Quality Assessment of Igaliwo and Olokwu Coals in the Northern Anambra Basin of Nigeria

Quality Assessment of Igaliwo and Olokwu Coals in the Northern Anambra Basin of Nigeria
Quality Assessment of Igaliwo and Olokwu Coals in the
Northern Anambra Basin of Nigeria
*1Fatoye Felix Bamidele and 2Mepaiyeda Seyi
1,2Department of Mineral and Petroleum Resources Engineering, Kogi State Polytechnic, Lokoja, Nigeria
Chemical and geochemical studies have been carried out on coal samples from Igaliwo and
Olokwu coal deposits in northern Anambra Basin of Nigeria. The studies were carried out
principally to determine the chemical and geochemical characteristics of the coals in order to
ascertain their potential relevance to possible industrial usages. Proximate analysis indicated that
the moisture content of the coal samples, on average, varied from 19.27% in Olokwu coal to
20.37% in Igaliwo coal, ash content from 4.88% in Olokwu coal to 6.48% in Igaliwo coal, volatile
matter content from 36.39% in Igaliwo coal to 37.97% in Olokwu coal, and fixed carbon content
from 36.76% in Igaliwo coal to 37.88% in Olokwu coal. Ultimate analysis revealed that the
percentage of carbon in the coals, on average, ranged from 52.01% in Igaliwo coal to 54.74% in
Olokwu coal, hydrogen from 4.34% in Igaliwo coal to 4.49% in Olokwu coal, nitrogen from 1.41%
in Igaliwo coal to 1.42% in Olokwu coal, oxygen from 14.42% in Igaliwo coal to 14.43% in Olokwu
coal, sulphur from 0.78% in Olokwu coal to 0.98% in Igaliwo coal, and phosphorus from 0.001%
in Olokwu coal to 0.003% in Igaliwo coal. The heating (calorific) values of the coals, on average,
varied from 9275 Btu/Ib in Igaliwo coal to 9740 Btu/Ib in Olokwu coal. Generally, both coals have
low free swelling index (FSI) of zero (0). These characteristics put together suggest that both coals
cannot be used by the steel industry, mostly for the manufacture of coke for metallurgical
processes such as iron and steel production. However, they are suitable for electricity generation,
heating boilers and ovens in industrial process heating, manufacturing organic chemicals and
production of gas and automotive fuel.
Keywords: Igaliwo Olokwu coals, low quality, non-coking and sub-bituminous.
INTRODUCTION
Coal was first discovered in Nigeria in 1909 at the Udi near
Enugu within the Anambra Basin in 1909 by the Mineral
Survey of Southern Nigeria (Orajaka et al., 1990;
Famuboni, 1996). Between 1909 and 1913, more coal
seams were discovered within the Basin at Enugu and
Ezimo in Enugu State; Orukpa in Benue State; Odokpono,
Okaba and Ogboyaga in Kogi State. These seams belong
to the Mamu Formation (Lower Coal Measures) of Middle
Campanian – Late Maastrichtian age (Simpson, 1954).
Coal seams of the Nsukka Formation (Upper Coal
Measures) of Late Maastrichtian – Paleocene age
outcropped at Inyi west of the Enugu Escarpment (De-
Swardt and Casey, 1963).
Intensive exploration and exploitation activities
commenced in 1916 at Ogbete drift mine near Enugu.
Over time, other mines sprang up in the region within the
Anambra Basin. In 1950, the Ogbete mine’s operations
and others in the country were merged into a new
Corporation called the Nigerian Coal Corporation (NCC)
with responsibility to manage the resources produced at
these mines.
Production started from a modest beginning (24,903
tonnes in 1916) and gradually rose to an annual output of
about 742,922 tonnes in 1966 just before the outbreak of
the Nigerian civil war (NCC, 1974; NCC, 1982). During this
period of growth, coal played a significant role in Nigeria’s
economic development. Coal was mainly utilised by the
Nigerian Railway Corporation (NRC) to operate its
locomotives, by the Electricity Corporation of Nigeria
*Corresponding Author: Dr. Fatoye Felix Bamidele;
Department of Mineral and Petroleum Resources
Engineering, Kogi State Polytechnic, Lokoja, Nigeria.
Email: feliztoye@yahoo.com
Research Article
Vol. 6(1), pp. 309-317, January, 2020. © www.premierpublishers.org. ISSN: 3019-8261
International Journal of Geology and Mining

