True Flotation and Entrainment of Kaolinitic Ore in Batch Tests

A new method for true flotation and entrainment evaluation is proposed and compared with three renowned methods. Therefore, reverse froth flotation tests were conducted in a laboratory Denver cell with a kaolinitic ore. The evaluation of entrainment and true flotation was based on the recoveries of iron, titanium, and manganese oxides (FeO, TiO₂, and MnO), and the contributions of each oxide on kaolin minerals determined by electronic microprobe. The effect of particle size in the flotation process was analyzed by particle size distributions of four fractions (<25 µm; +25–45 µm, +45–63 µm; and >63 µm). The contribution of entrainment is similar for the three oxides and the degree of entrainment decreases with increasing particle size; however, the recovery by true flotation is different because of its discriminatory effect on minerals. MnO has the greatest recovery, as a consequence of the major contribution of its hydrophobic minerals, while FeO has the lowest recovery values. The results of the proposed method, developed for fully liberated feeds, are coherent with those obtained by the other three methods, despite the slightly overestimated contribution of entrainment in the case of fraction greater than 63 µm.