Journal of Minerals & Materials Characterization & Engineering, Vol. 10, No.9, pp.855-863, 2011 Printed in the USA. All rights reserved
Mineralogical Characterization of Kuru Cassiterite Ore by SEM-EDS,
XRD and ICP Techniques
Martin Ogwuegbu,
Gerald Onyedika,
Jiann-Yang Hwang,
Asuwaji Ayuk,
Bowen Li,
Ejike, E.N.O. and
Matt Andriese
Department of Chemistry, Federal University of Technology,P.M.B. 1526, Owerri , Nigeria.
Materials Science and Engineering, Michigan Technological University, 1400 Townsend
Dr., Houghton , Michigan, U.S.A.
*Correspondence author:
The morphology and elemental characteristics of Kuru Cassiterite ore deposit was performed
by the combination of different instruments. This is vital to obtain accurate mineralogical,
surface properties and compositions of the ore. Mineral particles were prepared on epoxy
resin, polished and analyzed by a SEM coupled with an EDS. X- ray diffraction showed that
the ore contained different minerals of cassiterite, coffinite, siderophyllite,ilmenite, qartz,
rutile, manganocolumbite, zircon, tilleyite and monazite. Further quantitative analysis using
inductive coupled plasma – optical emission spectrometry gave the elemental analysis as
follows; Sn
(28.0%), Si (5.5%), Fe
(3.51%), Al (2.48%), Y (1.06%), and Nb
(2.53%). The other trace elements found include Mn, K, Na, Mg, La, Ce, U and Ca. The
ICP-OES data was correlated with the XRD data obtained using the Guassian Pro 8.1 origin
software and it showed significant correlation.
Key words: Cassiterite, Mineral phase, ore, characterization
Tin occurs in Nigeria in the form of casiterite with varying amounts of assoiated mnerals [1].
The major sources of ore bearing cassiterite in Nigeria are the alluvial and eluvial deposits
from the biotite granites within the jurssic alkaline ring complex of the Jos Plateau. Moreso,
less than 5 % of the total production has been recovered from the pegmatits within the largely
Precambrian basement complex consisting of magnesites, gneisses, but with the rapidly
depleting reserves [2]. Figure 1 shows the map of Kuru , a typical mining area, 20 Km away
from Jos. Tin mining in Nigeria is over 100 years old. Prior to 1975, Nigeria was a major tin
exporter of casiterite concentrates which peaked at about 11,000 tonnes. Their has been a
856 Martin Ogwuegbu, et al Vol.10, No.9
dramatic declne to about 2000 tonnes. Among the factors accounting for the collapse of this
tin industry include the inaccssiblilty of placer deposits and the current prohibitive cost of
mining the ores beneath the basalt flows of Jos [3].
In the nineties, theavailable techniques used for ore analysis in Nigeria is the solution
methods of either fusion or acid digestion [4]. These were believed to report low data due to
incomplete solubilization of the ore minerals in aqeous medium [5]. This has resulted in large
number of tailing dumps. The residues contain tin ores and other heavy metals which today
could be extracted as ehe prize of tin has risen to $23,300 per tonne, ranking more than
Nickel [6].Presently, several attempts has been made to correct the analytical deficiency.
Either one or sometimes two are employed [4,7,8]. In each of these, either the elemental
analysis was carried out or just the phase analysis which provides incomplete information
about the ore.
This work is aimed at characterizing a typical Nigerian ore with different modern instruments
for the purpose of compositional elucidation and documentation. Consequently, the primary
objective is to provide comprehensive data about the physical and chemical characteristics of
a typical Nigeria cassiterite ore. These include mineral morphology, phase analysis, elemental
composition and degree of liberation, with a view to finding out and understanding the best
possible practice or extraction route by which tin could possibly be extracted.
