Method for recovering metal from low-nickel copper fire refining slag and application

Abstract

The invention discloses a method for recovering metal from low-nickel copper fire refining slag and application, and relates to the technical field of metal metallurgy. Comprising the following steps: carrying out alkaline arsenic leaching on the copper fire refining slag to obtain leached slag and arsenic-containing liquid, carrying out arsenic removal on the arsenic-containing liquid by adopting a calcium salt precipitation method to obtain calcium arsenite and arsenic-removed liquid, and carrying out medium-temperature roasting on the calcium arsenite to obtain basic calcium arsenate; and leaching residues are subjected to reduction smelting to recover copper. The separation of copper and arsenic in the raw materials is realized by adopting alkaline arsenic leaching, the content of arsenic in the leaching residues is reduced, and when copper recycled from the leaching residues is introduced into a copper electrolysis process, the problem of arsenic accumulation in electrolyte purification is relieved, and the purification cost of the electrolyte is reduced. Besides, the arsenic-containing liquid is treated by adopting a calcium salt precipitation method to obtain calcium arsenite precipitates, so that rapid separation of arsenic elements is realized, the calcium arsenite precipitates are subjected to medium-temperature roasting, basic calcium arsenate with lower toxicity and better stability is obtained, and harmless and stable treatment of arsenic is realized.

Description

Technical Field

[0001] The invention relates to the technical field of metal metallurgy, and in particular to a method and application of metal recovery from low-nickel copper pyrometallurgical refining slag. Background Art

[0002] The process of copper pyro-refining includes the process of preparing copper anode plates by refining and removing impurities from crude copper in an anode furnace. In the above refining process, refining slags with different copper contents are produced. According to the copper grade and physical phase difference of the slags, the refining slags can be divided into primary refining slags and secondary refining slags. Among them, the primary refining slag contains about 10% copper, and the secondary refining slag contains about 40-60% copper. In addition to copper, the refining slag also contains metal elements such as nickel or iron. Since the content of metal elements in the refining slag is relatively high, the recovery of copper and other metal elements (such as nickel) in the refining slag is conducive to the resource treatment of metals in the copper pyro-refining process.

[0003] However, the existing metal recovery method generally involves reducing and smelting the refined secondary slag to obtain black copper anode plates, and then electrolytic refining to obtain electrolytic copper. In this process, since the refined slag contains some impurity metals, such as arsenic, nickel, tin and antimony, these impurity metals will affect the self-purification process of the electrolytic refining electrolyte, reduce the added value of metal recovery, and reduce the processing efficiency of the electrolytic process. In addition, arsenic is a toxic substance. If it is directly discharged together with other impurity components, it will cause serious environmental pollution.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a method and application for recovering metal from low-nickel copper pyrometallurgical refining slag.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a method for recovering metals from low-nickel copper pyrometallurgical refining slag, comprising subjecting the copper pyrometallurgical refining slag to alkaline arsenic leaching to obtain leached slag and arsenic-containing liquid, removing arsenic from the arsenic-containing liquid by a calcium salt precipitation method to obtain calcium arsenite and a dearsenified liquid, and subjecting the calcium arsenite to medium-temperature roasting to obtain basic calcium arsenate; recovering copper from the leached slag through reduction smelting, and returning the dearsenified liquid to the alkaline arsenic leaching process for recycling.

[0008] In a second aspect, the present invention provides an application of the method according to any one of the aforementioned embodiments in reducing the toxicity of arsenic in copper pyrometallurgical refining slag.

[0009] The present invention has the following beneficial effects:

[0010] The present invention provides a method and application for metal recovery in low-nickel copper pyrometallurgical refining slag. By adopting an alkaline arsenic leaching method, copper and arsenic in the raw material are separated, and the arsenic content in the leached slag is significantly reduced. In the process of reducing and smelting copper in the leached slag, the arsenic content in the discharged impurities is extremely low, which meets the discharge conditions of impurities; in addition, since copper and arsenic are separated in advance, the arsenic content in the copper recovered by reduction smelting is reduced. When it is used to prepare electrolytic copper, the arsenic content introduced into the electrolytic refining process is reduced, which alleviates the accumulation problem of arsenic in electrolyte purification, and creates conditions for efficiently solving the self-purification open circuit problem of the arsenic electrolytic system and realizing the stable operation of the electrolytic system, which greatly reduces the purification cost of the electrolyte. Furthermore, by removing arsenic from the arsenic-containing liquid by calcium salt precipitation method, calcium arsenite precipitation is obtained, and the rapid separation of arsenic elements is realized; the calcium arsenite precipitation is then roasted at medium temperature to obtain basic calcium arsenate with less toxicity and better stability, which is conducive to the harmless and stable treatment of arsenic. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0012] Figure 1 A flow chart of a method for recovering metals from low-nickel copper pyrometallurgical refining slag provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0014] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0015] Copper pyrometallurgical refining slag includes refined primary slag and refined secondary slag, wherein the copper content in the refined secondary slag is higher and more suitable for recycling. At present, the method for recovering metals in copper pyrometallurgical refining slag is generally to prepare black copper anode plates from copper pyrometallurgical refining slag (refined primary slag and / or refined secondary slag) through at least one process of reduction smelting or direct smelting by pyrometallurgy, and then electrolytically refine the black copper anode plates to obtain electrolytic copper products. However, in the process of producing and preparing electrolytic copper, the self-purification process of the electrolytic system is easily affected, and the electrolyte needs to be additionally purified to ensure the smooth progress of the electrolytic process, which is not conducive to improving the added value of metal recovery. In addition, arsenic is a toxic substance, and a certain amount of arsenic element is contained in copper pyrometallurgical refining slag. If it is not treated, it may cause environmental pollution, so the inventor proposes the following solution.

[0016] In the first aspect, the present invention provides a method for recovering metal from low-nickel copper pyrometallurgical refining slag, the process flow of which is as follows: Figure 1 As shown, the method comprises subjecting copper pyrometallurgical refining slag to alkaline arsenic leaching to obtain leaching slag and arsenic-containing liquid, removing arsenite from the arsenic-containing liquid by calcium salt precipitation method to obtain calcium arsenite and arsenic-free liquid, and medium-temperature roasting the calcium arsenite to obtain basic calcium arsenate; the leaching slag is subjected to reduction smelting to recover copper, and the arsenic-free liquid is returned to the alkaline arsenic leaching process for recycling.

[0017] The inventors have found that the self-purification process of the electrolysis system is affected by the high content of arsenic in the system, which makes the ratio of arsenic, antimony, bismuth and other elements required for the self-purification process of the electrolysis system unbalanced, and the accumulation of arsenic in the electrolyte and anode mud increases, affecting the smooth progress of the electrolysis process. Therefore, it is necessary to increase the frequency of external treatment of the electrolyte, such as using electrolytic de-arsenicing to separate arsenic from other components. However, the cost of electrolytic de-arsenicing is high, resulting in a decrease in the added value of metal recovery in this process.

[0018] Therefore, the inventors proposed to first separate copper and arsenic from the raw material (copper pyrometallurgical refining slag), and the separation method adopts alkaline arsenic leaching method. Arsenic in copper pyrometallurgical refining slag mainly exists in the form of arsenic trioxide. When it contacts with alkaline solution, it can react to generate arsenite and transfer to the solution. Therefore, after the copper pyrometallurgical refining slag is subjected to alkaline arsenic leaching, leached slag and arsenic-containing liquid are obtained, wherein the metal element in the leached slag is mainly copper, and the arsenic content is extremely low; the main element in the arsenic-containing liquid is arsenic, and the form of arsenic is mainly arsenite.

[0019] The arsenite in the arsenic-containing liquid is precipitated to obtain calcium arsenite and a dearsenicated liquid. The calcium arsenite is separated from the dearsenicated liquid, and the dearsenicated liquid can be returned to the alkaline arsenic leaching process for reuse, without generating external wastewater and reducing the amount of alkaline solution used.

[0020] In the process of obtaining calcium arsenite precipitate by the calcium salt precipitation method, the precipitation rate of arsenite ion is fast. After the calcium arsenite is calcined at medium temperature, basic calcium arsenate solid with lower toxicity and better stability is obtained, which is conducive to the harmless and stable treatment of arsenic.

