ABSTRACT
The utilisation of waste materials to producea useful product is highly encouraged to avoid its disposal on land fields so as to safeguard the environment. Kaolin waste, soda lime and borosilicate glass wastes were used to develop glass ceramic. The oxides content of the raw materials were determined using the X-Ray Florescence machine while the moisture content and loss on ignition were determined by the weight loss method and the following results were obtained; SiO₂ 80.50% for borosilicate 77.63% in soda lime and 46.80% in kaolin, Fe₂O₃ content in borosilicate was O.22%, 0.30%in soda lime and 0.01% in kaolin .V₂O5 was found in kaolin and soda lime glass wastes and B₂O₃ only in borosilicate glasswaste.CaO content of 7.46% in soda lime with value less than 1.0% in kaolin and borosilicate. Loss on ignition of 10.13% was found in kaolin, 0.30% in soda lime and 1.34% in borosilicateAl₂O₃ content of kaolin is 31.41%, 0.60% in soda lime and 0.52% in borosilicate, the MgO content of 0.20% in kaolin, 2.63% soda lime and 0.03% in borosilicate waste glass. Particle sizes of 90 μm, 125 μm and 250 μm of the waste glasses were used to formulate batches. which were compressed into pellet shape of 20mm in diameter with a thickness of 5mm.Hydraulic pressing machine at a pressure of 10metric tones using the polyvinyl chlorine (PVC) organic binder was used to produce pellets.Then sintered at 750c°, 850°c and 950°c in a furnace at a heating rate of 50C /min with residence time of one hour and cooled gradually. The composition containing kaolin, soda lime, borosilicate with 90μm particle size sintered at 950°Cgave the highest shrinkage in diameter with value of 17.36% and a batch containing kaolin, borosilicate and Na₂SO₄ with 250 μm particle size sintered at 750°C gave average of 0.94% in diameter. The physical properties of porosity, water absorption and bulk density were measured at all sintered temperatures for all the batches. The highest bulk density was found to be 2.54g /cm3 in the batch K₅B₅SL₉ₒ with 90 μm particle size at 850°C sintering temperature.The least bulk density is 1.34g/cm3 and the highest porosity of 26.84% were observed in batch K₁₅ B₅ SL₈ₒ with 250μm particle size at 750°C.The least value of 0.68% in batch K₁ₒ B₈₅ NS₅ with 125μm particle size at 950°C.The highest value of 18.02% water absorption was recorded for batch K₅ B₅ SL₈ₒ with 250μm at 750°C with the least value of 0.34% at 950°C .The highest hardness value was recorded for batch K5B₉₅ NSₒ with 90μm particle size at 950°Cwas81.5 Nm2 Rock well superficial scale and the least value of 70.5Nm2 was found in batches K10B₈₅ NS₅ with 125 μm particle size and K10B₅ SL8₅ with 125μm particle size sintered at 950° C. The most acid resistance batch was K₁₅ B₈ₒNS₅ with 250μm sintered at 750°C, 850°C and 950°C. The least acid resistance batch was K₁ₒ B₈₅ NS₅ with 7.85% loss sintered at 950°C with 125 μm. The most alkali resistance batch was found to be K₅ B₅ SL₉ₒ with 90 μm particle size with value of 0.35% sintered at 850 °C and 950°C and the least alkali resistance batch was observed in K5 B95 NS0 with 90 μm particle size with value of 8.87% sintered at 850°C. The X-Ray Diffraction (XRD) result for batch K₅ B₅ SL₉ₒ with 90 μm particle size showed thatCrystallisation occurs at 750°C and for batch K5 B95NS0 of same particle size, amorphous peaks were observed at the same sintering temperature. Scanning Electron Microscopy (SEM) appearance of a square pillar like crystals for batches K15 B80 NS5 at 125 μm and 250 μm sintered at 850°C and 950°C revealed sharp XRD peaks which correspond to that of diopside crystalline phase (CaO .MgO.Al₂O-SiO8) .The SEM appearance of feathery crystals for batches K5B5SL90 with 90 μm sintered at 850⁰C, K10 B5SL85with 125 μm sintered at 850°C and 950°Cindicated an anorthite( CaO .Al₂O₃SiO8) crystal phase… The results obtained in this study showed that the glass ceramic developed can be used as lining for materials in construction and communication, heat and wear-resistance appliances for thermo-chemical, biomedical and ceramic coatings.
