CN114277249A - Treatment method for recycling tin, copper and waste gas from PCB tin waste liquid in recycling mode - Google Patents
Treatment method for recycling tin, copper and waste gas from PCB tin waste liquid in recycling mode Download PDFInfo
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- CN114277249A CN114277249A CN202111422303.9A CN202111422303A CN114277249A CN 114277249 A CN114277249 A CN 114277249A CN 202111422303 A CN202111422303 A CN 202111422303A CN 114277249 A CN114277249 A CN 114277249A
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- 239000011135 tin Substances 0.000 title claims abstract description 127
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 title claims abstract description 125
- 239000007788 liquid Substances 0.000 title claims abstract description 84
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 64
- 239000010949 copper Substances 0.000 title claims abstract description 64
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 63
- 239000002699 waste material Substances 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 42
- 239000002912 waste gas Substances 0.000 title claims abstract description 28
- 238000004064 recycling Methods 0.000 title claims abstract description 25
- 229910052718 tin Inorganic materials 0.000 claims abstract description 122
- 239000002244 precipitate Substances 0.000 claims abstract description 47
- 239000006228 supernatant Substances 0.000 claims abstract description 37
- 239000007789 gas Substances 0.000 claims abstract description 31
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 28
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 26
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 25
- FAKFSJNVVCGEEI-UHFFFAOYSA-J tin(4+);disulfate Chemical compound [Sn+4].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O FAKFSJNVVCGEEI-UHFFFAOYSA-J 0.000 claims abstract description 25
- 230000008929 regeneration Effects 0.000 claims abstract description 24
- 238000011069 regeneration method Methods 0.000 claims abstract description 24
- 238000000926 separation method Methods 0.000 claims abstract description 23
- 238000005507 spraying Methods 0.000 claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 claims abstract description 16
- 239000000706 filtrate Substances 0.000 claims abstract description 12
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 10
- 230000001172 regenerating effect Effects 0.000 claims abstract description 10
- 235000006408 oxalic acid Nutrition 0.000 claims abstract description 9
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910001431 copper ion Inorganic materials 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 8
- 229910001432 tin ion Inorganic materials 0.000 claims abstract description 8
- 238000007599 discharging Methods 0.000 claims abstract description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 32
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 29
- 229910017604 nitric acid Inorganic materials 0.000 claims description 29
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 239000002184 metal Substances 0.000 claims description 15
- 229910052751 metal Inorganic materials 0.000 claims description 15
- 229920002401 polyacrylamide Polymers 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 13
- WFPZPJSADLPSON-UHFFFAOYSA-N dinitrogen tetraoxide Chemical compound [O-][N+](=O)[N+]([O-])=O WFPZPJSADLPSON-UHFFFAOYSA-N 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 11
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims description 9
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 9
- QRUDEWIWKLJBPS-UHFFFAOYSA-N benzotriazole Chemical compound C1=CC=C2N[N][N]C2=C1 QRUDEWIWKLJBPS-UHFFFAOYSA-N 0.000 claims description 8
- 239000012964 benzotriazole Substances 0.000 claims description 8
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 7
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 7
- 239000004202 carbamide Substances 0.000 claims description 7
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 7
- 238000003825 pressing Methods 0.000 claims description 7
- 230000005484 gravity Effects 0.000 claims description 6
- 239000003223 protective agent Substances 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 3
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 abstract description 18
- 239000002351 wastewater Substances 0.000 abstract description 8
- 229910021645 metal ion Inorganic materials 0.000 abstract description 6
- 239000003814 drug Substances 0.000 abstract description 5
- 230000001376 precipitating effect Effects 0.000 abstract description 4
- 239000000243 solution Substances 0.000 description 48
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 13
- 239000000047 product Substances 0.000 description 9
- 238000003723 Smelting Methods 0.000 description 8
- -1 nitrate ions Chemical class 0.000 description 8
- 229910052742 iron Inorganic materials 0.000 description 6
- 239000010410 layer Substances 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- QYCVHILLJSYYBD-UHFFFAOYSA-L copper;oxalate Chemical compound [Cu+2].[O-]C(=O)C([O-])=O QYCVHILLJSYYBD-UHFFFAOYSA-L 0.000 description 4
- 239000010802 sludge Substances 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910002651 NO3 Inorganic materials 0.000 description 3
