PROCESS FOR RECOVERING MANGANESE VALUES FROM LOW GRADE OXIDIZED MANGANESE CONTAINING ORES

摘要

1397029 Mn values from low grade ores DIAMOND SHAMROCK CORP 22 June 1973 [23 June 1972] 29882/73 Heading C1A Mn values are recovered from low grade ores (a) by dissolving NO 2 and water vapour in an aqueous medium and (b) immediately contacting with an unreduced ore containing excess MnO 2 relative to the HNO 2 in solution (a) at less than 80‹ C., pH below 4 and an equilibrium partial pressure of NO and water vapour less than atmospheric pressure which gives a slurry containing Mn(NO 3 ) 2 . The slurry may be adjusted to pH 4-5À5, e.g. using MnO derived from reduced ore, heated to 70-105‹ C. and filtered to remove impurities. The solution may be made into a slurry with MnO 2 , agitated and heated to form pyrolusite crystals, NO 2 and water vapour at preferably 138-160‹ C. The pyrolusite crystals may be dried at 110-150‹ C. The NO 2 and water vapour may be recycled to step (a).