JP4162483B2

JP4162483B2 - Concentrated granulation method for inorganic sludge

Info

Publication number: JP4162483B2
Application number: JP2002373328A
Authority: JP
Inventors: 宏之西村; 信雄加藤; 雄一大井; 実鈴木
Original assignee: 株式会社テルナイト
Priority date: 2002-12-25
Filing date: 2002-12-25
Publication date: 2008-10-08
Anticipated expiration: 2022-12-25
Also published as: JP2004202331A

Description

【０００１】
【産業上の利用分野】
本発明は、土木工事やボーリング工事、浚渫工事などから発生する粘土分や粘着物質を含む無機汚泥を処理し、粒状の改良土を得る方法に関する。
【０００２】
【従来の技術】
従来、土木工事やボーリング工事、浚渫工事などから発生する汚泥を処理するにあたっては、これを天日乾燥するか、セメントまたはセメント系固化材で固めるか、古紙やポリマー（有機高分子物質）を用いて流動性を失わせるか、凝集剤を加えて、凝集処理したのち脱水する方法がもっぱら用いられてきた。
天日乾燥は、広い処理ヤードが必要であり、乾燥が完結するまで１年〜数年という長期間を要する。固化材による固化処理は、減量化が望めない上、大量の固化材で処理したものは土としての性質を失うため、再利用の途が限定される。さらに凝集処理してから脱水する脱水処理は、処理コストが高く、処理能力を高めることに困難であるなどの欠点がある。
【０００３】
無機汚泥を有機高分子物質と混合して脱水せずに粒状化改良土を得ることは、特公６−３１５１４において提案されている。しかし、この方法で処理できる汚泥は、含水比が、砂質系で６０％以下、粘土系で１２０％以下のものであり、それ以上の含水比では、粒状改良土を得ることはできない。そこで、汚泥に予め、吸水性の高い回収古紙や木材加工品を加えて見かけ上の含水比を低下させ、それから有機高分子物質と混合して粒状化改良土とする方法が提案されている（特開２０００−２５４６９９）。しかし、この方法によると、水が吸水材に吸収固定されているだけであるから、処理物の密度が小さく、強度も弱く、再利用の途が限定され、処理コストも高い。
【０００４】
また、含水比を低下させる有力な手段として、汚泥に熱を加えて水分を蒸発除去させる方法がある。この方法は簡単であるが産業界で採用されていない。その理由は、無機汚泥が粘土分や粘着物質を含む場合、熱を加えて水分を蒸発させる過程で、急激に内容物が乾燥機の内壁に張り付く現象が生じるためである。
【０００５】
一般に、高含水率のスラリーの水分を加熱により蒸発させ低下させていく場合、とくに、スラリーに含まれる粉末の粒度が微粉末の領域にある場合や、粉末物質が粘着物質を含む場合には、どろどろ（Ｓｌｕｒｒｙ域）、ネバネバ（Ｃａｐｉｌｌａｒｙ域）、パサパサ（Ｆｕｎｉｃｕｌａｒ域又はＰｅｎｄｕｌａｒ域）という過程を経ることが知られている。
建設汚泥やボーリング汚泥は、多くの微粉末を含んでおり、また、ベントナイトや水溶性高分子などの粘着物質を含むことが多いから、乾燥を進めるうち、必ず、このネバネバ（Ｃａｐｉｌｌａｒｙ域）の過程を通過する。このとき、汚泥が濃縮乾燥機の内壁に張り付く現象がおき、乾燥の続行を不可能にする。本発明者らは、この張り付き現象を回避し、効率良く水分を蒸発させる方法について、鋭意、研究を進め、本発明に至ったものである。
【０００６】
