Slag-forming agents, purification methods, and silver anode plates for smelting crude silver powder in medium-frequency furnaces

Abstract

This invention relates to the field of precious metal hydrometallurgical technology, specifically a slag-forming agent and its application method for smelting crude silver powder in a medium-frequency furnace. The slag-forming agent, composed of rice husks, industrial potassium chloride, reducing iron powder, and crushed glass, is added in a specific manner, at a specific dosage, and at a medium-frequency furnace temperature to further purify the crude silver powder, meeting the production requirements of silver electrolytic refining. It effectively removes inclusions such as Te and Sb, as well as oxygen gases, from the molten crude silver, achieving purification and providing conditions for the production of high-quality silver anode plates through silver electrolytic refining. This invention solves problems such as the difficulty of blowing crude silver powder during medium-frequency furnace smelting, the difficulty of impurity removal, easy damage to the furnace lining, and poor deoxidation effect of the molten crude silver. The method provided by this invention has a fast reaction speed, wide applicability of raw materials, good impurity removal effect, and low energy consumption, and has good industrial application value.

Description

Technical Field

[0001] This invention relates to the field of precious metal smelting technology, and in particular to a slag-forming agent, purification method, and silver anode plate for smelting high tellurium crude silver powder in a medium-frequency furnace to further purify the crude silver powder. Technical Background

[0002] Copper anode mud is not only an important raw material for extracting precious metals such as gold and silver, but also contains rare metals such as selenium, tellurium, antimony, and bismuth as secondary byproducts, resulting in a mixed composition. In order to efficiently enrich and purify silver in the anode mud, technicians often remove harmful impurities in advance to prepare crude silver powder, which is then refined through electrolytic processes to obtain high-purity silver products.

[0003] Due to the small production scale, fast melting and casting speed, and simple operation, most of the precious metals industry uses medium-frequency furnaces for the melting and casting of crude silver powder, without realizing the requirements of open-type medium-frequency furnaces for the quality of crude silver powder in the production process.

[0004] First, the impurity removal effect is poor. The wet process of copper anode mud can produce crude silver powder with Ag content of over 98%, but it still contains a small amount of impurities such as Cu, Te, and Pb. The literature "Production Practice to Improve the Quality of Crude Silver Anode Plates" introduces a medium-frequency furnace method for removing high-melting-point harmful impurities Cu and Fe. However, for "stubborn" harmful elements such as Te and Sb that affect the quality of high-purity silver, it is difficult to remove them by medium-frequency furnace. Therefore, in order to avoid excessive tellurium and antimony in silver ingots, the industry usually uses a lengthy wet separation process or relies on converters, Kaldor furnaces, etc. for blowing to reduce the tellurium and antimony content in crude silver anode plates. This results in low production efficiency and extreme energy waste.

[0005] Secondly, the deoxidation effect is poor. Silver has a melting point of 961.8℃. Once silver begins to melt, its oxygen-dissolving capacity increases dramatically, absorbing approximately 21 times its own volume in oxygen. Therefore, deoxidation treatment is necessary during the smelting process. The literature "Research and Production Practice on the Selection of Deoxidizing Agents for Silver Ingot Casting" provides a deoxidizer, but it is limited to surface deoxidation after silver melts, making deep deoxidation difficult. This results in unstable content of easily oxidized elements in the silver anode plate, and a high content of inclusions and gases.

[0006] Third, the furnace lining has a short service life; the lining of the medium-frequency furnace used for casting crude silver powder is an acidic lining with high-purity graphite or silicon dioxide as the main components, while the crude silver powder extracted by wet method contains a large amount of alkaline substances, which causes great wear and tear on the furnace lining.

[0007] Therefore, developing a slag-forming agent suitable for improving the quality of silver anode plates when smelting coarse silver powder in an intermediate frequency furnace is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a slag-forming agent for medium-frequency furnace smelting of coarse silver powder, which can better target coarse silver powder for medium-frequency furnace smelting, efficiently and conveniently remove impurities from the coarse silver powder, and improve the quality of silver anode plates.

