A production process for preparing copper salt by using waste PCBs

Abstract

The application relates to a production process for preparing copper salt by using waste PCBs, and belongs to the technical field of preparing copper salt by using waste PCBs. The application discloses a production process for preparing copper salt by using waste PCBs, and the specific steps are as follows: (1) waste PCBs are crushed into powder, are subjected to magnetic attraction treatment in water, impurities are removed, and pretreated raw materials are obtained through filtration and drying; (2) the pretreated raw materials are put into a reaction device, mixed acid is added and stirred, then phosphoric acid, a catalyst and urea are added and stirred to form a solid-liquid mixture; (3) a conduit is connected to the reaction device to discharge gas, and the gas outlet end of the conduit is put into the mixed liquid; (4) the solid-liquid mixture is filtered, the filtrate is evaporated and crystallized to obtain copper salt, the solid is dried, and the catalyst is recovered through sieving. The magnetic attraction treatment in water removes magnetic metal and floating resin, plays a washing role, improves acidolysis and impurity removal efficiency, and guarantees the purity and yield of the copper salt; in addition, the catalyst promotes the decomposition of urea at normal temperature, and can be recycled.

Description

Technical Field

[0001] This invention belongs to the technical field of preparing copper salts from waste circuit boards, and relates to a production process for preparing copper salts using waste PCBs. Background Technology

[0002] Waste circuit boards are typically composed of multiple layers of fiber materials (such as fiberglass) and metal materials, with copper accounting for about 20% of the total weight, and contain various electronic components. These circuit boards are generated during the upgrading and replacement of electronic products, and improper disposal can cause serious environmental pollution, especially the release of heavy metals and toxic chemicals. Therefore, copper recycling is essential.

[0003] Currently, methods for recovering copper from waste circuit boards include physical methods, chemical methods, pyrometallurgical methods, and bioleaching methods. Each method has its own advantages and disadvantages. Physical methods are simple, but they are insufficient when separating mixtures of metal particles. Chemical methods are low-cost and yield high-purity recovered metals, but they are polluting and can damage equipment. Pyrometallurgical methods recover metals through refining and electrolysis, which requires a large amount of heat and generates a large amount of polluting gases at high temperatures. Bioleaching methods are low-cost, energy-saving, and environmentally friendly, but they have harsh operating conditions and long cycles. Therefore, this invention further optimizes existing technologies and proposes a production process for preparing copper salts from waste PCBs. Summary of the Invention

[0004] This invention relates to a production process for preparing copper salts using waste PCBs, belonging to the technical field of copper salt preparation from waste circuit boards. The invention discloses a production process for preparing copper salts using waste PCBs, with the following specific steps: (1) Waste circuit boards are crushed into powder, placed in water for magnetic adsorption treatment to remove impurities, filtered and dried to obtain pretreated raw materials; (2) The pretreated raw materials are placed in a reaction device and mixed acid is added and stirred, then phosphoric acid, a catalyst, and urea are added and stirred to form a solid-liquid mixture; (3) Gas is discharged from the reaction device via a connecting conduit, and the gas outlet of the conduit is placed into the mixed liquid; (4) The solid-liquid mixture is filtered, and the filtrate is evaporated and crystallized to obtain copper salts. The solid is dried, and the catalyst is recovered by sieving. Magnetic adsorption treatment in water removes magnetic metals and floats resin, while also acting as a washing agent, improving acidolysis and impurity removal efficiency, ensuring the purity and yield of copper salts; additionally, the catalyst promotes the decomposition of urea at room temperature and allows for recycling.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A production process for preparing copper salts using waste PCBs, specifically including the following steps:

[0007] (1) The waste circuit board is crushed into powder, then put into water and stir while using a magnet to remove floating impurities. After filtration, the solid is dried to become the pre-treated raw material.

[0008] (2) Place the pretreated raw materials into the reaction apparatus, add mixed acid and stir, then add phosphoric acid, catalyst and urea and continue stirring to form a solid-liquid mixture;

[0009] (3) The gas is discharged through the connecting tube of the reaction device, and the gas outlet end of the tube is placed into the mixture;

[0010] (4) The solid-liquid mixture is filtered, and the filtrate is evaporated until crystallization to obtain copper salt. The solid is dried, sieved, and the catalyst is recovered.

