JP2012012230A - Method for producing waste acid gypsum - Google Patents
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- JP2012012230A JP2012012230A JP2010147674A JP2010147674A JP2012012230A JP 2012012230 A JP2012012230 A JP 2012012230A JP 2010147674 A JP2010147674 A JP 2010147674A JP 2010147674 A JP2010147674 A JP 2010147674A JP 2012012230 A JP2012012230 A JP 2012012230A
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- 239000002699 waste material Substances 0.000 title claims abstract description 126
- 239000002253 acid Substances 0.000 title claims abstract description 125
- 229910052602 gypsum Inorganic materials 0.000 title claims abstract description 113
- 239000010440 gypsum Substances 0.000 title claims abstract description 113
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 28
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 37
- 229910052785 arsenic Inorganic materials 0.000 claims abstract description 31
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 claims abstract description 31
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 24
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000003513 alkali Substances 0.000 claims abstract description 14
- 230000033116 oxidation-reduction process Effects 0.000 claims abstract description 12
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical compound [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 claims abstract description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052802 copper Inorganic materials 0.000 claims abstract description 9
- 239000010949 copper Substances 0.000 claims abstract description 9
- 238000003723 Smelting Methods 0.000 claims description 16
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical group [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 14
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 9
- 239000000292 calcium oxide Substances 0.000 claims description 9
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 7
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 7
- 239000000920 calcium hydroxide Substances 0.000 claims description 7
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 7
- 239000002002 slurry Substances 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 6
- 238000005486 sulfidation Methods 0.000 claims description 6
- CUGMJFZCCDSABL-UHFFFAOYSA-N arsenic(3+);trisulfide Chemical compound [S-2].[S-2].[S-2].[As+3].[As+3] CUGMJFZCCDSABL-UHFFFAOYSA-N 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 238000010306 acid treatment Methods 0.000 claims 1
- 238000005987 sulfurization reaction Methods 0.000 abstract description 8
- 238000007670 refining Methods 0.000 abstract 1
- 239000007788 liquid Substances 0.000 description 25
- 239000002562 thickening agent Substances 0.000 description 19
- 229910001385 heavy metal Inorganic materials 0.000 description 13
- 239000000243 solution Substances 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 11
- 239000000203 mixture Substances 0.000 description 11
- 229910052725 zinc Inorganic materials 0.000 description 8
- 239000011701 zinc Substances 0.000 description 8
- 239000002244 precipitate Substances 0.000 description 7
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 5
- 238000004065 wastewater treatment Methods 0.000 description 5
- 229910052793 cadmium Inorganic materials 0.000 description 4
- 239000000706 filtrate Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 150000004763 sulfides Chemical class 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000003252 repetitive effect Effects 0.000 description 2
- 229910052979 sodium sulfide Inorganic materials 0.000 description 2
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 2
- 239000011550 stock solution Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- OMZSGWSJDCOLKM-UHFFFAOYSA-N copper(II) sulfide Chemical compound [S-2].[Cu+2] OMZSGWSJDCOLKM-UHFFFAOYSA-N 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- SRRKNRDXURUMPP-UHFFFAOYSA-N sodium disulfide Chemical compound [Na+].[Na+].[S-][S-] SRRKNRDXURUMPP-UHFFFAOYSA-N 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Removal Of Specific Substances (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
Description
本発明は、銅製錬で発生する廃酸からの廃酸石膏の製造方法に関する。 The present invention relates to a method for producing waste acid gypsum from waste acid generated in copper smelting.
銅製錬で発生する亜硫酸ガスは、回収された後、硫酸製造の原料とされる。その処理段階の前段で、亜硫酸ガスを工業用水等の冷却水で洗浄・冷却する工程があるが、当該冷却水中には砒素を中心に銅、亜鉛、カドミウム等の重金属を含んだ薄硫酸、いわゆる廃酸（硫酸濃度１００〜３００ｇ／ｌ）が発生する。通常、廃酸は炭酸カルシウム、酸化カルシウム等のアルカリで中和を行い、石膏を製造することで処理される。 Sulfurous acid gas generated in copper smelting is recovered and used as a raw material for sulfuric acid production. Before the treatment stage, there is a process of washing and cooling the sulfurous acid gas with cooling water such as industrial water, but the cooling water contains thin sulfuric acid containing heavy metals such as copper, zinc and cadmium mainly in arsenic, so-called Waste acid (sulfuric acid concentration 100 to 300 g / l) is generated. Usually, waste acid is treated by neutralizing with alkali such as calcium carbonate and calcium oxide to produce gypsum.
