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By T. Matlou, S. Myendeki, V. Midzi, T. Zulu, H. Mabotja, T. Mulabisana, B. S. Zulu, L. Hlatshwayo, T. Makhateng

The Council for Geoscience (CGS) performed a macroseismic investigation following the occurrence of an earthquake in the Boksburg area on 11 June 2023. The event had a magnitude of ML 4.4 and a focal mechanism that showed the event as having strike-slip motion along a northwest-southeast oriented fault. The event resulted in aftershocks, some of which occurred away from the causative fault in the east in an area without a mapped fault. However, the cluster of past events in that area suggests that there is an active fault. Due to the size of the main earthquake, a macroseismic survey was conducted to determine its impact on the community in the region. Analysis of observed data obtained from questionnaires resulted in the creation of 153 intensity data points. Their distribution showed high intensity values close to the earthquake source area. However, the investigation highlighted a number of anomalies, such as the higher than expected intensity values observed far from the event epicentre. It could be that these anomalies are caused by site conditions, for example, amplification of ground motion due to thick soil layers.

Jan 12, 2025

By D. Moses, J. A. Onyango

Carbonatites are generally competent rock masses with rock mass rating class II rating 60–74. In spite of their competency, they tend to be affected by weak features like manganese-iron veins and/or in situ rock damage due to brecciation associated with carbonatite complexes. Rock slope failure in such hard rocks is complex since such structures within the rock mass form weak links that could potentially control slope instability. In this contribution, a numerical simulation using phase2 v 7.0 was carried out to investigate the influence of in situ rock damage on the stability of mine pit walls. The outcome reveals that, the existence of breccia in the competent rock mass has the capability to reduce the slope stability performance particularly at gentle dipping angles of emplacement in close range to the slope toe. However, as the emplacement position of breccia moves away from the pit wall, the stability performance increases at gentle dipping angle <50º. On the contrary, at the dipping angle of 50° the performance of slope reduced, and at steeper angles >50° the impact becomes negligible. Thus, from a series of analyses, mine design in brecciated rock masses, the ratio of 1:5 between the breccia distance from slope toe and pit depth should be implemented to counter its impact, and if the breccia is within or close to the pit limit, a deliberate effort must be made to mine it out.

Sep 1, 2025

By O. T. Konina, V. A. Masloboev, A. V. Svetlov, E. A. Krasavtseva, D. V. Makarov, A. A. Goryachev

Dusting phenomena have been examined at the tailings storage facility of Apatit JSC Kirovsk, a mining operation located in the far north of the Russian Federation. The material composition of the tailings was identified. Existing dust suppression methods were examined. Field observations were undertaken and official data was obtained from the Murmansk Administration for Hydrometeorology and Environmental Monitoring, and analysed. A database was built for forecasting dusting according to critical scenarios in order to estimate the peak MPCs of suspended solids in the atmospheric air. Mitigation measures were formulated and recommended to the mining operation. Keywords: Mineral dust particles, apatite-nepheline ore concentration tailings, suspended solids MPC, climate change

Jan 1, 2020

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 C. C. Johnson

In the fourteen years that Rössing Uranium Limited has been in production, the metallurgical operations and controls on the leaching plant have evolved through four basic stages. Initially, the emphasis was placed on the achievement of consistent plant operation by overcoming severe startup difficulties. The second stage involved the attainment of the design operating targets, and also the commissioning of the ferric-leaching reactors in order to achieve a ferric ion concentration of more than 3,0 g/l. Improvements in control then became the priority, with the emphasis on consistently achieving the target concentrations of ferric ions, total iron, and terminal acidity. The latest phase has concentrated on the optimization of costs by means of adjustments to the historically established operating parameters in order to achieve large savings on consumables while maintaining the leaching efficiencies. Apart from the obvious incentive of reducing costs in an inflationary economy and a depressed uranium market, impetus for this work was given by a change in the type of ore from the open pit, which has the effect of reducing the extraction efficiency while increasing the consumption of consumable materials. These problems and their solutions are discussed in detail, and the importance to cost-effective optimization of an accurate, up-to-date cost-reporting structure is stressed.