[0011] Further, in step (1), the powder has a mesh size of 50-150, the mass ratio of the powder to water is 2-5:15-20, the stirring speed is 600-900 r / min, the magnetic force of the magnet is in the range of 300-500 Gauss, and the drying refers to drying to a moisture content of 5-8%.

[0012] Further, in step (2), the mass ratio between the pretreatment raw materials, mixed acid, phosphoric acid, catalyst and urea is 1-1.5:2:0.5-1:0.03-0.05:0.5-1, wherein the mixed acid is composed of nitric acid and sulfuric acid in a mass ratio of 0.5-1:1, and the mass fraction of the mixed acid is 50-60%.

[0013] Furthermore, the mixing and stirring time in step (2) is 15-20 min, the continuous stirring time is 1-2 h, and the mass fraction of phosphoric acid is 50-60%.

[0014] Further, the catalyst preparation method in step (2) is as follows: porous zeolite is soaked in zirconium oxynitrate solution, the liquid is removed by filtration, and then calcined at a higher temperature and cooled to obtain the catalyst.

[0015] Furthermore, the porous zeolite has a size of 3-5 mm, the zirconium oxynitrate solution has a mass fraction of 50-70%, the soaking time is 15-30 min, and the calcination temperature and time are 150-180℃ and 60-90 min, respectively.

[0016] Further, the gas in step (3) is nitrogen dioxide, and the mixture is formed by mixing distilled water, calcium oxide and ammonia water in a mass ratio of 5-8:2-3:3-5, wherein the mass fraction of ammonia water is 25-28%.

[0017] Furthermore, the evaporation temperature in step (4) is 90-100℃, and the drying refers to drying to a moisture content of 5-8%.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention utilizes magnetic adsorption in water to remove magnetic metals (including iron, tin, and nickel) and also removes floating resin with low density, while simultaneously serving a cleaning function. By controlling the stirring speed and the magnitude of the magnetic force, the adsorption of magnetic metals is enhanced. When the interaction between the two reaches a certain equilibrium point, the adsorption effect is optimal, thereby reducing copper doping and increasing the yield of copper salts.

[0020] 2. Using nitric acid and sulfuric acid as a mixed acid improves the acidolysis efficiency of metals. The addition of phosphoric acid, a catalyst, and urea causes metal ions other than copper to precipitate. Due to the instability of ammonia, the addition of urea decomposes it to form NH4. + It combines with excess nitric acid to form carbon dioxide, nitrogen and water, while the catalyst firmly attaches zirconium dioxide to the pores of porous zeolite, which solves the problem that urea is difficult to hydrolyze at room temperature and can be recycled.

[0021] 3. Furthermore, the nitrogen dioxide gas generated during the process is treated to avoid environmental impact. Therefore, this invention utilizes magnetic attraction to reduce the presence of impurity metals, thereby lowering acidity and mitigating damage to equipment. The preparation process of this invention ensures both the purity and yield of copper salts, is simple in steps, and is environmentally friendly. Detailed Implementation

[0022] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with embodiments, is provided below.

[0023] The porous zeolite involved in this invention was purchased from Pingxiang Kangyu New Energy Technology Co., Ltd.

[0024] Example 1

[0025] A production process for preparing copper salts using waste PCBs, specifically including the following steps:

[0026] (1) The waste circuit board is crushed into powder, then put into water and stir while using a magnet to remove floating impurities. After filtration, the solid is dried to become the pre-treated raw material.

[0027] (2) Place the pretreated raw materials into the reaction apparatus, add mixed acid and stir, then add phosphoric acid, catalyst and urea and continue stirring to form a solid-liquid mixture;

[0028] (3) The gas is discharged through the connecting tube of the reaction device, and the gas outlet end of the tube is placed into the mixture;

[0029] (4) The solid-liquid mixture is filtered, and the filtrate is evaporated until crystallization to obtain copper salt. The solid is dried, sieved, and the catalyst is recovered.

[0030] In step (1), the powder has a mesh size of 50, the mass ratio of the powder to water is 2:15, the stirring speed is 600 r / min, the magnetic force of the magnet is 300 gauss, and the drying refers to drying to a moisture content of 5%.

[0031] The mass ratio between the pretreatment raw materials, mixed acid, phosphoric acid, catalyst and urea in step (2) is 1:2:0.5:0.03:0.5, where the mixed acid is composed of nitric acid and sulfuric acid in a mass ratio of 0.5:1, and the mass fraction of the mixed acid is 50%.

