• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.235-242
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• 2010

Froth flotation using the residual water in the end of flotation process has been performed through controlling of pH. IEP (isoelectric point) of molybdenite and quartz in distilled water was below pH 3 and pH 2.7, respectively and the stabilized range was pH 5~10. In case of a suspension in reusing water, zeta potential of molybdenite decreased to below -10 mV or less at over pH 4 due to residual flocculants. As result of pH control, flotation efficiency in the alkaline conditions was deteriorated by flocculation, resulting from expanded polymer chain, ion bridge of the divalent metal cations ($Ca^{2+}$), and hydrophobic interactions between the nonpolar site of polymer/the hydrophobic areas of the particle surfaces. However, the weak acid conditions (pH 5.5~6) improved the efficiency of flotation as hydrogen ions neutralize polymer chains and then weakened its function. In cleans after rougher flotation, the Mo grade of 52.7% and recovery of 90.1% could be successfully obtained under the conditions of 20 g/t kerosene, 50 g/t AF65, 300 g/t $Na_2SiO_3$, pH 5.5 and 2 cleaning times. Hence, we developed a technique which can continuously supply waste water filtered from tailings into the grinding-rougher-cleaning processes.