A method for preparing crude silver from lead anode mud

Abstract

The invention relates to a method for preparing crude silver from lead anode mud, and belongs to the metallurgical technical field of combining wet process and pyrometallurgy. The invention comprises the following steps: arsenic is eluted by oxidation alkali from lead anode mud, arsenic is precipitated by lime from high arsenic wastewater; arsenic-removed anode mud is slurried with slag-making agent and reducing agent, and granulated and dried after liquid-solid separation; the dried material is reduced and smelted by medium frequency furnace; precious lead is impurity-removed by air top blowing in medium frequency furnace, arsenic is eluted by alkali from blowing smoke, and high arsenic solution is incorporated into high arsenic leaching liquid of lead anode mud for arsenic precipitation by lime; copper-bismuth-silver alloy is oxidized and refined, and after the refined slag is melted and allowed to stand for phase separation, the metal phase is returned to oxidation refining, the slag is acid-leached, copper is recovered by leaching liquid, gold and silver are wet-leached by leaching slag, gold and silver are recovered by wet leaching liquid, and bismuth is recovered by leaching slag. The invention solves the problems that arsenic is too dispersed in lead anode mud in pyrometallurgical smelting process and difficult to be handled, phase separation is not thorough in reduction smelting, and slag is entrained with a lot of slag, reaction time is too long in blowing and oxidative refining process, and energy consumption is high.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy combining hydrometallurgy and pyrometallurgy, and specifically relates to a method for preparing crude silver from lead anode mud. Background Art

[0002] Lead anode mud is the anode mud produced by the electrolytic refining of crude lead. It has high Au and Ag contents and is of high value. Their contents directly affect the benefits of lead smelting enterprises. In addition to Au and Ag, there are also valuable elements such as Sb, Pb, Cu, and Bi, which have very important comprehensive recycling and utilization value. The As content in the anode mud is also very high. It is introduced from the lead smelting raw materials and enters the anode mud during the electrolysis of crude lead. It is one of the difficult technologies in the lead anode mud recovery process. On the one hand, it affects the occupational health and safety of enterprise employees, and on the other hand, it affects the quality of the product. There are two commonly used methods for recovering lead anode mud: hydrometallurgical recovery and pyrometallurgical recovery. Patent CN101831551A introduces a hydrometallurgical process for comprehensive recovery of valuable elements in lead anode mud. The direction of arsenic is not fully explained, and the precious metals pass through many process units. The recovery rate is difficult to guarantee and the process control is not necessarily accurate. Among the many methods for recycling lead anode mud, the traditional pyrometallurgical process is optimized to achieve comprehensive recovery of valuable elements. However, high concentrations of arsenic exist in various intermediate materials, waste slag and products in the whole process, which affects the operating environment and the metal liquid level is achieved by gas stirring or furnace rotation. The full contact of additives results in incomplete metal phase separation during the smelting process, a large amount of smelting slag is entrained, and the reaction interface is updated slowly during blowing and impurity removal, requiring extended processing time to meet the requirements of intermediate products. There are also many studies on the use of vacuum separation of precious lead in pyrometallurgical processes. Vacuum separation of precious lead has low environmental pollution, small slag production, short process flow, high direct metal recovery rate, and improved operating environment. However, the initial investment in vacuum separation equipment is large and the operating cost is high. Multi-stage distillation is required to achieve the separation and recovery of multiple metals. Direct application and promotion to the recovery of valuable metal elements in lead anode mud needs further improvement and development. Summary of the invention

[0003] In order to overcome the problems existing in the background technology, the present invention provides a method for preparing crude silver from lead anode mud, which solves the problems of arsenic being too dispersed in lead anode mud and difficult to handle in the pyrometallurgical smelting process, incomplete phase separation during reduction smelting resulting in a large amount of slag entrainment, and long reaction time and high energy consumption during blowing and oxidation refining.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] The method for preparing crude silver from lead anode mud comprises the following steps:

[0006] (1) The lead anode mud is subjected to alkali oxidation or alkali oxygen pressure to obtain high arsenic solution and arsenic-free lead anode mud.

