CN114959290A - Method for selectively leaching and recycling precious metal gold, silver and palladium in electronic waste step by step - Google Patents
Method for selectively leaching and recycling precious metal gold, silver and palladium in electronic waste step by step Download PDFInfo
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- CN114959290A CN114959290A CN202210525164.0A CN202210525164A CN114959290A CN 114959290 A CN114959290 A CN 114959290A CN 202210525164 A CN202210525164 A CN 202210525164A CN 114959290 A CN114959290 A CN 114959290A
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- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 title claims abstract description 154
- 229910052763 palladium Inorganic materials 0.000 title claims abstract description 79
- 239000010931 gold Substances 0.000 title claims abstract description 78
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 77
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 73
- 229910052709 silver Inorganic materials 0.000 title claims abstract description 71
- 239000004332 silver Substances 0.000 title claims abstract description 71
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 238000002386 leaching Methods 0.000 title claims abstract description 51
- 239000010793 electronic waste Substances 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 24
- 239000010970 precious metal Substances 0.000 title claims description 11
- 238000004064 recycling Methods 0.000 title description 4
- 239000000706 filtrate Substances 0.000 claims abstract description 62
- 238000001914 filtration Methods 0.000 claims abstract description 30
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 claims abstract description 28
- 229910021607 Silver chloride Inorganic materials 0.000 claims abstract description 27
- 239000000126 substance Substances 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 20
- JGUQDUKBUKFFRO-CIIODKQPSA-N dimethylglyoxime Chemical compound O/N=C(/C)\C(\C)=N\O JGUQDUKBUKFFRO-CIIODKQPSA-N 0.000 claims abstract description 19
- 239000002244 precipitate Substances 0.000 claims abstract description 19
- 239000008367 deionised water Substances 0.000 claims abstract description 15
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 15
- 239000000843 powder Substances 0.000 claims abstract description 12
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims abstract description 4
- PQTCMBYFWMFIGM-UHFFFAOYSA-N gold silver Chemical compound [Ag].[Au] PQTCMBYFWMFIGM-UHFFFAOYSA-N 0.000 claims abstract 3
- 239000000203 mixture Substances 0.000 claims abstract 2
- 238000002390 rotary evaporation Methods 0.000 claims abstract 2
- 239000000243 solution Substances 0.000 claims description 19
- -1 gold ions Chemical class 0.000 claims description 18
- OEYIOHPDSNJKLS-UHFFFAOYSA-N choline Chemical compound C[N+](C)(C)CCO OEYIOHPDSNJKLS-UHFFFAOYSA-N 0.000 claims description 13
- 229960001231 choline Drugs 0.000 claims description 13
- 239000002904 solvent Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 10
- FPYYNALBDHWLNB-UHFFFAOYSA-N C(C)O.CC(C(=NO)C)=NO Chemical compound C(C)O.CC(C(=NO)C)=NO FPYYNALBDHWLNB-UHFFFAOYSA-N 0.000 claims description 8
- 229910001504 inorganic chloride Inorganic materials 0.000 claims description 8
- MPTQRFCYZCXJFQ-UHFFFAOYSA-L copper(II) chloride dihydrate Chemical compound O.O.[Cl-].[Cl-].[Cu+2] MPTQRFCYZCXJFQ-UHFFFAOYSA-L 0.000 claims description 7
- 239000011259 mixed solution Substances 0.000 claims description 6
- 238000001556 precipitation Methods 0.000 claims description 5
- VYWQTJWGWLKBQA-UHFFFAOYSA-N [amino(hydroxy)methylidene]azanium;chloride Chemical compound Cl.NC(N)=O VYWQTJWGWLKBQA-UHFFFAOYSA-N 0.000 claims description 4
- 150000003841 chloride salts Chemical class 0.000 claims description 4
- OASOQJKCZXXDMI-UHFFFAOYSA-N ethane-1,2-diol;hydrochloride Chemical compound Cl.OCCO OASOQJKCZXXDMI-UHFFFAOYSA-N 0.000 claims description 3
- 239000001763 2-hydroxyethyl(trimethyl)azanium Substances 0.000 claims description 2
