A method of preparing wet process phosphoric acid

摘要

The present invention relates to a method of preparing wet process phosphoric acid, which comprises: dividing raw materials which contain phosphate rock slurry and sulfuric acid into two parts, and then feeding these two parts into two reactors separately. In the first reactor, feeding 70-90 wt. % of the total amount of the slurry and sulfuric acid, in which the ratio of phosphate rock slurry to sulfuric acid to recycled phosphoric acid is set to be 1:0.6~0.8:1.0~2.5. 10~30% of the reaction solution directly flows into conversion cell, participating in the conversion reaction of dihydrate gypsum. Thus resulted phosphoric acid concentration is 33~39 wt. %. The recovery efficiency of P₂O₅ is 99% or more. When putting coke powders in the conversion solution as filter aid, the filtration efficiency can be improved by 10~30%, and in so produced hemihydrate gypsum, P₂O₅ is 0.05~0.2%, water of hydration is 4~8%. The product can be used for producing sulfuric acid and cement without baking dry.