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By K. Naidoo, M. Pelser, J. Hagemann, K. C. Sole

The copper tankhouse at Rustenburg Base Metals Refinery is an essential component of the Anglo American Platinum value chain. The tankhouse uses starter-sheet technology that was adopted in the 1980s, so dependence on manually intensive labour and overall operational excellence has a significant impact on process performance. An efficient, stable, and sustainable electrowinning process contributes to minimising energy consumption and reducing operational costs, and enables improved product quality and increased throughput. Historic performance of this tankhouse has often been suboptimum over prolonged periods. An in-depth operational review of performance from 2018–2024 was carried out to understand challenges, risks, and high-impact factors that contribute to poor performance. Implementation of adherence to fundamental operational basics identified from global best practice, such as the frequency and quality of cell cleaning and maintenance, preventing backlogged harvesting or maintenance, preserving cell-top furniture conditions and integrity of electrodes, preventing short circuits and poor current distribution, and maintaining a high level of operational discipline, has since contributed to an era of exceptional performance. Root-cause analysis fault trees pertaining to poor current efficiency and high scrap rate are summarised. Current efficiency has significantly improved since 2021, now consistently exceeding 88%. The copper scrap rate, previously believed to be limited to a minimum of 4%, achieved a historic monthly low record of 2.06% in 2023. Chemical and physical quality has considerably improved, and cathodes exhibit minimal morphological defects.

Jun 27, 2025

By M. B. C. Brandt

Richter magnitudes for seismic events were calibrated for use as a Local magnitude scale in the West Rand (WR), Far West Rand (FWR), and Klerksdorp–Orkney–Stilfontein–Hartebeesfontein (KOSH) gold mining areas. Richter magnitudes are currently calculated from seismograms recorded by local surface cluster networks using tabulated calibration values for Southern California, published in 1958. The Richter (1958) model is incorrect for distances of less than 30 km and should be applied only to crustal earthquakes in regions with similar attenuation properties to those of Southern California. When compared to the South African National Seismograph Network (SANSN), the cluster networks, on average, overestimate seismic event magnitudes by approximately 0.1 of a magnitude unit. A calibrated Local magnitude scale was derived by means of a multiple regression analysis between the Local magnitudes reported by the SANSN and the largest zero-to-peak trace amplitudes measured on the cluster network horizontal seismograms, after modelling the attenuation of the seismic waves as these progress from the epicentre to the station position. Magnitudes reported by individual stations for the same event show a significant scatter around the average magnitude owing to the near-surface amplifications of the seismic waves at the recordings sites. Average magnitude should be estimated using as many magnitudes of individual stations as possible to ensure an accurate estimate. Larger event magnitudes should be compared with those recorded by the SANSN.

Nov 1, 2021

By S. W. Jacobsz, Y. Narainsamy

Several high-impact tailings dam failures around the world in recent years have placed a renewed focus on the stability of tailings dams and pointed to potential shortcomings in traditional drained design and safety evaluation procedures. A need to consider undrained shear strength in the design of tailings facilities has become apparent. However, there are specific requirements that need to be met before undrained shearing occurs. In South Africa, the last major failure was likely the Merriespruit disaster in 1994, which leads to the question of whether the conditions required for undrained shearing are readily applicable to South African tailings dams. This paper describes research at the University of Pretoria that has recently commenced to further investigate the conditions required for undrained failure to occur. The research includes laboratory and field testing to replicate these conditions in the laboratory and relate them to those found in an active tailings dam.

Jun 2, 2022

By S. Dey, C. Bhar, S. K. Mandal

Loading and hauling of ore and waste are the key operations of an opencast coal mine and entail a high operational cost. The productivity of a mine can be increased by reducing the cycle time of loading equipment as well as utilizing dumpers optimally. In this paper we discuss the impact of rock type, bucket fill factor, rock fragmentation, the height of the cut, and angle of swing of the bucket on shovel performance. A time study is conducted on shovels in an opencast coal mine with experimental blasts of rocks to assess the impact of different factors on the performance of the shovel. Based on the data, the authors applied multiple regression (MR) and artificial neural network (ANN) techniques to develop different models for the prediction of the shovel cycle time. Developed models are validated by comparing the predicted data with actual field data. With the help of the best model, the plausible fleet size is determined in order to utilize the shovel and dumper optimally and to improve the performance of shovel–dumper operation.

