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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 A. W. Sundström

This paper reviews the development and suitability of various important thermophysical and electrical properties with respect to base metal mattes. Areas of focus include the critical validation of measurements of viscosity, density, surface and interfacial tension, electrical conductivity, and an overview of the various experimental methods used to determine these properties. Accurate physical property data of mattes are critical in process modelling and computational fluid dynamic modelling of smelting and converting operations employed in the extraction of copper, nickel, cobalt and platinum group metals.

Jan 1, 2008

By G. A. Brown

A colloquium on industrial minerals entitled' A Strategy for Growth in the Industrial Minerals Sector' was held at Mintek on 5th November, 1991, under the auspices of the Extractive Metallurgy Sub-Committee of the SAIMM. The SAIMM had not been previously active in the field of industrial minerals, and the programme was designed to appeal to the middle management of mining and manufacturing companies in the industrial-minerals field. A total of 86 registered for the Colloquium, a predominance of the delegates (65 per cent) being non-members of the SAIMM. Two overseas delegates were registered after announcements

Jan 1, 1992

Using the philosophy that 'change cannot be introduced through memos-you have to get people emotionallyinvolved', SRK's Environmental Group in South Africa is helping clients communicate their environmental management objectives more effectively through the powerful medium of interactive industrial theatre. Existing and pending environmental legislation, international pressures, and growing awareness of the environment have led South African industry to the point where responsible care, for both the environment and the health and safety of those affected by the activities of an industry, is now a focus of management policies.

Jan 1, 1995

By P. C. -H. Rhee, H. -G. Lee, J. -H. Choi, D. S. Kim, S. -B. Lee

In order to predict the composition of inclusions and to ascertain a method to prevent inclusions from forming in liquid Fe-16 mass Cr alloy, a thermodynamic database was developed through a quantitative determination of thermodynamic relationships of Cr-Al-Si-Mn systems in the liquid Fe alloys. Applications of the databases to the prediction of Mn/Si complex deoxidation with Alin Fe-16 mass Cr alloy were demonstrated in succession. The electromagnetic levitation technique using a cold crucible was employed to separate inclusions from liquid metallic alloys completely and to prevent any contamination from surroundings. Various interaction parameters in the liquid Fe-16 mass per cent Cr alloy system were determined; these are: [eAl(Fe)Cr= 0.19/T, rAl(Fe)O,Cr= -0.01, rAl(Fe)O,Cr= -0.00013, eS1Cr(Fe)= -0.38/T,rSi(Fe)O,Cr= 0.007, rO(Fe)Si,Cr= 0.0044, rA1(Fe)Si,Cr= -0.0075, rSi(Fe)A1,Cr= -0.0078, rSi(Fe)Mn,Cr= 0.005, and rMn(Fe)Si,Cr=0.01.] An improved database, utilizing interaction parameters for molten metal determined in this study, and the Fact Sage slag database of the MnO-SiO2-Al2O3-CrOx-MgO system were used for thermodynamic calculations. These were carried out under various thermodynamic conditions, and results were compared with experimental data of Si/Al, Mn/Si, and Mn/Si/Al deoxidation equilibria. With the abovementioned results, together with experimentally obtained data, thermodynamic conditions were determined, in particular Mn and Si contents, under which liquid inclusions form in liquid Fe-16 mass per cent Cr alloy. The critical Al content in liquid Fe-16 per cent Cr alloy, above which solid inclusion of corundum phase ((Al,Cr)2O3) formed, was as low as 10 ppm. This indicates that extreme care must be taken in controlling the Al content in the metal to avoid formation of solid corundum phase ((Al,Cr)2O3) inclusion. The compositional change prediction of inclusions, which originate from slag entrapment and by Ca addition, was demonstrated by use of the alloy database optimized through this study, and the Fact Sage oxide database. For Si-deoxidized Fe-16 per cent Cr alloy, high Si and low basicity of slag are effective to obtain liquid inclusions. For Al-deoxidized Fe-16 per cent Cr alloy, it is important to keep the Si content lower than 0.1 per cent and it is required to add Ca. Keywords: inclusion, thermodynamic simulation, deoxidation, Fe-16 per cent Cr alloy,stainless steel, interaction parameter, cold crucible