[0009] To achieve the above objectives, the technical solution of this disclosure is as follows: a slag-forming agent for smelting crude silver powder in a medium-frequency furnace, the slag-forming agent for smelting crude silver powder in a medium-frequency furnace includes rice husks, industrial potassium chloride, reducing iron powder and crushed glass;

[0010] The amount of rice husk added is 8-12 wt% of the weight of the crude silver powder to be treated;

[0011] The amount of industrial potassium chloride added is 1.2-1.5 times the impurity content in the crude silver powder to be treated;

[0012] The reducing iron powder is added at an amount of 2-4% of the weight of the crude silver powder to be treated;

[0013] The amount of broken glass added is 0.1-0.5% of the weight of the coarse silver powder to be processed.

[0014] Furthermore, the content of the industrial potassium chloride should be ≥90%, and the particle size should be 0.5-3mm.

[0015] Furthermore, the particle size of the reduced iron powder is 50-200 mesh.

[0016] Another object of the present invention is to provide a purification method for the slag-forming agent used in the above-mentioned medium-frequency furnace smelting of crude silver powder, the method specifically including the following steps:

[0017] S1) Determine the amount of each component of the slag-forming agent to be added based on the weight of the coarse silver powder to be processed;

[0018] The slag-forming agent for smelting crude silver powder in the medium-frequency furnace includes rice husks, industrial potassium chloride, reducing iron powder, and broken glass.

[0019] The amount of rice husk added is 8-12 wt% of the weight of the crude silver powder to be treated;

[0020] The amount of industrial potassium chloride added is 1.2-1.5 times the impurity content in the crude silver powder to be treated;

[0021] The reducing iron powder is added at an amount of 2-4% of the weight of the crude silver powder to be treated;

[0022] The amount of broken glass added is 0.1-0.5% of the weight of the coarse silver powder to be processed.

[0023] S2) First, mix the slag-forming agent with the coarse silver powder to be treated evenly for pretreatment;

[0024] S3) The pretreated crude silver powder from S2) and the remaining components are added to the medium-frequency furnace according to the preset addition method, and combined with the corresponding process treatment, the crude silver powder purification process is completed and cast into a silver anode plate.

[0025] More preferably, the content of the industrial potassium chloride should be ≥90% and the particle size should be 0.5-3mm.

[0026] The reducing iron powder has a particle size of 50-200 mesh.

[0027] Furthermore, the specific process of S2) is as follows:

[0028] Mix the rice husks with coarse silver powder, stir thoroughly, heat to 120-160℃, and bake for 4-6 hours.

[0029] Furthermore, the specific process of S3) is as follows:

[0030] S3.1) Divide the industrial potassium chloride into several equal parts. Now spread a layer of industrial potassium chloride on the bottom of the furnace, and then spread a layer of coarse silver powder of a certain thickness. Add one part of industrial salt for each addition of coarse silver powder until all the industrial salt is added. Then start heating.

[0031] S3.2) When the temperature reaches 800-850℃, hold the temperature for 8-12 minutes, then add the reducing iron powder all at once and continue heating;

[0032] S3.3) After the coarse silver powder in the furnace has completely melted and the temperature has reached 1050-1100℃, add crushed glass, stir slowly for 3-5 minutes, remove the floating material on the top layer, and cast it into a silver anode plate.

[0033] Furthermore, the thickness of the coarse silver powder in S3.1) is 10-20cm.

[0034] Furthermore, the silver anode plate obtained by the method has a purity of not less than 99.980%, a Te content of not more than 0.0053%, a Sb content of not more than 0.0006%, and an oxygen content of less than 0.0012%.

[0035] A silver anode plate was prepared using the purification method described above.

[0036] Compared with the prior art, the advantages and positive effects of the present invention are:

[0037] (1) A slag-forming agent for smelting crude silver powder in a medium frequency furnace can effectively remove inclusions such as Te and Sb and oxygen gases from the crude silver molten liquid, thereby achieving purification and providing conditions for the production of high-quality silver anode plates by silver electrolytic refining.

