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Preparation method for silicon powder

A technology of silicon powder and silicon material, which is applied in the industrial silicon removal process of boron removal and the preparation of high-purity ultra-fine silicon powder, and the field of preparing silicon material for solar cells, can solve the problems of secondary metal pollution, increase processing cost, etc., and achieve broad application prospects. Effect

Inactive Publication Date: 2014-11-26
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Usually, the silicon liquid after slagging and refining is poured into the ingot mold to cool and solidify into large silicon ingots, and then pickling and impurity removal are carried out after crushing and grinding, which often causes secondary metal pollution and Increase processing cost
Therefore, the traditional slagging refining method has certain limitations

Method used

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  • Preparation method for silicon powder
  • Preparation method for silicon powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028]A metallurgical grade silicon material with a B content of 5.1 ppmw was taken and melted in a graphite crucible. Add slagging agent (sodium bicarbonate 50%, silicon dioxide 30%, sodium fluoride 20%) when the silicon material is melted, slagging and refining boron removal time is 0.5h, control the temperature in the graphite crucible at 1600 ° C ~ 1650 ° C, static Leave it on for 10-20 minutes. Remove the slagging agent floating on the upper layer of the silicon liquid; open the valve, the silicon liquid flows into the atomizer from the diversion tube, the diameter of the diversion tube is 5mm, control the air pressure of the atomizer outlet to 0.5MPa, the liquid outlet of the atomizer is connected to the acceptor The distance of the turntable is 0.3m. The boron content in the obtained silicon powder was 0.24ppmw. The average particle size of silicon powder is 55 μm.

[0029] Through comparative tests, the B content in silicon prepared by ordinary technology (same slag...

Embodiment 2

[0031] The process is the same as in Example 1, the difference is that the slagging agent formula is 40% sodium bicarbonate, 40% silicon dioxide, and 20% sodium fluoride. When slagging and refining boron removal, the temperature in the graphite crucible is controlled at 1650°C to 1700°C. ℃, slagging and refining time 1h, the diameter of the guide tube is 4mm, the air pressure at the gas outlet of the atomizer is controlled at 1MPa, and the distance between the liquid outlet of the atomizer and the receiving turntable is 0.5m. The boron content in the obtained silicon powder was measured to be 0.21 ppmw. The average particle size of silicon powder is 48 μm.

[0032] According to comparative tests, the boron content in silicon prepared by ordinary technology (same slagging refining temperature, time and formula) is 0.51ppmw. It can be seen that the boron content in the silicon powder obtained in this embodiment is significantly reduced.

Embodiment 3

[0034] The process is the same as in Example 1, the difference is that the slagging agent formula is 60% sodium carbonate, 32% silicon dioxide, and 8% sodium fluoride. During slagging, refining and boron removal, the temperature in the graphite crucible is controlled at 1650°C to 1700°C , slagging and refining time is 0.5h, the diameter of the guide tube is 6mm, the air pressure at the gas outlet of the atomizer is controlled at 1.5MPa, and the distance between the liquid outlet of the atomizer and the receiving turntable is 0.75m. The boron content in the obtained silicon powder was measured to be 0.19 ppmw. The average particle size of silicon powder is 41 μm.

[0035] According to comparative tests, the boron content in silicon prepared by ordinary technology (same slagging refining temperature, time and formula) is 0.49ppmw. It can be seen that the boron content in the silicon powder obtained in this embodiment is significantly reduced.

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Abstract

The invention discloses a preparation method for silicon powder, relates to a process of removing boron by industrial silicon and a preparation method for high-purity superfine silicon powder. The invention provides the preparation method for the silicon powder capable of remarkably reducing the content of the boron. The silicon powder can be used as an ideal low-boron material for a later process, namely pickling and impurity-removing process of purifying solar polycrystalline silicon by a metallurgy method. The preparation method comprises the following steps of: (1), adopting a metallurgical-grade silicon material as the material, putting the material silicon to a crucible, electromagnetically heating up the silicon material to melt the silicon material by an inductive coil; (2), adding a slag former to control the heating power when the silicon material is molten, so that the temperature of the molten silicon is kept to 1550 DEG C to 1850 DEG C in a reaction process, stewing the molten silicon to remove the slag former on the upper layer of the molten silicon after slagging and refining; and (3), controlling the temperature of the molten silicon to 1500 DEG C to 1700 DEG C, and then opening the valve and starting an atomizer; guiding the molten silicon to the atomizer by a guide tube, adjusting the air pressure of the air outlet of the atomizer so that the molten silicon is sprayed out of the atomizer in the forms of mists to enter an atomizing chamber; and collecting the silicon powder by a supporting rotary plate.

Description

technical field [0001] The invention relates to a process for removing boron from industrial silicon and a method for preparing high-purity ultrafine silicon powder, in particular to a method for preparing silicon powder suitable for preparing silicon materials for solar cells. Background technique [0002] Facing the increasingly severe energy crisis and environmental degradation, governments of various countries are scrambling to focus on the development of new energy sources. my country is one of the countries with rich reserves of solar energy resources. The area with annual sunshine hours greater than 2,000 hours accounts for more than two-thirds of the total area of ​​the country. Solar power generation has great potential for development in my country. At present, solar cells mainly include crystalline silicon solar cells, thin-film solar cells, dye-sensitized solar cells, and quantum dot matrix solar cells. Among them, crystalline silicon cells account for more than...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
Inventor 罗学涛卢成浩方明陈娟黄柳青赖惠先李锦堂
Owner XIAMEN UNIV
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