Method for recovering valuable components in copper tellurium slag
Through the combined method of oxidative roasting and vacuum carbon thermal reduction combined with electrodistribution, the problem of low recovery of valuable components in copper tellurium slag is solved, and efficient and low-cost recovery of tellurium and selenium is achieved, which is suitable for industrial applications.
Patent Information
- Application Number
- CN202510611134.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-13
- Publication Date
- 2025-08-26
AI Technical Summary
When the prior art recovers tellurium, copper and selenium from copper tellurium slag, there are problems such as high reagent consumption, difficulty in waste disposal, low recovery rate and large energy consumption, and the traditional process flow is lengthy and costly.
The method of oxidative roasting and vacuum carbon-thermal reduction combined with electrodistribution is adopted to achieve initial separation of Cu/Te and Se through oxidative roasting, and vacuum carbon-thermal reduction is used to replace traditional coke with biomass carbon, and then electrodischarge is carried out to recover selenium, simplifying the process flow and reducing energy consumption.
It has achieved efficient recycling of valuable components in copper tellurium slag, with tellurium recovery rate reaching 99%, selenium recovery rate reaching 99%, short process flow, suitable for industrial production, and reducing costs and energy consumption.
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Figure CN120536737A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of resource recycling and utilization, and particularly relates to a method for recovering valuable components in copper-tellurium slag. Background Art
[0002] Tellurium is widely used in high-tech fields such as photovoltaic materials and semiconductor components. Over 90% of the world's tellurium comes from copper-tellurium slag produced during the processing of copper-lead anode mud. This slag is primarily composed of Cu2Te and also contains rare and precious metals such as selenium, gold, and silver. Currently, the treatment processes for recovering tellurium from copper tellurium slag are still semi-wet processes, wet processes or pyrometallurgical processes. However, the semi-wet process is lengthy. Taking the semi-wet process of sulfuric acid roasting selenium evaporation-alkali leaching tellurium separation as an example, the steps are as follows: copper tellurium slag is mixed with concentrated sulfuric acid in a mass ratio of 1:1.2-1.5, roasted in a rotary kiln at 450-550°C for 2.5-3 hours, the roasting flue gas is captured by a two-stage alkaline liquid absorption tower, the roasted slag is leached in 80°C hot water at a liquid-to-solid ratio of 5:1 for 1 hour, excess copper powder is added to the leachate to generate Cu2Te precipitate through a replacement reaction, the leached slag is leached with sodium cyanide for 48 hours, and lime milk is added to the liquid after replacement to neutralize it to a pH value of 8-9. This method has high reagent consumption, the tellurium recovery rate is only 70% to 80%, and a large amount of hazardous waste residue is generated; the wet process involves incubating copper tellurium slag with H2SO4 in an autoclave at 180°C and an oxygen partial pressure of 0.8MPa for 4 hours to enhance the tellurium leaching rate to >95%. This process consumes a lot of reagents, has high wastewater treatment costs, makes selenium and tellurium separation difficult, and the tellurium recovery rate is 40%; the pyrometallurgical process steps are: leaching copper tellurium slag in 10% H2SO4, a liquid-solid ratio of 4:1, and atmospheric sulfuric acid at 80°C for 2 hours, mixing the leached slag with quartz sand and coke in a ratio of 1:0.3:0.1, and smelting at 1200-1300°C in a Kaldo furnace for 3 hours. After the smelting flue gas is absorbed by water, SO2 gas is introduced to reduce it to elemental selenium. The leaching solution is replaced by iron powder to recover sponge copper, and the residual liquid is neutralized. This process has high cost, high energy consumption, and severe waste gas pollution. Summary of the Invention
[0003] In view of this, an object of the present invention is to provide a method for recovering valuable components in copper-tellurium slag, which can recover tellurium, copper and selenium in high yield, and the recovered tellurium, copper and selenium are of high purity.
