M.Sc. / The Dabolava region is an area of approximately 600 km2 and is situated on the western edge of the Precambrian in west-central Madagascar. The geology mainly consists of Proterozoic amphibolite facies metavolcanic rocks, inter-layered with minor metasedimentary rocks, crosscut by granodioritic to gabbroic plutons. The country rocks of the granodiorite and gabbroic plutons are composed of 50% amphibolites, 30% quartzofeldspathic gneisses and 20% metasedimentary rocks, mainly carbonates. The amphibolites consist dominantly of hornblende with plagioclase and minor quartz groundmass, although orthopyroxene, clinopyroxene, chlorite, and biotite are present in certain samples. They have tholeiitic affinities and may have been derived from basaltic lavas. They contain felsic segregations of tonalitic composition that possibly represent migmatitic leucosomes, with hornblende concentrated in associated melanosomes. The amphibolites are highly deformed compared to the plutonic rocks. Meta-quartzofeldspathic rocks of dominant rhyolitic compositions are interlayered within the amphibolites; these may represent felsic volcanics coeval with the metabasalt. Metamorphosed carbonates are also interlayered within the amphibolites. This assemblage of supracrustal rocks is intruded by Neoproterozoic granitoid and gabbroic plutons, and granodiorite dykes. The composition of the majority of the plutons in the area of study is mainly granodioritic, with minor quartz diorite and quartz monzodiorite. They are metaluminous and contain quartz, plagioclase, with minor K-feldspar (microcline); biotite and hornblende constitute the ferromagnesian minerals. The granodiorites have a prominent foliation defined by biotite and hornblende. According to their chemical and mineralogical composition, the granodiorites are classified as I-type in origin. Gold mineralization is associated with the Neoproterozoic granodiorite plutons, mainly the Dabolava and the Ambatomiefy plutons. It is hosted within quartz veins that are generally oriented parallel to the foliation of the host rock. A limited degree of alteration is observed within the granodiorite, with the alteration assemblages consisting of biotite, pseudomorphic chlorite, calcite, and sericite. Gold is associated with hydrothermal biotite and sulphide assemblages consist of pyrrhotite, arsenopyrite with minor pyrite and chalcopyrite, magnetite and ilmenite. The chemistry of analysed gold grains from the Dabolava pluton shows that they mainly consist of 95-97% gold with the remainder composed of Ag, Hg and Cu. A gold concentration of up to 2232 ppm was observed in one of the gold excavations within the Ambatomiefy pluton. Microthermometric studies reveal three fluid types, including a high salinity fluid (type 4), a CO2-rich fluid (type 1-a), and an aqueous type (type 3). It is suggested that the CO2-rich and high salinity fluids were exsolved from the magma. With decreasing temperature a low salinity CO2-H2O-NaCl fluid (type 1-b, type 2) (Th ranges from ~ 220-350° C) resulted from heterogeneous mixting of a CO2-rich fluid and a low salinity aqueous fluid. Therefore, fluid inclusion studies indicate a magmatic origin of the mineralizing fluid(s). A porphyry-type deposit is suggested for the gold mineralization in the study area, as it is associated with I-type granitoid plutons, the mineralizing fluid (s) are of magmatic origin, and gold is associated with chalcopyrite, albeit in minor amounts. Based on the rock associations observed in the field, which consist of metabasalts interlayered with minor coeval metarhyolite, with associated intrusive plutonic rocks, as well as trace element discrimination diagrams, an active continental margin tectonic setting is inferred for the rocks in the study area. Two samples from the granodiorite plutons and one sample from a gabbro body were dated using U-Pb single zircon geochronology. A sample from the Ambatomiefy pluton yielded an age of ~1002±3 Ma, which is interpreted to represent the crystallization age of the pluton. The Dabolava pluton has also been dated, and a similar age of 1008 Ma has been obtained. A gabbro sample from a smaller mafic body in the area has been dated at 982±2 Ma. This defines a ~26 m.y. period of Neoproterozoic magmatic activity. An age of 982.3±2 .9 was also reported from a gabbro body located in the southern part of Madagascar (Amborompotsy-Ikalamavony). These provide evidence of the presence of 1000 Ma magmatic activity in Madagascar. The extent and the significance of this magmatic event are not yet understood although it could be related to the Mesoproterozoic event associated with the assembly of the supercontinent Rodinia. The identification of granitoids of similar age and character in Madagascar and within Gondwana has economic significance regarding the potential of these granitoids for porphyry-type gold mineralization. Therefore, this is useful for future gold exploration.

