Alternative Oxidation Leaching Studies

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Proposed Refinement of Baseline: Multiple Oxidants • Current methods of chromite ore processing are extremely aggressive oxidizing processes: – Traditional • Kiln Roasting at 1200 C (Zheng et al, 2006) – Recent <strong>Alternative</strong>s • 240 ˚C Caustic Leach with 10 Bar O 2 application (Amer & Ibraham, 1996) • 300 ˚C Molten Caustic Leach (Zheng et al, 2006)
Free Radical & Other Intermediate Species Formation: γ-radiation driven reactions Tank Waste, pH = 13 H 2 O + hν → O •- + H 2 or → H 2 O + + e - OH - + hν → O •- + H • (OH • → O •- + H + pK a = 11.57) NO 3- + hν → ONOO - O 2 + hν → O( 1 D) + O( 3 P) H 2 O 2 Added H 2 O 2 → HO 2- + H + (pK a = 11.65) HO 2- + hν → O •- 2 + H • TiO 2 Added >TiO 2 + hν → TiO 2+ + e- >TiO 2+ + 2OH - → O •- + >TiO 2 + H 2 O O 3 Added O 3 + hν → O 2 + O( 1 D) MnO 4- Added MnO 4- + hν → ? (Swordsma, Tumosa et al. 1971) Buxton et al. 1988. J. Phys. Chem. Ref. Data 17(2) Other possible synergistic reactions besides O 3 + H 2 O 2 producing free radicals? (Holland et al. 2006)
Page 1 and 2: MULTIPLE OXIDANT CHROMIUM LEACHING
Page 3 and 4: BASELINE PERMANGANTE LEACHEACH Sele
Page 5: PROPOSED BASELINEASELINE REFINEMENT
Page 9 and 10: METHODOLOGY
Page 11 and 12: UV Lamps Emission Intensity Check U
Page 13 and 14: RESULTS
Page 15 and 16: Oxidation of Test Solution with Cr
Page 17 and 18: Irradiated NO 3- (or ONOO - ) Appea
Page 19 and 20: UV + O 3 -H 2 O Effectiveness in Te
Page 21 and 22: a Path Forward • Further Downsele
Page 23: REFERENCES (1998). 3500-Cr CHROMIUM

Alternative Oxidation Leaching Studies

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