[0004] In order to achieve the above object, the present invention provides the following technical solutions:
[0005] The present invention provides a method for recovering valuable components in copper-tellurium slag, comprising the following steps:
[0006] The copper-tellurium slag is oxidized and roasted in oxygen to obtain copper-tellurium composite oxide and SeO2 flue gas;
[0007] The copper-tellurium composite oxide and biomass char are mixed and subjected to vacuum carbon thermal reduction reaction to obtain a residue and a tellurium-containing gas; the tellurium-containing gas includes volatile tellurium, CO2 and SO2;
[0008] The SeO2 flue gas is condensed, the obtained SeO2 solid is mixed with water, and the obtained selenious acid solution is subjected to electrolysis to obtain selenium.
[0009] Preferably, in terms of mass percentage, the copper-tellurium slag contains 30% to 50% Cu, 20% to 40% Te, 2% to 5% Se, 0.01% to 0.1% Au and Ag, and the rest O and S.
[0010] Preferably, the temperature of the oxidation roasting is 500-600° C., and the holding time is 1-2 hours; the heating rate to the oxidation roasting temperature is 5° C. / min.
[0011] Preferably, the mass ratio of the copper-tellurium composite oxide to the biomass carbon is 1:5-10.
[0012] Preferably, the vacuum degree of the vacuum carbothermal reduction reaction is 10-50 Pa.
[0013] Preferably, the vacuum carbon thermal reduction reaction is pyrolysis and reduction performed sequentially; the pyrolysis temperature is 300-500°C, and the pyrolysis holding time is 1-2 hours; the reduction temperature is 800-900°C, and the reduction holding time is 2-3 hours.
[0014] Preferably, the oxidation roasting is performed by passing oxygen into a tubular furnace containing copper tellurium slag for oxidation roasting; the flow rate of the oxygen is 1 to 1.5 L / min; and the pressure in the tubular furnace is 0.01 to 0.02 MPa.
[0015] Preferably, the conditions for the electrolytic deposition include: graphite as anode; stainless steel sheet as cathode; electrolyte system pH 1-4; current density 60-80 mA / cm 2 , voltage is 1.5~3V, and electrolysis time is 1~24h.
[0016] Preferably, the biomass charcoal includes one or more of rice straw charcoal, walnut shell charcoal, corn cob charcoal and sawdust charcoal.
[0017] Preferably, before the oxidation roasting, the copper tellurium slag is crushed and sieved to a particle size of ≤150 μm.
[0018] The present invention provides a method for recovering valuable components in copper-tellurium slag, comprising the following steps: oxidatively roasting the copper-tellurium slag in oxygen to obtain copper-tellurium composite oxide and SeO2 flue gas; mixing the copper-tellurium composite oxide with biochar and subjecting it to a vacuum carbon thermal reduction reaction to obtain a residue and a tellurium-containing gas; the tellurium-containing gas comprises volatile tellurium, CO2, and SO2; condensing the SeO2 flue gas, mixing the obtained SeO2 solid with water, and subjecting the obtained selenious acid solution to electrolysis to obtain selenium; the residue comprises Cu, Au, and Ag; and the elements in the copper-tellurium slag comprise Cu, Te, Se, Au, Ag, O, and S. Compared with the prior art, the advantages of the present invention are: (1) preliminary separation of Cu / Te and Se is achieved in one step through oxidative roasting, avoiding the lengthy multi-stage leaching-precipitation process in the traditional process, and the tellurium recovery rate can reach 99%. (2) waste biochar such as rice straw is used to replace traditional coke, achieving "waste treatment with waste" at a low cost. (3) The vacuum carbon thermal reduction reaction is used to reduce tellurium, and the vacuum environment is used to lower the reduction temperature and reduce energy consumption. (4) The environmentally friendly electrolytic method is creatively used to recover selenium, with a recovery rate of up to 99%. (5) The process flow is short (shorter by 3-4 steps than the semi-wet process), the reaction conditions are mild, and the operation is simple, making it suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 The present invention provides a schematic flow diagram of a method for recovering valuable components in copper-tellurium slag. DETAILED DESCRIPTION
[0020] The present invention provides a method for recovering valuable components in copper-tellurium slag, comprising the following steps:
[0021] The copper-tellurium slag is oxidized and roasted in oxygen to obtain copper-tellurium composite oxide and SeO2 flue gas;
[0022] The copper-tellurium composite oxide and biochar are mixed and subjected to vacuum carbon thermal reduction reaction to obtain a residue and a tellurium-containing gas; the tellurium-containing gas includes volatile tellurium, CO2 and SO2;
[0023] The elements in the copper tellurium slag include Cu, Te, Se, Au, Ag, O and S.
