Evaluation of Mineral Matter

The use of coal as a fuel and the varied, often detrimental, effects of the mineral matter on the fuel properties of coal has been a source of concern for consumers (Alpern et al., 1984). Even the interactions of the mineral constituents themselves (Table 7.9) have directed interest toward the mineral constituents of coals but with the tendency to an increased use of coal for power generation as well as for gasification and conversion plants that will enable coal to act as a source of liquid and gaseous fuels. Therefore, methods by which the mineral matter can be evaluated have been a constant target for quantitative and qualitative improvement. 

Furthermore, the broad definition which defines mineral matter as all elements in coal except carbon, hydrogen, nitrogen, oxygen, and sulfur needs some modification since four of these five elements occur in inorganic locations and are, therefore, part of the mineral matter. For example, (1) carbon occurs in carbonates (2) hydrogen occurs in water of hydration, as well as in any free water in the coal (3) oxygen occurs in carbonates, sulfates, and silicates as well as in water as well as in water of hydration and free water in the coal and (4) sulfur occurs in sulfates and sulfides, predominantly pyrite and marcasite. 

Finally, mineral matter in coal is the parent material in coal from which ash is derived and which comes from minerals present in the original plant materials that formed the coal, or from extraneous sources such as sediments and precipitates from mineralized water. Mineral matter in coal cannot be analytically determined and is commonly calculated using data on ash and ash-forming constituents. Coal analyses are calculated to the mineral matter-free basis by adjusting formulas used in calculations in order to deduct the weight of mineral matter from the total coal. 

Qays Loose structural OH groups with rearraugements of structure 

Carbonates Decompose with loss of COj residual oxides fix some 

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