Search Documents

By C. Ndou, T. Mothupi, H. Mandende

The technological advances in efficient, rapid, and non-destructive hyperspectral core logging systems for systematic mineral mapping have led to the discovery and exploitation of new mineral deposits Hyperspectral imaging in the long-wave infrared range has been recently used successfully to identify various phosphatebearing minerals (monazite, xenotime, and britholite), with limited work on apatite associated with mafic-ultramafic layered intrusions. In this study we investigate the effectiveness of a hyperspectral imaging (HSI) system with long-wave infrared (LWIR) bandwidthsto identify apatite in the Upper Zone of the Bushveld Complex. The accuracy of the HSI results was validated by mineralogical and geochemical data. The two apatite-enriched zones detected by HSI suggesting widespread development of apatite throughout the uppermost 600 m of the Upper Zone. The lower apatite-enriched zone is approximately 40 m thick, while the upper apatite-enriched zone is about 23 m thick, consistent with previous thickness determinations by traditional logging and analytical methods. Spectral mixing observed in the response of apatite is ascribed either to the common association of apatite and olivine in these rocks, or to differences between the spatial resolution of the hyperspectral image and the size of apatite grains. The VNIR-SWIR wavelength region did not show prominent spectral features of apatite. Nonetheless, HSI in the LWIR range is effective in mapping apatite and should therefore be considered as an exploration tool. This research advances our knowledge of the reflectance spectroscopy of REE-bearing minerals, which makes it easier to detect, identify, and quantify REE-bearing silicate minerals by HSI.

Feb 6, 2023

By F. T. Cawood

The new mineral royalty regime for South Africa was signed into law in November 2008, with its main objective being to compensate the State for the depletion of public minerals through a royalty charge payable from 1 March 2010. The aims of this paper are to establish the potential impact of mining royalties on State revenues, industry affordability, and explore whether the dual formula system is likely to encourage miners to become refiners. It also measures the royalty dispensation against economists? tax standards in an attempt to make a judgement on the ?equity? of the new system. This paper argues that most stakeholders should be comfortable with most of the requirements of the Act for most of the time. However, the new regime is unlikely to motivate miners to become refiners, as the benefit of the reduced rate on refined minerals appears to be insufficient to justify the additional costs to refine the mineral resource to the prescribed states of beneficiation.

Jan 1, 2011

By M. Weir, J. R. Cutland, L A. J. Pronk van Hoogeveen

"A computer system for the design of open pits to mine stratiform orebodies has been developed for use at Nchanga Consolidated Copper Mines, Ltd. The particular requirements of such a system, for example, the accuracy of representation of geological detail and the ability to follow footwalls, arc described in this paper, together with the methods that have been adopted to satisfy them.A modified version of the Open Pit Design Program of Rio Tinto Zinc Consultants, Ltd. is incorporated in the system and the geological data are converted into a form usable by the computer by means of a pencil follower. Some of the uses which have been made of the system are described, with reference to the long- and medium-term planning of the Nchanga Open Pit, the major producing pit at Chingola Division."

Jan 1, 2014

By R. H. Matjie, J. R. Bunt, A. C. Collins, J. C. van Dyk, C. A. Strydom

South African coal discards derived from feed coal for thermoprocesses pose human health and environmental problems and incur high disposal costs. These issues need to be resolved. Coal fines and a coal fines/ K2CO3 blend were combusted at 700°C in a laboratory rotary kiln to produce ashes containing metakaolinite (Al2O3.2SiO2) and illite/muscovite/orthoclase amorphous materials. The blend ash and coal fines ash, containing 18% K2O and <1% K2O respectively, were leached with water and with 1 M and 8 M NaOH at 80°C for 4 hours using a solid to liquid ratio of 1:5. The 8 M NaOH leach yielded 17% sodalite (Na8Si6Al6O24(OH)2) formation through SiO32-, Al(OH)4-, and Na+ precipitation in the leached ashes. The 1 M NaOH leach yielded no sodalite. X-ray fluorescence analysis of the original ashes and leached ashes showed low Al and Si dissolution efficiencies due to the sodalite formation. Sequential NaOH leaching resulted in the highest potassium dissolution efficiency of 89% for the ashes of fines/K2CO3 blend and 59% for the fines. It may be possible to increase the ash-derived zeolite concentration by using even higher NaOH concentrations (12–20 M NaOH) during leaching. Sodalite derived from coal ash could possibly be utilized for water purification in industrial applications, or as molecule separators. The potassium-containing liquid could be used in fertilizer manufacture.

