JP4306394B2 - Cement kiln extraction dust processing method - Google Patents
Cement kiln extraction dust processing method Download PDFInfo
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- 239000000428 dust Substances 0.000 title claims description 23
- 239000004568 cement Substances 0.000 title claims description 22
- 238000000605 extraction Methods 0.000 title claims description 10
- 238000003672 processing method Methods 0.000 title description 6
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 claims description 47
- 229910052711 selenium Inorganic materials 0.000 claims description 47
- 239000011669 selenium Substances 0.000 claims description 47
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 42
- -1 salt compound Chemical class 0.000 claims description 36
- 239000007788 liquid Substances 0.000 claims description 34
- 229920000642 polymer Polymers 0.000 claims description 28
- 238000000926 separation method Methods 0.000 claims description 28
- 229910001385 heavy metal Inorganic materials 0.000 claims description 21
- 239000007791 liquid phase Substances 0.000 claims description 19
- 239000002738 chelating agent Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 13
- 229910000360 iron(III) sulfate Inorganic materials 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 9
- 239000002002 slurry Substances 0.000 claims description 8
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 7
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 7
- 239000011790 ferrous sulphate Substances 0.000 claims description 7
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 7
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 7
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 7
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 6
- 229910052744 lithium Inorganic materials 0.000 claims description 6
- 229910052708 sodium Inorganic materials 0.000 claims description 6
- 239000011734 sodium Substances 0.000 claims description 6
- DKVNPHBNOWQYFE-UHFFFAOYSA-N carbamodithioic acid Chemical group NC(S)=S DKVNPHBNOWQYFE-UHFFFAOYSA-N 0.000 claims description 5
- 229910052700 potassium Inorganic materials 0.000 claims description 5
- 229960002089 ferrous chloride Drugs 0.000 claims description 4
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 150000001875 compounds Chemical class 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 claims description 3
- 229920002401 polyacrylamide Polymers 0.000 claims description 3
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 claims description 3
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 claims 2
- 150000003573 thiols Chemical class 0.000 claims 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 18
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 12
- 239000000460 chlorine Substances 0.000 description 12
- 229910052801 chlorine Inorganic materials 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 239000003513 alkali Substances 0.000 description 10
- 239000000706 filtrate Substances 0.000 description 9
- 238000003911 water pollution Methods 0.000 description 9
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
- YHGPYBQVSJBGHH-UHFFFAOYSA-H iron(3+);trisulfate;pentahydrate Chemical compound O.O.O.O.O.[Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O YHGPYBQVSJBGHH-UHFFFAOYSA-H 0.000 description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 7
- 229910052742 iron Inorganic materials 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 239000002351 wastewater Substances 0.000 description 7
- NQXWGWZJXJUMQB-UHFFFAOYSA-K iron trichloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].Cl[Fe+]Cl NQXWGWZJXJUMQB-UHFFFAOYSA-K 0.000 description 6
- 239000011593 sulfur Substances 0.000 description 6
- 229910052717 sulfur Inorganic materials 0.000 description 6
- 229940032296 ferric chloride Drugs 0.000 description 5
- 229940044631 ferric chloride hexahydrate Drugs 0.000 description 5
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000007790 solid phase Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 4
- 239000003002 pH adjusting agent Substances 0.000 description 4
- 125000003396 thiol group Chemical class [H]S* 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 3
- 239000000920 calcium hydroxide Substances 0.000 description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 150000004687 hexahydrates Chemical class 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 235000014413 iron hydroxide Nutrition 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 229910052793 cadmium Inorganic materials 0.000 description 2
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- XNCMOUSLNOHBKY-UHFFFAOYSA-H iron(3+);trisulfate;heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O XNCMOUSLNOHBKY-UHFFFAOYSA-H 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000012488 sample solution Substances 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 239000010802 sludge Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 150000004684 trihydrates Chemical class 0.000 description 2
- CHRJZRDFSQHIFI-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;styrene Chemical compound C=CC1=CC=CC=C1.C=CC1=CC=CC=C1C=C CHRJZRDFSQHIFI-UHFFFAOYSA-N 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- KIECCKFSGCJGTM-UHFFFAOYSA-N O[Se](O)=O.[SeH2] Chemical compound O[Se](O)=O.[SeH2] KIECCKFSGCJGTM-UHFFFAOYSA-N 0.000 description 1
- 229920002873 Polyethylenimine Polymers 0.000 description 1
- LIKWJCOGLYRYIU-UHFFFAOYSA-N [Se](O)(O)(=O)=O.[Se] Chemical compound [Se](O)(O)(=O)=O.[Se] LIKWJCOGLYRYIU-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 229920005601 base polymer Polymers 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000003925 fat Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 150000004688 heptahydrates Chemical class 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 238000010169 landfilling Methods 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 150000004686 pentahydrates Chemical class 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920001281 polyalkylene Polymers 0.000 description 1
- 229920000768 polyamine Polymers 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical group [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 description 1
- GWQWBFBJCRDINE-UHFFFAOYSA-M sodium;carbamodithioate Chemical group [Na+].NC([S-])=S GWQWBFBJCRDINE-UHFFFAOYSA-M 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 150000004685 tetrahydrates Chemical class 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
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- Processing Of Solid Wastes (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
- Removal Of Specific Substances (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Description
本発明は、セメントキルンの塩素、アルカリ、及び硫黄の循環を低減するために、塩素バイパス等の抽気装置を用い焼成ガスの一部を抽気した際に同伴する、セレンを含むダスト（以下、抽気ダストと称す）の処理方法に関するものである。 In order to reduce the circulation of chlorine, alkali, and sulfur in a cement kiln, the present invention is a dust containing selenium (hereinafter, extracted air) that is accompanied when a part of the calcination gas is extracted using an extraction device such as a chlorine bypass. (Referred to as dust).
