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By P. M. Cole

An unprecedented expansion of the global zinc industry is currently under way. While most new projects and plant upgrades remain committed to traditional processing technologies, recent advances in zinc solvent extraction (SX) have created opportunities for new process routes for both primary and secondary materials. The first commercial plant to use zinc SX for the mainstream processing of a low-grade ore is under construction and promises to become one of the lowest cost zinc producers. Several other oxide and sulphide projects in various stages of feasibility are considering the inclusion of SX in their process flowsheet. Zinc SX has also proved advantageous in the reprocessing of secondary materials, particularly for the treatment of zinc residues and furnace dusts. This review focuses on recent installations and projects underdevelopment that feature zinc SZ as the key separation step.

Jan 1, 2002

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 P. N. Harris

The Colloquium on 'Recent Mining and Metallurgical Developments in the Orange Free State' was held at the Civic Centre in Welkom on the 4th and 5th May, 1983. The Chairman of the Orange Free StatejKlerksdorp Branch of the Institute and Acting General Manager of Unisel Gold Mining Company, Mr D. A. Parfitt, opened the proceedings, and Professor A. N. Brown gave the welcoming address. Mechanization of mining The South African Institute of Mining and Metallurgy is to hold a one-day colloquium on 'Developments in the Mechanization of Mining Operations' during September 1984. Surfac,e mining and quarrying The Second International Surface Mining and Quarrying Symposium is being organized by The Institution of Mining and Metallurgy in association with the Institute of Quarrying.

Jan 1, 1983

By K. -C. Han, S. -Y. Kim

This study was carried out in a bid to survey Ganboke gold mine in Pala, Mayo-Kebbi Province, southwestern Chad. The Ganboke mine is now being prepared for investigation and development, and the research sought to perform rock properties tests of relevant rocks through its geological survey, rock mass evaluation, and in-situ and laboratory tests and analyze the stability by the means of limit equilibrium method, thereby suggest appropriate methods to design the pit slope and individual benches in Ganboke mine. Targenting GS1-GS1' section with the depth of 180 m and GS2-GS2' section with the depth of 150 m in the survey area, we set the height of the bench at 10 m and 15 m, and the angle of bench at 60o and 70o, respectively, and then reviewed the stability for dried condition and saturated condition. The result of examination indicated that it would be appropriate to set the bench height at 10m and the bench angle at 60o in developing the mine slopes concerned. Cette étude est réalisé dans le but de faire des recherches sur Ganboke mine d'or dans Pala, Mayo-Kebbi Provence, Tchad sud-ouest. La Ganboke mine est actuellement en train de étre disposé à la investigation et le développement, et la recherche a cherché à accomplir les tests de la propriétè des roches par l'intermédiaire de la étude géologique, la évaluation de la masse rocheuse, et in-situ et les tests de laboratoire et à faire l'analyse de la stabilité au moyen de la méthode d'équilibre limite, de ce fait à proposer le methodes propres à faire le plan de la pente et les gradins individuels dans la Ganboke mine. Concernant la section de GS1-GS1' avec la profondeur de 180 m et la section de GS2-GS2' avec la profondeur de 150 m dans l'aire d'étude, nous mîmes l'hauteur du gradin à 10 m et 15 m, et l'angle du gradin à 60o and 70o, respectivement, et alors nous avon reconsidéré la stabilité pour la condition sèche et la condition saturé. Le résultat d'examen a indiqué que il pourrait être propre de mettre l'hauteur du gradin à 10m et l'angle du gradin à 60o en développant les pentes de la mine concerné. Diese Forschung wurde um das Gold Bergwerk zu überschauen in Pala, Mayo-Kebbi Provinz, der Südwesten Chad ausgeführen. Das Ganboke Bergwerk ist jetzt zur Erforschung und Entwicklung vorgebereiten worden, und die Forschung suchte zu ausführen die Prüfungen der Felseigenschaft durch geologischen Überblick, Felsmassewertbestimmung, und In-situ und Lavorversuch auf, und analysieren die Stabilität mittelst der Grenzegleichgewichtsmethode, da-durch schlug die angemes-sen Methoden zu entwerfen die Böschungen und die einzelnen Bänke im Ganboke Bergwerk vor. Für den Abschnitt GS1-GS1' mit der Tiefe von 180 m und GS2-GS2' mit der Tiefe von 150 m in der Überblickfläche, wir setzten die Bankhöhe an 10 m und 15 m, und das Bankwinkel an 60o und 70o, beziehungsweise, und dann zurückblickten die Stabilität für die getrockneten Bedingungen und die gesättigten Bedingungen. Das Ergebnis der Untersuchung anzeigte daß es würde angemessen sein zu setzen die Bqnkhöhe an 10m und das Bankwinkel an 60o in der Entwickelungen vom Bergwerk be-teiligt.