Jan 1, 1990

By P. Otto, G. Borm, Th. Dickmann, F. Amberg, R. Giese

Based on many years experience, the well proven Swiss Tunnel Seismic Prediction System TSP has been substantially augmented for online geological prognosis in underground construction. In its latest version, the Integrated Seismic Imaging System ISIS provides high resolution seismic images of the rock mass around a tunnel face via an array of standard anchor rods. These rods contain 3D-geophones at their tips and can be readily installed during excavation work. A further innovative component of the system is the newly developed high-power repetitive source for application in hard rock: a pneumatic hammer with laser triggering to be mounted on construction machinery. A user-friendly software package permits online data acquisition and processing, 3D-visualization, and a first geological interpretation. Tomographic images of compressional and shear wave velocity fields at fault zones in metamorphic rock of the Gotthard Base Tunnel in the Central Alps are presented. Das langjährig bewährte Schweizer Tunnelseismische Vorauserkundungssystem TSP wurde inzwischen wesentlich weiterentwickelt. In seiner neuen Version, dem Integrierten Seismischen Imaging System ISIS, ermöglicht es hochauflösende seismische Abbildungen des Gebirges im Vorfeld und Umfeld einer Tunnelauffahrung mit Hilfe einer Anordnung von Felsankern, die an ihren Spitzen 3-Komponenten-Geophone enthalten. Eine weitere Neuerung von ISIS ist die pneumatische Hochleistungs-Impulsquelle mit Laser-Triggering. Eine benutzerfreundliche, interaktive Software ermöglicht die online Datenerfassung und -auswertung, 3D-Visualisierung und eine erste geologische Interpretation. Tomografische Abbildungen von Kompressions- und Scherwellengeschwindigkeitsfeldern an Störungszonen in metamorphem Gestein des Gotthard-Basistunnels werden gezeigt. Basé sur de nombreuses années d’expérience, le système suisse, bien établit, de reconnaissance sismique à l’avancement des tunnels (système TSP), a été sensiblement amélioré pour obtenir une prévision géologique en temps réel durant l’avancement de travaux souterrains. Sa dernière version, le Système Intégré d’Imagerie Sismique (ISIS), fournit des images sismiques haute-résolution du massif rocheux à l’avant d’un tunnel grâce à un réseau de tiges d’ancrage standard. Ces tiges, équipées à leur extrémité de géophones 3 composantes, s’installent très aisément durant les travaux d’excavation habituels. Le élément d’innovation récente concern le nouvelle source très répétitive et de forte puissance pour les applications aux roches dures: un marteau pneumatique déclenché par un système à laser. Un ensemble de programmes informatiques convivial permet l’acquisition et le traitement en temps réel des signaux et produit une vue 3D ainsi qu’une première interprétation géologique. Nous présenterons des images de réflexion d’ondes de compression et de cisaillement ainsi que des inversions tomographiques de zones de faille dans des terrains métamorphiques obtenues à l’occasion du creusement du tunnel de base du Gothard, dans les alpes centrales.

Jan 1, 2003

By K. Hodgson, Cook. N. G. W.

Most structures are designed so that the possibility of failure is eliminated. However, some degree of failure in the rock around deep mine excavations is inevitable if mining operations are continued. The presence of failed rock constitutes a hazard the magnitude of which can be predicted by computer models from calculations of the energy change per unit area mined in stopes, or the field stress around service excavations. Empirical relationships between these calculable quantities and the incidence of rock failures and delays associated with them have been established. Experiments on the computer using different layouts enable the mining engineer to select the least hazardous of otherwise acceptable alternatives, and to predict the incidence of damage ahead of actual mining, so that appropriate measures to maintain an adequate degree of safety and productivity can be planned in advance.

