Search Documents

By Kurt RP Petersen, Hendriena van der Walt

With the decline in fine diamond production from the Argyle mine in Australia, there is a greater emphasis on efficiently treating the finer size fractions through a DMS circuit. Although it is generally well understood that smaller diameter cyclones are more appropriate for this application, practical results do not necessarily meet this expectation. In this paper the operational performance of particular sized cyclones throughout the group was compared. Based on the results there is evidence that under certain practical operating conditions, small cyclones are not necessarily best for fine size particle treatment, particularly given the production pressures faced by all mines. However, there seems to be considerable merit in using larger sized cyclones, which tend to exhibit less performance variability, irrespective of operation conditions.

Jan 1, 2006

By C. A. Ozturk

The compressive strength of rock (sc) has an important effect on design of structures in rock engineering. Compressive strength can be determined in the laboratory using the uniaxial compressive strength (UCS) test. Some other index tests, such as the point load test, are also used, particularly when suitable samples for UCS are not available. The quantification of rock texture has introduced a new method in rock engineering for estimating the mechanical and physical properties of rock materials from microscopic investigations. The aim of this study is to quantify rock texture to estimate rock strength from the texture coefficient (TC), which is determined from a statistical assessment of thin section images. Rock texture is quantified by twelve different images from a single thin section to increase the reliability of texture analysis. A data-set is prepared to investigate correlations between TC and sc. The statistical correlations are computed after classifying of the rock samples based on their lithology as well as grain features. Equations derived based on the results of this study are used to predict the approximate value of compressive strength from the texture coefficient. This method is particularly useful for preliminary studies in rock engineering projects prior to detailed site investigation.

Jan 1, 2014

By C. C. Pretorius

3D seismic surveys have become a well-accepted method of imaging sub-surface geology in the Bushveld Basin. Because both the seismic sources and receivers are placed at surface, most surveys are limited to imaging faults with >=7 m throw. However, some areas such as shaft infrastructure can benefit from the ability to detect smaller structures prior to shaft sinking. Borehole radar and logs such as the acoustic televiewer can identify these structures in the shaft barrel, but not within -200 m from the shaft. Therefore, Anglo Platinum has developed the method of high-resolution 3D vertical seismic profiles (VSPs) for structural sterilization of shaft sites prior to shaft sinking. VSPs utilize a surface source and sub-surface receivers deployed down a borehole. This means that seismic energy goes through the near surface only once, and therefore suffers less frequency loss than when both source and receivers are on surface. Furthermore, VSPs can record 3 component (3C) data which comprises P wave, Sh (horizontal) and Sv (vertical) wavemodes. Because S waves travel at about 0.6 of the velocity of a P wave, shorter wavelengths and therefore higher resolutions are possible using S wave data. VSPs were first used in their one dimensional, zero offset, mode to correlate borehole geology with seismic stratigraphy within seismic surveys. This showed that VSPs record -30% higher frequencies than surface seismic surveys. The program then applied two dimensional VSPs to the problem of imaging geological structure close to a borehole. 2D VSPs confirmed that high frequency results could be achieved, and that this enabled a more accurate image of the Merensky Reef than could be achieved by surface seismic data. Finally, the program has achieved the successful recording and processing of 3D VSP data, with both compressional and shear wavemodes giving a high resolution structural result. Although P wave data gives -30% frequency improvement over surface seismic surveys, S wave data can give as much as 80% improvement, further improving the structural image achieved. The high fixed costs of VSP surveys mean that they should ideally be run in multi-client batches, which can reduce the per borehole cost by up to 50%. Their application is anticipated to be on high value capital infrastructure with a geological risk from faults which are not imaged by surface seismics-generally in the sub-7 m range. Keywords VSP, 3D seismic, bushveld, platinum, resolution, imaging, shear waves, shaft sinking.

Jan 1, 2011

By A. D. Pienaar

The aqueous chemistry of niobium and tantalum compounds with hydrofluoric acid is a mature field of investigation. In contrast, very little attention has been paid to reactions of these compounds in non-aqueous environments. Similarly, reactions of elemental fluorine with niobium and tantalum compounds have received little more than cursory attention in literature. This work discusses the isothermal reaction kinetics derived from thermogravimetry, using a less redundant approach than is currently the standard. We also discuss the most likely kinetic models for this reaction.

