CN102719657A - Method for recycling heavy metal in electroplating sludge - Google Patents
Method for recycling heavy metal in electroplating sludge Download PDFInfo
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- CN102719657A CN102719657A CN2012102408923A CN201210240892A CN102719657A CN 102719657 A CN102719657 A CN 102719657A CN 2012102408923 A CN2012102408923 A CN 2012102408923A CN 201210240892 A CN201210240892 A CN 201210240892A CN 102719657 A CN102719657 A CN 102719657A
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- copper
- electroplating sludge
- thiobacillus
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- 239000010802 sludge Substances 0.000 title claims abstract description 384
- 238000009713 electroplating Methods 0.000 title claims abstract description 203
- 238000000034 method Methods 0.000 title claims abstract description 54
- 229910001385 heavy metal Inorganic materials 0.000 title claims abstract description 40
- 238000004064 recycling Methods 0.000 title claims abstract description 21
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 268
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 134
- 229910052802 copper Inorganic materials 0.000 claims abstract description 116
- 239000010949 copper Substances 0.000 claims abstract description 116
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 115
- 238000002386 leaching Methods 0.000 claims abstract description 51
- 241000605272 Acidithiobacillus thiooxidans Species 0.000 claims abstract description 50
- 238000004070 electrodeposition Methods 0.000 claims abstract description 44
- 239000012535 impurity Substances 0.000 claims abstract description 43
- 239000000203 mixture Substances 0.000 claims abstract description 27
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims description 87
- 238000006243 chemical reaction Methods 0.000 claims description 58
- 239000001963 growth medium Substances 0.000 claims description 57
- 241000605222 Acidithiobacillus ferrooxidans Species 0.000 claims description 48
- 239000000843 powder Substances 0.000 claims description 32
- 238000012258 culturing Methods 0.000 claims description 29
- 238000000926 separation method Methods 0.000 claims description 28
- 238000011084 recovery Methods 0.000 claims description 27
- 241001052560 Thallis Species 0.000 claims description 24
- 241000605118 Thiobacillus Species 0.000 claims description 23
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 23
- 239000002244 precipitate Substances 0.000 claims description 23
- 239000010936 titanium Substances 0.000 claims description 23
- 229910052719 titanium Inorganic materials 0.000 claims description 23
- 241000894006 Bacteria Species 0.000 claims description 22
- 238000000605 extraction Methods 0.000 claims description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 19
- 238000001914 filtration Methods 0.000 claims description 19
- 239000002245 particle Substances 0.000 claims description 18
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 239000010865 sewage Substances 0.000 claims description 16
- 229910000570 Cupronickel Inorganic materials 0.000 claims description 15
- YOCUPQPZWBBYIX-UHFFFAOYSA-N copper nickel Chemical compound [Ni].[Cu] YOCUPQPZWBBYIX-UHFFFAOYSA-N 0.000 claims description 15
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 14
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 14
- 239000013049 sediment Substances 0.000 claims description 14
- 230000003203 everyday effect Effects 0.000 claims description 13
- 238000007873 sieving Methods 0.000 claims description 13
- 239000006228 supernatant Substances 0.000 claims description 13
- 239000000706 filtrate Substances 0.000 claims description 12
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims description 12
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 11
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 11
- 239000011575 calcium Substances 0.000 claims description 11
- 229910052791 calcium Inorganic materials 0.000 claims description 11
- 229910052742 iron Inorganic materials 0.000 claims description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 238000005273 aeration Methods 0.000 claims description 9
- 239000011541 reaction mixture Substances 0.000 claims description 9
- 239000007787 solid Substances 0.000 claims description 9
- 238000000227 grinding Methods 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 7
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 7
- 241000193830 Bacillus <bacterium> Species 0.000 claims description 6
- 229960004887 ferric hydroxide Drugs 0.000 claims description 6
- 239000011790 ferrous sulphate Substances 0.000 claims description 6
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 6
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 claims description 6
- 239000004576 sand Substances 0.000 claims description 6
- 239000011775 sodium fluoride Substances 0.000 claims description 6
- 235000013024 sodium fluoride Nutrition 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 5
- 239000011593 sulfur Substances 0.000 claims description 5
- 229910052717 sulfur Inorganic materials 0.000 claims description 5
- 238000007605 air drying Methods 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- BZSXEZOLBIJVQK-UHFFFAOYSA-N 2-methylsulfonylbenzoic acid Chemical compound CS(=O)(=O)C1=CC=CC=C1C(O)=O BZSXEZOLBIJVQK-UHFFFAOYSA-N 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 3
- 241001468182 Acidobacterium Species 0.000 claims 1
- 238000012216 screening Methods 0.000 abstract description 4
- 238000003756 stirring Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 96
- 229910052751 metal Inorganic materials 0.000 description 14
- 239000002184 metal Substances 0.000 description 14
- 230000001580 bacterial effect Effects 0.000 description 12
- 238000010790 dilution Methods 0.000 description 12
- 239000012895 dilution Substances 0.000 description 12
- 238000007747 plating Methods 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 10
- 230000003247 decreasing effect Effects 0.000 description 10
- 239000002609 medium Substances 0.000 description 10
- 150000002739 metals Chemical class 0.000 description 10
- 229910052748 manganese Inorganic materials 0.000 description 9
- 239000011572 manganese Substances 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- 238000001035 drying Methods 0.000 description 7
- 239000002893 slag Substances 0.000 description 6
- 238000007865 diluting Methods 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- ZDFBXXSHBTVQMB-UHFFFAOYSA-N 2-ethylhexoxy(2-ethylhexyl)phosphinic acid Chemical compound CCCCC(CC)COP(O)(=O)CC(CC)CCCC ZDFBXXSHBTVQMB-UHFFFAOYSA-N 0.000 description 3
- 239000008223 sterile water Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 241000304886 Bacilli Species 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 2
- 229910052564 epsomite Inorganic materials 0.000 description 2
- 238000009854 hydrometallurgy Methods 0.000 description 2
- 239000002054 inoculum Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 230000001954 sterilising effect Effects 0.000 description 2
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 241000186146 Brevibacterium Species 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- 241000233866 Fungi Species 0.000 description 1
- 238000003794 Gram staining Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000001651 autotrophic effect Effects 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Inorganic materials [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 description 1
- 229910000396 dipotassium phosphate Inorganic materials 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- FLTRNWIFKITPIO-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe] FLTRNWIFKITPIO-UHFFFAOYSA-N 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
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
Classifications
-
- 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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- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention discloses a method for recycling heavy metal in electroplating sludge. The method comprises the following steps of: carrying out screening and acclimatizing to obtain thelloobacillus ferrooxidans and thiobacillus thiooxidans which have resistance of high-concentration heavy metal; under a certain condition, respectively stirring and mixing the thelloobacillus ferrooxidans and the thiobacillus thiooxidans with the electroplating sludge together; biologically leaching the mixture so as to obtain copper-contained leach liquor or nickel-contained leach liquor; and carrying out electrodeposition on the copper-contained leach liquor after removal of impurities, so as to recycle copper, and carrying out the electrodeposition on the nickel-contained leach liquor after the removal of the impurities, so as to recycle nickel.
Description
Technical Field
The invention relates to a method for recovering metals in electroplating sludge, in particular to a method for recycling heavy metals in electroplating sludge.
Background
Electroplating is one of three major global pollution industries today. According to incomplete statistics, more than 1 million electroplating enterprises in China discharge electroplating wastewater of about 40 billions of cubic meters every year in the electroplating industry. Such a large amount of electroplating wastewater is chemically treated to produce electroplating sludge containing a large amount of heavy metals (heavy metals generally refer to metals having a density of 5 or more, specifically, metals having an atomic number of 24 or more in the periodic table of elements). The heavy metals with the largest content of the electroplating sludge are Cu, Ni, Zn, Cr and Fe. The electroplating sludge has high heavy metal content, so the electroplating sludge is listed as dangerous waste by the name of the nation. But meanwhile, the electroplating sludge is rich in a large amount of metal resources, which is equivalent to low-grade ores, for example, the content of copper and nickel in the electroplating sludge is relatively high, and when the content of copper in the electroplating sludge is more than 5wt%, the electroplating sludge is called copper-containing electroplating sludge and has recovery value; when the nickel content in the electroplating sludge is more than 5wt%, the electroplating sludge is called nickel-containing electroplating sludge and has higher recovery value; when the copper content in the electroplating sludge is more than 5wt% and the nickel content is more than 5wt%, the electroplating sludge is called copper-nickel-containing electroplating sludge, and the copper and the nickel in the electroplating sludge have recovery values.
The first step in the recovery of heavy metals from electroplating sludge is a leaching process using inorganic acids or organic complexing agents such as HNO3The chemical heavy metal leaching method for treating the electroplating sludge by using HCl, EDTA and the like can leach heavy metals in a short time, but has the disadvantages of high acid consumption, high treatment cost, high pollution of acid mist generated in the operation process and poor operation environment of workers.