TABLE OF CONTENTS
Cover page………………………………………………………………………i
Title page………………………………………………………………………..ii
Declaration……………………………………………………………………..iii
Certification……………………………………………………………….……iv
Dedication……………………………………………………………………………………………..v
Acknowledgement………………………………………………………………vi
Abstract…………………………………………………………………………..vii
Table of Contents………………………………………………………………viii
List of Figures……………………………………….. …….. ……………………xiv
List of Tables……………………………………………………………………xvi
List of Plates…………………………………………………………………….xvii
List of Appendices………………………………………………………………xviii
CHAPTER ONE: INTRODUCTION
1.1 Background………………………………………………………………… 1
1.2 Statement of Problem………………………………………………………. 3
1.3 Aim and Objectives of the Study…………………………………………… 4
1.4 Justification………………………………………………………………… 4
1.5 Significance…………………………………………………………………5
16 Scope and Delimitation of the Study………………………………………. 6
CHAPTER TWO: LITERATURE REVIEW
2.1 Glass Ceramics……………………………………………………………… 7
2.2 Waste Generation…………………………………………………………… 8
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2.3 Waste Recycling ………………………………………………………. 9
2.4 Glass Recycling……………………………………………………………. 10
2.5 Borosilicate Glass………………………………………………………….. 11
2.6 Borosilicate Glass Waste…………………………………………………… 11
2.7 Soda lime Silica Glass……………………………………………………… 12
2.8 Soda lime Silica Waste Glass……………………………………………… 12
2.9. Kaolin………………………………………………………………………. 13
2.10 Kaolin Deposit in Nigeria………………………………………………….. 13
2.11 Kaolin Processing Waste………………………………………………….. 14
2.12 Glass Ceramics Products……………………………………………………15
2.13 Nucleation and Crystallisation……………………………………………… 15
2.14 Glass Ceramic Process Route……………………………………………… 16
2.15 Devitrification……………………………………………………………… 20
2.16 Glass-Ceramics Composition Systems…………………………………….. 22
2.17 Glass Ceramic Production Methods………………………………………… 23
2.17.1 Conventional Method………………………………………………………. 23
2.17.2 Petrurgic Method…………………………………………………………… 24
2.17.3 Powder Sintering Method………………………………………………….. 24
2.17.4 Uniaxial Pressing Technique………………………………………………. 25
2.18 Particle Size………………………………………………………………… 25
2.19 Forming……………………………………………………………………. 26
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2.20 Densification……………………………………………………………….. 26
2.21 Sintering……………………………………………………………………. 27
2.21.1 Solid State Sintering……………………………………………………….. 27
2.21.2 Sintering Mechanism………………………………………………………. 27
2.23 Types of Glass Ceramics…………………………………………………… 30
2.23.1 Commercial Glass Ceramics……………………………………………….. 30
2.23.2 Machinable Glass Ceramics……………………………………………….. 31
2.23.3 Dental Glass Ceramics……………………………………………………… 31
2.23.4 Bioactive Glass Ceramics………………………………………………….. 32
2.23.5 Electrically Conducting and Insulating Glass Ceramic……………………. 32
2.23.6 Transparent Glass Ceramics……………………………………………….. 33
2.23.7 Glass – Ceramic Armor…………………………………………………….. 33
2.24 Properties of Glass ceramics………………………………………………. 34
2.24.1 Mechanical Properties……………………………………………………… 34
2.24.2 Density…………………………………………………………………….. 34
2.24.3 Thermal Properties…………………………………………………………. 35
2.24.4 Optical Properties………………………………………………………….. 35
2.24.5 Electrical Properties……………………………………………………….. 35
2.24.6 Dielectric Properties………………………………………………………… 36
2.24.7 Chemical Properties………………………………………………………… 38
2.25 Applications of Glass Ceramics……………………………………………. 38
