ABSTRACT
Nigeria is endowed with vast
deposits of clay spread across her various regions. Today, almost all the clay
requirement of the country in the form of refractory and bentonite are imported
from the Great Britain, China and Japan etc. leading to high cost of procurement
and consequently result to high cost of finished products. This work is aimed
at investigating the plasticity and refractory properties of locally available
clays for possible use in our industries. Ososun, Abule-Oloni, Ile-IseAwo and
Osiele clay were collected from Ogun State. The properties investigated include
Bulk density, apparent porosity, Linear shrinkage, Thermal shock resistance,
Cold crushing strength, and loss on Ignition. The Refractoriness was estimated
using Pyrometric Cone Equivalence PCE) while the chemical composition was
determined using the Atomic Absorption Spectrophotometer (AAS). Based on the
chemical composition analysis, the clays were found to be Aluminosilicate clay
and from the result obtained from the physical test, almost all the properties
investigated gave results that are acceptable for use as a clay refractory
except the compressive strength of all samples fall below the minimum
specification which could be attributed
to inadequ ate power supply that resulted to inconsistent
firing. Findings shows that Ososun and Abule-Oloni Clays can be used for
refractory purposes such as firebricks, ramming masses, linings of iron and
steel making furnaces and ceramic product such as tiles and furnace crucibles.
TABLE OF CONTENTS
Contents Page
No
Title Page
……………………………………………………………………………i
Certification………………………………………………………………………… ii
Dedication……………………………………………............................................... iii
Acknowledgement………………………...……...….
…………………………….. iv
Table of contents…………………………..………………………………………. v
Abstract……………………………..……………………………………………… vii
List of Figures………………………………………………………………………………
List of Tables……………………………………………………………………………….
CHAPTER ONE………………………………………………………………………… 1
1.0 Introduction………………………………………………………………… 1
1.1 Background of the study……………………………………………………… 4
1.2 Statement of the problem………………………………………………………… 7
1.2 Aim and Objectives of the study…………………………………………………… 7
1.4 Scope and delimitation of the study……………………………………………… 8
1.5 Significance of the study …………………………………………………………… 10
1.6 Definition of Terms……………………………………………………………….11
CHAPTER TWO…………………………………………………………………………. 14
2.0 Literature Review……………………………………………………………………14
2.1 Nature of Refractory Clay………………………………………………………… 15
2.1.1 Classes of Refractory Clay………………………………………………………… 16
2.2 Properties of Clay……………………………………………………………………20
2.2.1 Thermal properties of clay………………………………………………………… 22
2.2.2 Physical Properties of Clay………………………………………………………… 25
2.2.3 Mechanical properties of Clay………………………………………………………28
CHAPTER THREE
3.0 Experimental Procedure…………………………………………………………… 30
3.1 Sourcing of materials for preparation……………………………………………… 30
3.2 Tools and equipment used for the production processes……………………………31
3.3 Experimental Procedure for the Research Work……………………………………32
3.4 Characterization Procedure………………………………………………………….33
3.4.1 Determination of Plasticity Index……………………………………………… 33
3.4.2 Bulk density……………………………………………………………………… 34
3.4.3 Moisture content……………………………………………………………………34
3.4.4 Fired linear shrinkage ………………………………………………………………34
3.4.5 Compressive Strength ………………………………………………………………35
3.4.6 Determination of Thermal
Shock Resistance……………………………………...36
3.4.7 Determination of
refractoriness (PCE) …………………………………………… 36
CHAPTER FOUR………………………………………………………………………… 37
4.0 Results and Discussion………………………………………………………………… 37
4.1 Compositional Analysis of clay Samples from Ogun State………………………. 37
4.2 Atterberg Limits………………………………………………………………….. 38
4.3 Sieving Results (Particle Size Distribution) ……………………………………… 42
4.4 Physico-mechanical Properties…………………………………………………… 43
CHAPTER 5 …………………..……………………………………………………….. 49
5.0 Conclusion……………………………………………………………………….. 49
References…………………………………………………………………………
51
List of Figures
Figure 1.1:
Map of Nigeria Showing Ogun State map at Latitude 6.9098ON and Longitude 3.2584OE Showing the location for the Clay
deposits.
