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Method for preparing silicon nitride by using recovery purification silicon wafer sawdust powder

A technology of silicon nitride and sawdust, which is applied in the field of preparing silicon nitride, can solve the problem of high consumption of additional silicon materials and achieve the effect of reducing costs

Inactive Publication Date: 2013-01-02
YANGZHOU AINO PV MATERIAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The resulting additional consumption of silicon materials is huge, becoming an important part of the cost of silicon wafer solar cells, and also brings a certain environmental load

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] The silicon sawdust powder separated and extracted from the waste mortar discharged from the SiC abrasive mortar wire saw when cutting silicon wafers was used as the raw material. The ICP-AES (plasma-coupled atomic spectrometer) analysis results of the main impurities are listed in Table 1.

[0024] Take 100 grams of the raw material powder, put it in a rotatable corundum tubular resistance furnace, feed ammonia gas, raise the temperature to 600°C, and keep it warm for 1 hour; Keep rotating at a speed of 3 revolutions per minute, and then cool to room temperature with the furnace; then raise the temperature to 1250°C, keep it warm for 2 hours, and then cool to room temperature with the furnace before taking it out of the furnace.

[0025] The product was measured by X-ray powder diffractometer as pure silicon nitride (Si 3 N 4 ), where α-Si 3 N 4 The ratio is 92% v.

[0026] Table 1 ICP-AES analysis results of the main impurities in the silicon sawdust powder raw ma...

Embodiment 2

[0029] The silicon sawdust powder separated and extracted from the waste mortar discharged from the SiC abrasive mortar wire saw when cutting silicon wafers was used as the raw material. The ICP-AES (plasma-coupled atomic spectrometer) analysis results of the main impurities are listed in Table 1.

[0030] Take 100 grams of the raw material powder, place it in a rotatable corundum tubular resistance furnace, feed nitrogen gas, raise the temperature to 800°C, and keep it warm for 3 hours; Keep rotating at a speed of 5 revolutions per minute, and then cool to room temperature with the furnace and take out the furnace; then take the obtained product powder and heat it up to 1350°C in another corundum tube furnace, keep it for 4 hours, and then cool to room temperature with the furnace and then come out of the furnace.

[0031] The product was measured by X-ray powder diffractometer as pure silicon nitride (Si 3 N 4 ), where α-Si 3 N 4 The ratio is 91% v.

Embodiment 3

[0033] The silicon sawdust powder separated and extracted from the waste mortar discharged from the SiC abrasive mortar wire saw when cutting silicon wafers was used as the raw material. The ICP-AES (plasma-coupled atomic spectrometer) analysis results of the main impurities are listed in Table 1.

[0034] Take 100 grams of the raw material powder, put it in a rotatable corundum tubular resistance furnace, pass in nitrogen-hydrogen mixed gas, raise the temperature to 1000°C, and keep it warm for 6 hours; then raise the temperature to 1200°C, keep it warm for 6 hours, The corundum tube keeps rotating at a speed of 30 revolutions per minute, and then cools to room temperature with the furnace; then raises the temperature to 1380°C, keeps it warm for 8 hours, and then cools to room temperature with the furnace and then comes out of the furnace.

[0035] The product was measured by X-ray powder diffractometer as pure silicon nitride (Si 3 N 4 ), where α-Si 3 N 4 The ratio is 95...

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Abstract

The present invention relates to a method for preparing silicon nitride by using recovery purification silicon wafer sawdust powder. The method is characterized by comprising the following steps: 1) adding silicon wafer sawdust powder to a container, introducing a protection gas, carrying out first heating under the protection of the protection gas, and carrying out a first thermal insulation treatment to obtain a powder A; 2) carrying out second heating on the powder A under the protection of the protection gas, carrying out a second thermal insulation treatment, and cooling to a room temperature to obtain a powder B, wherein the powder A is maintained to continuously rotate during the thermal insulation process; and 3) carrying out third heating on the powder B under the protection of the protection gas, carrying out a third thermal insulation treatment, and cooling to a room temperature to obtain the silicon nitride. With the method of the present invention, reasonable recovery utilization of a large amount of silicon wafer sawdust produced by photovoltaic industry can be achieved so as to reduce solar photovoltaic power generation cost.

Description

technical field [0001] The invention relates to a method for preparing silicon nitride by recycling and purifying sawdust powder of silicon wafers, which belongs to the field of modern photovoltaic industry. Background technique [0002] More than 85% of the modern photovoltaic industry is based on crystalline silicon wafer solar cells. The required monocrystalline silicon wafers or polycrystalline silicon wafers are cut from single crystal silicon rods or directionally solidified polycrystalline silicon ingots, respectively. At present, there are two silicon wafer wire cutting technologies in the industry: silicon carbide abrasive mortar combined with steel wire cutting technology and consolidated diamond wire saw cutting technology. Both technologies produce sawing kerfs equivalent to the thickness of silicon wafers, which are as high as 40-60%. The crystalline silicon becomes sawdust, which is discharged with the cutting fluid during the cutting process. The resulting ad...

Claims

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Application Information

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IPC IPC(8): C01B21/068B09B3/00
CPCY02W30/20
Inventor 周浪尹传强魏秀琴
Owner YANGZHOU AINO PV MATERIAL TECH
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