Dry Coal Cleaning Using Optical Sorting and Triboelectric Separation

The development, evaluation and commercialization of dry coal cleaning technologies have been the focus of a significant amount of research conducted worldwide over the last decade. Concerns over a shortage of water and the environmental impacts of wet coal cleaning facilities are the main reasons for the elevated interest. The proposed test program will evaluate the separation performance provided by XRT-based sorting technology when cleaning coal coarser than 20-mm. The XRT system has the ability of identifying the location of high-ash particles on a conveyor belt or the surface of a chute and removing the particles by focusing a jet of air on the particles upon discharge from the transport unit. A production unit of a XRT-based sorter will be utilized to treat run-of-mine Korean coal. Previous experience shows that data for the unit correlates well to full-scale units. Separation efficiency will be measured as a function of particle size using response parameters that include product ash content, mass yield, organic efficiency and probable error. The dry cleaning of coal with a particle size finer than 1-mm is achievable using triboelectric separation technologies. Researchers at the University of Kentucky have developed and patented a novel unit referred to as the Rotary Triboelectric Separator (RTS). The RTS provides high particle surface charge densities at low air speeds which enhances the process efficiency in the separation chamber. A detailed parametric test program will be conducted on the ultrafine size fractions of a Korean coal and the results used to quantify the optimum separation performance achievable.