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By S. Plaatjie, L. Linzer, M. S. D. Manzi, M. Sihoyiya

Fiber-Optic Sensing and UAV-Platform Techniques for Innovative Mineral Exploration (FUTURE) is a joint European Union and South African consortium project funded under ERA-NET Cofund ERA-MIN3. The project aims to develop cost-effective and novel seismic methods to image geological structures ahead of the mine face, ultimately leading to improved decision-making and safer mining practices. In this study we present results from numerical simulations conducted at South Deep Gold Mine for active in-mine seismic surveys. The study uses a finite differencing code known as WAVE3D, which models models the propagation of a seismic wave generated by stress pertubations that are applied to a defined grid. The numerical simulation model included two major ore bodies (Black Reef and Ventersdorp Contact Reef) and mine tunnels. The model was constrained using laboratory physical property measurements from underground borehole samples such as seismic velocities (e.g., compressional and shear waves) and bulk densities. Two case studies were created, one modelled the active shots and receivers on surface, and the other modelled the shots at depth (in a mine tunnel at ~4000 m depth) with receivers on surface. In both cases, the objective was to investigate the wavefield propagation through the rockmass between the mine tunnel and surface. The simulated wavefield produced by the source located along the mine tunnel was successfully recorded on surface. The surface-recorded wavefield exhibits clear one-way P-wave arrival times at approximately 450 ms to 500 ms, which can be used to calculate the surface-tunnel P-wave refraction tomogram. The results from the study were used to constrain the design, and for the acquisition and processing of the real surface and in-mine seismic surveys acquired under the FUTURE project.

Jan 12, 2025

By S. Hlajoane, L. S. Mokhahlane

The demand for rare earth elements has increased around the world due to their application in a variety of technological advancements. Previous studies have evaluated the potential of the rare earth elements and yttrium (REY) hosted within the Permian coal deposits of the main Karoo Basin (MKB) in Southern Africa. However, not a lot of scientific research has gone into the Triassic coal deposits. The Triassic coals in South Africa were the first coals to be exploited for their thermal use in the 1880s, but the discovery of the higher rank and more abundant Ecca coal deposits led to the Triassic coals remaining largely unexplored. The demand for rare earth elements has sparked interest in these coal deposits as potential sources for valuable minerals. Late Triassic coal deposits in Lesotho have previously not been well documented and these low-rank coals can be a potential source of rare earth elements. This study aims to characterize and evaluate the potential of REY in the Taung coal deposit, southwest of Lesotho. Coal and associated argillaceous samples from the Taung coal deposit were analyzed using microscopic petrography for coal characterization and an inductively coupled plasma mass spectrometry (ICP-MS) to determine the amount of rare earth elements. Taung coal is classified as middle medium rank D bituminous coal. The total REY content in Taung coal and its associated rocks range from 162.9 ppm to 855.1 ppm, which is significantly higher than the upper continental crustal (UCC) average. The average critical REY concentration of samples from the Taung coal deposit is 189.4 ppm, which is three times higher than that of the Chinese Bayan Obo deposit. Samples classified as very promising and promising because of their outlook coefficients, are found to contain up to 77% of critical REY. It is envisioned that the area could be a prime deposit for these REY.