2.26 Production of Glass Ceramics from Wastes Materials…………………….. 39
CHAPTER THREE: MATERIALS AND METHODS
3.1 Raw Materials……………………………………………………………… 50
3.2 Sample Treatment and Laboratory Analysis………………………………. 50
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3.2.1. Beneficiation……………………………………………………………….. 50
3.2.2 Sample Preparation………………………………………………………… 51
3.3 X-Ray Fluorescence Analysis……………………………………………… 51
3.4 Determination of Moisture Content of Kaolin……………………………… 52
3.5 Batch Formulation…………………………………………………………. 52
3.6 Pellet Formation……………………………………………………………. 55
3.7 Sintering……………………………………………………………………. 55
3.8 Determination of Percentage Firing Shrinkage……………………………. 58
3.9 Measurement of Bulk Density, Apparent Density and Percentage Porosity. 58
3.10. Water Absorption…………………………………………………………… 60
3.11 Hardness Test…………………………………………………………….. 61
3.12 X-ray Diffraction Studies………………………………………………….. 62
3.13 Scanning Electron Microscopy Studies……………………………………. 62
3.14 Chemical Durability Test…………………………………………………… 62
CHAPTER FOUR: RESULTS
4.1 Sample Collection………………………………………………………….. 65
4.2. Pulverised and Sieved Samples……………………………………………. 65
4.3. Moisture Content and Loss on Ignition……………………………………. 65
4.4 Oxides Analysis……………………………………………………………. 65
4.5 Pellets Formation…………………………………………………………… 67
4.6 Sintering…………………………………………………………………… 67
4.7. Shrinkage…………………………………………………………………… 70
4.8 Water absorption, Percentage Porosity, Bulk and Apparent Densities…….. 72
4.8.1 Water Absorption………………………………………………………….. 72
4.8.2 Porosity…………………………………………………………………….. 75
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4.8.3 Bulk and Apparent Densities………………………………………………. 78
4.9 Hardness……………………………………………………………………. 84
4.10 Chemical durability………………………………………………………… 86
4.11 Scanning Electron Microscopy and X-ray Diffraction…………………….. 86
CHAPTER FIVE: DISCUSSION
5.1 Moisture Content and Loss on Ignition……………………………………. 101
5.2 Oxides Analysis……………………………………………………………. 101
5.3 Particle Size Effect…………………………………………………………. 102
5.3.1 Shrinkage…………………………………………………………………… 102
5.3.2. Water Absorption…………………………………………………………… 103
5.3.4 Porosity…………………………………………………………………….. 103
5.3.5 Bulk and Apparent Densities………………………………………………. 104
5.3.6 Hardness……………………………………………………………………. 105
5.4 Composition Effect………………………………………………………… 105
5.4.1 Shrinkage…………………………………………………………………… 105
5.4.2. Water Absorption…………………………………………………………… 106
5.4.3 Porosity…………………………………………………………………….. 107
5.4.4 Bulk and Apparent Densities………………………………………………. 107
5.4.5 Hardness ……………………………………………………………… 108
5.5 Sintering Temperature Effect………………………………………………. 109
5.5.1 Shrinkage…………………………………………………………………… 109
5.5.2 Water Absorption…………………………………………………………… 109
5.5.3 Porosity…………………………………………………………………….. 110
5.5.4 Bulk and Apparent Densities………………………………………………. 110
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5.5.5 Hardness …………………………………………………………………. 111
5.6. Chemical durability………………………………………………………… 111
5.7 Scanning Electron Microscopy and X-ray Diffraction…………………….. 112
CHAPTER SIX: SUMMARY, CONCLUSION AND RECOMMENDATIONS
6.1. Summary…………………………………………………………………… 117
6.2 Conclusion…………………………………………………………………. 117
6.3 Recommendations………………………………………………………….. 118
REFERENCES……………………………………………………………..