塩素、アルカリ、硫黄含有物の多いセメント原料を使用した場合、セメントクリンカー中に含まれる塩素、アルカリ、硫黄の量が多くなり、セメントの品質に悪影響を与える。また、塩素、アルカリ、硫黄は蒸気圧の高い化合物を形成し、セメントキルン内においてガス化して循環する前に、装置内の比較的温度の低い部分で凝縮してコーティングを形成するため、セメント製造上のトラブルの原因ともなっている。
この問題を解決するために、セメントキルンの窯尻部分から焼成ガスの一部を抽気して、セメントキルン内を循環する塩素、アルカリ、硫黄の量を低減することが行われている。
When a cement raw material containing a large amount of chlorine, alkali, and sulfur is used, the amount of chlorine, alkali, and sulfur contained in the cement clinker increases, which adversely affects cement quality. In addition, chlorine, alkali, and sulfur form a compound with high vapor pressure, and before it is gasified and circulated in the cement kiln, it is condensed at a relatively low temperature in the equipment to form a coating. It is also the cause of the above trouble.
In order to solve this problem, a part of the firing gas is extracted from the kiln bottom portion of the cement kiln to reduce the amount of chlorine, alkali, and sulfur circulating in the cement kiln.
しかし、このような焼成ガスの抽気を行うと、塩素、アルカリ、硫黄の含有量が多い抽気ダストが必然的に同伴し、この抽気ダストの処理方法が新たに問題になってくる。即ち、抽気ダストには塩素、アルカリ、硫黄以外にも鉛、カドミニウム、クロム、マンガン、鉄、セレンなど、水質汚濁防止法で規制された有害物質が含まれており、抽気ダストを未処理のまま埋め立て、廃棄を行えば環境汚染を引き起こすため、適切な方法で処理する必要がある。また、抽気ダストを廃棄するのではなく、セメント原料として再利用する場合にも、抽気ダスト中に含まれるアルカリ、塩素の量を低減した後に原料系に戻す必要がある。 However, when such a calcination gas is extracted, extraction dust having a large content of chlorine, alkali, and sulfur is inevitably accompanied, and the processing method of this extraction dust becomes a new problem. In other words, in addition to chlorine, alkali and sulfur, extracted dust contains lead, cadmium, chromium, manganese, iron, selenium and other harmful substances regulated by the Water Pollution Control Law, and the extracted dust remains untreated. Landfilling and disposal can cause environmental pollution and should be handled in an appropriate manner. Even when the extracted dust is not discarded but reused as a cement raw material, it is necessary to reduce the amount of alkali and chlorine contained in the extracted dust and then return to the raw material system.
抽気ダストに含まれるアルカリ、塩素化合物は水溶性であるから、除去するには水洗処理が最も適しており、既に公知である（例えば特許文献１及び２）。しかしながら、本文献では、水処理の際、アルカリ、塩素化合物と一緒に溶出してくる重金属を含む有害物質の処理方法に関する報告はされてない。
重金属の処理方法としては、特許文献３に、４価セレン及び６価セレン（以下全セレンと称す）の処理方法に関する報告がされている。本文献では、全セレンの含有量が１．６ｍｇ／ｌの排水に、硫酸第一鉄・七水和物を全セレン量の２８３２倍モル量、塩化第二鉄・六水和物を全セレン量の９４５倍モル量添加し、ｐＨを９に調整して３０分間攪拌し、フィルタープレスでろ別除去した後の残存ろ液の全セレン濃度が０．０４ｍｇ/ｌになることが報告されている。しかしながら、本方法では多量の６価セレンが溶存しているセレン含有水の場合、多量の第一鉄と第二鉄が必要で凝集沈殿が困難となり、また、処理費用も高価となり、実用化が困難になる恐れが生じる。
Since alkali and chlorine compounds contained in the bleed dust are water-soluble, washing with water is most suitable for removal, and already known (for example, Patent Documents 1 and 2). However, in this document, there is no report regarding a method for treating harmful substances including heavy metals that are eluted together with alkali and chlorine compounds during water treatment.
As a method for treating heavy metals, Patent Document 3 reports a method for treating tetravalent selenium and hexavalent selenium (hereinafter referred to as all selenium). In this document, wastewater with a total selenium content of 1.6 mg / l is mixed with ferrous sulfate heptahydrate 2832 times the total selenium amount and ferric chloride hexahydrate with total selenium. It has been reported that the total selenium concentration of the remaining filtrate after addition of 945 times the amount, adjusting the pH to 9 and stirring for 30 minutes and filtering off with a filter press is 0.04 mg / l. . However, in this method, in the case of selenium-containing water in which a large amount of hexavalent selenium is dissolved, a large amount of ferrous and ferric iron is required, so that coagulation and precipitation are difficult, and the processing cost is expensive, so that it can be put into practical use. It can be difficult.
特許文献４では、硫酸第一鉄を２価の鉄イオン量換算で溶存セレン量の４０から８０重量倍量添加し、ｐＨを８．５〜１０に調節して２０から３０分間攪拌して、全セレンが水酸化第一鉄に対して吸着固定されると報告されている。しかしながら、処理水の全セレン含有量は０．２から０．４ｍｇ／ｌであり、水質汚濁防止法に係る排水基準値の０．１ｍｇ／ｌ以下を達成できていない。 In Patent Document 4, ferrous sulfate is added in an amount of 40 to 80 times the amount of dissolved selenium in terms of the amount of divalent iron ions, the pH is adjusted to 8.5 to 10 and stirred for 20 to 30 minutes, It has been reported that all selenium is adsorbed and immobilized on ferrous hydroxide. However, the total selenium content of the treated water is 0.2 to 0.4 mg / l, and the wastewater standard value of 0.1 mg / l or less according to the Water Pollution Control Law cannot be achieved.