[0032] The mixing and stirring time in step (2) is 15 min, the continuous stirring time is 1 h, and the mass fraction of phosphoric acid is 50%.

[0033] The catalyst in step (2) is prepared by soaking porous zeolite in a zirconium oxynitrate solution, filtering out the liquid, calcining it at a higher temperature, and then cooling it to obtain the catalyst.

[0034] The porous zeolite has a size of 3 mm, the zirconium oxynitrate solution has a mass fraction of 50%, the soaking time is 15 min, and the calcination temperature and time are 150 °C and 60 min, respectively.

[0035] The gas in step (3) is nitrogen dioxide, and the mixture is formed by mixing distilled water, calcium oxide and ammonia water in a mass ratio of 5:2:3, wherein the mass fraction of ammonia water is 25%.

[0036] The evaporation temperature in step (4) is 90°C, and the drying refers to drying to a moisture content of 5%.

[0037] Example 2

[0038] A production process for preparing copper salts using waste PCBs, specifically including the following steps:

[0039] (1) The waste circuit board is crushed into powder, then put into water and stir while using a magnet to remove floating impurities. After filtration, the solid is dried to become the pre-treated raw material.

[0040] (2) Place the pretreated raw materials into the reaction apparatus, add mixed acid and stir, then add phosphoric acid, catalyst and urea and continue stirring to form a solid-liquid mixture;

[0041] (3) The gas is discharged through the connecting tube of the reaction device, and the gas outlet end of the tube is placed into the mixture;

[0042] (4) The solid-liquid mixture is filtered, and the filtrate is evaporated until crystallization to obtain copper salt. The solid is dried, sieved, and the catalyst is recovered.

[0043] In step (1), the powder has a mesh size of 100, the mass ratio of the powder to water is 3.5:17.5, the stirring speed is 750 r / min, the magnetic force of the magnet is 400 gauss, and the drying refers to drying to a moisture content of 6.5%.

[0044] The mass ratio of the pretreatment raw materials, mixed acid, phosphoric acid, catalyst and urea in step (2) is 1.2:2:0.8:0.04:0.8, where the mixed acid is composed of nitric acid and sulfuric acid in a mass ratio of 0.8:1, and the mass fraction of the mixed acid is 55%.

[0045] The mixing and stirring time in step (2) is 18 min, the continuous stirring time is 1.5 h, and the mass fraction of phosphoric acid is 55%.

[0046] The catalyst in step (2) is prepared by soaking porous zeolite in a zirconium oxynitrate solution, filtering out the liquid, calcining it at a higher temperature, and then cooling it to obtain the catalyst.

[0047] The porous zeolite has a size of 4 mm, the zirconium oxynitrate solution has a mass fraction of 60%, the soaking time is 22 min, and the calcination temperature and time are 165 °C and 75 min, respectively.

[0048] The gas in step (3) is nitrogen dioxide, and the mixture is formed by mixing distilled water, calcium oxide and ammonia water in a mass ratio of 6.5:2.5:4, wherein the mass fraction of ammonia water is 26.5%.

[0049] The evaporation temperature in step (4) is 95°C, and the drying refers to drying to a moisture content of 6.5%.

[0050] Example 3

[0051] A production process for preparing copper salts using waste PCBs, specifically including the following steps:

[0052] (1) The waste circuit board is crushed into powder, then put into water and stir while using a magnet to remove floating impurities. After filtration, the solid is dried to become the pre-treated raw material.

[0053] (2) Place the pretreated raw materials into the reaction apparatus, add mixed acid and stir, then add phosphoric acid, catalyst and urea and continue stirring to form a solid-liquid mixture;

[0054] (3) The gas is discharged through the connecting tube of the reaction device, and the gas outlet end of the tube is placed into the mixture;

[0055] (4) The solid-liquid mixture is filtered, and the filtrate is evaporated until crystallization to obtain copper salt. The solid is dried, sieved, and the catalyst is recovered.

[0056] In step (1), the powder has a mesh size of 150, the mass ratio of the powder to water is 5:20, the stirring speed is 900 r / min, the magnetic force of the magnet is 500 gauss, and the drying refers to drying to a moisture content of 8%.

[0057] The mass ratio of the pretreatment raw materials, mixed acid, phosphoric acid, catalyst and urea in step (2) is 1.5:2:1:0.05:1, wherein the mixed acid is composed of nitric acid and sulfuric acid in a mass ratio of 1:1, and the mass fraction of the mixed acid is 60%.

