The growth in the use and wear of Ti-based alloy components in mining and offshore explorations has led to a search for techniques to re-engineer such components for reuse. The most desirable method of restoring/protecting the component surfaces is by hard-facing to enhance longevity in service. Laser cladding is one of the viable techniques to achieve a thick coating on such components which involves the addition of reinforcing particulates to improve surface properties such as hardness, wear and erosion resistance amongst others. A fundamental study and understanding of the resultant microstructure-property of the laser clad, hard-facing composite becomes necessary. In this study, laser cladding of Ti-6Al-4V wire with Spherotene particulate reinforcement and laser cladding of modified pre-blend of Ti-6Al-4V and TiB_2 powder were undertaken. The resulting physical and microstructural characteristics, hardness, and performance characteristics of laser clad composites were investigated. Samples from the as-deposited laser clad composites were characterised using optical microscopy, scanning electron microscopy (with chemical microanalysis) and X-ray diffraction. Performance characteristics were examined via erosion testing of the laser clad Ti-6Al-4V/Spherotene using plain and abrasive water jetting, and tensile testing of the laser clad Ti-6Al-4V/TiB_2 composite. The results showed that a crack and pore free clad containing as high as 76 wt.% Spherotene in the Ti matrix was achieved at an energy density of 150 J.mm^-2, 275 mm/min traverse speed, 700 mm/min wire feed rate and 30 g/min powder feed rate. The microstructure of the laser clad Ti-6Al-4V/Spherotene is characterised by nano-sized precipitates of reaction products (W and TiC) uniformly distributed in a beta-Ti solid solution matrix. Matrix hardness is enhanced by the presence of the reaction products in the Ti ranging between 410-620 kgf.mm^-2. Moreover, the modication made to the 90 wt.% Ti-6Al-4V/10 wt.% TiB2 feedstock by attaching the TiB2 to Ti-6Al-4V allowed uniform distribution of reinforcing element in the deposited composite. The composite microstructure on solidication is characterised by TiB eutectic needle-like features uniformly distributed in a Ti-rich primary phase. The hardness of the composite ranged between 440-480 gf.mm^-2. Tensile tests showed that the mean elastic modulus of Ti-6Al-4V/TiB_2 composite is 145 GPa, which is a 27% improvement when compared to that of Ti-6Al-4V. Erosion test indicated that the Ti-6Al-4V/Spherotene composite offered as high as 13 and 8 times resistance of that of Ti-6Al-4V when subjected to PWJ and AWJ impacts respectively.

This thesis covers in detail a study of the excavation of rock salt by roadheader, the factors affecting performance and finally a specification with operational results of a new production machine to suit the South African Coal Mining Industry. Dosco Overseas Engineering Ltd. the author's employer, is introduced. Reference is made to how, over the years, performance prediction has radically changed from a mere approximation to a position where an accurate value with a performance guarantee is a necessity. Reference is made to the Universities of Newcastle-upon-Tyne, Nottingham and Leeds who have been the main suppliers of rock testing facilities. The University of Newcastle-upon-Tyne has had further responsibilities for a specific test programme, funded by Dosco, to establish a Performance Prediction Methodology. A general introduction to the trial site at Domtar Salt, located in Canada, is given, along with the current mining methods and the particular aspects requiring consideration if machine mining were to be adopted. A detailed study over a twelve month period covering three main topics; fines production, performance rates, and cutter pick suitability is described. Results are discussed at length and valuable conclusions are drawn. Extrapolation of the results to predict the performance of a larger machine suitable to Domtar's high production requirements is shown. The ability to relate this study to other applications and, in particular, the aspect of pick penetration and its effect on machine design is discussed. A prediction curve suitable for South African coal is shown, along with the necessary calculations to enable a high production rate and the corresponding effect on machine design. Specification features, such as boom force, cutter head design and cutter motor power, are considered at length. The implications for the machine manufacturer for even larger, more powerful machines is shown. An early correlation· of findings is established by comparison to field results from a smaller single boom, Dosco roadheader. The study concludes that current or new machine design can be favourably influenced to reflect varying market requirements and that accurate prediction of machine performance is possible. A later, overall study of the TB2500 shows achieved production rates and comments in particular, on machine mining rate and available mining time. Recommendations having particular reference to the equipment suppliers involvement in the sales procedure are given.

