌が外圧に対して変形性を有している土壌に変質されていることがよく理解される。
【０２２７】
［実施例３］
本実施例において、実施例１の表５に示した各種固定化材（Ｓ）を採択して、事前混和方式による混和装置により固定化処理工程に付し、含有重金属類を固定化した処理土壌との処理土壌の変形性について説明する。
【０２２８】
固定化処理工程は、実施例１に示した事前混和方式であるモルタルミキサー混和装置［マイティ３０（形式ＭＴ−３０／２０）］を選んだ。
本実施例における混和物は、モルタルミキサー容器に実施例１に示した汚染土壌である土壌Ｂと実施例１の表５に示した固定化材（Ｓ）と水を表１１に示す量割合で移動投入し、次いで６０秒間撹拌して各可塑性混和物を調製した。
【０２２９】
ここで調製した可塑性混和物を密封した容器に採り、２４時間常温にてそれぞれ放置養生して処理土壌とする。調製した処理土壌をｐＨ４溶出試験、ｐＨ７溶出試験ならびにｐＨ９溶出試験に付して含有重金属類の固定化状況を評価した。また、簡易型変形性測定試験に付して、処理土壌の外圧に対する変形性を評価した。その結果を表１１に併せ表示する。
【０２３０】

【０２３１】

【０２３２】
以上の結果、本実施例に示した各種の固定化材（Ｓ）を用いて、事前混和方式による混和装置により本発明の固定化処理を施した処理土壌は、ｐＨ４、ｐＨ７、ｐＨ９の各溶出試験において含有重金属類を不溶出化合物として固定化されており、また処理土壌が外圧に対して変形性を有している土壌に変質されていることがよく理解される。
【０２３３】
［実施例４］
本実施例において、汚染土壌原位置において、掘削撹拌方式、機械撹拌方式ならびに高圧噴射方式による混和装置により、汚染土壌に対して実施例１で示した固定化材（Ｓ）を加えて本発明の混和処理工程に付し、重金属類の固定化状況と処理土壌の変形性について説明する。
【０２３４】
本実施例における掘削撹拌方式、機械撹拌方式ならびに高圧噴射方式により重金属類の固定化処理した原位置（深度約２ｍ）における汚染土壌Ｃの含有重金属類を表１２に示す。

【０２３５】
掘削撹拌方式装置としては、スタビライザー式の採掘型で撹拌可能な装置［東洋スタビ工事（株）製：ＴＯＹＯ　ＳＲＡＢＩ］により、汚染土壌Ｃ原位置において深さ約１ｍの深さまでを掘削撹拌式にて土粒子と表１３に示すスラルー状の固定化材（Ｓ）を原位置において撹拌混合して、ついで２４時間放置養生した後、混和処理された混和処理物をボーリング方式により採取したし試験体として密封した容器に採り処理土壌の試料とした。
【０２３６】
機械撹拌方式装置としては、三点式パイルドライバーで定格出力１８０ｐｓ／２１００ｒｐｍ、オーガのモータ出力が７５ｋｗクラスであるＮＡＳ１００形式のオーガパイルドライバーにより、汚染土壌Ｃ原位置において深さ約１ｍ以上の原位置土壌に機械撹拌式にて土粒子と表１３に示すスラルー状の固定化材（Ｓ）を撹拌混合して、ついで原位置において２４時間放置養生した後、混和処理された混和処理物をボーリング方式により採取したし試験体として密封した容器に採り処理土壌の試料とする。
【０２３７】
高圧噴射方式装置としては、ＣＣＰ−Ｌ工法として汎用されている回転ノズルより高圧噴射し、地盤深層部の有効径φ３００ないしは５００の範囲で均質接触せしめる高圧プランジャー一式で馬力７．５ＫＷを有するグラフト噴射方式により、汚染土壌Ｃ原位置において深さ約１ｍ以上の原位置土壌に高圧噴射式にて土粒子と表１３に示すスラルー状の固定化材（Ｓ）を撹拌混合して、ついで原位置において２４時間放置養生した後、混和処理された混和処理物をボーリング方式により採取したし試験体として密封した容器に採り処理土壌の試料とする。
【０２３８】
さらに、粉体噴射撹拌工法を可能とする高圧噴射方式装置としては、ＤＪＭ工法として汎用されている固定化材（Ｓ）を空気流により地盤深層部への搬送を可能とする、撹拌軸数２本、標準撹拌翼径１，０００ｍｍ、原動機出力９０ｋｗ×２台仕様を有する粉体高圧噴射式により、汚染土壌Ｃ原位置において深さ約１ｍ以上の原位置土壌に高圧噴射式にて土粒子と表１３に示す粉末状の固定化材（Ｓ）を撹拌混合して、ついで原位置において２４時間放置養生した後、混和処理された混和処理物をボーリング方式により採取したし試験体として密封した容器に採り処理土壌の試料とする。
【０２３９】
本実施例により、それぞれ掘削撹拌方式、機械撹拌方式ならびに高圧噴射方式による混和装置により処理された処理土壌をそれぞれボーリング採取して試験体とし、ｐＨ４溶出試験、ｐＨ７溶出試験ならびにｐＨ９溶出試験に付して含有重金属類の固定化状況を評価した。また、簡易型変形性測定試験に付して、外圧に対する変形性を評価した。その結果を表１３に併せ表示する
【０２４０】

