A method for separating copper and tin in copper-tin heavy sand

Abstract

The present invention relates to a method for separating copper and tin in copper-tin heavy sand, wherein the copper-tin heavy sand to be treated is dried to obtain a material with a moisture content of ≤3wt%; after the material is loaded into a screen barrel, it is placed in a flux melt at a temperature of 240-295°C, so that the material is immersed in the flux melt, stirred, and the material is loose; then, the material is centrifuged at 240-295°C to obtain a solder melt and a copper-rich copper slag material; wherein the screen barrel includes a barrel body, and a plurality of sieve holes are distributed on the side wall of the barrel body, and the aperture of the sieve holes is smaller than the particle size of the copper-tin heavy sand; the flux includes rosin. The separation method of the present invention is simple and easy to operate, and can quickly and directly separate solder products and copper-containing raw materials, realize copper-tin separation and enrichment, and can obtain solder products with a recovery rate of 96%, and the residual tin in the obtained copper slag material is only about 0.5-1.5%, which can be sold as high-grade copper raw materials for value-added.

Description

Technical Field

[0001] The invention relates to a method for separating copper and tin in copper-tin heavy sand, and belongs to the field of pyrometallurgical treatment of abandoned solid waste. Background Art

[0002] In the past, the disassembly of circuit boards in electronic solid waste mostly used manual hot baking to separate the electronic components, and the disassembled second-hand components were digested through the second-hand electronic component market. With the development of the times, this second-hand waste electronic component market is shrinking and disappearing. On the other hand, manual selection consumes a lot of labor. With the increasing labor costs, the previous process of manual sorting and disassembly of circuit boards faces difficulties. Now a large-scale mechanized crushing and disassembly of circuit boards with a crusher has been developed, and the iron is separated by magnetic separation, and the light sand, medium-heavy sand and heavy sand are separated by a shaking table. More than 95% of copper and tin can be recovered from the heavy sand separated by the shaking table. The copper is generally the lead pins of electronic components and the copper foil of the circuit board, and the tin is the solder and welding points coated on the copper surface. This copper-tin heavy sand generally contains 50-70% copper and 20-30% tin, which is a high-value non-ferrous metal raw material. There are two existing recovery process methods. One is to use nitric acid and sulfuric acid for mixed leaching to make copper enter the liquid phase, oxidize tin into tetravalent tin precipitation, and separate it from the copper liquid phase by filtration. This method is simple and easy to operate and suitable for small-scale production, but it requires strong acid, which will inevitably produce acid-containing wastewater, serious pollution, long process and high cost; the second is to smelt the copper-tin heavy sand into copper-tin alloy by pyrometallurgy, and then refine and separate it. This method requires large investment and is suitable for large-scale occasions, but it has a long process and high cost. Summary of the invention

[0003] In view of the shortcomings of the prior art, the object of the present invention is to provide a simple and feasible method for separating copper and tin in copper-tin heavy sand.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A method for separating copper and tin in copper-tin heavy sand comprises the following steps:

[0006] Step 1, drying the copper-tin heavy sand to be treated to obtain a material with a moisture content of ≤3wt%;

[0007] Step 2: After the material is loaded into a screen barrel, it is placed in a flux melt at a temperature of 240-295° C. so that the material is immersed in the flux melt and stirred to make the material loose;

[0008] The sieve barrel comprises a barrel body, and a plurality of sieve holes are distributed on the side wall of the barrel body, and the aperture of the sieve holes is smaller than the particle size of the copper-tin heavy sand; the flux comprises rosin;

[0009] Step 3: Centrifuge the material treated in step 2 at 240-295° C. to obtain solder melt and copper slag rich in copper.

[0010] The present invention dries the copper-tin heavy sand, immerses it in a flux melt at 240-295° C., and stirs it, so that the copper-tin heavy sand is covered by the flux melt and is evenly heated. Under the temperature condition and the action of the flux, the solder is melted and gathered, and the possibility of tin being oxidized is greatly reduced, so the formation of an oxide film can be avoided, and preparations are made for the subsequent smooth centrifugal separation of copper and tin. Subsequently, centrifugal separation is performed at 240-295° C., so that the solder and copper slag can be separated simply and efficiently.

[0011] Furthermore, in the copper-tin heavy sand to be treated, the copper content is ≥50wt%, preferably 55-75wt%, more preferably 60-70wt%; the tin content is ≥20wt%, preferably 25-40wt%, more preferably 30-35wt%.

[0012] Furthermore, the copper-tin heavy sand to be treated is dried to obtain a material with a moisture content of 1-2.5wt%.

