Determination of Weathering of Coal Using pH Values of the Coal Slurry.

During transportation and stockpiling, coal is in contact with air for periods of time that may exceed 6 months. During this time, reaction with oxygen in the presence of water, sunlight, and possibly elevated temperatures may take place. The resulting weathered coal suffers some alteration in its physical and chemical properties. This article describes weathering with reference to coking coal, and its importance in understanding the weathering of coal. In this article, the effect of weathering on coal quality is discussed. Two Indian coals were kept for a period of 2 months, and different coal properties such as free swelling index (FSI), ash, and slurry pH were monitored at different intervals. This article suggests pH determination of coal slurry technique is more reliable for monitoring weathering of the Indian coal. [ABSTRACT FROM AUTHOR]