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By C. Swart

Automation technologies are increasingly adopted in different mines world-wide. This paper presents the technical aspects of vehicle automation applications at two Noranda operating mines. Teleoperation of 5 LHDs at Noranda?s Bell Allard mine is used in order to meet aggressive mining requirements under difficult conditions. The equipment is performing under high demand for reliability and performance. In order to further increase performance, automated loading has been commissioned on one of the LHDs and is being tested. Results to date indicate improved performance with respect to an operator through better filling of the bucket, fewer passes at the muck pile and shorter cycles. Noranda?s Brunswick mine is currently commissioning an automated haulage zone where two optically guided trucks transport ore from a remotely operated chute to two ore passes. Expected operational advantages include increased system capacity and enhanced safety and comfort for the operator. Monitoring to date indicates that the trucks can operate reliably under the conditions imposed by mine production.

Jan 1, 2002

By O. Naiker, T. Riley

Keywords: Pyrometallurgy, furnace, Xstrata, ferrochromium, Premus Technology The presentation will give a basic overview of Xstrata Alloys. Included will be a brief history of the Alloys division as well as of each plant within the division. The Xstrata chrome plants utilise a wide variety of production processes, including Xstrata's Premus process, the Outokumpu process, and the conventional process. Xstrata?s Lion Project is underway, with commissioning expected in the third quarter of 2006. The new smelter will utilize Xstrata?s patented Premus process, and the competitiveness of the Premus process is discussed.

Jan 1, 2006

By K. Coleman, C. Visser, N. Selby, X. W. Pan, T. Letwaba

A prototype weightometer soft sensor is under development at DebTech, De Beers in partnership with Venetia Mine. Its main function consists of an online data source; data validation; dynamic weightometer models; online detection of weightometer failure; alarming and replacing a weightometer when it fails. 31 dynamic models have been developed. All models with R2>= 85%are accepted as good models and they generally have satisfactory results with a daily error of less than 8% within 90% confidence level. By using those models, a set of soft sensors can be set up to cover all weightometers in the entire processes starting from primary crushing to the stock piles of dense medium separation (DMS). Some practical issues and concerns on model development are discussed, including data collection, data analysis, data pre-processing, variable selection, time delay, model training and model validation. When deploying the weightometer soft sensor system, the potential benefits could include: reduction in plant downtime; reduction in unplanned maintenance and even replacement of non-critical weightometers, particularly where nuclear weightometers are used. Keywords: soft sensor, weightometer, dynamic modelling, neural network modelling

Jan 1, 2003

By P. Wittke-Gatterman

ABSTRACT: A three dimensional constitutive law for swelling rock is presented. It can be applied to the osmotic swelling of mudstone as well as to the swelling of rocks containing anhydrite. It describes the development of time-dependent strains and stresses due to swelling considering elastic and viskoplastic behaviour. Furthermore an anisotropic swelling behaviour can be considered. This constitutive model was implemented within a numerical computation program according to the finite element method and calibrated on the basis of the results of measurements in the investigation drift of the Freudenstein tunnel which is completely located in the unleached Gypsum Keuper. A parameter combination could be found which results in a good agreement between numerical solutions and results of measurements. Therewith an analysis procedure which enables the design of tunnels in swelling rock is available. ZUSAMMENFASSUNG: Im vorliegenden Beitrag wird ein dreidimensionales Quellgesetz vorgestellt, das nach derzeitigem Kenntnisstand sowohl auf das osmotische Quellen von Tonsteinen als auch auf das Quellen anhydrithaltiger Ton- beziehungsweise Schluffsteine anwendbar ist. Das Stoffgesetz wurde in ein Finite-Elemente-Programm implementiert und anhand von Meßergebnissen des im unausgelaugten Gipskeuper liegenden Untersuchungsstollens des Freudensteintunnels kalibriert. Es ist gelungen, eine Kennwertkombination zu finden, mit der alle Meßergebnisse gut beschrieben werden können. Damit steht ein Bemessungsverfahren für Tunnel in quellfähigem Gebirge zur Verfügung. RÉSUMÉ: Dans l'article présent un loi de gonflement à trois dimensions est présenté, qui peut être appliqué aussi bien au gonflement osmotique de l'argile compactée q'au gonflement de l'argile compactée ou du limon compacté contenant de l'anhydrite. Le loi de comportement était implémenté dans un programme numérique d'éléments finis et calibré avec des résultats de mesures de la galerie de recherche du tunnel de Freudenstein, situé dans le Keuper de gypse non lessivé. On est réussi à trouver une combinaison de paramètres avec laquelle tous les résultats de mesures peuvent être bien décrits. Par ce moyen, une méthode de dimensionnement existe pour des tunnels dans de la roche capable de gonfler.

