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By S. Moodley

In the chloride process for TiO2 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 1100ºC to yield gaseous metal chlorides. Although feedstock preference is largely based on TiO2 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 chlorinators; 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 µm 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. Ellis, J. Gagnon, L. Webb, M. Burr, D. Kakengela, D. Evans, A. Mirza

Lead-based alloys are used as the primary anodes for electrowinning from sulphate-based aqueous systems. Lead anode technology has evolved over the years, migrating from pure lead and lead-antimonial alloys to the present-day lead-calcium-tin alloys for copper electrowinning and leadsilver alloys for zinc electrowinning. Anode technology has also migrated from cast to rolled microstructures in search of improved mechanical properties and higher corrosion resistance. Although great strides have been made in the development of new alloys and production processes, the industry still has unresolved issues related to untimely corrosion, which limits anode life and may lead to higher contaminant levels in the metal being produced. Lead anodes corrode because of the difference in the chemical/electrochemical potential across the microstructural features of an anode. Given a very high purity material, we find that the grain boundary areas corrode significantly faster than the rest of the grain. A balance of alloying element selection and microstructural design allows the grain boundary area to be engineered, thus minimizing grain boundary corrosion. However, operational issues can lead to unexpected corrosion behaviours that we will discuss moving forward. The comments in this work, although directed toward copper electrowinning, can be extended to similar phenomena in other metals electrowon from sulphate media (i.e., zinc, nickel, cobalt, manganese). The life cycle of electrowinning anodes depends on tankhouse operating conditions and maintenance of the anodes, including cleaning and straightening. This paper will focus on the operational aspects of maximizing the utilization of lead anodes for base metals electrowinning.

Jan 1, 2016

By V-P. Takalo, M. Natsvlishvili, M. Hicks, S. Khizanishvili

"The complexity of copper-gold ores leads to large variations in recoveries and concentrate grades in the processing plant. Detailed chemical and mineralogical studies revealed considerable variation in the ratios of chalcopyrite, chalcocite, and oxidized copper minerals in the ore types studied. The end-member ore types are chalcopyrite-dominated and chalcocite-dominated, while most of the ore types plot between these end-members. In addition, increasing amounts of copper oxide and sulphate minerals result in a decreased response to flotation. Good recoveries and concentrate grades can be achieved from the chalcopyritedominated ore type, while the more altered chalcocite-dominated ore type is more challenging to enrich. IntroductionRich Metals Group (RMG) Copper in Georgia (Figure 1) produces copper-gold concentrates from two open pit mines, Madneuli and Sakdrisi, both located in the Bolnisi mining district in South Georgia. RMG and Outotec began a cooperative project with the aim of improving the recoveries and metal grades in concentrate by gaining an increased understanding of the ore variability and developing more efficient procedures for ore blending, grinding, and flotation. This type of mineralogy-led approach has already been used for other complex ores such as iron oxide copper-gold ores (Hunt, Berry, and Bradshaw, 2011), for iron ores (Lund, Lamberg, and Lindberg, 2013), and for Kupferschiefer ore deposits (Rahfeld et al., 2018).The project started with process audits and mineralogical and chemical characterization of process samples, followed by detailed chemical and mineralogical characterization of six different ore types with simultaneous flotation test work on the same samples. Since neither the recoveries nor the concentrate grades correlate with the head grades of the ores, the modal mineralogical composition, together with the ore hardness, proved to be the most promising approach in developing the geometallurgical classification of these ore types."

Apr 1, 2019

By S. L. Miller

The development of a pilot gold geostatistical ore reserve system proved that geostatistical methods worked well for the routine production of annual ore reserves on gold mines of the Gold Fields of South Africa (GFSA) group, and that the techniques could also be practically implemented, understood and accepted by Survey Department personnel. Many side benefits of the pilot system became apparent, and a variety of useful management information was provided by manipulating the data values that were already captured. It was decided that it was a priority computing project to develop a standard production system (GORS) for routine use by all the GFSA gold mines. Experience with the pilot system enabled detailed functional specifications for GORS to be laid down. These, together with group computing policy determined the terms of reference and constraints for the GORS development. System design could not be finalized until new and appropriate mainframe database software and graphics workstation equipment and software had been found. With these in place the basic system was structured to take best ad- vantage of the interactive features of the workstation, the number-crunching power of the mainframe and the flexibility offered by a relational database and associated 4GL tools. Application sub-systems were developed for data capture, statistical applications, geostatistical calculations, contour plotting and graphical queries. GORS is being introduced to the mines in a phased manner with suitable documentation, training and support structures to enable it to be routinely and effectively used on a day-to-day basis by all group gold mines.

