Effect of frother type in collectorless flotation of two high-rank coking coals of Gondwana origin

Two high-rank coking coals of drift origin, which exhibited strong natural hydrophobicity, were used in this work. As high as 64-74% yield could be achieved through collectorless batch flotation with three different frothers: pine oil, MIBC, and a synthetic frother for three different feed sizes. It appears that a fairly long wetting time minimized the frother consumption. The flotation response of three different sizes, -0.5 mm, -0.5+0.1 mm,and -0.1 mm of the same feed, was found to be different for the three frothers. Frother performance was also found to vary with the same size of the two coals. The performance of the synthetic frother and MIBC was found to be superior for the -0.5 + 0.1 mm and -0.1 mm feeds, respectively. MIBC performed best for the -0.5 mm feed of one coal, whereas the synthetic frother did the same for the other coal. Frother performance also seems to be dependent on performance evaluation methodology.