Method for recovering silicon carbide and polyglycol cutting solution from silicon slice cutting waste mortar

Abstract

The invention relates to a method for recovering silicon carbide and polyglycol cutting solution from a silicon slice cutting waste mortar. The method comprises the following steps of: stirring the mortar at normal temperature, and then performing solid-liquid separation to obtain a lower liquid stream and an upper liquid stream; putting the lower liquid stream into a belt filter to obtain cleaned silicon carbide; rinsing the silicon carbide by using alkali liquor, and driving the silicon carbide into a centrifuge; cleaning the silicon carbide through the belt filter, then rinsing the silicon carbide by using oxalic acid, and driving the silicon carbide into a three-level hydrocyclone to obtain a lower liquid stream of the silicon carbide; putting the lower liquid stream of the silicon carbide into a third belt filter; conveying the cleaned silicon carbide into a drying machine through a conveyor belt; grading the dried silicon carbide by wind force, screening large granular impurities by using a vibrating screen to ensure that the silicon carbide can be packaged; performing solid-liquid separation on the liquid part obtained after separating the mortar; adding a decolorant and a filter aid into the liquid; putting the mixture into a press filter; putting the separated liquid into an ion exchange system after the separated liquid passes through a bag filter; and dehydrating the separated liquid through an evaporator to obtain polyglycol. By the method, the pollution to the environment caused by the direct emission of the mortar is avoided, and the production cost during silicon slice cutting is effectively reduced.

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, semiconductors, solar cells, etc. all use silicon wafers as the basic carrier, and silicon carbide and polyethylene glycol are the components of the cutting fluid during the process of cutting silicon rods into silicon wafers , the silicon carbide and polyethylene glycol extracted from the cut mortar can be directly recycled in the silicon wafer cutting process. [0003] Silicon carbide (SiC), also known as moissanite, is the most widely use...

AI Technical Summary

Problems solved by technology

The price of new silicon carbide and polyethylene glycol is very expensive, but the price of silicon carbide and polyethylene glycol products obtained through the recycling technology of this invention is only half of the new product or even lower, and its use effect is the same as that of new silicon carbide , there is no difference in the use effect of polyethylene glycol, so it will bring very considerable economic benefits to a large number of silicon wafer cutting enterprises; at present, there is no mature set of offline recycling, silicon carbide, polyethylene glycol systems in the world

[0009] At present, the known silicon chip cutting waste liquid recovery technology is mainly based on simple chemical treatment methods, especially the recovery of silicon carbide. The application number: 200710117665.0, the invention name is "a single crystal and polycrystalline silicon wire cutting mortar recovery technology" The recovery method disclosed in the patent application of the invention: "Reduce the waste mortar to PEG liquid and SiC powder solid,...waste mortar stock solution → primary membrane filtration → PEG liquid; waste mortar stock solution → primary membrane filtration → cleaning treatment → powder drying → powder classification → SiC powder”, the drawbacks of the technical solution adopted for this invention patent application: excavate the pool on the ground, add acid and alkali to react, on the one hand, the acid and alkali water will gradually penetrate into the soil and damage the environment; on the other hand, the water in the pool The water cannot be reused, resulting in a large amount of waste water, increasing the burden on the environment; and recycling silicon carbide, the recovery rate is low, and the purity of silicon carbide is also low

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