A method for recovering metallic arsenic from arsenic sulfide residue using calcium carbonate and a carbon source

Abstract

The application provides a method for recovering metallic arsenic from arsenic sulfide residue by using calcium carbonate and a carbon source, comprising: providing a reaction container with a high-temperature zone and a low-temperature zone in communication; reacting arsenic sulfide residue, calcium carbonate and a carbon source in the high-temperature zone; during the reaction, the generated metallic arsenic is transferred to the low-temperature zone; the molar ratio of the calcium carbonate to the arsenic sulfide in the arsenic sulfide residue is not less than 3; the molar ratio of the carbon element in the carbon source to the arsenic sulfide in the arsenic sulfide residue is not less than 3; the temperature of the high-temperature zone is 800-950 DEG C, and the temperature of the low-temperature zone is 600-750 DEG C. Based on the combined treatment of the calcium carbonate and the carbon source, the application can recover the metallic arsenic from the arsenic sulfide residue in one step, and can ensure the recovery rate and purity of the metallic arsenic product.

Description

Technical Field

[0001] This invention belongs to the field of arsenic extraction, and particularly relates to a method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source. Background Technology

[0002] Arsenic materials are widely used in optoelectronic materials, alloys, pharmaceuticals, and semiconductors. Arsenic in waste often exists in unstable forms, exhibiting strong environmental mobility and high biotoxicity; arsenic sulfide slag, in particular, is highly toxic and corrosive. The large quantities of arsenic sulfide slag generated by the non-ferrous metal smelting industry are a significant source of solid waste pollution, primarily originating from the sulfide precipitation process used to treat arsenic-containing wastewater. Due to its high leaching toxicity and strong corrosiveness, the treatment of arsenic sulfide slag is extremely difficult.

[0003] Currently, pyrometallurgy and hydrometallurgy are the main potential technologies for treating arsenic sulfide slag and realizing arsenic resource recovery. However, hydrometallurgy suffers from drawbacks such as complex processes and high recovery costs, and often produces unstable arsenic-containing precipitates after treatment, posing a continued environmental threat. Valuable metals may also fail to be recovered, existing only in a stable form, leading to resource waste. In contrast, pyrometallurgy technology has advantages such as high maturity and short process flow, making it particularly suitable for treating solid hazardous waste with high arsenic content. However, existing pyrometallurgical processes generally suffer from low arsenic recovery rates, low product purity, and the need for further purification. Furthermore, traditional pyrometallurgical technologies typically involve oxidative roasting of the arsenic sulfide slag followed by carbothermic reduction, requiring two steps and generating sulfur dioxide that causes severe environmental pollution.

[0004] Therefore, it is necessary to provide a method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source, in order to solve the technical problem of how to recover metallic arsenic from arsenic sulfide slag in one step while ensuring the recovery rate and purity of metallic arsenic. Summary of the Invention

[0005] The main objective of this invention is to provide a method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source, aiming to solve the technical problem of how to recover metallic arsenic from arsenic sulfide slag in one step while ensuring the recovery rate and purity of metallic arsenic.

[0006] To achieve the above objectives, the present invention provides a method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source, comprising: A reaction vessel is provided, the reaction vessel having a high-temperature zone and a low-temperature zone connected in communication; Arsenic sulfide slag, calcium carbonate, and carbon source are reacted in the high-temperature zone; during the reaction, the generated metallic arsenic is transferred towards the low-temperature zone. The molar ratio of calcium carbonate to arsenic sulfide in the arsenic sulfide slag is not less than 3; the molar ratio of carbon in the carbon source to arsenic sulfide in the arsenic sulfide slag is not less than 3; the temperature of the high-temperature zone is 800-950℃, and the temperature of the low-temperature zone is 600-750℃.

[0007] Furthermore, the carbon source includes at least one of elemental carbon, methane, and carbon monoxide.

[0008] Furthermore, the carbon source includes the elemental carbon, and the molar ratio of the elemental carbon to the arsenic sulfide in the arsenic sulfide slag is not less than 5.

[0009] Furthermore, the carbon source includes the carbon monoxide, and the molar ratio of the carbon monoxide to the arsenic sulfide in the arsenic sulfide slag is 3-6:1.

[0010] Furthermore, the molar ratio of calcium carbonate to arsenic sulfide in the arsenic sulfide slag is 3-5:1.

