A method for purifying electroplating grade copper sulfate pentahydrate based on smelting by-product copper sulfate

Abstract

The application discloses a method for purifying electroplating grade copper sulfate pentahydrate based on smelting by-product copper sulfate, and belongs to the technical field of copper salt production processes. 2+ As 3+ Then, iron sulfate solution is added to provide an iron source, flocculent iron hydroxide is formed to simultaneously settle arsenate and iron ions, and after vacuum filtration, evaporation concentration, and cooling crystallization, coarse crystals are obtained; then, the coarse crystals are dissolved and selectively adsorbed through a weak acid cation exchange resin column; finally, high-purity copper sulfate desorption solution is obtained by using dilute sulfuric acid for countercurrent desorption, and after vacuum evaporation concentration and cooling crystallization of the desorption solution, electroplating grade copper sulfate pentahydrate is purified; the combined purification process of the electroplating grade copper sulfate pentahydrate can effectively avoid the introduction of sodium ion impurities, realizes targeted removal of arsenic, iron, nickel and zinc impurities, and realizes closed-loop recycling of liquid materials by recycling the crystallization mother liquor and condensate water to the front-end dissolving process, thereby significantly improving the purity of the copper sulfate pentahydrate product.

Description

Technical Field

[0001] This invention belongs to the field of copper salt production technology, specifically relating to a method for purifying electroplating-grade copper sulfate pentahydrate based on copper sulfate byproducts of smelting. Background Technology

[0002] Copper sulfate pentahydrate (CuSO4·5H2O) is an important inorganic chemical fine product widely used in electroplating, electronics, pharmaceuticals, pesticides, feed additives, and many other fields. Electroplating-grade copper sulfate pentahydrate, as a core raw material in the electroplating industry, directly determines the density, uniformity, and adhesion of the coating, and has a decisive impact on the performance of end products such as printed circuit board (PCB) manufacturing and semiconductor electroplating. Currently, the conventional industrial processes for preparing electroplating-grade copper sulfate pentahydrate mainly include the copper hydroxide intermediate method, the copper oxide intermediate method, and the technical route of preparing basic copper chloride from copper-containing etching waste liquid and then converting it into copper sulfate. However, these traditional processes generally suffer from technical defects such as complex ammonia treatment processes, large amounts of production wastewater, lengthy process flows, high energy consumption, and poor cost controllability.

[0003] In recent years, with increasingly stringent environmental regulations and the widespread adoption of the concept of resource recycling, the efficient resource utilization of copper-containing by-products has become a research hotspot in the copper metallurgy and fine chemical industries. Among these, copper sulfate, a major by-product of smelting and electrolytic copper production, has a high copper content but a complex composition. Arsenic and iron are the main associated impurities, along with heavy metals such as nickel and zinc. The difficulty in removing these impurities means its purity cannot meet the stringent requirements of electroplating-grade products, limiting its use to low-value-added applications. This results in inefficient utilization and waste of copper resources, contradicting the concept of a green circular economy.

[0004] Currently, the process of preparing high-purity electroplating-grade copper sulfate pentahydrate from copper sulfate by-products of smelting still faces many prominent technical bottlenecks. The removal of impurities is incomplete, making it difficult to effectively remove trace harmful impurities from the system. The process also easily introduces impurities such as sodium ions, which seriously affect the purity of the product and its subsequent application performance. Moreover, product purity and raw material yield are mutually restrictive, making it difficult to achieve a balance between the two and thus hindering high-efficiency production. At the same time, existing processes generally suffer from problems such as cumbersome procedures, high energy consumption, and large pollutant emissions, which are not conducive to production cost control and environmental compliance.

