DISSOLUTION OF HEMATITE IN MIXTURES CONTAINING DIFFERENT CHELATING AND REDUCING AGENTS

Our earlier investigations have shown that the dissolution of moderate ly sintered haematite in a reductive-complexing formulation containing citric acid, EDTA and ascorbic acid (CEA) in the initial concentratio n ratio of 11:44:4mol.m(-3) (initial pH 2.8) is faster than at other c oncentration ratios. The dissolution was considered for a system havin g a surface area to volume ratio of 67 m(-1) with oxide thickness of 5 mu m, a system volume of similar to 8.5 m(3) and no regeneration of c helant. In the present work different reducing agents in place of asco rbic acid and different chelating agents in place of EDTA have been st udied, keeping the citric acid-complexing agent-reducing agent concent ration ratio the same as above, to End out their relative effects on t he dissolution process and to identify that formulation which gives th e fastest dissolution. It is found that among the different formulatio ns studied, CEA is the best for the dissolution of moderately sintered haematite particles.