Method for joint production of potassium sulphate and calcium chloride dihydrate

Abstract

The invention relates to a method for joint production of potassium sulphate and calcium chloride dihydrate. The method comprises the steps of 1, adding potassium chloride and sulfuric acid to a first reactor, and introducing superheated steam to the first reactor to generate potassium sulphate and vapor containing hydrogen chloride through reaction; 2, introducing the vapor containing hydrogen chloride to a second reactor to generate calcium chloride dihydrate and superheated steam through reaction with calcium oxide or calcium hydroxide, and circulating the superheated steam to the step 1. By the adoption of the method, high energy consumption during production of potassium sulphate and calcium chloride dihydrate is avoided, the byproduct hydrogen chloride is well utilized, and environment pollution is basically avoided.

Description

technical field [0001] The invention relates to a preparation method of potassium salt, in particular to a method for jointly producing potassium sulfate and calcium chloride dihydrate. Background technique [0002] Potassium sulfate is an important inorganic chemical raw material, which is mainly used in the agricultural field to provide fertilizers with potassium and sulfur elements necessary for crop growth. In addition, potassium sulfate can also be used as dye intermediates, spice additives and medical Laxatives etc. [0003] There are three main methods for the production of potassium sulfate. One is the conversion method of producing potassium sulfate by reacting sulfuric acid or sulfate with potassium chloride. The total amount of potassium sulfate produced by this method accounts for about 75% of the world's total production of potassium sulfate. This method is represented by the Mannheim method, which was born in Germany at the end of the 19th century. It is the e...

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Problems solved by technology

The patent application number CN201410833456.6 discloses a typical method for producing calcium chloride dihydrate, but because the concentration of the distillation waste liquid used is generally low, the evaporation of water in the concentration operation will be relatively large. At the same time, It is also impossible to directly extract the desired product during the concentration process, which leads to a series of subsequent redundant processes, such as washing and drying the crystals after concentration and crystallization.

[0014] The process of using acid and limestone to produce calcium chloride is more complicated than the process mentioned above, because in addition to the process mentioned above, it also involves the treatment of other reactants and products

For example, when hydrochloric acid reacts with limestone, in addition to the treatment of unreacted limestone slag, it also involves the treatment of unreacted hydrogen chloride in the process of concentration. Therefore, this method not only has higher technical requirements, but also has caused environmental safety. a degree of threat

[0015] Combining the production methods of calcium chloride mentioned above, it can be clearly found that there are major defects in it, such as high energy consumption in the concentration process, long process flow and the phenomenon of repeated energy consumption and energy being directly discarded and wasted

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