- 239000002920 hazardous waste Substances 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 229910000365 copper sulfate Inorganic materials 0.000 description 2
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical class [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 2
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000009713 electroplating Methods 0.000 description 2
- VEPSWGHMGZQCIN-UHFFFAOYSA-H ferric oxalate Chemical compound [Fe+3].[Fe+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O VEPSWGHMGZQCIN-UHFFFAOYSA-H 0.000 description 2
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 2
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- RCCULWIHKBFZKF-UHFFFAOYSA-N [Cu].[Cl-].[NH4+].N Chemical compound [Cu].[Cl-].[NH4+].N RCCULWIHKBFZKF-UHFFFAOYSA-N 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- YPJKMVATUPSWOH-UHFFFAOYSA-N nitrooxidanyl Chemical compound [O][N+]([O-])=O YPJKMVATUPSWOH-UHFFFAOYSA-N 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 239000002516 radical scavenger Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- CVNKFOIOZXAFBO-UHFFFAOYSA-J tin(4+);tetrahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[Sn+4] CVNKFOIOZXAFBO-UHFFFAOYSA-J 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Abstract
The invention provides a method for treating PCB tin waste liquid by recycling and regenerating recovered tin, copper and waste gas, which comprises the following steps: adding sulfuric acid and a filter aid into the PCB tin waste liquid to precipitate tin ions, and separating tin sulfate precipitate from supernatant; then adding the supernatant as a circulating separating agent into new PCB tin waste liquid for tin sulfate precipitation separation, and entering the next step until the copper content of the supernatant meets the requirement; adding oxalic acid and a filter aid into the supernatant with the copper content reaching the standard, and precipitating copper ions; then mixing the filtrate with a regeneration solution to obtain a tin stripping regeneration sub-solution, and returning the tin stripping regeneration sub-solution to the production line for use; finally, spraying the generated tail gas with hydrogen peroxide, and discharging after the tail gas meets the standard. The method can selectively precipitate and separate the metal ions of tin and copper in the waste liquid, improve the tin content in the tin mud and the copper content in the copper mud, realize the regeneration and recycling of the tin stripping liquid medicine, avoid the generation of waste water and dangerous waste gas in the whole production process, protect the environment and greatly reduce the production cost.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to a method for recycling tin, copper and waste gas from PCB tin waste liquid in a recycling and regenerating manner.
[ background of the invention ]
The etching of the outer layer circuit of the PCB enterprise adopts electroplating pure tin (a pattern electroplating process) as a protective layer of the circuit, after the circuit is etched by a copper-ammonia-ammonium chloride alkaline buffer system, the tin protective layer on the surface of the circuit needs to be stripped (a tin stripping process) and then enters the next process, and at present, each PCB enterprise basically adopts nitric acid-ferric chloride type tin stripping liquid. The tin stripping waste liquid contains 60-80g/L of tin, 10-20g/L of iron, 5-6.5mol/L of nitrate radical, a small amount of organic additives such as benzotriazole for copper protection and the like.
The traditional nitric acid and ferric nitrate type tin-stripping solution utilizes the strong oxidizing property of nitric acid and the oxidizing property of Fe3+, the solution firstly corrodes tin on the surface, then attacks a copper-tin alloy layer and simultaneously attacks a trace copper layer to form a copper layer with a bright surface, so that a PCB (printed circuit board) is qualified and enters the next procedure. Due to the spraying principle, Fe3+Fe is generated after reaction with tin and copper2+In order to be oxidized into Fe by oxygen in the air (in some way, by nitric acid in solution)3+And circularly attacking the tin layer and the copper-tin alloy layer.
At present, tin-stripping waste liquid generated by PCB enterprises is generally neutralized by adding alkali (flake alkali or lime), valuable tin (generated tin mud, namely tin hydroxide) is recovered after filter pressing, and generated waste gas is discharged after reaching the standard through total nitrogen treatment. The disadvantages of the tin stripping waste liquor mode are as follows:
1. the tin sludge contains a large amount of impurities (containing a large amount of copper, iron and the like); 2. the tin content in the tin mud is not high, and the additional value is low; 3. raw materials in the liquid medicine are wasted, and resources cannot be recycled; 4. secondary pollution (total nitrogen is difficult to treat to reach the emission standard); 5. the oxynitride in the waste gas can not be recycled and is difficult to treat cleanly; 6. the hazardous waste transfer procedure is very complicated, and the enterprises with hazardous waste code qualification are few, and each transfer cost is high; 7. the hazardous waste loading, unloading and transporting process has great potential safety hazard in environmental protection.
