Application of flotometry for characterizing flotation in the presence of particles aggregation

Abstract

Different size fractions of coarse magnetite were floated in water in a monobubble Hallimond tube with an increasing dosage of sodium oleate (Na01), diethyl dixanthate ((EtX) 2), and hexadecane. All maximum recovery (R m) vs collector concentration curves plotted for various size fractions were similar in shape having zero recovery at a low and high collector concentration with a maximum recovery in between at a characteristic collector dosage c m, which provides maximum hydrophobicity of the system. Properties of the studied flotation system and literature data indicated that the cessation of magnetite flotation with a high dosage of Na01 is due to hydrophilic layers of oleate ions sorption, while in the other two systems it is due to oil agglomeration of the solids. The values of the maximum particle size which can still be floated (a m 50), taken from the maximum recovery vs particle mean size at the concentration equal to c m and R m=50%, seems to be the parameter which well characterizes any solid-collector-water flotation system because this value derives mainly from the hydrophobic properties of the flotation system and particle density in water, ϱ ′. The a m 50 value and the so-called “flotometry equation” (for our Hallimond tube in the form L m = a m 50 ϱ ′) were used for calculation of the parameter L m which in turn was used for a comparison of the floatability of magnetite with different collectors and subsequently with other flotation systems. The values of parameter L m indicated that magnetite floatability increases in the order: collectorless (mechanical carryover), flotation with (EtX) 2, flotation in the presence of hexadecane, and oleate flotation. It was established that the floatability of magnetite with Na01 is equal to the floatability of galena with (EtX) 2 and very similar to the collectorless floatability of Teflon. Floatability of the above three systems is most likely the maximum possible floatability of a solid in an aqueous environment.