本発明は、粘土分や粘着物質を含む無機汚泥に予め無機塩類を加え撹拌したのち、流動性を失わない範囲で出来る限り高濃度まで加熱濃縮して含水比を低下させる前工程と、濃縮物に有機高分子物質を加えて混合し粒状化改良土を得る後工程の２つの工程を組み合わせることからなる。
上記汚泥は、粘土分や粘着物質を含み、かつ比較的水分の多いもので、例えば、含水比５０〜８００％のものである。「粘土分」とは、例えばベントナイトや０．００２ｍｍ以下の土粒子をいう。また「粘着物質」とは、例えばカルボキシメチルセルローズ、グアガム、ポリアクリル酸ナトリウム、ポリアクリルアミドの部分加水分解物などをいう。これら「粘土分」と「粘着物質」が０．１〜２０％含まれている汚泥がおおむね対象となる。
「無機塩類」は、２価または３価の金属塩またはそれを含有する無機物質、例えば硫酸ばん土やポリ塩化アルミニウムであり、「有機高分子物質」は、加熱濃縮物から急速に水分を吸収する性質をもつものであり、例えば、ポリアクリルアミドやポリアクリル酸ナトリウムが好ましい。
「流動性を失わない範囲」とは、汚泥がポンプで輸送できる液体の状態、又は、容器に入れて傾けたとき液面がすみやかに水平となる液体の状態を示す範囲をいう。数値的には、円筒フローコーンによるフロー値が１２〜３０ｃｍの範囲に入る状態を指す。ここで円筒フローコーンによるフロー値とは、モルタルのコンシステンシー測定法として広く知られている値で、径５０ｃｍ程度の水平な鉄板の上に内径８ｃｍ、高さ８ｃｍの円筒を置き、この中に検体を満たした後、円筒を静かに持ち上げ、その時の検体の広がり（直径）を測定し、ｃｍを持って表わす値である。そのときの含水比は、例えば３０〜６０％である。
上記各工程においては、撹拌手段と加熱手段のみを用い、脱水機などは用いない。
【０００７】
本発明の工程を図１から図３に示す。図１が基本工程であり、図２、図３はその応用である。
まず、前工程の加熱濃縮工程について説明する。図１において加熱濃縮工程に先立ち、予め無機塩類を加える。その主な目的は、無機塩類の作用により、汚泥中に含まれる粘土（ベントナイトを含む）等のコロイドがもつ電荷を中和し、凝集状態に置くこと、および、粘着物質を凝集させて粘着性を失わせることにより濃縮工程での装置内部への張り付きを防止することである。
汚泥に凝集作用をもつ無機塩類を添加することは、汚泥を脱水処理する前工程として日常的に行われる。しかし、加熱濃縮時の装置への付着防止を目的にして無機塩類を添加することはこれまで提案されていない。また、脱水を目的にする場合と違って大きなフロックをつくる必要がないから、無機塩類の添加量が少なくて良い。
好ましい無機塩類の添加量は、水を除いた汚泥１００重量部に対して、２〜２０重量部が好ましい。とくに４〜１０重量部が好ましい。
【０００８】
建設汚泥やボーリング汚泥のように粘土分や粘着物質を含む汚泥の場合、上述のように、加熱すると、液状から固体状に移る境界付近で、急激に、内容物が乾燥機の内壁に張り付く現象が観察される。そこで発明者らは、加熱を、流動性が失われない範囲（液状から固体状に移る境界より前の段階）に留めることでこの問題を解決した。すなわち、「乾燥」するまで加熱はせず、「濃縮」と呼ばれる範囲で加熱を打切った。
【０００９】
次に、濃縮液に高分子物質を加え粒状化土を得る後工程について説明する。図１において濃縮物を濃縮工程から混合・粒状化工程に移し、そこで有機高分子を加え撹拌すると、有機高分子は、濃縮物から急速に水分を吸収するから、濃縮物は液状から固体状に姿を変え、撹拌力で造粒されて粒状になる。
好ましい有機高分子物質の添加量は、水を除いた汚泥１００重量部に対して、０．０５〜０．４５重量部が好ましい。とくに０．１５〜０．３重量部が好ましい。
