CN111172398A - Wet harmless extraction process for metal in waste mobile phone circuit board - Google Patents
Wet harmless extraction process for metal in waste mobile phone circuit board Download PDFInfo
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- CN111172398A CN111172398A CN202010058345.8A CN202010058345A CN111172398A CN 111172398 A CN111172398 A CN 111172398A CN 202010058345 A CN202010058345 A CN 202010058345A CN 111172398 A CN111172398 A CN 111172398A
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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
- 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
- C22B7/007—Wet processes by acid leaching
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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
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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
- C22B15/00—Obtaining copper
- C22B15/0063—Hydrometallurgy
- C22B15/0065—Leaching or slurrying
- C22B15/0067—Leaching or slurrying with acids or salts thereof
- C22B15/0071—Leaching or slurrying with acids or salts thereof containing sulfur
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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
- C22B15/00—Obtaining copper
- C22B15/0063—Hydrometallurgy
- C22B15/0084—Treating solutions
- C22B15/0089—Treating solutions by chemical methods
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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
- C22B25/00—Obtaining tin
- C22B25/04—Obtaining tin by wet processes
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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
- C22B25/00—Obtaining tin
- C22B25/06—Obtaining tin from scrap, especially tin scrap
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
- C23F1/44—Compositions for etching metallic material from a metallic material substrate of different composition
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention provides a wet harmless extraction process of metals in a waste mobile phone circuit board, aiming at the problems in the prior art of metal recovery in the waste mobile phone circuit board, the waste mobile phone circuit board is disassembled into an IC chip, a surface mounted device and a light plate, low-toxicity and environment-friendly leaching agents are developed, tin, copper, silver and gold palladium are directionally and selectively leached by a step-by-step method, then reduction extraction is respectively carried out, the recovery rates of gold, silver and palladium reach more than 95%, and a proper gold stripping agent is selected for stripping a gold plating layer on the light plate.
Description
Technical Field
The invention belongs to the technical field, and particularly relates to a wet harmless extraction process of metal in a waste mobile phone circuit board.
Background
In the electronic waste, the special feature of the waste mobile phone, such as fast update speed and high recycling value, is becoming the key point of the future recycling treatment of the electronic waste. The materials used in the mobile phone can be roughly divided into two categories, one is glass fiber and resin materials, accounts for about 65.90%, and is mostly used for plastic shells, screens, speakers, cameras and the like of the mobile phone; one is a metallic material, accounting for about 29.12%, mainly gold, palladium, silver, copper, tin, nickel, etc., which is basically present in the metal case and circuit board of the cellular phone. A handset typically includes 9 parts, namely: 30-40% of the total mass of the printed circuit board, the liquid crystal display screen, the battery, the antenna, the keyboard, the microphone, the loudspeaker, the shell and other accessories is various metals including noble metals such as gold, silver, palladium and the like. Compared with the primary mineral products, the content of the precious metals in the mobile phone is higher, the content of the natural gold ore, namely the grade, is as low as 3g/t, the mining value is higher, the gold concentrate obtained through mineral separation is only about 70g/t, and the gold content in the scrapped mobile phone can reach 60-400 g/t. The content of palladium in the mobile phone can reach 10-20 g/t. The content of noble metals in the waste mobile phones is greatly influenced by the brand, production date, process and the like of the mobile phones, and the content of gold, silver and copper in each ton of ipHone is reported to be about 302g, 3023g and 128.6 kg; research carried out by the Holland Delft technology university shows that the content of the noble metals in the mobile phone between 1999 and 2003 is as follows: 0.038% of gold, 0.244% of silver, 14.24% of copper and 0.015% of palladium, and the content of noble metals is reduced, and the content of gold, silver, copper and palladium in the mobile phone in 2003 is respectively reduced by 25.7%, 51.8%, 22% and 31% compared with that in 1999. The American research shows that the average weight of each mobile phone is 113g in 2005, and each mobile phone contains 0.034g of gold, 0.35g of silver, 0.015g of palladium and 16g of copper. Estimates from practical experience by the beauty company of Belgium indicate that the precious metals in a scrapped cell phone are about 0.034% gold, 0.35% silver, and 0.013% palladium. The experimental study on the material composition of the waste mobile phone in 2012 by the Chinese academy of sciences and the like shows that the content of copper in the material of the waste mobile phone is 11.3%, the content of gold, silver, palladium and the like is 0.00654%, the content of gold, silver, palladium and the like is 0.011% and 0.00406%, and the content of noble metal is obviously reduced compared with the existing data. Therefore, the content of rare and precious metals in the waste mobile phones from different sources and the resource value are greatly different, and according to the investigation of important enterprises for recycling the waste mobile phones in China, the gold content of the common waste mobile phones in the recycling market in China is about 150-200 g/t at present.