[0011] Furthermore, the temperature of the low-temperature zone is 650-750℃.

[0012] Furthermore, the reaction time is not less than 0.5 h.

[0013] Furthermore, the reaction time is 0.5-2.5 h.

[0014] Furthermore, before the reaction is carried out, the heating rate of the high-temperature zone and the low-temperature zone is 5-15℃ / min; After the reaction is completed, the high-temperature zone and the low-temperature zone are allowed to cool naturally to room temperature.

[0015] Furthermore, the reaction vessel includes a horizontally placed tube; The atmosphere of the reaction vessel is one of air, vacuum, or inert gas.

[0016] Compared with the prior art, the present invention has at least the following advantages: This invention enables the one-step recovery of metallic arsenic from arsenic sulfide slag, ensuring both the recovery rate and purity of the metallic arsenic. The invention involves reacting arsenic sulfide slag, calcium carbonate, and a carbon source in a high-temperature zone. The calcium carbonate fixes the sulfur in the arsenic sulfide, generating metallic arsenic and calcium sulfide. After generation, the metallic arsenic is transferred to a low-temperature zone, while the calcium sulfide remains in the high-temperature zone, thus achieving separation of metallic arsenic and calcium sulfide and facilitating their individual collection.

[0017] The process of this invention is short and low-cost. Based on carbothermic reduction, only calcium carbonate needs to be added to generate metallic arsenic in one step. The calcium sulfide generated simultaneously can be used in insecticides and luminescent paints, maximizing resource utilization. Furthermore, since the sulfur in arsenic sulfide exists primarily as calcium sulfide after the reaction, this invention also solves the problem of sulfur dioxide gas generation in traditional pyrometallurgical processes. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a photograph of the metallic arsenic product in Example 1 of the present invention; Figure 2 The image shows the XRD pattern of the metallic arsenic product in Example 1 of this invention. Figure 3 Here is a SEM image of the metallic arsenic product in Example 1 of this invention; Figure 4 This is a photograph of the roasting residue in Example 1 of the present invention; Figure 5 The image shown is the XRD pattern of the roasted slag in Example 1 of this invention. Figure 6 This is a SEM image of the roasted slag in Example 1 of the present invention.

[0020] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0024] This invention provides a method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source, comprising: A reaction vessel is provided, the reaction vessel having a high-temperature zone and a low-temperature zone connected together; arsenic sulfide slag, calcium carbonate, and a carbon source are reacted in the high-temperature zone; during the reaction, the generated metallic arsenic is transferred towards the low-temperature zone, and the generated calcium sulfide remains in the high-temperature zone.

[0025] In this invention, the reaction vessel includes a horizontally placed tube; in some more specific embodiments, the reaction vessel is a multi-temperature zone tubular quartz furnace, the main structure of which includes a sealed quartz tube and a heating furnace body sleeved outside the quartz tube, wherein the high-temperature zone and the low-temperature zone are equipped with independent heating elements and temperature control systems, enabling independent temperature adjustment.

[0026] In this invention, the atmosphere of the reaction vessel is one of air, vacuum, or inert gas. Further, the reaction vessel is in a vacuum environment or an inert gas environment; when the reaction vessel is in a vacuum environment, it means that after adding solid reactants to the reaction vessel, a vacuum treatment is performed, and the reaction vessel is sealed during the reaction process.

[0027] In this invention, the main component of the arsenic sulfide slag is arsenic sulfide, and the mass percentage of arsenic sulfide is 60-65%.

[0028] In this invention, the molar ratio of calcium carbonate to arsenic sulfide in the arsenic sulfide slag is not less than 3; further, the molar ratio of calcium carbonate to arsenic sulfide in the arsenic sulfide slag is 3-5:1, or more specifically 3.5-4, 3-3.5, 3-4, 3.5-5, or 4-5.

[0029] In this invention, the molar ratio of carbon in the carbon source to arsenic sulfide in the arsenic sulfide slag is not less than 3. In some embodiments of this invention, the carbon source includes at least one of elemental carbon, methane, and carbon monoxide.

[0030] In some specific embodiments of the present invention, the carbon source includes or is elemental carbon, and the molar ratio of the elemental carbon to the arsenic sulfide in the arsenic sulfide slag is not less than 5, and further 5-6:1; in this case, the carbon source is at least one of activated carbon and coal.