Jan 1, 1987

By G. R. Addie

The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for rotodynamic (centrifugal) slurry pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids. Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems.

Jan 1, 2007

1. Book reviews Nonparametric geostatistics, by S. Henley. London, Applied Science Publishers, 1981. xiv + 145 pp. Reviewer: Douglas M. Hawkins Mineral deposits and global tectonic settings, by A. H. G. Mitchell and M. S. Garison. London, Academic Press, Geology Series, 198!. Reviewer: J. Lurie The mining and mineral laws of South Africa, by B. L. S. Franklin and M. Kaplan. Durban, Butterworths, 1982. Cloth, 240 X 150 mm, Lxxcii + 853 pp. R197,50 + GST. Reviewer: M. J. Martinson Aluminium- Volume II, by M. H. Govett and J. Larsen. Sydney, Australian Mineral Economics (Pty) Ltd, 1982. Reviewer: D. G. Maxwell International technology for the nonferrous smelting industry, by Noyes Data Corporation. Reviewer: D. A. Viljoen 2. New publications Coaltransport- an analysis of technical and economic factors, by Dag Pike. London, Financial Times, 1982. £86 (D.K.), D.S. $175 (overseas including first class airmail postage). Small solute concentration differences determined by interferometry, by H.E.L.G. Schweigart. Pretoria, CERG-CSIR (P.O. Box 395, Pretoria), 1982. 3. Mintek reports Report M8A determination, using solid zirconia electrolytes, of the activities of chromium oxide in ferrochromium alloys and slags at 1650°C. Report M31Software for the design of multivariable control systems by use of the Inverse Nyquist Array. Report M37A literature survey of the metallurgical aspects of minerals in Witwatersrand gold ores.This survey reviews the information in the literature Report M 39 The use of masking agents in the determination, by hydride generation and atomicabsorption spectrophotometry, of arsenic, antimony, selenium, tellurium, and bismuth in the presence of noble metals. Report M40 The use of X -ray-fluorescence spectrometry in the determination of uranium, cobalt, and sulphur in materials from mine dumps. Report M44 A n on-line dilution system for spectrometry ustng an inductively coupled plasma source. Report M47 The separation of trace elements from iron, and the analysis of iron-rock ores for use as reference materials. Report M49 A programme in BASIC for the appending of computer files. Australian coal The editors of World Coal and World Mining have announced plans to sponsor the IVth International Coal Exploration Symposium. The symposium will be held in Sydney (Australia) from 15th to 19th May, 1983. Small mine economics The editors of World Mining and World Coal have announced plans to sponsor the Second International Symposium on Small Mine Economics and Expansion in Helsinki, Finland, from 12th to 16th June, 1983. The first symposium was held in Taxco, Mexico, in May 1981.

Jan 1, 1982

By E. L. Forner, G. M. Miller, J. Scheepers, A. J. du Toit

"The sizing, designing, and costing of copper electrowinning circuits requires an in-depth understanding of the fundamental relationships between circuit parameters and the practical operation requirements. The aim of this investigation was to optimize total copper electrowinning project cost by mapping the operating limits of key mechanical equipment. The model was compiled by mapping various cellhouse layouts in terms of number of cathodes per cell, crane productivity, stripping machine productivity, and rectifier–transformer (rectiformer) sizing using data tables for sensitivity analysis. These parameters were then collated and evaluated on a cost by size basis. The model provides an optimum band of operation for cellhouse productivity and project capital cost for a typical range of production throughputs, from 10 kt/a to 200 kt/a cathode copper. The information may be used as a high-level selection guide to assist with identifying a costeffective copper electrowinning circuit design for a specific production rate. The data was validated and compared with existing copper electrowinning cellhouses around the world that typically install no more than 84 cathodes per cell. IntroductionThe sizing, designing, and costing of copper electrowinning (EW) circuits require an indepth understanding of the fundamental parameters as well as the practical requirements to optimize cellhouse productivity and capital cost. Although a significant amount of work has been done designing new copper electrowinning circuits, an in-depth evaluation of world operating data reveals that the number of cathodes per cell, which affects cellhouse layout and productivity, is not consistent for a specific production rate (Anderson et al., 2009; Robinson et al., 2003, 2013). Based on this premise, Kafumbila (2017) suggested that there are unanswered questions, such as ‘why are the numbers of cathodes per cell different for copper production rates of 20 kt/a and 40 kt/a?’In this paper, data tables are employed to map the operating limits and costs of key Cu EW equipment. An overall Cu EW project cost map is then compiled by collating optimum cellhouse layout (number of cathodes per cell), optimum crane productivity, optimum"

