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:
Aug. 11, 1981
Filed:
Jun. 05, 1980
Leonard C Ellis, Chesapeake, VA (US);
Virginia Chemicals Inc., Norfolk, VA (US);
Abstract
Substantially stable slurries containing 30-35% by weight of sodium dithionite are manufactured by evaporating sodium dithionite solutions while maintaining the heating medium at 220.degree.-250.degree. F. and the solution and slurry at 110.degree.-155.degree. F. under a vacuum of at least 25 inches Hg and by promptly cooling the resultant slurry while agitating it. The vacuum is preferably 26.5-27.5 in. Hg. At 4-5% by weight of the sodium dithionite and preferably at 4.3% by weight, NaOH is preferably added to the solution or alternatively to the slurry, immediately after evaporation. A chelator is preferably added to the solution to prevent metal contamination thereof. Zinc-derived sodiation liquor is the preferred sodium dithionite solution.