[0007] (2) The high-arsenic solution produced in step (1) is treated with lime to precipitate arsenic, the arsenic slag is solidified and stored, and the liquid after arsenic precipitation is returned to the anode mud for oxidation and alkali elution of arsenic; this process is used to treat the high-arsenic solution in order to achieve internal circulation of the high-arsenic solution and the arsenic precipitation solution to avoid discharge of wastewater.

[0008] (3) The arsenic-free lead anode mud produced in step (1) is slurried with a slag-forming agent and a reducing agent, and then granulated and dried after liquid-solid separation.

[0009] (4) The granulated and dried material in step (3) is subjected to reduction smelting in a medium frequency furnace to obtain reduction smelting fumes, lead slag, and precious lead; the reduction smelting fumes and lead slag are returned to the lead smelting system to recover the valuable metals.

[0010] (5) The precious lead produced in step (4) is subjected to top-blowing of air in a medium frequency furnace to remove impurities to obtain blowing dust, blowing slag, and copper-bismuth-silver alloy; the blowing dust is subjected to alkaline elution to remove arsenic; the high-arsenic solution is returned to the lead anode mud oxidation alkaline washing solution for lime precipitation of arsenic; the arsenic-removed dust and blowing slag are used to smelt lead-antimony alloy.

[0011] (6) The copper-bismuth-silver alloy produced in step (5) is subjected to oxidative refining to obtain refining dust, refining slag, and crude silver; the refining dust is returned to the dearsenicized anode mud for reduction smelting; the refining slag is melted and allowed to stand for phase separation; and the metal phase is returned for oxidative refining.

[0012] (7) melting the refined slag in step (6), standing and phase-separating the resulting slag, leaching it with sulfuric acid, recovering copper from the leaching solution, wet-leaching gold and silver from the leached slag and recovering gold and silver from the solution, and smelting the slag to recover bismuth.

[0013] Furthermore, in the step (1), the arsenic is eluted by oxidative alkali or oxygen pressure alkali in the lead anode mud, and H2O2, NaClO or oxygen, ozone and a combination thereof can be added under normal pressure. Preferably, the arsenic is eluted by oxygen pressure alkali. This method is selected because As in the lead anode mud mainly exists in a single substance form, oxygen and hydrogen peroxide are difficult to oxidize and leach arsenic under normal pressure, ozone oxidation has a high cost, and NaClO oxidation leaching will cause the loss of valuable metal elements in the anode mud.

[0014] Furthermore, in step (1), the alkali used for eluting arsenic with oxidation alkali or eluting arsenic with oxygen pressure alkali is NaOH, KOH or a mixture of them and their carbonates. Preferably, NaOH and sodium carbonate are used, which have relatively low cost.

[0015] Furthermore, the slag-forming agent in step (3) is lime or fluorite, the amount of which is 0%-3% of the dry basis dearsenicized anode mud, the slurrying liquid is sodium carbonate solution, the amount of sodium carbonate added is 1%-5% of the dry basis dearsenicized anode mud, and the reducing agent is coke powder or coal powder, the amount of which is 2%-8%.

[0016] Furthermore, the granulation in step (3) can be performed by extrusion granulation or disc granulation, and the drying method can be rotary kiln drying or natural drying to meet the moisture requirements of the furnace.

[0017] Furthermore, in the step (4), the reduction smelting temperature in the medium frequency furnace is 900°C-1100°C, and the smelting time is 2h-6h.

[0018] Furthermore, in the step (5), the precious lead is blown with air from a medium frequency furnace to remove arsenic, antimony and lead. The blowing temperature is 900-1100°C, the pressure is 0.2-0.6MPa, the air blowing pipe is 8-15cm away from the metal liquid surface, the blowing time is 2-8h, and samples are taken at intervals of 2h during the process to monitor the removal of impurity elements.

