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By T. Aoki, Y. Maeno, R. Kawano, F. Nakahara, Y. Obara, K. Shibata

The mechanical behaviors of fully-grouted long-embedded cablebolts actually used in situ are very non-linear in pull tests and are different from those of short-embedded cablebolts. We have conducted the pull tests of long-embedded cablebolts installed in mockup rock test blocks, which are 4m in the longitudinal length. In order to investigate the mechanical behaviors inside the test block, the axial load distribution along the cablebolt and locations of acoustic emission events were measured during each pull test. It was found that the axial force distributions were quite linear and that the gradients were interpreted as the grout bond strength by taking into consideration the stress balance at the infinitesimal segment of a cablebolt. Les boulons-câbles longs entièrement cimentés qui sont réellement utilisés sur place présentent, au cours des essais de traction, des comportements mécaniques considérablement non linéaires et différents de ceux des boulons-câbles courts. Nous avons mené des essais de traction des boulons-câbles longs installés dans une maquette de fond rocheux servant d’éprouvette d’une longueur longitudinale de 4 m. Afin d’étudier les comportements mécaniques intérieurs de l’éprouvette, la répartition de la force axiale du boulon-câble et l’émission acoustique ont été mesurées durant chaque essai de traction. Il s’est avéré que les répartitions de la force axiale sont sensiblement linéaires et que leurs gradients représentent la résistance d’adhésion en prenant en compte l’équilibre de contraintes à la partie infinitésimale d’un boulon-câble. Das mechanische Verhalten von ganz eingegossenen, lang eingebetteten Kabelbolzen, die vor Ort eingesetzt werden, ist bei Zugprüfungen sehr nichtlinear und anders als das von kurz eingebetteten Kabelbolzen. Es wurden Zugprüfungen mit lang eingebetteten Kabelbolzen durchgeführt, die in Prüfblöcken (Gesteinsattrappen) mit 4 m Länge eingelassen waren. Zur Untersuchung des mechanischen Verhaltens in den Prüfblöcken wurden die Axiallastverteilung entlang des Kabelbolzens sowie das Auftreten von Schallemission im Verlauf jeder Zugprüfung gemessen. Es ergab sich, dass die axiale Kraftverteilung recht linear ist, und die Gradienten wurden unter Berücksichtigung des Kräftegleichgewichts am infinitesimal kleinen Punkt eines Kabelbolzens als Haftfestigkeit interpretiert.

Jan 1, 2003

By Q. G. Reynolds

The dual-electrode direct current (DC) arc furnace uses two graphite electrodes, one connected as cathode and one as anode. Such an arrangement avoids some of the design difficulties associated with the anode hearth traditionally used in single-electrode and twin-cathode DC furnaces, but can introduce other design and operational difficulties including deflection of the arcs toward the furnace walls. Counter-intuitively, both arc jets in a dual-electrode furnace travel from the electrode down to the bath surface, despite carrying electric current in opposite directions?this is suggested in the theory of the governing equations of arc formation, and confirmed by experiments using high-speed photography. The dual-electrode arc system at small pilot-plant scale is studied using a transient magnetohydrodynamic model capable of predicting arc deflection and interaction from first principles, and the results are compared to the behaviour of twin-cathode systems at similar power. Finally, a simple arrangement of the furnace busbars, M configuration, is shown to provide some passive protection against arc deflection.