本発明は、セメントキルン抽気ダストを水洗処理し、固形分はセメント原料として再利用し、通常の３価の鉄イオンでは処理できないセレンが含有している水洗液を、水質汚濁防止法に係る排水基準値以下に除去して放流廃棄を可能にする処理方法を提供することを目的とする。 The present invention is a waste water treatment method for water pollution treatment, in which cement kiln extraction dust is washed with water, solid content is reused as a cement raw material, and selenium containing selenium that cannot be treated with normal trivalent iron ions is contained. It aims at providing the processing method which makes it possible to discharge and discard by removing below a reference value.
本発明者らは鋭意検討を行った結果、上記目的を達成し得ることを知見した。
すなわち、本発明は、以下の各工程からなることを特徴とするセメントキルン抽気ダストの処理方法に関する。
（１）セメントキルン抽気ダストに水を加えてスラリー化した後、固液分離する第１工程、
（２）第１工程で得られた固液分離後の液相（以下、原水と称す）のｐＨを５〜１０に調節し、重金属除去用キレート剤を添加し、第二鉄塩化合物を添加した後、更に液相のｐＨを５〜１０に再調節し、高分子凝集剤を添加し、固液分離する第２工程であり、
前記第２工程の重金属除去用キレート剤が、ジチオカルバミン酸基（＞Ｎ−ＣＳ ２ Ｘ、但しＸはＨ、Ｌｉ、Ｎａ、Ｋ、Ｃａ １／２ 、Ｍｇ １／２ を示す）及び／又はチオール基（−ＳＹ、但しＹはＨ、Ｌｉ、Ｎａ、Ｋを示す）を有する高分子化合物であり、該重金属除去用キレート剤の添加量が、前記原水中の鉛イオンに対して０.２〜３当量であり、
前記第２工程の第二鉄塩化合物が、塩化第二鉄、硫酸第二鉄、ポリ硫酸第二鉄、又はこれらの水和物であり、該第二鉄塩化合物の添加量が、前記重金属除去用キレート剤に対して５〜２０重量倍量であり、
（３）第２工程で得られた固液分離後の液相に、第一鉄塩化合物を添加し、ｐＨを８〜１２に調節した後、高分子凝集剤を添加し、固液分離を行う第３工程、
前記第３工程の第一鉄塩化合物が、塩化第一鉄、硫酸第一鉄、又はこれらの水和物であり、該第一鉄塩化合物の添加量が、前記原水中の６価セレンに対して５０〜３００倍モル量であり、
（４）第３工程で得られた固液分離後の液相に、第二鉄塩化合物を添加し、ｐＨを８〜１２に調節した後、高分子凝集剤を添加し、固液分離を行う第４工程。
前記第４工程の第二鉄塩化合物が、塩化第二鉄、硫酸第二鉄、ポリ硫酸第二鉄、又はこれらの水和物であり、該第二鉄塩化合物の添加量が、前記原水中の全セレンに対して３０〜１２０倍モル量であり、
前記第２工程〜第４工程の高分子凝集剤が、ポリアクリルアミド又はポリアクリル酸ソーダを含む高分子凝集剤であり、該高分子凝集剤の添加量が０.２〜４ｍｇ／ｌである。
As a result of intensive studies, the present inventors have found that the above object can be achieved.
That is, this invention relates to the processing method of the cement kiln extraction dust characterized by including the following processes.
(1) A first step in which water is added to cement kiln extraction dust to form a slurry, followed by solid-liquid separation,
(2) The pH of the liquid phase after solid-liquid separation obtained in the first step (hereinafter referred to as raw water) is adjusted to 5-10, a chelating agent for removing heavy metals is added, and a ferric salt compound is added. Then, the pH of the liquid phase is readjusted to 5 to 10, and the polymer flocculant is added , followed by solid-liquid separation .
The chelating agent for heavy metal removal in the second step is a dithiocarbamic acid group (> N-CS 2 X, where X represents H, Li, Na, K, Ca 1/2 , Mg 1/2 ) and / or thiol. A high molecular compound having a group (-SY, where Y represents H, Li, Na, K), and the amount of the heavy metal removing chelating agent added is 0.2 to 0.2 with respect to lead ions in the raw water. 3 equivalents,
The ferric salt compound of the second step is ferric chloride, ferric sulfate, polyferric sulfate, or a hydrate thereof, and the amount of the ferric salt compound added is the heavy metal 5 to 20 times the amount of the chelating agent for removal,
(3) The ferrous salt compound is added to the liquid phase after solid-liquid separation obtained in the second step, the pH is adjusted to 8 to 12, and then the polymer flocculant is added to perform solid-liquid separation. A third step to perform,
The ferrous salt compound in the third step is ferrous chloride, ferrous sulfate, or a hydrate thereof, and the added amount of the ferrous salt compound is hexavalent selenium in the raw water. The molar amount is 50 to 300 times,
(4) A ferric salt compound is added to the liquid phase after solid-liquid separation obtained in the third step, the pH is adjusted to 8 to 12, and then a polymer flocculant is added to perform solid-liquid separation. 4th process to perform.
The ferric salt compound of the fourth step is ferric chloride, ferric sulfate, polyferric sulfate, or a hydrate thereof, and the added amount of the ferric salt compound is 30-120 times the molar amount of the total selenium in water,
The polymer flocculant in the second to fourth steps is a polymer flocculant containing polyacrylamide or sodium polyacrylate, and the amount of the polymer flocculant added is 0.2 to 4 mg / l.