Bioleaching (Bioleaching), which is a process derived from microbial hydrometallurgy, leaches heavy metals from the electroplating sludge into the liquid phase by using acidophilic microorganisms such as thiobacillus thiooxidans and thiobacillus ferrooxidans to dissolve the metals from the electroplating sludge into the leachate. The basic principle of heavy metal removal is to dissolve heavy metals existing in an insoluble form into a water phase through the biological oxidation of the bacteria and a low pH environment generated by the bacteria, and then remove the heavy metals from sludge through solid-liquid separation. The technology was first applied to the treatment of low-grade, dispersed, refractory deposits with bacteria, known as bioleaching or biological hydrometallurgy. In recent 20 years, the method has been widely applied to extracting metals such as gold, copper and the like in lean ores, waste ores and tailings, but the application of the method in the aspect of recovering heavy metals from electroplating sludge is rarely reported.
Chinese patent document CN 101705358 (application No. 200910238478.7) discloses a method for bioleaching manganese in electrolytic manganese slag, which comprises the steps of drying, grinding and sieving the electrolytic manganese slag in sequence to obtain a waste electrolytic manganese slag material; and then culturing the strain in a container, performing shake culture, adding an electrolytic manganese residue material for bioleaching after about 10 days of culture, allowing heavy metal to enter a liquid phase from a solid phase after leaching for 10 days, and filtering to remove waste residues to obtain bioleaching liquid containing the heavy metal.
Although this method proposes leaching manganese in manganese slag by bioleaching, it does not disclose how to treat electrolytic manganese slag material in bioleaching to recover manganese, and therefore it is essentially only a method of removing manganese from manganese slag.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for recycling heavy metals copper and nickel in electroplating sludge.
The technical scheme for realizing the aim of the invention is a method for recycling heavy metals in electroplating sludge, which comprises the following steps:
pretreating electroplating sludge: dehydrating and air-drying the electroplating sludge to be treated, sieving a mesh screen to remove large particles and large sand grains, collecting the sieved sludge, placing the sludge in an oven to be dried until the sludge is constant in weight, taking out the sludge, grinding the sludge into powder, sieving the powder by a 150-mesh to 220-mesh sieve, and collecting the sieved powder to be treated; the electroplating sludge is copper-containing electroplating sludge with the copper content of more than 5wt%, or nickel-containing electroplating sludge with the nickel content of more than 5 wt%; or the copper-nickel-containing electroplating sludge with both copper content and nickel content larger than 5 percent.
Preparing thiobacillus thallus: and (3) carrying out enrichment culture on the domesticated, separated and purified thiobacillus in a culture solution, wherein the thiobacillus is thiobacillus ferrooxidans or thiobacillus thiooxidans.
And for thiobacillus ferrooxidans, the culture solution is 9K culture solution, when the pH value of the enrichment culture system is detected to be 1.. 0-2.2, the mixed material with the pH value of 1.. 0-2.2 is subjected to centrifugal separation, the precipitate on the lower layer of a centrifugal tube is thiobacillus ferrooxidans thallus, and the thallus is collected.
And for thiobacillus thiooxidans, the culture solution is Waksman culture solution, when the pH value of an enrichment culture solution system is detected to be 2.0-2.5, the mixed material with the pH value of 2.0-2.5 is subjected to centrifugal separation, the precipitate on the lower layer is thiobacillus thiooxidans thallus, and the thallus is collected.
Thirdly, adding the thalli of the thiobacillus centrifugally collected in the second step and the electroplating sludge powder prepared in the first step into a culture solution to obtain a reaction mixed material, wherein the concentration of the electroplating sludge in the reaction mixed material is 20-40 g/L, and the mass of the transferred thalli of the thiobacillus is 5% -15% of that of the culture solution; when the copper in the copper-containing electroplating sludge is recovered, the added thiobacillus thallus is a thiobacillus ferrooxidans thallus, and the culture solution is 9K culture solution; when nickel in the nickel-containing electroplating sludge is recovered, the added thiobacillus thallus is thiobacillus thiooxidans thallus, and the culture solution is Waksman culture solution; when copper and nickel in the copper-nickel containing electroplating sludge are recovered, the added thiobacillus thallus is thiobacillus thiooxidans thallus, and the culture solution is Waksman culture solution.
Reacting the reaction mixture at the temperature of 26-30 ℃ and the rotating speed of a shaking table of 120-200r/min, and testing the pH of the mixture every day; for copper-containing electroplating sludge treated by thiobacillus ferrooxidans, reducing the pH value of the mixed material to 1.5-1.7, stopping the reaction, carrying out centrifugal separation on the reacted mixed material, and extracting and collecting an upper copper-containing leaching solution; and (3) for the nickel-containing electroplating sludge or copper-nickel-containing electroplating sludge treated by thiobacillus thiooxidans, reducing the pH value of the mixed material to 2-3, stopping the reaction, carrying out centrifugal separation on the reacted mixed material, and extracting and collecting the upper nickel-containing leachate or copper-nickel-containing leachate.
Fourthly, impurity removal of the leachate: fe in the leaching solution2+And Ca2+And removing to obtain leachate after impurity removal.
Electrodeposition: transferring the copper-containing leachate after impurity removal in the step (iv) into an electrolytic bath for electrodeposition, and performing electrodeposition on a titanium plate as an anode and a copper plate as a cathode to recover elemental copper so as to complete resource recovery of electroplating sludge; and fourthly, for the nickel-containing leachate after impurity removal in the fourth step, using a titanium plate as an anode and a nickel plate as a cathode for electrodeposition recovery to obtain simple substance nickel, thereby completing resource recovery of electroplating sludge.
Extracting the nickel in the leaching solution by using a nickel extracting agent to respectively obtain a nickel extraction solution and a copper-containing solution, back-extracting the nickel in the nickel extraction solution by using sulfuric acid for the nickel extraction solution, transferring the nickel extraction solution into an electrolytic bath, using a titanium plate as an anode and a nickel plate as a cathode for electrodeposition, and recovering to obtain elemental nickel; and transferring the copper-containing solution into an electrolytic bath, and performing electrodeposition recovery by using a titanium plate as an anode and a copper plate as a cathode to obtain elemental copper so as to finish resource recovery of electroplating sludge.
When the copper in the copper-containing electroplating sludge is recovered, the thallus prepared in the step two is the Thiobacillus ferrooxidans thallus, and the method comprises the following steps:
(a) culturing acidified sludge, taking sludge in an aeration tank of a sewage treatment plant, filtering to remove hair and large particles in the sludge, adjusting the solid content, taking the sludge from the sludge, adding the sludge into a conical flask into which a sterilized 9K culture medium is added, and performing acclimation culture for 7-10 days at the temperature of 28-30 ℃ and the rotating speed of a shaker of 120-200r/min to obtain first-generation acclimated sludge; sucking the first generation of acclimatized sludge, inoculating the first generation of acclimatized sludge into a fresh sterilized 9K culture medium, culturing for 7-10 days according to the conditions to obtain second generation of acclimatized sludge, and repeating the steps until the pH of the acclimatized sludge is reduced to below 2.0 to obtain acidified sludge; in the acclimation process, each generation of acclimation of sludge is added, and FeSO is contained in the culture medium4·7H2The concentration of O was increased by 1g/L compared with the previous generation.
(b) And (b) acclimatizing and culturing sludge resistant to heavy metal, adding the acidified sludge obtained in the step (a) into a 9K culture medium, and adjusting the initial pH value of the material to be 4.0, wherein the composition of the 9K culture medium is the same as that of a culture medium used for an acclimatizing end point of the acidified sludge.
And (2) gradually and gradually adding the copper-containing electroplating sludge powder prepared in the step (i) into the mixed material prepared freshly every time, wherein the concentration of the sludge is gradually increased from 0.5g/L, the change of the pH value of the material is measured every day at regular time, if the pH value is reduced to be below 3.0 within 7 d-10 d, the reaction material is centrifugally separated, and lower-layer sediment is collected, wherein the lower-layer sediment contains iron protoxide thiobacillus thallus which can resist electroplating sludge with corresponding concentration.
After the electroplating sludge with a certain concentration is added, the pH value of the reaction material does not decrease and increases reversely, and within 7-10 days, the pH value rises to be more than 7.0, so that the Thiobacillus ferrooxidans thallus capable of resisting the electroplating sludge with the previous concentration is the Thiobacillus ferrooxidans thallus capable of resisting the electroplating sludge with the highest concentration.
(c) And (c) taking the precipitate of the thiobacillus ferrooxidans thallus containing the electroplating sludge with the highest concentration resistance centrifugally collected in the step (b) to perform enrichment culture in a 9K culture medium for 9-10 days, and then separating, purifying and re-enriching to finish the preparation of the thiobacillus ferrooxidans thallus.