At present, due to the perfection of laws and regulations of waste electronic waste, waste circuit boards can be collected into one or two smelting plants in a centralized manner, large-scale high-temperature pyrometallurgy is adopted, a treatment factory is a large smelting plant, the waste circuit boards are used as a part of metallurgical raw materials according to the requirements of a metallurgical blast furnace, 10-20% of circuit boards are added in the metal smelting process, for example, a British American company can treat 25 ten thousand tons of waste circuit boards every year in Belgium, all precious metals are concentrated into copper smelting for subsequent treatment, meanwhile, due to the unique blast furnace smelting technology, the following intractable carcinogens such as dioxin and the like cannot be generated in the smelting process, and an environment-friendly treatment system is perfect.
More than 100 qualified waste household appliance disassembling enterprises are in China, and mainly perform disassembling and processing services of televisions, refrigerators, air conditioners, washing machines and computers, the nation subsidizes according to the number of the disassembled waste circuit boards according to the disassembling processing quantity, the disassembled waste circuit boards are processed by a mechanical physical method, the waste circuit boards are subjected to crushing, electric separation, magnetic separation and other processing steps, finally, metal is enriched into metal powder, then the metal powder is sent to a professional metal smelting plant for processing, and the enriched resin and glass fiber powder are subjected to landfill processing. The circuit board of the waste mobile phone belongs to one kind of circuit board, has the same parts with circuit boards disassembled from four machines of a television, a refrigerator, an air conditioner, a washing machine, a computer and the like, and is also greatly different from the circuit boards disassembled from the four machines of the television, the refrigerator, the air conditioner, the washing machine, the computer and the like, the most valuable parts of the circuit boards in the waste mobile phone are nonferrous metals and noble metals contained in the circuit boards, account for about 30 percent of the total mass of the mobile phone, and mainly comprise gold, palladium, silver, copper. By taking gold as an example only, the circuit board and the mobile phone of each ton respectively contain about 200g and 300 g of gold according to tests, the average grade of the gold ore is only 5g per ton, and the gold content of the electronic garbage is 40 to 60 times of that of the gold ore, so that great economic benefits are obtained.
At present, precious metals such as gold, silver, palladium and the like in electronic waste are extracted from domestic mobile phone circuit boards mainly by simple incineration and backward technical means such as aqua regia, cyanide and the like, so that serious environmental pollution is caused, a family workshop type treatment mode is adopted, waste water and waste gas are discharged at will, for example, in a region where precious metals are extracted from waste electrical equipment elements such as Guangdong precious metal and Taizhou Zhejiang, the flame retardant containing halogen elements in the waste circuit boards can generate carcinogenic substances in the combustion process, so that the health of a human body and the surrounding environment are threatened; in the subsequent acid leaching traditional process, hazardous reagents such as cyanide virulent reagents or aqua regia are mostly adopted, in the treatment process, workers need to be careful and careless, accidents which harm human bodies can be caused, and waste water, waste gas and residues generated in the treatment process are difficult to treat and are discharged randomly, so that the ecological environment and human beings are seriously harmed.
Moreover, 109 domestic qualified waste household appliance treatment enterprises adopt a mechanical physical sorting method to treat the waste circuit boards disassembled from televisions, washing machines, refrigerators, air conditioners and computers, and the method is the mainstream process for treating the waste circuit boards in China at present. The defects that the final products are metal powder enrichment body and resin glass fiber powder, and the metal enrichment body needs to be further purified and separated by other processes. Compared with a waste circuit board disassembled from a traditional four-machine one; because laws and regulations of the waste mobile phones are not sound, the recovery treatment of the waste mobile phones is still in a rough operation treatment stage at present, the waste mobile phones are recovered and dispersed, a precious mode is generally adopted, firstly, metal is enriched by burning a circuit board, then, the metal is leached by adopting solutions of aqua regia, cyanide and the like, and then, the gold is extracted by adopting methods of replacement and the like. The waste water and the waste gas are discharged at will, which causes serious environmental pollution.
In conclusion, the content of the precious metals in the mobile phone is high, the waste mobile phone has the most recycling value of the precious metals in the circuit board, and the research and development of the green and environment-friendly extraction process of the precious metals and the prevention of the secondary pollution problem in the treatment process of the waste mobile phone are very important and urgent.
Disclosure of Invention
The invention provides a wet harmless extraction process of metals in a waste mobile phone circuit board, aiming at the problems in the prior art of metal recovery in the waste mobile phone circuit board, the waste mobile phone circuit board is disassembled into an IC chip, a surface mounted device and a light plate, low-toxicity and environment-friendly leaching agents are developed, tin, copper, silver and gold palladium are directionally and selectively leached by a step-by-step method, then reduction extraction is respectively carried out, the recovery rates of gold, silver and palladium reach more than 95%, and a proper gold stripping agent is selected for stripping a gold plating layer on the light plate.