本発明のセメントキルン抽気ダストの処理方法を実施すると、除去が極めて困難な６価セレンを４価に還元し固相として捕集し、固液分離後の液相中の全セレン（４価セレン、６価セレン）を水質汚濁防止法に係る排水基準値を充分クリアする程度まで低減することができ、放流が可能になる。
また、還元剤として用いる第一鉄塩化合物の添加量が少量であるため、少量の高分子凝集剤の添加で沈降分離が短時間で容易になる。その為、固相であるスラッジ量が少なくなりスラッジの脱水処理も容易になる。
さらに、固形分は、セメント原料としての再利用が可能になる。
When the cement kiln extraction dust processing method of the present invention is carried out, hexavalent selenium, which is extremely difficult to remove, is reduced to tetravalent and collected as a solid phase, and all selenium (tetravalent selenium in the liquid phase after solid-liquid separation) is collected. , Hexavalent selenium) can be reduced to a level that sufficiently satisfies the drainage standard value according to the Water Pollution Control Law, and can be discharged.
Moreover, since the addition amount of the ferrous salt compound used as the reducing agent is small, sedimentation separation is facilitated in a short time by adding a small amount of the polymer flocculant. Therefore, the amount of sludge that is a solid phase is reduced and the sludge is easily dewatered.
Furthermore, the solid content can be reused as a cement raw material.
以下に本発明を詳細に説明する。また、本発明に係るセメントキルン抽気ダストの処理方法のフローを図１に示す。
本発明の第１工程は、セメントキルン抽気ダストに水を加えてスラリー化した後、固液分離する工程である。この工程で、塩化カリウム、塩化ナトリウム、及び塩化カルシウム等のアルカリ金属塩を溶出させ固相として捕集する。抽気ダストの主成分は、アルカリ金属塩であることから、生成スラリーは高ｐＨ値を示す。水の添加量は固液分離した液相の塩素濃度が２質量％以下になるように加える。一般に海水の塩素濃度は０.００５〜２質量％であり、液相の塩素濃度が２質量％以下であれば、処理排水をそのまま放流可能である。
The present invention is described in detail below. Moreover, the flow of the processing method of the cement kiln extraction dust which concerns on this invention is shown in FIG.
The first step of the present invention is a step of solid-liquid separation after adding water to the cement kiln bleed dust to form a slurry. In this step, alkali metal salts such as potassium chloride, sodium chloride, and calcium chloride are eluted and collected as a solid phase. Since the main component of the extracted dust is an alkali metal salt, the resulting slurry exhibits a high pH value. The amount of water added is such that the concentration of chlorine in the liquid phase after solid-liquid separation is 2% by mass or less. Generally, the chlorine concentration of seawater is 0.005 to 2% by mass, and the treated wastewater can be discharged as it is if the chlorine concentration of the liquid phase is 2% by mass or less.
本発明の第２工程は、第１工程で固液分離した液相（原水）のｐＨを５〜１０に調節し、重金属除去用キレート剤を添加し、第二鉄塩化合物を添加した後、更に液相のｐＨを５〜１０に再調節し、高分子凝集剤を添加し、固液分離する工程である。この工程で、鉛、カドミウム、クロム等の重金属、並びに一部の４価セレンを、水酸化鉄と共沈させ、固相として捕集する。 In the second step of the present invention, after adjusting the pH of the liquid phase (raw water) separated in the first step to 5 to 10, adding a chelating agent for removing heavy metals, and adding a ferric salt compound, Further, the pH of the liquid phase is readjusted to 5 to 10, a polymer flocculant is added, and solid-liquid separation is performed. In this step, heavy metals such as lead, cadmium, and chromium, and some tetravalent selenium are co-precipitated with iron hydroxide and collected as a solid phase.
原水のｐＨ調節剤としては、例えば、塩酸、硫酸、又は硝酸等が挙げられる。ｐＨは５〜１０、好ましくは６〜８に調節する。
重金属除去用キレート剤添加後の液相のｐＨ調節剤としては、例えば、水酸化ナトリウム、水酸化カルシウム等が挙げられる。ｐＨは５〜１０、好ましくは６〜８に調節する。
Examples of the raw water pH adjuster include hydrochloric acid, sulfuric acid, and nitric acid. The pH is adjusted to 5-10, preferably 6-8.
Examples of the liquid phase pH adjuster after addition of the chelating agent for heavy metal removal include sodium hydroxide and calcium hydroxide. The pH is adjusted to 5-10, preferably 6-8.
重金属除去用キレート剤としては、キレート形成基としてジチオカルバミン酸基（＞Ｎ−ＣＳ２Ｘ、但しＸはＨ、Ｌｉ、Ｎａ、Ｋ、Ｃａ／２、Ｍｇ／２を示す）及び／又はチオール基（−ＳＹ、但しＹはＨ、Ｌｉ、Ｎａ、Ｋを示す）を有する高分子化合物を用いることが出来る。例えば、スチレン−ジビニルベンゼン系樹脂、フェノール樹脂等の母体樹脂にジチオカルバミン酸基および／またはチオール基が導入された固体状高分子、ポリアルキレンポリアミンにジチオカルバミン酸基および／またはチオール基が導入された、重金属と結合してフロックを形成する液状の高分子を挙げることが出来る。
中でも、ポリエチレンイミンをベースポリマとし、分子内にジチオカルバミン酸ナトリウム基およびナトリウムメルカプチド基を有する液状の水溶性高分子キレート剤の使用が特に好ましく、この特性を有する市販の高分子キレート剤が原液のまま、または希釈水溶液として使用出来る。
As a chelating agent for removing heavy metals, a dithiocarbamic acid group (> N-CS 2 X, where X represents H, Li, Na, K, Ca / 2, Mg / 2) and / or a thiol group ( -SY, where Y represents H, Li, Na, or K) can be used. For example, a solid polymer in which a dithiocarbamic acid group and / or a thiol group is introduced into a base resin such as a styrene-divinylbenzene-based resin or a phenol resin, and a dithiocarbamic acid group and / or a thiol group is introduced into a polyalkylene polyamine. A liquid polymer that forms a floc by combining with a heavy metal can be used.
