Management of coal preparation fine wastes without disposal ponds

Abstract

In the beneficiation of coal, the common medium for upgrading the mined coal is water. The end products of coal beneficiation are generaly three materials; (1) the clean coal, (2) coarsely sized waste product, and (3) a finely sized waste product. As the need for cleaner coal increases, the amount of waste products generated also increases and the importance of safe, environmentally acceptable disposal of these wastes becomes more important. Generally, the coarse refuse (plus 28 mesh) can be disposed of safely because it is a solid with inherent engineering properties that can be utilized in engineered structrues. However, the fine refuse (minus 28 mesh) generally exists as a water-based slurry devoid of significant engineering properties that can be employed in engineering disposal methods. The objective of this study is to ascertain some physical/chemical properties of a diverse sampling of fine coal refuse and to investigate the effect of chemical stabilization. Samples of fine coal refuse were obtained from some of the major coal seams in the Eastern bituminous coal fields. Two common and one proprietary chemicals were employed in testing chemical stabilization on nine samples of fine coal refuse. This study indicated that chemical stabilization can be employed tomore » drastically improve some physical/chemiccal properties of the fine refuse for better handling and disposal. The proprietary chemical, Calcilox additive, is the most effective over the range of samples tested. Portland Type I cement is also effective but greatly influenced by waste solids concentration. The final chemical tested, lime, is inferior to the other two chemicals and generally ineffective in improving the fine waste's physical/chemical properties.« less