Studies in the Flotation of Colloidal Particulates: Effects of Aggregation in the Flotation Process

Abstract

An experimental investigation is reported of the effects of several solution parameters on the flotation of colloidal kaolin and montmorillonite using ethylhexadecyldimethylammonium bromide. The parameters examined were the zeta potential of the surfactant-particulate species, the concentration of selected cations, pH, and the ratio of initial surfactant concentration to initial particulate concentration. Two apparatuses were used to assess the affect of aggregation on flotation; one employed bubbles of 1-2 mm average diameter to effect the flotation, while the other used bubbles of about 0.2 mm. In the large bubble system, aggregation adversely affected the flotation of the particulates. For the small bubble (0.2 mm) system, the affect of aggregation on the flotation of particulates was contrary to that in the large bubble (1-2 mm) system. These observations are explained in terms of bubble sizes and their attachment to the particulate species during the flotation process. Studies also showed that several cations and pH variations cause little interference. A general discussion is given relative to the application of the process to large-scale clarification of turbid waters.