ABSTRACT
The beneficiation of the Agbado Okudu iron ore deposit located in
Kogi State, Nigeria was investigated. The investigation involved
determining the chemical composition and mineralogical characteristics of
the run-of-mine. Followed by determination of the work index of the ore
and then separation tests using shaking table, magnetic technique and a
combination of the two techniques. The results of the tests carried out
revealed that the Agbadu okudu iron ore contained on the average a total
iron content (38.82% FeT), 49.10% (Si02) and other element. Thin sections
of the ore sample examined under polarized light revealed that the iron
bearing minerals are predominantly magnetite and hematite with a
combined average percentage distribution of 69% and the mineral in
abundant after the iron bearing minerals is quartz. The grindability test
reveals that the Agbado Okudu iron ore has and average work index of
about 4.32 kwh/tonne. The results of gravity separation shows that a
concentrate with a maximum grade of 55.81% (FeT), and a recovery of
66.40% at particle size fraction -56 + 45m could be produced. While
magnetic separation alone produced a concentrate with an optimum grade of
57.43% (FeT), and a recovery of 82.12% at particle size fraction of –
80+63m. However, combination of gravity separation technique (shaking
table) followed by magnetic separation technique could only produce a
concentrate with an optimum grade of 57.17% (FeT), and a recovery of
80.85% at a particle size fraction of –63+53m. Hence, based on the results
obtained from the concentration tests, the Agbado Okudu iron ore deposit
can be best beneficiated using magnetic technique to produce a concentrate
that can serve as feed for pig iron production by conventional blast furnace
route.
TABLE OF CONTENTS
PAGE
DECLARATION- – – – – – – – – – – – iii
CERTIFICATION- – – – – – – – – – – – iv
DEDICATION- – – – – – – – – – – – v
ACKNOWLEDGEMENT- – – – – – – – – – vi
ABSTRACT- – – – – – – – – – – – – vii
TABLE OF CONTENTS – – – – – – – – – viii
LIST OF TABLES- – – – – – – – – – – – xi
LIST OF FIGURES– – – – – – – – – – – xiii
CHAPTER ONE
Introduction- – – – – – – – – – – – – 1
CHAPTER TWO
2.0 Literature Review- – – – – – – – – – – 4
2.1 Nigeria Iron Ore Deposits- – – – – – – – – 4
2.1.1 Agbado-Okudu Iron Ore- – – – – – – – – 5
2.1.2 Mineralogy of Agbado-okudu Iron Ore- – – – – 6
2.2 Study of some Nigerian Iron Ores Characteristics- – – – 7
2.2.1 Iron Ore Beneficiation Process- – – – – – – – 9
2.2.2 Gravity concentration process- – – – – – – 9
2.2.3 Magnetic separation- – – – – – – – – – 11
ix
2.2.4 Froth flotation- – – – – – – – – – – 13
2.3 Methods for the Beneficiation of Iron Ore- – – – – 13
2.3.1 Beneficiation route for the Itakpe Iron Ores- – – – 14
2.4 Procedures for development of conceptual flow sheet
for a newly discovered ore- – – – – – – – – 17
2.5 Particles Size Analysis – – – – – – – – 19
2.6 Size/Assay Analysis – – – – – – – – – – 20
2.7 Determination of liberation size of the valuable Minerals
in the Ore – – – – – – – – 20
2.8 Work index Determination – – – – – – – – 23
2.8.1 Standard bond method- – – – – – – – – 23
CHAPTER THREE
3.0 Materials and methods- – – – – – – – – – 26
3.1 Samples collection and equipment used- – – – – – 26
3.2 Methods- – – – – – – – – – – – 26
3.2.1 Preparation of the bulk sample for chemical analysis- – -26
3.2.2 Chemical analysis- – – – – – – – – – – 26
3.2.3 Microscopy- – – – – – – – – – – – 27
3.2.4 Size/Assay analysis- – – – – – – – – – 28
3.2.5 Work index Determination- – – – – – – – – 29
3.2.6 Separation test using shaking table technique- – – – 29
3.2.7 Separation test using Magnetic Separator- – – – – 30
x
3.2.8 Shaking table separation followed by Magnetic
Separation techniques – – – – – – – 31
CHAPTER FOUR
4.0 Results and Discussions- – – – – – – – 32
4.1 Results – – – – – – – – 32
4.2 Discussions – – – – – – – – 32
4.2.1 Chemical analysis- – – – – – – – – – – 32
4.2.2 Mineralogical analysis- – – – – – – – 33
4.2.3 Size/Assay Analysis of the Head Sample – – – 34
4.2.4 Work index Determination- – – – – – – – 35
4.2.5 Concentration test using Shaking Table – – – – – 36
4.2.6 Magnetic separation technique- – – – – – – 40
4.2.7 Results of concentration test using shaking table
followed by magnetic Separation Techniques – – – – 43
CHAPTER FIVE
5.0 Conclusions and Recommendations – – – – 46
5.1 Conclusions- – – – – – – – – – – – 46
5.2 Recommendations- – – – – – – – – – – 46
References- – – – – – – – – – – – – 58
CHAPTER ONE
NTRODUCTION
Iron is one of the most common elements on earth. Nearly every
structure put on by man contains at least a little iron. It is also one of the
oldest metals and was first fashioned into useful and ornamental objects
about 3,500 years ago (Lambert and Mark, 1988).
