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By A. Ennen, R. Wagner, B. Orberger, J. -M. Milazzo, N. Uhlmann, J. Banchet, J. Lucic, N. Wörlein, M. Firsching, J. L. Dubos, C. Bauer

The residues from mining and processing ores can often be considered as secondary raw materials. However, the material is only available in the form of fine particles (< 3 mm). In order to recycle these wastes, it is necessary to agglomerate it for transportation prior to reprocessing. The resulting agglomerates need to mechanically resist the stress of transportation and loading into the furnace. X-ray computed tomography (CT) is an established method for characterisation of internal structures in material science. This non-destructive technique can provide information on size and distribution of particles and grains. However, the information is not limited to the size, but also can yield structural features like orientation and position of cracks and fractures, which are important features indicating potential for deteriorating the agglomerates. Furthermore, deduced features such as contact conditions of inclusions or boundary surfaces can also be calculated. We studied binder-free tablets of manganese-oxyhydroxide, bentonite, kaolinite and slag powder using micro-CT. Inclusions of highly absorbing particles were identified using a watershed transformation with automatic segmentation by Otsu thresholding. Subsequently, the resulting data was analysed regarding their volume percentage, distribution in size and location within the sample. For the slag agglomerates, the volume fraction of iron could be determined. Furthermore, visible cracks were investigated with the goal to determine the long-term durability. It was shown that the data provided by micro-CT is reliable and helpful for the characterisation of industrial waste agglomerates. Keywords: X-ray, computed tomography, micro-CT, agglomerates, manganese fines, slags, kaolinite, bentonite

Jan 1, 2020

By T. R. Curr, W. A. Gericke, J. Basson

South Africa is a leading player in the international ferro alloys industry. Historical factors that have contributed to this dominant position include an abundance of natural resources and relatively low cost electricity. A number of relatively recent developments are potentially threatening this position. These include new legislation affecting the mining and minerals industry, a shortage of some types of suitable reductants, depletion of surplus electricity generation capacity with resultant threat of real escalation of electricity prices and pressure resulting from the recent strengthening of the South African Rand. The industry is addressing these challenges in a number of ways to ensure long-term viability. Some of these measures include investments in more efficient technologies that have economy of scale benefits and are less dependent on expensive reductants and electricity. Local macro-economic impacts include new legislation regarding ownership of enter-prises, mineral rights and royalties on mineral sales, development plans for port and rail infrastructure, as well as initiatives to expand electricity generation and coke production capacity. The fundamentals for being a successful ferro alloy producer are still largely in place for South African producers. Therefore the South African ferro alloy industry will remain competitive and is well placed for continued growth in line with the international growth in ferro alloy demand. The industry should emerge leaner, more efficient and ready to respond to any future demands of the industry. This paper will cover the present status of the industry, the factors that are impacting thereon and a view on its future outlook.

Jan 1, 2007

By M. Smit, N. C. J. Dempers, S. Lunkov, C. Saguru, J. Nel

A common method for the recovery of copper is by heap leaching, solvent extraction, and electrowinning. During solvent extraction, the solution is continuously recycled, and it is necessary to remove impurities that build up in the raffinate. For the process investigated in this study, the main impurities include Fe, Co, As, and Zn. Recovery of these impurities can provide economic benefits while adhering to legal and environmental constraints. Such impurities are often removed by precipitation utilizing a neutralizing agent, such as limestone or lime, but it is also possible to remove the impurities by sulfide precipitation. Sodium hydrosulfide (NaHS) is used to selectively precipitate copper, arsenic, and zinc from a solvent-extraction raffinate stream. The resulting sulfide precipitate is bagged and sent to a roaster for further treatment. The design of the sulfide precipitation was investigated to optimize the processing conditions (including temperature, pressure, and residence time), the materials of construction, and the toxicity and explosive nature of the hydrogen sulfide gas produced