Oct 1, 2022

By N. Naude, L. S. Leal Filho, M. P. Tshazi

In this paper, the authors performed experiments in the Denver and Leeds laboratory flotation devices at the University of Pretoria at various particle sizes to evaluate the performance of the devices. Quartz was used in a single mineral system at discrete sizes fractions, -25 μm, +25- 45 μm, +45-75 μm, and +75-106 μm. Hydrodynamic analysis, based on dimensionless power and Reynolds numbers, indicated that the Leeds cell required higher power input to achieve comparable flow conditions. Specifically, the Leeds cell exhibited an average power number of 1.03, whereas the Denver cell averaged 0.77 within the same impeller speed range of 1000 rpm–1500 rpm. For comparative flotation performance, impeller speeds were calibrated, resulting in operating speeds of 1200 rpm for the Denver cell and 1400 rpm for the Leeds cell. The cells performed similarly at two coarser-sized fractions. However, some deviations were observed in the finer particle size range. The -25 μm (fine) fraction initially achieved a recovery of only 15%. An additional reagent dosage was required to enhance the recovery of this fraction significantly. These findings highlighted the influence of particle size on flotation recovery. For all experiments, the Denver laboratory flotation cell outperformed (defined by higher recovery) the Leeds device, while still operating at a lower impeller speed. This advantage can be attributed to its impeller-stator design and air dispersion features, effectively overcoming slurry resistance and resulting in superior flotation performance compared to the Leeds cell.

May 27, 2025

By C. H. Wyndham, N. B. Strydom

INTRODUCTION Acclimatization of the labour force to heat is an integral aspect of gold mining in South Africa. A recent survey revealed that about 250,000 Bantu mine workers require to be acclimatized to heat each year. Until 1965 men were acclimatized by means of one of the Chamber of Mines methods (introduced by the Human Sciences Laboratory in 1953). This type of acclimatization was carried out underground where men shovelled rock in hot stopes under careful supervision. However, it has become increasingly difficult in the last few years for mines to provide underground the conditions of work and environmental heat required for adequate acclimatization to heat. In examining an alternative to acclimatization in underground hot stopes, the Human Sciences Laboratory carried out a trial in 1965 of acclimatization in an air-conditioned climatic room on the surface of a mine. The new procedures developed from this trial have been so successful that there are today 26 climatic rooms on different mines. These rooms have been built following a design proposed by Mr Hodgson of the National Mechanical Engineering Research Institute1. Approximately 85 per cent of the total number of men being acclimatized each year are put through the new procedures in these climatic rooms. This paper gives an account of the problems which arose and how they were solved, the inter-relationship between physical conditioning and climatic room acclimatization, the prodecures developed for elimination of labourers with low maximum oxygen intakes, and the advantages of climatic room acclimatization. CLIMATIC ROOMS The majority of the climatic rooms (twenty) have been built on the surface, but a number (six) of mines preferred to establish their acclimatization centres underground in order to decrease the initial costs involved in the construction of such facilities. These underground climatic rooms are usually located near shaft stations in redundant haulages and they can accommodate from 200 to 400 labourers, thus eliminating the need for multiple acclimatization shifts. Figs. 1-4 illustrate various aspects of a surface climatic room. PROBLEMS WHICH AROSE IN INTRODUCING CLIMATIC ROOM ACCLIMATISATION There were four main problems which arose in connection with the introduction of the new method. These were: (i) The type and rate of work to be used. (ii) The air conditions required to obtain optimum acclimatization. (iii) The duration of exposure to heat each day and the total number of days of acclimatization. (iv) The methods of cooling labourers with high body temperatures. Shovelling rock would have been the desirable type of physical work to employ, but the air-conditioned space required to accommodate large numbers of men and the difficulty in standardizing the work rate in shovelling led to the decision to employ instead the work procedure used by the Human Sciences Laboratory in acclimatizing men in the Laboratory. This is the lifting of the body weight against gravity when men step on and off a bench. It has the advantage that large numbers of men can work physically at the required rate in a relatively small space (120 men can be accommodated in an area of 70 ft by 21 ft) and the cost of construction and ventilation of the climatic rooms is thereby reduced. Also the work rate can be standardized by varying the height of the stepping benches in relation to the individuals' body weights. The next problem was the air condition to be used in the climatic rooms. The Laboratory's research experience in acclimatization led it to choose an air temperature of 89°F (with the air almost saturated with water vapour) and an average velocity of air movement of 100 fpm. This air condition was combined with a work rate of 1,560 ft lb/min (oxygen consumption 1.0 litre/min) on day 1, and the work rate was increased gradually over the period of acclimatization to reach a work rate of 3,120 ft lb/min (oxygen consumption 1.6 litres/min) on day 9.