Early produced water treatment technologies were developed before carbon dioxide emissions and hazardous waste discharge were recognised as operational priority. These technologies are deficient in the removal of dissolved hydrocarbons and dissolved heavy metal ions which have been identified as major contributors to the high environmental impact factor of produced water. The simultaneous removal of heavy metals and polycyclic aromatic hydrocarbon (PAH) from produced water via photoelectrochemical process was identified in this work as a produced water treatment alternative with the potential to virtually eliminate the cost for chemical reagents and high energy input. Several grades of simulated produced water were synthesised and used to understand different parameters necessary for developing a successful photoelectrochemical treatment. The process demonstrated in this work followed a simple two–electrode photoelectrochemical cell where heavy metals were recovered on a platinum electrode with simultaneous degradation of PAH (phenanthrene) on a photoanode, with the aid of sunlight (simulated) and an applied cell voltage of 1.0 V. Multiwall CNT-TiO2 synthesised via a modified sol-gel method served as the photoanode after it was immobilised at a loading of 2.5 mg/cm2 on a titanium plate. The results obtained from the photoelectrochemical treatment showed a recovery of 1.6 g/cm2 of lead, 0.2 g/cm2 of copper and 0.1 g/cm2 of nickel from produced water on a 0.1 cm diameter platinum electrode after 24 hours of irradiation with simulated sunlight at 1.0 V cell voltage and a simultaneous degradation of up to 16 % phenanthrene on the photoanode, which gives a potential of scaling up the process to a commercial throughput.

There is growing interest in Al-TM (transition metal)-RE (rare earth) amorphous alloys because of the combination of their good mechanical properties and corrosion resistance. However, the high critical cooling rate required to form the amorphous structure leads to difficulties in generating bulk amorphous material. Therefore, there has been greater interest in producing amorphous Al-TM-RE alloys as surface layers. In this study, wedge mould casting, laser surface melting (LSM) and large area electron beam (LAEB) surface melting were used to fabricate Al Co-Ce alloys in both crystalline and amorphous form. An eutectic Al 33Cu (wt.%) alloy was also used to quantify the solidification conditions based on the well-known relationship. The microstructures formed by different processes were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, image analysis and X ray and glancing angle X-ray diffraction. In particular, LAEB surface melting was found to be able to provide a sufficiently high solidification velocity for the generation of an amorphous layer on the remelted surface of bulk crystalline Al Co-Ce alloys. Experimental results show that the LAEB treatment can remelt, homogenise the multiphase crystalline starting material and generate a predominantly amorphous layer, although it also caused cracking of the treated layer. However, the cracking was largely reduced in the laser refined starting microstructure. Laser microstructural refinement also improved the homogenisation and amorphisation generated by the subsequent LAEB treatment. The temperature field of multi-pulse LAEB irradiated Al-Co-Ce and Al-Cu alloys was numerically simulated through a finite difference method. The simulation results were generally consistent with the experimental results. The corrosion behaviour of Al-Co-Ce alloys with different microstructures was studied through potentiodynamic polarisation tests. Al-Co-Ce amorphous layer exhibited an enhanced corrosion resistance compared to the crystalline counterpart, although cracking in the amorphous layer greatly influenced the effectiveness of the amorphous layer protecting the substrate.

<p> Ground conditions at underground gold mines in Nevada range from good to extremely poor and implementing the most appropriate ground support can be challenging. Existing empirical ground support design methods were developed predominantly from experience in tunneling or more competent ground, making them less applicable to underground gold mining in Nevada. This research presents empirically derived support guidelines from experience at 5 underground gold mines in Nevada, including: discussions with engineers and miners, review of ground control management plans and consulting documents, and roughly 400 ground control case-studies. Support design recommendations are based on the Weak-Rock Mass Rating (W-RMR) which is a modified Rock Mass Rating (RMR) classification incorporating the Unified Soil Classification System (USCS) for very weak rock masses. Ground support recommendations include rock bolt pattern support pressure, rock bolt length category, excavation surface support, and excavation strategy.</p>

<p> The Cuyuna Range is a former North American iron mining district about 90 miles(145 kilometers) west of Duluth in central Minnesota. The district was the furthest south and west of the three Minnesota iron ranges (Vermilion, Mesabi, and Cuyuna). In 2011, Students and staff from Michigan Technological University's Department of Social Sciences were asked to identify and promote features of the Cuyuna Range's mining heritage. Methods and approaches of mulitsited archaeology were used to unify the diverse places and themes into a more cohesive narrative. Their investigations focused on sites of technological innovation, social conflict, and important people. One collaborative project involved training a team of local volunteers to survey seven iron mining communities to identify sites with historic importance. In total, 876 sites were documented. The data generated from this effort can be used to develop plans for cultural tourism focused on the iron mining heritage of the Cuyuna Iron Range. It was found that using multiple themes from multisited archaeology strengthened the region&rsquo;s narrative better than simply focusing on sites from a single thematic viewpoint</p>

The research is directed towards modelling the chiller set, the heat rejection and the load subsystems of a complete mine refrigeration system and simulating the performance in order that the design can be optimised and the most cost effective control system determined. The refrigeration load profile for a mechanised mine is complex and primarily a function of surface climatic variations, the strongly cyclic sources of heat resulting from the operation of diesel powered mining equipment and the associated differences in thermal environmental acceptance criteria. Modelling of the central element of the system, the compressor, is based on empirical relationships which use the actual cooling duty and input power rather than general compressor curves using theoretical flow and head coefficients. This has a more general application and is not restricted to a single compressor type. The steady state modelling of five refrigeration systems has included two types of compressor, four types of evaporator, three types of condenser, two types of cooling tower and five types of mine cooling appliances. The research has extended modelling of refrigeration systems by incorporating fully the heat rejection and load subsystems and has demonstrated that relatively complex mine refrigeration systems can be modelled and the simulation results related to actual measurements with an acceptable accuracy. This has been further improved by testing the system elements and adjusting the theoretical performance analysis where necessary. These adjustments concern either the more difficult to assess factors such as evaporating and condensing heat transfer coefficients or factors influenced by unusual operating conditions. The research has shown that, despite the complexity of the load profile and the refrigeration system, modelling and simulation can be used effectively to optimise both the design and the control system.

