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. 09, 1986
Filed:
Jan. 31, 1985
Willem P Duyvesteyn, Benthuisen, NL;
Mahesh C Jha, Arvada, CO (US);
AMAX Inc., Greenwich, CT (US);
Abstract
A process is provided for selectively recovering zinc from steel plant dust containing substantial amounts of iron. The process comprises atmospherically leaching the steel plant dust in a first stage wherein an amount of steel plant dust is mixed with an amount of acidic zinc sulfate solution to leach zinc therefrom, the leaching of the dust being such that the solution is controlled to a terminal pH ranging from about 2 to 3.5 and preferably from about 2.5 to 3.5, thereby limiting iron dissolution. The mixture is then subjected to a crude liquid/solid separation step whereby a thickened pulp is produced containing zinc and iron values and a separated liquid containing low iron and substantial amounts of zinc, the solution being sent to zinc recovery. Following separation, the thickened pulp, together with additional sulfuric acid or spent electrolyte, is subjected to high pressure leaching at a temperature at least sufficient to leach the remaining zinc values and provide an acid zinc sulfate solution thereof, while converting hydrated iron oxides into free settling hematite residue, the amount of additional sulfuric acid added to said thickened pulp being sufficient to obtain near quantitative dissolution of zinc without excessive iron dissolution.