Method for removing impurity boron of metallurgical silicon by high-basicity refining agent

A technology of metallurgical grade silicon and refining agent, applied in the field of solar photovoltaic, can solve the problems of reducing the application requirements of solar cells, difficult boron content, etc., and achieve the effects of easy industrialization and application, good boron removal effect, and simple equipment.

Active Publication Date: 2013-05-01
KUNMING UNIV OF SCI & TECH
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Problems solved by technology

[0005] At present, the application of metallurgical grade silicon boron removal method is mainly slagging and refining, using simple SiO 2 -CaO binary slag is difficult to reduce the boron content to the application requirements of solar cells, while using other slagging agents, although a better boron removal effect can be achieved, but it needs to be used in combination with multiple slagging agents or multiple times. Slag process

Method used

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  • Method for removing impurity boron of metallurgical silicon by high-basicity refining agent

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Effect test

Embodiment 1

[0021] (1) Crush metallurgical-grade silicon with a boron content of 10ppmw into 30g of powder with a particle size of 150-200 mesh, and then mix 60g of high-alkalinity refining agent and metallurgical-grade silicon powder at a ratio of 2:1 to fully evenly, among which high The alkalinity refining agent is analytically pure CaO with a mass content of 50%, and analytically pure SiO with a mass content of 50%. 2 mixed powder;

[0022] (2) Put the mixed material obtained in step (1) into a graphite crucible with a silicon nitride coating on the inner wall, place the crucible in a quartz tube in an intermediate frequency induction furnace, and feed a flow rate of 15L / Min of argon protection, and use 50 ℃ / min to raise the temperature to 900 ℃, and then keep it for 30 minutes; Ensure that the liquid silicon melt is fully separated from the solid refining agent; finally cool down to room temperature at 50°C / min, then turn off the argon gas, and take out the sample;

[0023] (3) Us...

Embodiment 2

[0025] (1) Crush metallurgical-grade silicon with a boron content of 15ppmw into 30g of powder with a particle size of 150-200 mesh, and then mix 30g of high-alkalinity refining agent and metallurgical-grade silicon powder at a ratio of 1:1 to fully evenly, among which high The alkalinity refining agent is analytically pure CaO with a mass content of 40%, and analytically pure SiO with a mass content of 40%. 2 , 20% analytically pure K 2 CO 3 mixed powder;

[0026] (2) Put the mixed material obtained in step (1) into a graphite crucible with a silicon nitride coating on the inner wall, place the crucible in a quartz tube in an intermediate frequency induction furnace, and feed a flow rate of 20L / Min of argon protection, and use 50 ℃ / min to heat up to 1000 ℃, keep warm for 30 minutes to ensure that the K in the refining agent 2 CO 3 Fully decompose, metallurgical grade silicon is still solid at this time; then heat up to 1550°C at 15°C / min and hold for 2 hours, then cool d...

Embodiment 3

[0029] (1) Crush the bulk metallurgical grade silicon with a boron content of 22ppmw to 30g of powder with a particle size of 150-200 mesh, and then mix 90g of high alkalinity refining agent and metallurgical grade silicon powder at a ratio of 3:1 to fully evenly, among which the high The alkalinity refining agent is analytically pure CaO with a mass content of 40%, and analytically pure SiO with a mass content of 40%. 2 , 20% analytically pure K 2 CO 3 mixed powder;

[0030] (2) Put the mixed material obtained in step (1) into a graphite crucible with a silicon nitride coating on the inner wall, place the crucible in a quartz tube in an intermediate frequency induction furnace, and feed a flow rate of 15L / Min of argon protection, and use 50 ℃ / min to heat up to 1100 ℃, keep warm for 30 minutes to ensure that the K in the refining agent 2 CO 3 Fully decompose, metallurgical grade silicon is still solid at this time; then heat up to 1500°C at 15°C / min and hold for 3 hours...

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Abstract

The invention provides a method for removing impurity boron of metallurgical silicon by a high-basicity refining agent. The method comprises the following steps of: crushing and grinding the metallurgical silicon serving as a raw material; preparing the high-basicity refining agent from CaO, SiO2 and K2CO3 in a certain proportion; fully mixing silicon powder and the refining agent; placing the material in a medium-frequency induction furnace with Ar flow velocity of 5-20L/min, preserving heat at the temperature of 900 DEG C to 1100 DEG C for 30 minutes, then heating the material to 1420 DEG C to 1550 DEG C, preserving heat for 1 hour to 3 hours to remove boron and refine; then preserving heat at the temperature of 1400 DEG C to 1450 DEG C for 30 minutes to ensure that the impurity and the silicon are fully separated; and then cooling the material to obtain the refined silicon, wherein the removal rate of the boron is 97.2 percent. According to the method, the refining agent is obtained by adding high-basicity K2CO3 into CaO-SiO2, the method is more beneficial to removing the impurity boron of the metallurgical silicon, and has the advantages of innovation, good boron removal effect and high practicability, simple equipment, no need of complex blowing or a vacuum system, easiness in operation, simplicity in industrialization popularization and application, and can effectively reduce productive investment.

Description

technical field [0001] The invention belongs to the technical field of solar photovoltaics, and specifically relates to a method for removing impurity boron in metallurgical-grade silicon by using a high-alkalinity refining agent. Background technique [0002] Facing the decreasing of global traditional energy and its threat to human living environment, the development of new energy has become a top priority for human beings. Among the new energy sources, solar energy has attracted people's attention for its advantages of non-pollution and renewable. Therefore, the development of solar cell materials has also been developed rapidly. Silicon material is the most widely used solar cell material. The improved Siemens method is the main method to produce solar grade silicon, but this method has disadvantages such as large investment scale, high production cost, and serious pollution. Researchers have been trying to find a new method to produce solar-grade silicon materials at a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 伍继君马文会贾斌杰谢克强魏奎先周阳杨斌刘大春戴永年
Owner KUNMING UNIV OF SCI & TECH
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