[0005] In recent years, some progress has been made in the industrialization of methods for preparing high-purity electroplating-grade copper sulfate pentahydrate. For example, Chinese Patent No. CN117342603A, filed on September 25, 2023, discloses a method for preparing electroplating-grade copper sulfate pentahydrate. This method uses industrial-grade basic copper chloride as raw material. First, fine materials are screened out and slurried with water. Then, NaOH solution is added, and the reaction is stirred for 1 to 3 hours under conditions of pH 11-13 and temperature 60-80℃. Crude copper oxide is filtered out and washed with water four times to obtain a copper oxide intermediate. Subsequently, the copper oxide intermediate is added to water or copper sulfate mother liquor to make a slurry, and then concentrated sulfuric acid is added for acidification. The pH of the reaction endpoint is controlled at 1.6-2.2. After oxidation to remove impurities and hot filtration, the filtrate is cooled and crystallized to filter out crude copper sulfate. Then, the product undergoes washing, drying, and sieving to finally obtain electroplating-grade copper sulfate pentahydrate. However, the reaction conditions in the preparation stage of copper oxide intermediates were not fully optimized, resulting in low intermediate yield and insufficient purity, which in turn affected the quality stability of subsequent products. Furthermore, the process was lengthy and the washing process was complicated, leading to high energy consumption and wastewater discharge, which made it difficult to meet the needs of efficient and clean industrial production.

[0006] Chinese Patent Publication No. CN107986317A, filed on November 16, 2017, discloses a method for preparing electroplating-grade copper sulfate. This method uses acidic copper wastewater as raw material. First, chelating anion resin is used to adsorb organic matter in the acidic copper wastewater. Then, selective copper ion cation resin is used to adsorb copper ions in the wastewater until the resin is saturated. Subsequently, sulfuric acid with a concentration of 5-20% (v / v) is added to desorb and regenerate the saturated resin, yielding Cu. 2+ A concentrated copper sulfate solution with a concentration of 20-50 g / L and a pH of 0-1.5 is prepared. 1-10 ml / L of hydrogen peroxide is added to this concentrated solution, and the solution is heated at a constant temperature of 50-70℃ for 4-6 hours with forced air circulation. After cooling to room temperature, weak electrolysis is performed for 12-24 hours. This is followed by continuous filtration using activated carbon and cotton filters for at least 24 hours. The pH of the solution is then adjusted to ≥2.5 using copper oxide, basic copper carbonate, or copper hydroxide. Finally, the solution is evaporated to 15-20% of its original volume in a vacuum evaporation crystallizer. After cooling in a solid-liquid separator, copper sulfate crystal particles are obtained. However, this method involves time-consuming weak electrolysis and filtration processes, and the process parameters need optimization. This results in low production efficiency, and the impurity removal effect is insufficient to meet the stringent requirements of high-purity electroplating products.

[0007] In summary, traditional methods for preparing electroplating-grade copper sulfate pentahydrate lack targeted impurity removal capabilities, failing to effectively remove major impurities such as arsenic and iron, as well as heavy metals like nickel and zinc, and organic impurities from the copper sulfate solution. This results in low product purity, limiting its application to low-value-added sectors and leading to inefficient utilization of copper resources. Existing improved processes often employ sodium-containing alkaline solutions to adjust the pH, easily introducing sodium ion impurities that further reduce the purity and subsequent performance of the electroplating-grade copper sulfate. This fails to meet the stringent quality standards of downstream electroplating industries, and there is a clear trade-off between product purity and raw material yield, making it difficult to achieve both high purity and high yield simultaneously. This results in low production efficiency and hinders large-scale industrial application. Furthermore, current processes for preparing electroplating-grade copper sulfate pentahydrate are poorly designed, with lengthy, cumbersome, and poorly integrated steps, leading to high energy consumption and significant pollutant emissions. This not only increases production costs but also exacerbates the environmental burden, failing to meet the requirements of green and low-carbon industrial production development.