Jan 1, 2003

By P. Rosario

The application of high pressure grinding rolls (HPGR) has been growing in the mining industry for the last 10 to 15 years. The major benefits supporting this trend are better energy efficiency, improved grinding capacity, and higher metal recovery in downstream processes such as heap leaching and flotation. In general there is limited quantitative knowledge on the true benefits of HPGRs relative to SAG mills in comminution, and about which situations one deals with better than the other. This paper will present a structure for comparison of the energy requirements for HPGR versus SAG mill considering complete circuits for comminution of precious and base metals hard ores. The work presented is from the design of four complete circuits based on ore data from two sites.

Jan 1, 2010

By W. M. Jansen

In many mineral processing operations, the reported production figures for an accounting period may not make the best use of available data. While most of the mathematical approaches, such as check-in/check-out, mass balancing, used in effective metallurgical accounting strategies are well understood, the sources and magnitude of measurement errors generally are not. As part of the 'AMIRA P754-Metal Accounting and Reconciliation' project, a study was undertaken at the Northparkes copper/gold concentrator near Parkes, New South Wales to examine the data used in their concentrator metallurgical accounting system. This paper summarises the results of a detailed examination of the mass measurement systems around the concentrator as well as the primary sampling system used for grade estimation. The goal of this work was to develop practical techniques to quantify the error (ie both accuracy and precision) of the measured metal accounting information. With this information, statistical confidence levels for this data can then be calculated. If the errors are small, the effect of error in each piece of measured data can then be propagated to other calculated production figures such as recovery and feed grade using a statistical technique called `the propagation of error'.

Jan 1, 2007

Bateman Engineering managed the establishment of a second diamond treatment plant at the Letseng Mine in the Mokhotlong District of northern Lesotho, about 100 km from the town of Buthe Buthe. Letseng Diamonds Proprietary Limited, is owned 70 % by Gem Diamonds and 30 % by the Government of the Kingdom of Lesotho. The second plant, which commenced construction in late 2006, doubled Letseng Mines' hard rock processing capacity from 2.6 million t/yr to 5.2 million t/yr, making it the worlds' seventh largest diamond mine by throughput. Bateman Engineering provided the engineering design, procurement and construction management of the new plant.

Jan 1, 2010

By M. Abdellatif

Keywords: Pyrometallurgy, furnace, DC arc furnace, smelting, silicon The technical feasibility of silicon smelting in a DC arc furnace was investigated. A graphite-lined furnace was operated at power levels of 150 to 160 kW, and 40 to 60 V. The average feed rate during the silicon production period was about 30 kg/h. The recipe consisted of pre-mixed batches of 28% petroleum coke and 72% lumpy silica. The target furnace operating temperature was set at 1600°C and then raised to 1700°C. In total, about 1.6 tons of premixed feed materials was processed over 16 feeding?tapping operations. The feed was manually charged into the furnace in sub-batches of 10 to 40 kg at a time. The total batch mass was set at 90 kg during the initial part of the testwork, and increased to about 120 kg for the rest of the campaign.