Nov 1, 2018

By S. Pathak, B. Nilsen

Abstract: In recent years, probabilistic approach with the calculation of probability of failure instead of a factor of safety against failure is emerging in practice. The main objective of the paper is to discuss a probabilistic approach in rock slope stability analysis for Himalayan conditions. Due to the fragile geology brought about by the tectonic movements along the hill slopes, dramatic variations of the topography and intensive surface runoff during every monsoon season, serious slope failures occur frequently in Himalayan region. Slope failures have also been triggered by seismic activities. The probabilistic approach is applied to stability analysis for a road cut along the Desander back slope of the Kali Gandaki hydropower project in Nepal. It is concluded that the probability approach offers a more accurate grasp of the actual condition than any factor of safety. Zusammenfassung: In den letzten Jahren ist es mehr gewöhnlich geworden, ein stochastisches Verfahren und eine Berechnung von der Wahrscheinlichkeit eines Zusammenbruchs statt einer Berechnung von Sicherheitsfaktoren zu verwenden. Das Hauptziel dieses Artikels ist das stochastische Verfahren in Stabilitätsanalyse von Gebirghängen, welches an Himalayische Verhältnisse angewandt worden ist, zu diskutieren. Wegen der spröden Geologie die durch tektonische Bewegungen entstanden ist und den dramatischen topographischen Variationen sowie viel Oberflächenwasser während des Monsuns, kommen in der Region des Himalayas oft mehrere erhebliche Abhangszusammenbrüche vor. Abhangszusammenbruche ist auch von seismische Aktivität ausgelöst worden. Das stochastisches Verfahren ist auch benutzt worden, um die Stabilität von einem Wegschnitt in dem Desander Gebiet von dem Kali Gandaki Wasserwerk-Projekt zu analysieren. Die schlussfolgerung ist, dass die Ergebnisse eines stochastisches Verfahren die wirkliche Verhältnisse eines Abhangs besser beschreibt als der Sicherheitsfaktor. Résumé:- Ces dernières années, une approche probabiliste basée sur le calcul d’une probabilité de cassure au lieu d’un facteur de sécurité préventif d’une cassure est de plus en plus utilisée. L’objectif principal de ce papier est de discuter une approche probabiliste de la stabilité de versants rocheux en himalaya. Due à la fragile géologie causée par les mouvements tectoniques sur les versants de collines, aux dramatiques variations de topographie, ainsi qu’au lessivage intense du relief à chaque mousson, de sérieux glissements de terrains se produisent fréquemment en Himalaya. Les glissements de terrain sont aussi déclenchés par l’activité sismique. Cette approche probabiliste est appliquée aux analyses de stabilité d’une section de route le long du versant arrière Desander du projet « hydropower » du Kali Gandaki au Népal. On en conclut que l’approche probabiliste offre une estimation plus précise des conditions actuelles que n’importe quel facteur de sécurité.