Fatoye and Mepaiyeda 310
(ECN) later National Electric Power Authority (NEPA)
again changed to Power Holding Company of Nigeria
(PHCN) and now Electricity Distribution Company (EDC)
for the generation of electricity; and by the Nigerian
Cement Company (NIGERCEM) at Nkalagu for firing its
kilns.
However, coal production has steadily declined in the last
few decades due to the loss of two of its traditional
customers, who switched from coal to diesel, natural gas
and hydro resources for the generation of electricity and
for transportation services. Coal has been relegated to the
background especially after oil was discovered in
commercial quantity in Nigeria, and the country became
over-dependent on it as its primary source of energy.
The Nigerian civil war was another major factor in the
decline of coal production in the country. A number of coal
mines became inaccessible during the period and were
abandoned. Most of the abandoned mechanizing
production ended badly, as both the implementation and
maintenance of imported mining equipment proved
troublesome, and hurt production (NCC, 2011).
Nevertheless, the Federal Government is currently
planning to revitalize the coal mining industry and expand
power generation by attracting foreign companies to
develop these large coal resources and construct coal-
fired generating plants that will connect to the country’s
electrical distribution grid.
The Nigerian coal industry must be seen as a long
neglected economic frontier that needs urgent
resuscitation. It is one major area that can change the
economic fortune of this great country. Its potential for
growth is on the upward swing.
Therefore, this research work is aimed at investigating the
chemical and geochemical characteristics of Igaliwo and
Olokwu coal deposits in order to ascertain their potential
relevance to possible industrial usages.
Location of the Study Area
Igaliwo coal deposit is situated on Latitude 70 38' 23 .3'' N
and Longitude 70 35'48.7'' E while Olokwu coal deposit is
situated on Latitude 70 37' 50.2'' N and Longitude 70 37'
29.3'' E. Both deposits are located off Abejukolo road in
Omala Local Government Area of Kogi State (Figure 1).
Figure 1: Location map of the study area (modified from map of Nigeria).
Regional Geological Setting
The study area lies within the Anambra Basin of Nigeria.
The structural setting and general geology of the Anambra
Basin have been documented by various workers
(Reyment, 1965; Kogbe, 1989; Nwajide, 1990; Nwajide
and Reijers, 1996; Obaje et al., 1999). Sedimentation in
the Anambra Basin commenced with the Campanian –
Maastrichtian marine and paralic shales of the Nkporo
Formation (Figure 2), overlain by the Early – Late

Int. J. Geol. Min. 311
Figure 2: Geological map of the study area.
Maastrichtian coal measures of the Mamu Formation,
comprising paralic sandstones, mudstones and coals. The
Middle – Late Maastrichtian fluviodeltaic sandstones of the
Ajali Formation lie on the Mamu Formation and constitute
its lateral equivalents in most places. In the Paleocene, the
marine shales and paralic coaly sequence of the Nsukka
Formation were deposited to complete the succession in
the Anambra Basin (Umeji, 2005).
MATERIALS AND METHODS
Ten coal samples of approximately 300g each were
collected from each of the two coal deposits (Igaliwo and
Olokwu coal deposits). The samples were taken from the
coal’s outcrops. Samples collected were kept in an airtight
polyethylene bags prior to analyses. The coal samples
were pulverized and sieved to pass 60 mm sieve size. All
analytical determinations were done according to the
American Standard for Testing Materials (ASTM) 1992
standards methods. All sample analyses were carried out
at Mineral Laboratory, Kentucky, USA.
Proximate Analysis
Chemical composition of the coals was defined in terms of
their proximate analysis. The parameters of proximate
analysis are moisture, volatile matter, ash, and fixed
carbon.
Determination of Moisture Content: Exactly 1.00g of the
pulverized sample of each coal was placed in separate
pre-weighted silica crucibles and subjected to a
temperature of 1050C for 1 hour in the absence of air, until
a constant weight was attained.
Determination of Ash Content: Exactly 1.00g each of
pulverized samples were weighted into three separate
platinum crucibles and subjected to a temperature of
7500C in a muffle furnace for about 2 hours until a constant
weight was attained.
Determination of Volatile Matter: 1.00g of pulverized
sample of each coal was weighted and covered in a 10ml
platinum crucible. The same was subjected to a
temperature of 9500C in a muffle furnace for 7 minutes.
Determination of Fixed Carbon: The fixed carbon is said
to be the difference of the sum total of moisture, ash and
volatile from 100%, that is;
Fixed Carbon (%) = 100 – (% moisture content + %
ash content + % volatile matter content).
Ultimate Analysis
Geochemical composition of the coals was defined in
terms of their ultimate analysis. Ultimate (Elemental)
analysis is dependent on quantitative analysis of various
elements present in the coal samples, such as carbon,
hydrogen and oxygen (the major components) as well as
nitrogen, sulphur and phosphorus.
Determination of Carbon and Hydrogen: 1.00g of coal
is burnt in a current of oxygen thereby converting C and H
of coal into CO2 and H2O respectively. The products of
combustion (CO2 and H2O) were passed over weighted

