N. A. Vatolin, A. M. Amdur, V. V. Pavlov, S. A. Fedorov.
ABSTRACT:
The flotation of droplets in liquids occurs frequently. For example, the flotation is the basis for the removal of liquid non-metallic inclusions from steel. Meanwhile, the mechanism of this process is has not been sufficiently studied. The paper describes in detail the mechanism of flotation of metal droplets in the melt for example of gold: the kinetics and formation stages of the gas bubble–gold droplet system, as well as the subsequent gold flotation in the melt, are considered. Once a gas bubble and a micro-droplet have concerned, a third surface gold–gas and a wetting perimeter appear, in addition to the previously existing melt-gas (around the bubble) and gold–melt (around the droplet) surfaces. The time for achieving equilibrium for gold micro-droplets with a radius of about 3 μm has an order of 10–4 s. Consequently, the formation of an equilibrium bubble-drop system is occurs rapidly and does not hinder the overall process of collecting and fusion of gold micro-droplets by gas bubbles. The flotation condition providing an excess of the interfacial tension forces over the gravity force is analyzed in relation to the system of dispersed droplets (gold, platinum and palladium)—oxide melt. This condition holds for metal droplets with a radius of up to 3500 μm.
KEYWORDS:
flotation, spreading, gas bubble, droplet, interphase tension, wetting perimeter, wetting angle, gold
DOI: 10.1134/S0235010618060075