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Method for recovering silicon powder from monocrystalline and polycrystalline silicon linear cutting wastes by utilizing microporous membrane filter process

A microporous membrane filtration and cutting waste technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of long process flow, complicated operation, difficult recovery process, etc., and achieve simple process flow and high separation efficiency , the effect of improving the recovery rate

Active Publication Date: 2012-09-12
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above separation and recovery methods generally have a long process flow and complicated operations. The recovery cost of some methods is already greater than the value of the silicon powder itself, and the practicability is not strong.
If the silicon is converted from a simple substance to a compound, and then further into the original, it will make the recovery process more difficult
Although the common separation method can recover the silicon in the waste, it will use some toxic and polluting chemical reagents, causing pollution to the environment
[0006] To sum up, although silicon is the most valuable part of the monocrystalline silicon and polycrystalline silicon wire cutting waste slurry, there is currently no simple and mature separation technology that can regenerate it into solar-grade high-purity polysilicon

Method used

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  • Method for recovering silicon powder from monocrystalline and polycrystalline silicon linear cutting wastes by utilizing microporous membrane filter process
  • Method for recovering silicon powder from monocrystalline and polycrystalline silicon linear cutting wastes by utilizing microporous membrane filter process
  • Method for recovering silicon powder from monocrystalline and polycrystalline silicon linear cutting wastes by utilizing microporous membrane filter process

Examples

Experimental program
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Effect test

specific Embodiment 1

[0039] Put the mixed powder with polyethylene glycol removed in a ball mill and grind it for 15 minutes, then add water according to the liquid-solid ratio of 3:1, put it in an ultrasonic cleaner for 20 minutes, add water and adjust the pH value with sodium hydroxide solution 6. The liquid-solid ratio is 10:1. Put the mixed solution into a microporous membrane separation device with a pore size of 5 microns, take out the silicon-rich phase suspension, and put it into a microporous filter with a pore size of 2 microns. Secondary filtration is carried out in the membrane separation equipment to obtain the silicon-rich phase suspension and its pH value is adjusted to 1. The silicon powder settles rapidly and is dried and recovered; the silicon carbide-rich sediment is returned to the original mixed powder solution for recycling. It can be seen from the XRD pattern that only a small amount of silicon carbide is contained in the recovered silicon powder.

[0040]

specific Embodiment 2

[0041] Put the mixed powder with polyethylene glycol removed in a ball mill and grind it for 20 minutes, then add water according to the liquid-solid ratio of 3:1, put it in an ultrasonic cleaner for 15 minutes, add water and adjust the pH value with sodium hydroxide solution 8. The liquid-solid ratio is 10:1. Put the mixed solution into a tubular microporous membrane separation device with a pore size of 4 microns for filtration, take out the silicon-rich phase suspension and put it into a tubular microporous membrane with a pore size of 2 microns for separation Perform secondary filtration in the equipment to obtain the silicon-rich phase suspension and adjust its pH value to 1. The silicon powder is quickly agglomerated and filtered with a flat thin paper microporous membrane with a pore size of 1 micron to quickly recover the fine powder in the silicon-rich phase. ; Rich silicon carbide deposits are returned to the original mixed powder solution for recycling. Its XRD resu...

specific Embodiment 3

[0043]Put the mixed powder with polyethylene glycol removed in a ball mill and grind it for 20 minutes, then add water according to the liquid-solid ratio of 3:1, put it in an ultrasonic cleaner for 15 minutes, add water and adjust the pH value with sodium hydroxide solution 7. The liquid-solid ratio is 10:1. Put the mixed solution into a flat paper thin paper microporous membrane separation device with a pore size of 3 microns for filtration, take out the silicon-rich phase suspension and put it into a flat paper thin paper microporous membrane with a pore size of 1 micron. Secondary filtration is carried out in the filter membrane separation equipment to obtain the silicon-rich phase suspension and adjust its pH value to 1. The silicon powder settles rapidly and is dried and recovered; the silicon carbide-rich sediment is returned to the original mixed powder solution for recycling. Its XRD result is identical with embodiment one.

[0044]

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Abstract

The invention discloses a method for recovering a silicon powder from monocrystalline and polycrystalline silicon linear cutting wastes by utilizing a microporous membrane filter process. The method comprises the following steps of: (1) performing pretreatment on the cutting wastes; (2), adjusting surface potential in a suspension aqueous solution of a mixed powder; (3), performing a membrane separation process: putting a flat microporous membrane or a tubular microporous membrane of which the pore diameter is 3-5mum in filtration equipment; slowly pouring slurry with an adjusted specific pH value into the filtration equipment to obtain a silicon-rich phase suspension passing through the microporous membrane and silicon carbide-rich deposits; then, slowly adding the obtained silicon-rich phase suspension to flat microporous membrane or tubular microporous membrane equipment of which the pore diameter is 1-2mum for refiltering to obtain a secondary filtration silicon-rich phase suspension; and (4), adjusting the surface potential of a silicon-rich phase so as to rapidly recover the silicon powder.

Description

[0001] technical field [0002] The invention relates to a method for recovering silicon powder in monocrystalline silicon and polycrystalline silicon wire cutting waste by microporous membrane filtration. [0003] Background technique [0004] In recent years, the solar energy industry has entered a period of rapid development. The manufacture and production of solar cells have grown rapidly, and the output of monocrystalline silicon and polycrystalline silicon, which are the main raw materials of solar cells, has also developed surprisingly. Most factories currently process silicon cell wafers using multi-filament wire cutting technology. It is estimated that more than 30% of high-purity silicon will be lost in the process of cutting polysilicon into silicon wafers. Finally, in the formed wire cutting waste, about 20% of high-purity silicon, about 40% of silicon carbide, about 30% of polyethylene glycol and water, and about 5% of metal are mixed. At present, the market ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 黄凯朱鸿民刘苏宁
Owner UNIV OF SCI & TECH BEIJING
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