Jan 1, 2023

"Chairman: Dr W. S. RAPSON Rapporteur: Mr J. W. WILSONPapers:Computer applications in rock mechanics by F. H. Deist, E. Georgiadis and J. P. E. Moris Rock mechanics in the design of mine layouts by K. Hodgson and N. G. W. Cook Automated regulation of mine ventilation by P. NiskanenThe rock mechanics papers, because of their complementary nature, were presented in succession and discussion on both followed directly. The paper on automated ventilation control at a mine in Finland was then presented and the session was closed with several contributions to this paper.By and large the papers and discussions which followed in this session showed how a classic tie-up had developed between the use of computing techniques in important fields of mining, and their practical application. In fact, the dis-cussion following the rock mechanics papers showed clearly that without the aid of high-speed digital computers the rate of progress in applied research in deep-level hard-rock mines, would have been severely hindered. Furthermore, it became apparent from the comments made by several contributors that the rock mechanics techniques and computer progress described in Deist&apos;s and Cook&apos;s papers could be used to provide useful data in the solving of rock mechanics and design problems on mines other than flat dipping deep tabular deposits.The paper by Niskanen, which described an automated ventilation control system at a mine in Finland, showed how effective computers could be in areas where the reversal of mine ventilation occurs due to severe seasonal temperature ranges. Although the system described in the paper could not be introduced easily in complex underground mines, several contributors gave examples of similar ventilation problems that could be solved mechanically,In introducing his paper, Dr Deist said that the purpose of the paper was to give a brief account of some of the programs designed by himself and his co-authors to aid in the solution of rock mechanics problems,The first system presented by Dr Deist was known as MINSIM in the South African mining circles. This system was designed specifically to aid in the solution of rock mechanics problems in the South African gold mining industry. It was particularly designed to handle tabular deposits at great depth but it has been used satisfactorily on a number of occasions to obtain at least approximate solutions in other mining situations. Dr Deist said that the principles embodied in the programs were easily extended and, in fact, there was a project in progress at that time which was aimed to do this. He said that the principles could easily be extended to shallow-depth mining at steep or very steep inclinations."

Jan 1, 2014

By K. Karaman

This study investigated the effect of surface roughness on Schmidt rebound hardness (RL). Four different test surfaces of rock samples were studied: natural, ground, cut surfaces, and core samples. There was significant variability of standard deviation based on the RL on the natural surface, which indicated high roughness of the rock surface, whereas surface polishing caused a significant decrease in standard deviation. ISRM and ASTM methods were compared to estimate unconfined compressive strength (UCS) for different testing surfaces. RL obtained from the cut surface was found to be more reliable than those obtained from other testing surfaces for the prediction of UCS; however, regression and ANOVA analyses revealed that the ISRM method gave a more accurate UCS estimation of rocks with highly rough surfaces. It was also shown that RL values obtained from a cut surface were significantly higher than those obtained from core samples. Therefore, a comparison between RL values obtained from core samples and cut surfaces was made based on previous studies. This study statistically showed that estimated UCS values are not statistically significant if Schmidt rebound tests are not performed on similar surfaces. In addition, the mineral grain sizes of the studied rocks, different testing surfaces compared with those in literature, and standard deviation from RL are evaluated and discussed. The Schmidt hammer technique is a rapid, inexpensive, and straightforward method for estimating UCS for preliminary assessment; however, roughness of the surface should be eliminated if variations are shown in the surface rebound hardness.