[0019] Furthermore, in step (6), the copper-bismuth-silver alloy is subjected to oxidation refining at a temperature of 1000-1200°C, and the oxidant can be nitrate or oxygen. The preferred oxidant is oxygen, and the method is bottom blowing, the pressure is 0.2-0.5 MPa, the bottom blowing refining time is 2-6 hours, and the content of Cu, Bi, Au, and Ag is monitored by sampling at intervals of 1 hour during the process.

[0020] The technical scheme of the present invention is mainly based on the following principles: when the lead anode mud is leached in oxygen pressure alkali, arsenic is oxidized by elemental arsenic and then combined with sodium to form sodium arsenate, lead, copper, bismuth, gold and silver will not be leached, a small amount of antimony will react with NaOH, but will remain in the slag due to the presence of sodium carbonate; the medium frequency furnace has high thermal efficiency, fast heating speed, less metal element burnout, wide smelting material, less environmental pollution, can accurately control the temperature of the molten metal, and directly heat the material core surface with extremely small temperature difference by electromagnetic induction, and the molten metal produces a strong stirring effect under the action of electromagnetic force; when the arsenic-free lead anode mud is reduced and smelted in the medium frequency furnace, the heating speed is fast, the metal oxidation is small, the amount of reducing agent can be appropriately reduced, and the electromagnetic stirring condition is conducive to the separation of the reduced metal and the slag, and the amount of metal entrained in the slag is reduced; when the precious lead is blown or oxidized and refined, the heating speed is fast, the energy consumption is reduced, and the electromagnetic stirring effect can quickly update the reaction interface to accelerate the reaction, which can shorten the blowing and oxidation refining time.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention has the advantages of high metal recovery rate, centralized disposal of arsenic-containing smoke, environmental friendliness, low energy consumption, etc. Arsenic is removed by oxidizing lead anode mud with alkali and precipitating arsenic with lime to achieve deep separation of arsenic from main metals such as Pb, Ag, Au, Cu, Sb, etc., avoiding the high impurity content of each product and occupational health problems caused by the dispersion of arsenic in various metal products or intermediate materials; at the same time, the lead anode mud after arsenic removal is treated with high efficiency and enhanced stirring by a medium frequency furnace to directly produce crude silver, and air blowing and oxygen refining processes are carried out simultaneously in the medium frequency furnace, avoiding the problem of high energy consumption caused by the separation of air blowing and oxygen refining and the need for secondary melting of materials in the traditional process of preparing crude silver from lead anode mud.

[0023] 2. The arsenic is removed by oxidizing lead anode mud with alkaline elution in the present invention, so as to avoid excessive dispersion of high-content arsenic in the whole valuable metal recovery system during the traditional pyrometallurgical treatment of lead anode mud, which is not conducive to the low-cost and efficient removal of harmful arsenic and the occupational health of employees.

[0024] 3. The arsenic-free lead anode mud of the present invention is directly slurried with sodium carbonate aqueous solution and stirred and mixed with slag-making and reducing agents. After liquid-solid separation, the mixture can be disc granulated or extruded granulated, avoiding the uneven mixing of traditional dry mixing, which is beneficial to improving the efficiency of metal smelting reduction and shortening the smelting time.

[0025] 4. The present invention adopts a medium frequency furnace to carry out reduction smelting of dearsenicized lead anode mud, and utilizes the benefits of electromagnetic stirring, which is beneficial to improving the efficiency of reduction smelting and promoting the separation of metal phase and slag phase, and reducing metal loss caused by the entrainment of metal phase in smelting slag.

[0026] 5. The present invention uses air blowing dust to alkalinely elute arsenic, and uses high-arsenic solution and lead anode mud to dearsenify the leaching solution to precipitate arsenic; the dearsenicated dust and air blowing slag are used as raw materials for preparing lead-antimony alloy, reducing the metal loss caused by the separate recovery of antimony and lead.