Jan 1, 2012

Mineral Resource Throughput Management is based on the extraction of the maximum potential value from an ore reserve with the emphasis to generate maximum ROI and ROR (return on reserve). A steel producing company in India implemented MRTM to significantly improve their ROI and ROR. The value chain of this company consists of their own iron ore and coal mines, ore washing plants, sinter plants, steel plants, and sales and marketing division. The target for the mines was to produce at a stable and predictable rate and at specific quality requirements. These requirements were set to improve productivity and ROI of the steel plant. The implementation constituted the alignment of the reserve potential, total production chain, human resources and management culture at the mines with the requirements of the steel plant. Many typical mining practices were challenged and changed. Production targets regarding lump vs. fines ratio, consistent product tons, quality targets such as Fe, Al content and moist, and standard deviation on the quality targets were not achieved. A reverse distribution model with release mechanisms to satisfy the demand were developed and implemented at the mines. A stable and predictable flow of mine product with quality standards well within the required standard deviation targets were achieved. The contribution from the mines to significantly improve the Net Profit, ROI and ROR of the company were reached.

Jan 1, 2007

The reality of rising electrical power costs and the haunting prospect of decreasing electrical power availability are a threat to the growth of new projects and expansion programmes that could negatively affect the sustainability of mining operations. These threats require the adoption of effective power saving measures aimed at three principal objectives: the elimination of wastage, the reduction of power usage particularly during peak demand periods and, more importantly, improving the efficiency of high power-demand processes. It is reasonable to assume that the greatest impact will be achieved by concentrating on those processes that are large electrical power consumers. For Anglo Platinum operations, mine ventilation and, currently to a lesser extent, mine cooling are two continuous processes that fall in this category. It is estimated that these may consume fifteen to thirty-five per cent of the power delivered to the shaft head-depending on the shaft's design. Mine ventilation systems suffer from inherent, historical inefficiencies that lead to excessive power consumption. Air cooling systems are designed to be energy-wise in terms of modulating refrigeration plant operation to meet the underground requirements while maximizing use of 'free' cooling from surface conditions. Currently about ninety-five per cent of the refrigeration capacity used in Anglo Platinum mines is dedicated to surface bulk air coolers. The net thermal efficiency of these systems is compromised as mines expand in depth and on strike. Looking to the future, this practice will be complemented by more energy demanding underground cooling tactics requiring considerably higher electrical power consumption per unit ton produced. To counter this increase in power consumption, more energy-efficient systems and advantageous transient strategies such as thermal storage and the use of ice-on surface and possibly even underground-are being considered. This paper describes work currently undertaken and planned by Anglo Platinum operations to reduce power consumption by main fans during off-shift periods, the associated efforts currently introduced to reduce underground air leakage, the possibility of introducing more efficient auxiliary ventilation systems, the feasibility of thermal storage, and a brief look at energy recovery system as a means of countering the anticipated power demand associated with underground cooling. Keywords Mine ventilation, mine air cooling, energy efficiency, chilled service water, energy recovery, air wastage, fan selection.

Jan 1, 2011

A number of impending and actual pit wall failures have been observed and documented, which have been interpreted to initiate on newly generated structural features. This infers failure through intact rock. Failure mechanisms have been postulated resulting from circumferential stress, extensional strain and brittle flexure. These will be discussed in the context of the failures and the associated monitoring. The implications of failure initiating on ?unknown? features has a significant impact for deep open pit mines where designs are based on the expected structural regime. Being able to anticipate such failures is important for design. Equally important is management of such changes as they arise. In this context, monitoring using high resolution microseismic techniques will be discussed as a means of providing early warning of such failures.

