Study of the Mineral Composition and Its Connection with Some Properties Important for the Sludge Flocculation Process-Examples from Omarska Mine: A Comparative Approach

The primary objectives of this study is mineralogical characterization of two sludge samples with different initial content of iron derived by hydro-cyclone overflow generated during the processing of iron ore in the Omarska mine. Also, a comparative study of the mineral composition and its connection with some properties important for the sludge flocculation process was done. Studied sludge samples are composed of major goethite and quartz; less clay minerals; and minor magnetite, hematite, clinochlore and todorokite. They have quite similar qualitative, but different semi-quantitative compositions. There are similar particle size distributions between the samples, and highest contents of about 50% belongs to the finest classes of <6 m. Among size classes within the samples, almost identical iron contents are present; indicating to their similar mineral compositions, which make this system very complex for further separation processes. Sludge II has higher natural settling rate, due to its higher density and mineral composition. With addition of the flocculant, settling rates increases significantly with the increase of the liquid component in both of the samples. The effect of flocculant on the settling rate is different between samples, and depends on their mineral composition. The time of settling does not play a role in selectivity, to the ratio of the mass of floating and sinking parts, and iron content does not change with time. The content of iron partially increases by flocculation; therefore, this method should be considered as an appropriate one. Zeta potential values for sludge are mostly between those for goethite and quartz, indicating their particle mixture and intricately association.