Method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid

Abstract

The invention discloses a method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid. The method comprises the following steps of: A) diluting the cutting waste liquid with water and stirring, extracting metal scarp iron from the mixture by using a magnet after ultrasonic processing; B) adding a flocculating agent into the mixture for centrifugal separation; C) diluting solid I with water, adding sodium hydroxide into the solution, heating the mixture to perform reaction, cleaning the mixture with the water, adding an acid into the mixture, and cleaning the mixture with the water to obtain a crude silicon carbide product; D) performing centrifugal separation on the crude silicon carbide product, and drying the crude product to obtain a finished silicon carbide product; and E) filtering the liquid, heating, evaporating and dehydrating the filtered liquid to obtain a finished polyethylene glycol product. In the scheme, the mixture is diluted first, so the recovery rate of the polyethylene glycol is improved. The silicon and iron content of the crude silicon carbide product and the consumption level of the acid and alkali are reduced by ultrasonic processing and iron removal. The method has the characteristics of reasonable process, environmental protection and the like.

Description

Technical field [0001] The invention relates to a waste liquid recovery method, more specifically a method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid. Background technique [0002] In the process of multi-wire cutting of silicon wafers, the main role of the cutting fluid is to disperse, suspend, lubricate, cool, improve cutting efficiency, and reduce cutting consumption. The main components of the existing silicon wafer cutting fluid are polyethylene glycol and silicon carbide. Therefore, the main components of the cutting waste liquid generated by the silicon wafer cutting are polyethylene glycol and silicon carbide, and also include a small amount of silicon chips (generally 2~ 5%) and trace metal iron. The existing recycling of polyethylene glycol and silicon carbide in the silicon wafer cutting waste liquid often has problems such as low recovery rate and low purity of the recycled polyethylene glycol and silicon carbide....

AI Technical Summary

Problems solved by technology

This method is easy to control, simple equipment, and low cost, but its existing problems are: one is that silicon carbide and silicon cannot be effectively separated; the other is that HNO 3 The mixed acid liquid treatment method composed of +HF is likely to cause fluorine pollution; the above process needs to be further improved. If polyethylene glycol is to be evaporated, the temperature must be about 200°C under vacuum conditions, and the polyethylene glycol has deteriorated at this time Redness, loss of use value