When recovering nickel in the nickel-containing electroplating sludge or copper and nickel in the copper-nickel-containing electroplating sludge, the thallus prepared in the second step is a thiobacillus thiooxidans thallus, and the method comprises the following steps:
(a) culturing acidified sludge, taking sludge in an aeration tank of a sewage treatment plant, filtering to remove hair and large particles in the sludge, adjusting the solid content, taking the sludge from the sludge, adding the sludge into a conical flask into which a sterilized Waksman culture medium is added, and performing acclimation culture for 7-10 days at the temperature of 28-30 ℃ and the rotating speed of a shaking table of 120-200r/min to obtain first-generation acclimated sludge; and (3) sucking the sludge subjected to the first-generation domestication, inoculating the sludge into a fresh sterilized Waksman culture medium, culturing for 7-10 days according to the conditions to obtain sludge subjected to the second-generation domestication, and repeating the steps until the pH value of the domesticated sludge is reduced to be below 2.5 to obtain acidified sludge.
(b) Acclimatizing and culturing sludge resistant to heavy metal, adding the acidified sludge obtained in the step (a) into a Waksman culture medium, and adjusting the initial pH value of the material to be 4.0.
Adding the nickel-containing electroplating sludge powder or the copper-nickel-containing electroplating sludge prepared in the step I into the mixed material which is freshly prepared each time in an increasing mode, gradually increasing the concentration of the sludge from 0.5g/L, measuring the change of the pH value of the material every day at regular time, reducing the pH value to be below 3.0 within 7 d-10 d, carrying out centrifugal separation on the reaction material, and collecting lower-layer sediment which contains thiobacillus thiooxidans bacteria resisting electroplating sludge with corresponding concentration.
After the electroplating sludge with a certain concentration is added, the pH value of the reaction material does not decrease and increases reversely, and within 7-10 days, the pH value rises to be more than 7.0, so that the thiobacillus thiooxidans capable of resisting the electroplating sludge with the previous concentration is the thiobacillus thiooxidans capable of resisting the electroplating sludge with the highest concentration.
(c) And (c) carrying out enrichment culture on the sediment of the sulfur protoxide bacillus thallus containing the electroplating sludge with the highest concentration resistance, which is centrifugally collected in the step (b), in a Waksman culture medium for 9-10 days, and then separating, purifying and enriching to finish the preparation of the sulfur protoxide bacillus thallus.
When the copper in the copper-containing electroplating sludge is recovered, the impurity removal in the step (IV) is to remove impurities such as iron, calcium and the like in the copper-containing leaching solution obtained in the step (III); when removing impurities, the lixivium is heated first, and excess sodium chlorate is added to make Fe2+Complete oxidation to Fe3+(ii) a Adding excessive sodium hydroxide into the leaching solution to lead the Fe3+Combining with hydroxide particles to generate ferric hydroxide precipitate; and (3) filtering the ferric hydroxide precipitate, adding excessive sodium fluoride into the filtrate, generating calcium fluoride precipitate in the filtrate, and filtering again to remove calcium fluoride to obtain the filtrate, namely the copper-containing leachate after impurity removal.
And when recovering nickel in the nickel-containing electroplating sludge, removing calcium impurities in the nickel-containing leaching solution obtained in the step (III), adding excessive sodium fluoride into the leaching solution during impurity removal, introducing steam to heat the leaching solution to 58-65 ℃, precipitating calcium fluoride in the leaching solution, and filtering to remove the calcium fluoride, wherein the obtained filtrate is the nickel-containing leaching solution after impurity removal.
A method for recycling heavy metals in electroplating sludge comprises the following steps:
pretreating electroplating sludge: dehydrating and air-drying the electroplating sludge to be treated, sieving a mesh screen to remove large particles and large sand grains, collecting the sieved sludge, placing the sludge in an oven to be dried until the sludge is constant in weight, taking out the sludge, grinding the sludge into powder, sieving the powder by a 150-mesh to 220-mesh sieve, and collecting the sieved powder to be treated; the electroplating sludge is copper-containing electroplating sludge with the copper content of more than 5wt%, or nickel-containing electroplating sludge with the nickel content of more than 5 wt%; or the copper-nickel-containing electroplating sludge with both copper content and nickel content larger than 5 percent.
Preparing thalli: and (3) enriching and culturing the domesticated, separated and purified thalli in a culture solution, wherein the thalli comprise thiobacillus ferrooxidans, thiobacillus thiooxidans and heterotrophic thalli.
And for thiobacillus ferrooxidans, the culture solution is 9K culture solution, when the pH value of the enrichment culture system is detected to be 1.. 0-2.2, the mixed material with the pH value of 1.. 0-2.2 is subjected to centrifugal separation, the precipitate on the lower layer of a centrifugal tube is thiobacillus ferrooxidans thallus, and the thallus is collected.
And for thiobacillus thiooxidans, the culture solution is Waksman culture solution, when the pH value of an enrichment culture solution system is detected to be 2.0-2.5, the mixed material with the pH value of 2.0-2.5 is subjected to centrifugal separation, the precipitate on the lower layer is thiobacillus thiooxidans thallus, and the thallus is collected.
The bacterium body of the heterotrophic bacteria is obtained by using domestic sewage to perform enrichment culture on the heterotrophic bacteria for 3-5 days at the temperature of 28-30 ℃ and the rotating speed of a shaking table of 120-200r/min, then performing centrifugal separation on a culture solution, and collecting the lower-layer precipitate to obtain the bacterium body.
Uniformly mixing the thiobacillus ferrooxidans, thiobacillus thiooxidans and the heterotrophic bacteria, adding the mixture into a culture solution, and adding the electroplating sludge powder prepared in the step one into the culture solution to obtain a reaction mixed material, wherein the concentration of the electroplating sludge in the reaction mixed material is 20-40 g/L.
Reacting the reaction mixture at the temperature of 26-30 ℃ and the rotating speed of a shaking table of 120-200r/min, and stopping the reaction after 5-6 days of reaction; carrying out centrifugal separation on the reacted mixed materials, and extracting and collecting the upper-layer leachate;
fourthly, impurity removal of the leachate: fe in the leaching solution2+And Ca2+And removing to obtain leachate after impurity removal.
Electrodeposition: transferring the leachate after impurity removal in the step (iv) into an electrolytic bath for electrodeposition, using a titanium plate as an anode and a copper plate as a cathode for electrodeposition recovery to obtain elemental copper for the copper-containing leachate obtained by processing copper-containing electroplating sludge, and using a titanium plate as an anode and a nickel plate as a cathode for electrodeposition recovery of elemental nickel for the nickel-containing leachate obtained by processing nickel-containing electroplating sludge; extracting nickel in the leaching solution by using a nickel extracting agent to respectively obtain a nickel extraction solution and a copper-containing solution, back-extracting the nickel in the nickel extraction solution by using sulfuric acid for the nickel extraction solution, transferring the nickel extraction solution into an electrolytic bath, using a titanium plate as an anode, and using the nickel plate as a cathode for electrodeposition and recycling to obtain elemental nickel; and transferring the copper-containing solution into an electrolytic bath, and performing electrodeposition recovery by using a titanium plate as an anode and a copper plate as a cathode to obtain elemental copper so as to finish resource recovery of electroplating sludge.
The culture solution in the third step is obtained by uniformly mixing an activated sludge supernatant, elemental sulfur and a ferrous sulfate solution, wherein the volume fraction of the activated sludge supernatant is 40-60%, the concentration of the elemental sulfur is 8-12 g/L, and the concentration of the ferrous sulfate is 8-12 wt%; the supernatant of the activated sludge is obtained by taking sludge from an aeration tank of a municipal sewage plant, removing hair and large particles through filtration, and centrifugally separating to obtain the supernatant of the activated sludge.
In the step (c), the thiobacillus ferrooxidans, the thiobacillus thiooxidans and the heterotrophic bacteria are uniformly mixed according to the mass ratio of (1.8-2.2) to 1.
The invention has the positive effects that: for the bioleaching method, in order to enable the thiobacillus used in the method to adapt to the environment containing high-concentration heavy metal, a step of acclimatization is required, once the thiobacillus can not adapt to the environment containing high-concentration heavy metal and die, the whole bioleaching process can not be carried out, so the thiobacillus capable of resisting high-concentration heavy metal is obtained by screening and acclimatization, the thiobacillus and the electroplating sludge are stirred and mixed together for bioleaching, after several days, the leaching rate of heavy metal copper in the electroplating sludge reaches 96%, and the leaching rate of nickel reaches 91%; and then carrying out electrodeposition after impurity removal on the copper-containing leachate, recovering to obtain elemental copper, and carrying out electrodeposition after impurity removal on the nickel-containing leachate to recover to obtain metallic nickel.
Detailed Description
Example 1 Recycling of copper in electroplating sludge
The electroplating sludge treated in this example was obtained from an electroplating plant, and the appearance was gray, wherein the copper content was high, the water content was about 70% as copper-containing electroplating sludge, and the metal components in the electroplating sludge are shown in table 1.
