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. 04, 1990
Filed:
Jan. 05, 1990
Applicant:
Inventors:
Alvin J Lappinga, Martinez, CA (US);
George K Tyson, Walnut Creek, CA (US);
Assignee:
The Dow Chemical Company, Midland, MI (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
B01D / ; B01D / ;
U.S. Cl.
CPC ...
210639 ; 23296 ; 2330 / ; 423499 ;
Abstract
The removal of fluoride ion from potassium chloride containing at least a small amount of an acidic component with water is improved by adjusting the pH of the aqueous solution employed in a fractional crystallization of between about pH6 and about pH9 or adjusting the pH of the extractant used in an aqueous extraction by adding an amount of base so that final pH of the the extract is between about pH6 and about pH9. The fluoride ion contamination of potassium chloride, for example, was reduced from 1000 ppm to 90 ppm by adjusting the aqueous solution employed in a recrystallization of pH6.5 before precipitation.