In particular, it is particularly preferable to use a liquid water-soluble polymer chelating agent having polyethyleneimine as a base polymer and having a sodium dithiocarbamate group and a sodium mercaptide group in the molecule. It can be used as it is or as a diluted aqueous solution.
重金属除去用キレート剤の添加量は、原水に溶存している鉛イオンに対して０.２〜３当量、好ましくは０.５〜２当量である。
第二鉄塩化合物としては、例えば、塩化第二鉄、塩化第二鉄・六水和物、硫酸第ニ鉄、硫酸第ニ鉄・三水和物、硫酸第ニ鉄・六水和物、硫酸第ニ鉄・七水和物、ポリ硫酸第二鉄等が挙げられる。
第二鉄塩化合物の添加量は、重金属除去用キレート剤に対して５〜１５重量倍量、好ましくは７〜１３重量倍量である。
The addition amount of the chelating agent for removing heavy metals is 0.2 to 3 equivalents, preferably 0.5 to 2 equivalents with respect to lead ions dissolved in the raw water.
Examples of the ferric salt compound include ferric chloride, ferric chloride and hexahydrate, ferric sulfate, ferric sulfate and trihydrate, ferric sulfate and hexahydrate, Examples thereof include ferric sulfate heptahydrate, polyferric sulfate and the like.
The addition amount of the ferric salt compound is 5 to 15 times by weight, preferably 7 to 13 times by weight, with respect to the heavy metal removing chelating agent.
第３工程は、第２工程で固液分離した液相に、第一鉄塩化合物を添加し、ｐＨを８〜１２に調節した後、高分子凝集剤を添加し、固液分離を行う工程である。この工程で、第２工程で捕集されなかった６価セレン（セレン酸）を３価の水酸化鉄と共沈し易い４価セレン（亜セレン酸）に還元させる。
第一鉄塩化合物としては、例えば、塩化第一鉄、塩化第一鉄・二水和物、硫酸第一鉄、硫酸第一鉄・四水和物、硫酸第一鉄・五水和物、硫酸第一鉄・七水和物、ポリ硫酸第一鉄等が挙げられる。
第一鉄塩化合物の添加量は、原水に溶存している６価セレン量に対し、鉄イオン量で５０〜３００倍モル量、好ましくは１００〜２００倍モル量である。
液相のｐＨ調節剤としては、第２工程同様、例えば、水酸化ナトリウム、水酸化カルシウム等が挙げられる。ｐＨは８〜１２、好ましくは９〜１１に調節する。
The third step is a step of performing solid-liquid separation by adding a ferrous salt compound to the liquid phase solid-liquid separated in the second step and adjusting the pH to 8 to 12 and then adding a polymer flocculant. It is. In this step, hexavalent selenium (selenic acid) that has not been collected in the second step is reduced to tetravalent selenium (selenite) that is likely to coprecipitate with trivalent iron hydroxide.
Examples of ferrous salt compounds include ferrous chloride, ferrous chloride and dihydrate, ferrous sulfate, ferrous sulfate and tetrahydrate, ferrous sulfate and pentahydrate, Examples thereof include ferrous sulfate and heptahydrate, polyferrous sulfate and the like.
The addition amount of the ferrous salt compound is 50 to 300-fold mol amount, preferably 100 to 200-fold mol amount in terms of iron ion, with respect to the hexavalent selenium amount dissolved in the raw water.
Examples of the liquid phase pH adjuster include sodium hydroxide and calcium hydroxide as in the second step. The pH is adjusted to 8-12, preferably 9-11.
本発明の第４工程では、第３工程で固液分離した液相に、第二鉄塩化合物を添加し、ｐＨを８〜１２に調節した後、高分子凝集剤を添加し、固液分離を行う工程である。
第二鉄塩化合物としては、例えば、塩化第二鉄、塩化第ニ鉄・六水和物、硫酸第ニ鉄、硫酸第ニ鉄・三水和物、硫酸第ニ鉄・六水和物、硫酸第鉄・七水和物、ポリ硫酸第二鉄等が挙げられる。
第二鉄塩化合物の添加量は、原水に溶存している全セレン量に対し、鉄イオン量で３０〜１２０倍モル量、好ましくは５０〜１００倍モル量添加する。
液相のｐＨ調節剤としては、第２、第３工程同様、例えば、水酸化ナトリウム、水酸化カルシウム等が挙げられる。ｐＨは８〜１２、好ましくは９〜１１に調節する。
In the fourth step of the present invention, the ferric salt compound is added to the liquid phase separated in the third step and the pH is adjusted to 8 to 12, followed by the addition of the polymer flocculant and the solid-liquid separation. It is a process of performing.
Examples of the ferric salt compound include ferric chloride, ferric chloride, hexahydrate, ferric sulfate, ferric sulfate, trihydrate, ferric sulfate, hexahydrate, And ferric sulfate heptahydrate and polyferric sulfate.
The ferric salt compound is added in an amount of 30 to 120 times, preferably 50 to 100 times, the molar amount of iron ions with respect to the total amount of selenium dissolved in the raw water.
Examples of the liquid phase pH adjuster include sodium hydroxide and calcium hydroxide as in the second and third steps. The pH is adjusted to 8-12, preferably 9-11.
