Processing of Egyptian boiler-ashfor extraction of vanadium and nickel
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Alexandria University
Publication date: 2000-01-01
Physicochem. Probl. Miner. Process. 2000;34(1):153–161
Egyptian boiler ashes from thermal power stations contain up 20% vanadium and 22% nickel and thus they are valuable source for vanadium and nickel and their alloys as well as chemicals, The ash was directly leached with sulphuric acid under atmospheric pressure and in an autoclave. Atmospheric leaching leads to complete dissolution of vanadium and nickel together with iron. Separation of iron from vanadium is very difficult due to a narrow pH precipitation range of hydroxides of these metals, leaching under oxygen pressure leads to oxidation of iron and its precipitation as basic iron sulphate leaving vanadium and nickel in solution. Vanadium is thus precipitated as hydroxide by adjustment of pH value and then calcinated to vanadium penta-oxide. The leaching processes were thoroughly investigated and the optimum leaching conditions were determined.