【０２４１】
以上の結果、本発明の固定化材（Ｓ）をスラリー状ないしは粉末状で原位置の汚染土壌に対して、それぞれ掘削撹拌方式、機械撹拌方式ならびに高圧噴射方式による混和装置により混和処理された処理土壌はｐＨ４溶出試験、ｐＨ７溶出試験ならびにｐＨ９溶出試験において含有重金属類を不溶出化合物として固定化されており、また処理土壌が外圧に対して変形性を有している土壌に変質されていることがよく理解される。
【０２４２】
【発明の効果】
本発明の効果は、汚染土壌が含有する有害な重金属類をｐＨ４ないし９の範囲にある水系溶媒に対して不溶性化合物にして固定化し、しかも変形性を示す処理土壌として変質せしめることにより、生物生態系や人の健康に影響を及ぼす有害重金属類が地下水脈や河川・海域に流失し、広域な生活環境に二次汚染している実態を防止して環境問題を解消できるのみならず、土地の有効活用に貢献することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating heavy metals and contaminated soil; more particularly, the method in which the fixing material (S) has activated silica (SS) having silanol groups, reactive alumina (SA), and water. An immobilizing material comprising a powdery one-pack composite composition (PS) in which sodium oxide (SN), a calcium composition (SC), and, if necessary, a powder addition auxiliary composition (ST) are homogeneously mixed. (S), the immobilizing material (S) and water are added to the contaminated soil to form a mixture using a miscible device, and then the heavy metals contained in the pH range of 4 to 9 are obtained by the immobilization step of providing reaction and curing conditions. The present invention relates to a method for treating contaminated soil that has been modified as a treated soil that is immobilized with an insoluble compound in an aqueous solvent and exhibits deformability.
[0002]
[Prior art]
Currently, in order to protect the environment and ensure a healthy and comfortable living environment, heavy metals such as lead, which have an adverse effect on human health, and harmful substances such as dioxins and environmental hormones, harm the soil, water systems, and the atmosphere. There is a strong demand for remediation, restoration, and conservation of the natural environment by resolving the current pollution situation. Under these circumstances, establishing technologies to repair, regenerate, and preserve soil contaminated with harmful substances is important from the standpoint of not only solving environmental problems but also effectively using land.
[0003]
Harmful heavy metals (lead, chromium, cadmium, arsenic, mercury, etc.) contaminating the soil are highly soluble in water, especially on the acidic side, and dissolve and elute in rain, especially in acid rain. Harmful heavy metals are being washed away into groundwater veins, rivers and seas, causing pollution to spread to a wide range of living environments. The effects of these harmful substances on biological ecosystems are unavoidable, causing many adverse effects on the living environment, and urgent countermeasures are required.
[0004]
The Soil Contamination Countermeasures Law has been enacted (May 22, 2002) as one method for promoting measures to improve and remediate contaminated soil in order to prevent the spread of such harmful substances. Therefore, when constructing an apartment or the like on the site of a factory in the future, investigate the soil, and if the soil is contaminated with harmful substances, ask the land owner to remove / improve the harmful pollutants and take measures to prevent their spread. Have been.
[0005]
Measures to eliminate contaminated soil, which is subject to laws and regulations, are important in terms of land evaluation and land use. However, the restoration and regeneration of contaminated soil requires an enormous amount of treatment.Therefore, unless it is a low-cost restoration and regeneration method, there is no economic significance from the viewpoint of land use, and it is economical and safe. There is a demand for the establishment of a technology for a rehabilitation and regeneration method.
[0006]
However, at present, some methods have been implemented to replace contaminated soil with fresh soil in order to repair and regenerate contaminated soil areas. However, in this method, the contaminated soil taken out is a contaminated waste, and there is a risk that the contaminated soil that has been taken out will cause new pollution diffusion unless it is specifically managed. Therefore, this method does not solve the comprehensive environmental problem, but rather brings a risk of newly contaminating heavy metals into the non-polluted area.
[0007]
Furthermore, a method has been proposed in which the contaminated soil is washed with water and repaired / regenerated. However, because of the enormous amount of processing, the amount of work required for cleaning processing and the necessary processing equipment brought to the site, and the amount of water required, the enormous cost associated with cleaning processing is economical. Absent.
[0008]
Moreover, in this case as well, the harmful heavy metals transferred to the water required for the cleaning treatment must be treated as wastewater, which requires an enormous treatment cost. Also, discharging treated water to rivers and seas as it is is the diffusion of pollutants, and has not contributed to solving the comprehensive environmental problem.
[0009]
Furthermore, as a technology for rendering the contained heavy metals insoluble in water, an alkali component (lime or cement) or sulfide is added to transform ionic heavy metals that elute from water into hardly soluble hydroxides or sulfides. There is also technology. However, even if heavy metals are hardly soluble in water as hydroxides or sulfides, they will dissolve under a little acidic condition, for example, acid rain at pH 4, and are safely stable in the current natural phenomenon, acid rain. There is no perfection as a technique for immobilizing heavy metals as insoluble compounds.
[0010]
It is also conceivable to select Portland cement or the like as a material for covering and covering heavy metals. However, even after wrapping heavy metals with Portland cement, the wrapped Portland cement does not have acid resistance [see Example], and furthermore, the fact that Portland cement itself contains chromium, which is a harmful heavy metal, further increases the amount of soil in the soil. There is a tendency to increase harmful heavy metal chromium, which is not environmentally friendly.
[0011]
Moreover, the soil treated with cement hardens and solidifies after the treatment, and it is difficult to treat the concrete ground as general soil ground when trying to make effective use of the treated land. There is a tendency to make civil and construction work difficult and to limit the use of treated soil ground.
[0012]
Further, as a material for immobilizing heavy metals, there is also a chelating material for encapsulation. However, the chelate compound produced by the treatment with the chelating agent is easily decomposed when exposed to conditions such as natural light, heat, and acid rain for a long period of time, has no stability, and can chelate heavy metals to be safe for a long time. It is difficult to secure as a compound.
[0013]
Furthermore, a technology that mixes iron powder with a reducing function into contaminated soil to expect the effect of reducing and decomposing organic substances contained therein and to reduce the contained harmful heavy metals into water-insoluble compounds by the action of reducing harmful heavy metals. Are also disclosed. However, the immobilization of heavy metals by the iron powder treatment method does not show stable stability with respect to a solution on the acidic side at pH 4 assuming acid rain.
[0014]
In addition, as a material for immobilizing heavy metals contained in incinerated ash and sludge of industrial waste, a treatment material containing cement as a main component and a hydrogen phosphate compound, fly ash, gypsum, bentonite, allophane, etc. (JP-A-5-309354, JP-A-6-328063, JP-A-7-39847, JP-A-7-60221, JP-A-7-185499, etc.) have been proposed. However, heavy metals such as incineration ash and sludge treated with these proposed treatment materials are immobilized. However, in a dissolution test by the Environment Agency No. 46, for example, the lead content was at least 0.1 mg / l. The standard of 0.01 mg / l was not cleared.
[0015]
In addition, a treatment material composed of cement and a hydrogen phosphate compound as the main component is adopted to treat heavy metals contained in incineration ash and sludge, etc. There is no disclosure of the conditions that result in an insoluble compound. Much more
There is no disclosure of conditions or specific examples in which zeolites are formed from a hydrogen phosphate compound or the like with cement as a main component to fix heavy metals.
[0016]
Furthermore, at the “Research Meeting on Groundwater and Soil Pollution and Its Prevention Measures” held on June 26, 2002, as a measure to prevent and regenerate contaminated soil, a special symposium was held. Even in research presentations and the like, no technology has been disclosed in which the contaminated soil is stably fixed at a low price at a pH of 4 solution assuming acid rain.
[0017]
The present inventors, when adding a composite composition containing silica, alumina, alkali, calcium and the like as a main component to a heavy metal-containing material such as incineration ash and fly ash, and reacting and curing under normal temperature conditions, the heavy metal Patent applications (Japanese Patent Application Laid-Open No. Hei 11-246261, Japanese Patent Application No. 2000-351931, Japanese Patent Application No. 2001-083816, Japanese Patent Application No. 2001-2001) are examples in which the contained heavy metals are fixed in a water-insoluble manner while the contained material forms a hardened / solidified body. 234183).
[0018]
However, in these invention technologies, the main function of the composite composition containing silanol group-containing silica as a main component is a function of forming a solidified body having strength, and accompanying the function of forming a hardened / solidified body. It discloses a function of immobilizing heavy metals. However, when the heavy metals in the contaminated soil are fixed, it is not preferable that the treated soil hardens and solidifies and is converted into concrete from the viewpoint of using the treated soil as land and ground.
[0019]
In the application patent disclosed by the present inventors, a composite composition containing silica or the like as a main component is added to a silicate material contaminated with heavy metals and the like, and the silicate material is cured and cured. It does not disclose specific contents, conditions, methods, construction methods, and the like of the silicate-based treated soil that is fixed without fixing the heavy metals contained therein and is deformable.
[0020]
Furthermore, ionic heavy metals are not merely adsorbed, but are immobilized as zeolite crystals, and the immobilized compound withstands acid rain at pH 4 to immobilize heavy metals. No specific conditions, methods, construction methods, etc. for exhibiting a function that is stable and can be secured safely for a long period of time are not disclosed.
[0021]
In the prior art, as a technique for improving the soil ground by bringing a powder or slurry of a functional material such as a solidified body into contact with the soil, various techniques have been disclosed and implemented as a method of improving the soil ground such as soft ground. Have been. Among them, in response to the physical improvement, a quick lime pile method, a deep mixing method, a chemical liquid injection method, a powder injection stirring method, and the like have been implemented as a chemical method (consolidation method).
[0022]
However, in the prior art, an immobilizing material specified for contaminated soil and ground is added, and an appropriate method for immobilizing heavy metals as a plastic or fluid admixture in order to make the contaminated soil an environmentally safe deformable treated soil. There is no disclosure of a technique for making the contained heavy metals insoluble in an aqueous solvent having a pH of 4 to 9 by specifically showing the selection of an appropriate apparatus, treatment conditions, the state of immobilization of heavy metals in the treated soil that has been altered, and the like.
[0023]
Moreover, in order to effectively utilize the soil ground contaminated with harmful heavy metals, large-volume contaminated soil ground can be repaired inexpensively using a simple construction method at room temperature without using special expensive equipment.・ Technology to regenerate is required. However, a technique that satisfies the above conditions has not been disclosed yet. Furthermore, there is no disclosure of a technique for immobilizing heavy metals without diffusing them into groundwater veins, rivers, and sea areas under actual weather conditions in which acidic rain of pH 4 falls.
[0024]
[Problems to be solved by the invention]
The problem to be solved by the present invention is that when a solution showing pH 4 to 9 including acid rain falls on soil contaminated with heavy metals artificially on the site of a factory or the like, heavy metals dissolve and groundwater veins and It is secondarily eluted into rivers and sea areas, and harmful heavy metals are diffused into a wide area environment, which significantly affects the biological ecosystem and human health.
[0025]
In order to solve these problems, ionic heavy metals that affect the biological ecosystem and human health are stable for a long time even when exposed to a solution showing pH 4 or 9 where acid rain is expected at the site of normal temperature. A technique for transforming into an immobilized compound which does not elute has not yet been established.
[0026]
Even if the heavy metals contained were immobilized by at least a water-insoluble compound or coating treatment, the treated soil could not be repaired or regenerated as easy-to-use soil ground that was easy to reuse, and concrete was converted. No alteration of the treated soil, which is deformable to light external pressure, has been attempted.
[0027]
Moreover, the current treatment method for safely repairing, regenerating, and reforming contaminated soil requires enormous costs. For example, the replacement and post-management of contaminated soil requires enormous expenses even if it is replaced with fresh, non-polluting soil. The conversion process requires enormous costs.
[0028]
Therefore, the established technology is a technology that repairs and regenerates contaminated soil by simple and inexpensive construction and construction methods without adopting expensive materials, equipment and processes, and without consuming much energy. It is important that there is. In particular, from the standpoint of effective reuse of contaminated soil, it is important that the treatment method be economical to repair and regenerate the contaminated soil at the site where the pollution occurs without wasting the contaminated soil.
[0029]
Moreover, it is important from the standpoint of the reuse of the treated soil that the treated soil has been transformed into a general soil ground that allows easy deformation under external pressure without being converted into concrete. When treating contaminated soil using a solidifying material such as cement, it seems that the treated soil hardens and solidifies and tends to hinder the effective use of the treated soil ground. It is important that it be repaired and regenerated.
[0030]
[Object of the invention]
An object of the present invention is to fix a contaminated soil containing harmful heavy metals to a treatment sympathy that is stably immobilized even when exposed to a solution exhibiting a pH of 4 to 9 expected by acid rain. This is a treated soil that shows deformability without the hardening and solidification of the soil treated with the chemical material (S). The contaminated soil is repaired and regenerated to reduce the secondary diffusion and pollution of harmful heavy metals to the environment. It is an object of the present invention to provide a heavy metal fixing material (S) and a method for treating contaminated soil, which can prevent the soil and make effective use of land.
[0031]
[Means for solving the problem]
According to the present invention, the heavy metal-containing contaminated soil is subjected to an immobilization treatment step, and the heavy metal of the treated soil is immobilized as an insoluble compound that does not elute in an aqueous solvent having a pH of 4 to 9, In the heavy metal-fixing material (S), in which the treated soil is deformable against external pressure;
[0032]
The above fixing material (S) is 50 to 200 parts by mass of reactive alumina (SA) and 15 to 80 parts by mass of sodium hydroxide (SN) based on 100 parts by mass of active silica (SS) having a silanol group. Powder and one-pack composite composition (PS) in which the essential four components are added in an amount of from 20 to 300 parts by weight, and 20 parts to 300 parts by weight of the calcium carbonate composition (SC);
[0033]
In the immobilization treatment step, 5 to 30 parts by mass of the immobilizing material (S) and 10 to 140 parts by mass of water are homogeneously mixed with 100 parts by mass of the contaminated soil on a dry matter basis. Forming a plastic or fluid admixture which is formed and then leaving the admixture at 2 to 40 ° C. for at least 24 hours to obtain treated soil;
[0034]
By the above-mentioned immobilization treatment step, the heavy metals contained in the contaminated soil are immobilized as zeolites, which are basic salt compounds of aluminosilicic acid, to be transformed into a treated soil that is not eluted in an aqueous solvent having a pH in the range of 4 to 9. A heavy metal-fixing material is provided, which is a fixing material (S) in which treated soil at the time is soil exhibiting deformability due to external pressure.
[0035]
According to the present invention, in the activated silica (SS) having a silanol group, which is a component of the immobilizing material (S);
The activated silica (SS) is replaced with silica (SiO₂) As a main component, an amorphous silicic acid (SS1), an alkali silicate (SS2), a layered clay mineral of ferrosilicate (SS3) having an aluminum silicate as a main skeleton, and hydroxylation of silicic acid or silicate The present invention provides a heavy metal-fixing material composed of one or a combination of two or more selected from the group of alkali-modified silicates (SS4) having a silanol group by reacting sodium.
[0036]
According to the present invention, in the activated silica (SS) having a silanol group, which is a component of the immobilizing material (S);
The above-mentioned reactive alumina (SA) is a heavy metal-fixing material composed of one or a combination of two or more selected from the group consisting of aluminum oxide, aluminum hydroxide, sodium aluminate and alkaline earth metal aluminate. Provided.
[0037]
According to the present invention, in the calcium composition (SC) which is a component of the immobilizing material (S);
The above-mentioned Calcia composition (SC) is a Calcia standard composition (SC1), an oxyacid salt composition (SC2), a halogen salt composition (SC3), a waste powder composition (SC4), and a cement powder composition. (SC5), an alkali-modified composition (SC6) and a heavy metal-immobilizing material comprising a single or a combination of two or more selected from the group consisting of carbonic acid-modified composition (SC7).
[0038]
According to the present invention, the immobilizing material (S) is homogeneously mixed with the essential four components, and the homogenous mixture with the five components to which the additional auxiliary composition (ST) is further added. In the powdered one-pack composite composition (PS) being prepared;
[0039]
The powder addition auxiliary composition (ST) is composed of a crystal seed composition (ST1), a sulfate group composition (ST2), a phosphate group composition (ST3), a barium salt composition (ST4), and an iron salt replenishing composition (ST). ST5), a powder composition which is composed of one or a combination of two or more selected from the group consisting of the supporting auxiliary composition (ST6) and the dispersion medium composition (ST7) and exerts an auxiliary function;
[0040]
The above-mentioned immobilizing material (S) is added in an amount of 1 to 200 parts by mass with the addition auxiliary composition (ST) to 100 parts by mass of the composite composition (PS) in which the essential four components are homogeneously mixed. There is provided a heavy metal-immobilizing material comprising a five-component powdered one-pack composite composition (PS) which is intimately mixed.
[0041]
According to the present invention, in a one-pack composite composition (PS), wherein the immobilizing material (S) is homogeneously mixed with four essential components and five additional auxiliary compositions (ST);
The above-mentioned powdery one-pack composite composition (PS) contains 50 to 100 parts by mass of reactive alumina (SA) as sodium aluminate with respect to 100 parts by mass of active silica (SS) as sodium silicate in each powder. , A powdery one-pack composite in which 20 to 80 parts by weight of calcium silicate (SC) and 25 to 75 parts by weight of a natural zeolite crystalline seed composition (ST1) are homogeneously mixed. A heavy metal-fixing material comprising the composition (PS) is provided.
[0042]
According to the present invention, in a one-pack composite composition (PS), wherein the immobilizing material (S) is homogeneously mixed with four essential components and five additional auxiliary compositions (ST);
The powdery one-pack composite composition (PS) is prepared by adding 50 to 100 parts by mass of reactive alumina (SA), which is aluminum hydroxide, to 100 parts by mass of active silica (SS), which is the acid clay of each powder. , 15 to 80 parts by weight of sodium hydroxide (SN), 20 to 80 parts by weight of calcium composition (SC) as blast furnace slug and 25 to 75 parts by weight of crystalline seed composition (ST1) as natural zeolite. The present invention provides a heavy metal-immobilizing material composed of a powdery one-pack composite composition (PS) which is homogeneously mixed with the above.
[0043]
According to the present invention, the above-mentioned heavy metal-fixing material (S) is prepared in advance as a homogeneous slurry by adding water to the essential four-component or five-component powdery composite composition (PS). In the composite composition (LS);
A slurry composite composition which is previously prepared into a homogeneous slurry by adding water in an amount of 60 to 120 parts by mass with respect to 100 parts by mass of the powdery composite composition (PS) of the essential four or five components. There is provided a heavy metal immobilizing material composed of an object (LS).
[0044]
According to the present invention, an immobilization process in which the heavy metal-immobilizing material (S) is subjected to a mixing device that makes uniform contact with the contaminated soil via water as a plastic or fluid admixture and then reacted and cured. In the method for treating contaminated soil, the heavy metals contained therein are immobilized on an insoluble compound to give a deformable treated soil;
[0045]
The above-described mixing device is a mixing device of a pre-mixing method mainly including a container including a rotary driving body having a stirring blade;
The above-mentioned pre-mixing method is to transfer the mined contaminated soil to a mixing device, and furthermore, add and fix a predetermined amount of the immobilizing material (S) and, if necessary, water, and stir and mix the plastic or fluid. A method of forming a sex admixture;
[0046]
The method for treating contaminated soil described above immobilizes heavy metals contained as zeolites, which are basic salt compounds of aluminosilicate, and immobilizes them on compounds insoluble in aqueous solvents in the pH range of 4 to 9 to improve deformability. A method for treating contaminated soil, which is a method for treating soil as shown, is provided.
[0047]
According to the present invention, in the plastic admixture formed by stirring and mixing the contaminated soil, the fixing material (S), and water with the premixing device,
The above-mentioned plastic admixture is stirred and mixed in an amount ratio of 5 to 30 parts by mass of the immobilizing material (S) and water to less than 60 parts by mass with respect to 100 parts by mass of the contaminated soil containing heavy metals on a dry matter basis. Then, there is provided a method for treating contaminated soil, which is a method for treating a contaminated soil which is granulated into granules of 0.5 to 35 mmφ, dried if necessary, and transformed into deformable treated soil.
[0048]
According to the present invention, in the fluid admixture formed by mixing and mixing the contaminated soil, the immobilizing material (S), and water with the premixing-type mixing device described above;
The above-mentioned fluid mixture is stirred at a ratio of 5 to 30 parts by mass of the immobilizing material (S) and 60 to 140 parts by mass of water with respect to 100 parts by mass of the contaminated soil containing heavy metals on a dry matter basis. A method is provided for treating contaminated soil that has been mixed and then moved to the excavated site or elsewhere using fluidity to transform into deformable treated soil.
[0049]
According to the present invention, the mixing device is a device of an excavation stirring type capable of moving the target ground;
The above-mentioned excavation and agitation method adds a predetermined amount of immobilizing material (S) and water as needed to contaminated soil on the in-situ surface layer that is less than 1 m from the ground surface, and agitates and mixes while excavating soil. To form a plastic or flowable admixture;
A method for treating contaminated soil, which is a treatment method in which the above-mentioned plastic or fluid admixture is transformed into deformable treated soil, is provided.
[0050]
According to the present invention, the mixing device is a device of a mechanical stirring type centering on a deep part of a target ground;
The above-mentioned mechanical stirring method forms a plastic or fluid admixture by making the slurry-like fixing material (S) penetrate into the deeply contaminated soil at a depth of 1 m or more from the ground surface and mechanically stirring and mixing. Method;
A method for treating contaminated soil, which is a treatment method in which the above-mentioned plastic or fluid admixture is transformed into deformable treated soil, is provided.
[0051]
According to the present invention, the mixing device is a high-pressure injection type device centered on a deep part of the target ground;
The above-mentioned high-pressure injection method is a method of forming a plastic or fluid admixture by injecting a high-pressure slurry-type immobilizing material (S) into deep contaminated soil at a depth of 1 m or more from the ground surface and mixing with stirring. Yes;
A method for treating contaminated soil, which is a treatment method in which the above-mentioned plastic or fluid mixture is transformed into deformable treated soil, is provided.
[0052]
According to the present invention, the above-mentioned high-pressure injection type apparatus injects the powdered immobilizing material (S) toward the contaminated soil at a depth of 1 m or more from the ground surface using compressed air as a moving medium, and stirs and mixes. In addition, there is provided a method for treating contaminated soil, which is a device for discharging air sent to a deep part to the ground.
[0053]
According to the present invention, in the above-mentioned contaminated soil, in a composite contaminated soil contaminated with organic substances in addition to heavy metals;
There is provided a method for treating contaminated soil, which is a pre-treated contaminated soil in which the above-mentioned complex contaminated soil is preliminarily decomposed and removed by heating an organic substance contained therein.
[0054]
According to the present invention, in the deformable treated soil in which the treated soil is fixed to heavy metals as zeolites and transformed into an insoluble compound in an aqueous solvent having a pH of 4 to 9;
The above deformable soil was subjected to a simple type deformability measurement test, and the strength value was 80 N / cm.²The present invention provides a method for treating contaminated soil that has been transformed into a treated soil exhibiting the following deformability due to external pressure.
[0055]
BEST MODE FOR CARRYING OUT THE INVENTION
[Contaminated soil for control]
The contaminated soil to be controlled in the present invention refers to a soil contaminated by cadmium, lead, hexavalent chromium, arsenic and five heavy metals of total mercury in excess of environmental standards. In addition, copper, selenium, fluorine, and boron are listed as other elemental components that are subject to environmental standards, but are not included in the present invention for the time being. However, the immobilizing material (S) of the present invention and the processing method form an insoluble compound with respect to these element components, and it is determined that the effect of immobilizing these elements is exhibited as in the present invention. .
[0056]
As environmental standards for soil pollution, Article 9 of the Basic Law on Pollution Control has declared environmental standards for soil pollution, and Article 16 of the Basic Environmental Law states that " The following are the standards that are desirable to protect and preserve the living environment (hereinafter referred to as “environmental standards”) and their achievement periods are as follows. ” 1].
[0057]

