Method for extracting copper and selenium step by step through low-temperature sulfating roasting of copper anode slime

Abstract

The invention belongs to the field of comprehensive utilization of resources, and discloses a method for extracting copper and selenium step by step through low-temperature sulfating roasting of copper anode slime. The method comprises the steps that the copper anode slime and sulfate are evenly mixed, and first-stage sulfating roasting is conducted at the temperature of 200-350 DEG C; the obtained roasted product is subjected to water leaching, and a copper sulfate solution and water leaching residues are obtained; and mixing the water leaching residues with sulfate, carrying out second-stage sulfating roasting at 450-550 DEG C, and collecting selenium-containing oxide. According to the method, first-stage low-temperature sulfating roasting is carried out, the copper anode slime reacts with sulfate to generate metal sulfur oxide, copper exists in the roasted product in the form of copper sulfate, separation of copper and other elements can be achieved through water leaching, the purpose of preferentially extracting copper is achieved, and the copper recovery rate can reach 94% or above; second-stage low-temperature sulfating roasting is carried out, water leaching residues react with sulfate to generate selenium oxide, selenium volatilizes in the form of gas, separation of selenium and other elements can be achieved through collection, and the volatilization rate of selenium can reach 97% or above.

Description

Technical Field

[0001] The present invention belongs to the field of comprehensive utilization of resources, and particularly relates to a method for stepwise extracting copper and selenium by low-temperature sulfation roasting of copper anode slime. Background Art

[0002] Copper anode slime is a by-product generated during the refining of blister copper, accounting for about 0.2-0.8% of the blister copper amount. It usually contains a variety of valuable metals, such as Cu, Se, Te, Pb, Ba, Au, Ag, etc., and is an important resource library for extracting metals such as copper and selenium. Copper, as an important strategic metal, is a key supporting material for the industrial development of our country. With its excellent electrical conductivity, thermal conductivity and ductility, it is widely used in many fields such as electric power, transportation, construction, metallurgy, machinery, etc. At present, the reserves of copper ore resources in our country are limited, the grade is low, the mining difficulty is large, the domestic demand is high, and the external dependence is high, resulting in a significant resource tension situation. Therefore, recovering metallic copper from copper-containing waste materials is of great significance for the sustainable development of the copper industry. Selenium is a typical rare and scattered metal and is a key metal for the development of strategic emerging industries in our country. Selenium and its compounds have excellent properties and are widely used in industrial fields such as metallurgy, chemical industry, electronics, glass ceramics and medicine. However, selenium is scarce and dispersed in the earth's crust, with an abundance of only 5×10 -8 , making it difficult to be industrially enriched on a large scale. At present, the main source of selenium is recovered from various heavy metal smelting anode slimes, such as copper anode slime, lead-nickel anode slime, etc., and 90% of the selenium in the market comes from the recycling of copper anode slime.