Jan 1, 2011

By M. B. Fonseca

Risk quantification in grade-tonnage curves is critical for capital investment in mining projects and can be obtained through geostatistical simulations of orebodies. A practical difficulty may arise in multi-element deposits, as the joint modelling of the related attributes using the traditional co-simulation approaches is computationally intensive and may be impractical for use in the industrial environment. This paper presents the construction of risk-integrating grade-tonnage curves for a complex copper deposit in northern Brazil, by jointly simulating its key geochemical attributes of interest: Cu, Fe and K. The joint conditional simulation of these elements is based on Minimum/Maximum Autocorrelation Factors (MAF). MAF is an approach, based on principal components, that spatially decorrelates the variables involved to non-correlated factors. MAF’sspatial decorrelation at any lag distance is the main and critical difference of this approach from the principal component approach attempted in the past. In the MAF approach, the independent factors are individually simulated and back-transformed to the conditional simulations of the correlated deposit attributes that reproduce the cross-correlations of the original variables. Keywords: Joint simulation; mini/max autocorrelation factors; grade-tonnage curves.

Jan 1, 2003

By R. J. Hundermark

Keywords: Anglo American, Anglo Platinum Ltd, Waterval, Mortimer, Polokwane, ACP, pyrometallurgy, platinum, PGMs Anglo Platinum Ltd is the largest primary platinum producer in the world and operates three smelters in South Africa: Waterval, Mortimer and Polokwane. The operational details of the smelters are covered in previous reviews, thus only unit operations that have been upgraded are discussed. The most significant of the upgrades include the installation of a second ACP converter at Waterval Smelter in 2006 and the anticipated upgrade of Mortimer Smelter to 38MW in 2011. Several advances have been made in the smelting operations to improve the furnace stability and longevity. Control of the chromium input to each of the smelters has substantially allowed continued operations at levels below the spinel saturation point in slag, which results in lowered matte and slag temperatures. Mogalakwena concentrate, arising from the Platreef ore, is used to dilute high chromium-containing concentrates. In addition, furnace controls have improved in terms of crucible temperature and condition monitoring, improved feeding control, management of alarms and trips and having the quality of instrumentation and operational rigour required to support this. Advances have been made on the ACP converter in terms of good converter matte quality, and increased intensity and efficiency of operation. Combined with improvements to both the conventional and tower sulfuric acid plants, the emissions from Waterval Smelter have been reduced substantially since the introduction of the ACP. This is in spite of increasing metal throughput. The Anglo Platinum Ltd smelting operations have made significant progress since 2006 and further advances are envisaged to further improve on safety, reduce costs, increase efficiencies and throughput, while reducing emissions.

Jan 1, 2011

By W. D. Northrop

This paper gives an account of the development of a technique whereby the vertical limits of geological horizons may be identified by the use of vertical variograms on the mineral of economic interest. This information may supplement or guide the correct subdivision of the individual horizons into meaning full data sets by diligent geological observation. This process then improves the quality of the variance modelling of the gold distribution in the plane of the individual layers and therefore enables better estimates to be made into the grids or blocks of the mine model. The technique is explained by an account of the development work, which was performed, on duplicate superimposed reef horizons in the Kimberley formations. The paper then shows how the correct approach was developed to evaluate the mineralized layers in a multiple stacked conglomerate layer sequence in the Elsburg reefs of the Witwatersrand Rand System at the Target deposit. The method of categorization of resources according to confidence in the estimate is also explained. The feasibility processes carried out on the three-dimensional model, in accordance with the SAMREC code are also described. An example of the development of a reconciliation process utilizing chip sampling is also explained.

Jan 1, 2003

Keywords: Pyrometallurgy, Wits University, research Wits Metallurgy celebrated its centenary in 2004. The department has been at the forefront of education and research and has contributed greatly to the metals and minerals industry, both in South Africa and abroad, in terms of human resources and knowledge generation. A significant number of industry and academic leaders worldwide are Wits Metallurgy graduates. Since its early beginnings, pyrometallurgy has always been part of the curricula and research offered by the department. Pyrometallurgical activities started to expand tremendously from the middle of the 1960s, especially by the formation - together with Mintek - of the Pyrometallurgy Research Group, which continues its internationally recognised research activities today. The research efforts have been concentrated on problems associated particularly with ferroalloy, steel, stainless steel production, and PGM/Cu-Ni sulphide smelting. In recent years, research has been further expanded to physical modelling of pyrometallurgical reactors. Almost all of the specific research projects were handled from a fundamental point of view, and hence a large number of MSc(Eng) and PhD degrees were achieved by candidates under the supervision of the Pyrometallurgy Research Leaders. Moreover, a significant portion of the research results were published in internationally recognized journals and conference proceedings. Among these, Infacon and the Molten Slags, Fluxes and Salts Conference series are worth mentioning. The studies from a fundamental point of view include thermodynamics, phase equilibria, transport phenomena, kinetics, and process dynamic aspects of high temperature processes and systems, both in the solid and liquid states.

