Method for vacuum directional sulfidation and arsenic removal of copper smelting arsenic-containing solid waste
By separating Cu2S and metallic As from black copper sludge and sulphurized acid slag using vacuum melting and distillation technology, the problem of arsenic solid waste recovery in copper smelting is solved, resource utilization and purity are improved, and the process flow is simplified.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2023-07-11
- Publication Date
- 2026-07-07
AI Technical Summary
In existing copper smelting processes, it is difficult to effectively recover arsenic-containing solid waste from black copper sludge and acid sulfide slag, leading to environmental pollution and resource waste, while also affecting the direct metal recovery rate and equipment production capacity.
The black copper mud and the sulphurized acid slag are mixed and smelted under vacuum to produce Cu2S and metallic As. They are then separated by vacuum distillation. The metallic As is condensed and recovered by utilizing the difference in saturated vapor pressure, while Cu2S remains in the residue.
Arsenic was recovered from black copper sludge and sulphurized acid slag. The generated Cu2S can be directly returned to the copper blowing system, which improves the resource recovery rate and purity and simplifies the process.
Smart Images
Figure CN116814978B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of non-ferrous metal smelting technology, and in particular to a method for vacuum-directed sulfidation removal of arsenic from arsenic-containing solid waste in copper smelting. Background Technology
[0002] In recent years, with the depletion of copper resources, the mining of high-arsenic copper ore has been on the rise, especially in domestic concentrates, some of which contain arsenic of over 10 wt%. Based on the characteristics of the smelting process, approximately 45-50 wt% of the arsenic enters the smelting slag. In some plants that have implemented slag beneficiation processes, approximately 10-15 wt% of the arsenic enters the slag concentrate, 30-40 wt% enters the tailings, approximately 15 wt% enters the waste acid, and approximately 15 wt% enters the anode copper. During the electrolysis process, the arsenic gradually enters the anode mud, black copper mud, crude copper sulfate, and other wet process materials, ultimately generating arsenic-containing solid waste such as tailings, slag concentrate, black copper mud, anode mud, crude copper sulfate, and sulfide slag.
[0003] Black copper sludge is a black, sludge-like substance produced during the electrowinning process when impurities such as As, Pd, and Bi in the copper electrolyte are deposited together with Cu at the cathode. The main elements in black copper sludge are Cu and As (containing approximately 40 wt% copper and 20 wt% arsenic, primarily in the form of Cu3As), with lower levels of other impurities (Bi, Pb, Sb, S, etc.). Waste acid sulfidation slag is produced during copper smelting when a sulfidation process is used to purify waste acid. By adding a sulfiding agent, arsenic and heavy metal ions react with the sulfiding agent to form sulfide precipitates with low solubility products. In addition to large amounts of As and S (containing approximately 40 wt% arsenic and 36 wt% sulfur, primarily in the form of As2S3), waste acid sulfidation slag also contains valuable elements such as Cu, Pb, and Re. Most copper smelters do not have a good product form for As recovery; they either stockpile black copper sludge and waste acid sulfidation slag or simply remelt them. Because black copper sludge and acid sulfide slag contain large amounts of asperium (As), stockpiling them not only requires a significant amount of space, but the asperium also undergoes a series of reactions in the presence of air and water, causing severe environmental damage. Returning black copper sludge and acid sulfide slag to the copper smelting process would cause impurities such as asperium (As), sulfur dioxide (Sb), and bisulfite (Bi) to circulate within the system, severely impacting the direct metal recovery rate, reducing equipment production capacity, and increasing energy consumption. Summary of the Invention
[0004] In view of this, the purpose of this invention is to provide a method for vacuum-directed sulfidation to remove arsenic from arsenic-containing solid waste in copper smelting, which, while removing arsenic, comprehensively recovers and utilizes valuable elements such as Cu and S in black copper sludge and sludge sulfidation slag.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for vacuum-directed sulfidation removal of arsenic from arsenic-containing solid waste in copper smelting, comprising the following steps:
[0007] The black copper sludge and the sludge from the acid sulfidation process are mixed to obtain a mixture.
