Tin hard head liquation refining process

Abstract

The invention belongs to the technical field of metallurgical processes, and particularly relates to a tin hard head liquation refining process which comprises the following steps: step 1, adding solid tin hard heads into lead alloy liquid in batches, stirring, controlling the temperature of the lead alloy liquid to be 610-680 DEG C during stirring, stopping stirring after the tin hard heads are granular or powdery, and fishing out dross to obtain crude tin liquid; step 2, performing condensation to remove iron and arsenic; and step 3, removing iron and copper after arsenic is qualified. According to the method, the metal high-temperature liquation technology is adopted, the crude tin is separated out from the tin hard head, the process that in the traditional process, after crushing, the tin slag is matched for secondary furnace feeding is replaced, and the problems that in the traditional process, melting is difficult, the period is long, and the tin yield is low are solved.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical process technology, specifically relating to a tin hard-tip melting and refining process. Background Technology

[0002] During the smelting process of tin slag, iron elements enter the crude tin in liquid form. In the refining and copper removal process, a large amount of tin hard ends are produced through melting and precipitation. Tin hard ends generally contain more than 45% tin and a small amount of impurity elements.

[0003] The existing technology for processing tin hard ends generally adopts a process of crushing and then smelting with tin slag in a furnace (Liu Bin. Smelting of segregated tin slag with lead oxide ore in a blast furnace [J]. China Nonferrous Metallurgy, 1997(4):10-13.). Due to the high melting point of the hard ends, they are difficult to melt. After entering the furnace, part of them are oxidized and enter the dust collection device, and part of them are re-entered into the crude tin. The overall process has problems such as long cycle and low direct tin recovery rate. Summary of the Invention

[0004] To address the problems of long tin hard-tip melting processes and low tin yield in existing technologies, this invention provides a tin hard-tip melting and refining process. This process is simple to operate, environmentally friendly, and highly efficient. It can quickly precipitate coarse tin from the tin hard-tip and refine it to remove impurities, shortening the tin hard-tip melting time while improving the tin yield.

[0005] To achieve the above objectives, the present invention is implemented as follows: A tin hard-tip melting and refining process includes the following steps: Step 1: Add solid tin hardheads to the lead alloy liquid in batches and stir. During this process, control the temperature of the lead alloy liquid at 610-680℃. After the tin hardheads become granular or powdery, stop stirring, remove the dross, and obtain crude tin liquid. In this step, the solid tin hard tip can be added to the lead alloy liquid in 8-10 batches; the weight ratio of the solid tin hard tip to the lead alloy can be 0.5-2; the preferred temperature of the lead alloy liquid is 650-680℃.

[0006] When solid tin tips are added to liquid lead alloy, they dissolve through stirring. The low-melting-point tin and lead in the tin tips dissolve into the liquid, while the high-melting-point iron and copper float to the surface to form scum.

[0007] Step 2: Condensation to remove iron and arsenic. Before condensation to remove iron and arsenic, the crude tin solution contains more than 20% tin. The operation for condensation to remove iron and arsenic is as follows: The temperature of the crude tin solution is controlled at 280℃-300℃, stirred and a slagging agent is added. Dross forms, and stirring continues until the reaction is complete. At this point, the crude tin solution contains Fe≤0.2% and As≤0.5%, completing the condensation operation. Sawdust can be used as the slagging agent in this step, with 10-20 kg of sawdust added per 40 tons of crude tin solution. The slagging reaction ends when no more dross forms in this step.

[0008] Step 3: After iron and arsenic removal, copper removal is performed. The copper removal process is as follows: The crude tin liquid is heated to 250°C, stirred, and a slagging agent is added to form slag. Stirring continues until the reaction is complete. Sulfur is selected as the slagging agent in this step, with a sulfur-to-copper mass ratio of 0.5:1. During slagging, the crude tin liquid is stirred to form a vortex. Sulfur is added to the vortex, but not too quickly or in excessive amounts, otherwise the sulfur will burn on the surface of the crude tin liquid, reducing its utilization rate and affecting the copper removal efficiency. After the sulfur is added, stirring continues to allow the sulfur to fully react with the copper in the crude tin liquid. The slag on the surface of the crude tin liquid gradually changes from a yellowish-gray viscous substance to a black powder. When Cu ≤ 0.1%, the reaction is considered complete. Stirring is stopped, the slag is skimmed off, and the tin hardening refining process is finished.

