A method for adsorbing lead from a noble metal alloy melt

Abstract

This invention discloses a method for adsorbing lead from molten precious metal alloys, comprising the steps of melting the precious metal material; using an adsorbent to capture lead; and casting ingots. Adding this step to the production process effectively removes lead, offering advantages such as simple operation, significant results, batch stability, and environmental friendliness. It achieves the goal of fixing lead in a solid, preventing the formation of gaseous emissions that would cause environmental pollution. Testing shows that the lead content in the precious metal alloy ingots is less than 0.005%. Furthermore, it combines medium-frequency furnace heating with historical big data to obtain the optimal heating strategy, thereby ensuring the automation and intelligence of the heating process, offering advantages such as improved heating quality and reduced energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of precious metal smelting technology, specifically relating to a method for adsorbing lead from precious metal alloy ingots. Background Technology

[0002] Lead is a common metallic element with numerous compounds and a wide range of industrial uses. Its main compounds include lead oxide, lead sulfide, and lead nitrate. Industrially, lead is widely used in the manufacture of lead-acid batteries, cable sheaths, lead pipes, and lead plates, and plays a role in chemical, metallurgical, and construction industries. However, lead's toxicity limits its use in certain applications, requiring careful handling to avoid environmental pollution and health risks.

[0003] Lead is commonly used as a collector in precious metal smelting. During the smelting process, lead can form alloys with precious metals such as gold and silver, thereby enriching and collecting these metals. Lead anode mud is one of the main raw materials for extracting silver and gold. Traditional pyrometallurgical methods use ash blowing to remove lead, but this method has drawbacks such as low direct silver recovery rate, difficulty in the comprehensive recovery of valuable elements in the slag, and easy environmental pollution. A method for wet treatment of lead anode mud, patent number CN89103853.1, proposes a comprehensive wet treatment process for lead anode mud, achieving high direct recovery rates of silver and gold (Ag 96-98%, Au 98%), and also comprehensively recovering antimony, bismuth, and copper. A pretreatment method for lead anode mud before wet acid leaching, patent number ZL96113177.2, applied in the field of precious metal metallurgy, pretreats lead anode mud to improve the efficiency of subsequent wet acid leaching and the recovery rate of precious metals. An electrolyte and electrolysis method for electrolytic refining crude lead, patent number CN201510128363.8, relates to an electrolyte based on a methanesulfonic acid solution system for electrolytic refining crude lead. This method has environmental advantages, and the resulting cathode lead and anode mud can be further processed to extract precious metals. A process for extracting copper, lead, and precious metals using vacuum distillation, patent number CN119194087A, discloses a method for extracting copper, lead, and precious metals using vacuum distillation. This process can accurately separate metal vapors with different boiling points, avoid cross-contamination between metals, and improve the purity of the metals. These technologies demonstrate the various applications of lead in precious metal smelting, including its use as a precious metal collector, in hydrometallurgical and pyrometallurgical processes, and in advanced processes such as electrolytic refining and vacuum distillation. These technologies allow for more efficient extraction and recovery of precious metals while reducing environmental pollution. However, the presence of lead in alloy ingots during precious metal smelting often directly affects the extraction and separation of precious metals; therefore, how to quickly remove lead without affecting the recovery of precious metals is a research direction. Summary of the Invention

[0004] The purpose of this invention is to provide a method for adsorbing lead from precious metal alloy ingots. An adsorbent is used to capture lead in the precious metal alloy ingots, thereby fixing the lead in the solid and preventing the formation of gaseous volatilization that would cause environmental pollution. The lead content in the precious metal alloy ingots is found to be less than 0.005%.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for adsorbing lead from molten noble metal alloy, comprising the following steps:

[0006] Step (1) Melting of precious metal materials: Add low-content precious metal materials to a fluxing agent, mix evenly, place in a crucible of an induction furnace, heat until the material becomes molten, keep warm for 5-30 minutes, and pour off the surface slag to expose the metal surface;

[0007] Step (2) Lead capture by adsorbent: Keep the molten liquid at a slight boil, add the adsorbent and it floats on the surface. Stir the adsorbent to fully capture the lead in the molten liquid. After the adsorbent turns yellow, pour it into the medium frequency furnace until the surface is level with the furnace opening. Use an iron hook to remove the surface adsorbent. Repeat 2-5 times depending on the lead content.