[0024] The SeO2 flue gas is condensed, the obtained SeO2 solid is mixed with water, and the obtained selenious acid solution is subjected to electrolysis to obtain selenium.
[0025] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art can be used.
[0026] The present invention oxidizes and roasts copper-tellurium slag in oxygen to obtain copper-tellurium composite oxide and SeO2 fume.
[0027] As an embodiment, the elements in the copper tellurium slag include Cu, Te, Se, Au, Ag, O and S.
[0028] Calculated by mass percentage, the copper-tellurium slag contains 30% to 50% Cu, 20% to 40% Te, 2% to 5% Se, 0.01% to 0.1% Au and Ag, and the rest O and S.
[0029] As an embodiment, before the oxidative roasting, the copper tellurium slag is crushed and sieved to a particle size of ≤150 μm; as an embodiment, before the oxidative roasting, the oxygen is dried.
[0030] As an embodiment, the oxidative roasting is to introduce oxygen into a tubular furnace containing copper tellurium slag for oxidative roasting; the oxygen introduction rate can be 1 to 1.5 L / min, specifically 1 L / min, 1.1 L / min, 1.2 L / min, 1.3 L / min, 1.4 L / min or 1.5 L / min; the pressure in the tubular furnace is 0.01 to 0.02 MPa.
[0031] As an embodiment, the purity of the oxygen is ≥99.5%.
[0032] As an embodiment, the temperature of the oxidative roasting can be 500-600°C, specifically 500°C, 550°C, 600°C or 700°C, and the holding time is 1-2h, specifically 1h, 1.5h or 2h; the heating rate to the oxidative roasting temperature is 5°C / min.
[0033] After obtaining the copper-tellurium composite oxide, the present invention mixes the copper-tellurium composite oxide with biomass charcoal and performs a vacuum carbon thermal reduction reaction to obtain a residue and a tellurium-containing gas; the tellurium-containing gas includes volatile tellurium, CO2 and SO2.
[0034] In one embodiment, the biochar may include one or more of rice straw charcoal, walnut shell charcoal, corn cob charcoal, and sawdust charcoal, and the mass ratio of the copper-tellurium composite oxide to the biochar may be 1:5 to 10, specifically 1:5, 1:8, or 1:10. In one embodiment, the biochar is obtained by vacuum pyrolysis of biomass.
[0035] As an embodiment, the vacuum degree of the vacuum carbothermal reduction reaction may be 10-50 Pa, specifically 10 Pa, 20 Pa, 30 Pa, 40 Pa or 50 Pa. As an embodiment, the vacuum carbothermal reduction reaction is a sequential pyrolysis and reduction.
[0036] As an embodiment, the pyrolysis temperature can be 300-500°C, specifically 300°C, 400°C, 450°C or 500°C; the heating rate to the pyrolysis temperature can be 5°C / min; the pyrolysis holding time can be 1-2h, specifically 1h, 1.5h, 1.75h or 2h.
[0037] As an embodiment, the reduction temperature can be 800-900°C, specifically 800°C, 850°C or 900°C; the heating rate to the reduction temperature can be 5°C / min; the reduction holding time can be 2-3h, specifically 2h, 2.5h or 3h.
[0038] In the present invention, the core reaction of the oxidative roasting is:
[0039] Cu2Te+2O2=2CuO+TeO2;
[0040] The core reaction of vacuum carbothermal reduction is:
[0041] TeO2+2C=Te↑+CO2↑;
[0042] 2CuO+2C=2Cu+CO2↑
[0043] CuSO4+C=Cu+CO2↑+SO2↑
[0044] The present invention condenses the SeO2 flue gas, mixes the obtained SeO2 solid with water, and performs electrolysis on the obtained selenious acid solution to obtain selenium.
