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Electrophoretic assistant slag forming and boron removing method

An electrophoresis and slag-making technology, applied in chemical instruments and methods, inorganic chemistry, non-metallic elements, etc., can solve the problems of easy introduction of impurities, poor boron removal effect, and large amount of slag, avoiding metal pollution and low cost. , the effect of reducing industrial waste

Active Publication Date: 2014-04-23
福建上杭兴恒硅品有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above patents use a large amount of slag, the boron removal effect is not good, and impurities are easily introduced

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) Take 100kg of industrial silicon and put it into a graphite crucible, turn on the melting switch of the intermediate frequency furnace, adjust the intermediate frequency power to completely melt the industrial silicon

[0028] into silicon liquid;

[0029] (2) Adjust the power of the intermediate frequency furnace, keep the temperature of the above silicon liquid at 1500°C, add 50kg of slagging agent to the silicon liquid, of which Na 2 CO 3 30%, TiO 2 10%, the rest is SiO 2 ;

[0030] (3) Place the graphite plate on the upper surface of the molten silicon liquid, connect the graphite plate to the negative pole of the external DC voltage, connect the graphite crucible to the positive pole of the external DC voltage, and apply a 10V DC voltage to the graphite crucible for 6 hours to make the reaction The slag and metal impurities migrate to the negative electrode;

[0031] (4) Keep the temperature of the silicon liquid at 1450°C. Under the energized state, the g...

Embodiment 2

[0033] (1) Take 100kg of industrial silicon and put it into a graphite crucible, turn on the melting switch of the intermediate frequency furnace, and adjust the intermediate frequency power to completely melt the industrial silicon into silicon liquid;

[0034] (2) Adjust the power of the intermediate frequency furnace, keep the temperature of the above silicon liquid at 1650°C, add 70kg of slagging agent to the silicon liquid, of which Na 2 CO 3 35%, TiO 2 15%, the rest is SiO 2 ;

[0035] (3) Place the graphite plate on the upper surface of the molten silicon liquid, connect the graphite plate to the negative pole of the external DC voltage, connect the graphite crucible to the positive pole of the external DC voltage, apply a 50V DC voltage to the graphite crucible for 3 hours, and make the reaction The slag and metal impurities migrate to the negative electrode;

[0036] (4) Keep the temperature of the silicon liquid at 1500°C. Under the energized state, the graphite ...

Embodiment 3

[0038] (1) Take 100kg of industrial silicon and put it into a graphite crucible, turn on the melting switch of the intermediate frequency furnace, and adjust the intermediate frequency power to completely melt the industrial silicon into silicon liquid;

[0039] (2) Adjust the power of the intermediate frequency furnace, keep the temperature of the above silicon liquid at 1800°C, add 100kg of slagging agent to the silicon liquid, of which Na 2 CO 3 40%, TiO 2 20%, the rest is SiO 2 ;

[0040] (3) Place the graphite plate on the upper surface of the molten silicon liquid, connect the graphite plate to the negative pole of the external DC voltage, connect the graphite crucible to the positive pole of the external DC voltage, and apply a 100V DC voltage to the graphite crucible for 2 hours to make the reaction The slag and metal impurities migrate to the negative electrode;

[0041] (4) Keep the temperature of the silicon liquid at 1550°C. Under the energized state, the graph...

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PUM

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Abstract

The invention relates to the field of purification of solar grade polycrystalline silicon, and in particular to an electrophoretic assistant slag forming and boron removing method. The method comprises the steps of: filling raw material silicon to a graphite crucible and completely melting silicon to a silicon liquid; maintaining temperature of the silicon liquid at 1500-1800 DEG C, and adding a slag former to the silicon liquid to form slag; applying a direct current voltage to the silicon liquid in the graphite crucible so as to transfer borides and metal impurities after reaction to the cathode; carrying out directional solidification on the silicon liquid and cooling and taking out a silicon ingot as well as incising the upper impurity enriching area to obtain purified polycrystalline silicon. According to the method provided by the invention, a part of metal impurities is removed while the borides are removed. The use level of the slag former is reduced, the cost is lowered, and the industrial waste is reduced.

Description

technical field [0001] The invention relates to the field of purification of solar-grade polysilicon, in particular to an electrophoresis-assisted slagging and boron removal method. Background technique [0002] In today's background of increasing energy shortage and increasingly serious environmental pollution, solar photovoltaic power generation has become one of the most promising clean energy sources for large-scale application in the 21st century due to its mature technology, inexhaustible resources, and small environmental burden. It has attracted the attention of countries all over the world. Polysilicon is known as "the blood of modern industry, the cornerstone of the microelectronics information industry", and is the basic raw material and strategic material for the development of electronics and solar photovoltaic industries. [0003] At present, there are mainly chemical and metallurgical methods for the purification of polysilicon. Chemical methods mainly inclu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
Inventor 李伟生龚炳生陈晓萍
Owner 福建上杭兴恒硅品有限责任公司