図２は、含水比が高めの汚泥を対象とする場合を示す。この場合、濃縮物に有機高分子を加え撹拌しても、有機高分子の粘着性が残り、団子状の固形物は出来るが粒状化しない。このような場合、助剤として無機塩類を加える。すると、有機高分子の粘着性が失われ、ただちに、見掛け上、川砂に近い形の粒状の改良土が得られる。上記無機塩の添加量は水を除いた汚泥１００重量部に対して１．５〜２０重量部が好ましい。
【００１０】
図３は、粒状改良土に高い強度が要求される場合や、汚泥に有害な物質が含まれ、それを固定化する必要がある場合を示す。この場合、濃縮操作の前または後、あるいは、有機高分子物質を混合する前または後に、セメント、セメント系固化材、生石灰、石灰系固化材、石膏を含む固化材のうちのひとつ以上を加え、１〜７日間程度、養生する。養生は、大気下、自然養生によって行われるのが一般的であるが、水中養生や加熱養生によっても良い。これにより、得られる改良土の性状、とくに強度が著しく向上する。
上記固化材の添加量は、水を除いた汚泥１００重量部に対して２．０〜２０重量部が好ましい。
最終製品の性状を整えるため、得られた粒状改良土をほぐす装置（例えば解砕機）や、粒径を揃える装置（例えば振動篩やトロンメル）を通しても良い。
【００１１】
本発明の対象となる汚泥は、主に、建設基礎工事、たとえば、連続壁や杭、シールド、推進工事から発生する汚泥や、石油、地熱、温泉、用水、調査ボーリングなどに伴って排出される汚泥で、水分が高く、液状を呈しているものである。これらに類似している性状のものであれば、浚渫底泥、沈殿池沈降物などにも適用できる。いずれの場合も、「含水比」が５０〜８００のもので、「粘土分」が０〜２０％、「粘着物質」が０〜５％含まれるものである。
【００１２】
本発明の加熱濃縮工程で用いる濃縮装置は、加熱容器外面にスチームジャケットを有し、内部に汚泥を撹拌できる羽根を有する縦型または横型のものである。その他、同様の装置で羽根の内部にもスチームが通るようにしたもの、内部を加熱された多数のチューブ上に被濃縮液を降らして濃縮するものなど、効率よく加熱濃縮できる装置であれば、機種を問わない。装置内部は、常圧でも負圧（真空を含む）でも良い。市販品のうちの代表的なものとして、(株)オカドラのサイクロンドライヤーや東芝機械(株)のリサイクル乾燥機などがある。
混合・造粒工程で用いる粒状化装置は、濃縮液と高分子物質を良く混合することができ、かつ、処理物に回転運動を与え、粒状化を促す機能を有するものであれば、機種を問わない。市販品のうちの代表的なものとして、太平洋機工（株）のターボミキサー、（株）マツボーのレディゲミキサー、（株）三井三池製作所のヘンシェルミキサーなどがある。
加熱機構を備えた混合、粒状化装置を用いて、前工程と後工程をひとつの装置で行ってもよい。得られた粒状改良土は、造成用土壌、裏込め材などとして活用できる。
【００１３】
【実施例】
本発明の実施例について説明する。
（実施例１）
容量１リットルの金属製容器にリボンヒーターを巻き付け、かつ、縦型撹拌機をセットして、実験用加熱濃縮装置を製作した。この装置に、含水比４１５％の連続壁工事からの廃泥水を６００ｍｌとり、硫酸ばん土液（Ａｌ₂０₃８%水溶液)４ｍｌを加え、加熱濃縮を開始した。１５分経過後、１００℃に達し、５０分経過後、容量が１４５ｍｌになり、液がどろどろになったところで濃縮を停止し、内容物を篠原製作所製ソイルミキサーに移し、ソイルミキサーで、中アニオン性のポリアクリルアミド粉末（分子量１２００万）を０．５ｇを加え、２分間撹拌したところ、きれいな粒状改良土を得ることができた。粒度分布と含水比を表１に示す。
【００１４】
（実施例２）
実施例１と同じ加熱濃縮装置に含水比２００％の石油ボーリング廃泥水を６００ｍｌとり、硫酸ばん土液（Ａ１₂０₃８％水溶液）６ｍｌを加え、濃縮を開始した。１５分経過後、１００℃に達し、４０分経過後、容量が２００ｍｌになり、液がどろどろになったところで濃縮を停止し、内容物をソイルミキサーに移した。ソイルミキサーで、中アニオン性のポリアクリルアミド粉末（分子量１２００万）を０．４ｇ加え、３分間撹拌したところ、液状の内容物は大きな塊状の固体に変った。これに、ポリ塩化アルミニウム溶液（Ａ１₂０₃１０％）２０ｍｌを加え３０秒間撹拌したところ、塊がくずれ、きれいな粒状改良土を得ることができた。粒度分布と含水比を表１に示す。
