JP2016022444A - Method for immobilizing boron in coagulated-sedimented sludge - Google Patents
Method for immobilizing boron in coagulated-sedimented sludge Download PDFInfo
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- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 title claims abstract description 221
- 229910052796 boron Inorganic materials 0.000 title claims abstract description 221
- 239000010802 sludge Substances 0.000 title claims abstract description 155
- 238000000034 method Methods 0.000 title claims abstract description 45
- 230000003100 immobilizing effect Effects 0.000 title claims abstract description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 79
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 79
- 239000004571 lime Substances 0.000 claims abstract description 79
- 239000002699 waste material Substances 0.000 claims abstract description 35
- 239000007788 liquid Substances 0.000 claims abstract description 27
- 238000004062 sedimentation Methods 0.000 claims abstract description 27
- 239000011575 calcium Substances 0.000 claims abstract description 21
- QAOWNCQODCNURD-UHFFFAOYSA-L sulfate group Chemical group S(=O)(=O)([O-])[O-] QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 20
- 239000000701 coagulant Substances 0.000 claims abstract description 12
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 11
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 62
- 238000005345 coagulation Methods 0.000 claims description 27
- 230000015271 coagulation Effects 0.000 claims description 27
- 239000013049 sediment Substances 0.000 claims description 16
- 230000001112 coagulating effect Effects 0.000 claims description 6
- 230000001376 precipitating effect Effects 0.000 claims description 5
- 239000002244 precipitate Substances 0.000 claims 1
- 238000010828 elution Methods 0.000 abstract description 9
- 101100399296 Mus musculus Lime1 gene Proteins 0.000 description 74
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 64
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 51
- 239000008267 milk Substances 0.000 description 30
- 210000004080 milk Anatomy 0.000 description 30
- 235000013336 milk Nutrition 0.000 description 30
- 238000010586 diagram Methods 0.000 description 23
- 238000010304 firing Methods 0.000 description 20
- 239000000243 solution Substances 0.000 description 20
- 238000006243 chemical reaction Methods 0.000 description 19
- 238000003756 stirring Methods 0.000 description 18
- 230000007704 transition Effects 0.000 description 18
- 235000011121 sodium hydroxide Nutrition 0.000 description 17
- 238000001556 precipitation Methods 0.000 description 15
- 150000001875 compounds Chemical class 0.000 description 11
- 230000008569 process Effects 0.000 description 9
- 230000003247 decreasing effect Effects 0.000 description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 6
- 230000002776 aggregation Effects 0.000 description 6
- 238000001354 calcination Methods 0.000 description 6
- 238000004220 aggregation Methods 0.000 description 5
- 230000005484 gravity Effects 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000003139 buffering effect Effects 0.000 description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000000875 corresponding effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 230000004931 aggregating effect Effects 0.000 description 2
- 239000004327 boric acid Substances 0.000 description 2
- 125000005619 boric acid group Chemical group 0.000 description 2
- 229910052810 boron oxide Inorganic materials 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 235000011116 calcium hydroxide Nutrition 0.000 description 2
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 229910001653 ettringite Inorganic materials 0.000 description 2
- 238000005189 flocculation Methods 0.000 description 2
- 230000016615 flocculation Effects 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 238000010335 hydrothermal treatment Methods 0.000 description 2
- 238000010979 pH adjustment Methods 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical group [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 229910052925 anhydrite Inorganic materials 0.000 description 1
- 229940095564 anhydrous calcium sulfate Drugs 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229940063013 borate ion Drugs 0.000 description 1
- 150000001639 boron compounds Chemical class 0.000 description 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004660 morphological change Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000006174 pH buffer Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- VLCLHFYFMCKBRP-UHFFFAOYSA-N tricalcium;diborate Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]B([O-])[O-].[O-]B([O-])[O-] VLCLHFYFMCKBRP-UHFFFAOYSA-N 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
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Abstract
Description
本発明は、例えばホウ素含有廃棄物を凝集沈殿処理により分離凝集されたホウ素含有汚泥中からホウ素が再溶出しないためのホウ素固定化法に関するものである。 The present invention relates to a boron immobilization method for preventing boron from re-eluting from, for example, boron-containing sludge obtained by separating and aggregating boron-containing waste by a coagulation-precipitation treatment.
現在、ホウ素含有廃棄物は、電気メッキ業、ガラス製造業、液晶表示用偏光板製造業等から、１０００mg/L以上の高濃度に濃縮された状態で排出されている。ホウ素及びホウ素化合物については、平成１３年７月に水質汚濁防止法が改正され、ホウ素の排水基準(排水基準１０mg/L)が新たに追加された(海域外：１０mg/L、海域：２３０mg/L)。このホウ素の排水基準が強化されている中、これらホウ素廃棄物は主に希釈により放流されているのが現状であり、希釈に頼らないホウ素処理技術の開発が急務となっている。
Currently, boron-containing waste is discharged in a concentrated state of 1000 mg / L or more from the electroplating industry, the glass manufacturing industry, the liquid crystal display polarizing plate manufacturing industry, and the like. Regarding boron and boron compounds, the Water Pollution Control Law was revised in July 2001, and boron drainage standards (
現在の廃液中のホウ素の処理方法として、(1) 凝集剤と石灰による凝集沈殿処理、(2) イオン交換樹脂等による吸着処理、(3) 溶媒抽出処理等が挙げられる。後者の(2) 及び(3) の処理方法は、ホウ素を精製しリサイクルする手法が主流である。しかし、高濃度の夾雑物を含有する廃棄物を対象とした場合、純度の高いホウ素の回収が難しく、また、リサイクルできない場合はホウ素を含む残渣物に対して処理が必要となるなど、実用化が難しいのが実状である。 Current methods for treating boron in waste liquid include (1) coagulation-precipitation treatment with a flocculant and lime, (2) adsorption treatment with an ion exchange resin, and (3) solvent extraction treatment. The latter treatment methods (2) and (3) mainly involve purifying and recycling boron. However, when waste containing high-concentration impurities is targeted, it is difficult to recover high-purity boron, and if it cannot be recycled, it will be necessary to treat boron-containing residues. The reality is that is difficult.
一方、(1) の方法は、ホウ素廃液に対して凝集剤を添加し、石灰等を用いてｐＨ１０以上に調整する単純なプロセスであることから、操作が簡便であり、種々の工場の化学処理設備においてもＡｌ系凝集剤やＦｅ系凝集剤を用いた凝集沈澱処理が行われている。しかしながら、この場合、発生汚泥からのホウ素易溶出性が問題点として挙げられている。通常、凝集沈澱処理はアルカリ性雰囲気で行われるが、凝集沈澱処理によって形成された汚泥中のホウ素は、アルカリ側から中性側へのｐＨシフトすることにより形態を変化させて、汚泥から容易に溶出する。 On the other hand, since the method (1) is a simple process in which a flocculant is added to the boron waste liquid and the pH is adjusted to 10 or more using lime or the like, the operation is simple and the chemical treatment of various factories. In the equipment, coagulation-precipitation treatment using Al-based coagulant or Fe-based coagulant is performed. However, in this case, easy dissolution of boron from the generated sludge is cited as a problem. Usually, coagulation precipitation is performed in an alkaline atmosphere, but the boron in the sludge formed by coagulation precipitation is easily eluted from the sludge by changing the pH from the alkali side to the neutral side. To do.
つまり、この(1) の方法により、廃液中のホウ素は除去できるが、発生汚泥中のホウ素は、凝集沈殿処理後のアルカリ性雰囲気を保持している間は溶出しないが、最終処分地に埋め立てた際に浸出水と接触してアルカリ性雰囲気を保持できなくなると浸出水中にほぼ全量が溶出されることとなり、ホウ素の排水基準を超える場合には最終処分地において凝集沈殿を行うという悪循環が発生するに至っている。よって、凝集沈殿処理によりホウ素含有廃棄物を完全に処理するためには、発生する汚泥のホウ素不溶化技術(固定化技術)が必要不可欠である。尚、ホウ素の固定化技術としては、アルカリ土類金属(Ｃａ)とリン酸イオンの共存下のもと５０℃以上で凝集沈殿処理を行う“水熱処理”(特許文献１参照)が既に提案されている。 In other words, the boron in the waste liquid can be removed by the method (1), but the boron in the generated sludge does not elute while maintaining the alkaline atmosphere after the coagulation sedimentation treatment, but is buried in the final disposal site. If the alkaline atmosphere cannot be maintained due to contact with the leachate, almost all of the leachate will be eluted. If the drainage standard for boron is exceeded, a vicious cycle of coagulating sedimentation will occur at the final disposal site. Has reached. Therefore, in order to completely treat the boron-containing waste by the coagulation sedimentation treatment, the boron insolubilization technology (immobilization technology) of the generated sludge is indispensable. As a technique for immobilizing boron, “hydrothermal treatment” (see Patent Document 1) in which coagulation precipitation is performed at 50 ° C. or higher in the presence of alkaline earth metal (Ca) and phosphate ions has already been proposed. ing.
