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A method for combined melting and refining to purify industrial silicon

A technology for refining, purifying, and industrial silicon, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of low efficiency, unstable products, and high energy consumption, reducing energy consumption, reducing entrainment, and improving purification efficiency. Effect

Active Publication Date: 2016-08-17
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a method for combined melting and refining to purify industrial silicon, which overcomes the shortcomings of low efficiency, high energy consumption, and unstable products in most metallurgical processes, and effectively removes boron, phosphorus, and metal impurities.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] 10kg of industrial silicon blocks (brand 1101, produced in Hunan) were crushed and ground into particles with a particle size of less than 500 microns, and sieved to obtain silicon powder with a particle size of 150-500 microns. Get 100g silicon powder and wash, dry, obtain pretreatment silicon powder. Mix the pretreated silicon powder with metallic tin (purity 99.99%), heat to 1300°C to completely melt, and cool to room temperature at 3°C / min. The silicon crystals are separated by centrifugation, and the silicon crystals are made into particles with a particle size of less than 500 microns. They are pickled with 5wt% hydrofluoric acid at 70°C for 6 hours, and the reaction solid-to-liquid ratio is 1:10. After pickling, the silicon powder is rinsed and dried. Then pickle with 20wt% aqua regia at 70°C for 6 hours, the reaction solid-to-liquid ratio is 1:10, rinse and dry the silicon powder after pickling. The obtained silicon powder is mixed with metallic aluminum (purit...

Embodiment 2

[0028] 10kg of industrial silicon blocks (brand 1101, produced in Hunan) were crushed and ground into particles with a particle size of less than 500 microns, and sieved to obtain silicon powder with a particle size of 150-500 microns. Take 100g of silicon powder, wash with water, and dry to obtain pretreated silicon powder. The pretreated silicon powder was mixed with the centrifuged waste tin in Example 1, heated to 1300°C to completely melt, and cooled to room temperature at 3°C / min. The silicon crystals are separated by centrifugation, and the silicon crystals are made into particles with a particle size of less than 500 microns. They are pickled with 5wt% hydrofluoric acid at 70°C for 6 hours, and the reaction solid-to-liquid ratio is 1:10. After pickling, the silicon powder is rinsed and dried. Then pickle with 20wt% aqua regia at 70°C for 6 hours, the reaction solid-to-liquid ratio is 1:10, rinse and dry the silicon powder after pickling. The obtained silicon powder wa...

Embodiment 3

[0033] 10kg of industrial silicon blocks (brand 1101, produced in Yunnan) were crushed and ground into particles with a particle size of less than 500 microns, and sieved to obtain silicon powder with a particle size of 150-500 microns. Take 100g of silicon powder, wash with water, and dry to obtain pretreated silicon powder. Mix the pretreated silicon powder with metal tin (purity 99.9%), heat to 1250°C to completely melt, and cool to room temperature at 3°C / min. The silicon crystals are separated by centrifugation, and the silicon crystals are made into particles with a particle size of less than 500 microns. They are pickled with 5wt% hydrofluoric acid at 70°C for 6 hours, and the reaction solid-to-liquid ratio is 1:20. After pickling, the silicon powder is rinsed and dried. Then pickle with 20wt% aqua regia at 70°C for 6 hours, the reaction solid-to-liquid ratio is 1:20, rinse and dry the silicon powder after pickling. The obtained silicon powder was mixed with metallic a...

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Abstract

A method for purifying industrial silicon through combination of melting, precipitation and refining belongs to a technology for preparing solar-grade highly pure silicon. The method comprises the following steps: heating industrial silicon and a tin-based alloy to complete eutectic melting, cooling for recrystallization precipitation of silicon, pickling the above obtained crystal silicon, heating the pickled crystal silicon and an aluminum-based alloy to complete eutectic melting, cooling for silicon precipitation, pickling the obtained crystal silicon, and carrying out directional solidification, ingot casting and dicing of the pickled crystal silicon to obtain highly pure polysilicon. The operation temperature of the method is below 1400DEG C, so the content of impurities comprising boron and phosphorus is reduced to meet requirements of the solar grade silicon.

Description

technical field [0001] The invention relates to a technology for preparing solar-grade polysilicon, in particular to a method for combining melting and refining to purify industrial silicon. Background technique [0002] With the rapid development of the photovoltaic industry, the demand for solar-grade polysilicon has increased sharply. Due to the problems of high energy consumption, high cost and serious pollution in the production of solar polysilicon by chemical methods such as the Siemens method, the technology of preparing polysilicon by metallurgy has become the focus of attention. . [0003] The metallurgical method is to remove silicon by a series of combined methods such as pickling, directional solidification, gasification-slagging refining, vacuum smelting, high-energy beam (electron, ion) method, alloy melting and refining, etc. without changing the properties of the main silicon. Impurities in metallurgical silicon is a step-by-step purification process for im...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
Inventor 王志胡磊
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI