The Flotation Response of Dedo Coal Deposit, Jimma, Ethiopia: Implication to Improve the Quality of Coal

Ethiopia possesses considerable coal resources, but their low grade, marked by high ash and moisture, restricts industrial utilization. This work examined how run-of-mine coal from the Dedo deposit in Jimma Zone, south-western Ethiopia, responds to froth flotation, with the goal of raising its quality. Duplicate batch tests were run in a laboratory Wedag flotation cell to assess how particle size (−500+250 µm and −125+63 µm) and impeller speed (1500 and 2500 rpm) influence concentrate yield. Kerosene served as the collector and n-octanol as the frother, and the feed mass, conditioning time and reagent dosages were kept fixed. Proximate analysis, sulfur content and calorific value were used to characterize both the raw coal and the floated concentrate. Mean concentrate yield varied from 48.0% for the coarse fraction at 1500 rpm up to 66.5% for the fine fraction at 2500 rpm, which shows that, within the ranges tested, finer particles and a higher impeller speed improved flotation. Compared with the raw coal, the concentrate produced under the best conditions contained less ash (25.66% to 20.28%), moisture (13.63% to 11.06%), volatile matter (33.45% to 25.63%) and sulfur (0.36% to 0.25%), and had a higher calorific value (4806 to 5029.38 cal/g), while fixed carbon increased (27.26% to 43.03%). The findings suggest that froth flotation can give a cleaner, more energy-rich product from Dedo coal; however, the calorific value gain was small (about 4.6%), and only two levels of two variables were investigated. Before process conditions for industrial use can be defined, the effects of collector and frother dosage, solids concentration, pH, air flow rate and conditioning time, as well as the composition of the flotation tailings, still need to be assessed.