One of the most important determining factors for establishing Iron
and steel plants is the availability of iron ore deposit with good geological,
mineralogical and metallurgical properties. There is an estimated 2,707
million tonnes of iron ore deposit in the country out of which 200 million
tones are in the proven reserve (Umunnakwe, 1988). Iron ore is simply the
largest single raw material input in iron and steel making process and the
country is endowed with abundant reserves of it but with varying
characteristics. The deposits abound in different parts of the country as
shown in Table 2.1. Most of the iron ores discovered in the country are
however, low grade (their iron content in the crude ranges between 28-45%
FeT). This meant that for them to be used in iron and steel production they
have to undergo substantial beneficiation and upgrading. (Also and Yakubu,
1995). The Itakpe iron ore had been the most intensively studied and
exploited deposit with a proven reserve of 200million tones with an average
iron content of 36% FeT. This is presently being up-graded to obtain a
2
concentrate of 64% FeT for use at Ajaokuta and Aladja steel plants. Apart
from the Itakpe iron ore deposit there are other deposit which reserves are
estimated at over 2.3 billon tonnes as shown in (Table 2.1) within 150km
radius of the Ajaokuta steel plant. To ensure security of supply of the iron
ore for the nation Steel industries, further research and development need to
be carried out on these new founded deposits to enable their full
exploitation. With these reserves, conservative estimates indicate that the
nation could be self-sufficient in iron ore for a period ranging between 100-
150 years (Umunnakwe1988).
The role of iron and steel in the national economy is enormous.
One cannot name an economic branch where iron and steel find no
application and to some extend the economic power of a country is
determined by its consumption and output of steel products. It is on this
basis, that the Federal Government of Nigeria in 1971 launched the country
into a new era of iron and steel technology by the establishment of the Delta
and Ajaokuta steel projects. Though, the establishment of these projects was
laudable inadequate attention was given to the development of local raw
materials to feed the plants thus, making the plants on commissioning to
import iron ore concentrate form countries like Brazil, Liberia and Guinea.
Recently there has been renewed interests on the souring of locally available
raw materials to feed these plants because the Itakpe iron ore project and the
total iron ore requirement of Ajaokuta at 1.3 million tonnes of steel per
3
annum is about 2.135 million tones of iron concentrate and at this rate the
Itakpe iron ore project is conservatively estimated to last for about 25 years,
(Also and Yakubu, 1995).
Also, the Itakpe iron ore plant commissioned on the 80s to deliver
iron concentrate to Ajaokuta and later closed and now concessioned to
Indians. Would not be able to meet the demand of Ajaokuta Steel plant
when it finally takes off fully. It is therefore, important that these types of
studies be conducted so as to increase the source of Iron Ore for Ajaokuta
plant. And through such studies the technology for the beneficiation of
various Nigerian iron ore deposits for onward supply to Ajaokuta and Delta
steel plants will be developed.
Since the goal of every beneficiation process, mineral-processing
operation in particular, is to effectively separate the valuable material from
the gangue with minimum loss to the tailings; the need to develop and
employ a sustainable, effective and relatively economical method of
separation is imperative. The concentration of the valuable minerals from
the gangue involves exploitation of the differences in physical, chemical and
electrical properties of the ore after effective comminution Akande et al
(2000). This work, therefore, is aimed at developing a process route for the
beneficiation of the Agbado- Okudu iron ore deposit located close to Jakura
village in Kabba, Kogi State for its possible utilization in Ajaokuta and
Delta Steel Plants.
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