Jan 1, 2011

By More-O&apos, R. C. Ferrall, J. W. Wilson

SYNOPSIS The theory of elasticity has been shown to provide a means of determining the stresses and displacements induced by mining in deep level hard rock mines. This theory has been incorporated into an electrical resistance analogue on which the plane of a reef or ore-body can be modelled to enable the rapid determination of stresses and displacements at points in the plane of the reef. This electrical analogue has been used to determine energy release rates caused by scattered mining, which, to some extent, is a measure of the degree of hangingwall fracture. A correlation between predicted energy release rates and actual underground conditions in stopes in the O.F.S. goldfields has been encouraging enough to define parameters on which future stoping layouts can be based. The use of the elastic theory through the analogue has been extended to the assessment of the influence of stoping operations on off-reef excavations. Underground conditions at damaged and undamaged areas have been compared with predicted elastic stresses at the positions under review, resulting in the derivation of design parameters for use in siting off-reef excavations in the prevailing geological conditions in the O.F.S. and Klerksdorp goldfields. The analogue has also been used to assess the vulnerability of certain un mined dykes to bursting. Correlations between stresses induced on dykes by stoping and dyke behaviour underground has enabled critical stress levels to be determined for several persistent dykes occurring in the O.F.S. and Klerksdorp goldfields. A number of long and short term planning projects at mines operating in the Anglo American Corporation and General Mining and Finance Groups are described, where the data derived from the electrical resistance analogue is processed by computer programmes and assessed on the strength of the design factors derived from the correlation of field work and the elastic theory.

Jan 1, 1970

By Sh. Arshadnejad

Stress analysis in a rock medium is essential to determine the stress concentration between two consecutive circular holes and prediction of fracture behaviour. When two consecutive circular holes in a hard rock medium such as granite are loaded internally by the pressure of non-explosive expansion material (NEEM), stress concentration occurs between the holes which then causes the rock to fracture. In this work, finite element (FE) analysis using Phase2 code was employed to study the stress concentration between two consecutive circular holes under internal pressure induced by NEEM. Effects of different hole diameters and spacings, rock properties and NEEM pressures have been analysed. The data gained from the numerical analysis and analytical solutions were then used to develop two models. These models were then modified by using the FE data and polynomial regression analysis. The developed analytical models showed to be in a very good agreement with the FE analysis. Hence, the developed models can be used with confidence to determine stress distribution and concentration factors around two consecutive circular holes in a hard and brittle rock which are loaded internally by the pressure induced from the NEEM. Keywords Finite element method, non-explosive, quarry mining, stress concentration..

Jan 1, 2011

By T. F. Muller

In recent years, a great deal has been written and spoken, both in our country and overseas, about the dangers posed to the environment and the ecology by mining operations. The object of this address is to put this problem, and it is a real problem, into reasonable perspective. I shall try to present the various facets that merit consideration as objectively as possible. In doing so, I shall examine the following factors: Book review National Coal Board. Gate belt conveyors. London, H.M.S.O. (Price 95p.) Although the preface of this handy little book states that it has been written for the guidance of miningoperation trainees, it will prove valuable to the practising engineer as well. NIM reports Report no. 1733 A mineralogical investigation of weathered carbonatite from Salpeterkop. (14th Apr., 1975; re-issued 28th Feb., 1978). Report no. 1823 The recovery of gold and pyrite from a residue dump at Crown Mines. (10th Jul., 1976; re-issued 28th Feb., 1976). Report no. 1829 An investigation of weathered carbonatite from Salpeterkop. (20th Jul., 1976; reissued 28th Feb., 1978). Report no. 1932 A BASIC computer programme for the evaluation of intensity data from the Telsec Lab-X-250 Analyser. (12th Jan., 1978). Report no. 1940 The extraction of the noble metals with n-octylaniline, and its application to the analysis of platinum-bearing materials. (30th Jan., 1978). Report no. 1945 Analyses of the NIMROC reference samples for minor and trace elements. (28th Feb., 1978). Report no. 1945 Analyses of the NIMROC reference samples for minor and trace elements. (28th Feb., 1978). International futures conference A conference entitled 'The Road Ahead' is being organized by the 1820 Settlers National Monument Foundation to be held in Grahamstown from 3rd to 7th July, 1978. Conference of metallurgists The technical programme has been established for the 17th Annual Conference of Metallurgists sponsored by the Metallurgical Society of the Canadian Institute of Mining and Metallurgy. This year the Conference will be held in Montreal, Quebec, on 27th to 31st August, 1978, together with the 8th Hydrometallurgy Meeting.

