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By Alan Bauer

SYNOPSIS A discussion is presented of the advances that have been made in rotary drilling in recent years and it is indicated how and why these drills have replaced percussive equipment even in the hardest formations at larger than 7 in. diameter. A method is presented showing how it is possible to estimate drill requirements and how to optimize drilling and blasting costs for a particular situation. To do this it is necessary to have, in addition to drill performance data, a knowledge of comparative explosive performance. Current methods of doing this are therefore critically appraised. As hole diameters have increased for overall drilling and blasting economies the question of fragmentation arises. In North America this has been approached on a try-it-and-see basis giving results that, in general, have been very satisfactory. The current drilling and blasting practices in North America are reviewed and reference made to the factors of importance in slope control.

By B. Moritz, W. Schubert, E. A. Button

ABSTRACT: Geological conditions associated with alpine environments in combination with high overburden in many tunnelling projects lead to squeezing behaviour. The main problems associated with such conditions include large deformations, overstressing of supports, and lack of face stability. In the past during Alpine tunnelling the problem of large displacements incompatible with rockbolt – shotcrete support systems have been solved by leaving gaps in the lining to accommodate excessive deformations. In the late nineties, yielding elements have been developed, which are integrated into the lining. The paper deals with the basic concept, the design and the application of that system, which has been successfully used in several Alpine tunnels. ZUSAMMENFASSUNG: Die geologischen Verhältnisse in den Alpen führen bei großer Überlagerung häufig zu starken Deformationen während des Baues von Tunneln. Die großen Verformungen führen in vielen Fällen zu einer Überbeanspruchung des Ausbaues und Problemen mit der Ortsbruststabilität. Früher ist man dem Problem der Unverträglichkeit des Ausbaues mit den hohen Dehnungen durch Freilassen von Deformationschlitzen im Spritzbeton begegnet. Vor etwa 10 Jahren wurden duktile Stahlelemente entwickelt, welche in die Spritzbetonschale integriert werden. Der Beitrag beschäftigt sich mit dem Konzept, der Planung und der Ausführung. RÉSUMÉ: Les conditions géologiques dans les Alpes conduisent fréquemment lors d'un grand recouvrement à des déformations fortes pendant la construction des tunnels. Les grandes déformations conduisent dans beaucoup de cas à une surtension du revêtement et à des problèmes avec la stabilité de front de taille. On a fait face plus tôt au problème de l'incompatibilité du revêtement avec les extensions élevées par libérer des rainures dans le béton projeté. Il y a environ 10 ans, des éléments sidérurgiques ductiles qui sont intégrés dans le béton projeté ont été développés. La contribution s'occupe de concept, de planification et de mise en oeuvre.

Jan 1, 2003

I appreciate the honour that has been bestowed upon me by my election as President of this Institute. We are starting what I believe will be a challenging year. The first challenge facing the Institute is financial. From the accounts for you will note that the Institute operated at a loss for the first time since 1987. average membership subscription was increased by only 10 per cent, reflecting desire to keep costs down in the minerals industry. The Institute will therefore to rely on other income to meet its budget requirements and break even financially. source of these funds will be the activities of the Technical Programme Committees. disciplines-Mining, Extraction Metallurgy, and Metals Technology are planning programmes for the coming year. I urge al members to increase their support of colloquia schools. Increased membership would also bring in more funds. Please, therefore, encourage colleagues who are not yet members of the Institute to join it.

