Method for recovering valuable metals from tin dross by vacuum carbothermic reduction

Abstract

The present application relates to a kind of tin ash vacuum carbothermic reduction recycling valuable metal method, belong to non-ferrous metallurgy technical field.The tin ash is mixed carbon powder according to metal amount and carbon ratio 2~4:1, under the condition of temperature 900~1200 ℃, pressure 1~20Pa, time 1~3h, vacuum carbothermic reduction-directional condensation is carried out, finally, crude tin I is obtained in evaporation zone;While the lead-zinc mixed steam entering gas phase is condensed to obtain crude lead I by lead liquid trap, and then refined zinc is obtained by zinc liquid trap;The crude tin I obtained is evaporated I by vacuum to obtain refined tin and crude lead II;The crude lead I obtained and the crude lead II obtained are evaporated II by vacuum to obtain crude tin II and refined lead, and crude tin II returns the process of evaporation I by vacuum.This method is simple, easy to operate, and the required equipment is simple, low in cost, high in universality of raw material, good in working environment, and process is safe and controllable.

Description

Technical Field

[0001] This invention relates to a method for recovering valuable metals from tin ash by vacuum carbothermic reduction, belonging to the field of non-ferrous metal pyrometallurgical technology. Background Technology

[0002] Tin ash has a wide range of sources, including waste slag (tin oxide) from tin smelting, fumes from soldering (wave soldering) in the electronics industry, tin-containing friction waste shavings from steel mills, friction material factories, or auto repair shops, waste fluxes generated during ceramic manufacturing, and waste tin foil.

[0003] The existing treatment process for tin ash is carbothermal reduction, with a comprehensive metal recovery rate of only about 50%. The treatment process suffers from problems such as large amounts of smoke and dust, low comprehensive metal recovery rate, and low product added value.

[0004] Patent CN 102618727 A discloses a method for extracting tin alloys from tin ash. This method utilizes organic chemical methods, employing oxidation, dehydration, decarboxylation, and decomposition reactions of organic matter in the tin ash to reduce the metal oxides of the tin alloy, and then removes impurities such as carbides from the tin ash, thereby extracting the tin alloy for regeneration and reuse. This method generates a large amount of waste liquid and is time-consuming. Patent CN 1962163A discloses a method for reducing and purifying solder wire from waste tin ash. This method utilizes a temperature gradient for repeated condensation and melting, including steps such as impurity removal, neutralization, smelting reduction, separation and purification, pressing and molding, drawing, and wrapping. This method has a long processing flow, complex steps, and is difficult to operate. Summary of the Invention

[0005] To address the problems and shortcomings of the existing technology, this invention provides a method for recovering valuable metals from tin ash through vacuum carbothermic reduction. This method is simple, easy to operate, requires simple equipment, is low-cost, uses widely applicable raw materials, provides a good working environment, and ensures a safe and controllable process. This invention is achieved through the following technical solution.

[0006] A method for recovering valuable metals from tin ash by vacuum carbothermic reduction includes the following steps:

[0007] Step 1, Vacuum carbothermal reduction - directional condensation:

[0008] Tin ash is mixed with carbon powder at a metal-to-carbon ratio of 2–4:1, and then subjected to vacuum carbothermic reduction-directional condensation at a temperature of 900–1200℃, a pressure of 1–20 Pa, and a time of 1–3 h. Crude tin I is finally obtained in the evaporation zone. Meanwhile, the lead-zinc mixed vapor entering the gas phase is first condensed in a lead liquid collector at 500–700℃ to obtain crude lead I, and then condensed in a zinc liquid collector at a temperature below 200℃ to obtain refined zinc.

[0009] Step 2: The crude tin I obtained in Step 1 is subjected to vacuum volatilization I to obtain refined tin and crude lead II;

[0010] Step 3: Vacuum volatilization process 2 is performed on crude lead I obtained in step 1 and crude lead II obtained in step 2 to obtain crude tin II and refined lead. Crude tin II is returned to the vacuum volatilization process 1.

[0011] In step 1, the percentage mass composition of tin ash is Sn 20-30%, Pb 50-60%, Zn 5%-15%, Sb 0.01-0.1%, Bi < 0.001%, and Cu < 0.001%.

[0012] The conditions for vacuum evaporation I in step 2 are: temperature 800-1100℃, pressure 1-100Pa, and time 1-2h.