[0058]
Contaminated soils are classified into two categories: heavy metals, etc. (including cyanide, PCB, and pesticides) and volatile organic compounds, which are environmental standards in the "Operation Standards for Surveys and Countermeasures for Soil and Groundwater Pollution". . Therefore, although partly exceptional, they are classified based on non-volatility and volatility, and are distinguished in investigations and countermeasures.
[0059]
The present invention is intended for the ground and soil contaminated with heavy metals. However, the technology of the present invention is based on the incineration ash of waste, which is a material contaminated with heavy metals mainly composed of silicate, fly ash discharged from thermal power plants, sea, rivers, swamps, lakes, It is also possible to immobilize heavy metals and insolubilize heavy sludge deposited on dams and the like.
[0060]
[Immobilization material (S)]
The immobilizing material (S) adopted in the present invention includes activated silica (SS) having a silanol group, reactive alumina (SA), sodium hydroxide (SN), and calcium hydroxide composition (SC). It is prepared as a powdery composite composition (PS) having a five-component composition including a powdery composite composition (PS) having a component composition and a supplementary auxiliary composition (ST) WP. Further, the immobilizing material (S) is prepared as a slurry-like composite composition (LS) which is prepared in advance by adding water to a powdery composite composition (PS) having an essential four-component composition and a five-component composition. ing.
[0061]
As the activated silica (SS) having a silanol group of the present invention, silica (SiO)₂) As the main components, such as amorphous silicic acid (SS1), alkali silicate (SS2), and ferrosilicate layered clay mineral (SS3) having aluminum silicate as a main skeleton. A silica-alumina composite composition (SS4) such as sludge cake as a component, and an alkali-modified silicate (SS5) having silanol groups by reacting silicic acid and silicate with an alkali such as sodium hydroxide. ).
[0062]
As the amorphous silicic acid of activated silica (SS), hydrogel-like amorphous silicic acid can be preferably exemplified. Generally, amorphous silicic acid is prepared by neutralizing an alkali silicate or the like with an acid to remove alkali. Further, amorphous silicic acid prepared in a step of partially pulverizing fused silica mechanochemically can also be adopted in the present invention.
[0063]
The alkali silicate of the activated silica (SS) is represented by the following composition formula (1)
M¹ ₂O ・ aSiO₂・ WH₂O ……… (1)
(Where: M¹Is an alkali metal element, a is a number of 20 or less including zero, and w is a number of 1,6 or 50.0 or less.) A single or two or more selected from the group of powdery or liquid alkali silicates represented by Alkali silicates composed of the above combinations can be suitably mentioned.
[0064]
As the alkali metal M in the alkali silicate, sodium (Na) is preferable because it is generally easily available and inexpensive. However, depending on the purpose and use of the immobilizing material (S) and the workability, a composite silicate in which potassium or lithium is used alone or in combination with sodium can be used as the alkali metal. Among them, sodium silicate is industrially mass-produced in accordance with JIS as a water glass, is inexpensive, and can be suitably adopted.
[0065]
Moreover, sodium silicate coexists with a sodium component which is an essential component of the fixing material (S) of the present invention, and is suitable as the active silica (SS) for the fixing material (S) of the present invention. When the immobilizing material (S) of the present invention is a powdery one-pack composite composition (PS), a powdery alkali silicate may be selected, and a slurry-like one-pack composite composition (SS) may be used. In the case of)), a liquid alkali silicate may be selected.
[0066]
As a layered clay mineral of ferrosilicate having aluminum silicate as a main skeleton of activated silica (SS), amorphous allophane, hissinite, and crystalline ferrosilicate (2: 1 layer type pyroferrite) are generally used. Talc, mica group, montmorillonite group, vermiculite; 2: two-layer type ryokudeite group; 1: 1 layer type kaolinite) and inosilicate (pargolskite group).
[0067]
In the present invention, any of the above-mentioned layered clay minerals can be adopted, but from the viewpoint of availability and the like, a 2: 1 layer type 2-8-layered or 3octahedral smectai group of a hydrous ferrosilicate mineral is used. The layered clay mineral (A1), which is a hydrous ferrosilicate mineral, can be suitably selected. Layered clay minerals of hydrous ferrosilicate minerals are clays having abundant silanol groups in polysiloxane bonds centered on aluminum silicate, and are activated silica (S) for the immobilizing material (S) in the present invention. SS).
[0068]
In particular, montmorillonite classified into the smectite group is preferable because it has high reactivity and is easily available in Japan. Montmorillonite is (Na, Ca_1/2)_0.33(Al_1.67Mg_0.33) Si₄O (OH)₂(However, interlayer water is omitted). Montmorillonite is preferred because the distance between the positive and negative charges is large, the interaction is weak, cation exchange occurs easily, and silanol groups are abundant.
[0069]
However, since hydrous ferrosilicate minerals are natural minerals, various impurities coexist. Therefore, in the case of a water-containing layered clay mineral coexisting with impurities, a layered clay mineral, for example, a clay mineral containing at least 50% by mass or more of montmorillonite as an active ingredient, does not impair the object of the present invention. Can be adopted as clay mineral.
[0070]
Generally, the layered clay mineral (ferrosilicate mineral) contains 20 to 35% by mass of water. However, the layered clay mineral (A1) is preferably a dry powder. It is preferable that the powder is in a powder state in an amount of preferably 20% by mass or less, and the fineness at this time is that the powder has been pulverized and classified into powder that substantially passes at least 80% by mass or more through a 65-mesh sieve. It is preferable from the viewpoint of workability and workability.
[0071]
In addition, as the silica-alumina composite composition (SS4) of activated silica (SS), a sludge cake discharged when water such as a river is purified for water supply at a water treatment plant [Example of main component (mass) %): Moisture 63, SiO₂27, Al₂O₃28, Fe₂O₃5.5, CaO 0.74, MgO 1.1, C8.2], and furthermore, scraps of ceramic products discharged from a ceramic product production site.
[0072]
These silica-alumina composite compositions (SS4) can easily react with an alkali such as sodium hydroxide to cause the silica-alumina composite composition to have silanol groups effective as the active silica of the present invention. In addition, it is effective from the viewpoint of enabling reuse of industrial waste.
[0073]
Further, as the alkali-modified silicate (SS5) of activated silica (SS), silicic acid and a silicate are preliminarily reacted with an alkali such as sodium hydroxide to have a silanol group effective for the activated silica of the present invention. Examples include alkali-modified silicate (SS5).
[0074]
As the silicic acid and silicate at this time, volcanic ash, clay mineral, hydrous mud, sludge, various wastes, and the like can be preferably mentioned. In order to prepare these silicic acids and silicates into alkali-modified silicates (SS5), they must be homogeneously mixed with an alkali hydroxide such as sodium hydroxide via water and reacted at room temperature or under heating. This makes it possible to easily secure silanol groups in the raw material silicic acid or silicate.
[0075]
As the reactive alumina (SA) in the present invention, the following composition formula (2)
bM^I ₂O ・ cM^IIO ・ Al₂O₃・ WH₂O ……… (2)
(Where: M^IIs an alkali metal group, M^IIIs a single element or a combination of two or more elements of the calcium, magnesium, or zinc element group, b is a number of 10 or less including zero, c is a number of 10 or less including zero, and w is a number of 9.0 or less including zero. ) Is preferably a reactive alumina (SA) composed of an aluminum compound of an alkali metal or alkaline earth metal or a hydrate of alumina alone or in combination of two or more. Can be mentioned.
[0076]
The reactive alumina (SA) used in the present invention refers to an aluminum component that forms aluminate ions when the alumina component is dispersed at a room temperature at a reaction equivalent concentration or less with at least a 1/10 normal sodium hydroxide solution. .
As a specific example of the reactive alumina (SA) adopted in the present invention, an alumina-containing compound soluble in an ionic alkali is preferable, and aluminum hydroxide, which is an industrial chemical, can be preferably mentioned. Furthermore, various aluminum-containing compounds and minerals such as bauxite and coal ash that are soluble in ionic alkali can also be selected.
[0077]
In the present invention, sodium hydroxide (SN) is important as a component of zeolites, which are sodium salts of aluminosilicate, which fix heavy metals as water-insoluble compounds. As sodium hydroxide (SN), caustic soda widely used as an industrial chemical can be suitably selected. Of course, when the slurry-like fixing material (S) is selected, the composite composition (LS) can be prepared using caustic soda in a solution state to which necessary water has been added in advance.
[0078]
The calcium composition (SC) in the present invention is preferably a calcium or calcium salt compound containing at least 25% by mass of calcium, expressed as CaO, on a dry matter basis. In the immobilizing material (S) of the present invention, the reason why the calcium composition (SC) is allowed to coexist in the composite is that the coexisting calcium ion plays a catalytic role to stimulate the active silica and to form a zeolite structure which is a sodium salt of aluminosilicate. Helping to effectively form a zeolite structure.
[0079]
As the calcium composition (SC) adopted in the present invention, the following seven types are suitable.
{Circle around (1)} Calcium standard composition which is an oxide or hydroxide of calcium (SC1)
{Circle around (2)} Oxyacid salt composition which is an oxyacid salt compound of calcium (SC2)
{Circle around (3)} halogen salt composition which is a halogen salt compound of calcium (SC3)
▲ 4 ▼ Waste powder composition which is waste such as blast furnace slag and incinerated ash (SC4)
{Circle around (5)} Cement powder composition which is alumina cement / cement (SC5)
(6) Alkali-modified composition obtained by modifying calcium silicate with alkali (SC6)
(7) Carbon-carboxylate modified composition obtained by decarboxylation of carbonates such as limestone and shells (SC7)
[0080]
The calcium composition (SC) according to the present invention can be used for natural mineral resources, industrial chemicals, calcium carbonate such as limestone and shells, depending on the purpose and workability of exerting the function of immobilizing heavy metals by the immobilizing material (S). Decalcified calcium carbonates, cements, and wastes containing a calcium salt compound, and the like can be appropriately selected from compositions obtained by processing and modifying these calcium raw materials.
[0081]
As the calcium composition (SC) adopted in the present invention, the calcium component is represented by CaO in an amount of 25% by mass or more, preferably 35% by mass or more, more preferably 50% by mass, and has a high reaction activity. Powdered calcium oxide or calcium hydroxide containing calcium as a main component is preferred. However, calcia (quicklime) reacts violently with water and generates a large amount of heat (15,540 cal. Per mole), so care must be taken in handling.
[0082]
The calcium compound constituting the calcium composition (SC) is preferably a natural or synthetic calcium oxide or hydroxide. However, these calcium compounds are sensitive to the reaction with carbonic acid and water existing in the air, and generally part of them are changed to carbonates, and natural products contain various impurities. Therefore, when it is adopted as the immobilizing material (S), it is desirable to select as appropriate according to the construction specifications, etc., and to purify and adopt as needed beforehand.
[0083]
Of course, in the calcium composition (SC) adopted in the present invention, the calcium element and the alkaline earth metals magnesium, zinc, strontium, barium and the like which are homologous elements in the periodic table may coexist in some cases. However, as long as it is present in an amount of 10% by mass or less, it does not impair the basic chemical reaction and the specified effect of the present invention as a calcium composition (SC).
[0084]
As a typical composition of the Calcium composition (SC), the following composition formula (3)
CaO ・ wH₂O …………… (3)
(Wherein w is a number of 2 or less including zero) A calcium component composed of one or a combination of two or more selected from the group consisting of calcium oxide and calcium hydroxide is represented by 50% by mass as CaO. The calcium containing as a main component the powdered calcium contained above can be suitably mentioned as the calcium standard composition (SC1).
[0085]
Calcium oxide (aka Calcia, quicklime) constituting the calcium standard composition (SC1) is made of natural limestone, nepheline, calcite, marble, etc., and calcium carbonate (CaCO 2)₃) Is produced in large quantities as quicklime by decarboxylation under a heat atmosphere of about 900 ° C or higher, and is used in a wide range of fields such as steel, chemical industry, paper, building materials, fertilizers, pesticides, soil improvement, etc., and is inexpensive. It is easy to obtain.
[0086]
In particular, shells such as scallops and oysters are a treasure trove as calcium ingredient raw materials. However, since the main component of the shell is stable calcium carbonate, it is left unutilized without being effectively used, and is difficult to dispose of. Adopting shells that are short of treatment and disposal as the raw material of the cassia composition (SC) of the present invention is effective because the shells can be reused. In addition, it is preferable to use seashells as a raw material for immobilization, solidification and reuse of seabed contaminated soil such as sludge, since sea products can improve the environment of the sea.
[0087]
Calcium hydroxide (slaked lime) is produced by adding water to calcium oxide prepared as quicklime and digesting it. The chemical industry (sugar, leather, bleached powder), building and building materials, fertilizers, pesticides, It is used in large quantities in a wide range of fields such as soil stabilization, is inexpensive and easily available, and can be suitably adopted as the standard calcium composition (SC) of the present invention.
[0088]
As another embodiment of the calcium composition (SC) adopted for the immobilizing material (S) of the present invention, the following composition (4)
Ca_nTO_m・ WH₂O …………… (4)
(Wherein, T is a single element or a combination of two or more elements selected from the group consisting of aluminum, silicon, sulfur, and nitrogen elements, n is a number of 1.0 to 6.0, m is a number of 0.5 to 6.0, w is a number of 28,0 or less including zero), and is composed of one or a combination of two or more selected from the group of oxyacid salt compounds of a normal salt or a basic salt of each element of calcium. The powder of the oxyacid salt compound of each element of calcium containing at least 25% by mass based on the CaO oxide can be suitably mentioned as the oxyacid salt composition (SC2).
[0089]
Specific examples of the oxyacid salt composition (SC2) according to the present invention include positive oxyacid salt compounds of each element such as calcium aluminate, calcium silicate, calcium sulfate, calcium sulfite, calcium nitrite, and calcium nitrate. A salt or a basic salt, and an oxyacid salt compound of calcium accompanied by water of crystallization can be appropriately selected from natural minerals, industrial chemicals and the like, and can be suitably adopted.
[0090]
When calcium aluminate is adopted as the oxyacid salt composition (SC2) of the present invention, a supplementary material for the alumina component of zeolite formed in the binder (H) formed by the hydraulic hardening and fixing composition (W) It is also suitable. Moreover, calcium aluminate is a compound having hydration power. Therefore, it is advantageous to adopt the fixing material (S) of the present invention to form a cured body simultaneously with fixing of heavy metals.
[0091]
As another embodiment of the calcium composition (SC) adopted for the immobilizing material (S) of the present invention, the following composition formula (5)
CaZ ・ wH₂O …………… (5)
[Wherein, Z is a halogen element and w is a number of 6 or less] a calcium salt selected from the group consisting of calcium halides or a combination of two or more calcium halides, SC3).
[0092]
When the powdered halogen hydrochloride composition (SC3), which is a calcium halide salt compound, coexists with the active silicic acid composition (B), the halogen ions of the halogen hydrochloride composition (SC3) are converted to the active silicic acid composition (B). On the other hand, since it plays a catalytic role in the alkali reaction, it can be suitably adopted as the calcium composition (SC) of the present invention. Moreover, the calcium halide salt compound is inexpensive and easily available as an industrial chemical, and is suitable as a constituent material of the fixing material (S) of the present invention.
[0093]
Specific examples of the halogen hydrochloride composition (SC3) according to the present invention include anhydrides such as calcium fluoride, calcium chloride and calcium bromide, and compounds accompanied by water of crystallization from reagents and industrial chemicals. Generally, calcium chloride is industrially produced in large quantities and is inexpensive and suitable.
[0094]
Another embodiment of the calcium composition (SC) adopted as the immobilizing material (S) of the present invention is a waste powder composition (SC4). In particular, among industrial wastes, there are powder wastes containing a large amount of an active calcium component. Further, the powder waste containing the calcium component is preferable because it generally contains activated alumina which is an essential component of the fixing material (S).
[0095]
For example, blast furnace slag discharged from steel mills, lime neutralized sludge discharged from the paper industry, waste gypsum board discharged from the construction industry, incinerated ash discharged from incineration of various wastes, coal-fired power Fly ash discharged from the power industry in Japan, calcium silicate powder discharged as waste of insulation and heat insulation, treated sludge discharged from water purification plants for water treatment, wastewater treatment of industrial factories and oil as fuel Pulverized waste mainly composed of a calcium component such as gypsum recovered as a by-product from a flue gas discharged by the desulfurization treatment can be suitably used.
[0096]
The calcium silicate powder used as the waste powder composition (SC4) of the calcium composition (SC) of the present invention is suitable because it can be prepared without lowering the silica concentration of the immobilizing material (S) to be prepared. It is. Specifically, calcium silicate, a waste material used as a heat insulating and heat insulating material as amorphous calcium silicate, such as crystalline wollastonite and zonotorite, is suitable.
[0097]
Furthermore, as the waste powder composition (SC4) in the present invention, organic-containing wastes (thinned wood, pruned waste, wastes in agriculture, livestock, and fisheries, various fermentation residues, food processing residues, garbage, paper) Ashes obtained by incineration of sludge or the like or charcoal-containing ashes obtained by dry distillation can also be suitably mentioned.
[0098]
Another embodiment of the calcium composition (SC) adopted as the fixing material (S) of the present invention includes a cement powder composition (SC5). As the cement powder composition (SC5) of the present invention, Portland cement, which is industrially mass-produced and widely used at low cost, is easily available and suitable.
[0099]
Portland cement is stipulated in JIS R # 5200, and is classified into ordinary, early strength, ultra early strength, moderate heat, sulfuric acid resistance and the like. Furthermore, there are mixed cements such as blast furnace cement, silica cement, fly ash cement, etc. In addition, various special cements (white cement, alumina cement, ultra-fast setting cement, colloidal cement, oil well cement, geothermal cement, swelling cement, etc. Powders of hydraulic cement minerals).
[0100]
Since the cement powder composition (SC5) of the present invention itself is a cement mineral having a hydraulic function, it forms a hydrate by mixing with water to form a solid. However, the expectation for the cement powder composition (SC5) is that the polymerization reaction by the silanol group of the active silicic acid composition (B) is promoted, not the function of forming the solidified body of the cement itself, and the fixing material (S) It is where the function as is demonstrated.
[0101]
Another embodiment of the calcium composition (SC) employed in the immobilizing material (S) of the present invention includes an alkali-modified composition (SC6). As the alkali-modified composition (SC6), 100 parts by mass of silicate-containing calcium compounds (for example, calcium silicate, blast furnace slag, fly ash, incinerated ash, cement, etc.) are mixed with an alkali metal hydroxide. (MOH, M is an alkali metal) in an amount of 1 to 30 parts by mass, and water in an amount of 50 parts by mass or less. The silicate-containing calcium compounds having an alkali silanol group are reacted.
[0102]
As the calcium composition (SC) of the present invention, alkali metal hydroxide is added to a silicate-containing calcium compound, for example, calcium silicate used for heat insulation and heat insulating material, and the mixture is denatured and fixed. The alkali metal component, which is an essential four component of the material (S), is formed by adding silanol group-containing silica or calcium, and, depending on the selected raw material, alumina, and an alkali-modified composition as a component of the fixing material (S). (SC6) is very preferable.
[0103]
As a silicate-containing calcium compound used as a raw material of the alkali-modified composition (SC6), there is also a waste powder composition (SC4), which is an iron mill containing activated silica and reactive alumina together with calcium. Blast furnace slag discharged, fly ash discharged from a thermal power plant, and water treatment sludge discharged from a water treatment plant can be preferably cited because they can effectively utilize wastes.
[0104]
Since the alkali-modified composition (SC6) prepared in advance is a component of the immobilizing material (S), which is a powdery one-pack composite composition, it must be a powder. When the reactant collected by reacting with the silicate-containing calcium compound is paste-like or plastic-like, it is necessary to perform a dehydration treatment in advance by drying or the like, and then obtain a powdery one-pack composite composition.
[0105]
As another embodiment of the calcium composition (SC) adopted for the immobilizing material (S) of the present invention, a carboxyl acid-modified composition (SC7) can be mentioned. As in the case of the calcium standard composition (SC1), calcium carbonate is heated and decarbonated at about 900 ° C. and recovered as calcium. However, the activated silicic acid composition (B) subjected to the activation treatment is on the acidic side leaving free sulfuric acid. The use of sulfuric acid or the like to decompose calcium carbonate as a calcium raw material is also preferable because it can be used as a raw material for the immobilizing material (S) of the present invention.
[0106]
As other embodiments of the calcium composition (SC) adopted for the immobilizing material (S) of the present invention, the above-mentioned calcium composition (SC), the calcium standard composition (SC1), and the oxyacid salt composition (SC2) ), A halogen salt composition (SC3), a waste powder composition (SC4), a cement powder composition (SC5), an alkali-modified composition (SC6), and an acid-modified composition (SC7). The powdered calcium composite material (SC8), which is composed mainly of powdered calcium and is composed of a combination of the above, can exhibit the multifunctionality of each calcium composition in a composite manner. It can be suitably mentioned.
[0107]