[ summary of the invention ]
The technical problem to be solved by the invention is to provide a treatment method for recycling tin, copper and waste gas from PCB tin waste liquid in a recycling and regenerating manner, which can selectively precipitate and separate metal ions of tin and copper in the waste liquid, improve the tin content in tin mud and the copper content in copper mud, and realize recycling of tin stripping liquid medicine.
The invention is realized by the following steps:
a PCB tin waste liquid recycling and regenerating type tin, copper and waste gas recovery processing method comprises the following steps:
step 1, firstly, adding sulfuric acid or sulfate into PCB tin waste liquid to precipitate tin ions into tin sulfate, then adding a proper amount of diatomite and polyacrylamide, further increasing precipitate particles, finally separating tin sulfate precipitate from supernatant, and recovering the tin sulfate precipitate;
step 2, adding sulfuric acid or sulfate into the new PCB tin waste liquid to precipitate tin ions into tin sulfate, adding a proper amount of diatomite, then adding the supernatant obtained in the step 1 after the first solid-liquid separation as a circulating separating agent, finally adding polyacrylamide, further increasing precipitate particles, then separating tin sulfate precipitate from the supernatant, and recovering the tin sulfate precipitate; continuously adding new PCB tin waste liquid into the obtained supernatant, circularly repeating the step 2 until the weight percentage content of copper in the supernatant reaches 3-6% or the weight percentage of nitric acid reaches 30% -50%, and entering the step 3;
3, adding oxalic acid into the supernatant obtained in the step 2 to precipitate copper ions, adding a proper amount of diatomite and polyacrylamide filter aid, further increasing precipitate particles, separating copper metal precipitate from the supernatant, and performing filter pressing on the precipitate to obtain copper mud for recycling;
and 4, blending the filtrate obtained in the step 3 with a regeneration solution, and adjusting the main components to ensure that the volume content of the nitric acid in the solution is as follows: 10-30%, and the content of ferric iron: 19-55 g/L, copper protecting agent benzotriazole: 2.4-8.5 g/l, urea: 2.4-9.0 g/L to obtain a tin stripping regeneration sub-solution, and then returning the tin stripping regeneration sub-solution to a tin stripping production line to be used as a tin stripping solution;
step 5, collecting tail gas containing nitric oxide and dinitrogen tetroxide generated in the reaction process, spraying the tail gas by hydrogen peroxide, discharging after the tail gas meets the standard through detection, and recovering dilute nitric acid generated after spraying; the dilute nitric acid can be used for preparing the tin stripping regeneration sub-solution in the step 4, and zero emission of nitrogen oxides in waste gas is realized.
Further, the main raw material components for preparing the tin stripping regeneration sub-solution in the step 4 are as follows: nitric acid, ferric nitrate, benzotriazole, urea and ferric trichloride.
Further, the specific gravity of the filtrate of the stripping regeneration sub-solution obtained in the step 4 is 1.05-1.18.
Further, the tail gas in the step 5 is firstly sprayed by the third-level hydrogen peroxide, then sprayed by the first-level dilute sodium hydroxide solution, and finally discharged after meeting the standard.
The invention has the following advantages:
the tin-stripping waste liquid recycling process comprises two times of precipitation and solid-liquid separation, wherein sulfuric acid and a small amount of substances such as selective metal capture agents oxalic acid and precipitation aids (diatomite and polyacrylamide) are added into the tin-stripping waste liquid twice in sequence, so that metal ions tin and copper in the waste liquid are subjected to selective precipitation separation, the tin content in the separated tin mud and the copper content in the copper mud are greatly improved, and the recovery value of the tin mud and the copper mud in the tin-stripping waste liquid is increased. Waste gas generated in the recovery process of the tin stripping waste liquid is sprayed and absorbed by the three-level hydrogen peroxide, so that zero emission of nitrogen oxides in the waste gas can be realized.