Jan 1, 2003

By Y. J. F. Haven, G. H. J. Kitson, D. G. Beadle

I have read this paper with considerable interest. By using an automatic instrument to assess the dust samples taken in South African collieries, the authors are ahead of the gold mining industry, which still uses the laborious method of microscopic assessment, with its limited accuracy, of the half-a-million dust samples taken each year. As the authors state, the result obtained from the photoelectric assessment of the samples is approximately proportional to the surface area of the respirable dust. However, modern theory is that, in assessing coal dust, it is the respirable mass which is important in determining the danger to health. Thus Table II of their paper is of considerable value in showing the relationship between the P.E.R. value and the mass concentration measurement. Unfortunately this table only gives the mean relationship. The important point is to know the scatter around this mean. If the scatter is small, then this mean value (for different operations) would have considerable value in converting from respirable surface area to respirable mass, but if the scatter is large, then such a conversion, using a fixed factor, will have little value. In the text the authors mention the range of values as being between 3 to 24, but without a statement on the number of samples used to determine this range and their distribution, this is a rather nebulous statement. I hope, in their reply, that the authors will give, in statistical terms, some statement on the overall correlation between these two parameters. I might add that at present a member of my staff is working on similar relationships for dust samples taken in gold mines. Another factor which may well be most important in determining the danger of dust levels in coal mines is the composition of the dust, specifically its quartz content. I understand that the authors have some information on this point, and to make their results of greater value in International comparisons of dust levels and the concomitant development of pneumoconiosis, it will be extremely useful if they could place this information on record. Even though, as I have said above, modern theory postulates that respirable mass is a better parameter to use than respirable surface area, the problem remains of how to measure this parameter with short time sampling, which, as the authors point out, is their preferred strategy for dust sampling and dust control. I know of no easily portable instrument, independent of external power supplies, which can, in 5 to 10 minutes, collect sufficient dust to enable it to be weighed accurately. Thus the authors' implied intention of continuing to sample by their present techniques and using their present parameter to report the results is, in my opinion, an entirely valid decision.

Jan 10, 1968

By W. P. Nel

A fuel cell is an electrochemical engine that converts the chemical energy of a fuel, such as hydrogen, and an oxidant, such as oxygen, directly into electricity. The emerging fuel cell industry may represent a major opportunity for the global platinum mining industry. This is because low temperature fuel cell systems use platinum group metals as catalysts. Fuel cell vehicles may become the most important driver of future platinum demand within years of their commercialization. A great number of factors impact on and drive the diffusion of fuel cell vehicle innovation. Such drivers range from energy security to environmental concerns and the technological development of fuel cells and systems. Such factors and drivers of fuel cell vehicle diffusion are combined with the generic ?body of knowledge? on ?technology forecasting? and ?diffusion of innovation? to design a framework that provides a holistic approach to the analysis of this complex enterprise. An attempt is made in this paper to address the following questions: Which types of fuel cells require platinum group metals? Which types of fuel cells will achieve dominant design status? Will fuel cell vehicles diffuse successfully? How big will the impact of successful fuel cell vehicle diffusion be on future platinum demand? How well do fuel cell vehicles compete with incumbent technologies such as spark-ignited and compression-ignited internal combustion engine-driven vehicles? How soon will oil depletion start to drive the diffusion of fuel cell vehicles? How important is hydrogen as a fuel? What impact does the inadequate hydrogen fuelling infrastructure have on fuel cell vehicle diffusion? The paper contains some initial results of a research project that has the aim of producing a schedule of future platinum demand generated from fuel cell vehicles. Keywords: diffusion of fuel cell vehicles, technology forecasting, platinum demand forecasting.

