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By J. Pelders, G. Nelson

"Fatigue is a significant concern in the mining industry as it is a causal or contributing factor in many incidents and accidents. Fatigue can be caused by work- and non-work-related factors. There is a lack of information about associations between demographic and other non-work factors, and fatigue. This study aimed to assess associations between demographic, work, living, and socioeconomic conditions, and lifestyle characteristics, and fatigue at a platinum smelter in South Africa. Eight interviews with management and two focus groups with production workers were conducted, and 75 questionnaires were completed by production and other workers. Both work- and non-work-related factors were considered to be causes of fatigue. These factors included overtime, shift work, high workloads, activities performed outside of work, age, race, housing tenure, diet, sleep disorders, stress, and job satisfaction. In general, higher levels of fatigue were reported by younger participants, those who rented accommodation, ate less healthily, had a sleep disorder, and those with high levels of stress and low job satisfaction. As various demographic, lifestyle, and wellness-related factors were associated with fatigue, both work and non-work contributors should be addressed in fatigue management plans. BackgroundFatigue may be defined as ‘a state of impaired mental and/or physical performance and lowered alertness arising as a result of, or a combination of, hard physical and mental work, health and psychosocial factors or inadequate restorative sleep’ (BHP Billiton, 2005). Williamson et al. (2011) define fatigue as a biological drive for recuperative rest. Sleepiness and fatigue are related, and the terms are often used interchangeably. However, sleepiness, more specifically, can be defined as sleep propensity, or a person’s tendency to fall asleep (Hossain et al., 2003; Shen, Barbera, and Shapiro, 2006).Increasing levels of fatigue and sleepiness are associated with lapses in attention, errors, response slowing, fluctuations in alertness and effort, and impaired attention, working memory, long-term memory, decision-making, and creativity (Alhola and Polo-Kantola, 2007; van Dongen and Dinges, 2000). Fatigue is also associated with adverse effects on mood and impulsive behaviours (Alhola and Polo- Kantola, 2007; Minkel et al., 2011; Schwarz et al., 2013). It is a significant concern in the mining industry as it is commonly identified as a causal or contributing factor in many accidents and injuries (Schutte, 2009). Fatigue can also lead to long-term health problems, including digestive problems, heart disease, stress, and mental illness (Shaw, 2003)."

Mar 1, 2019

By G. Chitiyo

Prediction of pothole characteristics is a challenging task, confronting production geologists at the platinum mines of the Bushveld Complex. The frequency, distribution, size, shape, severity and relationship (FDS3R) of potholes has a huge impact on mine planning and scheduling, and consequently cost. It is with this in mind that this study was initiated. Quantitative analysis of potholes indicates that pothole size (area covered) can be described by two partly overlapping lognormal distributions. These are referred to as Populations A (smaller) and B (larger). The range of observed pothole sizes conforms to a simple double exponential growth model based on Newton's Cooling Curve. A third size range of very large potholes (Population C) that could not be modelled properly within the proposed growth model is interpreted as to represent a very early phase of aggressive regional thermo-chemical erosion and potholing. In general, potholes are dominantly quasi circular with only a subordinate tendency of elongation. In the UG2, potholes with elongated forms are more prevalent in the size range between 20 and 500 m diameter. In the Merensky Reef elongated potholes are more common in the size range above 50 m in diameter. Although not distinctly visible, elongation of potholes in both the UG2 and the Merensky Reef show a net north/south orientation. Using shapes of pothole rims and floor areas, documented for the UG2 in the Waterval Shaft area, it is demonstrated that the northern, down-dip edges of potholes have steeper dips than the southern, up-dip edges. Spatial distribution studies using a uniform quadrant method suggest that in both the UG2 and the Merensky Reef, the potholes are randomly distributed, with a tendency towards clustering. Clustering appears to be more prevalent in the smaller Population A potholes. Bearing all findings in mind, it is found that the model of thermo-chemical erosion of the cumulus floor by new influxes of superheated magma best explains the observed data. Partial to complete melting of the cumulate floor occurred in three phases. The first represents the emplacement of hot magma. This magma, due to turbulent flow and high chemical and physical potential, aggressively attacks the existing floor (crystal mush on the magma/floor interface). Regional erosion is manifested by large, often coalescing potholes. During the second phase, when the magma emplacement process ceased and cooling in situ started, two distinct periods of pothole formation ensued. The first is related to rapid cooling along the relatively steep part of the Newton Cooling Curve, when Population B potholes nucleated randomly and grew rapidly with concurrent convective overturn and largely laminar flow condition. The second period of cooling occurred on the shallow-dipping part of the Newton Cooling Curve. Population A pothole growth became more subdued and nucleation appears to have been, at least locally, clustered. The final phase of this proposed 'super magma cycle' was introduced when chromitite crystallization and precipitation terminated pothole formation. This was followed sequentially by pyroxene and plagioclase crystallization to form the typical cyclic units of the Critical Zone. No suitable proxy could be found for the prediction of pothole density of potholes associated with the UG2 (likely due to limited spatial data coverage), and these are best predicted by extrapolation. The Merensky Reef slope index, in contrast, provides a proxy for pothole density, enabling prediction with reasonable confidence. This predictive model has been verified using underground information. The findings made during the course of this investigation have, when implemented, significant impact. Successful implementation will not only allow enhanced resource and reserve definition, but also better mine planning and scheduling.

