CN113528817A

CN113528817A - A method for combined removal of impurities from waste circuit board copper powder selection and smelting

Info

Publication number: CN113528817A
Application number: CN202110842172.3A
Authority: CN
Inventors: 刘伟锋; 孙百奇; 陈霖; 张杜超; 杨天足; 胡晓丽
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2021-07-26
Filing date: 2021-07-26
Publication date: 2021-10-22
Anticipated expiration: 2041-07-26
Also published as: CN113528817B

Abstract

The invention relates to a method for the combined removal of impurities from waste circuit board copper powder selection and smelting. The waste circuit board copper powder is leached in a hydrochloric acid solution, so that aluminum and iron in the waste circuit board are selectively leached. The leaching residue adopts hydrocyclone separation method to separate alumina and silica to produce high-quality pyrometallurgical copper raw materials. The essence of the present invention is to first use a two-stage wet selective leaching process combined with beneficiation and sorting to treat waste circuit board copper powder, which not only selectively removes aluminum, lead, tin and other impurity metals, but also separates the oxidized copper powder in it. Aluminum and silicon dioxide, and finally realize the enrichment of copper, which solves the harm of impurity metals and organic substances when the copper powder of waste circuit boards is recovered by pyro-smelting.

Description

Method for removing impurities from waste circuit board copper powder through combination of sorting and smelting

Technical Field

The invention relates to a hydrometallurgy process in the field of nonferrous metallurgy, in particular to a hydrometallurgy method for treating waste circuit board copper powder by adopting a combination method of concentration and metallurgy.

Background

In recent years, people have been unable to keep their production and life away from electronic and electric appliances. With the development of the Electronic industry, the progress of technology and the expansion of market, the upgrading speed of Electronic and Electric Equipment is accelerated, resulting in the use time of the Electronic and Electric Equipment being far shorter than the actual service life of the product, which makes the Waste Electronic and Electric Equipment (WEEE) rapidly increase (RAHMANI M, NABIZADEH R, YAGHMAEIAN K, MAHVI A H, YUNFESIAN M. evaluation of Waste computer computers and mobile telephones in Iran [ J ] Resources, collocation and Recycling 2014, 87: 21-29.). WEEE presents a significant Environmental problem and has become one of the major sources of municipal solid Waste (WANG Jan-bo, XU ZHEN-ming, dispensing and Recycling wall Printed Circuit Boards: dispensing, Resource Recovery, and Pollution Control [ J ]. Environmental Science & Technology, 2015, 49(2): 721 733.). China enters the peak period of electronic product scrapping, the theoretical scrapping amount per year exceeds 5000 thousands of electronic products, and the electronic products are increased by 20% every year. WEEE has complex components, and on one hand, the WEEE contains various valuable metal components and is an important urban mineral resource; on the other hand, it contains many toxic and harmful substances, which may cause harm to the environment and human health if not handled properly. Therefore, the development of an environment-friendly WEEE recycling technology is urgent.

The circuit board is the foundation of the electronic industry and is an important component of all electronic and electrical equipment. In recent years, the annual growth rate of the circuit board industry in the world is 8.7%, and the growth rate of the circuit board manufacturing industry in China is as high as 14.4% (LI Huan, EKSTEEN J, ORABY E. Hydrometallurgical recovery of metals from Waste Printed Circuits (WPCBs): Current states and perspectives-A review [ J ] Resources, registration and Recycling, 2018, 139: 122-. The amount of circuit Boards produced in China is up to 15 ten thousand tons per year, and The amount of Waste Printed circuit Boards (Waste Printed Circuit Boards, WPCBs) to be treated is more than 50 ten thousand tons per year (XIA Ming-chen, WANG Ya-ping, PENG Tang-jian, ZHOU Hong-bo, LIU Xue-rui, JIANG Tao, QIU Guan-ZHOU, ZENG Wei-min. Parameter optimization during micro-biological testing and separated from Printed circuit Boards [ J ] The Chinese chain Journal of non-magnetic Metals 2016, 26(04): 928 935.).

WPCBs have the characteristics of high growth speed, high utilization value and great environmental hazard. WPCBs mainly comprise resin and glass fiber and contain a large amount of metals, such as copper, iron, tin, gold, palladium, silver and the like, wherein the grade of the metals in the WPCBs is tens of times of that of common ores (HE connecting-feeding, DUAN Chen-long. Recovery of metallic concentrations from Waste formulated ores, video conversion [ J ]. Waste Management, 2017, 60: 618-; meanwhile, the paint contains various heavy metals and toxic and harmful substances, such as lead, cadmium, mercury, hexavalent chromium, polyvinyl chloride, halide flame retardant and the like, and the improper treatment can cause great influence on the environment and human health. Therefore, research on the aspect of WPCBs recycling is carried out, so that the WPCBs are subjected to resource and harmless treatment, and the method has important significance for promoting human sustainable development.