In the method for treating contaminated soil according to the present invention, depending on the purpose, use, site conditions, workability, physical properties, performance, etc. required of the treated soil, various functions can be added together with immobilization of heavy metals in the contaminated soil. Is required. At this time, various additional auxiliary compositions (ST) are added to the essential four components [active silica, reactive alumina, sodium hydroxide, and calcium hydroxide composition] of the solidifying material fixing material (S) of the present invention, thereby increasing the amount. The immobilizing material (S) can be prepared as a functional composite composition (PS & LS).
[0108]
A preferred additive auxiliary composition (ST) which exhibits multifunctionality by being added to the immobilizing material (S) of the present invention is a mixed calcium composition comprising crystal seeds, sulphate groups and phosphate groups which are nuclei for zeolite formation. Dispersion of contaminants (SC), reaction modifiers composed of barium salts, trapping aids such as arsenic and chromium composed of iron salts, adsorbent carrying aids and immobilizing material (S) in contaminated soil. Additional compounding materials that exhibit assisting functional performance may be mentioned.
[0109]
Therefore, the following seven types can be suitably exemplified as the additional auxiliary composition (ST) in the present invention.
{Circle around (1)} Crystal seed composition which is a seed for growing zeolite crystals (ST1)
{Circle over (2)} Sulfate group composition (ST2) for adjusting the activity of calcium composition (SC), etc. {3} Phosphate group composition (ST3) for adjusting the activity, etc. of calcium composition (SC) ▲ 4ＳＣ Barium salt composition (ST4) for controlling workability in processing step
(5) Iron salt replenishment composition to assist in immobilization of heavy metals such as arsenic and chromium (ST5)
{Circle around (6)} Auxiliary supporting composition for supporting and capturing and fixing ionic heavy metals (ST6)
(7) Dispersion medium composition for improving the effect of the immobilizing material in contact with soil (ST7)
[0110]
The addition auxiliary composition (ST) in the present invention is preliminarily mixed with the essential four-component constitution of the present invention [active silica (SS), reactive alumina (SA), sodium hydroxide (SN), calcium composition (SC)]. It is preferable from the viewpoint of handling and workability that the mixture is made into a one-pack as a powdery composite composition. For this reason, it is preferable that the additional auxiliary composition (ST) adopted in the present invention be purified and prepared in powder form in advance by removing impurities.
[0111]
The crystalline seed composition (ST1) suitable as the addition auxiliary composition (ST) of the present invention exists as a nucleus for generating crystals of a zeolite, which is an aluminosilicate formed from the immobilizing material (S) of the present invention. However, it is preferable that the zeolite is allowed to coexist with the immobilizing material (S) as a seed for rapidly growing the zeolite.
[0112]
The crystal seed composition (ST1) to be added and blended into the fixing material (S) of the present invention includes a unit cell chemical composition formula (6) shown below.
M_{x / n}・ [(AlO₂)_x・ (SiO₂)_y] ・ WH₂O ……… (6)
[Wherein M is a metal cation having a valence of n: X + Y is a tetrahedral number per unit cell] and has a zeolite structure of a metal salt of aluminosilicate [M is generally sodium and calcium]. Zeolites are suitable as seeds for crystal growth.
[0113]
In particular, a natural product can be selected as the crystal seed composition (ST1) in the present invention, but industrially produced zeolites having a fixed crystal form, such as a 4A type synthetic zeolite, are preferred. It is preferable that the zeolite to be these seeds is fine particles having a particle size of 10 μm or less, preferably 6 μm or less.
[0114]
The sulfate group composition (ST2) suitable as the supplementary auxiliary composition (ST) of the present invention neutralizes the calcium composition (SC) constituting the immobilizing material (S) of the present invention, and treats the treated soil. Is important as a pH adjuster that does not unnecessarily improve the pH value of the compound. In particular, in the present invention, a sodium salt of aluminum silicate is formed by the immobilizing material (S), and the contained sodium element is not ionized but immobilized.
[0115]
However, although the catalytic role played by the calcium ions of the calcium composition (SC) incorporated in the formation of the sodium silicate of aluminum is important, the coexistence of the sulfate group composition (ST2) After the formation of zeolites, which are sodium salts of aluminum silicate, it is possible to avoid the alkalinity of the soil treated by calcium ions. Therefore, it is effective to form calcium sulfate sulfate crystals (by ST2). It is.
[0116]
The sulfate group composition (ST2) additionally blended with the fixing material (S) of the present invention has the following composition formula (7):
aM^I ₂ObM^IIO ・ cM^III ₂O₃・ SO_n・ WH₂O ……… (7)
[Where: M^IIs an alkali metal element, M^IIIs an alkaline earth metal element, M^IIIIs a trivalent aluminum or iron, a, b and c are numbers not more than 20 including zero, w is a number not more than 25 including zero, and aluminum or iron containing an alkali metal salt of a basic salt or a normal salt. And a sulfate group composition (ST2) composed of one or a combination of two or more selected from the sulfur oxyacid salt compounds.
[0117]
Examples of the sulfate group composition (ST2) suitable for the present invention include an alum-type composition (ST2-a) containing aluminum sulfate as a main component, and a sodium sulfate type composition (ST2-b) containing sodium sulfate as a main component. Compounds (ST2-c) obtained by combining these sulfates can be classified and listed.
[0118]
The alum-type composition (ST2-a), which is a sulfate group composition (ST2), has the following composition formula (7-a):
aM^I ₂O ・ cM^III ₂O₃・ SO_n-WH₂O ... (7-a)
[Where: M^IIs an alkali metal element, M^IIIIs a trivalent aluminum or iron, a is a number of 0.2 or 20, c is a number of 1 or 20, w is a number of 25 or less including zero, and n is a number of 2 or 3.] An alum-type composition (ST2-a) composed solely or in combination of two or more selected from the group of oxyacid salt compounds of aluminum or iron sulfur containing a salt or normal salt of an alkali metal can be mentioned.
[0119]
As an alum-type composition (ST2-a), the oxyacid salt of alkali metal aluminum or iron sulfur is octahedral K formed from a mixed solution of aluminum sulfate and potassium sulfate.₂SO₄・ Al₂(SO₄)₃・ 24H₂A double salt crystal of O is typical. Note that, as the sulfate group composition (ST2) in the present invention, aluminum sulfate and iron sulfate when a in formula (7-a) is zero can also be effectively adopted.
[0120]
Furthermore, in the immobilizing material (S) of the present invention, since the formation of zeolites is expected, the coexistence of an aluminum component which is a constituent component of zeolites is effective. Although the four-component composite composition (PS & LS) contains aluminum, the aluminum component of aluminum sulfate, which is an alum-type composition (ST2-a), is also effective as an aluminum component of zeolites.
[0121]
Furthermore, zeolites are formed by the immobilizing material (S) of the present invention, and heavy metals contained in contaminated soil are immobilized. At this time, arsenic and chromium as heavy metals coexist with iron ions. It is known that the alum-type composition (ST4-a) contains iron ions.
[0122]
As the sulfated salt composition (ST2-b) which is the sulfate group composition (ST2), the following composition formula (7-b)
aM^I ₂O ・ SO_n・ WH₂O ……… (7-b)
[Where: M^IIs an alkali metal element, a is a number of 1 to 20, w is a number of 20 or less including zero, n is a number of 2 or 3, and the alkali is a basic salt or a normal salt of lithium, sodium or potassium. A Glauber's salt type composition (ST2-b) composed solely or in combination of two or more selected from the metal oxyacid salt compounds can be suitably mentioned.
[0123]
Representative compounds of the alkali metal sulfur oxyacid salt compounds of lithium, sodium or potassium, which are the sodium sulfate type composition (ST2-b), are sodium sulfate (Na₂SO₄・ 10H₂O or anhydrous salt), and naturally in rock salt producing areas as a double salt with gypsum, which is lime-salt. Industrially, it is by-produced as a by-product sodium sulfate at the time of waste liquid treatment.
[0124]
In the present invention, any of natural and synthetic / by-product sodium sulfate containing impurities can be suitably adopted. Compounds such as a double salt or a basic salt containing potassium, a salt compound of an alkaline earth metal, and a mixed complex salt in which a carbonate coexists are also suitable as the glass-type composition (ST2-b) of the present invention. Can be adopted.
[0125]
As a composite composition (ST2-c) that is a sulfate group composition (ST2), it is composed of a combination of two or more of an alum-type composition (ST2-a) and a sodium sulfate composition (ST2-b) group. A composite sulfate group composition (ST2) can be mentioned. The composite composition (ST2-c) can be selected and adopted depending on the use, purpose, workability, and the like of the immobilizing material (S) of the present invention.
[0126]
The phosphate group composition (ST3) suitable as the addition auxiliary composition (ST) of the present invention neutralizes the calcium composition (SC) constituting the immobilizing material (S) of the present invention, and treats the treated soil. Is important for the same reason as in the case of the sulfate group composition (ST2) as a regulator that does not unnecessarily improve the pH value of the above.
[0127]
In particular, after the formation of zeolites, which are sodium salts of aluminum silicate, the treated soil shows high alkalinity due to the free calcium composition (SC), which causes secondary pollution and has truss φ. However, the formation of calcium phosphate crystals is effective because the concern can be avoided.
[0128]
The phosphate group composition (ST3) as the immobilizing material (S) of the present invention has the following composition formula (8):
hGO_t・ P₂O₅・ WH₂O ……… (8)
[Wherein, G is a single element or a combination of two or more elements selected from the group consisting of sodium, potassium, magnesium, calcium, barium, aluminum, titanium, silicon, and iron, h is a number of 1.0 to 8.0, and t is G The number of element valence ÷ 2, w is a number of 10 or less including zero], and boron of a single or a combination of two or more selected from the group of phosphorus oxyacid compounds of each metal element. Oxy acid salt compounds can be suitably mentioned.
[0129]
Specific examples of the phosphate group composition (ST3) adopted in the present invention include sodium phosphate, potassium phosphate, magnesium phosphate, calcium phosphate, barium phosphate, and aluminum phosphate among reagents or industrial chemicals. , Titanium phosphate, silicon phosphate, iron phosphate and the like.
[0130]
Furthermore, in the phosphate group composition (ST3) of the present invention, after treatment with a phosphoric acid-based chemical commonly used as a surface treatment agent (parkerizing treatment agent) for metal products (automobiles, vehicles, building materials, home appliances, etc.), Sludge containing a large amount of phosphate discharged as industrial waste can be effectively used.
[0131]
Still further, as the phosphate group composition (ST3) of the present invention, powdery silicon phosphate exhibiting a sustained release of phosphoric acid under alkaline conditions can be suitably exemplified.
Silicon phosphate has the following composition formula (8-a)
jSiO₂・ P₂O₅……… (8-a)
[Where j is a number of 1.0 or 8.0] is a silicon phosphorus selected from the group consisting of silicon phosphates selected from the group consisting of silicon phosphates or a combination of two or more thereof. An oxyacid salt compound having a "sustained release in minutes" can be suitably exemplified.
[0132]
"Slow release of phosphoric acid content" in silicon phosphate can be evaluated by the following test method, and the following formula (T-1)
Y = aX + b... (T-1)
In the formula, X is the time (minutes) elapsed after 1 g of silicon phosphate was stirred and dispersed in 100 ml of 4N (normal) caustic soda solution, and Y was phosphoric acid (P) eluted in the 4N (normal) caustic soda solution.₂O₅) Amount (mg / 100 ml)], the initial elution amount (b) at which the phosphoric acid content of silicon phosphate elutes into the alkaline solution is 200 or less, and the average hydrolysis rate constant corresponding to a in the formula (A) refers to the state of dissolution of phosphoric acid in the range of 0.2 or more.
[0133]
The silicon phosphate in the present invention is preferably a stable compound capable of gradually releasing phosphoric acid in the formation of zeolites without being easily hydrolyzed even under conditions of strong alkali side. Therefore, silicon phosphate was found to be synthesized by heating in a temperature range of 500 to 1100 ° C. with j in the composition formula (8-a) being in the range of 1.0 to 8.0. It is suitable because it allows sustained release of the drug.
[0134]
When j in the composition formula (8-a) is smaller than 1.0 and is synthesized by heating at 700 ° C. or lower, only unreacted deliquescent silicon phosphate is synthesized and alkali adjustment cannot be expected. When j is larger than 8.0 and synthesized by heating at 1100 ° C. or higher, the phosphoric acid contained is volatilized, and the effect as silicon phosphate cannot be expected.
[0135]
The silicon phosphate of the present invention is preferably surface-treated with a coating agent known and used in the art in order to ensure stability during storage and sustained release of phosphoric acid. In this case, as the coating agent, a fatty acid (such as stearic acid) or a fatty acid salt (such as calcium stearate) which is soluble in an alkaline solution, and a coupling agent (such as an organosiloxane or a titanium coupling agent) are added in a conventional manner. It is preferable that the coating is carried out at a content of 01 to 6.0% by mass.
[0136]
The barium salt composition (ST4) to be added to the fixing material (S) of the present invention is represented by the following composition formula (9):
BaO · fSiO₂・ WH₂O ……… (9)
[Wherein, f is a number of 4.0 or less, w is a number of 10 or less including zero] A single or a combination of two or more selected from barium salt compounds soluble in an alkali solution represented by the following formula: The barium salt compound in the form of a powder can be suitably exemplified.
[0137]
In the present invention, the regulating function such as workability of the powdery barium salt compound adopted as the barium salt composition (ST4) can be estimated by “soluble portion of barium ion in alkaline solution”. “Soluble of barium ion in alkaline solution” can be evaluated by the following test method.
[0138]
"Soluble of barium ion in alkaline solution" means the amount of barium ion in a sampling solution obtained by filtering a sample solution obtained by stirring and dispersing 10 g of a barium salt compound in 100 ml of 1N (normal) caustic soda solution at 25 ° C for 10 minutes. Is measured as BaO, and expressed as a percentage of the amount of all barium elements in the sample barium salt compound in terms of BaO, and the amount of barium soluble in the alkali solution can be evaluated.
[0139]
In order to control the formation of the zeolites adjusted by the immobilizing material (S) of the present invention, the “soluble matter in an alkaline solution” of the barium salt compound which is the barium salt composition (ST4) is 10% or more. It is preferred that there be. When the “soluble matter in the alkaline solution” is 10% or less, it is difficult to control the workability of the fixing material (S), which is not preferable.
[0140]
In general, the barium salt compound which satisfies the above "soluble matter in an alkaline solution", is inexpensive and easily available includes barium hydroxide [Ba (OH) .8H], an industrial chemical.₂O] or barium oxide [BaO] is preferred. However, barium silicate is suitable as the barium salt compound as the barium salt composition (ST4) which does not adversely affect the formed zeolites and can secure a sufficient work life for the formation of zeolites.
[0141]
The barium silicate as the barium salt supplementary composition (ST4) preferably has a number k of 4.0 or less in the composition formula (10), and effectively activates barium ion at a number of 4.0 or more. Not available. In addition, the number of w in the composition formula (10) is preferably 9.0 or less, and if the number is 9.0 or more, the storage stability of the barium salt compound is not ensured, and the national standard of the present invention is achieved. I can't.
[0142]
The iron salt replenishing composition (ST5) suitable as the supplementary auxiliary composition (ST) of the present invention is used for fixing heavy metals contained in contaminated soil in a water-insoluble manner. The coexistence of a salt is preferable in that the immobilization is effectively exhibited and the immobilization of the present invention is effectively achieved.
[0143]
As the iron salt replenishing composition (ST5) adopted in the present invention, divalent or trivalent iron hydroxide compounds are particularly effective. However, divalent or trivalent iron chloride, iron sulfate, and metal iron can be preferably mentioned from the viewpoint of easy availability as industrial chemicals or wastes.
[0144]
These metallic iron and iron chloride and iron sulfate are also easily divalent or trivalent by the reaction with the calcium composition (SC) blended in the immobilizing material (S) and the reaction with oxygen and moisture in the atmosphere. A monovalent iron hydroxide compound is generated, and the auxiliary effect of immobilizing heavy metals can be sufficiently exhibited.
[0145]
The supporting auxiliary composition (ST6) suitable as the additional auxiliary composition (ST) of the present invention sufficiently contains a soluble material such as sodium hydroxide (SN) mixed with the immobilizing material (S) of the present invention. When the immobilizing material (S) of the present invention is incorporated into contaminated soil by being supported or adsorbed, the zeolite can be effectively removed without releasing the compounded soluble material out of the reaction system. Is important in forming
[0146]
Suitable supporting auxiliary compositions (ST6) in the present invention include animals and plants containing various organic compounds and organic materials, and natural materials collected, produced and processed in the fields of agriculture, livestock and fisheries. Products and wastes, products and fermentation residues from fermentation of various natural products, wastes from manufacturers of paper, pulp and textile fabrics and processing, and also from various plastics and their processing sites Organic materials and the like to be obtained are subjected to dry distillation at 4000 to 1000 ° C., and charcoal containing carbon as a main component, and carbon-silicate composite containing silica or alumina in some cases. it can.
[0147]
The dispersion medium composition (ST7) suitable as the supplementary auxiliary composition (ST) of the present invention is important as a medium for dispersing the immobilizing material (S) of the present invention effectively and uniformly in contaminated soil. It is. As an effective medium for the immobilizing material (S) of the present invention, an inorganic compound in the form of a powder of 100 μ or less, preferably 10 μ or less, is effective. It has good compatibility with the fixing material (S) and is suitable.
[0148]
As a specific dispersion medium composition (ST7), an inexpensive material that is industrially mass-produced is suitable as the dispersion medium composition (ST7) of the present invention. For example, examples of natural products include kaolin, acid clay, bentonite, bauxite, silicate, talc, zeolite, lime powder, bauxite, perlite, gypsum, and volcanic ash.
[0149]
Furthermore, waste by-product shops from industrial associations that are emitting large quantities can raise their utensils. For example, fly ash discharged from thermal power plants, slugs discharged from the steel industry, flue gas desulfurization, gypsum by-produced from the titanium industry, etc. It is preferable because it is ready to be obtained.
[0150]
The composite auxiliary composition (ST7) suitable as the additional auxiliary composition (ST) of the present invention is obtained by combining the functionality of each additional auxiliary composition (ST) with the fixing material (S) of the present invention and fixing the composite. It is important for the composite material (S) to exhibit a plurality of functions in combination. The conditions such as the type and composition of these composites differ depending on the application, effect, site conditions, workability, etc., in which the immobilizing material (S) of the present invention is adopted, and thus are determined by preliminary experiments performed in advance according to each purpose. There is a need to.
[0151]
The composite auxiliary composition (ST7) of the present invention includes the above-described crystal seed composition (ST1), sulfate group composition (ST2), phosphate group composition (ST3), barium salt composition (ST4), and iron salt replenishment. The composition (ST5), the supporting auxiliary composition (ST6), and the composite auxiliary composition composed of a single or a combination of two or more selected from the group of dispersion medium compositions (ST7) are preferable. The amount is determined by preliminary experiments performed in advance depending on the purpose and application.
[0152]
The composite auxiliary composition (ST7) of the present invention is formed according to the purpose, application, local situation, workability, and the like required for immobilization of heavy metals by zeolites, and synergistic effect in the auxiliary effect is expected. Therefore, the kind and compounding amount selected for the composite auxiliary composition (ST7) of the present invention should be determined and confirmed by preliminary experiments conducted in advance according to the purpose, application, local situation, workability, and the like. Is preferred.
[0153]
In the method for treating contaminated soil according to the present invention, the immobilizing material (S) is mixed with the contaminated soil via water to fix the heavy metals contained therein, and the treated soil is not hardened and solidified and is exposed to an external pressure. On the other hand, it is important to convert the soil into deformable treated soil. At this time, the type and the mixing ratio of the fixing material are selected according to the purpose, application, local situation, workability, and the like.
[0154]
The compounding ratio of the immobilizing material (S) of the present invention in the powdery composite composition (PS) having the essential four components is based on 100 parts by mass of active silica (SS) having a silanol group and reactive alumina (SA). 50 to 200 parts by mass, 15 to 80 parts by mass of sodium hydroxide (SN) and 20 to 300 parts by mass of the calcium hydroxide composition (SC) are homogeneously mixed to form a one-pack. Effective and preferred for formation.
[0155]
When the amount of reactive alumina (SA) is less than 50 parts by mass with respect to 100 parts by mass of active silica (SS) in the powdery composite composition (PS) of the essential four-component constitution of the present invention, the formation rate of zeolites Decreases. When the amount of the reactive alumina (SA) is 200 parts by mass or more, unreacted alumina remains, and it is not possible to expect effective generation of zeolites.
[0156]
When the amount of sodium hydroxide (SN) is less than 15 parts by mass, the formation rate of zeolites decreases, and the effect function of the present invention cannot be expected. Further, when the content of sodium hydroxide (SN) is more than 80 parts by mass, an alkali component is separated and left in the treated soil, which is not preferable because the treated soil becomes alkaline.
[0157]
Further, when the ratio of the calcium composition (SC) is less than 20 parts by mass, the catalytic efficiency of calcium ions on the formation of zeolites at ordinary temperature is reduced, and the formation of zeolites is reduced. On the other hand, when the ratio of the calcium composition (SC) is more than 300 parts by mass, the amount of the immobilizing material (S) only increases, and a particularly improved effect on the immobilization of heavy metals of the present invention cannot be obtained.
[0158]
