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A South African gold mining rock-related fatal accident database has been analysed in order to determine rock-related fatality trends in the gold mining industry over the period 1990 to 1998. This analysis was extended further to include some of the individual reefs mined and focused particularly on the Carbon Leader Reef, the Ventersdorp Contact Reef, the Vaal Reef and the Basal Reef. Rock-related accident locations are also presented. A stope rock-related risk is proposed, where the fatality rate in terms of rock-related fatalities per million square metres mined for the gold mining industry as a whole is compared to individual reefs, allowing a stope rock-related risk to be attributed to the individual reef. This comparison is extended further by removing the contribution by the reef being evaluated from the industry data, thereby allowing this reef to be directly compared to the rest of the industry with respect to a stope rock-related risk.

Jan 1, 2001

By T. Maejima, K. Aoki, T. Mori, K. Iwano

Concerning the excavation of rock cavern, it is one of the most important issues to evaluate the behavior of rock joints. But few detailed measurements for joint behavior had been conducted. Therefore, in order to evaluate the stability of rock cavern, effective approach for monitoring and analyzing the joint behavior needs to be developed. In this paper, authors described the results of analysis for joint behavior during the excavation by comparing with both results of the in-situ measurement by BTV and the numerical analysis by MBC model. Bei Ausschachten von Gesteinshöhlen ist es von besonderer Bedeutung, das stark von den Verbindungsteilen beeinflusste Gesteinsverhalten zu bewerten. Jedoch wurden bisher nur wenige Beobachtungen über das Öffnungsverhalten von Verbindungen durchgeführt. Daher muss ein effizientes Verfahren zur Überwachung der Stabilität unterirdischer Höhlen und der Analyse des Verhaltens von Verbindungsstellen entwickelt werden. In der vorliegenden Studie beschreiben die Autoren das Verhalten von Verbindungsstellen während der Ausschachtung durch Vergleiche sowohl mit den Ergebnissen von in situ Messungen mittels BTV als auch numerische Simulation mit dem MBC Modell, welches auch Diskontinuitäten berücksichtigen kann. Quand il s’agit d’excaver une caverne dans une roche ayant des joints très développés, il importe fort d’évaluer le comportement de la roche. Cependant, le nombre d’observations du comportement des roches effectuées au niveau de joints est loin d’être suffisant. Par conséquent, pour s’assurer de la stabilité des parois des cavernes souterraines, il a fallu mettre au point une méthode fiable de détection et d’analyse du mouvement des joints. Dans cet article, les auteurs décrivent leurs études de comportement des joints pendant l'excavation, en comparant les résultats des mesures effectuées in-situ, dans un chantier d’excavation par BTV , avec ceux d’analyse de la simulation numérique par MBC permettant de tenir compte des discontinuités.

Jan 1, 2003

By I. A. Mwamba

Plain and alloyed titanium aluminides of composition Ti-47.5 at.% Al were prepared by melting commercial-purity titanium and aluminium with additions of 1 at.% precious metal. The as-cast alloys were subjected to potentiodynamic scans in 5, 15, and 25 wt% HCl aqueous solutions at room temperature and compared for their abilities to spontaneously passivate. Addition of precious metals resulted in a general improvement of corrosion resistance by increasing the open circuit potential to more noble values. Addition of 1 at.% gold or silver to titanium aluminide did not significantly increase the corrosion potential (Ecorr) above that of the plain titanium aluminide alloy, indicating that gold and silver are not sufficient cathodic modifiers to improve the corrosion resistance of titanium aluminide in all the solutions tested. However, platinum, palladium, and iridium additions shifted the corrosion potentials to the position of the passive region of plain TiAl for all solution concentrations. This indicated that TiAl alloyed with these platinum group metals would passivate spontaneously by cathodic modification. TiAl alloyed with palladium performed the best in 5 wt% HCl solution with the most positive corrosion potential. In 15 wt% HCl solution, alloys with platinum exhibited the most positive corrosion potentials, while alloying with iridium or palladium revealed more negative corrosion potentials. Thus, palladium alloying led to the best cathodic modification of titanium aluminide in low-concentration HCl solution, whereas platinum and iridium alloying additions resulted in the best cathodic modification of titanium aluminide in high-concentration HCl solutions.