Jan 1, 2004

By R. Ajalloian, L. Karimzadeh

This paper describes the engineering properties of Givi dam foundation. Givi dam will be built across the Givi River on the andesitic rocks (Karaj formation) in Ardabil province (northeast of Iran). Geotechnical investigations including drilling, pumping tests, sampling for laboratory testing and discontinuity survey. Physical and mechanical properties of andesitic rocks such as density, water absorption, porosity, uniaxial compressive strength, triaxial compressive strength, durability and direct shear tests are evaluated in this paper. Discontinuity data are process for the determination of dominant sets and for the rock mass characterization in terms of classification systems ( RMR, Q and RSR ). Correlations between these three classifications are discussed. Le barrage doit être construit sur la rivi_re givi qui cou_e sur les andesites (formation de Karaj)dans la province d_ Ardebile situee_ a Nord- Ouest de l_ _Iran. Les études géophsique commesondage, Pompage. Et échantillonnage afin de verifier les discontinutés out éte_ effectuées. Lesproprietés physique et méchanique des roches andesifique ont éte_ verifieés. Les informations concernaüt aux discontinuitiés afin de montrer leur principale direction ont éte_ verifieés, les proprietés des roches dans leurs ensemble ont éte_ etudieés. Les divers classifications(RMR,Q,RSR ) ont éte_ comparés et analyseés. Dieses Schreiben ist zur Erklaerung der Ingenieureigenschaften ueber Baugrund des Givi Deiches.Dieser Deich soll im Givi fluss auf Andesitgesteine (Karaj formation) gebaut werden. Der platzdes Deiches legit im Ardebil Provinz nordwestlich von Iran. Geotechnische Untersuchungen Sind:Bohrungen, pumpen Versuche, Probenentnahme fuer Laborversuche, BrechbarkeitBestimmungen, physikalische und mechanische Eigenschaften der Andesitgesteine wurde hierausgewertet, wie Z.B.: Wasserleitfahigkeit, Porositaet, Scherfestigketswiderstand, Informationenueber Brechbarkeiten der Gesteine wurde gesamelt, und die meisten Brechbarkeiten bestimdamitman die Gesteine besser klassifizieren kann. In Endefekt wrid die Resultate verschiedeneKlassifizierung wie RMR, Q, und RSR besser geachtet und zusammen vergliechen.

Jan 1, 2003

By J. Sjöberg, P. Lundman, E. Nordlund, C. Quinteiro

Abstract In the Kiirunavaara underground mine, crude ore is transported through ore passes from the production levels to the main haulage level. Failure and stability problems have occurred in some of these ore passes, with increasing frequency as mining depths increase. In this paper, selected results are presented from a research project run by LKAB. The presentation focuses specifically on stability analysis. Numerical models were used to identify failure mechanisms, in conjunction with empirical data and engineering judgment. The most important controlling factors governing failure and damage in ore passes were quantified. A causative model was established in which failure mechanisms and failure development were described. This model was used to formulate a prognosis of future ore pass stability, and for recommending remedial measures. Résumé Le transport du minerai entre les niveaux de production et le niveau principal de transport, à la mine de fer de Kiruna, se fait par des passes à minerai. Avec la profondeur d'extraction grandissante, les problèmes de stabilité au niveau de ces passes à minerai se sont multipliés. Les résultats d'un programme de recherche sur la stabilité des passes à minerai à la mine de fer de Kiruna sont présentés dans cet article. Les mécanismes de rupture ont été identifiés à l'aide de modèles numériques, de données de terrain et du jugement empirique des ingénieurs. Les facteurs principaux controllant l'instabilité des passes à minerai ont aussi été quantifiés. Un modèle a été établi dans lequel les mécanismes de rupture et le développement des dommages ont été décrits. Ce modèle a été utilisé à fins prédictives et remédiatives. Zusammenfassung In der Grube Kiirunavaara wird das gewonnene Erz über Sturzschächte von den Abbauebenen zu der Hauptförderebene gefördert. Mit zunehmender Tiefe des Abbaus sind vermehrt Standsicherheitsprobleme in den Sturzschächten aufgetreten, die teilweise zu Verbrüchen geführt haben. In dem vorliegenden Beitrag werden ausgewählte Ergebnisse einer Forschungsarbeit des LKAB präsentiert. Dabei wird der Schwerpunkt auf die Standsicherheitsuntersuchungen gelegt. Zur Ermittlung der Bruchmechanismen wurden numerische Modelle in Verbindung mit empirischen Daten angewendet. Die wichtigsten Einflußfaktoren für das Versagen der Sturzschächte wurden ermittelt. Es wurde ein Modell zur Beschreibung der Bruchmechanismen und des Versagensablaufs aufgestellt. Dieses Modell wurde verwendet, um die Standsicherheit zukünftiger Sturzschächte zu prognostizieren und um Sanierungsmaßnahmen zu erarbeiten.

