Method for preparing industrial-grade monopotassium phosphate

Abstract

The invention relates to a method for preparing industrial-grade monopotassium phosphate, which comprises the following steps of sending wet-process phosphoric acid or industrial waste phosphoric acidinto a neutralizing tank, adding sodium carbonate, reacting at 70-90 DEG C, regulating the pH value to 7-9, reacting for 30 minutes, regulating the pH value of the solution to 3.5-5.0 by using phosphoric acid, and carrying out filter pressing and washing on the reacted neutralized slurry by using a filter press, adding potassium chloride, fully reacting for 30 minutes at the temperature of 80-90DEG C, and controlling the specific gravity of decomposition liquid to be 30-40 Be, cooling the reacted decomposition liquid to 20-30 DEG C, and carrying out centrifugal separation to obtain a semi-finished monopotassium phosphate product with a concentration of about 95%, aging for 30 minutes by using a monopotassium phosphate saturated solution, and increasing the content of a monopotassium phosphate finished product to 98%, centrifugally separating the mother liquor of the semi-finished product, adjusting the pH value to be more than 7, concentrating half of water, separating out sodium chloride at 80 DEG C, and aging the byproduct sodium chloride for 30 minutes by using a saturated solution of sodium chloride at 60 DEG C to obtain the byproduct sodium chloride with the purity of 99%. Impurities in wet-process phosphoric acid or industrial waste phosphoric acid are removed by using sodium carbonate, so that the purpose of purifying phosphoric acid is achieved, and the cost of monopotassium phosphate is reduced.

Description

technical field [0001] The invention relates to a method for preparing industrial-grade potassium dihydrogen phosphate with wet-process phosphoric acid or industrial waste phosphoric acid, which adopts purification-reaction-purification to prepare fine phosphate, and belongs to the technical field of fine phosphorus chemical industry. Background technique [0002] Potassium dihydrogen phosphate is widely used in modern chemical industry, medicine, food, agriculture, feed and other industries. Especially in agriculture, potassium dihydrogen phosphate is a high-efficiency compound fertilizer containing phosphorus and potassium. With the rapid development of national high-efficiency agriculture, water-saving agriculture, and water-fertilizer integration, water-soluble fertilizers and liquid fertilizers and their required raw material industries The development of high-grade potassium dihydrogen phosphate has brought broad market demand. [0003] Potassium dihydrogen phosphate ...

AI Technical Summary

Problems solved by technology

Due to the high price of thermal phosphoric acid (or purified phosphoric acid) and potassium hydroxide, the production cost of this process is high, and the production plant has only small or no profit

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