- 235000019743 Choline chloride Nutrition 0.000 claims description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 2
- SGMZJAMFUVOLNK-UHFFFAOYSA-M choline chloride Chemical compound [Cl-].C[N+](C)(C)CCO SGMZJAMFUVOLNK-UHFFFAOYSA-M 0.000 claims description 2
- 229960003178 choline chloride Drugs 0.000 claims description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 2
- KQPMFNHZHBLVRR-UHFFFAOYSA-N oxalic acid;hydrochloride Chemical compound Cl.OC(=O)C(O)=O KQPMFNHZHBLVRR-UHFFFAOYSA-N 0.000 claims description 2
- NQCBIMOYRRMVNA-UHFFFAOYSA-N propane-1,2,3-triol;hydrochloride Chemical compound Cl.OCC(O)CO NQCBIMOYRRMVNA-UHFFFAOYSA-N 0.000 claims description 2
- CJGOMTUOQIGPNI-UHFFFAOYSA-N propane-1,2-diol;hydrochloride Chemical compound Cl.CC(O)CO CJGOMTUOQIGPNI-UHFFFAOYSA-N 0.000 claims description 2
- 238000011084 recovery Methods 0.000 abstract description 11
- 229910000510 noble metal Inorganic materials 0.000 abstract description 4
- 230000008901 benefit Effects 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 abstract 1
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 9
- 239000013049 sediment Substances 0.000 description 8
- 238000010183 spectrum analysis Methods 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000000605 extraction Methods 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 230000029087 digestion Effects 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- 229910001020 Au alloy Inorganic materials 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 101150003085 Pdcl gene Proteins 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 150000002941 palladium compounds Chemical class 0.000 description 1
- 239000012716 precipitator Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 231100000004 severe toxicity Toxicity 0.000 description 1
- 229940100890 silver compound Drugs 0.000 description 1
- 150000003379 silver compounds Chemical class 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B11/00—Obtaining noble metals
- C22B11/04—Obtaining noble metals by wet processes
- C22B11/042—Recovery of noble metals from waste materials
- C22B11/046—Recovery of noble metals from waste materials from manufactured products, e.g. from printed circuit boards, from photographic films, paper or baths
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
-
- 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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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention discloses a method for recovering noble metals gold, silver and palladium from electronic waste by selective leaching step by step. Taking electronic waste powder containing gold, silver and palladium as a raw material, firstly adding an ionic liquid-chloride system for leaching reaction, and filtering after leaching to obtain a first filtrate and filter residue; and adding deionized water into the first filtrate, filtering to obtain a second filtrate and a gold-silver mixed precipitate, adding dimethylglyoxime solution into the second filtrate, and filtering to obtain a third filtrate and a dimethylglyoxime palladium precipitate. Adding a certain amount of calcium chloride solution into the gold and silver mixture, filtering to obtain a fourth filtrate and simple substance gold, and finally adding water into the fourth filtrate and filtering to obtain silver chloride precipitate and a fifth filtrate. Finally, the third filtrate can be used for a leaching link after rotary evaporation. The method has the advantages of simple process, convenient operation and short leaching time, can selectively leach the gold, silver and palladium in the electronic waste, and can realize green and efficient recovery of noble metals such as gold, silver and palladium.
Description
Technical Field
The invention relates to a method for selectively leaching and recovering precious metal gold, silver and palladium in electronic waste, belonging to the technical field of metal recovery and solid waste recycling.
