A method for removing antimony by bismuth blowing in lead-antimony alloys

Abstract

This invention discloses a method for removing antimony from lead-antimony alloys by adding bismuth during smelting. The method includes the following process steps: S1: reduction smelting of lead anode mud; S2: initial soot blowing of the smelted mixture; S3: vacuum distillation of the soot blowing mixture; S4: electrolytic removal of lead from the distilled mixture; S5: secondary blowing of the soot blowing mixture; S6: recycling of the secondary soot blowing mixture. This invention, without altering the existing production facilities, changes the alloy composition in the furnace by adding bismuth materials (high-bismuth alloy or high-bismuth wet sludge) during the lead-antimony alloy soot blowing process. This allows the antimony metal content in the furnace alloy to be reduced to below 18% while still maintaining a good oxidation and volatilization rate. Furthermore, by adjusting the bismuth metal content in the furnace alloy, the soot blowing effect can be significantly improved.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal smelting equipment technology, and in particular to a method for removing antimony by adding bismuth during the smelting of lead-antimony alloys. Background Technology

[0002] In the lead smelting process, the electrolytic refining of crude lead produces lead anode mud, which typically contains various metals such as antimony, lead, bismuth, silver, and gold. These metals require comprehensive recycling. Most manufacturers use conventional pyrometallurgical processes for recycling these metals. The typical process involves first feeding the lead anode mud into a smelting furnace for reduction smelting. After slag removal, a lead-antimony alloy is obtained, which is then subjected to soot blowing to remove antimony. During soot blowing, most of the antimony metal is oxidized and volatilized into the flue gas. This antimony-containing flue gas is further purified before being used to produce antimony white or antimony ingots.

[0003] However, according to feedback from most manufacturers' production experience, during the soot blowing process for antimony removal in lead-antimony alloys, as antimony metal continues to oxidize and volatilize, when the antimony metal content in the alloy in the furnace drops below 18%, the oxidation and volatilization rate of antimony metal becomes extremely slow, and the soot blowing effect becomes significantly poor. At this point, continuing soot blowing to remove antimony will inevitably lead to a substantial increase in production costs. Therefore, most manufacturers have to stop soot blowing at this time, allowing the approximately 18% antimony metal to circulate and accumulate in the production system, affecting production. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of conventional soot blowing for antimony removal in the prior art, where the oxidation and volatilization rate of antimony metal becomes extremely slow when the antimony metal content in the alloy in the furnace drops below 18%, resulting in a significant reduction in the antimony removal effect of soot blowing. This invention provides a method for removing antimony from lead-antimony alloys by adding bismuth during soot blowing.

[0005] The objective of this invention is achieved through the following technical solution: a method for removing antimony from lead-antimony alloys by bismuth blowing, the method comprising the following process steps:

[0006] S1: Lead anode slime reduction smelting: The lead anode slime produced in the crude lead electrolytic refining process is fed into a smelting furnace for reduction smelting to obtain a smelted mixture. The lead anode slime produced in the crude lead electrolytic refining process usually contains about 2% bismuth and some other metals, of which about 11.69% lead and as much as 56.25% antimony remain. For these materials, a portion of the antimony can be removed by conventional pyrometallurgical processes, which is to be carried out in step S2 of this application after reduction smelting.

[0007] S2: Initial Soot Blowing of the Molten Mixture: The molten mixture obtained from the reduction smelting in step S1 is soot blown to remove antimony, resulting in a primary soot blown mixture. The composition of this primary soot blown mixture is approximately 7% bismuth, 60% lead, 18% antimony, and approximately 15% silver and other metals. For antimony removal, when the antimony content in the furnace alloy is reduced to below 18% through pyrometallurgical soot blowing, the oxidation and volatilization rate of antimony metal becomes extremely slow. At this point, further soot blowing would alter both material consumption and the enrichment of other metals. Continuing soot blowing would inevitably lead to a significant increase in production costs. Therefore, this method proceeds to step S3 after the initial soot blowing has reduced the antimony content in the material to approximately 18%.