TABLE 1 content of various metals in electroplating sludge mg/g
The method for recycling electroplating sludge comprises the following steps:
pretreating electroplating sludge. Centrifugally dewatering the electroplating sludge to be treated, wherein the water content of the dewatered sludge is 30-40%; naturally drying the sludge after centrifugal dehydration until the water content is equal to or less than 30%, sieving the sludge by a 250-350 mesh (300 mesh in the embodiment) screen, and removing large particles and large sand grains by screening; collecting the sieved sludge, drying the sludge in a drying oven at 105 ℃ until the sludge weight is constant, taking out the dried sludge, grinding the sludge into powder, sieving the powder by a sieve of 150 meshes to 220 meshes (200 meshes in the embodiment), collecting the sieved powder for treatment.
② preparing the Thiobacillus ferrooxidans thallus.
(a) And culturing the acidified sludge. Taking sludge in aeration tank of Changzhou pool sewage treatment plant, and adopting A in the sewage treatment plant2The sewage is treated by an Anaerobic-Anoxic-aerobic (Anaerobic-Anoxic-aerobic) method.
Filtering to remove hair and large particles in the sludge, adjusting the solid content to be 2%, taking 10mL of sludge from the sludge, adding the sludge into a conical flask into which 100mL of sterilized 9K culture medium is added, and performing acclimation culture for 7-10 days at the temperature of 30 ℃ and the rotating speed of a shaking table of 120-200r/min (150 r/min in the embodiment) to obtain first-generation acclimated sludge, wherein the culture medium in the conical flask becomes turbid milky white.
The configuration of the 9K medium used was as follows:
preparing a solution A: 3.0g (NH)4)2SO4 、0.5 g K2HPO4 、0.5 g MgSO4·7H2O 、0.01 g Ca(NO3)2And 0.1 g KCl in 700mL sterile water to obtain solution A.
Preparing a solution B: mixing 44gFeSO4·7H2Dissolving O in 300mL of sterile water to obtain solution B.
Sterilizing solution A and solution B at 121 deg.C for 20min, cooling to 70 deg.C, mixing solution A and solution B, and adjusting pH to 2.00 with 5mol/L sulfuric acid to obtain 9K culture solution.
10mL of the first-generation acclimatized sludge was aspirated from the Erlenmeyer flask, inoculated into 100mL of fresh sterilized 9K medium, and cultured for 7 d to 10d under the above conditions to obtain a second-generation acclimatized sludge. The composition of the 9K medium used here was the same as that of the 9K medium used for culturing the first generation acclimatized sludge, except that FeSO was contained in the medium4·7H2The O concentration increased to 45 g/L.
And (3) sucking the 10mL of second-generation domesticated sludge, inoculating the second-generation domesticated sludge into a fresh 100mL of sterilized 9K culture medium, and culturing for 7 d-10 d according to the conditions to obtain third-generation domesticated sludge. The composition of the 9K medium used here was the same as that of the 9K medium used for culturing the first generation acclimatized sludge, except that FeSO was contained in the medium4·7H2The O concentration increased to 46 g/L.
Repeating the steps to obtain fourth generation acclimatized sludge, and stopping culturing to obtain acidified sludge if the pH value of the sludge is less than or equal to 2. If the pH value of the sludge after the fourth generation acclimation is greater than 2, continuing to acclimate to obtain sludge after the fifth generation acclimation, and if the pH value of the sludge is still greater than 2, still performing acclimation, in this embodiment, acclimating to the fifth generation to obtain acidified sludge.
In the acclimation process, each generation of acclimation of sludge is added, and FeSO is contained in the culture medium4·7H2The concentration of O was increased by 1g/L compared with the previous generation.
(b) And (5) domesticating and culturing sludge with heavy metal resistance. Adding 10mL of the acidified sludge obtained in the step (a) into 100mL of 9K culture medium, adjusting the initial pH value of the materials to 4.0, and respectively adjusting the pH value to dilute H by using acid and alkali2SO4And dilute Na 0H. The composition of the 9K culture medium is the same as that of a culture medium used for the acclimation end point of the acidified sludge, namely the composition of the 9K culture medium is the same as that of a 9K culture medium used for culturing fifth-generation acidified sludge, and FeSO is contained in the 9K culture medium4·7H2The concentration of O was 48 g/L.
Adding the copper-containing electroplating sludge powder prepared in the step I into the mixed material in the proportion in a gradually increasing mode, wherein the concentration of the sludge is increased from 0.5g/L by 0.5g/L in each increase until the pH value of the reaction material is not decreased and is increased reversely after the electroplating sludge with a certain concentration is added, and the pH value can be increased to be more than 7.0 within 7 d-10 d.
The method comprises the steps of adding electroplating sludge into a mixture composed of a culture medium and acidified sludge for the first time to enable the sludge concentration to be 0.5g/L, stopping culturing when the pH value of the mixture is found to be reduced to be below 3 after 1 day, centrifugally separating reaction materials, and collecting lower-layer sediment which contains 0.5g/L electroplating sludge resistant Thiobacillus ferrooxidans thalli.
Adding electroplating sludge into a mixture material consisting of a fresh culture medium and acidified sludge for the second time to enable the sludge concentration to be 1.0g/L, measuring the change of the pH value of the material at regular time every day, reducing the pH value to be below 3.0 within 7 d-10 d, centrifugally separating the reaction material, and collecting lower-layer sediment which contains 1.0g/L electroplating sludge resistant Thiobacillus ferrooxidans thalli.
The above-described method was followed to obtain Thiobacillus ferrooxidans cells which were resistant to 1.5g/L, 2.0g/L, 3.0g/L, 4.0g/L, 5.0g/L, 6.0g/L, 7.0g/L, 8.0g/L, 9.0g/L, 10.0g/L, 11.0g/L, 12.0g/L, 13.0g/L, 14.0g/L, 15.0g/L, 16.0g/L, 17.0g/L, 18.0g/L, 19.0g/L, 20.0g/L, 21.0g/L, 22.0g/L, 23.0g/L, 24.0g/L and 25g/L of the electroplating sludge.
When the electroplating sludge is added into the mixture material consisting of the fresh culture medium and the acidified sludge to ensure that the sludge concentration is 25.5g/L, the pH value of the reaction material does not fall and rises, and the pH value rises to be more than 7.0 within 7 d-10 d. The acclimation is stopped, and the Thiobacillus ferrooxidans bacterial body capable of resisting 25g/L of electroplating sludge is obtained.
In the acclimation process, if the pH value of the reaction system can be reduced to below 3 after 1-3 days after adding the electroplating sludge with a certain concentration, the fact indicates that the thiobacillus ferrooxidans can survive under the electroplating sludge with the concentration, the acclimation can be immediately stopped without continuously culturing for 7 days, and the thalli can be centrifugally separated. If the pH value rises after a certain concentration of electroplating sludge is added, the change of the pH value of the reaction material is measured at regular time every day, and if the pH value can be reduced to be below 3.0 within 7 d-10 d, the ferrous oxide thiobacillus can survive under the concentration of electroplating sludge.
In order to further improve the efficiency, the concentration of the electroplating sludge in the acclimation process can also start to increase by 1g/L, then increase by 2g/L, 4g/L and 8g/L, and finally increase by 0.5 g/L. That is, if the concentration of the plating sludge in the reaction mass is 0.5g/L, the pH can be decreased to 2 or less in 2 days, the concentration of the plating sludge in the second reaction mass is increased to 1.5g/L, and if the pH can be decreased to 2 or less in 2 days, the concentration of the plating sludge in the third reaction mass is increased to 3.5g/L, and if the pH can be decreased to 2 or less in 2 days, the concentration of the plating sludge in the fourth reaction mass is increased to 7.5g/L, and the pH is increased in 1 to 3 days, but is decreased to 3 or less in 4 to 6 days, the concentration of the plating sludge in the fifth reaction mass is increased to 15.5g/L, and the pH is observed, and if the increase in 1 to 4 days and the decrease to 3 or less in 7 to 8 days are required, the concentration of the sludge is gradually increased at a rate of 0.5g/L, and after a certain amount of sludge is observed, the pH value can be reduced to below 3.0 within 7 d-10 d.
(c) And (c) taking 1g of the precipitate of the thiobacillus ferrooxidans strain which is centrifugally collected in the step (b) and contains 25.0g/L electroplating sludge, putting the precipitate into 10mL of 9K culture medium, and carrying out enrichment culture in a shaking table (the rotating speed is 120 r/min) at 28 ℃ for 9-10 days. The composition of the 9K medium was the same as the medium used for the acclimatization endpoint of the acidified sludge.
