Process of producing phosphates and phosphoric acid

Abstract

The process of treating insoluble phosphate ore in the form of calcium phosphate, such as phosphate rock or bone phosphate, at near ambient conditions with sulfur trioxide or sulfuric acid as reactants in the presence of a liquid anhydrous dispersion media of, preferably, sulfur trioxide, sulfur dioxide, or their mixtures in liquid form so that the contacting of the ore is made in the form of an anhydrous slurry, to make the phosphorous content available as a nutrient or as phosphoric acid, and subsequently separating the dispersion media from the contacted ore preceding aqueous contact or extraction of the phosphorous constituent. The presence of sulfur dioxide in the anhydrous dispersion media is desirable to minimize operational difficulties associated with the proximity of the vaporization and solidification points of sulfur trioxide. The process may be carried out with the sulfur trioxide and sulfur dioxide as dispersants as long as sulfuric acid content is limited to the amount required for reaction with the phosphate material. Sulfur trioxide can serve as both reactant and dispersant. The contact of the ore in the presence of the excesses of anhydrous liquid permits efficient contact with the ore as a slurry. Sulfuric acid may be formed 'in situ' from the sulfur trioxide associated with the ore upon aqueous contact or extraction after the sulfur trioxide treatment and removal of the excess required for reaction.