Background
Gold and silver have more and more extensive applications in the electronic industry due to their excellent stability and good electrical and thermal conductivity, such as high-frequency conductors for electroplating gold and silver and gold and silver alloys for high-temperature soldering in radio electronic components in the aerospace industry. Palladium, as a noble metal having excellent high temperature resistance, corrosion resistance and stable electrical characteristics, has been widely used in various fields such as electronics, medicine, chemical catalysts, and the like. Compared with gold, silver and palladium ores, the gold, silver and palladium content in the gold, silver and palladium-containing waste material is higher, so that the recovery of gold, silver and palladium from secondary resources is of great significance.
At present, the methods for recovering gold, silver and palladium in production comprise the following steps: dissolving alloy in nitric acid, adding silver and palladium into solution, precipitating silver with sodium chloride, and adding part of palladium in Ag 2 PdCl 6 The form (A) is co-precipitated with AgCl, and silver chloride adsorbs a large amount of palladium, resulting in difficult separation of silver and palladium; in the concentrated sulfuric acid separation method, when the concentrated sulfuric acid is used for dissolving silver, the required temperature is high, the silver dissolving effect is poor, most palladium also enters the solution, the recovery of silver is influenced, the refining of gold and palladium is also influenced, and the silver dissolving speed of the sulfuric acid is low. Therefore, it is of great significance to explore a green leaching recovery system for selectively dissolving gold, silver and palladium in electronic waste.
In previous researches, gold, silver and palladium are distributed and recovered by DMF (N, N-dimethylformamide), but DMF has a larger environment-friendly effect compared with strong acid and strong alkali, but basically has certain harm to human bodies and the environment.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for selectively leaching and recovering precious metals gold, silver and palladium in electronic waste based on an ionic liquid-chloride system; the method adopts a selective leaching method, can selectively leach the precious metals of gold, silver and palladium in the electronic waste to obtain high-purity gold, high-purity silver compound and high-purity palladium compound, has important significance for precious metal recovery, and avoids using strong acid or cyanide and other reagents with serious secondary pollution and severe toxicity to ensure that the recovery process is green and pollution-free.
According to the invention, the recovery of precious metals of gold, silver and palladium in the electronic waste is realized by adopting an ionic liquid-chloride system selective leaching method, which is different from the conventional DMF system, and the leaching solvent is further optimized. The ionic liquid has good environmental benefit and good stability. The reagent used in the patent can recycle gold, silver and palladium in the electronic waste, and can realize the distributed extraction of three precious metals by adding deionized water, calcium chloride aqueous solution, precipitator and other methods, thereby achieving the purpose of recycling.
The technical scheme of the invention is as follows.
The invention provides a method for selectively leaching and recovering precious metals gold, silver and palladium in electronic waste, which comprises the following specific steps:
(1) taking a mixed solution composed of inorganic chloride and an ionic liquid-like solvent as a leaching solution, adding electronic waste powder containing gold, silver and palladium into the leaching solution according to a solid-liquid mass-volume ratio of 1:10-1:90g/mL for leaching reaction, wherein the leaching temperature is 30-90 ℃, the leaching time is 60-120min, and after leaching is finished, filtering to obtain a first filtrate and filter residue;
(2) adding deionized water into the first filtrate to reduce and precipitate gold ions and silver ions in the filtrate, after precipitation is finished, adding 0.5-1mol/L calcium chloride solution into the system to dissolve precipitated silver chloride, wherein the addition amount of the silver chloride is 20-80% of the leachate, and filtering to obtain a fourth filtrate and a gold simple substance;
(3) continuously adding water into the fourth filtrate to precipitate silver ions, and filtering to obtain a fifth filtrate and silver chloride;
(4) adding dimethylglyoxime precipitant into the second filtrate to precipitate reduced palladium, and filtering after reduction to obtain dimethylglyoxime palladium and a third filtrate; the above steps are respectively implemented to recover the simple substance, the silver chloride and the dimethylglyoxime palladium, and the third filtrate is recycled.
In the step (1), the solid-liquid mass volume ratio of the mixed solution composed of the electronic waste powder containing gold, silver and palladium, the inorganic chloride and the ionic liquid-like solvent is 1:10-1:40 g/mL.
