The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 04, 1994
Filed:
Mar. 10, 1993
Jack M Sullivan, Florence, AL (US);
Raymond D Thrasher, Killen, AL (US);
Ronald E Edwards, Florence, AL (US);
Tennessee Valley Authority, Muscle Shoals, AL (US);
Abstract
A process for oxidizing aqueous elemental phosphorus containing residues (sludges) to produce orthophosphate containing slurries suitable for subsequent reaction with ammonia to produce nitrogen- and phosphorus-containing fertilizer products. It comprises reacting aqueous elemental phosphorus containing residues with certain special mixtures of concentrated nitric acid and sulfuric acid to effect the conversion of the elemental phosphorus content of the residues into mostly orthophosphoric acid and very little orthophosphorous acid with the relative ratios of orthophosphoric acid to orthophosphorous acid produced being dependent upon the weight ratio H.sub.2 SO.sub.4 :HNO.sub.3 employed in the processing. The reaction is conducted at the boiling point of the resulting aqueous reaction medium. Prior to the conversion to fertilizer products, the aqueous reaction product intermediate may be subjected to a solids separation step to remove insoluble salts of certain environmentally undesirable metals, such as, Pb, Cd, Ba, and Cr which are derived from phosphate rock via the dust component of phosphorus sludge.