Semi-anthracite and anthracite coals

Semi-anthracite and anthracite coals

Semi-anthracite and anthracite coals — these are also hard coals. They date back to the most ancient times and are the oldest fossilized hard coals.

They differ from hard coals by having a lower hydrogen content and a higher degree of carbonization. Semi-anthracites and anthracites are black in color, with a strong luster, and burn without flame and almost without smoke.

The composition of the working mass of semi-anthracites is approximately as follows (%): carbon C = 68.4, hydrogen H = 3.3, oxygen O = 3, nitrogen N = 1.5, sulfur S rt = 0.5, moisture W = 6.5%, ash A = 16.8. The calorific value of the working mass is Q = 26.0 MJ/kg (6210 kcal/kg).

The composition of anthracite coal differs slightly from that of semi-anthracite coal. Anthracite coal contains 68% carbon Crf, 1.5% hydrogen H, 1.9% oxygen O, 0.6% nitrogen, 1.5% sulfur S, 7.5% moisture W, and 19% ash. The heat of combustion of the working coal is Q = 24.2 MJ/kg (5790 kcal/kg).

Are coals classified according to the size of the pieces?

Coals with pieces measuring 50-100 mm are classified as large and are designated by the letter K; then come: nut O – piece size 25-30 mm, small M – piece size 13-25 mm, seed S – 6-13 mm, fine Sh – piece size less than 6 mm and, finally, ordinary P, for which the piece size is not limited; these coals are not sorted.