しかしながら、水熱処理では、１０００mg/L以上の高濃度ホウ素廃液に対してホウ素の除去性が悪く、また、汚泥からのホウ素溶出を抑制することは困難であった。本発明は、凝集沈殿処理により凝集されたホウ素含有汚泥を最終処分地に埋め立てた状態であっても、浸出水中への再溶出を防止することが可能となるホウ素固定化法を得ることができ、更に、簡便にホウ素を固定化することができるホウ素固定化法を得ることを目的とする。 However, in the hydrothermal treatment, boron removability is poor with respect to a high concentration boron waste liquid of 1000 mg / L or more, and it is difficult to suppress boron elution from sludge. The present invention can provide a boron immobilization method that can prevent re-elution into the leachate even when the boron-containing sludge aggregated by the coagulation sedimentation treatment is buried in the final disposal site. Furthermore, it aims at obtaining the boron fixation method which can fix a boron simply.
請求項１に記載された発明に係る凝集沈殿汚泥中のホウ素固定化法は、ホウ素廃液に対して凝集剤を添加し、石灰(Ｃａ(ＯＨ)２)によってｐＨ１０以上に調整してホウ素を凝集沈殿処理した凝集沈殿汚泥中のホウ素固定化法であって、
前記凝集沈殿汚泥には、石灰由来のカルシウム以外にアルミニウムと硫酸基とを含み、
前記凝集沈殿汚泥を４００℃以上７７０℃未満の条件で加熱することを特徴とするものである。
In the method for fixing boron in the coagulated sediment sludge according to the invention described in claim 1, a coagulant is added to the boron waste liquid, and the pH is adjusted to 10 or more with lime (Ca (OH) 2 ) to coagulate boron. A method for fixing boron in a coagulated sedimentation sludge that has been subjected to precipitation treatment,
In addition to calcium derived from lime, the aggregated sludge contains aluminum and sulfate groups,
The agglomerated sedimentation sludge is heated under conditions of 400 ° C. or higher and lower than 770 ° C.
請求項２に記載された発明に係るホウ素固定化法は、請求項１に記載の凝集沈殿汚泥中のアルミニウムがＡｌ系凝集剤由来であることを特徴とするものである。
The boron immobilization method according to the invention described in
請求項３に記載された発明に係るホウ素固定化法は、請求項１又は２に記載の凝集沈殿汚泥中のアルミニウムが硫酸バンド(Ａｌ２(ＳＯ４)３)由来であることを特徴とするものである。
The boron immobilization method according to the invention described in
請求項４に記載された発明に係るホウ素固定化法は、ホウ素廃液に対して硫酸バンド(Ａｌ２(ＳＯ４)３)を添加し、石灰(Ｃａ(ＯＨ)２)によってｐＨ１１以上に調整してホウ素を凝集沈殿処理した凝集沈殿汚泥中のホウ素固定化法であって、
前記凝集沈殿汚泥を５００〜６００℃の条件で加熱することを特徴とするものである。
In the boron immobilization method according to the invention described in
The agglomerated sedimentation sludge is heated under conditions of 500 to 600 ° C.
本発明は、凝集沈殿処理により凝集されたホウ素含有汚泥がアルカリ性雰囲気を保持できない状態であっても、汚泥から浸出水中への再溶出を防止することができ、更に、簡便にホウ素を固定化することができるという効果がある。 The present invention can prevent re-elution from the sludge into the leachate even when the boron-containing sludge aggregated by the coagulation sedimentation treatment cannot maintain an alkaline atmosphere, and further, boron is simply immobilized. There is an effect that can be.
本発明においては、ホウ素廃液に対して凝集剤を添加し、石灰(Ｃａ(ＯＨ)２)によってｐＨ１０以上に調整してホウ素を凝集沈殿処理した凝集沈殿汚泥を４００℃以上７７０℃未満の条件で加熱するものであるため、凝集沈殿処理により凝集されたホウ素含有汚泥を最終処分地に埋め立てた状態であっても、汚泥から浸出水中への再溶出を防止することができ、更に、簡便にホウ素を固定化することができる。 In the present invention, a coagulant is added to the boron waste liquid, and the coagulated sediment sludge obtained by adjusting the pH to 10 or more with lime (Ca (OH) 2 ) and coagulating and precipitating boron under conditions of 400 ° C. or higher and lower than 770 ° C. Because it is heated, even if the boron-containing sludge aggregated by the coagulation sedimentation treatment is buried in the final disposal site, it can prevent re-elution from the sludge into the leachate, and more simply boron Can be immobilized.
即ち、本発明では、凝集沈殿処理により発生した汚泥を高温で燃焼させる“凝集・焼成処理”に着目した。種々の検討の結果、アルミニウムを含む凝集剤を用いた凝集沈殿処理において、石灰を添加し、かつ、発生した汚泥を焼成することにより、ホウ素を凝集汚泥焼成物中に固定化できることが見出され、本発明に至った。 That is, in the present invention, attention is paid to “aggregation / firing process” in which sludge generated by the coagulation sedimentation process is burned at a high temperature. As a result of various studies, it has been found that boron can be fixed in the baked coagulated sludge by adding lime and calcining the generated sludge in the coagulation sedimentation treatment using the coagulant containing aluminum. The present invention has been reached.
図１はホウ素固定化メカニズムを示す説明図である。図に示す通り、凝集沈殿処理により、硫酸バンド(Ａｌ２(ＳＯ４)３)と石灰(Ｃａ(ＯＨ)２)とが反応して、二水石膏(ＣａＳＯ４・２Ｈ２Ｏ)とアルミン酸カルシウム(ＣａＯ・Ａｌ２Ｏ３)とを形成する。これらの化合物から、ホウ素吸着汚泥であるエトリンガイト様化合物(３ＣａＯ・Ａｌ２Ｏ３・３ＣａＳＯ４・６Ｈ２Ｏ)が形成される。このエトリンガイト中のＳＯ４ ２−はホウ酸イオン(Ｂ(ＯＨ)４ −)と容易に置換し、ホウ酸置換型エトリンガイト様化合物(３ＣａＯ・Ａｌ２Ｏ３・ＣａＳＯ４・Ｃａ[Ｂ(ＯＨ)４]２・６Ｈ２Ｏ)を形成することにより、溶液中のホウ素を効率的に除去されると考えられた。 FIG. 1 is an explanatory view showing a boron immobilization mechanism. As shown in the figure, the sulfate band (Al 2 (SO 4 ) 3 ) and lime (Ca (OH) 2 ) react with each other by agglomeration and precipitation treatment, and dihydrate gypsum (CaSO 4 .2H 2 O) and aluminate. Calcium (CaO.Al 2 O 3 ) is formed. From these compounds, an ettringite-like compound (3CaO.Al 2 O 3 .3CaSO 4 .6H 2 O) which is a boron adsorption sludge is formed. SO 4 2− in this ettringite is easily substituted with borate ion (B (OH) 4 − ), and boric acid substituted ettringite-like compound (3CaO.Al 2 O 3 .CaSO 4 .Ca [B (OH)) 4 ] 2 · 6H 2 O) was thought to efficiently remove boron in the solution.
このホウ酸置換型エトリンガイト様化合物は、加熱することにより、脱水する。４００℃より低い加熱の場合には、結晶中の水分子が残った状態となる。尚、７７０℃以上の加熱の場合には、エトリンガイト中のＣａＳＯ４成分が分解し始める温度であり、ガス化(硫酸・亜硫酸ガス)する場合と、ＣａＳＯ４の結合が弱くなる場合により、硫酸イオンが消失する。さて、４００℃以上７７０℃未満の条件で加熱する場合には、完全に脱水して無水ホウ酸置換型エトリンガイト様化合物が形成すると考えられた。この無水型は、硬石膏(無水硫酸カルシウム)の場合と同様に、水分を加えても水和物化することなく、難溶性を維持していると予想された。 This boric acid substituted ettringite-like compound is dehydrated by heating. In the case of heating lower than 400 ° C., water molecules in the crystal remain. In the case of heating at 770 ° C. or higher, it is the temperature at which the CaSO 4 component in ettringite begins to decompose, and depending on the case of gasification (sulfuric acid / sulfurous acid gas) and the weak binding of CaSO 4 , sulfate ions Disappears. Now, when heated under conditions of 400 ° C. or higher and lower than 770 ° C., it was considered that the boric anhydride-substituted ettringite-like compound was completely dehydrated. As in the case of anhydrite (anhydrous calcium sulfate), this anhydrous form was expected to maintain poor solubility without being hydrated even when water was added.
