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The method of intermediate frequency smelting to recover and polish silicon powder

A technology of intermediate frequency and silicon powder, which is applied in the field of intermediate frequency smelting, recycling and grinding silicon powder, which can solve the problems of inability to achieve removal effect and direct reuse, and achieve the effect of avoiding oxidation and improving yield

Active Publication Date: 2018-02-06
QINGDAO BLUE LIGHT NEW MATERIAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The silicon powder is rich in hard spots, which cannot be reused directly, and must be treated before it can be used
The traditional medium and low temperature roasting, directional purification and acid leaching methods cannot achieve good removal effect

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The method for recovering and grinding silicon powder by intermediate frequency smelting in this embodiment specifically includes the following steps:

[0031] (1) Select polysilicon ingot or purified top leather grinding powder as raw material and heat it with intermediate frequency coil. After the raw material is completely melted, add quartz sand at a speed of 1Kg / min. The mass ratio of the input material is polished silicon powder:quartz sand =100:1. Stir with a graphite rod and keep the temperature at 1650°C;

[0032] (2) After stirring for 10 minutes, remove the upper layer of quartz sand by a slag remover;

[0033] (3) Repeatedly add quartz sand once, and the mass ratio of feeding and grinding silicon powder:quartz sand=100:1, then stir with a graphite rod; after stirring for 5 minutes, remove the upper layer of fused silica sand to obtain high-purity silicon liquid;

[0034] (4) Pour the high-purity silicon liquid into a cooling bag for cooling to obtain a sil...

Embodiment 2

[0036] The method for recovering and grinding silicon powder by intermediate frequency smelting in this embodiment specifically includes the following steps:

[0037] (1) Select polysilicon ingot or purified top leather grinding powder as raw material and heat it with intermediate frequency coil. After the raw material is completely melted, add quartz sand at a speed of 2Kg / min. The mass ratio of the input material is: polished silicon powder: quartz Sand=150:1. Stir with a graphite rod and keep the temperature at 1750°C;

[0038] (2) After stirring for 20 minutes, remove the upper layer of quartz sand by a slag remover;

[0039] (3) Add quartz sand again, the mass ratio of the feed is: polished silicon powder: quartz sand = 150:1, stir with a graphite rod for 15 minutes and then add the quartz sand, the mass ratio of the feed is: polished silicon powder: quartz sand = 100: 1. Then, after stirring for 20 minutes with a graphite rod, remove the upper layer of fused silica san...

Embodiment 3

[0042] The method for reclaiming and grinding silicon powder by intermediate frequency smelting of the present invention specifically comprises the following steps:

[0043] (1) Select polysilicon ingot or purified ingot top skin grinding powder as raw material and heat it with intermediate frequency coil. After the raw material is completely melted, add quartz sand at a speed of 5Kg / min. The mass ratio of the input material is: polished silicon powder: quartz Sand=200:1. Stir with a graphite rod and keep the temperature at 1850°C;

[0044] (2) After stirring for 30 minutes, remove the upper layer of quartz sand by a slag remover;

[0045] (3) Add quartz sand again, the mass ratio of feeding is: polished silicon powder: quartz sand = 150:1, then stir with a graphite rod; after stirring for 20 minutes, remove the upper layer of fused silica sand to obtain high-purity silicon liquid;

[0046] (4) Pour the high-purity silicon liquid into a cooling bag for cooling to obtain a si...

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Abstract

The invention relates to a method for recovering polishing silicon powder through medium-frequency melting. According to the invention, polished powder of a top peel material produced by purified polysilicon cast ingots or purified ingots is used as a silicon material; the silicon material is subjected to induction heating by medium-frequency coils for melting so as to obtain silicon liquid; a slag adsorption agent is added to adsorb hard particles in the silicon liquid; then the slag adsorption agent rich in the hard particles is removed so as to obtain high-purity silicon liquid; and the high-purity silicon liquid is poured into a cooling package so as to obtain a silicon block. The method provided by the invention overcomes the problem that polysilicon rich in hard particles is difficult to melt at a high temperature. In an environment of high temperature, the high-temperature silicon powder is prevented from oxidation due to protection of the slag adsorption agent, so the silicon material without the hard particles is obtained, and top peel produced by polysilicon ingot casting / purification is recycled. The silicon material with low hard particle content obtained in the invention is free of enrichment of hard particles in subsequent ingot casting, which is favorable for improvement of the yield of cast ingots.

Description

technical field [0001] The invention relates to a method for recovering and grinding silicon powder by intermediate frequency smelting. technical background [0002] In recent years, due to the rapid development of the solar cell market, the demand for high-efficiency polycrystalline silicon ingots and purified ingots in the photovoltaic industry is increasing day by day. At the same time, during the ingot casting process, a large amount of polycrystalline ingot / purified ingot top skin will be produced. However, only a small portion of top hides can be directly reused. For most of the top leather materials, the surface layer can only be removed by grinding, and then pickled before they can be used again. [0003] The top skin material of polycrystalline ingot / purified ingot is rich in a large number of impurities and hard particles, common hard particles: SiC and Si 3 N 4 . The cause of SiC: During the high-temperature ingot casting process, a doping of the silicon melt...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
CPCC01B33/037
Inventor 方明李鹏廷谭毅姜大川张磊
Owner QINGDAO BLUE LIGHT NEW MATERIAL CO LTD