The invention adopts the following technical scheme:
a wet harmless extraction process of metals in a waste mobile phone circuit board comprises the following steps:
firstly, disassembling: firstly, disassembling a waste mobile phone circuit board into a chip, a chip component and a light panel;
second, processing of chip and chip components
1) Crushing: crushing the chip and the surface mount device to prepare powder, and sorting to obtain metal powder;
2) tin leaching process
(a1) Adding the metal powder obtained in the step 1) into a tin immersion liquid for tin immersion treatment to ionize metal tin, and then filtering to obtain a solution containing tin ions and filter residues containing other metals;
wherein the tin immersion liquid is prepared from CuSO4Aqueous solutionAnd H2SO4Mixing the aqueous solutions, and immersing in tin solution of CuSO4The concentration of the tin-dipping solution is 10-20g/L, and the acidity of the tin-dipping solution is 7% -12%;
(a2) adjusting the pH value of the solution containing tin ions obtained in the step (a1) to 1.5-2.5, and adding an oxidant to the solution to form Sn (OH) as tin ions4Precipitating in the form of (1), and filtering again to obtain tin;
wherein the oxidant is hydrogen peroxide and the molar amount of the oxidant added is theoretically Sn2+1.02 to 1.5 times of the molar weight of (A);
3) copper silver leaching process
(b1) Adding the filter residue containing other metals obtained in the step (a1) into a mixed solution of sulfuric acid and sodium nitrate to leach copper ions and silver ions, and then filtering to obtain filter residue containing gold and palladium and filtrate containing copper and silver;
wherein the concentration of the sodium nitrate is 5-10 g/L, and the acidity of the mixed solution of the sulfuric acid and the sodium nitrate is 20-30%;
(b2) adding sodium chloride into the filtrate containing copper and silver obtained in the step (b1) to obtain silver chloride precipitate, and filtering and separating to obtain silver and copper-containing filtrate;
wherein the molar weight of the added sodium chloride is Ag+1.02-1.2 times of theoretical molar weight;
(b3) adding a copper precipitation agent into the copper-containing filtrate obtained in the step (b2), and separating to obtain copper;
wherein the copper precipitation agent is sodium sulfide or potassium sulfide, and the molar weight of the added sodium sulfide or potassium sulfide is Cu2+1.02-1.2 times of theoretical molar weight;
4) gold palladium cyanide-free leaching procedure
(c1) Adding cyanide-free leaching solution into the filter residue containing gold and palladium obtained in the step (b1) to leach out gold ions and palladium ions, then adding a gold reducing agent to reduce the gold ions, and filtering and separating to obtain gold and palladium ion-containing filtrate;
the cyanide-free leaching solution takes water as a solvent, wherein the concentration of each component is as follows: h2SO480-120 g/L of sodium chlorate 20-40 g/L and 3 g/L of hydrogen peroxide～7g/L；
The gold reducing agent is oxalic acid, sodium sulfite or sodium bisulfite;
(c2) adding zinc powder into the filtrate containing palladium ions obtained in the step (c1), and performing displacement reduction to obtain palladium;
three, light plate stripping process
1) Dissolving copper and nickel parts under the gold plating layer by adopting a gold stripping agent, stripping the gold plating layer and filtering to obtain gold;
wherein the gold stripping agent takes water as a solvent, and Cu (NH) in the gold stripping agent3)2The concentration of Cl is 0.5-1.5 mol/L, NH3The concentration is 0.5 to 1.5 mol/L.
Preferably, in the step two 1), the crushing operation is as follows: firstly, the chip and the chip component are crushed by a crusher and then ball-milled to 200 meshes.
Preferably, in the step two 2) (a1), the specific operating conditions of the tin immersion treatment are as follows: and (3) carrying out tin immersion treatment for 0.5-2 h at the temperature of 30-50 ℃.
Preferably, in the second step 3) (b1), the temperature for leaching the copper ions and the silver ions is 80-100 ℃, and the leaching time is 1-3 h.
Preferably, in the second step 4) (c1), the temperature of the leached gold ions and palladium ions is 80-100 ℃, and the leaching time is 1-3 h.
Preferably, in the step three 1), the temperature for stripping the gold plating layer is 20-40 ℃ and the time is 2-4 h.
Preferably, in the step three 1), the remaining light plate after gold stripping is subjected to physical sorting to obtain copper powder and resin powder.
Preferably, in the step three 1), the copper powder and the metal powder are mixed and then are synchronously processed.
