Dry, mineral matter-free

Dry, mineral-matter-free basis except for moisture value. 

Coke Production. Coking coals are mainly selected on the basis of the quaUty and amount of coke that they produce, although gas yield is also considered. About 65—70% of the coal charged is produced as coke. The gas quaUty depends on the coal rank and is a maximum, measured in energy in gas per mass of coal, for coals of about 89 wt % carbon on a dry, mineral matter-free basis, or 30% volatile matter. 

Fixed carbon limits (dry, mineral-matter-free basis), % Volatile matter limits (dry, mineral-matter-free basis), % Gi (moist OSS calorific value limits mineral-matter-free basis) ... 

Volatile Matter corrected to dry mineral matter free basis... 

Table 1. Elemental compositions (dry mineral-matter free) for coalified wood samples...

M = equilibrium moisture, i. VM - volatile matter, S) PC = fixed carbon.St A - ash. sf S - sulfur. % Btu = high healing value. Btu per pound Rank FC = dry. mineral matter free fixed carbon. 51 Rank Blu — moist, mineral-matter-foee Blu per pound. 

Such data are necessary for calculation of parameters in the classification of coal by rank dry, mineral-matter-free volatile matter (or fixed carbon) as well as moist, mineral-matter-free gross calorific value. For volatile matter and fixed-carbon data, it is also necessary to assume that 50% by weight of the sulfur is volatilized in the volatile matter test and therefore should not be included as part of the organic volatile matter (nor should the loss from clays and carbonate minerals) ... 

Thus (Table 1.7), coal with a fixed carbon value in excess of 69% w/w or more, as calculated on a dry, mineral-matter-free basis, are classified according to the fixed-carbon value. Coal with a calorific value below 14,000 Btu/lb, as calculated on a moist, mineral-matter-free basis, is classified according to calorific value on a moist, mineral-matter-free basis, provided that the dry, mineral-matter-free fixed carbon is less than 69%. The agglomerating character is considered for coal... 

Class Group Fixed Carbon Limits (%, Dry, Mineral-Matter-Free Basis) Equal to or Greater Less Than Than Volatile Matter Limits (%, Dry, Mineral-Matter-Free Basis) Equal to or Greater Less Than Than Calorific Value Limits (Btu/lb, Moist, Mineral-Matter-Free Basis) Equal to or Greater Less Than Than Agglomerating Character... 

The fixed-carbon value is one of the values used in determining the efficiency of coal-burning equipment. It is a measure of the solid combustible material that remains after the volatile matter in coal has been removed. For this reason, it is also used as an indication of the yield of coke in a coking process. Fixed carbon plus ash essentially represents the yield of coke. Fixed-carbon values, corrected to a dry, mineral-matter-free basis, are used as parameters in the coal classification system (ASTM D-388). 

An ultimate analysis that can claim to represent the composition of the organic substance of a coal is said to be on a dry, mineral-matter-free (dmmf) basis. The dmmf basis is a hypothetical condition corresponding to the concept of a pure coal substance. Since the dry, ash-free basis for coal neglects changes in mineral matter when coal is burned, the dmmf basis is preferred whenever the mineral matter can be determined or calculated. 

If the determination of calorific value is carried out with a bomb calorimeter, the figure reported is usually corrected for the heat of formation of sulfuric acid and its dilution by water, but if the calorific value has to be reported on a dry, mineral-matter-free basis, the air-dried figure must be adjusted further to allow for the heat of formation of ferric oxide from the pyrites originally in the coal. The heat developed in the combustion of pyrite (FeSi) is approximately 3000 calories per gram of pyrite sulfur, so the correction to be applied is dependent on whether the calorific value is expressed as the heating power per gram or per pound. 

Rank property of coal that is descriptive of degree of coalification (i.e., the stage of metamorphosis of the original vegetal material in the increasing sequence peat, lignite, subbituminous, bituminous, and anthracite) (ASTM D-388). Anthracite rank of coal such that on a dry, mineral-matter-free basis, the volatile matter content of the coal is greater than 2% but equal to or less... 

The conversion to TS material in a dry, mineral-matter-free basis was calculated as... 

The values on a dry, mineral matter-free basis (dmmf) were obtained by using the modified Parr formula to calculate the mineral matter (m.m.) content ... 

At the time we wrote the manuscript for Reference (7), we were unable to relate the high fraction of transitional pores found in many of the coals to any other property of the coals. We have now concluded (11) that there are inflections in the scattering curves only for coals with fixed carbon contents in the interval from about 72% through 83% per cent (dry, mineral-matter free) and that for these coals, the specific surface of the transitional pores is appreciably larger than the specific surface of the macropores. As would be expected from our interpretation of the inflection (11), the specific surfaces of the transitional pores in all of the subbltumlnous coals in Table 1 except PSOC 138 are much larger than the specific surfaces of the macropores, and there is a tendency for the total x-ray specific surfaces [i. e., the sum of the specific surfaces of the macropores and transitional pores, as calculated by... 

The lignite samples from Carlos, Texas have heating values of 4000 to 6000 Btu/lb on an as-received basis or about 12000 Btu/lb on dry mineral-matter-free (dmmf) basis. The samples may... 

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