Furthermore, the compounding ratio of the immobilizing material (S) of the present invention in the five-component powdery composite composition (PS) is based on 100 parts by mass of the essential four-component composite composition (PS). It is preferred that (ST) is homogeneously mixed at 1 to 200 parts by mass to form a one-pack, because it exhibits a characteristic effect in the formation of zeolites with multifunctionality according to the purpose and application.
[0159]
In the compounding ratio of the five-component powdery composite composition (PS) of the present invention, the mixing ratio depends on the purpose, application, workability, etc., and the required functionality. ) The addition auxiliary composition (ST) may be added and blended within a range of 200 parts by mass with respect to 100 parts by mass, and even if the addition auxiliary composition (ST) is blended in 200 parts by mass or more, zeolite is formed. However, further improvement in functionality cannot be expected.
[0160]
Furthermore, water is added in the range of 60 to 120 parts by mass with respect to 100 parts by mass of the slurry-like composite composition (PS) having the essential four-component or five-component composition of the immobilizing material (S) of the present invention, and is previously homogenized. The composite composition (SS) of the present invention is preferably prepared in a mixing apparatus specified in a mixing step by mixing the contaminated soil and the immobilizing material (S). ) Is preferable from the viewpoint of effectively improving the workability of uniformly contacting the contaminated soil.
[0161]
Since the composite composition (PS), which is the immobilizing material (S) of the present invention, starts a reaction by coexisting with water, contact with water is minimized during storage of the immobilizing material (S). Preferably the direction. In addition, since the immobilizing material (S) contains reactive calcium, it is preferable that the immobilizing material (S) be stored and managed in a direction to minimize contact with carbon dioxide gas or the like.
[0162]
[Fixation treatment step]
In the present invention, it is an object of the present invention to efficiently fix insoluble heavy metals to insoluble, and to obtain deformable treated soil without hardening and solidifying the fixed treated soil. In order to achieve the object, it is necessary to uniformly contact the immobilizing material (S) with the contaminated soil via water to form an admixture. At this time, it is important to prepare a mixture to be formed into a plastic or fluid mixture according to the intended use / use of the soil to be treated, site conditions, workability including economy, and the like.
[0163]
Naturally, when the soil of the soil treated in parallel with the immobilization of heavy metals in the contaminated soil is required to have a certain strength and a certain strength and strength, a patent application by the present inventors (Japanese Unexamined Patent Application Publication No. -246261, Japanese Patent Application No. 2000-351931, Japanese Patent Application No. 2001-083816, Japanese Patent Application No. 2001-234183, etc.) and publicly / public ground improvement, or the present invention achieves the object. can do.
[0164]
Further, according to the method for treating contaminated soil of the present invention, the contaminated soil is once mined and moved by the immobilizing material (S), or the heavy metals contained therein are immobilized in water insoluble at the original position in the surface layer or the deep layer. It can be transformed into treated soil. At this time, the treated soil subjected to the immobilization treatment can be reused as the land utilization ground, but the treated soil can be utilized and utilized for other uses.
[0165]
When utilizing the treated soil according to the present invention for other purposes, it is effective to granulate the treated soil in advance into granules that are easy to handle. In the above-mentioned patents of the present inventors, a technique is disclosed that exerts not only a function of fixing heavy metals but also a function of hardening and solidifying hydrous soil. Specifically, a solidifying material having a heavy metal immobilizing function in parallel with the solidifying function is added to the contaminated soil to be processed into a plastic or fluid admixture. Using an apparatus for granulation and granulation, granulate the mixture into granules of a desired form having a particle size of 0.5 to 35 mmφ and, if necessary, drying in air or by heating to obtain granules. Can be used effectively.
[0166]
Furthermore, there is also contaminated soil that is subjected to complex contamination by containing contaminated soil containing organic substances such as dioxins and organic environmental hormones together with heavy metals. In this case, the organic substance contained, but does not prevent the formation of zeolites for immobilizing heavy metals. However, prior to treating heavy metals by the method of the present invention, the organic substance is decomposed and removed by a known / official decomposition and removal method, for example, heat treatment or the like, and then subjected to the treatment method of the present invention. Is effective because it can completely repair and regenerate the soil with complex contamination.
[0167]
In the present invention, the fact that the formed admixture is plastic refers to a state in which, when the admixture having no flowability is deformed beyond the elastic limit by applying an external pressure to exceed the elastic limit, the strain remains as it is even when the external pressure is removed. At this time, the shape of the plastic admixture may be a set of large lumps, or may be finely sized sand particles, or a mixture of various shapes and sizes. There is also.
[0168]
In the present invention, the fact that the formed admixture is fluid means that the admixture is in a state of flowing downward when the admixture is set on an inclined plate having good slipperiness. Say. Therefore, at this time, the formed fluid mixture can be injected into, for example, a narrow place by utilizing the fluidity possessed by the fluid mixture. In addition, by utilizing the flowability, the contaminated soil can be moved while flowing to a location where the contaminated soil is mined or another location to fix heavy metals.
[0169]
In actual soil, soil often contains moisture. Therefore, when preparing the admixture, measure the water contained in the target soil, convert the water content at this time, and take into account the intended purpose, use, site conditions, etc. of the treated deformable soil. Therefore, it is necessary to determine the compounding amount when the mixture of the present invention is obtained.
[0170]
In the plastic admixture of the present invention, 5 to 30 parts by mass of the immobilizing material (S) and less than 60 parts by mass of water are homogeneously mixed with 100 parts by mass of the contaminated soil contained on a dry matter basis. Achieved by At this time, when the amount ratio of the immobilizing material (S) is less than 5 parts by mass, the function as the immobilizing material (S) cannot be exhibited, and more than 30 parts by mass of the immobilizing material (S) Even if S) is added, there is no particular improvement in the effect, and there is no economic efficiency.
[0171]
When a small amount of water is used to form a plastic admixture, it is effective for in-situ fixation of contaminated soil, and a simple admixture treatment device can be carried to the site for work. This is advantageous because an economical construction method can be selected only for the soil immobilization treatment. Of course, the contaminated soil can be once mined, the mined contaminated soil can be moved to a mixing device capable of forming a plastic admixture, and the contaminated soil can be immobilized by homogeneously contacting and mixing.
[0172]
The flowable admixture of the present invention has a ratio of 5 to 30 parts by mass of the immobilizing material (S) and 60 to 140 parts by mass of water with respect to 100 parts by mass of the contaminated soil containing heavy metals on a dry matter basis. Achieved by intimate mixing. When the proportion of water is less than 60 parts by weight, the admixture loses fluidity. When the amount of water is more than 140 parts by mass, the admixture becomes a shabu-shabu state and loses its properties as soil.
[0173]
As a mixing device that enables the method of bringing the fixing material (S) into contact with the contaminated soil via water to uniformly mix the soil, the soil improvement method in the civil engineering work generally includes the soil soil and cement. And quick lime, various methods and methods of contacting and mixing solidifying materials such as solidifying chemicals, and furthermore, mixing devices adopted in the improved methods and methods of these methods and methods are used in the immobilization process of the present invention. It can also be suitably adopted as a mixing device that enables contact mixing.
[0174]
The contact mixing method that enables the mixing process of the contaminated soil and the immobilizing material (S) differs depending on whether a plastic or fluid admixture is selected as the admixture. Typically, it can be cited as a preferred system.
▲ 1 ▼ 事前 Pre-mixing method in which contaminated soil is moved to a container that can be stirred and mixed and mixed
(2) Excavation and agitation method for mixing at the in-situ surface layer less than 1m below the ground surface
(3) Mechanical agitation method for mixing in the in-situ deep part 1m or less from the ground surface
(4) High-pressure injection method that mixes in-situ deeper parts of 1m or less from the ground surface
[0175]
In the pre-mixing method in the mixing process, the soil mined from the ground where the contaminated soil is present is moved into a container equipped with a stirrer, and a predetermined amount of the immobilizing material (S) of the present invention and, if necessary, water. Is added and mixed and stirred, and the contaminated soil and the immobilizing material (S) are homogeneously contacted and mixed. At this time, if the mined soil has been dried with a water content of 10% by mass or less, it is necessary to add additional water in a range of at least 15 to 50% by mass, and then mix and stir to obtain uniform contact. This is suitable for improving the stirring efficiency of zeolite and forming zeolites.
[0176]
In the excavation and agitation method in the mixing process of the present invention, a mixing device that enables the contaminated soil and the immobilizing material (S) to be mixed and contacted on site in the in-situ surface layer portion less than 1 m from the ground surface of the contaminated soil is provided. is necessary. As the mixing device, all the mixing devices capable of excavation and stirring adopted in the ground improvement method in civil engineering can be adopted by the excavation and stirring method of the present invention.
[0177]
Specific examples of the mixing device adopted in the excavation stirring method of the present invention include a stirrer stirring method, a backhoe scraping and mixing method, and a backhoe method having a stirring function. These mixing devices are easy to bring into the site, easy to operate and economical, and can contact and mix the powdery or slurry-like fixing material (S) at the surface layer of the ground. It is.
[0178]
In the mechanical agitation method in the mixing process of the present invention, a mixing device is required that enables the contaminated soil and the immobilizing material (S) to be mixed and contacted on site in the in-situ deep portion of 1 m or less from the ground surface of the contaminated soil. It is. As the mixing device, all of the mixing devices capable of mechanical stirring adopted in the soil improvement method of the deep part in the civil engineering work can be adopted by the excavation stirring method of the present invention.
[0179]
Specific examples of the mixing device adopted by the mechanical stirring method of the present invention include a spiral insertion type earth auger method using a three-point pile driver (pile driving machine) and the like, a casing pipe forced lifting type rotary press-fitting method, and the like. Can be mentioned. The equipment required for these methods is a mechanical stirring method that sends the immobilizing material (S) into the deep part of the local soil ground and makes it contact with the soil, and is large-scale, but can process a large amount of soil up to the deep part. It is preferable that the powdery or slurry-like fixing material (S) can be contact-mixed in accordance with each mixing device.
[0180]
In the high-pressure injection method in the mixing process of the present invention, the contaminated soil and the immobilizing material (S) can be mixed and contacted in situ in the in-situ deep portion 1 m or less from the ground surface of the contaminated soil as in the mechanical stirring method. Is required. As the mixing device, all the mixing devices capable of contact-mixing the soil and the immobilization material (S) by high-pressure injection adopted by the soil improvement method for deep parts in the civil engineering work shall be adopted by the excavation stirring method of the present invention. Can be.
[0181]
Specific examples of the mixing device adopted in the high-pressure injection method of the present invention include a high-pressure injection stirring method of a powder injection stirring type or a slurry injection stirring type. In these construction methods, a powdery or slurry-like immobilizing material (S) is injected into the ground with a rotary nozzle at a high pressure, and the soil particles around the pile or the injected pile and the immobilizing material (S) are contact-mixed. It is a construction method and device that achieves the object of the invention.
[0182]
The mixing device required for these construction methods is a high-pressure jet stirring system in which the fixing material (S) is sent into the deep part of the local soil ground and brought into contact with the soil. It is possible to treat a large amount of soil, and it is possible to contact and mix the powdery or slurry-like immobilizing material (S) with the contaminated soil according to the respective high-pressure jet-stirring type mixing device. is there.
[0183]
In the mixing treatment step of the present invention, the step / method of bringing the immobilizing material (S) of the present invention into uniform contact with the contaminated soil is not limited to the above-described step / method. In practice, depending on the contamination status of the contaminated soil, for example, co-contamination with organic pollutants, types of contaminated heavy metals, contamination concentration, variation, depth of contaminated sites, etc. A construction method should be selected.
[0184]
The feature of the present invention is that the treated soil modified by the technology of the present invention is subjected to the immobilization step by adding the immobilizing material (S) to the contaminated soil via water to obtain a plastic or fluid admixture. As a result, the heavy metals contained therein are immobilized as zeolites, and the immobilized zeolites are stable without being decomposed even when contacted with an aqueous solvent having a pH in the range of 4 to 9, and the immobilized heavy metals are stable. In that they do not elute from the system.
[0185]
At this time, in order to evaluate the state of not decomposing even when contacted with an aqueous solvent having a pH in the range of 4 to 9, the following three kinds of heavy metal elution test methods were used.
(1) Environmental Agency Notification No. 46 Dissolution Test [abbreviation: pH 7 dissolution test:]
(2) NEN 7341 dissolution test method in the Netherlands [abbreviation: pH 4 dissolution test method:]
(3) Dissolution test method using alkaline solution [abbreviation: pH 9 dissolution test method:]
[0186]
Furthermore, a feature of the present invention is that the immobilization material (S) is added to the contaminated soil via water to form a plastic or fluid admixture and subjected to the immobilization treatment step, whereby the contaminated soil is not hardened and solidified. It is to be treated soil that shows deformability due to external pressure. As a means for evaluating the deformed treated soil at this time, a "standard penetration test" carried out in the civil engineering and ground industries is standard.
[0187]
However, the "standard penetration test" is a test method in the civil engineering industry for obtaining an N value that is a guideline for knowing the relative hardness and tightness of the soil. The standard penetration test is specified in JIS A1219 1995 and uses a bowling hole. Then, a rod attached with a standard test sampler having a diameter of 5.1 cm and a length of 81 cm at the tip of the rod is freely dropped from a height of 75 cm with a hammer having a mass of 63.5 kg, and the impact required to penetrate the sampler by 30 cm. This is a test method for measuring the number N (N value).
[0188]
Therefore, the "standard penetration test" is a method of measuring using a bowling hole at the original ground position, and is suitable for practical use. However, since it is not suitable for evaluating small-scale treated soils to be tested, in the present invention, a simplified type of the following physical property evaluation test method is used as an alternative to the standard penetration test. "Deformability measurement test" was adopted.
[0189]
The strength of the treated soil treated according to the present invention measured by the deformability measurement test method was 80 N / cm.²Or less, preferably 50 N / cm²In the following cases, the treated soil exhibited deformability, and was not hardened and solidified as in the case of general soil. Incidentally, the upper limit N value 50 in the soil ground measured by the “standard penetration test” is about 80 N / cm in this deformability measurement test.²Is equivalent to
[0190]
[Physical property evaluation test method of the present invention]
The main composition analysis in the soil adopted in the present invention was based on the method for investigating sediment sediment in soil analysis method II, and the analysis of the main component was performed by X-ray fluorescence analysis. The trace heavy metals were based on the analysis method shown in the method for investigating sediment. Further, the dissolution test of heavy metals was performed according to the dissolution test method in each pH range shown below.
[0191]
Handling of collected soil [common]
Store the collected soil in a glass container or a container that does not adsorb the substance to be measured. The test is performed immediately after sampling the soil. If the test cannot be performed immediately, store it in a dark place and perform the test as soon as possible.
[0192]
(1) Dissolution Test Method No. 46 of the Notification of the Environment Agency (excerpt) [Abbreviated name: Dissolution test method for pH7:]
1-1 Preparation of sample
The collected soil is air-dried to remove small and medium gravels, wood chips, and the like, and after crushing the lumps and aggregates, the soil obtained by passing through a nonmetallic 2 mm sieve is sufficiently mixed.
1-2 Preparation of sample solution
A sample (unit g) and a solvent (purely added with hydrochloric acid so that the hydrogen ion concentration index becomes 5.8 or more and 6.3 or less) (unit) are mixed at a weight / volume ratio of 10%, In addition, the mixed liquid is adjusted to 500 mL or more.
[0193]
1-3 Leaching
The prepared sample solution is shaken at room temperature (about 20 ° C.) and normal pressure (about 1 atm) using a shaking machine (shaking frequency is set to about 200 times per minute and shaking width is adjusted to 4 cm or more and 5 cm or less). And shake continuously for 6 minutes.
1-4 Preparation of test solution
After the sample solution obtained by performing the above operation is allowed to stand for about 10 to 30 minutes, and centrifuged at about 3,000 rpm for 20 minutes, the supernatant is filtered through a membrane filter having a pore size of 0.45 μm. Take the filtrate, measure accurately the amount required for quantification, and use this as the test solution.
[0194]
(2) NEN 7341 dissolution test method in the Netherlands (excerpt) [abbreviation: pH 4 dissolution test method:]
2-1 Preparation of sample
The collected soil is air-dried to remove small and medium gravels, wood chips, and the like, and after crushing the lumps and aggregates, the soil obtained by passing through a nonmetallic 2 mm sieve is sufficiently mixed.
[0195]
2-2 Preparation of sample solution
800 g of distilled water is added to 16 g of the sample, and the mixture is stirred for 3 hours while maintaining the pH at 7 with 1 mol / l nitric acid. Next, the solution is filtered through a membrane filter having a pore size of 0.45 μm to obtain a filtrate, and an amount necessary for quantitative determination is accurately measured and used as a pH 7 eluate. Further, 800 g of distilled water is added to the filtration residue eluted at pH 7 and stirred for 3 hours while maintaining the pH at 4 with 1 mol / l nitric acid. Next, the solution is filtered through a membrane filter having a pore size of 0.45 μm to obtain a filtrate, which is used as a pH 4 eluate.
2-3 Preparation of test solution
The pH 7 eluate and the pH 4 eluate obtained by performing the above operations are added and mixed, and the amount necessary for quantification is accurately measured and used as a test solution.
[0196]
(3) Dissolution test method using alkaline solution [abbreviation: pH 9 dissolution test method:]
3-1 Preparation of sample
The collected soil is air-dried to remove small and medium gravels, wood chips, and the like, and after crushing the lumps and aggregates, the soil obtained by passing through a nonmetallic 2 mm sieve is sufficiently mixed.
3-2 Preparation of sample solution
800 g of distilled water is added to 16 g of the sample, and the mixture is stirred for 3 hours while maintaining the pH at 9 with a 1 mol / l sodium hydroxide solution. Subsequently, the solution is filtered through a membrane filter having a pore size of 0.45 μm to obtain a filtrate, which is used as a pH 9 eluate.
2-3 Preparation of test solution
The amount necessary for quantification of the pH 9 eluate obtained by performing the above operation is accurately measured and used as a test solution.
[0197]
Detection method of each heavy metal:
Cd JIS K0102 1998 55.3 ICP emission spectroscopy
Pb JIS K0102 1998 54.3 ICP emission spectroscopy
Cr JIS K 0102, 1998 65.2.1 ICP diphenyl
Carbazide spectrophotometry
As JIS K 0102 ・ 1998 61.2 ICP hydride generation atomic absorption spectrophotometry
Hg @ Methods listed in Appendix 1 of Notification No. 59 of the Environment Agency, December 1971
[0198]
Simplified deformation test method:
In order to evaluate the deformability of the treated soil according to the present invention, a simple type deformability measurement test was adopted instead of the “standard penetration test”. In this test, the admixture of the present invention was prepared in a cylindrical test specimen (φ5 × 10 cm: n = 3), basically in accordance with the description of JSCE F 506 and JSCE G 505 adopted in the mortar test. After leaving the container at room temperature for 7 days in a closed state, it was measured by a uniaxial compressive breaking strength test.²It was measured and displayed in units.
[0199]
【Example】
In the present embodiment, the immobilizing agent (S) is added to the soil contaminated with heavy metals to form a mixture, and the heavy metals contained in the contaminated soil are immobilized to be insoluble in an aqueous solvent having a pH of 4 to 9. A concrete example of the heavy metal-fixing material (S) which is transformed into a compound to transform into a deformable treated soil and a method for treating contaminated soil will be described. The present invention is not limited to this embodiment.
[0200]
[Example 1]
In the present embodiment, each component constituting the composite composition (PS) [active silica (SS), reactive alumina (SA), sodium hydroxide (SN), calcium composition (SC), addition replenishment composition (ST) )], And the immobilization material (S) prepared with each component, the immobilization of heavy metals containing contaminated soil by the further prepared immobilization material (S), and the deformability indicating the state of the treated soil.
[0201]
Examples of the active silica (SS) as a raw material for preparing the composite composition (PS & LS) include finely divided amorphous silica manufactured by sodium silicate [Mizukasil, manufactured by Mizusawa Chemical Industry Co., Ltd.] and natural clay minerals. A smectite clay mineral, which is a ferrosilicate having a layered structure, is selected from the group consisting of acid clay of a 2-octahedral montmorillonite family and water glass No. 3 [sodium silicate] of JIS standard products. It is also shown in Table 2.
[0202]