In addition, the tin stripping liquid medicine can be recycled, no waste water and no dangerous waste gas are generated in the whole production process, and tin, copper and dilute nitric acid are recovered, so that great economic and social benefits are created, and the process becomes a clean production process in real sense.
[ detailed description ] embodiments
The invention relates to a treatment method for recycling tin, copper and waste gas from PCB tin waste liquid in a recycling and regenerating manner, which comprises the following steps:
step 1, firstly, adding sulfuric acid or sulfate into PCB tin waste liquid to precipitate tin ions into tin sulfate, then adding a proper amount of diatomite and polyacrylamide, further increasing precipitate particles, finally separating tin sulfate precipitate from supernatant, and recovering the tin sulfate precipitate;
step 2, adding sulfuric acid or sulfate into the new PCB tin waste liquid to precipitate tin ions into tin sulfate, adding a proper amount of diatomite, then adding the supernatant obtained in the step 1 after the first solid-liquid separation as a circulating separating agent, finally adding polyacrylamide, further increasing precipitate particles, then separating tin sulfate precipitate from the supernatant, and recovering the tin sulfate precipitate; continuously adding new PCB tin waste liquid into the obtained supernatant, circularly repeating the step 2 until the weight percentage content of copper in the supernatant reaches 3-6% or the weight percentage of nitric acid reaches 30% -50%, and entering the step 3;
3, adding oxalic acid into the supernatant obtained in the step 2 to precipitate copper ions, adding a proper amount of diatomite and polyacrylamide filter aid, further increasing precipitate particles, separating copper metal precipitate from the supernatant, and performing filter pressing on the precipitate to obtain copper mud for recycling;
and 4, blending the filtrate obtained in the step 3 with a regenerated solution, and adjusting the main components to ensure that the specific gravity of the filtrate in the solution is 1.05-1.18, and the volume content percentage of nitric acid is as follows: 10-30%, and the content of ferric iron: 19-55 g/L, copper protecting agent benzotriazole: 2.4-8.5 g/l, urea: 2.4-9.0 g/L to obtain a tin stripping regeneration sub-solution, and then returning the tin stripping regeneration sub-solution to a tin stripping production line to be used as a tin stripping solution;
step 5, collecting tail gas containing nitric oxide and dinitrogen tetroxide generated in the reaction process, spraying the tail gas by hydrogen peroxide, discharging after the tail gas meets the standard through detection, and recovering dilute nitric acid generated after spraying; the dilute nitric acid can be used for preparing the tin stripping regeneration sub-solution in the step 4, and zero emission of nitrogen oxides in waste gas is realized.
The main raw material components for preparing the tin stripping regeneration sub-solution in the step 4 are as follows: nitric acid, ferric nitrate, benzotriazole, urea and ferric trichloride.
And 5, spraying the tail gas in the step 5 through three stages of hydrogen peroxide, spraying the tail gas through a first-stage dilute sodium hydroxide solution, and finally discharging the tail gas after the tail gas meets the standard.