[0008] The mixture is pressed into shape to obtain a green body;
[0009] The green blank is melted under vacuum conditions to induce sulfidation and obtain sulfidation products; the sulfidation products include Cu2S and metallic As;
[0010] The sulfide product is subjected to vacuum distillation to obtain metallic arsenic in the condensation zone, and the distillation residue is mainly Cu2S; the vacuum distillation pressure is 1-100 Pa and the temperature is 1023-1273 K; the temperature of the condensation zone is 373-573 K.
[0011] Preferably, the black copper sludge contains 10-20 wt% arsenic and 30-40 wt% copper.
[0012] Preferably, the arsenic content in the sludge is 38-42 wt%, and the sulfur content is 35-39 wt%.
[0013] Preferably, the mass ratio of the black copper sludge to the sulphurized acid slag is 1:(0.2-5).
[0014] Preferably, the melting temperature is 673–973 K, the holding time is 30–120 min, and the pressure is 1–10000 Pa.
[0015] Preferably, the pressing pressure is 8-20 MPa.
[0016] Preferably, the vacuum distillation time is 30 to 120 minutes.
[0017] Preferably, before the melting process, the green blank is dried.
[0018] Preferably, the average particle size of the mixture is 75–90 μm.
[0019] Preferably, the green blank is a cylindrical blank with a height of 5-10 mm and a diameter of 25-30 mm.
[0020] This invention provides a method for vacuum-directed sulfidation removal of arsenic from arsenic-containing solid waste in copper smelting, comprising the following steps: mixing black copper sludge and sludge from acid sulfidation to obtain a mixture; pressing the mixture into a green blank; smelting the green blank under vacuum conditions to induce sulfidation and obtain a sulfidation product; the sulfidation product includes Cu₂S and metallic As; vacuum distilling the sulfidation product to obtain metallic arsenic in the condensation zone, with the distillation residue mainly being Cu₂S; the vacuum distillation pressure is 1–100 Pa, and the temperature is 1023–1273 K; the temperature of the condensation zone is 373–573 K.
[0021] This invention involves mixing black copper sludge and acid sulfidation slag and then smelting them under vacuum conditions to achieve the directional sulfidation of black copper sludge by acid sulfidation slag to generate Cu2S and metallic As. Then, based on the difference in saturated vapor pressure, the sulfidation products are vacuum distilled. As condenses in the condensation zone as vapor, while Cu2S does not volatilize and remains in the residue, thus achieving the separation of Cu2S and metallic As.
[0022] This invention enables the recovery of arsenic from black copper sludge and acid sulfide slag, yielding non-toxic and economically valuable metallic arsenic. Simultaneously, the generated Cu₂S can be directly returned to the copper smelting system, achieving comprehensive utilization of valuable elements. Results from the embodiments show that, after treatment by the method of this invention, the Cu₂S recovery rate is higher than 90%, and the purity is greater than 95%, meeting the purity standards for copper matte in copper smelting; the direct recovery rate of condensed As is higher than 90%, and the purity is greater than 99.5%.
[0023] This invention enables the co-treatment of two arsenic-containing solid wastes: copper smelting acid sulfide slag and black copper sludge. The process is short, simple to operate, and improves the resource recovery rate, showing great application potential. Attached Figure Description
[0024] Figure 1 This is a flowchart of the method for vacuum-directed sulfidation arsenic removal from arsenic-containing solid waste in copper smelting according to the present invention;
[0025] Figure 2 Graphs showing the change of saturated vapor pressure of different substances with temperature;
[0026] Figure 3 The image shows the XRD pattern of the black copper sludge raw material in Example 1.