Jan 1, 2006

By S. Pule, Z. Ndabezimbi, A. Hefer, E. Cupido

This article outlines various projects implemented at Rand Refinery to reduce effluent generation and freshwater consumption. The refinery generates about 2800 m³ of effluent annually and has initiated projects such as granulation water recycle and silver leach optimisation to address these issues. The granulation water recycle project has successfully reduced effluent volumes, while the silver leach optimisation has further decreased effluent by implementing stoichiometric addition of HCl and NaClO3. The vibratory shear enhanced processing (VSEP) trial showed promising results for gold recovery from wastewater, though further trials are recommended. The water savings of the effluent reduction projects are monitored by measuring the amount of effluent pumped to service yard effluent storage facilities with the use of flow meters connected on SCADA. Since the effluent reduction initiative of granulation effluent recycle in FY23, the effluent reduced to 2676 m³. In FY24, the stoichiometric addition of HCl and NaClO3 was implemented in the silver leach process, further reducing the effluent to 2083 m³.

Mar 5, 2025

By K. P. Kavun, M. N. Denisov

Discussed in the paper is the redesigned reserve/resource classification for solid minerals being put forth by the authors to replace the acting Russian classification of 19961. The new version is based on the traditional foundations of former Russian classifications and the principles of the ‘McKelvey box’, both categorizing mineral resources according to the degree of geological assurance and economic viability. Based on these approaches the classification deliberately deals with both reserve and resource categories very similar to those established by the Geneva Accords in terms of definitions implied. The authors proceed from the UN-ECE proposed concept of ‘reserves’ being a part of ‘total resources’ explored in great detail by geological and feasibility studies and economically mineable at the time of reporting. The draft classification distinguishes ‘proved’, ‘probable’ and ‘possible’ categories of reserves depending on the stage of feasibility assessment carried out, i.e. the degree of detail and accuracy with which modifying factors affecting mineability of an orebody are taken into account. The reserves are regarded as a product of feasibility assessment of ‘measured’, ‘indicated’ and ‘inferred’ resources. The portions of them not having been classified as ‘reserves’ are regarded as composed of two classes: ‘subeconomic’ and ‘potentially economic’ resources (or ‘resource base’). All the cells of the classification matrix are provided with traditional for Russia alphanumeric designations and appropriate UNFC codes. The classification scheme recommended is viewed as a step forward in improvement of the State inventory and reporting mineral resources in market conditions, conducive to cross-border professional collaboration in the field of providing reliable information on the mineral rawmaterials base of the world’s economy. Besides, it recommends an easy way to get rid of amethodological error in the UNFC classification scheme where consecutive stages of geologicalexploration are identified with a single inherent degree of geological assurance. Keywords: mineral resources, mineral reserves, classification, geological assurance, feasibility studies, subeconomic resources, undiscovered resources, competent person.

Jan 1, 2003

By D. H. Diering

The paper takes the reader into the depths of a modern ultra-deep South African gold mine and gives a perspective on the vertical and horizontal extent of the tunnel networks in such a mine. Depending on the mine design layout employed, tunnels once excavated are subjected to various levels of stress change over their life time, and the support requirements are explained. It is suggested that shotcreting is the only viable ultra-deep level support medium, and after looking at the latest developments, the logistical problems are put forward. In an effort to overcome most of these problems, the South African ultra-deep mining industry embarked on a collaborative research programme in 1998. The importance of tunnelling and in particular tunnel support as a critical technology for future successful ultra-deep level mining is stressed. While not yet fully ?on top of? these problems and challenges, our industry is now fully addressing them and we expect to make significant progress during the next 4 to 5 years.

Jan 1, 2000

By Mike McWha

Drivers to increasing RM use ?Compliance issues ?Section 12 JSE Listing Rules ?Canadian NI 43-101 ?Sarbanes Oxley ?Shortage of African ore reference materials ?Poor perceptions about quality of some local RM?s

Jan 1, 2005

By Arun Vathavooran, Adrian Singh, Michael Fletcher, Rainer Imhof

The Imhoflot G-Cell, a new development in the pneumatic flotation technology (which incorporates centrifugal forces in the separating vessel) is a recent innovation in the mineral processing world. The G-Cell was invented by Dr Rainer Imhof and commercialised by Maelgwyn Mineral Services Ltd. In a short time span a number of plants and units have been successfully commissioned in the mineral processing industry. In addition, a number of industrial G-Cell flotation plants are in the process of construction for the purpose of coal preparation and environmental remediation. In this paper two industrial installations have been highlighted together with a pilot plant test programme investigating ultra fine flotation recovery for a base metal operation.