[0058] The mixing and stirring time in step (2) is 20 min, the continuous stirring time is 2 h, and the mass fraction of phosphoric acid is 60%.

[0059] The catalyst in step (2) is prepared by soaking porous zeolite in a zirconium oxynitrate solution, filtering out the liquid, calcining it at a higher temperature, and then cooling it to obtain the catalyst.

[0060] The porous zeolite has a size of 5 mm, the zirconium oxynitrate solution has a mass fraction of 70%, the soaking time is 30 min, and the calcination temperature and time are 180 °C and 90 min, respectively.

[0061] The gas in step (3) is nitrogen dioxide, and the mixture is formed by mixing distilled water, calcium oxide and ammonia water in a mass ratio of 8:3:5, wherein the mass fraction of ammonia water is 28%.

[0062] The evaporation temperature in step (4) is 100°C, and the drying refers to drying to a moisture content of 8%.

[0063] Comparative Example 1

[0064] Based on Example 2, a production process for preparing copper salts using waste PCBs is provided, which specifically includes the following steps:

[0065] (1) The waste circuit board is crushed into powder, then put into the reaction device, and mixed acid is added and stirred. Then phosphoric acid, catalyst and urea are added and stirred continuously to form a solid-liquid mixture.

[0066] (2) The gas is discharged through the connecting tube of the reaction device, and the gas outlet end of the tube is placed into the mixture;

[0067] (3) The solid-liquid mixture is filtered, and the filtrate is evaporated until crystallization to obtain copper salt. The solid is dried, sieved, and the catalyst is recovered.

[0068] In step (1), the powder has a mesh size of 100 mesh, the mass ratio of the powder to water is 3.5:17.5, and the mass ratio of the powder, mixed acid, phosphoric acid, catalyst and urea is 1.2:2:0.8:0.04:0.8. The mixed acid is composed of nitric acid and sulfuric acid in a mass ratio of 0.8:1, and the mass fraction of the mixed acid is 55%.

[0069] The mixing and stirring time in step (1) is 18 min, the continuous stirring time is 1.5 h, and the mass fraction of phosphoric acid is 55%.

[0070] The catalyst in step (1) is prepared by soaking porous zeolite in a zirconium oxynitrate solution, filtering out the liquid, calcining it at a higher temperature, and then cooling it to obtain the catalyst.

[0071] The porous zeolite has a size of 4 mm, the zirconium oxynitrate solution has a mass fraction of 60%, the soaking time is 22 min, and the calcination temperature and time are 165 °C and 75 min, respectively.

[0072] The gas in step (2) is nitrogen dioxide, and the mixture is formed by mixing distilled water, calcium oxide and ammonia water in a mass ratio of 6.5:2.5:4, wherein the mass fraction of ammonia water is 26.5%.

[0073] The evaporation temperature in step (3) is 95°C, and the drying refers to drying to a moisture content of 6.5%.

[0074] Comparative Example 2

[0075] Based on Example 2, the stirring step in step (1) is removed, and other conditions are the same as in Example 2.

[0076] Comparative Example 3

[0077] Based on Example 2, the stirring speed in step (1) was adjusted to 1200 r / min, the magnetic force was 200 Gauss, and other conditions were the same as in Example 2.

[0078] Comparative Example 4

[0079] Based on Example 2, the catalyst in step (2) was removed, while other conditions remained the same as in Example 2.

[0080] Comparative Example 5

[0081] Based on Example 2, the catalyst was replaced with porous zeolite, and other conditions were the same as in Example 2.

[0082] Performance testing

[0083] The copper content of the waste circuit board powders in Examples 1-3 and Comparative Examples 1-5 was determined by energy-dispersive X-ray spectroscopy, and the mass of copper was calculated. The specific formula is: mass of copper (g) = mass of powder (g) × copper content (%). At the same time, the copper content and purity in the copper salts prepared in Examples 1-3 and Comparative Examples 1-4 were determined by energy-dispersive X-ray spectroscopy. The copper recovery rate % was calculated as: (copper content in copper salt % × mass of copper salt g) / mass of copper g × 100%. The above test results are shown in Table 1.