Mar 30, 2023

By M. Lange

The postulation that primary platinum group metal (PGM) matte will chemically react with magnesia-chrome bricks when temperatures exceed 1500°C was tested. Magnesia-chrome brick samples were heated in contact with matte at 1300°C to 1750°C for 30 minutes, after which the refractory samples were analysed using reflected light microscopy and scanning electron microscopy. The samples were all completely penetrated by matte. As the temperature increased the matte also penetrated the fused aggregate grains and disintegrated them. The chromium concentration of the matte inside the refractory samples was found to be slightly higher than that of the bulk matte. At temperatures of 1500°C and higher, MgO, FeO, and magnesium-rich silicate crystals could be identified in the matte directly adjacent to the refractorymatte interface. Phase relations clearly indicated that chemical reactions take place between primary PGM matte and the magnesiachrome refractory material at temperatures above 1500°C, but that these reactions are more complex than expected from FactSAGE® calculations.

Jan 1, 2014

By A. F. Spinks, S. P. Nicholls

"The Lower Orebody at Chingola Division of Nchanga Consolidated Copper Mines, Limited, is a stratified orebody that is mined by a continuous caving system. The accurate determination of the developed and semi-developed ore reserves has always been difficult. The new system proposed in 1971 is designed to update and, as new informa¬tion becomes available, to account for the depletion of, the reserves.There are three main inputs to the system. These are borehole data, survey data and extractions data. The borehole data are input to a geological borehole master file system, which holds every recorded detail of a borehole in an easily extractable form. These data can be extracted for ore reserve calculations or for contour mapping of orebodies and rock types. The grades for use in the ore reserve calculations are extracted from the relevant boreholes.The survey data are information on the position of the blocks and drifts, taken from plans, and information on the scraper drift and trough drive positions taken from sections. The information is extracted from the plans and sections using a D Mac pencil follower. The ore reserve is calculated from the survey data and the borehole data.Data on extractions are taken from scraper operators&apos; logs, tramming records, skips hoisted records and accepted mill tonnages and grades. Using these data, the mill tonnages are reconciled back to the drifts, to deplete the current ore reserves.As new workings are brought into operation and further evaluation holes are drilled, the relevant data are input and the new developed ore reserve is calculated."

Jan 1, 2014

By A. Santana, J. Jankolovits, G. S. Reyes

The flotation of sulfide ores that contain carbonaceous gangue requires significant operational and chemical intervention to achieve suitable metallurgical outcomes. Carbonaceous gangue dilutes concentrate grades, alters the froth behaviour, reduces operational stability, adsorbs reagents, and reduces value recovery. Carbon management processing strategies like preflotation and depression are often presented as point solutions. Moreover, oversimplified mechanisms of carbon depressants belie their complex and nuanced impact on flotation behaviour. Optimising the flotation of carbonaceous sulfide ores requires a holistic consideration of interactions between the carbon management reagents and the processing strategy, ore mineralogy, flotation behaviour, flowsheet, and all other aspects of the flotation system. Examples are shown where conventional, simplistic mechanisms of carbon depressants fail to explain the observed flotation behaviour. The multifaceted impacts of carbon depressants on froth behaviour, collector performance, and value recovery highlight the need for a holistic approach to carbon management. Keywords: Carbon management, carbonaceous ores, sulfide flotation, carbon depressant

Jan 1, 2020

By S. Moolla, R. Lynch, S. Brijraj

A reliable method to locate microseismic evets is an important objective for routine mine seismic monitoring. We developed an algorithm that can automatically and reliably locate an event from a single uniaxial trace. Signals created by microseismic events are recorded as seismograms that consist of direct P- and S-waves as well as the waves reflected off the underground excavations. We take advantage of the extra complexity these reflections introduce as they make the signal more unique. In our investigation we cross-correlated unaltered synthetic seismograms against trial waveforms created from a linear combination of appropriate waveforms from a library of numerically calculated strain Green’s tensors. We use a single uniaxial synthetic seismogram to invert for the source location, six moment tensor components, and frequency. The resulting cost functions are constructed as maximal correlations at each node in the mine grid through the true source x-planes. This function is maximized by differential evolution to simultaneously yield the source parameters. Sensitivity tests such as shifting the mine plans and altering the background velocities of the media are investigated to test the robustness of the method. We contaminate the data with 40% white noise to test the resolution against simulated real recorded seismograms. The method is demonstrated using synthetic data calculated with a realistic underground 3D velocity model.