Jan 1, 2013

By O. A. Bascur

Ores are becoming extremely variable with mineralogy and hardness disturbing the grinding and flotation circuits. The current grinding and flotation sensors provide large amounts of data for process optimisation. Adding the right context and operational events augments operational knowledge for proactive actions to improve the performance of the grinding and flotation circuits. A data-driven strategy is needed to enable operations, maintenance, and business personnel to quickly and easily take corrective action when abnormal conditions occur. A digital plant template transforms data into operational insights in real-time. It uncovers the hidden, idle and downtime losses. By measuring and managing these unproductive times, people find new ways of avoiding them, improving the profitability of the plant. The information created by the real time analytics enables the calculation of recovery in real time and develops predictive analytics models to find the best operating condition based on the type of ore currently mined. The creation of new workflows and collaboration between mining and concentrator plant and the enterprise, including services providers, are enabled. A grade recovery model is used to identify the best operating conditions in real-time. An optimal Gaudin size distribution shape is used to find the grinding operating conditions that optimise the metal recovery in the rougher sections of the mineral processing plant. Sensors in the flotation circuits enable estimation of metal recovery and determine the optimal froth depth and aeration profiles, using an industrial air holdup flotation model. The implementation of a recovery/grind strategy with industrial examples in non-ferrous metal concentrator is presented in the paper. Keywords: Digital transformation, soft sensors, predictive analytics, grinding flotation optimisation, flotation bubbles, particle size, particle size distribution shape, froth aeration profiles, flotation air hold up model, recovery predictive analytics

Jan 1, 2020

By D. C. Panigrahi

Extensive field studies have been carried out to investigate the pillar fire problems in one coal mine in India. A Thermal IR gun and a Thermovision camera have been employed for thermal scanning to assess the state of heating in selected pillars. Special sampling set-ups have been designed to collect gas samples from the holes drilled into the selected pillars and the multigas detector is used to analyse the composition of samples in situ. In order to predict the spontaneous heating in coal pillars, different gas ratios have been calculated and it has been observed that some of the established gas ratios, viz. Graham?s ratio, Young?s ratio etc. have resulted in negative values in samples containing high amounts of methane. The modified gas ratios have been proposed which will be useful for predicting the pillar fires. These ratios may also be used for assessing the condition of fires in sealed-off areas.

Jan 1, 2004

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements of The South African Institute of Mining and Metallurgy set out on pages 357 to 366 for the year ended 30 June 2002. These financial statements are the responsibility of the Institute?s Council. Our responsibility is to express an opinion on these financial statements based on our audit. Scope We have conducted our audit in accordance with statements of South African Auditing Standards. Those standards require that we plan and perform the audit to obtain reasonable assurance that the financial statements are free of material misstatement. An audit includes: ?examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, ?assessing the accounting principles used and significant estimates made by management, and ?evaluating the overall financial statement presentation. Audit opinion In our opinion, the financial statements fairly present, in all material respects, the financial position of the Institute at 30 June 2002 and the results of its operations and cash flows for the year then ended in accordance with South African Statements of Generally Accepted Accounting Practice. Auditors 26 July 2002 Council?s approval of the annual financial statements The annual financial statements for the year ended 30 June 2002 set out on page 357 to 366 wereapproved by the Council on 26 July 2002 and are signed on its behalf by:

Jan 1, 2002

By Philippe Dumont

?Lay out of the tunnel section ?General ?Geology ?Tunnels methods ?Stations constraints ?Impacts on tunnels ?Design ?Programs

By Glen Mc Gavigan

The roof of the Sishen cave is being mined in order to exploit 6.8Mt of high grade ore. The cavity is filled with quartzite backfill in order to support the roof in the event of collapse. The cave dips at approximately 37o, is 260m along dip and 70m along strike and has a total volume of 261,391m3. GPS and optical monitoring techniques were attempted to detect subsidence but proved to be impractical. The GroundProbe Slope Stability Radar (SSR) uses differential interferometry to measure sub millimetre movement in a rock face. The SSR was applied in a non production situation and detected subsidences of 38mm/day before visual signs of instability were detected. The rate of deformation detected was slowing as a result of the roof coming to rest on underlying backfill. Monitoring during production drilling detected a sudden subsidence of 18.6mm/hour which resulted in the evacuation of personnel from the area. Further inspection of data showed that the rate of deformation was slowing and production was allowed to continue without further incident. The SSR has helped dispel the fears of workers and has proven that subsidence can be accurately measured and delineated with the SSR.

