Method and equipment for purifying polycrystalline silicon by directional solidification and filter slag melting

A directional solidification, polysilicon technology, applied in chemical instruments and methods, silicon compounds, sustainable manufacturing/processing, etc., can solve problems such as unfavorable popular application of solar cells, poor removal of impurities, and reduced reaction temperature. Good effect, low cost and large contact area

Inactive Publication Date: 2011-10-19
DALIAN LONGSHENG TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the improved Siemens method and silane method require large equipment investment, high cost, serious pollution, and complicated processes, which are not conducive to the popular application of solar cells. In comparison, the metallurgical method has the characteristics of short production cycle, low pollution, and low cost. The focus of R&D in various countries
Known application number is 201010215

Method used

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  • Method and equipment for purifying polycrystalline silicon by directional solidification and filter slag melting
  • Method and equipment for purifying polycrystalline silicon by directional solidification and filter slag melting

Examples

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Effect test

Embodiment 1

[0025] A method for directional solidification and slag filtration smelting to purify polysilicon. First, melt the slag-forming agent in a melting crucible by induction heating and keep it in a liquid state. At the same time, melt high-boron and high-metal polysilicon in a small crucible by another induction heating The polysilicon melt is formed from the material, and then the polysilicon melt is continuously and slowly introduced into the liquid slagging agent through the flow guide device and evenly dispersed in the liquid slagging agent, and the boron is removed by the reaction. Finally, when the liquid in the melting crucible is full, stop adding the polysilicon melt. Induction heating keeps the melting crucible in a liquid state. After a certain period of time, the ingot is pulled down by the ingot pulling mechanism for directional solidification, so that metal impurities and waste slag are enriched on the top of the melt until the liquid is completely solidified and dropp...

Embodiment 2

[0027] An equipment for directional solidification and slag filtration smelting and purifying polysilicon, the equipment is composed of a furnace door 23 and a vacuum furnace wall 2 to form a vacuum equipment, the inner cavity of the vacuum equipment is a vacuum chamber 24; the left side of the bottom of the vacuum chamber 24 is fixed with a left support frame 14, the left heating device and the thermal insulation carbon felt 20 are installed on the left support frame 14, the ingot pulling mechanism and the melting crucible 16 are installed in the left heating device and the thermal insulation carbon felt, and the ingot pulling mechanism adopts the ingot supporting rod 13 to be installed in the vacuum furnace On the left side of the bottom of the wall 2, the graphite block 15 is installed on the ingot support rod 13, and the melting crucible 16 is installed on the graphite block 15; the right support base is installed on the right side of the bottom of the vacuum chamber 24, and...

Embodiment 3

[0029] Adopt the equipment described in embodiment 2 to carry out the method for directional solidification and slag filtration smelting purification polysilicon, its specific steps are as follows:

[0030] The first step of pretreatment: convert the mass percentage to SiO 2 60%, CaO25% and Na 2 CO 3 Put 1000g of 15% slagging agent in the melting crucible 16, and after closing the furnace door, use the mechanical pump 25 and Roots pump 26 to pump the vacuum chamber 24 to a low vacuum of 7Pa, and then use the diffusion pump 27 to pump the vacuum chamber 24 to a high vacuum 0.0018Pa; Pass cooling water into the ingot support rod 13 to keep its temperature at 40°C;

[0031] The second step is to melt the slag agent and silicon material: energize the left induction coil 18, melt the slagging agent by induction heating, and maintain the liquid state, and at the same time, continuously add boron content of 0.002% and metal impurities into the small crucible 6 through the feeding p...

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Abstract

The invention belongs to the technical field of purifying polycrystalline silicon by physical metallurgy technology. A method for purifying polycrystalline silicon by directional solidification and filter slag melting comprises the following steps: heating slag former in a melting crucible, keeping the slag former in a liquid state, simultaneously, melting polycrystalline silicon material with high boron and high metal in the other small crucible; introducing and dispersing polycrystalline silicon melt into the liquid slag former, conducting melting reaction to remove impurity boron, and when the melting crucible is fully filled with liquid, stopping adding polycrystalline melt, heating so as to lead the mixture in the melting crucible to be in a liquid state, conducting directional solidification on the mixture after melting, cutting polycrystalline silicon and waste residue with higher impurity content at the top of a silicon ingot, thus obtaining the polycrystalline silicon ingot with a lower boron and metal impurity content. The impurity boron and metal in the polycrystalline silicon are removed by filter slag melting and directional solidification, therefore, the purity of the polycrystalline silicon is improved effectively, the using requirement of solar silicon is achieved, the purifying effect is good, the technique is stable, the process is simple, the energy is saved, the cost is low and the production efficiency is high.

Description

technical field [0001] The invention belongs to the technical field of purifying polysilicon by physical metallurgy technology, and particularly relates to a method for removing boron and metal impurities in polysilicon; in addition, the invention also relates to its equipment. Background technique [0002] Solar-grade polysilicon material is an important raw material for solar cells. Solar cells can convert solar energy into electrical energy. In today's shortage of conventional energy sources, solar energy has great application value. At present, the preparation of polysilicon materials for solar cells has formed a large-scale production worldwide, and the current main technical routes are as follows: [0003] (1) Improved Siemens method: The Siemens method uses hydrochloric acid (or hydrogen, chlorine gas) and metallurgical grade industrial silicon as raw materials to perform hydrogen reduction from trichlorosilane. Now the relatively mature technology in foreign countri...

Claims

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Application Information

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IPC IPC(8): C01B33/037
CPCY02P20/10
Inventor 谭毅战丽姝顾正
Owner DALIAN LONGSHENG TECH CO LTD
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