Method for preparing polycrystalline silicon particles from silicon wastes

Abstract

The invention discloses a method for preparing polycrystalline silicon particles from silicon waste, and belongs to the technical field of photovoltaic products. According to the invention, silicon waste is used as a raw material, and cleaning, granulating, drying, microwave sintering, cooling and the like are performed to obtain polycrystalline silicon particles, wherein the specific physical strength of the polycrystalline silicon particles is that the polycrystalline silicon particles cannot be broken when rolling, falling off and the like within one meter, the purity of the polycrystallinesilicon particles is high (99.9999%-99.99999%), and the particle size of the polycrystalline silicon particles is uniform (300-30 mm); the method can be used in other required processes, increases the one-time charging amount, can also be used as a re-charging material, greatly reduces the production cost of polycrystalline silicon, and recycles resources; and the preparation method is low in cost.

Description

technical field [0001] The invention relates to a method for preparing polysilicon particles, in particular to a method for preparing polysilicon particles from silicon waste, and belongs to the technical field of photovoltaic products. Background technique [0002] The solar photovoltaic industry is an industry with small profits and small space, and requires low production cost of high-purity silicon materials, which poses great challenges to the traditional production methods of high-purity silicon materials. At present, in the existing high-purity silicon production process, a large amount of silicon waste is produced and has not been effectively utilized. Among them, these silicon wastes include: [0003] 1. In polysilicon production using the improved Siemens method, chlorine and hydrogen are used to synthesize HCl gas, and HCl gas and metallurgical silicon powder are synthesized at a certain temperature to SiHCl 3 , the SiHCl after separation and rectification purifi...

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Problems solved by technology

In this production process, the silicon powder produced inevitably adheres to the inner wall of the reactor, and is taken out of the reactor by SiHCl3, hydrogen and other gas streams, that is, this part of the silicon powder becomes waste and cannot application;

[0004] 2. The polysilicon rods produced by the improved Siemens method need to be crushed when they enter the next process. Broken into small pieces of different sizes and irregular shapes, and this process will produce a large amount of waste silicon materials below 3mm regardless of manual knocking or jaw crusher. These waste silicon materials are small in size and may be polluted Therefore, most polysilicon production enterprises dispose of such waste silicon materials at low prices or discard them, and this part of silicon materials cannot be used;

[0005] 3. When cutting silicon wafers, about 30% of the total mass of cutting silicon powder is produced. Similarly, this part of silicon powder cannot be used

[0006]The above-mentioned silicon materials are high-purity polysilicon in essence and have high value, but they have not been effectively used in subsequent production. The main reasons are: 1. The diameter is too small and the body surface area is large. If it is not well preserved, the surface of the silicon material is easily oxidized by the air, and its purity cannot be guaranteed; 2. The silicon powder is light in weight, and it is easy to raise dust during use, which is difficult to control; 3. The silicon powder is easily adsorbed by static electricity , the formation of pipeline blockage, enrichment of the cavity wall, resulting in reduced life of the equipment

In the end, this part of the silicon material cannot be effectively used in actual production, resulting in a huge waste of resources

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