Continuous pilot scale testing of column flotation for recovery of fine coal

A series of performance studies has been conducted using countercurrent column flotation to recover a marketable clean coal product from existing preparation plant fine waste streams. The test work was conducted at several preparation plant sites in Kentucky and Virginia and utilized a 0.15m (6 in.) I.D. column that was 5.79m (19 ft.) high. The refuse streams tested included both thickener feed and classifying cyclone overflow with a typical size distribution of 100 mesh X 0. The percent solids of the column flotation feed varied from 1.5 to 15%, while the ash content ranged from 30-60%. The concentrates produced contained 2-10% ash with BTU recoveries of nearly 90% using 0.12-1.25 kg/ton (0.25-2.5 lbs/ton) fuel oil and 0.12 kg/ton (0.25 lb/ton) MIBC. These results were consistent with or better than results obtained in preliminary laboratory-scale column flotation evaluation. Test results from 7 different seams are discussed as well as scale-up relationships utilized to design a full-scale installation presently in operation.