Jun 10, 2024

By I. O. Ondicho, E. K. Mutinda, B. O. Alunda, E. Agyekum

Driven by the necessity to improve blast performance regarding fragment size distribution in limestone mines, this paper introduces the prediction and measurement of blast fragmentation distribution through the modified Kuz-Ram (MKR) and Kuznetsov-Cunningham-Ouchterlony (KCO) models. Precise prediction and measurement of rock fragmentation resulting from blasting play a critical role in hard rock ore extraction. This is due to the substantial influence of post-blast ore size distribution on the efficiency of all subsequent downstream rock handling and processing operations. Additionally, employing secondary breakage of boulders, when necessary, leads to an unjustified rise in production costs. In this paper, the MKR and KCO models were utilised to identify the most appropriate model for application in Bisil and Simba quarries situated in Kajiado County, Kenya. Split-Desktop was used for blast fragment measurement by processing digital images obtained after blasting and computing the fragment size distribution of the blasted rock. As per the investigation, the recorded percentages of boulders generated at the sites ranged from 7% to 12.3% for the Simba quarry and from 11.2% to 23.9% for the Bisil quarry, respectively. Regression, correlation, and root mean square error (RMSE) were employed as the primary performance indicators. The study concluded that KCO outperformed MKR in accurately predicting blast fragment sizes in the examined quarries.

Mar 5, 2025

By P. K. Jain

A spiral concentrator is a density separation device used for the beneficiation of coal and various minerals such as iron ore, chromite ore, gold, beach sand minerals etc. The flow pattern developed in the equipment is complex and unique, yet the operation is very simple, with low capital and operating expenditure. Spirals are applied for beneficiation of material in the size range finer than 2 mm and are capable of recovering heavy minerals as fine as .01 mm. The understanding of the unique flow pattern has kept researchers engaged over the last few decades and attempts are being made to explain such flow patterns so that they can be controlled and modified to improve the operating efficiency, Ep (Ecart Probable Error, also known as probable error in separation) and acceptability of spiral concentrators for processing of fines and slimes - currently being discarded and dumped in the tailing ponds. An attempt has been made in this paper to explain the generation of complex flow patterns with application to classical solid mechanics in the fluid and slurry system. The same has been used to explain the selective separation of particles in different zones in a cross-section on the spiral trough. The paper also discusses the application of a force balance model to explain the generation of secondary circulation. Due to the presence of laminar and turbulent flow regimes in the spiral concentrator, varieties of equations have been proposed in the literature, consisting of different equations for different zones. An attempt has been made to present a unified flow equation for calculation of flow velocity at different positions on the spiral trough. Keywords: Secondary circulation, spiral concentrator, density separation, fine particle processing

Jan 1, 2020

By H. Mulder, M. C. Bekker

The objective of this paper is to describe the research followed in creating a generalized, readiness assessment tool for mining projects. We start by highlighting the need for the assessment tool and then progress towards explaining the methodology followed during the study. The selection and finalization of the list of elements, sections, and categories that make up the unweighted values are described, followed by a summary of the weighting process applied. The outcome of this process is a weighted readiness assessment tool for mining project studies. The main benefits of the tool are that it will guide decision-makers and project managers through the definition phases of the project and improve the likelihood of project success.

Jul 2, 2022

By J. H. deur Potgieter

This paper, &apos;A review of the biological treatment of cyanide-bearing waste water&apos; discusses the necessity for the treatment of cyanide-bearing waste water with a view to the avoidance of environmental pollution, and the limitations of the available chemical and physical processes are referred to briefly. The sources of cyanide-bearing waste waters are mentioned. The mechanisms of production and utilization of cyanide by fungi and bacteria are discussed. The work done in connection with the biological removal and destruction of cyanide is summarized, the successes achieved are described, and the relevant processes are listed. In conclusion, some advantages of biological processes for the removal of cyanide are mentioned.

