JP2004182559A

JP2004182559A - Method of manufacturing hydrothermally hardened body

Info

Publication number: JP2004182559A
Application number: JP2002353581A
Authority: JP
Inventors: Hiroteru Maenami; 洋輝前浪; Hideaki Tanaka; 英昭田中; Noribumi Isu; 紀文井須; Hideki Ishida; 秀輝石田
Original assignee: Inax Corp
Current assignee: Inax Corp
Priority date: 2002-12-05
Filing date: 2002-12-05
Publication date: 2004-07-02
Anticipated expiration: 2022-12-05
Also published as: JP4340058B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a hydrothermally hardened body from a raw material containing Al<SB>2</SB>O<SB>3</SB>. <P>SOLUTION: A mix comprising raw materials containing SiO<SB>2</SB>, Al<SB>2</SB>O<SB>3</SB>, and CaO is prepared. The mix is shaped to give a formed body. The formed body is hydrothermally treated to obtain the hydrothermally hardened body. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、Ａｌ_２Ｏ_３分を含む原料からなる水熱固化体の製造方法に関する。
【０００２】
【従来の技術】
従来、ＣａＯ分とＳｉＯ_２分とを含む原料から、水熱固化体を製造する方法は知られている（例えば、特許文献１参照。）。この製造方法では、まず調合工程として、ＣａＯ分とＳｉＯ_２分とを含む原料により調合物を用意する。そして、成形工程として、調合物を成形して成形体とする。次いで、水熱工程として、その成形体を水熱処理し、ケイ酸カルシウムを生じて固化した水熱固化体を得る。こうして得られる水熱固化体は、タイル等の建材として実用価値がある。
【０００３】
【特許文献１】
特許第３１９６６１１号公報
【０００４】
【発明が解決しようとする課題】
しかし、種々の原料により水熱固化体を製造することができれば、原料の安定供給、製品コスト等の面で好ましいにもかかわらず、従来の技術ではＡｌ_２Ｏ_３分を含む原料からは水熱固化体を製造することができなかった。
【０００５】
本発明は、上記従来の実情に鑑みてなされたものであって、Ａｌ_２Ｏ_３分を含む原料から水熱固化体を製造することを特徴とする解決すべき課題としている。
【０００６】
【課題を解決するための手段】
発明者らは、本発明の契機として、各種無機系廃棄物の水熱固化による再資源化を検討した。すなわち、各種無機系廃棄物のうち、排出量が多いものとして、汚泥が知られている。汚泥はその発生プロセスにおいて、ポリ塩化アルミニウム（ＰＡＣ）による凝集沈殿が用いられる場合が多く、ＰＡＣを中和する過程で生成する水酸化アルミニウム（Ａｌ（ＯＨ）_３）を多量に含む場合が多い。水酸化アルミニウムは水熱反応性が高いことが知られているものの、汚泥中の水酸化アルミニウムが水熱固化に及ぼす影響は従来から明らかにされていない。このため、発明者らは、Ａｌ成分を多量に含む汚泥の再資源化を図るため、浄水場で発生する汚泥である浄水汚泥の水熱固化について検討し、本発明を完成させるに至った。
【０００７】
本発明の水熱固化体の製造方法は、ＳｉＯ_２分及びＡｌ_２Ｏ_３分を含む原料からなる調合物を用意する調合工程と、該調合物を成形して成形体とする成形工程と、該成形体を水熱処理して固化した水熱固化体を得る水熱工程とを有することを特徴とする。
【０００８】
本発明の製造方法では、Ａｌ_２Ｏ_３分を含む原料から水熱固化体を製造することができる。このため、従来にも増して種々の原料により水熱固化体を製造することができ、原料の安定供給、製品コスト等の面で好ましい。