【００１５】
（実施例３）
実施例１と同じ加熱濃縮装置に含水比２００％の石油ボーリング廃泥水を６００ｍｌとり、硫酸ばん土液（Ａ１₂０₃８％）６ｍｌを加え、濃縮を開始した。１５分経過後、１００℃に達し、４０分経過後、容量が２００ｍｌになり、液がどろどろになったところで濃縮を停止し、内容物をソイルミキサーに移した。ソイルミキサーで、まず、Ｂ種高炉セメント２０グラムを添加、１分間撹拌し、次に中アニオン性のポリアクリルアミド粉末（分子量１２００万）を０．４ｇ加え３分間撹拌したところ、液状の内容物は大きな塊状の固体に変った。これに、ポリ塩化アルミニウム溶液（Ａ１₂０₃１０％）２５ｍｌを加え３０秒間撹拌したところ、塊がくずれ、きれいな粒状改良土を得ることができた。粒度分布と含水比を表１に、大気中、室温の条件下で、７日間養生後の強度を表２に示す。
【００１６】
（実施例４）
実施例１と同じ加熱濃縮装置に含水比２００％の石油ボーリング廃泥水を６００ｍｌとり、始めにポリ塩化アルミニウム液（Ａ１₂０₃１０％）６ｍｌを加え、濃縮を開始した。１５分後、１００℃に達し、４０分経過後、容量が２００ｍｌになり、液がどろどろになったところで濃縮を停止し、内容物をソイルミキサーに移した。ソイルミキサーで、ポリアクリル酸ナトリウム粉末（分子量８００万）を０．６ｇ加え、３分間撹拌したところ、液状の内容物は大きな塊状の固体に変わった。これに、ポリ塩化アルミニウム溶液２０ｍｌ（Ａ１₂０₃１０％）を加え３０秒間撹拌したところ、塊がくずれ、きれいな粒状改良土を得ることができた。粒度分布と含水比を表１に示す。
【００１７】
（実施例５）
（株）オカドラのサイクロンドライヤー（直径５００ｍｍ、高さ５５０ｍｍ）に含水比５００％の石油ボーリング廃泥水を１８リットルとり、始めに硫酸ばん土液（Ａ１₂０₃８％）５０ｍｌを加え、濃縮を開始した。１１分後、１００℃に達し、２６分経過後、容量が２．５リットルになり、液がどろどろになったところで濃縮を停止し、内容物を５リットル容量のソイルミキサーに移した。ソイルミキサーで、中アニオンのポリアクリルアミド粉末（分子量１２００万）を５グラム加え、３分間撹拌したところ、液状の内容物は大きな塊状の固体に変わった。これに、ポリ塩化アルミニウム溶液（Ａ１₂０₃１０％）２５０ｍｌを加え３０秒間撹拌したところ、塊がくずれ、きれいな粒状改良土を得ることができた。粒度分布と含水比を表１に示す。
【００１８】
【表１】

【００１９】
【表２】

【００２０】
【発明の効果】
本発明によれば、汚泥が加熱乾燥機の内壁に張り付く現象を回避し、効率良く水分を蒸発させて、再利用可能な粒状改良土を得ることができる。
【図面の簡単な説明】
【図１】本発明の処理方法を示す工程図である。
【図２】図１に示す方法の変形例を示す工程図である。
【図３】図１に示す方法の、さらに別の変形例を示す工程図である。[0001]
[Industrial application fields]
The present invention relates to a method for obtaining a granular improved soil by treating inorganic sludge containing clay and adhesive substances generated from civil engineering work, boring work, dredging work, and the like.