The invention has the following beneficial effects:
aiming at the current situation, the invention extracts the precious metals by adopting a classification treatment mode according to the characteristics of the waste mobile phone circuit board and the occurrence characteristics of the precious metals, divides the waste mobile phone circuit board into a circuit board light plate (chips and components are disassembled), an IC chip and a patch component, wherein the light plate is the main body of the circuit board, accounts for about 75% of the weight of the waste circuit board, mainly contains gold, copper and nickel, a gold plating layer is exposed outside, the IC chip is an integrated circuit packaged by epoxy resin (added with carbon black and silicon powder), contains metals such as gold, silver, palladium, tin, copper and the like, accounts for about 5% of the weight of the waste circuit board, most of the components are ceramic-based materials, mainly contains metals such as gold, silver, palladium, tin, copper and the like, accounts for about 5% of the weight of the waste circuit board, and other; the value of gold accounts for 85-90% of the total value of 5 extracted metals by calculation, the gold content in the IC chip is 4-5 times of that in components, in order to ensure the extraction rate of gold in production, a gold stripping agent which is independently developed is adopted to strip a gold plating layer into gold foil and separate the gold foil from a circuit board substrate, then the gold foil is filtered, enriched and smelted into gold ingots for recycling, and the circuit board with the recovered gold plating layer is crushed and separated into resin powder and metal copper powder by a physical separation method; the precious metal gold with the highest value is recovered before crushing and sorting, so that the loss of gold is avoided, and the recovery rate of gold is improved;
from the aspects of low toxicity and environmental protection, according to the current industrial situation and the defects that cyanide, nitric acid, aqua regia and the like are used as main extracting agents in the existing extraction method, the IC chip and the components are ground into slurry of about 200 meshes by adopting crushing and ball milling, and five metal elements of gold, silver, palladium, tin and copper are extracted by wet leaching by adopting a low toxicity and environmental protection leaching and reducing method through systematic research on extracting agents; the invention discloses a method for extracting valuable metals from a mobile phone circuit board light plate without an IC chip and a patch component by adopting a wet gold stripping process, wherein a gold plating layer on the circuit board is stripped from a bottom layer metal, then gold foil is filtered and enriched, and a gold ingot is obtained by high-temperature smelting.
In summary, the invention divides the waste mobile phone circuit board into two parts of components and parts and a light board (chip and chip components are removed) through analyzing and detecting the types and contents of noble metals in the components of the mobile phone circuit board, and the components and the parts are respectively treated, the IC chip and the components adopt a hydrometallurgy process, the basic principle is that the chip and the components are crushed and then placed in aqueous solution media (acid and alkaline solutions), and then target metals are extracted by utilizing chemical action, and the process flow mainly comprises the following steps: the method comprises the steps of immersing metal ions into leachate in a leaching mode, enabling non-metal substances to still exist in leaching residues, purifying, precipitating, solvent extracting, ion exchanging, replacing, filtering, evaporating and the like the leachate to obtain target metals, adopting a wet gold stripping enrichment process for a light plate, dissolving copper and nickel of a bottom substrate by adopting a proper stripping agent, stripping a gold-plated layer on the substrate, and then enriching and recycling. The wet process has the advantages of higher recovery rate of main metals and associated metals, less energy consumption, easy solution of environmental protection problem, easy realization of automation in the production process and the like. Tests prove that the low-toxicity environment-friendly leaching agent developed by the invention directionally and selectively leaches tin, copper, silver and gold palladium by adopting a step method, and then respectively performs reduction extraction, the recovery rates of gold, silver and palladium reach more than 95%, each process unit does not generate pollutants such as nitrogen oxide, sulfur dioxide and the like, which are strictly controlled by the country for the total amount, and the environmental pollution is reduced from the source; the leaching and extraction waste liquid of each process unit can be recycled through simple treatment, the reuse rate of clear water is improved, the waste water discharge is reduced, the waste water does not contain complex organic matters and ammonia nitrogen, the waste water can be discharged up to the standard through simple treatment, and the environment-friendly disposal cost is reduced. Therefore, the wet harmless extraction process of the waste mobile phone circuit board provided by the invention eliminates the huge environmental pollution caused by the existing treatment process (cyanide, nitric oxide, aqua regia and the like), and has an important promotion effect on the healthy development of the waste mobile phone resource utilization field.
Detailed Description
In order to make the technical purpose, technical solutions and advantageous effects of the present invention more clear, the technical solutions of the present invention are further described below with reference to specific embodiments.
The invention provides a wet harmless extraction process of metal in a waste mobile phone circuit board, which comprises the following steps:
firstly, disassembling a waste mobile phone circuit board: firstly, removing electronic components on a waste mobile phone printed circuit board, collecting the electronic components in a classified manner, respectively collecting an IC chip and a chip component for standby to be crushed, and removing a light plate of the IC chip and the chip component for standby gold stripping recovery treatment;
second, crushing and ball milling of IC chip and components
IC chip and paster components and parts disassembled from the useless mobile phone circuit board, contain metals such as gold, silver, palladium, tin and copper, adopt the wet process to leach the process and extract these metals, must carry on crushing and grinding to IC chip and paster components and parts and process into the powder of certain granularity, the mobile phone IC chip is the integrated circuit formed after adding carbon black and silica flour encapsulation solidification by epoxy, it is plastic-based, paster components and parts are ceramic-based, two kinds of mechanical properties are totally different, can't mix together and break and grind, must classify and process, IC chip material not only contains plastic metal material but also contains the macromolecular material, it is more difficult to pulverize into the powder of certain granularity, it is vital to choose appropriate crushing and grinding mode and grinding equipment to leach the subsequent treatment. The method comprises the steps of carrying out primary crushing on an IC chip and a ceramic surface mount device, then putting the primarily crushed material into a ball mill to be ground into pulp, and grinding the IC chip and the ceramic surface mount device to 200 meshes.
