Process for preparing magnesium hydroxide and sodium sulfite by using magnesium sulfite

Abstract

The invention discloses a process for preparing a magnesium hydroxide product and a sodium sulfite product by using magnesium sulfite, mirabilite and calcium carbide slag as raw materials. The specific process comprises: acidifying magnesium sulfite to dissolve and release sulfur dioxide gas, neutralizing and oxidizing the acidifying liquid to remove insoluble residue, respectively adding a converting agent, ammonia water, sodium hydroxide and other magnesium precipitation agents to the magnesium salt solution to generate magnesium hydroxide precipitate, and carrying out solid-liquid separation to obtain the magnesium hydroxide product, wherein the filtrate is soluble ammonium sulfate, sodium sulfate, ammonium chloride or calcium chloride and returns to the process system so as to be recycled, or lime milk is continuously added to the ammonium sulfate and ammonium chloride solution to generate ammonia and gypsum so as to regenerate and recycle the ammonia; and introducing the sulfur dioxide gas into a suspension formed from mirabilite and lime milk, carrying out a reaction to convert into sodium sulfite and gypsum precipitate, and carrying out solid-liquid separation to obtain thesodium sulfite product, wherein the filter cake is washed to obtain the by-product gypsum. According to the present invention, the magnesium hydroxide product and the sodium sulfite product are prepared by using the solid waste, such that the production cost is low, and the environmental and economic benefits are significant.

Description

technical field [0001] The invention belongs to the field of chemical technology, and relates to a process for preparing magnesium hydroxide and sodium sulfite by using magnesium sulfite solid waste; more specifically, it is produced by using industrial solid waste such as magnesium sulfite, carbide slag, and sodium sulfate through double decomposition reaction. The process of magnesium hydroxide, sodium sulfite and by-product gypsum. technical background [0002] Magnesium desulfurization produces a large amount of magnesium sulfite industrial solid waste, molecular formula MgSO 3 ·6H 2 O, slightly soluble in water, has strong reducing properties, and will cause great harm to natural water bodies and organisms after being directly discharged into the environment; enterprises producing polyvinyl chloride by calcium carbide method and salt chemical enterprises produce a large amount of solid waste of carbide slag and mirabilite; carbide slag It is industrial solid waste pro...

AI Technical Summary

Problems solved by technology

[0013] The production process of the above-mentioned magnesium hydroxide and other magnesium-based compounds needs to consume a large amount of primary mineral resources and a variety of chemical raw materials, which leads to high production costs, new solid waste and irreparable damage to the ecological environment of the mining area.

[0014] Known sodium sulfite production process uses lye to absorb SO 2 To prepare sodium sulfite, the production process needs to consume a large amount of caustic soda or soda ash, resulting in higher production costs

[0015] The above-mentioned existing magnesium sulfite solid waste treatment technology and the production process of magnesium hydroxide and sodium sulfite products are restricted by factors such as high raw material cost, poor economy, and harsh process conditions. Obviously, the products have high energy consumption, large pollution, and poor economic benefits. defect

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