The WPCBs resource utilization technology mainly comprises mechanical treatment, pyrogenic treatment and wet treatment. The mechanical treatment technology is the most extensive method for recycling WPCBs, and mainly comprises the processes of disassembling, crushing, sorting and the like. Because the circuit board contains multiple electronic components, they have very big difference with the base plate in composition and structure, consequently often with electronic component disassemble back independent processing, at present, disassemble mainly by the manual work and accomplish, but along with WPCBs's increase in quantity, automatic disassembling technique is more and more paid attention to, and it is the key that realizes automatic disassembling to utilize heating device to melt the solder and make electronic component break away from. The crushing degree of circuit board is directly influencing the separation effect of metal and nonmetal, and this makes the breakage become the key link of whole mechanical treatment flow, because WPCBs comprises multilayer glass fiber cloth, reinforced resin and copper foil, has very high hardness and toughness, and traditional breaker can't obtain good effect, adopts the crushing equipment that has shearing, cutting effect can reach better effect.

The sorting method mainly utilizes the difference of physical properties of materials in the WPCBs, such as magnetism, electric property, density, shape and the like, and separates metal and nonmetal in the WPCBs by means of gravity sorting, magnetoelectric sorting and the like. Mechanical treatment is often used as a pretreatment for other treatment processes because separation of the metal components cannot be achieved. The WPCBs are subjected to mechanical treatment to obtain metal-rich multi-metal powder and non-metal powder, wherein the recovery value of the multi-metal powder is higher, and the multi-metal powder is also called waste circuit board copper powder because the copper content is highest.

The method for recovering the copper powder of the waste circuit board comprises a wet method treatment process and a fire method treatment process, wherein the wet method treatment process mainly aims at recovering copper and precious metals in the copper powder of the waste circuit board, leaching is the most critical step, and wet method treatment is divided into an acid leaching method, a cyaniding method and a non-cyaniding method due to different leaching agents. The acid leaching method is that waste circuit board copper powder is treated by strong acid and strong oxidizer to strip noble metal in the waste circuit board copper powder for precipitation, other valuable metals such as copper are dissolved in acid, the precipitate is treated by nitric acid, aqua regia and the like to recover the noble metal in the waste circuit board copper powder, and the copper-containing acid solution is purified, electrolyzed and the like to obtain electrolytic copper.

The cyanidation method is mainly used for recovering gold and silver in the waste circuit board copper powder, but because the copper content in the waste circuit board copper powder is very high, a large amount of copper is dissolved in the leaching process, and the leaching rate of noble metals is reduced. Since the effect of cyanide on the environment and humans is being of great public concern, research into selective leaching of waste circuit board copper powder using non-cyanide leachants has received considerable attention, and the thiourea and thiosulfate methods are considered to be the most promising alternative to cyanidation (BIRLOAGA L, VEGLIO f. Study of multi-step hydraulic methods to extract the valid contents of gold, silver and copper from waste road printed circuit boards [ J ]. Journal of Environmental Chemical Engineering, 2016, 4(1): 20-29.).

Because the copper content in the waste circuit board copper powder is higher and can reach about 50 percent, the large-scale recovery of the waste circuit board copper powder in the world is usually carried out in a large-scale pyrometallurgical copper smelting plant at present. In the pyrometallurgical copper smelting process, metals such as tin, lead, zinc, aluminum and the like in the waste circuit board copper powder can be dispersed into slag, flue gas and copper matte, so that the recovery rate of copper is reduced, the quality of cathode copper is influenced, and the stability of a copper smelting system is influenced. At present, the research on the separation and recovery of these metals is relatively rare, and these valuable metal resources are wasted because the copper powder is often removed as impurity metal in the process of recovering the waste circuit board copper powder. In addition, the substrate of the Waste circuit board contains a large amount of organic matters, and part of metals are still wrapped by organic matters such as epoxy resin, fire retardant and the like due to insufficient dissociation in the mechanical pretreatment process, so that toxic and harmful gases such as dibenzodioxin, dibenzofuran and the like can be generated in the melting process, and the environment is greatly polluted (PENG Ya-qi, CHEN J-hao, LU Sheng-yong, HUANG Jian-xin, ZHANG Meng-mei, EKBUENS A, LI XIAO-dong, YAN Jian-hua, Chlorophenol in Multi Solid Circuit Inc: A review [ J ] Chemical Engineering Journal, 2016, 292: 398-.