Jan 1, 2006

By J. N. Van der Merwe, M. Mathey

"The South African squat coal pillar strength formula, developed by researchers from the Chamber of Mines Research Organization in the 1980s, predicts an exponential increase in coal pillar strength once a critical width-to-height ratio of 5 is exceeded. The arguments that have been proposed in favour of this formula are discussed critically in this paper.Field experience with squat pillars in the USA and evidence from published physical, analytical, and numerical model pillar studies corroborate the fact that a squat effect is unlikely to occur in coal pillars at width-to-height ratios less than 10. Furthermore, an exponential increase in peak strength of coal pillars does not exist. An alternative design criterion for squat pillars in South Africa is therefore suggested. IntroductionFive decades of coal pillar research in South Africa have produced a wealth of information on the mechanisms contributing to the strength and failure of in-situ coal pillars and accompanying phenomena. The relevant knowledge was sourced from, and for, a South African coal mining environment that remained largely unchanged in the second half of the 20th century. The depth of mining seldom exceeded 250 m, with mined seam thicknesses averaging 3 m and typical pillar width-to-height ratios (w/h) of 3–4.It is therefore not surprising that comparatively little research has been directed at the prediction of coal pillar performance in deeper deposits, where squat pillars of larger width-to-height ratios will be required to support the overlying strata. However, a thorough understanding of squat pillar performance will be necessary should the remaining deep coal deposits of the country be extracted in future, for instance in the Waterberg or Ermelo coalfields.A squat coal pillar strength formula has already been proposed in South Africa. The origin of this formula will be discussed in some detail in the following sections and its appropriateness will be critically reviewed against a great amount of evidence from relevant squat coal pillar research conducted internationally."

Jan 1, 2016

By L. Lehasa

The purpose of the project was to investigate the challenges faced by Khutala Colliery pertaining to underground road construction and maintenance. Furthermore the influence of these challenges on productivity and safety requirements were taken into consideration. The operating standards required for the construction and maintenance of the 2 seam road transport infrastructure was investigated, together with reasons why the standards of operating procedure are not met. The Code of Practice put in place by Khutala Colliery was used to view the standard operating procedures. Leading practices on underground road construction were researched. The project aims to discover the gaps that Khutala Colliery must bridge to implement enhanced practices with regards to underground road construction. During the period of study, observations were carried out to determine whether the road construction standards of operating procedure were being adhered to at all times for both road construction and road maintenance. Khutala Colliery has put in place a traffic management plan, which includes safety practices and work policies that must be adhered to while travelling on underground transport roads.

Jan 1, 2012

By S. P. Pearton

"Pumpable emulsion explosives have been available to surface and underground massive mining operations for decades, and their unique properties offer significant advantages in terms of improved safety, reliability, and performance. However, the benefits of pumpable emulsions have been unavailable to narrow-reef mining operations due to the lack of technology necessary for their successful implementation in this challenging environment. Despite efforts to promote and enhance the safety and performance of bulk emulsions for narrow-reef stoping, little research has been undertaken to advance the pump technologies required for their implementation. This has resulted in a gap in knowledge and technology, and as a consequence the successful implementation of a pumpable emulsion system has consistently eluded the narrow-reef environment.The purpose of the following investigation was to evaluate the viability of pumpable emulsion explosives for use in South African narrow-reef mining operations. By approaching the problem from multiple perspectives, this research aimed firstly to propose a theoretical framework and suite of equipment suitable for the implementation of pumpable emulsions within the narrow-reef environment. Through the development of this suite of pumpable emulsion technology, tests could be undertaken on the proposed narrow-reef emulsion formulation and pumpable emulsion technology to obtain the necessary understanding of the performance of the system under controlled operating conditions prior to its implementation in the broader mining industry."

