Method for extracting silver from chlorine-free double-pressing deselenization residue

Abstract

The present application relates to the technical field of extracting silver from deselenium residue, and discloses a method for extracting silver from deselenium residue by chlorine-free double-pressure, silver is extracted from deselenium residue by chlorine-free leaching, silver in copper anode slime deselenium residue is leached by one-stage pressurization, one-stage leaching residue is sent to two-stage pressurized sulfidation transformation, sulfidation transformation residue is returned to one-stage pressurized leaching for silver extraction after roasting, one-stage leaching liquid is sent to silver recovery, and roasting leaching residue is sent to extract other valuable elements, so that the silver leaching rate is high, the impurity content of the obtained crude silver powder is low, the crude silver powder can be used as raw material for producing first-grade silver ingot, the disadvantage of needing to add a large amount of chloride in conventional silver extraction is overcome, other valuable elements are enriched, selective leaching of silver is ensured, and part of impurities is inhibited, the corrosion problem of the system equipment can be better solved due to the adoption of chlorine-free pressurized leaching, no new solid waste and waste liquid are generated in the whole process, the problem of difficult opening of the present process waste water is effectively solved, and resources are fully utilized.

Description

Technical Field

[0001] This invention relates to the technical field of extracting silver from deselenic residue, specifically a method for extracting silver from deselenic residue without chlorine and under dual pressure. Background Technology

[0002] The purpose of extracting silver from deselenic slag is to efficiently extract silver from slag containing selenium and other impurities.

[0003] In the process of precious metal extraction, the wet process of deselementation residue will produce two kinds of crude silver powder. The silver in the deselementation residue is leached at atmospheric pressure, but the leaching rate is less than 50%. The residue obtained by atmospheric pressure leaching is converted to silver chloride by chloride salt conversion, and then leached with sodium sulfite. The high chloride wastewater generated in the process is difficult to treat and will corrode the system equipment.

[0004] A search revealed that patent application number CN201410221865.0 discloses a fully wet pretreatment method for copper anode sludge. This invention first involves hot acid leaching of the copper anode sludge, leaching copper, selenium, silver, barium, and other metals into the solution, while gold, tellurium, tin, platinum, and platinum group metals remain in the leaching residue. The hot acid leaching residue is then subjected to alkaline leaching, enriching tellurium, lead, and arsenic in the solution. The resulting tellurium-separated residue is then subjected to chlorination to separate gold, enriching gold, platinum, and platinum group metals in the solution, while tin and antimony are enriched in the residue. The hot acid leaching solution is diluted with water, enriching copper and selenium in the diluted solution. The resulting precipitate is then dissolved in nitric acid and filtered to obtain barium sulfate residue and silver nitrate solution. This invention eliminates the energy-intensive and polluting sulfation roasting process in traditional copper anode sludge treatment methods. By removing barium through hot acid leaching before gold and silver extraction and recovering it via open-circuit, the amount of copper anode sludge processed is reduced, and the gold and silver recovery rate is increased.

[0005] The above-mentioned scheme and the use of chloride salt conversion will generate high-chloride wastewater. Therefore, we need to propose a chlorine-free dual-pressure extraction method for silver from selenium-depleted residue. Summary of the Invention

[0006] The purpose of this invention is to provide a chlorine-free dual-pressure extraction method for silver from deselenate slag. This method employs chlorine-free leaching to extract silver from the deselenate slag. The process involves a first-stage pressurized leaching of silver from copper anode mud deselenate slag, followed by a second-stage pressurized sulfidation transformation of the leached residue. The sulfidation transformation residue is then roasted and returned to the first-stage pressurized leaching for silver extraction, while the first-stage leaching solution is sent for silver recovery. The roasted leaching residue is then used to extract other valuable elements. This method not only achieves a high silver leaching rate and low impurity content in the obtained crude silver powder, which can be used entirely as raw material for producing first-grade silver ingots, but also overcomes the drawback of conventional silver extraction methods that require the addition of large amounts of chloride ions. Other valuable elements are enriched, selective silver leaching is ensured, and some impurities are suppressed. Because chlorine-free pressurized leaching is used, the corrosion problem of system equipment is effectively solved. Furthermore, the entire process generates no new solid waste or waste liquid, effectively solving the problem of difficult wastewater treatment in current processes, and fully utilizing resources, thus addressing the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for chlorine-free dual-pressure extraction of silver from deselenate residue, comprising the following steps:

[0008] S1. Pretreatment of deselenized residue: The deselenized residue is crushed and screened in advance to obtain small particles of deselenized residue with uniform particle size.

