Rationale for efficiency of flotation in the conditions of wetting film heating

Abstract

When studying the aggregative stability of dispersed systems by sediment volumetry, nanobubbles are formed due to water structure imperfections in the contact area, and the coalescence of nanobubbles results in a hydrophobic attraction force. Changes in the aggregative stability of aqueous dispersions of particles can be explained as follows: water molecules with a high potential of interaction with medium molecules are difficult to flow into the interfacial gap between particle surfaces, and the outflow of water molecules with a high intensity of interaction with a solid surface is impaired. Excessive osmotic pressure between hydrophilic surfaces causes their hydrophilic repulsion, and excessive osmotic pressure of the surrounding water (reduced osmotic pressure between surfaces) causes hydrophobic attraction of the surfaces. To change the result of flotation, it is sufficient to bring the heat flow to a thin liquid layer of nanoscale thickness with the action of forces of structural origin localized inside, which determine the stability of wetting films. To increase the temperature in the interfacial gap between theparticle and the bubble due to the heat of water vapor condensation, it is proposed to use a mixture of air with hot water vapor as a gas during flotation. The developed flotation method was tested in the flotation of gold-bearing ores. The rational vapor consumption determined based on the factorial experiment results is 10.7·10–3kg/(s·m2) at a xanthate consumption of 1.74 g/t. The rougher flotation operation used a jet method of flotation circuit design, which provides for the combination of the initial feed and the rough concentrate. In comparison with ore flotation according to the factory scheme, the yield of concentrate sent for hydrometallurgical processing is 23.4 rel.% less while maintaining the gold recovery level achieved.