Jan 1, 2004

By T. Maejima, K. Aoki, T. Mori, K. Iwano

Concerning the excavation of rock cavern, it is one of the most important issues to evaluate the behavior of rock joints. But few detailed measurements for joint behavior had been conducted. Therefore, in order to evaluate the stability of rock cavern, effective approach for monitoring and analyzing the joint behavior needs to be developed. In this paper, authors described the results of analysis for joint behavior during the excavation by comparing with both results of the in-situ measurement by BTV and the numerical analysis by MBC model. Bei Ausschachten von Gesteinshöhlen ist es von besonderer Bedeutung, das stark von den Verbindungsteilen beeinflusste Gesteinsverhalten zu bewerten. Jedoch wurden bisher nur wenige Beobachtungen über das Öffnungsverhalten von Verbindungen durchgeführt. Daher muss ein effizientes Verfahren zur Überwachung der Stabilität unterirdischer Höhlen und der Analyse des Verhaltens von Verbindungsstellen entwickelt werden. In der vorliegenden Studie beschreiben die Autoren das Verhalten von Verbindungsstellen während der Ausschachtung durch Vergleiche sowohl mit den Ergebnissen von in situ Messungen mittels BTV als auch numerische Simulation mit dem MBC Modell, welches auch Diskontinuitäten berücksichtigen kann. Quand il s’agit d’excaver une caverne dans une roche ayant des joints très développés, il importe fort d’évaluer le comportement de la roche. Cependant, le nombre d’observations du comportement des roches effectuées au niveau de joints est loin d’être suffisant. Par conséquent, pour s’assurer de la stabilité des parois des cavernes souterraines, il a fallu mettre au point une méthode fiable de détection et d’analyse du mouvement des joints. Dans cet article, les auteurs décrivent leurs études de comportement des joints pendant l'excavation, en comparant les résultats des mesures effectuées in-situ, dans un chantier d’excavation par BTV , avec ceux d’analyse de la simulation numérique par MBC permettant de tenir compte des discontinuités.