[0008] S3: Vacuum distillation of the primary sootblowing mixture: The primary sootblowing mixture obtained from the sootblowing process in step S2 (antimony removal) is fed into a vacuum furnace for vacuum distillation. The volatilized material is collected to obtain the primary distillation mixture, which is the high-bismuth alloy material. The collected primary distillation mixture, i.e., the high-bismuth alloy material, contains 7%–15% bismuth, 88%–90% lead, and 1%–2% antimony. Vacuum distillation can effectively enrich lead while removing antimony; however, its production cost is extremely high, requiring significant investment and hindering cost control, making it inconvenient for long-term, large-scale production. This application addresses this by enriching bismuth and adjusting subsequent processes to avoid repeatedly using this step, specifically step S4.

[0009] S4: Electrolysis of the primary distillation mixture to remove lead: The primary distillation mixture obtained in step S3, i.e., the high-bismuth alloy material, is electrolyzed, and the anode material is collected to obtain high-bismuth anode slime. This electrolyzed high-bismuth anode slime contains 30-40% bismuth, 15-25% lead, and 10-20% antimony. The antimony is further enriched and flows back into the production system for recycling. This high-bismuth anode slime also contains other metals that can be recycled. Therefore, in step S5 of this method, while collecting usable metals, the enriched antimony is removed.

[0010] S5: Secondary soot blowing of the primary soot blowing mixture: The primary distillation mixture obtained in step S3, i.e., the high bismuth alloy material, is mixed with the smelted mixture obtained in step S1. After mixing and smelting again, the primary soot blowing method is used in step S2 to remove antimony, resulting in a secondary soot blowing mixture. Alternatively, the high bismuth anode mud obtained in step S4 is mixed with the lead anode mud produced in the original crude lead electrolytic refining process, and then step S1 is performed. Step S2 is then performed again, and the primary soot blowing method is used in step S2 to remove antimony, resulting in a secondary soot blowing mixture. The secondary soot blowing mixture contains approximately 3% antimony, approximately 40% lead, approximately 45% bismuth, and approximately 12% silver and other metals. At this point, the antimony content has been reduced to approximately 3%, and the secondary soot blowing mixture can be directly electrolyzed to obtain lead, or other subsequent operations can be performed, i.e., step S6.

[0011] S6: Secondary soot blowing mixture recycling treatment: The secondary soot blowing mixture obtained in step S5 is recycled and subjected to other subsequent treatments.

[0012] Optionally, in step S5, when the high-bismuth alloy material obtained in step S3 is mixed with the molten mixture obtained in step S1, the bismuth content is controlled to be between 28% and 33% during the second mixing.

[0013] Optionally, in step S5, when mixing the high-bismuth anode mud obtained in step S4 with the lead anode mud produced in the original crude lead electrolytic refining process, the bismuth content of the alloy in the furnace after slag removal is controlled between 17% and 25%.

[0014] Optionally, the furnace temperature in step S1 is 700℃~900℃.

[0015] Optionally, the furnace reduction smelting time in step S1 is 3 to 7 days.

[0016] Optionally, the antimony removal time in step S2 is 3 to 8 days.

[0017] This invention has the following advantages: Without altering the existing production facilities, this invention changes the alloy composition in the furnace by adding bismuth materials (high-bismuth alloy materials or high-bismuth anode mud) during the lead-antimony alloy soot blowing process. This allows the antimony metal content in the furnace alloy to drop below 18% while still maintaining a good oxidation and volatilization rate. Furthermore, by adjusting the bismuth metal content in the furnace alloy, the soot blowing effect can be significantly improved. This method is simple to operate, safe, and reliable. At the end of the soot blowing process, the antimony metal content in the furnace alloy can be reduced to about 3%. In production practice, this method can reduce the accumulation of antimony metal in the production system, shorten the antimony smelting production cycle, and significantly improve the metal recovery rate. Attached Figure Description

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

[0019] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] Example 1

[0024] like Figure 1 The method shown is a bismuth blowing process for removing antimony from a lead-antimony alloy. This method was used in production, and the specific steps are as follows:

[0025] S1: The lead anode mud produced in the original crude lead electrolytic refining process is put into the smelting furnace for reduction smelting. This smelting process can melt the material to obtain a smelted mixture.

[0026] S2: The mixture of molten material obtained by reduction smelting in step S1 is bleached to remove antimony by soot blowing. The reduction smelting and antimony removal by soot blowing are carried out in one smelting furnace. After antimony removal by soot blowing, a mixture of bleached material can be obtained.

