A method for preparing elemental sulfur and metallic arsenic by using arsenic sulfide residue

Abstract

The application discloses a method for preparing elemental sulfur and metallic arsenic by using arsenic sulfide residue, which comprises the following steps: providing arsenic sulfide residue; mixing the arsenic sulfide residue with lignin and acid liquor, and heating to a first preset temperature to obtain preheated ore slurry; introducing steam and oxygen into the preheated ore slurry, and reacting at a second preset temperature and a preset oxygen partial pressure for a first predetermined time, and then performing solid-liquid separation treatment to obtain leaching liquor and leaching residue; heating and melting the leaching residue at a third preset temperature, and performing hot filtration to obtain elemental sulfur; adding a reducing agent to the leaching liquor, and reacting at a fourth preset temperature for a second predetermined time, and then performing solid-liquid separation treatment to obtain metallic arsenic and arsenic precipitation liquid. The method can convert arsenic into solution by controlling oxygen leaching, and sulfur is enriched in the leaching residue in the form of elemental sulfur, and then the elemental sulfur and the metallic arsenic are respectively produced through an elemental sulfur preparation process and a hydrogen reduction process, so that the method has the technical advantages of simple process flow, safe product, no secondary hazardous waste generation and the like.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and in particular to a method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag. Background Technology

[0002] Arsenic is widely found in mineral resources such as gold, copper, zinc, lead, tin, and nickel. During the smelting of these metals, approximately 50% of the arsenic enters the smelting flue gas, and during flue gas purification and washing, the arsenic is transferred to the waste acid. Currently, the main industrial method for removing arsenic from waste acid is arsenic precipitation via sulfide treatment. The resulting arsenic sulfide slag typically contains 30-40% arsenic and 20-30% sulfur. Arsenic sulfide slag is unstable and is a hazardous solid waste that is explicitly required to undergo harmless treatment by national regulations. Arsenic sulfide slag production enterprises usually incur high hazardous waste disposal costs by entrusting qualified units to perform harmless treatment.

[0003] To reduce the disposal costs of arsenic sulfide slag and achieve its resource utilization, the main treatment method is to convert it into arsenic trioxide. There are two main processes: one is a drying-dehydration-high-temperature oxidation roasting-rapid arsenic removal process to produce arsenic trioxide, which yields arsenic trioxide with a purity of approximately 95%, requiring further purification to over 99%; the other is a pressure leaching-sulfur dioxide reduction-cooling crystallization process. However, the market for arsenic trioxide is currently in a state of oversupply, and due to its extremely high toxicity, arsenic trioxide must undergo harmless treatment as a highly toxic substance. This has limited the production of arsenic trioxide from arsenic sulfide slag, leading to a continuous shrinking of its industrial application.

[0004] Gallium arsenide is an important semiconductor material; however, the development of gallium arsenide production is limited by the complexity of the process, high cost, and the high toxicity of the raw material arsenic trioxide.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, aiming to solve the problems of complex process flow, high toxicity of intermediate products, and easy generation of secondary hazardous waste in the resource utilization of existing arsenic sulfide slag.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] A method for preparing elemental sulfur and metallic arsenic from arsenic sulfide slag, comprising the steps of:

[0009] Provide arsenic sulfide slag;

[0010] The arsenic sulfide slag is mixed with lignin and acid solution and heated to a first preset temperature to obtain a preheated slurry.

[0011] Steam and oxygen are introduced into the preheated slurry, and after reacting for a first predetermined time at a second preset temperature and preset oxygen partial pressure, solid-liquid separation is performed to obtain leachate and leach residue.

[0012] The leaching residue is heated and melted at a third preset temperature, and then hot filtered to obtain elemental sulfur;

[0013] A reducing agent is added to the leachate, and the mixture is reacted at a fourth preset temperature for a second predetermined time. Solid-liquid separation is then performed to obtain metallic arsenic and arsenic-precipitated liquid.

[0014] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the mass-to-volume ratio of the arsenic sulfide slag and the lignin to the acid solution is 1 kg: (4-10) L.

[0015] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the first preset temperature is 50-90℃.