[0045] As an embodiment of the present invention, the current density of the electrolysis can be 50 to 100 mA / cm, specifically 50 mA / cm, 75 mA / cm or 100 mA / cm; the voltage value can be 1.5 to 3 V, specifically 2 V, 2.5 V or 3 V; and the electrolysis time is 1 to 24 h, specifically 5 h.
[0046] As an embodiment of the present invention, after the electrolysis, the cathode product is further washed with deionized water and then dried; the number of washings is preferably 3 times, the drying temperature can be 60-80°C, and the drying time can be 2-3 hours.
[0047] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention, but they should not be understood as limiting the scope of protection of the present invention.
[0048] The biochar in the embodiment is obtained by vacuum pyrolysis of biomass.
[0049] Example 1
[0050] Copper tellurium slag was obtained from a copper smelter in Yunnan Province. Its composition is: Cu 31wt.%, Te 40wt.%, Se 2wt.%, gold and silver impurities 0.05%, and the rest O and S.
[0051] The copper-tellurium slag was crushed and sieved to a particle size of ≤150 μm. 20 g of the copper-tellurium slag with a particle size of ≤150 μm was placed in a quartz boat, placed in a tube furnace, and oxygen was introduced at a flow rate of 1.1 L / min to a pressure of 0.02 MPa. The furnace was then calcined at 500°C (the heating rate to 500°C was 5°C / min) for 1.5 h to obtain a solid product and SeO2 flue gas.
[0052] The solid product was analyzed by XRD to be copper-tellurium composite oxide; the selenium volatilization rate reached 99%.
[0053] Copper-tellurium composite oxide and rice straw charcoal were mixed in a mass ratio of 1:5 and placed in a vacuum reactor for pyrolysis (pyrolysis stage parameters: vacuum degree of 10 Pa, heating to 450°C at a rate of 5°C / min, holding time of 1.5 h) and reduction (reduction stage: vacuum degree of 10 Pa, heating from 450°C to 800°C at a rate of 5°C / min, holding time of 2.5 h) to obtain a residue and tellurium-containing gas (volatile tellurium and CO2, SO2); the residue was copper and a small amount of Au and Ag;
[0054] The tellurium-containing gas was condensed at 250°C and the metallic tellurium was collected.
[0055] After SeO2 flue gas is condensed, it is mixed with water to obtain a selenious acid solution with a concentration of 0.1 mol / L. The pH is adjusted to 2, and electrolysis is performed with graphite (anode) and stainless steel sheet (cathode) at a current density of 50 A / m 2 , voltage 1.5V, electrolysis 5h, the cathode precipitated product was washed 3 times with deionized water and dried at 60℃ to obtain selenium element.
[0056] According to inductively coupled plasma atomic emission spectroscopy (ICP-AES) detection, the tellurium purity was 99.99% and the recovery rate was 99%; the copper purity in the residue was 99% and the recovery rate was 99%; the selenium purity was 99.9% and the selenium recovery rate was 99.2%.
[0057] Example 2
[0058] The copper tellurium slag composition is: Cu 35wt.%, Te 40wt.%, Se 3.5wt.%, Ag and Au 0.02%, and the rest is O and S.
[0059] The copper tellurium slag was crushed and sieved to a particle size of ≤125 μm. 20 g of copper tellurium slag with a particle size of ≤125 μm was placed in a quartz boat, placed in a tube furnace, and oxygen was introduced (flow rate 1.3 L / min) to a pressure of 0.02 MPa. The temperature was raised to 550°C at a rate of 5°C / min and calcined for 1.75 h to obtain a solid product and SeO2 flue gas.
[0060] The solid product was analyzed by XRD to be copper-tellurium composite oxide; the selenium volatilization rate reached 99%.