[0027] S3: The primary soot mixture obtained by soot blowing to remove antimony in step S2 is put into a vacuum furnace for vacuum distillation. The volatilized material is collected to obtain the primary distillation mixture, which is the high bismuth alloy material.

[0028] S4: Electrolyze the high-bismuth alloy material obtained by vacuum distillation in step S3, and collect the anode material to obtain high-bismuth anode mud.

[0029] S5: After mixing the high bismuth anode mud obtained in step S4 with the lead anode mud produced in the original crude lead electrolytic refining process, step S1 is performed again, and step S2 is performed again. After step S2, a second soot blowing method is used to remove antimony to obtain a second soot blowing mixture.

[0030] S6: The secondary soot blowing mixture obtained in step S2 is recycled for further processing.

[0031] In this embodiment, the high-bismuth anode mud obtained in step S4 was directly mixed with the lead anode mud produced in the original crude lead electrolytic refining process. After step S1, step S2 was performed again. A production experiment was conducted and the specific records are as follows:

[0032] 1. This experiment was conducted using furnace #7 in the precious metals workshop;

[0033] 2. The reduction smelting time is 4 days (April 21st to April 24th);

[0034] 3. The antimony removal process will last for 3 days (April 25th to April 27th);

[0035] 4. Furnace temperature: 700℃~900℃;

[0036] 5. The raw materials and their contents used in the experiment are shown in the table below:

[0037]

[0038] During the production process, the existing production facilities were not altered. Lead anode mud produced in the crude lead electrolytic refining process was directly added to the original No. 7 smelting furnace. The furnace temperature was controlled at 800℃, with fluctuations not exceeding 50℃. Specifically, lead anode mud (wet lead mud) was added starting from the middle shift on April 21st, and high-bismuth anode mud was added starting from the middle shift on April 23rd. Reduction smelting in the reverberatory furnace continued until the end of the middle shift on April 24th. After completion, a smelted mixture was obtained. The smelted mixture was found to mainly consist of: high-bismuth alloy, black oxide powder, slag, and dry slag. Its composition is shown in the table below.

[0039]

[0040] After the afternoon shift on April 24th, the antimony removal operation began with air blowing. It is important to note that before air blowing to remove antimony, the bismuth content of the alloy in the furnace after slag removal from smelting must be controlled between 17% and 25%, with 21% being optimal. If the bismuth content is too low during this process, it can be adjusted by adding bismuth-containing alloy materials or directly adding bismuth alloy. Then, daily samples of the high-bismuth alloy from the smelting product are taken to test the changes in lead, antimony, and bismuth content. The changes in the composition of the high-bismuth alloy during the antimony removal process are shown in the table below:

[0041]

[0042] The table above clearly shows the changes in lead, antimony, and bismuth content. During the antimony removal process after adding high-bismuth anode mud, lead and bismuth are enriched as production progresses, while antimony is removed by blowing, reducing its content to 2.7%. This method can reduce the antimony content to below 3% by directly adding high-bismuth anode mud to lead anode mud without vacuum distillation, and then removing antimony through smelting and blowing. This reduces production costs, streamlines production processes, and optimizes production.

[0043] After the afternoon shift ended on April 27th, the final high-bismuth alloy was taken again for composition analysis. The final product is shown in the table below:

[0044]

[0045] Through this experiment, a noble lead with a low antimony content was finally obtained. This noble lead (lead-bismuth alloy) can be further processed for comprehensive recovery in subsequent processes.

[0046] This method, without altering the existing production facilities, changes the alloy composition in the furnace by adding bismuth materials (high-bismuth alloy or high-bismuth wet sludge) during the lead-antimony alloy soot blowing process. This allows the antimony metal content in the furnace alloy to drop below 18% while still maintaining a good oxidation and volatilization rate. By adjusting the bismuth metal content in the furnace alloy, the soot blowing effect can be significantly improved. This method is simple to operate, safe, and reliable. At the end of the soot blowing process, the antimony metal content in the furnace alloy can be reduced to below 3%. In production practice, it can reduce the accumulation of antimony metal in the production system, shorten the antimony smelting production cycle, and significantly improve the metal recovery rate.