このような廃酸を原料とした石膏（以下、廃酸石膏とする）の製造技術として、例えば、特許文献１には、銅製錬において発生する硫酸濃度１００〜２００ｇ／ｌの廃酸に水硫化ソーダを添加して酸化還元電位が０±１０ｍＶとなるまで硫化を行い、亜鉛以外の重金属類を硫化物として除去した後、清澄液に炭酸カルシウムを加え、ｐＨを２．０〜３．５の範囲となるように中和して石膏を製造することを特徴とする低不純物品位の廃酸石膏製造方法が開示されている（特許文献１の図１及び明細書の段落００１４〜００１８）。そして、これによれば、不純物を多く含む廃酸から低不純物品位の石膏を製造する方法を提供し、あわせて重金属の硫化殿物中に亜鉛を含ませないようにし、石膏製造工程の負荷の軽減を図ることのできる廃酸石膏の製造方法を提供することができると記載されている（特許文献１の明細書の段落００２６）。 As a technology for producing such gypsum using waste acid as a raw material (hereinafter referred to as waste acid gypsum), for example, Patent Document 1 discloses hydrosulfurization to waste acid having a sulfuric acid concentration of 100 to 200 g / l generated in copper smelting. Add soda and sulfidize until the oxidation-reduction potential becomes 0 ± 10 mV. After removing heavy metals other than zinc as sulfides, add calcium carbonate to the clarified liquid, and adjust the pH to 2.0 to 3.5. A method for producing waste acid gypsum having a low impurity quality, characterized in that it is neutralized to a range to produce gypsum (FIG. 1 of Patent Document 1 and paragraphs 0014 to 0018 of the specification). According to this, a method for producing low-impurity grade gypsum from waste acid containing a large amount of impurities is provided, and in addition, zinc is not included in the heavy metal sulfide, and the load of the gypsum production process is reduced. It is described that a method for producing waste acid gypsum that can be reduced can be provided (paragraph 0026 of the specification of Patent Document 1).
また、特許文献２には、硫化剤を用いて砒素を硫化物として沈殿させ、かつ濾過補助剤を併用して硫化砒素を分離させることによって、廃棄物に含まれる硫酸からヒ素を除去する技術が開示されている。特許文献２では、９９％以上の良好なヒ素の分離度を達成するため、該硫化剤として硫化ナトリウムと二硫化ナトリウムの混合水溶液を用い、Ｈ2Ｓ雰囲気を維持した状態で、廃棄物に含まれる硫酸の砒素含有量によって該硫化ナトリウムの量を調整している。 Patent Document 2 discloses a technique for removing arsenic from sulfuric acid contained in waste by precipitating arsenic as a sulfide using a sulfurizing agent and separating the arsenic sulfide together with a filter aid. It is disclosed. In Patent Document 2, in order to achieve a good arsenic separability of 99% or more, a mixed aqueous solution of sodium sulfide and sodium disulfide is used as the sulfiding agent, and the H 2 S atmosphere is maintained. The amount of sodium sulfide is adjusted according to the arsenic content of sulfuric acid.
しかしながら、特許文献１に記載の発明では、廃酸に水硫化ソーダを添加して酸化還元電位が０±１０ｍＶとなるまで硫化を行い、亜鉛以外の重金属類を全て硫化物として除去するとしているが、これでは水硫化ソーダの使用量が多く、コスト面で不利である。
また、特許文献２に記載の発明においては、廃酸から砒素を良好な回収率で回収しているが、それのみでは重金属を回収した後の廃酸から高純度の廃酸石膏を製造することができない。
However, in the invention described in Patent Document 1, sodium hydrosulfide is added to the waste acid to perform sulfidization until the redox potential becomes 0 ± 10 mV, and all heavy metals other than zinc are removed as sulfides. In this case, the amount of sodium hydrosulfide used is large, which is disadvantageous in terms of cost.
Moreover, in the invention described in Patent Document 2, arsenic is recovered from waste acid at a good recovery rate, but by itself, high-purity waste acid gypsum is produced from waste acid after recovering heavy metals. I can't.
そこで、本発明は、高純度の廃酸石膏を低コストで製造することを課題とする。 Then, this invention makes it a subject to manufacture high-purity waste acid gypsum at low cost.