Jan 1, 1991

By W. F. McKechnie

"Southern Africa is generally thought to be well explored, with only limited potential for major new diamond discoveries. However, Chiadzwa in Zimbabwe and reports of a significant new kimberlite find in Angola are testimony to the dangers attached to an attitude that ‘there is nothing left to find’.Since the major discoveries in the central interior of South Africa in the 1870s, diamond exploration in the region has been led by market and political factors that influence the key exploration drivers of opportunity and value proposition. Unexpected new discoveries by new players always impact on existing producers and, from time to time, denial of opportunity through political or protectionist policies has inhibited investment in exploration.Entrepreneurial exploration appetite in southern Africa will be tempered by the potential value equation and security of investment. Overlaid on this, developments in diamond recovery technologies provide opportunity to reinvigorate current mines and old prospects previously considered too difficult or costly to exploit. Position on the cost curve will remain a key factor for survival in an increasingly competitive environment. IntroductionThe diamond industry in southern Africa boasts a history of 150 years of discovery and mining, forming the cornerstone of development of the core, modern economies at the southern tip of Africa.Since the discovery, in the 1860s and 1870s, of the secondary diamond placers and primary diamond-bearing kimberlite deposits in the central interior of the then Cape Colony and Orange Free State, southern Africa has endured as the pre-eminent diamondproducing region in the world. Notwithstanding periodic competition from significant new discoveries in other parts of the globe and the paucity of recent, new discoveries in the region, its ranking is unlikely to change in the short to medium term.In a geological context the region contains the Kaapvaal-Zimbabwe and Angola-Kasai cratons, identified in terms of Clifford’s rule as areas inherently prospective for diamonds, being underlain by portions of the Earth’s crust that are tectonically stable and older than 1.5 billion years (Clifford, 1992). Although the Democratic Republic of Congo (DRC) would, in a geographic context, be considered to be part of Central Africa, for the purposes of this review it is included in southern Africa since northeast Angola and the adjacent parts of the DRC form part of the same geological terrane and diamond production from both countries needs to be considered together. Historical and current diamond production from the northeastern parts of the DRC around Kisangani is not considered to be significant and its inclusion in the overall numbers for the DRC does not materially affect the overall picture presented here."

Feb 1, 2019

Council for 1998/99 President R.P. Mohring President Elect J.R. Dixon Vice Presidents Senior M.H. Rogers Junior Dr L.A. Cramer Immediate Past President Dr N.A. Barcza Honorary Treasure J.A. Cruise Members of Council J.P.W. Bennie E.G. de Villiers A.A.B. Douglas F.M.G. Egerton R. Graham Dr R.G. Gürtunca Dr R.V.R. Handfield-Jones P.J. Knottenbelt R.G.B. Pickering* P.S. Piper Prof. R.F. Sandenbergh Dr T.R. Stacey D.J. van Niekerk P.J. Venter J.C. Viljoen

Jan 1, 1998

By S. K. Kawatra

Feasibility studies of the on-stream analysis of lead in mineral slurries by S. K. KAWATRA. P. Eng. (Canada). Ph.D. (Australia). M.Sc. (India) (Visitor) Instruments for the measurement of lead in mineral slurries by the use of isotopes can be based on the absorption of Iow-energy gamma rays, backscattering of beta particles, or X-ray fluorescence. The merits of each method are discussed, and the reasons for the selection of the beta-backscattering technique are given. A system using this technique has been designed, constructed, and tested on samples of concentrates from an industrial concentrator.

Jan 8, 1976

EMMES Sampling Conference BACKGROUND & INTRODUCTION ?Impala acquires toll material to supplement production from ROM ?Toll material consists of filter cake, slurry and catalysts ?Samples are collected to determine the commercial values of the lots ?Slurry deliveries projected to remain relatively constant at 120tons dry solids per month, whereas filter cake deliveries set to increase five-fold to 800 tons dry solids per month ?Due to projected increase in toll material, new sampling and offloading facility presently under construction at Impala ?Presentation will cover two projects aimed at reducing the uncertainty associated with sampling of toll deliveries ?i.e. slurries and filter cake.