Jan 1, 2008

Fathi Habashi, Chalcopyrite. Its chemistry and metallurgy. New York, McGraw-Hill, 1978. 165 pp. RI9,95. Loss prevention and safety promotion The Proceedings of the 2nd International Symposium on Loss Prevention and Safety Promotion in the Process Industries, Heidelberg, 6th to 9th September, 1977, are now available. Chemical reaction engineering The Proceedings of the 4th International/6th European Symposium on Chemical Reaction Engineering (4th ISCRE) held at Heidelberg, Federal Republic of Ge rmany, from 6th to 8th April, 1976, are available from DECHEMA Deutsche Gesellschaft fur Chemisches Apparatewesen, P.O.B. 970146, D-6000 Frankfurt/ Main, West Germany, at the price of DMlOO plus postage and packing. Books received The Institution of Mechanical Engineers Proceedings Volume 190. Tribos abstracts on friction lubrication wear. Published by BHRA Fluid Engineering, Cranfield, Bedford MK 43 OAJ England. Price £30 (UK), US$72 (Europe), Seawater corrosion handbook, edited by M. M. Schumaker. Noyes Data Corporation Publicity Department, Mill Road at Grand Ave., Park Ridge, NJ 07656. 494 pp. Australian mineral industry quarterly 31(1) 1978 and 31(2) 1978. Bureau of Mineral Resources, Geology and Geophysics, Box 378, Canberra City, ACT 2601 Australia. Subscriptions $8, individual number $2. Mineral and NIM reports Report no. 1996 The extraction of gold from chloride solutions. (10th Nov., 1978). Report no. 1898 Batch and pilot-plant tests on M erensky Reef ore from the Western Platinum Mine. (8th Jun., 1977; reissued 30th Jan., 1979). Report no. 1920 A mineralogical investigation of Mamatu'an and Wessels manganese ores. (15th Sep., 1977; reissued 3rd Jan., 1979). Report no. 1978 The preparation and certification of a referencesample of magnetite ore. (22nd Dec., 1978). Report no. 1998 Electrode response to the addition of zinc during the cementation of gold. (25th Jan., 1979). Report no. 2002 The spectrochemical determination of phosphorus, magnesium, and iron in phosphate rocks and sulphuric acid leach liquors. (26th January, 1979). Report no. 1992 The use of emission spectrometry for the determination of impurities in metals. (24th Jan., 1979). Report no. 2003 An electrodeless conductivity meter of improved sensitivity and reliability. (28th Feb., 1979). Report no. 2005 The spectrometric analysis of manganese-bearing materials with particular reference to ferromanganese slags and metals. (16th Mar., 1979). Report no. 2006 An examination of procedures for the analysis of dry powders by atomic-absorption spectrophotometry. (28th Feb., 1979). Report no. 2007 The instrumentation and computerization of a 25 MV.A submerged -arc furnace. (25th Mar., 1977; reissued 16th Mar., 1979). Corrosion The International Corrosion Council has decided to hold the next Internat ional Congress on Corrosion in Mainz, Federal Republic of Germany, from 6th to 11th September, 1981. Process control The First European Symposium on Real -time Datahandling and Process Control will be held in West Berlin from 23rd to 25th October, 1979. Geomechanics The 28th Geomechanics Colloquy, organized by the Oosterreichische Gesellschaft fur Geomechanik, is to be held at Salzburg on 18th and 19th October, 1979. Geosta tistics A short course on 'Geostatistics for exploration and production planning' is being conducted by the Applied Earth Sciences Department, Stanford University, California, from 27th to 31st August, 1979. Business administration The Twelfth Executive Development Programme of the Graduate School of Business Administration, University of the Witwatersrand, is to be held from 9th July to 17th August, 1979. The engineer and the law A series of four meetings on the above subject is being conducted by the Measurement, Computation and Control SubCommittee of The South African Institute of Electrical Engineers. Lead smelter for South Africa? The National Institute for Metallurgy and Gold Fields of South Africa are making a comprehensive joint investigation of the technical and economic viability of an integrated lead smelter. Conference on titanium The Fourth International Conference on Titanium will be held from 19th to 22nd May, 1980, in Kyoto, Japan.

