Method for recovering bismuth from precious lead

Abstract

The invention relates to a method for recovering bismuth from precious lead, and belongs to the technical field of metallurgical engineering. The method is carried out according to the following steps: (1) liquation copper removal; (2) primary vacuum distillation; (3) oxidizing to remove arsenic and antimony; (4) introducing chlorine to remove lead; (5) secondary vacuum distillation; (6) refining; (7) ingot casting; and the obtained refined bismuth liquid is cast into an ingot, and the finished product bismuth with the bismuth content larger than 99.99% is obtained. According to the method, on the basis that the technological process is shortened, efficient recovery of bismuth is achieved, and the product meeting the national standard bismuth ingot Bi998 grade requirement can be directly prepared.

Description

Technical Field

[0001] The present application relates to the field of metallurgical engineering technology, and in particular to a method for recovering bismuth from precious lead. Background Art

[0002] Precious lead is the main intermediate product produced in the precious metal silver metallurgical process. It is rich in gold, silver, copper, lead, bismuth and antimony, and has high value. Production companies have conducted research on the recovery of valuable metals in precious lead.

[0003] The existing technologies for recovering bismuth from precious lead are mainly pyrometallurgy, hydrometallurgy or pyrometallurgy-hydrometallurgy combined. The disadvantage of wet recovery of bismuth is that waste liquid is generated, and the waste liquid is inconvenient to handle, which increases the processing cost. The problem of simple pyrometallurgy treatment is low direct recovery rate of bismuth; and the problem of pyrometallurgy-hydrometallurgy combined treatment is that it not only faces the problem of waste liquid treatment, but also has the disadvantage of long process flow.

[0004] For example, the publication number CN104141057B discloses a method for recovering bismuth from precious lead, which uses a combination of pyrometallurgy and hydrometallurgy to efficiently recover bismuth from precious lead. First, the precious lead is placed in a vacuum furnace, and then lead, antimony, bismuth and copper are separated by vacuum distillation to produce primary high-bismuth lead and precious silver. The produced primary high-bismuth lead is placed in a vacuum furnace, and then lead, antimony, bismuth and copper are separated by vacuum distillation again under the above conditions to produce secondary high-bismuth lead and residual precious silver. The obtained secondary high-bismuth lead and crude lead ingredients are put into an anode pot to cast a bismuth anode plate, which is then loaded into an electrolytic cell and mixed with the main process of lead electrolysis for electrolytic refining to produce precipitated lead and high-bismuth anode mud after washing. The obtained high-bismuth anode mud is subjected to reduction smelting and blowing to produce crude bismuth. The obtained crude bismuth is subjected to pyrometallurgy refining, sulfur is added to remove copper, oxidation is used to remove arsenic and antimony, chlorine is passed through to remove lead, and zinc is added to remove silver. Finally, caustic soda and saltpeter are added for refining to produce bismuth ingot products that meet national standards.

[0005] Although the method claims to have a simple and refined process flow, looking at the technical solution as a whole, the technical solution only requires two vacuum distillations in step (1); in step (2), the secondary high-bismuth lead is electrolyzed; in step (3), the high-bismuth anode mud is reduced, smelted, and blown to produce crude bismuth; in step (4), the crude bismuth is pyro-refined, sulfur is added to remove copper, oxidation is used to remove arsenic and antimony, chlorine is passed through to remove lead, zinc is added to remove silver, and chlorine is passed through to remove zinc, and finally caustic soda and saltpeter are added for refining to produce bismuth ingot products that meet national standards.

[0006] Furthermore, although the quality of the bismuth ingots finally obtained by this method meets the national standard Bi998 grade requirements for bismuth ingots, and the recovery rate of bismuth can reach more than 99%, it involves extremely many processes, which inevitably leads to the problem of high energy consumption and cumbersome operation, and is not suitable for promotion and use in enterprises.

