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:
Dec. 07, 1982
Filed:
Jul. 15, 1981
Cornelis A Weterings, Stein, NL;
Stamicarbon, B.V., Geleen, NL;
Abstract
Phosphate rock is digested with H.sub.2 SO.sub.4 into phosphoric acid and gypsum, the latter is separated off, washed and converted into anhydrite. After this first wash the gypsum is divided into a minor portion of fine crystals, which is discharged, and into a major portion of coarse crystals, which is subjected to a second wash, thereafter recrystallized into anhydrite by means of concentrated H.sub.2 SO.sub.4, the anhydrite being separated and washed and the recrystallization liquor returned to the digestion zone. The washing liquor obtained from the anhydrite wash is used for the second gypsum wash, the washing liquor obtained from this second wash is, together with water, used for the first gypsum wash, whereas the washing liquor obtained in this first wash is returned to the digestion zone. In this way practically all gypsum formed can be converted into anhydrite, while substantially all water can be functionally used without dilution of the H.sub.3 PO.sub.4 -product.