本発明者は、鋭意検討した結果、廃酸中の酸化還元電位が２０〜１５０ｍＶ（ｖｓ．ＳＣＥ）となるように硫化反応を行うことで選択的に廃酸から砒素を除去し、その後、中和反応によって廃酸石膏を作製することで、硫化工程での水硫化ソーダの使用量を抑え、且つ、高純度の廃酸石膏を作製できることを見出した。すなわち、廃酸に含まれる砒素を選択的に硫化物として除去することによって、後に作製される第１の廃酸石膏への付着水からの砒素の混入を良好に抑制することができる。具体的には、第１の廃酸石膏中の砒素の含有率を０．００４質量％以下に抑制することができる。また、砒素を廃酸液から選択的に除去・回収することで、自溶炉等の溶錬炉への繰り返し物中の砒素の装入量を容易に制御することが出来る。尚、上記の硫化工程において、廃酸中に含まれる銅成分も硫化物として除去される。 As a result of intensive studies, the present inventor selectively removed arsenic from the waste acid by performing a sulfurization reaction so that the oxidation-reduction potential in the waste acid becomes 20 to 150 mV (vs. SCE). It has been found that by producing waste acid gypsum by a sum reaction, the amount of sodium hydrosulfide used in the sulfidation step can be suppressed and high-purity waste acid gypsum can be produced. That is, by selectively removing arsenic contained in the waste acid as a sulfide, mixing of arsenic from the adhering water to the first waste acid gypsum produced later can be well suppressed. Specifically, the arsenic content in the first waste acid gypsum can be suppressed to 0.004% by mass or less. Further, by selectively removing and recovering arsenic from the waste acid solution, it is possible to easily control the amount of arsenic in the repetitive material into a smelting furnace such as a flash smelting furnace. In the above sulfiding step, the copper component contained in the waste acid is also removed as a sulfide.
以上の知見を基礎として完成した本発明は一側面において、銅製錬において発生する硫酸を含んだ廃酸に水硫化ソーダを加え、酸化還元電位を２０〜１５０ｍＶ（ｖｓ．ＳＣＥ）に調整して硫化反応を行い、砒素を硫化物として除去する工程と、砒素の硫化物を除去した廃酸にアルカリを加えて中和反応を行うことで石膏を作製する工程とを備えた廃酸石膏の製造方法である。 In one aspect, the present invention completed based on the above knowledge is obtained by adding sodium hydrosulfide to waste acid containing sulfuric acid generated in copper smelting and adjusting the oxidation-reduction potential to 20 to 150 mV (vs. SCE). A method for producing waste acid gypsum comprising: a step of performing a reaction to remove arsenic as sulfide; and a step of preparing gypsum by adding an alkali to waste acid from which arsenic sulfide has been removed to perform a neutralization reaction It is.
本発明に係る廃酸石膏の製造方法の一実施形態においては、石膏を作製する工程は、廃酸にアルカリを加えてｐＨ１．２〜１．６に調整して第１の中和反応を行い、第１の廃酸石膏を作製する工程と、第１の廃酸石膏を除去した後の廃酸にアルカリを加えてｐＨ９．５〜１１．０に調整して第２の中和反応を行い、不純物金属を含んだ第２の廃酸石膏を作製する工程とを備える。 In one embodiment of the method for producing waste acid gypsum according to the present invention, the step of producing gypsum performs the first neutralization reaction by adjusting the pH to 1.2 to 1.6 by adding alkali to the waste acid. The step of producing the first waste acid gypsum and the second neutralization reaction by adjusting the pH to 9.5 to 11.0 by adding alkali to the waste acid after the removal of the first waste acid gypsum And a step of producing a second waste acid gypsum containing an impurity metal.
本発明に係る廃酸石膏の製造方法の別の実施形態においては、第１の廃酸石膏を作製する工程に使用されるアルカリが、炭酸カルシウム、酸化カルシウム、又は、水酸化カルシウムであり、第２の廃酸石膏を作製する工程に使用されるアルカリが、酸化カルシウム、又は、水酸化カルシウムである。 In another embodiment of the method for producing waste acid gypsum according to the present invention, the alkali used in the step of producing the first waste acid gypsum is calcium carbonate, calcium oxide, or calcium hydroxide, The alkali used in the step of producing the waste acid gypsum of 2 is calcium oxide or calcium hydroxide.
