Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Wollongong, 2001. / Typescript. Bibliographical references: leaf 218-232.

Thesis (M.Phil.)--University of Hong Kong, 1982. / Also available in print.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1947. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed July 9, 2010) Includes bibliographical references (p. 48).

Thesis (M.S. in environmental science)--Washington State University, August 2007. / Includes bibliographical references (p. 19).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 65 p. : ill., maps (part col.). Includes abstract. Includes bibliographical references.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed May 22, 2007). PDF text:xviii, 204 p. : ill. (some col.) ; 2.37Mb UMI publication number: AAT 3237050. Includes bibliographical references. Also available in microfilm and microfiche formats.

M.Phil. / Pulleys are critical items in belt conveyors. Their primary role is to drive large mining conveyor systems, facilitating the transportation of ore over extensive distances, both in South Africa and abroad. The effect of the manufacturing process (with specific emphasis on the induced residual stresses) on the fatigue performance of conveyor pulleys is herein investigated and reported. A pre-selected pulley was chosen based on size, suitable for experimental work as well as practical specifications. The static and fatigue performance of the pulley were investigated both with the current design criteria as well as Finite Element Analysis, with comparisons drawn. The material data for the Finite Element Models was obtained experimentally with tensile tests of the SANS 1431 350 WA plate. The magnitude of the residual stresses were obtained experimentally by using the incremental hole-drilling technique for non-uniform residual stresses. The method was verified by comparison with the Finite Element Analysis results for the non-linear material analysis of the roll-bending of the shell. The fatigue analysis revealed that the stress ranges of interest for the pulley were below the non-propagating stress range, and hence theoretically infinite fatigue life would be possible under constant amplitude conditions. The operational fatigue life required for the pulley would be possible, when considering the latest S-N curve for "very high cycle fatigue". The stress intensity factors for the weld details were also below the threshold value and hence crack growth should not occur, upon crack initiation. A new design criteria was proposed for the fatigue analysis considering either fatigue assessment standards or fracture mechanics for the assessment of the butt-welds. This investigation showed that the manufacturing-induced residual stresses may play a significant role in the fatigue life of a pulley. The fatigue strength of a machined stressrelieved joint is higher if the stress range is partly compressive. The fatigue strength of a machined as-welded joint is higher than estimated by the fatigue classifications. This is due to residual stress relaxation that occurs at the weld toe because of yielding and hence a subsequent reduction and redistribution of the residual stresses. This reduction in the mean stress level, with a stress range that is partly compressive, would mean an increase in the fatigue strength of the joint. This would in conclusion result in similar fatigue strengths for a stress-relieved and an aswelded joint. This would additionally depend on the extent of the reduction of the residual stress in the as-welded joint. Recommendations were suggested for further experimental and numerical work for both the T-bottom and Turbine-type pulleys.

