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Method for smelting silicon wafer cutting waste under micro-negative pressure

A silicon wafer cutting and micro-negative pressure technology, which is applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve the problems of complex process, low impurity removal rate, and intensified secondary oxidation of ultra-fine silicon powder.

Active Publication Date: 2020-10-20
KUNMING UNIV OF SCI & TECH
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  • Description
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Problems solved by technology

In the existing silicon wafer cutting waste directly into the furnace for smelting and adding slagging agent to assist smelting, different steps are required to achieve the separation of the silicon dioxide layer and the removal of aluminum and calcium impurities. The process is lengthy and complicated. It is difficult to accurately control the participation of oxygen in the process, but it intensifies the secondary oxidation of ultrafine silicon powder, and the removal rate of impurities is low

Method used

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Examples

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Effect test

Embodiment 1

[0028] Embodiment 1: A kind of method for smelting silicon wafer cutting waste under slight negative pressure, the specific steps are as follows:

[0029] (1) The silicon wafer cutting waste in a certain place in Yunnan is subjected to induction melting, so that the bulk powder is melted into a high-temperature silicon liquid; in terms of mass percentage, the impurity content in the silicon wafer cutting waste is 6000ppm for Al and 3000ppm for Ca;

[0030](2) In order to further reduce Al and Ca, at the same time as step (1) induction smelting, micro-negative pressure smelting is carried out, and the fume collecting hood of the micro-negative pressure device is moved to the furnace mouth of the smelting device (induction furnace) through the lifting-rotating member Right above, so that the mouth of the fume collecting hood can cover the mouth of the furnace, and the vacuum device of the micro-negative pressure device (two-cascade mechanical vacuum pump) is turned on. The silico...

Embodiment 2

[0033] Embodiment 2: A kind of method for smelting silicon wafer cutting waste under slight negative pressure, the specific steps are as follows:

[0034] (1) The silicon wafer cutting waste in a certain place in Yunnan is subjected to induction melting, so that the bulk powder is melted into a high-temperature silicon liquid; in terms of mass percentage, the impurity content in the silicon wafer cutting waste is 11000ppm for Al and 3000ppm for Ca;

[0035] (2) In order to further reduce Al and Ca, carry out slagging smelting to the high-temperature silicon liquid of step (1) induction smelting; wherein the slagging agent is CaO, and the addition amount of CaO is 2kg / ton based on the quality of silicon chip cutting waste ; After adding the slagging agent CaO, pass through industrial compressed nitrogen, and the ventilation time is about 15 minutes;

[0036] (3) Carry out micro-negative pressure smelting while slagging and smelting in step (2), and move the fume-collecting hood...

Embodiment 3

[0039] Embodiment 3: A kind of method for smelting silicon wafer cutting waste under slight negative pressure, the specific steps are as follows:

[0040] (1) The silicon wafer cutting waste in a certain place in Yunnan is subjected to induction melting, so that the bulk powder is melted into a high-temperature silicon liquid; in terms of mass percentage, the impurity content in the silicon wafer cutting waste is 8000ppm for Al and 500ppm for Ca;

[0041] (2) In order to further reduce Al and Ca, the high-temperature silicon liquid induced in step (1) is subjected to combined smelting by gas blowing and slagging; the gas blowing is top blowing ventilation, the gas is industrial oxygen, and the ventilation time is about 10 minutes. The pressure is 1.2-2 atmospheres, and the gas flow rate is 0.2-1m 3 / s; the slagging agent is CaO, and the amount of CaO added is 1kg / ton based on the quality of silicon wafer cutting waste;

[0042] (3) Micro-negative pressure smelting is carried ...

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Abstract

The invention relates to a method for smelting silicon wafer cutting waste under micro-negative pressure, belonging to the technical field of silicon regeneration and recovery by pyrometallurgy of silicon wafer cutting waste. The invention aims to solve the problems that silicon powder is easy to oxidize in the smelting process and impurity removal efficiency is low in the smelting process due tothe existence of moisture in the pyrometallurgy silicon recovery process of silicon wafer cutting waste. According to the invention, a micro-negative pressure device is moved to a position over a smelting furnace opening, and a vacuum device of the micro-negative pressure device is started to enable silicon wafer cutting waste to undergo micro-negative pressure smelting, so oxidation loss of superfine silicon powder in the smelting process is avoided, volatile impurities in silicon are removed, and synchronous refining of silicon melt is achieved. According to the invention, a micro-negative pressure environment is created above the silicon melt, so smoke can be prevented from escaping in the silicon smelting process, and the environmental influence is reduced. The method is simple in equipment requirement, easy to operate, friendly to environment and suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to a method for smelting silicon wafer cutting waste under slight negative pressure, and belongs to the technical field of pyromelting silicon wafer cutting waste regeneration and recovery of silicon. Background technique [0002] Due to the use of additives and other auxiliary materials in the silicon wafer cutting process and the oxidation of cutting / storage and transportation, the impurities in the silicon wafer cutting waste are high in aluminum and calcium content and the surface oxidation degree of ultra-fine silicon particles is high. Generate a silicon dioxide layer to make the silicon wafer cutting waste regenerated and purified. In the process of preparing high-purity silicon, it is necessary to ensure the removal of impurity aluminum and calcium, and to avoid the contact between silicon particles and oxygen to the greatest extent during the smelting process to reduce the oxidation of silicon. loss. In the existing sili...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
CPCC01B33/037
Inventor 魏奎先杨时聪马文会万小涵李绍元伍继君
Owner KUNMING UNIV OF SCI & TECH
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