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Elevated-temperature Nitrogen Treatment of Jamaican Bauxite Before Bayer Leaching.
Sandgren-KR; MacDonald-DJ; Zamzow-MJ; Shanks-DE
Light Metals 1990 :21-26
U.S. Bureau of Mines testing showed that treatment of bauxite with hydrogen under pressure at temperatures from 250 deg to 450 deg c partially reduced the ferric iron in bauxite to magnetite, fe3o4, as well as partially volatilizing the organic carbon. This partially fulfilled the twin goals of eliminating the organic carbon from the bauxite and making the leached residue susceptible to magnetic separation. Magnetic susceptibility of reduced bauxite was at a maximum for a treatment temperature of 400 deg c, and the residue, after Bayer leaching, retained its magnetic properties and was amenable to magnetic filtration. This would facilitate more complete clarification of Bayer liquor. Organic carbon in the bauxite was partially converted to co2 by thermal decomposition in the hydrogen atmosphere. The 0.2-Pct original organic carbon content was decreased to 0.05 pct by treatment with hydrogen at 450 deg c. Treatment with hydrogen under pressure also decreased aluminum leachability.
Light Metals 1990. TMS, 1990, PP. 21-26
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