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Method for purifying silicon through phase separation and dealloying

A dealloying and phase separation technology, applied in chemical instruments and methods, inorganic chemistry, silicon compounds, etc., can solve the problems of high cost, complex process, high energy consumption, etc., and achieve short cycle, high pollution, and low energy consumption Effect

Active Publication Date: 2019-06-28
WUHAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Aiming at the above defects or improvement needs of the prior art, the present invention provides a method for purifying silicon by vapor phase dealloying, which first converts the silicon element in the raw silicon containing impurities into magnesium silicide to realize the first separation of silicon and impurities. After one separation, the silicon-magnesium alloy is converted into magnesium nitride in a nitrogen-containing atmosphere, and silicon with a three-dimensional porous structure is re-precipitated to further separate silicon from impurities, wherein magnesium nitride is formed in a three-dimensional channel, and finally Remove magnesium nitride and the impurities mixed in it by pickling, thereby solving the technical problems of high cost, high energy consumption and complicated process existing in the existing improved Siemens method and metallurgical method for purifying silicon

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  • Method for purifying silicon through phase separation and dealloying
  • Method for purifying silicon through phase separation and dealloying
  • Method for purifying silicon through phase separation and dealloying

Examples

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Embodiment 1

[0051] A method for purifying silicon by phase separation dealloying, comprising the steps of:

[0052] (1) Mix metallurgical ferrosilicon powder (Si content is 80%) and magnesium powder according to the mass ratio of silicon and magnesium as 1:2 and put them into the high temperature resistant container;

[0053] (2) Put the container in a tube furnace filled with inert gas and heat it up to 600°C at a heating rate of 5°C / min. The holding time is 6h to obtain the product silicon-magnesium alloy mixture. After the product is cooled to room temperature with the furnace, take it out;

[0054] (3) put the product obtained in (2) into N 2 In the atmosphere, heat up to 780°C at a heating rate of 5°C / min, hold for 4 hours, and take out the product after cooling to room temperature with the furnace;

[0055] (4) Wash the product obtained in (3) with 1M hydrochloric acid to remove magnesium nitride, wash, centrifuge, and dry to obtain high-purity silicon. ICP test results show that ...

Embodiment 2

[0064] A method for purifying silicon by phase separation dealloying, comprising the steps of:

[0065] (1) Mix metallurgical ferrosilicon powder (Si content is 80%) and magnesium powder according to the mass ratio of silicon and magnesium at a ratio of 1:1.2 and put them in a high-temperature resistant container;

[0066] (2) Put the container in a tube furnace filled with inert gas and heat it to 500°C at a heating rate of 10°C / min. The holding time is 4h to obtain the product silicon-magnesium compound mixture. After the product is cooled to room temperature with the furnace, take it out;

[0067] (3) Put the product obtained in (2) into NH 3 In the atmosphere, heat up to 850°C at a heating rate of 3°C / min, hold for 6 hours, and take out the product after cooling to room temperature with the furnace;

[0068] (4) Wash the product obtained in (3) with 1M nitric acid to remove magnesium nitride, wash, centrifuge, and dry to obtain high-purity silicon with a purity of 99.15%....

Embodiment 3

[0070] A method for purifying silicon by phase separation dealloying, comprising the steps of:

[0071] (1) Put metallurgical ferrosilicon powder (with a Si content of 80%) and magnesium powder into a high-temperature-resistant container after being evenly mixed according to the mass ratio of silicon and magnesium at a ratio of 1:1.6;

[0072] (2) Put the container in a tube furnace filled with inert gas and heat it up to 650°C at a heating rate of 15°C / min. The holding time is 8h to obtain the product silicon-magnesium compound mixture. After the product is cooled to room temperature with the furnace, take it out;

[0073] (3) Put the product obtained in (2) into NH 3 In the atmosphere, heat up to 800°C at a heating rate of 10°C / min, hold for 5 hours, and take out the product after cooling to room temperature with the furnace;

[0074] (4) Wash the product obtained in (3) with 1M sulfuric acid to remove magnesium nitride, wash, centrifuge, and dry to obtain high-purity silic...

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Abstract

The invention belongs to the technical field of purification of silicon, and particularly relates to a method for purifying silicon through a phase separation and dealloying reaction method. Firstly,a silicon raw material containing metal or non-metal impurities is mixed with magnesium powder, and then a sufficient reaction is carried out under the inert atmosphere, so that silicon atoms in the silicon raw material react with magnesium to be converted into magnesium silicide, and the impurities in the silicon raw material are separated from silicon to obtain a first product; then the first product is subjected to a nitridation reaction under the nitrogenous atmosphere, the magnesium silicide in the first product is converted into liquid-phase magnesium nitride at the reaction temperature,silicon separates crystals from the liquid-phase magnesium nitride, three-dimensional porous silicon and magnesium nitride distributed in pore passages of the three-dimensional porous silicon are formed, and a second product is obtained; in the process of separating out the crystals by the silicon, the impurities are further separated and dissolved in the liquid-phase magnesium nitride; finally,the second product is treated through acid pickling, wherein the magnesium nitride and the impurities are dissolved and converted into a solution, and a solid product is high-purity porous silicon.

Description

technical field [0001] The invention belongs to the technical field of silicon purification, and more specifically relates to a method for purifying silicon by phase separation dealloying. Background technique [0002] High-purity silicon is an important basic material for the photovoltaic industry, electronic information industry, lithium-ion battery, semiconductor and national defense industries, especially the demand for solar-grade silicon is huge, and its purity is generally 99.99-99.9999%. The raw material for preparing solar grade silicon is metallurgical grade silicon, and the purity of metallurgical grade silicon is generally 98-99.5%. The chemical method is a common method for the production of industrialized high-purity silicon, mainly including the Siemens method and the improved Siemens method. The main principle of this method is to react silicon with chlorine to convert it into low-boiling silicides such as trichlorosilane, etc. , purified by rectification an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
CPCC01B33/037C01B33/039C01P2002/72C01P2004/04C01P2006/80
Inventor 霍开富高标安威力
Owner WUHAN UNIV OF SCI & TECH
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