[0003] At present, there are many methods for recovering copper and selenium metals from copper anode slime, mainly including the Kaldo furnace pyrometallurgical process, the semi-wet process, the full-wet process, etc. In the Kaldo furnace pyrometallurgical process, the recovery rate of selenium can reach 90%. The selenium-rich slag produced by this process still needs to be returned to the smelting furnace for the recovery of valuable metals such as copper, and the process flow is complex and the cost is high. The semi-wet process includes oxidation roasting, soda roasting, sulfuric acid roasting, etc. Its principle is mainly to use an oxidant to convert copper selenide and silver selenide compounds in copper anode slime into selenate and selenite. In a high-temperature environment, selenate and selenite decompose to produce SeO2 gas, thereby realizing the efficient recovery of selenium. The roasted product is leached with water or acid to recover metallic copper. Currently, sulfuric acid roasting and selenium evaporation is one of the mainstream processes for recovering copper and selenium from copper anode slime. For example, the patent application with the publication number CN 118702070 A discloses a selenium recovery system and its recovery method for copper anode slime, specifically discloses that after adding concentrated sulfuric acid in the sulfuric acid storage tank and copper anode slime into the centralized pulping tank for pulping reaction, it is then sent to a rotary kiln for heating and roasting. The selenium-containing flue gas generated by roasting is successively passed through a first-stage selenium production tower, a second-stage selenium production tower, and a third-stage selenium production tower for selenium production reaction, respectively obtaining crude selenium A, crude selenium B, and crude selenium C. Finally, crude selenium A, crude selenium B, and crude selenium C are fed into a secondary selenium production reaction kettle to obtain a crude selenium product D. This method uses concentrated sulfuric acid as an oxidant for low-temperature roasting and selenium evaporation, with a high selenium recovery rate and low energy consumption. However, the use of concentrated sulfuric acid is prone to corrode process equipment, increasing the maintenance cost, and will generate a large amount of SO2 gas, increasing the subsequent process treatment load. The full-wet process mainly leaches copper and selenium in copper anode slime with strong acid, and its recovery process is easy to control and has a high recovery rate. However, a large amount of waste liquid will be generated during the leaching process, and the wastewater needs to be further treated. For example, the patent application with the publication number CN 117344138 A discloses a full-wet step-by-step high-efficiency separation and recovery method for copper, selenium, and tellurium from copper anode slime, specifically discloses that copper anode slime is sulfurized and separated from tellurium using sodium sulfide, then oxygen pressure alkali leaching is used to separate selenium, and finally sulfuric acid leaching is used to separate copper. Although this method has a high metal separation degree, the recovery of selenium requires pressure leaching, and the process cost is high. Chinese invention patent CN 118932176 A discloses a full-wet step-by-step extraction method for copper, selenium, gold, and silver from copper anode slime, specifically discloses that metallic copper in copper anode slime is leached using a potassium persulfate solution, then a mixed leaching agent such as hydrogen peroxide, sulfuric acid, and sodium chloride is used to extract selenium from the copper-depleted anode slime, and finally thiourea, sulfuric acid, and an oxidant are used to leach gold and silver from the selenium-depleted slag. Although this method has a relatively high recovery rate for various valuable metals such as copper and selenium, the process is complex, and a large amount of wastewater is generated during multi-stage leaching, and the wastewater needs to be further treated.

[0004] Therefore, it is necessary to develop a method for recovering copper and selenium from copper anode slime with good selectivity, high metal recovery rate, and low process cost. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology, and provide a method for stepwise extracting copper and selenium by low-temperature sulfation roasting of copper anode slime.

[0006] To solve the above technical problem, the technical solution proposed by the present invention is: A method for stepwise extracting copper and selenium by low-temperature sulfation roasting of copper anode slime, comprising the following steps: (1) Uniformly mix copper anode slime with sulfate, and perform first-stage sulfation roasting at 200 - 350 °C; (2) Leach the roasting product obtained in step (1) with water to obtain a copper sulfate solution and a water leaching residue; (3) Mix the water leaching residue obtained in step (2) with sulfate, and perform second-stage sulfation roasting at 450 - 550 °C to collect selenium-containing oxides.

[0007] In the above method for stepwise extracting copper and selenium by low-temperature sulfation roasting of copper anode slime, preferably, in step (1), the sulfate is at least one of (NH4)2SO4, Na2SO4, NaHSO4, K2SO4, FeSO4, and the mass ratio of the copper anode slime to the sulfate is 1:0.16 - 0.64. The mass ratio of copper anode slime to sulfate needs to be controlled within the preferred range of the present invention. If the amount of sulfate used is too large, it will increase the raw material cost and the amount of water leaching residue; if the amount of sulfate used is too small, it will be difficult to realize the conversion of copper into the form of copper sulfate, thus affecting the recovery rate of copper.

[0008] In the above method for stepwise extracting copper and selenium by low-temperature sulfation roasting of copper anode slime, preferably, in step (1), the first-stage sulfation roasting is carried out in an atmosphere with an oxygen enrichment concentration of 10% - 60%. The oxygen enrichment concentration of sulfation roasting within the scope of the present invention can ensure complete reaction. If the oxygen enrichment concentration is too high, it will increase the peroxidation of copper into water-insoluble compounds, reducing the leaching rate of copper; if the oxygen enrichment concentration is too low, the reaction will be incomplete. The time of sulfation roasting is 30 min - 90 min. The sulfation roasting time within this range can ensure complete reaction. If the roasting time is too long, it will increase energy consumption; if the roasting time is too short, the reaction will be incomplete.

[0009] In the above method for stepwise extracting copper and selenium by low-temperature sulfation roasting of copper anode slime, preferably, in step (2), the temperature of water leaching is 40 - 90 °C, the liquid-solid ratio of water leaching is 3 - 15:1 (the ratio unit is mL / g), and the time of water leaching is 30 - 120 min.