[0021] Arsenic is largely removed from the leached slag obtained by alkaline arsenic leaching and separation. When the leached slag is subjected to reduction smelting to recover copper, the arsenic content in the recovered copper is significantly reduced. When the recovered copper is used in the preparation of electrolytic copper, the arsenic content introduced into the electrolytic system is reduced, reducing the accumulation of arsenic in electrolyte purification and significantly reducing the purification cost of the electrolyte.

[0022] In an optional embodiment, the copper pyrometallurgical refining slag is a secondary refined slag, and in the secondary refined slag, Cu ≥ 40wt.%, 2wt.% ≤ As ≤ 4wt.% by mass percentage ， Nickel ≤ 1.1wt.%.

[0023] When the nickel content in the secondary refining slag is low, the economic benefits of recovering the nickel element alone are small. Therefore, for the secondary refining slag with low nickel content, the copper element is mainly recovered, and impurity elements such as nickel, tin and antimony are separated. In the process of copper recovery, in order to avoid the influence of impurity arsenic on its recycling process, it is necessary to separate copper and arsenic in advance, and then treat the separated arsenic harmlessly, which improves the environmental friendliness of the secondary refining slag recovery process.

[0024] It is understandable that, in addition to the copper, nickel and arsenic elements mentioned above, the refined secondary slag also contains other metal impurities, such as antimony and tin, etc. In addition, in addition to the metal elements, the refined slag also includes slag-forming materials, such as SiO2, FeO, etc.

[0025] In an optional embodiment, during the arsenic removal process by calcium salt precipitation, the molar ratio of calcium to arsenic is 1.5 to 2, and the pH of the reaction system is controlled to be 12 to 13. By controlling the calcium-arsenic ratio and the pH value of the unit system within the above range, it is beneficial to obtain calcium arsenite with a higher arsenic precipitation rate, while increasing the precipitation rate of calcium arsenite.

[0026] For example, in the process of arsenic removal by calcium salt precipitation, the molar ratio of calcium to arsenic is any value among 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0, or a range value between any two values.

[0027] For example, during the arsenic removal process by the calcium salt precipitation method, the pH of the reaction system can be any value among 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9 or 13, or a range between any two values.

[0028] Preferably, in order to control the precipitation process of calcium arsenite and ensure that the arsenic in the arsenic-containing solution is completely precipitated, the reaction temperature of the calcium salt precipitation method for arsenic removal is 25 to 80° C. and the reaction time is 1 to 3 hours.

[0029] Preferably, by controlling the above reaction parameters, the generation rate of calcium arsenite can be controlled to be ≥99% and the arsenic precipitation rate can be controlled to be ≥99.5%.

[0030] Preferably, in the process of arsenic removal by calcium salt precipitation, the calcium salt comprises at least one of lime and calcium sulfate, more preferably lime.

[0031] Preferably, when the concentration of arsenic in the arsenic-containing liquid is ≥15 g / L, calcium salt precipitation method is used for arsenic removal to ensure that the arsenic in the arsenic-containing liquid can be enriched to reduce the cost of arsenic removal.

[0032] In an optional embodiment, the medium temperature roasting temperature is 550-850° C., and the roasting time is 1-3 hours. By controlling the parameters of the medium temperature roasting within the above range, calcium arsenite can be converted into more stable basic calcium arsenate, and the leaching toxicity value of basic calcium arsenate meets the requirements for hazardous waste identification and the hazardous waste landfill standards, thereby achieving harmless treatment of arsenic.

[0033] Preferably, the flue gas in the roasting kiln is connected to bag filters, flue gas scrubbers and other treatment facilities to ensure the harmless treatment of arsenic.

[0034] In an optional embodiment, the leaching toxicity of arsenic element in basic calcium arsenate is ≤0.6 ppm.

[0035] In an optional embodiment, during the alkaline arsenic leaching process, the arsenic leaching rate is 70-80wt.%, the copper leaching rate is less than 0.5wt.%, the nickel leaching rate is ≤0.1wt.%, and the tin leaching rate is ≤0.5wt.%.