Jan 1, 2007

By C. Sarkar

Increased competition in today’s global economy has put mineral industry under excessive pressure to effectively manage production assets to generate business wealth. Capital intensive industry (CII) organizations are seeking ways to manage skill resources, internal processes, and organizational networks with a view to reduce the cost of ownership of assets and increase efficiency of operations and service. The emerging concept of Enterprise Asset Management(EAM) is a collection of business processes that allow CII with right focus on return on investment on assets, to make right decisions on planning, acquisition, maintenance, operation, rehabilitation, and disposal of assets. Information technology (IT) can drive significant returns if the infrastructure covers seamlessly all business processes and all systems, like geographic information system, maintenance management, investment management, laboratory information management, and supervisory control and data acquisition system. The simple approach to IT in the past with disconnected silos of technology, information, and business processes cannot deliver the expected benefits under the modern business environment. Identification of business and application component is a prerequisite for the development of an asset management system that links effectively disciplined processes having characteristics of agility, speed, and integration. This paper discusses various issues and outlines the steps for developing an asset management roadmap in an organizsation. It also presents major business and application components of the system. Keywords: Enterprise asset management, Business architecture, Business component, Application component, Asset ownership, Asset operations, Information technology, Capital Intensive industry

Jan 1, 2003

By K. P. Davey

In 1998 an initial objective was given to the author, to process valuable off grade High Carbon Ferro Manganese (FeMn) metal fines profitably. The previous attempts that had been made to re-melt these metal fines through the furnaces had resulted in poor furnace operation, mainly to do with lack of electrode penetration and furnace bed permeability. It was decided that the method to resolve these problems was to agglomerate the metal fines. During the study on the agglomeration of the metal fines, a decision was made to use furnace baghouse dust and stockpiled furnace baghouse dust and sludge (DSF) as a ?filler? in the metal fines. The primary reason for using baghouse dust was to eliminate an environmental hazard, whereas the secondary reason for using the DSF was to utilize manganese units contained in the dust. The off-grade metal fines and dust were compacted using a brick press, with cement and aluminum rich plastic clay as a binder, to obtain agglomerate that was cost effective. Through the re-melting of the agglomerated off-grade metal fines, it was realized that this agglomerate concept could have other uses, that of replacing ores on the furnace, at a lower cost. The agglomerate recipe was changed to create an agglomerate that had a high manganese to iron ratio, this replaced Comilog ore on the furnaces, thereby reducing overall furnace unit costs. Future work concerning agglomeration, is to reduce furnace costs further through agglomerating .0.5mm ultra ore fines and .0.3mm Gloria and Nchwaning sludge. Using this agglomerate replaces a portion of the Gloria and Nchwaning lumpy ore on the furnaces at a lower cost. This would eliminate problematic material that exists at the ASSMANG Manganese mines.

