Sulfate Ion → Calcium Sulfate, Hemihydrate

Participants

Reaction Steps

adding sulfuric acid in amounts such that the sulfate content of the added phosphate rock is equivalent to about 90% to about 100% of the stoichiometric amount of sulfate required to react with the calcium present in the phosphate rock added in part (a) to form calcium sulfate hemihydrate to a second reaction vessel which contains a second slurry comprising calcium sulfate hemihydrate, monocalcium phosphate, and phosphoric acid, whereby the sulfuric acid is added and reacts with the monocalcium phosphate and the phosphate rock to form calcium sulfate hemihydrate and phosphoric acid, said second slurry being maintained at a soluble sulfate concentration of about 0.7% to +4.5%, provided that the soluble sulfate content of the second slurry is about +1.0% or greater when the soluble sulfate content of the first slurry is about +0.7%, the slurry has a specific gravity of between about 1.58 to about 1.99 grams/cc, the specific gravity of the liquid portion of the slurry has a specific gravity of from about 1.36 to about 1.72 grams/cc;

Provenance & Evidence