Method for producing fertilizer monopotassium phosphate by phosphoric acid by semi-hydrated process and wet process

Abstract

The invention discloses a method for producing a fertilizer monopotassium phosphate by phosphoric acid by a semi-hydrated process and a wet process. The method is characterized by comprising the following process steps of: adding phosphoric acid by the semi-hydrated process and the wet process into powdered rock phosphate to carry out desulfurization, filtering desulfurized slurry, feeding filter residues into a phosphoric acid system, introducing filtrate into a primary neutralizing tank, adding potassium hydroxide into the primary neutralizing tank to neutralize the filtrate, and regulating the pH value of the primary neutralized slurry to be 2.0-2.5. The method has the beneficial effects that the phosphoric acid by the semi-hydrated process and the wet process and dry ground phosphorite react for desulfurization, so that SO4<2-> of the phosphoric acid by the semi-hydrated process and the wet process is reduced while 2-5% of CaO is dissolved. Dosage of potassium hydroxide for primary and secondary neutralization and impurity removal can be reduced. Phosphor and potassium are sufficiently utilized, so that the yield of P2O5 is increased; mother liquor subjected to tertiary neutralization and filtration is returned to preparation water of potassium hydroxide subjected to primary and secondary neutralization, so that water consumption in a production process is reduced; and meanwhile, residual phosphor and potassium in the mother liquor are recycled, so that the phosphor and the potassium are sufficiently utilized, and therefore, the yields of the phosphor and the potassium are increased.

Description

technical field [0001] The invention belongs to the field of phosphorus chemical industry, in particular to potassium dihydrogen phosphate (KH 2 PO 4 )Methods. Background technique [0002] Potassium dihydrogen phosphate (KH 2 PO 4 ) is a large branch of phosphate, potassium dihydrogen phosphate is an important product of phosphate, pure potassium dihydrogen phosphate is potassium oxide (K 2 O) 34.60%, phosphorus pentoxide (P 2 o 5 )52.20%. Potassium dihydrogen phosphate is a colorless or white lustrous orthorhombic crystal, soluble in water, showing acidic reaction, insoluble in alcohol. Potassium dihydrogen phosphate is a high-quality high-quality phosphorus-potassium compound fertilizer. The traditional process generally uses neutralization and double decomposition. The neutralization process is simple, but the cost of raw materials used is expensive, and it is difficult to produce potassium dihydrogen phosphate for agriculture. Promoted in China; the metathesis m...

AI Technical Summary

Problems solved by technology

Potassium dihydrogen phosphate is a high-quality high-quality phosphorus-potassium compound fertilizer. The traditional process generally uses neutralization and double decomposition. The neutralization process is simple, but the cost of raw materials used is expensive, and it is difficult to produce potassium dihydrogen phosphate for agriculture. Promoted in China; the metathesis method mainly uses potassium chloride and phosphoric acid to carry out the metathesis reaction, and the reaction can be carried out by removing the hydrogen chloride gas generated by the reaction. This method has problems such as high energy consumption and excessive chloride ion content in the product.

In addition, the production process of potassium dihydrogen phosphate includes direct method, conversion method, organic extraction method, ion exchange method, etc., all of which have not been industrialized due to high raw material costs, high production costs, substandard product quality, and severe equipment corrosion.

[0003] So far, there is no large-scale potassium dihydrogen phosphate production device, resulting in a shortage of potassium dihydrogen phosphate in the market and higher product prices.

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