[0008] Therefore, there is an urgent need to develop a new, efficient, clean, and economical preparation process to achieve the efficient recycling of copper sulfate resources, a byproduct of smelting, to solve various defects in existing technologies, to ensure a stable supply of high-quality raw materials for the downstream electroplating industry, to reduce energy consumption and pollutant emissions, to increase the overall added value of the copper industry chain, and to meet the requirements of green, low-carbon, and circular economic development. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention discloses a method for purifying electroplating-grade copper sulfate pentahydrate based on copper sulfate by-products from smelting. The method employs a combined purification process of oxidation-neutralization-ion exchange adsorption-recrystallization, which selectively removes core impurities such as arsenic and iron from copper sulfate by-products from smelting through multiple steps, while simultaneously removing trace impurities such as nickel and zinc. This solves the problem of incomplete impurity removal in traditional methods and achieves the preparation of high-purity electroplating-grade copper sulfate pentahydrate.

[0010] The technical solution of the present invention is as follows: The purpose of this invention is to provide a method for the combined purification of electroplating-grade copper sulfate pentahydrate based on copper sulfate by-products from smelting, comprising the following steps: S1. Prepare crude copper sulfate solution with a copper content of 60-90 g / L using copper sulfate, a by-product of smelting, as raw material; S2. Add 20-40% hydrogen peroxide to the crude copper sulfate solution at a mass ratio of 1:50-200, and stir and oxidize at 30-70℃ for 0.5-1h. S3. Add ferric sulfate solution to the oxidized solution in S2 at a dosage of 0.2-1.2 mL / L. After flocculent ferric hydroxide is formed, adjust the pH of the solution to 3.5-4.0 using a sodium-free pH adjuster. Stir the reaction for 0.5-1 h and then let it stand for 0.5 h to settle. S4. Vacuum filtration is used to remove the precipitate obtained in S3, and the copper sulfate filtrate is obtained. The pH of the filtrate is adjusted to 1-2 with sulfuric acid, and the solution is concentrated by vacuum evaporation to a density of 1.2-1.6 g / ml. The solution is then cooled to 15-35℃ for crystallization. S5. Filter to obtain crude copper sulfate crystals, prepare them into an adsorption solution with a copper ion concentration of 60-90 g / L and heat to 50-80℃, and use a weak acid cation exchange resin column for selective adsorption. S6. Use 10-30% dilute sulfuric acid to flow through the weak acid cation exchange resin column after adsorption for countercurrent desorption to obtain high-purity copper sulfate desorption solution. Vacuum evaporate and concentrate the desorption solution to a solution density of 1.2-1.6 g / ml, cool to 15-35℃ for crystallization to obtain electroplating grade copper sulfate pentahydrate.

[0011] Furthermore, in step S1, copper sulfate raw material, a byproduct of smelting, is placed in a reaction vessel, and ultrapure water is added and stirred at a speed of 200-400 rpm to prepare crude copper sulfate solution.

[0012] Further, in step S2, hydrogen peroxide is slowly added to the crude copper sulfate solution in the reactor, and the mixture is stirred at 200-400 rpm for 0.5-1 h. This oxidizes ferrous ions to ferric ions and trivalent arsenic to pentavalent arsenic, improving the subsequent precipitate removal effect and yielding an oxidized solution.

[0013] Furthermore, the concentration of the ferric sulfate solution in S3 is 5-10 g / L. The ferric sulfate solution provides an iron source for the co-precipitation of arsenic and iron impurities, forming flocculent ferric hydroxide to simultaneously precipitate arsenate and iron ions, thereby improving the impurity removal effect. Furthermore, the sodium-free pH adjuster in S3 is any one of copper oxide, copper hydroxide, or basic copper carbonate, and the stirring speed is 200-400 rpm. Furthermore, the filtration pressure in S4 is -0.04 to -0.02 MPa.

[0014] Furthermore, sulfuric acid was used to adjust the pH of the filtered copper sulfate solution to 1-2 to inhibit hydrolysis, and the mixture was stirred at a rate of 100-300 rpm during pH adjustment. Furthermore, in the vacuum evaporation and concentration process in S4, the evaporation temperature is 60-80℃ and the evaporation pressure is -0.03 to -0.01MPa. Furthermore, the mixture is stirred at a rate of 50-200 rpm during cooling and crystallization.

