Method for recovering and recycling silicon slice cutting waste mortar

Abstract

The invention relates to a method for recovering and recycling silicon slice cutting waste mortar. The method is characterized by comprising the following steps of: 1, pre-treating: uniformly stirring raw mortar and water and performing solid-liquid separation by using a plate and frame type filter press; 2, recovering polyethylene glycol (PEG): adding a decoloring agent into filtered liquid, and performing plate and frame filtering; treating obtained filtrate by using ion exchange resin or a multiple-effect distiller; and performing reduced pressure distillation, rectification and fine filtering to obtain a PEG finished product; and 3, recovering silicon carbide: mixing filtered filter cakes and water according to a proportion of 1:(3-4), stirring to form mortar; separating the mortar by using a multi-stage cyclone; performing acid washing; separating by using the cyclone; filtering by using a belt filter; and drying to obtain the silicon carbide finished product. By the method, the separation amount is large, recovery rate is high, recovered PEG and silicon carbide have high quality, and the method saves energy and is environmentally-friendly.

Description

technical field [0001] The invention relates to a recycling method for silicon chip cutting waste mortar, which is mainly used for processing the waste mortar produced after silicon chip cutting, and recovering PEG and silicon carbide therein. Background technique [0002] With the depletion of non-renewable resources such as coal and oil, solar energy has received strong support from governments of various countries as a new energy source, and the solar photovoltaic industry has developed rapidly, and its related industries have also followed. Chip cutting manufacturers are also increasing rapidly, and a large amount of mixed mortar waste containing polyethylene glycol (PEG), silicon carbide (SiC), silicon powder, metal oxides, moisture, metal ions, free carbon, etc. is produced during the process of cutting silicon wafers , the resulting mortar cannot be disposed of in time, causing great pressure on enterprises and environmental protection. [0003] Chinese patent docume...

AI Technical Summary

Problems solved by technology

[0004] First of all, the solid-liquid separation of mortar by centrifugal equipment is too low to meet the expected production requirements, and the centrifugal equipment is easy to wear, the maintenance cost is high, and the maintenance time is too long;

[0005] Secondly, the conductivity of the PEG product liquid recovered by this method is 15-20 μs / cm, which cannot effectively reduce the conductivity of the recovered PEG product liquid, and its moisture content is high, so it is difficult to meet the actual conductivity required by customers. ≤6μs / cm cm, moisture content ≤ 0.5%;

[0006] Third, when treating solids, flotation oil is used for treatment, and new impurities are introduced, which increases the COD of sewage and increases the difficulty of final sewage treatment; and in the silicon carbide recovery step, it is necessary to use alkali washing to remove silicon powder in solids. The treatment cycle is long, the operation is cumbersome, and there is a lot of sewage discharge; the production cost is high due to the high material consumption

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