tubes of anhydrous CaCl2 and KOH which absorbed H2O
and CO2 respectively. The increase in the weight of CaCl2
tube represents the weight of water (H2O) formed while
increase in the weight of KOH tube represents the weight
of CO2 formed. The percentage of carbon and hydrogen
was then calculated.
Determination of Nitrogen: Nitrogen was determined by
Kjeldahal’s method. 1.00g of pulverized coal was heated
with concentrated H2SO4 in the presence of potassium
sulphate and copper sulphate in a long-necked flask
thereby converting nitrogen of coal to ammonium sulphate.
When clear solution was obtained it was treated with 50%
NaOH solution. The ammonia thus formed was distilled
over and absorbed in a known quantity of standard
sulphuric acid solution. The volume of unused H2SO4 was
then determined by titrating against standard NaOH
solution. Thus, the amount of acid neutralized by liberated
ammonia was determined.
Determination of Oxygen: Oxygen is traditionally
determined by subtracting the amount of the other
elements, carbon, hydrogen, nitrogen, sulphur, moisture
and ash from 100%.
% of oxygen in coal = 100 – (% C + % H + % N + % S + %
M + % A)
Determination of Sulphur: A 1.00g sample of coal of
0.2mm particle size was heated with Eschka mixture
(which consists of 2 parts of MgO and 1 part of anhydrous
Na2CO3) at 8000C. After burning amount of sulphur
present in the mix was retained as oxides and it was
precipitated as sulphate. The sulphate formed was
precipitated as BaSO4 (by treating with BaCl2). The
percentage of sulphur in coal was calculated from the
weight of coal sample taken and weight of BaSO4
precipitate formed.
Determination of Phosphorus: Phosphorus was
determined by treating 1.00g of the coal ash with a hot
mixture of HNO3, H2SO4 and HF acids. This volatilized the
silica and dissolved the phosphorus to precipitate a
complex phospho-molybdate from which the phosphorus
content was estimated.
Calorific Value Analysis
A bomb calorimeter was used to measure the calorific
value of the coal. A bomb calorimeter is a type of constant-
volume calorimeter used in measuring the heat of
combustion of a particular reaction. Bomb calorimeters
have to withstand the large pressure within the calorimeter
as the reaction is being measured. Electrical energy was
used to ignite the coal; as the coal was burning, it heated
up the surrounding air, which expanded and escaped
through a tube that leads the air out of the calorimeter.
When the air was escaping through the copper tube it also
heated up the water outside the tube. The change in
temperature of the water was then accurately measured
with a thermometer. This reading, allowed for calculating
calorie content of the coal.
Determination of Free Swelling Index
10.00g of finely grounded coal sample was weighed into a
dry platinum crucible. The crucible was placed in a muffle
furnace and the temperature raised to 800oC for 2 hours
or until all volatiles were driven off. The crucible was
removed from the furnace and allowed to cool naturally.
The cross section of the coke “button’ was then compared
to a series of standard profiles (chart) to determine the free
swelling index.
RESULTS AND DISCUSSION
Proximate analysis revealed that the studied coals are
characterized by high moisture, medium to high ash,
medium to high volatile matter and low fixed carbon
contents. Comparing these characteristics with other coals
(X, Y and Z in Tables 1 and 2), the studied coals are similar
to Saar (Germany) sub-bituminous coal but contrast with
Newcastle (England) bituminous coal and South Wales
(Britain) anthracite thereby placing Igaliwo and Olokwu
coals in sub-bituminous rank.
The average moisture content of Igaliwo coal is 20.37%
(Table 1) while that of Olokwu coal is 19.27% (Table 2).
The moisture content of the two coals is very high
compared with high rank coals (Tables 1 and 2). This high
moisture content would result in a decreased plant
capacity and an increase in operating costs (Jauro et al.,
2008) with consequent decrease in the calorific value and
the concentration of other constituents (IEA/OECD, 2002).
Moisture is an undesirable constituent of coals because it
reduces the heating value (water does not burn!) and its
weight adds to the transportation costs of coal. The
moisture content required for good coking coal is 1.5%
(Obaje, 1997). However, the Central Fuel Research
Institute (CFRI), India in Chukwu et al. (2012) stipulated a
range of 1 – 4% moisture for semi-coke used in low shaft
furnace. Therefore, the values recorded in Igaliwo and
Olokwu coals are above the stipulated rating for coking
coal. However, based on Gunn et al. (2012)
recommendation of maximum 18 – 30% moisture content
for thermal coals, the coals are suitable for generation of
electricity and heating for manufacturing of cement,
ceramics, glass, paper, bricks, etc.
The average ash content of Igaliwo coal is 6.48% (Table
1) and that of Olokwu coal is 4.88% (Table 2). Lower ash
content is an essential requirement for coke making coals,
because some of the ash would end up in the coke on
carbonization and in the blast furnace (Akpabio, 1998).
The lower the ash content of a coal, the better its
application as a source of fossil fuel especially in the steel
industry (Wessiepe, 1992). Ash reduces plasticity and
determines the behaviour of slag and fouling in