Jan 1, 1978

By K. -J. Shou

A special three-dimensional boundary element method has been developed for the simulation of the development of fracture zone in rock mass. This approach comprises a boundary element method and a three-dimensional tessellation mesh generator. By using the tessellation generator, a set of pre-defined potential fractures is defined, and the fractures activate when the failure criterion is exceeded. This approach is justified by the reproduction of features observed in laboratory simulations of fracturing in blocks of rock subjected to compression. An attempt is then made to explain some of the attributes of fracture zone surrounding underground openings. Eine spezielle drei-Dimesionen Grenze Element Methode ist entwickelt zu simulieren die Entwicklung der Fraktur Zone in der Steinmasse. Diese Untersuchung benutzt eine Grenze Element Methode und ein drei-Dimensionen tessellation Masche Generator. Durch das Benutzen des Tessellation Generator, ein Satz der vor-bestimmt potentielle Fraktur ist festgelegt. Die Fraktur wird betaetigen, wenn das gescheiterte Kriterium ist uebersteigt und sind in dem Verscheiben-Abbrechen Element eingeschlossen. Diese Untersuchung ist von der Reproduktion der Fraktur justiert, die ins Labor beobachtet wird, um die Fraktur in der von der Kompression unterworfenen Steine zu simulieren. Ein Versuch ist gemacht, um einige Eigenschaften der Fraktur Zone um die untertageoeffnung zu erklaeren. Une méthode tridimensionelle spéciale de élément frontière a été dévélopée pour la simulation du dévélopment d’une zone fracturée dans la massive roche. Cette approche comprend une méthode de élément frontière et un générateur de maillage de la mosaïque tridimensionelle. En utilisant le générateur de mosaïque, une série des fractures potentielles predéfinies est définie avec d’une procédure de la triangulation de Delaunay. Les fractures activent lorsque le critère de rupture est dépassé et sont inclues dans les éléments du déplacement discontinuité. Cette approche est justifiée par la reproduction des caractéristiques observées dans le laboratoire, les simulations des blocs de roche fracturé et sujetés en compression. La tentative est alors fait pour expliquer quelques arttributs d’une zone fracturée alentours les ouvrages soustérrains.

Jan 1, 2003

Book reviews Natural gas substitutes from coal and oil, by S.A. Qadar. Amsterdam, Elsevier Science Publishers, 1985. U.S.$83.25. Reviewer: U. Grimsehl High heat production (HHP) granites, hydrothermal circulation and ore genesis. London, The Institution of Mining and Metalurgy, 1985. 593 pp. £30. Reviewer: S.A. de Waal 2. Recent publications Uranium recovery from phosphates and phosphoric acid, by S. Huwyler. 3rd edition. Wirenlingen (Switzerland), Swiss Federal Institute of Reactor Research, EIR-Bericht (C) no. 1. Apr. 1985. 56 pp. Geological aspects of mining productivity. Canada's base metal resources, by B.W. MacKenzie. Kingston (Canada), Centre for Resource Studies, Queen's University, Technical Paper no. 6, Aug. 1985. 115 pp. $10.Taxation policies in the Canadian minerals industry, edited by M. Wojciechowski. Kingston (Canada), Centre for Resource Studies, Queen's University, 1985. Mineral policy update 1984: Policy and program changes afecting the Canadian mineral industry, by M.l. Wojciechowski and M.L. McAlister. Kingston (Canada), Centre for Resource Studies, Queen's University, 1985. $12. 3. Mintek reports Report MU7 The selective solvent extraction of pal/adium by the useof di-normal hexyl sulphide. Report M218 Modification of the design of screen boxes for carbonin-pulp and resin-in-pulp plants. Report M225 The commissioning, operation, and maintenance of an on-line corosion-monitoring station for the mining industry. Report M231The determination of selected lanthanoid elements by atomic-absorption spectroscopy using electrothermal atomization. Report M233 A computer programme for the prediction of hydrocyclone performance, parameters, and product size distributions. Report M234 The solvent extraction of base metals by mixtures of carboxylic acids and non-chelating oximes. 6 The efect of particle size and coloid stability on the wet high-intensity magnetic separation of uranium from cyanidation residues. Report M238 The beneficiation of fine coal. Report M240 The spectrophotometric determination of tin in silicates and tungsten-bearing materials. Report M242 Wear and performance of materials in pipelines for the hydraulic conveyance of fused ash. IPMI award for distinguished achievementThe International Precious Metals Institute has announced that Professor Henry C. Taube, Nobel Laureate, wil be the recipient of their 1986 Distinguished Achievement Award. Dr Taube is Professor of Chemistry at Stanford University, Palo Alto, California.