Jan 1, 1979

By T. J. Otto, C. H. Cloete, T. Mkhatshwa, T. J. van Heerden

The value realised by an open pit mine depends on the quality and integrity of the mine planning process as well as the level of execution against these mine plans. When managing the execution against the mine plan, how well the mine plan is executed spatially, is of critical importance. The short-term mine plan is the plan that is physically executed on most open pit mines. At the same time, the spatial mine-to-plan compliance is typically reconciled against the annual business plan. Short-term mine planning, therefore, plays an important role in the effectiveness of the spatial mine-to-plan compliance reconciliation process by providing operational teams with detailed designs and schedules, while ensuring that mining execution is spatially aligned with the business plan. The Sishen open pit iron ore mine (Sishen) strives to continuously improve spatial compliance to the business plan. Sishen enhanced the role that short-term mine planning plays in enabling the forward-looking component of the spatial mine-to-plan compliance reconciliation process. The enhanced short-term mine planning process focuses on detailed tactical sequence designs per mining pushback, the health of value chain buffers, spatial plan-to-plan reconciliation, and the associated management routines. This led to improved spatial mine-to-plan compliance to the business plan from 71% to 94% over the four-year period from 2020 to 2023 inclusive. These results indicate that the application of short-term mine planning as part of an integrated spatial mine-to-plan compliance process at open pit mines can contribute positively to improving the level of spatial execution against the business plan. This paper presents the enhancements made to the short-term mine planning process, which other open pit mining operations can consider to improve spatial mine-to-plan compliance.

May 27, 2025

By A. C. Scott

A detailed fundamental model of a zinc electrowinning cell has been developed and validated for both steady state and dynamic simulations. This model was used to investigate the effects of a range of operating variables and to find their optimum values. As well as providing useful design information for a planned upgrading of the EZ refinery, more generally it demonstrates the potential benefits to the minerals industry of the applications of modern CAD flowsheeting techniques. The SPEEDUP equation oriented CAD package was found most suitable for this task as the user can easily generate models specific to his site with any number of components and mixture properties.

Jan 1, 1987

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 G. Popplewel

Commencing with the Pre-Feasibility Study (PFS) conclusions, the Orapa 3 process design evolved through a phase of value-engineering studies. An overall re-evaluation of the originally proposed process design was necessary both in order to address the interim increase in target throughput from 9.8 Mtpa to 12 Mtpa as well as to increase capital efficiency. In the interests of clarity, the PFS process design for Orapa 3 has been omitted from this paper, as it is no longer relevant. Recognition is however due to those engaged in earlier phases of the Orapa 3 project with respect to fundamental mass-balancing modelling; and ore and diamond characterization, which fanned the basis for the process design that has evolved from feasibility study activities.