[0009] S2. Silver is extracted from the deselementized residue of copper anode mud using a single-stage pressure leaching method. After filtration, a first-stage leaching residue and a first-stage leaching solution are obtained. After recovering the silver from the first-stage leaching solution, the first-stage leaching solution is returned to continue the single-stage pressure leaching.

[0010] S3. The first-stage leaching residue is transformed with a sulfiding agent, and after filtration, sulfidation transformation residue and sulfidation transformation liquid are obtained. The sulfidation transformation liquid is returned to the first-stage leaching residue for further sulfidation transformation.

[0011] S4. The sulfide conversion slag is converted by roasting. The roasted slag is sent to a first-stage pressure leaching to extract silver. After filtration, roasted leaching slag and a first-stage leachate are obtained. The roasted leaching slag is sent to extract other valuable elements. After recovering the silver from the first-stage leachate, the first-stage leachate is returned to continue the first-stage pressure leaching.

[0012] Preferably, in step S1, a jaw crusher, cone crusher, or impact crusher is used to crush the large pieces of material in the deselement slag into granular material with a particle size of 80-100 mesh. After crushing, the granular deselement slag is screened using a vibrating screen, drum screen, or air classifier to ensure that the particle size of the deselement slag is uniform.

[0013] Preferably, in step S2, the pressure leaching silver extraction includes the following steps:

[0014] S21. The copper anode mud deselement residue is fed into a pressure leaching device and a leaching agent is added so that the leaching agent reacts with the silver in the deselement residue and dissolves the silver ions into the leaching solution.

[0015] S22. Leaching parameter control: During the pressurized leaching process, the leaching pressure and temperature are adjusted to accelerate the reaction rate and improve the leaching efficiency, and the reaction time is controlled to increase the silver leaching rate.

[0016] S23. After leaching, the leaching residue and the leaching solution are separated by filtration. The leaching residue contains undissolved solids, while the leaching solution is rich in dissolved silver ions.

[0017] S24. Silver ions are separated from a first-stage leachate by means of ion exchange, electrolysis or precipitation, and the recovered silver is further refined and processed.

[0018] S25. Return the leachate after silver recovery treatment to the pressure leaching equipment for cyclic leaching of silver.

[0019] Preferably, in step S22, the leaching parameters are controlled at pressure of 0.9-1.1 MPa, temperature of 110-150°C, and reaction time of 5-10 hours. The solid-liquid ratio of copper anode mud desulphurization residue to leaching agent is 1:10-14, and the leaching agent is any one of nitric acid, hydrochloric acid, or sulfuric acid.

[0020] Preferably, in step S3, the process of leaching residue sulfidation transformation is as follows:

[0021] S31. Add a sulfiding agent to the first-stage leaching residue produced in the first-stage pressurized leaching silver extraction step. The sulfiding agent reacts with the metal oxides in the first-stage leaching residue to generate sulfides.

[0022] S32. Control of vulcanization transformation parameters: control the amount of vulcanizing agent, reaction temperature, reaction time and reaction pressure;

[0023] S33. After the sulfurization transformation is completed, the sulfurization transformation slag and sulfurization transformation liquid are separated by filtration. The sulfurization transformation slag contains metal sulfides, and the sulfurization transformation liquid contains unreacted sulfurizing agents.

[0024] S34. The sulfurization conversion solution is returned to the first-stage leaching residue for recycling, and the sulfurization conversion of the first-stage leaching residue is continued.

[0025] Preferably, in step S32, the pressure during the sulfurization transformation of the first-stage leaching residue is controlled at 0.9-1.1 MPa, the temperature is controlled at 95-135℃, the reaction time is controlled at 4-8 hours, and the solid-liquid ratio of the first-stage leaching residue to the sulfurizing agent is 1:4-6, and the actual amount of sulfurizing agent used is 1.05-1.2 times the theoretical amount used.

[0026] Preferably, in step S4, the roasting and transformation process of the sulfidation transformation slag is as follows:

[0027] S41. The separated sulfide transformation slag is roasted at a high temperature of 500-900℃. The metal-containing sulfides will be oxidized to generate oxides or sulfides that are easy to dissolve or separate.

[0028] S42. After roasting and transformation, the roasted residue is sent to a first-stage pressure leaching device for pressure leaching treatment to extract silver.

