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Method for purifying and preparing silicon carbide powder from crystalline silicon cutting waste mortar

A technology of crystal silicon cutting and waste mortar, which is applied in the direction of silicon carbide and carbide, can solve the problems of low recovery rate, difficult recovery, and reduction of silicon carbide output, and achieve the effect of simplifying the process and reducing environmental pollution

Active Publication Date: 2013-10-23
HAINAN UNIVERSITY
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Problems solved by technology

[0006] However, the method of separately extracting silicon and silicon carbide in the mixture in the above-mentioned traditional recovery process complicates the recovery process and consumes a lot of resources such as acid and alkali.
Moreover, the recovery of silicon is very difficult. If the two are recovered separately, the recovery rate of silicon will be low, and the output of silicon carbide will also be reduced.

Method used

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  • Method for purifying and preparing silicon carbide powder from crystalline silicon cutting waste mortar

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specific Embodiment approach

[0028] The specific implementation method comprises the following steps:

[0029] (1) Weigh a certain amount of crystalline silicon cutting waste mortar, add a sufficient amount of organic solvent, and stir at room temperature to fully dissolve polyethylene glycol and organic solvent in the waste mortar to obtain a mixed solution.

[0030] (2) Filtrating the mixed solution to obtain a cutting waste slurry (mainly including trace metal elements, silicon and silicon carbide) from which polyethylene glycol, water and organic solvents have been removed.

[0031] (3) Add excess dilute acid to the obtained waste and stir in a water bath to fully react the dilute acid and metal elements to obtain a mixed solution containing metal salt, acid, silicon and silicon carbide.

[0032] (4) In order to wash away the metal salt and excess acid in the mixed solution, add enough deionized water to the mixed solution, stir, filter, put the filter cake in an oven to dry, and obtain a mixture of s...

Embodiment 1

[0037] Take 20g of cutting waste mortar, add 220ml of absolute ethanol, and stir for 0.5h. The resulting mixture was filtered, and the filter cake was taken in a beaker. Add 10% hydrochloric acid, stir in a water bath (85° C.) for 1.5 h, and filter to get the filter cake. The filter cake was placed in a drying oven and dried at 80°C for 2 hours. To obtain 13.4g of a mixture of silicon and silicon carbide, add 50g of glucose, take 400g of balls, and grind for 10h with a planetary ball. After ball milling, take the material and place it in a vacuum sintering furnace, and vacuumize it to 7.0×10 -3 After Pa, the temperature was raised to 1100°C at a rate of 15°C / min, held for 3 hours, and finally cooled down to room temperature naturally with the furnace, and decarbonized at 650°C to obtain 12.42g of high-purity silicon carbide.

Embodiment 2

[0039] Take 40g of cutting waste mortar, add 410ml of absolute ethanol, and stir for 0.5h. The resulting mixture was filtered, and the filter cake was taken in a beaker. Add 20% hydrochloric acid, stir in a water bath (75° C.) for 1 h, and filter to get the filter cake. The filter cake was dried in a drying oven at 95°C for 2 hours. To obtain 28g of silicon and silicon carbide mixture, add 8g of activated carbon, take 360g of balls, and stir ball mill for 15h. After ball milling, take the material and place it in a vacuum sintering furnace, and vacuumize it to 2.0×10 -2 After Pa, the temperature was raised to 1300°C at a rate of 15°C / min, kept for 2 hours, and finally cooled to room temperature naturally with the furnace, and carbon removal was carried out at 700°C to obtain 26.73g of high-purity silicon carbide.

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Abstract

The invention discloses a method for preparing silicon carbide powder by using crystalline silicon cutting waste mortar. The method comprises following concrete processes: firstly, adding an organic solvent to the crystalline silicon cutting waste mortar, dissolving polyethylene glycol in the waste mortar; filtering and drying a filter cake; then grinding the filter cake into powder; adding dilute hydrochloric acid to react, filtering after the reaction is complete, and removing trace metal impurities, so as to obtain mixed powder of silicon and silicon carbide; then adding excessive carbon source to the mixed powder; evenly mixing the powder in a mechanical milling manner; finally, carrying out thermal treatment on the mixed powder in vacuum or inert atmosphere within a certain temperature range, so that the silicon and the carbon are subjected to carbonization reaction; removing residual carbon in air after the reaction is complete; finally obtaining high-purity silicon carbide powder. By adopting the method, the complicated technological process in the traditional method for recovering the crystalline silicon cutting waste mortar is simplified; finally the silicon in the crystalline silicon cutting waste mortar is completely converted into silicon carbon by a simpler method; the resources are recycled; environmental pollution is also reduced.

Description

technical field [0001] The invention relates to a method for converting the mixture of silicon and silicon carbide obtained after purification of crystal silicon cutting waste mortar into silicon carbide powder. If all the main components in the waste mortar are converted into silicon carbide powder, it can be reused for cutting silicon wafers, and can also be used as a raw material for the production of silicon carbide and its composite ceramics. The invention belongs to the field of recovery and reuse of silicon chip cutting waste mortar in the solar photovoltaic industry. Background technique [0002] Silicon carbide is an important special ceramic raw material, which is widely used in industrial production. It is of great significance to "turn waste into treasure" from crystal silicon cutting waste mortar, and to purify it to prepare silicon carbide powder. [0003] Traditional crystal silicon cutting waste mortar is generally used to recover polyethylene glycol by dist...

Claims

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Application Information

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IPC IPC(8): C01B31/36C01B32/956
Inventor 向道平何雨翔杨昱桢丁雷李建保
Owner HAINAN UNIVERSITY
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