[0031] In some other specific embodiments of the present invention, the carbon source includes or is carbon monoxide, and the molar ratio of the carbon monoxide to the arsenic sulfide slag is 3-6:1, further 3-5:1, 3.5-5:1, 3-3.5:1, or 3.5-6:1.

[0032] In this invention, when the carbon source is solid, the arsenic sulfide slag, the calcium carbonate, and the carbon source are ground together and then placed in the high-temperature zone. When the carbon source is gaseous, the arsenic sulfide slag and the calcium carbonate are ground together and then placed in the high-temperature zone, and the gaseous carbon source is introduced; before introducing the gaseous carbon source, the reaction vessel can be vacuum-treated.

[0033] In the reaction process of this invention, the temperature of the high-temperature zone is 800-950℃; further, the temperature of the high-temperature zone is 850-950℃, or 800-900℃, or 800-850℃, or 850-900℃, or 900-950℃, or 800-810℃, or 840-860℃, or 890-910℃. The temperature of the low-temperature zone is 600-750℃, further 650-750℃, or 640-750℃, or 650-700℃, or 700-750℃, or 600-650℃, or 600-620℃, or 640-660℃, or 730-750℃.

[0034] In this invention, the temperature of the high-temperature zone is greater than the temperature of the low-temperature zone; the temperature difference between the high-temperature zone and the low-temperature zone is not less than 50°C, and the temperature difference between the high-temperature zone and the low-temperature zone is further 50-350°C. For example, the temperature difference between the high-temperature zone and the low-temperature zone can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, or a range consisting of any two of these values.

[0035] In this invention, the reaction time is not less than 0.5 h; further, the reaction time is 0.5-2.5 h, 0.5-1 h, 1-1.5 h, 1.5-2 h, 2-2.5 h, 1.5-2.5 h, or 1.4-1.6 h. The reaction time in this invention refers to the holding time after both the high-temperature zone and the low-temperature zone have reached their corresponding temperatures.

[0036] In the reaction process of this invention, the low-temperature zone and the high-temperature zone are maintained at corresponding temperatures; when the carbon source includes elemental carbon or carbon monoxide, the following reaction occurs: As2S3+ 3CaCO3+ 5C = 2As + 3CaS + 7CO(g) + CO2(g); As2S3+ 3CaCO3+ 3CO(g) = 2As + 3CaS + 6CO2(g).

[0037] During the reaction, the arsenic sulfide slag, the calcium carbonate, and the metallic arsenic generated from the carbon source are transferred from the high-temperature zone to the low-temperature zone and collected after solidification; the generated calcium sulfide remains in the high-temperature zone and is collected after cooling.

[0038] Before the reaction, the present invention heats the high-temperature zone and the low-temperature zone at a rate of 5-15°C / min. For example, the heating rate can be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, or any range of two of these values.

[0039] In this invention, after the reaction is completed, the high-temperature zone and the low-temperature zone are naturally cooled to room temperature; then the calcium sulfide product in the high-temperature zone and the metallic arsenic product in the low-temperature zone are collected.

[0040] It should be understood that developing a low-cost, high-efficiency method that can complete the treatment of arsenic sulfide slag in one step and effectively recover valuable metals while avoiding environmental pollution has become a technical problem that urgently needs to be solved in this field. This invention explores and obtains a high-efficiency, low-cost, high-economic-benefit method for treating arsenic sulfide slag in one step.

[0041] This invention utilizes calcium carbonate and a carbon source to recover metallic arsenic from arsenic sulfide slag. Using the arsenic sulfide slag, calcium carbonate, and carbon source as raw materials, they are placed in a high-temperature zone with independent temperature control for reaction. The resulting metallic arsenic is then deposited in a low-temperature zone. This invention achieves efficient preparation of metallic arsenic and simultaneous fixation of sulfur in a one-step process. The reaction products are completely separated, resulting in high-purity metallic arsenic. Simultaneously, sulfur is effectively fixed in the slag phase, avoiding secondary pollution. The metallic arsenic prepared by this invention can be applied in optoelectronic materials, alloys, semiconductors, and other fields; the calcium sulfide in the roasted slag can be used as a depilatory agent, insecticide, and in the production of luminescent paints. This invention features a short and low-cost process, providing an efficient and feasible technical solution for the harmless treatment and resource utilization of arsenic sulfide slag, with significant environmental and economic benefits.