【０００９】
調合物は、Ａｌ_２Ｏ_３分の一部又は全てが水酸化アルミニウムであることが好ましい。水酸化アルミニウムは水への溶解度が高く、水熱処理時の反応性が高いためである。また、これにより汚泥の再資源化を実現することができる。
【００１０】
ＳｉＯ_２分は、珪砂、ガラス粉、石英粉、シリカフューム、廃鋳物砂、籾殻灰、珪藻土、ホワイトカーボン、コンクリート屑、シラス、白土等により構成することができる。Ａｌ_２Ｏ_３分は、長石、粘土、キラ、陶磁器屑、石炭灰、下水汚泥焼却灰、アルミサッシ工場等で発生する水酸化アルミニウムスラッジ、赤泥、スラグ、釉汚泥、メタカオリン、アロフェン、ゼオライト等により構成することができる。また、ＳｉＯ_２分及びＡｌ_２Ｏ_３分を含む原料としては、長石、粘土、ガラス粉、廃鋳物砂、コンクリート屑、シラス、白土、キラ、陶磁器屑、石炭灰、下水汚泥焼却灰、赤泥、スラグ、釉汚泥、メタカオリン、アロフェン、ゼオライト等の他、ＰＡＣを用いて処理された汚泥を採用することができる。第１原料として、ＰＡＣを用いて処理された汚泥を採用すれば、再資源化を実現することができる。
【００１１】
調合物はＣａＯ分を含み得る。ＣａＯ分は消石灰（Ｃａ（ＯＨ）_２）等により構成することができる。発明者らは、調合工程では、ＳｉＯ_２分及びＡｌ_２Ｏ_３分を含む第１原料と、ＣａＯ分を含む第２原料とを混合した調合物を用意し、第１原料はＰＡＣを用いて処理された汚泥であり、第２原料は消石灰である場合に本発明の効果を確認した。
【００１２】
第１原料は、ＰＡＣを用いて処理された汚泥を加熱処理したものであることが好ましい。加熱処理により水熱固化に不必要な有機分を除去することができる。また、加熱処理により水分量がほとんどないものになるため、成形及び水熱固化に必要な水分を調整し易く、水熱固化体をより製造し易いからである。加熱処理後の汚泥を湿式粉砕すれば、汚泥中のアルミナ分が再水和し、成形及び水熱固化に必要な水分の調整をより行い易くなる。また、粉砕により汚泥の粒径が小さくなり、反応性が向上する。
【００１３】
発明者らは、調合物が１０質量％以下の第２原料と残部の第１原料とが混合されたものである場合に本発明の効果を確認した。
【００１４】
成形工程を乾式プレス法により行なうことが好ましい。これにより、原料の搬送、保管が容易になる。また、水熱固化に必要な水分を調整した成形体を成形することができ、成形体の乾燥を行なうことなく水熱固化体を製造することができる。これらのため、製造コストの低廉化を実現できる。また、乾式プレス法により成形すれば、原料粒子間の距離が小さくなり、水熱処理で生成する組織を数〜数十ｎｍサイズにして強度発現を効率よく行うことができる。
【００１５】
発明者らは、水熱固化体がＡｌ／Ｓｉ（モル比）＝０．９〜１．５の組織を有して固化していることを確認している。この組織は、数〜数十ｎｍサイズの微細なものであり、アモルファスの可能性もある。このため、Ａｌ／Ｓｉ（モル比）＝０．９〜１．５になるように調合工程を行なうことが好ましいこともわかる。
【００１６】
【発明の実施の形態】
以下、本発明を具体化した実施形態を図面を参照しつつ説明する。
【００１７】
この実施形態では、浄水場で発生する汚泥である浄水汚泥の水熱固化について、調合及び水熱処理温度が水熱固化体の強度発現に及ぼす影響を検討する。
【００１８】
まず、図１に示す調合工程Ｓ１０として、ＰＡＣを用いて処理された浄水汚泥と、宇部マテリアル（株）製の消石灰とを用意する。浄水汚泥は、浄水場で発生した汚泥をフィルタープレスにより脱水した後、乾燥したものである。この浄水汚泥の化学組成を表１に示す。また、この浄水汚泥の構成相をＸＲＤチャートにより図２に示す。図２において、Ｑはｑｕａｒｔｚ（ＳｉＯ_２）であり、Ｍはｍｕｓｃｏｖｉｔｅ（ＫＡｌ_２（Ｓｉ_３Ａｌ）Ｏ_１０（ＯＦ，Ｆ）_２）であり、Ａはａｌｂｉｔｅ（ＮａＡｌＳｉ_３Ｏ_８）であり、Ｃｌはｃｌｉｎｏｃｈｌｏｒｅ（（Ｍｇ，Ａｌ）_６（Ｓｉ，Ａｌ）_４Ｏ_１０（ＯＨ）_８）であり、Ｋはｋａｏｌｉｎｉｔｅ（Ａｌ_２Ｓｉ_２Ｏ_５（ＯＨ）_４）である（以下、同様。）。なお、浄水汚泥はＰＡＣを用いて処理されているため、ＰＡＣを中和する過程で生成する水酸化アルミニウムを含むが、水酸化アルミニウムは非晶質であるため、ＸＲＤチャートでは、１５〜３５°のハロー（ブロードなバックグラウンドの盛り上がり）として認められる。
【００１９】