[0007] Therefore, how to achieve efficient recovery of bismuth on the basis of shortening the process has always been a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0008] In order to solve or partially solve the problems existing in the related art, the present application provides a method for recovering bismuth from precious lead. This method achieves efficient recovery of bismuth on the basis of shortening the process flow, and can directly prepare products that meet the national standard bismuth ingot Bi998 grade requirements.

[0009] A method for recovering bismuth from precious lead in the present application is carried out according to the following steps:

[0010] (1) Copper removal by smelting

[0011] After the precious lead is melted at 600-700℃, the temperature is then lowered to 340-450℃ for smelting and copper removal to obtain copper-free precious lead; when the precious lead contains high levels of arsenic and antimony, copper has a strong affinity for arsenic and antimony, which can generate copper arsenide and copper antimonide that are insoluble in lead and float on the surface of the lead liquid together with the copper slag and are separated from the lead;

[0012] (2) One vacuum distillation

[0013] The copper-free precious lead obtained in step (1) is added into a vacuum distillation furnace for a vacuum distillation, with a vacuum degree of 5-30 Pa, a temperature of 600-700° C., and a distillation time of 5-10 h; an arsenic-antimony alloy is produced on the furnace shell, the evaporated product is a lead-bismuth-antimony alloy, and the residue is a gold-silver alloy;

[0014] Arsenic antimony alloy is sold out, lead-bismuth-antimony alloy is sent for lead, bismuth and antimony recovery, and gold-silver alloy is sent to the main process for gold and silver recovery;

[0015] (3) Oxidation to remove arsenic and antimony

[0016] The lead-bismuth-antimony alloy is heated to 650-750℃, and then compressed air is blown onto the surface of the melt to oxidize and slag to remove arsenic and antimony. The operation time is 4-10 hours, and the end point is when the volatilized white smoke becomes thin. Arsenic-antimony dust and 1# crude bismuth are produced; the arsenic-antimony dust can be directly sold out;

[0017] (4) Chlorine lead removal

[0018] Chlorine gas is introduced into the obtained 1# crude bismuth through a glass tube. Chlorine reacts with the lead in 1# crude bismuth to generate PbCl2. The density of PbCl2 is 5.91g / cm 3 , bismuth liquid density 10g / cm 3 , the dark grey PbCl2 is removed in the form of scum to obtain 2# crude bismuth;

[0019] (5) Secondary vacuum distillation

[0020] 2# crude bismuth is added into a vacuum distillation furnace for secondary vacuum distillation, with a vacuum degree of 5-20 Pa, a temperature of 800-850°C, and a distillation time of 1-2 hours; the evaporated product is 3# crude bismuth, and the residue is crude silver;

[0021] (6) Refining

[0022] Adding caustic soda and potassium nitrate to the obtained 3# crude bismuth for refining to remove trace amounts of Cl, Zn, As, Sb, Pb, and Te to obtain refined bismuth liquid;

[0023] (7) Ingot

[0024] The refined bismuth liquid is cast into ingots at 320-400° C. to obtain a finished bismuth product containing more than 99.99% bismuth.

[0025] The beneficial effects of this application are:

[0026] In this application, when precious lead is processed to recover bismuth, a vacuum distillation combined with a pyrometallurgical method is used. In particular, by controlling the order of vacuum distillation and coordinating with pyrometallurgical smelting, bismuth is efficiently recovered, and the bismuth recovery rate reaches more than 99%, and the prepared finished bismuth contains more than 99.99% bismuth. In addition, compared with the existing method of combining wet and pyrometallurgical methods, this application does not produce any waste liquid and is more convenient to operate; further, compared with the pyrometallurgical part of a method for recovering bismuth from precious lead in publication number CN104141057B, this application has fewer steps and a more streamlined process. The method in this application achieves efficient recovery of bismuth on the basis of shortening the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the process flow in this application. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in more detail below with reference to examples. Although the embodiments of the present application are shown in the examples, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and the scope of the present application can be fully communicated to those skilled in the art.