By Q. Liu, S. Liu, Y. Cui

To reduce the frequency of mining incidents and improve safety and production efficiency, it is important to develop technology for the autonomous positioning and navigation of mining equipment, without the assistance of satellite navigation signals. In this study we review the current technological environment for positioning and navigation underground and present several integrated navigation strategies. Existing underground positioning and navigation technology is described, and the performances of different methods based on this technology analysed and compared. The combination types and positioning effects of underground positioning and navigation strategies are discussed. Recent research directions for filtering methods and positioning estimation algorithms for underground positioning and navigation are reviewed. Finally, we summarize the future direction of underground positioning and navigation technology and related algorithms.

Jun 1, 2021

By T. Fabritius, L. Hekkala, J. Härkki

The Outokumpu steel belt sintering technology is used for manufacturing chromite pellets that are charged into smelting furnace for ferrochromium production. Hot air is blown through the moving bed of raw pellets. Direct temperature and flow measurements are difficult to do in the bed of a real scale belt sintering process. Therefore, a tested and reliable mathematical model would be a valuable help for optimising operational parameters of the process and designing new constructional improvements. The aim of this work is to present a mathematical model that calculates the gas flow and temperature distribution in the bed of pellets and the atmosphere. Computational fluid dynamics program FLUENT is used to calculate the gas flow, composition and temperature of the gas in the sintering bed during processing. Energy equation for the bed, containing the effects of evaporation of water and oxidation of carbon and iron oxide, will be added to the model to obtain the temperature of the pellets. The porous media model used for pressure drop calculations in the bed is shortly discussed. A comparison between CFD-calculations and experiments with a pilot scale batch-sintering reactor are also presented. The final model can be used as an engineering tool when developing the process and the equipment further. Different designs can be easily tested with the model and the effects of the changes to the flow pattern and temperature distribution can be studied.

Jan 1, 2004

By N. V. Moraka

Calls for transformation in the mining sector are legislated. Whilst the composition of boards in terms of gender diversity and equal representation has improved, little is known on how women directors experience boardrooms. This research investigated the experiences of South African women in male-dominated mining boards. It questions why women remain marginalised in boardrooms, even when they are qualified as the men in their respective fields. The experiences of South African women on male-dominated mining boards were investigated by means of a multiple case study using a qualitative research methodology. Interviews were conducted with 16 women and 12 men serving across six JSE-listed South African mining companies. The findings show that irrespective of their qualification and experience, women,s, contributions are often ignored, and they are assigned to more social roles. Regardless of race, all women experienced gender stereotyping. Strategies are required to ensure that board cultures embrace female talent, where women can effectively contribute to decision-making and maximize their talent. It is argued that gender and identity should be studied in relation to post-colonial history in African countries. Women have multiple, varying identities, and their experiences require a unique investigation that would enable strategies to overcome barriers, through the implementation of an appropriate diversity management programme.

