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. 21, 1992
Filed:
Apr. 26, 1991
Everett C Barrett, Richmond Hill, CA;
Emil H Nenniger, Oakville, CA;
Hatch Associates Ltd., Toronto, CA;
Abstract
In a process for the hydrometallurgical treatment of electric arc furnace dusts which includes an acetic acid leach, the acetic acid solution used to perform the leach is made strong enough to dissolve heavy metal residues in the dusts, the iron-containing residues of which are recycled to a steel producing furnace. Zinc and other heavy metals are precipitated from hot acetic acid solution as useful products by the use of hydrogen sulphide. Calcium is then precipitated from the acetic acid solution as a clean gypsum using a deficiency of sulphuric acid, thus avoiding leaving sulphate ions in solution in sufficient concentration to interact with the dust and form sulphates in the iron containing residues when the acetic acid is recycled to the leaching step.