Effect of Key Variables on Coal Cleaning by Froth Flotation Technique

Abstract

Coal, in India and Worldwide, is cleaned predominantly by dense medium separations and jigging. But when it comes to cleaning of fine coals such as mine dust, slack coal, washing rejects and slurries, froth flotation method of coal cleaning has better efficiency and handling. In this method of wet cleaning, froth is made in a flotation cell by bubbling air through water in presence of frothing agents; on addition, pure and light coal adhere to air bubble while the dirtier part sinks to bottom of the cell. Thus clean coal is recovered from the collected froth amount. Density and wettability can be termed as the two bases of separation which are the inherent properties of the coal. In this current project froth flotation was being carried in a fixed froth flotation cell used in the laboratory. Runs of froth flotation have been carried out using the same stock of coal but varying the size of coal fines, concentration of coal slurries and different doses of collecting agents and of their mixtures. In order to quantitatively measure the effect, ash rejection, combustible recovery and efficiency were calculated. Effect of size of particles in slurry was very much visible while the combustible recovery and ash rejection was enhanced when higher dose of collecting agents were used. Use of advanced frothing agents and pH controllers can be studied further in this direction.