[0016] The method for preparing elemental sulfur and metallic arsenic from arsenic sulfide slag, wherein, after the step of obtaining the leachate and the leachate slag, further includes the following step:

[0017] The leaching residue is mixed with water to obtain a mixed slurry;

[0018] The mixed slurry is subjected to pulping and washing, followed by solid-liquid separation to obtain wash water and wash residue.

[0019] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the acid solution is a mixed solution of the washing water, 98% concentrated sulfuric acid, and the arsenic precipitation liquid.

[0020] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the concentration of the acid solution is 70–160 g / L.

[0021] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the second preset temperature is 60-150℃, the preset oxygen partial pressure is 0.5-1.5 MPa, and the first predetermined time is 1-5 h.

[0022] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the third preset temperature is 120-140℃.

[0023] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the fourth preset temperature is 30-95℃ and the second preset time is 1-5h.

[0024] The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, wherein the reducing agent is hydrogen gas; and the concentration of arsenic ions in the arsenic precipitation solution is less than 1000 mg / L.

[0025] Beneficial effects: This invention discloses a method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag. Arsenic is transferred into the solution through controlled oxygen leaching, while sulfur is enriched in the leaching slag in elemental form. Elemental sulfur and metallic arsenic are then produced through elemental sulfur preparation and hydrogen reduction processes, respectively. The arsenic-precipitated liquid is returned to the controlled oxygen leaching process. This method has technical advantages such as simple process flow, safe products, and no secondary hazardous waste generation. Attached Figure Description

[0026] Figure 1 This is a flowchart of a preferred embodiment of the method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag provided by the present invention. Detailed Implementation

[0027] This invention provides a method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] 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 merely some embodiments of the present invention, not all embodiments, and are intended only to illustrate the present invention and not to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] To reduce the disposal costs of arsenic sulfide slag and achieve its resource utilization, the main treatment method is to convert it into arsenic trioxide. There are two main processes: one is a drying-dehydration-high-temperature oxidation roasting-rapid arsenic removal process to produce arsenic trioxide, which yields arsenic trioxide with a purity of approximately 95%, requiring further purification to over 99%; the other is a pressure leaching-sulfur dioxide reduction-cooling crystallization process. However, the market for arsenic trioxide is currently in a state of oversupply, and due to its extremely high toxicity, arsenic trioxide must undergo harmless treatment as a highly toxic substance. This has limited the production of arsenic trioxide from arsenic sulfide slag, leading to a continuous shrinking of its industrial application.

[0030] Based on this, the present invention provides a method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, see [link to relevant documentation]. Figure 1 It includes the following steps:

[0031] S10, provides arsenic sulfide slag;

[0032] S20. The arsenic sulfide slag is mixed with lignin and acid solution and heated to a first preset temperature to obtain a preheated slurry.

[0033] S30. Steam and oxygen are introduced into the preheated slurry, and after reacting for a first predetermined time at a second preset temperature and preset oxygen partial pressure, solid-liquid separation is performed to obtain leachate and leachate residue.

[0034] S40. The leaching residue is heated and melted at a third preset temperature, and then hot filtered to obtain elemental sulfur.

[0035] S50. Add a reducing agent to the leachate, react at a fourth preset temperature for a second predetermined time, and perform solid-liquid separation treatment to obtain metallic arsenic and arsenic-precipitated liquid.

[0036] Specifically, this invention uses controlled oxygen leaching to transfer arsenic into the solution while sulfur is enriched in the leaching residue in elemental form. Elemental sulfur and metallic arsenic are then produced through an elemental sulfur preparation process and a hydrogen reduction process, respectively. The arsenic-precipitated liquid is returned to the controlled oxygen leaching process. This invention has technical advantages such as simple process flow, safe products, and no secondary hazardous waste generation.

[0037] Specifically, in step S10, the arsenic sulfide slag contains 30-42% arsenic and 20-30% sulfur on a dry basis; in step S20, the acid solution is obtained by diluting industrial concentrated sulfuric acid with a concentration of 98%. The arsenic-precipitated liquid can be returned for use as acid solution and used for slurry preparation and leaching, thereby reducing the output of wastewater in the process and the generation of secondary hazardous waste residue from wastewater purification treatment.

[0038] In some embodiments, the mass-to-volume ratio of the arsenic sulfide slag and the lignin to the acid solution is 1 kg: (4-10) L.

