Method for purifying byproduct sodium chloride in organic silicon high-salinity wastewater

Abstract

The invention discloses a method for purifying a byproduct sodium chloride in organic silicon high-salinity wastewater. The method comprises a high-salinity wastewater pretreatment stage and an MVR (mechanical vapor recompression) evaporation stage. The high-salinity wastewater pretreatment stage comprises oil-water separation, Fenton reaction, pulse electrocoagulation reaction and clarification separation; and the MVR evaporation stage comprises the following steps: (1) preheating clarified high-salinity wastewater, (2) carrying out primary evaporation concentration on the high-salinity wastewater to obtain concentrated saline water, (3) carrying out secondary evaporation concentration on the concentrated saline water to obtain a crystal slurry solution, and (4) crystallizing and drying: thickening the concentration of the crystal slurry solution, introducing the crystal slurry solution into a double-pusher centrifuge, carrying out solid-liquid separation, conveying sodium chloride crystals with the water content smaller than or equal to 5% obtained through solid-liquid separation to a drying bed through a spiral conveyor to be dried, and packaging the dried sodium chloride crystals enter a packaging machine to obtain a sodium chloride product. The method is scientific and reasonable, the content of pollutants in the organic silicon high-salinity wastewater can be reduced to the minimum, and the sodium chloride product is high in extraction rate and purity.

Description

technical field [0001] The invention belongs to the technical field of organosilicon production technology, and in particular relates to a method for purifying by-product sodium chloride from organosilicon high-salt wastewater. Background technique [0002] Silicone is an important link in the silicon industry chain. Silicone materials are widely used due to their excellent performance. Silicone production technology route Direct synthesis of methyl chlorosilane process, that is, using silicon powder and methyl chloride gas to react in the presence of a copper catalyst system to produce methyl chlorosilane mixed monomers, and the synthesized mixed methyl monomers are refined Distillation and separation of dimethyl dichlorosilane and other refined monomers. Dimethyldichlorosilane is hydrolyzed and cracked to produce dimethylsiloxane oligomers (DMC, D4), which are used as basic raw materials for further processing into various silicone polymerization products. A large amount...

AI Technical Summary

Problems solved by technology

A large amount of industrial wastewater will be produced in the above-mentioned organosilicon production process. The industrial wastewater mainly contains pollutants such as AOX, COD, BOD, SS, siloxane, etc. The industrial wastewater has complex components, high COD concentration, high salt content, and heavy metals. It has complex components, high toxicity, and poor biodegradability, and is one of the most difficult industrial wastewater to treat.

In the existing organic silicon wastewater treatment technology, the focus is mainly on the removal of COD, BOD and siloxane in organic silicon, while ignoring the large amount of salt contained in organic silicon wastewater. Effective treatment will not only affect the recycling of industrial wastewater, but also increase the difficulty of subsequent wastewater treatment, and cause waste of salt resources. Therefore, when extracting sodium chloride products from industrial wastewater, the current silicone wastewater treatment industry urgently needs to solve the problem one

At present, in the technology of extracting sodium chloride from organic silicon wastewater, most of the processes basically directly evaporate and concentrate organic silicon wastewater. Complicated, the extraction rate of sodium chloride in direct evaporation and concentration is low, the impurity content of sodium chloride is high, and the purity is relatively low; second, in the process of evaporation and concentration, industrial wastewater pollutants are likely to cause problems such as structure and blockage of equipment, And in the process of evaporation and concentration, the saturated steam cannot be used twice, which will increase the operating energy consumption of the equipment and virtually increase the operating cost of the equipment

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