CHAPTER ONE
INTRODUCTION
1.1 Background
Glass ceramics are fine grain polycrystalline ceramic materials obtained through the controlled Crystallisation of suitable glass compositions and different heat treatments (Callister, 2005).Considerable research work has been devoted to the recovery and safe, use of waste residuesfrom industries and domestic uses. The wastes from industry contain a high concentration of toxic substances, heavy metals, organic substances and soluble salts. Waste processing resulting in reduction of the noxious and toxic substance occupies a central place for environmental preservation. Recycling methods and technologies with minimum quantity of energy and time are designed for the protection of the environment against pollution by toxic elements produced by industrial chemical waste (Sheppard, 1990).The development of new glass ceramics is particularly relevant due to the possibilities of recycling large amounts of waste materials by incorporating them into the glass ceramics formulations. This trend is in line with one of the most important concerns of the present to ensure the quality of life of future generations by the minimization of the consumption of traditional raw – materials (Menezes et al., 2002 and Andreola et al., 2002).
The production of glass ceramic materials made by recycling industrial waste is an innovative development in theglass ceramic industry. Many researchers have paid much attention to the production of glassceramic and sintered materials from industrial wastes to make them reasonably safe for the environment .The insertion of waste materials into the productive cycle might represent an alternative option which is interesting from both environmental and economic perspective (Sanchezet al., 2006).
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The primary advantages of glass ceramics materials are higher strength, chemical durability and electrical resistance which can be made with very low thermal expansion coefficients, giving excellent thermal shock resistance (Rahaman, 2003). They are attractive materials used in various applications and are commercially important due to their unique properties. These properties make them superior to the parent glass, making them suitable for the construction, mechanical and chemical industries around the world (Romualdoet al., 2008).
There has been considerable research on the production of glass -ceramics from a variety of silicate wastes in the last few decades. The development of glass ceramics involved intensive heat treatment technologies that have been widely used for the treatment of several silicate wastes usually processed to form glass ceramic products. These wastes, coming from numerous sources can be considered raw-materials (Rawlings et al. 2006).
Kaolin being an important raw material for various industries, such as the ceramic, rubber, plastic,and paint, chemicals, cement and paper industries generateslarge amount of wastes because the part used for the industries is small compared to the waste being generated. A lot of studies have indicated the viability of using the kaolin processing wastes as alternative raw materials for the production of ceramic bricks and glass ceramic materials which shows better chemical and mechanical performance (Erolet al., 2008). The reuse of the glass waste in ceramic system is capable of improving the performance of both chemical and mechanical properties compared to conventional ceramic material, especially in highly demanding structural applications (Romualdo et al., 2009).
Several factors such as particle size distribution, and binders for holding the powder together during pellets formation and sintering process are to be considered to ensure quality of glass ceramics manufactured from waste silicates.
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The present study concentrates on the preparation of glass ceramics using kaolin processing waste, borosilicate and soda lime waste glass.The developed glass ceramics were subjected to physical, chemicaland mechanical tests. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis were used to analyze the microstructure and crystal phases present in the samples produced. The properties achieved would determine the potential applications of the product.
1.2 Statement of Problem
Nigeria has abundant mineral deposits, and kaolin is one of the raw – material that is important in various industries for different kinds of production.It isestimated that over 70 percent of the wastes coming from mining and beneficiation is discharged into streams, rivers or dumped in open air sites. These are inorganic wastes that contain heavy metals such as lead, chromium and other toxic elements.Kaolin waste aggravating problem is that it is not exploited, and its powdery nature leads to its inhalation which causes lungs and skin diseases. So its disposal is a serious threat to humans (Luisa et al., 2002).
Today in Nigeria, wastes such as glasses, papers, plastics and others are not adequately utilised but are usually disposed in landfills. These cause damage to the environment through air, soil and water contamination which are potentially harmful to plants, animals and human.