Jan 1, 2003

By J. K. E. Douglas

PRESIDENTIAL ADDRESS Given by Mr J. K. E. DOUGLAS, M.Se. (Eng.) (Rand) SYNOPSIS Lime is the most widely used and the cheapest chemical alkali known to man and virtually every product we use or eat has required lime in some phase of its manufacture. Its use goes back to the earliest days of man and many ancient buildings and writings bear testimony to this. The manufacture of lime involves quarrying, crushing and screening of limestone and the burning of the sized stone in kilns of which there are several types. The earliest kilns were of very crude design and only in comparatively recent times have large capacity, automated and scientifically controlled kilns been developed. The history of the South African lime industry is largely that of the three main lime companies and their story is briefly told. No other material used in industry has a greater diversity of uses or more varied functions and lime has applications in most South African industries. The main applications are in the production of gold and uranium, iron, steel and ferrochrome, carbide, sugar and paper and for water treatment, agriculture and building. The Republic is well endowed with high quality limestone and the conclusion is drawn that many other minerals will have been exhausted before we run out of limestone with which to process them. The expansion of the lime industry has in the past kept pace with the requirements of industry and the future demand is expected to grow in parallel with the growth of these industries. Since the war this growth has been phenomenal and with our expanding populations and abundance of raw materials it should continue in the years ahead. Limiting factors are the shortage of skilled labour and the distance from export markets. Confidence is expressed that the challenges of the future will be met and that the lime industry will continue to make an important contribution to the growth and prosperity of South Africa. INTRODUCTION Lime, gentlemen, is known to all of you. Like myself, most of you have undoubtedly found it to be, on the appropriate occasion, a most pleasant flavouring for gin. But this lime, or rather its juice, was in earlier days more than just a flavouring. In the days of sail it was vital to the health of sailors as a deterrant against the scourge of all sea-going men-scurvy. It thus played a small but important role in the opening-up of trade routes around the world on which was based the original wealth of many of today's more advanced nations. I propose to address you on the subject of lime this evening, not the citrus variety I have just mentioned, but the most widely-used and cheapest alkali known to man, which, largely unsung, plays an even more vital part in modern industry than did its namesake in the development of inter-continental trade. In the time at my disposal, I propose to tell you something of the history, geology and technology of lime manufacture. Then I will briefly sketch for you the development of this industry in South Africa and indicate the role it plays in supplying the requirements of many of our important industries. Finally we will attempt to look into the future. The importance of this chemical alkali to our modern civilization is seldom fully appreciated-virtually every product we use or eat has required lime in some phase of its manufacture, either directly or indirectly. It is one of those basic materials, along with iron, coal, sulphur, salt and petroleum without which industry and, in fact, our modern way of living could not exist. Fortunately, nature has endowed the world with a plentiful supply of the limestone from which lime is derived and most countries have deposits adequate for their requirements. As a result, not only has there been little trade in lime products between countries but in the past the widespread occurrences of limestone have set a pattern of numerous small plants each serving a limited area. These plants were generally crude affairs incapable of producing a quality product. It is not surprising that, in an industry comprised of small producers with limited financial resources and in fierce competition with each other, there was little interchange of information. Technological development was therefore slow and the industry tended to be regarded as a backyard operation. Its popularity was not enhanced by the fact that lime is difficult and unpleasant to handle if proper facilities are not provided. In recent years the lime industry has undergone very radical changes to meet the more exacting requirements of today's more sophisticated consumers. Only since the war have the larger companies emerged with proper management, highly mechanized plants and a scientific approach. HISTORY Lime was one of the first chemical reagents used by man and consequently lime burning is one of the oldest of the chemical industries. The use of limestone dates back to the stone age when primitive man used limestone to build fireplaces, construct shelters and make crude tools and weapons. It is probable that lime was first discovered by him when the stone in these fireplaces disintegrated to a white powder which he could use for decorative purposes. The first recorded use of limestone was when huge blocks of limestone were used to build the pyramids of Egypt in 4,000 to 2,000 RC. It was not long after this that the beauty of marble, which is in fact a limestone, came to be appreciated and it found wide application in sculpturing and for decorative wall construction. Originally lime, mixed with sand, was used mainly as a mortar for building purposes, the earliest record of its use for chemical purposes being in 350 B.C. in a report of the wreck near Marseilles of a ship carrying a cargo of linen and lime 'for its bleaching'1. Cato mentioned the burning of lime kilns in 184 B.C. and the Romans made extensive use of both limestone and lime for highway construction. A treatise on architecture by Vitruvius who had an official position in the rebuilding of Rome under the Emperor Augustus remained for nearly two thousand

By W. Pulles

Mining can adversely affect water quality and poses a significant risk to South Africa?s water resources. Proactive management of environmental impacts is required from the outset of mining activities in order to reduce this risk. Major strides have been made over the last 7 to 8 years, by both the Department of Water Affairs & Forestry (DWAF) and the mining industry, in developing strategies and management plans for the effective management of water within the industry. This has largely been achieved through the development of joint structures where problems have been discussed and addressed through cooperation. This process, which was started around 1991, has continued through to the present time. The mining sector management strategy has been developed at a number of different levels as follows: ?A detailed Management Plan, that sets out strategic objectives, broad strategies and functional and organizational arrangements. ?Operational Guidelines, that define and document specific operational procedures. ?Technical Guidelines, that define and document best practices for pollution prevention and impact minimization from mining operations. The Technical Guidelines consist of Best Practice Guidelines (BPGs) and Regulations.