Then, 1mL of the upper layer liquid of the material after enrichment culture is taken to 9mL without FeSO4·7H2In the O9K culture medium, the rest of the used 9K culture medium is the same as the 9K culture medium for culturing the first generation domesticated sludge in the step II, except that FeSO is not contained in the culture medium4·7H2And O. According to the ratio of the above-mentioned two components, diluting to 10-1Until the solution is diluted to 10-9Thereby completing the dilution separation. After diluting to 10-9In the process, respectively take 10-4～10-9The dilution liquid of the dilution liquid is coated and cultured on a plate (Leathen solid culture medium), 3 times of dilution liquid is repeated, black colonies with the size of a needle point appear on the plate after 9-10 days of culture, and simultaneously white colonies and colonies with other forms appear. Microscopic examination revealed that the black colonies were mainly short bacilli accompanied by filamentous fungi and larger bacilli. And selecting black colonies to prepare a bacterial suspension, diluting and separating according to the method, taking diluents with different dilutions as plates for coating, and culturing for 9-10 days at 28 ℃. Repeating the steps of selecting the black bacterial colony for dilution and culture for 2 times, wherein only the black bacterial colony exists in the reddish brown area of the plate, and the bacterial morphology is observed to be consistent through smear, gram stain and microscopic examination, so that the bacterial strain is the thiobacillus ferrooxidans.
(d) Will step withThe domesticated iron protoxide thiobacillus separated in the step (c) is subjected to enrichment culture in a newly configured 9K culture solution (with the volume set as V), the culture is carried out for 7-10 days under the conditions that the temperature is 28 ℃ and the rotating speed of a shaking table is 120-200r/min, the composition of a used 9K culture medium is the same as that of a 9K culture medium used in the step (II), and FeSO is contained in the 9K culture medium4·7H2The concentration of O was 48 g/L. When the pH value of the enrichment culture system is detected to be 1.0-2.2, the enrichment culture system can be used for treating the electroplating sludge. And taking out the materials after the culture is finished, performing centrifugal separation at 5000rpm (namely 5000 rpm), wherein the sediment at the lower layer of the centrifugal tube is the thiobacillus ferrooxidans thallus, and collecting the thallus.
Thirdly, adding the centrifugally collected thalli of the thiobacillus ferrooxidans and the electroplating sludge powder prepared in the first step into a 9K culture medium to obtain a reaction mixed material, wherein the composition of the 9K culture medium is the same as that of the 9K culture medium used for the acidification sludge domestication end point in the second step. The concentration of the electroplating sludge in the reaction mixture is 20-40 g/L (25 g/L in the embodiment), the mass of the transferred thiobacillus ferrooxidans is 10% of the mass of the 9K culture solution, and the volume of the 9K culture solution in the embodiment is 10 times that of the 9K culture solution in the step (d), namely 10V.
Reacting the reaction mixture at the temperature of 26-30 ℃ and the rotating speed of a shaking table of 140r/min, testing the pH value of the mixture every day, reacting for 8 days, and stopping the reaction when the pH value of the mixture is reduced to 1.6.
And (4) carrying out centrifugal separation on the reacted mixed materials, and collecting the upper-layer leachate.
The leaching rate of copper in the leaching solution is measured to be 90 percent, and the leaching rates of iron and calcium are respectively 30 to 50 percent and 10 to 15 percent. The leaching rate here means a mass percentage of leached metals to the total amount of the metals in the plating sludge.
And fourthly, impurity removal of the leachate. And the impurity removal is to remove impurities such as iron, calcium and the like in the copper-containing leaching solution obtained in the third step.
Heating the leaching solution to 90 ℃, addingAdding an excess of sodium chlorate to obtain Fe2+Complete oxidation to Fe3+(ii) a Adding excessive sodium hydroxide into the leaching solution to lead the Fe3+Combining with hydroxide particles to generate ferric hydroxide precipitate; and (3) filtering the ferric hydroxide precipitate, adding excessive sodium fluoride into the filtrate, generating calcium fluoride precipitate in the filtrate, and filtering again to remove calcium fluoride to obtain the filtrate, namely the copper-containing leachate after impurity removal.
The reaction formula of the iron removal principle is as follows:
6Fe2++NaClO3+6H+→6Fe3++NaCl+3H2O
Fe3++3OH-→Fe(OH)3↓ reaction formula of the above calcium removing principle is as follows:
Ca2++ 2NaF→CaF2↓+2Na+
electrodeposition.
Transferring the copper-containing leachate after impurity removal in the step (IV) into an electrolytic bath for electrodeposition, wherein a titanium plate is used as an anode, and a copper plate is used as a cathode. The control voltage is 2.0V, and the current density is 350A/m2The pH value is 3, the polar distance is 1cm, the time is 3h, and the temperature is 10 ℃.
The recovery rate of electrodeposited copper was 99%. The recovered copper can reach the national GB/T6516-1997 standard.
The electrodeposition solution is continuously circulated in order to keep the electrodeposition conditions substantially stable.
In the embodiment, the titanium plate is used as the anode, so that the current can be efficiently transmitted to the electrolyte and used for anion discharge, and the electrodeposition efficiency is improved. In addition, the sulfuric acid generated in the process of electrodepositing copper can be recycled.
The content of nickel in the leachate of the embodiment is extremely low, and the electrode copper is not affected basically. However, if the leaching solution has a high nickel content, the copper in the leaching solution after impurity removal must be separated from the nickel, and then the copper is recovered by electrodeposition. The separation of nickel adopts an extraction method, the leaching solution is extracted by 2-ethyl hexyl phosphonic acid mono 2-ethyl hexyl ester (P507 for short) to obtain nickel, and the residual solution after extraction only contains a very small amount of nickel, thus no influence is generated on the electro-deposited copper.
Example 2 Recycling of Nickel from electroplating sludge
The electroplating sludge treated in the embodiment is taken from an electroplating plant, the appearance of the electroplating sludge is reddish brown, the nickel content is more than 5 percent compared with the common electroplating sludge, the total content of various metals is 30.37 percent by weight and the water content is about 68 percent by weight as the nickel-containing electroplating sludge, and various metal components in the electroplating sludge are shown in table 2. Wherein,
TABLE 2 content wt% of various metals in nickel-containing electroplating sludge
The method for recycling electroplating sludge comprises the following steps:
pretreating electroplating sludge. Centrifugally dewatering the nickel-containing electroplating sludge to be treated, wherein the water content of the dewatered sludge is 30-40%; naturally drying the sludge after centrifugal dehydration until the water content is equal to or less than 30%, sieving the sludge by a 250-350 mesh (300 mesh in the embodiment) screen, and removing large particles and large sand grains by screening; collecting the sieved sludge, drying the sludge in a drying oven at 105 ℃ until the sludge weight is constant, taking out the dried sludge, grinding the sludge into powder, sieving the powder by a 200-mesh sieve, and collecting the sieved powder for treatment.
② preparation of thiobacillus thiooxidans thallus.
(a) Taking sludge in an aeration tank of a Changzhou pool sewage treatment plant, and treating sewage by the sewage treatment plant by adopting A2/O.
Filtering to remove hair and large particles in the sludge, adjusting the solid content to be 2%, adding 10mL of sludge into a conical flask into which 100mL of sterilized Waksman culture medium is added, and performing acclimation culture for 7-10 d under the conditions that the temperature is 30 ℃ and the rotating speed of a shaking table is 120-200r/min (150 r/min in the embodiment) to obtain first-generation acclimated sludge, wherein the culture medium becomes turbid.
The configuration of the Waksman culture medium is as follows: 0.2g of (NH)4)2SO4、3.0 g K2HPO4、0.5 g MgSO4·7H2O、0.25g CaCl2·2H2Dissolving O in 1000mL of distilled water, sterilizing at high temperature, adding 10g of sulfur, and adding 5mol/L H2SO4The pH was adjusted to 4.00.
Sucking 10mL of the sludge after the first generation of acclimatization, inoculating the sludge into a fresh Waksman culture medium, culturing for 7 d-10 d according to the steps to obtain the sludge after the second generation of acclimatization, and repeating the steps until 4 th generation and 5 th generation of acclimatized sludge are obtained; and if the pH value of the sludge after the domestication of the 4 th generation is reduced to be below 2.5, stopping culturing to obtain acidified sludge, and if the pH value of the sludge after the domestication of the 4 th generation is greater than 2.5, continuing the domestication until the pH value of the sludge is reduced to be below 2.5, wherein the domestication is carried out to the fifth generation to obtain the acidified sludge in the embodiment.
(b) And (5) domesticating and culturing sludge with heavy metal resistance. Adding 10mL of the acidified sludge obtained in the step (a) into 100mL of Waksman culture medium, adjusting the initial pH value of the material to 4.0, and respectively adjusting the pH value to dilute H by using acid and alkali2SO4And dilute Na 0H.
Adding the nickel-containing electroplating sludge powder prepared in the step I into the mixed material in the ratio in an incremental manner, wherein the concentration of the sludge is increased by 0.5g/L from 0.5g/L each time until the pH value of the reaction material does not fall and rises reversely after a certain amount of electroplating sludge is added, and the pH value can rise to be more than 7.0 within 7-10 d.
Adding electroplating sludge into a mixture material consisting of a culture medium and acidified sludge for the first time to enable the sludge concentration to be 0.5g/L, stopping culturing after the pH value of the mixture material is found to be reduced after 1 day, centrifugally separating the reaction material, and collecting lower-layer sediment which contains thiobacillus thiooxidans thallus resisting 0.5g/L of electroplating sludge.