Jan 1, 2003

By Mark Craddock, Johan Swanepoel

In this paper we present The Ultimate Flotation Cell, a newly developed flotation cell that is proving very popular in the industry. All flotation cells have only one purpose and that is the recovery of the required product, the patented impeller and disperser system of the Ultimate Flotation Cell allows total flexibility in order to achieve the optimal recovery. This ability to tune the cell performance provides the optimization of the ?capture? (collection) stage, all existing models address the need for a wide bubble size distribution (100µm-2 mm) to obtain a better flotation size-by-size, Yoon, 1999,Yoon 2000, Franzidis and Manlapig, 1999. The Ultimate Flotation Cell provides flexible performance optimization. This ability to optimize the flotation regime particular to a specific ore is achieved by the following factors: ? The impeller allows vastly improved air induction rates compared to conventional and sparged cells. This ability to induce and disperse large quantities of air, in a controlled manner, allows the cells to be tuned to give the optimal Sb by varying the rotational speed via a VSD which every cell is fitted with. ? The patented impeller gives a very constant and stable air induction rate, which ensures that the cell?s circulation pattern is constant, giving a very stable surface, allowing optimal froth depth. ? Although conventional dart valve, level control can be offered, great success has been achieved with a simple draft tube/sand relief device. ? The cells have a inlet design similar to the old Denver ?Cell-to-Cell? design, which guarantees the at lease one pass through the mixing zone in each cell. Actual plant performance data will be presented from two plants, one in Zambia and the other in the DRC.

Jan 1, 2007

By S. Rupprecht, G. Rapson

Long blast hole drilling has been successfully implemented since the 1950s in caving operations, steeply dipping wide reefs and boxhole/raise developments worldwide. However, when applying long hole drilling to narrow tabular reefs, the challenges of achieving high economic drilling rates, combined with acceptable accuracy and appropriate powder factors have yet to be overcome. The focus in this paper is the selection, application and optimization of long hole drilling equipment at mining operations shallower than 2 000 meters. The drilling, blasting and cleaning operations have to be optimized as a process if maximum production at minimum per unit cost is to be achieved. For this to be possible, it is essential that the mine design and layout match the mining process being implemented. The critical parameters affecting the sustainable implementation of long hole drilling in stoping applications for platinum mines are improved safety and higher production rates compared to conventional methods. In terms of drilling, both top hammer and down-the hole hammer configurations have been considered. For economic drilling, the benefits of monitoring and optimizing performance (i.e. drill bit rotation, thrust, and percussive power) for specific rock types are discussed. While the drive is for longer, more accurate, smaller diameter holes to reduce drilling costs, the design of appropriate blast hole patterns and the corresponding charging and initiation systems is crucial for success. The effect of hole diameter and pattern on the powder factor, when comparing small diameter, shorter holes versus large diameter, longer holes, is a major factor in achieving good blasting results. Once appropriate drilling and blasting have been implemented, the cleaning process becomes a potentially critical operation to ensure the production, cost and safety goals are met. Hence, the blast hole pattern and charge have to be integrated for optimal fragmentation to suit the cleaning cycle for maximum production output. Providing that long blast hole drilling is applied as a process in a planned, committed and well-managed manner, the benefits in safety, production and cost over conventional methods should be achievable. However, if the implementation process is not planned and supported by all parties concerned, it will not be possible to succeed in the new operation. Hence, an implementation or roll-out plan of new technology is crucial for success.