[0203]
As reactive alumina (SA), aluminum hydroxide (Al) widely used as an industrial chemical₂O₃: SA-1). I chose.
Further, as the calcium composition (SC) in which sodium hydroxide (SN) caustic soda (NaOH: SN-1) is selected, powders such as commercially available reagents, industrial chemicals, and processed products of wastes are selected. The components are shown together in Table 2.
[0204]

[0205]
As the additional auxiliary composition (ST) as a compounding raw material of the composite composition (PS & LS), a commercially available reagent, an industrial chemical, a waste, and a powder of a synthetic product shown below were selected.
As the crystal seed composition (ST1), a 4A type powder of an aluminosilicate, an industrial chemical, having an Al / Si atomic ratio of 4.2, a ring number of 8, and a secondary particle size of 20 μ or less was selected.
[0206]
As the sulfate group composition (ST2), sodium sulfate, iron sulfate, aluminum sulfate and potassium alum were selected from commercially available reagents and industrial chemicals. Silicon phosphate {[SiO] as phosphate group composition (ST3)_2:: P₂O₅Molar ratio = 3.0: 1.0950 ° C., baked and pulverized product], sodium phosphate, zinc phosphate and phosphate sludge [main component (% by mass): iron phosphate 25.0 zinc phosphate 7.5 silica] 10.5 alumina 8.4 moisture 35.0].
As the barium salt composition (ST4), barium silicate [BaO: SiO_2:Molar ratio = 1.0: 1.0 250 ° C. reaction / crushed product], and barium hydroxide.
[0207]
Iron (II) oxide was selected as the iron salt supplement composition (ST5). As the supporting auxiliary composition (ST6), silica gel, aluminum gel and carbon-aluminum silicate composite having adsorptivity [main component (% by mass): C: 25.5} SiO₂35.6 Al₂O₃27.5 {CaO} 11.4].
The main chemical composition of the selected addition auxiliary composition (ST) is also shown in Table 4.
[0208]