Jan 1, 2005

By M. U. Ozbay, D. R. Lougher

An in-situ experimental programme was carried out to improve the understanding of the rockmass and pillar behaviour in moderately deep hard-rock mines. The experiments were carried out at Impala Platinum mines and consisted of precise levelling measurements in the footwall of the reef, stress measurements in pillars, convergence measurements in the stope, and petroscope observations in pillars. The results were analyzed using a computer program in an attempt to quantify the characteristic behaviour of the rockmass as well as the pillars. The measured off-reef displacement data were found to co11fonn to the trends obtained from elastic modelling and the correlation could be improved by modelling the small pillars with reduced modulus to simulate yielding' of the pillars. The stress strain curve obtained from analyzing the in situ results, showed that a 6x 3 xl m pillar yields without significant load shedding at peak stress levels of approximately 208 MPa. The closure measurements confirmed that the mechanism of yielding is mainly that of pillars punching into the foundations. Slight to moderate sidewall fracturing and slabbing might be contributing to yielding, but to a much lesser degree than the former mechanism, as the petroscope observation revealed the existence of an intact region beyond 0,6m from the pillar sides.

Jan 1, 1995

By D. A. Fenton

The structural design of large grinding mills, with reference to shell-mounted bearings by D. A. FENTON*, P. Eng. (Visitor) The paper outlines the advantages of shell-mounted grinding mills over mills having a conventional trunnionsupported shell. The growing use of larger mills in the past decade has led to a significant number of mechanical and structural failures, the most common being those at the junction of the head and the shell. Larger mill diameters favour the use of shell-mounted bearings. The elimination of castings, which have an inherent weakness to fracture, makes the shell-supported mill lighter and stronger than a conventional mill of the same shell thickness.

Jan 9, 1976

By J. Petersen, H. Naderi, H. Zare, M. H. Nikzad, M. Karimi

In the copper electrorefining process, the dissolution of anodes is significantly reduced or even stopped when the passivation phenomenon occurs. The results of this phenomenon are increasing energy consumption, residual formatting, and voltage levels in the cell. In this study, the electrochemical behaviour of blister copper in the presence of sodium persulfate (PDS) was studied. The electrochemical methods of LPR, Tafel, and Electrochemical Impedance Spectroscopy (EIS) were used. The results showed that the addition of sodium persulfate activates the electrode surface and increases the open circuit potential. In the presence of PDS, the polarisation resistance of the electrode shows an increasing or decreasing tendency, based on the PDS concentration. This tendency is probably due to the formation of surface layers (such as slime layer or copper sulfate) and dissolution of this layer at various concentrations of PDS. The lowest polarisation resistance of 1.8 ohms and the highest corrosion current of 60.6×10-3 and 36.6×10-3 A/cm2 from LPR and Tafel techniques respectively were obtained at the concentration of 40 g/l PDS. Based on the results of potentiodynamic and electrochemical impedance spectroscopy tests, the addition of sodium persulfate to the solution reduces the corrosion resistance, therefore the passivation time of the blister copper anode increases. Keywords: Blister copper, electrorefining, sodium persulfate, anodic passivation