The following detailed description will clearly and completely describe the technical solution of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Examples
The method comprises the following specific process steps:
step 1, primary precipitation and solid-liquid separation process: firstly, adding concentrated sulfuric acid into the PCB tin waste liquid to precipitate tin ions into tin sulfate, wherein the color of the precipitate is white, then adding a proper amount of diatomite and polyacrylamide, further increasing the particles of the precipitate, and effectively separating the required tin metal precipitate from the supernatant through a solid-liquid separation device; the white precipitate is converted into tin mud (the dry base content of tin in the tin mud is 40-65%) through filter pressing, and then the tin mud is directly sold to a smelting plant for smelting to obtain simple substance tin;
step 2, directly adding the supernatant of the first solid-liquid separation (the supernatant is used as a circulating separating agent) into the new PCB tin waste liquid in which concentrated sulfuric acid and a proper amount of diatomite are added in the second tank, then adding polyacrylamide, further increasing precipitate particles, and effectively separating the required tin metal precipitate from the supernatant through a solid-liquid separation device; then carrying out filter pressing to recover the metallic tin;
and then, the steps are adopted to carry out sequential circulation production (normally, the circulation can be carried out for 3-5 times), so that the recovery of high-content tin mud and tin metal can be realized under the condition of not increasing the volume of the solution. After the copper content in the solution reaches 3-6% (mass ratio) or the nitric acid concentration is 30-50% (concentration ratio when nitric acid is 100%), carrying out secondary precipitation, and carrying out solid-liquid separation again to obtain copper ions and nitrate ions with higher concentration, wherein the solution can be recycled;
step 3, secondary precipitation and solid-liquid separation process: adding a proper amount of oxalic acid (equivalent to copper ions) into the supernatant obtained in the step 2, precipitating the copper ions by utilizing the principle that the copper oxalate and ferric oxalate have different solubility products (KSP), not precipitating the iron ions, adding a proper amount of filter aids such as diatomite and polyacrylamide, further increasing precipitate particles, effectively separating the required copper metal precipitate from the supernatant by a solid-liquid separation device, and filter-pressing the precipitate to obtain copper sludge (the content of copper dry basis in the copper sludge is 40-50 percent), and directly selling the copper sludge to a smelting plant for smelting;
step 4, mixing the regeneration liquid: and (3) putting the filtrate obtained in the step (3) into a regenerated liquid storage and blending system for blending regenerated liquid, and adjusting main components to ensure that the specific gravity of the filtrate in the obtained solution is 1.05-1.18, and the volume content percentage of nitric acid is as follows: 10-30%, and the content of ferric iron: 19-55 g/L, copper protecting agent benzotriazole: 2.4-8.5 g/l, urea: 2.4-9.0 g/L, and after each index reaches the solution concentration required by tin stripping production, the solution can be called as tin stripping regeneration sub-solution, and then the tin stripping regeneration sub-solution is automatically added and returned to a tin stripping production line for use through specific gravity control, so that the cyclic utilization of resources and the zero emission of waste liquid are realized.
And 5, tail gas treatment: the tail gas generated in the reaction process is collected in the whole process, the spray tower circularly recovers the dilute nitric acid by adopting a mode of spraying reverse tail gas (mainly nitric oxide and dinitrogen tetroxide) with three-level hydrogen peroxide, the product can be used for preparing regenerated tin stripping solution, and is sprayed with first-level dilute sodium hydroxide solution, finally discharged after meeting the standard, and the zero emission of nitrogen oxide in waste gas can be realized.
Second, the process principle
1. Primary precipitation and solid-liquid separation process
The primary precipitation process is mainly to add concentrated sulfuric acid or sulfate as selective metal trapping agent into tin-stripping waste liquid to make the metal ions in the waste liquid react with the selective metal trapping agent to generate precipitate.
By utilizing the principle that the solubility of tin sulfate, copper sulfate and ferric sulfate is greatly different, only tin sulfate can be precipitated under the condition, and copper sulfate and ferric sulfate are remained in the solution, thereby achieving the purpose of separating tin, copper and iron.
The tin in the tin stripping water is captured, sulfuric acid which is equivalent to the tin in the solution is added through analysis and calculation, and the product tin sulfate precipitate is generated, wherein the reaction formula is as follows:
Sn 2++SO4 2-＝Sn SO4↓
Sn 4++2SO4 2-＝Sn(SO4)2↓
after adding proper amount of filter aid such as diatomite and polyacrylamide, the particles of the precipitate are further enlarged.
The tin-stripping waste liquid after the primary precipitation process needs to be separated from the supernatant by a separation device such as a filter press, the white precipitate (mainly tin sulfate) can be directly sold to a smelting plant for smelting to obtain simple substance tin metal, and the filtrate enters the next precipitation and solid-liquid separation system.
To be specifically noted are: the filtrate is an acidic solution containing copper and a filter aid, and the solution is collected and used as an additive solution for next precipitation and separation by adding sulfuric acid.
2. Secondary precipitation and solid-liquid separation process
The copper in the tin stripping solution is captured, and oxalic acid which is slightly excessive than the equivalent of the copper in the solution is added through analysis and calculation to generate a product copper oxalate precipitate, wherein the reaction formula is as follows:
CU 2++C2O4 2-＝CUC2O4↓
as can be seen from the above ionic reaction formula, the added selective metal scavenger oxalic acid is a copper precipitating agent, and the solubility product of copper oxalate is much smaller than that of iron oxalate, so that oxalate only precipitates with copper ions, and ferric iron is not precipitated all the time in the process.