[0039] In some embodiments, the first preset temperature is 50–90°C.

[0040] In some embodiments, in step S20, the sulfur content in the leaching residue is greater than 70% by mass, and the arsenic concentration in the leachate is 50-60 g / L, with an As(III) content greater than 90%. By controlling oxygen leaching, efficient leaching and valence state control of arsenic in arsenic sulfide slag can be achieved, resulting in a leachate that is beneficial for subsequent arsenic recovery. After hydrogen reduction, the arsenic in the leachate is recovered as metallic arsenic products.

[0041] In some embodiments, after the steps of obtaining the leachate and the leachate residue, the method further includes the step of:

[0042] The leaching residue is mixed with water to obtain a mixed slurry;

[0043] The mixed slurry is subjected to pulping and washing, followed by solid-liquid separation to obtain wash water and wash residue.

[0044] Optionally, the mass-to-volume ratio of the leaching residue to the water is 1 kg: (2-5) L.

[0045] In some embodiments, the acid solution is a mixture of the wash water, 98% concentrated sulfuric acid, and the arsenic precipitation solution.

[0046] In some embodiments, the concentration of the acid solution is 70–160 g / L.

[0047] In some embodiments, in step S30, the steam is high-temperature water vapor, which mainly serves the functions of heating and heat exchange. The second preset temperature is 60-150°C, the preset oxygen partial pressure is 0.5-1.5 MPa, and the first predetermined time is 1-5 hours. Under these conditions, the oxidation and dissolution of arsenic sulfide can be achieved. The specific reaction formula is As2S3+2O2+2H2O=2H3AsO3+3S.

[0048] In some embodiments, the third preset temperature is 120–140°C.

[0049] In some embodiments, in step S40, the fourth preset temperature is 30-95°C and the second preset time is 1-5 hours. Under these conditions, metallic arsenic can be prepared, and the specific reaction formula is 2H3AsO3+3H2=2As+6H2O.

[0050] In some embodiments, the reducing agent is hydrogen gas; the concentration of arsenic ions in the arsenic-precipitated solution is less than 1000 mg / L.

[0051] Specifically, clean and efficient hydrogen is used as a reducing agent, which reduces the introduction of impurity elements and the purification of impurity elements in the solution. In the overall preparation process, the reaction rate can be controlled by adjusting the temperature. The higher the temperature, the faster the reaction rate. The specific temperature can be set according to the actual production needs.

[0052] 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 merely some embodiments of the present invention, not all embodiments, and are intended only to illustrate the present invention and not to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] A method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, comprising the following specific steps:

[0055] (1) Slurry preparation: The solid materials such as arsenic sulfide slag (dry basis composition: arsenic 30.2% and sulfur 20.6%), lignin and other solid materials are mixed with the arsenic precipitation liquid, concentrated sulfuric acid and washing water to form an acid solution with an acidity of 160g / L at a solid-liquid ratio of 1:4kg:L and then preheated to 50℃.

[0056] (2) Oxygen-controlled leaching: The preheated slurry from step (1) is fed into a sealed reaction vessel equipped with a stirring device. Steam and oxygen are introduced into the vessel at the same time. The reaction temperature is controlled at 60°C and the oxygen partial pressure is 1.5 MPa. After the reaction is carried out for 5 hours, the slurry is separated into liquid and solid to obtain a leaching solution containing 73.8 g / L of arsenic and 68.4 g / L of As(III) and leaching residue. The leaching residue is mixed with water at a solid-liquid ratio of 1:2 kg:L and slurry washing is carried out in a normal pressure stirred reaction tank. After slurry washing, liquid-solid separation is carried out to obtain wash water and wash residue. The wash water is returned to the slurry preparation process and the wash residue is further used to recover elemental sulfur.

[0057] (3) Preparation of elemental sulfur: The leaching residue produced in step (2) is heated and melted in the temperature range of 130°C and then filtered to produce elemental sulfur product;

[0058] (4) Preparation of metallic arsenic: The leachate produced in step (2) is sent into a closed stirring reaction tank, and hydrogen is continuously introduced into the tank until the concentration of residual arsenic ions in the arsenic-precipitated liquid is less than 300 mg / L. The reaction temperature is controlled at 95°C and the reaction time is 5 hours. Then the reaction slurry is separated into liquid and solid to obtain metallic arsenic product and arsenic-precipitated liquid. The arsenic-precipitated liquid is returned to the slurry adjustment process.