[0042] The following are specific examples of the present invention: In this invention, the recovery rate of metallic arsenic products refers to: (mass of metallic arsenic products ÷ mass of arsenic in arsenic sulfide slag) × 100%; the purity of metallic arsenic products refers to: the atomic percentage of arsenic in metallic arsenic products.

[0043] The arsenic sulfide slag used in all cases of this invention is from the same batch. The main component of the arsenic sulfide slag is arsenic sulfide, accounting for about 63% by mass. The surface elemental composition and content of the arsenic sulfide slag were analyzed by SEM-EDS, and the mass percentage of each element is shown in Table 1.

[0044] Example 1 A method for treating arsenic sulfide slag, comprising the following steps: S1, weigh arsenic sulfide slag, calcium carbonate, and activated carbon powder as raw materials, and grind them in a mortar to obtain a mixture; the molar ratio of arsenic sulfide, calcium carbonate, and carbon is 1:3.5:5.

[0045] After the mixture is loaded into one end of the quartz tube, it is placed horizontally in a multi-temperature zone tube furnace. The quartz tube is then vacuum treated and sealed. The position of the mixture is the high-temperature zone, and the other end of the quartz tube, which is horizontally opposite to the high-temperature zone, is the low-temperature zone.

[0046] S2, the high-temperature zone is heated to 900 ℃ at a heating rate of 10℃ / min, and the low-temperature zone is simultaneously heated to 750 ℃ ​​at a heating rate of 10℃ / min, and then kept at that temperature for 1.5h.

[0047] After the heat preservation is completed, the mixture is allowed to cool naturally to room temperature; collect the metallic arsenic products in the low-temperature zone and the roasted residue in the high-temperature zone.

[0048] See Figure 1 As shown, metallic arsenic products have a metallic luster; see also Figures 2-3As shown, the main product of metallic arsenic is metallic arsenic; in this embodiment, the recovery rate of metallic arsenic product is 99.31%. See also Figures 4-6 As shown, the roasting slag is mainly calcium sulfide.

[0049] The surface elemental composition and content of metallic arsenic products and roasted slag were analyzed by SEM-EDS. The atomic percentage of each element is shown in Table 2.

[0050] As shown in Table 2, the purity of the metallic arsenic product is extremely high, with a purity of 99.80%. The main component of the roasting slag is calcium sulfide, with only a small amount of arsenic remaining.

[0051] Example 2 A method for treating arsenic sulfide slag, comprising the following steps: S1. Arsenic sulfide slag and calcium carbonate are ground and mixed and placed at one end of a quartz tube. After vacuum treatment, carbon monoxide is introduced and the tube is sealed. The molar ratio of arsenic sulfide, calcium carbonate and carbon monoxide is 1:3:3. The quartz tube is placed horizontally in a multi-temperature zone tube furnace. The arsenic sulfide slag and calcium carbonate are placed in the high-temperature zone, and the other end of the quartz tube opposite the high-temperature zone in the horizontal direction is the low-temperature zone.

[0052] S2, the high-temperature zone is heated to 850℃ at a heating rate of 10℃ / min, and the low-temperature zone is simultaneously heated to 650℃ at a heating rate of 10℃ / min, and then kept at that temperature for 1.5h.

[0053] S3, after the heat preservation ends, is naturally cooled to room temperature, and metallic arsenic products in the low-temperature zone and roasted slag in the high-temperature zone are collected.

[0054] In this embodiment, the recovery rate of metallic arsenic product was 99.76%, and the purity of metallic arsenic product was 99.34%.

[0055] Example 3 A method for treating arsenic sulfide slag, comprising the following steps: S1. Arsenic sulfide slag and calcium carbonate are ground and mixed and placed at one end of a quartz tube. After vacuum treatment, carbon monoxide is introduced and the tube is sealed. The molar ratio of arsenic sulfide, calcium carbonate and carbon monoxide is 1:3:3.5. The quartz tube is placed horizontally in a multi-temperature zone tube furnace. The arsenic sulfide slag and calcium carbonate are placed in the high-temperature zone, and the other end of the quartz tube opposite the high-temperature zone in the horizontal direction is the low-temperature zone.