Jan 1, 2020

By C. S. Oteo, H. Suárez, P. de la Fuente

ABSTRACT: In the south of the Island of Gran Canaria (Spain) there appear layers of swelling clays inside volcanic formations of a fonolitic type, down to depths as low as 500 m, with thicknesses of 1 to 3 m. Two tunnels (each of length 1,500 m) have been built in these zones (ignimbrites and swelling clays), work on which started in the ‘70s. The construction has been influenced by phenomena of expansivity and decompression. Presented below are the problems that arose, the field and indoor studies conducted and the numerical optimisation of the lining. ZUSAMMENFASSUNG: Im Süden der Insel Gran Canaria (Spanien) kommen im Inneren vulkanischer Formationen phonolithischen Typs in Tiefen von bis zu 500 Metern 1 bis 3 Meter dicke Blähtonschichten vor. In diesem Gelände aus Schmelztuff und Blähton begann man zu Beginn der siebziger Jahre, zwei Tunnel von jeweils 1.500 Metern Länge anzulegen. Die Bauarbeiten standen unter dem Einfluss von Dehnungs- und Dekompressionserscheinungen. Der folgende Text enthält eine Darstellung der aufgetretenen Probleme, der durchgeführten Feld- und Laborstudien und der numerischen Optimierung der Tunnelauskleidung. RESUME: Dans le sud de l’Ille du Gran Canaria (Espagne) on a détecté des couches d’argile gonflante dans l’intérieur des formations de roches volcaniques fonolitiques, à la profondeur autom des 500 m, avec épaisseur de 1 à 3 m. On a perforé deux tunnels (de longueur 1.500 m chaque un) dans cettes zones (igniumbrités et argiles gonflantes), chantier qui comenza pendant les 70’. La construction on a influencé pour des phénomènes d’expansivité et de décompression. Dans cette communication on présente les problèmes presentes, les études de chantier et théoriques realicés et l’optimisation numérique développé pour dimensionner le revêtement.

Jan 1, 2003

By D. -H. Park, G. -j. Kim, Y. -J. Park, C. -S. Hong, S. -Y. Choo

To evaluate the quantitative tunnel behavior influenced by characteristics of discontinuity, this pa-per executes the parametric study using 2 and 3-dimensional DEM analysis. First of all, this study finds that displacement and the stress of shortcrete are proportioned to frequency of joint and rockbolt axial force is adversely proportioned too. Secondly, it is found that the most sensitive in-put parameter used in Barton-Bandis(BB) model is residual friction angle. Finally, when joint sets are encountered at tunnel excavation face, to identify the most critical joint orientation is very crucial for a stability of tunnel. La thèse a pour but d’étudier les influences sur la stabilité du tunnel, au niveau du réseau de la discontinuité et de la valeur de sa nature aquis par le projet récemment exécuté en vue de mener à l’analyse quantitative de cette stabilité, en appliquant chaque différent paramètre comme la fréquence de diaclase, la constante de résistance des modèles de Barton-Bandis(BB) ainsi que la relation entre le sens d’excavation du tunnel et le réseau de diaclase en 3 dimensions. En fait, cette étude nous a montré que la fréquence de diaclase s’accroît proportionnellement au déplacement et à la contrainte du béton projeté. L’angle de friction résiduel s’est montré le plus sensible à la stabilité du tunnel parmi les modèles de BB. Aussi à travers l’analyse à 3 dimensions, il s’est vérifié que si l’angle de pente du groupe de diaclase est horizontal entre l’axe du tunnel et la direction, il donne une influence importante sur le comportement du tunnel. En particulier, l’influence était la plus importante sur un fond rocheux dont la diaclase horizontale est grande. Um das quantitative Verhalten des Tunnels zu bewerten, eroertert dieses Papier eine parametrische Studie mit Hilfe der DEM Analyse. Auch wird hier eine zweidimensionale Analyse von Ver-bindungen verschiedener Frequenzen in der Gesteinsmasse, eine sensitive Analyse von allen der im Barton-Bandis-Modell (BB) genutzten Parameter und eine Dreidimensional-Analyse mit ver-schiedenen dreidimensionalen geometrischen Veteilungen von Verbindungen ausgefuehrt. Erstens: Die Studie findet heraus, dass Vedraengung und Druck im Shortcrete proportional zur Frequenz von Verbindungen und Axialkraft der Steinbolzen antiproportinal ist. Zweitens: Es wird herausge-funden, dass die am meisten Sensitiven der im BB-Modell angewendeten Eingaben die am Ende uebriggebliebenen Reibungswinkel sind. Und schliesslich wird herausgefunden, dass wenn Ver-bindungsteile an der Tunnelaushoelungsoberflaeche ausgemacht werden, fuer die Tunnelstabiltaet die Identifikation der meist kritischen Verbindungsorientierung sehr bedeutungsvoll.