Nov 6, 2024

By C. Birch, J. Perold

"Due to the challenging geological environment of the Postmasburg Manganese Field (PMF), a study was conducted to determine if any benefits would derive from the inclusion of resistivity data during threedimensional (3D) modelling of the manganese resource. This was achieved by estimating manganese resources from 2011/2012 drilling data and comparing them with manganese resources estimated from the same drilling data and resistivity data collected during 2013 and 2017.Both models were adjusted to limit their extent to the same 3D modelling space. Significant volume and tonnage differences were observed for all lithological units. The greatest differences were noted in the manganiferous zones of alteration – 7.200 Mt for the geological model versus 3.700 Mt for the geoelectric model.This study showed that the inclusion of resistivity data can reduce exploration costs significantly, as a direct consequence of the resistivity data allowing more accurate siting of boreholes. This decreases the number of boreholes, samples, and analyses required due to the 3D electrical delineation of mineralized areas prior to drilling.An additional benefit is the ability to more correctly forecast the net present value of an operation due to more accurate estimation of manganese resources and stripping ratios. This is clearly demonstrated by the estimated gross profit estimation of R409 million for the geological resource model versus R264 million for the geoelectric resource model.The addition of resistivity data can, therefore, reduce exploration costs and can increase confidence in geological and financial modelling. It would be reasonable to conclude that this approach could also be used for karsthosted massive sulphide deposits. IntroductionAccording to Corathers (2014) and Gajigo, Mutambatsere. and Adjei (2011), South Africa holds between 75–80% of global manganese reserves, followed by Ukraine (10%), Australia (3%), India (3%), and Gabon (2%). The known, land-based, manganese resources located elsewhere are estimated at 2%.The majority of economically important sedimentary manganese ore deposits in South Africa are situated in the Northern Cape Province (Gutzmer, 1996). Manganese ores of the Postmasburg Manganese Field (PMF) were discovered in 1922, and the Kalahari Manganese Field (KMF) in 1940. According to Astrup and Tsikos (1998) and Gutzmer (1996), mining of manganese ore from the PMF ceased during 1989 in favour of the superior quality of manganese ore from the KMF."

Mar 1, 2019

By L. Stamenov, A. Grigoryan, M. Nolte, E. Ayvazov, K. Evtiminova

Dundee Precious Metals Inc. (DPM) owns and operates the Ada Tepe gold mine and processing facility (previously referred to as the Krumovgrad Gold Project) located in south-western Bulgaria. The Ada Tepe mine became the first green filed project in past 40 year in Balkans and one of the few in Europe when it was commissioned during the first half of 2019. The plant produces a high-grade gold silicate concentrate generated through its comminution circuit and staged floatation reactors (SFR’s) while depositing its tailings in a state-of-the-art Integrated Mine Waste Facility (IMWF). This paper presents the successful commissioning, ramp-up and optimization of the Ada Tepe processing plant and how the various challenges, including that of an inexperienced front-line workforce, were overcome. More specifically addressing how the implemented modern processing technologies and the operational readiness program, supported the people and process to achieve the design parameters safely and consistently. Keywords: Commissioning, Optimization, Innovation, Gold mine, Digital mine

Jan 1, 2020

By S. Michael, T. E. Moongo

Electrowinning consumes a substantial amount of electrical energy, and owing to the ever-increasing unit cost of electrical power there is a need to improve current efficiency in the process. This research was carried out to design a continuous quality improvement framework for improving electrowinning current efficiency by applying statistical process control (SPC) on an online industrial copper electrowinning operation. A sequential mixed research methodology was applied and a statistical software package utilized for analysing data. It was concluded that metallurgical short-circuits (hotspots) had the most significant effect on current efficiency. Bringing hotspots under statistical control resulted in a 5.40% improvement in current efficiency, which is equivalent to approximately 74 t of 99.999% pure grade A copper cathode production over a period of 1.5 months.

Jan 1, 2021

By C. Musingwini, M. Mohutsiwa

"SynopsisCapital cost estimates are important in decisions on whether a project will be approved, mothballed, or abandoned. In South Africa, junior coal miners do not have extensive databases of historical projects from which to estimate capital costs. The purpose of this paper is to establish formulae that can be used for estimating capital costs of developing coal mines in a coal-producing country, using South Africa as a case study. The costs are estimated to an error of magnitude level of -30% to +50%, which is suitable for a concept study level, using a parametric estimation technique. The study uses data from completed coal mining projects from selected coal-producing countries. Three formulae are developed and presented for estimating capital costs of underground bord and pillar, surface shovel and truck, and dragline operations.IntroductionCapital cost estimates play a critical role in deciding whether projects will proceed, be delayed, or abandoned. It is therefore important that capital cost estimates are carried out accurately as determined by the estimation guidelines based on the level of estimation conducted (Shafiee and Topal, 2012). The lack of literature on estimation of capital costs in many coal mining countries is adversely affecting junior coal miners, since they do not have an extensive database of historical projects on which to base estimations. In South Africa, the difficulty in estimating capital costs is attributable to lack of publicly available data on completed South African mining projects (Hall, 2013)."