[0084] Table 1 Evaluation Results

[0085]

[0086] Analysis of the results in Table 1 shows that the copper recovery rate (%) in Examples 1-3 is higher than that in Comparative Examples 1-5, and the purity of the copper salt in Examples 1-3 is higher than that in Comparative Examples 1 and 3-5. Comparative Example 1 did not undergo magnetic adsorption treatment in water, resulting in a large amount of impurities (metals, resins, and glass fibers) during the acidolysis process, thus reducing the acidolysis efficiency of the mixed acid and significantly decreasing the copper recovery rate and the purity of the copper salt. Comparative Example 2 omitted the stirring step during the magnetic adsorption treatment in water, causing copper adsorption during the magnetic adsorption process, thus reducing the copper recovery rate, but not affecting the purity of the copper salt. Comparative Example 3 increased the stirring speed in the magnetic adsorption treatment in water, exceeding the speed range of Examples 1-3, and simultaneously reduced the magnetic force, resulting in poor magnetic force and excessively high speed, making it difficult to adsorb magnetic metals. The high content of metal impurities reduced the acidolysis efficiency, thus decreasing the copper recovery rate and the purity of the copper salt. Comparative Example 4 did not add a catalyst, and urea was difficult to decompose at room temperature, resulting in NH4. + The reduction in nitric acid content resulted in an inability to remove excess nitric acid, leading to a decrease in the purity of the copper salt. Comparative Example 5 used porous zeolite as a catalyst, but it lacked the catalytic effect of urea, thus reducing copper recovery. In conclusion, during the preparation process of copper recovery from waste PCBs, the optimal adsorption effect is achieved when the interaction between magnetic attraction and stirring reaches a certain equilibrium point. Furthermore, using zirconium dioxide support and porous zeolite as a catalyst can effectively improve the copper recovery rate.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A production process for preparing copper salts using waste PCBs, characterized in that, The production process for preparing copper salts using waste PCBs specifically includes the following steps: (1) The waste circuit board is crushed into powder, then put into water and stir while using a magnet to remove floating impurities. After filtration, the solid is dried to become the pre-treated raw material. (2) Place the pretreated raw materials into the reaction apparatus, add mixed acid and stir, then add phosphoric acid, catalyst and urea and continue stirring to form a solid-liquid mixture; (3) The gas is discharged through the connecting tube of the reaction device, and the gas outlet end of the tube is placed into the mixture; (4) The solid-liquid mixture is filtered, and the filtrate is evaporated until crystallization to obtain copper salt. The solid is dried, sieved, and the catalyst is recovered.

2. The production process for preparing copper salts using waste PCBs according to claim 1, characterized in that, In step (1), the powder has a mesh size of 50-150, the mass ratio of the powder to water is 2-5:15-20, the stirring speed is 600-900 r / min, the magnetic force of the magnet is 300-500 Gauss, and the drying refers to drying to a moisture content of 5-8%.

3. The production process for preparing copper salts using waste PCBs according to claim 1, characterized in that, The mass ratio between the pretreatment raw materials, mixed acid, phosphoric acid, catalyst and urea in step (2) is 1-1.5:2:0.5-1:0.03-0.05:0.5-1, where the mixed acid is composed of nitric acid and sulfuric acid in a mass ratio of 0.5-1:1, and the mass fraction of the mixed acid is 50-60%.

4. The production process for preparing copper salts using waste PCBs according to claim 1, characterized in that, The mixing and stirring time in step (2) is 15-20 min, the continuous stirring time is 1-2 h, and the mass fraction of phosphoric acid is 50-60%.

5. The production process for preparing copper salts using waste PCBs according to claim 1, characterized in that, The catalyst in step (2) is prepared by soaking porous zeolite in a zirconium oxynitrate solution, filtering out the liquid, calcining it at a higher temperature, and then cooling it to obtain the catalyst.

6. The production process for preparing copper salts using waste PCBs according to claim 5, characterized in that, The porous zeolite has a size of 3-5 mm, the zirconium oxynitrate solution has a mass fraction of 50-70%, the soaking time is 15-30 min, and the calcination temperature and time are 150-180℃ and 60-90 min, respectively.

7. The production process for preparing copper salts using waste PCBs according to claim 1, characterized in that, The gas in step (3) is nitrogen dioxide, and the mixture is formed by mixing distilled water, calcium oxide and ammonia water in a mass ratio of 5-8:2-3:3-5, wherein the mass fraction of ammonia water is 25-28%.

8. The production process for preparing copper salts using waste PCBs according to claim 1, characterized in that, The evaporation temperature in step (4) is 90-100℃, and the drying refers to drying to a moisture content of 5-8%.

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