[0059] After treating the arsenic sulfide slag using this embodiment, the arsenic leaching rate of the oxygen-controlled leaching process is 98.5%, the purity of the elemental sulfur product is 99.8%, and the arsenic content of the metallic arsenic product is 99.5%.

[0060] Example 2

[0061] A method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, comprising the following specific steps:

[0062] (1) Slurry preparation: The solid materials such as arsenic sulfide slag (dry basis composition: arsenic 42.0%, sulfur 33.6%), lignin and other solid materials are mixed with the arsenic precipitation liquid, concentrated sulfuric acid and washing water, and the acidity is 140g / L. The mixture is then preheated to 80℃.

[0063] (2) Oxygen-controlled leaching: The preheated slurry from step (1) is fed into a sealed reaction vessel equipped with a stirring device. At the same time, steam and oxygen are introduced into the vessel to control the reaction temperature at 150℃ and the oxygen partial pressure at 0.5MPa. After the reaction is carried out for 3 hours, the reaction slurry is subjected to liquid-solid separation to obtain a leaching solution containing 40.8g / L of arsenic and 36.5g / L of As(Ⅲ) and leaching residue. The leaching residue is mixed with water at a solid-liquid ratio of 1:5kg:L and slurry washing is carried out in a normal pressure stirred reaction tank. After slurry washing, liquid-solid separation is carried out to obtain wash water and wash residue. The wash water is returned to the slurry preparation process, and the wash residue is further used to recover elemental sulfur.

[0064] (3) Preparation of elemental sulfur: The leaching residue produced in step (2) is heated and melted in a temperature range of 120°C and then filtered to produce elemental sulfur product;

[0065] (4) Preparation of metallic arsenic: The leachate produced in step (2) is sent into a closed stirring reaction tank, and hydrogen is continuously introduced into the tank until the concentration of residual arsenic ions in the arsenic-precipitated liquid is less than 1000 mg / L. The reaction temperature is controlled at 30°C and the reaction time is 1 hour. Then the reaction slurry is separated into liquid and solid to obtain metallic arsenic product and arsenic-precipitated liquid. The arsenic-precipitated liquid is returned to the slurry adjustment process.

[0066] After treating the arsenic sulfide slag using this embodiment, the arsenic leaching rate of the oxygen-controlled leaching process is 95.3%, the purity of the elemental sulfur product is 99.2%, and the arsenic content of the metallic arsenic product is 99.0%.

[0067] Example 3

[0068] A method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag, comprising the following specific steps:

[0069] (1) Slurry preparation: The solid materials such as arsenic sulfide slag (dry basis composition: arsenic 36.3%, sulfur 24.1%), lignin and other solid materials are mixed with the arsenic precipitation liquid, concentrated sulfuric acid and washing water to form an acid solution with an acidity of 70 g / L at a solid-liquid ratio of 1:6 kg:L and then preheated to 70℃.

[0070] (2) Oxygen-controlled leaching: The preheated slurry from step (1) is fed into a sealed reaction vessel equipped with a stirring device. Steam and oxygen are introduced into the vessel at the same time. The reaction temperature is controlled at 130℃ and the oxygen partial pressure is 0.8MPa. After the reaction is carried out for 1 hour, the slurry is subjected to liquid-solid separation to obtain a leaching solution containing 58.1g / L of arsenic and 52.1g / L of As(Ⅲ) and leaching residue. The leaching residue is mixed with water at a solid-liquid ratio of 1:3kg:L and slurry washing is carried out in a normal pressure stirred reaction tank. After slurry washing, liquid-solid separation is carried out to obtain wash water and wash residue. The wash water is returned to the slurry preparation process and the wash residue is further used to recover elemental sulfur.

