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Leaching of Pyroxmangite Ore With Calcium Fluoride and Sulfuric Acid.

Droes SR; Lei KPV; Carnahan TG
MISSING :8 pages
The U.S. Bureau of Mines investigated calcium fluoride (caf2) assisted sulfuric acid (h2so4) leaching as an alternative to the melting-quenching procedure to obtain mn from domestic manganese silicate resources. Pyroxmangite [(mn, fe) sio3] ore containing, in percent, 34.4 Mn, 22.8 Si, 2.6 Ca, and 1.3 Fe was leached in a 500- ml resin kettle. Ninety-six percent of the mn was extracted under conditions of 330 g/l ore, 245 g/l h2so4, 35 g/l caf2, 90 deg c, and 2 h. To incorporate electrowinning in recovering mn, the ore was leached with a simulated spent anolyte solution containing, in grams per liter, 12 mn, 140 h2so4, 130 (nh4)2so4 (ammonium sulfate), and 5 caf2. Manganese extraction of 92 pct was achieved from 130 g/l ore leached at 90 deg c in 3 h. The fe, silica (sio2), and other impurities were precipitated from the pregnant solution by neutralization with ammonia (nh3). Manganese of greater than 99-pct purity was deposited at a cathode current density of 50 ma/cm2 at 30 deg c, with a current efficiency of 65 pct in a two-compartment cell. A flowsheet was proposed for the leaching and electrowinning procedure.
Publication Date
Document Type
IH; Report of Investigations;
Fiscal Year
Identifying No.
RI 9318
NIOSH Division
Source Name
Page last reviewed: December 3, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division