Scattered mining was practised on Kusasalethu Mine (previously Elandsrand Gold Mine) prior to 1998, but as mining proceeded deeper, it was no longer a feasible option. The scattered mining method would have resulted in unacceptably high stress levels and energy release rates on the active mining faces. Longwall mining was considered as it was practiced on neighbouring mines. This would have ensured that energy and stress levels remained within acceptable limits and avoided the formation of remnants at depth. Kusasalethu Mine required a more flexible mining method owing to the highly variable grade, the presence of multiple faults and dykes and the high production rate required. A mining method was therefore developed that consisted of dip stabilizing pillars for regional support as well as bracket pillars to support geological structures. This was called the Sequential Grid mining method. Sequential Grid mining addressed two main problems, namely, negotiating the adverse geology and the erratic grade of the VCR orebody. However, a recent drop in production resulted in the need for alternatives and improvements to the original mining layout. This involved modifications to the design in order to increase production rates without any compromise to safety. An investigation to modify for the Sequential Grid mining method was therefore conducted by the author in order to determine the consequences for layout stability. A few alternatives were investigated to determine the best possible solution for the Sequential Grid design. As a result, the modified Multi-raise mining method was introduced to address the problems that were experienced with the original design. This study compared the original mining method and the Multi-raise mining with regards to layout stability. Investigation of the seismic data showed no significant differences between the original Sequential Grid mining and the proposed Multi-raise mining. The numerical modelling of the mining layouts showed slightly higher interim Energy Release Rates (ERR) and Average Pillar Stress (APS) levels during the extraction process. The final values for these parameters are nevertheless similar to the original Sequential Grid mining method. It is therefore concluded that the Multi-raise mining method will not have adverse effects on the mine stability. It is concluded that changes to the original Sequential Grid mine design are possible without influencing the seismic hazard. In addition the anticipated interim increases in ERR and APS levels could be kept within acceptable levels through slight decreases to the extraction ratio. The concept of an average value for the stress distribution in a remaining portion of solid rock (pillars) surrounded by underground mining excavations is used as the rock engineering design parameter called average pillar stress (APS). Although averages are generally simple to calculate given the availability of appropriate data, average values for the stress distributed with pillars is somewhat more complex especially when working in MINSIM 2000 is proposed to ensure that the calculation of APS is done appropriately. The study also investigated the use of the Modelled magnitude method to analyse future seismic trends. The study illustrated that the expected seismic trends will be very similar for the Multi-raise method compared to the original Sequential Grid mining method. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Mining Engineering / unrestricted

An ever-expanding global industry focuses attention on energy supply and use. Cost-effective electrical energy production and reduced consumption pave the way for this expansion. Eskom’s demand-side management (DSM) initiative provides the opportunity for reduced electricity consumption with cost-effective implementation for their respective clients. South African gold mines have to extend their operations to up to 4000 m below the surface to maintain profitable operations. Deep-level mining therefore requires large and energy-intensive cooling installations to provide safe working conditions. These installations generally consist of industrial chillers, cooling towers, bulk air coolers and water transport systems. All of these components operate in unison to provide chilled service water and cooled ventilation air underground. In this study the improved energy efficiency and control of a South African gold mine’s cooling plant is investigated. The plant is separated into a primary and secondary cooling load, resulting in a cascading cooling system. Necessary research was conducted to determine the optimal solution to improve the plant’s performance and electrical energy usage. Variable speed drives (VSD) were installed on the chiller evaporator and condenser water pumps to provide variable flow control of the water through the chillers, resulting in reduced motor electricity usage. Potential electricity savings were simulated. Proposed savings were estimated at 600 kW (13.6%) daily, with an expected saving of R 2 275 000 yearly, resulting in a payback period of less than 9 months. Results indicated are based on total savings, as VSD savings and control savings were combined. The VSDs that were installed, were controlled according to an optimum simulation model’s philosophy. A real-time energy management program was used to control the VSDs and monitor the respective systems. The program’s remote capabilities allow for off-site monitoring and control adjustments. A control strategy, which was implemented using the management program, is discussed. Energy efficiency was achieved through the respective installations and control improvements. The results were analysed over an assessment period of three months to determine the viability of the intervention. A newly installed Bulk Air Cooler (BAC) added to the service delivery of the cooling plant post installation of the VSDs. Focusing on service delivery to underground showed a savings of 1.7 MW (33.6%) daily and a payback period of 3.6 months (0.3 years). The overall implementation showed an average energy saving of 2.3 MW (47.1%) daily, with the result that a daily saving of R 23 988.20 was experienced, reducing the payback period to 2.3 months (0.2 years). Through the installation of energy-efficiency technology and a suitable control philosophy, a cost-effective, energy-efficiency improvement was created on the case-study cooling plant. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

