Flotation of zinc silicate ore: A focus on effective parameters, synergistic effect of mixed cationic collectors and its mechanism

The present study addresses the direct flotation route for the concentration of a zinc silicate ore. Flotation of hemimorphite faces some challenges due to the similarity of hemimorphite and quartz surface properties. XRD, and XRF analyses, optical mineralogy and SEM with X-ray mapping were performed for characterization. The results showed that the quartz, hemimorphite, calcite and dolomite are the main minerals. In the flotation process, combined form of Octadecylamine and Armac T, as mixed cationic collectors were introduced. Flotation tests were employed in two steps to evaluate the individual effect of the variables such as: size distribution of feed and the presence of Armac T in the first step, alkalinity, types and concentrations of reagents (Armac T and stearyl amine (collectors), sodium sulfide (sulphidizing agent), and sodium hexametaphosphate (dispersant) in the second step. In optimal conditions, the grade and recovery of zinc in concentrate were ~33 % and 83 %, respectively. Finally, for removing the detrimental effect of fine particles, de-sliming of pulp feed accomplished which resulted in a remarkable increase in the recovery of hemimorphite concentrate (12.67%) and a decrease in the grade of zinc in tailing (6.11%). FTIR analysis showed the adherence of collectors on hemimorphite particles increased after de-sliming.