Disclosure of Invention

In order to overcome the defects of the traditional treatment method of the waste circuit board copper powder, the invention provides a hydrometallurgy method for treating the waste circuit board copper powder by adopting a selection and metallurgy combined mode of combining acid potential-controlled selective oxidation leaching and hydraulic cyclone separation, and the hydrometallurgy method has the advantages of high lead-tin recovery rate, good separation effect of copper concentrates and silicon dioxide and aluminum oxide, low cost and small environmental pollution.

In order to achieve the aim, the technical scheme adopted by the invention is that the waste circuit board copper powder is leached in an acid system, so that aluminum enters a solution in the form of aluminum chloride, and the primary separation of aluminum in the raw materials is realized; leaching the dealuminized slag by using a potential-control selective oxidation leaching method to realize leaching of lead and tin; and separating the leached slag of lead and tin by using a hydrocyclone to produce mixed slag of alumina and silicon dioxide. The essence of the invention is that firstly, a process combining two-stage wet selective leaching and mineral separation is adopted to realize the step-by-step removal of the copper powder impurities of the waste circuit board, the processes are closely related, and the single process can not achieve the expected effect of the combined removal of the impurities in the copper powder of the waste circuit board.

The specific technological process and parameters are as follows:

1 hydrochloric acid leach

Leaching waste circuit board copper powder in a hydrochloric acid solution; preparing hydrochloric acid solution with the molar concentration of 0.5-2.0mol/L, adding waste circuit board copper powder according to the liquid-solid ratio (the ratio of the volume L of the solution to the weight Kg of solid) of 2-8: 1, controlling the temperature to be 30-90 ℃, reacting for 1-4 hours, cooling to room temperature after the reaction is finished, realizing solid-liquid separation by adopting a vacuum filtration mode, recovering aluminum from the leaching solution, sending the leaching residue of the hydrochloric acid to a subsequent potential-controlled oxidation leaching process, wherein the main chemical reaction generated in the leaching process of the hydrochloric acid is as follows:

2Al+6HCl=2AlCl₃+3H₂ （1）

2 controlled potential oxidation leaching

Adding hydrogen peroxide into hydrochloric acid to control potential for oxidizing leaching of hydrochloric acid leaching residue; preparing hydrochloric acid solution with the molar concentration of 1.0-4.0mol/L, adding hydrochloric acid leaching slag according to the liquid-solid ratio (the ratio of the volume L of the solution to the weight Kg of solid) of 2-8: 1, controlling the reaction temperature to be 30-80 ℃, adding hydrogen peroxide at the speed of 1.0-5.0mL/min, continuing to react for 1-3h when the potential value of the solution is maintained at-100 and 100mV, filtering while hot after the reaction is finished, realizing solid-liquid separation by adopting a vacuum filtration mode, recovering lead and tin from the leaching solution, sending the oxidized leaching slag to a subsequent hydrocyclone for separation treatment, wherein the chemical reaction formula mainly generated in the potential-controlled oxidation leaching process is as follows:

Pb+2HCl+H₂O₂=PbCl₂+2H₂O （2）

Sn+2HCl+H₂O₂=SnCl₂+2H₂O （3）

3 hydrocyclone separation

Separating impurity substances from the oxidized leaching residues in a hydrocyclone; grinding the oxidation leaching slag to the granularity of 0.074-5mm, pulping with water, introducing into a hydrocyclone for separation, controlling the feeding pressure to be 0.2-1.0MPa and the feeding concentration to be 2-10%, allowing the copper concentrate to enter underflow and the mixture containing alumina, silicon dioxide and organic matters to enter overflow.

The invention is suitable for treating waste circuit board copper powder produced in the process of crushing and sorting waste circuit boards, and the ranges of the main components are (%): cu40.0-80.0%, Al1.0-10.0%, Sn4.0-18.0%, Pb4.0-18.0%, Au 10-200 g/t and Ag 500-2000 g/t.

