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Method for treating silicon in waste oil sand generated in silicon ingot cutting process

A treatment method, waste oil sand technology, applied in the direction of chemical instruments and methods, silicon carbide, silicon compounds, etc., can solve the problems of waste residue accumulation environment, complicated process flow, long treatment cycle, etc., achieve huge social and economic benefits, overcome The process is complicated, and the effect of solving waste residue accumulation and environmental pollution

Inactive Publication Date: 2012-09-26
JIANGNAN UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] The technical problem to be solved by the present invention is to overcome the existing defects and provide a method for treating silicon in silicon ingot cutting waste oil sands, which can overcome the complicated process flow, low efficiency, and energy consumption in the current silicon recycling process. High, long processing cycle and serious environmental pollution, etc., and can effectively solve the social problems of waste residue accumulation and environmental pollution in the industry

Method used

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  • Method for treating silicon in waste oil sand generated in silicon ingot cutting process
  • Method for treating silicon in waste oil sand generated in silicon ingot cutting process

Examples

Experimental program
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Effect test

Embodiment 1

[0027] Add 100g of waste oil sand containing 15.7% silicon, add 2.0% lye (solid-to-liquid ratio 1:1), stir and wash at 65°C for 2 hours, and centrifuge. After separation, the liquid contains 10.2% silicon (silicon conversion rate 65%), iron, copper and other metals and a small amount of PEG. Add solid alkali to the liquid to a concentration of 2%, and repeat the cleaning of the above-separated waste oil sand solid for 3 times. After centrifugation, the liquid contains 15.5% silicon (the total conversion rate of silicon is 99%). Finally, the separated waste oil sand solids are washed with pure water, and the solid SiC is recovered by drying.

[0028] Add solid alkali to the cleaned liquid to a concentration of 2%, and it can still be used as a cleaning liquid to treat waste oil sands. The separated and cleaned liquid is recycled until the silicon concentration is about 30%, and the acidity is adjusted to obtain a stable silica sol.

Embodiment 2

[0030] Add 100g of waste oil sand containing 15.7% silicon, add 2.5% lye (solid-to-liquid ratio 1:3), stir and wash at 85°C for 3 hours, and centrifuge. The separated and cleaned liquid contains 11.9% silicon (silicon conversion rate 76%), iron, copper and other metals and a small amount of PEG. Add solid alkali to the liquid to a concentration of 2.5%, and repeat the cleaning of the above-separated waste oil sand solid twice. After centrifugation, the resulting cleaned liquid contained 15.5% silicon (total conversion of silicon was 99%). The separated solid was washed with pure water and dried to recover SiC. Add solid alkali to the cleaned liquid to a concentration of 2.5%, and it can still be used as a cleaning liquid to treat waste oil sands. The liquid is recycled until the silicon concentration reaches about 30%, and the acidity is adjusted to obtain a stable silica sol.

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Abstract

The invention provides a method for treating silicon in waste oil sand which is generated in a silicon ingot cutting process. The method comprises the following steps of: washing the waste oil sand in alkali liquor for a certain period of time in a countercurrent mode to dissolve silicon powder, a small amount of iron, copper and residual polyethylene glycol (PEG) in the waste oil sand; separating the mixture to obtain waste oil sand solid and liquid which is obtained after washing; adding alkali into the liquid which is obtained after washing till the solution reaches a certain concentration; washing the waste oil sand once again; repeating the steps of adding the alkali and washing the waste oil sand for several times; washing the waste oil sand by using pure water; separating to obtain silicon carbide (SiC) solid and liquid which is obtained after washing; drying the SiC, and recycling; adding the alkali into the liquid which is obtained after washing to obtain a washing solution for washing other waste oil sand; and when the concentration of the silicon in the liquid which is obtained after washing reaches the needed concentration, collecting, and thus obtaining silica sol. In the whole treatment process, materials are recycled in a closed mode, and the method is pollution-free, environment-friendly (waste water cannot be generated and discharged), low in consumption and economic. By the method, the defects of complex process flows, low efficiency, high energy consumption, long treatment cycle, severe environmental pollution and the like which commonly exist in the prior art of recycling the silicon are overcome, and the problems of the accumulation of waste residues and environmental pollution in industries are solved effectively.

Description

Technical field [0001] The present invention involves a method of cutting a silicon in a silicon in the silicon, which is a silicon recycling technology field. Background technique [0002] In recent years, photovoltaic materials technology and solar photovoltaic industries have developed rapidly worldwide. As a result, a large amount of demand for silicon wafers is required. A large number of single crystal silicon or polysilicon silicon ingot needs to be cut into silicon wafers that meet the requirements. [0003] The cutting process of the industrial silicon wafer is often used. During the online cutting process, some crystal silicon will be cut into silicon powder into the cutting material.Waste mortar).Silicon ingot cutting waste mortar is a gray -black substance that is mixed with liquid and solids. The liquid is composed of a large amount of polyethylene glycol (PEG) and a small amount of water and grinding assistant; solid (waste oil sand) includes diamond sand(SIC), sili...

Claims

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Application Information

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IPC IPC(8): C01B31/36C01B33/141C01B32/956
Inventor 丁玉强王娟朱振中王庆
Owner JIANGNAN UNIV
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