Dissolution of haematite in mixtures containing different chelating and reducing agents

Our earlier investigations have shown that the dissolution of moderately sintered haematite in a reductive-complexing formulation containing citric acid, EDTA and ascorbic acid (CEA) in the initial concentration ratio of 11:44:4mol.m(-3) (initial pH 2.8) is faster than at other concentration ratios. The dissolution was considered for a system having 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 chelant. In the present work different reducing agents in place of ascorbic acid and different chelating agents in place of EDTA have been studied, keeping the citric acid-complexing agent-reducing agent concentration ratio the same as above, to End out their relative effects on the dissolution process and to identify that formulation which gives the fastest dissolution. It is found that among the different formulations studied, CEA is the best for the dissolution of moderately sintered haematite particles.