Jan 1, 2014

By J. Mulenshi, J. Rosenkranz, P. Khavari, S. C. Chelgani

The geometallurgical concept has mainly been applied to primary ore deposits, starting from ore characterisation to the economic optimisation of the mining operation. However, as primary ore resources are becoming depleted and lower in grade, alternative sources need to be explored and a question of adaptability of the geometallurgical approach to the secondary resource repositories arises. The particle size distribution, chemical and mineralogical compositions of the Smaltjärnen historical tungsten tailings from physical separation in Yxsjöberg, Sweden were studied using drill core samples collected from different locations within the tailings repository in order to assess the amenability of the tailings to reprocessing. The tailings are dominated by the –600 to +149 μm particle size fraction. This fraction contains most of the elements of interest (W, Cu, S, Sn, Zn, Be, Bi and F) hosted by scheelite, chalcopyrite, pyrrhotite, cassiterite, danalite (both Zn and Be), bismuthinite and fluorite, respectively. The particle size distribution and mineralogical composition vary across the repository, suggesting a possible existence of geometallurgical domains, which require further assessment to evaluate metallurgical performance. Keywords: Historical tailings, tungsten, scheelite, geometallurgy, characterisation, mineralogy, reprocessing

Jan 1, 2020

By E. K. Mutinda, D. K. Maina, R. M. Kasomo, B. O. Alunda

Assessment of blast fragment size distribution is critical in mining operations because it is the initial step towards mineral extraction. Different empirical models and techniques are available for predicting and investigating the consequences of blasting, one of which is the Kuznetsov Cunningham-Ouchterlony (KCO) model. In this paper we summarize the advances in the empirical models from inception until now, and explore the improvements that have been made so far with particular emphasis is on the most recent KCO model. Utilization of the model and the errors that arise between expected and the actual outcomes are analysed. The results indicate that the KCO model remains useful for predicting the blast fragmentation at limestone mine sites, despite the availability of other advanced prediction models. It is also a valuable instrument for pre-surveying the impact of varying certain parameters of a blast plan.

Mar 1, 2021

By C. Massola, E. E. M. N. de Guzmán, M. G. Bergermana

The abrasiveness of a mineral or rock is an extremely important topic in the mining industry and is generally measured by the Bond abrasion index (AI). However, to determine such an index by the Bond test requires 1,600 g of sample with particle sizes ranging from ½” to ¾”, which are not available in certain situations, such as ore prospecting, drilling, and geometallurgical studies. In order to investigate the abrasiveness of smaller-sized sample materials, a modified LCPC test was developed, which allows testing fine materials (i.e., 1.0 mm or smaller) to predict wear in ore processing circuits and anticipate possible failures resulting from changes in abrasive characteristics of the ore being processed. The results for 16 different materials indicated a good correlation with the AI and the modified LCPC, resulting in a reliable alternative for the AI. Keywords: Bond Abrasion Index (AI), LCPC, abrasiveness

Jan 1, 2020

By M. T. G. Davis, J. V. Cleasby, H. J. Wright

Mining practice in the Kimberley Division of De Beers Consolidated Mines Limited by J. V. CLEASBY. B.Sc.. A.R.S.M. (Fellow). H. J. WRIGHT. B.Se.. M.Sc.. (Fellow). And M. T. G. DAVIES. B.Sc. (Visitor) T his paper highlights the changes that are taking place at De Beers Consolidated Mines Limited in mining methods, mechanization, and employment practices. De Beers has four underground mines in Kimberley itself (Dutoitspan, Bultfontein, De Beers, and Wesselton), and two open-cast mines outside Kimberley (Finsch and Koffiefontein). Emphasis is placed on the new method envisaged for Koffiefontein when it becomes an underground mine. The paper also includes notes on chemical drilling and on winding practices.