Because the solution has a small amount of filter aid, the supernatant liquid of the first solid-liquid separation (containing a certain amount of copper and the filter aid) is added, so that the purposes of not increasing the volume of the solution and separating copper and iron can be achieved. The purpose of the cyclic repeated process is to improve the copper content and the nitric acid content in the solution and reduce the generation amount of wastewater, even prevent the increase of the volume of the solution in the whole regeneration cycle and really realize the zero discharge of the wastewater in the whole process of recovering metals and regenerating the sub-solution.
The tin-stripping waste liquid after the secondary precipitation process needs to be separated from the copper metal precipitate and the supernatant through a separating device such as a filter press, the yellow precipitate (mainly copper oxalate) can be directly sold to a smelting plant for smelting to obtain elemental copper, and the filtrate enters a regenerated liquid storage and blending system.
The method can realize the selective separation of tin, copper and iron in the waste liquid, and the supernatant after complete precipitation mainly contains hydrogen radicals, ferric iron and nitrate ions, so that the effective tin stripping component and concentration in tin stripping are basically not changed, and the tin stripping effect can be recovered by only slightly supplementing the main component of a small amount of tin stripping subplant.
3. Tin stripping liquid storage and component adjustment process
The tin stripping liquid storage and component regulation system regulates the components of the precipitated tin stripping waste liquid with low metal ion content, so that each index of the tin stripping waste liquid meets the requirement required by production, the tin stripping waste liquid can become regenerated sub-liquid at the moment, the regenerated sub-liquid is automatically regulated in price through specific gravity control and is returned to a tin stripping production line for use, and therefore resource recycling and zero discharge of the waste liquid are achieved.
4. Tail gas treatment process
Acid (mainly nitrogen monoxide and nitrogen dioxide gas) waste gas that produces among the whole process of tin-stripping waste liquid treatment process enters into tail gas processing apparatus through exhaust system, sprays hydrogen peroxide solution through the tertiary and handles, thoroughly retrieves effective components such as nitrogen monoxide and nitrogen dioxide in the tail gas, and the solution after the absorption turns into dilute nitric acid solution, and this solution can regard as the make-up fluid of liquid nitric acid, and the tail gas after the tertiary absorption contains trace acidity, sprays through a small amount of basicity and handles up to standard back emission.
The main gas components in the waste gas are nitric oxide and dinitrogen tetroxide, the industry adopts a method of spraying hydrogen peroxide to carry out oxidation treatment on the two components, the treated product is valuable dilute nitric acid, the product is exactly the main component required by the tin stripping subphase, and the reaction formula is as follows:
3H2O2+2NO＝2NO3 -+2H++2H20-------①
H2O2+N2O4＝2NO3 -+2H+-------②
as can be seen from the above ion chemical reaction formula, the product after the reaction is dilute nitric acid, and not only valuable nitrate ions but also hydrogen ions are actually obtained (no additional acid is added). And continuously spraying and absorbing the waste gas by adopting hydrogen peroxide, repeatedly spraying the waste gas in three stages, spraying the tail gas by using a first-stage dilute sodium hydroxide solution, and finally enabling the tail gas emission to meet the standard of table 2 of the Integrated emission Standard of atmospheric pollutants (GB 16294-1996).
5. Waste water
The supernatant which is completely precipitated in the post-process of the process mainly comprises three components of hydrogen radicals, ferric iron, nitrate ions and the like, the liquid which is filtered by a filter press can be directly prepared into tin-stripping solution, and particularly, the supernatant which is precipitated once and separated from solid and liquid is adopted as the circulating additive solution of the next round of precipitation once and separation from solid and liquid, so that the process completely realizes the recycling, the whole process does not generate waste water, or the zero discharge of the waste water is realized.