[0061] Copper-tellurium composite oxide and corn cob carbon were mixed in a mass ratio of 1:8 and subjected to pyrolysis (heating at 5°C / min to 500°C and holding for 2 hours, vacuum degree of 20 Pa) and reduction (heating at 5°C / min to 850°C and holding for 2 hours, vacuum degree of 20 Pa) in sequence to obtain a residue and tellurium-containing gas (volatile tellurium and CO2, SO2); the residue was copper and a small amount of Au and Ag;
[0062] The tellurium-containing gas was condensed at 250°C and the metallic tellurium was collected.
[0063] After SeO2 flue gas is condensed, it is mixed with water to obtain a 0.1 mol / L selenious acid solution, which is adjusted to pH 3. Electrolysis is performed using graphite (anode) and stainless steel sheet (cathode) at a current density of 75 A / m 2 , voltage 1.8V, electrolysis 5h, the cathode precipitated product was washed three times with deionized water and dried at 60℃ to obtain selenium;
[0064] According to inductively coupled plasma atomic emission spectroscopy (ICP-AES) detection, the tellurium purity is 99.99% and the tellurium recovery rate is 99%; the copper purity in the residue is 99% and the recovery rate is 99%; the selenium purity is 99.9% and the selenium recovery rate is 99.2%.
[0065] Example 3
[0066] The main components of copper tellurium slag are: Cu 33wt.%, Te 25wt.%, Se 4wt.%, Au and Ag 0.03%, and the rest are O and S.
[0067] The copper-tellurium slag was crushed and sieved to a particle size of ≤100 μm. 20 g of the copper-tellurium slag with a particle size of ≤100 μm was placed in a quartz boat, which was then placed in a tube furnace. Oxygen (flow rate 1.5 L / min) was introduced to a pressure of 0.02 MPa. The temperature was raised to 600°C at a rate of 5°C / min and calcined for 2.0 h to obtain a solid product and SeO2 fume.
[0068] XRD analysis shows that the solid product is a mixture of CuO and TeO2, namely copper-tellurium composite oxide; the selenium volatilization rate reaches 99%.
[0069] Copper-tellurium composite oxide and waste tea residue charcoal were mixed in a mass ratio of 1:10, and pyrolysis (vacuum degree 30 Pa, pyrolysis stage: heating to 500°C at 5°C / min, holding time for 2 hours) and reduction (vacuum degree 30 Pa, heating to 900°C at 5°C / min, holding time for 2 hours) was performed to obtain a residue and tellurium-containing gas (volatile tellurium and CO2, SO2); the residue was copper and a small amount of Au and Ag;
[0070] The tellurium-containing gas was condensed at 250°C and the metallic tellurium was collected.
[0071] After SeO2 flue gas is condensed, it is mixed with water to obtain a selenious acid solution with a concentration of 0.1 mol / L. The pH is adjusted to 4 and electrolysis is performed using graphite (anode) and stainless steel sheet (cathode) at a current density of 100 A / m 2 , voltage 2.0V, electrolysis 5h, the cathode precipitated product was washed three times with deionized water and dried at 60℃ to obtain selenium;
[0072] According to inductively coupled plasma atomic emission spectroscopy (ICP-AES) detection, the tellurium purity is 99.99% and the tellurium recovery rate is 93%; the copper purity in the residue is 99% and the recovery rate is 99%; the selenium purity is 99.9% and the selenium recovery rate is 99.2%.
[0073] Example 4
[0074] The copper tellurium slag composition is: Cu 40wt.%, Te 33wt.%, Se 5wt.%, and the rest is O and S.
[0075] The copper tellurium slag was crushed and sieved to a particle size of ≤75μm. 20g of copper tellurium slag with a particle size of ≤75μm was placed in a quartz boat, placed in a tube furnace, and oxygen was introduced (at a flow rate of 1.5L / min) to a pressure of 0.02MPa. The temperature was raised to 600℃ at a rate of 5℃ / min and calcined for 2.0h to obtain a solid product and SeO2 flue gas.
[0076] XRD analysis showed that the solid product was copper-tellurium composite oxide; the selenium volatilization rate reached 98%.
