Page 146 - Advanced Mine Ventilation

Generation of Respirable Coal Dust 127

Table 9.2 Chemical and Petrological Properties of Coals

Fixed
Moisture Dry Volatile Carbon Fixed
Sample Percent as Ash Percent Percent Carbon/ Fusain
Number Received Percent (DAF) (DAF) Volatile Percent
1 3.28 7.84 6.13 93.87 14.29 3.70
2 4.07 9.16 6.35 93.65 14.29 27.70
3 1.04 27.74 12.63 87.37 7.15 17.40
4 2.08 3.90 37.62 62.38 1.67 6.00
5 1.74 4.65 37.73 62.27 1.64 11.10
6 1.81 4.50 37.99 62.01 1.64 17.10
7 2.04 1.26 34.10 65.90 1.92 7.50
8 1.88 5.15 37.85 62.15 1.64 5.50
9 1.46 6.23 38.22 61.78 1.61 3.40
10 1.93 6.01 34.01 65.99 1.92 24.90
11 1.73 17.35 39.63 60.37 1.50 14.50
12 4.89 11.83 41.90 58.10 1.39 5.50
13 12.10 10.84 45.66 54.34 1.19 3.20
14 20.47 5.24 46.67 53.33 1.14 10.70
15 1.67 6.34 19.82 80.18 4.04 7.40
16 1.82 6.39 23.01 76.99 3.32 11.20
17 28.07 8.17 45.81 54.19 1.18 12.00
18 28.92 11.92 46.55 53.45 1.15 13.30

annular ring, A. Because of the constant rotary motion of the sample container, the
cylindrical weight and annular ring exert a constant pressure on the container wall,
and coal particles caught in between are crushed to finer sizes. A fixed amount of
energy was expended on a sample of given mass of uniformly sized material. This
permitted the evaluation of the effect of the properties of coal alone on the production
of respirable coal dust.
A Bleuler mill provides an efficient and rapid means for grinding samples and meets
the requirements of reproducibility of particle size distribution for optical and X-ray
fluorescence spectrographic studies. The time of grinding can be preset and is
controlled electrically.

9.2.2 Procedure for Grinding
Twenty grams of the closely sized material was ground for 1 minute in the Bleuler
mill. The crushed material was sieved through a 400-mesh (37 mm) Tyler screen on