Page 21 - Advanced Mine Ventilation

4 Advanced Mine Ventilation

1.1 Introduction to Coal Mining

Coal is the most abundant and the cheapest fossil fuel in the world today. Over the
past 200 years, it has played a vital role in the growth and stability of world economy.
20
The current world human population of about 7300 million consumes 5 10 Jof
energy per year. It is likely to increase to 7.5 10 20 J/year in the next 20 years. Fossil
fuels at present provide 87% of all energy consumed. Nuclear and hydro power pro-
vide 12%. Solar, wind, and geothermal energy barely provide 1% [1] as shown in
Table 1.1.
Barring a breakthrough in nuclear fusion, fossil fuels will remain the main source of
energy in the foreseeable future, as they have been in the past 200 years. Ninety
percent of all fossil fuel energy in the world is in coal seams. It is, therefore, natural
to anticipate that coal’s share in the energy mix will increase. At present, coal provides
26% of global energy demand and generates 41% of the world’s electricity. Coal
deposits are widespread in 70 countries of the world. Coal is a very affordable and reli-
able source of energy. The total proved, mineable reserve of coal exceeds 1 T tons to a
depth of about 3300 feet. Indicated reserves (mostly nonmineable) to a depth of
10,000 feet range from 17 to 30 T tons [2]. Current (2015) world coal production is
about 8000 million ton/year. Coal production from top 10 countries are shown in
Table 1.2 [3].
Total tonnage mined in these 10 countries comprises nearly 90% of global produc-
tion. Coal production may continue to increase if they start converting coal into syn-
thetic gases and liquid fuels, such as diesel and aviation fuels.
Coal mining is done in two ways: surface mining and underground mining. Most
thick and shallow deposits of coal are mined by surface mining methods. The depth
of surface mining is generally less than 200e300 feet. The overlying soil and rocks
are removed to expose coal before it is mined out. Nearly 50% of the global production
of coal is obtained by surface mining. The mine is open to the atmosphere, hence no
ventilation is needed.

Table 1.1 World Energy Reserve and Consumption
a b
Fuel Type Energy Consumed (EJ/year) Proved Reserve (ZJ)
Coal 120 290
Gas 110 15.7
Oil 180 18.4
Nuclear 30 2e17 c
Hydro 30 N.A.
All others 4 Uncertain

a 18
E ¼ 10 .
b 21
Z ¼ 10 .
c
reprocessing not considered. 1000 J ¼ 0.948 BTU.