本発明に係る廃酸石膏の製造方法の更に別の実施形態においては、第２の廃酸石膏は回収されて、自溶炉又は溶錬炉へ繰り返し原料として利用される。 In still another embodiment of the method for producing waste acid gypsum according to the present invention, the second waste acid gypsum is recovered and repeatedly used as a raw material in a flash smelting furnace or a smelting furnace.
本発明に係る廃酸石膏の製造方法の更に別の実施形態においては、第２の中和反応において生成される石膏スラリーの一部を第１の中和反応で用いる中和槽に戻す工程を更に備える。 In still another embodiment of the method for producing waste acid gypsum according to the present invention, the step of returning a part of the gypsum slurry produced in the second neutralization reaction to the neutralization tank used in the first neutralization reaction is performed. In addition.
本発明によれば、廃酸中の酸化還元電位が２０〜１５０ｍＶ（ｖｓ．ＳＣＥ）となるように硫化反応を行うことで選択的に廃酸から砒素を除去し、その後、中和反応によって廃酸石膏を作製する。これにより、硫化工程での水硫化ソーダの使用量を抑えることができ、さらに廃酸石膏における砒素の含有量が良好に抑制される。従って、高純度の廃酸石膏を低コストで製造することができる。 According to the present invention, arsenic is selectively removed from the waste acid by performing a sulfurization reaction so that the oxidation-reduction potential in the waste acid is 20 to 150 mV (vs. SCE), and then the waste acid is discarded by a neutralization reaction. Make acid gypsum. Thereby, the usage-amount of sodium hydrosulfide in a sulfidation process can be suppressed, and also content of arsenic in waste acid gypsum is suppressed favorably. Therefore, high-purity waste acid gypsum can be produced at low cost.
（廃酸石膏の製造方法）
図１に、本発明に係る廃酸石膏の製造方法のフローチャートを示す。
本発明に係る廃酸石膏の製造方法は、まず、銅製錬において発生する廃酸を硫化反応槽へ供給し、これに水硫化ソーダを加え、酸化還元電位を２０〜１５０ｍＶ（ｖｓ．ＳＣＥ）に調整して硫化反応を行う。次に、これを硫化物シックナーへ移し、沈殿物（砒素、銅の硫化物）をフィルタープレスで除去し、濾液を硫化物シックナーへ戻す。
前述したように、特許文献１では、酸化還元電位を０±１０ｍＶとして当該硫化反応により、亜鉛以外の重金属を全て硫化物として除去するとしているが、その場合、水硫化ソーダの使用量が多く、製造コストが高くなる。
これに対し、本発明は、酸化還元電位を２０〜１５０ｍＶ（ｖｓ．ＳＣＥ）に調整して硫化反応を行うことで、廃酸に含まれる主として砒素を選択的に硫化物として除去する。このため、次工程で作製される第１の廃酸石膏への付着水からの砒素の混入を良好に抑制することができる。具体的には、第１の廃酸石膏中砒素の含有率を０．００４質量％以下に抑制することができる。また、砒素を選択的に除去・回収することで、自溶炉等の溶錬炉への繰り返し物中の砒素の装入量を容易に操作することが出来る。
ここで、酸化還元電位を２０〜１５０ｍＶ（ｖｓ．ＳＣＥ）に調整するのは、酸化還元電位が１５０ｍＶを超えると砒素を十分に回収できず、後工程へ砒素が流れてしまうという問題が生じるためであり、一方、酸化還元電位が２０ｍＶ未満では特許文献１に記載の技術のように、水硫化ソーダの使用量が増え、製造コストが高くなるという問題が生じるためである。
(Method for producing waste acid gypsum)
In FIG. 1, the flowchart of the manufacturing method of the waste acid gypsum based on this invention is shown.
In the method for producing waste acid gypsum according to the present invention, first, waste acid generated in copper smelting is supplied to a sulfidation reaction tank, and sodium hydrosulfide is added thereto, so that the oxidation-reduction potential is 20 to 150 mV (vs. SCE). Adjust and perform sulfurization reaction. This is then transferred to a sulfide thickener where the precipitate (arsenic, copper sulfide) is removed with a filter press and the filtrate is returned to the sulfide thickener.
As described above, in Patent Document 1, the oxidation-reduction potential is set to 0 ± 10 mV, and all heavy metals other than zinc are removed as sulfides by the sulfurization reaction. In that case, the amount of sodium hydrosulfide used is large, Manufacturing cost increases.