Jan 1, 2004

By C. -I. Lee

Since the early 1970s, Korea has constructed many large-scale tunnels and underground storage caverns in response to the rapid industrial development. The rock mechanics engineers have accumulated valuable experiences in the area of underground space technologies. But they still face technical challenges in environmental and safety aspects. To discuss those challenges in Korea, a brief engineering description of underground space projects including oil and gas storage, food storage, pumped storage power plant, transportation tunnels, waterway tunnels, and radioactive waste disposal is presented. Mechanical and hydrological stability analyses of the storage caverns in Korea are also introduced. Depuis le début des années soixante-dix, le développement industriel rapide en Corée a entraîné la construction de nombreuses galeries et cavernes de stockage souterraines. Les ingénieurs de mécanique minière ont donc accumulé des expériences précieuses dans le domaine de la technologie de l’espace souterrain. Cependant, ils font toujours face à de nombreux défis techniques en ce qui concerne les aspects de l’environnement et de la sécurité. Pour présenter ces défis en Corée, l’étude présente décrit les projets d’espace souterrain, y compris le stockage de pétrole et de gaz, de nourriture, centrales de stockage pompé, tunnels de transport, tunnels navigables, et évacuation des déchets radioactifs. Des analyses de stabilité mécanique et hydrologique des cavernes de stockage en Corée sont aussi présentées. Seit Anfang der 70er-Jahre, baute Korea in Folge raschen Industriewachstums viele lange Tunnelsund unterirdische Lagerungsräume. Fachkräfte im Bereich Gesteinsmechanik sammeltenwertvolle Erfahrungen über unterirdische Raumtechnologien. Dennoch stehen sie auch heute nochvor technischen Herausforderungen im Bereich Umweltschutz und Sicherheit. Zur Erläuterungdieser Herausforderungen in Korea folgt eine kurze technische Beschreibung der Projekte zurSchaffung unterirdischen Raumes für beispielsweise Öl- und Gaslagerung,Nahrungsmittellagerung, Pumpspeicherwerke, Straßen- und Wasserstraßentunnels, als auchLagerung radioaktiven Mülls. Mechanische und hydrologische Stabilitätsanalysen derLagerungsräume in Korea werden ebenfalls dargestellt.

Jan 1, 2003

By C. Rodrigues

This investigation compares the gas adsorption behaviour and capacity of three bituminous coals from South Africa, of similar rank, by assessing the characteristics of the raw coal, as well as the resulting float and sink fractions (at 1.80 cm3/g) obtained by density separation of crushed coal samples. Calculations were also made to obtain the raw coal gas storage capacity from the weighted contribution of both float and sink fractions results, thereby permitting comparison with the analysed results of the raw coal. The study demonstrated that the clean fraction of a coal has the highest capacity to retain gas in the sorbed state, followed by raw coal, and lastly the sink fraction, and re?confirmed previous investigations that showed minerals to be inhibitors of gas adsorption and retention.

Jan 1, 2008

Bougainville Copper Limited (BCL) operates a 50 Mtpy copper/gold/silver mine and concentrator on Bougainville Island, Papua New Guinea. BCL has installed an in-house developed data logging and supervisory process control system using a DEC PDP 11/73 mini-computer in the mill and has recently installed a similar system in the crushing plant. Together with the central DEC VAX 11/780 computer, they form part of a high speed, fibre optic, local area network in the concentrator. The in-house developed software, known as BIAS (Bougainville Copper Information and Automation System), was developed as a low cost option to interface to a number of different existing plant input/output systems while providing the capability to make maximum use of computer networking facilities. The package includes the more usual control system colour displays and data logging features, but also makes provision for two novel features: (a) Any user connected to the computer network can access the system displays. This allows metallurgists and management to monitor (but not control) plant operation from their offices. (b) Specialized application programs for performing advisory and supervisory control, dynamic simulation, and data analysis are easily incorporated into the system. The mill process system currently runs rougher/scavenger flotation stabilizing control and general data logging. The crushing plant system currently performs data logging only; however it will soon be augmented with the facility to run dynamic crushing plant simulations. Future developments will concentrate on making greater use of the detailed information available from the mine's fully automatic truck dispatch system which runs on a VAX 11/780 computer. Milling process control will be expanded to examine possible economic control of the operation of regrind and cleaner flotation circuits. An advisory water management system to optimize water supply within powerhouse generating capacity constraint will also be investigated.

Jan 1, 1987

By S. J. Moema, M. G. Maruma, L. A. Mampuru, M. E. Maja

"The most commonly used high-chromium white cast iron (HCWCI) is the hypoeutectic white cast iron that contains 2–3.5 wt.% C and 10–30% Cr. This type of material relies on hard, brittle M7C3 carbides to impart good wear resistance. Due to its good wear resistance, this material has found application in the mining industry and cement industry. However, it has low fracture strength and this challenge led to research aimed at refining the microstructure. This was done by the addition of niobium in the range between 0.1 and 0.6 wt.%. In the as-cast condition, the addition of niobium was found to increase the fracture strength due to the finer eutectic microstructure. The hardness was also found to have increased slightly compared to the reference alloy with no niobium additions. Low fracture strength after heat treatment was observed in the Nb-added HCWCI, which is believed to have been caused by the precipitation of secondary carbides and the transformation of the matrix from austenite to martensitic. IntroductionFor the past few years Mintek has been involved in a project in which a number of alloys have been identified for grinding media applications. The high-chromium white cast iron (HCWCI) alloys were among the alloys researched for this application. The knowledge acquired from the grinding ball media research has now been extended to mill liners, which have traditionally been made of manganese-, chromium- and chrome-molybdenum steels. The replacement of worn mill liners costs the mining industry a significant amount of money and this has led to a need for continuous research to prolong the life of the liners. During milling operations, liner wear has an adverse effect on the capacity of the mill, the energy efficiency and milling efficiency and finally leads to relining, to replace worn liners."