[0027] 6. The present invention can realize the recovery of Au, Ag, Cu and Bi in the slag by centralized treatment of oxidative refining slag, and combines lime precipitation of arsenic in high-arsenic leaching solution, arsenic removal from blowing dust and air blowing of slag to prepare lead-antimony alloy, and the crude silver produced by oxidative refining, wet recovery of copper, gold and silver, and recovery of bismuth from leaching slag to achieve effective removal of harmful impurities in lead anode mud and comprehensive recovery of valuable elements.

[0028] 7. The present invention removes arsenic from lead anode mud by pressurized oxidation alkaline leaching, produces dearsenicized anode mud, and stirs and mixes it with sodium carbonate and coal powder, and directly carries out reduction smelting in a medium frequency furnace after drying to produce low-arsenic precious lead. The precious lead air blowing and oxidation refining experiments are carried out on this raw material to produce crude silver containing 95.03% Ag and 661.68g / t Au. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0030] The method for preparing crude silver from lead anode mud comprises the following steps:

[0031] (1) Eliminating arsenic from lead anode mud by oxygen-pressure alkali elution to obtain high arsenic solution and de-arsenicized lead anode mud. Eliminating arsenic from lead anode mud by oxygen-pressure alkali elution can be carried out by adding H2O2, NaClO or introducing oxygen, ozone and their combination under normal pressure. Eliminating arsenic by oxygen-pressure alkali elution is because As in lead anode mud mainly exists in the form of a single substance. Under normal pressure, it is difficult to oxidize and leach arsenic with oxygen and hydrogen peroxide. The cost of ozone oxidation is relatively high. NaClO oxidation leaching will cause the loss of valuable metal elements in the anode mud. The alkali used in oxygen-pressure alkali elution of arsenic is NaOH and sodium carbonate, which are relatively low in cost.

[0032] (2) The high-arsenic solution produced in step (1) is treated with lime to precipitate arsenic, the arsenic slag is solidified and stored, and the liquid after arsenic precipitation is returned to the anode mud for oxidation and alkali elution of arsenic; this process is used to treat the high-arsenic solution in order to achieve internal circulation of the high-arsenic solution and the arsenic precipitation solution to avoid discharge of wastewater.

[0033] (3) The dearsenicated lead anode mud produced in step (1) is mixed with a slag-making agent and a reducing agent, and then granulated and dried after liquid-solid separation. The slag-making agent is lime or fluorite, and the amount of the added amount is 0%-3% of the dry dearsenicated anode mud. The slurry liquid is sodium carbonate solution, and the amount of sodium carbonate added is 1%-5% of the dry dearsenicated anode mud. The reducing agent is coke powder or coal powder, and the amount of the added amount is 2%-8%. Granulation can be carried out by extrusion granulation or disc granulation, and the drying method can be rotary kiln drying or natural drying to meet the moisture requirements of the furnace.

[0034] (4) The granulated and dried material in step (3) is subjected to reduction smelting in a medium frequency furnace at a reduction smelting temperature of 900°C to 1100°C for a smelting time of 2h to 6h. Reduction smelting fumes, lead slag, and precious lead are obtained, and the reduction smelting fumes and lead slag are returned to the lead smelting system to recover valuable metals.

[0035] (5) The precious lead produced in step (4) is subjected to top blowing of air in a medium frequency furnace to remove arsenic, antimony and lead, the blowing temperature is 900-1100°C, the pressure is 0.2-0.6MPa, the air blowing pipe is 8-15cm away from the metal liquid surface, the blowing time is 2-8h, and sampling is performed every 2h during the process to monitor the removal of impurity elements. Blowing dust, blowing slag and copper-bismuth-silver alloy are obtained, and arsenic is removed from the blowing dust by alkali washing. The high arsenic solution is returned to the lead anode mud oxidation alkali washing solution for lime precipitation of arsenic, and the arsenic-removed dust and blowing slag are used to smelt lead-antimony alloy.

