Efficient and energy-saving smelting process of indium-tin alloy

Abstract

The invention discloses a high-efficiency energy-saving smelting process of indium tin alloy, which comprises the following steps: A) crushing and ball-milling an ITO (indium tin oxide) waste target material to obtain ITO waste target powder; b) the ITO waste target powder and a slag former are uniformly mixed, the mass ratio of the ITO waste target powder to the slag former is 1: (0.1-0.5), the slag former is a mixture of lime and fluorite, and the mass ratio of the lime to the fluorite is 2: 3; c, the mixture is put into a reduction furnace to be smelted, before feeding, nitrogen is introduced firstly, air in the furnace is expelled out, then hydrogen is introduced, a reduction reaction is carried out, the temperature is 1000-1300 DEG C, and the smelting time is 5-8 h; and D) after the smelting is finished, obtaining a smelting solution and slag, pouring the smelting solution and the slag into an ingot casting mold, cooling to 300 DEG C, and fishing out the slag to obtain the indium-tin alloy. The process flow is simple and efficient, and the product is high in purity and good in quality.

Description

Technical Field

[0001] The invention relates to the technical field of smelting, and in particular to a high-efficiency and energy-saving smelting process of indium-tin alloy. Background Art

[0002] Indium tin alloy is a rare metal alloy with a wide range of uses in industrial production, such as liquid crystal displays, solar panels, semiconductor wafers, lenses, bottles and pharmaceutical products. Indium tin alloy is usually prepared by smelting indium and tin metals in a furnace. As primary indium-rich resources are gradually exhausted, it has become a trend to extract indium and tin from secondary resources and then smelt indium tin alloy. ITO waste targets and scraps and chips generated during the production of ITO targets have become one of the most important secondary resources due to their high indium and tin content.

[0003] Patent document CN109762993A discloses a method for preparing indium tin alloy from ITO waste target by high-temperature reduction of graphite powder. This method requires preparation of particles of a specific shape, and first adding water to make pulp and then drying. The operation process is relatively large, and a large amount of energy is consumed. Spray equipment is required, and volatile organic solvents such as ethanol, acetone and non-ionic surfactants are added as graphite surface lubricants.

[0004] Patent document CN104818388B discloses a method for preparing indium tin alloy from ITO waste targets by high-temperature reduction using coal, charcoal and carbon. This method completes the reduction and indium tin separation steps in a vacuum furnace, simplifies the operation process, and obtains crude indium alloy and crude tin alloy. However, there are also steps of material mixing and granulation and particle drying, which increases energy loss. At the same time, when coal is used as a reducing agent, a large amount of impurity elements in fly ash during the reduction process will enter the crude indium alloy and crude tin alloy products, resulting in low product purity and poor quality. Summary of the invention

[0005] The purpose of the present invention is to provide an efficient and energy-saving smelting process for indium tin alloy to solve the technical problems existing in the background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a high-efficiency and energy-saving smelting process of indium tin alloy, comprising the following steps:

[0007] A) Raw material preparation: After the ITO waste target material is ultrasonically cleaned with an organic solvent, it is dried, crushed and ball-milled to obtain ITO waste target powder, and the particle size of the ITO waste target powder is less than 1000 μm; the slag-forming agent is ground into powder, and the slag-forming agent is a mixture of lime and fluorite, and the mass ratio of lime to fluorite is (5-3:2-1);

[0008] B) Mixing: Evenly mix the ITO waste target powder and the slag-forming agent powder, wherein the mass ratio of the ITO waste target powder to the slag-forming agent is 1:(0.3-0.5);

[0009] C) Reduction smelting: firstly, nitrogen is introduced into the reduction furnace to drive out the air in the furnace, and the mixture of the above-mentioned ITO waste target powder and slag-forming agent powder is put into the reduction furnace for smelting, and hydrogen is introduced during the smelting process to carry out reduction reaction, the smelting temperature is 1000-1300° C., and the smelting time is 5-8h;

[0010] D) Preparation of alloy products: After smelting, a molten solution and slag are obtained, the molten solution and slag are poured into an ingot casting mold, cooled to 300°C, and then the slag is removed to obtain an indium tin alloy.

[0011] Preferably, in step C), the amount of nitrogen introduced is 250-300 L / h, and the amount of hydrogen introduced is 150-200 L / h.