[0029] S43. The roasted leaching residue and the first-stage leaching solution are separated by filtration. The first-stage leaching solution is rich in dissolved silver ions and other metal elements. Silver ions are separated from the first-stage leaching solution by precipitation, electrolysis or ion exchange. The first-stage leaching solution after silver recovery is returned to the pressure leaching equipment for cyclic leaching of silver.

[0030] S44. Use hydrometallurgical or pyrometallurgical methods to process roasting leaching residue and extract copper, lead and zinc elements.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] This invention employs a chlorine-free leaching method to extract silver from deselementized residue. The process involves a first-stage pressurized leaching of silver from the copper anode mud deselementized residue, followed by a second-stage pressurized sulfidation transformation of the leached residue. The sulfidation transformation residue is then roasted and returned to the first-stage pressurized leaching for silver extraction, while the first-stage leaching solution is sent for silver recovery. The roasted leaching residue is then used to extract other valuable elements. This method not only achieves a high silver leaching rate and low impurity content in the resulting crude silver powder, which can be used entirely as raw material for producing first-grade silver ingots, but also overcomes the drawback of conventional silver extraction methods that require the addition of large amounts of chloride ions. Other valuable elements are enriched, selective silver leaching is ensured, and some impurities are suppressed. Because chlorine-free pressurized leaching is used, the corrosion problem of system equipment is effectively solved. Furthermore, the entire process generates no new solid waste or waste liquid, effectively addressing the difficulty of wastewater treatment in current processes and ensuring full utilization of resources. Attached Figure Description

[0033] Figure 1 This is a flowchart of the present invention;

[0034] Figure 2 This is a flowchart of a section of the pressurized leaching silver extraction process of the present invention;

[0035] Figure 3 This is a flowchart of the sulfidation transformation of a leaching residue according to the present invention.

[0036] Figure 4 This is a flowchart illustrating the process of roasting and transforming sulfidation transformation slag according to the present invention. Detailed Implementation

[0037] 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 some embodiments of the present invention, and not all embodiments. 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. Example 1

[0038] Please see Figure 1-4 This invention provides a technical solution: a method for extracting silver from deselementized residue without chlorine and under dual pressure, comprising the following steps:

[0039] S1. Pretreatment of deselenized residue: The deselenized residue is crushed and screened in advance to obtain small particles of deselenized residue with uniform particle size.

[0040] In step S1, a jaw crusher, cone crusher, or impact crusher is used to crush large pieces of material in the deselement slag into particles with a size of 80-100 mesh. After crushing, the granular deselement slag is screened using a vibrating screen, drum screen, or air classifier to ensure uniform particle size.

[0041] S2. Silver is extracted from the deselementized residue of copper anode mud using a single-stage pressure leaching method. After filtration, a first-stage leaching residue and a first-stage leaching solution are obtained. After recovering the silver from the first-stage leaching solution, the first-stage leaching solution is returned to continue the single-stage pressure leaching.

[0042] In step S2, the pressure leaching silver extraction process includes the following steps:

[0043] S21. The copper anode mud deselement residue is fed into a pressure leaching device and a leaching agent is added so that the leaching agent reacts with the silver in the deselement residue and dissolves the silver ions into the leaching solution.

[0044] S22. Leaching parameter control: During the pressurized leaching process, the leaching pressure and temperature are adjusted to accelerate the reaction rate and improve the leaching efficiency, and the reaction time is controlled to increase the silver leaching rate.

[0045] S23. After leaching, the leaching residue and the leaching solution are separated by filtration. The leaching residue contains undissolved solids, while the leaching solution is rich in dissolved silver ions.

[0046] S24. Silver ions are separated from a first-stage leachate by means of ion exchange, electrolysis or precipitation, and the recovered silver is further refined and processed.

[0047] S25. Return the leachate after silver recovery treatment to the pressure leaching equipment for cyclic leaching of silver.

[0048] The pressurized leaching equipment mainly consists of a vessel, heating system, stirring system, and pressure control system, and can perform solvent extraction, leaching, crystallization and other operations under high temperature and high pressure conditions.

[0049] In step S22, the leaching parameters are controlled at pressure of 0.9 MPa, temperature of 110°C, and reaction time of 5 hours. The solid-liquid ratio of copper anode mud deselination residue to leaching agent is 1:10. The leaching agent is any one of nitric acid, hydrochloric acid, or sulfuric acid.

[0050] Nitric acid has strong oxidizing properties and can oxidize and dissolve silver; sulfuric acid has a better leaching effect at higher temperatures.