On the other hand, the present invention selectively removes mainly arsenic contained in the waste acid as a sulfide by adjusting the oxidation-reduction potential to 20 to 150 mV (vs. SCE) and performing a sulfurization reaction. For this reason, mixing of the arsenic from adhering water to the 1st waste acid gypsum produced at the next process can be suppressed favorably. Specifically, the content of arsenic in the first waste acid gypsum can be suppressed to 0.004% by mass or less. Further, by selectively removing and collecting arsenic, the amount of arsenic in the repetitive material to a smelting furnace such as a flash smelting furnace can be easily manipulated.
Here, the reason for adjusting the oxidation-reduction potential to 20 to 150 mV (vs. SCE) is that if the oxidation-reduction potential exceeds 150 mV, arsenic cannot be sufficiently recovered and arsenic flows to the subsequent process. On the other hand, when the oxidation-reduction potential is less than 20 mV, the amount of sodium hydrosulfide used increases as in the technique described in Patent Document 1, and the production cost increases.
次に、硫化物シックナーのオーバーフロー液を回収し、石膏反応槽へ移す。続いて、炭酸カルシウム、酸化カルシウム、又は、水酸化カルシウム等のアルカリを石膏反応槽へ加え、ｐＨ１．２〜１．６に調整して第１の中和反応を行う。第１の中和反応をｐＨ１．２未満とした場合、第２の廃酸石膏工程へ移る硫酸の成分が多くなり、これを中和するための炭酸カルシウムや酸化カルシウム、水酸化カルシウムといった中和剤の使用量が増加し、製造コストが高くなるという問題が生じる。また、第１の中和反応のｐＨが高ければ、それだけ多くの砒素が沈殿物（第１の廃酸石膏）に含まれる。このため、第１の中和反応はｐＨ１．６以下で行われている。
続いて、石膏反応槽の反応液を石膏シックナーへ移し、沈殿物を遠心分離機、フィルタープレスなどの濾過機にかけた後、液体分を濾過することにより、残った固体分である廃酸石膏（第１の廃酸石膏）を得る。この廃酸石膏は、上述のようにｐＨ１．２〜１．６の範囲において中和反応を行っていることにより、重金属の混入が抑制され、純度の高い石膏となっている。このようにして作製された廃酸石膏（第１の廃酸石膏）は、重金属の混入が抑制されているため、外販用としての品質を十分に確保している。
なお、このように中和反応においてｐＨが２未満であると、石膏の粒子が微細化し、石膏の脱水性が悪くなり、輸送費用が高くなるという問題が生じる。そこで、第２の中和反応槽内の廃酸溶液（石膏スラリー）の一部を第１の中和反応槽に繰り返し循環するように配管で接続し、第２中和槽の廃酸溶液の液面表面の高さに対して１／２以下となる高さ位置から石膏スラリーを第１中和槽の液面表面へ供給されるようにして液循環させてもよい。このように石膏スラリーを循環させることによって局部的な石膏溶質濃度の上昇による微細結晶核の発生を抑制し、石膏の粒子を大きく成長させることができる。
Next, the overflow liquid of the sulfide thickener is collected and transferred to the gypsum reaction tank. Subsequently, an alkali such as calcium carbonate, calcium oxide, or calcium hydroxide is added to the gypsum reaction tank, and the pH is adjusted to 1.2 to 1.6 to perform the first neutralization reaction. When the first neutralization reaction is less than pH 1.2, more sulfuric acid components are transferred to the second waste acid gypsum process, and neutralization such as calcium carbonate, calcium oxide, and calcium hydroxide is performed to neutralize this. The problem is that the amount of the agent used increases and the production cost increases. If the pH of the first neutralization reaction is high, more arsenic is contained in the precipitate (first waste acid gypsum). For this reason, the first neutralization reaction is performed at pH 1.6 or less.
Subsequently, the reaction liquid in the gypsum reaction tank is transferred to a gypsum thickener, the precipitate is applied to a filter such as a centrifuge or a filter press, and the liquid content is filtered, so that waste acid gypsum (residual solid content) First waste acid gypsum) is obtained. As described above, the waste acid gypsum is neutralized in the pH range of 1.2 to 1.6, so that mixing of heavy metals is suppressed and the gypsum is highly purified. Since the waste acid gypsum (first waste acid gypsum) produced in this way is prevented from being mixed with heavy metals, the quality for use in external sales is sufficiently ensured.