In order to achieve the best crushing effect and simultaneously realize the control of process cost, 200g of IC chips and components are put into a high-speed universal crusher for crushing experiments, the crusher is intermittent operation equipment, the purpose of crushing is achieved by utilizing the high-speed rotation of a cross-shaped blade to collide with materials, the experiments of different crushing time from 1min to 8min are sequentially carried out on the raw materials, then a standard sieve with 20 meshes is used for sieving, the crushed materials under each crushing time are weighed to obtain the mass of the crushed materials, the requirement of the next ball grinding process on the feed granularity can be met when the mass percentage reaches 95%, the mass percentage of the raw materials passing through the standard sieve with 20 meshes is calculated, the best crushing time is determined, and the experiment results are as follows:
TABLE 1 relationship between crushing time and particle size of circuit board chip and component of waste mobile phone
| Serial number | Grinding time (min) | 20 mesh powder quality (g) | Percent by mass (%) |
| 1 | 1 | 98.6 | 49.3 |
| 2 | 2 | 130.8 | 65.4 |
| 3 | 3 | 170.0 | 85.0 |
| 4 | 4 | 180.7 | 90.35 |
| 5 | 5 | 192.2 | 96.1 |
| 6 | 6 | 192.4 | 96.2 |
| 7 | 7 | 192.8 | 96.4 |
| 8 | 8 | 192.0 | 96.0 |
As can be seen from Table 1, along with the extension of the crushing time, the mass percent of the powder passing through the 20-mesh standard sieve is larger and larger, the mass percent of the powder within 5min-8min is not changed greatly and is larger than 95%, the requirements of the next step of working procedure can be met, the process requirements can be met by crushing for 5min from the viewpoint of energy saving and economy, meanwhile, the crushing time is prolonged, so that the crusher can crush a large amount of heat energy, some non-metal particles and some metals with low melting points can be coked, and therefore the crushing time can be determined to be 5 min.
Adding the raw materials after the primary crushing into water to prepare slurry, grinding the crushed powder into slurry with the granularity of 200 meshes by adopting an upright ball mill, creating conditions for subsequent metal leaching extraction, and determining the experimental results of the time required by the slurry with the granularity of 200 meshes by adjusting the slurry concentration as follows:
TABLE 2 slurry concentration vs. grinding time relationship
| Serial number | Slurry concentration (%) | Grinding time (h) |
| 1 | 15 | 4 |
| 2 | 20 | 3 |
| 3 | 25 | 2 |
| 4 | 30 | 2.5 |
| 5 | 40 | 4.5 |
As can be seen from table 2, the higher the slurry concentration, the less the time required for polishing to 200 mesh, and the minimum time required for the slurry concentration to reach 25%, and the minimum value exists, and the polishing time becomes longer as the slurry concentration increases, so that the optimum slurry concentration at the time of polishing is determined to be 25%.
Third, determination of technological parameters of tin leaching process
The traditional treatment method is to leach copper, tin and other base metals in the waste water by nitric acid to enrich precious metals, thereby creating conditions for subsequent extraction, and the tin stripping process by nitric acid, ferric nitrate, high-temperature alkali liquor and the like is adopted, so that the nitric acid process efficiency is higher, but a large amount of nitrogen oxides are generated, the environmental pollution is serious, the high-temperature alkaline tin stripping process temperature is high, the energy consumption is large, the speed is slow, especially, the process contains organic oxidants such as anti-staining salts and nitrates, and the waste water is very difficult to treat;
the invention adopts sulfuric acid as an activating agent, adopts a replacement method to ionize metal tin, then filters the ionized metal tin to obtain filtrate containing tin and filter residue containing other metals to separate, and utilizes the hydrolysis precipitation property of tin ions to extract tin. Specifically, the chips and the components which are crushed and ball-milled are placed into tin immersion liquid for tin immersion treatment according to the solid-liquid ratio of 1: 3-7 (the unit of the solid-liquid ratio is g/L, the same applies below), the treatment temperature is 30-50 ℃, and the treatment time is 0.5-2 h; the tin immersion liquid is prepared from CuSO4Aqueous solution and H2SO4Mixing the aqueous solutions, and immersing in tin solution of CuSO4The concentration of the tin-dipping solution is 10-20g/L, and the acidity of the tin-dipping solution is 7% -12%; the tin leaching treatment process can reach more than 90 percent of tin leaching rate, and the filtrate containing tin ions and filter residue containing other metals are obtained by filtration and separation after the tin leaching treatment. Meanwhile, the invention carries out single-factor experiments, on the basis, the influence of the acidity of the tin immersion liquid, the solid-liquid ratio, the leaching temperature and the leaching time on the leaching rate of tin is inspected by adopting orthogonal experiments, and the appropriate leaching process conditions are determined as shown in the table 3.