[0036] (6) The copper-bismuth-silver alloy produced in step (5) is subjected to oxidation refining at a temperature of 1000-1200°C. The oxidant can be nitrate or oxygen. The preferred oxidant is oxygen. The method is bottom blowing at a pressure of 0.2-0.5 MPa. The bottom blowing refining time is 2-6 hours. During the process, samples are taken every 1 hour to monitor the content of Cu, Bi, Au, and Ag. Refining dust, refining slag, and crude silver are obtained. The refining dust is returned to the dearsenicized anode mud for reduction smelting. The refining slag is melted and allowed to stand for phase separation. The metal phase is returned for oxidation refining.

[0037] (7) melting the refined slag in step (6), standing and phase-separating the resulting slag, leaching it with sulfuric acid, recovering copper from the leaching solution, wet-leaching gold and silver from the leached slag and recovering gold and silver from the solution, and smelting the slag to recover bismuth.

[0038] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by technicians.

[0039] Example 1

[0040] (1) Eliminating arsenic from lead anode mud by oxygen-pressure alkali elution to obtain high-arsenic solution and de-arsenicized lead anode mud. Eliminating arsenic from lead anode mud by oxidation alkali elution or oxygen-pressure alkali elution.

[0041] (2) The high-arsenic solution produced in step (1) is precipitated with lime, the arsenic slag is solidified and stored, and the solution after arsenic precipitation is returned to the anode mud for oxidation and alkali elution of arsenic.

[0042] (3) The dearsenicated lead anode mud produced in step (1) is mixed with 1% lime, 5% coal powder and 3% sodium carbonate to form a slurry, filtered, granulated and dried. The components of the lead anode mud and the dearsenicated anode mud are shown in Table 1.

[0043] Table 1 Composition of lead anode mud and dearsenicized anode mud

[0044]

[0045] (4) The material obtained in step (3) is reduced and smelted in a medium frequency furnace, the medium frequency furnace is heated to 900°C, and the heat preservation and smelting time is 3 hours. The scum on the surface is scraped off with an iron spoon with a wooden handle, and the metal phase is transferred into the mold. After cooling, the slag phase on the surface is further separated. The reduced smelting smoke, lead slag, and precious lead are obtained. The reduced smelting smoke and lead slag are returned to the lead smelting system to recover valuable metals. The precious lead composition is shown in Table 2.

[0046] Table 2 Precious lead composition

[0047]

[0048] (5) The precious lead produced in step (4) is blown and impurized in a clay graphite crucible, and the temperature is raised to 930° C. An air compressor is used to provide high-pressure air, and the gas enters the gas flow meter after water vapor separation and is quantitatively introduced into the metal liquid surface. The blowing pipe is a silicon carbide pipe with a height of 10 cm from the metal liquid surface, and the air flow rate is 5m 3 / h, pressure 0.2-0.6MPa, blowing time 7h, sampling every 2h to monitor the removal of impurity elements. The blowing dust, blowing slag, copper-bismuth-silver alloy were obtained, the blowing dust was alkali-eluted to remove arsenic, the high arsenic solution was returned to the lead anode mud oxidation alkali washing solution for lime precipitation of arsenic, and the arsenic-removed dust and blowing slag were used to smelt lead-antimony alloy. The composition of blowing dust, blowing slag and metal phase at different times is shown in Table 3.

[0049] Table 3 Composition of blowing dust, blowing slag and metal phase at different times

[0050]

[0051] (6) The copper-bismuth-silver alloy produced in step (5) is subjected to oxidation refining to remove copper and bismuth, and is refined by oxygen in a silicon carbide crucible, and the temperature is raised to 1085°C. The silicon carbide tube is preheated and inserted into the middle of the molten metal and fixed. The oxygen enters the gas flow meter after water vapor separation, and the oxygen flow is adjusted to 300L / h, the pressure is 0.2-0.5MPa, and the refining time is 5h. During the process, samples are taken every 1h to monitor the content of Cu, Bi, Au, and Ag. Refining dust, refining slag, and crude silver are obtained. The refining dust is returned to the dearsenicized anode mud for reduction smelting, the refining slag is melted and allowed to stand for phase separation, and the metal phase is returned for oxidation refining. The composition of the refining slag, crude silver, and metal phase at different times is shown in Table 4.

