Journal of Minerals & Materials Characterization & Engineering, Vol. 8, No.5, pp 359-366, 2009
jmmce.org Printed in the USA. All rights reserved
Exploring the Potentials of Tailings of Bukuru Cassiterite Deposit for the
Production of Iron Ore Pellets
O. K. Abubakre*
1
, Y. O. Sule
2
and R. A. Muriana
1
Department of Mechanical Engineering
Federal University of Technology, Minna, Nigeria
2
Raw Materials Research & Development Council, Abuja, Nigeria
*Corresponding Author, contact: [e-mail]
ABSTRACT
Cassiterite ore was sourced from Dogo-Na-Hawa, in Bukuru, Jos South Local Government of
Plateau State, Nigeria. The ore was analyzed as mined and its various constituents noted.
Previous study has shown considerable iron ore composition of the deposit. The present study
entails the separation and analysis of magnetic mineral (mostly iron ore) from the ore. The
beneficiated iron ore was pelletized using the facilities of the Nigerian Metallurgical
Development Centre (NMDC), Jos. The pellets so produced were subjected to various tests such
as drop resistance, green compressive strength, dry compressive strength at 900
o
C, tumbler
resistance, micro porosity and indurations compressive strength at 1100
o
C. The results
indicated Bukuru cassiterite contains sufficiently high grade of iron ore that could be
beneficiated for iron production. The pellets produced are of good quality and could be utilized
for iron and steel making.
1. INTRODUCTION
Cassiterite, SnO
2
, is the most important ore of tin. It is often found in hydrothermal veins or
pegmatite, but also forms as a result of secondary processes in the oxidation zone of weathered
tin deposits [1]. During erosion, cassiterite can wear down to nodules and large grains and
concentrated in placer deposits. The nodules have a greasy luster and seem heavy in the hand.
Some cassiterite is very black and hence tests are sometimes essentials. By reducing cassiterite
to powder (white) and heating it on a block of charcoal, a globule of tin is produced. The present

360 O. K. Abubakre, Y. O. Sule and R. A. Muriana Vol.8, No.5
study entails the separation and analysis of magnetic mineral (mostly iron ore) from the ore. The
beneficiated iron ore was pelletized using the facilities of the Nigerian Metallurgical
Development Centre (NMDC), Jos. The pellets so produced were subjected to various tests such
as drop resistance, green compressive strength, dry compressive strength at 900
o
C, tumbler
resistance, micro porosity and indurations compressive strength at 1100
o
C. The results
indicated Bukuru cassiterite contains sufficiently high grade of iron ore that could be
beneficiated for iron production. The pellets produced are of good quality and could be utilized
for iron and steel making.
2. LITERATURE REVIEW
2.1. Sources of Tin Ore
The main suppliers of tin to the ancient world were the Phoenicians who carried on a trade based
on their mines and smelters in the Iberian Peninsula and on trade with Cornwall. Greek literature
mentions the cassiteride, the “tin Islands” but just what these were is not clear. Cassiterites is
widely distributed in small amounts but were produced on a commercial scale in only a few
localities. Most of the world’s supply of tin ore now comes from the Malay states, Bolivia,
Indonesia, Belgian, Congo and Nigeria. Cornwall, England, has produced large amount of tin
ore in the past. Tin was a rare metal in the East and had to be brought from the misty Cassiterides
by sailors from Atlantic shores [2].
2.2. Tin Mining in Nigeria
Nigeria used to be one of the major sources of Cassiterite. Tin mining was discovered around
1700 – 1750 in Kuza near the river channel. Tin mining began to develop in local villages and
trade occurred with those who came from Tripoli and crossed the Sahara. The tin would be
melted and made into rolls. By 1760 – 1770, there were thirteen indigenous blacksmith smelters
in Naraguta - a city located just north of Jos. The Beron ethnic group was mining and producing
tin along the Delimi River for the ethnic Hausa Traders. Tin became popular during the industrial
revolution in Europe. Tin was traced from Tripoli (Libya) to Bauchi (Nigeria) which served as
commercial centre for tin from Jos. The Hausa traders established the buying center in Bauchi to
prevent foreigners from knowing the original source of Jos tin.
In 1868, Clepparton from Britain traveled three months across the Trans Sahara to find smelters
in Naraguta. As at this time, tin sources in Europe were beginning to fade [3]. By 1820, Colonel
Levis from Britain was ordered to sample produce tin from Naraguta deposit. At that time, there
was little knowledge among Nigerians on what tin was being used for. Awareness developed
later that Spain was using the tin for gun barrels. Apart from the Naraguta deposit, many
locations with viable deposit have been identified at various locations in Nigeria (Table 1).

