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Relationship between biohydrometallurgy and weathering
Weathering is described as the breakdown of materials on the earth’s crust, which leads to changes in the composition of the original materials yielding more stable products (Banfield et al., 1999; White et al., 1992; Burford et al., 2003). Weathering could be biological, physical or chemical (Banfield et al., 1999; White et al., 1992), but weathering described in this study is biological. This is in some situations referred to as bioweathering, defined by Sollas (1880) as a process that involves the erosion, decay and decomposition of rocks and minerals caused by living organisms. There are numerous advantages associated with weathering in nature. The most discussed topic pertaining to weathering is its natural effects, which ensure nutrient cycling and availability to both plants and microbes in the soil (Banfield et al., 1999; White et al., 1992; Burford et al., 2003; van Scholl et al., 2006b). Putting the pieces of this puzzle together, weathering could therefore be described as a natural bioleaching process that involves slow and gradual degradation or purification or solubilisation of some important minerals which can occur over a long period of time. In addition, it is also a process that could remove toxic metals from the environment (Willscher and Bosecker, 2003).
Apart from the fact that both biological weathering and bioleaching are natural processes, there are many other features that are also shared between them (Rawlings, 2002; Rawlings, 2005; Willscher and Bosecker, 2003). These include production of organic acid, mobilisation, binding and solubilisation of metals. Therefore, it may be true that some natural microbial weathering agents could also be bioleaching agents. In some situations, weathering roles of some microorganisms have been translated as bioleaching (Styriakova et al., 2003; Jain and Sharma, 2004). However, further studies on both processes could provide more information on how bioleaching occurs in nature. In addition, potential bioleaching agents may also be identified by investigating microorganisms that are known to participate in weathering.
CHAPTER ONE LITERATURE REVIEW.
1.1 Introduction – Biohydrometallurgy.
1.2 Relationship between biohydrometallurgy and weathering
1.3 Biohydrometallurgy as a technology
1.4 Bioleaching methods
1.5 Bioleaching of sulfidic minerals.
1.6 Bioleaching of non-sulfidic minera;s
1.6.2 Mechanisms of biobeneficiation of non-sulfidic minerals.
1.6.3 Importance of organic acid to biobeneficiation of non-sulfidic minerals
1.6.4 Factors affecting bioleaching of non-sulfidic minerals
1.6.5 Bacterial leaching of non-sulfidic minerals
1.6.6 Fungal leaching of non-sulfidic minerals
1.7 Iron ore
1.7.2 Iron ore in South Africa.
1.7.3 Biobeneficiation of iron ore
1.8 Objectives of the study:
1.9 References
CHAPTER TWO IMPLICATION OF ECTOMYCORRHIZAL WEATHERING OF IRON ORE MINERALS: THE BIOLEACHING CONNECTION.
2.1 Introduction.
2.2 Materials and Methods
2.2.1 Origin of ectomycorrhizal fungi
2.2.2 Iron ore preparation
2.2.3 Preparation of seeds
2.2.4 Mycorrhizal synthesis experiment
2.2.5 Soil Treatments.
2.2.7 Watering and nutrient supply
2.2.8 Harvesting
2.2.9 Organic acid analyses
2.2.10 Plant root and shoot analyses
2.2.11 Statistical analyses
2.3 Results
2.4 Discussion
2.5 References
CHAPTER THREE MOBILISATION OF POTASSIUM AND PHOSPHORUS FROM IRON ORE BY ECTOMYCORRHIZAL FUNGI
3.1 Introduction
3.2 Materials and Methods
3.2.1 Origin of fungal isolates and iron ore preparation
3.2.2 Media preparation.
3.2.3 Organic acid analyses by High Performance Liquid Chromatography (HPLC
3.2.4 Chemical analyses for nutrients absorbed by the ECM fungi.
3.2.5 Microscopy
3.2.6 Elemental analyses
3.2.7 Statistical analyses and experimental design
3.3.1 Mobilisation of K and P in relation to particle size and organic acid production
3.3.2 Organic acid production
3.3.3 Aqueous K /P and Dry mycelia K/P
3.3.4 Microscopy.
3.4 Discussion
3.5 References
CHAPTER FOUR COMPARISON BETWEEN DIRECT SOLUBILISING EFFECTS OF IRON ORE-ASSOCIATED FUNGUS AND ITS METABOLITE Introduction
4.2 Materials and Methods
4.2.1 Origin and preparation of iron ore samples
4.2.2 Preparation of media and isolation of fungi from iron ore samples.
4.2.3 Molecular identification of the isolates
4.2.4 Phylogenetic analysis .
4.2.5 Fungal leaching experiment.
4.2.6 The use of fungal metabolites
4.2.7 Harvesting .
4.2.8 Organic acids detection
4.2.9 Statistical analyses
4.3 Results
4.5 References
CHAPTER FIVE CULTURABLE MICROORGANISMS ASSOCIATED WITH SISHEN IRON ORE AND THEIR POTENTIAL ROLES IN BIOBENEFICIATION
5.1 Introduction.
5.2 Materials and methods
5.2.1 Origin and preparation of iron ore samples
5.2.2 Preparation of media.
5.2.3 Isolation of bacteria from iron ore samples .
5.2.4 Screening of phosphorus-solubilising, potassium-solubilising and low pH- isolates..
5.2.5 Molecular identification of the isolates
5.2.6 Phylogenetic analysis .
5.2.7 Leaching experiments.
5.2.8 pH measurement and high performance liquid chromatography (HPLC) .
5.2.9 Fourier transform infrared (FTIR) spectroscopy
5.2.10 Microscopy
5.2.11 Induction Coupled Plasma (ICP)
5.2.12 Experimental design and Statistical analyses..
5.3 Results
5.4 Discussion
5.5 References
CHAPTER SIX. FERMENTATION IN BIOHYDROMETALLURGY, A NOVEL METHOD FOR K AND PREMOVAL FROM IRON ORE.
7 GENERAL DISCUSSION, CONCLUSION AND RECOMMENDATION.
APPENDICES.