特に、５００℃以上６００℃以下の場合には、無水ホウ酸置換型エトリンガイト様化合物の組成中に含まれるＣａＯ・Ｂ２Ｏ３(ホウ酸カルシウム)・Ａｌ２Ｏ３(アルミナ)、ＣａＳＯ４(石膏)は、それぞれ非常に難溶性であることからも、５００〜６００℃で焼成して無水化物に変換させることにより、ホウ素の再溶出を大きく抑制していると考えられた。 In particular, in the case of 500 ° C. or more and 600 ° C. or less, CaO · B 2 O 3 (calcium borate) · Al 2 O 3 (alumina), CaSO 4 ( Since gypsum) is very poorly soluble, it was considered that re-elution of boron was greatly suppressed by baking at 500 to 600 ° C. to convert it to an anhydride.
本発明による凝集沈殿汚泥中には、エトリンガイト様化合物が形成されて、ホウ素をその中に取り込んだ状態となればよいため、その凝集沈殿汚泥はアルミニウムとカルシウムと硫酸基とを備えるものであればよい。凝集沈殿の際に石灰によってｐＨを調整するため、ホウ素廃液に添加使用する凝集剤としてＡｌ系凝集剤を用いれば、アルミニウムを追加する必要がなくなる。更に、凝集剤として硫酸バンドを用いれば、アルミニウムと硫酸基とを追加する必要がなくなる。 In the coagulated sediment sludge according to the present invention, an ettringite-like compound is formed, and it is sufficient that boron is taken into the coagulated sediment sludge. Good. Since the pH is adjusted with lime during the coagulation and precipitation, if an Al-based coagulant is used as the coagulant added to the boron waste liquid, it is not necessary to add aluminum. Furthermore, if a sulfate band is used as the flocculant, it is not necessary to add aluminum and sulfate groups.
１．Ａｌ系凝集剤の選定
ホウ素の凝集沈殿処理において使用されるＡｌ系凝集剤として、硫酸バンドとＰＡＣ(ポリ塩化アルミニウム)が頻用されている。そこで、硫酸バンドまたはＰＡＣ(ポリ塩化アルミニウム)を用いて凝集・焼成処理を行い、両Ａｌ系凝集剤を用いた場合の焼成汚泥(以下、硫酸バンド汚泥、ＰＡＣ汚泥)のホウ素固定力を比較した。凝集剤添加量は、２００mg/Lのホウ素廃液に対して、ＰＡＣはAl/B＝８、硫酸バンドはAl/B＝４の比率とした。
1. Selection of Al-based flocculant A sulfate band and PAC (polyaluminum chloride) are frequently used as the Al-based flocculant used in the coagulation-precipitation treatment of boron. Therefore, coagulation / firing treatment was performed using sulfuric acid band or PAC (polyaluminum chloride), and the boron fixing power of calcined sludge (hereinafter referred to as sulfuric acid band sludge, PAC sludge) was compared when both Al-based coagulants were used. . The amount of the flocculant added was a ratio of Al / B = 8 for PAC and Al / B = 4 for sulfuric acid band with respect to 200 mg / L boron waste liquid.
また、凝集沈殿処理の条件は、ｐＨ調整時の石灰乳添加速度は１．０mL/(min・L)とし、ｐＨ１２．０にまで調整後、固液分離して脱水汚泥を得た。この脱水汚泥を所定量るつぼに入れ、電気炉により、５００℃、２ｈの条件で焼成させた。焼成汚泥のホウ素固定率は、実験水による通水試験により求めた。通水条件は、各焼成汚泥をＬ／Ｓ＝２０として実験水中に添加し、２００ｒｐｍ、６ｈの条件で振盪した。その後、３０００ｒｐｍ、１５分の条件で遠心分離し、デカンテーションして、再度上記の条件で実験水を添加した後に振盪させた。 The coagulation sedimentation conditions were such that the lime milk addition rate during pH adjustment was 1.0 mL / (min · L), adjusted to pH 12.0, and then solid-liquid separated to obtain dehydrated sludge. A predetermined amount of this dewatered sludge was placed in a crucible and fired in an electric furnace at 500 ° C. for 2 hours. The boron fixation rate of the calcined sludge was determined by a water flow test using experimental water. The water flow conditions were as follows: each calcined sludge was added to the experimental water with L / S = 20 and shaken at 200 rpm for 6 hours. Thereafter, the mixture was centrifuged at 3000 rpm for 15 minutes, decanted, and again added with experimental water under the above conditions, followed by shaking.
通水試験は、この操作を繰り返して実施した。また、通水試験時における焼成汚泥のホウ素固定化率は、次式により算出した。
［ホウ素固定率(％)］＝ホウ素固定量／初期汚泥ホウ素含有量×１００
［ホウ素固定量］＝初期汚泥ホウ素含有量−{(通水中の実験水ホウ素濃度−元来の実験水ホウ素濃度)}×実験水量
This operation was repeated for the water flow test. Moreover, the boron fixed rate of the baked sludge at the time of a water flow test was computed by following Formula.
[Boron fixation rate (%)] = Boron fixation amount / Initial sludge boron content × 100
[Boron fixation amount] = Initial sludge boron content − {(Experimental water boron concentration in running water−Original experimental water boron concentration)} × Experimental water amount
図２は焼成汚泥と脱水汚泥との通水試験結果を示す線図であり、ａ図は硫酸バンド汚泥とＰＡＣ汚泥とのｐＨ値の推移、ｂ図は硫酸バンド汚泥とＰＡＣ汚泥とのホウ素溶出濃度の推移、ｃ図は硫酸バンド汚泥とＰＡＣ汚泥とのホウ素固定率の推移を示している。ａ図に示す通り、ｐＨ推移に関して、硫酸バンド焼成汚泥は、通水初期においてｐＨ１０程度を示したが、２０mL/g-sludgeの通水以降は実験水ｐＨに収束した。一方、ＰＡＣ焼成汚泥は通水２０mL/g-sludgeまでｐＨ１０．８の高い領域でｐＨ緩衝性を示し、硫酸バンド焼成汚泥より遅れて４０mL/g-sludgeに実験水ｐＨに収束した。 Fig. 2 is a diagram showing the water flow test results of calcined sludge and dewatered sludge. Fig. A shows the transition of pH value between sulfuric acid band sludge and PAC sludge. Fig. B shows boron elution of sulfuric acid band sludge and PAC sludge. Concentration transition, FIG. C, shows transition of boron fixation rate of sulfuric acid band sludge and PAC sludge. As shown in FIG. a, regarding the pH transition, the sulfuric acid band calcined sludge showed a pH of about 10 at the beginning of water flow, but converged to the experimental water pH after water flow of 20 mL / g-sludge. On the other hand, the PAC calcined sludge showed pH buffering properties in a high pH 10.8 region up to a water flow of 20 mL / g-sludge and converged to the experimental water pH at 40 mL / g-sludge later than the sulfuric acid band calcined sludge.
ｂ図に示す通り、実験水中のホウ素濃度推移に関して、硫酸バンド焼成汚泥は、通水２０mL/g-sludgeに最大８０mg/Lを示したが、それ以降は減少して４０mL/g-sludgeの通水で実験水ホウ素濃度に収束した。ＰＡＣ焼成汚泥は、通水量初期のｐＨ緩衝領域において実験水中ホウ素を新規に吸着することにより、そのホウ素濃度は１０mg/L以下にまで減少した。その後、ｐＨの低下に伴ってホウ素濃度は上昇し、８０mL/g-sludge目で最大１３３mg/Lを示した。それ以降は減少したが、２００mL/g-sludgeの通水まで僅かではあるがホウ素の溶出が継続した。 As shown in Fig. b, regarding the transition of boron concentration in the experimental water, the sulfuric acid band calcined sludge showed a maximum of 80 mg / L for 20 mL / g-sludge, but after that it decreased to 40 mL / g-sludge. The water converged to the experimental water boron concentration. In the PAC calcined sludge, the boron concentration was reduced to 10 mg / L or less by newly adsorbing boron in experimental water in the pH buffer region in the initial stage of water flow. Thereafter, the boron concentration increased with a decrease in pH, showing a maximum of 133 mg / L at the 80 mL / g-sludge order. After that, although it decreased, the elution of boron continued to a little until the water flow of 200 mL / g-sludge.
ｃ図に示す通り、汚泥のホウ素固定率は、２００mL/g-sludgeの通水において、硫酸バンド焼成汚泥は８２％を示したのに対して、ＰＡＣ焼成汚泥は２７％にまで低下した。因みに、未焼成汚泥である脱水汚泥は、硫酸バンドの場合は９０mL/ g-sludge目で、ＰＡＣの場合は５０mL/ g-sludge目においてホウ素固定率が０％となり、汚泥内のホウ素の全量を溶出した。以上より、凝集・焼成処理において使用するＡｌ系凝集剤は硫酸バンドを使用することにより、汚泥内の８０％以上のホウ素を固定化できることが確認された。 As shown in Fig. c, the boron fixation rate of the sludge showed 82% for the sulfuric acid band calcined sludge at a water flow rate of 200 mL / g-sludge, whereas the PAC calcined sludge decreased to 27%. Incidentally, dehydrated sludge, which is unfired sludge, has a boron fixation rate of 0% at 90 mL / g-sludge in the case of sulfuric acid band and 50 mL / g-sludge in the case of PAC, and the total amount of boron in the sludge. Eluted. From the above, it was confirmed that the Al-based flocculant used in the flocculation / firing treatment can fix 80% or more of boron in the sludge by using a sulfuric acid band.