Vol.8, No.5 Exploring the Potentials of Tailings of Bukuru Cassiterite Deposit 361
2.3. Tin Processing in Nigeria
At the dawn of the Second World War, Nigeria was already a major source of high-grade tin ore
for the Tin Smelters of the Western Europe where tin was extracted for ammunition production
to support the war efforts, amongst other uses. By 1960, Nigeria had established itself as an
important producer of tin ore, which then became a major foreign exchange earner for the
country. In 1962, Makeri Smelting Company Limited was established on the Jos Plateau by
Consolidated Tin Smelters (a British company) displacing a Spanish Smelter nearby that was
competing for the concentrate [4].
Table 1 Cassiterite deposits in Nigeria.
S/N STATES LOCATION
1 Cross River Akaibamu, Ogoja, Obeju
2 Ekiti Ijero
3 Nassarwa Wamba
4 Kaduna Kaduna, Jama’a
5 Plateau Jos North/South
Barkin – Ladi, Mangu
Bassa, Panshin, Bakkos
6 Kogi Ojuwo – Olijo, Egbe,
7 Adamawa Toungu, Vere Hill
8 Gombe Kaltun
The science of Tin Smelting did not begin in Nigeria with the establishment of a Tin Smelter.
Prior to the arrival of the European Explorer, there already existed sophisticated cultures that
were vast in the art of local smelting. For many years the ore extracted by miners on the Plateau
was brought by traders and taken to Lireuin (Ririwai), Delma which were important centers for
the smelting process. Lireuin in Kano was the older center but by the end of the 19
th
century
much of the activity had been transferred to the other town when an ambitious younger brother
quarreled with the head of the family and set up new furnaces at Lireuin (Ririwai) Delma with
some followers. The operation of the furnaces was simple and effective. Each furnace belonged
to one of the leading men of the town. Maintenance and repairs were carried out under cover of
darkness to keep the art of making furnaces secret. The owners of the furnaces smelted for their
town men who had enough ore to make a convenient charge of about 63.5 kg (140Ibs) [5].
3. EXPERIMENTAL PROCEDURE
3.1. Beneficiation of the Ore

362 O. K. Abubakre, Y. O. Sule and R. A. Muriana Vol.8, No.5
Tin ore weighing 15.19 kg was collected from its Padok (field leased out by Government where
mineral ore exists). The ore was dried in the sun and run on gravitational shaking machine to
reduce the sand. Bucket 1 and 2 on gravitational shaking machine contains tin ore, which is then
transferred to rapid double disc machine. The dried and floated tin ore (SnO
2
) is now charged
into the charging chamber of rapid disc machine. On this machine, which works by
electromagnetic field effect, the material runs down through the conveyor belt and through the
disc. At the first disc, magnetic and non magnetic minerals are separated. The magnetic
mineral, iron ore, which is the most magnetic is first separated on the first disc, columbite and
other less magnetic mineral are attracted by the second and third discs.
The non – magnetic mineral i.e. cassiterite or tin ore (SnO
2
), monozite, zircon sand in traces,
zinc and other non – magnetic ore in the mineral goes to the front (i.e. they are not being picked
by any of the disc). These are known as over – belt materials. The over – belt is subjected to
gravity floatation on the air float to obtain pure tin oxide. The percentage composition (by mass)
of Cassiterite Ore (as mined) Samples from Padok in Dogo Na Hawa in Bukuru is presented in
Table 2.
Table 2: Composition of Ore Sample from Padok
Constituent Composition (kg) Percentage Composition (%)
Tin 1.98 13.06
Iron Ore 4.83 31.45
Columbite 0.39 2.5
Monozite and Other non-magnetic
materials
7.94 52.27
Loss during Processing 0.062 0.41
The analysis was carried out by Geotec Nigerian Limited, Jos.
The magnetic mineral (with iron ore as the major constituent) recovered from magnetic shaking
machine was also analysed. The result of the analysis is presented in Table 3.
Table 3: ED-XRF Chemical Composition of Cassiterite Deposit from Dogo Na-Hawa in Bukuru
Compound CaO TiO
2
V
2
O
5
Cr
2
O
3
MnO Fe
2
O
3
NiO CuO As
2
O
3
Y
2
O
3
Composition
%
2.8
%
16.7
%
0.2
%
0.93
%
1.1
%
23.7
%
0.26
%
0.50
%
0.01
%
0.52
%
Compound ZrO
2
Nb
2
O
5
Rh
2
O
3
SnO
2
CeO
2
Yb
2
O
3
HfO
2
PtO
2
PbO ThO
2
Composition
%
29.1
%
8.9
%
4.0
%
7.2
%
0.5
%
0.46
%
0.81
%
0.31
%
0.33
%
1.6
%

