Fine Coal Recovery Utilizing Landfill-Derived Liquids

Liquid effluents that arise in the landfilling of municipal solid wastes, both leachate and gas condensates, can replace some or all of the conventional coal flotation reagents. The waste management industry currently must treat these effluents, to destroy contained organics, prior to their discharge to the environment and hence they are available at no cost, or even with “dollars attached”. These landfill-derived liquids contain valuable short-chain fatty acids (e.g. valeric and caproic acids) that act as both frother and collector in flotation processes. They can be further concentrated by membrane filtration to reduce the transport costs of such liquids and the ease of their use in coal recovery systems. This paper will discuss how these liquids are formed in landfills, their typical compositions and how they can be employed to recover fine coal. Data from both conventional flotation feeds (-0.5 mm) and column flotation feeds (-0.1 mm) is presented.