Page 43 - New Trends In Coal Conversion

Coal 11

Middle-East Middle-East 14
South America 70
South America Africa 211
ClS 351
Africa Pacific 835
116
Europe
Regions Pacific North America 700
CIS
Asia
5,123
Europe
North America

Asia
0 1,000 2,000 3,000 4,000 5,000 6,000
Million tonnes
Figure 1.8 Coal consumption (including all ranks of coal) by regions in 2016.
Data from Enerdata, 2017. Global Energy Statistical Yearbook 2017. https://yearbook.enerdata.
net/coal-lignite/coal-world-consumption-data.html.
(1984), Diessel (1992), Taylor et al. (1998), Ward and Su arez-Ruiz (2008) among
others, these parameters are briefly as follows:
1. Rank: It reflects the degree of metamorphism/coalification to which the peat has been sub-
jected during its burial history. Many of the fundamental properties of coal that are important
for industrial use are rank dependent (Ward, 1984; Taylor et al., 1998).
2. Type: Coal type reflects the nature of the plant debris from which the original peat was
derived, including the mixture of plant components (wood, leaves, roots, etc.) involved and
the degree of degradation to which they were exposed before burial. The individual plant com-
ponents occurring in coal, and in some cases fragments or other materials derived from them,
are referred to as macerals (ICCP, 1963, 1971, 1975, 1993, 1998, 2001; Sýkorov a et al., 2005;
Pickel et al., 2017), which are fundamental from the point of view of coal composition.
3. Grade: The grade of a coal reflects the extent to which the accumulation of plant debris has
been kept free of contamination by inorganic material (mineral matter), including the periods
before burial (i.e., during peat accumulation), after burial, and during rank advance. A high-
grade coal is therefore a coal, regardless of its rank or type, with a low proportion of mineral
matter, and hence a high organic matter content (Ward and Su arez-Ruiz, 2008).
The parameters, type and grade, of a coal describe the coal composition. Therefore,
coal rank and coal composition are the key characteristics that determine the physico-
chemical properties of a coal.

1.5.1 Fundamental characteristics of coal
Coal is in its very nature a heterogeneous material and macroscopically can be classi-
fied into the following two categories or types:
1. Humic coals or banded coals, which are the most commonly found in nature, are derived
from a heterogeneous mixture of a wide range of plant debris. In general, commercial coals