Jan 1, 2010

The October General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 21st October, 1970, at 4.30 p.m. V. C. Robinson (President) was in the chair. There were also present 25 Fellows, including J. K. E. Douglas, Prof D. D. Howat, D. G. Maxwell, Dr R. E. Robinson, P. A. von Wielligh (Council Members). D. Ayres, G. Burrow, E. H. D. Carman, D. L. Carson, M. E. E. Douglas, S. A. Finney, W. R. Flook, A. J. Freemantle, W. A. Gilbert, E. B. Gordon, B. W. Gray, J. M. Jacobs, P. H. Kitto, C. H. Kruger, Dr P. J. D. Lloyd, D. G. Malan, W. Pilkington, W. G. Pyne-Mercier, K. S. Rae, W. T. Ruhmer, D. J. Tutt and D. T. Watt. Seven Members, including E. J. Dominy, S. I. du Preez, L. V. Grobler, D. R. Lings, G. D. Louw, J. S. A. Oelofse and O. B. Prentis. Fifteen Visitors, including J. R. Coppin, Dr A. Faure, P. E. Franzl, G. P. Hart, D. van Heerden, A. W. Hunt, A. R. F. MacDonald, B. G. Meyburgh, P. H. Radcliffe, J. M. Shirley, T. H. Tunley, A. D. Vellema and R. E. Wheeler. Secretary, D. C. Visser. Total present: 49. OBITUARIES The President: "It is my sad duty to announce the death of the following: Sir George Arthur Davenport, Honorary Life Fellow, who joined the Institute in 1930 and passed away on 17th September, 1970. The late Sir George was also, for many years, our corresponding member for Rhodesia. Andrew Malcolm Carmichael, Associate, who joined the Institute in 1944 and passed away on 22nd August, 1970. Cyril John Douglas Veal, Life Fellow, who joined the Institute in 1929 and passed away on 27th August, 1970. As a mark of respect to the memory of the deceased and in sympathy with the bereaved I would ask you all to rise and observe a few moments' silence." CONFIRMATION OF MINUTES The President: "May we confirm the minutes of the Annual General Meeting held on 26th August, 1970, and the minutes of the monthly general meetings which were held on the 20th of May and the 17th of June, 1970, as published in the August Journal." Agreed. MEMBERSHIP The President: "I have much pleasure in announcing that the names of the undermentioned candidates, having been published in accordance with By-Law 5.2.2., Council has elected them to membership of the Institute in the following grades: Members: Nikolaos Lalakakis, Gordon Phillips Rundle. Associates: Henry du Preez, James Robert Forbes, Johannes Stephanus Albertus Oelofse, Casper Vorster van Heerden. Graduates: Michael Harold Crosbie, Graham Robert Wallis Walker, Gary Walker Braithwaite. Students: Mohammad Ali Kazemzadeh, Gerhardus Petrus Benade. APPLICATIONS FOR TRANSFER From Graduate to Member: James Wormald. From Student to Graduate: Peter John Cook, Pieter Willem Greeff. "I welcome the newly elected members to the Institute and congratulate the members who have been transferred to a higher grade." PAPER FOR PRESENTATION The President: "This paper is entitled 'The Design, Erection and Operation of a Purlex Plant at Buffelsfontein Gold Mining Company Limited'. It is presented to the Institute by Mr B. G. Meyburgh, a visitor to our Institute. He is a graduate of the University of the Orange Free State and is the Uranium Plant Superintendent at Buffelsfontein and he, therefore, is in a very strong position to describe this very excellent job which is being done as he has been associated with this plant from the inception." After the presentation of the paper the President said: "Gentlemen, the paper you've heard from Mr Meyburgh is a very concise and interesting account of an important piece of work, and I think the title is so completely descriptive of the subject, which is admirably set out in the paper which you have heard. You probably haven't all had the opportunity of reading it, but you very soon will. I found it interesting to note that the results predicted were surpassed in the operation of the plant to date. The actual results obtained are significantly good, I think. Any process which, in this country, increases production and decreases costs, is to be welcomed, particularly when it is so necessary for South Africa almost to bend over backwards to utilise every avenue available in order to increase the scope of the production for overseas' markets, of her metallurgical and mineral potential. In lighter vein-and there is no reason why we should always be so serious-I am glad to see that, in a scientific journal like this, such words as the American word 'crud' which I have been picked out about so often, because my grandchildren use it, is now given an aura of respectability. Thank you very much, Mr Meyburgh, for an interesting paper. We have a long list of contributors, and I am not going to waste any more time. I am going to call on Mr Tunley of the N.I.M. for the first contribution." T. H. Tunley, P. de Bruyn (read by A. D. Vellema), E. J. Dominy, E. H. D. Carman, A. R. F. MacDonald D. C. Streicher (read by P. H. Radcliff), Dr A. Faure and Dr P. J. D. Lloyd then contributed to the discussion. (This discussion will appear in a later issue of the Journal.) The President: "I wish to thank members and visitors for their attendance, and now declare the meeting closed." The meeting closed at 6.05 p.m.