In the step (1), the inorganic chloride salt is one or more of copper chloride dihydrate, anhydrous copper chloride and ferric chloride; the concentration of the inorganic chloride salt in the mixed solution is as follows: 0.25-1.5 mol/L; the ionic liquid-like solvent is any one or more of choline chloride-urea, choline chloride-propylene glycol, choline chloride-oxalic acid, choline chloride-glycerol and choline chloride-ethylene glycol, wherein the mol ratio of the choline chloride to the other component is as follows: 1:2.
In the step (2), the volume ratio of the deionized water to the first filtrate is as follows: 1: 2-2: 1, the precipitation time is 0.5-1.5 h.
In the step (2), the solubility of the added calcium chloride solution is as follows: 0.5-1mol/L, and the addition amount is 20-80% of the volume of the leaching solution. The addition amount of calcium chloride is related to the silver content in the electronic waste, and the silver is dissolved again along with the addition of the calcium chloride.
In the step (3), the deionized water is added to the second filtrate in a volume equal to that of the leachate.
In the step (4), 0.1mol/L-1mol/L of dimethylglyoxime ethanol solution is added into the third filtrate to precipitate and reduce palladium, and the addition amount of the dimethylglyoxime ethanol solution is 40-100% of the volume of the leachate.
Compared with the prior art, the invention has the beneficial effects that:
the method has the advantages of simple process, convenient operation, short leaching time, low cost and high recovery efficiency. The non-toxic and biodegradable ionic liquid-like green solvent is adopted, gold, silver and palladium in the electronic waste can be selectively leached, a large amount of toxic solvents such as strong acid and the like are avoided, meanwhile, the reduction of other substances is reduced, and the difficulty of subsequent metal separation is reduced. The green and efficient recovery of the noble metal gold, silver and palladium is realized.
Drawings
Fig. 1 is a process flow chart of the method for selectively leaching and recovering the precious metals gold, silver and palladium in the electronic waste.
FIG. 2 spectral analysis of gold precipitate in example 1.
FIG. 3 spectral analysis of the precipitate combined with silver in example 1.
FIG. 4 spectral analysis of palladium combined with precipitates in example 1.
Detailed Description
The invention is described in detail below with reference to the drawings and the embodiments.
Example 1
The digestion result shows that the gold content of the electronic waste containing gold, silver and palladium is 0.003 percent, the palladium content is 0.007 percent and the silver content is 0.01 percent; the copper content is 11.5%, the nickel content is 2.8% and the iron content is 1.3%. The extraction process is shown in figure 1: 0.33g of electronic waste powder containing gold, silver and palladium is put into 10mL of choline chloride-ethylene glycol liquid solvent containing 1.5mol/L of copper chloride (the solid-liquid mass ratio is 1:30 g/mL), and heated in water bath at 80 ℃. Leaching for 10min, filtering after leaching is finished, and in the first filtrate, gold is trivalent, palladium is divalent, copper is 2-valent, and silver is 1-valent. And adding 10mL of deionized water into the first filtrate, and filtering to obtain a second filtrate and a mixed precipitate of gold and silver. Reducing gold ions in the first filtrate into a gold simple substance for precipitation, precipitating silver ions in a silver chloride form, adding 5mL of 0.6mol/L calcium chloride solution into the precipitate, dissolving the silver chloride in the solution, filtering the solution to filter the gold simple substance, and filtering to obtain a fourth filtrate and the gold simple substance; adding 10mL of deionized water into the fourth filtrate to reduce silver ions, and filtering to filter silver chloride to obtain a fifth filtrate and silver chloride; 6mL of 0.1mol/L dimethylglyoxime ethanol solution is added into the second filtrate, and palladium ions in the filtrate are precipitated in a dimethylglyoxime palladium mode. And filtering to obtain a fourth filtrate and the palladium dimethylglyoxime. Finally, the precipitate is combined to obtain simple substance gold, silver chloride and palladium dimethylglyoxime. The leaching rate of gold reaches more than 99.7%, the leaching rate of silver reaches more than 99.7%, the leaching rate of palladium reaches more than 99.6%, the leaching rate of copper reaches 32.1%, the leaching rate of nickel reaches 19.3%, and the leaching rate of iron reaches 5.9%. The precipitate simple substance gold, the precipitate silver chloride and the precipitate dimethylglyoxime palladium are respectively subjected to electron microscope energy spectrum analysis, and the energy spectrum analysis shows that no peak value of other metals is found in the detection of the precipitate, so that the high-purity selective recovery of the gold, silver and palladium in the electronic waste powder containing the gold, silver and palladium by the ionic liquid-chloride system is demonstrated.