Figure 3.1:
Pictures of clay samples from different site in Ogun State
Figure 3.2:
Pictures of some of the tools and equipment used to carry out the research
Figure 3.3:
Process flowchart for the research work
Figure 4.1:
Liquid Limit graph for Ososun Clay
Figure 4.2:
Liquid Limit graph for Abule-Oloni Clay
Figure 4.3:
Liquid Limit graph for Ile-Ise Awo Clay
Figure 4.4:
Liquid Limit graph for Osiele Clay
Figure 4.5:
Bulk Densities of the sampled clay as a function of Firing Temperature
Figure 4.6:
Water absorption of the sampled clay as a function of Firing Temperature
Figure 4.7:
Thermal Shock Resistance of the sampled clay
Figure 4.8:
Compressive and Refractoriness of the sampled clay
List of Tables
Table 2.1:
Percentage composition of clay minerals
Table2.2: Mechanical
properties of five selected clay at 1200oc
Table 4.1:
Chemical composition of the clay sample from different deposit in Ogun state
Table 4.2: Atterberg limit Ososun
Clay
Table 4.3: Atterberg limit Abule-Olon
Clay
Table 4.4: Atterberg limit Ile-IseAwo
Clay
Table 4.5:
Plasticity index value for the sampled clay
Table 4.6:
Sieving result test samples
Table 4.7: Physico-mechanical
properties of Ososun clay
Table 4.8: Physico-mechanical
properties of Abuleolowi clay
CHAPTER ONE
1.0 Introduction
Clay is a common name for a number of
fine-grained, earthy materials that become plastic when wet. Chemically, clays
are hydrous aluminum silicates, ordinarily containing impurities, e.g.,
potassium, sodium, calcium, magnesium, or iron, in small amounts Grimshaw
(1959). They are divided into two classes: residual clay, found in the place of
origin, and transported clay, also known as sedimentary clay, removed from the
place of origin by an agent of erosion and deposited in a new and possibly
distant position. Residual clays are most commonly formed by surface
weathering, which gives rise to clay in three ways—by the chemical
decomposition of rocks, such as granite, containing silica and alumina; by the
solution of rocks, such as limestone, containing clayey impurities, which,
being insoluble, are deposited as clay; and by the disintegration and solution
of shale (Ryan,1978). One of the commonest processes of clay formation is the
chemical decomposition of feldspar. Clay minerals are typically formed over
long periods of time by the gradual chemical weathering of rocks, usually
silicate-bearing, by low concentrations of carbonic acid and other diluted
solvents. These solvents, usually acidic, migrate through the weathering rock
after leaching through upper weathered layers. In addition to the weathering
process, some clay minerals are formed by hydrothermal activity Guggenheim et
al., (1995). Clay deposits may be formed in place as residual deposits in soil,
but thick deposits usually are formed as the result of a secondary sedimentary
deposition process after they have been eroded and transported from their
original location of formation. Clay deposits are typically associated with
very low energy depositional environments such as large
lakes and marine basins. Primary
clays, also known as kaolins, are located at the site of formation. Secondary
clay deposits have been moved by erosion and water from their primary location.
Depending on the academic source, there are three or four main groups of clays:
kaolinite, montmorillonite-smectite, illite, and chlorite. Chlorites are not
always considered to be clay, sometimes being classified as a separate group
within the phyllosilicates. There are approximately 30 different types of
"pure" clays in these categories, but most "natural" clays
are mixtures of these different types, along with other weathered minerals.
Ehlers et al.,(1982)..
Clays exhibit
plasticity when mixed with water in certain proportions. When dry, clay becomes
firm and when fired in a kiln, permanent physical and chemical changes occur.
These reactions, among other changes, cause the clay to be converted into a
ceramic material. Because of these properties, clay is used for making pottery
items, both utilitarian and decorative. Different types of clay, when used with
different minerals and firing conditions, are used to produce earthenware,
stoneware, and porcelain. Clay, being relatively impermeable to water, is also
used where natural seals are needed, such as in the cores of dams, or as a
barrier in landfills against toxic seepage (lining the landfill, preferably in
combination with geotextiles). Hillier (2003) Clay is one of the oldest
building materials on Earth, among other ancient, naturally-occurring geologic
materials such as stone and organic materials like wood. Between one-half and
two-thirds of the world's population, in traditional societies as well as
developed countries, still live or work in a building made with clay as an
essential part of its load-bearing structure.
Properties of the
clays include plasticity, shrinkage under firing and under air drying, fineness
of grain, color after firing, hardness, cohesion, and capacity of the surface
to take decoration. On the basis of such qualities clays are variously divided
into classes or groups; products are generally made from mixtures of clays and
other substances. The purest clays are the china clays A refractory material is
one that retains its strength at high temperatures. ASTM C71 defines
refractories as "non-metallic materials having those chemical and physical
properties that make them applicable for structures or as components of
systems, that are exposed to environments above 1,000 °F (811 K; 538 °C)".
Guggenheim et al., (1995).
Refractory materials
are used in linings for furnaces, kilns, incinerators, reactors and crucibles.