Jan 1, 1986

By R. V. Ramani

Managers need quality information for effective decision making. This demand, at the present time, is being fulfilled by the increased use of computers via information systems, decision support systems and management information systems. The idea of incorporating intelligence into computers to aid decision-makers has been evolving for over two decades. In recent years, significant progress is reported on applications to business and sciences. In engineering functions, the Artificial Intelligence approach that seems to have great potential is the application of Knowledge Based Systems. The primary objective of this paper is to identify domains in mining engineering where application of knowledge based systems could be beneficial. In- corporation of the expertise required during the analysis and interpretation stages of an engineering design problem through knowledge based systems is recognized as an area of significant benefit. To this end, the components of knowledge based systems for mine ventilation and strata control design are described. The potential applications and limitations of knowledge based systems are outlined.

Jan 1, 1987

By F. R. Deist, R. P. Plewman

Discussion: A. Hazell (Associate Member) and T. J. Kotze (Graduate Member): The authors must be congratulated on the development of a versatile computer programme for determining the stresses and displacements resulting from mining operations. As a design tool it will no doubt take its rightful place together with the analogue computer. Union Corporation made use of this digital computer programme whilst still in its development stage to determine the stress distributions which were causing the unexpected failure of the Marievale sub-incline shaft. Two features arising from this investigation may be of interest to members, namely: A. The solution to the problem of stabilizing a rectangular inclined shaft, which turned out to be contrary to accepted mining practice, and B. A comparison between the results obtained with the pure digital system and the analogue computer. A. The shaft is nine ft high and 20 ft wide, dipping at 9° to the horizontal and crossing the bedding planes. Fig. 1 is a plan and Fig. 2 is a section of the sub-incline shaft pillar area showing the relative positions of the shaft and reef as well as their respective dips. The deepest point in the shaft is 3 300 ft below surface and the requirement of a stress free ground surface may not be satisfied. It also means that the original gravitational stresses are low. A 900 ft wide pillar was left to protect the bottom section of the shaft, the top section being understoped years ago. Extraction of the pillar was started at the beginning of last year, mining operations being carried out in the accepted manner, starting beneath the shaft and mining outwards. The approach did, however, turn out to be the wrong one, because failure of the shaft was noticed soon afterwards. Even small movements were serious in this case due to the low clearance between the skips and the shaft supports. During October, 1968, failure between benchmarks 8 and 10 (see Fig. 1) became so excessive that hoisting speeds had to be reduced. Failure continued to occur and, by the end of March, 1969, failure had propagated up the shaft as far as benchmark 7, and down as far as benchmark 12. As this shaft had a tight hoisting schedule it was imperative that a quick solution be found to arrest the failure.

By S. Potgieter-Vermaak

The main mineral components of the so-called heavy sands (or black sand) are the titanium, zirconium and iron-bearing minerals, rutile, zircon and illmenite, accompanied by various minor and trace amounts of silicates or phosphates, often present together with the rare earth elements. The investigated samples originated from Richards Bay Minerals (RBM) in South Africa, which is jointly owned by BHP Billiton and Rio Tinto, the largest titanium slag producer in the world. The present study focused on the characteristics of samples originating from various points in the separation plant. The heavy-mineral fractions and concentrates of a representative suite of samples were investigated using various analytical techniques to establish the differences in morphological and elemental compositions at the different points in the plant. These techniques included: reflected light microscopy, micro-raman spectrometry (MRS), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX) and structural and chemical analyser (SCA). All samples comprised a heterogeneous population of zircon and rutile grains with diverse physico-chemical properties, expressed by large differences in colour and trace element chemistry of single grains. The elemental composition proved the presence of the rare earth elements that appeared to coexist with both Ti and Zr minerals. The percentage of grains hosting inclusions, such as anatase, monazite, quartz, spessartine, augite, epidote and actinolite, varied for each sample and could be uniquely characterized by Raman investigations. Keywords: heavy mineral sands, micro-ram an spectrometry, elemental analysis