[0008] Step (3) Pouring and casting ingots: Slightly increase the temperature of the medium frequency furnace for 5-10 minutes, and quickly pour the melt into a preheated cast iron tank to remove moisture, so as to obtain a precious metal alloy ingot of appropriate size for the next step of wet recycling.

[0009] Furthermore, in step (1), the precious metal material includes precious metals and other metals, wherein the precious metals are one or more of palladium, platinum, rhodium, iridium, ruthenium, osmium, gold and silver, and the other metals are one or more of iron, copper, iron, lead, tin, antimony, etc.

[0010] Furthermore, in step (1), the co-solvent is one or more of sodium carbonate, borax, quartz sand, lime, and alumina, and the amount of co-solvent used is such that the mass ratio of the precious metal material to the co-solvent is 1:0.2-2, preferably 1:0.5-1.

[0011] Furthermore, in step (3), the stabilizer is one or more of polyvinylpyrrolidone, polyvinyl alcohol, polyacrylamide, and sodium polyacrylate, and the mass ratio of the amount added to the amount of ruthenium is 0.1~0.5:1.

[0012] Furthermore, in step (2), the adsorbent is one or more of borax, sodium carbonate, lime, cement, gypsum, and fluorite. The ratio of the amount of adsorbent added to the mass of lead in step (1) is 1-10:1. The specific number of adsorptions and time need to be determined based on the color change after the adsorbent captures lead. 2-5 times is sufficient, with each time lasting 15-30 minutes.

[0013] Furthermore, the intermediate frequency furnace is equipped with a temperature control device, which includes:

[0014] S1, Obtain the current temperature of the material to be heated in the intermediate frequency furnace;

[0015] S2, calculate the difference between the current temperature and the target temperature;

[0016] S3, based on the current temperature and the difference, match the data in the medium-frequency furnace historical database to obtain the first input electric power;

[0017] S4, adjust the first input power to obtain the second input power;

[0018] S5, control the power supply of the intermediate frequency furnace according to the second input power;

[0019] S6, repeat S1 to S5 until heating is complete.

[0020] Furthermore, step S4 includes:

[0021] Obtain the third input electrical power and actual temperature rise of the previous preset time period at the current moment;

[0022] Calculate the theoretical temperature rise corresponding to the third input electrical power;

[0023] Calculate the ratio of the theoretical temperature rise to the actual temperature rise;

[0024] Based on the ratio, the first input power is adjusted to obtain the second input power.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. A method for adsorbing lead from molten precious metal alloys is provided. This method can effectively remove lead by simply adding this step to the production process. It is simple to operate, has significant effects, stable batch production, and is environmentally friendly.

[0027] 2. To achieve the goal of fixing lead in a solid, without causing environmental pollution by volatilizing gas, the lead content in the precious metal alloy ingot is less than 0.005% as tested. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0030] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] A method for adsorbing lead from molten precious metal alloys includes the following steps:

[0032] Step (1) Melting of precious metal materials: Add low-content precious metal materials to a fluxing agent, mix evenly, place in a crucible of an induction furnace, heat until the material becomes molten, keep warm for 5-30 minutes, and pour off the surface slag to expose the metal surface;

[0033] Step (2) Lead capture by adsorbent: Keep the molten liquid at a slight boil, add the adsorbent and it floats on the surface. Stir the adsorbent to fully capture the lead in the molten liquid. After the adsorbent turns yellow, pour it into the medium frequency furnace until the surface is level with the furnace opening. Use an iron hook to remove the surface adsorbent. Repeat 2-5 times depending on the lead content.

[0034] Step (3) Pouring and casting ingots: Slightly increase the temperature of the medium frequency furnace for 5-10 minutes, and quickly pour the melt into a preheated cast iron tank to remove moisture, so as to obtain a precious metal alloy ingot of appropriate size for the next step of wet recycling.

[0035] The intermediate frequency furnace is equipped with a temperature control device, which includes:

[0036] S1, Obtain the current temperature of the material to be heated in the intermediate frequency furnace;

[0037] S2, calculate the difference between the current temperature and the target temperature;

[0038] S3, based on the current temperature and the difference, match the data in the medium-frequency furnace historical database to obtain the first input electric power;

[0039] S4, adjust the first input power to obtain the second input power;

[0040] S5, control the power supply of the intermediate frequency furnace according to the second input power;

[0041] S6, repeat S1 to S5 until heating is complete.