TABLE 3 tin Leaching Process conditions
| Cu2+Concentration (g/L) | Acidity (%) | Solid-to-liquid ratio | Temperature (. degree.C.) | Time (h) | Leaching rate (%) |
| 15 | 10 | 1∶5 | 40 | 1 | 95 |
After the tin immersion treatment, the tin is Sn2+Is present in the filtrate containing tin ions due to Sn2+The ions are very unstable in the aqueous solution, and the stannous sulfate is easy to undergo hydrolysis reaction, so the invention continues to perform the following tin precipitation treatment: at normal temperature, adjusting the pH value of the tin leaching solution to 1.5-2.5 by using sulfuric acid, and then adding a proper oxidant into the solution to react Sn2+Oxidation to Sn4+Ions of Sn4+Ionic stannic acid, namely Sn (OH)4Precipitating in the form of precipitate, filtering to obtain Sn (OH)4The calculated recovery rate of the tin is as high as 98 percent; wherein the oxidizing agent is preferably hydrogen peroxide, and theoretically Sn2+Based on the molar amount of hydrogen peroxide added is theoretically Sn2+1.02 to 1.5 times of the molar amount of (A).
The invention determines the proper pH value in the tin precipitation treatment through experiments, screens proper oxidant, determines the addition amount of the oxidant, and uses the oxidant and Sn2+The molar ratio of (b) represents that suitable process conditions are shown in table 4.
TABLE 4 Process conditions for the hydrolytic precipitation of ions
Fourth, determining technological parameters of copper-silver leaching procedure
Adding the filter residue containing other metals obtained after the tin leaching extraction process into a mixed solution of sulfuric acid and sodium nitrate according to a solid-to-liquid ratio of 1: 3-7, wherein the concentration of the sodium nitrate is 5-10 g/L, the acidity of the mixed solution is 20% -30%, the temperature is controlled between 80-100 ℃, the time is 1-3 h, so that copper ions and silver ions are leached, then filtering is carried out to obtain filter residue containing gold and palladium and filtrate containing copper and silver, the leaching rate of copper is up to 95%, and the leaching rate of silver is up to 98%; then adding sodium chloride into the obtained filtrate containing copper and silver to precipitate silver, and then filtering and separating copper ions to obtain silver chloride precipitate and copper-containing filtrate, wherein the molar weight of the added sodium chloride is Ag+1.02-1.2 times of theoretical molar weight; adding a copper-containing filtrate into a copper precipitation agent to recover copper, wherein the copper precipitation agent is sodium sulfide or potassium sulfide, and the molar weight of the added sodium sulfide or potassium sulfide is Cu2+1.02 to 1.2 times of the theoretical molar weight. The acidity of sulfuric acid, solid-liquid ratio, leaching temperature, leaching time and theoretical excess coefficient of the catalyst are considered, and appropriate process parameters are determined as follows:
TABLE 5 Process conditions for copper silver leaching
| Solid-to-liquid ratio | Temperature (. degree.C.) | Time (h) | Copper leaching rate (%) | Silver leaching rate (%) |
| 1∶5 | 90 | 2 | 95 | 98 |
Cyanide-free leaching process and reduction process for gold and palladium
After tin, copper and other base metals and noble metal silver are removed from components and chips, filter residues containing gold and palladium are obtained, and the filter residues containing the gold and the palladium are leached out of gold and palladium by a cyanide-free chlorination gold leaching process, which specifically comprises the following steps: adding filter residues containing gold and palladium into cyanide-free leachate according to a solid-to-liquid ratio of 1: 3-7 to ionize gold and palladium to produce a liquid, wherein the temperature is 80-100 ℃, the leaching time is 1-3 h, the cyanide-free leachate takes water as a solvent, and the concentration of each component is as follows: h2SO480-120 g/L of sodium chlorate, 20-40 g/L of sodium chlorate and 3-7 g/L of hydrogen peroxide; then solid-liquid separation is carried out to obtain filtrate containing gold and palladium, the leaching rate of gold and palladium is up to 99 percent through detection, then a selective gold reducing agent is added into the filtrate containing gold and palladium, the reducing agent only reduces gold and does not reduce palladium, the gold and palladium in the liquid are reduced and separated through the method, and the gold and the filtrate containing palladium are obtained through separation after filtration; and replacing and recycling palladium ions in the palladium-containing filtrate by using zinc powder, and performing replacement and recycling at normal temperature for 1-3 hours, wherein the molar weight of the zinc powder is 1.1-1.5 times of the theoretical molar weight of palladium.
