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:
Sep. 02, 1980
Filed:
Jan. 04, 1978
Fernando N Ore', Whittier, CA (US);
Occidental Petroleum Corporation, Los Angeles, CA (US);
Abstract
When sulfate ions and a solution of monocalcium phosphate are reacted under conditions which result in the formation of a slurry comprising calcium sulfate hemihydrate and phosphoric acid of about 35% to about 55% P.sub.2 O.sub.5, filtration is improved when a sulfonic acid, a sulfonic acid salt, tall oil fatty acid or alkoxylated or esterified tall oil fatty acid and mixtures thereof is present in the slurry (preferably at 1-1000 ppm). Preferably a two vessel reaction system is used in which the reaction slurry undergoes intra- and inter- vessel circulation (preferably through a draft tube). The solution portion of the slurry in the first vessel (the 'dissolver') is preferably maintained at a negative sulfate concentration (i.e. excess Ca.sup.+2) and the solution in the second vessel (the 'crystallizer') is preferably maintained at a positive sulfate ion concentration, most preferably at a reduced pressure, (e.g. to provide evaporative cooling). Better filtration rates can thus be obtained due to the lower viscosity of the slurry and/or favorable shape, dominant size and size distribution of the hemihydrate crystals.