Jan 1, 1999

The key aspects of process metallurgy that distinguish platinum group metal (PGM) concentrate smelting from that of other base metal sulphide concentrates are presented. These differences include considerably higher input chrome and magnesia contents that directly raise the slag liquidus temperature and have the potential to increase accumulations of refractory spinels. Most importantly, the higher processing temperature required for PGM smelting and the resulting very high matte superheat lead to considerably more onerous smelting conditions than those typical of other smelting operations. This has presented challenges to furnace design and integrity, especially when coupled with the progressive intensification of smelting, involving doubling, and then redoubling, of furnace power inputs over the past 20 years. These power increases have been enabled by increasingly more advanced furnace cooling and structural technologies. Key technologies include strong constant-force spring-loaded bindings acting in three dimensions to minimize infiltration of superheated matte into brick joints, and robust well-cooled tapholes for reliably tapping the superheated matte. The result has been substantially improved productivity, and reduced smelting capital cost outlay per unit of production. A significant challenge, which was not anticipated, presented itself in the form of insidious corrosion of the furnace lining, and especially high-intensity copper cooling elements. Investigation of corrosion in related industries eventually identified chloride-accelerated sulphidation', and this term has been retained as it generically describes the most pertinent aspects of the accelerated low-temperature wear of copper coolers observed in PGM smelting. In addition to discussing the corrosion mechanism, this paper describes a number of solutions that were developed jointly by Anglo American Platinum and Hatch to address the copper corrosion problem. First, new monitoring technologies allowed furnaces to be operated more safely for a longer period of time. Second, a system for replacing corroded coolers from outside the furnace during a fast 'hot' shutdown minimized the impact on furnace operating factor and hearth life. Finally, a corrosion-resistant graphite-protected cooler design significantly improved furnace campaign life, and heralds a more lasting solution to cooler corrosion in PGM furnaces.

Jan 1, 2013

By B. Derin, T. Uzunoglu, O. Yücel

In this study, reduction behaviours of Turkish chromite concentrate (48 % Cr2O3, 13.30 % FeO, 18.33 % MgO, 12.37 % Al2O3, 5.76 % SiO2) and nickel oxide by Fe-C alloy in graphite crucible were investigated. In the first stage of experiments, steel scraps were melted in graphite crucibles and were saturated with carbon at 1600 °C and 30 min. In the second stage, mixtures of different amount of chromite concentrate, nickel oxide and flux additives (CaO,SiO2 and CaF2) were charged into the graphite crucible containing the Fe-C alloy and heated to 1600 °C for different reduction times (0-180 min) under argon gas. The highest Cr and Ni con-tents in alloys were found as 11.41 and 14.37 % and the highest Cr and Ni recoveries were found as 88 and94 %, respectively at 180 min.

Jan 1, 2007

By V. H. R. Brereton

The gold deposits of the farms Lisbon and Berlyn in the Eastern Transvaal by V. C. H. R. BRERETON* (Visitor) This paper describes the discovery and recovery of gold, over a period dating back to the 1870s. on the farms Lisbon and Berlyn, situated approxim ately 1I km north-east of Pilgrims Rest. where mining ceased in July 1971. 99 years after gold was first discovered in the Pilgrims Rest and Sabie districts. Included in the paper are accounts of the discovery and mining operations of the Lisbon-Berlyn Company from 1884 to 1890. The operations of small companies and syndicates. the superficial winning of gold by diggers, and the encouraging reports of four mining engineers in 1890 are also mentioned.

Jan 11, 1973

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Jan 1, 2009

By P. G. Gresse

The Orange-Vaal River system is known to be the primary secondary source for alluvial diamond deposits in the northern Cape and along the west coast of Namaqualand. The higher order sources for diamonds contained within this system are still not defined entirely to satisfaction, but certainly include kimberlite pipes exposed in the catchment regions of these rivers. The focus of alluvial diamond mining along the Orange-Vaal system recently changed from the traditional areas in the upper catchment regions?the Barkly West, Christiana, Bloemhof, Wolmaranstad, Schweizer-Reineke region, and the lower regions near the mouth of the Orange River at Baken, Alexander Bay and Oranjemund, to the area between Douglas and Prieska?the so-called mid-Orange region (Figure 1).

Jan 1, 2003

By L. J. Olivier

The possible closure and subsequent flooding of South Deep Gold Mine?s (SD) neighbouring Randfontein Estates Limited No. 4 Shaft (REL 4) necessitated the construction of five concrete plugs in the connecting tunnels to prevent the ingress of groundwater into REL4 from flooding SD. This paper describes the proposed controlled flooding of REL 4, the planned in-service monitoring of the five plugs and the water barrier between REL 4 and South Deep Mine, and the long-term maintenance of the plugs and rock mass in the immediate vicinity of the plugs.

