Method for producing monoammonium phosphate and coproducing N-P binary compound fertilizer by using wet-process phosphoric acid

Abstract

The invention discloses a method for producing monoammonium phosphate and coproducing an N-P binary compound fertilizer by using wet-process phosphoric acid. According to the method, wet-process phosphoric acid prepared from low-grade phosphate ores is used as a raw material. The method comprises the following steps: concentrating and setting the wet-process phosphoric acid to remove impurities; diluting with process water; neutralizing with ammonia twice; filtering twice; concentrating; cooling for crystallization; centrifugally separating; drying to obtain the industrial grade monoammonium phosphate finished product; and mixing acid sludge, the centrifugalized mother liquor, residue and the flushing fluid in a slurry mixing tank, performing spray drying to obtain the N-P binary compound fertilizer. According to the method, wet-process phosphoric acid and gaseous ammonia are directly used as raw materials and the existing related devices in the phosphoric acid industry and resources such as waste heat steam and self power can be utilized, thus the yield of industrial grade monoammonium phosphate can be increased, the output of the byproduct N-P binary compound fertilizer can be reduced, the production cost of industrial grade monoammonium phosphate can be greatly reduced, the industry scale can be enlarged, the adaptability of the equipment can be enhanced, the market demands can be met, the stepped comprehensive utilization of the phosphorus resource can be realized and the economic benefit is higher.

Description

technical field [0001] The invention belongs to the technical field of preparation of phosphorus chemical products, and relates to the production of monoammonium phosphate, in particular to a method for producing industrial-grade monoammonium phosphate with wet-process phosphoric acid and co-producing N-P binary compound fertilizer. Background technique [0002] Industrial monoammonium phosphate is mainly used as drip irrigation fertilizer, and can also be used as flame retardant for paper, plastic, rubber, paint, dry powder fire extinguishing agent, analytical reagent, feed, wastewater, metal treatment, etc. The market prospect is extremely broad. The annual industrial monoammonium phosphate consumption in the world is more than 10 million tons, and it is growing at a rate of more than 4%. [0003] The traditional method of producing industrial monoammonium phosphate in my country uses thermal acid as raw material, and the production cost is high. In recent years, the slurr...

AI Technical Summary

Problems solved by technology

[0003] The traditional method of producing industrial monoammonium phosphate in my country uses thermal acid as raw material, and the production cost is high. In recent years, the slurry purification method represented by Sichuan University (wet acid of high-grade phosphate rock) Some progress has been made, but the production scale is relatively small, the source of slurry (raw acid) is limited, and its production rate (the ratio of industrial grade to fertilizer grade is 1:6-10, that is, every ton of industrial grade monoammonium phosphate is produced at the same time Fertilizer-grade monoammonium phosphate (6-10 tons) is not high, and it is difficult to promote industrialization

[0004] According to this situation, many related enterprises in the phosphorus chemical industry and some colleges and universities and research institutions are actively carrying out technical research on industrial monoammonium phosphate, and have achieved some results, which can be summarized into the following categories: First, use wet-process phosphoric acid The main fertilizer cascade produces industrial-grade monoammonium phosphate, and about 1 ton of fertilizer-grade monoammonium phosphate produces 50-100 kg of industrial-grade monoammonium phosphate as a by-product. Obviously, co-production of industrial-grade industrial grade improves economic benefits compared with pure fertilizer-grade production. Not obvious; second, there is a pretreatment and purification process, such as wet-process phosphoric acid first adding carbonates or other salts to remove impurities (desulfurization, defluorination, etc.). Although continuous production is possible, the process is long and complicated, and the production cost is high. And the yield is low; the third is to use the batch method to produce industrial-grade monoammonium phosphate using the conventional fertilizer-grade monoammonium phosphate process. The method is simple but the production cycle is long and the yield is not high, and the overall economic benefit is not high; the fourth is to use other ammonium salts Production of industrial-grade monoammonium phosphate with phosphoric acid, based on the current market conditions and national industrial policies, there is no competitive advantage in the production of industrial-grade monoammonium phosphate using such technical methods

Limited by the above-mentioned process technology and cost, the scale and production capacity of domestic industrial monoammonium phosphate production plants are generally small, and the supply of industrial monoammonium phosphate is always in short supply, and the price is also rising

Images