Jan 1, 2003

OFS Branch Minutes of the General Meeting Held at the President Steyn G.M. Ltd Canteen on Wednesday, 13th November, 1974, at 3.55 p.m. Mr D. A. Smith (Chairman of the O.F.S. Branch) was in the Chair. There were also present: Nim reports Report no. 1696 The preparation and certification of a reference sample of a preciousmetalore. Report no. 1705 The effects of various matrix elements on the efficiency of the fire-assay procedure using nickel sulphide as the collector. Report no. 1720 The initial development of processes for the direct leaching of iron-nickelcopper mattes containing platinumgroup metals, and for the production of ferronickel.

Jan 5, 1975

Contribution by G. Narsimhan It was with much pleasure that I went through D.F. Malan's excellent paper. The following explanatory and critical note has been the result of my deep study of the paper. Although by qualifications and experience I have been a chemical engineer, involved over four decades with problems in the modeling and simulation of transport-limited (heat and mass) chemical reactions in multi-phase systems, I have of and on interested myself in challenging problems in extractive metallurgy. This is the first time I have veered of to continuum mechanics, at the age of 71! Author's reply. I thank Professor Narsimhan for his extensive contribution to the paper. It provided me with the stimulus to derive an extended model. However, there are some inaccuracies in his arguments that need further discussion. Professor Narsimhan's main concern is that there is not a good enough fit between the derived viscoelastic Kelvin model and the experimental data supplied by Güler1 (see Figure l1 on page 218 of my paper). I will therefore explain the choice of a viscoelastic model in more detail and also make specific comments on the arguments given in his contribution.

Jan 1, 1996

1. New books 1979 Louisville Coal Conference proceedings. Epping (England), Bowker Publishing Co., 1980. 4 vols. $43.00. Proceedings of a joint meeting of the Institution of Mining and Metallurgy, the Society of Mining Engineers of AIME, and the Metallurgical Society of AIME, held in London, 27 to 30 May, 1980, by M. J. Jones (ed.). London, Institution of Mining and Metallurgy, 1981. 350 pp. £46. Economic mineral deposits, by M. L. Jensen and A. M. Bateman. 3rd ed. New York, John Wiley, 1981. 752 pp. $22.95. E & MJ intErnational directory of mining and mineral processing operations. Epping (England), Bowker Publishing Co., 1980. 1314 pp. $67.00. Physical methods in modern chemical analysis, by T. Kuwana (ed.). New York, Academic Press, 1980. Vol. 2. 432 pp. $38.25. English translations of DIN standards. Availablefrom the SABS, Private Bag 191, Pretoria 0001. Mining international year book. London, Financial Times, 1981. 730 pp. $90.00 airmail, £37.50 surface. Analytical atomic absorption spectroscopy. Selected methods, by J. V. van Loon. New York, Academic Press, 1980. 360 pp. $35.00. 2. NIM reports Report no. 1848 An electrochemical and kinetic investigation of the behaviour of gold in chloride solutions. I. The cathodic deposition of gold. (First issued 7th Jul., 1976.) Report no. 1844 An electrochemical and kinetic investigation of the behaviour of gold in chloride solutions. 11. The anodic dissolution of gold. (First issued 7th Jul., 1976.) Report no. 1846 An electrochemical and kinetic investigation of the behaviour of gold in chloride solutions. 111. The gold(II1)- gold(I) eaction on platinum and the disproportionation of gold(I). (First issued 7th Jul., 1976.) Report no. 1979 An electrochemical investigation of the behaviour of gold in chloride solutions. I V. Results obtained from Phase 2 of the investigation. (First issued 30th Jun., 1978.) Report no. 2093 The measurement of electrical variables in a submergedarc furnace. Steels for pipelines Since welding was first introduced as a method of joining pipelines, gas-pipeline engineers have taken the opportunity to increase gas pressures, and hence increase the efficiency and economy of transporting gases. Envitec '83 The International Trade Fair and Congress for Engineering in Environmental Protection - the ENVITEC '83 - will take place in Diisseldorf from 21st to 25th February, 1983.