[0027] Figure 4 XRD patterns of the distillation residues from Examples 1 and 2;
[0028] Figure 5 SEM images of the mixed condensate products collected in the condensation zones of Examples 1 and 2. Detailed Implementation
[0029] This invention provides a method for vacuum-directed sulfidation removal of arsenic from arsenic-containing solid waste in copper smelting, comprising the following steps:
[0030] The black copper sludge and the sludge from the acid sulfidation process are mixed to obtain a mixture.
[0031] The mixture is pressed into shape to obtain a green body;
[0032] The green blank is melted under vacuum conditions to induce sulfidation and obtain sulfidation products; the sulfidation products include Cu2S and metallic As;
[0033] The sulfide product is subjected to vacuum distillation to obtain metallic arsenic in the condensation zone, and the distillation residue is mainly Cu2S; the vacuum distillation pressure is 1-100 Pa and the temperature is 1023-1273 K; the temperature of the condensation zone is 373-573 K.
[0034] This invention mixes black copper sludge and sludge sulfide residue to obtain a mixture.
[0035] In this invention, the black copper sludge is preferably arsenic-containing solid waste generated on the surface of cathode copper during copper refining; the arsenic content in the black copper sludge is preferably 10-20 wt%, more preferably 13-18 wt%, and the copper content is preferably 30-40 wt%, more preferably 32-38 wt%. In this invention, Cu and As in the black copper sludge mainly exist in the form of Cu3As. In this invention, the black copper sludge inevitably also contains Bi, Pb, and S impurities.
[0036] In this invention, the sludge from the treated acid is preferably an arsenic-containing solid waste generated in an acid production system using a sulfidation method; the arsenic content in the sludge is preferably 38–42 wt%, and the sulfur content is preferably 35–39 wt%. In this invention, the As and S in the sludge mainly exist in the form of As₂S₃; the sludge inevitably also contains valuable elements such as Cu, Pb, and Re.
[0037] In this invention, the mass ratio of the black copper sludge to the sulphurized acid slag is preferably 1:(0.2-5), more preferably 1:(1-4), and even more preferably 1:(2-3).
[0038] The present invention does not have any special requirements for the mixing process, and any method known in the art that can mix black copper mud and sulphurized acid slag evenly is acceptable.
[0039] In this invention, the average particle size of the mixture is preferably 75-90 μm, more preferably 80-85 μm.
[0040] After obtaining the mixture, the present invention presses the mixture into a shape to obtain a green body.
[0041] In this invention, the pressing pressure is preferably 8-20 MPa, more preferably 9-11 MPa. In this invention, the green blank is preferably a cylindrical blank with a height of 5-10 mm and a diameter of 30 mm. The pressing of the mixture in this invention facilitates more thorough contact between the black copper sludge and the acid sulfidation slag, reduces the volatilization of the sulfidation reactant As₂S₃, and makes the directional sulfidation reaction process more complete.
[0042] After obtaining the green blank, the present invention melts the green blank under vacuum conditions to induce sulfidation and obtain sulfidation products; the sulfidation products include Cu2S and metallic As.
[0043] Prior to the smelting process, the present invention preferably further includes drying the green blank. In the present invention, the drying temperature is preferably 110°C, and the drying time is preferably 4 hours.
[0044] In this invention, the smelting is preferably carried out in a vacuum reduction furnace; the smelting temperature is preferably 673–973 K, more preferably 700–900 K, and even more preferably 730–873 K; the smelting holding time is preferably 30–120 min, more preferably 40–100 min, and even more preferably 60–80 min; the smelting pressure is preferably 1–10000 Pa, more preferably 100–9000 Pa, and even more preferably 1000–8000 Pa. The main chemical reaction occurring during the smelting process in this invention is: 2Cu3As + As2S3 = 3Cu2S + 4As.
[0045] In this invention, the sulfide products include Cu2S and metallic As, and inevitably contain other impurity elements or sulfides containing other impurity elements.
[0046] After obtaining the sulfide product, the present invention performs vacuum distillation on the sulfide product to obtain metallic arsenic in the condensation zone, and the distillation residue is mainly Cu2S; the pressure of the vacuum distillation is 1-100 Pa, the temperature is 1023-1273 K, and the temperature of the condensation zone is 373-573 K.