本発明の第２〜４工程に添加する高分子凝集剤は、水酸化鉄を主成分とする沈殿の凝集を促進して固液分離を容易にする効果を示す。高分子凝集剤としては、ポリアクリルアミド、又はポリアクリル酸ソーダを含む高分子凝集剤であれば良く、ノニオン系、カチオン系、アニオン系を問わずに使用できる。また高分子凝集剤の添加量は、０.２〜４ｍｇ/ｌ、好ましくは０.５〜２ｍｇ/ｌである。
本発明の第１〜４工程で行う固液分離する方法は、一般に行われている方法、例えば、ろ過法、遠心分離法、沈降分離法等を利用することができる。
第４工程の固液分離で重金属およびセレンを排水基準値以下に低減させた液相は、そのｐＨを中性付近にまで低下させた後、放流することができる。また、第１〜４工程で得られた固相は、鉄を含むため、鉄源としてセメント原料に再利用可能である。
The polymer flocculant added to the second to fourth steps of the present invention has an effect of facilitating the aggregation of the precipitate mainly composed of iron hydroxide and facilitating solid-liquid separation. As the polymer flocculant, any polymer flocculant containing polyacrylamide or sodium polyacrylate may be used, regardless of nonionic, cationic or anionic. The addition amount of the polymer flocculant is 0.2 to 4 mg / l, preferably 0.5 to 2 mg / l.
As a method for solid-liquid separation performed in the first to fourth steps of the present invention, a generally used method such as a filtration method, a centrifugal separation method, a sedimentation separation method, or the like can be used.
The liquid phase in which heavy metal and selenium are reduced to below the drainage standard value by solid-liquid separation in the fourth step can be discharged after the pH is lowered to near neutrality. Moreover, since the solid phase obtained in the first to fourth steps contains iron, it can be reused as a raw material for cement as an iron source.
以下に具体例を示し、本発明を詳細に説明する。また、以下の実施例、比較例の結果を表１に示す。
（実施例１）
抽気ダスト２５０ｇに水２５００ｇを加え、３時間攪拌しスラリー化した。スラリーは１μｍの孔径のメンブランフィルターで固液分離を行った。得られたろ液（以下、原水１と称す）のｐＨは１３．２であった。
The present invention will be described in detail with reference to specific examples. The results of the following examples and comparative examples are shown in Table 1.
Example 1
2500 g of water was added to 250 g of extracted dust and stirred for 3 hours to form a slurry. The slurry was subjected to solid-liquid separation with a membrane filter having a pore size of 1 μm. The pH of the obtained filtrate (hereinafter referred to as raw water 1) was 13.2.
この原水１に含まれる鉛等の重金属類はＪＩＳ Ｋ ０１０２に準拠し、水素化合物ＩＣＰ発光分光分析法により定量した。
また、全セレンは以下の方法で定量した。
即ち、原水１に硫酸及び硝酸を添加し、加熱し硫酸白煙発生後、室温まで放冷し、塩酸を加え、９０〜１００℃で１０分間加熱し、放冷し、試料液とした。この試料液を水素化合物発生原子吸光分析装置にて全セレンの定量を行った。また、４価セレンは原水１を前処理せず、水素化合物発生原子吸光分析装置にて定量を行った。６価セレンは、全セレンから４価セレンを差し引いた値とした。
全セレン（４価セレンと６価セレン）、６価セレンおよび鉛の含有量は夫々１３、１２、１３０ｍｇ/ｌであった。
Heavy metals such as lead contained in the raw water 1 were quantified by hydrogen compound ICP emission spectroscopic analysis in accordance with JIS K 0102.
Further, total selenium was quantified by the following method.
That is, sulfuric acid and nitric acid were added to the raw water 1 and heated to generate sulfuric acid white smoke, then allowed to cool to room temperature, hydrochloric acid was added, heated at 90 to 100 ° C. for 10 minutes, allowed to cool, and used as a sample solution. This sample solution was quantified with a hydrogen compound generation atomic absorption spectrometer. Tetravalent selenium was quantified with a hydrogen compound generation atomic absorption spectrometer without pretreatment of raw water 1. Hexavalent selenium was obtained by subtracting tetravalent selenium from all selenium.
The contents of total selenium (tetravalent selenium and hexavalent selenium), hexavalent selenium and lead were 13, 12, and 130 mg / l, respectively.
上記２５０ｍｌの原水１に硫酸を添加してｐＨを７．５に調節し、それから重金属除去用キレート剤（ミヨシ油脂製エポフレックスＬ−１）を５１．８ｍｇ（鉛に対して１当量）添加して、１０分間攪拌混合した。次いで１ｍｏｌ/ｌの塩化第二鉄・六水和物を１．９ｍｌ（重金属除去用キレート剤の１０重量倍量）添加して、水酸化ナトリウムでｐＨを７．５に調節して５分間攪拌混合した。次いで高分子凝集剤（ダイヤトリニックス製ダイヤフロックＮＰ８００）を１ｍｇ/ｌ添加して１０分間攪拌混合し、静置１０分後にこの処理液を５種Ａのろ紙でろ過した。 Add sulfuric acid to the above 250 ml of raw water 1 to adjust the pH to 7.5, and then add 51.8 mg (1 equivalent to lead) of chelating agent for heavy metal removal (Epoflex L-1 made by Miyoshi Oil & Fats). And stirred for 10 minutes. Next, 1.9 ml of 1 mol / l ferric chloride hexahydrate (10 times the amount of chelating agent for heavy metal removal) was added, the pH was adjusted to 7.5 with sodium hydroxide, and the mixture was stirred for 5 minutes. Mixed. Next, 1 mg / l of a polymer flocculant (Diatrinics Diafloc NP800) was added and stirred and mixed for 10 minutes, and after standing for 10 minutes, the treatment liquid was filtered with 5 types A filter paper.
上記ろ液に硫酸第一鉄・七水和物を１．５８ｇ（原水１に溶存している６価セレン１２ｍｇ/ｌの１５０倍モル量）添加して、水酸化ナトリウムを添加しｐＨを１０に調節し、３０分間攪拌混合した。次いで上記高分子凝集剤を１ｍｇ/ｌ添加して１０分間攪拌混合し、静置１０分後にこの処理液を５種Ａのろ紙でろ過した。 Add 1.58 g of ferrous sulfate heptahydrate to the above filtrate (150 times molar amount of 12 mg / l of hexavalent selenium dissolved in raw water 1), add sodium hydroxide to adjust the pH to 10 And stirred and mixed for 30 minutes. Next, 1 mg / l of the above polymer flocculant was added and stirred and mixed for 10 minutes, and after standing for 10 minutes, the treatment liquid was filtered with 5 types A filter paper.