[0051] S3. The first-stage leaching residue is transformed with a sulfiding agent, and after filtration, sulfidation transformation residue and sulfidation transformation liquid are obtained. The sulfidation transformation liquid is returned to the first-stage leaching residue for further sulfidation transformation.

[0052] In step S3, the process of leaching residue sulfidation transformation is as follows:

[0053] S31. Add a sulfiding agent to the first-stage leaching residue produced in the first-stage pressurized leaching silver extraction step. The sulfiding agent reacts with the metal oxides in the first-stage leaching residue to generate sulfides.

[0054] S32. Control of vulcanization transformation parameters: control the amount of vulcanizing agent, reaction temperature, reaction time and reaction pressure;

[0055] S33. After the sulfurization transformation is completed, the sulfurization transformation slag and sulfurization transformation liquid are separated by filtration. The sulfurization transformation slag contains metal sulfides, and the sulfurization transformation liquid contains unreacted sulfurizing agents.

[0056] S34. The sulfurization conversion solution is returned to the first-stage leaching residue for recycling, and the sulfurization conversion of the first-stage leaching residue is continued.

[0057] In step S32, the pressure during the sulfurization transformation of the first-stage leaching residue is controlled at 0.9 MPa, the temperature is controlled at 95°C, the reaction time is controlled at 4 hours, and the solid-liquid ratio of the first-stage leaching residue to the sulfurizing agent is 1:4. The actual amount of sulfurizing agent used is 1.05 times the theoretical amount used.

[0058] S4. The sulfide conversion slag is converted by roasting. The roasted slag is sent to a first-stage pressure leaching to extract silver. After filtration, roasted leaching slag and a first-stage leachate are obtained. The roasted leaching slag is sent to extract other valuable elements. After recovering the silver from the first-stage leachate, the first-stage leachate is returned to continue the first-stage pressure leaching.

[0059] In step S4, the roasting and transformation process of the sulfidation transformation slag is as follows:

[0060] S41. The separated sulfide transformation slag is roasted at a high temperature of 500℃. The metal-containing sulfides will be oxidized to generate oxides or sulfides that are easy to dissolve or separate.

[0061] S42. After roasting and transformation, the roasted residue is sent to a first-stage pressure leaching device for pressure leaching treatment to extract silver.

[0062] S43. The roasted leaching residue and the first-stage leaching solution are separated by filtration. The first-stage leaching solution is rich in dissolved silver ions and other metal elements. Silver ions are separated from the first-stage leaching solution by precipitation, electrolysis or ion exchange. The first-stage leaching solution after silver recovery is returned to the pressure leaching equipment for cyclic leaching of silver.

[0063] S44. Use hydrometallurgical or pyrometallurgical methods to process roasting leaching residue and extract copper, lead and zinc elements.

[0064] Furthermore, the results of the selenium-depleted residue after a period of pressurized leaching are shown in the table below:

[0065] Table 1: Results of pressure leaching of deselenized residue (%)

[0066]

[0067] Table 2: Results of pressure leaching of roasted residue (%)

[0068]

[0069] Table 3 Overall Leaching Results

[0070]

[0071] Silver was leached from the deselementized residue of copper anode mud using a first-stage pressurized leaching method. The leached residue was then subjected to sulfidation transformation to obtain sulfidation transformation residue. After roasting, the sulfidation transformation residue was returned to the first-stage pressurized leaching method to extract silver. The experiment showed that the overall silver leaching rate was 99.47%, and the resulting crude silver powder had a low impurity content, which can provide high-quality raw materials for the production of first-grade silver ingots. Example 2

[0072] The similarities with Example 1 will not be repeated here; the differences are...

[0073] In step S22, the leaching parameters are controlled at 1 MPa, 130°C, and 7.5 hours. The solid-liquid ratio of the copper anode mud deselination residue to the leaching agent is 1:12. The leaching agent is any one of nitric acid, hydrochloric acid, or sulfuric acid.

[0074] In step S32, the pressure during the sulfurization transformation of the first-stage leaching residue is controlled at 1 MPa, the temperature is controlled at 115°C, the reaction time is controlled at 6 hours, and the solid-liquid ratio of the first-stage leaching residue to the sulfurizing agent is 1:5. The actual amount of sulfurizing agent used is 1.12 times the theoretical amount used.

[0075] S41. The separated sulfide transformation slag is roasted at a high temperature of 700℃. The metal-containing sulfides will be oxidized to generate oxides or sulfides that are easy to dissolve or separate.

