Beneficiation of Char, from a Pyrolyzed Eastern Canadian Coal, by Aggregative Flotation†

Abstract

A high-volatile high-sulphur coal was pyrolysed at pressures of 50 and 500torr, and at temperatures from 390 to 660°C. The floatability of the chars and the removal of ash and mineral sulphur from the char by aggregative notation were studied using a high-shear blender and a laboratory-scale flotation column. With respect to efficiency of cleaning, low temperature chars were better than high, and high pressure chars better than low. The inherent pH of char-water slurries increased from 4 to 10 as the temperature of pyrolysis was raised from 390 to 660°C. The amount of bridging liquid required to achieve 90% recovery of product, and the calculated floatability coefficient, were found to be functions of the specific surface area of the char.