[0015] Furthermore, the weakly acidic cation exchange resin column in S5 is prepared by pretreatment of iminodiacetic acid-type chelated cation exchange resin with dilute sulfuric acid. The pretreatment steps are as follows: Backwash the iminodiacetic acid chelating cation exchange resin with countercurrent water flow until its expansion rate reaches 50-70%. Control the flow rate during backwashing at 8-20 BV / hr until the effluent is clear. Then, introduce 2-3% dilute sulfuric acid (200-250 g / L) into the iminodiacetic acid chelating cation exchange resin at a flow rate of 3-4 BV / hr and soak for 2-4 hours. After soaking, slowly wash the iminodiacetic acid chelating cation exchange resin with water at a flow rate of 3-4 BV / hr until the pH of the effluent stabilizes at 3-4.

[0016] Furthermore, the selective adsorption process in S5 is as follows: the heated adsorbent solution is passed into a weak acid cation exchange resin column at a flow rate of 10-45 BV / hr, and the effluent is detected using copper test paper. Adsorption is stopped when the copper ion concentration is higher than 0.1 g / L.

[0017] The weakly acidic cation exchange resin column and Cu 2+ The complexation stability constant is higher than that of Ni. 2+ Zn 2+ Impurity ions, under weakly acidic conditions of pH 3-5, Cu 2+ It preferentially binds to the weakly acidic cation exchange resin column to achieve selective adsorption. Furthermore, in S6, dilute sulfuric acid is desorbed countercurrently at a flow rate of 3-4 BV / hr, and the desorption temperature is 20-30℃. Furthermore, in S6, the vacuum evaporation concentration temperature of the desorbate is 60-80℃; the evaporation pressure is -0.03 to -0.01 MPa. Furthermore, the cooling crystallization temperature in S6 is 15-35℃, and the cooling crystallization process is stirred at a rate of 50-200 rpm. Further, the crystals were filtered and separated to obtain electroplating grade copper sulfate pentahydrate with a purity of ≥99.5%.

[0018] Furthermore, the mother liquor from the cooling and crystallization processes in S4 and S6 is collected by filtration and reused in the dissolution of crude copper sulfate crystals in S5; the condensate generated by vacuum evaporation in S4 is recovered through a condenser and reused in the dissolution and preparation of copper sulfate by-products from smelting in S1.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Based on the characteristics of copper sulfate, a byproduct of smelting, this invention is the first to construct a combined purification process for pentahydrate copper sulfate, involving oxidation, neutralization, ion exchange adsorption, and recrystallization. The process employs a multi-step combined treatment to specifically remove core impurities such as arsenic and iron, while simultaneously removing trace impurities like nickel and zinc. First, hydrogen peroxide is used to treat the crude copper sulfate solution, converting ferrous ions into ferric ions and trivalent arsenic into pentavalent arsenic, facilitating subsequent precipitation steps. Then, ferric sulfate solution is introduced to replenish the iron source, allowing arsenate and residual iron ions to precipitate simultaneously during the formation of flocculent ferric hydroxide, achieving deep impurity removal through co-precipitation. A sodium-free pH adjuster is used to regulate the pH, preventing the introduction of sodium ions and overcoming the impact of sodium ion impurities on purity found in existing technologies. Furthermore, a combination of vacuum filtration, acidification, and evaporation concentration is designed to simultaneously ensure efficient solid-liquid separation and copper ion enrichment. After selective adsorption of copper ions, countercurrent desorption with dilute sulfuric acid further removes heavy metal impurities, achieving efficient conversion of the copper sulfate raw material and complete impurity removal, solving the technical problem of balancing purity and yield in traditional methods.