[0009] The principle of the tin hardhead melting and refining process of this invention is as follows: solid tin hardheads are added to molten lead alloy liquid, and the temperature of the lead alloy liquid is controlled so that the tin hardheads melt and precipitate at high temperature under the stirring of a stirrer. At room temperature, tin hardheads mainly exist in the form of tin-iron-arsenic alloy. When the tin hardheads are heated, a liquid phase (tin liquid with an iron content of less than 10%) will separate out. Through melting and precipitation, liquid tin is formed, and the heavier portion of the tin hardheads can be separated out. The remaining solid phase of the tin hardheads continues to heat up, further precipitating a liquid phase with a higher iron content. During the tin hardhead melting and refining process, if the melting temperature of the tin hardheads is too high, the melting rate of the tin hardheads will accelerate, but it will also increase the solubility of impurities in the resulting crude tin liquid, making it difficult to completely separate subsequent impurities such as iron and arsenic. Excessively high tin hardhead melting temperatures may also accelerate tin oxidation loss and reduce tin recovery rate. When the melting temperature of the tin hardener is too low, the tin does not melt completely, resulting in some tin failing to separate from the hardener and remaining in the solid tin hardener, thus reducing the tin recovery rate. At low temperatures, the fluidity of the molten tin deteriorates, hindering its outflow and collection. By precisely controlling the melting temperature of the tin hardener (i.e., the temperature of the lead alloy liquid), the tin recovery rate can be improved while reducing the introduction of impurities. In this invention, the temperature control of the lead alloy liquid is a crucial step in the heating and melting method, directly affecting the tin recovery rate and purity. This invention, through the control of the lead alloy liquid temperature, can improve tin recovery efficiency, reduce resource waste, and simultaneously reduce the difficulty of subsequent refining.

[0010] The beneficial effects of this invention are as follows: 1. The process of this invention involves adding solid tin hard tips into molten lead alloy liquid and controlling the temperature of the lead alloy liquid at 610-680℃. This ensures that the tin in the tin hard tips melts more completely and does not increase the solubility of impurities, thus allowing for the direct and effective recovery of tin elements from the tin hard tips. 2. The process of this invention is green and efficient, which can effectively reduce tin loss and increase tin yield; 3. This invention significantly shortens the tin smelting cycle by more than 50%. Attached Figure Description

[0011] Figure 1 : Flowchart of the tin hard-tip melting and refining process of the present invention. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0013] The lead alloy volatiles used in the examples contain 96% lead and 3% tin.

[0014] The elemental content of the tin hard tip in the embodiments is shown in Table 1.

[0015] Table 1. Element content in tin hard tips Example 1 like Figure 1 As shown, a tin hard-tip melting and refining process includes: 1. With the mixture stirred in a mixer, add the solid tin hardheads in 8-10 batches to the refining pot containing molten lead alloy, and stir for 1 hour, controlling the temperature of the molten lead alloy within a certain range during this period. Once the tin hardheads are in the form of small particles or powder, stop stirring and skim off the scum; the crude tin liquid is obtained.

[0016] 2. Take a sample of the crude tin solution for testing. If the tin content in the crude tin solution is above 20%, remove the surface slag and then perform condensation to remove iron and arsenic. The condensation to remove iron and arsenic operation is as follows: control the temperature of the crude tin solution at 280℃-300℃, stir, and add sawdust to promote the coagulation and floating of iron and arsenic grains. Stir until no more slag is precipitated. At this point, the Fe content in the crude tin solution is ≤0.2% and the As content is ≤0.5%, completing the condensation operation.