[0038] (2) It solves the problems of difficult blowing of crude silver powder in medium frequency furnace, difficulty in removing impurities, easy damage to furnace lining, and poor deoxidation effect of crude silver molten liquid.

[0039] (3) The method provided by the present invention has a fast reaction speed, wide applicability of raw materials, good impurity removal effect, and low energy consumption, and has good industrial promotion value. Attached Figure Description

[0040] Figure 1 This is a flowchart of a purification method for slag-forming agents in the smelting of crude silver powder in a medium-frequency furnace according to the present invention. Detailed Implementation

[0041] The present invention will be further described in detail below through embodiments, but the scope of the present invention is not limited to these embodiments.

[0042] like Figure 1 As shown, this invention discloses a purification method for slag-forming agents used in the smelting of crude silver powder in a medium-frequency furnace. The method specifically includes the following steps:

[0043] S1) Determine the amount of each component of the slag-forming agent to be added based on the weight of the coarse silver powder to be processed;

[0044] S2) First, mix the rice husks and coarse silver powder in the slag-forming agent, stir thoroughly, heat to 120-160℃, and bake for 4-6 hours.

[0045] S3) The pretreated crude silver powder from S2) and the remaining components are added to the medium-frequency furnace according to the preset addition method, and combined with the corresponding process treatment, the crude silver powder purification process is completed.

[0046] The specific process is as follows:

[0047] S3.1) Divide the industrial potassium chloride into several equal parts. Now spread a layer of industrial potassium chloride on the bottom of the furnace, and then spread a layer of coarse silver powder of a certain thickness. Add one part of industrial salt for each addition of coarse silver powder until all the industrial salt is added. Then start heating.

[0048] S3.2) When the temperature reaches 800-850℃, hold the temperature for 8-12 minutes, then add the reducing iron powder all at once and continue heating;

[0049] S3.3) After the coarse silver powder in the furnace has completely melted and the temperature has reached 1050-1100℃, add crushed glass, stir slowly for 3-5 minutes, remove the floating material on the top layer, and cast it into a silver anode plate.

[0050] Example 1

[0051] Add 10% by weight of rice husk to coarse silver powder 1 (chemical composition shown in Table 1) and mix thoroughly. Bake at 130℃ for 6 hours for later use. Weigh industrial potassium chloride at 1.5 times the mass of impurities and divide it into 5 equal parts. Add one part of industrial potassium chloride to the bottom of the preheated medium-frequency furnace. Then add the mixed coarse silver powder until the material layer reaches 20cm. Add another part of industrial potassium chloride and add another 20cm of coarse silver powder. Repeat the operation until all industrial potassium chloride is added. Fill the medium-frequency furnace chamber with coarse silver powder and heat to 800℃. Hold the temperature for 10 minutes. Add 4% of 150-mesh reducing iron powder at once. After raising the temperature to 1100℃, add 0.4% of crushed glass and stir slowly for 5 minutes. Remove the floating material on the top layer and cast it into a silver anode plate.

[0052] Example 2

[0053] Add 8% by weight of rice husk to coarse silver powder 2 (chemical composition shown in Table 2) and mix thoroughly. Bake at 140℃ for 4 hours for later use. Weigh industrial potassium chloride at 1.3 times the mass of impurities and divide it into 3 equal parts. Add one part of industrial potassium chloride to the bottom of the preheated medium-frequency furnace. Then add the mixed coarse silver powder until the material layer reaches 10cm. Add another part of industrial potassium chloride and add another 10cm of coarse silver powder. Repeat the operation until all industrial potassium chloride is added. Fill the medium-frequency furnace chamber with coarse silver powder and heat to 850℃. Hold the temperature for 10min. Add 3% of 150-mesh reducing iron powder at once. After raising the temperature to 1050℃, add 0.2% of crushed glass and stir slowly for 3min. Remove the floating material on the top layer and cast it into a silver anode plate.

