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Removing method of boron impurities in metalluragical silicon

A technology for metallurgical silicon and impurities, which is applied to the purification process field of metallurgical silicon materials, can solve the problems of difficulty in removing impurities and costs, and achieve the effects of reducing purification costs and easy and simple operation.

Inactive Publication Date: 2009-12-09
JACO SOLARSI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a kind of metallurgical silicon that can remove boron in silicon at a lower temperature, with simple removal method and lower cost, in view of the defects of difficult impurity removal and cost in the existing solar-grade polysilicon purification process The removal method of middle impurity boron

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Put the self-produced or purchased metal silicon block with a boron content of 60ppm into the general mill and crush it to obtain a powder with a particle size between 50 mesh and 800 mesh. Soak the 50 mesh silicon powder in acid for 6 hours to remove metal impurities, and then Plasma water is used for cleaning, and the cleaned silicon powder is baked in an oven. When the silicon powder is in a dry state, the treated silicon powder is put into a closed reactor, and the reactor is heated to 700°C and passed through Oxygen is introduced, and the silicon powder is not stirred during this process. The treatment time is 72 hours, so that non-metallic impurities such as boron are oxidized into oxides soluble in water or acid. Soak the oxidized silicon powder in hydrochloric acid for 48 hours to remove the oxides of non-metallic impurities such as boron, then wash it with deionized water, and bake it at 200°C. After 6 hours, the silicon powder is dry state. After the above tr...

Embodiment 2

[0022] In Example 1, silicon powder with a particle size of 300 meshes was put into acid and soaked for 12 hours to remove metal impurities, then cleaned with tap water, and the cleaned silicon powder was baked in an oven. When the silicon powder was in a dry state, put The treated silicon powder is placed in a closed reactor, the reactor is heated to 500°C and oxygen is introduced, and the silicon powder is not stirred during this process. The treatment time is 72 hours, so that non-metallic impurities such as boron are eliminated. Oxidized to water-soluble or acid-soluble oxides. Soak the oxidized silicon powder in hydrochloric acid for 6 hours to remove the oxides of non-metallic impurities such as boron, then wash it with deionized water, and bake it at 150°C. After 8 hours, the silicon powder is dry state. After the above treatment, the boron content of metal silicon is 32ppm.

Embodiment 3

[0024] In Example 1, silicon powder with a particle size of 500 meshes was put into acid and soaked for 48 hours to remove metal impurities, then cleaned with deionized water, and the cleaned silicon powder was put into an oven to bake. When the silicon powder was in a dry state , put the treated silicon powder into a semi-closed reactor, heat the reactor to 300°C and let in air, and stir the silicon powder during this process. The treatment time is 48 hours, so that boron and other non- Metallic impurities are oxidized to water or acid soluble oxides. Soak the oxidized silicon powder in aqua regia for 12 hours to remove oxides of non-metallic impurities such as boron, then wash it with distilled water, and bake it at 150°C. After 8 hours, the silicon powder is in a dry state. After the above treatment, the boron content of metal silicon is 28ppm.

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Abstract

The invention discloses a removing method of boron impurities in metallurgical silicon, comprising the following steps: immersing the metallurgical silicon powder into acid for 6 hours to 48 hours to carry out acid cleaning, washing the metallurgical silicon powder, drying the metallurgical silicon powder, putting the metallurgical silicon powder subjected to the acid cleaning, the washing and the drying into a reactor, heating the metallurgical silicon powder to the temperature of 300 DEG C-700 DEG C, introducing oxidizing gas to carry out an oxidizing reaction for 6 hours to 72 hours, immersing the metallurgical silicon powder which is heated and oxidized into water or acid for 1 hour to 6 hours, washing the metallurgical silicon powder, and baking the metallurgical silicon powder which is immersed and washed for 6 hours to 24 hours at the temperature of 100 DEG C-300 DEG C. With the purification process of the metallurgical silicon of the invention, because the purification is completed at lower temperature, the operation is easier and simpler, the purification cost is also reduced. Thus, high quality raw materials are provided for later processes so that needs of producing solar-grade polycrystalline silicon at low cost are met.

Description

technical field [0001] The invention relates to a purification process of metallurgical silicon materials, in particular to a method capable of removing impurity boron in metallurgical silicon. Background technique [0002] People have found that the reserves of fossil energy have decreased sharply, and at the same time, the use of fossil energy has seriously polluted the environment. Human beings are actively developing new types of energy that are both environmentally friendly and renewable. At present, the renewable green energy that has entered human life includes solar energy and wind energy, among which solar energy is the one that human beings value most, and this situation can be well reflected in developed countries. Silicon material is the most widely used solar panel material. According to the use of silicon material, silicon material can be divided into electronic grade and solar grade. At present, electronic grade waste or leftover materials are basically used ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
CPCC01B33/037
Inventor 蒋光辉
Owner JACO SOLARSI
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