ABSTRACT
Due to rapid industrialization, the demand for heavy metals is ever
increasing, but the reserves of high-grade ores are diminishing.
Therefore there is a need to explore alternative sources of heavy
metals. Ore mine gangues which are industrial wastes can act as
potential sources of industrial materials. Typical iron ore minerals may
contain antimony, arsenic, beryllium, cadmium, chromium, copper, lead,
nickel, as well as silver and zinc [6]. The economic viability of these
metals would depend on their various amounts in the iron ore. The
analysis of the Itakpe iron ore in Nigeria would determine whether the
associated metals are commercially feasible for secondary recovery. Due
to these afore mentioned problems, the research was carried out using
EDX - XRF and XRD, analyzing five different samples which include coarse
iron ore, middle fine iron ore, fine iron ore, gangue iron ore and
concentrate iron ore. The sample analysis shows that Itakpe iron ore is
hematite-rich with atomic % of Fe to be 40.00 and weight % to be 69.94.
The EDX results showed the presence of iron peak of varying intensity
which was observed to have the concentrate with the highest peak of
37500 and the gangue with the least peak of 11200. Also, the presence of
silicon peak of varying intensity was observed with the gangue having
the highest intensity of 7000 while the concentrated iron ore and coarse
iron ore has a negligible intensity. The varying intensity of cobalt in
the 5 sample cannot be neglected as the concentrate iron ore has the
highest intensity of 5000 and the gangue has the lowest intensity of
1500.
The XRF was used for the elemental analyses which showed high
percentage of iron element ranging from 34.60% for GIO, 51.59% for MfIO,
53.80% for FIO, 56.34% for CIO, and 64.51% for CoIO. Also, the samples
contain some percentage of Silica ranging from 0.36% for CIO, 1.63% for
CoIO, 11.60% for FIO, 12.53% for MfIO and 22.97% for GIO. This really
shows that the iron and the silicon can still be recovered from the
gangue.
Also, the XRD was used for the structural analysis of the unprocessed
iron ore, middle fine iron ore, concentrate iron ore and the gangue
iron ore samples in which the spectral of the unprocessed iron ore was
observed to have many peaks when compared with the spectrum of other
samples, this is attributed to high concentration of impurities.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Overview
Iron constitutes about 5% of the Earth’s crust, making it the fourth
most abundant element. Iron oxides and hydroxides form the principal
iron ore minerals, due to their high iron content and occurrence as
large tonnage surface deposits [1]. The presence of the amount of iron
varies from an average of 2-3% in sedimentary rocks to 8.5% in the
basalt and gabbro [5]. Iron is, however, present in low concentration in
most parts of the earth, thus a deposit must have a high percentage of
the metal to be considered ore grade for economic purposes. Typically, a
deposit must contain at least 25% iron to be considered economically
recoverable. Exploitation of large, low grade iron ore deposits can be
achieved through concentration of the iron.
The iron itself is usually found in the minerals of magnetite
(Fe3O4), hematite (Fe2O3), goethite (FeO(OH)) or limonite
(FeO(OH)n(H2O)), siderite (FeCO3), chamosite (Mg,Fe,Al)6(Si,Al)414(OH)8,
ilmenite (FeTiO3) and pyrite (FeS). Despite the existence of iron in
many minerals, five of them are the primary sources of iron: magnetite
(Fe3O4), hematite (Fe2O3), goethite/limonite (FeO(OH)), siderite
(FeCO3), and pyrite (FeS) [5].
Iron ores are rocks and minerals from which metallic iron can be
extracted. An iron ore deposit is a mineral body of sufficient size,
iron content, and chemical composition with physical and economic
characteristic that will allow it to be a source of iron either
immediately or potentially [2]. Iron ore is the raw material used to
make pig iron, which is one of the main raw materials to make steel.
Nearly 98% of the mined iron ore is used to make steel [3]. There are
four main types of iron ore deposits worked currently, depending on the
mineralogy and geology of the ore deposits. These are magnetite,
titanomagnetite, massive hematite, and pisolitic ironstone deposits [2].
The Itakpe iron ore deposit in Nigeria which has a total estimated
reserve of about 182.5 million metric tonnes consists mainly of
quartzite with magnetite and hematite [6].
The deposit has been developed to supply iron ore concentrates to
Ajaokuta steel plant and the Delta steel plant, Aladja, in Nigeria.
The Itakpe Iron deposit is important for the successful development
of iron and steel industry in Nigeria though on the national scale there
are other silico-ferruginous formations which are interesting from
commercial and economic viewpoint especially the deposits of Ajabonoko
Hill and Choko-Choko which are said to be similar to those at Itakpe. To
be taken seriously also is the revenue loss due to the uncovered
minerals in Itakpe iron ore gangue.
The extraction of specific value minerals from their naturally
occurring ores is variously termed “ore dressing,” “mineral dressing,”
and “mineral beneficiation.” For most metalliferous ores produced by
mining operations, this extraction process is an important intermediate
step in the transformation of natural ore to pure metal. Although a few
mined ores contain sufficient metal concentrations to require no
beneficiation (e.g. some iron ores), most contain relatively small
amount of the valuable metal, from perhaps a few percent in the case of
base metals which are commonly intergrown with economically important
and unimportant (gangue) minerals on a microscopic scale in the iron ore
gangue.