Jan 1, 2015

By L. Uotinen, M. Rinne, R. Mishra

Underground mining gives rise to geotechnical hazards. A formal geotechnical risk assessment can help to forecast and mitigate these hazards. Frequentist probability methods can be used when the hazard does not have many variables and a lot of data is available. However, often there is not enough data for probability distributions, such as in the case of new projects. The risk assessment is often subjective and qualitative, based on expert judgement. The purpose of this research is to present the use of Bayesian networks (BNs) as an alternative to existing risk assessment methods in underground mines by combining expert knowledge with data as it becomes available. Roof fall frequency forecasting using parameter learning is demonstrated with 1141 sets of roof fall data across 12 coal mines in the USA. The prediction is nearly identical for individual mines, but when multiple mines are evaluated it is difficult to find a single best fit distribution for annual roof fall frequency. The BN approach with TNormal distribution was twice as likely to fit the observed data compared to the Poisson distribution assumed in the past. A hybrid approach using BN combining multiple probability distribution curves from historical data to predict annual roof fall is proposed. The BN models can account for variability for multiple parameters without increasing the complexity of the calculation. BNs can work with varying amounts of data, which makes them a good tool for real-time risk assessment in mines.

Jun 1, 2021

By A. McQuillan, N. Bar

Geotechnical models developed during the planning stages of open pit mines are three-dimensional so as to capture the spatial variation in lithological, structural, hydrogeological, and geomechanical conditions. Geological models that describe the lithological and structural (faulting and folding) characteristics of a deposit are always 3D. Likewise, boreholes and piezometers used to develop geomechanical properties and groundwater models are drilled at spatial offsets across the deposit to understand the lateral and vertical characteristics. Yet when geotechnical analysis is completed, often the three-dimensional geological, hydrogeological, and structural models as well as geometrically complex 3D mine designs for optimizing economic mineral recovery and overburden removal are simplified to two-dimensional sections. In this paper we demonstrate that this simplification can lead to the wrong failure mechanism being identified, analysed, and/or a conservative factor of safety being calculated and hence an over-estimation of slope stability. Through case studies we show how three-dimensional analysis methods are more suited to rock slopes, particularly those with anisotropic material strength, when singularities such as geological faults are present, and nonlinear slope geometry. When the same slopes are analysed in two dimensions, the failure mechanism calculated is often fundamentally incorrect. The case studies further reveal that the factor of safety calculated in three dimensions is not always higher than the two-dimensional factor of safety.

Feb 6, 2023

By C. M. Rule, A. K. Anyimadu, L. Knopjes

Ongoing development work on ultra-fine grinding for various applications at the Group?s concentrators has been conducted by Anglo Platinum over the last few years. Current potential applications for mainstream grinding and concentrate grinding are the subject of a group-wide research and development programme. The first 10 000-litre 2.6 MW IsaMill was jointly developed by Anglo Platinum, Xstrata Technology and Netszch for installation at the Western Limb Tailings Re-treatment project in Rustenburg, South Africa. The unit was commissioned in late 2003/early 2004, and has operated in an intermediate concentrate regrind application successfully since. This paper describes the operational performance to date, as compared with the original duty specifications and objectives. The first mainstream M10 000 IsaMill with a 3 MW drive will be operational in November2006 at the Potgietersrus Platinum (PPL) ?Platreef? Sandsloot Concentrator in South Africa?s Limpopo Province. Key Words: Western Limb Tailings Re-treatment Plant, IsaMilling, Platreef, Platinum, Palladium, PGMs, tailings.

Jan 1, 2006

Mr K.C. Owen started his mining career as a learner official after matriculating at the Parktown Boys' High School, Johannesburg in 1967.