Jan 12, 1975

By B. K. Loveday

The use of large flotation machines is well established, resulting in substantial savings in both capital and operating costs. Therefore, when a new plant is designed, laboratory and pilot-plant tests should be used to simulate large flotation cells, or appropriate scale-up factors should be employed. &apos;Conference on titanium The Fifth International Conference on Titanium will be held from 10th to 14th September, 1984, in Munich, West Germany, organized by the Deutsche Gesellschaft fur Metallkunde e.V., in association with the American Society for Metals, Societe Francaise de Metallurgie, The Academie of Sciences U.S.S.R., The Japan Institute of Metals, The Metallurgical Society of A.I.M.E., and The Metals Society.

Jan 1, 1983

By G. Mucsi, F. Kristály, R. Szabó

Kaolin is one of the most important ingredients in porcelain manufacturing. Its main phase is clay mineral containing aluminum hydrosilicate, namely kaolinite. Beside kaolinite it also contains quartz, illite and feldspars, which impair its applicability. Kaolin is a non-reactive material, but metakaolin can be produced by heat treatment (calcination) of kaolin, which is also used by the cement and concrete industry due to its latent hydraulic (pozzolanic) properties. Beside thermal activation, reactive materials can also be produced by mechanochemical activation in general. This paper deals with the mechanochemical activation of kaolin. The raw material was classified into various size fractions, then ground in a batch stirred media mill under varying circumstances (residence time, circumferential velocity). After grinding, the structural changes of the products were investigated by X-ray diffractometry (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). In addition, the particle size distribution of the ground material was determined by laser scattering. As a result of the grinding experiments and analytical measurements of the products, it can be clearly seen that reactivity of kaolin can be improved significantly by mechanical activation in a stirred media mill, but due to its high energy density the circumstances were optimised carefully to avoid aggregation. Keywords: Kaolin, grinding, stirred media mill, mechanical activation, material structure

Jan 1, 2020

By M. Mpofu, M. van Schoor, T. Kgarume, H. Grobler

The South African mining industry has committed to achieving a state of zero harm for its workforce, with a strong emphasis on worker health and safety. Among the major safety concerns are falls of ground, a leading cause of injuries and fatalities. Ground-penetrating radar, a non-destructive geophysical method, is recognised for its ability to image structures, fractures, and geological features within the rock mass. However, ground penetrating radar data is often acquired in local coordinates, posing challenges for visualisation in mine computer-aided design or three-dimensional visualisation software. This study explores the pivotal role of light detection and ranging data in transforming ground penetrating radar data from local survey coordinates to absolute mine coordinates. A comprehensive georeferencing methodology is presented, providing the stepwise progression from the initial georeferencing of ground penetrating radar data to the ultimate integration of ground penetrating radar and light detection and ranging datasets, resulting in the creation of a ground penetrating radar-light detection and ranging three-dimensional model. The proposed approach not only facilitates the integration of but also offers a practical means of visualising the integrated datasets within commonly used computer-aided design or three-dimensional visualisation software. An essential aspect of this integration is the adoption of non-proprietary data formats, specifically American Standard Code for Information Interchange text files, ensuring broader accessibility and compatibility. The potential for integrating diverse datasets to construct insightful models of the underground mining environment is illustrated. Integration of different datasets has the potential to offer a holistic understanding of the mining environment, providing essential information to decision-makers.