[0077] Copper-tellurium composite oxide and walnut shell charcoal were mixed in a mass ratio of 1:10 and subjected to pyrolysis (vacuum degree 40 Pa, pyrolysis stage: heating to 500°C at 5°C / min and holding for 2 hours) and reduction (vacuum degree 40 Pa, reduction stage: heating to 900°C at 5°C / min and holding for 2 hours) to obtain a residue and tellurium-containing gas (volatile tellurium and CO2, SO2); the residue was mainly copper and a small amount of Au and Ag;
[0078] The tellurium-containing gas was condensed at 250°C and the metallic tellurium was collected.
[0079] After SeO2 flue gas is condensed, it is mixed with water to obtain a selenious acid solution with a concentration of 0.1 mol / L. The pH is adjusted to 4 and electrolysis is performed using graphite (anode) and stainless steel sheet (cathode) at a current density of 100 A / m 2 , voltage 3.0V, electrolysis 5h, the cathode precipitated product was washed three times with deionized water and dried at 60℃ to obtain selenium;
[0080] According to inductively coupled plasma atomic emission spectroscopy (ICP-AES) detection, the tellurium purity is 99.99% and the recovery rate is 93%; the copper purity in the residue is 99% and the copper recovery rate is 99%; the selenium purity is 99.9% and the selenium recovery rate is 99.2%.
[0081] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.
Claims
1. A method for recovering valuable components in copper-tellurium slag, comprising the following steps: The copper-tellurium slag is oxidized and roasted in oxygen to obtain copper-tellurium composite oxide and SeO2 flue gas; The copper-tellurium composite oxide and biomass char are mixed and subjected to vacuum carbon thermal reduction reaction to obtain a residue and a tellurium-containing gas; the tellurium-containing gas includes volatile tellurium, CO2 and SO2; Condensing the SeO2 flue gas, mixing the obtained SeO2 solid with water, and subjecting the obtained selenious acid solution to electrolysis to obtain selenium; The residues include Cu, Au and Ag; The elements in the copper tellurium slag include Cu, Te, Se, Au, Ag, O and S.
2. The recycling method according to claim 1, wherein Calculated by mass percentage, the copper-tellurium slag contains 30% to 50% Cu, 20% to 40% Te, 2% to 5% Se, 0.01% to 0.1% Au and Ag, and the rest O and S.
3. The recycling method according to claim 1, wherein: The temperature of the oxidation roasting is 500-600° C., and the holding time is 1-2 hours; the heating rate to the oxidation roasting temperature is 5° C. / min.
4. The recovery method according to claim 1, 2 or 3, wherein: The mass ratio of the copper-tellurium composite oxide to the biomass carbon is 1:5-10.
5. The recycling method according to claim 1, wherein: The vacuum degree of the vacuum carbothermal reduction reaction is 10-50 Pa.
6. The recovery method according to claim 1 or 5, wherein: The vacuum carbon thermal reduction reaction is a sequential process of pyrolysis and reduction; the pyrolysis temperature is 300-500° C., and the pyrolysis holding time is 1-2 hours; the reduction temperature is 800-900° C., and the reduction holding time is 2-3 hours.
7. The recycling method according to claim 1, wherein: The oxidation roasting is carried out by introducing oxygen into a tubular furnace filled with copper tellurium slag for oxidation roasting; the flow rate of the oxygen is 1 to 1.5 L / min; and the pressure in the tubular furnace is 0.01 to 0.02 MPa.
8. The recycling method according to claim 1, characterized in that The conditions for the electrolytic deposition include: graphite as anode; stainless steel sheet as cathode; electrolyte system pH 1-4; current density 60-80 mA / cm 2 , voltage is 1.5~3V, and electrolysis time is 1~24h.
9. The recycling method according to claim 1 or 4, characterized in that: The biomass charcoal includes one or more of rice straw charcoal, walnut shell charcoal, corn cob charcoal and sawdust charcoal.
10. The recycling method according to claim 1, characterized in that: Before the oxidation roasting, the copper tellurium slag is crushed and sieved to a particle size of ≤150 μm.