[0010] For the above method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime, preferably, in step (3), the secondary sulfation roasting is carried out in an atmosphere with an oxygen enrichment concentration of 10%-60%, and the roasting time of the low-temperature sulfation roasting is 20 min - 120 min. The sulfation roasting time within this range can ensure complete reaction. If the roasting time is too long, it will increase energy consumption; if the roasting time is too short, the reaction will be incomplete.

[0011] For the above method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime, preferably, in step (3), the sulfate is at least one of (NH4)2SO4, Na2SO4, NaHSO4, K2SO4, FeSO4, and the mass ratio of the water-leached residue to the sulfate is 1:0.2 - 0.8. The mass ratio of the water-leached residue to the sulfate needs to be controlled within the preferred range of the present invention. If the amount of sulfate used is too much, the raw material cost will increase; if the amount of sulfate used is too little, it is difficult to realize the phase transformation of selenium into selenium oxide, thus affecting the recovery rate of selenium.

[0012] For the above method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime, preferably, the main components of the copper anode slime include Se 5 - 20 wt%, Te 2 - 8 wt%, Pb 2 - 6 wt%, and Au 0.1 - 1.2 wt%.

[0013] The invention principle of the present invention is as follows: The present invention mixes copper anode slime and sulfate evenly for the first-stage low-temperature sulfation roasting to realize the phase transformation of copper into copper sulfate. According to the water solubility of the roasting product, water leaching of the roasting product can achieve the separation of copper; the water-leached residue and sulfate are evenly mixed for the second-stage low-temperature sulfation roasting to realize the phase transformation of selenium into selenium oxide, and under high-temperature conditions, according to the volatility of selenium oxide, the separation of selenium can be achieved.

[0014] In a section of the low-temperature sulfation roasting product of the present invention, copper exists in the form of copper sulfate and is easily soluble in water. Copper separation can be achieved through simple water leaching and filtration. When the roasting temperature of the first stage is 275 °C, it can be seen from the XRD pattern of the roasting product that copper exists in the form of sulfate. After water leaching, such peak shapes disappear. Combining the chemical analysis of the water leaching solution, it can be known that at this time, the reaction temperature reaches the temperature condition required for the transformation in the first-stage roasting, and the transformation effect is good. When the roasting temperature of the first stage is 400 °C, the copper sulfate phase peak in the water leaching product completely disappears, indicating that the water leaching process can ensure that the generated copper sulfate enters the solution; however, there is a characteristic peak of CuSe2 in the water leaching product. Combining the analysis of the water leaching solution, it can be known that under this roasting temperature condition, part of the copper has achieved phase transformation to copper sulfate, and part of the copper exists in the form of copper selenide compounds, indicating that during the low-temperature sulfation roasting process of the first stage, too high a temperature is not conducive to the phase transformation of copper, and part of the selenium volatilizes. Therefore, the temperature of the first-stage low-temperature sulfation roasting in this application is 200-350 °C; if the roasting temperature is too low or too high, the roasting product contains untransformed copper selenide compounds respectively, which affects the copper recovery rate and is not conducive to the subsequent water leaching operation.

[0015] The present invention mixes the water leaching residue and sulfate for sulfation roasting to achieve the phase transformation of selenium into selenium oxide, and then selenium can be separated by steam collection. The applicant has found through research that the temperature of sulfation roasting needs to be controlled within the preferred range of the present invention. When the roasting temperature is relatively low, such as 400 °C, the reaction is not complete at this low roasting temperature, and the structure of some silver selenide compounds is not destroyed, making it difficult to achieve the full conversion of the selenium phase, and thus affecting the selenium volatilization rate; in addition, under this roasting temperature condition, most of the tellurium still exists in the form of metal compounds, which is not conducive to the subsequent chlorination leaching of tellurium. When the roasting temperature is 550 °C, the peak intensity of the silver selenide compound weakens, indicating that selenium has been effectively volatilized, and there is a significant TeO2 phase peak in the XRD pattern, laying a foundation for the subsequent recovery of the rare-dispersed metal tellurium; when the roasting temperature is too high, such as 600 °C, the TeO2 phase peak disappears in the XRD pattern of the sulfation roasting product, which is not conducive to the subsequent chlorination leaching of tellurium and increases the energy consumption.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention first conducts low-temperature sulfation roasting in the first stage, uses copper anode slime to react with sulfate to generate metal sulfur oxides, so that copper exists in the roasting product in the form of copper sulfate, and copper can be separated from other elements through water leaching to achieve the purpose of preferentially extracting copper, and the copper recovery rate can reach more than 94%; then conducts low-temperature sulfation roasting in the second stage, uses the water leaching residue to react with sulfate to generate selenium oxide, and selenium volatilizes in the form of gas, and selenium can be separated from other elements through collection, and the selenium volatilization rate can reach more than 97%.