[0029] Example 1

[0030] A method for recovering bismuth from precious lead in this embodiment is carried out according to the following steps:

[0031] (1) Copper removal by smelting

[0032] After melting precious lead (containing 4.2% copper, 18.0% lead, 20% antimony, 9.7% bismuth, 14% silver, 6.6% arsenic, and 210 g / t gold) at 670° C., the temperature is then lowered to 450° C. for smelting and copper removal to obtain copper-removed precious lead (containing 1.2% copper, 19.2% lead, 23% antimony, 10.8% bismuth, 15% silver, 77.9% arsenic, and 235 g / t gold);

[0033] (2) One vacuum distillation

[0034] The copper-free precious lead obtained in step (1) is added into a vacuum distillation furnace for a vacuum distillation, with a vacuum degree of 20-30 Pa, a temperature of 600-700° C., and a distillation time of 5 h; an arsenic-antimony alloy is produced on the furnace shell, the evaporated product is a lead-bismuth-antimony alloy, and the residue is a gold-silver alloy;

[0035] Lead-bismuth-antimony alloy contains 0.02% copper, 28% lead, 18% antimony, 6.1% bismuth, 0.3% silver and 3% arsenic;

[0036] (3) Oxidation to remove arsenic and antimony

[0037] The lead-bismuth-antimony alloy is heated to 650-750℃, and then compressed air is blown onto the surface of the melt to oxidize and slag to remove arsenic and antimony. The operation time is 10 hours, and the end point is when the volatilized white smoke becomes thin, and arsenic-antimony smoke and 1# crude bismuth are produced;

[0038] 1# crude bismuth contains 2.2% copper, 18% lead, 0.3% antimony, 66% bismuth, 0.3% silver and 0.5% arsenic;

[0039] (4) Chlorine lead removal

[0040] Chlorine gas is introduced into the obtained 1# crude bismuth through a glass tube, and the chlorine reacts with the lead in the 1# crude bismuth to form PbCl2 scum which is removed to obtain 2# crude bismuth;

[0041] The PbCl2 slag contains 37% lead, 0.4% antimony, 0.05% bismuth, 0.03% silver and 0.5% arsenic;

[0042] 2# crude bismuth contains 0.3% antimony, 95% bismuth, 0.2% silver and 0.6% arsenic;

[0043] (5) Secondary vacuum distillation

[0044] 2# crude bismuth is added into a vacuum distillation furnace for secondary vacuum distillation, with a vacuum degree of 5-20 Pa, a temperature of 800-850°C, and a distillation time of 1.5 h; the evaporated product is 3# crude bismuth, and the residue is crude silver;

[0045] 3# crude bismuth contains 0.08% antimony, 98% bismuth and 0.4% arsenic;

[0046] (6) Refining

[0047] Adding caustic soda and potassium nitrate to the obtained 3# crude bismuth for refining to obtain refined bismuth liquid;

[0048] (7) Ingot

[0049] The refined bismuth liquid is cast into ingots to obtain finished bismuth containing more than 99.99% bismuth. The recovery rate of bismuth is 97%.

[0050] The chemical composition analysis of the finished bismuth obtained in Example 1 is shown in the following table:

[0051]

[0052] Example 2

[0053] A method for recovering bismuth from precious lead in this embodiment is carried out according to the following steps:

[0054] (1) Copper removal by smelting

[0055] After melting precious lead (containing 5.1% copper, 16% lead, 23.9% antimony, 6.5% bismuth, 11% silver, 7% arsenic, and 265g / t gold) at 650°C, the temperature is then lowered to 400°C for smelting and copper removal to obtain copper-removed precious lead (containing 1.4% copper, 18% lead, 24.5% antimony, 9% bismuth, 12% silver, 8% arsenic, and 285g / t gold);