An ever-expanding global industry focuses attention on energy supply and use. Cost-effective electrical energy production and reduced consumption pave the way for this expansion. Eskom’s demand-side management (DSM) initiative provides the opportunity for reduced electricity consumption with cost-effective implementation for their respective clients. South African gold mines have to extend their operations to up to 4000 m below the surface to maintain profitable operations. Deep-level mining therefore requires large and energy-intensive cooling installations to provide safe working conditions. These installations generally consist of industrial chillers, cooling towers, bulk air coolers and water transport systems. All of these components operate in unison to provide chilled service water and cooled ventilation air underground. In this study the improved energy efficiency and control of a South African gold mine’s cooling plant is investigated. The plant is separated into a primary and secondary cooling load, resulting in a cascading cooling system. Necessary research was conducted to determine the optimal solution to improve the plant’s performance and electrical energy usage. Variable speed drives (VSD) were installed on the chiller evaporator and condenser water pumps to provide variable flow control of the water through the chillers, resulting in reduced motor electricity usage. Potential electricity savings were simulated. Proposed savings were estimated at 600 kW (13.6%) daily, with an expected saving of R 2 275 000 yearly, resulting in a payback period of less than 9 months. Results indicated are based on total savings, as VSD savings and control savings were combined. The VSDs that were installed, were controlled according to an optimum simulation model’s philosophy. A real-time energy management program was used to control the VSDs and monitor the respective systems. The program’s remote capabilities allow for off-site monitoring and control adjustments. A control strategy, which was implemented using the management program, is discussed. Energy efficiency was achieved through the respective installations and control improvements. The results were analysed over an assessment period of three months to determine the viability of the intervention. A newly installed Bulk Air Cooler (BAC) added to the service delivery of the cooling plant post installation of the VSDs. Focusing on service delivery to underground showed a savings of 1.7 MW (33.6%) daily and a payback period of 3.6 months (0.3 years). The overall implementation showed an average energy saving of 2.3 MW (47.1%) daily, with the result that a daily saving of R 23 988.20 was experienced, reducing the payback period to 2.3 months (0.2 years). Through the installation of energy-efficiency technology and a suitable control philosophy, a cost-effective, energy-efficiency improvement was created on the case-study cooling plant. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Thesis (MSc (Earth Sciences))--Stellenbosch University, 2008. / Detailed geological mapping and a structural analysis of auriferous quartz veins were undertaken in the Karibib region of the Pan-African Damara belt in central Namibia. The study focuses on the formation and controls of quartz-vein sets and associated lodegold mineralization in heterogeneous, siliciclastic- and marble- dominated amphibolitefacies host rocks around the Navachab gold mine and adjacent areas. Two main arrays of shallowly-dipping quartz veins can be distinguished that form a conjugate set. Steep, bedding-parallel and high-angle cross-cutting veins also occur, but play a subordinate role for mineralization. The orientation of the main conjugate set and progressive deformation of these quartz veins indicate that veining occurred during the late stages of the main phase of NW-SE directed, subhorizontal shortening (D2) and associated NW-verging folding and top-to-the-NW thrusting. Cross-cutting relationships with plutonic rocks indicate a timing of ca. 540 Ma for the mineralization. The quartz veins sets show a consistent orientation irrespective of their location with respect to NE-trending, NW-verging first-order fold structures that were previously considered to be pertinent for the mineralization. The quartz vein sets also cross-cut different lithologies at high angles. This suggests that the regional strain (D2) was the first-order control of quartz vein formation. More localized lithological and/or structural controls played, however, an important factor for the formation of economicgrade mineralization. Thick and closely spaced quartz veins in steeply dipping rocks of the Navachab open pit form a more than 150m thick economic-grade vein swarm. In this structural situation and during layer-normal subhorizontal shortening, the host rocks experienced high extensional strains in a vertical direction, favouring the formation of subhorizontal extension fractures.

M.Sc. / Doornfontein Gold Mine is the westernmost member of a group of mines in the West Wits Line, extending from Westonaria to Carletonville. A study of the sedimentology and gold distribution of the Middelvlei Reef was carried out with the aim to acquire an understanding of the processes responsible for the economic concentration of gold ...