The invention adopts a chlorination method of sodium chlorate under the acidic condition to leach gold and palladium, and the most preferable proportion of cyanide-free leachate and the proper gold separation process conditions are determined through experiments as follows:
TABLE 6 gold leach liquor composition
TABLE 7 gold leach Process conditions
| Solid-to-liquid ratio | Temperature (. degree.C.) | Time (h) | Gold leaching rate (%) | Palladium leaching rate (%) |
| 1∶5 | 90 | 2 | 99 | 99 |
The reducing agent with proper reducing performance is selected, so that the influence of impurity elements in the solution on the quality of the gold powder caused by the fact that the impurity elements enter the gold powder can be effectively avoided. The purity requirement of the reducing agent is strict, and other impurities are avoided to the greatest extent. The commonly used reducing agents include oxalic acid, formaldehyde, sodium bisulfite, ferrous chloride, sodium sulfite, etc. Because the selectivity of oxalic acid is good, Pt and Pd in the solution are not easy to be reduced when the oxalic acid reduces gold; the rate of reducing gold by sodium sulfite is high, and the product purity is high; when sodium bisulfite reduces gold, gold powder is easy to precipitate. The three gold reducing agents have respective characteristics, oxalic acid, sodium sulfite and sodium bisulfite are selected as the gold reducing agents, and the used molar weight of the gold reducing agents is 1.5-2 times of the theoretical molar weight of gold.
TABLE 8 comparison of gold reduction with reducing agent
As can be seen from the table, the reduction with sodium sulfite and sodium bisulfite has low reduction temperature, short reduction time, complete reaction and the need of reducing gold at higher acidity; the reduction by oxalic acid is carried out at a higher temperature, the oxalic acid can selectively reduce the gold, and the purity of the reduced gold is high, thereby reaching the secondary standard of the national standard.
In order to verify the treatment effect of the process, the treatment effect of gold, silver, palladium, tin and copper in the leaching solution is tested by the leaching method, the content of metals in the leaching solution is detected by a quality supervision and inspection center of products in south China, the nonferrous metal industry of the third-party detection institution, the residual quantity of the five metals in the waste liquid after the five metals are extracted is detected, and the recovery rate of the target metal is calculated as follows:
table 9 extraction rates of five metals in chips and components of circuit boards of waste mobile phones
As can be seen from Table 9, the method adopts low-toxicity and environment-friendly leaching agents, selectively leaches tin, copper, silver and gold palladium by a step method, and then respectively performs reduction extraction, so that the recovery rates of gold, silver and palladium can reach more than 98 percent.
Gold stripping process for light plate
Gold in the light plate of the waste mobile phone circuit board is attached to a copper-nickel metal base material by electroplating or chemical plating, the traditional treatment method is to enrich the metal by burning, and then use nitric acid, aqua regia and cyanide to soak the gold to cause huge environmental pollution, the invention adopts an oxidant and a complexing agent to dissolve copper and nickel under the gold plating layer, and strip the gold plating layer, so that the gold with the most recovery value is obtainedFirstly, the gold stripping agent is recovered, the gold stripping agent uses water as a solvent, and Cu (NH) in the gold stripping agent3)2The concentration of Cl is 0.5-1.5 mol/L, NH3The concentration is 0.5-1.5 mol/L, the gold stripping agent can slightly dissolve base metal on the bottom layer, the gold stripping treatment temperature is 20-40 ℃, the time is 2-4 hours, then the gold foil is filtered and enriched to directly obtain the gold foil, the treatment process is simple, the reaction condition is mild, and the gold foil is directly smelted after being dried to obtain the gold ingot. The experimental determination of suitable process conditions is as follows:
TABLE 10 gold stripping Process conditions
| Temperature (. degree.C.) | Extraction time (h) | Recovery (%) |
| 30 | 3.0 | 98 |
After gold stripping treatment, the bare board without the gold coating is sent to a physical crushing and sorting production line for physical crushing and sorting, the bare board of the circuit board is sorted into metal copper powder and resin powder, and the metal copper powder can be mixed with crushed metal powder of chips and components and then recycled.
In the field of waste circuit board recovery, compared with the main technical route at home and abroad, the invention has the following main technical and economic indexes:
TABLE 11 technical economic indicators analysis
As can be seen from the comparison in Table 11, the total treatment cost, in terms of chemical consumption, waste treatment cost, equipment cost and the like, of the present invention is reduced compared with the conventional incineration acid cleaning or aqua regia/cyanide treatment method, and the present invention does not generate highly toxic waste gas or waste water, the method has small environmental pollution, and the recovery efficiency of the noble metal reaches 98 percent, therefore, each process unit of the method does not generate pollutants such as nitrogen oxide, sulfur dioxide and the like which are strictly controlled by the country in total amount, reduces the environmental pollution from the source, and the leaching and extraction waste liquid of each process unit can be recycled through simple treatment, the reuse rate of clear water is improved, the waste water discharge is reduced, the waste water does not contain complex organic matters and ammonia nitrogen, the waste water can be discharged up to the standard through simple treatment, and the environment-friendly disposal cost is reduced.
Finally, it should be noted that: the above embodiments are merely illustrative and not restrictive of the technical solutions of the present invention, and any equivalent substitutions and modifications or partial substitutions made without departing from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.