[0013] The applicant has found that controlling the water content of the material can effectively prevent high-temperature water frying.

[0014] Further, the temperature of the flux melt is 245-285°C, preferably 255-275°C, and more preferably 260-280°C.

[0015] Furthermore, the side wall of the barrel is made of a screen. Preferably, the screen is made of stainless steel.

[0016] Furthermore, the bottom plate of the barrel is a flat plate, preferably, the barrel is cylindrical, and preferably, the flat plate is made of stainless steel, so that subsequent centrifugal separation can be facilitated and tin leakage can be avoided.

[0017] Furthermore, the aperture of the sieve hole is 10-180 mesh, preferably 20-60 mesh; more preferably, the aperture of the sieve hole is smaller than the particle size of the copper slag.

[0018] Furthermore, the stirring time is ≥15 min, preferably 25-90 min, more preferably 30-75 min, and even more preferably 45-65 min.

[0019] Furthermore, during centrifugal separation, the rotation speed is controlled to be 1000-2000 r / min, preferably 1200-1600 r / min, and more preferably 1300-1500 r / min; the time is 5-30 min, and preferably 10-20 min.

[0020] Furthermore, the material together with the screen bucket is taken out, and the screen bucket is fixed in the drum of a centrifuge for centrifugal separation; preferably, the centrifuge is a vertical centrifuge.

[0021] Furthermore, the solder melt is placed in an ingot mold and cooled to obtain an ingot; wherein the ingot has a solidified flux layer and a solder layer distributed on the upper and lower sides; preferably, after the solidified flux layer and the solder layer of the ingot are physically separated, the solidified flux layer is returned and used as a flux.

[0022] Optionally, a high temperature resistant filter element with a pore size of 10-40 μm is used to filter the solder melt to remove the copper particles. Specifically, the copper content of the solder melt can be tested. When the copper content exceeds the solder standard requirement, the above steps can be performed to ensure that the solder product meets the standard.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The separation method of the present invention is simple and easy to implement, and can quickly and directly separate the solder product and the copper-containing raw material, realize the separation and enrichment of copper and tin, and can obtain a solder product with a recovery rate of 96%. The residual tin in the obtained copper slag is only about 0.5-1.5%, which can be sold as a high-grade copper raw material for added value.

[0025] (2) Compared with the existing acid dissolution method or full smelting method for recovering copper-tin heavy sand, the separation method of the present invention does not require the consumption of reagents such as acid, nor does it require high-temperature treatment. It can effectively avoid problems such as serious environmental pollution and high production costs. It can quickly and directly produce solder products and recover copper raw materials at low cost and high efficiency, and has good environmental and economic benefits.

[0026] (3) In the separation method of the present invention, the flux used can be recycled, which helps to further reduce the separation processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention discloses a flow chart of a method for separating copper and tin in copper-tin heavy sand. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0029] Example 1

[0030] The method for separating copper and tin in the copper-tin heavy sand of the present embodiment comprises the following steps:

[0031] Step 1: Take a sample from the copper-tin heavy sand product obtained by the shaker gravity selection of the disassembled circuit board, and dry it to obtain 20 kg of copper-tin heavy sand (containing Cu 67.5%, Sn 30%, H2O 1.5%).

[0032] Step 2: Use a 40-mesh screen to make a bucket screen (as a screen bucket) with a diameter of 200 mm, a height of 150 mm, a flat bottom at the lower end, and a rotatable handle at the upper end, and add 4 kg / batch of shaking copper-tin heavy sand into the bucket screen;

[0033] Use a stainless steel barrel with a diameter of 250mm and a height of 200mm, put 4kg of rosin into it and place it on an electric furnace to heat and melt it. After the rosin is completely melted and the temperature rises to 280℃, adjust the electric furnace to control the temperature of the rosin melt to remain at 280℃, put the bucket sieve filled with copper-tin heavy sand into the molten rosin melt so that the copper-tin heavy sand is immersed, stir it with an iron rod for 60 minutes, and the copper-tin heavy sand will be loosely suspended, then stop stirring.

[0034] Step 3: Take out the bucket sieve of step 2 from the stainless steel barrel, and immediately and quickly put it into the drum of a centrifuge with a heating function. After fixing it, start the centrifuge, control the speed to 1400r / min, centrifuge for 10 minutes, and introduce the solder melt flowing out of the lower part of the centrifuge into the ingot mold. The solder melt is layered and cooled in the ingot mold to form an ingot with a rosin layer and a solder layer. Take out the ingot in the ingot mold, and knock off the rosin layer and the solder layer to obtain a solder product of 1.16kg / time and rosin, and return the rosin to step 2;

[0035] After the centrifuge drum stops, loosen and take out the bucket screen, pour out the copper slag powder material, and obtain 2.8 kg of copper slag material per time;

[0036] The above steps are repeated until 20 kg of copper-tin heavy sand is completely processed in the same manner as above.