Jan 1, 1991

By K. J. Craig, M. A. Swart, Q. G. Reynolds, L. Hockaday

A solar reflector soiling study was carried out at a ferromanganese smelter in South Africa to assess the soiling rates at different locations around the plant. Several meteorological parameters were monitored to give insight into the conditions that lead to increased soiling. Mineralogical characterization of dust samples collected from the reflectors and the atmosphere revealed that only a certain size fraction is of importance with regard to soiling, and that the dust can be attributed to both raw materials and smelter products. Proximity to the dust source was the primary driver for increased soiling. The site that experienced the most soiling was very close to raw material heaps; this was deemed an outlier and was excluded from the summary statistics. The secondary driver for increased soiling was location relative to the smelter dust sources and the wind’s direction and speed. The reflector set at the best location experienced 13.1% less soiling than the set at the ‘worst’ (but still feasible) location, represented by an averaged mean daily reflectance loss of 0.0186. The study revealed that while there are periods of intense soiling at this particular site, proper planning of reflector location in relation to the smelter dust sources can significantly mitigate the soiling rate.

Jun 5, 2023

By H. Han, Z. Gao, Y. Gao, W. Sun, J. Wang

Strategic Ca-bearing minerals like scheelite and fluorite are usually separated by flotation, yet the separation is quite difficult due to their similar surface Ca active sites. Compared with the conventional strong collector sodium oleate (NaOL), lead nitrate-benzohydroxamic acid (Pb-BHA), complex collector shows a better selectivity for scheelite, yet its high cost hinders its wide application. Therefore, a novel collector (Pb-BHA-NaOL complex) was initially developed in this work to overcome the abovementioned dilemma. The flotation results of a single mineral showed that Pb-BHA-NaOL had a better selectivity for scheelite than Pb-BHA. Under the conditions of sequential assembly of Pb, BHA and NaOL at the molar ratio of 240:120:1 and pH 9.0, selective separation of scheelite from fluorite could be achieved without adding any depressants. In addition, for the same preferred scheelite recovery, Pb- BHA-NaOL could also save approximately 20% Pb and BHA compared with Pb-BHA. The analyses of the zeta potential measurement and X-ray photoelectron spectroscopy indicated that Pb-BHA-NaOL showed stronger adsorption on scheelite relative to fluorite. Meanwhile, Pb-BHA-NaOL showed more adsorption modes and higher utilisation of Pb and BHA on scheelite than Pb-BHA, which was due to the accelerator, NaOL. Keywords: Scheelite, fluorite, lead nitrate, benzohydroxamic acid, sodium oleate, flotation

Jan 1, 2020

By S. K. Murphy

A partial shaft pillar extraction project was embarked on at a mine in the West Wits mining region in South Africa. Prior to the extraction, a rock engineering assessment was conducted with the main objective being to establish which areas of the shaft pillar could be extracted without unduly affecting the stability of major infrastructure within the shaft pillar. Standard numerical modelling methods were used to conduct this assessment and several areas were identified for extraction. However, during the extraction process, it was found that the infrastructure was affected more than was originally predicted by linear elastic modelling. In addition to this, several large events resulted in far more large aftershocks than would normally be predicted. In order to gain an understanding of this phenomenon, seismic data was integrated with numerical modelling as follows: > The seismic data in the form of displacements was integrated in 3D space within the model to assess the effect of static stress changes associated with seismic activity > Data from large events was integrated onto specific structures, where displacements associated with large events were integrated onto the plane of structure in question. This paper describes the methodology and results obtained from each of the above processes and include insights into the mining process that were previously unfathomable using standard linear elastic numerical modelling. The way forward for this rock engineering assessment of partial shaft pillar extraction is also discussed.

Jan 1, 2012

By T. Nyakudarika

The Unki Platinum Mines concentrator, employing an MF2 circuit configuration which includes fully-autogenous primary milling of run-of-mine (ROM) ore, was commissioned in November 2010. The project was Anglo American Platinum?s first PGM concentrator in Zimbabwe and would form a significant contribution to the group?s platinum production. The project financials demonstrated that the project was operating-cost sensitive. After reviewing the metallurgical testwork, mineralogical examinations, and the history of similar operations, it became apparent that the Unki ore characteristics rendered it amenable to autogenous milling. The primary ball mill, structurally designed for 30 per cent steel load, could be operated at the required initial phase throughput with fully-autogenous primary milling, realizing savings in both power requirements and grinding media consumption. The original mill sizing had been done with fully-autogenous milling in mind, but allowing for flexibility and mitigation in case of varied mining fragmentation. Since attaining steady state, target grinds have been achieved. This paper looks at the Unki ore characterization programme, design considerations, and the operational and control philosophy for a successful comminution circuit, and discusses the design to produce a flexible, low opex, mitigated comminution and overall MF2 flowsheet that is easily expanded in line with the potential for optimum exploitation of the orebody.

