Method for preparing potassium sulfate with co-products of aluminum sulfate and ferric sulfate by using alum sludge hydrolysis filtrate

Abstract

The invention discloses belongs to the technical field of treatment and comprehensive utilization of three wastes (waste gas, waste liquid and waste residues) in the inorganic chemical industry and particularly relates to a method for preparing potassium sulfate with co-products of aluminum sulfate and ferric sulfate by using alum sludge hydrolysis filtrate. The method mainly comprises the steps of: fully hydrolyzing alum sludge with water to generate a mixture of water-soluble substances such as potassium sulfate, ferric sulfate, aluminum sulfate and the like, filtering the mixture to obtain filtrate, conveying the filtrate to a corrosion-resistant reduced pressure distiller for reduced pressure distillation, and distilling the filtrate to obtain saturated distillate so as to obtain crystallized products of the potassium sulfate, the ferric sulfate and the sodium sulfate respectively according to different condensation points of the three substances. The method provided by the invention not only can be used for completely eliminating waste residues and alleviating the pollution of the waste residues to the environment, but also can be used for preparing valuable products of the potassium sulfate, the ferric sulfate and the sodium sulfate, has the advantages of obvious social and economic benefits and simple process and production equipment, and is a comparatively practical treatment and utilization method.

Description

technical field [0001] The invention relates to the technical field of treatment and comprehensive utilization of alum slurry waste liquid produced from alum, in particular to a method for preparing potassium sulfate and co-producing aluminum sulfate and iron sulfate from alum mud hydrolysis filtrate. technical background [0002] Alum is also known as potassium aluminum alum, potassium alum and potassium alum, and its chemical formula is K 2 SO 4 ·Al 2 (SO 4 ) 3 24 hours 2 O or KAl(SO 4 ) 2 24 hours 2 O. Alum is a double salt of potassium magnesium sulfate and aluminum sulfate containing crystal water. It is a colorless octahedral crystal with a sour taste. The density is 1.75 and the melting point is 92 degrees. It is easily soluble in water. It produces aluminum hydroxide colloidal precipitate; when it is heated, it loses crystal water and becomes a white powder, which is referred to as burnt alum. [0003] Alum is widely used in chemical industry, food, daily c...

AI Technical Summary

Problems solved by technology

The main components of alum mud and the production of alum slurry are not much, mainly including silicon dioxide content of 22.48%, ferric oxide content of 2.29%, aluminum oxide content of 43.03%, calcium oxide content of 2.97%, potassium oxide content of 4.44% %, and the content of sulfur trioxide is 15.52%. If there is no secondary pollution, these compounds must be fully utilized, and even several separate technological processes are required to digest all these substances. Treatment and utilization of pulp have been done, but secondary pollution has occurred after treatment

There are few types and low-grade products processed by treatment and utilization, and many elements and compounds have not been taken out; moreover, it is basically divided into several separate processes to digest all these substances; at present, there is no hydrolysis of alum mud Related reports on the method of preparing potassium sulfate from filtrate and co-producing aluminum sulfate and iron sulfate

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