上記ろ液に１ｍｏｌ/ｌの塩化第二鉄・六水和物を２．９ｍｌ（原水１の全セレン１３ｍｇ/ｌの７０倍モル量）添加して、水酸化ナトリウムを添加しｐＨを１０に調節して３０分間攪拌混合した。次いで上記高分子凝集剤を１ｍｇ/ｌ添加して１０分間攪拌混合し、静置１０分後にこの処理液を５種Ａのろ紙でろ過した。 2.9 ml of 1 mol / l ferric chloride hexahydrate (70 times mol amount of 13 mg / l of total selenium in raw water 1) was added to the filtrate, and sodium hydroxide was added to adjust the pH to 10. The mixture was stirred and mixed for 30 minutes. Next, 1 mg / l of the above polymer flocculant was added and stirred and mixed for 10 minutes, and after standing for 10 minutes, the treatment liquid was filtered with 5 types A filter paper.
上記ろ液を、原水１の分析方法により定量を行った。全セレンは０．０５ｍｇ/ｌであり、水質汚濁防止法に係る排水基準値の０．１ｍｇ/ｌをクリアした。また鉛は０．０５ｍｇ/ｌ（検出限界）以下であり、これも水質汚濁防止法に係る排水基準値の０．１ｍｇ/ｌをクリアした。 The filtrate was quantified by the raw water 1 analysis method. Total selenium was 0.05 mg / l, which cleared the wastewater standard value of 0.1 mg / l according to the Water Pollution Control Law. Lead was 0.05 mg / l (detection limit) or less, which also cleared the wastewater standard value of 0.1 mg / l according to the Water Pollution Control Law.
（比較例１）
実施例１で使用した原水１に、硫酸第一鉄・七水和物を２．８１５ｇ（原水１に溶存している６価セレン１２ｍｇ/ｌの２６７倍モル量）添加して、ｐＨを１０に調節して３０分間攪拌混合した。次いで実施例１で使用した高分子凝集剤を２ｍｇ/ｌ添加して１０分間攪拌混合し、静置１０分後にこの処理液を５種Ａのろ紙でろ過した。
上記ろ液に１ｍｏｌ/ｌの塩化第二鉄・六水和物を２．９ｍｌ（原水１の全セレン１３ｍｇ/ｌの７０倍モル量）添加して、ｐＨを１０に調整して３０分間攪拌混合した。次いで上記高分子凝集剤を２ｍｇ/ｌ添加して１０分間攪拌混合し、静置１０分後にこの処理液を５種Ａのろ紙でろ過した。
上記ろ液を、原水１の分析方法により定量を行った。全セレン量は、０．２９ｍｇ/ｌであり、水質汚濁防止法に係る排水基準値の０．１ｍｇ/ｌをクリアできなかった。また鉛は０．０５ｍｇ/ｌ（検出限界）以下であり、これは水質汚濁防止法に係る排水基準値の０．１ｍｇ/ｌをクリアした。
(Comparative Example 1)
To raw water 1 used in Example 1, 2.815 g of ferrous sulfate heptahydrate (267 times mole amount of 12 mg / l of hexavalent selenium dissolved in raw water 1) was added to adjust the pH to 10 The mixture was stirred and mixed for 30 minutes. Next, 2 mg / l of the polymer flocculant used in Example 1 was added, and the mixture was stirred and mixed for 10 minutes. After standing for 10 minutes, the treatment liquid was filtered with 5 types A filter paper.
2.9 ml of 1 mol / l ferric chloride hexahydrate (70 times molar amount of 13 mg / l of total selenium in raw water 1) was added to the above filtrate, and the pH was adjusted to 10 and stirred for 30 minutes. Mixed. Next, 2 mg / l of the above polymer flocculant was added and stirred and mixed for 10 minutes. After 10 minutes of standing, this treatment liquid was filtered with 5 types A filter paper.
The filtrate was quantified by the raw water 1 analysis method. The total amount of selenium was 0.29 mg / l, and the effluent standard value of 0.1 mg / l according to the Water Pollution Control Law could not be cleared. Moreover, lead is 0.05 mg / l (detection limit) or less, which cleared the wastewater standard value of 0.1 mg / l according to the Water Pollution Control Law.
（比較例２）
抽気ダスト２５０ｇに水２５００ｇを加え、３時間攪拌しスラリー化した。スラリーは１μｍの孔径のメンブランフィルターで固液分離を行った。得られたろ液（以下原水２と称す）のｐＨは１２．２であった。原水２に含まれる全セレンおよび６価セレンの含有量は夫々４５、４ｍｇ/ｌであった。
上記２５０ｍｌの原水２に１ｍｏｌ/ｌの塩化第二鉄・六水和物を１５．５ｍｌ（原水２の全セレン４５ｍｇ/ｌの１０９倍モル量）添加して、ｐＨを１０に調整して３０分間攪拌混合した。次いで実施例１で使用した高分子凝集剤を１ｍｇ/ｌ添加して１０分間攪拌混合し、静置１０分後にこの処理液を５種Ａのろ紙でろ過した。
上記ろ液を、原水１の分析方法により定量を行った。全セレン量は、１．０ｍｇ/ｌであり、水質汚濁防止法に係る排水基準値の０．１ｍｇ/ｌをクリアできなかった。
(Comparative Example 2)
2500 g of water was added to 250 g of extracted dust and stirred for 3 hours to form a slurry. The slurry was subjected to solid-liquid separation with a membrane filter having a pore size of 1 μm. The pH of the obtained filtrate (hereinafter referred to as raw water 2) was 12.2. The contents of total selenium and hexavalent selenium contained in raw water 2 were 45 and 4 mg / l, respectively.
