A method for separating indium-tin-silver ternary alloys

Abstract

This invention relates to a method for separating an indium-tin-silver ternary alloy, belonging to the field of pyrometallurgical technology for non-ferrous metals. The indium-tin-silver ternary alloy is heated to complete melting, then inserted into a crystallization shaft. Cooling water is passed through the shaft, which slowly rotates and rises. Silver crystallizes on the shaft, while indium and tin remain molten. The resulting indium-tin melt is then placed in an oxidation volatilization furnace for further melting. Oxygen is bubbled in from the bottom, oxidizing tin and indium. Stannous oxide volatilizes, resulting in stannous oxide in the condensation section, while indium oxide remains in the bottom crucible. This invention features a short process flow, achieving efficient separation of silver, tin, and indium through only two steps: crystallization and oxidation volatilization.

Description

Technical Field

[0001] This invention relates to a method for separating indium-tin-silver ternary alloys, belonging to the field of non-ferrous metal pyrometallurgical technology. Background Technology

[0002] Indium tin-silver (ITi) ternary alloys possess excellent resistance to welding and burn-off, making them ideal contact and contact material. They are widely used in relays, contactors, circuit breakers, motor protectors, micro switches, instruments, household appliances, automotive electrical systems (light switches, starter motors, and other load switches), and residual current circuit breakers (RCCBs). Given the high value of each metal in ITi, there is an urgent need to separate the metals from ITi and efficiently recycle each element. Summary of the Invention

[0003] To address the problems and shortcomings of the existing technology, this invention provides a method for separating indium-tin-silver ternary alloys. This invention is achieved through the following technical solution.

[0004] A method for separating indium-tin-silver ternary alloys, comprising the following steps:

[0005] Step 1: Heat the indium-tin-silver ternary alloy until it is completely melted, then insert it into a crystallization shaft and pass cooling water into the crystallization shaft. Silver crystals will precipitate on the crystallization shaft, and the remaining indium-tin melt will be obtained.

[0006] Step 2: Place the indium-tin melt obtained in Step 1 into an oxidation volatilization furnace for melting. Blow an oxidant through a spray gun. After tin and indium are oxidized, stannous oxide volatilizes while indium oxide does not volatilize. Stannous oxide is obtained in the condensation section, and the remaining indium oxide is obtained.

[0007] In step one, the indium-tin-silver ternary alloy contains 40-90% indium, 10-60% tin, and 5-20% silver, with a total indium, tin, and silver content of 100%.

[0008] In step one, the indium-tin-silver ternary alloy is heated to 800~1000℃ and completely melted.

[0009] In step one, the crystallization shaft is made of graphite. Cooling water is introduced into the crystallization shaft to maintain the temperature of the crystallization shaft at 600~800℃. The rotation speed of the crystallization shaft is 10~30 r / min, the pulling speed is 0.1~0.5 mm / min, and the crystallization time is 120~300 min.

[0010] In step one, the crystallizing shaft is a hollow circular tube with a partition inside, which divides the tube into an inlet pipe and an outlet pipe. The bottom of the partition is 10-30mm away from the bottom of the circular tube, allowing the inlet and outlet water to flow between each other.

[0011] In step two, the indium-tin melt is melted at a temperature of 400~800℃, and then an oxidant is blown in from the spray gun and oxidized and volatilized at a pressure of 10~50Pa for 30~120 minutes.

[0012] The working principle of this invention is as follows: Based on the large difference in melting points of indium, tin, and silver, the temperature distribution difference in the system is controlled, and a crystallization axis is used to crystallize and precipitate silver to obtain pure silver product. In the range of 400~800℃, an oxidant is added to the silver-tin melt to oxidize tin to stannous oxide and indium to react to form indium oxide. Since the saturated vapor pressures of stannous oxide and indium oxide are significantly different, the stannous oxide is volatilized through a vacuum distillation process, and indium remains in the form of indium oxide, thereby achieving the separation of silver, tin, and indium.

[0013] The beneficial effects of this invention are:

[0014] (1) The process flow is short. The separation of silver, tin and indium in the indium-tin-silver ternary alloy can be achieved through two process steps: crystallization and oxidation volatilization.