[0076] Furthermore, the results of the selenium-depleted residue after a period of pressurized leaching are shown in the table below:

[0077] Table 4: Results of pressure leaching of deselenized residue (%)

[0078]

[0079] Table 5: Results of pressure leaching of roasted residue (%)

[0080]

[0081] Table 6: Overall Leaching Results

[0082]

[0083] Silver was leached from the deselementized residue of copper anode mud using a first-stage pressurized leaching method. The leached residue was then subjected to sulfidation transformation to obtain sulfidation transformation residue. After roasting, the sulfidation transformation residue was returned to the first-stage pressurized leaching method to extract silver. The experiment showed that the overall silver leaching rate was 99.74%, and the resulting crude silver powder had a low impurity content, which can provide high-quality raw materials for the production of first-grade silver ingots. Example 3

[0084] The similarities with Examples 1 and 2 will not be repeated here; the differences are...

[0085] In step S22, the leaching parameters are controlled at pressure of 1.1 MPa, temperature of 150°C, and reaction time of 10 hours. The solid-liquid ratio of copper anode mud deselination residue to leaching agent is 1:14. The leaching agent is any one of nitric acid, hydrochloric acid, or sulfuric acid.

[0086] In step S32, the pressure during the sulfurization transformation of the first-stage leaching residue is controlled at 1.1 MPa, the temperature is controlled at 135°C, the reaction time is controlled at 8 hours, and the solid-liquid ratio of the first-stage leaching residue to the sulfurizing agent is 1:6. The actual amount of sulfurizing agent used is 1.2 times the theoretical amount used.

[0087] S41. The separated sulfide transformation slag is roasted at a high temperature of 900℃. The metal-containing sulfides will be oxidized to generate oxides or sulfides that are easy to dissolve or separate.

[0088] Furthermore, the results of the selenium-depleted residue after a period of pressurized leaching are shown in the table below:

[0089] Table 7: Results of pressure leaching of deselenized residue in stage 1 (%)

[0090]

[0091] Table 8: Results of pressure leaching of roasted residue (%)

[0092]

[0093] Table 9: Overall Leaching Results

[0094]

[0095] Silver was leached from the deselementized residue of copper anode mud using a first-stage pressurized leaching method. The leached residue was then subjected to sulfidation transformation to obtain sulfidation transformation residue. After roasting, the sulfidation transformation residue was returned to the first-stage pressurized leaching method to extract silver. The experiment showed that the overall silver leaching rate was 99.58%, and the resulting crude silver powder had a low impurity content, which can provide high-quality raw materials for the production of first-grade silver ingots.

[0096] In summary, the optimal leaching parameters for silver in copper anode mud deselement residue using a single-stage pressurized leaching method are: solid-liquid ratio 1:12, pressure 1.0 MPa, temperature 130℃, and reaction time 8 hours. After filtration, a first-stage leaching residue and a first-stage leaching solution (soluble silver solution such as silver sulfate) are obtained. The silver in the first-stage leaching solution is recovered and returned to continue leaching.

[0097] Based on the obtained leaching residue, a sulfurizing agent was used for transformation. The optimal transformation parameters were: solid-liquid ratio 1:5, sulfurizing agent dosage 1.1 times the theoretical amount, pressure 1.0 MPa, reaction temperature 110℃, and reaction time 6 hours. After filtration, sulfurized transformation residue and sulfurized transformation liquid were obtained. The sulfurized transformation liquid was returned to the first leaching residue for further sulfurized transformation.

[0098] Based on the obtained sulfidation transformation slag, roasting transformation is adopted, with the optimal parameters being a temperature of 700℃. The roasted slag is then sent to a first-stage pressure leaching process to extract silver. After filtration, roasted leaching slag and a first-stage leachate are obtained. The roasted leaching slag is sent for the extraction of other valuable elements, while the first-stage leachate is returned to continue leaching after silver recovery.

[0099] This method yields the most silver from the deselenized residue of copper anode mud, meaning it has the highest silver leaching rate.

