Minerals

Abstract

AbstractAll coals contain a variety of non-combustible inorganic constituents that form ash when a coal is burned. The inorganic constituents can be present as discrete minerals or as ions attached to the carbonaceous structure. Some inorganic constituents were part of the original plant material, others were carried into the coal during the process of coalification, and still others may have precipitated into the coal after it formed. Ash is not a constituent of coal. Ash forms from various chemical reactions experienced by the inorganic constituents originally in the coal. Because ash results from the use of coal, the properties and behavior of ash can have significant impacts on coal utilization processes. In addition to the major components of most coals—quartz, clays, pyrite, and carbonates—coals also contain many elements at trace levels. Some of the trace elements could be valuable byproducts of coal use.