2.1 Sample Preparation
Cassiterite ore weighing 3.0kg was collected from Kuru mining site through the National
Metallurgical Development Center, (NMDC), Jos, Nigeria. The ore was dried in the sun and
ground using the crusher. The sample was seived using seive sizes of ASTM of 850 µm, 425
µm and 212 µm. All the samples used for the various analysis was obtained by quatering
2.2 Scanning Electron Microscopy (SEM)
The representative sample was prepared using epoxy resins, polished and made conductive
by carbon coating in a Dentom vacuum, DV-502A. The morphology of the cassiterite ore was
analyzed in a JEOL JSM-6400 scanning electron microscope at accelerating voltage of
20KVA, realtime of 21-36 and livetime of 60 seconds. It was configured with an ultra thin
window energy dispersive X-ray spectrometry, three WDS spectrometers and a Geller dSpec
automation system controlling the spectrometers and motorized stage. Images were made
using the back scattering electron detectors. The chemical elements of the sample was
determined by the EDS. The images were shown with point analysis at the positions of the
ore particles.
Vol.10, No.9 Mineralogical Characterization of Kuru Cassiterite Ore 857
2.3 X – ray Powder Diffraction (XRD)
Analysis of X-ray diffraction was performed on the cassiterite ore. The sample was placed in
a lucite holder on the goinometer of the Scintag XDS 2000 powder diffractometer. It was also
configured with a graphite monochromator and IBM compatible workstation running Scintag
DMSNT software in window NT environment. The diffraction beam monochromator
operated at 20 KVA with step size of 0.02
for 120 minutes to create x- ray patterns with
enough intensities to produce lines to identify minerals at the 2Θ angles (5
– 90
). Scanning
rate was 0.75 degree per minute.
Fig. 1: Map of Kuru in Jos Nigeria where the Cassiterite sample was collected
Minerals were identified using the JCPDFWIN software of the Joint Committee on Powder
Diffraction Standard (JCPDS). Peak analysis was also carried out using the Guassian curve
fitting with origin Pro 8.1 software. The base lines are SS= 2.666408E+005, and the degree
of freedom was 4005.
2.4 Inductive Coupled Plasma – Optical Emission Spectrometry
0.2 g of the Kuru cassiterite ore was placed in a graphite crucible containing 1.20 g of
Lithium metaborate (LiBO
). Fusion digestion of the mixture was carried out in a muffle
furnace at 1000
C for 20 minutes. The red hot fused mixture was quickly poured into 100 ml
of 10% Hydrochloric acid. The solution was stirred with a magnetic stirrer until all the solid
particles dissolved and later filtered. The filtered solution was made up to 250 ml with de-
ionized water. The solution was analyzed with the Leeman Inductively coupled plasma –
optical emission spectrometry.
858 Martin Ogwuegbu, et al Vol.10, No.9
2.5 Liberation Studies
100 g of the crushed ore was introduced unto a set of sieves arranged in descending order and
shaken for 30 minutes. The weight retained in each sieve was taken and expressed as percent
of the total sample weight. Liberation studies were carried out with an optical microscope of
the wild Herbrugo 195006 and Megapixel firewire model coupled with field diameter of 35.0
mm. The images were captured with an implanted camera PL – A642. The imaging
magnification chosen was 10 x 6. In each count, 2 g of the representative sieve size was
taken. The sieve sizes selected for the studies are 20 (850µm), 40 (425µm) and 70 (212µm)
3.1 Physical and Chemical Characterization
3.1.1 Scanning electron microscopy
The chemical and morphological characteristics of the crushed particles in the ore including
chemical composition of each liberated particle were determined by means of SEM. The
chemical elements of the ore bearing cassiterite were also determined by the EDS. The sizes
of the particles varied from 70 mesh to 20 mesh. The SEM image shows the interlocking of
some minerals within some crystal aggregates. The EDS chemical analysis showed that the
elements that abound in the ore bearing cassiterite were Sn, Fe, Mn, Nb, Ti, Zr, Al, Y, Si, K,
La, Ce, P, Mg, Ca, U and O. Figure 2 show the SEM images of the various mineral particles
and Figure 3 provide the details for the EDS analysis data.
Fig. 2: Scanning Electron Microscopy image of represenative crushed cassiterite sample
Quartz in Cassiterite
Yttrium oxide
Vol.10, No.9 Mineralogical Characterization of Kuru Cassiterite Ore 859
Zircon Zircon
Yttrium Oxide
860 Martin Ogwuegbu, et al Vol.10, No.9
Fig. 3: EDS peaks for the various minerals in the Kuru Cassiterite Ore deposit showing
different elemental compositions.