Jan 1, 1991

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in a solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimising the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give an account of the uranium processing optimisation journey embarked on over the years; namely, the operational tradeoffs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper. Keywords: By-products, gold extraction, reverse leach benefit, uranium extraction

Jan 1, 2020

By Ernst-Ulrich Reuther, Alexander Donmen

Mine ventilation in the German coal mining industry is concerned mainly with problems of thermal environment arising from greater depths and with increasing emission of methane gas. The development of computer techniques over the past ten years for solving these and ancillary problems is reviewed. The emphasis from a planning and control point of view falls mainly on ventilation network calculations, temperature predictions and advance estimates of methane emission.

Jan 1, 2014

By R. A. Wildenboer, R. F. Sandenbergh

Rare earth elements (REE) are present at concentrations of approximately 0.36 % in phosphogypsum stacks located in Phalaborwa, South Africa. The REE are present in the phosphogypsum in solid solution in the gypsum and as fluorine and aluminium rich precipitates. Recovery of the REE offers opportunities for valorization and reducing the environmental impact of the phosphogypsum waste. This paper presents the results of investigations into the leaching behaviour of rare earth elements and other impurities from phosphogypsum using aqueous sulfuric acid. The effects of acid concentration, temperature, residence time, and the influence of impurities were evaluated for their impact on the solubility of rare earth elements in a sulfate medium. It was found that a significant fraction of the REE can be leached from the phosphogypsum in a range of conditions much less severe than traditional hard rock rare earth processing conditions. The REE were leached at a sulfuric acid concentration of 110 g/l, temperature of 30°C – 40°C and a residence time of approximately 8 hours.

Nov 6, 2024

By S. T. Johansen, B. T. Løvfall, T. Rodriguez Duran, J. Zoric

A methodology for building pragmatic physics-based models is here adapted to predict the erosion of ladle linings in the steel industry, in order to support operators when deciding whether the lining can be used safely for another heat. A defective lining may allow 140 t of molten steel to spill, with disastrous consequences for workers and plant. The adopted work flow for the development, challenges faced, and some model results are presented. One key learning outcome is that model development should allow time for maturing the process understanding, as well as for many iterations by ‘questions-responses and actions’ at various stages in the model development. Good interaction between the development team and industry case owner is an important success factor. Combining or extending the model with the use of machine learning and cognition-related methods, such as knowledge graphs and self-adaptive algorithms, is discussed.

Apr 16, 2024

By H. W. J. P. Neomagus, J. R. Bunt, D. L. Botha, N. T. Leokaoke

Coal briquetting traditionally makes use of high-dosage, nonpolymeric binders (such as coal tar pitch or molasses) or polyvinyl alcohol (PVA) at low dosages for the binding of fine and ultrafine coal. Due to constraints associated with the manufacturing and cost of PVA-bound briquettes, a novel polyacrylic binder was developed that could possibly be added in low dosages at room temperature. A set of formulations of two polyacrylic components (components A and B) was developed, from which an optimal binder mixture was determined. This formulation comprises 40wt.% component A and 10wt.% component B with a 0.04wt.% cross-linking additive, and the balance water. The uniaxial briquette compressive strength was used to obtain the optimal binder mixture. The binder mixture was added to the coal powder in dosages from 0.1 to 1.2wt.%. Mechanical tests and thermogravimetric analysis in an oxidized environment at a maximum temperature of 930°C were conducted. Binder-bound briquettes were compared to binderless briquettes and PVA-bound briquettes. Briquettes made from the polyacrylic formulation had uniaxial compressive strengths double that of the binderless briquette yield strength, as well as the minimum recommended compressive strength of 0.375 MPa. The organic binders did not affect the combustion of the briquettes, since the results compared well with the binderless briquettes. The polyacrylic formulation is considered to be a possible substitute for PVA in terms of mechanical and thermal properties and raw material cost.