Apr 14, 2024

By A. Rödfalk, P. Bloemer, J. P. Nilsson, N. Brogden

"Reliable and accurate metal transfer information during silicon tapping from an EAF is invaluable for decision-making and process optimization, while obtaining such information safely is a necessity.Elkem Thamshavn Norway, a producer of metallurgical-grade silicon, identified inherent safety problems with gauging fill levels in ladles using dip bars while molten metal was continuously pouring from a rotating EAF. Operator safety was a paramount concern, and an alternative automatic method of controlling the tapped fill level needed to be found.It was also considered that further benefits could be achieved such as monitoring the tapping flow from the EAF in order to identify any clogging, as well as the potential to use the live feed from such a system to assist decision-making regarding work around the taphole area.Agellis Group AB, Sweden, a company with over 30 years of experience in gauging molten metal levels in the metals industry, was able to design a solution for Elkem Thamshavn that would provide the required real-time process data while enhancing operator safety.This paper shows how the Agellis AB EMLI-L system was successfully installed at Elkem Thamshavn’s EAF continuous tapping area, how ladle fill levels were constantly monitored, and how full ladles were replaced by empty ones without the need for operators to be in the tapping area to take level readings. The results were used to compare the accuracy and reliability of Elkem Thamshavn’s current measuring methods with that of the EMLI-L system. The paper also covers how problems such as how to connect, run, and protect cables in and around the EAF tapping area, as well as connector and cabling survivability during the three day refractory pre-bake period, were solved. Finally, the paper discusses the potential production improvements, maintenance requirements, and data integration attainable through the installation of the system, as well as the major safety improvements that have been achieved."

Jan 1, 2014

By D. Botha, J. F. Cronjé

"SynopsisAlthough women all over the world have been involved in mining activities for centuries, mining has always been considered a very masculine industry due to its heavily male-dominated workforce as well as the physicality of mining work. The mining industry has not been an obvious career choice and preferred place of employment for women; women were mainly employed in administrative and advisory positions. Until 1994, women were legislatively prohibited from being employed in underground operations in South Africa, but the Mines Health and Safety Act, No. 29 of 1996, removed these restrictions. In addition, new mining legislation (the Mineral and Petroleum Resources Development Act, No. 28 of 2002) and the accompanying Mining Charter make specific provisions for the inclusion of women in core mining activities and require 10% of core positions to be filled by women.This article voices perceptions of the physical ability of women employed in core mining positions. Findings are drawn from empirical work undertaken at platinum, phosphate, and copper mines. Quantitative and qualitative research paradigms are used. It is evident that women find it extremely difficult to perform mine work that requires physical strength and stamina. Practical recommendations, informed by the literature review and empirical findings, are made with the objective of contributing to the sustainable deployment of women in the mining industry.IntroductionFor many years, mining has been considered the foundation of the South African economy. Although the mining industry in South Africa is currently under considerable pressure and experiences various challenges, including escalating operational costs, electricity tariff increases, safety-related issues and associated production stoppages, poor productivity, labour unrest, and reduced demand both globally and domestically, it remains a key contributor to the national economy and development of the country (IDC, 2013, p. 9).Until 1994, women were legislatively prohibited from meaningful participation in the mining industry and were denied access to skills and jobs, self-employment, and entrepreneurship. The newly elected democratic government in 1994 initiated substantial socio-political and economic transformation in South Africa. Nearly every sector in the country was transformed and re-shaped, primarily through sector-specific legislation, but also through negotiations between government, industry, and labour unions to create and refine the so-called sector charters, which included the Mining Charter. The vision of the new regime, the African National Congress (ANC), was to ‘transfer power to the people and transform society into a non-racial, non-sexist, united, democratic one, and change the manner in which wealth is shared, in order to benefit all the people’ (ANC, 2007)."