Compared with the traditional pretreatment method of the waste circuit board multi-metal powder, the method has the following advantages: 1. according to the invention, the waste circuit board copper powder is treated by adopting a wet pretreatment mode combining hydrochloric acid leaching and potential-controlled oxidation leaching, aluminum, lead and tin in the waste circuit board copper powder are effectively removed, and the leaching residue is subjected to organic matter and glass fiber removal by adopting a hydrocyclone, so that a high-quality raw material is provided for pyrometallurgical copper smelting; 2. the method comprises the following steps of leaching in a hydrochloric acid solution to realize high-efficiency removal of aluminum in the copper powder of the waste circuit board, wherein the removal rate of the aluminum reaches more than 97.0%; 3. selectively leaching lead and tin in the dealuminized slag by controlling potential oxidation leaching, wherein the leaching rates respectively reach more than 91.1 percent and 94.7 percent; 4. separating alumina and silica components in the oxidized leaching slag from the copper concentrate by adopting a hydrocyclone to realize high enrichment of copper; 5. the invention has the advantages of stable technical indexes of the process, low labor intensity, low production cost and the like.

Drawings

FIG. 1: the invention is a process flow diagram.

The specific implementation mode is as follows:

example 1:

the waste circuit board copper powder produced in the process of crushing and sorting waste circuit boards of certain enterprises in China comprises the following main components in percentage by mass: cu44.6, Al2.5, Sn9.2, Pb5.1, Au20g/t and Ag700 g/t. The hydrochloric acid and the hydrogen peroxide are analytical pure grade reagents, wherein the mass percentage of the hydrochloric acid is not less than 36.0%, and the mass percentage of the hydrogen peroxide is not less than 30%.

Preparing a hydrochloric acid solution with the molar concentration of 1.5mol/L, adding waste circuit board copper powder according to the liquid-solid ratio (the ratio of the volume L of the solution to the weight Kg of the solid) of 5:1, heating and stirring the waste circuit board copper powder by using a constant-temperature magnetic stirring water bath, controlling the reaction temperature to be 80 ℃, reacting for 2 hours, cooling the solution to room temperature after the reaction is finished, and filtering the solution, wherein the leaching rate of aluminum is more than 97.0 percent; preparing a hydrochloric acid solution with a molar concentration of 3mol/L according to a liquid-solid ratio (the ratio of the volume L of the solution to the weight Kg of the solid) of 5:1, adding the dealuminized slag, controlling the reaction temperature to be 70 ℃, adding hydrogen peroxide at the speed of 1.0mL/min, controlling the potential value of the solution to be 48mV in the reaction process, reacting for 1h, filtering while the solution is hot after the reaction is finished, and obtaining oxidized leaching slag, wherein the leaching rates of lead and tin respectively reach more than 91.1 percent and 94.7 percent; controlling the granularity of the oxidized leaching slag to be 0.074-1 mm, pulping by using water, then conveying the pulped oxidized leaching slag into a hydraulic cyclone for separation, controlling the ore feeding pressure to be 0.4MPa and the ore feeding concentration to be 8%, wherein in the separation process, copper concentrate enters underflow, and a mixture of alumina and silica enters overflow.

Claims

1. A method for removing impurities from waste circuit board copper powder in a selective smelting combined mode is characterized by comprising the following steps:

(1) hydrochloric acid leaching

Preparing a hydrochloric acid solution with the molar concentration of 0.5-2.0mol/L, adding waste circuit board copper powder according to the liquid-solid ratio, namely the ratio of the volume L of the solution to the weight Kg of solid, which is 2-8: 1, controlling the temperature to be 30-90 ℃, reacting for 1-4 hours, cooling to room temperature after the reaction is finished, realizing solid-liquid separation by adopting a vacuum filtration mode, recovering aluminum from a leaching solution, and sending hydrochloric acid leaching residues to a subsequent potential-controlled oxidation leaching process;

(2) controlled potential oxidative leaching

Preparing hydrochloric acid solution with the molar concentration of 1.0-4.0mol/L, adding hydrochloric acid leaching slag according to a liquid-solid ratio, namely the ratio of the volume L of the solution to the weight Kg of solid is 2-8: 1, controlling the reaction temperature to be 30-80 ℃, adding hydrogen peroxide at the speed of 1.0-5.0mL/min, continuing to react for 1-3h when the potential value of the solution is maintained at-100 and 100mV, filtering while hot after the reaction is finished, realizing solid-liquid separation by adopting a vacuum filtration mode, recovering lead and tin from the leaching solution, and sending the oxidized leaching slag to a subsequent hydrocyclone for separation treatment;

(3) hydrocyclone separation

Grinding the oxidation leaching slag to the granularity of 0.074-5mm, pulping with water, introducing into a hydrocyclone for separation, controlling the feeding pressure to be 0.2-1.0MPa and the feeding concentration to be 2-10%, allowing the copper concentrate to enter underflow and the mixture containing alumina, silicon dioxide and organic matters to enter overflow.