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Dry deshaling is receiving renewed attention in the coal-mining industry. In this methodology, high-density rock is removed from run-of-mine (ROM) coal at the mine extraction point and prior to shipping. One of the popular technologies used globally, the density-based vibrating air-table, was tested on a pilot-scale at three different coal-processing facilities in India. In this article, statistical analysis of the resulting test data was conducted using response surface methodology (RSM). The study identified that out of the four major operating parameters (i.e., tilt, slope, fan speed, and table vibrations), vibration frequency and its combined effect with slope impact the deshaling performance the most. In addition, empirical equations formulated using regression analyses were used for simultaneous optimization of the significant parameters in order to achieve the highest performance for the separation of Indian coals. The optimal operating conditions were determined using a desirability functi...

Coal mining and processing operations have in the past and continue to create large tonnages of fine coal and waste particles. While technological advances in wet processing has made it possible to efficiently recover coal fines, difficulties associated with dewatering make these fine particles unattractive economically for most coal markets. A novel system has been developed for cleaning fine raw coal utilizing a multistage dry classification process that removes the clay particles that are typically much smaller than the majority of the clean coal particles and that reduces the product surface moisture to as low as 1%. In this article, the novel dry coal-cleaning process under license to Greenfields Coal Company was evaluated. The classification process offers a viable alternative to traditional wet processing and dewatering of the fine particles, especially for operations recovering abandoned impoundments where a sufficient water source and/or a waste slurry disposal site are unavailable. This article ...

The potential of dry cleaning coal of varying ranks using a pneumatic table concentrator has been evaluated as part of an ongoing investigation. The evaluation has been performed at several sites throughout the United States where coal is extracted from surface open cast, highwall and underground operations as well as from coarse reject. The treated coals varied in feed ash content (i.e., 7–70%). Regardless of the mineral matter type, pure rock removal into the reject stream was achieved in all applications with little coal loss. Field data obtained when treating 50 × 6 mm run-of-mine bituminous coal indicate that 70–90% of the >2.0 Relative Density (RD) rock can be rejected. As a result, a clean product having acceptable market quality was generated from several coal sources including lignite, sub-bituminous, and bituminous coals. This article provides an overview of data from recent field testing of the dry air table technology and discusses the potential implementation strategy for the various sites ev...