Feb 12, 2024

By J. C. Vreugdenburg, B. A. Dippenaar, J. Muller, T. L. de Vries

Iron ore fines are agglomerated to produce sinter, which is an important feed material for blast furnaces worldwide. A model of the iron ore sintering process has been developed with the objective of being representative of the sinter pot test, the standard laboratory process in which the behaviour of specific sinter feed mixtures is evaluated. The model aims to predict sinter quality, including chemical quality and physical strength, as well as key sinter process performance parameters such as production rate and fuel consumption rate. The model uses the finite difference method (FDM) to solve heat and mass distributions within the sinter pot over the height and time dimensions. This model can further be used for establishing empirical relationships between modelled parameters and measured sinter properties. Inputs into the model include the feed material physical properties, chemical compositions, and boundary conditions. Submodels describe relationships between applied pressure differential and gas flow rate through the bed of granulated fine ore particles, combustion of carbonaceous material, calcination of fluxes, evaporation and condensation of water, and melting and solidification. The model was applied to typical sinter test conditions to illustrate the results predicted, and to test sensitivities to parameters such as feed void fraction, feed coke percentage, and the fraction of combustion heat transferred to the gas phase. A model validation and improvement study should follow, ensuring sinter test results are free from experimental errors by conducting repeated tests.

Jan 1, 2015

By B. Ceki, A. Mabentsela

The BCL furnace is scheduled to restart operations after being placed on care and maintenance in 2016 due to depressed nickel prices. The decision to start operations after such a stoppage ought to be led by a techno-economic evaluation of process options to make operations more resilient. For BCL, the decision lies between using the existing flash-smelting furnace (FSF) or a top-submerged lance (TSL) furnace. Available studies show that the FSF combined with other converting technologies is cheaper to operate; however, such studies are based on flowsheet simulation results of single copper concentrates and therefore do not provide a full scope of practical capabilities based on smelter operator skills. Using a t-test on normalized prior operational data from three Cu FSF and two Cu TSL, it was found that the only statistical differences between the operating costs of the FSF and TSL technologies are in the coal use for heating the feed blow and number of rebuilds: the FSF consumes coal to heat the feed blow and the TSL requires 2.4 rebuilds during a course of a single FSF campaign. A summative operating cost comparison over the existing BCL FSF 11-year life shows that BCL can decrease operational costs by some BWP 55.5 million if the operation were to change to the newer TSL technology. The savings derive from reduced coal use, which is normally associated with heating the blow when using the FSF. Despite the TSL carrying added costs of 2.4 rebuilds during a life time of one FSF furnace campaign, the cost associated with the TSL rebuilds of approximately BWP 1.3 million is minimal compared with the overall operational expenditure decrease that BCL will incur on using the TSL technology. In terms of the technology, BCL can have higher Ni–Cu recoveries at lower operational costs by elimination of Ni–Cu losses and eliminating the slag-cleaning furnace by converting to a TSL furnace.

Jul 10, 2024

By S. Durapraj, R. T. Masethe, U. Maqina, A. C. Adoko

This study investigates seismicity and rockburst control within the Merensky Reef and UG2 orebody of an intermediate-depth platinum mine located in South Africa's Bushveld Complex. Utilising a mine-wide seismic monitoring system, over 1,900 seismic events were recorded between April 2023 and May 2024, revealing complex seismic patterns driven by mining-induced stress changes. The largest event, with a magnitude of ML 2.0, underscores the seismic risks associated with mining at increasing depths. Key findings include the spatial and temporal variability of seismic events, with high seismic activity observed near pillars and geological structures. A significant portion of events correlated with pillar and foundation failures. Moment tensor analysis identified dominant failure modes, such as stress-driven fracture closures and dynamic pillar failures. To mitigate risks, the study emphasises advanced support system redesign and rockburst risk assessment using the rockburst damage potential (RDP) method. The research highlights the importance of monitoring, geotechnical compliance, and adaptive designs in enhancing safety and reducing seismic hazards in underground mining operations. The study applied the RDP framework, classifying damage across R1 to R5 scales, where most instances fell into low-risk categories (R1 and R3), indicating minor to moderate damage. However, data limitations and the tabular stoping method's complexity led to inconclusive results, highlighting the need for more robust data and customised risk assessment tools. Despite these challenges, the RDP approach provided valuable insights into rockburst mechanisms and the effectiveness of existing support systems.

Jan 12, 2025

By M. Ksiazek

Keywords: Thermal conductivity, thermal diffusivity, flash method, specific heat capacity, manganese ore Manganese ferro-alloys manufacturing involves a combination of quality raw materials and an energy source to produce high-quality products with low energy consumption. The thermal properties of manganese raw materials such as ores, sinters, and briquettes, are among the many factors that determine the amount of energy needed for processing. Thermal expansion, thermal diffusivity, conductivity, and apparent specific heat capacity of solid samples and compacted powder samples of manganese ores were examined from room temperature to 1000 °C. The effect of porosity (of the materials used) on the thermal properties was also investigated. The laser flash method and a pushrod dilatometer were used.