Refractory materials must be chemically and physically stable at high
temperatures. Depending on the operating environment, they need to be resistant
to thermal shock, be chemically inert, and/or have specific ranges of thermal
conductivity and of the coefficient of thermal expansion. The oxides of aluminum
(alumina), silicon (silica) and magnesium (magnesia) are the most important
materials used in the manufacturing of refractories. Another oxide usually
found in refractories is the oxide of calcium (lime). Fire clays are also
widely used in the manufacture of refractories. Refractories must be chosen
according to the conditions they will face. Some applications require special
refractory materials. Zirconia is used when the material must withstand extremely
high temperatures. Silicon carbide and carbon (graphite) are two other
refractory materials used in some very severe temperature conditions, but they
cannot be used in contact with oxygen, as they will oxidize and burn.
Binary compounds such as tungsten
carbide or boron nitride can be very refractory. Hafnium carbide is the most
refractory binary compound known, with a melting point of 3890 °C. Hugh (1992) the
ternary compound tantalum hafnium carbide has one of the highest melting points
of all known compounds (4215 °C). McGraw-Hill (1977).
1.1 Background of the study
Interest
in clays has increased in recent years due to their physic-chemical and plastic
properties, which make them some of the most widely used materials in industry
for making traditional ceramics. Since Atterberg (1911) much work has been done
in soils and sediments in an attempt to evaluate the influence of the various
factors involved in the plasticity of clay samples, such as their mineralogical
composition, shape, size distribution of particles, interaction among clays or
with water or dissolved salts, the effect of cementing, clay genesis, etc.
Casagrande published his well-known soil chart in 1948, and Dumbleton and West
(1966) studied the relationships between clay contents and the plastic and
liquid limits of natural soils from around the world, in an attempt to define
the contribution of clay component to the engineering properties of soil as a
whole. More specifically, Bain (1971) focussed on industrial clays (halloysite,
kaolinite, illite, mixed layers, several kinds of smectites, sepiolite and
paylygorskite), Decleer et al,. (1983) correlated mineral composition,
chemistry and granulometry with plastic and liquid limits in Belgian clays, and
Hawkins et al., (1986) did similar analysis in the UK, while Al-Homoud et al.,
(1996) focussed on clay beds causing landslides and Ohtsubo et al. (2002) on
marine clays.
Perhaps
the most recent and conclusive contribution is by Schmitzet al., (2004) who
introduced equivalent basal spacing (EBS), a parameter obtained by multiplying
the relative amount of a clay with its basal spacing (Å) known from the
literature.
Most
of the traditional ceramic mixtures show plastic type behaviour, due to the
presence of the plate-like morphology of the particles of the clay-based raw
materials that are able to slide over each other due to the water retained in
the interstitial spaces that acts as lubricant. When necessary, commercial
plasticizers might be added, such as methylcellulose or hydroxypropyl
methylcellulose. The measurement and control of the plasticity is essential to
achieve good fabrication conditions (correct shapes and low processing times).
However, the common practice is somewhat empirical, due to the large number of
influent parameters and the lack of sensitive quantification means for the
evaluation of the complex relationship between the flow characteristics and
processed components’ properties.
Raw
materials used in the traditional ceramics industry can be classified as clay
(plastic) and non-clay (non-plastic) minerals. Clays are the chief raw material
for many commercial structural ceramic products such as wall tiles, roofing
tiles, building bricks, and white wares. Chemically, clay minerals are phyllo-
silicates with ions arranged in parallel planes forming layers (Graw-Hill,
1977). Clays occur in deposits of greatly varying nature. No two deposits have
exactly the same clay and frequently different samples of clay from the same
deposit differ.
Clay
products such as wall tiles, ceramic wares, burnt bricks, roofing, and floor
tiles are cheaper and durable building materials than cement especially under
tropical conditions. An optimum combination of various clays is the essential
ingredient in ceramic wall tile composition, which provides plasticity and
green strength during forming stages and contributes substantially to the color
of the fired products depending upon the impurity of oxides present.
The
formation, structure, mineralogical and other physico-chemical properties of
various types of clay minerals are widely being studied. Two factors are
helping the development of good refractories using the local raw materials. The
first one is the growing number of metallurgical industries that are in dire
need of these refractories, while the other factor is the difficulty in
sourcing for foreign exchange market, a situation that has led to higher and
unaffordable cost of procuring the refractory materials needed by these
industries. Some of the refractory materials usually employed are fireclay,
quartz sand, magnesite, sillimanite, berylia, alumina, chromite, zirconia,
boron, nitride, graphite and carbide.