２．石灰量
凝集・焼成処理において、ホウ素固定率の高い焼成汚泥を作成するためには、凝集沈殿処理に必要な石灰量を適確に添加する必要がある。その必要な石灰量を添加する方法として、添加速度を低速にする方法が挙げられる。表１は１０００mg/Lのホウ素廃液１Ｌに対して硫酸バンドをＡｌ／Ｂ＝２．５の比率で添加し、種々の石灰乳添加速度(１．０、２．５、５mL/(min・L))で凝集沈殿処理を行った結果であり、図３は石灰添加速度により調製した汚泥焼成物(５００℃)の通水試験結果を示す線図であり、ａ図はｐＨ推移、ｂ図はホウ素濃度推移、ｃ図はホウ素固定率推移である。
2. In the lime content coagulation / firing process, in order to create a calcined sludge having a high boron fixation rate, it is necessary to add an appropriate amount of lime necessary for the coagulation sedimentation process. As a method of adding the necessary amount of lime, a method of lowering the addition rate can be mentioned. Table 1 shows that a sulfuric acid band was added at a ratio of Al / B = 2.5 to 1 L of 1000 mg / L boron waste liquid, and various lime milk addition rates (1.0, 2.5, 5 mL / (min · L )) Is the result of the coagulation sedimentation treatment, FIG. 3 is a diagram showing the water flow test results of the sludge calcined product (500 ° C.) prepared at the lime addition rate, a diagram is pH transition, b diagram is Boron concentration transition, c figure is boron fixation rate transition.
これらの結果より、石灰乳添加速度が２．５、５mL/(min・L)以上の場合、凝集沈殿処理のホウ素除去効率はそれぞれ９７．９％、９６．４％、焼成汚泥のホウ素固定率は４５％、２５％を示したのに対して、１．０mL/(min・L)の場合は、ホウ素除去効率が９９．４％、ホウ素固定率も８５％を示した。 From these results, when the lime milk addition rate is 2.5 or 5 mL / (min · L) or more, the boron removal efficiency of the coagulation sedimentation treatment is 97.9% and 96.4%, respectively, and the boron fixation rate of the calcined sludge 45% and 25%, while 1.0 mL / (min · L) showed a boron removal efficiency of 99.4% and a boron fixation rate of 85%.
よって、石灰乳添加速度を１．０mL/(min・L)に設定することにより反応に必要なＣａが無駄なく供給されてホウ素除去効率、ホウ素固定率ともに向上し、また、石灰乳使用量と汚泥発生量も減量することが確認された。しかし、石灰の低速添加の問題点としてｐＨ調整の長時間化が挙げられる。そこで、この問題点の打開策として必要量分の石灰を一括で添加する方法(以下、一括添加法)を考慮した。以下に、その一括添加法における必要な石灰乳量の算出方法について記す。 Therefore, by setting the lime milk addition rate to 1.0 mL / (min · L), Ca necessary for the reaction is supplied without waste, and both the boron removal efficiency and the boron fixation rate are improved. It was confirmed that sludge generation was reduced. However, the problem of slow addition of lime is that the pH adjustment takes a long time. Therefore, as a measure for overcoming this problem, a method of collectively adding a necessary amount of lime (hereinafter referred to as a batch addition method) was considered. Below, the calculation method of the amount of lime milk required in the lump addition method is described.
３．一括添加法
図４はホウ素廃液(1000ｍｇ-B/L)のｐＨシフト図であり、ａ図は１Ｎ苛性ソーダ、ｂ図は石灰乳(34.3wt%)を用いた場合を示す。ａ図に示す通り、１Ｎ苛性ソーダでｐＨシフトさせた場合は、第１停滞区間(ｐＨ３〜4.5)は存在するが、第２停滞区間(ｐＨ10.5〜11.0)が短くなる。一方、石灰乳でｐＨ調整した場合、第２停滞区間が長くなる。これは、苛性ソーダで調整した場合は、Ａｌ(ＯＨ)３→Ａｌ(ＯＨ)４ −の形態変化しか進行していないが、石灰乳の場合はＣａ２＋とＡｌ(ＯＨ)３、ＳＯ４ ２−によるエトリンガイト様化合物(ホウ素吸着汚泥)の生成反応がこの第２停滞区間で進行していることを示している。
3. Batch Addition Method FIG. 4 is a pH shift diagram of boron waste liquid (1000 mg-B / L). FIG. 4a shows the case using 1N caustic soda, and FIG. B shows the case using lime milk (34.3 wt%). As shown in FIG. a, when the pH is shifted with 1N caustic soda, the first stagnation section (
そこで、高いホウ素固定力を示す汚泥を形成するために必要な石灰乳添加量のポイントを見極めるために、図４のｂ図に示す４ポイント((a) ｐＨ１０、(b) ｐＨ１１(第２停滞区問始点、ｐＨ１１ａ)、(c) 第２停滞区間中点（ｐＨ１１ｂ）、(d) ｐＨ１１．２(第２停滞区間終点、ｐＨ１１ｃ)について、そのホウ素処理性及びホウ素固定率を調査した。凝集沈殿処理の条件は、ｂ図上の各ポイントに相当する石灰添加量を一括で添加し、その後１５０分間撹拌した。その結果、石灰乳の添加量に従い反応液粘度が上がり、その粘度に従ってホウ素除去効率が向上した。特に、ポイント(d) ｐＨ１１ｃにおいては、99.0％を示した。 Therefore, in order to ascertain the point of the lime milk addition amount necessary for forming sludge showing a high boron fixing force, 4 points ((a) pH10, (b) pH11 (second stagnation) shown in FIG. The ward inquiry point, pH 11a), (c) the second stagnation section midpoint (pH 11b), and (d) pH 11.2 (second stagnation section end point, pH 11c) were examined for boron treatability and boron fixation. Precipitation treatment conditions were as follows: lime addition amount corresponding to each point on Fig. B was added all at once, and then stirred for 150 minutes, and as a result, the reaction solution viscosity increased according to the lime milk addition amount, and boron was removed according to the viscosity. In particular, the point (d) was 99.0% at pH 11c.
次に各発生汚泥に対して焼成処理(電気炉、５００℃、２ｈｒ)を施し、前述の通り、通水試験に供して、ホウ素固定力を調査した。図５は各ポイントの焼成汚泥の通水試験結果を示す線図であり、ａ図はｐＨ、ｂ図はホウ素濃度、ｃ図はホウ素固定率の各推移を示している。凝集沈殿処理時の反応液粘度が７６mPa・sであった(a) ｐＨ１０及び３０mPa・sであった(b) ｐＨ１１ａはホウ素の放出が顕著であり、ホウ素固定率も１５％にまで低下した。また、粘度１５７mPa・sを示した(c) ｐＨ１１ｂに関してもホウ素固定率が２０％にまで低下した。一方、５２６．４mPa・sを示した(d) ｐＨ１１ｃに関しては、ホウ素放出も抑制され、ホウ素固定率も８５％を維持した。この結果から、ホウ素除去率、ホウ素固定率ともに高い値を示すポイントとしては、(d) ｐＨ１１ｃであった。 Next, each generated sludge was subjected to a firing treatment (electric furnace, 500 ° C., 2 hours), and subjected to a water flow test as described above to examine the boron fixing force. FIG. 5 is a diagram showing the water flow test results of the calcined sludge at each point. FIG. 5 shows the transition of pH, b shows the boron concentration, and c shows the boron fixation rate. The viscosity of the reaction solution during the coagulation treatment was 76 mPa · s. (A) The pH was 10 and 30 mPa · s. (B) At pH 11a, boron was significantly released, and the boron fixation rate was reduced to 15%. In addition, (c) pH 11b, which showed a viscosity of 157 mPa · s, also decreased the boron fixation rate to 20%. On the other hand, for (d) pH 11c, which showed 526.4 mPa · s, boron release was also suppressed and the boron fixation rate was maintained at 85%. From this result, it was (d) pH11c as a point which shows a high value in both a boron removal rate and a boron fixed rate.