Jan 1, 2015

By A. J. Hofmann, G. P. R. van der Merwe, J. E. W. Holm

"A new approach is proposed to perform relativistic comparisons between alternative operational risk management solutions by taking into account the impact of each operational activity on overall system performance. A specific case study, to which this new approach is applied, involves the deployment of safety systems in underground mining operations. Conflicting objectives to be satisfied are the minimization of risk to human lives and the minimization of production losses. As the focus in this case is primarily on the mitigation of risk, the approach that was applied is referred to as activity-based risk (ABR) analysis. Existing development process and risk management methods used in the South African mining environment were analysed by means of observations, a case study, technical documentation, and literature review. It was evident from this analysis that a discontinuity existed between the acquisition and operational phases in terms of the management of safety risk in the acquisition of electronic safety equipment when viewed from a full lifecycle perspective. This discontinuity could be addressed by defining a risk perspective in the system development phase by employing ABR in the preliminary design phase of a system’s engineering life-cycle. The focus of the ABR system development process is to find the functional definition and configuration of safety equipment that addresses both safety and productivity when taking into account human performance variability. In doing so, a balance between productivity and safety is found in a relativistic sense. IntroductionIn any system life-cycle, two major phases exist, namely system acquisition and operation (including maintenance). A distinction is made between acquisition and procurement, where acquisition includes system development and integration as specific engineering activities. In the development phase of a new system, conceptual design, preliminary design, and detail design phases follow in this order to define a complete system, after which the system is put into production and implemented in an operational environment—these activities chronologically define system acquisition in the context of this paper. It is not uncommon that differences exist between the risk management perspective during acquisition of a system and risk management perspective during operation, where nontechnical aspects are often ignored during acquisition, but are then encountered and found to be problematic during operation (Leveson, 2012). These differences also exist in the mining industry."

Jan 1, 2017

By R. Nyirenda, B. Besa, N. Dzimunya

The accurate estimation of peak particle velocity (PPV) is crucial during the design of bench blasting operations in open pit mines, since the vibrations caused by blasting can significantly affect the integrity of nearby buildings and other structures. Conventional models used to predict blast-induced vibrations are not capable of capturing nonlinear relationships between the different blasting-related parameters. Soft computing techniques, i.e., techniques that are founded on the principles of artificial intelligence, effectively model these complexities. In this paper, we use the random forest (RF) algorithm to develop a model to predict blast-induced ground vibrations from bench blasting using 48 data records. The model was trained and tested using WEKA datamining software. To build this model, a feature selection process using several combinations of Attribute Evaluators and Search Methods under the WEKA Select Attributes tab was performed. The correlation coefficient of the actual data and RF model-predicted data was 0.95, and the weighted average of the relative absolute error (RAE) was 10.9%. The RF model performance was also compared to the equivalent-path-based (EPB) equation on the testing data-set, and it was seen that the RF model can effectively be used to predict PPV. The study also demonstrates that the EPB equation is a suitable empirical method for predicting PPV.

Mar 30, 2023

By A. Marek

The safe and optimal installation of roof support remains one of the biggest challenges in underground mining today. Traditional hand-held, roofbolt installation in conventional mining has been replaced, in a lot of mining operations, by mechanized equipment. This was a first step to moving the operators out of the unsafe working environment and a start on the trend toward a changed support regime in mechanized mining. However, the challenge of handling of the drill steel itself, as well as inserting resin cartridges and bolts, remains a major hazard and the cause of many lost-time injuries. The paper describes and discusses developments in this area, of mechanized bolting and on-board automation, presenting solutions to known problems, achievements to date, and future developments. The solutions presented will identify with addressing customer needs while touching on possibilities for further technology changes, keeping focus on the safety aspect for operators and the need to bring the operators even further away from the unsafe working environment. The-state-of-the-art technology in mechanized bolting equipment is presented and a brief outlook on the past, current, and future developments is given.

Jan 1, 2012

By J. P. Garnier, T. Bhambhani, J. A. Garcia, N. Renaud

Most flotation plants use a static reagent scheme, i.e., a set combination of collectors, frothers, and modifiers. This scheme is usually developed and refined over time to deliver optimal (not necessarily the highest) performance when the major ore types are fed to the plant. However, when ore types or mineralogy coming to the plant change substantially (and this often happens as different areas of the pit(s) are mined and crushed at the same time), there are upsets in the process, typically leading to lower recoveries. Adapting to this variability is usually done only when performance drastically suffers, and the changes made may be too late and bring additional variability in performance. The premise for SmartFloat™ is that the reagent suite needs to be dynamic, adapting continuously to changes in the ore and operating conditions. Solvay has combined advanced analytics and data science techniques with its expertise in flotation reagent chemistry to systematically and automatically achieve the above, and in real time. Thus, SmartFloat™ is optimizing the reagent suite continuously, removing the additional variability created by belated human interactions resulting in a better and more stable process. In addition, this advanced approach allows for continuous improvement by identifying poor performing ore domains and improving the reagent suite using Solvay’s FM-100 approach to design appropriate solutions.

