Decomposition Moisture—The Hidden Reactive Constituent in Coal

Abstract

Abstract When coals are heated to temperatures of 200°C–250°C, moisture from the decomposition of organic materials, such as humic acids, is driven off. This moisture is decomposition moisture. Very little information is known about decomposition moisture, and there are no known examples of the quantification of this type of moisture in coal. The amount of decomposition moisture in coal is assumed to be relatively small. Recent studies involving the rapid drying of coal have shown that moisture that evolves around 200°C plays a significant role in the determination of the volatile matter yields of most ranks of coal. It is assumed that this moisture is decomposition moisture. A series of experiments were performed to study this moisture, including how to identify and quantify it. Analytical techniques including thermogravimetric analysis, derivative thermogravimetry, and carbon and hydrogen analysis were employed in the study. All these techniques were needed to quantify the decomposition moisture evolved from various ranks of coal. The decomposition moisture in the coals studied ranged from 0.03 to 2.07 %.