If the pH is less than 2 in the neutralization reaction as described above, the gypsum particles become finer, the dehydration property of the gypsum becomes worse, and the transportation cost increases. Therefore, a part of the waste acid solution (gypsum slurry) in the second neutralization reaction tank is connected by piping so as to circulate repeatedly to the first neutralization reaction tank, and the waste acid solution in the second neutralization tank The gypsum slurry may be circulated so that the gypsum slurry is supplied to the liquid surface of the first neutralization tank from a height position that is ½ or less of the height of the liquid surface. By circulating the gypsum slurry in this manner, generation of fine crystal nuclei due to a local increase in the gypsum solute concentration can be suppressed, and gypsum particles can be grown greatly.
次に、遠心分離機やフィルタープレスなどの濾過機にかけた後に得られた濾液を第１の廃酸石膏シックナーに戻す。続いて第１の廃酸石膏シックナーのオーバーフロー液を回収し、第２の中和槽へ移す。続いて、酸化カルシウムや水酸化カルシウム等のアルカリを加え、ｐＨ９．５〜１１．０に調整して第２の中和反応を行う。第２の中和反応をｐＨ９．５〜１１．０に調整して行うのは、廃酸中に含まれるＣｄ及びＺｎがこの範囲で全て水酸化物として回収することができるためである。このとき、ｐＨ９．５未満であれば、Ｃｄ及びＺｎの水酸化物としての反応が進行せず、廃酸溶液中に溶解したままとなり、第２の廃酸石膏中で回収することができないという問題点があり、一方、ｐＨ１１．０超の場合、一旦水酸化物となったＣｄ及びＺｎ等が再び廃酸溶液中に溶け出すという点で問題となる。
続いて、第２中和槽内の廃酸溶液（石膏スラリー）を第２の廃酸石膏シックナーへ移し、沈殿物を遠心分離機にかけ、固液分離した後、残った固体分である廃酸石膏（第２の廃酸石膏）を得る。この廃酸石膏は、上述のようにｐＨ９．５〜１１．０の条件で中和反応を行っているので、第１の中和反応後に廃酸溶液中に残留している重金属を水酸化物として第２の廃酸石膏中に含ませることができる。このようにして製造した廃酸石膏（第２の廃酸石膏）は、自溶炉又は溶錬炉へ繰り返し原料として利用することができる。
Next, the filtrate obtained after passing through a filter such as a centrifugal separator or a filter press is returned to the first waste acid gypsum thickener. Subsequently, the overflow liquid of the first waste acid gypsum thickener is collected and transferred to the second neutralization tank. Subsequently, an alkali such as calcium oxide or calcium hydroxide is added to adjust the pH to 9.5 to 11.0, and a second neutralization reaction is performed. The reason why the second neutralization reaction is adjusted to pH 9.5 to 11.0 is that Cd and Zn contained in the waste acid can all be recovered as hydroxide in this range. At this time, if the pH is less than 9.5, the reaction as a hydroxide of Cd and Zn does not proceed and remains dissolved in the waste acid solution and cannot be recovered in the second waste acid gypsum. On the other hand, when the pH is more than 11.0, there is a problem in that Cd, Zn and the like once converted into hydroxides are dissolved again in the waste acid solution.
Subsequently, the waste acid solution (gypsum slurry) in the second neutralization tank is transferred to the second waste acid gypsum thickener, the precipitate is subjected to a centrifuge, solid-liquid separated, and the waste acid that is the remaining solid content Gypsum (second waste acid gypsum) is obtained. Since the waste acid gypsum is neutralized under the conditions of pH 9.5 to 11.0 as described above, the heavy metal remaining in the waste acid solution after the first neutralization reaction is converted into hydroxide. As a second waste acid gypsum. The waste acid gypsum thus produced (second waste acid gypsum) can be repeatedly used as a raw material in a flash smelting furnace or a smelting furnace.
次に、第２の廃酸石膏シックナーから、遠心分離機やフィルタープレスなどの濾過機を通り、得られた濾液を再び第２の廃酸石膏シックナーに戻す。そして、第２の廃酸石膏シックナーでオーバーフローされる分の廃酸溶液は、排水処理設備へ移される。上述のように、原料廃酸に含まれていた重金属系の不純物が上記各工程によってほとんど回収されているため、排水処理設備における排水処理工程に加わる負荷が軽減されている。 Next, the second waste acid gypsum thickener is passed through a filter such as a centrifugal separator or a filter press, and the obtained filtrate is returned to the second waste acid gypsum thickener again. Then, the waste acid solution overflowed by the second waste acid gypsum thickener is transferred to the waste water treatment facility. As described above, since the heavy metal impurities contained in the raw material waste acid are almost recovered by the respective steps, the load applied to the wastewater treatment step in the wastewater treatment facility is reduced.