By S. A. Forrest, B. Clarke

Trends in PGM demand?The conference paper will cover a concise analysis of demand trends, which will include the major PGM end-use sectors (autocatalysis, jewellery, glass, petroleum, nitric acid, medical/dental) and will touch on the investment sector. Reference will be made to environmental legislation affecting global emission standards, trends in PGM loadings and the substitutability of platinum and palladium in this end-use sector. Observations will also be made on the jewellery sector, and the development of Chinese and Japanese demand. Trends in primary and secondary PGM supply?Similarly the paper will summarize historic and current global mine supply and primary production trends for PGMs, referencing recent expansions, their deliverability, and other projects coming on line. Consideration will be given to the grade and geology of PGMs worldwide and metallurgical developments. PGMs produced as by-products of base metal production and early PGM recycling estimates will also be appraised. In order to gain a wide-ranging appreciation of the industry?s long-term cost trends of producing virgin PGM metals, the paper will look at the cost and profit dynamics of global production on a regional basis (Western Bushveld, Eastern Bushveld, Northern Bushveld, Zimbabwe, USA, Canada and Russia). Extrapolating tomorrow?s PGM market and forecasting metal prices?Based on established industry trends and market practices Stephen Forrest will conclude by unveiling a variety of thought-provoking extrapolations of today?s and tomorrows platinum, palladium and rhodium markets to conference delegates. Importantly, having highlighted major developing PGM market trends in end-use (specifically on the elasticity of demand to high metal prices), primary and secondary PGM supply trends, in addition to presenting a carefully reasoned forecast of industry supply costs and margin trends, Stephen Forrest will conclude by estimating long-range PGM metal price trends. Other relevant market factors including industrial production, global currency rates and regional political factors will be deliberated.

Jan 1, 2006

The Floatability Characterisation Test Rig (FCTR) is a self-contained, highly instrumented, mobile pilot plant. It was developed as part of the AMIRA P9 project, primarily to determine ore floatability characteristics and to develop and validate flotation plant modelling, scale-up and simulation methodologies. This paper describes the use of the FCTR in validating the AMIRA P9 flotation model and modelling methodology. In 2001 the FCTR was installed and operated in parallel with WMC's (now BHP Billiton's) Kambalda Nickel Operation. The FCTR was operated using four different circuit configurations of increasing complexity. Metallurgical surveys, cell characterisation measurements and batch flotation tests were performed around each circuit. This allowed the calibration of a number of flotation models using a combination of data from one, two, three or four circuit configurations. The calibrated flotation models were then validated using predictive validation. To do this, data around a further five FCTR circuit configurations were collected (three of which are presented in this paper). The performance of each of the five circuit configurations was predicted using JKSimFloat V6.1 and the parameters from the various calibrated flotation models. The predicted performance was compared to the experimentally determined performance of each circuit. The validation of the AMIRA P9 model was shown to be largely successful except in the case where the reagent addition (depressant) to the validation circuit was different to that in the calibration circuits. The results also provided information regarding the required complexity of the calibration circuit and how many calibration circuits are required to obtain an accurate prediction of circuit performance. These results have increased the confidence in the AMIRA P9 flotation modelling methodology and have provided important information on what data must be collected to allow the accurate prediction of plant performance using the floatability component modelling approach.