[0056] S2, the high-temperature zone is heated to 850℃ at a heating rate of 10℃ / min, and the low-temperature zone is simultaneously heated to 650℃ at a heating rate of 10℃ / min, and then kept at that temperature for 1.5h.

[0057] S3, after the heat preservation ends, is naturally cooled to room temperature, and metallic arsenic products in the low-temperature zone and roasted slag in the high-temperature zone are collected.

[0058] In this embodiment, the recovery rate of metallic arsenic product was 99.05%, and the purity of metallic arsenic product was 99.29%.

[0059] Example 4 A method for treating arsenic sulfide slag, comprising the following steps: S1. Arsenic sulfide slag and calcium carbonate are ground and mixed and placed at one end of a quartz tube. After vacuum treatment, carbon monoxide is introduced and the tube is sealed. The molar ratio of arsenic sulfide, calcium carbonate and carbon monoxide is 1:4:3. The quartz tube is placed horizontally in a multi-temperature zone tube furnace. The arsenic sulfide slag and calcium carbonate are placed in the high-temperature zone, and the other end of the quartz tube opposite the high-temperature zone in the horizontal direction is the low-temperature zone.

[0060] S2, the high-temperature zone is heated to 850℃ at a heating rate of 10℃ / min, and the low-temperature zone is simultaneously heated to 650℃ at a heating rate of 10℃ / min, and then kept at that temperature for 1.5h.

[0061] S3, after the heat preservation ends, is naturally cooled to room temperature, and metallic arsenic products in the low-temperature zone and roasted slag in the high-temperature zone are collected.

[0062] In this embodiment, the recovery rate of metallic arsenic product was 99.08%, and the purity of metallic arsenic product was 98.75%.

[0063] Example 5 A method for treating arsenic sulfide slag, comprising the following steps: S1. Arsenic sulfide slag and calcium carbonate are ground and mixed and placed at one end of a quartz tube. After vacuum treatment, carbon monoxide is introduced and the tube is sealed. The molar ratio of arsenic sulfide, calcium carbonate and carbon monoxide is 1:3:3. The quartz tube is placed horizontally in a multi-temperature zone tube furnace. The arsenic sulfide slag and calcium carbonate are placed in the high-temperature zone, and the other end of the quartz tube opposite the high-temperature zone in the horizontal direction is the low-temperature zone.

[0064] S2, the high-temperature zone is heated to 800℃ at a heating rate of 10℃ / min, and the low-temperature zone is simultaneously heated to 650℃ at a heating rate of 10℃ / min, and then kept at that temperature for 1.5h.

[0065] S3, after the heat preservation ends, is naturally cooled to room temperature, and metallic arsenic products in the low-temperature zone and roasted slag in the high-temperature zone are collected.

[0066] In this embodiment, the recovery rate of metallic arsenic product was 95.72%, and the purity of metallic arsenic product was 99.31%.

[0067] Example 6 A method for treating arsenic sulfide slag, comprising the following steps: S1. Arsenic sulfide slag and calcium carbonate are ground and mixed and placed at one end of a quartz tube. After vacuum treatment, carbon monoxide is introduced and the tube is sealed. The molar ratio of arsenic sulfide, calcium carbonate and carbon monoxide is 1:3:3. The quartz tube is placed horizontally in a multi-temperature zone tube furnace. The arsenic sulfide slag and calcium carbonate are placed in the high-temperature zone, and the other end of the quartz tube opposite the high-temperature zone in the horizontal direction is the low-temperature zone.

[0068] S2, the high-temperature zone is heated to 850℃ at a heating rate of 10℃ / min, and the low-temperature zone is simultaneously heated to 600℃ at a heating rate of 10℃ / min, and then kept at that temperature for 1.5h.

[0069] S3, after the heat preservation ends, is naturally cooled to room temperature, and metallic arsenic products in the low-temperature zone and roasted slag in the high-temperature zone are collected.

[0070] In this embodiment, the recovery rate of metallic arsenic product was 81.94%, and the purity of metallic arsenic product was 99.17%.

[0071] Example 7 Compared to Example 1, this example only adjusts the heat preservation time to 0.5h, 1h, 2h, and 2.5h, while keeping other conditions unchanged.