Table 1: Proximate Analysis Results of Igaliwo Coal Samples
Sample Moisture Ash Volatile Fixed Total
Number Content Content Matter Carbon
(%) (%) (%) (%) (%)
Igaliwo 1 20.05 4.58 37.83 37.54 100.00
Igaliwo 2 20.68 8.38 34.96 35.98 100.00
Igaliwo 3 20.11 4.35 38.37 37.17 100.00
Igaliwo 4 20.27 7.54 36.15 36.04 100.00
Igaliwo 5 20.67 8.25 35.46 35.62 100.00
Igaliwo 6 20.56 5.17 37.21 37.06 100.00
Igaliwo 7 20.34 6.50 36.31 36.85 100.00
Igaliwo 8 20.19 7.73 35.53 36.55 100.00
Igaliwo 9 20.43 4.78 36.50 38.29 100.00
Igaliwo 10 20.40 7.52 35.58 36.50 100.00
Average 20.37 6.48 36.39 36.76 100.00
X 15.10 12.35 46.10 26.45 100.00
Y 4.31 0.20 31.26 64.23 100.00
Z 3.15 1.32 21.63 73.90 100.00
X: Saar (Germany) sub-bituminous coal (after Jensen and Bateman, 1979)
Y: Newcastle (England) bituminous coal (after Jensen and Bateman, 1979)
Z: South Wales (Britain) anthracite (after Jensen and Bateman, 1979)
Table 2: Proximate Analysis Results of Olokwu Coal Samples
Sample Moisture Ash Volatile Fixed Total
Number Content Content Matter Carbon
(%) (%) (%) (%) (%)
Olokwu 1 19.01 5.91 37.52 37.52 100.00
Olokwu 2 19.48 3.85 38.43 38.24 100.00
Olokwu 3 18.89 5.84 37.65 37.62 100.00
Olokwu 4 19.43 3.83 38.11 38.63 100.00
Olokwu 5 19.37 4.93 38.02 37.68 100.00
Olokwu 6 18.96 5.98 37.59 37.47 100.00
Olokwu 7 19.39 4.86 37.98 37.77 100.00
Olokwu 8 19.28 5.72 37.81 37.19 100.00
Olokwu 9 19.44 3.81 38.32 38.43 100.00
Olokwu 10 19.41 4.07 38.27 38.25 100.00
Average 19.27 4.88 37.97 37.88 100.00
X 15.10 12.35 46.10 26.45 100.00
Y 4.31 0.20 31.26 64.23 100.00
Z 3.15 1.32 21.63 73.90 100.00
X: Saar (Germany) sub-bituminous coal (after Jensen and Bateman, 1979)
Y: Newcastle (England) bituminous coal (after Jensen and Bateman, 1979)
Z: South Wales (Britain) anthracite (after Jensen and Bateman, 1979)
combustion chamber (ASTM, 1987). The high ash content
is also an indication of low degree of coalification and
hence immaturity of the coal. An ash content of less than
10% is recommended for good coking coals (Akpabio et
al., 2008; Bustin et al., 1985; Averitt, 1974). Industrial
experience indicates that a 1% weight increase of ash in
the coke reduces metal production by 2 or 3% weight (Diez
et al., 2002). Maximum of 10 – 20% is recommended by
Thomas (2002) in coking coals, as higher ash contents
reduce the efficiency in the blast furnace. However, coking
coal with ash content up to 20% are being used for
smelting iron in some parts of the world (Afonja, 1974). In
such cases, coke and flux consumption per tonne of pig
iron produced is relatively high. In a steam coal, high ash
content will effectively reduce its calorific value.
Recommended maximum ash contents for steam coals for
use as pulverized fuel are around 20% (Thomas, 2002).
Though the ash content of both coals is within the less than
10% recommended for good coking coals by Akpabio et
al. (2008); Bustin et al. (1985) and Averitt (1974), but their
high moisture content make them unsuitable for coke
making. However, the coals are appropriate for electricity
generation and heating for manufacturing processes
based on less than 20% ash content proposed for steam
coals by Thomas (2002).
The average volatile matter content of Igaliwo coal is
36.89% (Table 1) while that of Olokwu coal is 37.97%
(Table 2). Volatile matter represents the components of
coal, except for moisture which are liberated at high

