Use of oscillatory air supply for improving the throughput and carrying capacity of column flotation

Abstract

Column flotation is widely used for material separation such as coal cleaning, mineral beneficiation, water purification and oil recovery. Flotation columns typically have small diameter-to-height ratios, posing a severe limit on their throughput and carrying capacity. This paper addresses this issue. A fast-switching solenoid valve was added to the air intake line of a 5-cm diameter flotation column equipped with a sparger to change the flow pattern of air supply from steady to rapidly oscillatory. The flotation tests were carried out at semi-continuous mode for a coking coal sample at various throughput levels controlled by adjusting the solids content or volumetric flowrate of the feed slurry. It was found that use of oscillatory air supply to replace steady air supply could significantly improve the throughput without sacrificing product yield and increase the carrying capacity of the column, which was consistent with the enhanced bubble surface area flux in the column.