[0015] (2) The process of this invention is a full pyrometallurgical process, which does not produce wastewater and has no wastewater treatment cost.

[0016] (3) Pure silver can be directly obtained by using this process for indium-tin-silver ternary alloy.

[0017] (4) The tin oxide and indium oxide produced by this process have high purity and can be used directly as materials. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0019] Figure 2 This is a schematic diagram of the melt crystallization and oxidation volatilization equipment and its principle according to the present invention;

[0020] Figure 3 A schematic diagram of the crystallization axis structure of this invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] like Figure 1 and 2 As shown, the method for separating the indium-tin-silver ternary alloy includes the following steps:

[0024] Step 1: A ternary alloy of indium, tin, and silver (83 wt% indium, 11 wt% tin, and 6 wt% silver) is heated to 1000℃ and completely melted. A crystallization shaft is then inserted, and cooling water is passed through it. Silver crystals precipitate on the shaft, and the remaining indium-tin melt is obtained. The crystallization shaft is made of graphite. Cooling water is passed through the shaft to maintain a temperature of 600℃. The rotation speed of the shaft is 10 r / min, the pulling speed is 0.1 mm / min, and crystallization takes 120 minutes. Figure 3 As shown, the crystallizing shaft is a hollow cylindrical tube with a partition inside, which divides the tube into an inlet pipe and an outlet pipe. The bottom of the partition is 10mm away from the bottom of the cylindrical tube, allowing water to flow between the inlet and outlet. A power device is installed at the top of the crystallizing shaft to control the rotation and rise of the crystallizing shaft according to the speed.

[0025] Step 2: Place the indium-tin melt obtained in Step 1 into an oxidation volatilization furnace and melt it at 500℃. Blow an oxidant (oxygen as the oxidant, with an addition rate of 0.5~5 ml / min) into the furnace through a top-blown lance. Oxidize and volatilize at a pressure of 50 Pa for 2 hours. Tin oxide is obtained in the condensation section, and indium oxide is obtained in the crucible.

[0026] The silver crystals obtained in this embodiment have a purity of 98.14%, tin oxide a purity of 99.25%, and indium oxide a purity of 98.57%.

[0027] Comparative Examples

[0028] The indium-tin-silver ternary alloy (83 wt% indium, 11 wt% tin, and 6 wt% silver) was heated to 1000°C in a reactor and completely melted. Then, the reactor temperature was directly controlled to drop to 600°C. After crystallization for 120 minutes, the indium-tin melt was released and a large amount of silver crystals were found to be doped in the indium-tin melt.

[0029] As seen in Example 1 and the comparative example, direct temperature-controlled crystallization cannot effectively separate the silver product and the indium-tin melt.

[0030] Example 2

[0031] like Figure 1 and 2 As shown, the method for separating the indium-tin-silver ternary alloy includes the following steps:

[0032] Step 1: A ternary alloy of indium, tin, and silver (69 wt% indium, 24 wt% tin, and 7 wt% silver) is heated to 1000℃ and completely melted. Then, a rotating crystallizing shaft is inserted, and cooling water is passed through it. Silver crystals precipitate on the shaft, and the remaining indium-tin melt is obtained. The rotating crystallizing shaft is made of graphite. Cooling water is passed through it to maintain the temperature at 800℃. The rotation speed is 20 r / min, the pulling speed is 0.5 mm / min, and crystallization takes 200 minutes. Figure 3 As shown, the rotating crystallizing shaft is a hollow cylindrical tube with a partition inside, which divides the tube into an inlet pipe and an outlet pipe. The bottom of the partition is 20mm away from the bottom of the cylindrical tube, allowing water to flow between the inlet and outlet. A rotating power device is provided at the top of the rotating crystallizing shaft to control the rotating crystallizing shaft to rotate and rise according to the speed.

[0033] Step 2: Place the indium-tin melt obtained in Step 1 into an oxidation volatilization furnace and melt it at 600℃. Blow an oxidant (oxygen as the oxidant, with an addition rate of 0.5~5 ml / min) into the furnace from the top. Add oxygen from the bottom and oxidize and volatilize at a pressure of 20 Pa for 120 min. In the condensation section, tin oxide is obtained, and the remaining indium oxide is also obtained.