【表１】

【００２０】
浄水汚泥の有機分除去のための前処理として、浄水汚泥を６００°Ｃで１０時間加熱処理する。加熱処理後の浄水汚泥をポットミルで４時間湿式粉砕し、乾燥する。これにより浄水汚泥中のアルミナ分が再水和し、成形及び水熱固化に必要な水分の調整が容易になる。また、粉砕により浄水汚泥の粒径が小さくなり、反応性が向上する。前処理前の浄水汚泥と、６００°Ｃで１０時間加熱処理後の浄水汚泥と、４時間の湿式粉砕及び乾燥後の浄水汚泥との構成相をＸＲＤチャートにより図３に示す。図２及び図３より、６００°Ｃの加熱処理でｋａｏｌｉｎｉｔｅが分解したものの、その他の鉱物はほとんど変化しないことがわかる。
【００２１】
湿式粉砕及び乾燥後の浄水汚泥を第１原料とし、この第１原料に第２原料としての消石灰が０〜２０質量％となるように加えるとともに、外割で３０質量％の蒸留水を加えて混合する。こうして各調合物を得る。
【００２２】
図１に示す成形工程Ｓ２０として、各調合物を乾式プレス法により成形圧力３０ＭＰａで１０ｍｍ×１５ｍｍ×４０ｍｍの直方体に一軸加圧成形し、各成形体を得る。成形体の曲げ強度は１ＭＰａ、成形体の嵩密度は１．０７（ｇ／ｃｍ^３）であった。
【００２３】
そして、水熱工程Ｓ３０として、各成形体に対し、１６０〜２２０°Ｃで６時間又は２２０°Ｃで１０時間の水熱処理を行なう。こうして、水熱固化体である各試験体を得る。各試験体の嵩密度は１．０８〜１．０９（ｇ／ｃｍ^３）であった。
【００２４】
こうして、この製造方法では、Ａｌ_２Ｏ_３分を含む原料から水熱固化体を製造することができる。このため、従来にも増して種々の原料により水熱固化体を製造することができ、原料の安定供給、製品コスト等の面で好ましいことが明らかである。
【００２５】
各試験体を８０°Ｃで２日間乾燥後、各試験体について、曲げ強度（３点曲げ試験法）、生成相（粉末Ｘ線回折）及び微構造（ＳＥＭ、水銀圧入法による細孔分布測定）を評価した。
【００２６】
２２０°Ｃで１０時間水熱処理した場合における消石灰の添加量（質量％）と曲げ強度（ＭＰａ）との関係を図４に示す。図４より、消石灰の添加量が５質量％の調合物を用いた試験体が最大の曲げ強度である１３．０ＭＰａを示すことがわかる。消石灰をこれより減少させたり、増加させたりした試験体は曲げ強度が低下している。消石灰が１０質量％以下（０質量％を含み、１０質量％以下）であれば、インターロッキングブロックの規格値である５ＭＰａ以上の曲げ強度の水熱固化体が得られている。このため、１０質量％以下の消石灰と残部の浄水汚泥焼却灰とが混合された調合物により、実用的な水熱固化体を製造できることがわかる。なお、用途によっては、１０ＭＰａ程度の高い曲げ強度の水熱固化体を得る必要があり、消石灰を３〜８質量％にすることがより好ましい。
【００２７】
また、消石灰の添加量が５質量％の試験体を各水熱処理温度で６時間水熱処理した場合における水熱処理温度（°Ｃ）と曲げ強度（ＭＰａ）との関係を図５に示す。図５より、水熱処理温度が高くなれば、徐々に大きな曲げ強度が得られることがわかる。
【００２８】
消石灰の添加量に伴う構成相の変化をＸＲＤチャートにより図６に示す。また、消石灰の添加量が５質量％の試験体における水熱処理温度（°Ｃ）に伴う構成相の変化をＸＲＤチャートにより図７に示す。また、消石灰の添加量が２０質量％の試験体における水熱処理前後の構成相の変化をＸＲＤチャートにより図８に示す。図６〜８において、Ｑ、Ｍ、Ａ、Ｃｌ及びＫは図２に示した場合と同様であり、Ｐはｐｏｒｔｌａｎｄｉｔｅ（Ｃａ（ＯＨ）_２）、Ｃはｃａｌｃｉｔｅ（ＣａＣＯ_３）、Ｈはｈｙｄｒｏｇａｒｎｅｔ（Ｃａ_３Ａｌ_２（ＳｉＯ_４）（ＯＨ）_８）、Ａｎはａｎｈｄｒｉｔｅ（ＣａＳＯ_４）、●はＣａ_４Ａｌ_２ＣＯ_９・１１Ｈ_２Ｏである（以下、同様。）。図６より、消石灰の添加量が２０質量％の試験体では、ｈｙｄｒｏｇａｒｎｅｔが生成したものの、消石灰の添加量が２０質量％未満の試験体では、ｈｙｄｒｏｇａｒｎｅｔの生成が認められないことがわかる。
【００２９】
消石灰の添加量に伴う水熱処理した各試験体の細孔径分布を図９に示す。また、消石灰の添加量が５質量％で水熱処理温度を変化させた試験体における細孔径分布を図１０に示す。図９及び図１０より、消石灰の添加量が１５質量％以下の試験体で強度発現し、消石灰の添加量が２０質量％の試験体で強度発現しなかった原因は、消石灰の添加量が１５質量％以下の試験体では、１０ｎｍ（０．０１μｍ）を中心とする数〜数十ｎｍサイズの微細な細孔が形成されて強度が発現しているのに対し、消石灰の添加量が２０質量％の試験体では水熱処理の前後で細孔径分布にほとんど変化が認められなかったためであると考えられる。