[0036] By adopting alkaline arsenic leaching, only arsenic is leached out in large quantities in the copper pyrometallurgical refining slag, and copper, nickel and tin elements can be considered to be almost not leached out, so that the arsenic-containing liquid is rich in arsenic, which is conducive to obtaining calcium arsenite precipitate with higher purity.

[0037] Preferably, the alkaline substance in the alkaline solution used for alkaline arsenic leaching includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate or sodium oxalate.

[0038] Preferably, the alkali solution is a sodium hydroxide solution, and the concentration of sodium hydroxide in the sodium hydroxide solution is 1.0 to 1.5 mol / L.

[0039] By adopting the alkaline arsenic leaching process and controlling the concentration of the alkali solution, the arsenic in the copper pyrometallurgical refining slag is leached with a low concentration of alkali, while the metals such as copper, tin and antimony are controlled not to be leached, thereby obtaining calcium arsenite with higher purity. The separation of copper from tin and antimony is carried out through reduction smelting, which ensures the effective recovery of various metal elements and realizes the harmless treatment of arsenic.

[0040] Preferably, during the alkaline arsenic leaching process, the mass concentration of the ore pulp is 10-20%, the reaction time of the alkaline arsenic leaching is 0.5-2.0 hours, and the reaction temperature is 25-80° C. By controlling the parameters of the alkaline arsenic leaching within the above range, it is beneficial to ensure the leaching of arsenic and the non-leaching of other metal elements.

[0041] After alkaline arsenic leaching, metal elements such as copper, tin and nickel are enriched in the leaching slag. In order to separate copper from other metal impurities, in an optional embodiment, the leaching slag is subjected to reduction smelting to obtain black copper anode plates (containing a small amount of nickel), tin-antimony smoke and smelting slag.

[0042] Preferably, the method further comprises blowing air or oxygen into the alkaline arsenic leaching reaction system to increase the arsenic leaching rate and reduce the concentration of the alkaline solution.

[0043] Preferably, since arsenic has been separated from metal elements in large quantities by alkaline leaching, the mass percentage of arsenic in the black copper anode plate obtained by reduction smelting of the leached slag is 0.5-1.5%, and the arsenic content is significantly reduced compared with the existing black copper anode plate.

[0044] For example, in some embodiments, the mass percentage of arsenic in the black copper anode plate can be any value among 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%, or a range value between any two values.

[0045] In an optional embodiment, the leaching residue is further cleaned, and the washing liquid obtained by cleaning is mixed with the arsenic-containing liquid and returned to the alkaline arsenic leaching process for cyclic leaching. The system does not generate effluent wastewater and does not cause direct arsenic discharge.

[0046] In an optional embodiment, in order to ensure the treatment effect of the subsequent process, the copper pyro-refining slag is further subjected to pre-treatment before alkaline arsenic leaching, and the pre-treatment includes ore crushing and ore grinding. By crushing and grinding the copper pyro-refining slag, the recovery rate of metals in the copper pyro-refining slag and the collection rate of arsenic elements can be improved.

[0047] Preferably, after the ore crushing process, the particle size of the copper pyrometallurgical refining slag is 0 to 10 mm.

[0048] Preferably, the ore is crushed in two stages of closed circuit, with a jaw crusher for coarse crushing, a cone crusher for fine crushing, and a vibrating screen for screening.

[0049] Preferably, the grinding adopts two-stage closed-circuit grinding, the first-stage grinding fineness -0.050mm accounts for 68-72%, and the final grinding fineness -0.074mm accounts for 82-88%.

[0050] Preferably, a ball mill is used for grinding, and a cyclone group is used for both the first stage classification and the second stage classification.

[0051] In a second aspect, the present invention provides an application of the method according to any one of the aforementioned embodiments in reducing the toxicity of arsenic in copper pyrometallurgical refining slag.

[0052] Example 1

[0053] This embodiment provides a method for recovering metal from low-nickel copper pyrometallurgical refining slag, and its process flow is as follows: Figure 1 As shown, the specific steps are as follows:

[0054] The element composition of the copper pyrometallurgical refining slag, by mass percentage, includes Cu: 60.15%, As: 2.14%, Ni: 0.8%, Sb: 0.45 and Sn: 2.39%.