[0042] Step S4 includes:

[0043] Obtain the third input electrical power and actual temperature rise of the previous preset time period at the current moment;

[0044] Calculate the theoretical temperature rise corresponding to the third input electrical power;

[0045] Calculate the ratio of the theoretical temperature rise to the actual temperature rise;

[0046] Based on the ratio, the first input power is adjusted to obtain the second input power.

[0047] By combining medium-frequency furnace heating with historical big data, the optimal heating strategy can be obtained through historical data, thereby ensuring the automation and intelligence of the heating process, which has the advantages of improving heating quality and reducing energy consumption.

[0048] Example 1

[0049] Mix 20 kg of precious metal material (palladium 5.32%, platinum 3.31%, gold 1.56%, silver 24.39%, iron 38.19%, lead 11.35%) with one or more of the following: sodium carbonate, borax, quartz sand, lime, and alumina. Place the mixture in a silicon carbide crucible in a medium-frequency furnace. After heating for 2 hours, the material will become molten. Hold the mixture at this temperature for 30 minutes, then remove the surface scum to expose the metal surface. Maintain the molten liquid at a gentle boil, and slowly add 2.27 kg of one or more of the following: lime, cement, gypsum, and fluorite. The adsorbent floats... On the surface, the adsorbent is stirred to fully capture lead in the molten metal. After the adsorbent turns yellow, it is poured into the induction furnace until the surface is level with the furnace opening. The adsorbent on the surface is removed using an iron hook. 2.27 kg of adsorbent is added repeatedly three times, and the color of the adsorbent remains basically unchanged. The temperature of the induction furnace is slightly increased for 5-10 minutes, and the melt is quickly poured into a preheated cast iron tank to remove moisture, resulting in four precious metal alloy ingots, totaling 12.516 kg. The contents were tested and found to be 8.49% palladium, 5.28% platinum, 2.49% gold, 38.96% silver, 42.14% iron, and 0.003% lead.

[0050] Example 2

[0051] 30 kg of precious metal material (85.21% silver, 13.55% lead) was mixed evenly with 6 kg of one or more of sodium carbonate, borax, quartz sand, lime, and alumina. The mixture was then placed in a silicon carbide crucible in an induction furnace. After heating for 40 minutes, the material became molten. The mixture was held at this temperature for 5 minutes, and the surface scum was removed to expose the metal surface. The molten liquid was kept at a gentle boil, and 2 kg of one or more of lime, cement, gypsum, and fluorite was slowly added. The adsorbent floated on the surface. The adsorbent was stirred to ensure it fully captured the lead in the molten liquid. After the adsorbent turned yellow, it was poured into the induction furnace until the surface was level with the furnace opening. The surface adsorbent was removed using an iron hook. The adsorbent was added repeatedly at a rate of 2 kg four times. The color of the adsorbent remained largely unchanged. The temperature of the induction furnace was slightly increased for 5 minutes, and the melt was quickly poured into a preheated and dehydrated cast iron trough. Two silver ingots were obtained, totaling 25.526 kg. The silver content was 99.991%, and the lead content was 0.002%.

[0052] Example 3

[0053] Mix 15 kg of precious metal material (10.11% rhodium, 40.24% platinum, 24.26% lead) with 18 kg of one or more of sodium carbonate, borax, quartz sand, lime, and alumina. Place the mixture into a silicon carbide crucible in a medium-frequency furnace. After heating for 2.5 hours, the material will become molten. Hold the mixture at this temperature for 20 minutes, then remove the surface scum to expose the metal surface. Maintain the molten liquid at a gentle boil, and slowly add 4 kg of one or more of lime, cement, gypsum, and fluorite to adsorb the molten metal. The adsorbent floats on the surface. Stirring the adsorbent allows it to fully capture lead in the molten metal. After the adsorbent turns yellow, pour it into the induction furnace until the surface is level with the furnace opening. Use an iron hook to remove the surface adsorbent. Repeat this process of adding 4 kg of adsorbent 5 times. The color of the adsorbent remains basically unchanged. Slightly increase the temperature of the induction furnace for 10 minutes, and quickly pour the melt into a preheated cast iron tank to remove moisture. This produces two precious metal alloy ingots, totaling 8.634 kg. Testing shows that the ingots contain 17.48% rhodium, 69.88% platinum, and 0.002% lead.