【００３０】
また、消石灰の添加量が０質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真を図１１に示し、消石灰の添加量が２質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真を図１２に示し、消石灰の添加量が５質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真を図１３に示し、消石灰の添加量が１０質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真を図１４に示し、消石灰の添加量が２０質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真を図１５に示す。
【００３１】
最大の曲げ強度を示した消石灰の添加量が５質量％の試験体は、成形体においてはｈｙｄｒｏｇａｒｎｅｔの生成は認められなかったものの、水熱処理することで約１０ｎｍの細孔が形成されている。図１１〜１５に示すＳＥＭ観察から、消石灰の添加量が１５質量％以下の試験体では、水熱処理により数〜数１０ｎｍサイズの生成物が認められ、強度発現に寄与していると推察される。一方、消石灰の添加量が２０質量％の試験体では、数〜数十ｎｍサイズの微細組織の形成は認められなかった。
【００３２】
また、ＥＤＳ分析から、各試験体の数〜数十ｎｍサイズの微細組織は主にＳｉＯ_２とＡｌ_２Ｏ_３成分から構成され、Ａｌ／Ｓｉ（モル比）＝０．９〜１．５であることが判明した。また、各試験体のＸＲＤ結果より、Ｃａ（ＯＨ）_２の添加量が５質量％の試験体のみ、ｋａｏｌｏｎｉｔｅ（Ａｌ_２Ｓｉ_２Ｏ_５（ＯＨ）_４）と疑われるピークが認められた。以上の結果から、数〜数十ｎｍサイズの生成物はｋａｏｌｏｎｉｔ若しくはその前駆体であると推測している。
【図面の簡単な説明】
【図１】実施形態の製造方法を示す工程図である。
【図２】前処理前の浄水汚泥の構成相を示すＸＲＤチャートである。
【図３】前処理前の浄水汚泥と、６００°Ｃで１０時間加熱処理後の浄水汚泥と、４時間の湿式粉砕及び乾燥後の浄水汚泥との構成相を示すＸＲＤチャートである。
【図４】２２０°Ｃで１０時間水熱処理した場合における消石灰の添加量と曲げ強度との関係を示すグラフである。
【図５】消石灰の添加量が５質量％の試験体を各水熱処理温度で６時間水熱処理した場合における水熱処理温度と曲げ強度との関係を示すグラフである。
【図６】消石灰の添加量に伴う構成相の変化を示すＸＲＤチャートである。
【図７】消石灰の添加量が５質量％の試験体における水熱処理温度に伴う構成相の変化をＸＲＤチャートである。
【図８】消石灰の添加量が２０質量％の試験体における水熱処理前後の構成相の変化を示すＸＲＤチャートである。
【図９】消石灰の添加量に伴う水熱処理した試験体の細孔径分布を示すグラフである。
【図１０】消石灰の添加量が５質量％で水熱処理温度を変化させた試験体における細孔径分布を示すグラフである。
【図１１】消石灰の添加量が０質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真である。
【図１２】消石灰の添加量が２質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真である。
【図１３】消石灰の添加量が５質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真である。
【図１４】消石灰の添加量が１０質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真である。
【図１５】消石灰の添加量が２０質量％の成形体を２２０°Ｃで１０時間水熱処理した試験体のＳＥＭ写真である。
【符号の説明】
Ｓ１０…調合工程
Ｓ２０…成形工程
Ｓ３０…水熱工程[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for producing a hydrothermally solidified body composed of a raw material containing ₃ minutes of Al ₂ O.
