Method for removing boron impurity from industrial silicon by using titanium-containing compound

A technology for titanium compounds and industrial silicon, applied in the fields of silicon compounds, chemical instruments and methods, inorganic chemistry, etc., can solve the problems of safety and environmental hidden dangers, high process energy consumption and high cost, and achieve low cost, stable chemical properties, and low cost. The effect of boron content

Inactive Publication Date: 2011-08-03
XIAMEN UNIV
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Problems solved by technology

At present, European and American countries mainly use the improved Siemens method to produce solar-grade polysilicon. However, this process consumes a l

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] 1) Take titanium dioxide, fluorite powder and silicon dioxide as raw materials and press TiO 2 (20%wt)-CaF 2 (15%wt)-SiO 2 (65%wt), a total of 10kg is fully mixed to make a slagging agent.

[0023] 2) Mix the above slag-forming agent with 150kg of industrial silicon thoroughly, and then press into tablets. Use the tablet machine to 6 Press Pa for 50s to form a cylindrical sheet with a diameter of 80mm and a thickness of 30mm, each with a mass of 300g.

[0024] 3) Pre-heat treatment of the compressed material, the pre-heating temperature is controlled at 1400 ℃, and then the furnace is vacuumed with a vacuum pump and a roots pump.

[0025] 4) After evacuating until the pressure is lower than 10Pa, use a breather rod to blow argon into the furnace. The blowing speed is 1.5L / min, the blowing time is 10min, and the stable power for controlling the intermediate frequency heating during the reaction is 80kW. The slagging time is 10 minutes.

[0026] The sample was analyzed by ICP an...

Embodiment 2

[0028] The process is the same as in Example 1. The slagging agent is in accordance with TiO 2 (25%wt)-CaF 2 (15%wt)-SiO 2 (60%wt), prepare 30kg, change the preheating temperature to 1450℃, change the blowing speed to 2L / min, blowing time to 20min, control the intermediate frequency heating and stabilize the power to 90kW during the reaction process, perform ICP analysis on the sample, and measure The boron content in the sample is 0.44 ppmw.

Embodiment 3

[0030] The process is the same as in Example 1. The slagging agent is in accordance with TiO 2 (25%wt)-CaF 2 (20%wt)-SiO 2 (55%wt) prepared 50kg, changed the preheating temperature to 1500°C, and changed the slagging time to 20min. The sample was analyzed by ICP, and the boron content in the sample was determined to be 0.41ppmw.

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Abstract

The invention provides a method for removing a boron impurity from industrial silicon by using a titanium-containing compound and belongs to the field of metallurgy. The method comprises the following steps of: mixing the industrial silicon and a slag forming constituent, adding the mixture into a graphite crucible and pre-heating the graphite crucible in a smelting furnace to the temperature of between 1,400 and 1,600 DEG C; vacuumizing the smelting furnace with a mechanical pump and a Roots pump in turn, heating the smelting furnace to the temperature of between 1,500 and 1,700 DEG C and controlling the frequency of a medium frequency power supply to between 80 and 120kW; and introducing gas into the smelting furnace, stirring, forming slag, pouring silicon liquid into a die after the slag is fully formed, and cutting impurities from the solidified silicon material to obtain the silicon material from which boron is removed. The slag forming constituent used in the method has a good effect; the distribution ratio can be over 5; and compared with the distribution ratio of a pure Ca slag forming constituent, the distribution ratio of the slag forming constituent is obviously improved. The content of the boron in the industrial silicon is obviously reduced. The method has a wide application prospect.

Description

Technical field [0001] The invention relates to a method for removing boron from industrial silicon, in particular to a method for removing boron impurities in industrial silicon by using a titanium-containing compound. Background technique [0002] Solar energy has the advantages of cleanliness and abundant reserves. The solar energy received on the earth each year is equivalent to about 35,000 times that of the solid, gas, and liquid fuels burned annually on the earth. How to effectively use solar energy has been a hot issue in scientific research for a long time. Among them, the solar cell technology that uses solar photovoltaics to convert light energy into electrical energy is one of the effective ways to solve the energy problem of the earth's increasingly crisis. [0003] Solar-grade polysilicon is the raw material for the production of solar photovoltaic cells, and its production cost has always been an important factor restricting the photovoltaic industry. At present, E...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 罗学涛卢成浩李锦堂黄平平吴浩张蓉傅翠梨
Owner XIAMEN UNIV
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