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Defluorination of byproduct zinc concentrates.
Prater-RB Jr.; Miller-VR; Cole-ER Jr.
Rolla, MO: U.S. Department of the Interior, Bureau of Mines, RI 8957, 1985 Jan; :1-13
The Bureau of Mines conducted research to separate the F from byproduct Zn concentrates obtained from fluorspar (CaF2) production, as part of the Bureau's effort to devise efficient, environmentally acceptable technology for recovering Zn from resources considered undesirable by Zn producers. Sulfuric acid (H2SO4) was found to be effective in F removal, while ammonium carbonate [(NH4)2CO3] was not. The most important variables for reducing the necessary residence time were found to be temperature and agitation. Optimum leaching conditions were 75 deg. C and 500 r/min for 2 h at 40 pct solids with 0.2 g acid per gram of concentrate, which resulted in a 98.3-Pct F extraction. Zinc losses during F removal were in the range of 2 to 3.3 pct. Other elements such as Fe, Cd, Ca, and Cu were also partially dissolved. About 93 pct of the F was removed from the leach solution by neutralization and precipitation with calcium hydroxide [Ca(OH)2]. Additional treatment might be necessary to limit the buildup of soluble elements in the recycled leach solution.
Fluorite; Environmental surveys; Materials recovery; Zinc; Fluorine; Temperature; Leaching; Agitation; Solutions; Sulfuric acid; By products; Chemical treatment; Defluorination
IH; Report of Investigations
NTIS Accession No.
Rolla, MO: U.S. Department of the Interior, Bureau of Mines, RI 8957
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division