Jan 1, 2012

By J. Githiria, D. Wachira

The conventional truck and shovel haulage system has become expensive to operate in most mines due to current strict environmental conditions, increase in depth and size of open-pit mines, increase in labour costs, and fuel costs. These factors have motivated the search for alternative material haulage options in open-pit mines. In-pit crushing and conveying (IPCC) system has been regarded as a plausible alternative in material haulage systems. However, usage of IPCC has been limited to a few mines due to limited knowledge of IPCC performance, and other technical factors of the system. This paper investigates, and evaluates the productivity performance of four types of IPCC systems (fixed, semi-fixed, semi-mobile, and fully mobile IPCCs) using mine productivity index (MPi). Using a model developed by MATLAB, the MPi for the four systems is computed using input variables such as availability, utilisation, performance and number of trucks and shovels in a limestone quarry. The mine productivity index for fixed, semi-fixed, semi-mobile, and fully mobile IPCC is obtained as 67.13%, 69.02%, 70.52%, and 71.52% respectively. In conclusion, the fully mobile in-pit crushing and conveying system is the most appropriate IPCC in the quarry, due to its better productivity performance compared to the other three IPCC systems and the truck and shovel system currently in use.

Sep 1, 2021

By C. Dorfling, M. Tadie, M. Tucker

Electrowinning is the final step in the hydrometallurgical production of high purity copper, involving the passage of electric current through an electrolyte and consequent plating of solid copper to form cathode sheets. Key electrowinning performance indicators are the current efficiency, specific energy consumption, yield, and quality of the metal. The high energy demand and associated cost mean that determination of performance indicators is critical during operation, but ‘online’ measurement is impractical due to the nature of the measurements and corrosive environment brought about by acid mist. This research considered the development of a predictive electrowinning model as a shift towards a pre-emptive approach to attaining plant performance data. A steady-state model was created from input variables available in the industry, using a first-principles approach combining mass balances, electrochemical and thermodynamic equations, and property correlations. A circuit diagram equivalent of an electrowinning cell, containing multiple pairs of electrodes, was used as the backbone of the model. The kinetics of each electrochemical reaction were modelled including iron as a major impurity. Losses in current efficiency due to ineffective electrode contact, short circuits, and stray currents were also incorporated. The model was used to predict the current efficiencies for tests performed at varying conditions in a bench-scale electrowinning cell; the average absolute error between the measured and predicted current efficiencies was 3.2%. The model requires a unique parameter fitting approach for each industrial operation; if parameters are customised for specific plants, the model will be a useful tool to predict performance and can aid the development of effective process control systems in copper electrowinning tank houses. Keywords: Copper; current efficiency; electrowinning; modelling; plating rate

Jan 1, 2020

By T. Grewar

"South Africa is a water-scarce country, rated as one of the 30 driest countries in the world. Worryingly, government expects water demand to outstrip supply as early as 2025. The South African government believes that substantial volumes of water can be made available through the reuse of treated mining-impacted water. Currently, however, large volumes of treated mining-impacted water are produced, often with no end use in mind other than discharge or disposal, when these treated effluents may have further uses in applications which are currently and unnecessarily using high-quality water. Treating the wastewaters to levels that meet ’fitness-for-use’ guidelines for alternative applications such as agriculture, sanitation, or industrial processes will reduce the treatment cost burden compared to potable water production. The primary conclusion of this review is that the most suitable option for re-using treated mine-impacted water is in agriculture, for irrigation of crops (food, forage, or energy crops), which currently and unnecessarily makes use of the majority of South Africa’s high-quality resources or potable water. Other findings include the realization that although guidelines and legislation for water re-use in South Africa exist and are readily available, they tend to be contradictory and confusing in many cases. It is imperative that these ambiguities and incongruities in the available guidelines and legislation for water re-use be clarified and updated swiftly IntroductionSouth Africa is a water-scarce country and is currently rated as one of the 30 driest countries in the world, with an average rainfall of 490 mm/a, approximately half of the global average. As an indicator of the degree of regional variability in South Africa’s water supply, it has been shown that 70% of all runoff is from approximately 20% of the land area. Regardless of the water scarcity faced in South Africa, our water conservation track record is poor, with an average consumption of 280 L/d per person, almost 60% more than the global average of 175 L/d per person. Around 40% of this allocation is utilized in watering lawns and gardens (Zhuwakinyu, 2017).The South African government predicts water demand to outstrip supply as early as 2025. On an international scale, the situation appears just as dire, with the United Nations High Level Panel on Water (HLPW) expecting a 40% water shortfall by 2030, which may affect up to 1.8 billion people based on current water demand trajectories (Zhuwakinyu, 2017)."