Jan 1, 1981

By S. A. Allison

The Conference began with registration, followed by a well-attended cocktail party on the evening of Sunday 25th, where, in a convivial atmosphere, Dr Louw Alberts, President of Mintek, welcomed the delegates and wished them an enjoyable and informative week. The Conference was formally opened by the Minister Mineral and Energy Affairs, the Honourable Mr D. W. Steyn, at 9hOO on Monday. Sketching the history of Mintek and its predecessors, Minister Steyn described the objective and achievements of Mintek, as well as the background to mineral-processing research in South Africa and the policy of the South African government towards the development of the mineral industry.

Jan 1, 1984

By B. K. Loveday

A Colloquium on 'Control and Simulation in the Minerals Industry' was held at the Holiday Inn, Milner Park, on 20th September, 1984, in conjunction with the Electra Mining Exhibition. A total of 170 persons attended the very full morning programme, which began with an opening address by the President, The South African Institute of Mining and Metallurgy, Mr l.D. Austin. He outlined the reasons why computers were being used to an ever-increasing extent for control and simulation in the minerals industry. The computer was even used to check, among other things, the validity of the signals it was receiving by mass-balance calculations.

Jan 1, 1985

The sixth University of Stelenbosch (US)/University of Cape Town (UCT) Minerals Processing Symposium was held at the University of Cape Town on Friday, 7th August, 1987, and was sponsored by The South African Institute of Mining and Metallurgy (SAIMM). Once again the Symposium attracted a large number of delegates from the mining, metallurgical, and chemical industries. Uranium and electricity A symposium on 'Uranium and Electricity- The Complete Nuclear Fuel Cycle' will be held in Saskatoon, Canada, during 18th to 20th September, 1988. The Symposium is sponsored by the Canadian Nuclear Society. Electric steel The Institute of Metals, organizers of the 3rd European Electric Steel Congress, have announced that this important international event will take place in October 1989 at the Bournemouth International Centre.

Jan 1, 1987

By S. Maluadzi, D. Rocchi, S. Luyckx, S. S. Potgieter-Vermaak, C. Machio, J. H. Potgieter

The aim of this work was to compare the corrosion behaviour of thermal spray WC ? based coatings before and after annealing. X-ray diffraction (XRD) was used to determine the phases present in the coatings at various stages. The corrosion resistance of the coatings was measured using electrochemical and immersion corrosion tests. The results obtained from electrochemical corrosion (quantified by corrosion current density) and immersion corrosion tests showed that annealing appears to decrease the corrosion resistance of the coatings. From the XRD results it was determined that the phases that corroded preferentially were cobalt (Co), eta (Co6W6C) and W2C. Keywords: Corrosion, thermal spray, coatings, hardmetals.

Jan 1, 2006

By J. P. Hugo

Nuclear energy - its interactions with mining and metallurgy - PRESIDENTIAL ADDRESS given by J. P. Hugo Pr. Eng., B.Sc (Eng.) (Rand), Ph.D. (Sheffield) Energy is the life blood of the modern technological era in which we live and it was, I think, Benjamin Franklin who said that the manipulation of energy was the basis of all science and technology. This is perhaps an oversimplification, but there can be little doubt that our life today, and the improved standard of living we aspire to, are governed almost entirely by our ability to generate and manipulate energy. This ability has made it possible for Man - each specimen a feeble twentieth of a horsepower - to travel to the moon, to recover valuable minerals from the depths of the earth, to do arithmetic at unbelievable speed, to lessen the drudgery of manual labour. For these and virtually every aspect of our life we are dependent on energy from external sources. It is, therefore, not surprising that the per capita consumption of energy, and more particularly electricity, has become one of the most reliable criteria by which to measure the standard of living and technological advancement of a country.