[0052] Table 4 Composition of refined slag, crude silver and metal phase at different times

[0053]

[0054] (7) The refined slag obtained in step (6) is melted and allowed to stand for phase separation, the produced slag is leached with sulfuric acid, copper is recovered from the leaching solution, gold and silver are leached by wet method from the leached slag and gold and silver are recovered from the solution, and bismuth is recovered by smelting the slag.

[0055] Example 2

[0056] (1) Eliminating arsenic from lead anode mud by oxygen-pressure alkali elution to obtain high-arsenic solution and de-arsenicized lead anode mud. Eliminating arsenic from lead anode mud by oxidation alkali elution or oxygen-pressure alkali elution.

[0057] (2) The high-arsenic solution produced in step (1) is precipitated with lime, the arsenic slag is solidified and stored, and the solution after arsenic precipitation is returned to the anode mud for oxidation and alkali elution of arsenic.

[0058] (3) The arsenic-free lead anode mud produced in step (1) is mixed with 0% lime, 3% coal powder and 5% sodium carbonate to form a slurry, filtered, granulated and dried.

[0059] (4) The material obtained in step (3) is reduced and smelted in a medium frequency furnace, the medium frequency furnace is heated to 1100°C, and the heat preservation and smelting time is 5 hours. The scum on the surface is scraped off with an iron spoon with a wooden handle, and the metal phase is transferred into the mold. After cooling, the slag phase on the surface is further separated. The reduced smelting smoke, lead slag, and precious lead are obtained. The reduced smelting smoke and lead slag are returned to the lead smelting system to recover valuable metals. The precious lead composition is shown in Table 5.

[0060] Table 5 Noble lead composition

[0061]

[0062] (5) The precious lead produced in step (4) is blown and impurized in a clay graphite crucible, and the temperature is raised to 922° C. An air compressor is used to provide high-pressure air, and the gas enters a gas flow meter after water vapor separation and is quantitatively introduced into the metal liquid surface. The blowing pipe is a silicon carbide pipe with a height of 10 cm from the metal liquid surface, and the air flow rate is 6m 3 / h, pressure 0.2-0.6MPa, blowing time 8h, sampling every 2h to monitor the removal of impurity elements. The blowing dust, blowing slag, copper-bismuth-silver alloy were obtained, the blowing dust was alkali-eluted to remove arsenic, the high arsenic solution was returned to the lead anode mud oxidation alkali washing solution for lime precipitation of arsenic, and the arsenic-removed dust and blowing slag were used to smelt lead-antimony alloy. The composition of blowing dust, blowing slag and metal phase at different times is shown in Table 6.

[0063] Table 6 Composition of blowing dust, blowing slag and metal phase at different times

[0064]

[0065] (6) The copper-bismuth-silver alloy produced in step (5) is subjected to oxidation refining to remove copper and bismuth, and is refined by oxygen in a silicon carbide crucible, and the temperature is raised to 1075°C. The silicon carbide tube is preheated and inserted into the middle of the molten metal and fixed. The oxygen enters the gas flow meter after water vapor separation, and the oxygen flow is adjusted to 450L / h, the pressure is 0.2-0.5MPa, and the refining time is 4h. During the process, samples are taken every 1h to monitor the content of Cu, Bi, Au, and Ag. Refining dust, refining slag, and crude silver are obtained. The refining dust is returned to the dearsenicized anode mud for reduction smelting, the refining slag is melted and allowed to stand for phase separation, and the metal phase is returned for oxidation refining. The composition of the refining slag, crude silver, and metal phase at different times is shown in Table 7.

[0066] Table 7 Composition of refined slag, crude silver and metal phase at different times

[0067]

[0068] (7) The refined slag obtained in step (6) is melted and allowed to stand for phase separation, the produced slag is leached with sulfuric acid, copper is recovered from the leaching solution, gold and silver are leached by wet method from the leached slag and gold and silver are recovered from the solution, and bismuth is recovered by smelting the slag.

