ABSTRACT
A. Introduction Flotation is a process for separating particles, based on their differences in surface properties, using air bubbles. The flotation process has a long history (over 100 years) of development and widespread applications. One of the earliest applications was in the recovery of sphalerite (zinc sulphide, ZnS) minerals from finely ground tailings of a gravity concentrator at Broken Hill in New South Wales, Australia in 1905. In mineral flotation, the ore is first crushed and finely ground to less than about 200 µm to liberate the minerals, before reagents are added to alter the mineral surface properties. The surface of the wanted minerals is rendered hydrophobic or water-repellent, which allows the particles to attach themselves to air bubbles while leaving the surface of the unwanted particles hydrophilic (water-wetted) and not attachable to air bubbles. After attaching themselves to the air bubbles, the
hydrophobic particles are separated from the suspension by the bubble rise as froth, which forms at the top of the slurry and flows over the lip of the cell (Fig. 1). The hydrophilic particles do not attach to the bubbles and remain in the liquid which is discharged from the bottom of the cell. In this way, the particles are separated, based on their surface hydrophobicities.