[0017] (2) The present invention treats copper anode slime through sulfation roasting, with a simple operation process, little pollution, easy control, and is suitable for industrial application; it overcomes the problems existing in the recovery of valuable metals from copper anode slime by traditional wet and pyrometallurgical processes, such as large acid consumption, long process flow, high energy consumption, and high equipment maintenance costs.

[0018] In summary, the method for stepwise extraction of copper and selenium from copper anode slime by low-temperature sulfation roasting in the present invention can achieve the preferential and efficient extraction of valuable metals copper and selenium from copper anode slime, with a short process flow, and eliminates the problems such as high energy consumption, acid corrosion, and large amount of wastewater generation existing in traditional pyrometallurgical and wet processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the process flow diagram of stepwise extraction of copper and selenium from copper anode slime by low-temperature sulfation roasting in the present invention.

[0020] Figure 2 It is the XRD patterns of the roasting products and water leaching products of the first-stage sulfation roasting of copper anode slime in the present invention at 275 °C and 400 °C.

[0021] Figure 3 It is the XRD patterns of the roasting products of the second-stage sulfation roasting of copper anode slime without copper in the present invention at 400 °C, 550 °C, and 600 °C. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the accompanying drawings of the specification and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0024] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0025] Example 1: The method for stepwise extraction of copper and selenium from copper anode slime by low-temperature sulfation roasting in the present invention includes the following steps: (1) Uniformly mix copper anode slime and ammonium sulfate in a mass ratio of 1:0.5, and conduct low-temperature roasting at 275 °C for 90 min; at the same time, conduct a parallel test, and roast at 400 °C under the condition of an oxygen enrichment concentration of 50% for 90 min; (2) The calcined product obtained in step (1) is subjected to separate water leaching. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, and the water leaching is carried out for 120 min to obtain a copper sulfate solution and a water leached residue; the XRD patterns of the calcined product and the water leached product are shown in Figure 2 as follows; (3) The water leached residue obtained in step (2) (calcined once at 275 °C) is mixed with ammonium sulfate in a mass ratio of 1:0.4, and then divided into three portions for parallel experiments. They are calcined at 400 °C, 550 °C, and 600 °C respectively under the condition of an oxygen enrichment concentration of 50% for 50 min. The XRD pattern of the calcined product is shown in Figure 3 as follows.

[0026] As Figure 2 shown, when the first-stage calcination temperature is 275 °C, it can be seen from the XRD pattern of the calcined product that copper exists in the form of sulfate. After water leaching, such peak shapes disappear. Combining the chemical analysis of the water leached solution, it can be known that at this time, the reaction temperature reaches the temperature condition required for the first-stage calcination transformation, and the transformation effect is better. When the first-stage calcination temperature is 400 °C, the copper sulfate phase peak in the water leached product completely disappears, indicating that the water leaching process can ensure that the generated copper sulfate enters the solution; however, there is a characteristic peak of CuSe2 in the water leached product. Combining the analysis of the water leached solution, it can be known that under this calcination temperature condition, part of the copper has undergone a phase transformation to copper sulfate, and part of the copper exists in the form of copper selenide compounds, indicating that during the first-stage low-temperature sulfation roasting process, too high a temperature is not conducive to the phase transformation of copper, and part of the selenium volatilizes.

[0027] As Figure 3 shown, when the calcination temperature is relatively low, such as 400 °C, the reaction is not complete at this time because the calcination temperature is too low, and the structure of some silver selenide compounds is not destroyed, making it difficult to achieve the full conversion of the selenium phase, thereby affecting the selenium volatilization rate; in addition, under this calcination temperature condition, most of the tellurium still exists in the form of metal compounds, which is not conducive to the subsequent chlorination leaching of tellurium. When the calcination temperature is 550 °C, the peak intensity of the silver selenide compound weakens, indicating that selenium has been effectively volatilized, and there is a significant TeO2 phase peak in the XRD pattern, laying a foundation for the subsequent recovery of the rare metal tellurium; when the calcination temperature is too high, such as 600 °C, the TeO2 phase peak in the XRD pattern of the sulfation roasting product disappears, which is not conducive to the subsequent chlorination leaching of tellurium and increases energy consumption.