Jan 1, 2023

By J. van Deventer

Ion exchange is widely used in hydrometallurgical operations for the recovery and purification of valuable metals. Special chelating resins have a high affinity for specific elements, allowing the selective removal of low levels of impurities from a background of highly concentrated valuable metal. Solvent-impregnated resins have been added to this group more recently, expanding the treatment options. These products find application in the purification of cobalt-rich liquor prior to the production of high-purity metal or metal salts. Impurities in copper-cobalt circuits that are typically targeted by ion exchange include iron, uranium, copper, zinc, nickel, bismuth, and antimony. Ion-exchange resins can also be used to treat tailings, thereby recovering additional valuable metal and improving the Environmental and Social Governance credentials of the operation. This article takes a look at various applications of ion exchange in copper-cobalt operations

Jan 1, 2023

"Investment in diamond exploration has been declining over the past decade, in spite of positive long-term industry fundamentals and a growing interest in diamonds as an investment category. The lack of new significant discoveries in recent years has eroded investor confidence, yet no new discoveries are possible without investment in exploration. Junior ‘mine finders’ have been the hardest hit. Their agility, tenacity, and appetite for risk are not sufficient to attract the funding required, even at the greenfield stage. Developing new discoveries into mineral resources can be crippling without solid financial support. Junior incubators could play a crucial role, especially at the project evaluation stage – but where are they? Alternatives to traditional funding mechanisms have become available, many still untested in the junior diamond exploration space. Valuable lessons can be drawn from the past and used to inform emerging new strategies. IntroductionDiamonds are the ultimate expression of love. Their ancient and timeless allure continues to influence consumer emotions and behaviours across continents, cultures and age groups. Analysts are predicting a sustained supplydemand shortfall in the years ahead which will trend diamond prices generally upwards. With positive long-term industry fundamentals, one cannot help but wonder why funding for diamond exploration and development projects is so scarce.Investment in exploration across commodities – including diamonds – has been declining for a number of years, reaching a historic eleven-year low early in 2017. The lack of major diamond discoveries in recent years has done little to strengthen the case for investing in diamond projects, yet no new discoveries can be made without investment in exploration.Global estimates of known carats in the ground stand currently at 2.5 billion carats, which equates to around 18 years of production at current levels of 140 million carats (mct) per annum. Sustainable replenishment of depleting diamond resources is possible only through the development of new discoveries. This is what junior explorers are best at – but they need investors to fund their evaluation activities from early in the project development continuum."

Feb 1, 2019

By R. J. Durrheim, B. Manzunzu, V. Midzi

Selecting ground motion prediction models (GMPM) is crucial in assessing seismic hazard levels in a specific region. This study investigates the influence of ground motion model (GMM) selection on seismic hazard assessment in Johannesburg, South Africa. Most seismic events affecting Johannesburg are related to mining activities and water ingress into the underground mine voids. The most seismically active regions in South Africa include areas around Klerksdorp, Welkom, and Carletonville. These regions experience a significant number of earthquakes, with mining activities being a major factor contributing to seismic events. Ten ground motion prediction equations were selected from regions of similar tectonics setting and were assessed to see if they correspond to the available local data. Six of these were also compared to the ground motions produced by the earthquake of 14 August 2014, which occurred in the Orkney area, one of the mining areas in South Africa. Sensitivity analyses were also carried out to assess the influence of ground motion prediction equations (GMPE) on the seismic hazard of Johannesburg. The results indicate that the choice of GMPM significantly affects the estimation of seismic hazard levels in Johannesburg. Different GMM can lead to varying ground shaking intensity predictions, impacting risk assessments and engineering design considerations. The findings highlight the importance of carefully selecting appropriate GMM tailored to Johannesburg’s specific geological and tectonic characteristics. Understanding how different models perform in this region is essential for accurate seismic risk mitigation strategies.