[0056] (2) One vacuum distillation

[0057] The copper-free precious lead obtained in step (1) is added into a vacuum distillation furnace for a vacuum distillation, with a vacuum degree of 20-30 Pa, a temperature of 600-700° C., and a distillation time of 6 hours; an arsenic-antimony alloy is produced on the furnace shell, the evaporated product is a lead-bismuth-antimony alloy, and the residue is a gold-silver alloy;

[0058] Lead-bismuth-antimony alloy contains 0.02% copper, 32% lead, 19% antimony, 9% bismuth, 0.3% silver and 3% arsenic;

[0059] (3) Oxidation to remove arsenic and antimony

[0060] The lead-bismuth-antimony alloy is heated to 650-750℃, and then compressed air is blown onto the surface of the melt to oxidize and slag to remove arsenic and antimony. The operation time is 10 hours, and the end point is when the volatilized white smoke becomes thin, and arsenic-antimony smoke and 1# crude bismuth are produced;

[0061] 1# crude bismuth contains 1.2% copper, 19% lead, 0.4% antimony, 70% bismuth, 0.1% silver and 0.5% arsenic;

[0062] (4) Chlorine lead removal

[0063] Chlorine gas is introduced into the obtained 1# crude bismuth through a glass tube, and the chlorine reacts with the lead in the 1# crude bismuth to form PbCl2 scum which is removed to obtain 2# crude bismuth;

[0064] The PbCl2 slag contains 33% lead, 0.5% antimony, 0.02% bismuth, 0.01% silver and 0.8% arsenic;

[0065] 2# crude bismuth contains 0.4% antimony, 96% bismuth, 0.3% silver and 0.3% arsenic;

[0066] (5) Secondary vacuum distillation

[0067] 2# crude bismuth is added into a vacuum distillation furnace for secondary vacuum distillation, with a vacuum degree of 5-20Pa, a temperature of 800-850°C, and a distillation time of 2h; the evaporated product is 3# crude bismuth, and the residue is crude silver;

[0068] 3# crude bismuth contains 0.1% antimony, 99% bismuth and 0.5% arsenic;

[0069] (6) Refining

[0070] Adding caustic soda and potassium nitrate to the obtained 3# crude bismuth for refining to obtain refined bismuth liquid;

[0071] (7) Ingot

[0072] The refined bismuth liquid is cast into ingots to obtain finished bismuth containing more than 99.99% bismuth.

[0073] The recovery rate of bismuth was 98%.

[0074] The chemical composition analysis of the finished bismuth obtained in Example 2 is shown in the following table:

[0075]

[0076] Example 3

[0077] A method for recovering bismuth from precious lead in this embodiment is carried out according to the following steps:

[0078] (1) Copper removal by smelting

[0079] After melting precious lead (containing 3% copper, 14% lead, 18% antimony, 10% bismuth, 20% silver, 6% arsenic, and 295 g / t gold) at 600° C., the temperature is then lowered to 340° C. for smelting and copper removal to obtain copper-removed precious lead (containing 1% copper, 16% lead, 20% antimony, 8% bismuth, 21% silver, 6% arsenic, and 205 g / t gold);

[0080] (2) One vacuum distillation

[0081] The copper-free precious lead obtained in step (1) is added into a vacuum distillation furnace for a vacuum distillation, with a vacuum degree of 20-30 Pa, a temperature of 600-700° C., and a distillation time of 6 hours; an arsenic-antimony alloy is produced on the furnace shell, the evaporated product is a lead-bismuth-antimony alloy, and the residue is a gold-silver alloy;

[0082] Lead-bismuth-antimony alloy contains 0.01% copper, 30% lead, 21% antimony, 8.5% bismuth, 0.3% silver and 4.5% arsenic;

[0083] (3) Oxidation to remove arsenic and antimony

[0084] The lead-bismuth-antimony alloy is heated to 650-750℃, and then compressed air is blown onto the surface of the melt to oxidize and slag to remove arsenic and antimony. The operation time is 12 hours, and the end point is reached when the volatilized white smoke becomes thin, and arsenic-antimony smoke and 1# crude bismuth are produced;