temperature in the absence of air. Volatile matter includes
light hydrocarbon compounds such as carbon dioxide
(CO2), methane (CH4), etc that were yielded by the
decomposition of each layer of dead plant material by
aerobic or oxygen-requiring bacteria during coalification.
Volatile matter also includes hydrogen, oxygen, nitrogen,
sulphur, phosphorus and carbon that are lost in the form
of gases and vapour on carbonization. The high volatile
matter content in most of the coals is a reflection of the
exceptionally large proportion of hydrogen in the coals
(Orajaka et al., 1990). In pulverized fuel firing for electricity
generation, most boilers are designed for a minimum
volatile matter of 20 – 25%. In stoker firing for electricity
generation, the volatile matter limits recommended are 25
– 40% (Thomas, 2002). There is virtually no limit for the
volatile matter for coals used in the production of cement.
In coke production, high volatile matter content will give a
lower coke yield so that the best quality coking coals have
a volatile range of 20 – 35% but values of 16 – 36% can
be used (Thomas, 2002). Bustin et al. (1985)
recommended a much lower value of less than 1.5%
volatile matter for good metallurgical coal. The volatile
matter apart from its use in coal ranking is one of the most
important parameters used in determining their suitability
and applications (U.S. Energy Information Administration,
2008; Chen and Ma, 2002). The volatile matter of Igaliwo
and Olokwu coals is in consonance with the reports of
(Okolo, 1988) who observed that Nigerian coals have high
volatile matter and as such are potential sources of energy
and feedstock for the chemical and allied industries. Based
on volatile matter content proposed for coking coals by
Thomas (2002), both Igaliwo and Olokwu coals are
unsuitable for coke making. However, the coals are
appropriate for electricity generation and heating for
manufacturing processes.
The average fixed carbon content of Igaliwo coal is 36.76%
(Table 1) and that of Olokwu coal is 37.88% (Table 2). The
coals are characterized by low fixed carbon content
compared with high rank coals (Tables 1 and 2). The fixed
carbon content of a coal has a direct relation with its
moisture and volatile matter, therefore, the low fixed
carbon content in the coals is as a result of their high
moisture and volatile matter contents. Fixed carbon
content determines the coke yield of coal samples (Diez et
al., 2002; Schobert, 1987). High carbon content is
essential for coke making coal because it is the mass that
forms the actual coke on carbonization (Diez et al., 2002).
Maximum of 46 – 86% is recommended by Lowry (1945)
in coking coals. Both coals contain very low fixed carbon
below the recommended rating for coking coals given by
Lowry (1945). However, they could be utilized in thermal
power plants and other small industries for combustion
processes.
Table 3 Ultimate Analysis and Calorific Value Results of Igaliwo Coal Samples
Sample Carbon Hydrogen Nitrogen Oxygen Sulphur Phosphorus Total Calorific Value
Number (%) (%) (%) (%) (%) (%) (%) (Btu/Ib) (KJ/Kg)
Igaliwo 1 54.14 4.53 1.49 14.27 0.94 0.001 75.37 9661 22471.486
Igaliwo 2 49.88 4.15 1.33 14.56 1.01 0.004 70.93 8889 20675.814
Igaliwo 3 53.24 4.20 1.35 14.37 0.97 0.003 74.13 9763 22708.738
Igaliwo 4 52.86 4.33 1.41 14.46 0.97 0.004 74.03 9020 20980.520
Igaliwo 5 50.98 4.50 1.45 14.23 1.01 0.004 72.17 9445 21969.070
Igaliwo 6 53.62 4.24 1.27 14.31 0.96 0.003 74.40 8937 20787.462
Igaliwo 7 51.33 4.47 1.46 14.44 1.01 0.002 72.71 9568 22255.168
Igaliwo 8 52.71 4.31 1.44 14.51 0.95 0.004 73.92 8890 20678.140
Igaliwo 9 49.90 4.51 1.47 14.50 0.98 0.003 71.36 9304 21641.104
Igaliwo 10 51.44 4.16 1.43 14.55 1.00 0.002 72.58 9273 21568.998
Average 52.01 4.34 1.41 14.42 0.98 0.003 73.16 9275 21573.650
X 67.60 4.80 1.20 17.70 0.80 0.06 92.16 8683 20196.658
Y 83.47 6.68 0.59 8.00 0.20 0.04 98.98 12000 27912.000
Z 91.44 3.36 0.09 2.70 0.09 0.03 97.71 15700 36518.200
X: Wyoming (USA) sub-bituminous coal (after Spath and Amos, 1995)
Y: Newcastle (England) bituminous coal (after Jensen and Bateman, 1979) and San Pedro (USA) bituminous coal
(after Warwick and Hook, 1995)
Z: South Wales (Britain) anthracite (after Jensen and Bateman, 1979) and Barakar (India) Anthracite (after Sethi,
2014)