[0072] In this embodiment, after heat preservation for 0.5 hours, the recovery rate of the metallic arsenic product was 92.17%, and the purity of the metallic arsenic product was 98.45%. In this embodiment, after 1 hour of heat preservation, the recovery rate of the metallic arsenic product was 93.59%, and the purity of the metallic arsenic product was 99.88%. In this embodiment, after 2 hours of heat preservation, the recovery rate of the metallic arsenic product was 97.89%, and the purity of the metallic arsenic product was 99.25%. In this embodiment, after heat preservation for 2.5 hours, the recovery rate of the metallic arsenic product was 95.51%, and the purity of the metallic arsenic product was 98.63%.

[0073] Comparative Example 1 Compared to Example 1, this comparative example only adjusts the molar ratio of arsenic sulfide, calcium carbonate, and carbon to 1:3.5:1, while keeping other conditions unchanged.

[0074] In this comparative example, the recovery rate of metallic arsenic products was 5.31%, and the purity of metallic arsenic products was 98.64%.

[0075] Comparative Example 2 Compared to Example 2, this comparative example only adjusts the molar ratio of arsenic sulfide, calcium carbonate, and carbon monoxide to 1:3:1, while keeping other conditions unchanged.

[0076] In this comparative example, the recovery rate of metallic arsenic products was 17.04%, and the purity of metallic arsenic products was 99.31%.

[0077] Comparative Example 3 Compared to Example 2, this comparative example only adjusts the molar ratio of arsenic sulfide, calcium carbonate, and carbon monoxide to 1:1:3, while keeping other conditions unchanged.

[0078] In this comparative example, the recovery rate of metallic arsenic products was 15.17%, and the purity of metallic arsenic products was 98.76%.

[0079] Comparative Example 4 Compared to Example 2, this comparative example only adjusts the temperature of the high-temperature zone to 700°C, while keeping other conditions unchanged.

[0080] In this comparative example, the recovery rate of metallic arsenic products was 23.65%, and the purity of metallic arsenic products was 98.95%.

[0081] Comparative Example 5 Compared to Example 2, this comparative example only adjusts the temperature of the low-temperature zone to 550°C, while keeping other conditions unchanged.

[0082] In this comparative example, the recovery rate of metallic arsenic products was 23.16%, and the purity of metallic arsenic products was 98.72%.

[0083] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source, characterized in that, include: A reaction vessel is provided, the reaction vessel having a high-temperature zone and a low-temperature zone connected in communication; Arsenic sulfide slag, calcium carbonate, and carbon source are reacted in the high-temperature zone; during the reaction, the generated metallic arsenic is transferred towards the low-temperature zone. The molar ratio of calcium carbonate to arsenic sulfide in the arsenic sulfide slag is not less than 3; the molar ratio of carbon in the carbon source to arsenic sulfide in the arsenic sulfide slag is not less than 3; the temperature of the high-temperature zone is 800-950℃, and the temperature of the low-temperature zone is 600-750℃.

2. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 1, characterized in that, The carbon source includes at least one of elemental carbon, methane, and carbon monoxide.

3. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 2, characterized in that, The carbon source includes the elemental carbon, and the molar ratio of the elemental carbon to the arsenic sulfide in the arsenic sulfide slag is not less than 5.

4. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 2, characterized in that, The carbon source includes the carbon monoxide, and the molar ratio of the carbon monoxide to the arsenic sulfide in the arsenic sulfide slag is 3-6:

1.

5. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 1, characterized in that, The molar ratio of calcium carbonate to arsenic sulfide in the arsenic sulfide slag is 3-5:

1.

6. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 1, characterized in that, The temperature of the low-temperature zone is 650-750℃.

7. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 1, characterized in that, The reaction time is not less than 0.5 h.

8. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 7, characterized in that, The reaction time is 0.5-2.5 hours.

9. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to claim 1, characterized in that, Before the reaction is carried out, the heating rate of the high-temperature zone and the low-temperature zone is 5-15℃ / min; After the reaction is completed, the high-temperature zone and the low-temperature zone are allowed to cool naturally to room temperature.

10. The method for recovering metallic arsenic from arsenic sulfide slag using calcium carbonate and a carbon source according to any one of claims 1-9, characterized in that, The reaction vessel includes a horizontally placed tube. The atmosphere of the reaction vessel is one of air, vacuum, or inert gas.

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