Adding electroplating sludge into a mixture material consisting of a fresh culture medium and acidified sludge for the second time to enable the sludge concentration to be 1.0g/L, measuring the change of the pH value of the material at regular time every day, reducing the pH value to be below 3.0 within 7 d-10 d, centrifugally separating the reaction material, and collecting lower-layer sediment which contains thiobacillus thiooxidans thallus resisting 1.0g/L of the electroplating sludge.
Thiobacillus thiooxidans bacterial cells capable of resisting 1.5g/L and 2.0g/L … 15.0.0 g/L … 20g/L electroplating sludge are obtained in sequence according to the method.
When the electroplating sludge is added into the mixture material consisting of the fresh culture medium and the acidified sludge to ensure that the sludge concentration is 20.5g/L, the pH value of the reaction material does not decrease and increases reversely, and the pH value rises to be more than 7.0 within 7 d-10 d. The acclimation is stopped, and the thiobacillus thiooxidans bacterial body capable of resisting 20g/L electroplating sludge is obtained.
In the acclimatization process, if it is found that the pH value of the reaction system can be lowered after 1 day after adding a certain concentration of the electroplating sludge, it means that thiobacillus thiooxidans can survive under the concentration of the electroplating sludge, and the acclimatization can be immediately stopped without continuing to culture for 7 days, and the cells can be centrifuged. If the pH value rises after a certain concentration of electroplating sludge is added, the change of the pH value of the reaction material is measured at regular time every day, and if the pH value can be reduced to be below 3.0 within 7 d-10 d, the thiobacillus thiooxidans can survive under the concentration of electroplating sludge.
In order to further improve the efficiency, the concentration of the electroplating sludge in the acclimation process can also start to increase at 0.5g/L, then increase at the speed of 1g/L and 2g/L, and finally increase at the speed of 0.5 g/L. That is, if the concentration of the plating sludge in the reaction material is 0.5g/L, the pH value can be decreased to 2 or less in 3 days, the concentration of the plating sludge in the second reaction material is increased to 1.0g/L, if the pH value can be decreased to 2 or less in 3 days, the concentration of the plating sludge in the third reaction material is increased to 2.0g/L, if the pH value can be decreased to 2 or less in 3 days, the concentration of the plating sludge in the fourth reaction material is increased to 4.0g/L, thus the rate of 2g/L increase is maintained, when the pH value is increased to a certain concentration, the pH value is increased in 1 to 3 days, and when the pH value is decreased to 3 or less in 4 to 6 days, the concentration of the plating sludge in the next starting reaction material is increased to 0.5g/L, and whether the pH value can be decreased to 3.0 or less in 7 d to 10d is observed.
(c) And (c) taking 1mL of the upper layer liquid of the material subjected to acclimation culture in the step (b) to be placed in a Waksman culture medium, and carrying out enrichment culture in a shaking table (the rotating speed is 120 r/min) at 28 ℃ for 9-10 days.
Then, 1mL of the liquid in the culture broth after enrichment culture was taken into 9mL of sterile water and diluted to 10 by this ratio-1Until the solution is diluted to 10-9Thereby completing the dilution separation. After diluting to 10-9In the process of (1), take 10-4～10-9Dilutions were plated on solid plates and plated at 28 ℃ for 10-15 days (3 replicates per dilution) at which time pale yellow colonies, accompanied by white colonies, appeared on the plates. The faint yellow colonies were mainly brevibacterium by microscopic examination. Selecting light yellow colony to obtain bacterial suspension, diluting and separating according to the above method, and taking dilution degree of 10-4～10-9The dilutions of (2) were spread on solid plates at 28 ℃ and incubated for 10 days. Repeating the steps of selecting the faint yellow bacterial colony for dilution and culture for 2 times, only the faint yellow bacterial colony exists on the flat plate, and observing consistent thallus forms through smear, gram staining and microscopic examination to obtain the target bacterial strain, namely thiobacillus thiooxidans.
(d) And (c) carrying out enrichment culture on the domesticated thiobacillus thiooxidans separated in the step (c) in a newly configured Waksman culture medium, carrying out aerobic culture on the thiobacillus thiooxidans under the conditions that the temperature is 28-30 ℃ and the rotating speed of a shaking table is 120-200r/min, and when the pH value of a culture solution system is detected to be 2.0-2.5, treating the electroplating sludge. And (3) carrying out centrifugal separation on the mixed material with the pH value of 2.0-2.5 at 5000rpm, wherein the precipitate at the lower layer is thiobacillus thiooxidans thallus, and collecting the thallus.
And thirdly, adding the sulfur oxide bacillus thalli centrifugally collected in the step II and the electroplating sludge powder prepared in the step I into a Waksman culture solution to obtain a reaction mixed material, wherein the concentration of the electroplating sludge in the reaction mixed material is 15-25 g/L (20 g/L in the embodiment), and the mass of the transferred sulfur oxide bacillus thalli is 10% of that of the Waksman culture solution.
And (3) reacting the reaction mixture at the temperature of 28-30 ℃ and the rotating speed of a shaking table of 160r/min, testing the pH value of the mixture every day, reacting for about 2.5 days, and stopping the reaction when the pH value of the mixture is reduced to 2-3.
And (4) carrying out centrifugal separation on the reacted mixed materials, and collecting the upper-layer leachate.
The leaching rate of nickel, zinc and copper in the leaching solution was 91%, 94% and 82%, respectively.
And fourthly, impurity removal of the leachate. And the impurity removal is to remove calcium impurities in the nickel-containing leaching solution obtained in the step III.
Adding excessive sodium fluoride into the leachate, introducing steam to heat the leachate to 60 ℃, precipitating calcium fluoride in the leachate, and filtering to remove the calcium fluoride to obtain filtrate, namely the nickel-containing leachate after impurity removal.
The reaction formula of the calcium removal principle is as follows: ca2++ 2NaF→CaF2↓+2Na+
Electrodeposition. Extracting nickel from the nickel-containing leachate after impurity removal in the step (IV) by using 2-ethyl hexyl phosphonic acid mono 2-ethyl hexyl ester (P507 for short), wherein the extract almost only contains nickel, namely the concentration of other metal ions is lower than 1%; and then carrying out back extraction on the extract liquor by using sulfuric acid, transferring the inorganic extract liquor obtained by back extraction into an electrolytic bath for electrodeposition, wherein a titanium plate is used as an anode, and a nickel plate is used as a cathode. The control voltage is 2.0V, and the current density is 250A/m2The pH value is 3-3.2, the polar distance is 1cm, the time is 3 hours, the temperature is 50-60 ℃, and the current efficiency is 87%.
The recovery rate of electrodeposited nickel was 99%. The recovered nickel can reach the national GB/T6516-1997 standard.
The electrodeposition solution is continuously circulated in order to keep the electrodeposition conditions substantially stable.
The leachate of this example had a high copper content, which affected the electrodeposition of nickel, and therefore it was necessary to separate nickel and copper.
If the copper content in the electroplating sludge treated in the embodiment is more than 5wt%, the copper in the electroplating sludge also has a recovery value, and after the nickel in the leaching solution is extracted, the residual copper-containing solution is subjected to cathodic electrodeposition by using a titanium plate as an anode and a copper plate as a cathode to recover metal copper.
Example 3 Recycling of copper in electroplating sludge
The electroplating sludge treated in this example was the same as that treated in example 1.
The method for recycling the electroplating sludge is the same as the embodiment 1 except that:
in the third step, the thiobacillus ferrooxidans thalli, the thiobacillus thiooxidans thalli and the heterotrophic bacteria thalli are uniformly mixed according to the mass ratio of 2: 1, and then are added into the culture solution, and then the electroplating sludge powder prepared in the first step is added into the culture solution to obtain a reaction mixed material. The concentration of electroplating sludge in the reaction mixture is 20-40 g/L (30 g/L in the embodiment); the concentration of the inoculum of the thiobacillus ferrooxidans is 108The strain concentration of thiobacillus thiooxidans is 10 per mL8The strain/mL, the inoculum concentration of the heterotrophic bacteria is 108one/mL.
The thiobacillus ferrooxidans thallus is obtained according to the method of the step II in the embodiment 1; thiobacillus thiooxidans thalli are obtained according to the method of the step II of the embodiment 2; the bacterium body of the heterotrophic bacteria is obtained by using domestic sewage to perform enrichment culture on the heterotrophic bacteria for 3 days at the temperature of 28 ℃ and the rotating speed of a shaking table of 120r/min, centrifuging a culture solution at the rotating speed of 5000rpm, and collecting lower-layer precipitates.
The culture solution is obtained by uniformly mixing an activated sludge supernatant, elemental sulfur and a ferrous sulfate solution, wherein the volume fraction of the activated sludge supernatant is 40-60%, the concentration of the elemental sulfur is 10g/L, and the concentration of the ferrous sulfate is 10 wt%. Wherein the supernatant of the activated sludge is obtained by the following method: taking activated sludge with stronger activity from an aeration tank of a municipal sewage plant, filtering to remove hair and large-particle substances, and centrifugally separating to obtain supernatant, namely activated sludge supernatant.
