Method for recovering silicon carbide and polyethylene glycol cutting fluid from waste silicon wafer cutting fluid

Abstract

The invention relates to a method for recovering silicon carbide and polyethylene glycol cutting fluid from waste silicon wafer cutting fluid. The method is characterized by comprising the following steps: stirring the waste cutting fluid at normal temperature and separating to obtain solid and liquid; adding pure water to the solid, stirring, smashing, adding alkali liquor for reacting, and transferring the obtained reaction product into a centrifugal separator to obtain silicon carbide liquid flow; adding acid liquor for reacting, and then transferring the obtained reaction product into the centrifugal separator to obtain clear silicon carbide liquid flow; cleaning and then transferring the clear silicon carbide liquid flow into a dryer for drying, screening by air classification and packaging; adding a decolorizer and a filter aid to the liquid part after solid-liquid separation, performing mechanical separation, adding the decolorizer and the filter aid again to the separated liquid, performing mechanical separation, filtering and desalinizing with an ion exchange system, and dewatering with a four-effect evaporation system to obtain the polyethylene glycol cutting fluid. The method of the invention can prevent environmental pollution caused by direct emission of the waste silicon wafer cutting fluid and effectively reduce the production cost for cutting silicon wafers.

Description

technical field [0001] The invention relates to recovery technology, in particular to a recovery method for silicon carbide and polyethylene glycol cutting fluid. Background technique [0002] Silicon wafer is the basic material of semiconductor, solar energy, liquid crystal display and other industries. It is divided into monocrystalline silicon wafer and polycrystalline silicon wafer. The raw material is single crystal silicon or polycrystalline silicon. , use a wire cutting machine to process silicon wafers of various specifications. During the cutting process, the suspension of silicon carbide and polyethylene glycol cutting fluid and the steel wire act on the silicon rod together to play a cutting role; from the waste cutting after cutting The high-quality silicon carbide and polyethylene glycol cutting fluid extracted from the liquid can be directly recycled for the silicon wafer cutting process. [0003] Silicon carbide (SiC) is also called moissanite. Among the non...

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Problems solved by technology

[0007] Extracting silicon carbide and polyethylene glycol cutting fluid from silicon wafer cutting mortar has great environmental benefits, social benefits and corporate benefits. If the cutting fluid after silicon wafer cutting is directly discarded, it will cause huge and irreversible damage to the environment. Pollution: Although there is a complete set of off-line recovery systems for silicon carbide and polyethylene glycol in the world, the energy consumption is high and the pollution is large

[0008] At present, the known silicon chip cutting waste liquid recovery technology is mainly based on simple chemical treatment methods, esp

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