４．苛性ソーダ量からの石灰必要量の算出
前述の通り、高いホウ素除去率、固定率を示すためには、第２ｐＨ停滞区間の終点まで到達するのに必要な石灰乳を添加する必要があることが確認された。しかし、石灰は溶解度が低く反応性も悪いため、ビーカーテストにおいて石灰乳によりその最適量を検索するには、1ｈｒ程度緩速添加して求めなければならない。また、急速添加を行うと過剰添加などにより誤差を拡大させるため、石灰乳を用いたビーカーテストの実現は難しいと考える。そこで、第２ｐＨ停滞区間終点に到達するまでに必要な石灰乳量を苛性ソーダから求めた。
4). Calculation of required amount of lime from caustic soda amount As described above, in order to show a high boron removal rate and fixation rate, it is confirmed that it is necessary to add lime milk necessary to reach the end point of the second pH stagnation section It was done. However, since lime has low solubility and poor reactivity, in order to search for the optimum amount with lime milk in the beaker test, it must be obtained by slowly adding about 1 hr. In addition, since the error is enlarged due to excessive addition when rapid addition is performed, it is difficult to realize a beaker test using lime milk. Therefore, the amount of lime milk necessary to reach the end point of the second pH stagnation section was determined from caustic soda.
図６は図４のｐＨシフト図との関係を示す説明図であり、ａ図は石灰量と１Ｎ苛性ソーダ量との関係、ｂ図はＡｌの形態との関係を示す。前述の(d) ｐＨ１１ｃポイントは苛性ソーダ量が１６０mLに対して石灰量が２５mLである。硫酸バンド由来のＡｌは両性金属でありｐＨに応じて、ｂ図に示す通り、(1) ｐＨ＜３：Ａｌ３＋、(2) ｐＨ４.５〜７：Ａｌ(ＯＨ)３、(3) ｐＨ＞１２；Ａｌ(ＯＨ)４ −に形態が変化する。Ａｌ溶液のｐＨシフトにおける第１停滞区間はＡｌ３＋→Ａｌ(ＯＨ)３、第２停滞区間はＡｌ(ＯＨ)３→Ａｌ(ＯＨ)４ −の形態変化に起因している。その変化に応じて、反応液の色は、(1) Ａｌ３＋：透明、(2) Ａｌ(ＯＨ)３：白色、(3) Ａｌ(ＯＨ)４ −：透明を呈する。(d) ｐＨ１１ｃポイントに相当する１６０mLの苛性ソーダ量を添加すると、反応液は半透明となる。 FIG. 6 is an explanatory diagram showing the relationship with the pH shift diagram of FIG. 4, where FIG. 6a shows the relationship between the amount of lime and 1N caustic soda, and FIG. 6b shows the relationship with the form of Al. The above-mentioned (d) pH 11c point is a caustic soda amount of 160 mL and a lime amount of 25 mL. Al derived from a sulfate band is an amphoteric metal, and depending on pH, as shown in FIG. B, (1) pH <3: Al 3+ , (2) pH 4.5-7: Al (OH) 3 , (3) pH >12; the form changes to Al (OH) 4 − . The first stagnation section in the pH shift of the Al solution is caused by a change in the form of Al 3+ → Al (OH) 3 , and the second stagnation section is caused by a change in the form Al (OH) 3 → Al (OH) 4 − . According to the change, the color of the reaction solution exhibits (1) Al 3+ : transparent, (2) Al (OH) 3 : white, and (3) Al (OH) 4 − : transparent. (d) When 160 mL of caustic soda corresponding to pH 11c point is added, the reaction solution becomes translucent.
そこで、この半透明度を判定するため、ビーカーの一側壁から対向する他側壁に亘って側方からの距離を相違させた少なくとも２つの目印を配置し、白濁した状態から徐々に半濁の状態によって、手前の目印と奥の２つめの目印で２つの目印が側壁から確認できる指標を配して、必要石灰乳量を求めるビーカーテストを行った。以下に、そのテスト手順を示す。
(1) 所定量(１００mL)のホウ素廃液(硫酸バンド添加済み)に２つの目印を浸し、苛性ソーダを用いてｐＨを上げる。
(2) ｐＨ４より反応液が白濁し、２つの目印が目視できなくなる。
(3) ｐＨ１１より反応液が序々に半透明となり、手前の１つ目の目印が目視される。
(4) 奥の２つ目の目印が確認された時点で苛性ソーダを停止し、この終点を苛性ソーダ添加量とした。
Therefore, in order to determine the semi-transparency, at least two marks having different distances from the side are arranged from one side wall of the beaker to the other side wall facing each other, and gradually from the cloudy state to the semi-turbid state. The beaker test was conducted to determine the required amount of lime milk by placing an index that allows the two marks to be confirmed from the side wall with the mark in front and the second mark in the back. The test procedure is shown below.
(1) Immerse the two marks in a predetermined amount (100 mL) of boron waste liquid (added with sulfuric acid band) and raise the pH with caustic soda.
(2) The reaction solution becomes cloudy from
(3) The reaction solution gradually becomes translucent from
(4) Caustic soda was stopped when the second mark in the back was confirmed, and this end point was taken as the amount of caustic soda added.
この苛性ソーダ添加量から図６のａ図に示す石灰と苛性ソーダの関係式を用いて、石灰必要量を求める、但し、実際の石灰必要量は、処理対象液容量と使用する石灰乳の濃度を考慮に入れる必要があるため、次式により、求めることとした。
石灰乳添加量＝(１Ｎ苛性ソーダ量と石灰乳添加量の関係式)×
(反応液容量Ｌ)／(ビーカーテス卜容量０．１Ｌ)×
(苛性ソーダと石灰の関係図の作成に使用した石灰乳濃度wt%)／(処理に使用する石灰乳濃度wt%)
The required amount of lime is determined from the amount of caustic soda added using the relational expression of lime and caustic soda shown in FIG. 6a. However, the actual required amount of lime takes into account the volume of liquid to be treated and the concentration of lime milk to be used. Since it is necessary to put in, it decided to obtain | require by the following formula.
Lime milk addition amount = (Relationship between 1N caustic soda amount and lime milk addition amount) ×
(Reaction solution volume L) / (Beakates volume 0.1 L) ×
(Concentration of lime milk used to create the relationship between caustic soda and lime wt%) / (Concentration of lime milk used for processing wt%)
ここで、石灰乳の濃度は、粘度及び比重の値に高い相関があり、次式により石灰乳濃度を求めることができる。２号石灰を使用した場合、濃度は粘度、比重ともに相関性が高く、両値から石灰濃度を求めることができた。特号石灰の場合、調製した石灰乳の粘度が非常に低いため、濃度と粘度の関係式を得ることができない。そこで、次式の通り、比重を用いて濃度を求めた。以上より、廃液毎に石灰と苛性ソーダとの関係図を作成し、石灰と苛性ソーダの関係式を導き出して必要な石灰量を求めることができることが確認された。 Here, the density | concentration of lime milk has a high correlation with the value of a viscosity and specific gravity, and can calculate | require lime milk density | concentration by following Formula. When No. 2 lime was used, the concentration was highly correlated with both viscosity and specific gravity, and the lime concentration could be determined from both values. In the case of special lime, since the viscosity of the prepared lime milk is very low, the relational expression of a density | concentration and a viscosity cannot be obtained. Therefore, the concentration was determined using the specific gravity as follows. From the above, it was confirmed that a relationship diagram between lime and caustic soda was prepared for each waste liquid, and a relational expression between lime and caustic soda was derived to obtain a necessary amount of lime.
(２号石灰の場合)
石灰乳濃度＝９８．２×(石灰比重)−８５．４
＝８．１×ｌｎ(石灰粘度)−９．４ (≦４００mPa・s)
＝５．６×ｌｎ(石灰粘度)＋４．５ (＞４００mPa・s)
(特号石灰の場合)
石灰乳濃度＝１４０×(比重)−１３７
(In the case of No. 2 lime)
Lime milk concentration = 98.2 × (lime specific gravity) −85.4
= 8.1 × ln (lime viscosity) −9.4 (≦ 400 mPa · s)
= 5.6 × ln (lime viscosity) +4.5 (> 400 mPa · s)
(For special lime)
Lime milk concentration = 140 × (specific gravity) −137
５．硫酸バンド必要量
硫酸バンドの必要量を求めるために、ホウ素濃度１０００mg/Lのホウ素廃液に対して、硫酸バンドを種々のＡｌ／Ｂ比で添加し、前述の石灰一括添加法で凝集沈殿処理を行った後、発生汚泥を焼成処理(電気炉、５００℃、２ｈｒ)した。
5. Required amount of sulfuric acid band To obtain the required amount of sulfuric acid band, a sulfuric acid band is added at various Al / B ratios to a boron waste solution having a boron concentration of 1000 mg / L, and the aggregation precipitation process is performed by the lime batch addition method described above. After that, the generated sludge was fired (electric furnace, 500 ° C., 2 hours).