[0085] 1# crude bismuth contains 2% copper, 18% lead, 0.5% antimony, 68% bismuth, 0.2% silver and 0.5% arsenic;

[0086] (4) Chlorine lead removal

[0087] Chlorine gas is introduced into the obtained 1# crude bismuth through a glass tube, and the chlorine reacts with the lead in the 1# crude bismuth to form PbCl2 scum which is removed to obtain 2# crude bismuth;

[0088] The PbCl2 slag contains 40% lead, 0.5% antimony, 0.02% bismuth, 0.03% silver and 0.5% arsenic;

[0089] 2# crude bismuth contains 0.3% antimony, 94% bismuth, 0.2% silver and 0.6% arsenic;

[0090] (5) Secondary vacuum distillation

[0091] 2# crude bismuth is added into a vacuum distillation furnace for secondary vacuum distillation, with a vacuum degree of 5-20Pa, a temperature of 800-850°C, and a distillation time of 2h; the evaporated product is 3# crude bismuth, and the residue is crude silver;

[0092] 3# crude bismuth contains 0.04% antimony, 97% bismuth and 0.4% arsenic;

[0093] (6) Refining

[0094] Adding caustic soda and potassium nitrate to the obtained 3# crude bismuth for refining to obtain refined bismuth liquid;

[0095] (7) Ingot

[0096] The refined bismuth liquid is cast into ingots to obtain finished bismuth containing more than 99.99% bismuth. The recovery rate of bismuth is 99%.

[0097] The chemical composition analysis of the finished bismuth obtained in Example 3 is shown in the following table:

[0098]

[0099] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for recovering bismuth from precious lead, characterized in that: Follow these steps: (1) Copper removal by smelting After the precious lead is melted at 600-700°C, the temperature is then lowered to 340-450°C for copper removal by smelting to obtain copper-removed precious lead; (2) Single vacuum distillation The copper-free precious lead obtained in step (1) is added into a vacuum distillation furnace for a vacuum distillation, with a vacuum degree of 5-30 Pa, a temperature of 600-700° C., and a distillation time of 5-10 h; an arsenic-antimony alloy is produced on the furnace shell, the evaporated product is a lead-bismuth-antimony alloy, and the residue is a gold-silver alloy; (3) Oxidation to remove arsenic and antimony The lead-bismuth-antimony alloy is heated to 650-750℃, and then compressed air is blown onto the surface of the melt to oxidize and slag to remove arsenic and antimony. The operation time is 4-10 hours, and the end point is reached when the volatilized white smoke becomes thin, and arsenic-antimony smoke and 1# crude bismuth are produced; (4) Chlorine lead removal Chlorine gas is introduced into the obtained 1# crude bismuth through a glass tube, and the chlorine reacts with the lead in the 1# crude bismuth to form PbCl2 scum which is removed to obtain 2# crude bismuth; (5) Secondary vacuum distillation 2# crude bismuth is added into a vacuum distillation furnace for secondary vacuum distillation, with a vacuum degree of 5-20 Pa, a temperature of 800-850°C, and a distillation time of 1-2 hours; the evaporated product is 3# crude bismuth, and the residue is crude silver; (6) Refining Adding caustic soda and potassium nitrate to the obtained 3# crude bismuth for refining to obtain refined bismuth liquid; (7) Ingot The refined bismuth liquid is cast into ingots to obtain finished bismuth containing more than 99.99% bismuth.

2. A method for recovering bismuth from precious lead according to claim 1, characterized in that: The precious lead contains 3-5% copper, 13-18% lead, 18-24% antimony, 6-10% bismuth, 10-20% silver, 5-8% arsenic and 200-300g / t gold.

3. A method for recovering bismuth from precious lead according to claim 1, characterized in that: The copper-removing precious lead contains 1-1.5% copper, 14-19% lead, 19-25% antimony, 7-11% bismuth, 11-21% silver, 5-8% arsenic and 200-300g / t gold.

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