DISSOLUTION PROPERTIES OF A DOLOMITE CONTAINING ZINC ORE IN SODIUM HYDROXIDE SOLUTIONS

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In this work, the dissolution properties of a dolomite containing zinc carbonate (smithsonite) ore sample having 24.22% ZnO were determined in sodium hydroxide solutions using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermal (TG/DTA) and chemical analyses methods. It was observed that the dissolution efficiency value of zinc continuously increased with the increase of sodium hydroxide concentration from 1 to 4 M and the highest zinc dissolution efficiency of 70.7% was reached after dissolution in 4 M NaOH solution at temperature of 298 K. The XRD, FT-IR, TG/DTA and chemical analyses of undissolved solids obtained after dissolution of ore sample in 4 M NaOH solution at 298 K revealed that the smithsonite phase in the sample completely dissolved whereas the main gangue mineral dolomite remained practically unaffected, showing the selectivity of sodium hydroxide solution considering zinc dissolution. Although the smithsonite phase in the sample totally dissolved, hundred percent zinc dissolution efficiency could not be reached, which may indicate the presence of zinc in the gangue components, i.e. dolomite, clay minerals etc., of the studied ore sample.