Jan 1, 2011

By G. Mahieu, L. Perez-Barnuevo, P. Barbeau-Verreault, O. Gravel

Raglan mine is a copper-nickel mining operation, part of Glencore, and located at the northern border of the province of Quebec, in Canada. The concentrator is fed by a mix of four different underground mines, thus it must accommodate periodic variations in run-of-mine mineralisation and composition. In order to concentrate nickel and copper sulphides, the flotation circuit also includes a regrind step at the cleaner stage. This leads to challenges in maintaining optimal recoveries and in diagnosing potential disturbances. This paper advocates for the combination of automated mineralogical analyses, reconciliated mass balances from diagnostic sampling campaigns and innovative multidimensional visualisation to assist in tackling these challenges. Through this approach, it has been possible to quantify the regrind step influence on the liberation of valuable mineral particles in the final flotation concentrate. The methodology also allows for virtual sieving of the products in order to track unit loss in the flotation process. The proposed analysis scheme presents an opportunity to easily diagnose flotation circuit performance based on mineralogical information. Keywords: Flotation diagnostics, multi-dimensional visualisation, mineral liberation analysis

Jan 1, 2020

By K. Woodward, Y. Potvin, B. McFadyen, M. Grenon

Open stoping has become a popular mining method in hard rock mines, not only due to the safety of the method as a non-entry approach, but also because of the high extraction rate and low costs. At mine sites, stope performance is evaluated by calculating stope overbreak using the stability chart. However, limitations of the stability chart regarding the precision of the predictions, nonconsideration of factors such as the influence of blasting, and the exclusion of underbreak have led to non-optimal designs. The capabilities of today's computers have increased the amount of data being collected and the power of models being built. This article presents a step towards a new stope design approach where stope overbreak and underbreak are measured and georeferenced using octrees at an approximately cubic metre resolution and predicted using multivariate statistical models (partial least square, linear discriminant analysis, and random forest). Results show that overbreak and underbreak location along the design surface and their magnitude are predicted with good precision using a random forest model. These predictions are used to build the expected geometry of the open stope. The resolution of the data and the use of multivariate analysis has enabled the prediction of variation in stope performance along the design surface, going well beyond the simple qualitative per stope face prediction provided by a traditional stability chart approach.

Jun 5, 2023

By F. Nakhaei, M. Le Roux, Q. P. Campbell, S. Botlhoko

The results of coal sink and float tests are plotted as washability curves. Analysis of these curves indicates the most effective method by which the coal can be cleaned. Sink and float experiments are samplingdependent, destructive, and use toxic chemicals. The present research introduces an alternative method based on a 3D imaging system called RhoVol, in which the density of individual particles is determined from mass and volume measurements. A quantitative error analysis was conducted on coal sample density measurements obtained by RhoVol, and the main factors influencing the errors identified and investigated. The results show that the drawback of this technique is related to its not being able to detect hidden concavities in the particle, resulting in an overestimation of particle volume. Furthermore, it is difficult to capture the impact of porosity and cracks on the volume of coal particles obtained from 3D silhouette images. This mismatch between the RhoVol data and sink and float test results has led to attempts to apply neural network (NN) and linear regression techniques to produce a fully reliable model for correction and estimation of coal density. The NN approach offers superior predictive capability over linear regression, and the estimated density distribution is in line with the sink and float analysis. The root mean square error in estimation of density using the NN model was less than 0.05 g/cm³.

Aug 2, 2022

By Z. Ruetz

Portable X-ray fluorescence (pXRF) analysis has been widely adopted in the geochemical and environmental field as a cost-saving alternative to standard analyses. This paper outlines the efficacy of a method for indirectly quantifying organic copper content in solvent extraction circuits via stripping of the chelated metal with concentrated sulfuric acid in a single contact and subsequent pXRF aqueous analysis. pXRF analysis is common within the mining industry but presents unique challenges with liquid analysis, the most prevalent of which are briefly discussed. This method was developed specifically for mining operations with regional constraints and limited resources. Providing an in-field alternative to flame atomic absorption spectrophotometry and inductively coupled plasma optical emission spectroscopy, this entirely mobile XRF analysis method produces consistent and accurate results within minutes and at a fraction of the cost.