以下、本発明の実施例を示すが、これらは本発明をより良く理解するために提供するものであり、本発明が限定されることを意図するものではない。 EXAMPLES Examples of the present invention will be described below, but these are provided for better understanding of the present invention and are not intended to limit the present invention.
（実施例）
表１に示す硫酸及び重金属を含む廃酸原液を硫化反応槽へ供給し、酸化還元電位が７０ｍＶ（ｖｓ．ＳＣＥ）になるように水硫化ソーダを加えて硫化反応を行った。廃酸中の砒素成分は０〜４ｇ／Ｌであった。
(Example)
A waste acid stock solution containing sulfuric acid and heavy metals shown in Table 1 was supplied to a sulfurization reaction tank, and sodium hydrosulfide was added so as to have a redox potential of 70 mV (vs. SCE), and a sulfurization reaction was performed. The arsenic component in the waste acid was 0 to 4 g / L.
次に、反応液を硫化物シックナーへ移し、沈殿物（硫化砒素を主成分とする硫化物）をフィルタープレスで除去し、濾液を硫化物シックナーへ戻した。 Next, the reaction solution was transferred to a sulfide thickener, the precipitate (sulfide containing arsenic sulfide as a main component) was removed with a filter press, and the filtrate was returned to the sulfide thickener.
次に、硫化物シックナーのオーバーフロー液を回収し、石膏反応槽へ移す。また、このオーバーフロー液を採取して液組成を測定した。当該組成を表１に併せて示す（硫化後液）。続いて、炭酸カルシウムを石膏反応槽へ加え、ｐＨ１．２〜１．６に調整して第１の中和反応を行った。続いて、石膏反応槽の反応液を第１の廃酸石膏シックナーへ移し、沈殿物を遠心分離機にかけ、固液分離後に、残った固体分である廃酸石膏（第１の廃酸石膏）を得た。表２に、このとき得た廃酸石膏（第１の廃酸石膏）の組成の分析結果を示す。 Next, the overflow liquid of the sulfide thickener is collected and transferred to the gypsum reaction tank. Moreover, this overflow liquid was extract | collected and the liquid composition was measured. The composition is also shown in Table 1 (liquid after sulfidation). Subsequently, calcium carbonate was added to the gypsum reaction tank, and the pH was adjusted to 1.2 to 1.6 to perform the first neutralization reaction. Subsequently, the reaction solution in the gypsum reaction tank is transferred to the first waste acid gypsum thickener, the precipitate is subjected to a centrifuge, and after solid-liquid separation, waste acid gypsum (first waste acid gypsum) that remains is a solid content. Got. Table 2 shows the analysis results of the composition of the waste acid gypsum (first waste acid gypsum) obtained at this time.
次に、遠心分離機にかけ、固液分離後の液体分を第１の廃酸石膏シックナーに戻した。続いて石膏シックナーのオーバーフロー液を回収し、中和槽へ移した。また、このオーバーフロー液を採取して液組成を測定した。当該組成を表１に併せて示す（中和後液１）。 Next, it was centrifuged and the liquid content after solid-liquid separation was returned to the first waste acid gypsum thickener. Subsequently, the overflow liquid of gypsum thickener was collected and transferred to a neutralization tank. Moreover, this overflow liquid was extract | collected and the liquid composition was measured. The said composition is combined with Table 1 (after-neutralization liquid 1).
続いて、第２の中和槽へ酸化カルシウムを加え、ｐＨ９．５〜１１．０に調整して第２の中和反応を行った。続いて、第２中和槽の廃酸溶液を第２の石膏シックナーへ移し、沈殿物を遠心分離機にかけ、固液分離後の残った固体分である廃酸石膏（第２の廃酸石膏）を得た。表２に、このとき得た廃酸石膏（第２の廃酸石膏）の組成の分析結果を併せて示す。 Subsequently, calcium oxide was added to the second neutralization tank to adjust the pH to 9.5 to 11.0, and a second neutralization reaction was performed. Subsequently, the waste acid solution in the second neutralization tank is transferred to the second gypsum thickener, the precipitate is subjected to a centrifuge, and the waste acid gypsum (second waste acid gypsum) that remains after solid-liquid separation. ) Table 2 also shows the analysis results of the composition of the waste acid gypsum (second waste acid gypsum) obtained at this time.