[0020] 2. The electroplating-grade copper sulfate pentahydrate product processed by the combined purification process of this invention exhibits excellent physicochemical properties and stable quality. Test results from the examples show that the silver (Ag) content in the copper sulfate pentahydrate product is 0.0008%~0.0011%, and the contents of arsenic (As), bismuth (Bi), iron (Fe), nickel (Ni), antimony (Sb), and tin (Sn) are all below the detection limits, reaching <0.0001%, <0.0001%, <0.0001%, <0.0001%, and <0.00%, respectively. With a purity of 0.01% and <0.0001%, lead (Pb) content is <0.0005%~0.0013%, and zinc (Zn) content is <0.0003%. The main purity of the products reaches over 99.5%, and some can reach over 99.7%. This achieves efficient conversion of raw materials and complete removal of impurities. Furthermore, no foreign impurities such as sodium ions are introduced throughout the process. The stable purity of the products meets the strict quality standards of the high-end electroplating industry for raw materials, and can provide high-quality raw material guarantees for downstream PCB manufacturing, semiconductor electroplating and other fields.

[0021] 3. The innovative combined purification process of this invention is simple and smooth, with each step closely linked. The rational use of vacuum filtration and vacuum evaporation concentration equipment significantly shortens the overall process flow and achieves closed-loop recycling of mother liquor and wastewater. By reusing filter wash water and evaporation condensate, production energy consumption and pollutant emissions are significantly reduced. Furthermore, the vacuum conditions in the evaporation concentration stage further reduce energy consumption compared to traditional atmospheric pressure evaporation. Based on this, the invention designs mild cooling and crystallization conditions, avoiding lattice defects and impurity entrainment caused by rapid product cooling. Therefore, the overall combined purification process disclosed in this invention not only ensures the requirement for high-purity extraction but also meets the requirements of green environmental protection and a circular economy.

[0022] 4. This invention uses copper sulfate, a byproduct of copper smelting, generated during the electrolytic copper production process, as the core raw material. Through deep purification and processing, it is transformed into a high-value-added electroplating-grade product, effectively realizing the efficient recycling of copper smelting byproduct resources. This avoids the waste caused by the fact that this part of the copper resources can only be used in low-value-added fields, significantly improving the overall added value of the copper industry chain. Furthermore, this combined purification process has multiple advantages such as simple operation, controllable cost, excellent product quality, high resource utilization rate, and environmental friendliness, and has good prospects for industrial promotion and application. Detailed Implementation

[0023] The present invention will be further described below with reference to preferred embodiments. The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values. These ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. The weak acid cation exchange resin columns used in the following examples were prepared by pretreatment of iminodiacetic acid type chelated cation exchange resin with dilute sulfuric acid. The pretreatment steps are as follows: The iminodiacetic acid chelating cation exchange resin was backwashed with countercurrent water until its expansion rate reached 50-70%. The backwashing process was controlled at a flow rate of 14 BV / hr until the effluent was clear. Then, 2.5% dilute sulfuric acid (225 g / L) was introduced into the iminodiacetic acid chelating cation exchange resin at a flow rate of 3.5 BV / hr and soaked for 3 h. After that, the iminodiacetic acid chelating cation exchange resin was slowly washed with water at a flow rate of 3.5 BV / hr until the pH of the effluent was 3.5.

[0025] In addition, depending on experimental requirements or actual operation, the backwash flow rate can be adjusted to 8 BV / hr or 20 BV / hr; the amount of dilute sulfuric acid can be 200 g / L or 250 g / L, the concentration can be 2% or 3%, the flow rate can be 3 BV / hr or 4 BV / hr, the soaking time can be 2 h or 4 h, the slow water rinsing flow rate can be 3 BV / hr or 4 BV / hr, and the pH of the effluent can be 3 or 4.