Jan 1, 2006

By H. M. Friede, R. H. Steel

Tin mining and smelting in the Transvaal during the Iron Age by H. M. FRIEDE*. Ph.D. and R. H. STEEL* (Visitors) This paper reviews the historical, archaeological, and metallurgical evidence on Iron Age tin mining and tin smelting in Southern Africa. The results of the analysis of twenty samples of tin ore, tin slag, and tin ingots found associated with Iron Age materials in the Transvaal (mostly in the Rooiberg area) are reported and discussed. The types of ingots preserved in local collections are described. A small experimental tin-smelting furnace was constructed and worked according to traditional African Iron Age technology. Qualitative and quantitative results of this experiment are reported.

Jan 7, 1976

By Simon Mundike, Muwindwa Lipalile

A scraper based block cave method has been successfully applied to extract the Lower Ore Body at Nchanga since the 1950?s. Since inception, scraper drifts and service ways have been supported using steel arch sets fabricated to a specific design from high strength manganese steel To reduce costs and to improve productivity, trials commenced in 2002 using fibre reinforced shotcrete as an alternative support method. One of the areas; the 2420 8E 1C trial drift was subjected to abutment loading for several months prior to undercutting and cave mining. Shotcrete installed exhibited minor cracking shortly after application but very little deterioration thereafter. Following the success of the trial, the application of fibre reinforced shotcrete was extended to other drifts. This paper describes the application of fibre reinforced shotcrete at Nchanga and outlines design and quality assurance methods employed.

Jan 1, 2005

By K. Ding

The thermodynamic activity of MnO was measured in MnO-CaO-MgO-SiO2 slags that are typically encountered in the production of manganese-containing stainless steels. A gas equilibration-quenching technique was employed in measuring the activities. Activities of Mn in Pt-Mn alloys were redetermined at 1600ºC, which reconfirmed earlier results of strong negative deviations. MnO activities were then measured by equilibrating slags of various compositions based on a statistical experimental design procedure with Pt-Mn alloys under controlled partial pressure of oxygen in MnO saturated platinum crucibles at 1600ºC. Activities of MnO were found to increase with increasing concentration of MnO, basicity and CaO to MgO ratio. Two multi-coefficient regression models were developed to predict the activities and activity coefficients of MnO in slags at 1600ºC. Keywords: activity, MnO, slag

Jan 1, 2005

By K. Aoki, Y. Mito, S. Shirasagi

The authors developed the TBM Excavation Control System (the TBM Navigator), in order to realize the advanced observational construction. During the excavation using this system, the rock strength value is immediately calculated from the TBM driving data as an index of rock properties, and the drill energy coefficient is also calculated from the drill logging data that is carried out using the probe hole ahead of the tunnel face. In this study, a new, geostatistical simulation-based method is proposed for the automatic prediction of the rock properties ahead of the tunnel face with good precision, using both the drill logging data and the TBM driving data. The applicability of this method is validated through the prediction at the actual tunnel excavation that passes through the faults. Les auteurs ont mis au point un Système de Contrôle de forage avec la machine à pleine section (Navigateur de la machine à pleine section), en vue de réaliser un système de surveillance plus efficace. Avec ce système, la résistance de la roche est immédiatement calculée, au cours du forage, à partir des données de conduite de la machine, comme indice des propriétés de la roche, et le coefficient d'énergie de la foreuse est également calculé à partir des données de log de forage collectées dans un trou de sonde foré dans le front de taille. Dans cette étude, on propose une nouvelle méthode basée sur la simulation géostatistique qui permet de prévoir d’une manière automatique, des propriétés de roches se trouvant derrière le front de taille avec une précision satisfaisante, à l’aide des données de log de forage et celles de conduite de la machine à pleine section. Cette méthode s’est avérée suffisamment précise au cours du forage d’un tunnel réel qui traversait une zone de failles. Die Autoren entwickelten das TBM Ausschachtungssteuerungssystem (den TBM Navigator), um noch besser überwachte Bauarbeiten zu ermöglichen. Unter Einsatz dieses Systems wird die Gesteinsfestigkeit während der Ausschachtungsarbeiten unmittelbar aus den TBM Antriebsdaten als ein Index für die Gesteinseigenschaften berechnet. Gleichzeitig wird auch der Bohrenergiekoeffizient aus den Bohrlogdaten berechnet, die an Hand der Probebohrung am Stirnende des Tunnels erhalten wurden. In der vorliegenden Studie wurde ein neuartiges, auf geostatistischen Methoden basierendes Verfahren für die automatische und angemessen genaue Vorhersage der Gesteinseigenschaften am Stirnende des Tunnels vorgeschlagen, für das sowohl die Bohrlogdaten als auch die TBM Antriebsdaten verwendet werden. Die Anwendbarkeit dieser Methode wird durch die Vorhersage bei einer tatsächlichen, durch Verwerfungen verlaufenden Tunnelausschachtung bewiesen.