[0002]
[Prior art]
Conventionally, when treating sludge generated from civil engineering work, boring work, dredging work, etc., this is dried in the sun, solidified with cement or cement-based solidifying material, or used paper or polymer (organic polymer material) Thus, a method of dehydrating after adding a flocculant and adding a flocculant and then dehydrating has been used.
The sun drying requires a wide processing yard, and it takes a long period of one to several years until the drying is completed. The solidification treatment with the solidifying material cannot be reduced in weight, and the material treated with a large amount of the solidified material loses the properties as soil, and therefore, the reuse is limited. Furthermore, the dehydration process of dehydrating after the coagulation process has disadvantages such as high processing costs and difficulty in increasing the processing capacity.
[0003]
In Japanese Patent Publication No. 6-31514, it is proposed to obtain a granulated improved soil by mixing inorganic sludge with an organic polymer substance without dehydration . However, the sludge that can be treated by this method has a water content of 60% or less for sandy type and 120% or less for clay type, and granular improved soil cannot be obtained with a water content higher than that. Therefore, a method has been proposed in which sludge is added to recovered sludge paper or processed wood products with high water absorption in advance to reduce the apparent water content, and then mixed with an organic polymer material to form granulated improved soil ( JP 2000-254699). However, according to this method, since water is only absorbed and fixed to the water-absorbing material, the density of the processed material is small, the strength is weak, the reuse is limited, and the processing cost is high.
[0004]
Further, as an effective means for reducing the water content ratio, there is a method of evaporating and removing moisture by applying heat to sludge. This method is simple but has not been adopted by the industry. The reason for this is that when the inorganic sludge contains clay or an adhesive substance, a phenomenon occurs in which the content abruptly sticks to the inner wall of the dryer in the process of evaporating moisture by applying heat .
[0005]
In general, when the moisture content of the slurry having a high water content is evaporated and reduced by heating , especially when the particle size of the powder contained in the slurry is in the fine powder region, or when the powder substance contains an adhesive substance, It is known to go through a process of mushy (Slurry area), sticky (Capillary area), and papasa (Funular area or Pendular area).
Construction sludge and boring sludge contain many fine powders, and often contain sticky substances such as bentonite and water-soluble polymers. Pass through. At this time, a phenomenon occurs in which sludge sticks to the inner wall of the concentration dryer, making it impossible to continue drying. The inventors of the present invention have earnestly researched a method for efficiently evaporating water while avoiding this sticking phenomenon, and have reached the present invention.
[0006]
The present invention is a pre-process for reducing the water content by heating and concentrating as much as possible within a range not losing fluidity after adding and stirring inorganic salts in advance to inorganic sludge containing clay and adhesive substances, and concentrate. The organic polymer substance is added to and mixed to combine the two subsequent steps to obtain the granulated improved soil.
The sludge contains clay and an adhesive substance, and has a relatively high water content. For example, the sludge has a water content of 50 to 800%. “Clay” refers to, for example, bentonite or soil particles of 0.002 mm or less. The “adhesive substance” refers to, for example, carboxymethyl cellulose, guar gum, sodium polyacrylate, a partial hydrolyzate of polyacrylamide, and the like. The sludge containing 0.1-20% of these “clay” and “adhesive substances” is generally the target.
“Inorganic salts” are divalent or trivalent metal salts or inorganic substances containing them, such as sulfated clay and polyaluminum chloride, and “organic polymer substances” rapidly absorb moisture from the heated concentrate. It is those having a property of, for example, sodium polyacrylamide and polyacrylic acid are preferred.