[0013] The conditions for vacuum evaporation II in step 3 are: temperature 700-900℃, pressure 1-100Pa, and time 1-2h.

[0014] This invention can produce three products: refined tin, refined lead, and refined zinc. The tin content in refined tin is as high as 99.9% or more by mass, the lead content in refined lead is as high as 99.99% or more by mass, and the zinc content in refined zinc is as high as 99.9% or more by mass.

[0015] The metal recovery rates of tin, lead, and zinc in the tin ash of this invention are as high as 99.0-99.5%, 98.2-99.0%, and 99.1-99.6%, respectively.

[0016] The devices or traps whose structures are not specifically mentioned above are all existing devices and traps known in the art.

[0017] The beneficial effects of this invention are:

[0018] This method achieves comprehensive recovery of metal resources from tin ash, yielding refined tin, refined lead, and refined zinc. Compared to traditional processing methods, this method generates no waste, is safe and reliable throughout the process, is easy to operate, requires simple equipment, is low-cost, has high metal recovery efficiency, and operates in a friendly environment. Attached Figure Description

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

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1

[0022] like Figure 1As shown, the method for recovering valuable metals from tin ash by vacuum carbothermic reduction includes the following steps:

[0023] Step 1, Vacuum carbothermal reduction - directional condensation:

[0024] 5 kg of tin ash (specific composition as shown in Table 1) was mixed with carbon at a ratio of 2:1 (total mass of tin and zinc). Vacuum carbothermal reduction-directional condensation was carried out at 900℃, 1 Pa, and 1 h to obtain crude tin I in the evaporation zone. The lead-zinc mixed vapor entering the gas phase was first condensed in a lead liquid collector at 500-700℃ to obtain crude lead I, and then condensed in a zinc liquid collector at below 200℃ to obtain refined zinc (specific composition as shown in Table 1). The lead liquid collector was located near the evaporation zone and connected to the zinc liquid collector. The length of the lead liquid collector was 20-30 cm and the length of the zinc liquid collector was 15-20 cm. In this embodiment, the length of the lead liquid collector was 20 cm and the length of the zinc liquid collector was 15 cm.

[0025] Step 2: The crude tin I obtained in Step 1 is evaporated at a temperature of 800℃ and a pressure of 1Pa through vacuum evaporation I for 1 hour to obtain refined tin in the evaporation zone (the specific composition is shown in Table 1) and crude lead II in the condensation zone.

[0026] Step 3: The crude lead I obtained in Step 1 and the crude lead II obtained in Step 2 are subjected to vacuum volatilization II at a temperature of 700℃ and a pressure of 1Pa for 1 hour to obtain crude tin II in the evaporation zone and refined lead in the condensation zone (the specific composition is shown in Table 1). The crude tin II is returned to the vacuum volatilization I process.

[0027] Table 1. Composition of Tin Fauxite and its Products

[0028]

[0029] After processing using this method, the metal recovery rates of tin, lead, and zinc were 99.0%, 98.2%, and 99.6%, respectively.

[0030] Example 2

[0031] like Figure 1 As shown, the method for recovering valuable metals from tin ash by vacuum carbothermic reduction includes the following steps:

[0032] Step 1, Vacuum carbothermal reduction - directional condensation:

[0033] 5 kg of tin ash (specific composition as shown in Table 2) was mixed with carbon at a ratio of 4:1 (total mass of tin and zinc). Vacuum carbothermal reduction-directional condensation was then carried out at 1200℃, 20 Pa, and 3 h to obtain crude tin I in the evaporation zone. The lead-zinc mixed vapor entering the gas phase was first condensed in a lead liquid collector at 500–700℃ to obtain crude lead I, and then condensed in a zinc liquid collector below 200℃ to obtain refined zinc (specific composition as shown in Table 2). The lead liquid collector was located near the evaporation zone and connected to the zinc liquid collector. The lead liquid collector was 20–30 cm long, and the zinc liquid collector was 15–20 cm long. In this embodiment, the lead liquid collector was 20 cm long, and the zinc liquid collector was 15 cm long.

[0034] Step 2: The crude tin I obtained in Step 1 is evaporated in vacuum volatilization I at a temperature of 1100℃ and a pressure of 100Pa for 2 hours to obtain refined tin in the evaporation zone (the specific composition is shown in Table 2) and crude lead II in the condensation zone.