Jan 1, 2007

By O. S. Tinkler, K. C. Sole

"Although the first large-scale application of copper recovery by solvent extraction took place in Zambia in the early 1970s, it is only in the last decade that this technology has become widely employed in this part of the world and is now a mainstay unit operation in copper hydrometallurgical flow sheets. The mineralogy of the ores of the African Copperbelt, and hence the characteristics of African leach liquors, differs significantly from those in Chile and the southwestern USA, where copper solvent extraction has had a long and successful history. These differences provide operators, metallurgists, reagent vendors, and engineers with many challenges: new approaches are needed to adapt solvent-extraction technology for successful implementation in this region. This paper examines typical operating practice in the African Copperbelt, discusses differences compared with other parts of the world, and looks at some of the challenges and opportunities presented by these flow sheets. IntroductionFollowing the success of the Rancher’s Bluebird and Bagdad solvent extraction and electrowinning (SX–EW) operations in Arizona in the late 1960s, the Tailings Leach Plant at Chingola, Zambia, became the first large-scale copper SX plant in the world, commissioned in 1974. Despite the equipment design now being outdated, this plant still continues to operate successfully, indicating the versatility and adaptability of this technology. Today, there are some 75 copper SX operations worldwide with cathode production above 10 kt/a. The top ten producers currently account for about 40% of the global 4.3 Mt/a SX–EW copper production. South America (predominantly Chile and Peru) is the largest copper cathodeproducing region, with annual production of some 2 Mt. The Central African Copperbelt (Zambia and the Democratic Republic of Congo (DRC)) is second, with cathode production of 1.2 Mt/a, and North America (USA and Mexico) third, producing close to 0.8 Mt/a Cu (Solvay Cytec data, 2014). The remaining 0.35 Mt/a comes from all other regions combined (referred to as ‘Rest-of-World’)."

Jan 1, 2016

By M. Gericke

Over the past few decades the commercial application of heap bioleaching technology for the extraction of base metals has become increasingly important, due mainly to the depletion of high-grade ore reserves. Heap bioleaching is widely used for the extraction of copper from secondary copper sulphide ores. The design and engineering aspects of the process have received considerable attention, but issues related to the microbiology of the process have been subjected to less rigorous scrutiny. The major role of micro-organisms in bioleaching processes is to catalyse the regeneration of ferric iron and protons, from ferrous iron and by sulphur oxidation respectively. It is accepted that even the most carefully engineered heaps are heterogeneous in terms of temperature, pH, the presence of anaerobic pockets, irrigation efficiency, and dissolved solutes. Since interactions between solution chemistry, mineralogy, and microbial populations exist in heaps, a better understanding of the correlation between microbial numbers and types with changes in these chemical and physical profiles with time would be beneficial during process design and operation of heaps, and could result in faster start-up times and higher metal recoveries. This paper reviews the role of microbiology in heap bioleaching processes. Aspects such as microbial diversity, identification and monitoring of cultures, inoculation strategies, colonization behaviour, and tolerance to metals and salts are discussed, and the potential contribution of the knowledge to the improvement of the operation and design of heap bioleach processes assessed. Conclusions are drawn with respect to the role of genetic engineering, heap inoculation practises, and remaining areas for future heap bioleaching research and development.

Jan 1, 2012

By S. Moodley

In the chloride process for Ti02 pigment production, various titania feedstocks (i.e. rutile, synthetic rutile, slag, and upgraded titania slag (UGS)) are chlorinated in a fluidized bed reactor with petroleum coke at temperatures between 1000°C and 1100°C to yield gaseous metal chlorides. Although feedstock preference is largely based on Ti02 content, feedstock physical properties (i.e. density, sphericity, size distribution, and porosity) differ; these differences will affect fluidization behaviour and can inadvertently affect conversion efficiency. For example, a high carryover from the reactor reduces particle residence time and decreases conversion rates. Owing to dwindling rutile reserves in the world, most chloride producers are forced to feed blends of feedstocks to their chlori¬nators; and so it becomes important to understand whether blends have an effect on the hydrodynamic properties of the bed. This paper describes the physical characterization of different feeds and the determination of the elutriation constants for slag, rutile, synthetic rutile, and a blend (i.e. 50 wt% rutile, 50 wt% slag). A common feature of the tests was that particles finer than 75 Km tended more than any other size to be elutriated. The tested rutile, classified as a Geldart Group B material, had the lowest carryover, whereas the slags had the highest. Interestingly, the elutriation constant (ki) of the blend is lower than those of either of its individual components.

