Effect of Flotation Procedure and Composition of Reagents on Yield of a Difficult-to-float Coal

The paper discusses two procedures of flotation of difficult-to-float oxidized coal. The first one is the normal flotation procedure which relies on wetting coal with water followed by addition of flotation reagents (dodecane, dodecyl tetraoxyethelene ether (C12E4), and 1-pentanol). The second, direct contact procedure consists of mixing pure reagents with dry coal followed by addition of water. Investigation showed that for both procedures and applied chemicals, the yield – reagent dosage curves reached a plateau. The yield plateau level was 10 g/kg for normal flotation and 20 g/kg for direct contact flotation. At the plateau dosage, normal flotation provided a maximum clean coal yield of only 70% with mixed two-reagent (C12E4 + 1-pentanol). The second procedure resulted in a maximum clean coal yield of ~94 % using the same two reagent but at a higher dosage. It was also concluded that always two-reagent systems provided better flotation yields compared to one-reagent and three-reagent systems. Thus, flotation of difficult-to-float oxidized coal can be successfully accomplished by applying the direct contact flotation procedure with appropriate reagents.