By N. Mangadoddy, M. Padhi

The simulation of multi-component classification with modified viscosity model is the key focus in the current study. The classification of the ores using hydrocyclone is a renowned process and has a convoluted flow separation phenomenon. The highly turbulent flow inside hydrocyclone depends on the operating and design parameters apart from the feed mixture. Slurry viscosity also plays a dominant role in the classification of solid particles under the centrifugal settling action. A heterogeneous mixture with different components would result in different settling and rheological behaviour of particles’ suspension in the water medium. The newly proposed multi-component viscosity model (Mandakini et al. 2020) is implemented as a user-defined function to define the material property during the CFD study of the mixture rheology inside hydrocyclone classifier. The multiphase and turbulence model is solved using the modified Algebraic Slip Model and Large Eddy Simulation model. A comparison of the predicted component performance curves is evaluated with and without the corrected viscosity model. The density and size effect on the particle phase distribution inside the classifier are compared, where the misplacements of the finer particles are carefully assessed. Validation of the component classification in hydrocyclone with the laboratory experiments found a close agreement with the rheology based CFD data. Keywords: Dual-component, multi-component viscosity model, double-gap rheometer, computational fluid dynamics, high solids concentration

Jan 1, 2020

By P. J. Petit

"The complex planning required to achieve any planned production yields multiple and dissociated responses over the life of project (LOP). The customary decision-making process negates the possibilities of developing optimized and integral solutions from operating levels up to business and strategic levels. This results in an inefficient project or overall underperformance of the operation.In the project setting, disconnected trade-offs and improved performance studies become inadequate, because they are site-specific and use only a few comparative parameters. They are often based on a small data-set.Decisions taken to achieve overall objectives require the correct determination and dissemination of key performance indicators (KPIs). The KPIs indicate efficiency in operation, whereby the marginal rate of technical substitution corresponds to the rate of production. It is the necessary condition for optimization. Performance realization for sustainability follows optimization modelling, the latter often being presented with financial results such as business net present value (NPV). It considers techno-financial constraints and provides a strategic and aligned outlook of KPI decisions for an enhanced and integrated outcome.This paper explains a mining case study that is rendered efficient, and through business optimization (BO) short-term and sustainable targets are reached. Business optimization increases the NPV by 14.7%. This is achieved by challenging conventional decision-making associated with maximizing business value by including environmental externalities within the LOP."

Jan 1, 2016

By P. G. Toledo, R. I. Jeldres, G. R. Quezada

Chile is the main producer of copper in the world and lately the mining industry has suffered challenges due to the lack of water in the north of the country, along with the new policies of not using fresh water for the industry. This has prompted the use of seawater as an alternative source for mining. Several studies have been driven due to this new scenario, which have shown that seawater can be beneficial, if certain ions are removed from the process. This is the Mg that generates precipitates at high pH, that have been shown to make mining operations difficult. In particular, thickening operations are impaired by the presence of Mg ions, where aggregate formation and sedimentation decreases substantially. Our studies suggest the competence of the precipitates in adhering to the polyacrylamide (HPAM) flocculant and not towards the surface of the quartz minerals. This motivates the present work to use molecular dynamics to study the adsorption of a HPAM molecule on quartz surfaces and the surfaces formed by Mg precipitates. The surfaces are immersed in a saline solution or seawater that includes the HPAM molecule. Results are obtained by measure the adsorption frequency and duration. We obtained that the HPAM molecules are preferably absorbed on the surfaces of magnesium hydroxide. This gives us a good agreement with what is observed experimentally and strengthens the premise of the competition of hydroxide with the flocculant. Keywords: Molecular dynamics, adsorption, tailing flocculation, magnesium removal