15.5 ml of 1 mol / l ferric chloride hexahydrate (109 times mole amount of 45 mg / l of total selenium in raw water 2) was added to 250 ml of raw water 2 to adjust the pH to 10 and 30 Stir and mix for a minute. Next, 1 mg / l of the polymer flocculant used in Example 1 was added and mixed with stirring for 10 minutes. After 10 minutes of standing, the treatment liquid was filtered with 5 types A filter paper.
The filtrate was quantified by the raw water 1 analysis method. The total amount of selenium was 1.0 mg / l, and the wastewater standard value of 0.1 mg / l according to the Water Pollution Control Law could not be cleared.
１ 第１工程
２ 第２工程
３ 第３工程
４ 第４工程
５ 抽気ダスト
６ セメント原料
７ 放流水
1 First Step 2 Second Step 3 Third Step 4 Fourth Step 5 Extracted Dust 6 Cement Raw Material 7 Effluent Water
Claims (1)
（１）セメントキルン抽気ダストに水を加えてスラリー化した後、固液分離する第１工程、
（２）第１工程で得られた固液分離後の液相（以下、原水と称す）のｐＨを５〜１０に調節し、重金属除去用キレート剤を添加し、第二鉄塩化合物を添加した後、更に液相のｐＨを５〜１０に再調節し、高分子凝集剤を添加し、固液分離する第２工程であり、
前記第２工程の重金属除去用キレート剤が、ジチオカルバミン酸基（＞Ｎ−ＣＳ ２ Ｘ、但しＸはＨ、Ｌｉ、Ｎａ、Ｋ、Ｃａ １／２ 、Ｍｇ １／２ を示す）及び／又はチオール基（−ＳＹ、但しＹはＨ、Ｌｉ、Ｎａ、Ｋを示す）を有する高分子化合物であり、該重金属除去用キレート剤の添加量が、前記原水中の鉛イオンに対して０.２〜３当量であり、
前記第２工程の第二鉄塩化合物が、塩化第二鉄、硫酸第二鉄、ポリ硫酸第二鉄、又はこれらの水和物であり、該第二鉄塩化合物の添加量が、前記重金属除去用キレート剤に対して５〜２０重量倍量であり、
（３）第２工程で得られた固液分離後の液相に、第一鉄塩化合物を添加し、ｐＨを８〜１２に調節した後、高分子凝集剤を添加し、固液分離を行う第３工程、
前記第３工程の第一鉄塩化合物が、塩化第一鉄、硫酸第一鉄、又はこれらの水和物であり、該第一鉄塩化合物の添加量が、前記原水中の６価セレンに対して５０〜３００倍モル量であり、
（４）第３工程で得られた固液分離後の液相に、第二鉄塩化合物を添加し、ｐＨを８〜１２に調節した後、高分子凝集剤を添加し、固液分離を行う第４工程。
前記第４工程の第二鉄塩化合物が、塩化第二鉄、硫酸第二鉄、ポリ硫酸第二鉄、又はこれらの水和物であり、該第二鉄塩化合物の添加量が、前記原水中の全セレンに対して３０〜１２０倍モル量であり、
前記第２工程〜第４工程の高分子凝集剤が、ポリアクリルアミド又はポリアクリル酸ソーダを含む高分子凝集剤であり、該高分子凝集剤の添加量が０.２〜４ｍｇ／ｌである。 A cement kiln bleed dust treatment method comprising the following steps.
(1) A first step in which water is added to cement kiln extraction dust to form a slurry, followed by solid-liquid separation,
(2) The pH of the liquid phase after solid-liquid separation obtained in the first step (hereinafter referred to as raw water) is adjusted to 5-10, a chelating agent for removing heavy metals is added, and a ferric salt compound is added. Then, the pH of the liquid phase is readjusted to 5 to 10, and the polymer flocculant is added , followed by solid-liquid separation .
The chelating agent for heavy metal removal in the second step is a dithiocarbamic acid group (> N-CS 2 X, where X represents H, Li, Na, K, Ca 1/2 , Mg 1/2 ) and / or thiol. A high molecular compound having a group (-SY, where Y represents H, Li, Na, K), and the amount of the heavy metal removing chelating agent added is 0.2 to 0.2 with respect to lead ions in the raw water. 3 equivalents,
The ferric salt compound of the second step is ferric chloride, ferric sulfate, polyferric sulfate, or a hydrate thereof, and the amount of the ferric salt compound added is the heavy metal 5 to 20 times the amount of the chelating agent for removal,
(3) The ferrous salt compound is added to the liquid phase after solid-liquid separation obtained in the second step, the pH is adjusted to 8 to 12, and then the polymer flocculant is added to perform solid-liquid separation. A third step to perform,
The ferrous salt compound in the third step is ferrous chloride, ferrous sulfate, or a hydrate thereof, and the added amount of the ferrous salt compound is hexavalent selenium in the raw water. The molar amount is 50 to 300 times,
(4) A ferric salt compound is added to the liquid phase after solid-liquid separation obtained in the third step, the pH is adjusted to 8 to 12, and then a polymer flocculant is added to perform solid-liquid separation. 4th process to perform.
The ferric salt compound of the fourth step is ferric chloride, ferric sulfate, polyferric sulfate, or a hydrate thereof, and the added amount of the ferric salt compound is 30-120 times the molar amount of the total selenium in water,
The polymer flocculant in the second to fourth steps is a polymer flocculant containing polyacrylamide or sodium polyacrylate, and the amount of the polymer flocculant added is 0.2 to 4 mg / l.
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