Jul 23, 2025

By J. E. Dickinson, R. Campbell, M. J. Cole, K. P. Galvin, M. C. Cole

It is common practice in the beneficiation of iron ore ultrafines to apply reverse flotation, and hence float the gangue minerals, leaving behind a high-grade iron ore product. Given the difficulty in floating particles finer than 20 μm, especially those finer than 10 μm, it is necessary to subject the feed to desliming ahead of flotation. There are two problems with this approach. Firstly, given the known inefficiencies of cyclones, desliming needs to be aggressively applied to particle sizes upwards of 45 μm to ensure all the offending ultrafine gangue is removed. Secondly, desliming also removes a significant portion of the valuable iron ore. Thus, a significant portion of the ultrafines, including the iron ore, is lost to the tailings. This paper examines the direct flotation of iron ore fines using the Reflux Flotation Cell. The RFC operates using a concentrated bubbly zone, in the absence of a conventional froth zone, for delivering strong counter current washing through an inverted fluidised bed of bubbles ahead of the product discharge. A system of parallel inclined channels in the lower part of the cell provides enhanced segregation of the bubbles from the tailings, preventing the loss of air bubbles into the tailings. Experiments conducted under semi-batch conditions produced encouraging results with concentrates of ~65% Fe grade in a single flotation stage. Comparatively, up to five successive batch flotation stages were required when using a laboratory scale batch mechanical flotation cell to achieve similar Fe grades. For a given grade, lower Fe recoveries were typically achieved by the RFC. This was attributed to the effective prevention of ultrafine particles succumbing to hydraulic entrainment under a positive bias flux, as well as an increasing feed volume involved in the semi-batch operation using inverted fluidisation water for cleaning. Overall, similar grade-recovery curves were produced, however, significantly higher grades were obtained by the RFC and with fewer separation stages. Keywords: Desliming flotation, iron ore, modified release analysis, reflux flotation cell

Jan 1, 2020

By M. N. Mathabathe, A. S. Bolokang, C. W. Siyasiya, R. J. Mostert, G. Govender

The b-solidifying g-TiAl intermetallic alloys of nominal composition Ti-48Al (binary alloy), Ti-48Al-2Nb (ternary alloy), Ti-48Al-2Nb-0.7Cr (quaternary alloy), and Ti-48Al-2Nb-0.7Cr-0.3Si (quinary alloy) (in at.%) were developed. The materials produced were tensile tested at room temperature. The as-cast microstructures and fracture surfaces of the tensile tested specimens were examined using conventional metallographic methods. Microstructural examination indicated that the alloys were comprised of lamellar structures (a2+g) embedded in columnar dendritic cores in the as-cast condition. However, the quinary alloy contained a Ti5Si3 second phase. The alloys exhibited no detectable ductility during tensile deformation, indicating the brittleness of all the materials. The fracture surfaces revealed that the alloys failed by translamellar fracture with correspondingly few cleavage facets.

Apr 1, 2021

By E. Marè, D. R. Groot, R. Engelbrecht, T. Coetsee

Hydrogen peroxide is often used as an oxidising agent in experimental waste electronic equipment (WEE) leaching work. However, the high cost of peroxide is a negative factor in its consideration in further process development. A few studies have reported on the efficient application of peroxide addition schedules to ensure optimum reagent consumption. Large quantities of unleached substrate material contained in WEE feed material result in a large dead volume of material in the leaching reactor. This factor necessitates fast reaction rates to enable the use of a high feed material throughput reactor to enhance overall project viability via hydrometallurgical processing. In this study the effects of hydrogen peroxide addition schedules on base metal leaching efficiency and solution temperatures were tested at laboratory scale. The results showed that overall peroxide consumption can be optimised to lower levels by matching peroxide additions to the particular feed material’s leaching behaviour. A simplified integrated model for peroxide decomposition is used to explain its effect on solution temperatures and leaching rates. Keywords: Peroxide consumption, waste electronic equipment, copper leaching, integrated model

Jan 1, 2020

By P. Lloyd

Perceptions of disaster caused by burning fossil fuels have reached such a pitch that they seriously threaten the very future of the industry. Coal is a dirty word. A leader in Business Day(January 192009) claimed ?There is no disputing that renewable and non-polluting energy sources are preferable to the country?the true cost of so-called cheap coal-fired power stations is neither reflected nor accounted for by Eskom?the true and immediate but unacknowledged cost of continued coal mining is apparent in the catastrophic level of acidification from mining runoff of all significant natural water resources in the country?and their waters have been rendered unfit for human consumption. Air quality is in a similar state with?increases in pulmonary disease causing workforce absenteeism and compromised childhood development, among many other health problems recorded in areas polluted by coal mining.? The upshot is that our latest coal-fired power station, Kusile, is being required to use flue gas desulphurization. The costs are considerable, and the benefits minimal. Meanwhile, exports are being threatened by EU directives and an assumption that South African coal gives off excessive quantities of SOx and NOx when burned. The industry needs to arm itself with clear responses to these and similar misconceptions, and to communicate those responses loudly and clearly, if it is to survive.