Jan 1, 2015

By G. H. Lind

Research into the safe and economic extraction of underground coal pillars in the Witbank and Highveld coalfields of South Africa highlighted that future practices will have to consider pertinent risks associated with this least safe of all underground coal mining methods conducted in South Africa. To this end, a computer-based program called A-PEP (Analysis for Pillar Extraction Potential) was developed to assess three aspects of this mining practice, viz. risks associated with the physical attributes, operational risk attributes and economic attributes. This intelligent tool can thus be used when planning to conduct underground pillar extraction to ensure that all pertinent risk elements and legislative requirements are considered to conduct this mining method safely before a submission is made to the Department of Minerals and Energy. Keywords: operational risk management, mine planning, underground coal mining, pillar extraction.

Jan 1, 2003

By J. Kempken, T. A. Schreiter, R. Degel, H. Schmieden

Keywords: Pyrometallurgy, SMS Demag, Germany, submerged arc furnace, ferro alloys, non-ferrous, FeCr, FeNi, FeMn, copper, cobalt, slag cleaning, PGM, rectangular furnace After a short summary of the SMS Metallurgy part of the SMS group, the paper will focus on Submerged Arc furnace technology. After general aspects of furnace design, the focus will shift to different applications and their specific furnace requirements. Finally, a state-of-the-art design tool as well as a new invention to improve slag-cleaning technology will be featured.

Jan 1, 2006

By J. Härkki, R. Hiltunen

The Akanvaara intrusion (surface area 50-55 km2) in Savukoski, Northern Finland, hosts 23 distinct monocumulate layers of small euhedral chromite crystals enclosed in a silicate matrix. These chromitite layers have been divided into four groups; UC (upper chromitite), ULC (uppermost lower chromitite) LC (lower chromitite) and LLC (lowermost lower chromitite). The driving force for investigating the Akanvaara chromites and their reduction behaviour originated from their very low MgO content and relatively low Al2O3 content, giving them a unique quality which based on thermodynamics should facilitate the reduction. Another interesting feature is the high amount of V2O3 present especially in the upper chromitite. The chromites included in this study are from the UC and ULC layers (24.9 and 22.7 per cent Cr2O3 respectively). To obtain a better understanding of the reduction behaviour of Akanvaara samples in comparison to MgO-bearing chromitites, Kemi chromite from the ferrochrome works in Tornio, Finland, was included in the study as a reference sample. The reduction experiments were isothermal in a temperature range of 1000-1400°C in CO atmosphere. Experiments were also conducted with coke addition in pellets and briquettes in CO/Ar/H2 atmospheres. The results of the reduction experiments complemented with microanalytical research indicate that the Akanvaara chromites do reduce to a higher degree than the Kemi chromite. Although the aim was to characterize the mechanisms of reduction focusing on gas-solid reactions, the nature and amount of the gangue minerals was such that a considerable amount of slag phase was formed, which affected the reduction mechanisms extensively. The structural features together with low MgO and high FeO content in both Akanvaara chromites are important factors resulting in better reducibility than in the Kemi chromite.

