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Method for purifying polysilicon through silicon alloy slagging

A silicon alloy and polysilicon technology, which is applied in the field of polysilicon purification, can solve the problems of material circulation, prominent energy consumption, large amount of alloy usage, large consumption of reagents, etc., and achieves the effect of ensuring reuse, reducing melting temperature and reducing crucible loss.

Inactive Publication Date: 2013-04-03
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages are that the amount of alloy used is large, the consumption of reagents is large, and the problems of material circulation and energy consumption are prominent.

Method used

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  • Method for purifying polysilicon through silicon alloy slagging

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Comparison scheme
Effect test

Embodiment 1

[0021] Such as figure 1 Shown, a kind of brief flow process of the method for silicon alloy slagging purification polysilicon is:

[0022] The first step of alloying and smelting: aluminum with a total mass fraction of 50% and a purity of 99% and metallurgical silicon with a purity of 98% and a boron content of 50ppmw are used for alloying and melting at 1300°C under the protection of argon to obtain a silicon alloy , the resulting silicon alloy has a density of 3g / cm 3 ;

[0023] The second step of silicon alloy slagging smelting: the silicon alloy obtained in the first step is used as a raw material, and the alkaline slag agent Na 2 SiO 3 -CaO-TiO 2 According to the mass ratio of alkaline slag agent and silicon alloy of 5, it is heated and melted at a temperature of 1400°C to form a molten liquid, wherein the alkalinity of the alkaline slag agent is 1.2, and the density is 2.5g / cm 3 ;

[0024] The third step of separation and recovery: heat the molten liquid for 4 hour...

Embodiment 2

[0026] Such as figure 1 Shown, a kind of brief flow process of the method for silicon alloy slagging purification polysilicon is:

[0027] The first step of alloying and smelting: aluminum, iron and copper with a total mass fraction of 10% and a purity of 99.3% and metallurgical silicon with a purity of 98.7% and a boron content of 24ppmw are used for alloying at 1450°C under argon protection Melting to obtain a silicon alloy, the density of the obtained silicon alloy is 3.2g / cm 3 ;

[0028] The second step of silicon alloy slagging smelting: the silicon alloy obtained in the first step is used as a raw material, and the alkaline slag agent is selected as Na 2 SiO 3 -CaO-TiO 2 According to the mass ratio of basic slag agent and silicon alloy as 2, it is heated and melted at a temperature of 1300°C to form a molten liquid, wherein the alkalinity of the basic slag agent is 2.0, and the density is 3g / cm 3 ;

[0029] The third step of separation and recovery: heat the molten...

Embodiment 3

[0031] Such as figure 1 Shown, a kind of brief flow process of the method for silicon alloy slagging purification polysilicon is:

[0032] The first step of alloying and smelting: alloying aluminum, tin and titanium with a total mass fraction of 40% and a purity of 99.9% and metallurgical silicon with a purity of 99% and a boron content of 10ppmw at 1000°C under argon protection Smelting to obtain a silicon alloy, the density of the obtained silicon alloy is 6g / cm 3 ;

[0033] The second step of silicon alloy slagging smelting: the silicon alloy obtained in the first step is used as a raw material, and the alkaline slag agent Na 2 SiO 3 -CaO-TiO 2 According to the mass ratio of alkaline slag agent and silicon alloy of 0.5, it is heated and melted at a temperature of 1550°C to form a molten liquid after mixing, wherein the alkalinity of the alkaline slag agent is 1.8, and the density is 2.9g / cm 3 ;

[0034] The third step of separation and recovery: heat the molten liquid...

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Abstract

The invention belongs to the technical field of metallurgical purification, and particularly relates to a polysilicon purification method. The method comprises the following steps: performing alloying smelting on metal and metallurgical silicon to obtain a silicon alloy; adding basic slagging agent into the silicon alloy used as a raw material, slagging, smelting, and purifying; and finally, keeping the temperature of the melt, cooling, and separating according to density difference to obtain high-purity silicon, the slagging agent and the silicon alloy, wherein the slagging agent and the silicon alloy can be recovered and used repeatedly. By adding a small amount of metal element into the metallurgical silicon, the metal element and the silicon can be formed into the alloy melt, thus effectively lowering the smelting temperature in the slagging and purifying process and reducing the crucible loss; in the cooling process, impurities have fractional condensation effect between the silicon and the alloy melt, thus effectively lowering the boron impurity content in the primary silicon and improving the purifying effect; and finally, based on the density difference among the silicon, the alloy and the slagging agent, the three phases are separated, thus obtaining the high-purity polysilicon, ensuring that the silicon alloy and the slagging agent can be used repeatedly, and avoiding the reagent consumption and alloy element loss in the subsequent acid washing and purifying process.

Description

technical field [0001] The invention belongs to the technical field of metallurgical purification, in particular to a method for purifying polysilicon. Background technique [0002] As we all know, energy and environment are two major issues facing mankind today. With the depletion of traditional energy resources and the increasingly serious environmental problems caused by the burning of fossil fuels, human beings urgently need to develop clean and renewable energy. Solar cells use the photovoltaic effect to convert solar energy into electrical energy, which has the characteristics of clean and renewable energy and is widely favored by people. At present, the most widely used is the silicon battery. In order to ensure its photoelectric conversion efficiency, the purity of its important component silicon material needs to reach more than 6N. The preparation of polysilicon for solar cells has become one of the bottlenecks in the widespread application of solar technology. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 谭毅李亚琼李佳艳贾朋军
Owner DALIAN UNIV OF TECH
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