Jan 1, 2016

By Oaitse Medupe

The feed to the BCL concentrator is made of the ore from Phikwe No3 shaft, Selebi shaft and Selebi North shaft. The receiving bin of the concentrator has daily throughput of 7869mt live capacity of ore with feed grade from underground operation of 0.70%Ni, 0.75% Cu and 0.05% Co. The valuable minerals in the ore are Pentlandite, Chalcopyrite. Cobalt is present mainly in the solid solution in pentlandite. The common non-sulphides minerals are Amphibolites, quartz, micas, and Feldspar while pyrite and pyrrhotite are the major gangue sulphides. Pyrrhotite contains between 0.1% and 1% Ni in solid solution. From the mineralogical investigation, it was found that approximately 65% of the pentlandite in the ore occurs as exsolutions in the pyrrhotite and the grain sizes ranges from 8 to 38µm. about 25% of the nickel bearing pentlandite is medium grained and subhedral. This kind of pentlandite occurs along the cracks of pyrrhotite or as inclusions in pyrrhotite. The rest of pentlandite present is disseminated in the gangue matrix. Because of the fine occurrence of pentlandite, fine grinding was conducted in order to improve the recovery as well as the concentrate quality. A series of subsequent flotation test were performed in order to evaluate grinds of 35, 40, 45, 50, 60 and 80% passing 75µm. It was observed that ? The mass pull increased together with increasing fineness of grind ? Similar nickel recoveries were obtained at 35 and 40% passing 75µm but from 50% and 60% the grind was seen to adversely affect the nickel recovery. At 80% passing 75µm the recovery increased by small amount. ? Flotation kinetics showed higher initial nickel recoveries but these did not translate into higher final recoveries. ? Grinding finer than 80% passing 75µm yield very high grades of the concentrate in the first minute of the flotation test, and the grade is dramatically reduced in the fifth minute of the test. It was concluded that the current grind of approximately 48% passing 75µm is close to the optimum and no significant benefit were found to be associated with finer primary grinds. The inconsistence of the grade and recovery as well as the pentlandite losses will be discussed. Keywords: Pentlandite, Nickel losses, Grain size, Flotation

Jan 1, 2007

Palabora Mining Company is operating a copper block cave mine in the Limpopo Province of South Africa. The mine was developed in the late nineties with a target ore reserve of 220 million tonnes of carbonatite at 0.69% copper. At 30,000 tonnes per day the operation had an estimated life of mine of approximately 23 years. Cave induced open pit side wall failure occurred in late 2004 with 130 million tonnes of waste reporting to the bottom of the open pit. This failure resulted in potential sterilization and dilution of the ore reserve and subsequent reduction in life of mine. Physical and numerical modelling indicated potential losses of up to 30% of the original ore reserves. Cave Management tools based on throughput principles are utilized to manage the failed waste ingress and ensure an optimum life of mine. Extracting the maximum rate possible, as soon as draw points are commissioned, with the view of achieving the highest production in the short term, is any mining operation?s goal as more money is required sooner. This approach, of course, improves the cash flow but presents a risk in the cave propagation profile as overall draw control is compromised. At Palabora it is evident from a Mineral Resource Throughput Management (MRTM) point of view that maximum production in the short term is not the solution. If high production rates are achieved and the profile of the cave is not manage correctly, this results in failed waste reporting to draw points earlier with adverse effects on grade. This would effectively and significantly shorten Palabora?s Life of Mine. The applications of good MRTM principles are required to assist the value chain for sustained profitability. The process commenced with change management paving the way for a better understanding and a holistic view for all role players.

Jan 1, 2007