[0071] (3) Preparation of elemental sulfur: The leaching residue produced in step (2) is heated and melted in a temperature range of 140°C and then filtered to produce elemental sulfur product;

[0072] (4) Preparation of metallic arsenic: The leachate produced in step (2) is sent into a closed stirring reaction tank, and hydrogen is continuously introduced into the tank until the concentration of residual arsenic ions in the arsenic-precipitated liquid is lower than 600 mg / L. The reaction temperature is controlled at 60°C and the reaction time is 3 hours. Then the reaction slurry is separated into liquid and solid to obtain metallic arsenic product and arsenic-precipitated liquid. The arsenic-precipitated liquid is returned to the slurry adjustment process.

[0073] After treating the arsenic sulfide slag using this embodiment, the arsenic leaching rate of the oxygen-controlled leaching process is 96.7%, the purity of the elemental sulfur product is 99.6%, and the arsenic content of the metallic arsenic product is 99.3%.

[0074] In summary, this invention discloses a method for preparing elemental sulfur and metallic arsenic from arsenic sulfide slag, comprising the following steps: providing arsenic sulfide slag; mixing the arsenic sulfide slag with lignin and acid, heating to a first preset temperature to obtain a preheated slurry; introducing steam and oxygen into the preheated slurry, reacting at a second preset temperature and a preset oxygen partial pressure for a first predetermined time, followed by solid-liquid separation to obtain a leachate and a leaching residue; heating and melting the leaching residue at a third preset temperature, followed by hot filtration to obtain elemental sulfur; adding a reducing agent to the leaching solution, reacting at a fourth preset temperature for a second predetermined time, followed by solid-liquid separation to obtain metallic arsenic and a precipitated arsenic solution. This invention uses controlled oxygen leaching to transfer arsenic into solution while sulfur is enriched in elemental form in the leaching residue. Elemental sulfur and metallic arsenic are then produced through an elemental sulfur preparation process and a hydrogen reduction process, respectively. The precipitated arsenic solution is returned to the controlled oxygen leaching process. This method has advantages such as simple process flow, safe products, and no secondary hazardous waste generation.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing elemental sulfur and metallic arsenic using arsenic sulfide residue, characterized by, Including the following steps: Provide arsenic sulfide slag; The arsenic sulfide slag is mixed with lignin and acid solution and heated to a first preset temperature to obtain a preheated slurry. Steam and oxygen are introduced into the preheated slurry, and after reacting for a first predetermined time at a second preset temperature and preset oxygen partial pressure, solid-liquid separation is performed to obtain leachate and leach residue. The leaching residue is heated and melted at a third preset temperature, and then hot filtered to obtain elemental sulfur; Hydrogen gas was added to the leachate, and the mixture was reacted at 30-95°C for 1-5 hours. The solid and liquid were then separated to obtain metallic arsenic and arsenic-precipitated liquid.

2. The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide slag according to claim 1, characterized in that, The mass-to-volume ratio of the arsenic sulfide slag, the lignin, and the acid solution is 1 kg: (4~10) L.

3. The method of claim 1, wherein the method is characterized by, The first preset temperature is 50~90℃.

4. The method of claim 1, wherein the method is characterized by, After the steps of obtaining the leachate and the leachate residue, the method further includes the following step: The leaching residue is mixed with water to obtain a mixed slurry; The mixed slurry is subjected to pulping and washing, followed by solid-liquid separation to obtain wash water and wash residue.

5. The method for preparing elemental sulfur and metallic arsenic from arsenic sulfide slag according to claim 4, characterized in that, The acid solution is a mixture of the wash water, 98% concentrated sulfuric acid, and the arsenic precipitation solution. 6.The method for preparing elemental sulfur and metallic arsenic using arsenic sulfide residue according to claim 5, characterized in that, The concentration of the acid solution is 70~160g / L.

7. The method for preparing elemental sulfur and metallic arsenic from arsenic sulfide slag according to claim 1, characterized in that, The second preset temperature is 60~150℃, the preset oxygen partial pressure is 0.5~1.5Mpa, and the first preset time is 1~5h. 8.The method of claim 1, wherein the method further comprises: separating the elemental sulfur and the metallic arsenic from the sulfuric arsenic residue. The third preset temperature is 120~140℃.

9. The method for preparing elemental sulfur and metallic arsenic from arsenic sulfide slag according to claim 1, characterized in that, The concentration of arsenic ions in the arsenic-precipitated solution is less than 1000 mg / L.

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