[0047] In this invention, the pressure of the vacuum distillation is 1–100 Pa, preferably 10–90 Pa, more preferably 20–80 Pa; the temperature of the vacuum distillation is 1023–1273 K, preferably 1073–1223 K, more preferably 1100–1173 K; the temperature of the condensation zone is 373–573 K, preferably 400–550 K, more preferably 450–500 K. In this invention, the time of the vacuum distillation is preferably 30–120 min, more preferably 50–100 min, and even more preferably 60–90 min.
[0048] This invention utilizes the difference in saturated vapor pressure to perform vacuum distillation on the sulfide products. The saturated vapor pressure of metallic As differs significantly from that of Cu₂S and other impurities (see...). Figure 2 Therefore, by controlling the temperature, metallic As can be separated out, and As condenses in the condensation zone in the form of vapor. Cu2S and other impurities have similar saturated vapor pressures, so they cannot be completely separated by vacuum distillation. However, the content of other impurities is low, so the recovery rate and purity of Cu2S in the residue can reach a high level, thus achieving the separation of Cu2S and metallic As.
[0049] Figure 1 This is a process flow diagram of the method of the present invention. (For example...) Figure 1 As shown, this invention mixes black copper sludge and acid sulfidation slag to obtain a mixture; the mixture is pressed into a shape to obtain a green blank; the green blank is smelted under vacuum conditions to undergo sulfidation, yielding a sulfidation product; the sulfidation product includes Cu₂S and metallic As; the sulfidation product is vacuum distilled, and metallic arsenic is obtained in the condensation zone, with the distillation residue mainly being Cu₂S. After treatment by the method of this invention, the recovery rate of Cu₂S is higher than 90%, and the purity is greater than 95%, meeting the purity standard for copper matte in copper blowing; the direct recovery rate of condensed As is higher than 90%, and the purity is greater than 99.5%.
[0050] The following detailed description of the method for vacuum-directed sulfidation removal of arsenic from arsenic-containing solid waste in copper smelting provided by the present invention, with reference to specific embodiments, is not intended to limit the scope of protection of the present invention.
[0051] Example 1
[0052] Taking black copper sludge and acid sulfidation slag from a domestic copper smelter as an example (composition shown in Table 1), the materials were mixed at a mass ratio of 1:1.5 to obtain a mixture with an average particle size of 80 μm. The mixture was pressed into cylindrical green billets with a diameter of 30 mm and a height of 10 mm under a pressure of 20 MPa. The green billets were then dried in a drying oven at 110 °C for 4 hours. The dried green billets were then placed in a vacuum reduction furnace. The control system pressure was 7500 Pa, and the temperature was increased from room temperature to 773 K at a rate of 15 °C / min, and held for 60 minutes to generate sulfidation products, the main component of which was Cu. Cu₂S and metallic As were then separated. The sulfidation product was vacuum distilled, with the system pressure controlled at 10 Pa and the temperature increased from room temperature to 1023 K at a rate of 15 °C / min, held at this temperature for 60 min, and the condensation zone temperature controlled at 573 K. Based on the difference in saturated vapor pressure, Cu₂S and As were separated from the sulfidation product. The distillation residue was Cu₂S, and the condensation zone contained metallic arsenic. After treatment using the above method, the Cu₂S recovery rate reached 92.35%, and the purity reached 95.56%, meeting the purity standards for copper matte in copper blowing. The direct recovery rate of the condensed As reached 92.79%, and the purity reached 99.51%.
