Dissolution behavior of cobalt, nickel and iron from smelter slag using aqueous sulphur dioxide.

摘要

Smelter slags, an industrial waste product, contain valuable metals such as Co, Ni and Cu in proportions of less than 1 wt% along with about 40wt% of Fe and 15wt% of Si. This research has focused on understanding the dissolution behavior of Co, Ni and Fe from smelter slag applying aqueous SO2, another product of metallurgical industries. Such an understanding would help lay the foundation for developing a scheme for the extraction of the valuable metals from slag using aqueous SO2.; Thermodynamic modeling, applying OLI, was used to study the slag-SO 2 system. The model developed was adequate in describing the dissolution of slag in aqueous SO2. The main species in the system were the metal-S(IV) species: FeSO30, CoSO3 0 and NiSO30. The model suggested that iron could be removed from the system as FeSO3.3H2O with increase of total S(IV). Experimentally by increasing the pH of the leach solution the precipitate FeSO3.3H2O was obtained. As a result the ratio of Co to Fe and Ni to Fe increased significantly. However, coprecipitation of Co and Ni also occurred with Fe. The metal/Fe ratio in solution was sensitive to pH. Lower pH was desirable for high metal to Fe ratio in solution.