[0028] Example 2: A method for stepwise extracting copper and selenium from copper anode slime by low-temperature sulfation roasting according to the present invention, the process flow chart of which is shown in Figure 1 as follows, including the following steps: (1) Accurately weigh 5 g of copper anode slime and 2.4 g of ammonium sulfate, mix them well and put them into a corundum crucible; (2) Place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration during roasting is 50%. Control the temperature of sulfation roasting at 300 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace; (3) Take out 4 g of the roasted product and perform a single water leaching on the roasted product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, and leach for 120 min. After the water leaching is completed, filter to obtain copper sulfate solution and water leaching residue respectively. After detection, the leaching rate of copper after water leaching is 89.42%, and the selenium volatilization rate during the roasting process is 1.03%. The copper sulfate solution is purified and then enters the copper electrolysis system to obtain cathode copper products.

[0029] (4) Accurately weigh 2.5 g of the water leaching residue obtained in step (3) and 1.5 g of ammonium sulfate. After fully mixing, put them into a corundum crucible. Place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration during roasting is 50%. Control the temperature of sulfation roasting at 600 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace and collect selenium oxides; after detection, the selenium volatilization rate during the roasting process is 97.67%. The collected selenium oxides are reduced, and the obtained crude selenium is refined into elemental selenium products. Comparative Example 1: The method for roasting and extracting copper and selenium from copper anode slime in this comparative example includes the following steps: (1) Accurately weigh 5 g of copper anode slime and 2.4 g of ammonium sulfate. After fully mixing, put them into a corundum crucible; (2) Place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration during roasting is 50%. Control the temperature of sulfation roasting at 500 °C and the roasting time at 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace; (3) Take out 4 g of the roasted product and perform a single water leaching on the roasted product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, and the leaching time is 120 min; filter to obtain copper sulfate solution and water leaching residue respectively. After detection, the leaching rate of copper after water leaching is 31.15%, and the selenium volatilization rate during the roasting process is 88.07%.

[0030] (4) Accurately weigh 2.5 g of the water leaching residue obtained in step (3) and 1.5 g of ammonium sulfate. After fully mixing, put them into a corundum crucible. Place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration during roasting is 50%. Control the temperature of sulfation roasting at 600 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace and collect selenium oxides; after detection, the selenium volatilization rate during the roasting process is 98.01%.

[0031] Comparative Example 2: The method for roasting and extracting copper and selenium from copper anode slime in this comparative example includes the following steps: (1)Accurately weigh 5 g of copper anode slime and 2.4 g of ammonium sulfate, mix them thoroughly and put them into a corundum crucible; (2)Place the corundum crucible into a tubular furnace for sulfation roasting. The oxygen-enriched concentration for roasting is 50%. Control the temperature of sulfation roasting at 300 °C, roast for 90 min, and after the roasting reaction is completed, cool it to room temperature with the furnace; (3)Take out 4 g of the roasted product, perform a first water leaching on the roasted product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, leach for 120 min, and after the water leaching is completed, filter to obtain copper sulfate solution and water leaching residue respectively.

[0032] (4)Weigh 2.5 g of the water leaching residue and put it into a corundum crucible. Place the corundum crucible into a tubular furnace for roasting. The oxygen-enriched concentration for roasting is 50%. Control the temperature of sulfation roasting at 600 °C, roast for 90 min, and after the roasting reaction is completed, cool it to room temperature with the furnace. After detection, the volatilization rate of selenium during roasting is 77.64%.

