GB460761A - Improved method of obtaining coal powder by froth flotation - Google Patents

Abstract

460,761. Washing coal. BIESEL, P. Aug. 1, 1936, No. 21327. [Class 82 (ii)] Coal powder with an ash content of less than 1 per cent is obtained from coal already poor in ash, e.g. with an ash content of 2-5 per cent, by froth flotation. The apparatus comprises a unitary structure divided into a plurality of compartments each comprising an agitating cell and a separating cell, or groups of agitating cells and separating cells. Tailings are withdrawn from each agitating cell or group of agitating cells and the coal froth floating in the separating cell or cells in each compartment is passed to the agitating cell or cells of the next compartment. Fresh water is supplied to the agitating cell or cells of each compartment. The apparatus shown includes nine units 1 . . . 9, each being divided into an agitating cell a and a separating cell b, which communicate through an opening c. The units 1 and 2 form a single compartment and the other units are separated from-one another, each constituting a compartment. The coal is introduced at d and the froth forming in the separating cells b of the first compartment passes into a trough f from which it is raised by a conveyer k to a shoot k1 which leads it to the agitating cell a of the unit 3. The treatment is repeated in each compartment, tailings being removed from each cell a by pipes h leading to a collecting pipe h1, and the purified coal being collected at g. To facilitate the removal of the coal froth, the separating cells b may be provided with a horizontal or inclined false bottom m, Fig. 3, the passage of the froth over the member m being assisted by blade wheels o or a rake conveyer o1. The flotation agents preferably comprise an oil such as beach tar oil and an alkali, e.g. ammonia. The purified coal may be used in the manufacture of electrodes, for driving coal-dust motors, for the production of emulsions or suspensions of coal in oil, &c.