Jan 1, 2004

By K. Osburn

South Deep Gold Mine, owned by Gold Fields Ltd., is situated near Westonaria in the Gauteng Province of South Africa and mines the conglomerate bands of the Upper Elsburg reefs (Mondeor Conglomerate Formation) of the Witwatersrand Supergroup and the Ventersdorp Contact Reef (VCR) of the Ventersdorp Supergroup. The stoping and underground developments are mechanized. The Upper Elsburg reefs are mined by a variety of mining methods, including mechanized drift and fill, modified drift and bench, longhole stoping, and low-profile mining. Optimal mine design and scheduling for deep-level mechanized mining are complex, and success is highly dependent on detailed, robust, and accurate geological and geostatistical models. Geological structures significantly influence the sedimentological characteristics, distribution, and preservation of the Upper Elsburg reefs and VCR. Accordingly, particular emphasis is placed on the generation of a mine-scale structural model that accommodates the relationships between the older north-trending fault systems (West Rand and Panvlakte faults) and younger east-trending dextral wrench faults. Results from underground mapping, borehole intersections, and highresolution three-dimensional seismic data have been integrated to produce coherent three-dimensional geological models. The Upper Elsburg reefs suboutcrop against the VCR and comprise an easterly diverging clastic wedge, thickening from the suboutcrop position, to approximately 130 m at the mine?s eastern boundary. The Upper Elsburg reefs are characterized by conglomerate and quartzite bands forming multiple, stacked, upward-fining unconformity-bounded couplets. Palaeocurrent directions are dominantly from west-northwest to east-southeast, indicating that the more proximal deposits are preserved close to the suboutcrop, with distal facies to the east. Sedimentological modelling is applied to individual stratigraphic units and caters for facies definition. This is achieved through channel width (CW) kriging and fitting of type sections to borehole and mapping data. Homogenous geological geozones for each stratigraphic unit are thus defined within individual structural blocks on the basis of those sedimentological parameters that have been found to have a positive spatial correlation to gold concentration. These geozones then serve as constraints to the evaluation of the orebody. This contribution presents a summary of the modelling processes that are currently applied in the development of high-confidence, timeously produced geological models that are essential input for mineral resource estimation and mechanized mine planning and scheduling.

Jan 1, 2014

By J. Riss, S. Gentier, A. Marache

The study of the hydromechanical behaviour of fractured rock masses requires a detailed knowledge of the isolated fractures. The aim of the paper is the simulation of the evolution of the void space, located between both walls of a fracture, during a shear test under constant normal stress. Results of the mechanical simulation model are first validated then analyzed in detail. We observe that, during the shear process, there is an opening of the fracture with the creation of preferential channels. These channels are determined at the early phase of the shear process (pre-peak phase), and we observe during the post-peak phase that void areas increase in size rather than the creation of new apertures. Die Untersuchung des hydromechanischen Verhaltens eines zerlegten Felsmassivs erfordert genaue Kenntnisse der einzelnen Spalten. Ziel dieses Artikels ist die Simulation der Evolution des Hohlraumes zwischen den beiden Wänden eines Spaltes während eines Abscherungsexperimentes unter konstantem senkrechtem Druck. Die Ergebnisse der Modellierung werden zunächst mit dem Abscherungsexperiment verglichen und dann im Einzelnen ausführlich analysiert. Während des Abscherungsprozesses tritt eine Öffnung des Spaltes auf, die die Bildung von bevorzugten Fliesswegen fördert. Diese Kanäle werden bereits in einer frühen Phase des Abscherungsprozesses (pre-peak Phase) festgelegt. In der post-peak Phase tritt dann eher eine Vergrößerung dieser Kanäle, als die Bildung neuer Hohlräume auf. L’étude du comportement hydromécanique d’un massif rocheux fracturé ne peut se faire sans une connaissance approfondie des fractures le constituant. L’étude présentée dans cet article concerne la simulation de l’évolution de l’espace des vides présent entre les deux épontes d’une fracture au cours d’un essai de cisaillement à contrainte normale constante. Les résultats du modèle sont tout d’abord validés puis analysés en détail. On constate que, au cours du cisaillement, il apparaît une ouverture de la fracture permettant la création de chenaux préférentiels. Ces derniers sont déterminés très tôt dans le cisaillement (phase pré-pic), et on observe dans la phase post-pic davantage un accroissement de la taille des chenaux plutôt que la formation de nouvelles zones de vides.

Jan 1, 2003

By R. Ordóñez Olivares

This manuscript focuses on the design and development of steels for the railroad industry and methods of testing them. Here are summarized the results of research focusing on alloy development and design, with particular focus on advanced rails and wheels. The high-performance steels are characterized for their mechanical and service characteristics. The relationship between properties and cleanliness is discussed and compared to the regular railroad steel. Some of the tests presented are standard tests that are complemented with the nonstandard test recommended by the Association of American Railroads (AAR) and recommended modifications of this. The paper presents the results of metallurgical analysis, mechanical, and residual stress tests. The laboratory methods include microstructure, residual stresses, tensile, hardness, fracture toughness, and microcleanliness tests.