The “range in which fluidity is not lost” refers to a range in which the sludge can be transported with a pump, or a range in which the liquid level is immediately leveled when tilted in a container. Numerically, it refers to a state where the flow value by the cylindrical flow cone falls within the range of 12 to 30 cm. Here, the flow value by the cylindrical flow cone is a value that is widely known as a mortar consistency measurement method. A cylinder having an inner diameter of 8 cm and a height of 8 cm is placed on a horizontal iron plate having a diameter of about 50 cm. After filling the sample, the cylinder is gently lifted, and the spread (diameter) of the sample at that time is measured, and the value is expressed with cm. The water content ratio at that time is, for example, 30 to 60%.
In each of the above steps, only the stirring means and the heating means are used, and no dehydrator is used.
[0007]
The steps of the present invention are shown in FIGS. FIG. 1 shows the basic process, and FIGS. 2 and 3 show its application.
First, the heating and concentration step in the previous step will be described. In FIG. 1, prior to the heat concentration step, inorganic salts are added in advance. Its main purpose is to neutralize the charge of colloids such as clay (including bentonite) contained in the sludge by the action of inorganic salts, put it in a cohesive state, and cohesive the adhesive substance to make it sticky Is to prevent sticking to the inside of the apparatus in the concentration step.
Adding inorganic salts having an aggregating action to sludge is routinely performed as a pre-process for dewatering sludge. However, it has not been proposed so far to add inorganic salts for the purpose of preventing adhesion to the apparatus during heat concentration. In addition, unlike the case of dehydration, it is not necessary to make a large floc, so the amount of inorganic salt added may be small.
The amount of inorganic salt added is preferably 2 to 20 parts by weight with respect to 100 parts by weight of sludge excluding water. 4 to 10 parts by weight is particularly preferable.
[0008]
In the case of sludge containing clay and sticky substances, such as construction sludge and boring sludge, as described above, the contents suddenly stick to the inner wall of the dryer near the boundary where it changes from liquid to solid when heated. Is observed. Therefore, the inventors solved this problem by restricting the heating to a range in which the fluidity is not lost (the stage before the boundary from the liquid state to the solid state). That is, heating was not performed until “drying”, but heating was stopped within a range called “concentration”.
[0009]
Next, a post-process for obtaining a granulated soil by adding a polymer substance to the concentrate will be described. In FIG. 1, when the concentrate is transferred from the concentration step to the mixing and granulating step, and the organic polymer is added and stirred there , the organic polymer rapidly absorbs moisture from the concentrate, so the concentrate changes from liquid to solid. It changes shape and is granulated by stirring force to become granular.
The amount of the organic polymer substance added is preferably 0.05 to 0.45 parts by weight with respect to 100 parts by weight of sludge excluding water. 0.15-0.3 weight part is especially preferable.
FIG. 2 shows a case where sludge with a high moisture content is targeted. In this case, even if the organic polymer is added to the concentrate and stirred, the organic polymer remains sticky and a dumpling-like solid is formed but not granulated. In such a case, inorganic salts are added as auxiliary agents. Then, the adhesiveness of the organic polymer is lost, and immediately, a granular improved soil that looks like a river sand is obtained. The addition amount of the inorganic salt is preferably 1.5 to 20 parts by weight with respect to 100 parts by weight of sludge excluding water.
[0010]
FIG. 3 shows a case where high strength is required for the granular improved soil, and a case where a harmful substance is contained in sludge and it is necessary to fix it. In this case, before or after the concentration operation, or before or after mixing the organic polymer substance, add one or more of cement, cement-based solidified material, quicklime, lime-based solidified material, and solidified material including gypsum, Curing for about 1-7 days. Curing is generally performed by natural curing in the atmosphere, but may be performed by underwater curing or heat curing. Thereby, the property of the improved soil obtained, especially the strength, is remarkably improved.
The addition amount of the solidifying material is preferably 2.0 to 20 parts by weight with respect to 100 parts by weight of sludge excluding water.