Example 2
The electronic waste containing gold, silver and palladium is subjected to digestion to obtain the electronic waste containing gold, silver and palladium, wherein the gold content is 0.01%, the palladium content is 0.05% and the silver content is 0.08%; the extraction process is shown in figure 1: 1g of electronic waste powder containing gold, silver and palladium is put into 30mL of choline chloride-urea liquid solvent containing 1mol/L of copper chloride (the solid-liquid mass ratio is 1:30 g/mL), and the electronic waste powder is heated in water bath at the temperature of 90 ℃. Leaching for 10min, filtering after leaching, adding 30mL of deionized water into the first filtrate, reducing gold ions in the first filtrate to precipitate as a gold simple substance, reducing silver ions in the filtrate to precipitate as silver chloride, adding 10mL of 0.5mol/L calcium chloride solution, dissolving silver chloride in the solution, filtering to filter out the gold simple substance, and filtering to obtain a second filtrate and the gold simple substance; adding 30mL of deionized water into the second filtrate to reduce silver ions, and filtering to filter silver chloride to obtain a third filtrate and silver chloride; then 18mL of 0.1mol/L dimethylglyoxime ethanol solution is added into the third filtrate, and palladium ions in the filtrate are precipitated in a dimethylglyoxime palladium mode. And filtering to obtain a fourth filtrate and the palladium dimethylglyoxime. Finally, the precipitate is subjected to the reaction to obtain the simple substance gold, the silver chloride and the palladium dimethylglyoxime. The leaching rate of gold is more than 99.6%, the leaching rate of silver is more than 99.5%, and the leaching rate of palladium is more than 99.4%. The sediment simple substance gold, the sediment silver chloride and the sediment dimethylglyoxime palladium are respectively detected by an electron microscope, and energy spectrum analysis shows that in the detection of the sediment, no peak value of other metals is found, thereby showing that the ionic liquid-chloride system selectively recovers the gold, silver and palladium in the electronic waste powder containing the gold, silver and palladium with high purity.
Example 3
The electronic waste containing gold, silver and palladium is subjected to digestion to obtain the electronic waste containing gold, silver and palladium, wherein the gold content is 0.02%, the palladium content is 0.08% and the silver content is 0.08%; the extraction process is shown in figure 1: 3g of electronic waste powder containing gold, silver and palladium is put into 30mL of choline chloride-urea liquid solvent containing 1.2mol/L of copper chloride (the solid-liquid mass ratio is 1:10 g/mL), and heated in water bath at 90 ℃. Leaching for 10min, filtering after leaching, adding 30mL of deionized water into the first filtrate, reducing gold ions in the first filtrate to precipitate as a gold simple substance, reducing silver ions in the filtrate to precipitate as silver chloride, adding 10mL of 0.5mol/L calcium chloride solution, dissolving silver chloride in the solution, filtering to filter out the gold simple substance, and filtering to obtain a second filtrate and the gold simple substance; adding 30mL of deionized water into the second filtrate to reduce silver ions, and filtering to filter silver chloride to obtain a third filtrate and silver chloride; then 18mL of 0.1mol/L dimethylglyoxime ethanol solution is added into the third filtrate, and palladium ions in the filtrate are precipitated in a dimethylglyoxime palladium mode. And filtering to obtain a fourth filtrate and the palladium dimethylglyoxime. Finally, the precipitate is combined to obtain simple substance gold, silver chloride and palladium dimethylglyoxime. The leaching rate of gold is more than 99.5%, the leaching rate of silver is more than 99.6%, and the leaching rate of palladium is more than 99.99%. The sediment simple substance gold, the sediment silver chloride and the sediment dimethylglyoxime palladium are respectively detected by an electron microscope, and energy spectrum analysis shows that in the detection of the sediment, no peak value of other metals is found, thereby showing that the ionic liquid-chloride system selectively recovers the gold, silver and palladium in the electronic waste powder containing the gold, silver and palladium with high purity.