[0026] Example 1 This embodiment provides a method for purifying electroplating-grade copper sulfate pentahydrate based on copper sulfate by-products from smelting, including the following steps: S1: Place copper sulfate raw material, a by-product of smelting, into a reaction vessel, add ultrapure water, and stir at 300 rpm to obtain crude copper sulfate solution with a copper content of 70 g / L. S2: Add 30% hydrogen peroxide to the crude copper sulfate solution in the reactor at a mass ratio of 1:150, and oxidize at 300 rpm at 50°C for 0.5 h. S3: Add 8 g / L ferric sulfate solution to the oxidized solution in S2 at a dosage of 0.5 mL / L. After flocculent ferric hydroxide is formed, adjust the pH of the solution to 3.8 using a sodium-free pH adjuster. Stir the reaction for 1 h and then let it stand for 0.5 h to settle. S4: The precipitate obtained from S3 was removed by vacuum filtration at a pressure of -0.03 MPa to obtain copper sulfate filtrate. The solution was adjusted to pH 1 by stirring with sulfuric acid at 200 rpm for 0.8 h. It was then concentrated by vacuum evaporation at 70 °C and -0.02 MPa to a solution density of 1.4 g / ml. The solution was then cooled to 25 °C for crystallization. S5: Filter to obtain crude copper sulfate crystals, prepare them into an adsorption solution with a copper ion concentration of 80 g / L and heat to 65℃; S6: Pass the heated adsorption solution into a weak acid cation exchange resin column at a flow rate of 30 BV / hr. Stop adsorption when the copper ion concentration in the effluent reaches 0.1 g / L. S7: Use 20% dilute sulfuric acid to flow through the adsorbed weak acid cation exchange resin column for countercurrent desorption at a flow rate of 3 BV / hr and a desorption temperature of 25℃ to obtain a high-purity copper sulfate desorption solution. S8: The desorbed solution was concentrated by vacuum evaporation to a solution density of 1.4 g / ml. The evaporation temperature was controlled at 75℃ and the evaporation pressure was -0.025 MPa. After cooling to 25℃, crystallization was carried out. The crystals were separated by filtration to obtain an electroplating-grade copper sulfate product with a purity of 99.7%. The product composition is shown in Table 1. Table 1

[0027] In this embodiment, the mother liquor from cooling and crystallization in S4 and S8 is collected by filtration and then combined for reuse in dissolving the crude copper sulfate crystals in S5; the condensate from vacuum evaporation in S4 is recovered via a condenser and reused in dissolving and preparing the copper sulfate by-product from smelting in S1, thereby achieving closed-loop recycling of liquid materials.

[0028] Example 2 This embodiment provides a method for purifying electroplating-grade copper sulfate pentahydrate based on copper sulfate by-products from smelting, including the following steps: S1: Place copper sulfate raw material, a by-product of smelting, into a reaction vessel, add ultrapure water, and stir at 350 rpm to obtain crude copper sulfate solution with a copper content of 75 g / L. S2: Add 20% hydrogen peroxide to the crude copper sulfate solution in the reactor at a mass ratio of 1:50, and stir at 400 rpm for 1 hour at 30°C. S3: Add 8 g / L ferric sulfate solution to the oxidized solution in S2 at a dosage of 1 mL / L. After flocculent ferric hydroxide is formed, adjust the pH of the solution to 4.0 using a sodium-free pH adjuster. Stir the reaction for 0.5 h and then let it stand for 0.5 h to settle. S4: The precipitate obtained from S3 was removed by vacuum filtration at a pressure of -0.035 MPa to obtain copper sulfate filtrate. The solution was adjusted to pH 2 by stirring with sulfuric acid at 250 rpm for 0.6 h. It was then concentrated by vacuum evaporation at 75 °C and -0.015 MPa to a solution density of 1.5 g / ml. The solution was then cooled to 30 °C for crystallization. S5: Filter to obtain crude copper sulfate crystals, prepare them into an adsorption solution with a copper ion concentration of 85 g / L and heat to 50℃; S6: Pass the heated adsorption solution into a weak acid cation exchange resin column at a flow rate of 25 BV / hr. Stop adsorption when the copper ion concentration in the effluent reaches 0.1 g / L. S7: Use 10% dilute sulfuric acid to flow through the adsorbed weak acid cation exchange resin column for countercurrent desorption at a flow rate of 4 BV / hr and a desorption temperature of 24℃ to obtain a high-purity copper sulfate desorption solution. S8: Vacuum evaporation was used to concentrate the desorbed solution to a density of 1.5 g / ml. The evaporation temperature was controlled at 72℃ and the evaporation pressure was -0.02 MPa. The solution was then cooled to 30℃ for crystallization. The crystals were separated by filtration to obtain an electroplating-grade copper sulfate product with a purity of 99.6%. The product composition is shown in Table 2. Table 2