[0002]
[Prior art]
BACKGROUND ART Conventionally, a method for producing a hydrothermally solidified body from a raw material containing a CaO component and a SiO _{2 component} is known (for example, see Patent Document 1). In this production method, first, as a preparation step, a preparation is prepared from a raw material containing CaO and SiO ₂ . Then, as a forming step, the preparation is formed into a formed body. Next, in a hydrothermal step, the molded body is subjected to hydrothermal treatment to produce calcium silicate and obtain a solidified hydrothermal solid. The thus obtained hydrothermally solidified body has practical value as building materials such as tiles.
[0003]
[Patent Document 1]
Japanese Patent No. 3196611 [0004]
[Problems to be solved by the invention]
However, if it is possible to produce a hydrothermally solidified by a variety of raw materials, stable supply of raw materials, even though preferred in view of such product costs, in the prior art from the raw material containing Al ₂ O ₃ minutes hydrothermal A solid could not be produced.
[0005]
The present invention has been made in view of the above-mentioned conventional circumstances, and has an object to be solved, characterized in that a hydrothermally solidified body is manufactured from a raw material containing Al ₂ O ₃ .
[0006]
[Means for Solving the Problems]
The inventors studied the recycling of various inorganic wastes by hydrothermal solidification as a trigger of the present invention. That is, among various inorganic wastes, sludge is known as one having a large discharge amount. In the generation process of the sludge, coagulation sedimentation with polyaluminum chloride (PAC) is often used, and the sludge often contains a large amount of aluminum hydroxide (Al (OH) ₃ ) generated in the process of neutralizing the PAC. Although aluminum hydroxide is known to have high hydrothermal reactivity, the effect of aluminum hydroxide in sludge on hydrothermal solidification has not been clarified. Therefore, the inventors studied hydrothermal solidification of purified water sludge, which is sludge generated in a water purification plant, in order to recycle sludge containing a large amount of Al component, and completed the present invention.
[0007]
The method for producing a hydrothermally solidified product of the present invention comprises: a preparing step of preparing a preparation comprising a raw material containing SiO ₂ and Al ₂ O ₃ ; and a forming step of forming the preparation into a molded article. And a hydrothermal step of obtaining a solidified hydrothermally solidified body by hydrothermally treating the molded body.
[0008]
According to the production method of the present invention, a hydrothermally solidified product can be produced from a raw material containing Al ₂ O ₃ . For this reason, a hydrothermally solidified body can be produced from various raw materials more than ever before, which is preferable in terms of stable supply of raw materials, product cost, and the like.
[0009]
Preferably, the formulation is such that some or all of the Al ₂ O ₃ is aluminum hydroxide. This is because aluminum hydroxide has high solubility in water and high reactivity during hydrothermal treatment. This also makes it possible to realize sludge recycling.
[0010]
The SiO ₂ component can be composed of silica sand, glass powder, quartz powder, silica fume, waste foundry sand, rice husk ash, diatomaceous earth, white carbon, concrete debris, shirasu, white clay, and the like. Al ₂ O ₃ minutes are feldspar, clay, giraffe, ceramic waste, coal ash, sewage sludge incineration ash, aluminum hydroxide sludge, red mud, slag, glaze sludge generated in aluminum sash factories, etc., metakaolin, allophane, zeolite, etc. Can be configured. Raw materials containing SiO ₂ and Al ₂ O ₃ include feldspar, clay, glass powder, waste foundry sand, concrete waste, shirasu, white clay, giraffe, ceramic waste, coal ash, sewage sludge incineration ash, and red mud. , Slag, glaze sludge, metakaolin, allophane, zeolite, etc., and sludge treated with PAC can be used. If sludge treated using PAC is employed as the first raw material, recycling can be realized.
[0011]
The formulation may include a CaO component. The CaO component can be composed of slaked lime (Ca (OH) ₂ ) or the like. In the compounding step, the present inventors prepare a mixed material in which a first raw material containing SiO ₂ and Al ₂ O ₃ and a second raw material containing CaO are mixed, and the first raw material is prepared using PAC. The effect of the present invention was confirmed when the sludge was treated and the second raw material was slaked lime.
[0012]
It is preferable that the first raw material is obtained by subjecting sludge treated using PAC to heat treatment. By the heat treatment, organic components unnecessary for hydrothermal solidification can be removed. Further, since the amount of water becomes almost nil by the heat treatment, the amount of water necessary for molding and hydrothermal solidification is easily adjusted, and the hydrothermally solidified product is more easily manufactured. If the sludge after the heat treatment is wet-pulverized, the alumina content in the sludge is rehydrated, and it becomes easier to adjust the water necessary for molding and hydrothermal solidification. In addition, the particle size of the sludge is reduced by the pulverization, and the reactivity is improved.