[0069] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing crude silver from lead anode mud, characterized in that: The specific steps include: (1) Eliminating arsenic from lead anode mud by oxidizing alkali or eluting arsenic with oxygen-pressure alkali to obtain high-arsenic solution and arsenic-free lead anode mud; (2) using lime to precipitate arsenic in the high-arsenic solution produced in step (1), solidifying the arsenic slag and storing it in a pile, and returning the arsenic-precipitated solution to the anode mud for alkali oxidation to remove the arsenic; (3) slurrying the dearsenicized lead anode mud produced in step (1) with a slag-making agent and a reducing agent, and granulating and drying the mixture after liquid-solid separation; (4) reducing and smelting the granulated and dried material in step (3) in a medium frequency furnace to obtain reduced smelting dust, lead slag, and precious lead, and returning the reduced smelting dust and lead slag to the lead smelting system; (5) removing impurities from the precious lead produced in step (4) by top blowing air in a medium frequency furnace to obtain blowing dust, blowing slag, and copper-bismuth-silver alloy; removing arsenic from the blowing dust by alkali elution; and adding the high-arsenic solution to the lead anode mud oxidation alkali washing solution for lime precipitation of arsenic; and using the arsenic-removed dust and blowing slag to smelt lead-antimony alloy; (6) subjecting the copper-bismuth-silver alloy produced in step (5) to oxidative refining to obtain refining dust, refining slag, and crude silver, wherein the refining dust is returned to the dearsenicized anode mud for reduction smelting, the refining slag is melted and allowed to stand for phase separation, and the metal phase is returned for oxidative refining; (7) The refined slag in step (6) is melted, allowed to stand and phase separated, and the slag produced is leached with sulfuric acid, copper is recovered from the leaching solution, gold and silver are leached by wet method from the leached slag and gold and silver are recovered from the solution, and bismuth is recovered by smelting the slag.

2. The method for preparing crude silver from lead anode mud according to claim 1, characterized in that: In the step (1), the arsenic is eluted by oxidative alkali elution of lead anode mud or eluted by oxygen-pressure alkali elution, which can be carried out by adding H2O2, NaClO or introducing oxygen, ozone or a combination thereof under normal pressure.

3. The method for preparing crude silver from lead anode mud according to claim 1, characterized in that: In the step (1), the base used for arsenic elution by oxidation alkali or arsenic elution by oxygen pressure alkali is NaOH, KOH or a mixture of NaOH and their carbonates.

4. The method for preparing crude silver from lead anode mud according to claim 1, characterized in that: The slagging agent in step (3) is lime or fluorite, the amount of which is 0%-3% of the dry basis dearsenicized anode mud; the slurrying liquid is sodium carbonate solution, the amount of which is 1%-5% of the dry basis dearsenicized anode mud; the reducing agent is coke powder or coal powder, the amount of which is 2%-8%.

5. The method for preparing crude silver from lead anode mud according to claim 1, characterized in that: The granulation in step (3) can be performed by extrusion granulation or disc granulation, and the drying method can be rotary kiln drying or natural drying.

6. The method for preparing crude silver from lead anode mud according to claim 1, characterized in that: In the step (4), the reduction smelting temperature of the medium frequency furnace is 900°C-1100°C, and the smelting time is 2h-6h.

7. The method for preparing crude silver from lead anode mud according to claim 1, characterized in that: In the step (5), the precious lead is blown with air from a medium frequency furnace to remove arsenic, antimony and lead. The blowing temperature is 900-1100°C, the pressure is 0.2-0.6 MPa, the air blowing pipe is 8-15 cm away from the metal liquid surface, the blowing time is 2-8 hours, and samples are taken at intervals of 2 hours during the process to monitor the removal of impurity elements.

8. The method for preparing crude silver from lead anode mud according to claim 1, characterized in that: In the step (6), the copper-bismuth-silver alloy is subjected to oxidation refining at a temperature of 1000-1200° C., and the oxidant may be nitrate or oxygen.

Images