[0017] 3. After removing iron and arsenic, remove copper. The copper removal process is as follows: Heat the crude tin liquid to 250℃, stir the crude tin liquid to form a vortex, and slowly add sulfur to the vortex. The mass ratio of sulfur to copper is 0.5:1. After the sulfur is added, continue stirring to allow the sulfur to fully react with the copper in the crude tin liquid. When the scum floating on the surface of the crude tin liquid gradually changes from a yellowish-gray viscous substance to a black powder, and Cu ≤ 0.1%, the reaction can be considered complete. Stop stirring, skim off the scum, and the tin hardening refining is complete, yielding a tin alloy. From July 21, 2025 to August 4, 2025, three batches of tin hardening refining were carried out using refining pot #11. Details of the material input, lead alloy liquid temperature, and refining time for each batch are shown in Table 2. The elemental content of the crude tin liquid in step 2 of each batch is shown in Table 3. The elemental content of the tin alloy obtained in step 3 of each batch is shown in Table 4. The three batches produced 87.16 tons of tin alloy, consuming approximately 9360 m³ of natural gas and approximately 6864 kWh of electricity. A total of 23 tons of slag was produced from the three batches, with the following contents: Sn 11.06%, Pb 58.45%, Cu 0.48%, Sb 0.078%, As 2.38%, Bi 0.17%, and Fe 19.1%. The metal balance table for the processed tin hardening is shown in Table 5.

[0018] Table 2. Relevant parameters for tin hardening refining Table 3. Element content in crude tin solution Table 4. Element content of tin alloys Table 5. Metal Balance Table for Processing Tin Hard Tips The results above show that when the temperature of the lead alloy melt is controlled at 650-680℃, the tin recovery rate is higher.

[0019] Comparative Example 1 The existing technology (Liu Bin. Smelting of segregated tin slag with lead oxide ore in a blast furnace [J]. China Nonferrous Metallurgy, 1997(4):10-13.) uses a 1.2m 2 A blast furnace is used to process mixed lead-tin ore and high-tin hard ends in the tin smelting process. Production is carried out using lead ore, low-calcium slag, low coke ratio, and small-batch feeding. The material composition and balance are as follows: Table 6. Material Composition and Balance As can be seen from Table 2, the direct tin recovery rate of the traditional process is only 48.20%, while the direct tin recovery rate of the present invention can reach 95.14%.

[0020] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention 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 the present invention.

Claims

1. A tin hard-tip melting and refining process, characterized in that, include: Step 1: Add solid tin hardheads to the lead alloy liquid in batches and stir. During this process, control the temperature of the lead alloy liquid at 610-680℃. After the tin hardheads become granular or powdery, stop stirring, remove the dross, and obtain crude tin liquid. Step 2: Condensation to remove iron and arsenic; Step 3: After removing iron and arsenic, remove copper.

2. The tin hard-tip melting and refining process according to claim 1, characterized in that, In step 1, the temperature of the lead alloy liquid is controlled at 650-680℃.

3. The tin hard-tip melting and refining process according to claim 1, characterized in that, Before step 2, when condensation is performed to remove iron and arsenic, the crude tin solution contains more than 20% tin.

4. The tin hard-tip melting and refining process according to claim 1, characterized in that, In step 2, the condensation removal of iron and arsenic is carried out as follows: the temperature of the crude tin liquid is controlled at 280℃-300℃, stirred and slag-forming agent is added, slag is formed, and stirring is continued until the reaction is completed. The crude tin liquid obtained contains Fe≤0.2% and As≤0.5%, and the condensation operation is completed.

5. The tin hard-tip melting and refining process according to claim 4, characterized in that, Sawdust is used as the slag-forming agent in step 2.

6. The tin hard-tip melting and refining process according to claim 1, characterized in that, In step 3, the copper removal operation is as follows: the crude tin liquid is heated to 250°C, stirred and slag-forming agent is added to form slag, and stirred until the reaction is completed.

7. The tin hard-tip melting and refining process according to claim 6, characterized in that, In step 3, sulfur is selected as the slag-forming agent, and the mass ratio of sulfur to copper is 0.5:

1.

8. The tin hard-tip melting and refining process according to claim 6, characterized in that, In step 3, during slag formation, the crude tin liquid is stirred to form a vortex. Sulfur is added to the vortex, and stirring continues after the sulfur is added. The slag on the surface of the crude tin liquid gradually changes from a yellowish-gray viscous substance to a black powder. When Cu ≤ 0.1%, the reaction is considered complete.

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