Vol.8, No.5 Exploring the Potentials of Tailings of Bukuru Cassiterite Deposit 363
3.2. Characteristics of Pellets produced from the Ore
About 3.0kg of pulverized magnetic component of the ore was mixed with 0.12kg of bentonite,
and 450ml of water. Pellets of 8 to 10cm were produced using palletizing disc machine. The
resulting pellets were subjected to various tests to establish its suitability for use in iron
production. Such test include Drop Number test, Drop Resistance, Moisture Content, Green
Compressive Strength Test, Dry Compressive Strength Test at 900
o
C, Tumbler resistance Test,
Micro – Porosity Test, Indurating Compressive Strength Test at 1100
o
C. Standard test procedure
was used to determine these parameters as highlighted by Guanzhou [5] and others [6-8].
4. RESULTS AND DISCUSSIONS
4.1. Chemical Composition of the Beneficiated Ore
The chemical composition of the magnetic component of the analyzed cassiterite ore after
beneficiation is shown in Table 4:
Table 4: Chemical Composition of Magnetic material (mostly Iron ore) from recovered from the
cassiterite deposit
Compound CaO V
2
O
5
MnO Fe
2
O
3
ZrO
2
Nb
2
O
5
Rh
2
O
3
TiO
2
Others
Composition
%
0.89
%
0.83
%
1.10
%
42.40
%
0.63
%
0.86
%
2.00
%
34.50
%
16.69
%
There is a noticeable increase in the iron ore content of the primary ore by 44 percent.
4.2. Drop Number and Drop Resistance Test
The result obtained form Drop Number test and Drop Resistance test are presented in Table 5.
Table 5 Result of Drop Number and Drop Resistance Tests
S/N 1 2 3 4 5 6 7 8
Height (cm) 60 46 46 46 60 46 60 60
Drop nos 3 4 4 4 3 4 3 2
Drop Height (cm) 72 60 48 36 48 72 36 60
Drop Resistance nos 2 2 2 4 2 2 3 3
The Drop number test can be carried out at the height of 46 cm to 60 cm. When carried out at
the height of 46 cm, the average drop number is 4. The result of the test carried out from the
height of 60 cm for eight green pellets has an average drop number of 3. Similarly, Drop

364 O. K. Abubakre, Y. O. Sule and R. A. Muriana Vol.8, No.5
Resistance number ranging between 2 and 3 was obtained for the various heights of 36 cm to 72
cm. These values are an indication of the admissible height difference at various transfer points
during green ball transformation.
4.3. Moisture Content of the Iron ore
The moisture content of the pulverized iron ore was determined. The weight of pulverized iron
ore stabilized after sun drying and firing for 30 minutes at 200
o
C. An average weight loss of 0.6
grams was observed which represents 0.6% moisture content.
4.4. Compressive Strength
It is apparent from practical operation that pellet consumers demand a minimum strength of an
average sample of about 2,000 N/pellet. 8 pellets were used for the test and the strength for the
untreated pellets is presented in Table 8. The average compressive strength at 900
o
C is
3.37kN/pellet. Similar test was carried out for pellets subjected to Heat treatment and the result is
presented in the second column of Table 8. The average strength of the treated pellets is 3.83
kN/Pellet
Table 6: Results Dry Compressive Strength of Treated and Non-Treated Ore
PELLETS
Compressive Strength
(kN/PELLET)
Compressive Strength after Heat
Treatment (kN/PELLET)
1
2
3
4
5
6
7
8
AVERAGE
3.24
3.62
4.16
3.22
3.54
3.50
2.60
3.09
3.37
3.78
3.88
3.49
3.91
3.94
3.94
3.70
3.98
3.83
This shows some relative hardening of the pellets subjected to heat treatment process.
4.5. Tumbler Test
The tumbler test was carried out and the results obtained are as presented in Table 7