Jan 12, 2025

By W. H. Holtzhausen

The purpose of this project was to compare two underground, batch coal haulers ? battery haulers and shuttle cars ? in order to determine the more viable machine to implement. The specific standards for battery haulers were investigated and compared to the requirements of shuttle cars in order to identify the unnecessary expenses related to the legal requirements that are attached to the machines. Costs such as running costs, capital costs, and maintenance costs were researched and compared over a typical life of machine. Average production rates and breakdown times were obtained and used to determine which machine would be more reliable in achieving the required annual production.

Jan 1, 2014

By Y. Qin, X. Fu, T. Qi, H. Tang

"The FASTMELT ® process was developed as an alternative to blast furnace ironmaking; in this process, high-quality molten iron is produced using direct reduction followed by high-temperature slag/metal separation. In this study, iron recovery and phosphorus removal from oolitic highphosphorus haematite using the FASTMELT® process was investigated. The performance of two reducing agents, coal and wood char, was compared. Direct reduction experiments indicated that with optimized reductant addition, the ore-char and ore-coal briquettes attained metallization values of 82% and 78%, respectively, and residual carbon contents of 0.24 and 2.35%, respectively. The slag/metal separation experiments revealed that molten iron containing 0.41% phosphorus and 0.021% silicon (by mass) was produced from optimally reduced ore-char briquettes, and molten iron containing 0.78% phosphorus and 0.91% silicon from optimally reduced ore–coal briquettes. The study indicates that carbonaceous materials with high CO2 reactivity are suitable for use in the FASTMELT ® process for phosphorus removal and iron recovery from oolitic high-phosphorus haematite. IntroductionIn China, the general depletion of iron-rich mineral reserves has led to many efforts to exploit low-grade and refractory ironcontaining resources for ironmaking (Liu et al., 2014). The efficient utilization of the highphosphorus oolitic haematite resources in central China has received considerable attention. The available resources of this material total approximately 3.0 billion tons. The oolitic units in the ore exhibit an onionlike structure with phosphorus-containing gangue layers of 2–10 µm thickness. The best concentrate produced from these resources contains approximately 50% iron (Fe) and 0.8–1.2% phosphorus (P) (by mass) (Ai, Yu, and Wei, 2009; Song et al., 2013; Wu, Wen, and Cen, 2011). Further removal of phosphorus from these ores using conventional beneficiation methods is not possible."

Jan 1, 2017

By W. K. Ting, A. Hasan

Mine stope is typically backfilled with cemented paste backfill, which provides a regional underground stability and also a reduction of aboveground tailings accumulation. During backfilling, a phenomenon known as arching occurs and affects the stress distribution of the cemented paste backfill. The change in temperature due to uncontrolled heat transfer from the surrounding rock mass and/or generation from hydration process complicates the stress distribution development of cemented paste backfill. This paper presents results of the investigation on the effects of hydration to cemented paste backfill behaviour when backfilled into a narrow wall model using uncemented paste backfill as controlled sample. The parameters considered include backfill type (cemented paste backfill vs uncemented paste backfill), curing temperature (30°C–60°C), and stress evolution during pouring, consolidation, and curing stages. Results show that uncemented paste backfill re-establishes arching effects more readily, with lower peak stresses and greater stress relaxation than cemented paste backfill, of which its behaviour is significantly influenced by hydration under elevated temperatures. The main outcome of this work is that hydration critically controls the stress-temperature response of cemented paste backfill, and the balance between hydration-driven strength gain and stress relaxation can be leveraged to optimise backfill mix design for safer and more efficient stope filling.