And (3) reacting the reaction mixture at the temperature of 28-30 ℃ and the rotating speed of a shaking table of 120-200r/min, testing the pH value of the mixture every day, and stopping the reaction after 5-6 days of reaction.
And (4) carrying out centrifugal separation on the reacted mixed materials, and collecting the upper-layer leachate.
The leaching rate of copper in the leaching solution is measured to be 95 percent, and the leaching rates of iron and calcium are respectively 30 to 50 percent and 10 to 15 percent.
The content of nickel in the electroplating sludge treated by the embodiment is low, so that a titanium plate is used as an anode during electrodeposition, and a copper plate is used as a cathode for electrodeposition to recover copper. If the contents of copper and nickel in the treated electroplating sludge are high, the copper and the nickel in the leaching solution can be separated firstly to obtain a copper-containing solution and a nickel-containing solution; for the copper-containing solution, then, a titanium plate is used as an anode, and a copper plate is used as a cathode for electrodeposition to recover copper; for the solution containing nickel, a titanium plate is used as an anode, and a nickel plate is used as a cathode for electrodeposition to recover copper and nickel.
The separation of copper and nickel in the leachate is to extract nickel in the leachate by using 2-ethyl hexyl phosphonic acid mono 2-ethyl hexyl ester (P507 for short), almost only contain nickel in the extract, and then to obtain nickel-containing solution by back extraction by using sulfuric acid; and extracting nickel from the leaching solution to obtain the residual solution which is the copper-containing solution.
In the embodiment, after the heterotrophic bacteria are added into the reaction system, the electroplating sludge with high organic matter content can be treated, because the thiobacillus ferrooxidans and the thiobacillus thiooxidans are autotrophic bacteria, if more organic matters exist in the environment, the growth of the thiobacillus thiooxidans is not facilitated, and the addition of the heterotrophic bacteria can consume the organic matters in the sludge, so that the normal treatment of the electroplating sludge by the thiobacillus ferrooxidans and the thiobacillus thiooxidans is ensured.
Claims (8)
1. A method for recycling heavy metals in electroplating sludge is characterized by comprising the following steps:
pretreating electroplating sludge: dehydrating and air-drying the electroplating sludge to be treated, sieving a mesh screen to remove large particles and large sand grains, collecting the sieved sludge, placing the sludge in an oven to be dried until the sludge is constant in weight, taking out the sludge, grinding the sludge into powder, sieving the powder by a 150-mesh to 220-mesh sieve, and collecting the sieved powder to be treated; the electroplating sludge is copper-containing electroplating sludge with the copper content of more than 5wt%, or nickel-containing electroplating sludge with the nickel content of more than 5 wt%; or the copper-nickel-containing electroplating sludge with both the copper content and the nickel content larger than 5 percent;
preparing thiobacillus thallus: carrying out enrichment culture on domesticated, separated and purified thiobacillus in a culture solution, wherein the thiobacillus is thiobacillus ferrooxidans or thiobacillus thiooxidans;
for thiobacillus ferrooxidans, the culture solution is 9K culture solution, when the pH value of an enrichment culture system is detected to be 1.. 0-2.2, the mixed material with the pH value of 1.. 0-2.2 is subjected to centrifugal separation, the precipitate on the lower layer of a centrifugal tube is thiobacillus ferrooxidans thallus, and the thallus is collected;
for thiobacillus thiooxidans, the culture solution is Waksman culture solution, when the pH value of an enrichment culture solution system is detected to be 2.0-2.5, the mixed material with the pH value of 2.0-2.5 is subjected to centrifugal separation, the sediment of the lower layer is thiobacillus thiooxidans thallus, and the thallus is collected;
thirdly, adding the thalli of the thiobacillus centrifugally collected in the second step and the electroplating sludge powder prepared in the first step into a culture solution to obtain a reaction mixed material, wherein the concentration of the electroplating sludge in the reaction mixed material is 20-40 g/L, and the mass of the transferred thalli of the thiobacillus is 5% -15% of that of the culture solution; when the copper in the copper-containing electroplating sludge is recovered, the added thiobacillus thallus is a thiobacillus ferrooxidans thallus, and the culture solution is 9K culture solution; when nickel in the nickel-containing electroplating sludge is recovered, the added thiobacillus thallus is thiobacillus thiooxidans thallus, and the culture solution is Waksman culture solution; when copper and nickel in the copper-nickel containing electroplating sludge are recovered, the added thiobacillus thallus is thiobacillus thiooxidans thallus, and the culture solution is Waksman culture solution;
reacting the reaction mixture at the temperature of 26-30 ℃ and the rotating speed of a shaking table of 120-200r/min, and testing the pH of the mixture every day; for copper-containing electroplating sludge treated by thiobacillus ferrooxidans, reducing the pH value of the mixed material to 1.5-1.7, stopping the reaction, carrying out centrifugal separation on the reacted mixed material, and extracting and collecting an upper copper-containing leaching solution; for the nickel-containing electroplating sludge or copper-nickel-containing electroplating sludge treated by thiobacillus thiooxidans, reducing the pH value of the mixed material to 2-3, stopping the reaction, carrying out centrifugal separation on the reacted mixed material, and extracting and collecting the upper nickel-containing leachate or copper-nickel-containing leachate;
fourthly, impurity removal of the leachate: fe in the leaching solution2+And Ca2+Removing to obtain leachate after impurity removal;
electrodeposition: transferring the copper-containing leachate after impurity removal in the step (iv) into an electrolytic bath for electrodeposition, and performing electrodeposition on a titanium plate as an anode and a copper plate as a cathode to recover elemental copper so as to complete resource recovery of electroplating sludge; for the nickel-containing leachate after impurity removal in the step (iv), a titanium plate is used as an anode, and a nickel plate is used as a cathode for electrodeposition recovery to obtain elemental nickel, so that the resource recovery of electroplating sludge is completed;
extracting the nickel in the leaching solution by using a nickel extracting agent to respectively obtain a nickel extraction solution and a copper-containing solution, back-extracting the nickel in the nickel extraction solution by using sulfuric acid for the nickel extraction solution, transferring the nickel extraction solution into an electrolytic bath, using a titanium plate as an anode and a nickel plate as a cathode for electrodeposition, and recovering to obtain elemental nickel; and transferring the copper-containing solution into an electrolytic bath, and performing electrodeposition recovery by using a titanium plate as an anode and a copper plate as a cathode to obtain elemental copper so as to finish resource recovery of electroplating sludge.
2. The method for recycling heavy metals contained in electroplating sludge according to claim 1, wherein the bacteria prepared in the step (II) are Acidithiobacillus ferrooxidans bacteria when copper contained in electroplating sludge is recycled, comprising the following steps:
(a) culturing acidified sludge, taking sludge in an aeration tank of a sewage treatment plant, filtering to remove hair and large particles in the sludge, adjusting the solid content, taking the sludge from the sludge, adding the sludge into a conical flask into which a sterilized 9K culture medium is added, and performing acclimation culture for 7-10 days at the temperature of 28-30 ℃ and the rotating speed of a shaker of 120-200r/min to obtain first-generation acclimated sludge; sucking the first generation of acclimatized sludge, inoculating the first generation of acclimatized sludge into a fresh sterilized 9K culture medium, culturing for 7-10 days according to the conditions to obtain second generation of acclimatized sludge, and repeating the steps until the pH of the acclimatized sludge is reduced to below 2.0 to obtain acidified sludge; in the acclimation process, acclimation of sludge is added every generationFeSO in the culture Medium used4·7H2The concentration of O is increased by 1g/L compared with the previous generation;
(b) domestication culture of sludge heavy metal resistance, namely adding the acidified sludge obtained in the step (a) into a 9K culture medium, and adjusting the initial pH value of the material to be 4.0, wherein the composition of the 9K culture medium is the same as that of a culture medium used for domestication end point of the acidified sludge;
gradually adding the copper-containing electroplating sludge powder prepared in the step I into the mixed material prepared freshly every time, wherein the concentration of the sludge is gradually increased from 0.5g/L, the change of the pH value of the material is measured every day at regular time, if the pH value is reduced to be below 3.0 within 7 d-10 d, the reaction material is centrifugally separated, and lower-layer sediment is collected, and contains iron protobacterium thiobacillus ferrooxidans bacteria resisting electroplating sludge with corresponding concentration;
after the electroplating sludge with a certain concentration is added, the pH value of the reaction material does not decrease and increases reversely, and within 7-10 days, the pH value rises to be more than 7.0, so that the Thiobacillus ferrooxidans thallus capable of resisting the electroplating sludge with the previous concentration is the Thiobacillus ferrooxidans thallus capable of resisting the electroplating sludge with the highest concentration;
(c) and (c) taking the precipitate of the thiobacillus ferrooxidans thallus containing the electroplating sludge with the highest concentration resistance centrifugally collected in the step (b) to perform enrichment culture in a 9K culture medium for 9-10 days, and then separating, purifying and re-enriching to finish the preparation of the thiobacillus ferrooxidans thallus.