Jan 1, 2020

By E. Van Der Lingen, A. Paton

"The South African ferrochrome industry has been faced with various challenges during the past few years, such as influences from the market, manpower strikes, China’s control over the demand for both ferrochrome and chrome ore from South Africa, and electricity supply constraints, placing increased pressure on the local industry to improve output in order to remain globally competitive. The year 2016 brought a dramatic change in the local ferrochrome industry, being marked by higher chrome ore prices and the takeover of some idle smelters.This study investigates the methods of technology acquisition used in various parts of the ferrochrome smelter value chain throughout a business cycle, and whether there is a preference for a specific acquisition in an explicit part of the value chain. The study also considers whether companies prefer to partner with local or global institutions for collaborative development, and the methods used by companies to protect their technologies.IntroductionSouth Africa holds the world’s largest chrome ore reserves and was the world’s largest producer of ferrochrome until 2012, when China became the leading ferrochromeproducing country. South Africa’s chrome ore (chromite) supply into the Chinese market has risen significantly from 36% of China’s total chrome ore imports in 2010 to more than 70% in 2016 (Fowkes, 2014; Creamer, 2017). China controls the demand for both ferrochrome and chrome ore from South Africa (Fowkes, 2014). China’s high import rate of chrome ore has resulted in ferrochrome prices being driven down and a depressed ferrochrome market. The South African industry meets the chrome ore demands but loses out on ferrochrome beneficiation.Furthermore, the local ferrochrome industry has been threatened with the overall poor competitiveness over the past few years, resulting in four of the eight producers ceasing operations at the beginning of 2016. Challenges experienced by the producers, some of which are directly linked to production costs, include influences from the market, productivity that was affected by wildcat strikes, China’s control over the demand for both ferrochrome and chrome ore, and electricity supply issues (Fowkes, 2014, 2013; Biermann, Cromarty, and Dawson, 2012). Ferrochrome production is energy-intensive and South African producers have faced higher electricity costs, electricity supply complications, and a weaker currency exchange rate since 2009."