Thesis ((M.Sc.) Engin))--University of the Witwatersrand, Faculty of Engineering & the Built Environment, School of Mining Engineering, 2003. / The ore reserves of the Kloof Sub Vertical Shaft operations are coming to an end and as such, the Eastern Boundary Area mining operations, which will extract the Ventersdorp Contact Reef ("VCR"), must be commissioned to replace the diminishing reserves. Although feasibility studies have been carried out on the eastern portion of the Kloof Gold Mine lease area, none have been undertaken to investigate the potential benefits of including the new mineral rights recently acquired from JCI. This project report is a prefeasibility study into the potential value to Kloof of accessing and extracting the resources of the Eastern Boundary Area. This project report shows, using DCF analysis, that the Eastern Boundary Area has potential to economically generate the additional reserves that will be required to supplement Kloof s diminishing Three Shaft reserves. An NPV and IRR are calculated for the project, the results of which support the commissioning of further investigative work in order to obtain a better understanding of the orebody and to generate results that are more accurate. Despite its popularity, traditional DCF analysis has fundamental shortcomings, as do the commonly associated measures of NPV and IRR. This project report identifies and reviews these shortfalls and comments on methods to overcome these as far as practically possible.

No description available.

Abstract Background: The high prevalence of smoking on the mines contributes significantly to the public health burden due to exposure to crystalline silica dust and high HIV and TB prevalence rates. Progressive anti-tobacco legislation that informs workplace smoking policies is in existence but there are no formal smoking interventions to achieve the objectives of such policies and to facilitate health promotion. Health care workers, in particular have a vital role to play in this regard. Objectives: The objectives of this research study were to determine the knowledge, attitudes and practices of HCWs regarding prevention of smoking in gold mine workers and to use this information to propose a framework for a smoking intervention programme for the mines. Methods: This was a cross-sectional descriptive knowledge, attitudes and practice (KAP) study. Data were obtained from 69 HCWs using self-administered questionnaires, from 161 occupational lung disease (OLD) and 30 medical ward admission record reviews, and from 4 informal discussions. Results: While knowledge and attitudes about smoking was good overall and 84.1% of HCWs reported that they would routinely ask smoking status and document it, this was not done in practice. An overwhelming majority of HCWs are aware that smoking is harmful to one’s health (98.6%); is harmful to mine workers’ health (97.1%), and predisposes them to acquiring lung diseases (95.7%). Half (56.7%) of the nurses, but no doctors documented smoking history on admission and poor follow up of this advice (38.5%) is an area of concern. HCWs identified a need for support structures such as workplace and community programmes that include education, training and awareness campaigns. Conclusion: Overall, HCWS are responsive to workplace smoking interventions: they are knowledgeable, and show insight and have positive attitudes towards smoking interventions, but a more enabling environment is required to establish good workplace practices. To this end a “Proposed framework for smoking interventions on the mines, incorporating the HCW programme” has been developed and partially implemented. Awareness of this study and its preliminary findings has already demonstrated a paradigm shift in thinking about tobacco on the gold mines.

South Africa is one of the world's foremost mining nations and mining and its associated industries continue to form the cornerstone of the country's economy. However, the mining industry has, by its very nature, the potential to endanger human health and safety, as well as the physical environment. Consequently, mining will always contend with major environmental challenges and remain under constant public pressure to demonstrate its commitment to responsible environmental management. The key to effective environmental management is the use of a systematic approach to plan, control and improve environmental efforts. An Environmental Management System (EMS) employs such an approach and allows organisations to address environmental concerns in an orderly and consistent manner. Such a system allows organisations to anticipate and meet their environmental objectives and to ensure ongoing compliance with national and/or international requirements. An organisation with no existing EMS should, initially, establish its current position with regard to the environment by means of an initial review process. The aim should be to consider all environmental aspects of the organisation as a basis for establishing the EMS. Although a few gold mines in South Africa have implemented an EMS, the question of which significant environmental aspects need to be managed in such a system at a deep level gold mine shaft, remains largely unanswered. This study endeavoured to provide answers to this question and develop a generic model for the initial review process of a deep level gold mine shaft. The development of such a model should facilitate the development and implementation of an EMS at such shafts, thereby contributing to reduce the environmental impact of gold mines. The research consisted of a literature review of national and international literature on the topic and a comparative empirical study, which evaluated the mining operations of two deep level gold mine shafts. Data collection and analysis was done according to the IS0 14015 guideline on the environmental assessment of sites and organisations. Other techniques used included business process analysis, the use of modified Leopoldt matrices and risk analysis to determine the significance of the environmental impacts and aspects. This study contributed to a generic model for the initial environmental review process that precedes the development of an EMS at deep level gold mine shafts through: developing a generic sub-model that can be used to determine the scope of any deep level gold mine shaft; identifying some of the significant environmental impacts and aspects of deep level gold mine shafts, as well as identifying some generic business activities that are potentially destructive and carry a high risk of causing significant negative environmental impacts. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2004.