[0034] The silver crystals obtained in this embodiment have a purity of 98.06%, tin oxide a purity of 99.81%, and indium oxide a purity of 99.03%.

[0035] Example 3

[0036] like Figure 1 and 2 As shown, the method for separating the indium-tin-silver ternary alloy includes the following steps:

[0037] Step 1: The indium-tin-silver ternary alloy (76wt% indium, 18wt% tin, and 5wt% silver) is heated to 1200℃ and completely melted. Then, a rotating crystallizing shaft is inserted, and cooling water is passed through it. Silver crystals precipitate on the shaft, and the remaining indium-tin melt is obtained. The rotating crystallizing shaft is made of graphite. Cooling water is passed through it to maintain the temperature at 700℃. The rotation speed is 30 r / min, the pulling speed is 0.3 mm / min, and crystallization takes 250 minutes. Figure 3 As shown, the rotating crystallizing shaft is a hollow cylindrical tube with a partition inside, which divides the tube into an inlet pipe and an outlet pipe. The bottom of the partition is 20mm away from the bottom of the cylindrical tube, allowing water to flow between the inlet and outlet. A rotating power device is provided at the top of the rotating crystallizing shaft to control the rotating crystallizing shaft to rotate and rise according to the speed.

[0038] Step 2: Place the indium-tin melt obtained in Step 1 into an oxidation volatilization furnace and melt it at 700℃. Blow an oxidant (oxygen as the oxidant, with an addition rate of 0.5~5 ml / min) into the furnace through a top-blown nozzle. Oxidize and volatilize at a pressure of 10 Pa for 120 min. In the condensation section, tin oxide is obtained, and the remaining indium oxide is also obtained.

[0039] The silver crystals obtained in this embodiment have a purity of 97.62%, tin oxide a purity of 99.89%, and indium oxide a purity of 99.45%.

[0040] 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 separating indium-tin-silver ternary alloys, characterized by the following steps include: Step 1: The indium-tin-silver ternary alloy is completely melted, then inserted into a crystallization shaft. Cooling water is passed into the crystallization shaft, which rotates and rises slowly. Silver in the melt will precipitate into crystals on the crystallization shaft when the temperature reaches the crystallization point, while indium-tin remains a melt. Step 2: The indium-tin melt obtained in Step 1 is placed in an oxidation volatilization furnace for melting. An oxidant is blown in from the spray gun. Tin and indium are oxidized into stannous oxide and indium oxide. The stannous oxide of tin volatilizes and stannous oxide is obtained in the condensation section. Indium oxide remains in the crucible.

2. The method for separating indium-tin-silver ternary alloys according to claim 1, characterized in that: In step one, the indium-tin-silver ternary alloy contains 40-90 wt% indium, 10-60 wt% tin, and 5-20 wt% silver, with a total indium, tin, and silver content of 100 wt%.

3. The method for separating indium-tin-silver ternary alloys according to claim 1, characterized in that: The indium-tin-silver ternary alloy in step one is heated to 800~1000℃ and completely melted.

4. The method for separating indium-tin-silver ternary alloys according to claim 1, characterized in that: In step one, the crystallization shaft is made of graphite. Cooling water is introduced into the crystallization shaft to maintain the temperature of the crystallization shaft at 600~800℃. The rotation speed of the crystallization shaft is 10~30 r / min, the pulling speed is 0.1~0.5 mm / min, and the crystallization time is 120~300 min.

5. The method for separating indium-tin-silver ternary alloys according to claim 4, characterized in that: In step one, the crystallizing shaft is a hollow circular tube with a partition inside, which divides the tube into an inlet pipe and an outlet pipe. The bottom of the partition is 10-30mm away from the bottom of the circular tube, allowing the inlet and outlet water to flow between each other.

6. The method for separating indium-tin-silver ternary alloys according to claim 1, characterized in that: In step two, the indium-tin melt is melted at a temperature of 400~800℃, and then an oxidant is blown in from the spray gun and oxidized and volatilized at a pressure of 10~50Pa for 30~120 minutes.

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