[0054] (Comparative Example)

[0055] The applicant of this invention conducted industrial production tests on crude silver powder with the same chemical composition under the same temperature environment, using two sets of medium-frequency furnaces for smelting crude silver powder: one with a smelting method without slag-forming agent and the other with a smelting method with slag-forming agent. Through sampling and analysis, the following sets of test data were obtained.

[0056] Table 1: Chemical composition (%) of silver anode plates

[0057]

[0058] Table 2: Oxidation Thickness of Crucible in Medium Frequency Furnace (mm)

[0059] name Oxidation thickness of crucible wall Smelting method without slagging agent 15.3mm Smelting method with slagging agent 4.2mm

[0060] Through comparative examples, the chemical composition and oxygen content of the silver anode plate were significantly reduced by using the fluxing smelting method. Low-melting-point impurities such as Te and Sb were effectively removed. At the same time, the oxidation degree of the medium-frequency furnace crucible was also effectively alleviated, thus improving the service life of the crucible.

[0061] The above provides a detailed description of the slag-forming agent, purification method, and silver anode plate for smelting crude silver powder in a medium-frequency furnace, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0062] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0063] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0064] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0065] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A slag-forming agent for smelting crude silver powder in a medium-frequency furnace, characterized in that, The slag-forming agent for smelting crude silver powder in the medium-frequency furnace includes rice husks, industrial potassium chloride, reducing iron powder, and broken glass. The amount of rice husk added is 8-12 wt% of the weight of the crude silver powder to be processed. The amount of industrial potassium chloride added is 1.2-1.5 times the impurity content in the crude silver powder to be treated; The reduced iron powder is added at an amount of 2-4% of the weight of the crude silver powder to be treated; The amount of broken glass added is 0.1-0.5% of the weight of the coarse silver powder to be processed.

2. The slag-forming agent for smelting crude silver powder in a medium-frequency furnace according to claim 1, characterized in that, The content of the industrial potassium chloride should be ≥90%, and the particle size should be 0.5-3mm.

3. The slag-forming agent for smelting crude silver powder in a medium-frequency furnace according to claim 1, characterized in that, The reducing iron powder has a particle size of 50-200 mesh.

4. A purification method using the slagging agent according to any one of claims 1-3, characterized in that, The method specifically includes the following steps: S1) Determine the amount of each component of the slagging agent to be added based on the weight of the coarse silver powder to be processed; S2) First, mix the rice husks in the slag-forming agent with the coarse silver powder to be treated evenly for pretreatment; S3) The pretreated crude silver powder from S2) and the remaining components are added to the medium-frequency furnace according to the preset addition method, and combined with the corresponding process treatment, the crude silver powder purification process is completed. The specific process is as follows: S3.1) Divide the industrial potassium chloride into several equal parts. First, spread a layer of industrial potassium chloride on the bottom of the furnace, then spread a layer of coarse silver powder of a certain thickness. Add one part of industrial salt for every part of coarse silver powder added, until all the industrial salt is added. Then start heating. S3.2) When the temperature reaches 800-850℃, hold the temperature for 8-12 minutes, then add the reducing iron powder all at once and continue heating; S3.3) After the coarse silver powder in the furnace has completely melted and the temperature has reached 1050-1100℃, add crushed glass, stir slowly for 3-5 minutes, remove the floating material on the top layer, and cast it into a silver anode plate.

5. The purification method according to claim 4, characterized in that, The specific process of S2 is as follows: Mix the rice husks with coarse silver powder, stir thoroughly, heat to 120-160℃, and bake for 4-6 hours.

6. The purification method according to claim 4, characterized in that, The thickness of the coarse silver powder in S3.1) is 10-20cm.

7. The purification method according to claim 4, characterized in that, The silver anode plate obtained by the method has a purity of not less than 99.980%, a Te content of not more than 0.0053%, a Sb content of not more than 0.0006%, and an oxygen content of less than 0.0012%.

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