[0100] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for chlorine-free dual-pressure extraction of silver from deselenized residue, characterized in that: Includes the following steps: S1. Pretreatment of deselenized residue: The deselenized residue is crushed and screened in advance to obtain small particles of deselenized residue with uniform particle size. Jaw crushers, cone crushers, or impact crushers are used to crush large pieces of deselenized residue into granular materials with a particle size of 80-100 mesh. After crushing, vibrating screens, drum screens, or air classifiers are used to screen the granular deselenized residue to ensure uniform particle size. S2. Silver is extracted from the deselementized residue of copper anode mud using a single-stage pressure leaching method. After filtration, a first-stage leaching residue and a first-stage leaching solution are obtained. After recovering the silver from the first-stage leaching solution, the first-stage leaching solution is returned to continue the single-stage pressure leaching. The leaching parameters are controlled at pressure of 0.9-1.1 MPa, temperature of 110-150℃, and reaction time of 5-10 hours. The solid-liquid ratio of copper anode mud deselination residue to leaching agent is 1:10-14. The leaching agent can be any one of nitric acid, hydrochloric acid, or sulfuric acid. S3. The first-stage leaching residue is transformed with a sulfiding agent, and after filtration, sulfidation transformation residue and sulfidation transformation liquid are obtained. The sulfidation transformation liquid is returned to the first-stage leaching residue for further sulfidation transformation. The pressure during the sulfidation transformation of the first-stage leaching residue is controlled at 0.9-1.1 MPa, the temperature at 95-135℃, and the reaction time at 4-8 hours. The solid-liquid ratio of the first-stage leaching residue to the sulfiding agent is 1:4-6, and the actual amount of sulfiding agent used is 1.05-1.2 times the theoretical amount. S4. The sulfide conversion slag is converted by roasting. The roasted slag is sent to a first-stage pressure leaching to extract silver. After filtration, roasted leaching slag and a first-stage leachate are obtained. The roasted leaching slag is sent to extract other valuable elements. After recovering the silver from the first-stage leachate, the first-stage leachate is returned to continue the first-stage pressure leaching.

2. The method for extracting silver from deselenized residue without chlorine under dual pressure according to claim 1, characterized in that: In step S2, the pressure leaching silver extraction process includes the following steps: S21. The copper anode mud deselement residue is fed into a pressure leaching device and a leaching agent is added so that the leaching agent reacts with the silver in the deselement residue and dissolves the silver ions into the leaching solution. S22. Leaching parameter control: During the pressurized leaching process, the leaching pressure and temperature are adjusted to accelerate the reaction rate and improve the leaching efficiency, and the reaction time is controlled to increase the silver leaching rate. S23. After leaching, the leaching residue and the leaching solution are separated by filtration. The leaching residue contains undissolved solids, while the leaching solution is rich in dissolved silver ions. S24. Silver ions are separated from a first-stage leachate by means of ion exchange, electrolysis or precipitation, and the recovered silver is further refined and processed. S25. Return the leachate after silver recovery treatment to the pressure leaching equipment for cyclic leaching of silver.

3. The method for extracting silver from deselenized residue without chlorine under dual pressure according to claim 1, characterized in that: In step S3, the process of leaching residue sulfidation transformation is as follows: S31. Add a sulfiding agent to the first-stage leaching residue produced in the first-stage pressurized leaching silver extraction step. The sulfiding agent reacts with the metal oxides in the first-stage leaching residue to generate sulfides. S32. Control of vulcanization transformation parameters: control the amount of vulcanizing agent, reaction temperature, reaction time and reaction pressure; S33. After the sulfurization transformation is completed, the sulfurization transformation slag and sulfurization transformation liquid are separated by filtration. The sulfurization transformation slag contains metal sulfides, and the sulfurization transformation liquid contains unreacted sulfurizing agents. S34. The sulfurization conversion solution is returned to the first-stage leaching residue for recycling, and the sulfurization conversion of the first-stage leaching residue is continued.

4. The method for extracting silver from deselenized residue without chlorine under dual pressure according to claim 1, characterized in that: In step S4, the roasting and transformation process of the sulfidation transformation slag is as follows: S41. The separated sulfide transformation slag is roasted at a high temperature of 500-900℃. The metal-containing sulfides will be oxidized to generate oxides or sulfides that are easy to dissolve or separate. S42. After roasting and transformation, the roasted residue is sent to a first-stage pressure leaching device for pressure leaching treatment to extract silver. S43. The roasted leaching residue and the first-stage leaching solution are separated by filtration. The first-stage leaching solution is rich in dissolved silver ions and other metal elements. Silver ions are separated from the first-stage leaching solution by precipitation, electrolysis or ion exchange. The first-stage leaching solution after silver recovery is returned to the pressure leaching equipment for cyclic leaching of silver. S44. Use hydrometallurgical or pyrometallurgical methods to process roasting leaching residue and extract copper, lead and zinc elements.

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