Claims (8)
1. A wet harmless extraction process of metal in a waste mobile phone circuit board is characterized by comprising the following steps:
firstly, disassembling: firstly, disassembling a waste mobile phone circuit board into a chip, a chip component and a light panel;
second, processing of chip and chip components
1) Crushing: crushing the chip and the surface mount device to prepare powder, and sorting to obtain metal powder;
2) tin leaching process
(a1) Adding the metal powder obtained in the step 1) into a tin immersion liquid for tin immersion treatment to ionize metal tin, and then filtering to obtain a solution containing tin ions and filter residues containing other metals;
wherein the tin immersion liquid is prepared from CuSO4Aqueous solution and H2SO4Mixing the aqueous solutions, and immersing in tin solution of CuSO4The concentration of (A) is 10-20g/L, and the acidity of the tin immersion liquid7 to 12 percent;
(a2) adjusting the pH value of the solution containing tin ions obtained in the step (a1) to 1.5-2.5, and adding an oxidant to the solution to form Sn (OH) as tin ions4Precipitating in the form of (1), and filtering again to obtain tin;
wherein the oxidant is hydrogen peroxide and the molar amount of the oxidant added is theoretically Sn2+1.02 to 1.5 times of the molar weight of (A);
3) copper silver leaching process
(b1) Adding the filter residue containing other metals obtained in the step (a1) into a mixed solution of sulfuric acid and sodium nitrate to leach copper ions and silver ions, and then filtering to obtain filter residue containing gold and palladium and filtrate containing copper and silver;
wherein the concentration of the sodium nitrate is 5-10 g/L, and the acidity of the mixed solution of the sulfuric acid and the sodium nitrate is 20-30%;
(b2) adding sodium chloride into the filtrate containing copper and silver obtained in the step (b1) to obtain silver chloride precipitate, and filtering and separating to obtain silver and copper-containing filtrate;
wherein the molar weight of the added sodium chloride is Ag+1.02-1.2 times of theoretical molar weight;
(b3) adding a copper precipitation agent into the copper-containing filtrate obtained in the step (b2), and separating to obtain copper;
wherein the copper precipitation agent is sodium sulfide or potassium sulfide, and the molar weight of the added sodium sulfide or potassium sulfide is Cu2+1.02-1.2 times of theoretical molar weight;
4) gold palladium cyanide-free leaching procedure
(c1) Adding cyanide-free leaching solution into the filter residue containing gold and palladium obtained in the step (b1) to leach out gold ions and palladium ions, then adding a gold reducing agent to reduce the gold ions, and filtering and separating to obtain gold and palladium ion-containing filtrate;
the cyanide-free leaching solution takes water as a solvent, wherein the concentration of each component is as follows: h2SO480-120 g/L of sodium chlorate, 20-40 g/L of sodium chlorate and 3-7 g/L of hydrogen peroxide;
the gold reducing agent is oxalic acid, sodium sulfite or sodium bisulfite;
(c2) adding zinc powder into the filtrate containing palladium ions obtained in the step (c1), and performing displacement reduction to obtain palladium;
three, light plate stripping process
1) Dissolving copper and nickel parts under the gold plating layer by adopting a gold stripping agent, stripping the gold plating layer and filtering to obtain gold;
wherein the gold stripping agent takes water as a solvent, and Cu (NH) in the gold stripping agent3)2The concentration of Cl is 0.5-1.5 mol/L, NH3The concentration is 0.5 to 1.5 mol/L.
2. The wet harmless extraction process of metals in the waste mobile phone circuit board according to claim 1, characterized in that in step two 1), the specific operation of crushing is as follows: firstly, the chip and the chip component are crushed by a crusher and then ball-milled to 200 meshes.
3. The wet harmless extraction process of metals in waste mobile phone circuit boards according to claim 1, wherein in the step two 2) (a1), the specific operating conditions of the tin immersion treatment are as follows: and (3) carrying out tin immersion treatment for 0.5-2 h at the temperature of 30-50 ℃.
4. The wet harmless extraction process of metals in the waste mobile phone circuit board according to claim 1, wherein in the second step 3) (b1), the temperature for leaching copper ions and silver ions is 80-100 ℃, and the leaching time is 1-3 h.
5. The wet harmless extraction process of metals in waste mobile phone circuit boards as claimed in claim 1, wherein in the step two 4) (c1), the temperature for leaching gold ions and palladium ions is 80-100 ℃, and the leaching time is 1-3 h.
6. The wet harmless extraction process of metals in the waste mobile phone circuit board according to claim 1, characterized in that in the step three 1), the temperature for stripping the gold coating is 20-40 ℃ and the time is 2-4 h.
7. The wet harmless extraction process of metals in the waste mobile phone circuit board according to claim 1, characterized in that in the step three 1), the residual light board after gold stripping is physically separated to obtain copper powder and resin powder.
8. The wet harmless extraction process of metals in the waste mobile phone circuit board as claimed in claim 7, wherein the copper powder and the metal powder are mixed and then treated synchronously.
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Application publication date: 20200519 |