[0013]
The inventors have confirmed the effects of the present invention when the preparation is a mixture of the second raw material of 10% by mass or less and the remaining first raw material.
[0014]
The forming step is preferably performed by a dry press method. This facilitates the transport and storage of the raw materials. In addition, a molded body in which the water necessary for hydrothermal solidification is adjusted can be molded, and a hydrothermally solidified body can be manufactured without drying the molded body. For these reasons, the manufacturing cost can be reduced. In addition, if formed by dry pressing, the distance between the raw material particles is reduced, and the structure generated by the hydrothermal treatment can be made several to several tens of nanometers in size to efficiently develop strength.
[0015]
The inventors have confirmed that the hydrothermally solidified body has a structure of Al / Si (molar ratio) = 0.9 to 1.5 and is solidified. This structure is a fine structure having a size of several to several tens nm, and may be amorphous. Therefore, it is understood that it is preferable to perform the blending step so that Al / Si (molar ratio) = 0.9 to 1.5.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
In this embodiment, regarding the hydrothermal solidification of purified water sludge, which is sludge generated in a water purification plant, the effect of the preparation and hydrothermal treatment temperature on the strength development of the hydrothermally solidified body is examined.
[0018]
First, as the preparation step S10 shown in FIG. 1, purified water sludge treated using PAC and slaked lime manufactured by Ube Material Co., Ltd. are prepared. The purified water sludge is obtained by dewatering the sludge generated in the water purification plant by a filter press and then drying. Table 1 shows the chemical composition of this purified water sludge. The constituent phases of the purified water sludge are shown in FIG. 2 by an XRD chart. In FIG. 2, Q is quartz (SiO ₂ ), M is muscovite (KAl ₂ (Si ₃ Al) O ₁₀ (OF, F) ₂ ), A is albite (NaAlSi ₃ O ₈ ), and Cl is Is clinochlore ((Mg, Al) ₆ (Si, Al) ₄ O ₁₀ (OH) ₈ ) and K is kaolinite (Al ₂ Si ₂ O ₅ (OH) ₄ ) (the same applies hereinafter). In addition, since the purified water sludge is treated using PAC, it contains aluminum hydroxide generated in the process of neutralizing PAC. However, since aluminum hydroxide is amorphous, it is 15 to 35 ° in the XRD chart. Halo (broad background swell).
[0019]
[Table 1]

[0020]
As a pretreatment for removing organic components from the purified water sludge, the purified water sludge is heated at 600 ° C. for 10 hours. The purified water sludge after the heat treatment is wet-ground with a pot mill for 4 hours and dried. As a result, the alumina content in the purified water sludge is rehydrated, and the adjustment of the water necessary for molding and hydrothermal solidification becomes easy. Further, the particle size of the purified water sludge is reduced by the pulverization, and the reactivity is improved. The XRD chart shows the constituent phases of the purified water sludge before the pretreatment, the purified water sludge after the heat treatment at 600 ° C. for 10 hours, and the purified water sludge after the wet grinding and drying for 4 hours. 2 and 3 that kaolinite was decomposed by the heat treatment at 600 ° C., but other minerals hardly changed.
[0021]
The purified water sludge after the wet pulverization and drying is used as a first raw material, and slaked lime as a second raw material is added to the first raw material so as to be 0 to 20% by mass, and distilled water of 30% by mass is added to the first raw material. Mix. Thus, each composition is obtained.
[0022]
In a molding step S20 shown in FIG. 1, each preparation is uniaxially pressed into a rectangular parallelepiped of 10 mm × 15 mm × 40 mm at a molding pressure of 30 MPa by a dry press method to obtain each molded body. The bending strength of the molded body was 1 MPa, and the bulk density of the molded body was 1.07 (g / cm ³ ).
[0023]
Then, as a hydrothermal step S30, a hydrothermal treatment is performed on each molded body at 160 to 220 ° C for 6 hours or at 220 ° C for 10 hours. Thus, each specimen which is a hydrothermally solidified body is obtained. The bulk density of each test body was 1.08~1.09 (g / cm ^3).
[0024]
Thus, in this production method, a hydrothermally solidified product can be produced from a raw material containing Al ₂ O ₃ . For this reason, the hydrothermally solidified body can be produced from various raw materials more than before, and it is clear that this is preferable in terms of stable supply of raw materials, product cost, and the like.
[0025]
After drying each test piece at 80 ° C. for 2 days, the bending strength (three-point bending test method), generated phase (powder X-ray diffraction) and microstructure (SEM, pore distribution measurement by mercury intrusion method) for each test piece ) Was evaluated.