[0012] Preferably, the smelting process in step C) includes a stirring step.

[0013] Preferably, the particle size of the slag-forming agent is 1200-1400 μm.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. In this application, nitrogen is introduced before feeding, so that the reduction furnace is in an oxygen-free environment, the reduction effect is better, and hydrogen is used as a reducing agent, which will not bring in other impurities, and the final product has high purity and good quality.

[0016] 2. The slag-forming agent used in the present application and the appropriate proportion can react well with the impurity elements (such as silicon, phosphorus, etc.) in the target material to generate metal-insoluble compounds, thereby playing a role in purifying the melt.

[0017] 3. The process flow of this application is simple, efficient and has low energy consumption. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Embodiment 1: A high-efficiency and energy-saving smelting process of indium-tin alloy, comprising the following steps:

[0020] The ITO waste target material raw material is ultrasonically cleaned with acetone and dried, and then the ITO waste target material is put into a crusher for crushing. The indium tin metal content in the ITO waste target material is 83.5wt%. After crushing, it is transferred to a ball mill for ball milling to obtain ITO waste target powder. The particle size of the ITO waste target powder is 900μm; the slag-forming agent is also ground into powder. The particle size of the slag-forming agent is 1200μm. The slag-forming agent is a mixture of lime and fluorite, and the mass ratio of lime to fluorite is 5:2. The ITO waste target powder and the slag-forming agent powder are mixed evenly, and the mass ratio of the ITO waste target powder and the slag-forming agent is 1:0.3. Before feeding, nitrogen is first introduced into the reduction furnace to drive out the air in the furnace. The amount of nitrogen introduced is 300L / h, and the introduction time depends on the size of the reduction furnace. After completion, the nitrogen supply is stopped, and the mixture of the above-mentioned ITO waste target powder and the slag-forming agent powder is put into the reduction furnace for smelting. Hydrogen is introduced and stirred during the smelting process. The amount of hydrogen introduced is 200L / h, the smelting temperature is 1300°C, and the smelting time is 5h. After the smelting is completed, a smelting solution and slag are obtained, and the smelting solution and slag are poured into an ingot mold. After cooling to 300°C, the slag is fished out to obtain an indium tin alloy. The indium tin alloy content of this embodiment is 95.81% after detection.

[0021] Example 2: After the ITO waste target material raw material is ultrasonically cleaned with acetone and dried, the ITO waste target material is put into a crusher for crushing. The indium tin metal content in the ITO waste target material is 81.2wt%. After crushing, it is transferred to a ball mill for ball milling to obtain ITO waste target powder. The particle size of the ITO waste target powder is 800μm; the slag-forming agent is also ground into powder. The particle size of the slag-forming agent is 1400μm. The slag-forming agent is a mixture of lime and fluorite. The mass ratio of lime to fluorite is 3:1. The ITO waste target powder and the slag-forming agent powder are mixed evenly, and the mass ratio of the ITO waste target powder and the slag-forming agent is 1:0.5. Before feeding, nitrogen is first introduced into the reduction furnace to drive out the air in the furnace. The amount of nitrogen introduced is 250L / h, and the introduction time depends on the size of the reduction furnace. After completion, the nitrogen supply is stopped, and the mixture of the above-mentioned ITO waste target powder and the slag-forming agent powder is put into the reduction furnace for smelting. Hydrogen is introduced and stirred during the smelting process. The amount of hydrogen introduced is 150L / h, the smelting temperature is 1000°C, and the smelting time is 8h. After the smelting is completed, a smelting solution and slag are obtained, and the smelting solution and slag are poured into an ingot mold. After cooling to 300°C, the slag is fished out to obtain an indium tin alloy. The indium tin alloy content of this embodiment is 92.63% after detection.