Jan 1, 2003

By M. J. U. T. Van Wijngaarden, R. J. Dippenaar, P. M. Van Den Heever

Some of the important properties of solid electrolytes that influence the performance of electrochemical oxygen probes are discussed in the first part of this paper. It is shown that accurate and reproducible measurements of oxygen in liquid steel are possible with commercial oxygen probes only if great care is exercised in the make-up of the chemical and phase composition, as well as the microstructure of the solid electrolytes used in these probes. To prove this premise, the second part of this study reports on the results of an experimental evaluation of new commercially available oxygen probe. An evaluation of the solid electrolytes used in this probe indicated that the consistency of the chemical composition, degree of stabilization, and microstructure of the electrolytes used are well controlled. The successful application of this particular oxygen probe under industrial conditions was confirmed. It was also found possible to make reliable and reproducible measurements, with acceptable uncertainty, by proper handling of the probe. Some recommendations are made as to the interpretation of the e.m.f. response curve and the use of the electronic processing unit supplied with the probe.

Jan 1, 1987

Like it or not, CPD is upon us. As from 1 January 2006, all registered engineering professionals, i.e. professional engineers, professional engineering technologists, professional certificated engineers and professional engineering technicians, were required to undertake CPD in order to keep their professional registration current. The rules regarding CPD have been gazetted under Government Gazette No. 28328, Board Notice 131 on 23 December 2005, and they also appear on the ECSA website?www.ecsa.co.za. For the convenience of our members they are reproduced in full in this issue of the SAIMM Journal.

Jan 1, 2006

By H. Krogerus, P. Niemelä, P. Oikarinen

High carbon ferrochromium is produced by carbon reduction. No replacement for carbon as reductant has yet been developed. The reduction creates a considerable amount of CO-gas. In open and semi-closed furnaces the gas is burned when leaving the burden. In closed furnaces the formed gas is sucked out by a fan, washed and utilised as fuel. The formation of carbon monoxide is presented briefly starting from thermodynamic considerations up to solid and liquid state reduction. The volume, composition and energy content of the furnace gas are discussed, focusing on the raw materials and pre-treatment processes of the furnace feed as well as on the process equipment and control. Outokumpu has been using closed and sealed furnaces and utilising the CO-gas in its Tornio Ferrochrome Works since 1968. Today in Tornio with an annual ferrochromium production of 260 000 t CO-gas production is 186 million m3, representing 68 MWh an hour. At the same time the furnace power input is 95MW. About 98 % of the CO-gas is utilised, whereof 30% in the ferrochrome production itself. This paper focuses on the characteristics and utilisation of CO-gas. CO-gas is secondary energy, which on one hand saves primary electric and fossil fuel energy in ferrochromium production and, on the other, replaces other fossil fuels at the adjacent steel works. The characteristics of the fuel, requirements for utilisation as well as health and safety aspects are discussed. Utilisation of the gas has a high impact on the total dust and gaseous emissions and on the energy optimisation at the ferrochromium and steel works.

Jan 1, 2004

By J. A. Ryder

A high proportion of damaging rockbursts are thought to be underlain by seismic events that represent shear or rupture along planes of weakness (faults, joints, dyke contacts). Such events are controlled by shear stresses and friction properties along the plane. Excess shear stress (ESS) is a measure that can be evaluated numerically and that, in principle, can be used in an assessment of the possible magnitude and relative likelihood of seismic activity. Methods for the calculation of ESS in practical mining contexts, and for the estimation of the magnitudes of possible seismic event progressions, are briefly reviewed. The effects of variables such as depth, stoping width and, in particular, virgin horizontal stresses on general shear-type seismic hazards are investigated. Attempted back-analyses of two large rockbursts are described.