Disposal of waste glass(borosilicate glasses) obtained from scientific laboratories and glasses used for containers, furniture in our homes as table tops and window glasses (soda lime glasses) are dumped on landfills which litters around or buried in the soil and being non-biodegradable cause contamination and pollution of the environment.
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1.3 Aim and Objectives of the Study
The aim of this study is to develop and characterize a glass ceramic product using kaolin processing waste, borosilicate and soda lime wastes glass with the following objectives;
i. To determine the chemical oxides composition of waste kaolin , borosilicate and sodalime glass waste
ii. To formulate batch compositions of three different proportions considering the particle sizes of the waste glasses, with some batches containing sodium sulphate to study the effect of soda lime glass waste
iii. To determine the effect of sintering temperatures on the properties of the produced glass ceramics.
iv To determine the physical, chemical and mechanical properties of the glass ceramic
vTo analyse the crystalline phases present in glass ceramics as well as their microstructure.
1.4 Justification
Glass ceramics arecategory of glasses used for high technology and special applications such as building materials, cooking ceramics, machinable ceramics,optical materials and bio-active glass ceramics in addition to their common uses in domestic appliances. They are mostly produced using numerous silicate based wastes from processing industries such as coal combustion ash, slag from steel production, sugar cane baggase, fly ash, bottom ash, pulp paper waste ashes,and filter dust from blast furnace slag and mud from hydrometallurgy plant. All these ashes are by products of the incineration process which
releases toxic particles and gaseous emissions to the atmosphere leading to pollution and contamination causing health hazards.
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The production of glass ceramic materials made by recycling industrial waste is an innovative development in glass – ceramic industry. Many researchers have paid much attention to produce glass, glass ceramic and sintered materials from industrial wastes.. The application of glass ceramics is gaining strength in all fields of science and technology such as in medical (dental and orthopedic), electrical and architectural field.This makes it necessary for researchers to intensify their activities in this growing field of material sciences.
1.5 Significance
The significance of this study is to develop glass ceramic from wastes other than incinerated by products which are of great concern on the enormous quantity of wastes generated by the numerous industrial sectors which have been the sources of environmental contamination and pollution in Nigeria. Using recycled materials will ultimately reduce the environmental contamination.
Mining and beneficiation processes are good examples of waste generation, these waste materials have traditionally been discarded in landfills and often dumped directly into the ecosystems without adequate treatment. These waste products often contain heavy metals that lead to environmental contamination and pollution causing major health hazards such as cancer, brain and nerve damage, birth defects, lung injury and respiratory problems (Luisa et al.,2002)
Recycling and utilization of glass and kaolin wastes will reduce its disposal in landfills which invariably sanitize the environment, making it clean and safe from the effects of contamination and pollution. Currently over 4.2 million glass waste is generated from household and industrial wastes and collected for recycling worldwide, this saved over 1.34million tonnes of carbon dioxide from being released to the environment (Luisa et al.,2002;Oluseyi et al., 2013).
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Economically, the use of these wastes will minimize the consumption of natural raw materials, reduce production cost, save energy, reduce importation, promote industrial development and provide employment in Nigeria.
1.6 Scope and Delimitation of the Study
This study is delimited to the development of glass ceramic using waste kaolin obtained from kaolin mining and processing plant in Kaloma, Alkaleri- Bauchi State. The borosilicate glass wastes from the Science Laboratories in NuhuBamalli Polytechnic, Zaria and soda lime glass wastes from postconsumer white bottles and broken window glasses in SabonGari Zaria. The particle sizes investigatedwere 90μm, 125μm and 250μm. The waste materials were mixed with poly vinyl chloride (PVC) as binder, then pressed by uniaxial pressing at 10 metric tonnes, and sintered at temperatures of 750oC, 850oCand 950oC.
Physical, chemical, mechanical, scanning electron microscopy and x-ray diffractrometry characterizations of the properties of the glass ceramic products were determined using ASTM standard methods.
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