An advanced coursework and a project submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements of MSc. Engineering (Mining), November 2015 / General For mining operations, both underground and open cast, there are generally accepted criteria used to arrive at the optimum mining method with which to exploit the ore body economically. Having selected the optimum mining method, mining companies should then make the decision to also select the optimum technology to apply given the various options that are now available. In the case of a shallow massive ore body where open-pit mining has been selected as the optimum mining method, the use of conventional trucks and shovels has been the popular choice but over the years, as pit become deeper, and stripping ratios increase, growing interest and adoption of in-pit crushing and conveying for both ore and waste has been gaining ground with several mining sites currently now operating, testing the systems or conducting studies at various stages for In-pit Crushing and Conveying (IPCC) in its different configurations (Chadwick, 2010). Open pit mining general involves the movement of pre-blasted or loose waste ahead of underlying ore out of the pit or to a previously mined part of the pit. This is then followed by the drilling and blasting or loosening of the ore and transportation to the processing plant or stockpiles. The conventional Truck and Shovel open pit operation involves the use of shovels – electric rope shovels, diesel or electric hydraulic shovels or excavators or front-end loaders to load the blasted, or loose waste and ore material in the pit onto mining trucks which haul the material to crushers or stockpiles if it is ore or to waste dumps in the case of waste. In a Fully Mobile IPCC (FMIPCC) system, the broken or loose material in the pit is loaded into a crusher or sizer by a shovel, continuous miner or dozer, crushed to a manageable size and transported by conveyor belts to the waste dump where it is deposited in place using spreaders if it is waste or onto stockpiles if it is ore. A combination of the two systems is where trucks dump material loaded at the face into a semi mobile crusher or sizer located in the pit close to the loading points N BANDA 392438 before conveying to destination thereby reducing truck haulage distance. In the semi-mobile configuration, the crusher is relocated closer to the loading points to minimise the hauling distance. Other various configurations are also employed depending on the various considerations. Although the Truck and Shovel system is considered as the convention in open pit mining, the IPCC system is not a new concept and has been operational on a number of mines worldwide for quite a number of years (Szalanski, 2010). Loading and hauling receive great attention especially in a high volume open pit mines due to the high cost contribution to the overall operation and therefore, if optimised, good cost savings can be realised (Lamb, 2010). Figure 1: Sishen Mining Cost Breakdown In the case of Sishen Loading and Hauling costs constituted 67% of the mining costs including labour mining support services in 2013 (Kumba Iron Ore, 2013). This picture remains unchanged to a large extent. In some cases the hauling cost alone can make up as much as 60% of the mining operating cost (Meredith May, 2012) Selection of a materials handling system between Truck and Shovel (T/S) and In-pit Crushing and Conveying (IPCC) has proven to be difficult due to limited understanding of the IPCC system especially its advantages and disadvantages relative to the Truck and Shovel system. The aim of this research was to unpack these two systems in terms of their applicability using studies conducted at Sishen 6,5% 8,8% 29,1% 22,7% 9,7% 0,6% 1,3% 0,4% 7,0% 4,2% 3,7% 5,9% Sishen Mining Cost 2013 Blasting Drilling Hauling L&H Contractors Loading Maintenance Other Mining Manangement Mining Engineering Mining Other Resource Management SHEQ Mining Support N BANDA 392438 Mine as well as develop some scorecard that could be used to select one over the other one. Sishen Case Study Sishen Mine is an iron ore open pit mine located in the Northern Cape province of South Africa and is part of Kumba Iron Ore Company which is Anglo American PLC. The mine has been in operation since 1953 with the current life of mine going up to 2030. It produces 44Mt tonnes of product from a 56Mt mine ore at a life of mine strip ratio of 4. One of the planned expansion the north part of the mine known as the GR80 and GR50 areas. Mining in these areas will require pre-stripping of 290Mt of clay material over the life of mine to expose the ore in pre volume phases. Figure2: Sishen Pit –Sishen Mine 2014. Sishen mine is constantly evaluating various technologies in its mining operations aimed at improving its bottom line by way of increasing productivity and efficiency, reducing costs and improving safety, however, the last time that the mine considered evaluating a technology that significantly could have resulted in a totally different operational philosophy was i contracted to institute a study to evaluate technology options for mining and moving majority owned by a minimum of 437Mt of calcrete and the underlying pre- g in 2007 when Snowden Mining Consultants run-ofmine areas is in -planned time and were N BANDA 392438 55 Mt of the calcrete/clay material per year from the waste pushback area in the GR80/GR50 area of the mine from 2009 till 2030. Snowden completed the Prefeasibility study in early 2008 in which they evaluated a conventional Truck and Shovel operation as well as IPCC. Economic viability of both systems in various configurations was demonstrated with the use of larger trucks and shovels ranked as the most economic option in terms of Net Present Cost (NPC), unit owning and operating cost per mined tonne and, to a less extent, in terms of risk and other considerations. In this case, the Truck and Shovel option was more economic than both IPCC configurations. However the small difference in the cost figures gave rise to interest in further evaluations. Following the Snowden study, Sishen engaged Sandvik Mining and Construction in 2008, to review the work done by Snowden and provide more detail and practical input to the IPCC system at scoping level. In the review, the IPCC system was shown to be the economic approach for the waste removal from the target area in terms of owning and operating cost. Practicality was also demonstrated and the case for the consideration of the IPCC system was put forward to Sishen. A further consultant, Sinclair Knight Merz (SKM) of Australia, was engaged, in the later part of 2008, to further evaluate and optimise the IPCC option to further demonstrate practically in detail at a feasible study level and strengthen its case by mitigating perceived risk. This included equipment specifications, mine and equipment layout per period per bench and risk assessment on the IPCC options. The mine, however, implemented the conventional truck and shovel option using larger equipment. The final decision was to stick with the current set up of Truck and Shovel system and gradually replace the current fleet of 730E Komatsu (190 tonne payload) trucks with the 930E or equivalent ( 320 tonne payload) and the current XPB 2300 P& H electric rope shovels and CAT 994/Komatsu WA1200 front end loaders with XPC 4100 P&H electric rope shovels, Komatsu PC8000/Liebherr 996 diesel hydraulic shovels and LeTournea L-2350 front end loaders to reduce the number of equipment and manage the operational cost. This decision was based on issues around initial capital investment, flexibility of the system to suit changing mining plans, ability of current personnel to run the system and general low risk appetite for change. The adopted option has its own challenges N BANDA 392438 such as supporting infrastructure requirements, labour intensity and associated low productivity and high cost, fleet management challenges to achieve required productivity constantly, supplies such as fuel and tyres and safety issues due to traffic density. A high level recalculation of the costs using current information was done as part of this research. For simplicity, no escalations or discounting were applied on future expenditure. The estimated unit owning and operating costs in 2014 terms for the study area were as follows:- Fully Mobile IPCC (FMIPCC) option ZAR 10.38/t, Semi Mobile IPCC (SMIPCC) option ZAR 13.12/t, Truck and Shovel option ZAR 15.80/t. The objective of this research is to use lessons from the Sishen case as well as other operations and gather expert views with the aim of establishing criteria that could be applied in a preliminary evaluation that would determine the suitability of either of the materials handling options. General Approach The costs were recalculated using as much current information as possible. Other considerations including advantages and disadvantages of either of the systems were examined in more detail, with real life examples examined where possible. This resulted in the establishment of generalized criteria for the selection of mining and transport technology for a large open pit mine with focus on conventional Truck and Shovel systems on one hand and IPCC systems, in their various formats, on the other. These criteria which identify conditions necessary for the successful adoption and implementation of either of the systems could then be used as input into the decision to carry out any further detailed studies of the options. The previous study reports on the Sishen mine case were examined, input parameters to the calculations checked and the general approached analyzed for practicality. The relative costs were also viewed for comparative purposes. Literature on these two main systems was reviewed including that from conferences. Other large operations running either one or both systems were looked at to gain N BANDA 392438 further insight. Original Equipment suppliers’ views on these systems were also looked at through many articles in the public domain. Sishen mine has previously had the IPCC system running in the same part of the mine in a semi mobile configuration, crushing and conveying waste. It was then changed to become a supplementary system for the ore handling system and the in pit crusher has never been relocated. The Truck and Shovel system took over the movement of all the waste and most of the ore at the mine. Lessons from these experiences were incorporated in this study.