Table 4: Ultimate Analysis and Calorific Value Results of Olokwu Coal Samples
Sample Carbon Hydrogen Nitrogen Oxygen Sulphur Phosphorus Total Calorific Value
Number (%) (%) (%) (%) (%) (%) (%) (Btu/Ib) (KJ/Kg)
Olokwu 1 54.20 4.41 1.46 14.15 0.83 0.001 75.05 9614 22362.164
Olokwu 2 55.28 4.57 1.38 14.71 0.72 0.001 76.66 9865 22945.990
Olokwu 3 53.76 4.63 1.42 14.52 0.79 0.001 76.12 9533 22173.758
Olokwu 4 54.63 4.25 1.45 14.41 0.75 0.001 75.49 9721 22611.046
Olokwu 5 55.12 4.67 1.36 14.63 0.78 0.001 76.56 9852 22915.752
Olokwu 6 54.53 4.38 1.50 14.49 0.77 0.001 75.67 9861 22936.686
Olokwu 7 54.82 4.45 1.31 14.56 0.79 0.001 75.93 9796 22785.496
Olokwu 8 54.46 4.53 1.56 14.33 0.72 0.001 75.60 9807 22811.082
Olokwu 9 54.70 4.32 1.27 13.97 0.88 0.001 75.14 9587 22299.362
Olokwu 10 54.90 4.69 1.49 14.53 0.77 0.001 76.38 9764 22711.064
Average 54.74 4.49 1.42 14.43 0.78 0.001 75.86 9740 22655.240
X 67.60 4.80 1.20 17.70 0.80 0.06 92.16 8683 20196.658
Y 83.47 6.68 0.59 8.00 0.20 0.04 98.98 12000 27912.000
Z 91.44 3.36 0.09 2.70 0.09 0.03 97.71 15700 36518.200
X: Wyoming (USA) sub-bituminous coal (after Spath and Amos, 1995)
Y: Newcastle (England) bituminous coal (after Jensen and Bateman, 1979) and San Pedro (USA) bituminous coal
(after Warwick and Hook, 1995)
Z: South Wales (Britain) anthracite (after Jensen and Bateman, 1979) and Barakar (India) Anthracite (after Sethi,
2014)
Ultimate analysis indicated that the studied coals are also
characterized by low carbon, medium to high hydrogen,
high nitrogen and high oxygen contents. Comparing these
characteristics with other coals (X, Y and Z in Tables 3 and
4), the studied coals are similar to Wyoming (USA) sub-
bituminous coal but contrast with Newcastle (England)
bituminous coal and South Wales (Britain) anthracite
thereby placing Igaliwo and Olokwu coals in sub-
bituminous rank.
The average carbon content of Igaliwo coal is 52.01%
(Table 3) while that of Olokwu coal is 54.74% (Table 4),
and the average hydrogen content of Igaliwo coal is 4.34%
(Table 3) while that of Olokwu coal is 4.49% (Table 4).
Carbon and hydrogen are the principal combustible
elements in coal. Maximum of 75 – 90% carbon and 4.5 –
5.5% hydrogen is recommended by Lowry (1945) in coking
coals. Based on carbon content, Igaliwo and Olokwu coals
have no coking ability, hence unsuitable for coke
production for metallurgical processes. However, they are
appropriate for electricity generation and heating for
manufacturing processes.
The average nitrogen content of Igaliwo coal is 1.41%
(Table 3) while that of Olokwu coal is 1.42% (Table 4), and
the oxygen content of Igaliwo coal is 14.42% (Table 3)
while that of Olokwu coal is 14.43% (Table 4). The nitrogen
content of both coals is high compared with high rank coals
(Tables 3 and 4). The less the oxygen content of a coal the
better the coal. As oxygen content increases, moisture
holding capacity increases and caking power decreases.
Based on nitrogen and oxygen contents, the coals are
more appropriate for generation of electricity and heating
for manufacturing processes.
The average sulphur content of Igaliwo coal is 0.98%
(Table 3) and that of Olokwu coal is 0.78% (Table 4) while
the phosphorus content of Igaliwo coal is 0.003 (Table 3)
and that of Olokwu coal is 0.001 (Table 4). The sulphur
content of the coals is low and within the rating of < 1.0%
recommended by Bustin et al. (1985) for coke-making, but
their pyritic nature makes them unsuitable for coke
making. Pyritic coal contributes to producing brittle steel,
causes slagging and fouling in the furnace thereby
reducing its efficiency and causes corrosion of the furnace.
Phosphorus is another element with adverse effect on iron
quality. Based on sulphur and phosphorus contents, the
coals are better used in electricity generation and heating
for manufacturing processes.
Comparing the calorific values of the studied coals with
other coals (X, Y and Z in Tables 3 and 4), the studied
coals contrast with San Pedro (USA) bituminous coal and
Barakar (India) anthracite but similar to Wyoming (USA)
sub-bituminous coal thereby also placing Igaliwo and
Olokwu coals in sub-bituminous rank.
The average calorific value of Igaliwo coal is 9275 Btu/Ib
(Table 3) while that of Olokwu coal is 9740Btu/Ib (Table 4).
These average calorific values are low compared with high
rank coals (Tables 3 and 4). The low heating values
recorded in the two coals are as a result of high moisture
content (IEA/OECD, 2002). The calorific value (CV) of a
coal is the amount of heat per unit mass of coal when
combusted. Mineral matter, moisture and ash contents of
a coal help in determining its heating value. The less these
contents the better the calorific value. Bustin et al. (1985)
recommended 14499Btu/Ib for good metallurgical coal.
Based on this recommendation, none of the coals is good
for metallurgical processes. However, they are suitable for
combustibility.

