A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillnent of the requirements for the degree of Doctor of Philosophy, 1992 / The self-heating of coal is a problem which concerns the mining industry not only in South Africa, but also in many other countries. This thesis deals with the contouring of spontaneous combustion liabilities (WITS-ERAC index values) of different seams at the Durban Navigation Colliery and the relationship between the WITS-EHAC index values and the properties of the coal samples. In the determination of the spontaneous combustion liabilities 58 different coal samples were tested with an ignition-temperature test apparatus, crossing-point temperature tests and differential thermal analysis were conducted simultaneously. [Abbreviated abstract. Open document to view full version] / MT2017

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, for the Degree of Master of Science. / Storage and waste dumps from coal mining tend to spontaneously combust. This is mainly as a result of the oxidation process which is accelerated by the availability of oxygen and the exothermic nature of the oxidation process. In cases of poor ventilation the heat accumulation within the bed is thought to lead to the spontaneous combustion of coal. The work in this dissertation aims to investigate the change in oxygen concentration in a bed of coal and also measure the rate of oxidation (oxygen absorption) in a closed reactor under isothermal conditions. Drying rate of coal under nitrogen was also looked into. An analysis of the oxygen concentration profile in a three metre 20 cm ID plastic column filled up with coal has been carried out. As the coal ages (becomes oxidised) its reactivity towards oxygen decreases and changes in the oxygen concentration profile are noticed. Experiments have been carried out up to 8 months and from the results obtained, a simple pseudo-steady-state model has been developed to describe the diffusion of oxygen into a reacting coal bed. The findings could prove useful in trying to find a solution to coal and waste dump fire control. The second experiment is a simple isothermal oxygen absorption experiment in which the rate of absorption of oxygen on a given coal sample is measured at different initial concentrations of oxygen. The initial concentration of oxygen is varied over a fairly wide range in order to determine the dependence of the rate of oxidation on the oxygen concentration. The rate- limiting step in low temperature oxidation of coal is found to be the absorption of oxygen. Moisture also plays a role in coal oxidation. Drying experiments were also carried out so as to quantify and investigate the rate of loss of moisture. Models have been developed which try to explain tile mechanisms involved in the drying process. The modelling suggest that the bound water model is more appropriate to the type of behaviour exhibited during the drying process. / Andrew Chakane 2018

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / The quality and grade of South African coal is declining simultaneously with depleting seams. This has a negative impact on power generation and the economics of coal mining and power production. The reason is that good quality coal is more difficult to mine and hence costly, thus affecting coal prices and the ability of mines to supply coal quality of the required specifications. There is a global environmental awareness around the CO2 greenhouse gas and its effect on global warming. Legislations are becoming more stringent in limiting the amount of greenhouse gases and air pollutants we produce. In power generation, the most prominent greenhouse gas is carbon dioxide (CO2) and the most prominent air pollutants are oxides of Nitrogen and Sulphur (NOx and SOx). Oxy-fuel combustion (OFC) is a process change that can reduce the production of CO2 by increasing the concentration of oxygen in combusting air. A study is presented here, that focuses on the application of this process (OFC) to South African coals. Three different coal types were studied and characterized by conventional proximate and ultimate analyses and further characterized and graded by more specialized analyses; petrographic analyses and the quantitative evaluation of minerals b scanning electron microscopy (QEMSCAN). The gasification of the coals was then modeled to determine, qualitatively, its magnitude in comparison to combustion (oxidation) in oxy-fuel combustion. However, when modeling and conducting experiments to determine this, it was found that existing empirical formulae used to quantify char burnout are not suitable for all South African types of coal. The formulae found in literature (for both oxidation and gasification) could only be applied to two of the three samples. For the two samples that were successfully modeled, it was found that reactivity in gasification was probable but not to a significant level. For the third sample that couldn’t be modeled successfully, a recommendation was made that a new model be developed to take into account the nature of low grade, high inertinite South African coal. This is required in order to successfully formulate the char burnout of South African coals and thus depict with certainty, the applicability of Oxy-fuel combustion on South African coals. Such a step would benefit the forthcoming studies on modeling the char burnout of South African coal and therefore contribute to addressing the challenge of declining coal quality in South Africa. / MT2017