[0022] Example 3: The ITO waste target material raw material is ultrasonically cleaned with acetone and dried, and then the ITO waste target material is put into a crusher for crushing. The indium tin metal content in the ITO waste target material is 82.53wt%. After crushing, it is transferred to a ball mill for ball milling to obtain ITO waste target powder. The particle size of the ITO waste target powder is 700μm; the slag-forming agent is also ground into powder. The particle size of the slag-forming agent is 1300μm. The slag-forming agent is a mixture of lime and fluorite, and the mass ratio of lime to fluorite is 3:2. The ITO waste target powder and the slag-forming agent powder are mixed evenly, and the mass ratio of the ITO waste target powder and the slag-forming agent is 1:0.4. Before feeding, nitrogen is introduced into the reduction furnace to drive out the air in the furnace. The amount of nitrogen introduced is 280L / h, and the introduction time depends on the size of the reduction furnace. After completion, the nitrogen supply is stopped, and the mixture of the above-mentioned ITO waste target powder and the slag-forming agent powder is put into the reduction furnace for smelting. Hydrogen is introduced and stirred during the smelting process. The amount of hydrogen introduced is 180L / h, the smelting temperature is 1200°C, and the smelting time is 7h. After the smelting is completed, a smelting solution and slag are obtained, and the smelting solution and slag are poured into an ingot mold. After cooling to 300°C, the slag is fished out to obtain an indium tin alloy. The indium tin alloy content of this embodiment is 93.52% after detection.

[0023] Example 4: After the ITO waste target material raw material is ultrasonically cleaned with acetone and dried, the ITO waste target material is put into a crusher for crushing. The indium tin metal content in the ITO waste target material is 81.65wt%. After crushing, it is transferred to a ball mill for ball milling to obtain ITO waste target powder. The particle size of the ITO waste target powder is 800μm; the slag forming agent is also ground into powder. The particle size of the slag forming agent is 1200μm. The slag forming agent is a mixture of lime and fluorite. The mass ratio of lime to fluorite is 3:1. The ITO waste target powder and the slag-forming agent powder are mixed evenly, and the mass ratio of the ITO waste target powder and the slag-forming agent is 1:0.5. Before feeding, nitrogen is introduced into the reduction furnace to drive out the air in the furnace. The amount of nitrogen introduced is 300L / h, and the introduction time depends on the size of the reduction furnace. After completion, the nitrogen supply is stopped, and the mixture of the above-mentioned ITO waste target powder and the slag-forming agent powder is put into the reduction furnace for smelting. Hydrogen is introduced and stirred during the smelting process. The amount of hydrogen introduced is 150L / h, the smelting temperature is 1250°C, and the smelting time is 6h. After the smelting is completed, a smelting solution and slag are obtained, and the smelting solution and slag are poured into an ingot mold. After cooling to 300°C, the slag is fished out to obtain an indium tin alloy. The indium tin alloy content of this embodiment is 94.56% after detection.

[0024] Finally, it should be noted that the above is only a specific embodiment of the present invention, which is used to illustrate the technical solution of the present invention, rather than to limit it. Those skilled in the art should understand that any person familiar with the technical field can still modify the technical solution recorded in the above embodiment within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiment of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An efficient and energy-saving smelting process for indium tin alloy, characterized in that: The following steps are involved: A) Raw material preparation: After the ITO waste target material is ultrasonically cleaned with an organic solvent, it is dried, crushed and ball-milled to obtain ITO waste target powder, and the particle size of the ITO waste target powder is less than 1000 μm; the slag-forming agent is ground into powder, and the slag-forming agent is a mixture of lime and fluorite, and the mass ratio of lime to fluorite is (5-3:2-1); B) Mixing: Evenly mix the ITO waste target powder and the slag-forming agent powder, wherein the mass ratio of the ITO waste target powder to the slag-forming agent is 1:(0.3-0.5); C) Reduction smelting: firstly, nitrogen is introduced into the reduction furnace to drive out the air in the furnace, and the mixture of the above-mentioned ITO waste target powder and slag-forming agent powder is put into the reduction furnace for smelting, and hydrogen is introduced during the smelting process to carry out reduction reaction, the smelting temperature is 1000-1300° C., and the smelting time is 5-8h; D) Preparation of alloy products: After smelting, a molten solution and slag are obtained, the molten solution and slag are poured into an ingot casting mold, cooled to 300°C, and then the slag is removed to obtain an indium tin alloy.

2. The high-efficiency and energy-saving smelting process of indium-tin alloy according to claim 1, characterized in that: In step C), the amount of nitrogen introduced is 250-300 L / h, and the amount of hydrogen introduced is 150-200 L / h.

3. The high-efficiency and energy-saving smelting process of indium-tin alloy according to claim 2, characterized in that: The smelting process in step C) includes a stirring step.

4. The high-efficiency and energy-saving smelting process of indium-tin alloy according to claim 1, characterized in that: The particle size of the slag-forming agent is 1200-1400 μm.