Mechanical, contactless, and collector flotation in the hallimond tube

Abstract

Different size fractions of quartz or magnetite were floated separately in a Hallimond tube. Recovery vs flotation time results and contact angle measurements showed that the following types of flotation took place, depending on conditions: mechanical carryover in pure water, contactless flotation in aqueous ethyl alcohol, and collector flotation in the presence of 10 −3 M aqueous dodecyl amine for quartz or 10 −3 M aqueous sodium oleate for magnetite. It was established that the maximum size of a particle which can be floated in the Hallimond tube depends on the type of flotation and the density of the solid. The maximum particle size which can be transported from the main body of the Hallimond tube to the product receiver increases in the order mechanical carryover, contactless flotation, collector flotation. It was also found that for all three kinds of flotation the quartz particle diameter to magnetite particle diameter ratio is equal to 2.6 ± 0.2, if comparison is made with the same recovery, time of flotation, and hydrophobicity. This indicates that the hydrodynamics of particles floated in a Hallimond tube, producing a single train of monodispersed bubbles at a gas flow rate of 0.625 cm 3/s, follows Netwon's law for a turbulent liquid medium.