Page 138 - Advanced Mine Ventilation

Characteristics of Respirable Coal Dust Particles 119

Figure 8.4 Graph of mass distribution for a low-volatile coal; n ¼ 1.00, k ¼ 15.5 mm.

The submicron (most dust particles found in human lungs) fraction of dust from
various coal types are as follows:

Anthracite 72%
Low-volatile coal 48%
High-volatile bituminous coal 39%
Lignite 44%

Lignite is mostly mined by surface mining and is not of concern for CWP.

8.6 Chemical Composition of Respirable Coal Dust

Coal seams are not all coal; it also contains rock bands in it. Besides, the roof and floor
are also mined to a little extent with coal. Calcium carbonate dust is profusely used in
mines to neutralize coal dust. Diesel engines, if used, add diesel particulate matter to
respirable coal dust. The resulting coal dust, therefore, contains many minerals and el-
ements in small proportions besides carbon.
Table 8.7 shows a typical analysis of mine dust.