Vol.8, No.5 Exploring the Potentials of Tailings of Bukuru Cassiterite Deposit 365
Table 7: Result of Tumbler Test
Weight
of
Sample
(B)
Abrassive
weight
(A)
Tumbler
weight
(C)
Abbrassive
index
{(A/B)×100}
Tumbler
index
{(C/B)×100}
Losses in
Abbrassion
(D)
% losses
{(D/B)×100}
127.35g 71.9g 53.6g 56.46% 42.09% 1.85g 1.45%
4.6. Green Compressive Strength Test at 100
o
C
The average compressive strength obtained after subjecting six different pellets to compressive
strength test is 0.23kN/Pellet. In a very few cases it could be possible to use green balls directly
in metallurgical processes despite their low mechanical strength. Pellets must have a
substantially higher strength primarily to withstand their transportation and the stresses occurring
in metallurgical operations.
This test method is carried out to provide a relative measure of the resistance of iron ore pellets
to degradation by impact and abrasion.
4.7. Micro – Porosity Test
The micro porosity test was conducted and the result is as presented in the Table 8 below:
Table 8: Micro porosity of Pellets
Weight (g) Volume
(cm
3
)
Density (g/cm
3
) Porosity
(P = 1-ρ
a
/ρ
t
) X
100 (%)
Initial Final Apparent (
ρ
a
)
True (ρ
t
)
First Pellet 37.70 39.60 8.18 4.61 4.85 5.86
Second Pellet 36.80 39.10 8.18 4.50 4.78 4.95
The porosity is measured on the dry balls. Total porosity of a pellet is expressed as the ratio of
pore volume to total volume of the pellet and is calculated using the difference between the true
density and apparent density. Porosity of a pellet is an important property to ascertain pellet
quality. Porosity affects the compressive strength, thermal conductivity. It also plays important
role in controlling its swelling during its reduction. Kasai and Murayama [9] reported an
increase in thermal conductivity with decrease in porosity for coke pellets.
4.8. Indurating Compressive Strength Test at 1100
o
C

366 O. K. Abubakre, Y. O. Sule and R. A. Muriana Vol.8, No.5
The indurations impart such characteristics to the pellets as are imperative both for their
transportation and metallurgical treatment. It is the last processing step to impart substantially
higher strength. The produced pellet with an average compressive strength of 5.2kN/Pellet more
than satisfies the minimum strength requirement of 2 kN/Pellet. The strength of pellet can further
be increased by increasing the percentage of binder.
5. CONCLUSION
Cassiterite was sourced from Dogo Na Hawa in Bukuru, Jos South Local Government Area of
Plateau State. The ore was analyzed and the various constituents of the ore ascertained. The iron
ore content of the ore as mined was 31.45%. After magnetic separation of the iron ore from the
cassiterite ore, it was then analyzed and was found to be 42.40%.
The iron ore was pelletized using the equipment available at the National Metallurgical
development Centre (NMDC), Jos and the results were compared with properties of pellets
required for use for DRI process of iron and steel making and Blast furnace process. The
pelletised iron ore were found to be suitable for any of the two processes.
Though iron ore from cassiterite is good enough for iron and steel production, abundant
availability of iron ore in the earth crust and in Nigeria in particular does not make cassiterite a
viable source of iron ore for iron and steel production today and in the near future.
REFERENCES
[1] Adams, H., 2001, Columbia Encyclopedia, Sixth Edition, available at www.bartleby.com
[2] Calvert, J.B., 2000, Tin 4, available at www.du.edu/~jcalvert/phys/tin.htm
[3] Natasha, C., 2002, Tin mining of the Jos plateau, available at
www.uni.edu/gai/nigeria/lessons/tin-mining.htm
[4] Gibson, O., 2002, “Tin Smelting in Nigeria – the Challenge of our time.” Proceedings of the
19
th
Annual Conference/AGM of the Nigerian Metallurgical Society, pp. 47 – 60.
[5] Guanzhou, Q., Tao, J., Zhucheng H., Deqing, Z., and Xiaohui, F., 2002, “Characterization of
Preparing Cold Bonded pellets for Direct Reduction using an Organic Binder.” ISIJ
International Journal, Vol. 4, pp. 20 – 25.
[6] Kurt, M., 1980, Pelletizing of Iron Ore, Springer – Verlag Berlin Heidelberg, New York.
[7] Rumpf, H., 1962, “The Strength of Granules and Agglomerates.” Agglomeration (ed. W.A.
Knepper), New York.
[8] Tohidi, N., and Rames, V., 1997, “Preparation of Iron and Steel Burden.” Seminar paper
presented at Tehran University.
[9] Kasai A., Murayama T., and Ono Y., 1993, “Measurement of Effective Thermal Conductivity
of Coke.” ISIJ International, Vol. 33, pp. 697 – 702.