Jan 1, 2011

By S. T. L. Harrison, M. Smart, C. J. Edward

Biooxidation, a biohydrometallurgical process, utilizes a mixed microbial consortium to mediate the dissolution of refractory gold-bearing ores to enhance gold recovery during cyanidation. Recognition of water as a critical resource has prompted improved water management strategies within mining and minerals processing. Bioremediated wastewater from the cyanidation tailings provides a potential water source to supplement the water required for the biooxidation circuit, reducing freshwater extraction. Gold biomining operations have typically been reluctant to recycle this wastewater due to the potential inhibitory effects of cyanide and thiocyanate (SCN-) on the microbial population. Historical process upsets suggest that the microorganisms are sensitive to SCN- concentrations as low as 1 mg/L. However, effective bioremediation processes resulting in effluents with low or negligible SCN- concentrations may allow gold biomining plants the opportunity to recycle available water. Microbial activity as well as alteration in community structure were monitored as a function of increasing SCN- concentration over the range of 0 mg/L to 5 mg/L to investigate the response of the biooxidation community to potential SCN- spikes resulting from upsets in the remediation process. Appropriate microbial growth and ferrous iron oxidation activity with a nominal shift in community structure were observed at SCN- concentrations up to 1 mg/L. Thiocyanate concentrations above 1 mg/L resulted in the complete inhibition of ferrous iron oxidation activity. This was attributed to Leptospirillum ferriphilum’s sensitivity to SCN-. Exposure to a SCN- concentration of 5 mg/L resulted in a lower cell concentration and a significant increase in growth lag time, and the absence of L. ferriphilum from the microbial population. At. caldus and Ap. cupricumulans were still present at 5 mg/L SCN-, although Ap. cupricumulans was unable to oxidise ferrous iron at this SCN- concentration. It was concluded that recycling bioremediated cyanidation tailings wastewater within the biooxidation circuit is feasible; however, to retain process performance, SCN- concentrations should not exceed 1 mg/L. Keywords: Biooxidation, thiocyanate, water recycling, community structure

Jan 1, 2020

By Z. L. Xue, J. L. Li, X. Y. Wang

"In low-carbon energy-efficient basic oxygen furnace (BOF) steelmaking processes, limestone partly or completely replaces the active lime. The effects of limestone calcination temperature (1200–1500°C) and time (5–15 minutes) on lime reactivity and CaO grain size were investigated. The reactivity was evaluated by titration with hydrochloric acid, and the CaO grain size was analysed using scanning electron microscopy. The results revealed that for calcination temperatures higher than 1300°C, the reactivity reached a maximum and then decreased . The higher the temperature, the earlier the peak of reactivity appears. The CaO grains grow with increasing temperature and time, which leads to the decrease of reactivity. Notably, the effects of temperature on CaO grain size and reactivity are more marked than that of time. To obtain active lime calcined at ultra-high temperature by flash heating, the calcination conditions should be 1300–1400°C for 10–15 minutes, or 1400–1500°C for 8–10 minutes. IntroductionLime is one of the most important slag-making materials for dephosphorization and desulphurization in the basic oxygen furnace (BOF) steelmaking process. The reactivity of lime is a measure of its capability to take part in slag-making. Lime having a reactivity of more than 300.0 mL (4 N HCl), determined by hydrochloric acid titration is generally referred to as active lime (Rusjan et al., 2007; Zeman, 2008). At present, the active lime used for BOF processes comes primarily from a kiln or shaft kiln, where limestone is preheated at 700– 900°C, and then calcined at 1050–1200°C (Drenhaus et al., 2010; Oates, 2007)."

Jan 1, 2016