3.1.2 X – ray diffraction
The mineralogical component of the crushed ore bearing cassiterite was carried out by X –
ray diffraction technique. The main minerals found in the sample were cassiterite with
JCPDS card numbers 41-14445, rutile with JCPDS card number 21-1276, manganocolumbite
with JCPDS card number 45-1360, coffinite (46-1304), tilleyite (24-0184), zircon (06-0266),
quartz in the form of rodiocolite (50-1635), monazite, siderophyllite (JCPDS 25-1355). Each
JCPDS card number has the phase information from the XRD patterns. The peak analysis
using the Guassian curve fitting gave the percent area integration of the various phases which
correlated to the quantity of the various minerals in the ore. The integrated peak area for
cassiterite that showed 4.52% was rejected due to high standard deviation of 74. Figure 4
shows the XRD phase pattern and Table 1 shows the percent quantity of the mineral
components from XRD peak analysis.
Zirconium Silicate
Ilmenite(Ti, Fe, Mn, O)
Vol.10, No.9 Mineralogical Characterization of Kuru Cassiterite Ore 861
Fig. 4: XRD pattern of Kuru Cassiterite ore showing the signature lines for SnO
Table 1: XRD Peak analysis by the Guassian curve fitting with origin Pro 8.1 software
Mineral Cassit
Zircon Mangano-
Quartz Monazite
34.18 4.08 3.55 2,06 3.28 1.05 1.94 9.98 1.01
862 Martin Ogwuegbu, et al Vol.10, No.9
3.1.3 Inductive coupled plasma – optical emission spectrometry
The results of the elemental analysis by ICP-OES showed that Sn(28.0%), Si(5.5%),
Fe(5.16%), Nb(2.53%), Ti(3.51%), Al(2.48%), Y(1.6%), La(1.13%), P(0.88%), Zr(0.99%)
and Mn(0.31%). Other trace elements found in their trace quantities are U, Ce, K, Na, Mg
and Ca. When the elements are converted to their oxides by the stoichiometric technique
using combining atomic weights with oxygen, the values are obtained are shown in Table 2.
Table 2: ICP-OES analysis of Kuru cassiterite ore
Elements % Composition
Sn 28
Si 5.5
Fe 5.16
Mn 0.31
Nb 2.53
Ti 3.51
Al 2.48
Y 1.06
3.1.4 Liberation studies
Table 3 shows the percent degree of liberation of the major components mineral in cassiterite
at various sieve sizes. Significant liberation of 52% was observed at the sieve size of 20
mesh. This indicates that reasonable quantities of SnO
can be obtained if the ore is crushed
in that size range. Below this sieve size is the presence of high amount of quartz and other
locked minerals.
Table 3: Degree of liberation at various sizes
Mesh size 20 40 70
% SnO
52 21.70 32.90
The primary objective of this work was the characterization of an ore bearing cassiterite
mineral from Kuru, Jos Nigeria. The mineralogical studies carried out with SEM point
imaging showed the presence of different aggregates of minerals. The chemical elemental
composition determined by EDS were Sn, Fe, Mn, Ce, P, K, Mg, Th, Y, La Nb, Si, O, and Zr.
XRD phase patterns confirmed the availability of minerals such as cassiterite,
manganocolumbite, rutile, monazite, siderophylite, coffinite, zircon, quartz, tilleyite . The
Vol.10, No.9 Mineralogical Characterization of Kuru Cassiterite Ore 863
XRD peak analysis by the Guassian Pro 8.1 software showed over 34% cassiterite in the form
of SnO
(JCPDS card 41-1445). ICP-OES analysis gave the quantity of SnO
in the ore to be
35.55%. The composition of cassiterite as observed in the XRD indicated that XRD analysis
coupled with the Guassian curve fitting could be used for quantitative estimation of
cassiterite in the ore. Also, liberation study has shown that SnO
are physically concentrated
at particle size of 20 mesh. From the above mentioned, the use of SEM-EDS , XRD and ICP-
OES provided excellent information on mineral composition of Kuru ore deposit.
Special appreciation goes to Institute of Material Processing, Michigan Technological
University, USA for providing facilities and Nigeria Education Tax Fund in collaboration
with Federal University of Technology, Owerri, Nigeria for their sponsorship.
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