図７は１０００mg/Lのホウ素廃液における硫酸バンド添加量に対するホウ素除去効率、ホウ素固定率、粘度、処理後ホウ素濃度の関係を示す線図である。これらの結果より、どの濃度の硫酸バンド添加量においても、ホウ素除去効率９０％以上、ホウ素固定率８０％以上を示した。これより、硫酸バンドの添加量は、処理施設の能力(運用基準、粘度許容値など)に準じて決定すれば良いことが判った。但し、各廃液の種類や濃度によって硫酸バンドの必要量は異なる。よって廃液毎に、種々の硫酸バンド添加量を検討し、目標とする処理後ホウ素濃度、ホウ素固定率及び粘度を満たす最適な量を見極める必要がある。 FIG. 7 is a diagram showing the relationship between boron removal efficiency, boron fixation rate, viscosity, and post-treatment boron concentration with respect to the amount of sulfuric acid band added in a 1000 mg / L boron waste solution. From these results, the boron removal efficiency was 90% or more and the boron fixation rate was 80% or more at any concentration of sulfuric acid band addition. From this, it was found that the addition amount of the sulfuric acid band may be determined in accordance with the capacity of the treatment facility (operation standard, allowable viscosity value, etc.). However, the required amount of sulfuric acid band varies depending on the type and concentration of each waste liquid. Therefore, it is necessary to examine the amount of various sulfuric acid bands added for each waste liquid and determine the optimum amount that satisfies the target post-treatment boron concentration, boron fixation rate, and viscosity.
６．撹拌時間
次に、凝集沈殿処理の石灰乳一括添加法における撹拌時間の最適値を検索した。処理条件は、対象液を１０００mg/Lのホウ素廃液とし、前項の石灰乳計算方法に従って求めた石灰乳量を一括で添加し、種々の時間撹拌した後、発生汚泥を焼成処理(電気炉、５００℃、２ｈｒ〉した。図８は石灰を一括添加した後の撹拌時間に対するｐＨ、粘度及びホウ素濃度の推移である。
6). Stirring time Next, the optimum value of the stirring time in the batch addition method of lime milk in the coagulation sedimentation process was searched. The treatment condition is that the target liquid is 1000 mg / L boron waste liquid, the amount of lime milk obtained according to the lime milk calculation method in the previous section is added in a lump and stirred for various times, and then the generated sludge is baked (electric furnace, 500 Fig. 8 shows changes in pH, viscosity, and boron concentration with respect to the stirring time after lime was added all at once.
図に示す通り、時間経過とともに、ｐＨは上昇し、３０分後にはｐＨ１０以上を示した。よって、一括添加法におけるｐＨの予定の到達点(ｐＨ１０〜１１)には３０分以上の撹拌が必要である。ホウ素の処理効率に関しては、３０分経過において除去効率が９８％以上を示した。さらに、粘度の上昇とともにホウ素除去効率が向上し、９０分経過において９９％に達した。しかし、さらに撹拌を継続すると、粘度の低下に伴って除去効率は若干低下し、一晩撹拌後には、ホウ素除去効率は、９７．５％となった。
As shown in the figure, the pH increased with time, and after 30 minutes, the pH was 10 or more. Therefore, stirring for 30 minutes or more is required for the planned arrival point (
次いで、各撹拌時間に対する焼成汚泥のホウ素固定率について、最も高い処理効率を示した撹拌時間９０分の汚泥と、１５０分、１１１０分の汚泥を焼成し、通水試験に供した。図示はしないが、何れの焼成汚泥についても、通水時のｐＨ推移に関しては、どの撹拌時間においても、通水４０mL/ｇ目において実験水ｐＨに収束し、またホウ素濃度に関しても、通水初期において若干のホウ素放出が見られたが、通水４０mL/ｇで実験水ホウ素濃度に収束した。ホウ素固定率も全ての撹拌時間で９０％以上を示し、撹拌時間が長いほど高いホウ素固定率を示す傾向となった。 Next, regarding the boron fixation rate of the calcined sludge with respect to each stirring time, the sludge with the stirring time of 90 minutes and the sludge with 150 minutes and 1110 minutes, which showed the highest treatment efficiency, were fired and subjected to a water flow test. Although not shown, for any calcined sludge, with regard to the pH transition during water flow, at any stirring time, the water converges to the experimental water pH at the 40 mL / g water flow, and the boron concentration also relates to the initial water flow. Although some boron release was observed in the sample, it converged to the experimental water boron concentration at a water flow rate of 40 mL / g. The boron fixation rate also showed 90% or more in all stirring times, and the longer the stirring time, the higher the boron fixation rate tended to be.
以上より、凝集沈澱処理のホウ素除去性に関しては、撹拌時間９０分目で最大除去効率を示し、焼成汚泥のホウ素固定率は撹拌時間が長いほど向上する傾向が得られたことから、撹拌時間は、９０分以上とする。但し、撹拌時間が長くなるとホウ素除去性が悪くなり、一晩撹拌後の処理後濃度は、最大除去効率を示す濃度の約２倍となる。そのため、撹拌時間９０分以降は、早い段階で反応を終了させるべきであることが判った。 From the above, regarding the boron removability of the coagulation precipitation treatment, the maximum removal efficiency was exhibited at the stirring time of 90 minutes, and the boron fixation rate of the baked sludge was tended to improve as the stirring time was longer. , 90 minutes or more. However, if the stirring time becomes longer, the boron removability deteriorates, and the post-treatment concentration after overnight stirring is about twice the concentration showing the maximum removal efficiency. Therefore, it was found that the reaction should be terminated at an early stage after 90 minutes of stirring time.
７．凝集沈殿処理時の反応液粘度
凝集沈殿処理において、反応液粘度がホウ素除去効率、ホウ素固定率に与える影響は大きい。図９のａ図は反応液粘度に対するホウ素除去効率、ｂ図はホウ素固定率を示している。図に示す通り、反応液粘度の上昇に伴い、ホウ素除去効率及びホウ素固定率が高くなることが示された。また、両図より、ホウ素の除去効率及び固定率の高い凝集汚泥を示す目安として、反応液粘度が１００mPa・s以上であることを確認することが望ましいことが示された。
7). Reaction solution viscosity during coagulation sedimentation treatment In the coagulation sedimentation treatment, the reaction solution viscosity has a great influence on the boron removal efficiency and the boron fixation rate. 9 shows the boron removal efficiency with respect to the reaction solution viscosity, and b shows the boron fixation rate. As shown in the figure, it was shown that the boron removal efficiency and the boron fixation rate increase as the reaction solution viscosity increases. In addition, both figures indicate that it is desirable to confirm that the viscosity of the reaction solution is 100 mPa · s or more as a guideline indicating agglomerated sludge having a high boron removal efficiency and a high fixation rate.
８．焼成温度
焼成処理において、最もホウ素固定能力の高い焼成汚泥を形成する温度を検索した。実験条件は、対象液を２００ｍｇ−Ｂ／Ｌのホウ素廃液とし、硫酸バンド添加量をＡｌ／Ｂ＝４の比率で添加して凝集沈澱処理を行った。また、焼成処理は、脱水汚泥の含水によるバラツキを無くすため、１１０℃で乾燥させた汚泥(以下、乾燥汚泥〉に対して行った。条件は、電気炉により時間を２ｈｒとし、温度は４００、５００、６００、８００、１０００℃とした。焼成温度の増加に伴って容積の減量が見られ、乾燥汚泥と比較すると約４０〜７０％の減量を示した。また、質量は、５００℃以上で焼成することで乾燥汚泥と比較して約１８〜２７％の減量となった。形状は、全体的に細やか粒状となった。硬度は、乾燥汚泥の場合は脆いが、焼成汚泥は焼結して硬度が高くなっていた。特に、５００、６００℃における焼成汚泥は硬度が高いことが確認された。
8). Calcination temperature The temperature at which calcination sludge having the highest boron fixing ability was formed was searched. The experimental conditions were that the target solution was a 200 mg-B / L boron waste solution, and the amount of sulfuric acid band added was added at a ratio of Al / B = 4 to perform the aggregation precipitation treatment. The firing treatment was performed on sludge dried at 110 ° C. (hereinafter referred to as dry sludge) in order to eliminate variation due to water content of the dehydrated sludge. The conditions were that the time was 2 hours with an electric furnace, the temperature was 400, 500, 600, 800, 1000 ° C. A decrease in volume was observed with an increase in calcination temperature, indicating a weight loss of about 40 to 70% compared to dry sludge. The calcining resulted in a reduction of about 18-27% compared to the dry sludge, and the overall shape was fine and granular.The hardness was brittle in the case of dry sludge, but the calcined sludge was sintered. In particular, it was confirmed that the calcined sludge at 500 and 600 ° C. had a high hardness.