3. The method for recycling heavy metals in electroplating sludge according to claim 1, wherein when recovering nickel in nickel-containing electroplating sludge or copper and nickel in copper-nickel-containing electroplating sludge, the thalli prepared in step (ii) is thiobacillus thiooxidans thalli, comprising the following steps:
(a) culturing acidified sludge, taking sludge in an aeration tank of a sewage treatment plant, filtering to remove hair and large particles in the sludge, adjusting the solid content, taking the sludge from the sludge, adding the sludge into a conical flask into which a sterilized Waksman culture medium is added, and performing acclimation culture for 7-10 days at the temperature of 28-30 ℃ and the rotating speed of a shaking table of 120-200r/min to obtain first-generation acclimated sludge; sucking the first generation of acclimatized sludge, inoculating the first generation of acclimatized sludge into a fresh sterilized Waksman culture medium, culturing for 7-10 days according to the conditions to obtain second generation of acclimatized sludge, and repeating the steps until the pH value of the acclimatized sludge is reduced to below 2.5 to obtain acidified sludge;
(b) acclimatizing and culturing sludge resistant to heavy metal, namely adding the acidified sludge obtained in the step (a) into a Waksman culture medium, and adjusting the initial pH value of the material to be 4.0;
adding the nickel-containing electroplating sludge powder or the copper-nickel-containing electroplating sludge powder prepared in the step I into the mixed material which is freshly prepared each time in an increasing mode, gradually increasing the concentration of the sludge from 0.5g/L, measuring the change of the pH value of the material every day at regular time, reducing the pH value to be below 3.0 within 7 d-10 d, carrying out centrifugal separation on the reaction material, and collecting lower-layer sediment which contains thiobacillus thiooxidans bacteria resisting electroplating sludge with corresponding concentration;
after the electroplating sludge with a certain concentration is added, the pH value of the reaction material does not decrease and increases reversely, and within 7-10 days, the pH value rises to be more than 7.0, so that the thiobacillus thiooxidans capable of resisting the electroplating sludge with the previous concentration is the thiobacillus thiooxidans capable of resisting the electroplating sludge with the highest concentration;
(c) and (c) carrying out enrichment culture on the sediment of the sulfur protoxide bacillus thallus containing the electroplating sludge with the highest concentration resistance, which is centrifugally collected in the step (b), in a Waksman culture medium for 9-10 days, and then separating, purifying and enriching to finish the preparation of the sulfur protoxide bacillus thallus.
4. The method for resource recovery of heavy metals in electroplating sludge according to claim 1, characterized in that: when the copper in the copper-containing electroplating sludge is recovered, the impurity removal in the step (IV) is to remove impurities such as iron, calcium and the like in the copper-containing leaching solution obtained in the step (III); when removing impurities, the lixivium is heated first, and excess sodium chlorate is added to make Fe2+Complete oxidation to Fe3+(ii) a Adding excessive sodium hydroxide into the leaching solution to lead the Fe3+Combining with hydroxide particles to generate ferric hydroxide precipitate; filtering ferric hydroxide precipitate, adding excessive sodium fluoride into the filtrate to generate calcium fluoride precipitate in the filtrate, and recovering calcium fluorideAnd filtering to remove calcium fluoride to obtain filtrate, namely the copper-containing leaching solution after impurity removal.
5. The method for resource recovery of heavy metals in electroplating sludge according to claim 1, characterized in that: and when recovering nickel in the nickel-containing electroplating sludge, removing calcium impurities in the nickel-containing leaching solution obtained in the step (III), adding excessive sodium fluoride into the leaching solution during impurity removal, introducing steam to heat the leaching solution to 58-65 ℃, precipitating calcium fluoride in the leaching solution, and filtering to remove the calcium fluoride, wherein the obtained filtrate is the nickel-containing leaching solution after impurity removal.
6. A method for recycling heavy metals in electroplating sludge is characterized by comprising the following steps:
pretreating electroplating sludge: dehydrating and air-drying the electroplating sludge to be treated, sieving a mesh screen to remove large particles and large sand grains, collecting the sieved sludge, placing the sludge in an oven to be dried until the sludge is constant in weight, taking out the sludge, grinding the sludge into powder, sieving the powder by a 150-mesh to 220-mesh sieve, and collecting the sieved powder to be treated; the electroplating sludge is copper-containing electroplating sludge with the copper content of more than 5wt%, or nickel-containing electroplating sludge with the nickel content of more than 5 wt%; or the copper-nickel-containing electroplating sludge with both the copper content and the nickel content larger than 5 percent; preparing thalli: enriching and culturing domesticated, separated and purified thalli in a culture solution, wherein the thalli comprise thiobacillus ferrooxidans, thiobacillus thiooxidans and heterotrophic thalli;
for thiobacillus ferrooxidans, the culture solution is 9K culture solution, when the pH value of an enrichment culture system is detected to be 1.. 0-2.2, the mixed material with the pH value of 1.. 0-2.2 is subjected to centrifugal separation, the precipitate on the lower layer of a centrifugal tube is thiobacillus ferrooxidans thallus, and the thallus is collected;
for thiobacillus thiooxidans, the culture solution is Waksman culture solution, when the pH value of an enrichment culture solution system is detected to be 2.0-2.5, the mixed material with the pH value of 2.0-2.5 is subjected to centrifugal separation, the sediment of the lower layer is thiobacillus thiooxidans thallus, and the thallus is collected;
the method comprises the following steps of carrying out enrichment culture on the bacteria of the heterotrophic bacteria for 3-5 days by using domestic sewage at the temperature of 28-30 ℃ and the rotating speed of a shaking table of 120-200r/min, carrying out centrifugal separation on a culture solution, and collecting lower-layer precipitates to obtain bacteria;
uniformly mixing the thiobacillus ferrooxidans, thiobacillus thiooxidans and the heterotrophic bacteria, adding the mixture into a culture solution, and adding the electroplating sludge powder prepared in the step one into the culture solution to obtain a reaction mixed material, wherein the concentration of the electroplating sludge in the reaction mixed material is 20-40 g/L;
reacting the reaction mixture at the temperature of 26-30 ℃ and the rotating speed of a shaking table of 120-200r/min, and stopping the reaction after 5-6 days of reaction; carrying out centrifugal separation on the reacted mixed materials, and extracting and collecting the upper-layer leachate;
fourthly, impurity removal of the leachate: fe in the leaching solution2+And Ca2+Removing to obtain leachate after impurity removal;
electrodeposition: transferring the leachate after impurity removal in the step (iv) into an electrolytic bath for electrodeposition, using a titanium plate as an anode and a copper plate as a cathode for electrodeposition recovery to obtain elemental copper for the copper-containing leachate obtained by processing copper-containing electroplating sludge, and using a titanium plate as an anode and a nickel plate as a cathode for electrodeposition recovery of elemental nickel for the nickel-containing leachate obtained by processing nickel-containing electroplating sludge; extracting nickel in the leaching solution by using a nickel extracting agent to respectively obtain a nickel extraction solution and a copper-containing solution, back-extracting the nickel in the nickel extraction solution by using sulfuric acid for the nickel extraction solution, transferring the nickel extraction solution into an electrolytic bath, using a titanium plate as an anode, and using the nickel plate as a cathode for electrodeposition and recycling to obtain elemental nickel; and transferring the copper-containing solution into an electrolytic bath, and performing electrodeposition recovery by using a titanium plate as an anode and a copper plate as a cathode to obtain elemental copper so as to finish resource recovery of electroplating sludge.
7. The method for recycling heavy metals in electroplating sludge according to claim 6, wherein the culture solution in the third step is obtained by uniformly mixing an activated sludge supernatant, elemental sulfur and a ferrous sulfate solution, wherein the volume fraction of the activated sludge supernatant is 40% -60%, the concentration of the elemental sulfur is 8-12 g/L, and the concentration of the ferrous sulfate is 8-12 wt%; the supernatant of the activated sludge is obtained by taking sludge from an aeration tank of a municipal sewage plant, removing hair and large particles through filtration, and centrifugally separating to obtain the supernatant of the activated sludge.
8. The method for recycling heavy metals in electroplating sludge according to claim 6, wherein Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Acidobacterium are uniformly mixed according to the mass ratio of (1.8-2.2) to 1.
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| CB03 | Change of inventor or designer information |
Inventor after: Cheng Jiehong Inventor after: Kong Feng Inventor after: Chen Xian Inventor before: Cheng Jiehong Inventor before: Zhou Quanfa Inventor before: Kong Feng Inventor before: Chen Xian |
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Free format text: CORRECT: APPLICANT; FROM: JIANGSU TECHNOLOGY NORMAL COLLEGE TO: JIANGSU UNIVERSITY OF TECHNOLOGY Free format text: CORRECT: INVENTOR; FROM: CHENG JIEHONG ZHOU QUANFA KONG FENG CHEN XIAN TO: CHENG JIEHONG KONG FENG CHEN XIAN |
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