[0029] In this embodiment, the mother liquor from cooling and crystallization in S4 and S8 is collected by filtration and then combined for reuse in dissolving the crude copper sulfate crystals in S5; the condensate from vacuum evaporation in S4 is recovered via a condenser and reused in dissolving and preparing the copper sulfate by-product from smelting in S1, thereby achieving closed-loop recycling of liquid materials.

[0030] Example 3 This embodiment provides a method for purifying electroplating-grade copper sulfate pentahydrate based on copper sulfate by-products from smelting, including the following steps: S1: Place copper sulfate raw material, a by-product of smelting, into a reaction vessel, add ultrapure water, and stir at 320 rpm to obtain crude copper sulfate solution with a copper content of 80 g / L. S2: Add 40% hydrogen peroxide to the crude copper sulfate solution in the reactor at a mass ratio of 1:200, and oxidize at 350 rpm at 70°C for 0.8 h. S3: Add 7 g / L ferric sulfate solution to the oxidized solution in S2 at a dosage of 0.7 mL / L. After flocculent ferric hydroxide is formed, adjust the pH of the solution to 3.5 using a sodium-free pH adjuster. Stir the reaction for 1 h and then let it stand for 0.5 h to settle. S4: The precipitate obtained from S3 was removed by vacuum filtration at a pressure of -0.03 MPa to obtain copper sulfate filtrate. The solution was adjusted to pH 1.5 by stirring with sulfuric acid at 220 rpm for 0.7 h. The solution was then concentrated by vacuum evaporation at 72 °C and -0.02 MPa to a solution density of 1.45 g / ml. The solution was then cooled to 28 °C for crystallization. S5: Filter to obtain crude copper sulfate crystals, prepare them into an adsorption solution with a copper ion concentration of 80 g / L and heat to 80℃; S6: Pass the heated adsorption solution into a weak acid cation exchange resin column at a flow rate of 28 BV / hr. Stop adsorption when the copper ion concentration in the effluent reaches 0.1 g / L. S7: Use 30% dilute sulfuric acid to flow through the adsorbed weak acid cation exchange resin column for countercurrent desorption at a flow rate of 3 BV / hr and a desorption temperature of 25℃ to obtain high-purity copper sulfate desorption solution. S8: The desorbed solution was concentrated by vacuum evaporation to a solution density of 1.45 g / ml. The evaporation temperature was controlled at 73℃ and the evaporation pressure was -0.022 MPa. After cooling to 28℃, crystallization was carried out. The crystals were separated by filtration to obtain an electroplating-grade copper sulfate product with a purity of 99.6%. The product composition is shown in Table 3. Table 3

[0031] In this embodiment, the mother liquor from cooling and crystallization in S4 and S8 is collected by filtration and then combined for reuse in dissolving the crude copper sulfate crystals in S5; the condensate from vacuum evaporation in S4 is recovered via a condenser and reused in dissolving and preparing the copper sulfate by-product from smelting in S1, thereby achieving closed-loop recycling of liquid materials.