[0055] S01. Pre-treatment

[0056] The copper pyrometallurgical refining slag is subjected to two-stage closed-circuit crushing and two-stage closed-circuit grinding to obtain finely ground slurry.

[0057] Among them, jaw crusher is used for coarse crushing, cone crusher is used for fine crushing, and vibrating screen is used for screening. After crushing, the particle size of copper pyrometallurgical refining slag is 125 mesh.

[0058] Ball mill is used for grinding, and cyclone group is used for both the first and second stage classification. The first stage grinding fineness is -0.050mm, accounting for 70%, and the final grinding fineness is -0.074mm, accounting for 85%.

[0059] S02, alkaline arsenic leaching

[0060] The finely ground slurry obtained in step S01 is transported to a leaching reactor or a reaction tank by a mortar pump for alkaline arsenic leaching. The liquid-to-solid ratio of the reaction system in the alkaline arsenic leaching process is 10L:1kg. A 1.5mol / L sodium hydroxide solution is used as a leaching agent. The reaction is carried out at 45°C for 1h and the leaching residue and arsenic-containing liquid are obtained by filtering.

[0061] In the arsenic-containing solution, the leaching rate of arsenic is 75.9%, the leaching rate of copper is 0.25%, the leaching rate of nickel is 0.00%, and the leaching rate of tin is 0.20%.

[0062] S03, calcium salt precipitation

[0063] The leaching residue obtained in step S02 is washed and filtered multiple times, and the washing liquid obtained by separation is mixed with the arsenic-containing liquid obtained in step S02. The mixed arsenic-containing liquid is partially recycled back to step S01 for use as a leaching liquid. The arsenic concentration in the mixed arsenic-containing liquid is 16 g / L, and calcium salt precipitation is performed to remove arsenic.

[0064] Lime was added to the arsenic-containing liquid at a molar ratio of calcium to arsenic of 1.5. The pH of the reaction system was 12.5. The reaction was carried out at 30°C for 1 hour and then filtered to obtain calcium arsenite and dearsenified liquid. The dearsenified liquid was returned to the alkaline arsenic leaching process and recycled as a leaching agent.

[0065] S04, medium temperature roasting

[0066] The calcium arsenite obtained in step S03 is placed in a medium-low temperature calcination furnace for calcination at a temperature of 800° C. for 1.5 h to obtain basic calcium arsenate.

[0067] S05, Reduction Smelting

[0068] The leached slag after multiple washings in step S03 is granulated and then reduced and smelted together with auxiliary materials and flux, the smelting temperature is 1250° C., the coke dosage is 12 wt.%, and black copper anode plates, tin-antimony smoke and smelting slag are obtained.

[0069] The black copper anode plate contains 85wt.% copper and 0.72wt.% arsenic, which meets the requirements of black copper electrolysis.

[0070] Example 2

[0071] This embodiment provides a method for recovering metals from low-nickel copper pyrometallurgical refining slag, the steps of which are similar to those of Example 1, with the only difference being that in step S02, the concentration of sodium hydroxide used is 1.0 mol / L, and air is blown into the alkaline arsenic leaching process.

[0072] In the obtained arsenic-containing solution, the leaching rate of arsenic was 81.29%, the leaching rate of copper was 0.12%, the leaching rate of nickel was 0.00%, and the leaching rate of tin was 0.00%.

[0073] The obtained black copper anode plate contains 85wt.% of copper and 0.53wt.% of arsenic, which meets the requirements of black copper electrolysis.

[0074] Example 3

[0075] This embodiment provides a method for recovering metal from low-nickel copper pyrometallurgical refining slag, and its process flow is as follows: Figure 1 As shown, the specific steps are as follows:

[0076] The element composition of the copper pyrometallurgical refining slag, by mass percentage, includes Cu: 49.64%, As: 3.13%, Ni: 0.89%, Sb: 0.35 and Sn: 1.39%.

[0077] S01. Pre-treatment

[0078] The copper pyrometallurgical refining slag is subjected to two-stage closed-circuit crushing and two-stage closed-circuit grinding to obtain finely ground slurry.