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, 2017 / Productivity is an important topic within the mining industry and advances in productivity open up opportunities to make the best possible use of South Africa’s mineral wealth. The report uses publicly available data to assess trends in productivity in the SA coal mining industry since the 1980s and to compare SA’s performance with that of the US and Australia. It is found that between 1980 and 2003, productivity growth in the SA coal mining sector was primarily driven by capital deepening. However, productivity growth has been negative from 2004 onwards, despite continued capital deepening. Possible explanations include resource depletion, investment lags, deteriorating worker quality, increased complexity, more stringent safety regulations and adverse labour market conditions. The report highlights skills development and investment in innovation as possible ways of addressing declining productivity performance in the SA coal mining sector and recommends improvements to the availability of data for productivity research purposes. / CK2018

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science in Engineering, 2016 / Previously undermined areas pose a significant challenge to mining by opencast due to the risk of sinkhole occurrence. In order to optimise reserve utilisation as well as safeguard personnel and equipment there was need to develop a “Sinkhole Prediction Model” to assist in the prediction of areas prone to sinkhole formation. The aim of this research therefore was to develop a “Sinkhole prediction tool” with a view to pre-identifying areas of potential sinkhole hazard to inform better controls to assist in mining these areas safely. This was done utilising the current Hill (1996) caving height method culminating in the development of a hazard index model dividing the mining zones into high and low hazard. These areas were colour coded Red (High hazard) and Green (Low Hazard). The “Sinkhole Prediction Model” evolved to include over hundred sinkhole incidences that were statistically analysed to firm up on the robustness of the Prediction Model capabilities. The Hill (1996) caving height formula was discounted after the statistical analysis indicated that a good prediction model lies in the interrogation of site specific data. The outcome of the work conducted in this research report indicated a 97% correlation between the refined “Sinkhole Prediction Model” and the actual sinkhole occurrence at the Anglo American case study area (Mine X). Various refinements inclusive of lithological assessments, blast and drilling reconciliations as well as the implementation of the roughening up quality audits led to the implementation of a robust sinkhole management process that has managed to consistently assist in safeguarding equipment and personnel thus allowing for coal extraction optimisation in areas that could have been written off due to the sinkhole hazard. This risk can only be eliminated by mining the areas with the sinkhole risk. Currently the method is being impacted by significant roughening up cost incurred in a drive to make the areas safe to allow for coal extraction. The roughening up process on average costs R3.5 million per sinkhole and is a function of the number of sinkholes found, which translates to an equivalent cost of R7 / sales tonne. The current sinkhole prediction model being employed in deficient in that it cannot pinpoint the actual location of the void in the area previously undermined by bord and pillar and this is a great limitation of this report. Various geophysical techniques were pursued to assist in the precise identification of the actual sinkhole spatially. This process was aimed to reduce the roughening up cost (entire block stabilisation) as opposed to targeted sinkhole excavation and stabilisation. This process proved futile as the void identification systems are highly incapable of identifying the voids / iv sinkholes spatially (x, y and z coordinates) to assist targeted sinkhole treatment as a result of the following:  System inability to penetrate areas comprised of highly conductive strata such as clays.  Inability to distinguish between the underground voids and geological anomalies such as dykes.  Not suitable for penetrating wet strata.  Impacted by noise interference from mining machinery. The major result of this research is the establishment of a site specific “Sinkhole Prediction Model” that can generate hazard plans in real time thus informing the management on areas associated with a potential sinkhole hazard. The hazard plans can be generated timely and decisions made to facilitate safe coal extraction in areas of high sinkhole hazard. This has culminated in a robust sinkhole management process within the group that has managed to eliminate the risk of personnel and equipment exposure at Mine X. The roughening up process is accepted as the primary sinkhole mitigation or rehabilitation process with the need to work towards reducing the roughening up costs through development of the tool capable of precisely identifying the voids routinely to facilitate targeted rehabilitation. Significant research is required in this area as the mining environment is comprised of strata that currently cannot support the use of real time void identification to facilitate targeted void identification and rehabilitation. There is also merit in the future to formulate the database capable of assisting in the prediction of sinkholes in the Witbank coalfield as well as assist in robust management of mining boundaries across the different mining houses. The system implemented at Mine X is currently being deployed to other operations in the group where modification will be made to match the site specific conditions. Future research into understanding the sinkhole occurrence dynamics is quite crucial if targeted rehabilitation is to be achieved for cost reduction and mining sustainability. A combination of the understanding of the sinkhole occurrence driving mechanisms in conjunction with use of modelling packages such as ELFEN (a hybrid Modelling) tool will go a long way in enhancing the development of precise sinkhole prediction point in space.