[0026]
FIG. 4 shows the relationship between the added amount (mass%) of slaked lime and the bending strength (MPa) when the hydrothermal treatment was performed at 220 ° C. for 10 hours. From FIG. 4, it can be seen that the test piece using the composition in which the added amount of slaked lime is 5% by mass exhibits the maximum bending strength of 13.0 MPa. Specimens in which the amount of slaked lime was reduced or increased, had lower flexural strength. If the slaked lime is 10% by mass or less (including 0% by mass and 10% by mass or less), a hydrothermal solid having a bending strength of 5 MPa or more, which is the standard value of the interlocking block, is obtained. Therefore, it can be seen that a practical hydrothermal solidified body can be produced by a mixture of slaked lime of 10% by mass or less and the remaining incinerated ash of purified water sludge. In some applications, it is necessary to obtain a hydrothermally solidified material having a high bending strength of about 10 MPa, and it is more preferable to make slaked lime 3 to 8% by mass.
[0027]
FIG. 5 shows the relationship between the hydrothermal treatment temperature (° C.) and the flexural strength (MPa) in the case where the test specimen containing 5% by mass of slaked lime was hydrothermally treated at each hydrothermal treatment temperature for 6 hours. FIG. 5 shows that the higher the hydrothermal treatment temperature, the more gradually the bending strength can be obtained.
[0028]
FIG. 6 shows an XRD chart of a change in the constituent phases with the addition amount of slaked lime. FIG. 7 shows an XRD chart of a change in the constituent phases of the test specimen in which the added amount of slaked lime was 5% by mass with the hydrothermal treatment temperature (° C.). FIG. 8 shows an XRD chart of changes in the constituent phases before and after the hydrothermal treatment in the test specimen in which the added amount of slaked lime was 20% by mass. 6 to 8, Q, M, A, Cl and K are the same as those shown in FIG. 2, P is portlandite (Ca (OH) ₂ ), C is calcite (CaCO ₃ ), and H is hydrogarnet ( Ca ₃ Al ₂ (SiO ₄ ) (OH) ₈ ), An is anhdrite (CaSO ₄ ), and ● is Ca ₄ Al ₂ CO ₉ .11H ₂ O (the same applies hereinafter). From FIG. 6, it can be seen that hydrogarnet was generated in the test specimen in which the added amount of slaked lime was 20% by mass, but in the test specimen in which the added amount of slaked lime was less than 20% by mass, no hydrogarnet was observed.
[0029]
FIG. 9 shows the pore size distribution of each test piece subjected to hydrothermal treatment with the amount of slaked lime. FIG. 10 shows the pore size distribution of the test specimen in which the amount of slaked lime was 5% by mass and the hydrothermal treatment temperature was changed. 9 and FIG. 10, the strength of the test specimen in which the amount of slaked lime was 15% by mass or less and the strength in the test specimen with the added amount of slaked lime of 20% by mass were the reason why the amount of slaked lime was 15%. In a specimen having a mass of not more than mass%, fine pores having a size of several to several tens of nanometers centering on 10 nm (0.01 μm) are formed to exhibit strength, whereas the amount of slaked lime is 20 mass%. It is considered that this was because almost no change was observed in the pore diameter distribution before and after the hydrothermal treatment in the test specimen of%.
[0030]
In addition, FIG. 11 shows an SEM photograph of a test body obtained by hydrothermally treating a molded body having an added amount of slaked lime of 0% by mass at 220 ° C. for 10 hours. FIG. 12 shows an SEM photograph of a test body subjected to hydrothermal treatment for 10 hours, and FIG. 13 shows an SEM photograph of a test body subjected to hydrothermal treatment at 220 ° C. for 10 hours for a molded body having an added amount of slaked lime of 5 mass%. FIG. 14 shows an SEM photograph of a test body obtained by hydrothermally treating a molded body having an addition amount of 10% by mass at 220 ° C. for 10 hours. FIG. 14 shows a hydrothermal treatment of a molded body having an addition amount of slaked lime at 220 ° C. for 10 hours. FIG. 15 shows an SEM photograph of the test specimen.
[0031]
In the test body having the maximum bending strength and the added amount of slaked lime of 5% by mass, although no formation of hydrogarnet was observed in the molded body, pores of about 10 nm were formed by hydrothermal treatment. From the SEM observations shown in FIGS. 11 to 15, in the test specimens in which the amount of slaked lime was 15% by mass or less, several to several tens of nm-sized products were observed by the hydrothermal treatment, and it is presumed that they contributed to strength development. . On the other hand, in the test specimen in which the added amount of slaked lime was 20% by mass, the formation of a microstructure having a size of several to several tens nm was not recognized.