[0079] Among them, jaw crusher is used for coarse crushing, cone crusher is used for fine crushing, and vibrating screen is used for screening. After crushing, the particle size of copper pyrometallurgical refining slag is 125 mesh.

[0080] Ball mill is used for grinding, and cyclone group is used for both the first and second stage classification. The first stage grinding fineness is -0.050mm, accounting for 70%, and the final grinding fineness is -0.074mm, accounting for 85%.

[0081] S02, alkaline arsenic leaching

[0082] The finely ground slurry obtained in step S01 is transported to a leaching reactor or a reaction tank by a mortar pump for alkaline arsenic leaching. The liquid-to-solid ratio of the reaction system in the alkaline arsenic leaching process is 10L:1kg. A 1.5mol / L sodium hydroxide solution is used as a leaching agent. The reaction is carried out at 45°C for 1h and the leaching residue and arsenic-containing liquid are obtained by filtering.

[0083] In the arsenic-containing solution, the leaching rate of arsenic is 73.9%, the leaching rate of copper is 0.15%, the leaching rate of nickel is 0.00%, and the leaching rate of tin is 0.10%.

[0084] S03, calcium salt precipitation

[0085] The leaching residue obtained in step S02 is washed and filtered multiple times, and the washing liquid obtained by separation is mixed with the arsenic-containing liquid obtained in step S02. The mixed arsenic-containing liquid is partially recycled back to step S01 for use as a leaching liquid. When the arsenic concentration in the mixed arsenic-containing liquid is ≥16 g / L, calcium salt precipitation is performed to remove arsenic.

[0086] Lime was added to the arsenic-containing liquid at a molar ratio of calcium to arsenic of 1.5. The pH of the reaction system was 12.5. The reaction was carried out at 30°C for 1 hour and then filtered to obtain calcium arsenite and dearsenified liquid. The dearsenified liquid was returned to the alkaline arsenic leaching process and recycled as a leaching agent.

[0087] S04, medium temperature roasting

[0088] The calcium arsenite obtained in step S03 is placed in a medium-low temperature calcination furnace for calcination at a temperature of 750° C. for 1.5 h to obtain basic calcium arsenate.

[0089] S05, Reduction Smelting

[0090] The leached slag after multiple washings in step S03 is granulated and then reduced and smelted together with auxiliary materials and flux, the smelting temperature is 1250° C., the coke dosage is 12 wt.%, and black copper anode plates, tin-antimony smoke and smelting slag are obtained.

[0091] Among them, the black copper anode plate contains 84wt.% copper and 1.38wt.% arsenic, which meets the requirements of black copper electrolysis.

[0092] Comparative Example 1

[0093] This comparative example provides a method for recovering metals from low-nickel copper pyrometallurgical refining slag. The specific steps are similar to those of Example 1, with the only difference being that in step S02, the concentration of the leaching agent sodium hydroxide is 0.1 mol / L.

[0094] In the obtained arsenic-containing solution, the leaching rate of arsenic was 34.19%, the leaching rate of copper was 0.03%, the leaching rate of nickel was 0.00%, and the leaching rate of tin was 0.00%.

[0095] The obtained black copper anode plate contains 84.5wt.% copper and 1.86wt.% arsenic, which is slightly higher.

[0096] Comparative Example 2

[0097] This comparative example provides a method for recovering metals from low-nickel copper pyrometallurgical refining slag. The specific steps are similar to those of Example 1, with the only difference being that in step S02, the concentration of the leaching agent sodium hydroxide is 4 mol / L.

[0098] In the obtained arsenic-containing solution, the leaching rate of arsenic was 83.29%, the leaching rate of copper was 1.50%, the leaching rate of nickel was 0.00%, and the leaching rate of tin was 35.20%.

[0099] The obtained black copper anode plate contains 85.1 wt.% of copper and 0.52 wt.% of arsenic, meeting the requirements for black copper electrolysis.

[0100] Comparative Example 3

[0101] This comparative example provides a method for recovering metals from low-nickel copper pyrometallurgical refining slag. The specific steps are similar to those of Example 1, except that the arsenic-containing liquid in step S03 is subjected to lime dearsenicization to obtain arsenic calcium slag by a conventional method, and the pH of the reaction system is controlled to be 10 after the addition of lime.

