An experimental study on the effects of some process parameters on lignite flotation

摘要

Flotation, as an efficient method for separating fine coal particles (-500 mu m), is making slow progress for use with lignite, which basically remains at the laboratory stage. Lignite flotation is more difficult than flotation of other coals, and flotation efficiency here is very low. The difficulty in floating lignite primarily includes two aspects, abundant oxygen containing groups on the coal surface and porous surface of the coal particles. Therefore, it is of paramount importance to clean lignite by flotation. In this article, the effects of some process parameters for lignite flotation were studied. Laboratory experiments were carried out, and the effects of depressant (sodium silicate) dosage (0-1000 g/t), collector (kerosene) dosage (50-3000 g/t), frother (methyl isobutyl carbinol) dosage (15-1000 g/t), pulp pH (2-12), solid ratio (10%-20%), flotation time (1-7 minutes) and particle size (500-63 mu m) on flotation performance were investigated. A concentrate with 37.18% yield and 40.11% combustible recovery was obtained at 250 g/t sodium silicate (Na2SiO3), 250 g/t kerosene and 100 g/t methyl isobutyl carbinol (MIBC). Within the studied range, the optimum pulp pH was 2, the solid ratio was 10%, the flotation time was 5 minutes, and the particle size was -500 mu m. Under these optimum conditions, the ash content of lignite coal was reduced from 19.08% to 12.70%.