ホウ素含有量に関しては、焼成温度が高くなるに従い、ホウ素含有量が高くなる傾向を示した。これは、温度が高くなるに従って、汚泥が減量して濃縮されたことに起因する。しかし、焼成温度１０００℃においては若干低い値を示した。ホウ素は、高温で焼成させることにより脱水して酸化ホウ素の形態で焼成汚泥内に存在していると考えられた。酸化ホウ素の沸点は約１６８０℃であり、１０００℃で焼成させた場合、ホウ素が若干揮発する結果となった。 Regarding the boron content, the boron content tended to increase as the firing temperature increased. This is because sludge was reduced and concentrated as the temperature increased. However, it showed a slightly lower value at a firing temperature of 1000 ° C. Boron was dehydrated by firing at a high temperature and was considered to be present in the calcined sludge in the form of boron oxide. Boron oxide had a boiling point of about 1680 ° C., and when baked at 1000 ° C., boron was slightly volatilized.
図１０は各温度の焼成汚泥の通水試験結果を示す線図であり、ａ図はｐＨ、ｂ図はホウ素濃度、ｃ図はホウ素固定率の推移である。ａ図に示す通り、ｐＨ推移に関して、含水汚泥、乾燥汚泥に関しては、３０mL/g-sludgeまでｐＨ緩衝性を示したが、その後低下し、４０mL/g-sludge以降は実験水ｐＨに収束した。他の温度の焼成汚泥はｐＨ緩衝性がなく、特に、５００℃、６００℃の焼成汚泥はｐＨ低下が早く、２０mL/g-sludgeで実験水ｐＨに収束した。 FIG. 10 is a diagram showing the water flow test results of the baked sludge at each temperature, where a is the pH, b is the boron concentration, and c is the transition of the boron fixation rate. As shown in Fig. a, regarding pH transition, water-containing sludge and dry sludge showed pH buffering properties up to 30 mL / g-sludge, but then decreased, and after 40 mL / g-sludge, converged to experimental water pH. The calcined sludge at other temperatures has no pH buffering property. In particular, the calcined sludge at 500 ° C. and 600 ° C. has a fast pH drop and converged to the experimental water pH at 20 mL / g-sludge.
実験水中のホウ素濃度推移に関して、乾燥汚泥、８００℃、１０００℃での焼成汚泥に関しては、実験水中ホウ素の新規吸着が見られた。１０mL/g-sludge以降は、全ての汚泥において汚泥からのホウ素の放出が見られたが、１１０mL/g-sludge以降は実験水のホウ素濃度に収束した。特に、５００℃、６００℃での焼成汚泥は、ホウ素の再溶出が少なく、実験水ホウ素濃度も５００℃では３０mL/g-sludge、６００℃では６０mL/g-sludgeの通水で収束値を示した。 Regarding the boron concentration transition in the experimental water, new adsorption of boron in the experimental water was observed for the dried sludge and the calcined sludge at 800 ° C and 1000 ° C. After 10 mL / g-sludge, boron was released from the sludge in all sludges, but after 110 mL / g-sludge, the concentration of boron in the experimental water converged. In particular, calcined sludge at 500 ° C and 600 ° C has little re-elution of boron, and the experimental water boron concentration shows a convergence value with water flow of 30 mL / g-sludge at 500 ° C and 60 mL / g-sludge at 600 ° C. It was.
これに伴い、２００mL/g-sludgeの通水におけるホウ素固定率は、５００℃では８２％、６００℃では７２％と非常に高いホウ素固定能力を示した。他の温度におけるホウ素固定率は脱水汚泥：０％、１１０℃：３１％、８００℃：５１％、１０００℃：４１％という結果を示した。以上より、ホウ素固定率の高い焼成汚泥を作成することができる温度領域は、５００〜６００℃であることが確認された。 Along with this, the boron fixation rate in passing water of 200 mL / g-sludge showed a very high boron fixation capacity of 82% at 500 ° C. and 72% at 600 ° C. The boron fixation rates at other temperatures were as follows: dehydrated sludge: 0%, 110 ° C .: 31%, 800 ° C .: 51%, 1000 ° C .: 41%. From the above, it was confirmed that the temperature range in which baked sludge having a high boron fixation rate can be created is 500 to 600 ° C.
９．焼成時間
最適な焼成時間を検索した。実験条件は、１０００mg/Lのホウ素廃液に硫酸バンドをＡｌ／Ｂ＝３．５の割合で添加して凝集沈殿した。焼成条件は、電気炉により温度を５００℃とし、また、焼成時間は、１５、３０、６０、１２０、１８０分とした。図１１は各焼成時間における通水試験結果を示す線図であり、ａ図はｐＨ、ｂ図はホウ素濃度、ｃ図はホウ素固定率の推移である。ｐＨ推移に関しては、焼成汚泥はどの時間においても６０mL/g-sludgeの通水で実験水ｐＨに収束し、大きな差は見られなかった。
9. The optimum firing time was searched. The experimental condition was that a sulfuric acid band was added to a 1000 mg / L boron waste liquid at a ratio of Al / B = 3.5 to cause aggregation precipitation. The firing conditions were an electric furnace at a temperature of 500 ° C., and the firing time was 15, 30, 60, 120, and 180 minutes. FIG. 11 is a diagram showing the results of the water flow test at each firing time. FIG. 11 shows the transition of pH, FIG. B shows the boron concentration, and FIG. Regarding the pH transition, the calcined sludge converged to the experimental water pH by passing water at 60 mL / g-sludge at any time, and no significant difference was observed.
実験水中のホウ素濃度に関しては、脱水汚泥、乾燥汚泥の場合、６０mL/g-sludgeまでホウ素の放出が顕著に見られたのに対して、焼成汚泥は通水初期においてホウ素の放出が見られたが、通水６０mL/ｇ以降はホウ素の放出は抑えられ、実験水ホウ素濃度に収束した。これに付随して、ホウ素固定率に関しても、脱水汚泥は全量のホウ素が放出し、乾燥汚泥は３０％にまで低下したのに対して、どの時間の焼成汚泥も８０％以上のホウ素固定率を示した。 Regarding the boron concentration in the experimental water, in the case of dehydrated sludge and dried sludge, boron was significantly released up to 60 mL / g-sludge, whereas the calcined sludge showed boron released in the early stage of water flow. However, the release of boron was suppressed after water flow of 60 mL / g and converged to the experimental water boron concentration. Concomitantly, with regard to the boron fixation rate, dehydrated sludge released all the amount of boron and dry sludge was reduced to 30%, while calcined sludge at any time had a boron fixation rate of 80% or more. Indicated.
次に、図１２は焼成時間に対するホウ素固定率をプロットした線図である。図に示す通り、焼成時間が１５分の場合は８８％、３０分の場合は９１．７％という高いホウ素固定率を示した。６０分以上では１５〜３０分と比較するとホウ素固定力は若干低下するが、８３％以上のホウ素固定率を維持する結果となった。以上より、焼成時間は３０分に設定することで最大のホウ素固定率を示すが、１５分以上の焼成を行うことで、８０％以上のホウ素固定力を示すことが確認された。 Next, FIG. 12 is a diagram plotting the boron fixation rate against the firing time. As shown in the figure, the boron fixation rate was as high as 88% when the firing time was 15 minutes and 91.7% when the firing time was 30 minutes. When it was 60 minutes or more, the boron fixing force slightly decreased as compared with 15 to 30 minutes, but the boron fixing rate of 83% or more was maintained. From the above, it was confirmed that the maximum boron fixation rate is exhibited by setting the firing time to 30 minutes, but that 80% or more of boron fixation force is exhibited by firing for 15 minutes or more.
１０．ホウ素固定化メカニズム
図１に示す通り、ホウ酸置換型エトリンガイト様化合物(３ＣａＯ・Ａｌ２Ｏ３・ＣａＳＯ４・Ｃａ[Ｂ(ＯＨ)４]２・６Ｈ２Ｏ)を４００℃以上７７０℃未満の条件、より好ましくは５００℃以上６００℃以下の条件で加熱することにより、完全に脱水して無水ホウ酸置換型エトリンガイト様化合物(ＣａＯ・Ａｌ２Ｏ３・ＣａＳＯ４・Ｂ２Ｏ３)となることにより、水分を加えても水和物化することなく、難溶性を維持していると予想される。
10. Boron immobilization mechanism As shown in FIG. 1, a boric acid-substituted ettringite-like compound (3CaO.Al 2 O 3 .CaSO 4 .Ca [B (OH) 4 ] 2 .6H 2 O) is 400 ° C. or higher and lower than 770 ° C. By heating under conditions, more preferably 500 ° C. or more and 600 ° C. or less, it is completely dehydrated to form a boric anhydride-substituted ettringite-like compound (CaO.Al 2 O 3 .CaSO 4 .B 2 O 3 ). Therefore, even if water is added, it is expected that it remains insoluble without being hydrated.