[0033] Example 3: A method for stepwise extracting copper and selenium from copper anode slime by low-temperature sulfation roasting of the present invention, the process flow chart is as Figure 1 shown, including the following steps: (1)Accurately weigh 5 g of copper anode slime, 1.2 g of (NH4)2SO4 and 1.5 g of Na2SO4, mix them thoroughly and put them into a corundum crucible; (2)Place the corundum crucible into a tubular furnace for sulfation roasting. The oxygen-enriched concentration for roasting is 50%. Control the temperature of sulfation roasting at 275 °C, roast for 90 min, and after the roasting reaction is completed, cool it to room temperature with the furnace; (3)Take out 4 g of the roasted product, perform a first water leaching on the roasted product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, leach for 120 min, and after the leaching is completed, filter to obtain copper sulfate solution and water leaching residue. After detection, the leaching rate of copper after water leaching is 94.07% respectively, and the volatilization rate of selenium during roasting is 0%. After the copper sulfate solution is purified and treated, it enters the copper electrolysis system to obtain cathode copper products.

[0034] (4)Accurately weigh 2.5 g of the water leaching residue obtained in step (3), 0.7 g of (NH4)2SO4 and 0.8 g of Na2SO4, mix them thoroughly and put them into a corundum crucible; place the corundum crucible into a tubular furnace for sulfation roasting. The oxygen-enriched concentration for roasting is 50%. Control the temperature of sulfation roasting at 550 °C, roast for 90 min, and after the roasting reaction is completed, cool it to room temperature with the furnace, and collect selenium oxides; after detection, the volatilization rate of selenium during roasting is 99.27%. The collected selenium oxides are reduced, and the obtained crude selenium is refined into elemental selenium products. Comparative Example 3: The method for roasting and extracting copper and selenium from copper anode slime in this comparative example includes the following steps: (1) Accurately weigh 5 g of copper anode slime, 1.2 g of (NH4)2SO4, and 1.5 g of Na2SO4. After fully mixing, put them into a corundum crucible; (2) Place the corundum crucible into a tubular furnace for sulfation roasting. The oxygen-rich concentration during roasting is 50%. Control the temperature of sulfation roasting at 400 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace; (3) Take out 4 g of the roasted product and perform primary water leaching on the roasted product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, and the leaching time is 120 min. After filtration, copper sulfate solution and water leaching residue are obtained respectively. After detection, the leaching rate of copper after water leaching is 58.51%, and the volatilization rate of selenium during the roasting process is 56%.

[0035] (4) Accurately weigh 2.5 g of the water leaching residue obtained in step (3), 0.7 g of (NH4)2SO4, and 0.8 g of Na2SO4. After fully mixing, put them into a corundum crucible; Place the corundum crucible into a tubular furnace for sulfation roasting. The oxygen-rich concentration during roasting is 50%. Control the temperature of sulfation roasting at 425 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace and collect selenium oxide; After detection, the volatilization rate of selenium during the roasting process is 65.82%.

[0036] Example 4: A method for stepwise extracting copper and selenium from copper anode slime by low-temperature sulfation roasting, the process flow chart of which is as Figure 1 shown, includes the following steps: (1) Accurately weigh 5 g of copper anode slime, 1.2 g of (NH4)2SO4, and 1.5 g of Na2SO4. After fully mixing, put them into a corundum crucible; (2) Place the corundum crucible into a tubular furnace for sulfation roasting. The oxygen-rich concentration during roasting is 60%. Control the temperature of sulfation roasting at 275 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace; (3) Take out 5 g of the roasted product and perform primary water leaching on the roasted product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, and the leaching time is 120 min. After filtration, copper sulfate solution and water leaching residue are obtained respectively. After detection, the leaching rate of copper after water leaching for copper extraction is 91.33%, and the volatilization rate of selenium during the roasting process is 0%. After the copper sulfate solution is purified, it enters the copper electrolysis system to obtain cathode copper products.

[0037] (4) Accurately weigh 2.5 g of the water leaching residue obtained in step (3), 0.7 g of (NH4)2SO4, and 0.8 g of Na2SO4. After fully mixing, put them into a corundum crucible; place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration of the roasting is 50%. Control the temperature of the sulfation roasting at 550 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace, and collect the selenium oxide; after detection, the volatilization rate of selenium during the roasting process is 98.74%. Reduce the collected selenium oxide, and refine the obtained crude selenium into a selenium product.

[0038] Comparative Example 4: The method for roasting and extracting copper and selenium from copper anode slime in this comparative example includes the following steps: (1) Accurately weigh 5 g of copper anode slime, 1.2 g of (NH4)2SO4, and 1.5 g of Na2SO4. After fully mixing, put them into a corundum crucible; (2) Place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration of the roasting is 70%. Control the temperature of the sulfation roasting at 275 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace; (3) Take out 5 g of the roasting product, perform one-time water leaching on the roasting product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, and the leaching time is 120 min; after filtration, obtain copper sulfate solution and water leaching residue respectively. After detection, the leaching rate of copper after water leaching for copper extraction is 66.85%, and the volatilization rate of selenium during the roasting process is 0%.