[0047] Example 2:

[0048] like Figure 1 The method for removing antimony from a lead-antimony alloy by adding bismuth during smelting is shown. To further verify the effectiveness of this method in removing antimony from the molten material, production was carried out using this method, and the changes in antimony and bismuth were mainly recorded. The specific steps are as follows:

[0049] S1: The lead anode mud produced in the original crude lead electrolytic refining process is put into the smelting furnace for reduction smelting. This smelting process can melt the material to obtain a smelted mixture.

[0050] S2: The mixture of molten material obtained by reduction smelting in step S1 is bleached to remove antimony by soot blowing. The reduction smelting and antimony removal by soot blowing are carried out in one smelting furnace. After antimony removal by soot blowing, a mixture of bleached material can be obtained.

[0051] S3: The primary soot mixture obtained by soot blowing to remove antimony in step S2 is put into a vacuum furnace for vacuum distillation. The volatilized material is collected to obtain the primary distillation mixture, which is the high bismuth alloy material.

[0052] S5: The high bismuth alloy material obtained in step S3 is mixed with the molten mixture obtained in step S1 and then mixed and smelted again. At the same time, the antimony is removed by blowing air in step S2 to obtain the secondary soot mixture.

[0053] S6: The secondary soot blowing mixture obtained in step S5 is recycled for further processing.

[0054] In this embodiment, a first-distilled mixture, namely high-bismuth alloy material (also known as high-bismuth oxygen powder), was added to the smelted mixture obtained after smelting lead anode mud in a smelting furnace using the method described above. After smelting for two days, the bismuth alloy mixture was added again for S2 mixing and smelting, and antimony was removed by blowing air. The specific records of this experiment are as follows:

[0055] 1. This experiment was conducted using furnace #7 in the precious metals workshop;

[0056] 2. The reduction smelting time is 4.5 days (January 9th to January 13th);

[0057] 3. The antimony removal process will last for 6 days (January 14th to January 19th);

[0058] 4. Furnace temperature: 700℃~900℃;

[0059] 5. The raw materials and their contents used in the experiment are shown in the table below:

[0060]

[0061] During the production process, without altering the existing production facilities, high-bismuth oxygen powder and bismuth-containing alloys were directly added to the molten mixture being smelted in the original No. 7 smelting furnace. The furnace temperature was controlled at 800℃, with fluctuations not exceeding 80℃. Specifically, high-bismuth oxygen powder was continuously added during the interval between the night shift on January 9th and January 11th. Starting from the afternoon shift on January 13th, bismuth-containing alloys were added to adjust the bismuth content before blasting. Reduction smelting in the reverberatory furnace continued until the end of the night shift on January 13th. After completion, the molten mixture was obtained. The main components of the reduction smelting output, i.e., the molten mixture, were detected to be: high-bismuth alloy, black oxygen powder, slag, and dry slag. The composition is shown in the table below.

[0062]

[0063] After the night shift on January 14th, the antimony removal operation began with air blowing. It's important to note that before air blowing to remove antimony, the bismuth content must be controlled between 28% and 33% when mixing the primary distillation mixture (high-bismuth alloy material) obtained in step S3 with the smelted mixture obtained in step S1. Since this embodiment primarily focuses on verification, measures were taken to adjust the bismuth content when adding the bismuth-containing alloy. This was to ensure the bismuth content before air blowing to remove antimony wasn't too low. The final control required ensuring that the bismuth content of the alloy in the furnace after slag removal was approximately 11.26% before antimony removal began. Essentially, this verifies the impact of the bismuth content of the alloy in the furnace after slag removal on antimony removal through air blowing, and also indirectly verifies the impact of the bismuth content when mixing the primary distillation mixture (high-bismuth alloy material) with the smelted mixture on antimony removal through air blowing. Then, daily samples of the high-bismuth alloy from the smelting product were taken to test the changes in antimony and bismuth content. The changes in the high-bismuth alloy composition during the antimony removal process are shown in the table below:

[0064]

[0065] The table above clearly shows the changes in antimony and bismuth content. When the bismuth content was controlled at around 11.26% before antimony removal by blowing air, bismuth was enriched during production, while antimony was removed by the blowing air. Furthermore, its content only decreased to 3.9%. This indicates that when the bismuth content before blowing air removal is below 17%, it affects the antimony removal rate. After 6 days of production, the antimony content was only around 3.9%. However, this method still reduces the antimony content to around 3% without vacuum distillation, simply by removing antimony through melting and blowing air. This reduces production costs, streamlines production processes, and optimizes production.

