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.