Mar 1, 2021

By H. -U. Lim, C. -H. Kim

The sixth underground pumped powerhouse cavern is under construction now in Korea. For the stability analysis of the five underground powerhouses, finite element method was used. For this analysis, in-situ rock stresses were measured by overcoring method and horizontal to vertical stress ratio was calculated 1.07-1.32 at four sites. Rock mass strength and elasticity were assumed from intact rock properties. The ratio of elasticity of rock mass was 0.16-0.55 of intact rock core elasticity. In general, elasto-plasticity with Mohr-Coulomb failure criterion was applied and the input cohesion and internal friction angle were approximately 0.12-0.22, 0.6-0.87 of intact rock strength parameters, respectively. Der sechste Untergrund-gepumpt-Powerhouse-Cavern ist jetzt im Bau in Korea. Für die vergan-gene Stabilitätsanalyse des fünf unterirdischen Powerhouses in Gebrauch wurde ein begrenztess Elementsmethode benutzt. Für die Analyse wurden In-Situ Felsenspannungen von overcoring Methode gemessen und Horizontale zu senkrechtem Spannungsverhältnis waren als 1.07-1.32 an vier Stellen kalkuliert. Felsenmassenkraft und Elastizität wurden von unversehrtem Felsenei-gentümern angenommen. Das Verhältnis der Elastizität von Felsenmasse war 0.16-0.55 von un-versehrter Felsenkernelastizität. Im allgemeinen wurde Elasto-Plasticity mit Ausfallskriterium des Mohr-Coulombs verwendet. Die Eingabebindekraft und die innere Reibungswinkel waren unge-fähr 0.12-0.22, 0.6-0.87 von unversehrtem Felsenkraftsparametern, jeweilig. En Coree, la sixieme centrale souterraine de la pompe d&apos;accumulation dans la caverne est en construction. La methode d&apos;element fini a ete utilisee pour analyser la stabilite de cinq dernieres centrales en service. Dans cette analyse, la reaction de la roche sur place etait mesuree par la methode d&apos;overcoring et celle du rapport horizontal-vertical etait calculee de 1.07-1.32 en quatre places. L&apos;intensite et l&apos;elasticite de la masse de roche ont ete estimees de la roche intacte. Quant a l&apos;elastic-ite, sa masse de roche etait 0.16-0.55 fois que celle de la roche intacte. En general, elasto-plasticite avec le critere de defaut Mohr-Coulomb etait utilisee et sa cohesion d&apos;energie et son angle de friction interieure etaient supposees respectivement 0.12-0.22, 0.6-0.87 fois que la parametre de l&apos;intensite de roche intacte.

Jan 1, 2003

By J. W. D. Groenewald, L. Auret, B. S. Lindner, E. C. Nienaber

Mineral processing plants have complicated control strategies, with different control layers, multiple interacting loops, and feedforward disturbance rejection. The complicated control strategies mean that oscillations can arise and propagate to multiple loops and degrade the control performance. Oscillation detection techniques, such as the spectral envelope method, can be applied to detect oscillations within an observation window. However, the start- and end-points of the oscillations within the observation window cannot be identified with current oscillation detection techniques. The start- and end-points would be useful to label the oscillatory intervals, and then to use these labels to identify process conditions associated with the oscillation. In this paper, a pattern recognition technique, Density-Based Spatial Clustering of Applications with Noise (DBSCAN), was used to label oscillation intervals. An oscillation diagnosis workflow combining spectral envelope and DBSCAN was demonstrated on an industrial case study of oscillations in a flotation circuit concentrate sump. The workflow successfully detected the oscillation, labelled the oscillatory intervals, and enabled accurate root cause analysis. The impact of time series features, namely the signal power ratio () and the oscillation frequency, on the performance and optimal parameter selection of DBSCAN was also investigated. Low oscillation frequencies and low s negatively affected the performance of DBSCAN. Additionally, the results indicated that higher oscillation frequency was related to higher optimal values for the lag parameter. Keywords: Oscillation diagnosis, process monitoring, data mining, clustering, flotation control

Jan 1, 2020

By A. W. Cramb

A three-day symposium on the production of clean steel organized by The South African Institute of Mining and Metallurgy, was held in September 1995 at Vanderbijlpark. It was attended by 151 delegates, who represented the whole of the steel industry in South Africa: Iscor Works, Saldanha Steel, Columbus Stainless, Highveld Steel & Vanadium, Iscor Research & Development, University of Pretoria, and Technikon Witwatersrand, as well as the users of steel products were represented. Professor Allan Cramb held the delegates attention with well-presented research and practical information. He obtained excellent interaction with the delegates by responding in depth to the questions put to him during the Symposium. In summary, he emphasized the following aspects of the elimination of defects during the processing of steel in continuously cast materials.

Jan 1, 1996