Jan 1, 2004

By Y. Mitani, M. Xie, G. Zhou, T. Esaki

The assessment of landslide instability and risk has become a topic of major interest for both geoscientists and engineering professionals as well as for local communities and administrations in many parts of the world. In this paper, based on a new developed Geographic Information Systems (GIS) grid-based 3D deterministic model and taken the slope unit as the study object, the landslide hazard is mapped by the index of the 3D safety factor. Assuming the initial slip as the lower part of an ellipsoid, the 3D critical slip surface in the 3D slope stability analysis is obtained by means of a minimization of the 3D safety factor using the Monte Carlo random simulation. The failure probability of the landslide is calculated by an approximate method in which the distributions of f,c and the 3D safety factor are assumed to be in normal distributions. The assessment of the earthquake triggered landslide hazard is done by the dynamic displacement analysis using the index of the Newmark displacement. All the calculations are implemented by a computational system call 3DSLOPEGIS in that a GIS component is used for fulfilling the GIS spatial analysis function. Besides the results of 3D safety factor and probability, the possible landslide body and boundary can be three-dimensionally quantitatively identified. L’ estimation des glissement de terrain et des risques impliqués est devenu un des principal sujet de préoccupation pour les géotechniciens, mais aussi pour les ingénieurs specialisés ainsi que pour les communautés et administrations locales dans de nombreuses région du monde. Dans cette étude, basé sur un modèle de maillage 3D et une approche déterniniste couplée au Système d'Information Géographique (SIG), étudiant la stabilité des versants , le lieu d'étude à risque est maillé suivant le facteur de sécurité calculé en 3D. En supposant que le glissement initial soit la partie inférieure d'un élipsoïde, l'analyse de stabilité pour le glissement critique 3D d'un versant 3D est obtenu grace à une minimisation du facteur de sécurité en 3D utilisant la méthode de simulation aléatoire de Monte Carlo. La probabilité d'un glissement de terrain est calculée par une méthode approximative, supposant la distribution de c, f et du facteur de sécurité 3D normale. L'estimation d'un risque de glissement de terrain causé par un tremblement de terre est faite grace à une analyse du déplacement dynamique suivant l'index de Newmark. Tous les calculs sont effectués par le biais d'un système de calcul appellé 3DSLOPEGIS dans lequel te GIS est utilisé pour gérer l'analyse spatiale. En plus de cela, les résultats du coefficient de sécurité en 3D, des probabilités, le terrain susceptible de glisser, et ses limites, peuvent être quantitativement évalués en trois dimensions. Die Bewertung von Erdrutsch-Instabilität und risiko sind zu einem Thema von großen Interesse für sowohl Geowissenschaftlern und Ingenieuren als auch von Gemeinden und Verwaltungen in vielen Teilen der Welt geworden. In dieser Arbeit, basierend auf einem neu entwickelten Geografische Informationssysteme (GIS) gitterbasierten 3D deterministischen Modell und mit der Böschung als Untersuchungsobjekt wird die Erdrutschgefahr durch den Index des 3D-Sicherheitsfaktors kartografiert. Unter der Annahme, dass der erste Rutsch der untere Teil eines Ellipsoiden ist, wird die 3D kritische Schlupfoberfläche in der 3D-Böschungsstabilitätsanalyse mit einer Minimierung des 3D-Sicherheitsfaktors mit der Monte Carlo Zufallssimulation erhalten. Die Fehlerwahrscheinlichkeit des Erdrutschs wird mit einer Annäherungsmethode berechnet, bei der die Verteilungen von f,c und dem 3D-Sicherheitsfaktor als innerhalb normaler Verteilungen angenommen werden. Die Beurteilung der Erdbeben-ausgelösten Erdrutschgefahr wird mit der dynamischen Verdrängungsanalyse mit dem Index der Newmark-Verdrängung gearbeitet. Alle Berechnungen werden mit einem Berechnungssystem mit der Bezeichnung 3DSLOPEGIS ausgeführt, bei dem eine GIS-Komponente zum Erfüllen der GIS räumlichen Analysefunktion verwendet wird. Neben der Ergebnissen des 3D-Sicherheitsfaktors und der Wahrscheinlichkeit kann der mögliche Erdrutschkörper und der Umfang dreidimensional quantitativ identifiziert werden.

Jan 1, 2003

By O. Leuangthong, M. Nowak

"The impact of high-grade data on resource estimation has been a longstanding topic of interest in the mining industry. Concerns related to possible over-estimation of resources in such cases have led many investigators to develop possible solutions to limit the influence of highgrade data. It is interesting to note that the risk associated with including high-grade data in estimation appears to be one of the most broadly appreciated concepts understood by the general public, and not only professionals in the resource modelling sector. Many consider grade capping or cutting as the primary approach to dealing with high-grade data; however, other methods and potentially better solutions have been proposed for different stages throughout the resource modelling workflow.This paper reviews the various methods that geomodellers have used to mitigate the impact of high-grade data on resource estimation. In particular, the methods are organized into three categories depending on the stage of the estimation workflow when they may be invoked: (1) domain determination; (2) grade capping; and (3) estimation methods and implementation. It will be emphasized in this paper that any treatment of high-grade data should not lead to undue lowering of the estimated grades, and that limiting the influence of high grades by grade capping should be considered as a last resort. A much better approach is related to domain design or invoking a proper estimation methodology. An example data-set from a gold deposit in Ontario, Canada is used to illustrate the impact of controlling high-grade data in each phase of a study. We note that the case study is by no means comprehensive; it is used to illustrate the place of each method and the manner in which it is possible to mitigate the impact of high-grade data at various stages in resource estimation."

