Method for improving by-product phosphogypsum quality during phosphoric acid production process

Abstract

The invention discloses a method for improving the by-product phosphogypsum quality during a phosphoric acid production process. The method comprises the steps that: (1) phosphoric acid is subjected to a reaction with phosphate concentrate; filtering is carried out, such that a filtrate containing calcium dihydrogen phosphate, calcium hydrogen phosphate, and phosphoric acid is obtained; and the filtrate is delivered to an extraction tank; (2) the filtrate is subjected to an extraction reaction in the extraction tank by using sulfuric acid with calcium dihydrogen phosphate and calcium hydrogen phosphate, and an obtained extract liquid is dilute phosphoric acid containing phosphogypsum; during the process, through analyzing filtrate calcium content, sulfuric acid theoretical dose is calculated according to a phosphoric acid extraction reaction formula, and sulfuric acid addition amount is determined; and (3) the extraction liquid is filtered by using a filtering machine, such that dilute phosphoric acid and phosphogypsum comprising 97% of dehydrate are obtained. In the phosphogypsum provided by the invention, dihydrate gypsum content is greatly higher than that of prior art, phosphorus content is substantially reduced, and phosphogypsum quality is greatly improved. Therefore, good raw material is provided for downstream phosphogypsum construction material manufacturing, and a basis is provided for sufficient utilization of phosphogypsum. The method is suitable for wet-method phosphoric acid production enterprises intending to utilize phosphogypsum.

Description

technical field [0001] The present invention relates to phosphoric acid and, in particular, to phosphogypsum by-produced in the production of phosphoric acid. technical background [0002] As we all know, phosphogypsum is the waste residue produced in the industrial production process of phosphoric acid and phosphate fertilizer. About 4 to 6 tons of gypsum are discharged per ton of wet-process phosphoric acid produced. At present, about 200 million tons of phosphogypsum slag are discharged every year in the world, and 50 million tons are discharged in my country every year. more than tons. The phosphogypsum produced in the production of phosphoric acid in various countries in the world is mostly piled up as waste, which requires land resources, and the fluorine and phosphorus in the piled up phosphogypsum will leach out with the rainwater after being leached by rainwater, and enter the soil or rivers, causing surface water and Groundwater pollution. Therefore, in recent yea...

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Problems solved by technology

[0004] One of the difficulties in the utilization of phosphogypsum is that the quality cannot meet the needs of the product, and the dihydrate content in phosphogypsum is only 90%, so it is difficult to expand its application range

At present, there is no patent application for improving the quality of phosphogypsum, and there are no reports of related new technologies.

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