The current trends towards increased coal production from seams at greater depth has led to increased demands being placed on the methane drainage and mine ventilation systems. This study has been directed towards the development of computer models to simulate and analyse the gas flows in methane drainage ranges and the airflow and pressure distribution in mine ventilation networks. The first part of this thesis describes the conventional techniques of methane drainage currently employed and the mathematical approach used to model gas flow in the methane drainage range. It also discusses how, when combined with measured underground data, predicted results can be used to assess the performance of the range. Subsequent analysis techniques will suggest measures that can be undertaken to optimise this performance and assess the effect of selective network reconfiguration. The second part of the thesis includes a discussion of the increasing application of booster fans in U.K. underground coal mines and a critical analysis of the mathematical methods used to model airflow and pressure distribution in mine ventilation networks. One particular method was adopted in a simulation model used to analyse networks with booster fans and specified face airflows. Both simulation models developed have been used to analyse representative underground methane drainage ranges and mine ventilation networks. The thesis concludes that the accuracy of the methane drainage models can only be guaranteed when developed in conjunction with suitable measured data. The mine ventilation model requires user guidance through the solution and analysis procedure. Results are presented in a simple graphical manner and this approach, rather than the 'black box' non interactive approach, is to be favoured in the analysis of mine ventilation networks.

Geologic information extraction and integration are the main goals of this study. Tools are designed to aid in exploration for common mineral deposits by intelligently and efficiently processing spatial geological data. Gabor filters, comprising Gaussian-attenuated sinusoidal weight vectors, are used for textural discrimination. A highly non-linear logic operator was designed for "valley", "ridge", edge, and intersection extraction from multispectral images to cover most of the possible local lineament types. A zonation detector (a non-linear logic operator) indicates the presence or absence of lithologic zonation, the number and the types of zones using a series of automatically expanding moving windows. The ultimate window size represents the zonation size. Two different types of raster-based expert systems help optimize pixel-by-pixel knowledge extraction and representation over the spatial information and throughout the different raster feature layers. First a 2-D expert system is used for classification, ranking, recognition and searching for important pattern associations in the feature space. Second, a multilayer adaptive raster-based expert system allows the processing of multiple geologic features, and operates over each pattern in the feature layers. The fuzzy integral method of evidence fusion is used to integrate information from a variety of mineral exploration sources. This nonlinearly combines objective mineral occurrence evidence, in the form of a fuzzy membership function, with subjective evaluation of the worth of the sources with respect to the decision. An application of these methods to the Tombstone mineral district in southern Arizona demonstrates its ability to pick out circular features from TM imagery, Gabor transforms and lineament patterns, as well as identify favorable zonation for new mineral occurrence. The final product at this time is a probability map to guide the exploration geologist.

This dynamic study of investment under uncertainty reveals that conventional analyses of aluminum industry patterns of trade and investment may be based on industrial policy rather than competitive advantages. The study results confirm the hypothesis that, with competition and free trade, U.S. aluminum smelting investment (and capacity) does not decrease, rather it increases as capacity is lost by Pacific Basin (PB) and European (EUR) suppliers, both presently protected with high tariffs. Using a competitive market approach and rational expectations, firms are considered as taking current market prices and acting as if current output and investment decisions will not affect current or future prices. Fixed production proportions of input to output are assumed for all production stages, for efficient-sized plants. Dynamic elements are captured through frictions in adjustment of smelting capacity that restrict the capacity that can be added in a single period. Investment is irreversible except by depreciation. In the resultant expectations framework, supply and demand are not always in sync and random shifts in investment occur across different regions. Rational expectations allows equivalence between a competitive equilibrium and welfare optimization under uncertainty. The study here solves the simpler but equivalent welfare maximization problem. The pattern of investment under free trade shows that, though the Latin American (LA) and (PB) smelting regions have absolute advantages in smelter power costs (typically assumed the determining factor for new investment), total aluminum production costs (including bauxite and alumina) in the eastern U.S. and western North America (US-E and NA-W) are sufficiently below those of (EUR) and PB to maintain the former's competitive advantages. Using World Bank aluminum demand growth rates, US-E capacity increases by 28 percent and NA-W by 49 percent as EUR capacity falls by 22 percent and PB by 32 percent for the year 2010. The results differ markedly from conventional forecasts which have predicted declines in North American investment, inferring that barriers to free trade may be distorting investment patterns.