Jan 1, 2015

By A. Kapito

The ferrite-pearlite microstructure is the most popular microstructure for alloys used in structural applications, including railway wagon wheels. These alloys have been designed through alloying and thermo-mechanical processing to have a refined microstructure. Ferrite-pearlite alloys are low cost, weldable, have good fabricability, and are reliable under extreme conditions. Given these performance attributes, it seems unlikely then that their dominant position as structural steels would ever be challenged by alternative microstructures. One major achievement in the development of ferrite-pearlite steels has been in the refinement of their interlamellar spacing to very fine distances of the order of < 0.3 um. A refined microstructure increases the hardness of the alloy, thus increasing its life under wear conditions. The interlamellar spacing in pearlitic steels has, however, been refined almost to its theoretical limit. The increasing demand for speed and increased axle loading on railway wagons requires the use of stronger, tougher, and more durable materials. This has opened the window for the development of novel bainitic steels. Bainitic alloys have a higher level of microstructural refinement than pearlitic ones. They have shown to have good wear resistance and rolling-contact fatigue resistance, and high toughness. This paper will discuss the progress to date on the development of bainitic railway wheel alloys. Four alloy chemistries have been chosen for possible further development.

Jan 1, 2012

By H. Yilmaz

A testing method for assessing the shear-bond strength of thin spray-on liner (TSL) on rock substrate was developed at Wits University Rock Mechanics Laboratories. The gap between a 20 mm thick steel ring and a rock core is filled with TSL along the depth of the ring. After the curing of the TSL for a predetermined period, the sample is placed on a base, which offers support to the steel ring and the TSL but not to the rock core. A compressive load is applied on the rock core displacing the core on TSL contact and punching it towards the void in the support base. Shear-bond strengths for different TSL products as well as shotcrete were measured. This paper describes the test set-up and points out the important aspects and procedures during sample preparation and test execution. The test results are also presented and discussed.

Jan 1, 2007

By A. A. Angelov

This paper presents a unique method of monitoring the effectiveness of the planning process as well as the execution of mine plans. The method primarily determines the degree of deviation from the original mine plans by comparing actual mined areas to initially planned mining areas. The performance of mining operations is also measured by comparing actual and planned tonnages for a particular period. Once the degree of deviation from mine plans has been established the cause/s of the deviation can be determined through a simple fault tree analysis. Accurate identification of the reasons of deviation can aid the mine in selecting possible methods to correct the deviation. It is, however, beyond the scope of this paper to discuss the methods employed in correcting such deviations, as each mining operation will have unique causes of plan deviation and methods of remedying them. Deviations from the plan greatly affect the yields obtainable, which in turn affects the life of mine, thus having negative economic and financial implications. Accordingly, this paper presents a project management method which aims to reduce risk by improving planning systems to ensure optimum overall extraction of coal reserves.

Jan 1, 2010

By Rajendra Singh

Underground depillaring of contiguous coal seams/sections is a difficult problem, which becomes even more complex if the interburden/parting between them is thin. Conventionally, the depillaring with caving of contiguous seams/sections is done in descending order. However, if the parting is thin, the influence of the top sections/seams working over the standing pillars of bottom the sections/seams becomes extremely important for the safety and optimal exploitation of coal. Field investigations were carried out at Nowrozabad East mine where superimposed pillars of the Johilla top section were depillared above the developed pillars of the Johilla bottom section with a 3 m thick parting between the two sections. The competency of the 3 m thick parting (which consists of alternate layers of shale, sandstone and shaly sandstone) was improved by reinforcement (underpinning). The strata control investigations did not show any considerable instability problem of the 3 m thick reinforced parting and pillars of the bottom section due to top section depillaring. On the basis of this field investigation and a laboratory study on simulated models, simultaneous extraction of both the sections, along with reinforcement of the parting, was suggested for the geomining conditions of the Johilla top and bottom sections. Adopting the suggested simultaneous depillaring process, two sub panels of Johilla top and bottom sections have successfully been extracted without any strata control problem. This paper presents this case study along with the results of the strata monitoring conducted to evaluate performance of the underground structures during the field trial.

Jan 1, 2004