[0039] (4) Accurately weigh 2.5 g of the water leaching residue obtained in step (3), 0.7 g of (NH4)2SO4, and 0.8 g of Na2SO4. After fully mixing, put them into a corundum crucible; place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration of the roasting is 50%. Control the temperature of the sulfation roasting at 550 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace, and collect the selenium oxide; after detection, the volatilization rate of selenium during the roasting process is 97.80%.

[0040] Comparative Example 5: The method for roasting and extracting copper and selenium from copper anode slime in this comparative example includes the following steps: (1) Accurately weigh 5 g of copper anode slime, 1.2 g of (NH4)2SO4, and 1.5 g of Na2SO4. After fully mixing, put them into a corundum crucible; (2) Place the corundum crucible in a tubular furnace for sulfation roasting. The oxygen-enriched concentration of the roasting is 60%. Control the temperature of the sulfation roasting at 275 °C and roast for 90 min. After the roasting reaction is completed, cool it to room temperature with the furnace; (3) Take out 5 g of the calcined product, and perform a single water leaching on the calcined product. The water leaching temperature is 70 °C, the liquid-solid ratio is 10 mL:1 g, and the leaching time is 120 min. After filtration, a copper sulfate solution and a water leached residue are obtained respectively. After detection, the copper leaching rate after water leaching for copper is 91.33%, and the selenium volatilization rate during the calcination process is 0%.

[0041] (4) Weigh 2.5 g of the water leached residue, 0.7 g of (NH4)2SO4, and 0.8 g of Na2SO4, mix them well and put them into a corundum crucible. Place the corundum crucible in a tube furnace for sulfation roasting. The oxygen enrichment concentration during roasting is 50%, control the sulfation roasting temperature at 400 °C, roast for 90 min, and cool to room temperature with the furnace after the roasting reaction is completed. After detection, the selenium volatilization rate during the roasting process is 51.41%.

Claims

1. A method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime, characterized in that, It includes the following steps: (1) Uniformly mix copper anode slime with sulfate, and conduct first-stage sulfation roasting at 200 - 350 °C; (2) Leach the roasting product obtained in step (1) with water to obtain copper sulfate solution and water leaching residue; (3) Mix the water leaching residue obtained in step (2) with sulfate, and conduct second-stage sulfation roasting at 450 - 550 °C to collect selenium-containing oxide.

2. The method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime according to claim 1, characterized in that, In step (1), the sulfate is at least one of (NH4)2SO4, Na2SO4, NaHSO4, K2SO4, FeSO4, and the mass ratio of the copper anode slime to the sulfate is 1:0.16 - 0.

64.

3. The method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime as claimed in claim 1, characterized in that, In step (1), the first-stage sulfation roasting is carried out in an atmosphere with an oxygen enrichment concentration of 10% - 60%, and the roasting time is 30 min - 90 min.

4. The method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime according to claim 1, characterized in that, In step (2), the temperature of the water leaching is 40 - 90 °C, the liquid-solid ratio of the water leaching is 3 - 15:1 (the ratio unit is mL / g), and the water leaching time is 30 - 120 min.

5. The method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime according to claim 1, characterized in that, In step (3), the second-stage sulfation roasting is carried out in an atmosphere with an oxygen enrichment concentration of 10% - 60%, and the sulfation roasting time is 20 min - 120 min.

6. The method for stepwise extracting copper and selenium by low-temperature sulfation roasting of copper anode slime according to claim 1, characterized in that, In step (3), the sulfate is at least one of (NH4)2SO4, Na2SO4, NaHSO4, K2SO4, FeSO4, and the mass ratio of the water leaching residue to the sulfate is 1:0.2 - 0.

8.

7. The method for stepwise extraction of copper and selenium by low-temperature sulfation roasting of copper anode slime according to claim 1, characterized in that, The main components of the copper anode slime include Se 5 - 20 wt%, Te 2 - 8 wt%, Pb 2 - 6 wt%, Au 0.1 - 1.2 wt%.

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