In conclusion, the tin-stripping waste liquid recycling process provided by the invention comprises two times of precipitation and solid-liquid separation, wherein sulfuric acid and a small amount of substances such as selective metal capture agents oxalic acid and settling aids (diatomite and polyacrylamide) are added into the tin-stripping waste liquid twice in sequence, so that metal ions, namely tin and copper in the waste liquid are subjected to selective precipitation separation, the tin content in the separated tin mud and the copper content in the copper mud are greatly improved, and the recovery value of the tin mud and the copper mud in the tin-stripping waste liquid is increased. Waste gas generated in the recovery process of the tin stripping waste liquid is sprayed and absorbed by the three-level hydrogen peroxide, so that zero emission of nitrogen oxides in the waste gas can be realized.
In addition, the tin stripping liquid medicine can be recycled, no waste water and no dangerous waste gas are generated in the whole production process, and tin, copper and dilute nitric acid are recovered, so that great economic and social benefits are created, and the process becomes a clean production process in real sense.
Although specific embodiments of the invention have been described above, it will be understood by those skilled in the art that the specific embodiments described are illustrative only and are not limiting upon the scope of the invention, and that equivalent modifications and variations can be made by those skilled in the art without departing from the spirit of the invention, which is to be limited only by the appended claims.
Claims (4)
1. A PCB tin waste liquid recycling and regenerating type tin, copper and waste gas treatment method is characterized in that: the method comprises the following steps:
step 1, firstly, adding sulfuric acid or sulfate into PCB tin waste liquid to precipitate tin ions into tin sulfate, then adding a proper amount of diatomite and polyacrylamide, further increasing precipitate particles, finally separating tin sulfate precipitate from supernatant, and recovering the tin sulfate precipitate;
step 2, adding sulfuric acid or sulfate into the new PCB tin waste liquid to precipitate tin ions into tin sulfate, adding a proper amount of diatomite, then adding the supernatant obtained in the step 1 after the first solid-liquid separation as a circulating separating agent, finally adding polyacrylamide, further increasing precipitate particles, then separating tin sulfate precipitate from the supernatant, and recovering the tin sulfate precipitate; continuously adding new PCB tin waste liquid into the obtained supernatant, circularly repeating the step 2 until the weight percentage content of copper in the supernatant reaches 3-6% or the weight percentage of nitric acid reaches 30% -50%, and entering the step 3;
3, adding oxalic acid into the supernatant obtained in the step 2 to precipitate copper ions, adding a proper amount of diatomite and polyacrylamide filter aid, further increasing precipitate particles, separating copper metal precipitate from the supernatant, and performing filter pressing on the precipitate to obtain copper mud for recycling;
and 4, blending the filtrate obtained in the step 3 with a regeneration solution, and adjusting the main components to ensure that the volume content of the nitric acid in the solution is as follows: 10-30%, and the content of ferric iron: 19-55 g/L, copper protecting agent benzotriazole: 2.4-8.5 g/l, urea: 2.4-9.0 g/L to obtain a tin stripping regeneration sub-solution, and then returning the tin stripping regeneration sub-solution to a tin stripping production line to be used as a tin stripping solution;
step 5, collecting tail gas containing nitric oxide and dinitrogen tetroxide generated in the reaction process, spraying the tail gas by hydrogen peroxide, discharging after the tail gas meets the standard through detection, and recovering dilute nitric acid generated after spraying; the dilute nitric acid can be used for preparing the tin stripping regeneration sub-solution in the step 4, and zero emission of nitrogen oxides in waste gas is realized.
2. The PCB tin waste liquid recycling and regenerating type tin, copper and waste gas treatment method of claim 1 is characterized in that: the main raw material components for preparing the tin stripping regeneration sub-solution in the step 4 are as follows: nitric acid, ferric nitrate, benzotriazole, urea and ferric trichloride.
3. The PCB tin waste liquid recycling and regenerating type tin, copper and waste gas treatment method of claim 1 is characterized in that: the specific gravity of the filtrate of the stripping regeneration sub-solution obtained in the step 4 is 1.05-1.18.
4. The PCB tin waste liquid recycling and regenerating type tin, copper and waste gas treatment method of claim 1 is characterized in that: and 5, spraying the tail gas in the step 5 through three stages of hydrogen peroxide, spraying the tail gas through a first-stage dilute sodium hydroxide solution, and finally discharging the tail gas after the tail gas meets the standard.
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