Margins in defect assessment procedures such as BS 7910 and R6/4 have been examined for cleavage and ductile tearing from complex and re-characterised defects. A range of crack profiles with re-entrant sectors developed from two co-planar surface breaking defects by fatigue has been examined experimentally and numerically. Both studies show enhanced crack driving forces in the re-entrant sector combined with a loss of crack tip constraint. Cleavage failures from complex and re-characterised defects demonstrated that the re-characterisation procedure is not conservative when cleavage occurs at small fractions of the limit load. Failures close to the limit load benefit from constraint loss which counteract the amplified crack driving forces in re-entrant sectors and cause re-characterised defects to be more detrimental than the original complex defects. Benefit may be taken from statistical size effects, which are strongly dependent on the crack geometry. Experimental fatigue and ductile tearing studies show similar development of complex cracks towards the re-characterised shape and re-characterisation procedures, such as those given in BS 7910 and R6/4, are conservative for fatigue and ductile tearing. A procedure has been developed to quantify enhanced temperature margins due to constraint loss by comparing the self similar stress fields at a critical local fracture stress (the Ritchie-Knott-Rice approach) and through the Weibull stress. Agreement with the experimental data has been demonstrated and the temperature dependence of the material parameters has been discussed. Following Li (1997) and Karstensen (1996), a toughness mapping technique was discussed that allows mode I toughness to be translated into mixed-mode I+II toughness for stress controlled fracture. In support of the arguments, toughness of Mode I and mixed-mode I+II configurations was measured on a mild steel. The experimental data clearly show increased cleavage toughness for unconstrained mode I and mixed-mode fields and the correlation with the predictions from the numerical models was demonstrated.