Jan 1, 2003

By B. Tiryaki

Performance prediction models for partial face mechanical excavators, when developed in laboratory conditions, depend on relating the results of a set of rock property tests and indices to specific cutting energy (SE) for various rock types. There exist some studies in the literature aiming to correlate the geotechnical properties of intact rocks with the SE, especially for massive and widely jointed rock environments. However, those including direct and/or indirect measures of rock fracture parameters such as rock brittleness and fracture toughness, along with the other rock parameters expressing different aspects of rock behavior under drag tools (picks), are rather limited. With this study, it was aimed to investigate the relationships between the indirect measures of rock brittleness and fracture toughness and the SE depending on the results of a new and two previous linear rock cutting programmes. Relationships between the SE, rock strength parameters, and the rock index tests have also been investigated in this study. Sandstone samples taken from the different fields around Ankara, Turkey were used in the new testing programme. Detailed mineralogical analyses, petrographic studies, and rock mechanics and rock cutting tests were performed on these selected sandstone specimens. The assessment of rock cuttability was based on the SE. Three different brittleness indices (B1, B2, andB4) were calculated for sandstones samples, whereas a toughness index (Ti), being developed by Atkinson et al.1, was employed to represent the indirect rock fracture toughness. The relationships between the SE and the large amounts of new data obtained from the mineralogical analyses, petrographic studies, rock mechanics, and linear rock cutting tests were evaluated by using bivariate correlation and curve fitting techniques, variance analysis, and Student?s t-test. Rock cutting and rock property testing data that came from well-known studies of McFeat-Smith and Fowell2andRoxborough and Philips3have also been employed in statistical analyses together with the new data. Laboratory tests and subsequent analyses revealed that there were close correlations between the SE and B4 whereas no statistically significant correlation has been found between the SE and Ti. Uniaxial compressive and Brazilian tensile strengths and Shore scleroscope hardness of sandstones also exhibited strong relationships with the SE. NCB cone indenter test had the greatest influence on the SE among the other engineering properties of rocks, confirming the previous studies in rock cutting and mechanical excavation. Therefore, it was recommended to employ easy-to-use index tests of NCB cone indenter and Shore scleroscope in the estimation of laboratory SE of sandstones ranging from very low to high strengths in the absence of a rock cutting rig to measure it until the easy-to-use universal measures of the rock brittleness and especially the rock fracture toughness, being an intrinsic rock property, are developed.

Jan 1, 2006

By R. Romano

Some topics, which difficult the effective use of RMR for dam foundations, are reviewed and a new geomechanics classification system, DMR (Dam Mass Rating), is proposed -as an adaptation of RMR- giving guidelines for several practical aspects in dam engineering and appraisal of dam foundation. On revise quelques problems qui ont fait difficile l’application du RMR pour les fondations des barrages. On propose un nouveau classification système, DMR (Dam Mass Rating)-comme un désarroi du RMR-qui donne recommendations pour quelques problèmes pratiques dans le projet et construction des barrages, et de ses fondations. Es werden einige die praxisgerechte Nutzung des RMR (Rock mass Rating) erschwerende Themen betrachtet und ein neues Geomechanisches Einteilungssystem, das DMR (Dam Mass Rating), eine Anpassung des RMR, vorgeschlagen. Daraus resultieren neue Richtlinien für verschiedene praktische Aspekte beim Dammbau und bei der Beurteilung von Dammunterbauten

Jan 1, 2003