Oct 1, 2018

By D. R. Tesarik, F. M. Jones, J. B. Seymour

As part of safety and stability studies at three underground mines in the United States, researchers installed earth pressure cells and embedment strain gauges in cemented rockfill to measure stress and strain changes as mining progressed and the rockfill was loaded. Data from these instruments were used to calculate the in situ modulus of the rockfill for two of the mines. A three-dimensional numerical model of a cemented rockfill cap was validated with data from extensometers anchored in the mine roof and sill; this model was then used to estimate deformation modulus at the third mine because the earth pressure cells and embedment strain gauges recorded negligible changes. Rockfill binder used at these mines ranged from 4 to 8 per cent of the dry components by weight, the water-to-cement ratio was from 0.42 to1.0, and the largest aggregate size in the three mixes ranged from 5 to12 cm (2 to 4.7 in). The range of the calculated in situ deformation modulus values was large, but as expected, it was bracketed by modulus values for cemented tailings and roller-compacted concrete with similar cement contents and water-to-cement ratios. Dans le cadre d’études sur la sécurité et la stabilité de trois mines souterraines situées aux États-Unis, les chercheurs ont installé des palpeurs de pression des terres et des extensomètres d’encastrement dans les remblais cimentés afin de mesurer les variations relatives à l’effort et à la déformation des terrains durant l’exploitation minière et le chargement du remblai. Les données recueillies à l’aide de ces instruments ont servi au calcul du module in situ du remblai dans deux de ces mines. Le modèle numérique tridimensionnel de la semelle d’un remblai cimenté a été validé à partir des données recueillies par les extensomètres ancrés dans la voûte et dans la semelle de ces mines; ce modèle a ensuite été utilisé pour estimer le module de déformation à la troisième mine, étant donné que les palpeurs de pression des terres et les tensiomètres enfouis avaient relevés des variations négligeables. La matière d’agrégation de l’enrochement utilisée dans ces mines comportait entre 4 % et 8 % des composantes sèches par poids; le rapport eau-ciment se situait entre 0,42 et 1,0; et la taille des agrégats les plus gros dans ces trois mélanges était de 5 cm à 12 cm (2 po à 4,7 po). L’écart entre les valeurs calculées des modules de déformation in situ était grand, mais comme on s’y attendait, cet écart a été compensé par les valeurs modulaires des résidus cimentés et du béton tassé au rouleau avec des teneurs en ciment et des rapports eau-ciment semblables. Als Teil der Sicherheits- und Stabilitätsstudien an drei Bergwerken in den Vereinigten Staaten von Amerika installierten Forscher Erddruckgeber und Einbindungsdehnungsmesser in zementierter Steinschüttung, um Spannungs- und Dehnungsveränderungen während der fortlaufenden Bergarbeiten und der Belastung der Steinschüttung zu messen. Daten von diesen Instrumenten wurden dazu verwendet, das In-Situ-Modul der Steinschüt-ung für zwei Gruben zu berechnen. Ein dreidimensionales numerisches Modell einer zementierten Steinschüttungsschwelle wurde mit den Daten von den im Grubendach und in der Schwelle verankerten Extensometern validiert; dieses Modell wurde dann dazu eingesetzt, um das Deformationsmodul in der dritten Grube zu schätzen, da die Erddruckgeber und Einbindungsdehnungsmesser nur geringfügige Messabweichungen feststellten. Das in diesen Gruben verwendete Steinschüttungsbindemittel variierte zwischen vier und acht Prozent an Trockenkomponenten nach Gewicht, der Wasser-Zementfaktor betrug zwischen 0,42 und 1,0 und die größte Zuschlagstoff-größe in den drei Mischungen schwankte zwischen fünf und zwölf Zentimetern. Die Reichweite der berechneten Werte des In-Situ-Deformationsmoduls fiel etwas breit aus, aber es fand erwartungsgemäß eine Klammerung der Modulwerte zwischen den Zemen-trückständen und dem durch Walzen verdichteten Beton mit ähnlichem Zementanteil und Wasser-Zementfaktor statt.

Jan 1, 2003

By B. Moritz, W. Schubert, E. A. Button

ABSTRACT: Geological conditions associated with alpine environments in combination with high overburden in many tunnelling projects lead to squeezing behaviour. The main problems associated with such conditions include large deformations, overstressing of supports, and lack of face stability. In the past during Alpine tunnelling the problem of large displacements incompatible with rockbolt – shotcrete support systems have been solved by leaving gaps in the lining to accommodate excessive deformations. In the late nineties, yielding elements have been developed, which are integrated into the lining. The paper deals with the basic concept, the design and the application of that system, which has been successfully used in several Alpine tunnels. ZUSAMMENFASSUNG: Die geologischen Verhältnisse in den Alpen führen bei großer Überlagerung häufig zu starken Deformationen während des Baues von Tunneln. Die großen Verformungen führen in vielen Fällen zu einer Überbeanspruchung des Ausbaues und Problemen mit der Ortsbruststabilität. Früher ist man dem Problem der Unverträglichkeit des Ausbaues mit den hohen Dehnungen durch Freilassen von Deformationschlitzen im Spritzbeton begegnet. Vor etwa 10 Jahren wurden duktile Stahlelemente entwickelt, welche in die Spritzbetonschale integriert werden. Der Beitrag beschäftigt sich mit dem Konzept, der Planung und der Ausführung. RÉSUMÉ: Les conditions géologiques dans les Alpes conduisent fréquemment lors d'un grand recouvrement à des déformations fortes pendant la construction des tunnels. Les grandes déformations conduisent dans beaucoup de cas à une surtension du revêtement et à des problèmes avec la stabilité de front de taille. On a fait face plus tôt au problème de l'incompatibilité du revêtement avec les extensions élevées par libérer des rainures dans le béton projeté. Il y a environ 10 ans, des éléments sidérurgiques ductiles qui sont intégrés dans le béton projeté ont été développés. La contribution s'occupe de concept, de planification et de mise en oeuvre.

