Investigation of froth flotation and selection of reagents on the basis of the mechanism of their effect: Report 1. Substantiation of the selected methods for investigation of the process

Abstract

Three strengthening components of the particle-bubble contact that emerges under the effect of appearance of the external detachment force f in the dynamic conditions of froth flotation are considered. These are the flexure of the bubble surface at the contact perimeter, the increase in the contact angle θ, and the local increase in the surface tension σ on the bubble surface near the perimeter of its contact with the detached particle. Using the equations of capillary physics and experiments, three possible mechanisms of flexure of the bubble surface (which are caused by the effect of gravitation and reagents, namely, classical, hysteresis, and capillary mechanisms) are revealed. The necessary properties of reagents, which promote such flexure under the effect of f, are established. These are their ability to selective hydrophobization of the particle surface and to the local increase in the surface tension σ on the stretched bubble surface. Two groups of simple methods are recommended to investigate the process and to select reagents which model the process of froth flotation: (i) to evaluate the ability of reagents to vary the wettability of the particle surface—flotation experiments in frothing and nonfrothing apparatuses and to measure detachment forces, the time of adherence of the bubbles to the particles, and contact angles; (ii) methods for recording the relaxation curves and evaluating frothing properties (for reagents acting preferentially on the bubble surface). The effect of the capillary pressure of the gas in variously sized bubbles on the value of detachment forces of the particles from them, as well as the invariance of these forces of σ during slow detachment, are shown.