[0054] Example 4

[0055] Mix 25 kg of precious metal material (palladium 3.16%, platinum 42.15%, rhodium 1.26%, iridium 2.21%, ruthenium 13.11%, gold 1.55%, silver 0.33%, iron 25.37%, lead 8.35%) with 15 kg of sodium carbonate, borax, quartz sand, lime, or alumina. Place the mixture in a silicon carbide crucible in a medium-frequency furnace. Heat to molten state for 2 hours, then maintain the temperature for 20 minutes. Remove surface scum to expose the metal surface. While maintaining a gentle boil, slowly add 2.1 kg of lime, cement, gypsum, or fluorite to adsorb the molten metal. The adsorbent floats on the surface. Stirring the adsorbent allows it to fully capture lead in the molten metal. Once the adsorbent turns yellow, pour it into the induction furnace until the surface is level with the furnace opening. Use an iron hook to remove the surface adsorbent. Repeat this process three times, adding 2.1 kg of adsorbent each time, until the color remains largely unchanged. Slightly increase the temperature of the induction furnace for 10 minutes, then quickly pour the melt into a preheated cast iron bath to remove moisture. This yields four precious metal alloy ingots, totaling 19.672 kg. Testing revealed the following composition: palladium 4.0%, platinum 53.53%, rhodium 1.60%, iridium 2.81%, ruthenium 16.64%, gold 1.97%, silver 0.4%, iron 14.66%, and lead 0.004%.

[0056] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

[0057] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and incorporate common knowledge or customary techniques in the art disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of this application is indicated by the claims.

Claims

1. A method for adsorbing lead from molten noble metal alloy, characterized in that: Includes the following steps: Step (1) Melting of precious metal materials: Add low-content precious metal materials to a fluxing agent, mix evenly, place in a crucible of an induction furnace, heat until the material becomes molten, keep warm for 5-30 minutes, and pour off the surface slag to expose the metal surface; Step (2) Lead capture by adsorbent: Keep the molten liquid at a slight boil, add the adsorbent and it floats on the surface. Stir the adsorbent to fully capture the lead in the molten liquid. After the adsorbent turns yellow, pour it into the medium frequency furnace until the surface is level with the furnace opening. Use an iron hook to remove the surface adsorbent. Repeat 2-5 times depending on the lead content. Step (3) Pouring and casting ingots: Slightly increase the temperature of the medium frequency furnace for 5-10 minutes, and quickly pour the melt into a preheated cast iron tank to remove moisture, so as to obtain a precious metal alloy ingot of appropriate size for the next step of wet recycling.

2. The method for adsorbing lead from molten noble metal alloy according to claim 1, characterized in that: In step (1), the precious metal material includes precious metals and other metals, wherein the precious metals are one or more of palladium, platinum, rhodium, iridium, ruthenium, osmium, gold and silver, and the other metals are one or more of iron, copper, lead, tin, antimony, etc.

3. The method for adsorbing lead from molten noble metal alloy according to claim 1, characterized in that: In step (1), the co-solvent is one or more of sodium carbonate, borax, quartz sand, lime, and alumina. The amount of co-solvent used is such that the mass ratio of the precious metal material to the co-solvent is 1:0.2-2, preferably 1:0.5-1.

4. The method for adsorbing lead from molten noble metal alloy according to claim 1, characterized in that: In step (2), the adsorbent is one or more of borax, sodium carbonate, lime, cement, gypsum, and fluorite. The ratio of the amount of adsorbent added to the mass of lead in step (1) is 1-10:

1. The specific number of adsorptions and time need to be determined based on the color change after the adsorbent captures lead. 2-5 times is sufficient, with each time lasting 15-30 minutes.

5. The method for adsorbing lead from molten noble metal alloy according to claim 1, characterized in that: The intermediate frequency furnace is equipped with a temperature control device, which includes: S1, Obtain the current temperature of the material to be heated in the intermediate frequency furnace; S2, calculate the difference between the current temperature and the target temperature; S3, based on the current temperature and the difference, match the data in the medium-frequency furnace historical database to obtain the first input electric power; S4, adjust the first input power to obtain the second input power; S5, control the power supply of the intermediate frequency furnace according to the second input power; S6, repeat S1 to S5 until heating is complete.

6. The method for adsorbing lead from molten noble metal alloy according to claim 5, characterized in that: Step S4 includes: Obtain the third input electrical power and actual temperature rise of the previous preset time period at the current moment; Calculate the theoretical temperature rise corresponding to the third input electrical power; Calculate the ratio of the theoretical temperature rise to the actual temperature rise; Based on the ratio, the first input power is adjusted to obtain the second input power.