Browsing by Subject "Taconite processing"

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    The Reduction of Fluoride Dissolution During Induration Off-Gas Scrubbing
    (University of Minnesota Duluth, 2001-05-10) Engesser, John
    A research project supported by the Minnesota Department of Natural Resources and the Iron Ore Cooperative Research Committee was undertaken to reduce the dissolution of fluoride into process water during taconite processing. Leach tests were conducted using rod mill feed samples and water containing varying concentrations of calcium and sodium. Laboratory liberation grinds were performed to evaluate fluoride rejection during grinding and magnetic separation. Tube furnace tests were conducted to evaluate fluoride volatilization during pellet induration. The results indicate that fluoride concentration of process water is a function of both calcium and sodium concentration in process water. It appears that less than 1 percent of the fluoride present in rod mill feed will dissolve in process water during grinding. More than 90 percent of the fluoride present in rod mill feed is rejected with tailings during siz.e reduction and magnetic separation. The furnace tests demonstrate that bentonite and fluxstone (calcite and dolomite) addition to taconite concentrate during pellet production increases the amount of fluoride that volatiliz.es during induration. Lime hydrate addition to pellets decreases the amount of fluoride that volatilizes during pellet induration. During acid pellet production approximately three times more fluoride enters the water during indurationoff- gas scrubbing than during grinding. When fluxed pellets are produced three to eight times more fluoride enters the water during off-gas scrubbing than during taconite grinding.
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    Taconite Process Water and Tailing Water Quality Cationic-Exchange Effect on Balling and Flotation: Final Report
    (University of Minnesota Duluth, 1999-10) Engesser, John
    A research project supported by the Minnesota Department of Natural Resources and the Iron Ore Cooperative Research Committee was undertaken to 1) evaluate the problems related to cation exchange mechanisms that occur during wet grinding, flotation and balling and 2) investigate ionic formation and precipitation that occurs in the processwater during taconite processing. The cation exchange capacities of rod mill feed samples from two taconite plants were determined. Ball mill grinding, magnetic separation, bench scale flotation and balling tests were performed to establish the effect that cation exchange has on flotation and balling. Tests indicate that balling and flotation are affected by the cation exchange capacity of processed taconite ore. The rate of formation of sulfate, fluoride and bicarbonate anions during the grinding of taconite rod-mill-feed was determined. Sulfide oxidation to sulfuric acid followed by neutralization with carbonate minerals was studied. Fluoride liberation from the taconite ore was also investigated.