[0037] The solder product obtained in the third step of the test contains 0.004% Cu, which meets the requirement of the national standard of my country's solder industry that the copper content is ≤ 0.08%. No further fine filtration and copper removal treatment is required to meet the requirements of the relevant standards, and the recovery rate of tin reaches 96%.

[0038] Comparative Example 1

[0039] Example 1 was repeated, except that the moisture content of the copper-tin heavy sand after drying was 5.5%.

[0040] The results showed that when the copper-tin heavy sand was immersed in the rosin melt in step 2, a high-temperature water explosion accident occurred, which shows the importance of controlling the copper-tin heavy sand to ensure safety.

[0041] Example 2

[0042] Example 1 was repeated, except that the bucket sieve was directly heated at 280° C. for 60 min instead of immersing it in the rosin melt.

[0043] The results showed that the tin recovery rate was only 30wt%. The possible reason was that, although the tin could be transformed into a melt without being immersed in the rosin melt, it was difficult to gather into large tin droplets, which made subsequent centrifugal separation difficult.

[0044] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A method for separating copper and tin in copper-tin heavy sand, characterized in that: The steps include: Step 1, drying the copper-tin heavy sand to be treated to obtain a material with a moisture content of ≤3wt%; Step 2: After the material is loaded into a screen barrel, it is placed in a flux melt at a temperature of 240-295° C. so that the material is immersed in the flux melt and stirred to make the material loose; The screen barrel comprises a barrel body, a plurality of screen holes are distributed on the side wall of the barrel body, and the aperture of the screen holes is smaller than the particle size of the copper-tin heavy sand; the flux comprises rosin; and the bottom plate of the barrel body is a flat plate; Step 3, taking out the material together with the screen bucket, and fixing the screen bucket in the drum of the centrifuge, centrifuging the material after the treatment in step 2 at 240-295° C. to obtain solder melt and copper slag rich in copper; The solder melt is placed in an ingot mold and after cooling, an ingot is obtained; wherein the ingot has a flux solidification layer and a solder layer distributed on the upper and lower sides.

2. The separation method according to claim 1, characterized in that In the copper-tin heavy sand to be treated, the content of copper is ≥50wt%; the content of tin is ≥20wt%.

3. The separation method according to claim 2, characterized in that The copper-tin heavy sand to be treated has a copper content of 55-75wt% and a tin content of 25-40wt%.

4. The separation method according to claim 3, characterized in that The copper-tin heavy sand to be treated has a copper content of 60-70wt% and a tin content of 30-35wt%.

5. The separation method according to claim 1, characterized in that The copper-tin heavy sand to be treated is dried to obtain a material with a moisture content of 1-2.5wt%.

6. The separation method according to claim 1, characterized in that The side wall of the barrel is made of screen.

7. The separation method according to claim 5, characterized in that The material of the screen is stainless steel.

8. The separation method according to claim 1, characterized in that The barrel body is cylindrical in shape.

9. The separation method according to claim 1, characterized in that The material of the flat plate is stainless steel.

10. The separation method according to claim 1, characterized in that The sieve has a hole diameter of 10-180 meshes.

11. The separation method according to claim 9, characterized in that: The sieve has a hole diameter of 20-60 meshes.

12. The separation method according to claim 10, characterized in that The aperture of the sieve hole is smaller than the particle size of the copper slag material.

13. The separation method according to claim 1, characterized in that Stirring time ≥15min.

14. The separation method according to claim 12, characterized in that: The stirring time is 25-90min.

15. The separation method according to claim 13, characterized in that: The stirring time is 30-75min.

16. The separation method according to claim 14, characterized in that The stirring time is 45-65min.

17. The separation method according to claim 1, characterized in that: During centrifugal separation, the speed is controlled at 1000-2000r / min and the time is 5-30min.

18. The separation method according to claim 16, characterized in that During centrifugal separation, the speed is controlled at 1200-1600r / min and the time is 10-20min.

19. The separation method according to claim 17, characterized in that: During centrifugal separation, the speed is controlled at 1300-1500r / min.

20. The separation method according to claim 1, characterized in that The centrifuge is a vertical centrifuge.

21. The separation method according to claim 1, characterized in that After the flux solidified layer and the solder layer of the ingot are physically separated, the flux solidified layer is returned and used as flux.

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