In order to adjust the properties of the final product, it may be passed through a device for loosening the obtained granular improved soil (for example, a crusher) or a device for adjusting the particle size (for example, a vibrating sieve or trommel).
[0011]
The sludge that is the subject of the present invention is mainly discharged with construction foundation work, for example, sludge generated from continuous walls, piles, shields, propulsion work, oil, geothermal heat, hot springs, water, survey boring, etc. It is sludge, has a high water content, and exhibits a liquid state. Anything similar to these can be applied to dredged mud and sedimentation sediment. In any case, the “water content ratio” is 50 to 800, the “clay content” is 0 to 20%, and the “adhesive substance” is 0 to 5%.
[0012]
The concentration apparatus used in the heating and concentration step of the present invention is of a vertical type or a horizontal type having a steam jacket on the outer surface of the heating container and having blades capable of stirring sludge inside. In addition, if it is a device that can efficiently concentrate by heating, such as a device that allows steam to pass inside the blade with the same device, a device that drops the concentrated liquid on many heated tubes, and concentrates it, Regardless of model. The inside of the apparatus may be normal pressure or negative pressure (including vacuum). Typical examples of commercially available products are Okadora's cyclone dryer and Toshiba Machine's recycling dryer.
The granulating device used in the mixing and granulating process can be a model as long as it can mix the concentrated liquid and the polymer substance well and has a function of imparting rotational motion to the processed material and promoting granulation. It doesn't matter. Typical examples of commercially available products include a turbo mixer manufactured by Taiheiyo Kiko Co., Ltd., a ladyge mixer manufactured by Matsubo Co., Ltd., and a Henschel mixer manufactured by Mitsui Miike Manufacturing Co., Ltd.
Using a mixing and granulating apparatus equipped with a heating mechanism, the pre-process and post-process may be performed with a single apparatus. The obtained granular improved soil can be used as soil for creation, backfilling material, and the like.
[0013]
【Example】
Examples of the present invention will be described.
(Example 1)
A ribbon heater was wound around a metal container with a capacity of 1 liter, and a vertical stirrer was set to produce an experimental heating concentration apparatus. To this apparatus, 600 ml of waste mud from a continuous wall construction with a water content ratio of 415% was taken, 4 ml of sulfuric acid earth solution (Al ₂ 0 ₃ 8% aqueous solution) was added, and heating and concentration were started. After 15 minutes, the temperature reached 100 ° C., and after 50 minutes, the volume became 145 ml, and when the liquid became muddy, the concentration was stopped, and the contents were transferred to a Shinohara Soil Mixer. After adding 0.5 g of a functional polyacrylamide powder (molecular weight of 12 million) and stirring for 2 minutes, a clean granular improved soil could be obtained. Table 1 shows the particle size distribution and the water content ratio.
[0014]
(Example 2)
In the same heating and concentrating apparatus as in Example 1, 600 ml of oil boring waste mud having a water content of 200% was taken, 6 ml of sulfuric acid earth solution (A1 ₂₀ ₃ 8% aqueous solution) was added, and concentration was started. After 15 minutes, the temperature reached 100 ° C., and after 40 minutes, the volume became 200 ml. When the liquid became muddy, concentration was stopped and the contents were transferred to a soil mixer. When 0.4 g of medium anionic polyacrylamide powder (molecular weight: 12 million) was added and stirred for 3 minutes with a soil mixer, the liquid content turned into a large lump solid. When 20 ml of polyaluminum chloride solution (A1 ₂ 0 ₃ 10%) was added to this and stirred for 30 seconds, the lump was broken and a clean granular improved soil could be obtained. Table 1 shows the particle size distribution and the water content ratio.