The refractories need of Nigeria which is a
developing industrial nation is potentially enormous. It was estimated that the
Ajaokuta Steel Company and Delta Steel Company will, at full capacity,
respectively require 43,503 and 25,000 tonnes/year of fireclay refractories for
their activities; and these products are sourced from abroad (Hassan et al.,
1993). Ijagbemi (2002) noted that small-scale industries in Nnewi and elsewhere
in the country have recently embarked on the fabrication of spare parts. These
spare parts are fabricated using high temperature furnaces [foundry melting
furnaces and heat-treatment furnaces] that require refractories as linings.
Most of the refractories consumed in this country are sourced from abroad
whereas there are many clay deposits in Nigeria that could be used as
refractories. Ijagbemi (2002) reported that in 1987 alone, Nigeria imported 27
million metric tonnes of refractories. The country expends a lot of foreign
exchange importing refractories. Yet, a lot of clay deposits abound in the country,
which can be developed to meet our local needs. Earlier works on various
Nigerian clay deposits have shown many of them to be rather high in silica
content and low in alumina (NMDC, 1999; Hassan, 2001). However, a number of
deposits were found suitable for use as refractory raw materials; that is, if
properly processed. Therefore, the development of our local materials for the
production of refractories to meet our industrial and technological
requirements is not only justified but imperative.
1.2 Statement of the problem
Nigeria is
endowed with vast deposits of clay
spread across her various regions. Today, almost all the clay requirement of
the country in the form of refractory and bentonite are imported leading to
high cost of procurement and consequently result to high cost of finished
products.
The limit
in the application of local ceramic deposits (clay) is as a result of inadequate study to examine
the relevant mineralogical parameters affecting the plasticity and
refractoriness of samples, in order to easily distinguish and select those
suited for certain technological applications.
1.3 Aim and Objectives of the study
The aim of
this project is to investigate the plasticity and refractory properties of clay
samples of the selected area with
the following objectives:
(i)
To investigate the plasticity of clay samples of
Ososun, Abule-Oloni, Ile-IseAwo and Osiele clays, all from Ogun State;
(ii)
To investigate the refractory properties of clay
samples of Ososun and Abule-Oloni, all from Ogun State;
(iii)
To determine the effect of water content on the
workability of the sampled clay.
1.4 Scope
and de-limitation of the study
This work
is designed to investigate the chemical composition, plasticity and refractory
properties of samples clay selected from Ososoun, Abule-Oloni, Ile-IseAwo and
Osiele in Ogun State.
The
beneficiation of the clay sample is done by filtration and sieving to a fine
particles size of 100μm. The prepared samples clay is pressed in a circular disc
of 3cm by 7cm before firing at different temperature ranges.
The scope of this study is
limited to the chemical composition, plasticity, shrinkage, bulk density,
strength and refractory test carried out in the laboratory and the firing
temperature of the furnace which could not exceed 1400oC.
Figure 1.1:
Map of Nigeria Showing Ogun State map at Latitude6.9098ON and Longitude 3.2584OE Showing the location
for the Clay deposits (Source: Ogun State Bureau of Land and Survey).
1.5 Significance of the study
The
development and production of ceramic material from many clay deposits in
Nigeria for modern usage has been very slow. This research study therefore
traces the success and failure of using local ceramic deposits (clay) to
produce modern table wares with particular reference to the stone ware pottery.
This research work would also cite the study and analysis of physical
properties of ceramic deposits to research on local materials for modern
production of ceramic wares.
The demand
for ceramic wares particularly table wares architectural ceramic in Nigeria has
been on the increase for some time. The study would enable us to put into
process the use of local ceramic deposits for the production of ceramic wares
such as sanitary ware and table ware which would be easily available, cost
effective and create job opportunities for people to earn a living. More so,
the research provides adequate study to find local substitute for the imported
raw materials for the production of ceramic wares.
The
industries which are directly working in the areas related to this study will
immensely benefit from this study whenever they have access to its findings. It
would be easy for prospective investors to know the physical and chemical
properties of these clay minerals. The knowledge will guide their decision on
whether the properties required for their products can be found in any of these
clay deposits.
In
conclusion, the result of this study will be of help to other researchers who
may be seeking for related information while carrying out a similar research
work in future if the result is made available to them in their education
resource centers.
1.6 Definition
of Terms
Beneficiation: process of
winning valuable minerals from gangue (impurities)
Ceramic: A
non-organic and non-metallic substance, often an oxide or carbide.
Ceramic ware: an article
made of ceramic.
Plasticity: a basic clay property that permits this
material to form a plastic body
Refractory: materials
which are capable of withstanding very high temperature condition without
losing their chemical and mechanical integrity.
Click “DOWNLOAD NOW” below to get the complete Projects
FOR QUICK HELP CHAT WITH US NOW!
+(234) 0814 780 1594
Login To Comment