[0032]
From the EDS analysis, the microstructure of each specimen having a size of several to several tens of nm is mainly composed of SiO ₂ and Al ₂ O ₃ components, and Al / Si (molar ratio) = 0.9 to 1.5. It turned out to be. Further, from the XRD results of the respective specimens, a peak suspected of kaolonate (Al ₂ Si ₂ O ₅ (OH) ₄ ) was observed only in the specimens in which the amount of Ca (OH) ₂ added was 5% by mass. From the above results, it is estimated that the product having a size of several to several tens nm is kaolonit or a precursor thereof.
[Brief description of the drawings]
FIG. 1 is a process chart showing a manufacturing method according to an embodiment.
FIG. 2 is an XRD chart showing constituent phases of purified water sludge before pretreatment.
FIG. 3 is an XRD chart showing constituent phases of purified water sludge before pretreatment, purified water sludge after heat treatment at 600 ° C. for 10 hours, and purified water sludge after wet grinding and drying for 4 hours.
FIG. 4 is a graph showing the relationship between the amount of slaked lime and the bending strength when hydrothermally treated at 220 ° C. for 10 hours.
FIG. 5 is a graph showing the relationship between the hydrothermal treatment temperature and the flexural strength when a test specimen containing 5% by mass of slaked lime was subjected to hydrothermal treatment at each hydrothermal treatment temperature for 6 hours.
FIG. 6 is an XRD chart showing a change in a constituent phase with an addition amount of slaked lime.
FIG. 7 is an XRD chart showing a change in a constituent phase with a hydrothermal treatment temperature in a test specimen in which the amount of slaked lime is 5% by mass.
FIG. 8 is an XRD chart showing changes in constituent phases before and after hydrothermal treatment in a test specimen in which the added amount of slaked lime is 20% by mass.
FIG. 9 is a graph showing the pore size distribution of a test body subjected to hydrothermal treatment with the amount of slaked lime added.
FIG. 10 is a graph showing the pore size distribution of a test specimen in which the amount of slaked lime was 5% by mass and the hydrothermal treatment temperature was changed.
FIG. 11 is an SEM photograph of a test body obtained by subjecting a molded body to which the added amount of slaked lime was 0% by mass to hydrothermal treatment at 220 ° C. for 10 hours.
FIG. 12 is a SEM photograph of a test body which was subjected to a hydrothermal treatment at 220 ° C. for 10 hours on a molded body to which 2% by mass of slaked lime was added.
FIG. 13 is an SEM photograph of a test body obtained by subjecting a formed body to which 5% by mass of slaked lime was subjected to hydrothermal treatment at 220 ° C. for 10 hours.
FIG. 14 is a SEM photograph of a test body which was subjected to a hydrothermal treatment at 220 ° C. for 10 hours for a molded body having an added amount of slaked lime of 10% by mass.
FIG. 15 is an SEM photograph of a test body subjected to a hydrothermal treatment at 220 ° C. for 10 hours on a molded body in which the added amount of slaked lime is 20% by mass.
[Explanation of symbols]
S10: Compounding step S20: Forming step S30: Hydrothermal step

Claims

A preparation step of preparing a preparation comprising a raw material containing a SiO _{2 component} and an Al ₂ O _{3 component} ,
A molding step of molding the composition to form a molded body,
A hydrothermal step of hydrothermally treating the molded body to obtain a solidified hydrothermally solidified body.

The method for producing a hydrothermally solidified product according to claim 1, wherein a part or all of Al ₂ O ₃ is aluminum hydroxide in the preparation.

In the blending step, a blend is prepared by mixing a first raw material containing SiO ₂ and Al ₂ O ₃ and a second raw material containing CaO, and the first raw material is treated using polyaluminum chloride. The method according to claim 1, wherein the sludge is sludge, and the second raw material is slaked lime.

The method according to claim 3, wherein the first raw material has been subjected to a heat treatment to remove organic components.

The method for producing a hydrothermally solidified product according to claim 4, wherein the first raw material is subjected to a heat treatment for removing organic components and then to a wet pulverization.

The hydrothermally solidified product according to any one of claims 3 to 5, wherein the mixture is a mixture of the second raw material of 10 mass% or less and the remaining first raw material. Manufacturing method.

The method for producing a hydrothermally solidified body according to any one of claims 1 to 6, wherein the forming step is performed by a dry press method.

The method for producing a hydrothermally solidified product according to any one of claims 1 to 7, wherein the hydrothermally solidified product has a structure of Al / Si (molar ratio) = 0.9 to 1.5.