Mar 1, 2019

By J. Pelders, F. Magweregwede, S. M. Rupprecht

Increased depths of conventional gold and platinum mines, longer travelling times as working places move further from the shaft, and ancillary activities taking place in the mining cycle reduce the useable time spent at them workface. Current shift lengths of 8 hours 20 minutes may no longer be adequate ton complete required mining activities.The impact of mineworker commuting times on shift work is also not well understood. The aim of this research was to draft a framework to optimize shift cycles in order to maximize productivity, health, safety, and wellness in the South African mining sector. The framework was informed by a review of the literature, case studies at a local gold mine and platinum mine, and a workshop with industry experts. The findings indicate potential advantages of extended shift lengths and continuous operations, such as improved productivity, asset utilization, and employee morale. However, concerns included fatigue and the associated safety hazards, particularly when working longer shifts, night shifts, and numerous consecutive shifts. Job demands, personal factors, and commuting times are further considerations when scheduling shifts. The ideal shift system for the mining sector should holistically consider and balance operational requirements, health and safety, and employees’ and their families’ requirements, and suit the unique needs of each operation. Changes in shift cycles will require a structured change management process, which involves all stakeholders, and could help to enhance the viability of the South African mining sector.

Aug 1, 2021

By C. Dorfling, M. Tadie, S. Grobbelaar

The physicochemical properties of the complex electrolytes used in direct copper electrowinning are an important consideration for the development of a high-fidelity model of the process. Direct electrowinning electrolytes typically contain a high background of metallic impurities. The effect of metallic ions on the properties and accompanying change in the limiting-current density for copper reduction have been the subject of several studies. Although various empirical correlations have been published for describing the physicochemical properties of electrowinning electrolytes, the correlations are only applicable to a limited range of conditions and cannot be extrapolated without further validation. Consequently, in this paper we validated existing physicochemical property correlations for the full range of operating conditions applicable to direct copper electrowinning and developed a new correlation for predicting the associated limitingcurrent density for copper deposition. Following, we evaluated the benefit of using the validated correlations as a component of a dynamic electrowinning model.

Jan 1, 2023

By M. Buchmann, T. Mütze, F. Heinicke

Dry air classification is a well-known technique used for decades in the cement industry to separate material in the size range of 0.01-1.0 mm. Additionally, in corresponding dry grinding circuits with effective machines such as High Pressure Grinding Rolls (HPGR), the energy consumption can be reduced compared to wet applications. These dry systems are not state of the art in minerals processing plants, but first prototypes have been installed and an increasing number of projects are starting to evaluate this option. One challenge in this field is the mineral composition of ores, which have, by far, a higher variety in density and size than those of cement. High density particles such as iron- containing ones have higher settling rates than low density silica particles of the same size. The main question to answer in this paper is how to evaluate this effect, so a quantitative method using Mineral Liberation Analyses was developed to calculate two-dimensional partition curves. Additional statistical analyses allow for isolation and quantifying the interaction of density and size, enabling engineers to consider this effect for the sizing of process plants. The paper will present the method and selective results for a compounded ore of iron and silica. Keywords: HPGR, air classification, partition curve, MLA

Jan 1, 2020