図１３は各温度の硫酸バンド焼成汚泥の通水試験における実験水中の硫酸イオン濃度の推移図である。図に示す通り、焼成温度が高いほど、ホウ素脱着区間における実験水中の硫酸イオン濃度が高くなることから、硫酸イオンが汚泥から容易に脱離しているものと考えられる。特に、１０００℃と５００℃における硫酸イオン濃度を比較すると、約２．８倍もの差が見られた。これより、硫酸イオンが、ホウ素処理および固定化に重要な役割を果していることが確認された。 FIG. 13 is a transition diagram of sulfate ion concentration in experimental water in a water flow test of sulfuric acid band calcined sludge at various temperatures. As shown in the figure, the higher the calcination temperature, the higher the sulfate ion concentration in the experimental water in the boron desorption section. Therefore, it is considered that sulfate ions are easily desorbed from the sludge. In particular, when the sulfate ion concentrations at 1000 ° C. and 500 ° C. were compared, a difference of about 2.8 times was observed. From this, it was confirmed that sulfate ion plays an important role in boron treatment and immobilization.
１１．ホウ素固定化処理操作
図１４はホウ素固定化処理操作のフロー図である。図に示す通り、ホウ素固定化技術の効率化を目的に、凝集・焼成処理の最適化を行うことができ、簡便にホウ素を固定化することができる。特に、次の条件を備えるとより良好にホウ素を固定化することが可能となる。
11. Boron Immobilization Processing Operation FIG. 14 is a flow chart of boron immobilization processing operation. As shown in the figure, for the purpose of improving the efficiency of the boron immobilization technique, the aggregation / firing treatment can be optimized, and boron can be immobilized easily. In particular, when the following conditions are provided, it becomes possible to better fix boron.
(1) ホウ素廃液を凝集沈殿する際の凝集剤は、Ａｌ系凝集剤を使用することができるが、特に硫酸バンドを使用することにより、硫酸イオンがホウ素処理および固定化に重要な役割を果しているため、ホウ素の固定化が飛躍的に高まる。
(2) 石灰必要量は、一括添加法のプロセスに従って求めればよく、硫酸バンドの必要量は、処理後濃度及び反応液の粘度の設定値により決定すればよい。
(3) 凝集沈殿処理の撹拌時間は９０分以上とする。但し、９０分以降はホウ素除去率が低下するため、なるべく早く反応を終了する。
(4) 凝集沈殿処理時の液粘度は１００mPa・s以上であることを確認する。但し、硫酸バンドの添加量が少ない場合、１００ｍPa・s未満となることもあるため、廃液毎に粘度とホウ素固定率の関係を確認しておく。
(5) 焼成条件は、温度５００〜６００℃、時間１５分以上とする。
(1) Al-based flocculants can be used as the flocculant for coagulating and precipitating boron waste liquid, but sulfate ions play an important role in boron treatment and immobilization, especially by using sulfate bands. Therefore, the immobilization of boron is dramatically increased.
(2) The required amount of lime may be determined according to the batch addition process, and the required amount of sulfuric acid band may be determined by the post-treatment concentration and the set value of the viscosity of the reaction solution.
(3) The stirring time for the coagulation sedimentation treatment shall be 90 minutes or more. However, since the boron removal rate decreases after 90 minutes, the reaction is completed as soon as possible.
(4) Confirm that the liquid viscosity during the coagulation sedimentation treatment is 100 mPa · s or more. However, when the addition amount of the sulfuric acid band is small, it may be less than 100 mPa · s, so the relationship between the viscosity and the boron fixation rate is confirmed for each waste liquid.
(5) The firing conditions are a temperature of 500 to 600 ° C. and a time of 15 minutes or more.
請求項１に記載された発明に係る凝集沈殿汚泥中のホウ素固定化法は、ホウ素廃液に対して凝集剤を添加し、消石灰(Ｃａ(ＯＨ)２)によってｐＨ１０以上に調整してホウ素を凝集沈殿処理した凝集沈殿汚泥中のホウ素固定化法であって、
前記凝集沈殿汚泥には、消石灰由来のカルシウム以外にアルミニウムと硫酸基とを含み、
前記消石灰(Ｃａ(ＯＨ) ２ )が、ｐＨ１０を超えてエトリンガイト様化合物(ホウ素吸着汚泥)の生成反応が進行する区間を経てｐＨ１１以上に調整されるまで添加され、
前記凝集沈殿汚泥を４００℃以上７７０℃未満の条件で１５分以上加熱することを特徴とするものである。
Boron immobilization method in flocculation sludge according to the invention described in claim 1, by adding an aggregating agent to boron waste, boron and adjusted to pH10 or by extinguishing lime (Ca (OH) 2) A method for fixing boron in a coagulated sediment sludge that has been coagulated and precipitated,
Wherein the coagulation-sedimentation sludge, including aluminum and sulfate groups in addition to the calcium-derived anti lime,
The slaked lime (Ca (OH) 2 ) is added until the pH is adjusted to 11 or more through a section where the production reaction of ettringite-like compound (boron adsorption sludge) proceeds beyond
The agglomerated sedimentation sludge is heated under conditions of 400 ° C. or higher and lower than 770 ° C. for 15 minutes or longer .
請求項４に記載された発明に係るホウ素固定化法は、ホウ素廃液に対して硫酸バンド(Ａｌ２(ＳＯ４)３)を添加し、消石灰(Ｃａ(ＯＨ)２)によってｐＨ１１以上に調整してホウ素を凝集沈殿処理した凝集沈殿汚泥中のホウ素固定化法であって、
前記消石灰(Ｃａ(ＯＨ) ２ )が、ｐＨ１０を超えてエトリンガイト様化合物(ホウ素吸着汚泥)の生成反応が進行する区間を経てｐＨ１１以上に調整されるまで添加され、
前記凝集沈殿汚泥を５００〜６００℃の条件で３０分以上加熱することを特徴とするものである。
Boron immobilization method according to the invention described in
The slaked lime (Ca (OH) 2 ) is added until the pH is adjusted to 11 or more through a section where the production reaction of ettringite-like compound (boron adsorption sludge) proceeds beyond
The agglomerated sedimentation sludge is heated at 500 to 600 ° C. for 30 minutes or more .
そこで、高いホウ素固定力を示す汚泥を形成するために必要な石灰乳添加量のポイントを見極めるために、図４のｂ図に示す４ポイント((a) ｐＨ１０、(b) ｐＨ１１(第２停滞区間始点、ｐＨ１１ａ)、(c) 第２停滞区間中点（ｐＨ１１ｂ）、(d) ｐＨ１１．２(第２停滞区間終点、ｐＨ１１ｃ)について、そのホウ素処理性及びホウ素固定率を調査した。 凝集沈殿処理の条件は、ｂ図上の各ポイントに相当する石灰添加量を一括で添加し、その後１５０分間撹拌した。その結果、石灰乳の添加量に従い反応液粘度が上がり、その粘度に従ってホウ素除去効率が向上した。特に、ポイント(d) ｐＨ１１ｃにおいては、99.0％を示した。 Therefore, in order to ascertain the point of the lime milk addition amount necessary for forming sludge showing a high boron fixing force, 4 points ((a) pH10, (b) pH11 (second stagnation) shown in FIG. Section start point, pH 11a), (c) Second stagnation section midpoint (pH 11b), (d) pH 11.2 (second stagnation section end point, pH 11c) was examined for boron treatability and boron fixation rate. The treatment conditions were as follows: lime addition amount corresponding to each point on Fig. B was added all at once, and then stirred for 150 minutes, and as a result, the viscosity of the reaction solution increased according to the addition amount of lime milk, and boron removal efficiency according to the viscosity. In particular, the point (d) was 99.0% at pH 11c.
Claims (4)
前記凝集沈殿汚泥には、石灰由来のカルシウム以外にアルミニウムと硫酸基とを含み、
前記凝集沈殿汚泥を４００℃以上７７０℃未満の条件で加熱することを特徴とする凝集沈殿汚泥中のホウ素固定化法。 A method for fixing boron in a coagulation sedimentation sludge in which a coagulant is added to a boron waste liquid and the pH is adjusted to 10 or more with lime (Ca (OH) 2 ) to coagulate and precipitate boron.
In addition to calcium derived from lime, the aggregated sludge contains aluminum and sulfate groups,
A method for immobilizing boron in a coagulated sediment sludge, characterized in that the coagulated sediment sludge is heated under conditions of 400 ° C or higher and lower than 770 ° C.
前記凝集沈殿汚泥を５００〜６００℃の条件で加熱することを特徴とする凝集沈殿汚泥中のホウ素固定化法。 Addition of sulfuric acid band (Al 2 (SO 4 ) 3 ) to boron waste liquor, adjusting the pH to 11 or more with lime (Ca (OH) 2 ) and coagulating and precipitating boron in the coagulated sediment sludge Because
A method for immobilizing boron in a coagulated sediment sludge, wherein the coagulated sediment sludge is heated under conditions of 500 to 600 ° C.
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