Free swelling index (FSI) is a traditional and quick
measurement of a coal’s overall coking characteristics.
The coal samples have zero (0) swelling index. According
to Blackmore (1985), coals are generally considered to
have coking properties if their FSI is over four (4).
However, coals that are classified as metallurgical coals
generally have FSI of seven (7) or more (the top of the
scale is nine). This implies that Igaliwo and Olokwu coals
are unsuitable for manufacturing of coke for metallurgical
processes. The lower the free swelling index of a steam
coal, the higher the efficiency of combustion (Blackmore,
1985). This also means that Igaliwo and Olokwu coals with
zero (0) free swelling index are good for heating and
generation of electricity.
CONCLUSION
Proximate, ultimate and calorific value analyses as well as
free swelling index test revealed that Igaliwo and Olokwu
coals both have high moisture, low ash, high volatile
matter, low carbon, low sulphur, low calorific values and
zero (0) free swelling index.
All these characteristics suggest that the coals are non-
coking. Though the sulphur content is low, but the pyritic
nature of the sulphur makes the coals non-coking and
therefore not suitable to be employed in the generation of
substantial heat for the working of blast furnace for iron
smelting. However, they can be used as a source of
energy in the production of electrical power using steam
generation. The coals are suitable in heating boilers and
ovens in industrial process heating. The cement, glass,
ceramic, paper and brick industries can use them for this
purpose. The coals are also good source of raw material
for manufacturing products such as drugs, dyes, oils,
waxes, plastics, synthetic rubbers, pesticides, insecticides,
antiseptics, paint products, solvents, synthetic fibres,
flavourings, perfumes, varnishes, adhesives, soaps,
detergents, fertilizer, shampoo and numerous other
organic chemicals. In addition, gasification and
liquefaction of the coals will produce gaseous and liquid
fuels that can be easily transported (e.g. by pipeline) and
conveniently stored in tanks.
ACKNOWLEDGEMENT
We sincerely appreciate Tertiary Education Trust Fund
(TETFUND) for giving us grant for this research work. The
Management of Kogi State Polytechnic, Lokoja is
gratefully acknowledged also for the approval given for the
release of the grant.
REFERENCES
Afonja AA (1974). Chemical, Petrographic and Coking
Studies of Enugu Coal, Nigeria. Abstracts, 10th Annual
Conference held at University of Ile-Ife, 40 – 42.
Akpabio IO (1998). Thermal Properties of Some Nigerian
Coals: Science Forum. Journal of Pure and Applied
Sciences, 1: 87 – 92.
Akpabio IO, Chagga MM and Jauro A (2008). Assessment
of some Nigerian Coals for Metallurgical Applications.
Journal of Minerals and Materials Characterization
Engineering, 7:301 – 306.
ASTM (1987). Gaseous Fuel; Coal and Coke. Petroleum
Products, Lubricants and Fossil Fuels. Easton, MD,
USA., Vol 05.05, pp. 278 – 282.
ASTM (1992). Annual Book of ASTM Standards, Section
5.50 Petroleum Products. Lubricants and Fossil Fuels.
Averitt P (1974). Coal Resources of the United States, U.S
Geological Survey. Nigerian Coals; A Resources for
Energy and Investments, Raw Materials Research and
Development Council, Abuja, 89 – 105.
Blackmore G (1985). Measuring the Cost Effects of Coal
Quality. pp. 2 – 3.
Bustin RM, Cameron AR, Greve DA and Kalkreuth WD
(1985). Coal Petrology. Its Principles, Methods and
Applications. Geological Association Canada. Short
Course Notes. 230p.
Chen P and Ma J (2002). Petrographic Characteristics of
Chinese Coals and their Applications in Coal Utilization
Processes. Fuel, 81:1389 – 1395.
Chukwu CJ, Obasi NA, Jauro A, Ezeribe AI, Nwachuckwu
CB and Putshak JD (2012). Physical and Plastic
Properties of Three Nigerian Coals. Asian Journal of
Materials Science, 4: 45 – 51.
De-Swardt AJ and Casey OP (1963). The Coal Resources
of Nigeria. Geological Survey of Nigeria Bulletin, No.
28. 100 p.
Diez MA, Alvarez R and Barriocanal C (2002). Coal for
Metallurgical Coke Production: Production of
Coke Quality and Future Requirements for Coke
Making. International Journal of Coal Geology, 50: 389
– 412.
Famuboni AD (1996). Maximizing Exploration of Nigeria’s
Coal Reserves. In: Nigerian Coals: A Resource for
Energy and Investments, Famuboni AD (Ed.). Raw
Materials Research and Development Council
(RMRDC), Abuja, Nigeria, pp. 39 – 62.
Gunn P, Gunn A and Mackenzie H (2012). Advanced Coal
Science. Coal Marketing International Ltd.
IEA/OECD (2002). Co-operation and Development Coal in
the Energy Supply of India. International Energy
Agency, Organization for Energy, Paris, pp. 92.
Jauro A, Agbo MO, Abayeh OJ, Obaje NG and Abubakar
MBJ (2008). Petrographic Study and Coking Properties
of Lamza, Chikila and Lafi-Obi Coals of the Benue
Trough. Mining Geology, 44:37 – 43.
Jensen ML and Bateman AM (1979). Economic Mineral
Deposits. 3rd Edition, Revised Printing. John Wiley &
Sons. Inc. New York; Chapman and Hall, London, 593
p.
Kogbe CA (1989). Geology of Nigeria, 2nd Edition.
Rockview Nigeria Ltd, Jos, 538 p.
Lowry HH (1945). Chemistry of Coal Utilization, vols. 1 and
2. New York; John Wiley, 1080 p.