Jan 30, 2026

By L. Ntlhakana, K. Khoza-Shangase, G. Nelson, I. Maposa

Occupational noise-induced hearing loss (ONIHL) is associated with various risk factors in South African mines. We investigated the association between standard threshold shifts (STSs) and exposure to noise and platinum mine dust (PMD), using demographic data, five years of annual audiometry screening results, and noise and dust exposure data. Miners’ age, sex, percentage hearing loss (PLH), and dust and noise exposure data were gathered, and a linear mixed effects regression model used to predict STS. Average occupational exposure levels to noise and dust were calculated from recorded measurements. A total of 12 692 records were analysed. Most miners were male (89.6%) and more than 50% were younger than 41 years. More than 70% were exposed to > 85 dBA noise and 58% were exposed to 1.5–2.99 mg/m3 PMD. Changes in hearing levels ranged from 8.3 dBHL at baseline (2014/2015) to 10 dBHL in 2016 (STS), with no changes thereafter. The model showed that the estimated effect on STS for males was 27% and 21% higher than for females, for the left and right ear, respectively The estimated effect of age, PLH, noise exposure and years of exposure on STS was < 10% for each variable. There was no statistically significant association between PMD and STS. The combined effects of age, sex, years of exposure to noise, and noise exposure levels, and strength of associations can be used to predict STS for this group of miners. Our findings may be used to measure the efficacy of the mine’s hearing conservation programme.

Aug 1, 2021

By A. Drumond, J. F. C. L. Costa, M. G. Lemos, A. L. Rodrigues, F. G. Niquini

The past decade has seen a renewed possibility of using machine learning algorithms to solve a large collection of problems in several fields. Data acquisition for mining operations has increased with the growth in sensor-based technologies, and therefore the amount of information available for mining applications has dramatically increased. Ore sorting equipment is available for separating ore from waste based on differences in physical properties detected by a real-time analyser. The separation efficiency depends on the contrast in these properties. In this study we investigate the application of machine learning models trained using data from the output of a dual-energy X-ray ore sorting apparatus at a gold mine. The particles were first hand-sorted into ore and gangue classes based on their mineralogical composition. Classification models were then used to help decide the balance between the number of true and false positives for ore in the concentrate, with a view to economic parameters, using their receiver operator characteristic (ROC) curves. The results showed AUC (area under the ROC curve) scores of up to 0.85 for the classification models and a maximum reward condition Fpr/Tpr around 0.5/0.9 for a simplified economic model.

Aug 8, 2024

By M. Karsten

Platinum mines in the Bushveld Complex are located in areas with a high geothermal gradient. This means that, compared to, for example, gold mines of the Witwatersrand region, high rock temperatures are encountered at relatively shallower depths. Thus air cooling and refrigeration need to be considered at early stages in mine development. Another factor that influences air cooling and ventilation requirements is the use of trackless diesel equipment for loading and hauling broken rock. At shallower depths it will be more cost-effective to locate the cooling and ventilation equipment on surface, whereas for deeper mines the more cost-effective option is to locate cooling equipment underground. For intermediate depths, trade-off studies need to be undertaken to determine the optimum mix between more cooling and less air or more air and less cooling, as well as the optimum location for this cooling equipment. Factors that are taken into account include power requirements, positional efficiency, and additional infrastructure requirements. Traditionally the approach has been to ventilate ?all of the mine all of the time?. However, with increasing power costs and growing pressure to ensure sustainability, this strategy must be modified to apply ventilation and cooling on demand. In other words, both cooling and ventilation equipment should be operated only when needed and should be adjusted to the demand at the time. Obviously there will be areas that will need to be ventilated (and cooled) continuously (for example, for dilution of flammable gases), but this can be built in to the overall strategy. In addition, in devising ventilation on demand (VoD) strategies, occupational criteria relating to exposure to gases, noise, and heat need to be taken into account. This paper discusses options available for implementing energy-efficient ventilation and cooling systems and suggests ways of changing traditional thinking in the overall ventilation and cooling of mines. Efficient ventilation and cooling designs can play a major role in improving sustainability and reducing energy costs and carbon footprint.

Jan 1, 2012