Substantiation of Flotation Efficiency under Conditions of Heating of Wetting Films

In investigation of the aggregative stability of disperse systems by sediment volumetry, a violation of the structure of water in the contact area causes formation of nanobubbles, whose coalescence leads to appearance of hydrophobic attraction forces. A change in the aggregative stability of aqueous dispersions of particles can be interpreted in such a way that ingress of water molecules having a high potential of interaction with molecules of the medium in the interfacial gap between particle surfaces and outflow of water molecules exhibiting high intensity of interaction with a solid surface from the interfacial gap between particle surfaces is difficult. Excess osmotic pressure between hydrophilic surfaces leads to their hydrophilic repulsion, and excess osmotic pressure of the surrounding water (reduced osmotic pressure between surfaces) leads to hydrophobic attraction of the surfaces. To change the result of flotation, it is sufficient to bring a heat flow to a nanoscale-thick liquid layer, within which action of forces of structural origin is localized, determining the stability of wetting films. To increase the temperature in the interfacial gap between the particle and the bubble using the heat of water vapor condensation, as a gas for flotation, a mixture of air and hot water vapor is proposed. The developed flotation method has been tested in flotation of gold ores. The efficient steam flow rate determined from the results of a factorial experiment is 10.7 × 10^–3 kg/(s m²), with the xanthate flow rate being 1.74 g/t. In the rough flotation operation, the jet method of constructing a flowsheet is used, which provides for combination of the initial feed and rough concentrate. In comparison with flotation of ores according to a factory scheme, the yield of a concentrate sent to hydrometallurgical processing is smaller by 23.4 rel. %, with the achieved level of gold recovery remaining the same.