Jan 1, 2006

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

Beatrix Gold Mine, a deep-level gold mine in the Free State province of South Africa, has the highest methane emission rate of any gold mine in the country. Methane is emitted from underground sources intersected during mining operations and is liberated into the general mine atmosphere. The total methane emission rate for the mine is of the order of 16001/s and the South section of the mine emits approximately 10001/s of methane gas. The mine has a history of gas accumulations which have led to a number of underground explosions. Following the last explosion in 2001 and the subsequent investigation, a number of recommendations were made. Two of these were to consider extracting the underground mine methane to render the mine atmosphere safe, and to declare hazardous locations that require special operating procedures. A number of such workplaces have now been declared at the South section of the mine. Methane gas is a potent, explosive greenhouse gas whose contribution to global warming and climate change is 21 times higher than that of carbon dioxide. To reduce its inherent danger and to mitigate its global warming impact, a carbon credit project under the Clean Development Mechanism (CDM) of the Kyoto Protocol has been developed and implemented, the aim being to capture and destroy the methane at Beatrix mine. The mine has constructed an extraction system to capture and extract 400 (Is of the methane. Percentage methane (per volume) of the gas intersected at source is 85%, with negligible concentrations of other hydrocarbons and water associated. The mine contracted the services of Group Five to design and construct the flare and ancillary equipment on surface, and Promethium Carbon was contracted to assist with the carbon¬-related aspects, approval framework, and administration of the project. A number of design and construction challenges had to be faced to extract and transport the gas effectively to the surface of the mine as the emitters are approximately 3 600 m away from the mine shaft at a depth of 860 m. Further considerations were the requirements for the type of column to be used to transport the methane gas, the pressure loss over the system, the safety systems needed to address the risk factors involved in the transport of the methane gas, and a suitable pumping system to extract the gas to the surface. The system operates under negative pressure provided by two blowers on surface delivering the emissions to a flare capable of burning off 450 8/s of methane gas. In this paper a number of benefits for the mine are discussed. These include, but are not limited to, the removal of approximately 55% of the total volume of methane gas from the general body of the air in the geographical areas of the mine where the methane gas is emitted into the atmosphere, and reducing the risk of methane-related incidents. A further benefit of this project is the mitigation of the global warming impact of the methane gas and the reduction of the mine's carbon footprint by approximately 25%. This project could also assist in alleviating the energy shortage being experienced in South Africa by means of the planned generation of 4 MW of electrical power, utilizing the methane gas, as a second phase of the project.

Jan 1, 2011

By G. A. Bezuidenhout, J. P. T. Kapusta, D. K. Chibwe

"Peirce-Smith converters (PSCs) are extensively used in the copper, nickel, and platinum group metals industries. The typical converting operation involves lateral purging of air into molten matte through a bank of tuyeres. This blowing operation occurs at low pressure from the blowers, resulting in a bubbling regime that is considered inefficient from both a process and an energy utilization perspective. Inherent drawbacks also include recurrent tuyere blockage, tuyere punching, and low oxygen efficiency.Western Platinum embarked on a full-scale industrial evaluation of generating a jetting regime by using sonic injection. Prior to industrialscale tests, a numerical assessment to ascertain the feasibility of implementing sonic injection into a PSC was conducted. The work included flow characterization at high-pressure injection achieving sonic velocity at the tuyere exit. The 2D and 3D simulations of the three-phase system were carried out using the volume of fluid method together with the RKE turbulence model to account for the multiphase and turbulent nature of the flow.This paper discusses the key findings in understanding plume extension, velocity distribution, shear wall stress analysis, and phase distribution characteristics in the system. Plant trials are also discussed with reference to the commercial aspects of a full-scale implementation of sonic injection in the smelter."