[0209]
The immobilizing material (S) of the present embodiment is selected from the above-mentioned activated silica (SS), reactive alumina (SA), sodium hydroxide (SN), calcium hydroxide composition (SC) and addition auxiliary composition (ST). The kinds and amounts shown in Table 5 were homogeneously mixed, and a four-component or five-component essential one-pack powder composite composition (PS) was prepared and used as a sample.
[0210]

[0211]
As the contaminated soil adopted in this example, two types, soil A and soil B, which were on the site of the factory, were selected. Table 6 shows the water content and main components (dry matter basis) of soil A and soil B, and the content of contaminated heavy metals. In this example, the purified contaminated soil from which the miscellaneous substances (tree pieces, vegetation, sand, gravel, etc.) coexisting in the contaminated soil were classified and removed was used as a sample.
[0212]

[0213]
In the immobilization treatment step of the present invention, a stainless steel 20-liter container equipped with a beater-type stirrer (rotational speed: 205 rpm), which is a pre-mixing method, was used as a mixing device adopted for the preparation of the mixture. A mortar mixer (manufactured by Aikosha Seisakusho: Mighty 30 (model MT-30 / 20)) as a main body was selected.
[0214]
The mixture in this example was prepared by moving 4 kg of contaminated soil into a mortar mixer container, and then into the mortar mixer container into which the contaminated soil was charged, from among the powder fixing materials (S) shown in Table 5, sample No. S-1. Two methods, one in which 1 kg of the immobilizing material (S) and 1 kg of water are added in two stages, and the other method in which 1 kg of the immobilizing material (S) of sample number S-1 is prepared in a slurry form in advance with 1 kg of water and added in one stage , And stirred for 60 seconds to prepare a plastic mixture shown in Table 7.
[0215]
The prepared plastic mixture is taken in a sealed container and left to cure at room temperature for 24 hours to obtain four types of treated soils shown in Table 7.
The prepared four types of treated soils were subjected to a pH 4 dissolution test, a pH 7 dissolution test and a pH 9 dissolution test to evaluate the immobilization status of contained heavy metals. In addition, a simple type deformability measurement test was performed to evaluate the deformability of the treated soil with respect to the external pressure. The results are also shown in Table 8.
[0216]

[0219]
As a comparative example of the present invention, a case where portland cement, which is widely used in place of the fixing material (S) of the present invention, was used as a treated soil under the same treatment conditions as those shown in Table 7 was used as a comparative example. Untreated contaminated soil without the immobilizing material (S) of the present invention was also used as a comparative example. The soil of each comparative example was subjected to each dissolution test, and comparative evaluation with the present invention was performed. The results are also shown in Table 8.
[0218]

[0219]
For reference, analysis in the dissolution test of heavy metals [cadmium (Cd), lead (Pb), hexavalent chromium (Cr), arsenic (As), and total mercury (T-Hg)] performed in this example. The lower limit of quantification and the environmental standard values indicated by the Ministry of the Environment are shown in Table 9 for reference.
[0220]

[0221]
As a result, as compared with the untreated soil and the treated soil using cement as the immobilizing material, the treated soil in which the contaminated soil was immobilized with the immobilizing material (S) according to the present invention had a pH of 4 adjusted with nitric acid. In the dissolution test with the above solution, the dissolution test in neutral pH 7 water and the dissolution test of alkali, the contained heavy metals, especially chromium, are also immobilized and do not elute, and the treated soil is deformable against external pressure. Is well understood.
[0222]
[Example 2]
In this example, the fixing materials (S) shown in Table 5 of Example 1 were adopted, and heavy metals when contaminated soil was subjected to the immobilization treatment of heavy metals containing contaminated soil by a mixing device using a pre-mixing method. The state of immobilization and the deformability of the treated soil will be described.
[0223]
For the immobilization process, a mortar mixer mixing device [Mighty 30 (type MT-30 / 20)], which is a pre-mixing method shown in Example 1, was selected.
The admixture in this example is shown in Table 10 in which the soil A or soil B, which is the contaminated soil shown in Example 1, the immobilizing material (S) shown in Table 5 of Example 1, and water are mixed in a mortar mixer container. The mixture was charged at a fixed rate and then stirred for 60 seconds to prepare a plastic admixture.
[0224]

[0225]
The prepared plastic mixture is taken in a sealed container and left to cure at room temperature for 24 hours to obtain a treated soil.
The prepared treated soil was subjected to a pH 4 dissolution test, a pH 7 dissolution test and a pH 9 dissolution test to evaluate the immobilization status of the contained heavy metals. In addition, a simple type deformability measurement test was performed to evaluate the deformability of the treated soil with respect to the external pressure. The results are also shown in Table 10.
[0226]
As a result, the treated soil subjected to the immobilization treatment of the present invention by the premixing device using the various immobilizing materials (S) shown in the present embodiment by the premixing method was dissolved in each of pH4, pH7, and pH9. It is well understood that the heavy metals contained in the test were immobilized as an unelutable compound, and that the treated soil was transformed into a soil having deformability against external pressure.
[0227]
[Example 3]
In the present embodiment, various fixing materials (S) shown in Table 5 of Example 1 were adopted, subjected to a fixing treatment step by a mixing device using a pre-mixing method, and treated soil in which contained heavy metals were fixed. The deformability of the treated soil will be described.
[0228]
For the immobilization process, a mortar mixer mixing device [Mighty 30 (type MT-30 / 20)], which is a pre-mixing method shown in Example 1, was selected.
The admixture in this example was prepared by mixing soil B, which is the contaminated soil shown in Example 1, immobilizing material (S) shown in Table 5 of Example 1, and water in a mortar mixer container in the amount ratio shown in Table 11. The mixture was charged and then stirred for 60 seconds to prepare each plastic mixture.
[0229]
The prepared plastic mixture is taken in a sealed container and left to cure at room temperature for 24 hours to obtain a treated soil. The prepared treated soil was subjected to a pH 4 dissolution test, a pH 7 dissolution test and a pH 9 dissolution test to evaluate the immobilization status of the contained heavy metals. In addition, a simple type deformability measurement test was performed to evaluate the deformability of the treated soil with respect to the external pressure. The results are also shown in Table 11.
[0230]

[0231]

[0232]
As a result, the treated soil subjected to the immobilization treatment of the present invention by the premixing device using the various immobilizing materials (S) shown in the present embodiment by the premixing method was dissolved in each of pH4, pH7, and pH9. It is well understood that the heavy metals contained in the test were immobilized as an unelutable compound, and that the treated soil was transformed into a soil having deformability against external pressure.
[0233]
[Example 4]
In this embodiment, the immobilizing material (S) shown in Example 1 was added to the contaminated soil at the original position of the contaminated soil by a mixing device using an excavation stirring method, a mechanical stirring method, and a high-pressure injection method to add the fixing material (S) shown in Example 1 to the contaminated soil. The immobilization status of heavy metals and the deformability of the treated soil in the mixing process will be described.
[0234]
Table 12 shows the heavy metals contained in the contaminated soil C at the original position (depth about 2 m) where the heavy metals were immobilized by the excavation stirring method, the mechanical stirring method, and the high-pressure injection method in this example.