[0066] To record the actual levels of antimony and bismuth emitted, and to analyze the emitted oxide powder, the changes in antimony and bismuth content were recorded as shown in the table below:

[0067] 1.14 Morning Shift content / % 34.75 2.69 1.15 Morning Shift content / % 46.37 1.71 1.16 Morning Shift content / % 57.27 1.09 1.17 Morning Shift content / % 64.13 0.33 1.18 Morning Shift content / % 63.83 0.22 1.19 Morning Shift content / % 55.23 0.68

[0068] As shown in the table above, antimony was continuously blown out during production, reaching its peak on January 18th, at which time the bismuth content was approximately 17.82%, representing the optimal removal rate. However, due to antimony losses during production, it is necessary to initially control the bismuth content above 17%, with an optimal initial control of 21%. This, combined with consumption and enrichment, ensures efficient antimony removal within the furnace. This also explains why the bismuth content is controlled between 28% and 33% when mixing the high-bismuth alloy material with the smelted mixture obtained in step S1. Some bismuth is lost during the mixing and smelting process, and further losses occur during the blowing process. Therefore, controlling the bismuth content within this range is suitable, with 29% being preferred. Of course, in reality, the higher the bismuth content, the better. However, this is not necessary in actual production because bismuth is both enriched and consumed during the production process. As long as a suitable initial input is set, the removal of antimony can be guaranteed. The difference lies only in the length of time it takes. Of course, this requires comprehensive consideration of material consumption and production costs. Taking a median input of 21% is the appropriate amount with the lowest production cost.

[0069] After the afternoon shift ended on January 19th, the final high-bismuth alloy was taken again for composition analysis. The final product is shown in the table below:

[0070] Lead-bismuth alloy content / % 75.9 3.66 20.78 0.45

[0071] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for removing antimony from a lead-antimony alloy by bismuth blowing, characterized in that: This method includes the following process steps: S1: Lead anode mud reduction smelting: The lead anode mud produced in the original crude lead electrolytic refining process is put into a smelting furnace for reduction smelting to obtain a smelted mixture; S2: Initial soot blowing of the molten mixture: The molten mixture obtained from the reduction smelting in step S1 is soot blown to remove antimony, resulting in a primary soot blowing mixture; S3: Vacuum distillation of primary soot blowing mixture: The primary soot blowing mixture obtained by soot blowing to remove antimony in step S2 is put into a vacuum furnace for vacuum distillation, and the volatilized material is collected to obtain the primary distillation mixture. S4: Electrolysis of lead from primary distillation mixture: Electrolyze the primary distillation mixture obtained from vacuum distillation in step S3, and collect the anode material to obtain high bismuth anode mud; S5: Secondary soot blowing of the primary soot blowing mixture: The primary distillation mixture obtained in step S3 is mixed with the smelted mixture obtained in step S1, and then mixed and smelted again while undergoing primary soot blowing to remove antimony, resulting in a secondary soot blowing mixture. Alternatively, the high-bismuth anode mud obtained in step S4 is mixed with the lead anode mud produced in the original crude lead electrolytic refining process, followed by step S1, and then step S2. After step S2, primary soot blowing is performed to remove antimony, resulting in a secondary soot blowing mixture. When mixing the primary distillation mixture obtained in step S3 with the smelted mixture obtained in step S1, the bismuth content is controlled between 28% and 33%. When mixing the high-bismuth anode mud obtained in step S4 with the lead anode mud produced in the original crude lead electrolytic refining process, the bismuth content of the alloy in the furnace after slag removal is controlled between 17% and 25%. S6: Secondary soot blowing mixture recycling treatment: The secondary soot blowing mixture obtained in step S5 is recycled and subjected to other subsequent treatments.

2. The method for removing antimony from a lead-antimony alloy by bismuth blowing according to claim 1, characterized in that: The furnace temperature in step S1 is 700 ℃~900 ℃.

3. The method for removing antimony from a lead-antimony alloy by bismuth blowing according to claim 1, characterized in that: In step S1, the reduction smelting time in the furnace is 4 to 7 days.

4. The method for removing antimony from a lead-antimony alloy by bismuth blowing according to claim 1, characterized in that: The antimony removal time in step S2 is 3 to 8 days.

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