[0032] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for the combined purification of electroplating-grade copper sulfate pentahydrate based on copper sulfate by-products from metallurgical processes, characterized in that, Includes the following steps: S1. Prepare crude copper sulfate solution with a copper content of 60-90 g / L using copper sulfate, a by-product of smelting, as raw material; S2. Add 20-40% hydrogen peroxide to the crude copper sulfate solution at a mass ratio of 1:50-200, and stir and oxidize at 30-70℃ for 0.5-1h. S3. Add 0.2-1.2 mL / L ferric sulfate solution, and adjust the pH of the solution to 3.5-4.0 using a sodium-free pH adjuster to hydrolyze the iron ions to form flocculent ferric hydroxide, while simultaneously precipitating arsenate. Stir the reaction for 0.5-1 h and then let it stand for 0.5 h to settle. S4. Vacuum filtration is used to remove the precipitate obtained in S3, and the copper sulfate filtrate is obtained. The pH of the filtrate is adjusted to 1-2 with sulfuric acid, and the solution is concentrated by vacuum evaporation to a density of 1.2-1.6 g / ml. The solution is then cooled to 15-35℃ for crystallization. S5. Filter to obtain crude copper sulfate crystals, prepare them into an adsorption solution with a copper ion concentration of 60-90 g / L and heat to 50-80℃, and use a weak acid cation exchange resin column for selective adsorption. S6. Use 10-30% dilute sulfuric acid to flow through the weak acid cation exchange resin column after adsorption for countercurrent desorption to obtain high-purity copper sulfate desorption solution. Vacuum evaporate and concentrate the desorption solution to a solution density of 1.2-1.6 g / ml, cool to 15-35℃ for crystallization to obtain electroplating grade copper sulfate pentahydrate.

2. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, The concentration of the ferric sulfate solution in S3 is 5-10 g / L, the sodium-free pH adjuster is any one of copper oxide, copper hydroxide or basic copper carbonate, and the stirring speed is 200-400 rpm.

3. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, The filtration pressure in S4 is -0.04 to -0.02 MPa; the pH is adjusted with sulfuric acid by stirring at a rate of 100-300 rpm.

4. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on copper sulfate by-product from smelting as described in claim 1, characterized in that, During the vacuum evaporation and concentration process in S4, the evaporation temperature is 60-80℃ and the evaporation pressure is -0.03 to -0.01MPa.

5. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, The weak acid cation exchange resin column in S5 is prepared by pretreatment of iminodiacetic acid type chelated cation exchange resin with dilute sulfuric acid. The pretreatment steps are as follows: Backwash the iminodiacetic acid chelating cation exchange resin with countercurrent water flow until its expansion rate reaches 50-70%. Control the flow rate during backwashing at 8-20 BV / hr until the effluent is clear. Then, introduce 2-3% dilute sulfuric acid into the iminodiacetic acid chelating cation exchange resin at a flow rate of 3-4 BV / hr. The amount of dilute sulfuric acid used is 200-250 g / L of resin. After soaking for 2-4 h, slowly wash the iminodiacetic acid chelating cation exchange resin with water at a flow rate of 3-4 BV / hr until the pH of the effluent stabilizes at 3-4.

6. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, The selective adsorption process in S5 is as follows: the heated adsorbent solution is passed into a weak acid cation exchange resin column at a flow rate of 10-45 BV / hr, and the effluent is detected using copper test paper. Adsorption is stopped when the copper ion concentration reaches 0.1 g / L.

7. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, In S6, dilute sulfuric acid is desorbed countercurrently at a flow rate of 3-4 BV / hr, and the desorption temperature is 20-30℃.

8. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, The vacuum evaporation concentration temperature of the desorbate in S6 is 60-80℃; the evaporation pressure is -0.03 to -0.01 MPa.

9. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, The cooling crystallization temperature in S6 is 15-35℃, and the cooling crystallization process is carried out by stirring at a rate of 50-200 rpm.

10. The method for jointly purifying electroplating-grade copper sulfate pentahydrate based on smelting by-product copper sulfate according to claim 1, characterized in that, The mother liquor from the cooling and crystallization processes in S4 and S6 is collected by filtration and reused in the dissolution of crude copper sulfate crystals in S5; the condensate from the vacuum evaporation in S4 is recovered through a condenser and reused in the dissolution and preparation of copper sulfate by-product from smelting in S1.

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