[0015]
(Example 3)
The water content of 200% petroleum boring waste mud to the same heating and concentrating apparatus as in Example 1 taking 600 ml, aluminum sulfate solution _{_{(A1 2 0 3 8%)}} 6ml was added to initiate concentrated. After 15 minutes, the temperature reached 100 ° C., and after 40 minutes, the volume became 200 ml. When the liquid became muddy, concentration was stopped and the contents were transferred to a soil mixer. First, 20 grams of Class B blast furnace cement was added and stirred for 1 minute with a soil mixer, then 0.4 g of medium anionic polyacrylamide powder (molecular weight 12 million) was added and stirred for 3 minutes. It turned into a large blocky solid. When 25 ml of polyaluminum chloride solution (A1 ₂ 0 ₃ 10%) was added to this and stirred for 30 seconds, the lump was broken and a clean granular improved soil could be obtained. Table 1 shows the particle size distribution and water content, and Table 2 shows the strength after curing for 7 days in the atmosphere at room temperature.
[0016]
Example 4
In the same heating and concentrating apparatus as in Example 1, 600 ml of petroleum boring waste mud having a water content of 200% was taken, and 6 ml of polyaluminum chloride solution (A1 ₂ 0 ₃ 10%) was first added to start concentration. After 15 minutes, the temperature reached 100 ° C., and after 40 minutes, the volume became 200 ml. When the liquid became muddy, the concentration was stopped and the contents were transferred to a soil mixer. When 0.6 g of sodium polyacrylate powder (molecular weight: 8 million) was added and stirred for 3 minutes with a soil mixer, the liquid content turned into a large blocky solid. To this, 20 ml of polyaluminum chloride solution (A1 ₂ 0 ₃ 10%) was added and stirred for 30 seconds. As a result, the lump was broken and a clean granular improved soil could be obtained. Table 1 shows the particle size distribution and the water content ratio.
[0017]
(Example 5)
Ltd. Okadora cyclone dryer (diameter 500 mm, height 550 mm) of the hydrous ratio 500% petroleum boring waste mud take 18 l, aluminum sulfate solution _{_{(A1 2 0 3 8%)}} 50ml was added to the first, concentrated Started. After 11 minutes, the temperature reached 100 ° C., and after 26 minutes, the volume became 2.5 liters. When the liquid became muddy, the concentration was stopped, and the contents were transferred to a 5 liter soil mixer. Using a soil mixer, 5 grams of polyacrylamide powder (molecular weight: 12 million) of medium anion was added and stirred for 3 minutes, and the liquid content turned into a large solid mass. When 250 ml of a polyaluminum chloride solution (A1 ₂ 0 ₃ 10%) was added to this and stirred for 30 seconds, the lump was broken and a clean granular improved soil could be obtained. Table 1 shows the particle size distribution and the water content ratio.
[0018]
[Table 1]

[0019]
[Table 2]

[0020]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the phenomenon in which sludge sticks to the inner wall of a heat dryer can be avoided, a water | moisture content can be efficiently evaporated, and the reusable granular improvement soil can be obtained.
[Brief description of the drawings]
FIG. 1 is a process diagram showing a processing method of the present invention.
FIG. 2 is a process diagram showing a modification of the method shown in FIG.
FIG. 3 is a process diagram showing still another modification of the method shown in FIG. 1;

Claims

After adding inorganic salts to the inorganic sludge containing clay and sticking substances in advance and stirring, heat concentration to the highest possible concentration within the range that does not lose fluidity, and reduce the water content ratio. A method for concentrating and granulating sludge, comprising a step of adding and mixing a polymer substance to obtain a granulated improved soil.

2. The inorganic sludge according to claim 1, wherein an organic polymer substance is added to the concentrate and mixed to obtain a granulated improved soil, and an inorganic salt is used in combination to obtain a granulated treated soil having a shape close to river sand. Concentrated granulation processing method.

At least one of solidifying materials including cement, cement-based solidified material, quicklime, lime-based solidified material, and gypsum before or after heating concentration or before or after adding organic polymer substance to the concentrate and mixing. 3. A method for concentrating and granulating inorganic sludge according to claim 1 or 2, characterized in that the soil is cured by adding a high-strength granulated soil.

The method for concentrating and granulating inorganic sludge according to claim 1 or 2, wherein the inorganic salt is a divalent or trivalent metal salt or an inorganic substance containing the same.