Method for producing potassium dihydrogen phosphate with double decomposition method

Abstract

The invention relates to a method for producing potassium dihydrogen phosphates, in particular to a method for producing potassium dihydrogen phosphate with a double decomposition method. The invention is characterized by further improving the quality of a potassium dihydrogen phosphate product and enhancing the concentration of byproduct hydrochloric acid on the basis of the work of the previous period. The method comprises the following steps of: mixing potassium chloride powder with a phosphoric acid solution, carrying out double decomposition reaction in a spray tower, dissipating hydrogen chloride gas generated by the reaction along with hot air for preparing hydrochloric acid or chlorate; and hydrolyzing, neutralizing and crystallizing double decomposition reaction materials after the hydrogen chloride gas is dissipated to prepare a potassium dihydrogen phosphate product. By adopting the method, it is unnecessary to dissolve potassium chloride into phosphoric acid, it is only necessary for adequately mixing the potassium chloride solid powder with phosphoric acid, therefore, the reaction time is shortened, the production energy consumption is reduced, the production efficiency is improved, and the conversion rate is higher up to more than 99%; meanwhile, the concentration of by-product hydrochloric acid can reach above 25%, and can reach as high as 33%, and the recycling value is greater.

Description

technical field [0001] The invention relates to a method for producing potassium dihydrogen phosphate, in particular to a method for producing potassium dihydrogen phosphate by a metathesis method. Background technique [0002] There are many production methods of potassium dihydrogen phosphate, mainly neutralization method, extraction method, ion exchange method, metathesis method, direct method, crystallization method and electrolysis method. In my country, the neutralization method is mostly used in the production process, and the extraction method, metathesis method, ion exchange method, and direct method have not yet been industrialized. Although the neutralization method is simple, the potassium hydroxide is expensive, the production cost is high, and the added value is low; other methods such as potassium chloride and phosphoric acid metathesis low-temperature extraction method have serious loss of extractant, high price, and serious environmental pollution; phosphate...

AI Technical Summary

Problems solved by technology

Although this method solves the strong corrosion problem of hydrochloric acid and phosphoric acid mixed acid, it has the following two disadvantages: ①The core reactor adopts graphite reactor. Large diameter ratio, small effective volume, difficult to achieve mass production

② The hydrogen chloride gas produced by potassium chloride and phosphoric acid escapes from the liquid phase by stirring, the escape efficiency is low, and the conversion time of potassium chloride is long, reaching 1.5 to 4 hours, which seriously restricts the reaction rate and makes it difficult to realize large-scale industrial production

Compared with CN1324760A, although this method is easy to realize industrialized production, there are still deficiencies: 1. It is required to fully dissolve the chloride salt in phosphoric acid and then carry out the spray reaction, which relatively prolongs the reaction time and is unfavorable for the improvement of production efficiency

②Since the chloride salt is required to be dissolved in phosphoric acid, the concentration of phosphoric acid used is low, and the water evaporated during the spraying process is high, resulting in high energy consumption

③And due to the high moisture content in the material, the concentration of the by-product hydrochloric acid is low, and the recovery value is not great

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