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Chalcopyrite ores are usually processed by means of hydrometallurg ical or pyro metallurgical processes, but due to environmental aspects and the possibility of increased exp loitation of mixed and lower grade ores and relat ively small isolated deposits, there has been a worldwide upsurge of interest in the hydrometallurg ical processes of this ore as compared to pyrometallurgy. The different concentrates obtained through differential flotation in pyro metallu rgy are usually of poor quality with low metal recovery. This further makes pyrometallurgical processing of chalcopyrite very difficult and costly and rendered them difficult to commercialize. As a result, the metal value is preferab ly extracted directly fro m low grade ores through hydrometallurg ical process. A detailed review of chalcopyrite deposits, production and consumption, min ing, ore processing, steps involved in the pyrometallurgical and hydrometallurgical processing of copper as well as the dissolution kinetics and microbial studies of chalcopyrite ore were discussed.

Hydrometallurgy is the most suitable extractive technique for the extraction and purification of manganese as compared to all other techniques including biometallurgy and pyrometallurgical processes. In the hydrometallurgical processing of manganese from its ore, the leach liquors often contain divalent ions such as iron, manganese, copper, nickel, cobalt and zinc along with other impurities which make manganese very difficult to separate. The processes employed for solution concentration and purification in the hydrometallurgical processing of manganese include precipitation, cementation, solvent extraction and ion exchange. Solvent extraction also proves more efficient and it plays vital roles in the purification and separation of the manganese as compared to all other techniques. A detailed review of the various steps involved in the hydrometallurgical manganese processing, concentration and purification processes and newer processes of extraction of manganese from ores and waste materials were discussed.

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Sequential extraction was carried out to determine the concentrations of some trace metals (Mn, Cu, Fe, Pb and Cd) in the Kainji lake sediments from seven different locations in four fractions: exchangeable, bound to iron and manganese oxide, bound to organic matters and residual. This was to undertaken to assess the environmental fate of these trace metals. The BCR technique, a modified form of the Tessier method of sequential extraction was used.The proportion of the mean metal concentrations of the bioavailable metals follows the order Fe4Cu4Pb4Mn4Cd. Generally, Fe was most abundant metal in the sediment and about 40% was found in its bioavailable form. Although Cd contributed least to the bioavailable content, a greater percentage ( $ 60%) was found in the bioavailable fraction. This suggests that Cd is highly mobile and, since it is known to be toxic, its concentration in the bioavailable form constitutes an environmental threat.The contribution of metals bound to organic matter was found to be high and of the same magnitude as those bound to oxides and constitutes about 70% of the non-bioavailable metal contents. The petrological analysis of the sediments revealed that the sediments were predominantly quartz and rock clays with percussion marks and indentations.