[0102] The liquid after arsenic removal contains 5.3 g / L arsenic, and the arsenic precipitation rate is 70%.

[0103] Comparative Example 4

[0104] This comparative example provides a method for recovering metals from low-nickel copper pyrometallurgical refining slag, and the specific steps are similar to those of Example 1, except that there are no S02 and S03 steps.

[0105] The obtained black copper anode plate contains 84.2wt.% copper and 2.85wt.% arsenic, which is relatively high.

[0106] Test Example 1

[0107] The metals in the copper pyro-refining slag were recovered by calculating the methods of Examples 1 to 3 and Comparative Examples 1 to 4, wherein the direct recovery rates of copper, nickel and tin were calculated based on the metals recovered in the black copper plate. For example, the direct recovery rate of copper = the mass of copper in the black copper anode plate / the mass of copper in the copper pyro-refining slag input × 100%; the arsenic removal rate = the arsenic leaching rate in step S02 × the arsenic precipitation rate of calcium salt in step S03, and the results were obtained as shown in Table 1.

[0108] Table 1 Direct recovery of metals and removal rate of arsenic in copper pyrometallurgical refining slag

[0109] Copper / wt.% Nickel / wt.% Tin / wt.% Arsenic / wt.% Example 1 97.9 90.2 83.4 75.52 Example 2 97.8 90.1 83.4 80.88 Example 3 97.7 90.2 83.5 73.53 Comparative Example 1 97.8 90.1 83.5 34.02 Comparative Example 2 97.6 90.1 54.1 82.87 Comparative Example 3 97.8 90.1 83.2 53.20 Comparative Example 4 97.8 90.1 83.5 0

[0110] As shown in Table 1, the method provided by the embodiment of the present invention can effectively realize the recovery of metals, and at the same time realize the separation of copper and arsenic, with high metal recovery rate and good separation effect between copper, nickel and tin. However, since the alkali solution concentration used in Comparative Example 1 is too low, the arsenic leaching effect is poor. After the remaining arsenic and copper elements are prepared into black copper anode plates together, arsenic accumulation is still prone to occur during the electrolytic preparation of electrolytic copper, affecting the self-purification process of the electrolyte. The alkali solution concentration of Comparative Example 2 is too high, resulting in arsenic leaching while part of the tin is also leached synchronously, thereby reducing the direct recovery rate of tin. Comparative Example 3 uses a conventional method to add lime to precipitate arsenic, and lime is not added according to the requirements of the calcium-arsenic ratio. Although its arsenic leaching rate is comparable to that of Example 1, after adding lime, the pH of the reaction system is lower than that of the embodiment, and the arsenic precipitation rate decreases, so the arsenic recovery rate is also reduced. Comparative Example 4 does not immerse arsenic in advance and directly prepares the black copper anode plate. The arsenic content in the obtained black copper anode plate is relatively high. If it is directly used to prepare electrolytic copper, it will seriously affect the self-purification process of the electrolyte.

[0111] Test Example 2

[0112] The arsenic-containing materials recovered by the methods of Examples 1 to 3 and Comparative Examples 1 to 4 (basic calcium arsenate in the examples and calcium arsenic slag in the comparative examples) were subjected to leaching toxicity testing in accordance with the "Identification Standard for Hazardous Wastes - Leaching Toxicity Identification" (GB5085.3-2007), and the results shown in Table 2 were obtained.

[0113] Table 2 Toxicity leaching results of arsenic-containing materials

[0114] Arsenic / ppm Example 1 0.45 Example 2 0.49 Example 3 0.53 Comparative Example 1 0.42 Comparative Example 2 0.39 Comparative Example 3 6.2 Comparative Example 4 No separate arsenic-containing material was obtained

[0115] As shown in Table 2, the toxicity of basic calcium arsenate obtained by the method provided in the embodiment of the present invention is significantly lower than that of traditional arsenic calcium slag, meeting the discharge requirements of arsenic elements in the hazardous waste landfill standard. However, the arsenic calcium slag obtained by separation in Comparative Example 3 is more toxic, which increases the difficulty of post-treatment of the arsenic calcium slag.