Jan 1, 2012

By T. Tholana, P. N. Neingo

"A mineral resource constitutes the principal underlying asset of a mining company, and must be exploited and managed in such a way that maximum value is derived from it. Various asset management frameworks applicable to physical assets are available. This paper focuses on the extension of an asset management approach, particularly the Publicly Available Specifications (PAS) 55 asset management framework and the International Organization for Standardization (ISO) 55000 series of standards, to mineral assets. It is concluded that PAS 55 and the ISO 55000 series of standards can be extended to manage mineral assets, resulting in an integrated approach to sustainably optimize value from the company’s mineral assets. The benefits include improved returns on mineral assets, maximum mineral asset utilization, creation of an organizational culture focused on quality and continuous improvement, and assurance to stakeholders that the mineral assets are being efficiently managed over their entire life-cycle. In the context of this paper, a ‘mineral resource’ refers to both Resources and/or Reserves as classified by the SAMREC Code. IntroductionMining involves the extraction of valuable mineral resources from the Earth’s crust. A mineral resource is unique among natural resources in the sense that it is a wasting asset, which means that its value depreciates continuously with extraction. In addition, it is often impaired from time to time as commodity price changes (Macfarlane, 2011a). Since a mineral resource is a wasting asset there is a single opportunity available to optimize value from its extraction. Mine planning involves identifying a strategy to exploit the mineral resource in a way that maximizes value at an acceptable risk level throughout the life of mine (LOM). This optimum extraction strategy changes as economic conditions change, particularly commodity prices, as well as with improvements in orebody knowledge as mining progresses. It is the mineral deposit that competitively distinguishes two different mines and dictates the location of a mine; hence the adage ‘the orebody dictates’. Therefore, a mineral resource is the primary tangible asset possessed by mining companies and must be managed in such a manner that maximizes its value at an acceptable risk level (Macfarlane, 2011a)."

Jan 1, 2016

By G. E. Blight

Many mines engaged in deeplevel gold mining in South Africa are experimenting with the use of tailings fills, or are implementing tailings backfilling programmes on a limited scale. The approach varies from mine to mine, depending on circumstances and available fill materials. Several mines are backfilling with a cyclone underflow product; the cyclone overflow is then combined with the balance of the tailings stream and directed to surface disposal. As the extent of backfilling increases, the proportion of the surface tailings stream composed of overflow material will rise, and the properties of the tailings requiring surface disposal will approach those of the cyclone overflow. As the latter will be finer, less permeable and possibly weaker than the total tailings currently being disposed, the design and operation of surface tailings dams will have to be modified. Dams may have to be designed with flatter outer slopes of a reduced maximum height. Lower rates of rise may be required and, as a consequence, larger disposal areas may be demanded. To offset the negative aspects is the fact that the quantity of tailings requiring surface disposal will be reduced. The paper explores the dam-building properties of two cyclone overflow products. It shows that although these materials are inferior in dam-building characteristics to the corresponding total tailings, their geotechnical proper- ties still fall within, or close to, the range of properties typical of gold tailings. Although the design and operation of tailings dams may have to be modified, existing technology is adequate to handle these changes.