Nigerian Coal Corporation, NCC (1974). Analysis and
Calorific Values of Nigerian Coal, Enugu, 3.
Nigerian Coal Corporation, NCC (1982). Information on
the Nigerian Coal, Enugu, 7.
Nigerian Coal Corporation, NCC (2011). The Nigerian
Coal Corporation: An Evaluation of Production
Performance (1960 – 1987). Quantitative Economic
Research Bureau.
Nwajide CS (1990). Sedimentation and Paleo-geography
of the Central Benue Trough, Nigeria. In: Ofoegbu CO
(Ed). The Benue Trough Structure and
Evolution. Vieweg, Braunschweig, 19 – 38.
Nwajide CS and Reijers TJA (1996). Sequence
architecture in outcrops: examples from the Anambra
Basin, Nigeria. NAPE Bull 11:23–33.
Obaje NG (1997). Petrographic Evaluation of the Coking
Potential of the Cretaceous Lafia-Obi Coal Deposits in
the Benue Trough of Nigeria. Journal of Mining and
Geology, 43:4 – 7.
Obaje NG, Ulu OK and Petters SW (1999).
Biostratigraphic and Geochemical Controls of
Hydrocarbon Prospects in the Benue Trough
and Anambra Basin, Nigeria. NAPE Bulletin, 14:18–54.
Okolo HC (1988). Investment Opportunities in the Nigerian
Coal Industry. In: Resources for Energy and
Investments, Okolo HC and Mkpadi MC (Eds). Raw
Materials Research and Development Centre, Abuja.
pp. 132 – 412.
Orajaka IP, Onwuemesi G, Egboka BCE and Nwanfor GI
(1990). Nigerian Coal. Mining Magazine, 446 –
451.
Reyment RA (1965). Aspects of the Geology of Nigeria.
University Press, Ibadan, 145 p.
Schobert M (1987). Coal: The Energy Source of the Past
and Future. American Chemical Society, Washington,
USA, pp. 188.
Sethi A (2014). Information on Raniganj Coalfield.
Important India. www.importantindia.com
Simpson A (1954). The Nigerian Coalfield: The Geology of
Parts of Owerri and Benue Provinces. Geological
Survey of Nigeria. Bulletin 24, pp 1 – 85.
Spath P and Amos W (1995). Techno-economic Analysis
of Hydrogen Production from Western Coal Augmented
with CO2 Sequestration and Coal Bed Methane
Recovery. National Renewable Energy Laboratory
(NREL), 5.
Thomas L (2002). Coal Geology. John Wiley and Sons Ltd;
384 p.
U.S. Energy Information Administration (2008). World Coal
Production, Most Recent Estimates 1980 – 2007,
htt://www.ela.doe.gov/emeu/international/coalproducti
on.html.
Umeji OP (2005). Palynological Study of the Okaba Coal
Mine Section in the Anambra Basin, Southern Nigeria.
Journal of Mining and Geology. 41(2) pp. 194.
Warwick PD and Hook RW (1995). Petrography,
Geochemistry, and Depositional Setting of the San
Pedro and Santo Tomes Coal Zones: Anomalous
Algae-rich Coals in the Middle Part of the
Claiborne Group (Eocene) of Webb County Texas.
International Journal of Coal Geology, 28(2):303 – 342.
Wessiepe K (1992). Present Coke Making Capacities
Worldwide. Coke Making International. Vol 4
(Germany), pp. 11.
Accepted 31 December 2019
Citation: Fatoye FB, Mepaiyeda S (2020). Quality
Assessment of Igaliwo and Olokwu Coals in the Northern
Anambra Basin of Nigeria. International Journal of
Geology and Mining 6(1): 309-317.
Copyright: © 2020: Fatoye and Mepaiyeda. This is an
open-access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are cited.

Quality Assessment of Igaliwo and Olokwu Coals in the Northern Anambra Basin of Nigeria

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Quality Assessment of Igaliwo and Olokwu Coals in the Northern Anambra Basin of Nigeria

Similar to Quality Assessment of Igaliwo and Olokwu Coals in the Northern Anambra Basin of Nigeria (20)

More from Premier Publishers

More from Premier Publishers (20)

Recently uploaded

Recently uploaded (20)

Quality Assessment of Igaliwo and Olokwu Coals in the Northern Anambra Basin of Nigeria