[0235]
As the excavating and stirring system, a stirrer-type mining-type and stirrable device [TOYO SRABI manufactured by Toyo Stabilizer Co., Ltd.] is used to excavate and stir to a depth of about 1 m at the original position of contaminated soil C. The soil particles and the slurry-like immobilizing material (S) shown in Table 13 were stirred and mixed in situ, and then left to cure for 24 hours. A sample of the treated soil was taken in a sealed container.
[0236]
As a mechanical stirring system device, a NAS100 type auger pile driver with a rated output of 180 ps / 2100 rpm and an auger motor output of 75 kW class with a three-point pile driver is used for in-situ soil with a depth of about 1 m or more at the in-situ location of contaminated soil C. The soil particles and the slurry-like fixing material (S) shown in Table 13 were stirred and mixed by a mechanical stirring method, and then left to cure in situ for 24 hours. Then, take it in a sealed container as a test body and use it as a sample of the treated soil.
[0237]
As a high-pressure injection system, a high-pressure plunger is a set of high-pressure plungers that injects high-pressure from a rotary nozzle generally used as the CCP-L method and makes uniform contact within the effective diameter of φ300 or 500 in the deep part of the ground, and has a horsepower of 7.5 kW. By the injection method, the soil particles and the slurry-like fixing material (S) shown in Table 13 are stirred and mixed in the in-situ soil having a depth of about 1 m or more in the in-situ contaminated soil C by the high-pressure injection method. After curing for 24 hours, the mixed product obtained by the mixing process is collected by a boring method and taken as a test sample in a sealed container to obtain a sample of the processed soil.
[0238]
Further, as a high-pressure injection type apparatus capable of performing the powder injection stirring method, a stirrer (S) generally used as a DJM method can be transported to a deep portion of the ground by an air flow. This is a high-pressure powder injection type with a standard stirring blade diameter of 1,000 mm and a motor output of 90 kW x 2 units. The powdered immobilizing material (S) shown in Table 13 was stirred and mixed, then left to cure in situ for 24 hours, and then the mixed treated product was collected by a boring method and sealed as a test specimen. And used as a sample of treated soil.
[0239]
According to this example, the treated soil treated by the mixing device using the excavation stirring method, the mechanical stirring method, and the high-pressure injection method was respectively bored and collected as test specimens, and subjected to the pH4 dissolution test, the pH7 dissolution test, and the pH9 dissolution test. The immobilization status of the heavy metals contained was evaluated. In addition, a simple type deformability measurement test was performed to evaluate the deformability against an external pressure. The results are shown in Table 13.
[0240]

[0241]
As a result, the immobilizing material (S) of the present invention was mixed with a slurry or a powder in an in-situ contaminated soil by a mixing device using a drilling stirring method, a mechanical stirring method, and a high-pressure injection method, respectively. Soil shall be immobilized with heavy metals contained as non-eluting compounds in pH4 dissolution test, pH7 dissolution test and pH9 dissolution test, and treated soil shall be transformed into soil which is deformable to external pressure. Is well understood.
[0242]
【The invention's effect】
The effect of the present invention is that the harmful heavy metals contained in the contaminated soil are fixed as an insoluble compound in an aqueous solvent having a pH of 4 to 9 and are transformed into a deformable treated soil. In addition to preventing the situation where harmful heavy metals that affect the health of the system and humans are washed away into groundwater veins, rivers and seas, and secondary pollution to a wide area of living environment, not only can environmental problems be solved, It can contribute to effective utilization.

Claims (17)

The contaminated soil containing heavy metals is subjected to an immobilization treatment step, and the heavy metals in the treated soil are immobilized as an insoluble compound that does not elute in an aqueous solvent having a pH of 4 to 9, and the treated soil is exposed to an external pressure. The heavy metal-fixing material (S), which is soil that exhibits deformability;
The above fixing material (S) is 50 to 200 parts by mass of reactive alumina (SA) and 15 to 80 parts by mass of sodium hydroxide (SN) based on 100 parts by mass of active silica (SS) having a silanol group. Powder and one-pack composite composition (PS) in which the essential four components are added in an amount of from 20 to 300 parts by weight, and 20 parts to 300 parts by weight of the calcium carbonate composition (SC);
In the immobilization treatment step, 5 to 30 parts by mass of the immobilizing material (S) and 10 to 140 parts by mass of water are homogeneously mixed with 100 parts by mass of the contaminated soil on a dry matter basis. Forming a plastic or fluid admixture which is formed and then leaving the admixture at 2 to 40 ° C. for at least 24 hours to obtain treated soil;
By the above-mentioned immobilization treatment step, the heavy metals contained in the contaminated soil are immobilized as zeolites, which are basic salt compounds of aluminosilicic acid, to be transformed into a treated soil that is not eluted in an aqueous solvent having a pH in the range of 4 to 9. A heavy metal-fixing material, characterized in that the treated soil at that time is a fixing material (S) which is a soil exhibiting deformability due to external pressure. In the activated silica (SS) having a silanol group, which is a component of the fixing material (S);
The active silica (SS) is a layered clay mineral of ferrosilicate having silica (SiO ₂ ) as a main component, amorphous silicic acid (SS1), alkali silicate (SS2), and aluminum silicate as a main skeleton. (SS3) and an alkali-modified silicate (SS4) group having a silanol group by reacting sodium hydroxide with silicic acid or silicate, or a combination of two or more selected from the group. The material for immobilizing heavy metals according to claim 1. In the activated silica (SS) having a silanol group, which is a component of the fixing material (S);
The said reactive alumina (SA) is comprised alone or in combination of 2 or more types selected from the group consisting of aluminum oxide, aluminum hydroxide, sodium aluminate and alkaline earth metal aluminate. Heavy metals fixing material. In the calcium composition (SC), which is a component of the fixing material (S);
The above-mentioned calcia composition (SC) is calcia standard composition (SC1), oxyacid salt composition (SC2), halogen salt composition (SC3), waste powder composition (SC4), cement powder composition The heavy metal according to any one of claims 1 to 3, wherein the heavy metal is composed of one or a combination of two or more selected from the group consisting of (SC5), an alkali-modified composition (SC6), and a carbonic acid-modified composition (SC7). Class immobilization material. The above-mentioned immobilizing material (S) is homogeneously mixed with the essential four components, and the powdery one is homogeneously mixed with the five components obtained by adding the additional auxiliary composition (ST) to the composite one (PS). In a pack composite composition (PS);
The powder addition auxiliary composition (ST) comprises a crystal seed composition (ST1), a sulfate group composition (ST2), a phosphate group composition (ST3), a barium salt composition (ST4), and an iron salt replenishing composition (ST4). ST5), a powder composition which is composed of one or a combination of two or more selected from the group consisting of a supporting auxiliary composition (ST6) and a dispersion medium composition (ST7) and which has an auxiliary function.
The above-mentioned immobilizing material (S) is added in an amount of 1 to 200 parts by mass with the addition auxiliary composition (ST) to 100 parts by mass of the composite composition (PS) in which the essential four components are homogeneously mixed. The heavy metal fixing material according to any one of claims 1 to 4, comprising a five-component powdery one-pack composite composition (PS) that is homogeneously mixed. In a one-pack composite composition (PS) in which the immobilizing material (S) is homogeneously mixed with four essential components and five additional auxiliary compositions (ST);
The above powdery one-pack composite composition (PS) contains 50 to 100 parts by mass of reactive alumina (SA) as sodium aluminate with respect to 100 parts by mass of active silica (SS) as sodium silicate of each powder. , A powdery one-pack composite in which 20 to 80 parts by weight of calcium silicate (SC) and 25 to 75 parts by weight of a natural zeolite crystalline seed composition (ST1) are homogeneously mixed. The heavy metal-fixing material according to claim 5, which is composed of a composition (PS). In a one-pack composite composition (PS) in which the immobilizing material (S) is homogeneously mixed with four essential components and five additional auxiliary compositions (ST);
The powdery one-pack composite composition (PS) is prepared by adding 50 to 100 parts by mass of reactive alumina (SA), which is aluminum hydroxide, to 100 parts by mass of active silica (SS), which is the acid clay of each powder. , 15 to 80 parts by weight of sodium hydroxide (SN), 20 to 80 parts by weight of calcium composition (SC) as blast furnace slug and 25 to 75 parts by weight of crystalline seed composition (ST1) as natural zeolite. The heavy metal-fixing material according to claim 1 or 5, which is composed of a powdery one-pack composite composition (PS) that is homogeneously mixed in (1). The above-mentioned heavy metal-fixing material (S) is obtained by adding water to the essential four-component or five-component powdery composite composition (PS) and preparing a slurry-like composite composition (LS In);
A slurry composite composition which is previously prepared into a homogeneous slurry by adding water in an amount of 60 to 120 parts by mass with respect to 100 parts by mass of the powdery composite composition (PS) of the essential four or five components. The heavy metal-immobilizing material according to any one of claims 1 to 7, comprising a material (LS). The heavy metal-immobilizing material (S) according to any one of claims 1 to 8, which is subjected to a mixing device for bringing the contaminated soil into uniform contact with the contaminated soil via water to obtain a plastic or fluid admixture. In the method of treating contaminated soil, which cures the immobilized heavy metals to insoluble compounds by the immobilization treatment step to form a deformable treated soil;
The above-described mixing device is a mixing device of a pre-mixing method mainly including a container including a rotary driving body having a stirring blade;
The above-mentioned pre-mixing method is to transfer the mined contaminated soil to a mixing device, and furthermore, add and fix a predetermined amount of the immobilizing material (S) and, if necessary, water, and stir and mix the plastic or fluid. A method of forming a sex admixture;
The above-mentioned method for treating contaminated soil fixes the heavy metals contained as zeolites, which are basic salt compounds of aluminosilicate, and immobilizes them on compounds insoluble in aqueous solvents having a pH of 4 to 9 to improve the deformability. A method for treating contaminated soil, characterized in that it is a method for treating soil as indicated. In the plastic admixture formed by stirring and mixing the contaminated soil, the immobilizing material (S), and the water with the premixing device,
The above-mentioned plastic admixture is stirred and mixed in an amount ratio of 5 to 30 parts by mass of the immobilizing material (S) and less than 60 parts by mass of water to 100 parts by mass of the contaminated soil containing heavy metals on a dry matter basis. 10. The method for treating contaminated soil according to claim 9, wherein the method is a method for granulating into granules having a diameter of 0.5 to 35 mmφ, drying as necessary, and transforming into deformable treated soil. A fluid mixture formed by mixing and mixing the contaminated soil, the fixing material (S) and the water with the premixing-type mixing device;
The above-mentioned fluid mixture is stirred at a ratio of 5 to 30 parts by mass of the immobilizing material (S) and 60 to 140 parts by mass of water with respect to 100 parts by mass of the contaminated soil containing heavy metals on a dry matter basis. 10. The method for treating contaminated soil according to claim 9, wherein the soil is mixed and then moved to the original or mined location using fluidity to be transformed into deformable treated soil. The above-mentioned mixing device is a device of an excavation stirring type capable of moving the target ground;
The above-mentioned excavation and agitation method is a method of adding a predetermined amount of the immobilizing material (S) and, if necessary, water to contaminated soil on the in-situ surface layer of less than 1 m of the ground surface, and stirring and mixing while excavating the soil. A method of forming a sexual mixture;
10. The method for treating contaminated soil according to claim 9, wherein said plastic or fluid mixture is a method of altering the deformable treated soil. The mixing device is a device of a mechanical stirring type centering on a deep part of a target ground;
The above-mentioned mechanical stirring method forms a plastic or fluid admixture by making the slurry-like fixing material (S) penetrate into the deeply contaminated soil at a depth of 1 m or more from the ground surface and mechanically stirring and mixing. Method;
10. The method for treating contaminated soil according to claim 9, wherein said plastic or fluid mixture is a method of altering the deformable treated soil. The above-mentioned mixing device is a device of a high-pressure injection system centering on a deep part of the target ground;
The above-mentioned high-pressure injection method is a method of forming a plastic or fluid admixture by injecting a high-pressure slurry-type immobilizing material (S) into deep contaminated soil at a depth of 1 m or more from the ground surface and mixing with stirring. Yes;
10. The method for treating contaminated soil according to claim 9, wherein said plastic or fluid mixture is a method of altering the deformable treated soil. The high-pressure injection type device injects the powdery fixing material (S) using compressed air as a moving medium toward the deep contaminated soil at a depth of 1 m or more from the ground surface, and mixes and agitates the powder. 15. The method for treating contaminated soil according to claim 14, which is a device for discharging the sent air to the ground. In complex contaminated soil, wherein said contaminated soil is contaminated with organic substances in addition to heavy metals;
The method for treating contaminated soil according to any one of claims 1 to 15, wherein the composite contaminated soil is a contaminated soil that has been subjected to a pretreatment for preliminarily decomposing and removing contained organic substances by heating. In a deformable treated soil in which the treated soil is immobilized as a zeolite containing heavy metals and transformed into a compound insoluble in an aqueous solvent having a pH of 4 to 9;
17. The deformable treated soil which has been subjected to a simple type deformability measurement test and has been transformed into a treated soil exhibiting deformability due to external pressure having a strength value of 80 N / cm ² or less. The method for treating contaminated soil according to claim 1.