[0053] Table 1. Main chemical components (%) of black copper sludge and acid sulfide slag
[0054] name Cu As Pb S Bi Sb Black Copper Mud 41.4550 23.2310 4.4761 3.4339 2.9665 1.6753 sulfide slag 0.9526 31.8452 1.5096 35.6446 1.5015 1.6582
[0055] Example 2
[0056] Taking black copper sludge and acid sulfidation slag (main chemical composition shown in Table 2) from a domestic copper smelter as an example, the materials were mixed at a mass ratio of 1:2 to obtain a mixture with an average particle size of 85 μm. The mixture was pressed into cylindrical green billets with a diameter of 30 mm and a height of 10 mm under a pressure of 20 MPa. The green billets were then dried in a drying oven at 110 °C for 4 hours. The dried green billets were then placed in a vacuum reduction furnace. The control system pressure was 6000 Pa, and the temperature was increased from room temperature to 973 K at a rate of 15 °C / min, and held for 120 min to generate sulfidation products, mainly Cu2+. S and metallic As; then, the sulfidation product is subjected to vacuum distillation, with the system pressure controlled at 10 Pa, and the temperature increased from room temperature to 1273 K at a rate of 15 °C / min, held at that temperature for 60 min, and the temperature of the condensation zone controlled at 473 K. Based on the difference in saturated vapor pressure, Cu2S and As in the sulfidation product are separated; the distillation residue is Cu2S, and the condensation zone contains metallic arsenic. After the above treatment, the recovery rate of Cu2S reaches 94.75%, and the purity reaches 97.23%, which meets the purity standard of copper matte in copper blowing; the direct recovery rate of As from directional condensation reaches 96.59%, and the purity reaches 99.89%.
[0057] Table 2. Main chemical components (%) of black copper sludge and acid sulfide slag
[0058] name Cu As Pb S Bi Sb Black Copper Mud 39.6283 19.0373 3.9845 3.1695 2.1965 1.2419 sulfide slag 0.8842 34.8425 1.2395 37.6491 1.3562 1.7458
[0059] Structural characterization:
[0060] The black copper sludge from Example 1 was characterized by XRD, and the results are shown in the figure. Figure 3 .Depend on Figure 3 It can be seen that the main components of black copper mud are Cu3As and a small amount of PbSO4.
[0061] The distillation residues from Examples 1 and 2 were characterized by XRD, and the results are shown in the figure. Figure 4 .Depend on Figure 4 It can be seen that in both implementation examples, the system pressure was controlled at 10 Pa, the vacuum distillation reaction temperature was 1023 K and 1273 K respectively, the reaction time was 60 min, and the final residue was Cu2S.
[0062] The mixed condensate products from the condensation zones of Examples 1 and 2 were characterized by SEM, and the results are shown in [Figure 1]. Figure 5 .
[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for vacuum-directed sulfidation removal of arsenic from arsenic-containing solid waste in copper smelting, characterized in that, Includes the following steps: The black copper sludge and the sludge from the acid sulfidation process are mixed to obtain a mixture. The mixture is pressed into shape to obtain a green body; The green blank is melted under vacuum conditions to induce sulfidation and obtain a sulfidation product. The sulfide products include Cu2S and metallic As; The sulfide product was subjected to vacuum distillation to obtain metallic arsenic in the condensation zone, and the distillation residue was mainly Cu2S; the vacuum distillation pressure was 1~100 Pa and the temperature was 1023~1273 K; the temperature of the condensation zone was 373~573 K. The black copper sludge contains 10-20 wt% arsenic and 30-40 wt% copper. The arsenic content in the sludge is 38-42 wt%, and the sulfur content is 35-39 wt%. The mass ratio of the black copper sludge to the sulphurized acid slag is 1:(0.2~5). The melting temperature is 673~973K, the holding time is 30~120min, and the pressure is 1~10000Pa.
2. The method according to claim 1, characterized in that, The pressure for compression molding is 8~20MPa.
3. The method according to claim 1, characterized in that, The vacuum distillation time is 30~120 min.
4. The method according to claim 1, characterized in that, Before the smelting process, the green blank is dried.
5. The method according to claim 1, characterized in that, The average particle size of the mixture is 75~90μm.
6. The method according to claim 1 or 2, characterized in that, The green blank is a cylindrical blank with a height of 5~10mm and a diameter of 25~30mm.