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Method for removing phosphorus and boron from metallurgical-grade silicon

A technology of metallurgical grade silicon and silicon material, which is applied in the field of purification of metallurgical grade industrial silicon and can solve the problems of unspecified

Active Publication Date: 2012-06-27
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the metallurgical-grade silicon used in the experiments in this paper has not been subjected to slagging treatment, nor has it been pointed out that phosphorus and boron can be removed.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] 1. Slagging treatment

[0031] Break 20kg of silicon into lumps, wash it and put it into a crucible, and then mix 5kg of CaO 2 -CaF 2 -SiO 2 The slag is evenly covered on the silicon block. Clean the receiving funnel and the receiving crucible with alcohol. A mechanical pump is used for vacuum extraction. When the mechanical pump draws the vacuum in the furnace to 1000Pa, close the valve tightly, stop the pump, unscrew the intake valve, quickly fill the argon gas to 10000Pa, and then tighten the valve to stop the inflation. Start intermediate frequency heating to melt the mixture, and use a double colorimetric-infrared thermometer to control the temperature at 1600°C. After the mixture is completely melted, lower the aeration rod to a place 1 to 2 cm away from the surface of the silicon liquid to preheat for 5 minutes, use argon as the carrier, feed in 30% water vapor, and adjust the gas flow rate to 0.8 L / min, then ventilate The rod is inserted about 2cm away from...

Embodiment 2

[0038] 1. Slagging treatment

[0039] Break 15kg of silicon into chunks, put the cleaned and crushed chunks of silicon into the crucible, and then put 7.5kg of CaO 2 -CaF 2 -SiO 2The slag is evenly covered on the silicon block. Clean the receiving funnel and the receiving crucible with alcohol. A mechanical pump is used for vacuum extraction. When the mechanical pump draws the vacuum in the furnace to 1000Pa, close the valve tightly, stop the pump, unscrew the intake valve, quickly fill the argon gas to 10000Pa, and then tighten the valve to stop the inflation. Start intermediate frequency heating to melt the mixture, and use a double colorimetric-infrared thermometer to control the temperature at 1500°C. After the mixture is completely melted, lower the aeration rod to a place 1-2 cm away from the surface of the silicon liquid to preheat for 5 minutes, use argon as the carrier, feed in 30% water vapor, and adjust the gas flow rate to 0.9 L / min, then ventilate The rod is ...

Embodiment 3

[0046] 1. Slagging treatment

[0047] Break 15kg of silicon into chunks, put the cleaned and crushed chunks of silicon into the crucible, and then put 5kg of CaO 2 -CaF 2 -SiO 2 The slag is evenly covered on the silicon block. Clean the receiving funnel and the receiving crucible with alcohol. A mechanical pump is used for vacuum extraction. When the mechanical pump draws the vacuum in the furnace to 1000Pa, close the valve tightly, stop the pump, unscrew the intake valve, quickly fill the argon gas to 10000Pa, and then tighten the valve to stop the inflation. Start intermediate frequency heating to melt the mixture, and use a double colorimetric-infrared thermometer to control the temperature at 1600°C. After the mixture is completely melted, lower the aeration rod to a place 1-2cm away from the surface of the silicon liquid to preheat for 5 minutes, use argon as the carrier, feed in 30% water vapor, and adjust the gas flow rate to 1.0L / min, then ventilate The rod is ins...

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PUM

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Abstract

The invention provides a method for removing phosphorus and boron from metallurgical-grade silicon, which relates to the purification of metallurgical-grade industrial silicon. The provided method for removing the phosphorus and the boron from the metallurgical-grade silicon has the advantages of less investment, lower production cost, less environmental pollution and the like. The method comprises the following steps of: putting a bulk silicon material into a smelting furnace; smelting the bulk silicon material, and covering the bulk silicon material with a slag former to obtain a silicon block mixture; vacuumizing the smelting furnace until the pressure is between 800 and 1,200 Pa, and charging argon until the pressure is between 8,000 to 12,000 Pa; heating the silicon block mixture to be melted, introducing water vapor, pouring a melted mixture on a loading graphite crucible below a smelting crucible, and taking out the silicon material after being cooled; crushing and milling the silicon material after slag forming to obtain silicon powder; soaking the powdered silicon in hydrochloric acid; soaking the silicon powder after being soaked in the hydrochloric acid in dilute aqua regia; and soaking the silicon powder after being soaked in the dilute aqua regia in hydrofluoric acid to obtain the metallurgical-grade silicon without the phosphorus and the boron.

Description

technical field [0001] The invention relates to the purification of metallurgical-grade industrial silicon, in particular to a method for removing phosphorus and boron in metallurgical-grade silicon mainly used for preparing solar-grade polysilicon. Background technique [0002] With the advantages of cleanness, safety and abundant resources, solar power generation can effectively alleviate the problems of energy shortage and environmental pollution. Photovoltaic power generation is known as the most important new energy source in the 21st century. However, the solar-grade silicon (SOG-Si) required for photovoltaic power generation is mainly produced by chemical processes such as improved Siemens. Although the purity is high, its cost is also very high, and there are problems such as possible environmental pollution. Physical metallurgy is currently one of the most promising methods for developing low-cost solar cells. It is characterized by low cost and a purity of about 6N...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/037
Inventor 陈朝何发林陈文辉庞爱锁罗学涛
Owner XIAMEN UNIV
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