[0116] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recovering metal from low-nickel copper pyrometallurgical refining slag, characterized in that: The method comprises subjecting copper pyrometallurgical refining slag to alkaline arsenic leaching to obtain leaching slag and arsenic-containing liquid, removing arsenite from the arsenic-containing liquid by a calcium salt precipitation method to obtain calcium arsenite and a dearsenified liquid, and medium-temperature roasting the calcium arsenite to obtain basic calcium arsenate; the leaching slag is subjected to reduction smelting to recover copper, and the dearsenified liquid is returned to the alkaline arsenic leaching process for recycling.

2. The method according to claim 1, characterized in that The copper pyrometallurgical refining slag is a secondary refined slag, and in the secondary refined slag, Cu≥40wt.%, 2wt.%≤As≤4wt.%, and nickel≤1.1wt.%.

3. The method according to claim 1, characterized in that During the arsenic removal process using the calcium salt precipitation method, the molar ratio of calcium to arsenic is 1.5 to 2, and the pH of the reaction system is 12 to 13; Preferably, the reaction temperature of the calcium salt precipitation method for arsenic removal is 25 to 80° C., and the reaction time is 1 to 3 hours; Preferably, the calcium arsenite generation rate is ≥99%, and the arsenic precipitation rate is ≥99.5%; Preferably, in the process of arsenic removal by calcium salt precipitation, the calcium salt comprises at least one of lime and calcium sulfate; Preferably, when the concentration of arsenic in the arsenic-containing liquid is ≥15 g / L, the calcium salt precipitation method is used for arsenic removal.

4. The method according to claim 1, characterized in that The medium-temperature calcination has a calcination temperature of 550 to 850° C. and a calcination time of 1 to 3 hours.

5. The method according to claim 1, characterized in that: During the alkaline arsenic leaching process, the arsenic leaching rate is 70-80wt.%, the copper leaching rate is less than 0.5wt.%, the nickel leaching rate is ≤0.1wt.%, and the tin leaching rate is ≤0.5wt.%; Preferably, the alkaline substance in the alkaline solution used for alkaline arsenic leaching includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate or sodium oxalate; Preferably, the alkali solution is a sodium hydroxide solution, and the concentration of sodium hydroxide in the sodium hydroxide solution is 1.0 to 1.5 mol / L; Preferably, during the alkaline arsenic leaching process, the mass concentration of the slurry is 10-20%, the reaction time of the alkaline arsenic leaching is 0.5-2.0h, and the reaction temperature is 25-80°C; Preferably, the method further comprises blowing air or oxygen into the alkaline arsenic leaching reaction system.

6. The method according to claim 1, characterized in that The leached slag is subjected to reduction smelting to obtain black copper anode plates, tin-antimony smoke and smelting slag; Preferably, the mass percentage of arsenic in the black copper anode plate is 0.5-1.5%.

7. The method according to claim 1, characterized in that The method also includes washing the leached residue, mixing the washing liquid obtained by washing with the arsenic-containing liquid and returning the washing liquid to the alkaline arsenic leaching process for cyclic leaching.

8. The method according to claim 1, characterized in that The copper pyrometallurgical refining slag also includes pre-treatment of the copper pyrometallurgical refining slag before alkaline arsenic leaching, and the pre-treatment includes ore crushing and ore grinding; Preferably, after the ore crushing process, the particle size of the copper pyrometallurgical refining slag is 0 to 10 mm; Preferably, the ore crushing adopts two-stage closed-circuit ore crushing, the coarse crushing adopts a jaw crusher, the fine crushing adopts a cone crusher, and the screening adopts a vibrating screen; Preferably, the grinding adopts two-stage closed-circuit grinding, the first-stage grinding fineness -0.050mm accounts for 68-72%, and the final grinding fineness -0.074mm accounts for 82-88%; Preferably, the grinding is performed by a ball mill, and both the first-stage classification and the second-stage classification are performed by a cyclone group.

9. The method according to claim 1, characterized in that: The leaching toxicity of arsenic element in the basic calcium arsenate is ≤0.6 ppm.

10. Use of the method according to any one of claims 1 to 9 for reducing the toxicity of arsenic in copper pyrometallurgical refining slag.

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