Jan 1, 2003

By A. Pareek, V. S. Masampally, V. Runkana

Mineral processing plants, in general, consist of comminution and separation circuits. Rougher flotation is considered as the heart of the separation circuit with concentrate grade and mineral recovery being the key productivity and quality parameters that affect the downstream operations and profitability. Online prediction of these parameters can help improve process performance in real-time. Past efforts to predict flotation cell performance have focused on building physics-based or machinelearning (ML) based models. Although physics-based models are popular in process design applications, ML models are more appropriate for online monitoring, control and optimisation due to their lower computational requirements. Deep learning (DL) is gaining prominence nowadays for application in industrial operations where a large amount of data is available. We have developed a DL model based on long short-term memory (LSTM) neural networks to forecast the two key performance indicators (KPIs), namely, mineral recovery and concentrate grade in a mineral processing plant. Rougher feed characteristics such as mineral grade and particle size distribution, upstream measurable disturbances such as throughput of the comminution circuit and pulp density, and control variables such as aeration rate, pH, and collector addition rate are considered as explanatory variables to train the model. The model was tested with data from an industrial mineral processing plant. For real-time dynamic predictions, the trained model appropriately accounts for mismatch in measurement frequency of real-time process data and off-line laboratory analysis data. Such a time series model can be used as a state observer in model predictive control techniques for optimal control of unit operations in a mineral processing plant. Keywords: Mineral processing, flotation, time-series, dynamic modelling, deep learning

Jan 1, 2020

By N. C. J. Dempers, J. A. L. Parker, R. A. Wildenboer

More than half of global cobalt reserves are located in the Southern African Copperbelt, stretching over the northern tip of Zambia and southern area of the Democratic Republic of Congo. In these areas, cobalt is not typically produced as a primary product but as a byproduct of copper production. Ores from this region often contain uranium, which is readily leached under typical copper leach conditions and enters the process. Uranium does not pose a challenge to copper production, but it becomes a significant problem when it follows cobalt to the cobalt precipitation process and results in unacceptably high levels of U in the final Co product. This paper evaluates the existing process technologies that can be used to remove uranium from cobalt-bearing process streams, including phosphate precipitation and ion exchange. Advantages and disadvantages of the uranium removal processes are discussed, and important design considerations are highlighted.

Jan 1, 2023

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 N. Morris

In South Africa, diamonds are mined predominantly in rural areas. Kimberlitic diamonds dominate in Limpopo and the Northern Cape Provinces whereas alluvial diamonds are mainly sourced from the North West and Northern Cape Provinces. There are a few large and medium sized diamond companies (De Beers, Petra Diamonds, Trans Hex, Rockwell and Alexkor). There are many smaller companies involved in diamond mining, mostly alluvial diamond mines. The nature of alluvial diamond deposits is that they are aerially more extensive and thus their surface impacts are more pervasive: The recent downturn in diamond prices has resulted in the sudden cessation of mining at many small and medium diamond operations. The South African Mining Charter requires all mines, including diamond mines, to subscribe' to .the following empowerment objectives:

Jan 1, 2010

By F. Sundqvist, B. Skawina, J. Greberg, A. Salama, M. Astrand, P. Ekbeck

Today’s mining operations require fast reporting and rapid rescheduling based on updated information. An automatic mine scheduling system could not only quickly reschedule but also propose alternative solutions. To avoid the financial and physical risks associated with testing such a system directly in operation, it could be first evaluated via discrete event simulation models. This would offer a safe environment to evaluate different operating rules and algorithms. In this study, this is achieved by integrating automatic scheduling software with a discrete event simulation model.

Jun 1, 2021

By M. S. Shishvan, J. Sattarvand, R. S. H. Meij

Navigating miners during an evacuation using a smart evacuation technology can significantly decrease the evacuation time of an underground mine in case of an emergency. This paper presents a mathematical programming model to calculate the most efficient escape path for each miner as a critical component of the smart evacuation technology. In this model, the total evacuation distance of the crew is minimised and scenarios with blocked pathways, and stamina categories for the miners are simulated. It was found that all the tested scenarios are technically feasible. Using the feature that filters out blocked pathways has no downsides, as safer routes are calculated, and there is no penalty in the computation time. The paper also discusses the social and technical issues that need to be overcome before the algorithm can be implemented as an actual escape solution.

Sep 1, 2021