[0035] Step 3: The crude lead I obtained in Step 1 and the crude lead II obtained in Step 2 are subjected to vacuum volatilization II at a temperature of 900℃ and a pressure of 100Pa for 2 hours to obtain crude tin II in the evaporation zone and refined lead in the condensation zone (the specific composition is shown in Table 2). The crude tin II is returned to the vacuum volatilization I process.

[0036] Table 2 Composition of Tin Ash and its Products

[0037]

[0038] After processing using this method, the metal recovery rates of tin, lead, and zinc were 99.5%, 98.8%, and 99.1%, respectively.

[0039] Example 3

[0040] like Figure 1 As shown, the method for recovering valuable metals from tin ash by vacuum carbothermic reduction includes the following steps:

[0041] Step 1, Vacuum carbothermal reduction - directional condensation:

[0042] 5 kg of tin ash (specific composition as shown in Table 3) was mixed with carbon at a ratio of 3:1 (total mass of tin and zinc). Vacuum carbothermal reduction-directional condensation was then carried out at 1000℃, 10 Pa, and 2 h to obtain crude tin I in the evaporation zone. The lead-zinc mixed vapor entering the gas phase was first condensed in a lead liquid collector at 500–700℃ to obtain crude lead I, and then condensed in a zinc liquid collector below 200℃ to obtain refined zinc (specific composition as shown in Table 3). The lead liquid collector was located near the evaporation zone and connected to the zinc liquid collector. The lead liquid collector was 20–30 cm long, and the zinc liquid collector was 15–20 cm long. In this embodiment, the lead liquid collector was 25 cm long, and the zinc liquid collector was 18 cm long.

[0043] Step 2: The crude tin I obtained in Step 1 is evaporated in vacuum volatilization I at a temperature of 1000℃ and a pressure of 10Pa for 2 hours to obtain refined tin in the evaporation zone (the specific composition is shown in Table 3) and crude lead II in the condensation zone.

[0044] Step 3: The crude lead I obtained in Step 1 and the crude lead II obtained in Step 2 are subjected to vacuum volatilization II at a temperature of 800℃ and a pressure of 10Pa for 2 hours to obtain crude tin II in the evaporation zone and refined lead in the condensation zone (the specific composition is shown in Table 3). The crude tin II is returned to the vacuum volatilization I process.

[0045] Table 3 Composition of Tin Fauxite and its Products

[0046]

[0047]

[0048] After processing using this method, the metal recovery rates of tin, lead, and zinc were 99.4%, 99.0%, and 99.3%, respectively.

[0049] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for recovering valuable metals from tin ash by vacuum carbothermic reduction, characterized in that... Includes the following steps: Step 1: Vacuum carbothermal reduction - directional condensation: Tin ash is mixed with carbon powder at a ratio of 2 to 4:1 based on the total mass of tin and zinc. The mixture is then subjected to vacuum carbothermal reduction and directional condensation at a temperature of 900 to 1200°C, a pressure of 1 to 20 Pa, and a time of 1 to 3 hours. Crude tin I is finally obtained in the evaporation zone. Meanwhile, the lead-zinc mixed vapor entering the gas phase is first condensed in a lead liquid collector at 500 to 700°C to obtain crude lead I, and then condensed in a zinc liquid collector at a temperature below 200°C to obtain refined zinc. Step 2: The crude tin I obtained in Step 1 is subjected to vacuum volatilization I to obtain refined tin and crude lead II; Step 3: Vacuum volatilization process 2 is performed on crude lead I obtained in step 1 and crude lead II obtained in step 2 to obtain crude tin II and refined lead. Crude tin II is returned to the vacuum volatilization process 1. The vacuum evaporation conditions in step 2 are: temperature 800~1100℃, pressure 1~100Pa, and time 1~2h; The conditions for vacuum evaporation II in step 3 are: temperature 700~900℃, pressure 1~100Pa, and time 1~2h.

2. The method for recovering valuable metals from tin ash by vacuum carbothermic reduction according to claim 1, characterized in that: In step 1, the percentage mass composition of tin ash is Sn 20~30%, Pb 50~60%, Zn 5%~15%, Sb 0.01~0.1%, Bi <0.001%, Cu <0.001%.

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