Jan 1, 1988

By M. Pötsch, W. Schubert, A. Goricki

Geological and geotechnical data are essential for the design of tunnels. To determine the rock mass behavior and the support of a planned tunnel excavation a consistent method for rock mass characterization and excavation and support determination has been developed. Probabilistic data processing with analytical methods is used for the quantification of the procedure and allows an evaluation of the applicability and the technical risk of different excavation and support methods. The sensitivity of the procedure on selected input parameters is highlighted in a parametric study. Finally an application of the procedure illustrates the use of the described method of probabilistic excavation and support determination for tunnels. Des données géologiques et géotechniques sont décisives pour la planification d’un tunnel. Pour la détermination du comportement des strates, le choix du soutènement et de la méthode de progression une description compréhensible de la montagne a été développée. À l'aide d'un traitement de données probabiliste, la procédure proposée est transposée quantitative sur une base de méthodes analytiques. De cette manière l'évaluation des méthodes de construction et la détermination du risque technique deviennent possibles. La sensitivité de la procédure de différents paramètres d'entrée est représentée dans une étude de paramètre. Pour finir, l'application de la procédure décrite est montrée à l’aide d'un cas pratique. Geologische und geotechnische Daten sind entscheidend für die Planung von Tunnels. Für die Ermittlung des Gebirgsverhaltens und der Festlegung von Ausbruch und Stützung wurde ein nachvollziehbarer Ablauf der Gebirgsbeschreibung entwickelt. Mit Hilfe von probabilistischer Datenverarbeitung auf Grundlage analytischer Methoden wird die vorgeschlagene Prozedur quantiativ umgesetzt. Dadurch werden die Bewertung von Baumethoden und die Ermittlung des technischen Risikos ermöglicht. Die Sensitivität des Verfahrens von einzelnen Eingangsparametern wird in einer Parameterstudie dargestellt. Abschließend wird anhand eines Beispiels die Anwendung des beschriebenen Verfahrens gezeigt.

Jan 1, 2003

By A. Chryss

Tailings management aims to dispose of tailings at the minimum cost consistent with meeting or exceeding imposed standards, including legislative obligations. This simple business objective requires managing the tailings storage facility (TSF) risks associated with surface water, groundwater, dust, sustainable closure, and potential catastrophic failure. The individual nature of every orebody and specific site topography ensures that no one size fits all. It has been suggested that paste and thickened tailings (P&TT) provides the ability to tailor the production and transportation of tailings to suit the deposition site, rather than the traditional approach of accepting that the deposition site has to accommodate tailings of high variability. While the traditional approach can be made to work, it is directly linked to the catastrophic failures of tailings impoundments, where large volumes of decant water have triggered failures due to overtopping, piping or slope instability, or saturated tailings have simply liquefied. P&TT offers an ability to mitigate these risks, and when implemented into new projects with variable tailings streams there are significant benefits to be realized. This paper identifies the interdependencies between the various tailings disposal processes, such as thickening, pumping, and deposition. It demonstrates that there are benefits in taking a more integrated approach to the design and operation of tailings disposal facilities. A collaborative industry project to tackle this challenge is described.

Jan 1, 2012

By F. Hees, A. H. Bracken, L. I. Boshoff

"Biological cementation of the Mandena heavy mineral sand deposit in Madagascar was causing difficulty in dredge mining and hence in planning and control of production rates. An investigation was initiated to better evaluate the geotechnical properties of the orebody by defining the distribution and geotechnical properties of the cemented strata, in order to generate a site-specific geotechnical model for the deposit. The geotechnical characterization was developed by an integrated approach using several ground investigation techniques such as piezocone (CPTu) testing, geotechnical drilling, standard penetration testing (SPT), as well as laboratory testing. The final outcomes of the investigation included a 3D geotechnical model showing the distribution and extent of the cemented areas, as well as the typical geotechnical parameter ranges associated with each of the defined geotechnical units. The interpretations developed were incorporated into the mine and production planning to ultimately optimize operational planning and control.IntroductionQIT Madagascar Minerals (QMM) is a heavy mineral sand mining operation at Mandena, near Fort Dauphin in Madagascar. During the final planning and commissioning stages of the project, the need to fully characterize the unusual geotechnical conditions was identified and a geotechnical investigation became necessary.Nature of the problemDuring the commissioning phase it was found that mining production was being hampered by biologically cemented/indurated layers encountered within the sands. Closer inspection of the indurated horizons in the dredging face revealed that these layers contain a high loading of bacteria and fungi. It appears that the bacteria produce an extracellular (outside the cell) polysaccharide (i.e. sugar and carbon salts), which form a gelling biofilm to trap nutrients. There are a number of different bacteria. The fungi, on the other hand, produce a network of fibrous strands that bind the sand grains together. Thus both bacteria and fungi probably contribute to the ‘apparent cohesive’ strength or binding of the indurated sand (Lynn, 2008)."

Jan 1, 2017