次に、遠心分離機で第２の廃酸石膏を分離した際に得られた液体分を第２の廃酸石膏シックナーに戻す。続いて第２の廃酸石膏シックナーのオーバーフロー液を採取して液組成を測定した。当該組成を表１に併せて示す（中和後液２）。 Next, the liquid obtained when the second waste acid gypsum is separated by the centrifuge is returned to the second waste acid gypsum thickener. Subsequently, an overflow liquid of the second waste acid gypsum thickener was collected and the liquid composition was measured. The said composition is combined with Table 1 (after-neutralization liquid 2).
（評価結果）
表１及び表２に示す結果より、廃酸原液の硫化によって、砒素（Ａｓ）が選択的に除去され、その後の第１の廃酸石膏の作製をｐＨ１．２〜１．６で、第２の廃酸石膏の作製をｐＨ９．５〜１１．０でそれぞれ行うことにより、外販製品となる第１の廃酸石膏及び排水処理に送る中和後液２に砒素がほとんど含まれていないことが確認された。
表２の組成分析により、第１の廃酸石膏には不純物がほとんど含まれていないことが確認された。
表２の組成分析により、砒素以外の重金属が第２の廃酸石膏に含まれることによって回収されたことが確認された。
表１の中和後液２の組成分析により、最後に排水処理設備へ送られる液には硫酸及び重金属がほとんど含まれていないことが確認された。
(Evaluation results)
From the results shown in Tables 1 and 2, arsenic (As) is selectively removed by sulfidation of the waste acid stock solution, and the subsequent production of the first waste acid gypsum at pH 1.2 to 1.6, The production of the waste acid gypsum at pH 9.5 to 11.0 respectively results in that the first waste acid gypsum to be sold externally and the neutralized solution 2 sent to the wastewater treatment contain almost no arsenic. confirmed.
From the composition analysis in Table 2, it was confirmed that the first waste acid gypsum contained almost no impurities.
The composition analysis in Table 2 confirmed that heavy metals other than arsenic were recovered by being included in the second waste acid gypsum.
The composition analysis of the post-neutralization liquid 2 in Table 1 confirmed that the liquid finally sent to the wastewater treatment facility contains almost no sulfuric acid and heavy metals.
Claims (5)
前記砒素の硫化物を除去した廃酸にアルカリを加えて中和反応を行うことで石膏を作製する工程と、
を備えた廃酸石膏の製造方法。 Waste acid treatment process that removes arsenic as sulfide by adding sodium hydrosulfide to waste acid containing sulfuric acid generated in copper smelting, adjusting oxidation-reduction potential to 20-150 mV (vs. SCE), and performing sulfidation reaction When,
A step of producing gypsum by adding an alkali to the waste acid from which the arsenic sulfide has been removed, and performing a neutralization reaction;
A method for producing waste acid gypsum comprising:
前記廃酸にアルカリを加えてｐＨ１．２〜１．６に調整して第１の中和反応を行い、第１の廃酸石膏を作製する工程と、
前記第１の廃酸石膏を除去した後の廃酸にアルカリを加えてｐＨ９．５〜１１．０に調整して第２の中和反応を行い、不純物金属を含んだ第２の廃酸石膏を作製する工程と、
を備える請求項１に記載の廃酸石膏の製造方法。 The step of producing the gypsum includes
Adding the alkali to the waste acid to adjust the pH to 1.2 to 1.6, performing a first neutralization reaction, and producing a first waste acid gypsum;
A second waste acid gypsum containing an impurity metal is obtained by adding an alkali to the waste acid after removing the first waste acid gypsum to adjust the pH to 9.5 to 11.0 and performing a second neutralization reaction. A step of producing
A method for producing waste acid gypsum according to claim 1.
前記第２の廃酸石膏を作製する工程に使用されるアルカリが、酸化カルシウム、又は、水酸化カルシウムである請求項２に記載の廃酸石膏の製造方法。 The alkali used in the step of producing the first waste acid gypsum is calcium carbonate, calcium oxide, or calcium hydroxide,
The method for producing waste acid gypsum according to claim 2, wherein the alkali used in the step of producing the second waste acid gypsum is calcium oxide or calcium hydroxide.
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| CL2010001189A1 (en) | 2011-03-11 |
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