Jan 1, 2015

By L. Andrews

Keywords: mineralogy, phase-chemical, chemical-looping combustion, XRD, SEM, EDS, QEMSCAN, PGM, slag, matte, ilmenite Mineralogy, traditionally associated with concentrator studies, is being increasingly applied to problems in pyrometallurgy. Such investigations commonly make use of a number of techniques, and the results are combined for a meaningful interpretation, which can lead to a successful solution. Mineralogical applications are described from pyrometallurgical operations. Examples are given of studies and investigations involving mineralogy in chemical-looping combustion, feed monitoring to platinum-smelting furnaces, and losses to slag in base metal and platinum smelting.

Jan 1, 2011

By S. H. Badenhorst

Zacharias Lewala discovered a diamond at Grasplatz, near Lüderitz in April 1908. While this stone may not have been the first diamond to be found in this barren, inhospitable area, it most certainly was the stone that set off a chain reaction ultimately leading to the creation of Namdeb as we know it today. [ ]

Jan 1, 2003

By M. Abdellatif

Keywords: Magnesium, pyrometallurgy, Mintek Extensive testwork on atmospheric thermal magnesium production has highlighted certain important fundamental and operational factors that have a major influence on magnesium extraction and its extraction rate, the condensation efficiency of magnesium, as well as on the quality of the condensed metal. The possible impact of these factors on the selection and preparation of raw materials, recipe choice, furnace electrical energy consumption, and on the refining requirements of the crude magnesium is discussed. Selected pilot plant operational and metallurgical data are also presented.

Jan 1, 2006

By M. Dworzanowski

The physical beneficiation of iron ore that has a wide particle-size distribution is problematic, regardless of the process applied, whether dense medium separation, gravity concentration, magnetic separation, or flotation. The problem of particle size is further compounded when there is a significant -10 µm fraction. Generally the approach to a wide particle-size distribution is to split into narrower size ranges and treat each separately. More often than not the -10 µm fraction is not treated but discarded. This approach results in a more complicated and expensive flow sheet and the loss of any potential value in the -10 µm fraction. Wet high-intensity magnetic separation (WHIMS) bench-scale test work was conducted on a haematite-rich material with a particle size of -200 µm. What made this material different was that it contained a 60% -10 µm fraction, hence discarding the -10 µm material was not an option. The objective of the test work was to determine how to maximize the recovery of the haematite across the full particle size range. Given the unusual particle size distribution, it was concluded that WHIMS would be the only practical beneficiation route. The -200 +10 µm and -10 µm fractions were treated separately and together under varying WHIMS conditions. For a given concentrate grade, the mass yield obtained was greater when the total particle-size distribution was treated. The inferred optimum conditions, using the same material, were tested on a pilot-scale WHIMS and similar results were obtained.

Jan 1, 2014

A201 aluminium alloy is a high strength casting alloy with a nominal composition of Al-4.6Cu-0.3Mg-0.6Ag. It is strengthened by the O(Al2Cu) phase and the ??(Al2Cu) phase during heat treatment. Further strengthening of this alloy system can be obtained through the addition of transition elements, but care must be taken as other elements might have adverse effects on the mechanical properties. The objective of this study is to determine the influence of Mn on the tensile properties of rheo-processed Al-Cu-Mg-Ag alloy A201. ThermoCalc software was used to predict the different phases that can be expected in the alloys, and scanning electron microscopy(SEM) with energy dispersive spectroscopy (EDS) was used to investigate the actual phases that formed. The influence of these phases on tensile properties is quantified. SEM and ThermoCalc revealed that there is an increased amount of the Al20Cu2Mn3 with increasing Mn. The tensile properties showed that high amounts of Mn do have adverse effects on the tensile properties of alloy A201, especially the ductility. Keywords Semi-solid metal (SSM) forming, alloy A201, intermetallics, Al20Cu2Mn3

Jan 1, 2011