Medium smelting cohesion primary directional solidification process applied to purifying polycrystalline silicon

A medium smelting and directional solidification technology, used in the chemical industry, silicon compounds, sustainable manufacturing/processing, etc., can solve problems such as large expenditure costs and inability to remove metal impurities, reducing production costs, saving power consumption, Energy saving effect

Inactive Publication Date: 2014-02-05
QINGDAO XINSHIJI SOLAR ENERGY TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In the traditional metallurgical process flow, the dielectric melting process can only remove the B impurities in polysilicon, and has no effect on the removal of metal impurities, and a large amount of metal impurities will bring great pressure to the subsequent directional solidification process, so the directional The solidification process often needs to be repeated 1 or 2 times, resulting in a large expenditure cost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] (1) Material selection: 600kg of the silicon block to be purified is metallurgical grade silicon, the silicon content in the metallurgical grade silicon is 97.0-99.9wt%, and the impurity boron content is 10-20ppmw. The slag agent is commonly used silicon-calcium-based slagging agent, with a total amount of 2400kg, which is divided into two parts and used for two medium smelting processes, so that the ratio of silicon to slag in each medium smelting process is 0.5:1.

[0020] (2) Medium smelting: Add 240kg of slag agent and all the silicon blocks to be purified to the graphite crucible in the intermediate frequency induction heating furnace, control the heating power of 250KW to melt them all, and then add the remaining slag agent in 5 times for melting, and the melting temperature is 1600 ℃, the smelting time for each addition is 20min, after smelting, pour the upper layer of old slag into the heat-resistant cast iron mold; repeat the above medium smelting process once, ...

Embodiment 2

[0023] (1) Material selection: 600kg of the silicon block to be purified is metallurgical grade silicon, the silicon content in the metallurgical grade silicon is 97.0-99.9wt%, and the impurity boron content is 10-20ppmw. The slag agent is commonly used calcium-silicon slagging agent, with a total amount of 1000kg, which is divided into five parts and used for five medium smelting processes, so that the ratio of silicon to slag in each medium smelting process is 3:1.

[0024] (2) Medium smelting: Add 40kg of slag agent and all the silicon blocks to be purified to the graphite crucible in the intermediate frequency induction heating furnace, control the heating power of 300KW to melt them all, and then add the remaining slag agent in 3 times for melting, and the melting temperature is 1800 ℃, the smelting time for each addition is 30min, after smelting, pour the upper layer of old slag into the heat-resistant cast iron mold; repeat the above medium smelting process 4 times, and ...

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PUM

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Abstract

The invention belongs to the field of polycrystalline silicone purification, and in particular relates to a medium smelting cohesion primary directional solidification process applied to purifying polycrystalline silicon. The process comprises medium smelting which comprises the steps of reacting a to-be-purified silicon block with a slag remover to remove boron impurity in the silicon, the process is characterized in that a silicon solution is placed in a primary directional solidification device under atmospheric condition after the medium smelting is finished, the metal impurity in the silicon solution is gathered at the top to remove by adopting a manner of water-cooling and pulling an ingot at the bottom. The primary directional solidification process has the advantages of being short in period, high in production efficiency, simple in process, saving in energy and low in cost.

Description

technical field [0001] The invention belongs to the field of polysilicon purification, and in particular relates to a preliminary directional solidification process applied to the purification of polysilicon by medium smelting and joining. Background technique [0002] In today's world, the energy crisis and the pressure of environmental pollution coexist, and people urgently need clean, safe and sustainable new energy. As an energy source that meets such requirements, solar energy has always been the goal pursued by people. The earliest use of solar energy is the utilization of its thermal effect, but it is difficult to fully meet the needs of modern society. Until the discovery of the semiconductor photoelectric effect and the manufacture of solar cells, people found new ways to use solar energy. Silicon is the most ideal raw material for solar cells. The impurities in it mainly include metal impurities such as Fe, Al, and Ca and non-metallic impurities such as B and P. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
CPCY02P20/10
Inventor 张磊谭毅侯振海刘瑶
Owner QINGDAO XINSHIJI SOLAR ENERGY TECH CO LTD
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