Claims (7)
1. A method for selectively leaching and recovering precious metal gold, silver and palladium in electronic waste is characterized by comprising the following specific steps: (1) taking a mixed solution composed of inorganic chloride and an ionic liquid-like solvent as a leaching solution, adding electronic waste powder containing gold, silver and palladium into the leaching solution according to a solid-liquid mass-volume ratio of 1:10-1:90g/mL for leaching reaction, wherein the leaching temperature is 30-90 ℃, the leaching time is 10-60min, and after leaching is finished, filtering to obtain a first filtrate and filter residue;
(2) adding deionized water into the first filtrate to reduce and precipitate gold ions and silver ions in the filtrate, filtering after precipitation to obtain a silver-gold mixture and a second filtrate, adding a calcium chloride solution with a certain concentration into the gold-silver mixed precipitate to dissolve the precipitated silver chloride, and filtering to obtain a fourth filtrate and a gold simple substance;
(3) adding dimethylglyoxime ethanol solution into the second filtrate to precipitate palladium ions, and filtering to obtain a third filtrate and dimethylglyoxime palladium;
(4) adding deionized water into the fourth filtrate to precipitate silver, and filtering after reduction to obtain silver chloride precipitate and a fifth filtrate; the above steps are respectively implemented to recover the simple substance, the silver chloride and the palladium dimethylglyoxime;
(5) the third filtrate can be used for leaching again after rotary evaporation, and closed cycle is realized.
2. The method according to claim 1, wherein in the step (1), the solid-liquid mass volume ratio of the mixed solution of the gold-silver-palladium-containing electronic waste powder, the inorganic chloride and the ionic liquid-like solvent is 1:10-1:40 g/mL; the leaching temperature is 80-90 deg.C, and the leaching time is 10-20 min.
3. The method according to claim 1, wherein in the step (1), the inorganic chloride salt is one or more of copper chloride dihydrate, anhydrous copper chloride and ferric chloride; the concentration of the inorganic chloride salt in the mixed solution is as follows: 0.25-1.5 mol/L; the ionic liquid-like solvent is any one or more of choline chloride-urea, choline chloride-propylene glycol, choline chloride-oxalic acid, choline chloride-glycerol and choline chloride-ethylene glycol, wherein the mol ratio of the choline chloride to the other component is as follows: 1:2.
4. The method according to claim 1, wherein in the step (2), the calcium chloride solution is added in an amount of 20 to 80% by volume of the leachate at a concentration of 0.5 to 1 mol/L.
5. The method of claim 1, wherein the volume ratio of deionized water to the first filtrate in step (2) is: 1: 2-2: 1, the precipitation time is 0.5-1.5 h.
6. The method according to claim 1, wherein in the step (3), 1mol/L to 1mol/L of the dimethylglyoxime ethanol solution is added to the second filtrate to precipitate and reduce the palladium, and the dimethylglyoxime ethanol solution is added in an amount of 40 to 100 percent by volume of the leachate.
7. The method according to claim 1, wherein in the step (4), the deionized water is added to the fourth filtrate in an amount equal to the volume of the leachate.
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