Jan 1, 2023

By V. V. Getman, V. A. Chanturiya, T. N. Matveeva

Most of the Au and PGM ores in Russia are characterised by a thin mineral impregnation of noble metals in sulfide minerals, and a large variety of mineral forms that lead to high loss of precious metals with fine fractions during flotation. In modern flotation technology, the rational choice of reagents is one of the main trends for selective separation of minerals and effective metals recovery. New data on the selectivity of the thermo-sensitive polymer with specific functional groups (TMPPh) as a flocculant and collector of Au and Pt fine fractions are available. The selective modified collector (DEDTCm) for the recovery of Au and Pt from complex ores is discussed in this paper. Scanning electronic microscopy (SEAM), laser SIM and AFM microscopy, UV and IR spectroscopy were applied to study the adsorbed layer of new reagents on the mineral surface. Flotation tests of TMPPh on the gold-bearing ore of the Olimpiada deposit showed an increase in Au extraction and Au content in the concentrate of the rougher flotation. Using a combination of reagents TMPPh and ButX, the quality of the Au and Pt concentrates increased in 1.7 time with an increase in recovery up to 15 % compared with the traditional reagent mode. Testing of TMPPh polymers in flotation of Pt-Cu-Ni ore at Norilsk Nickel has shown the ability to obtain a concentrate with a higher Pt content. Recovery of platinum is 17% higher than recovery in an experiment without polymer. Application of DEDTCm helped to achieve higher technological parameters in flotation of lowgrade Rt-Cu-Ni ore. Compared to the basic mode Pt recovery was plus 13%, Pd recovery was plus 9% and the content of precious metals in the rougher flotation concentrate increased in 2,5 - 4 times. The studies have been supported by Grants of the President of RF “Scientific School of Academician V.A. Chanturiya” NSh-220.2012.5, NSh-748.2014.5. Keywords: Au and Pt complex ores, flotation, flocculation, thermo-sensitive polymer TMPPh, modified collector

Jan 1, 2020

By B. Clermont

Ball mills are usually the largest consumers of energy within a mineral concentrator. Comminution is responsible for 50% of the total mineral processing cost. In today?s global markets, expanding mining groups are trying to optimize mill performances. Since comminution is concerned with liberating valuable minerals for recovery in the separation process, it is crucial to run the mills at the best operating conditions which lead to good liberation at competitive throughputs with minimum costs (energy and wear). The high availability of the equipment is also essential to maximize production and profit. To reach this key objective, continuous and reliable information about the mill operation is vital. An innovative tool which can deliver information about in-mill dynamics has been developed by Magotteaux. It can provide online and accurate measurements of the degree of grinding ball fill and pulp position for timely decision making and actions. This tool could be used on its own or linked to an automatic grinding ball loading system named Magoload. Therefore, ball load could be kept constant by using direct measurement. This article describes the Sensomag and presents some of the major improvements that can be achieved with it. Some other promising avenues are still to be explored. Keywords: Comminution, process control, process optimization, process instrumentation, online analysis.

Jan 1, 2010

By V. W. Lumadi, S. Nyasha

The mining industry has yet to fully accept and embrace the strategic role of technology and innovation in successful business planning and execution. In this study, we empirically determine the factors that influence acceptance of technology solutions in the mining industry in South Africa, assess critical success factors influencing adoption of advanced technology in the South African mining industry, and explore challenges faced by the mining industry in South Africa in adopting advanced technology in its operations. Thematic content analysis is employed in the data analysis. Results show that critical success factors to the adoption of mining technology include learning culture, knowledge sharing, high labour costs, and behaviour of other firms in the industry; commonly identified challenges include inadequate engagement with external stakeholders, uncertainties, the cyclical nature of the sector, and high risk related to the adoption of unproven technology and performance systems focused on volumetric production. The study encourages mining companies to implement usage of technology. This can be properly done through regular engagement with the Minerals Council South Africa.

Apr 14, 2024