A kind of wet-process phosphoric acid prepares tripotassium phosphate method

Abstract

The invention relates to the field of a technology for preparing tripotassium phosphate from wet-process phosphoric acid, especially relates to a method for preparing tripotassium phosphate from wet-process phosphoric acid. The method comprises the following steps: a content of sulfate radical in the wet-process phosphoric acid is analyzed, and rock phosphate is added, so that sulfate radical, iron ion and aluminium ion and other cations as well as fluorine ion, silicon ion and other anions form precipitation; ammonia gas or ammoniacal liquor is added, pH value is adjusted to 3-7, so that a solution of ammonium phosphate is formed, after filtering, the formed precipitation is left in the residue liquid by filtering, so that the wet-process phosphoric acid is purified, and the purity of the tripotassium phosphate produced by subsequent production is ensured. After a reaction between an ammonium phosphate slurry and potassium hydroxide or potassium bicarbonate or potash is carried out, an evaporative crystallization is carried out at a negative pressure of 0-0.01MPa, so that the quality of the tripotassium phosphate crystal is good, the purity is high, the consumption of potassium ions is reduced, the production cost is reduced, and resource waste is avoided.

Description

technical field [0001] The invention relates to the technical field of preparing tripotassium phosphate by wet-process phosphoric acid, in particular to a method for preparing tripotassium phosphate by wet-process phosphoric acid. Background technique [0002] Tripotassium phosphate, which is used in many fields, such as agriculture, etc.; its current production method is mainly the neutralization method, that is, after the reaction of phosphoric acid with potassium hydroxide or potassium bicarbonate, potassium carbonate, through the control of the reaction end point , and then concentrate the neutralized solution, remove the insoluble matter, and then cool it down to crystallize, centrifuge and dry to obtain the product. However, since phosphoric acid is divided into hot-process phosphoric acid and wet-process phosphoric acid, wet-process phosphoric acid is mainly carried out by using phosphate rock and inorganic acid according to the principle of producing weak acid from s...

AI Technical Summary

Problems solved by technology

However, since phosphoric acid is divided into hot-process phosphoric acid and wet-process phosphoric acid, wet-process phosphoric acid is mainly carried out by using phosphate rock and inorganic acid according to the principle of producing weak acid from strong acid. root and other elements, such as calcium, form calcium sulfate insoluble matter, and then obtain it by filtration; however, because the quality of phosphate rock will affect the quality of wet-process phosphoric acid, the quality of phosphoric acid products prepared by wet-process phosphoric acid is unstable. Simultaneously, also make the impurity content in the phosphoric acid obtained be higher, purity is lower, make when using the phosphoric acid prepared by wet-process phosphoric acid to produce potassium phosphate product, it not only can make the purity of potassium phosphate lower, the quality is unstable At the same time, the potassium ions in the added potassium hydroxide or potassium carbonate and potassium bicarbonate interact with other impurity elements during the preparation process to form insoluble matter, which in turn causes waste of potassium ions, resulting in potassium hydroxide, potassium carbonate or The addition amount of potassium bicarbonate increases, and then causes preparation cost higher, resource consumption is bigger