Thesis (M.S.)--Massachusetts Institute of Technology, Alfred P. Sloan School of Management, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY. / Includes bibliographical references. / by Mauricio Sancho Obregón. / M.S.

Thesis (Ph. D.)--State University of New York at Binghamton, Anthropology, 2006. / Includes bibliographical references.

Today, solid waste management in coal mines is an urgent requirement for the coal mining industry. The overlying materials removed from a seam of coal are solid wastes transported to dumping sites and should be strictly, efficiently managed and monitored by an automatic system. These wastes must be separated for use as leveling and filling materials or residue materials need to be processed in order to minimize the impact on the environment. The system was designed to manage and monitor vehicles transporting solid waste in open coal mines to force them in tasks of taking solid wastes and giving out these wastes in the right places, to help collect and process suitably. The results showed that the calculation of numbers of trips using the software program named "Management of trucks" achieved the statistics of running trucks between the points of removing wastes and dumping sites, in which the numbers of valid and invalid trips were given out. The monitoring process obtained the statistics of active and inactive total time of vehicles transporting solid waste. From that we can calculate and classify them at each dumping site. In addition, the statistics of productivity of power-shovels, fuel consumption levels of excavators and trucks were also gained. / Hiện nay quản lý chất thải rắn tại các mỏ than là một yêu cầu cấp bách đối với ngành khai thác than. Các chất thải khi bóc vỉa được chở đến các bãi đổ cần có một hệ thống quản lý giám sát chặt chẽ. Những chất thải này phải được phân loại để làm vật liệu san lấp hoặc vật liệu cần xử lý nhằm giảm thiểu các tác động tới môi trường. Hệ thống được thiết kế có nhiệm vụ quản lý và giám sát các xe chở chất thải trong quá trình khai thác tại các mỏ lộ thiên, đảm bảo các phương tiện này được xúc và đổ đúng nơi quy định, giúp thu gom, xử lý một cách phù hợp. Kết quả cho thấy rằng việc tính toán số lượng các chuyến xe bằng cách sử dụng chương trình phần mềm có tên là "Quản lý xe tải" thu được các số liệu thống kê xe chạy giữa các điểm xúc chất thải và các điểm đổ, trong đó thống kê được số lượng các chuyến đi hợp lệ và không hợp lệ. Quá trình giám sát thu được các số liệu thống kê của tổng thời gian hoạt động và không hoạt động của các phương tiện vận chuyển chất thải rắn. Từ đó chúng tôi có thể tính toán và phân loại chúng ở mỗi điểm đổ chất thải. Ngoài ra, cũng thu được các số liệu thống kê năng suất hoạt động của máy xúc, mức tiêu thụ nhiên liệu của máy xúc và xe tải.

Thesis (M.S.)--Ohio University, November, 2009. / Title from PDF t.p. Includes bibliographical references.

Thesis (MS)--University of Montana, 2009. / Contents viewed on January 15, 2010. Title from author supplied metadata.