Jan 1, 2013

By M. du Toit

Cromanite?is a new high-strength austenitic stainless steel developed by Columbus Stainless. It contains approximately 19 percent chromium, 10 per cent manganese and 0,5 per cent nitrogen. Cromanite can be welded successfully, but due to the high nitrogen content of the base metal, certain precautions have to be taken to ensure sound welds with the desired combination of properties. Although no matching filler metals are currently available, Cromanite can be welded using a range of commercially available stainless steel welding consumables. Welds produced using E309L, E307, E307Si and E312 filler wires are resistant to hot cracking and the formation of nitrogen-induced porosity, but the hardness, strength, ductility and toughness of the welds are generally inferior to those of the base metal. In applications where full use is made of Cromanite?s high strength, welds with matching strength levels would be required. In wear applications, where Cromanite is used primarily for its work-hardening properties and corrosion resistance, lower strength welds would probably be acceptable. Welds produced using E307 filler metal demonstrate the best combination of properties for use in wear applications. The welds display high rates of work-hardening that would result in increases in hardness and strength when subjected to abrasive or high impact environments.

Jan 1, 1999

By M. Nyoka

Historically bauxite-based refractories have been used in applications where andalusite-based refractories could work. Bauxite-based refractories were chosen over andalusite-based refractories mainly because of the availability of low-cost Chinese bauxite and also because many furnaces were designed by international companies that cannot easily access high-quality products. Currently, the availability of low-cost bauxite is under threat as a result of high export duties and tariffs as well as restrictions on the amount of material that China allows to be exported. South Africa is a major producer of andalusite, and this guarantees stability with respect to both availability and price. Refractories based on andalusite have an added economic advantage over bauxite-based refractories in that unlike bauxite, which requires high-temperature calcination before use, andalusite is used in its raw state. This paper constitutes a literature study of the merits, both technical and economic, of using refractories based on andalusite compared to bauxite-based refractories. Keywords bauxite, andalusite, refractory, furnaces, calcination.

Aug 1, 2013

By K. M. Phamotse, A. S. Nhleko

"*Paper written on project work carried out in partial fulfilment of BSc (Mining Engineering) degreeSynopsisLiqhobong Mining Development Company (LMDC) has been experiencing problems with boulders after blasting where the fragment sizes exceed the maximum of 800 mm as per mine standard. As a result, the mine has employed various methods to improve the fragmentation. The goal is to produce a run-of-mine (ROM) feed that does not choke the crusher and cause delays in production. In order to achieve this goal, fragmentation distribution within the fines and coarse envelope must be optimized through effective planning of blasting activities and accurate execution.The mine determined the fines-coarse envelope within which the entire crushing system can handle fragments using Split Desktop software. It is expected that both the predicted and actual fragmentation curves lie within that envelope for optimal fragmentation. The Kuz-Ram model with blast design parameters of 2.6 m for burden, 2.8 m for spacing, and 127 mm hole diameter was used to predict the fragmentation. The results show that the blast design parameters may need altering to achieve optimum fragmentation. Furthermore, the execution of the drilling and blasting may be the cause of the fragmentation problems. The mean fragmentation size (X50) differs greatly, unlike the uniformity index (n)s values which are relatively close to each other (0.6 to 2.2). The mean squared error (MSE) values have a large range. A proposed solution is a modified burden, spacing, and hole diameter. It is concluded that blast design parameters need to be reviewed in order to obtain correct predictions. IntroductionFragmentation has an impact on the mine production cycle which comprises, inter alia, drilling, blasting, loading, hauling, and crushing. Correct fragmentation as set by the plant design is important as it reduces the time lost due to secondary blasting and/or loading difficulties. In this paper we analyse blast results at Liqhobong Mining Development Company (LMDC) in Lesotho for a period of six months. This project was undertaken to observe the trends from the blasts and to identify whether any discrepancies exist in the overall blast information. The period under study included 16 blasts."

Jul 1, 2019