Jan 1, 1988

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

The case for national research in mineral processing PRESIDENTIAL ADDRESS given by R. E. Robinson*, Ph.D., B.Sc. (Eng.) (Wits.) Some of you have only raised your eyebrows, some have made tactful comments, and a few of you have been fairly outspoken, but all of you in industry are concerned at the high level of State expenditure by bodies such as the National Institute for Metallurgy. The case for a national research organization in mineral processing is not clear-cut and in fairness I must present both cases - for and against. Competition for student members Each year the South African Institute of Mining and Metallurgy offers a prize (or prizes should the entries warrant it) of up to Rl00 for the best paper or dissertation on a topic appropriate to the interests of the Institute.

Jan 10, 1975

By Q. Li, B. Ricks

Over the last several decades mineral concentrate long distance slurry pipelines have been installed and successfully operated. Nearly all were installed via the buried construction method. Their record of depend ability and economy has been well proven. However, these systems operate in regions where seasonal soil frost penetration is shallow or non-existent. In recent years interest in long distance mineral concentrate pipelines in northern cold regions has been increasing. For cold regions one must consider seasonal temperatures and soil frost penetration in order to ensure reliable operations through the year. Herein a case study is developed where heat balance and temperatures for small and large diameter long distance slurry pipelines are compared. The study development is as follows: ?Rheological properties are analysed over range of temperatures from near freezing (4ºC; 39ºF) to relatively very warm (40ºC; 104ºF). ?Then assuming similar climatic conditions, soil properties, and pipeline length, a study is carried out for two pipeline diameters, namely: a small diameter (nominal8 inch; 219.1 mm) and a large diameter (22 inch; 558.8 mm). ?The study focus is on maintaining slurry temperature above freezing throughout the pipeline length by illustrating a decision based on burial depth versus coating the pipeline with insulation.

Jan 1, 2007

Mining is a business involving extraction of commodities of value to society from non-renewable resources. Consequently there is only one opportunity to extract ore from the ore body in order to unlock the value potential encompassed in the asset. It is therefore imperative that the maximum value is unlocked during the extraction programme, considering the relative wealth generated for shareholders and society, the sustainability of society, the environment and the operation. The bulk of the value that is unlocked is usually embedded in the initial design process. How do you measure sucess The most common measure of success is the return on investment, which is unlocked during the extraction process. This is usually only determined and locked-in during the study process. Another measure of success is the profitability that is achieved on a monthly basis. A further measure would be the enhancement the asset affords to the share price of the operation. Increasing focus on sustainable development requires that the impact on the society and environment received high priority as well. All these measures are largely encompassed in the cash flow and the discounted cash flows. This paper focuses on the dynamics of the cash flow and the most significant elements influencing return in investment. These include the mine design, production volume, sustainability, risk and valuation techniques. When do you add the most value? There are many different phases and definitions noted by different authors to demonstrate and standardise the study process for new projects. This paper is based on a process with 3 major components namely a conceptual study, a prefeasibility study and a feasibility study.

Jan 1, 2007

By H. Ogasawara

To study the preparation process of an earthquake, we should get closer to the hypocentre. In co-operation with ISS International, we had an experimental field (~200 m x~200 m) without dykes and faults in a South African deep gold mine. We have monitored more than 20,000 seismic events (M<2) with borehole tri-axial accelerometers. We used a data acquisition system with 15 kHz sampling and 120-dB dynamic range. In a remnant area at a distance of 100?200 m, an earthquake sequence associated with an M~2 event occurred. Significant changes in seismic parameters such as stress drop, b-value, energy index were observed associated with the sequence. We installed Ishii?s borehole strain meters and could monitor as large a strain change as 10-4associated with mining. However, sampling was only 4 times per hour and 12 bit A/D. A distance from the M2 sequence was ~100 m, being not close enough. Therefore, we found another field with several crosscut tunnels excavated across a fault where an M=2-3 event is expected. We installed the strain meter within several metres of the fault to monitor both shear and normal strains on the fault. The strains are continuously digitized with a 24-bit 25-Hz A/D conversion. The Earth Tide (10-8)is clearly detected. Seismicity induced by longwall mining can be compared to earthquake swarm induced by fluid intrusion to vertical dykes. We also found a decrease in energy index in the source area of M>5events a few days before the major events. Keywords: seismic monitoring, strain monitoring, seismic parameters, preparation process of an earthquake, South African gold mine.

Jan 1, 2002

By D. Pohl

The past decade has seen rapid expansion in the West African mineral exploration environment. This expansion has been largely driven by changes in ?Political climate ?Fiscal and legal regimes ?Exploration approaches ?West African geology. Major regional mapping and geochemical surveys by the UNDP, and the BRGM in the late 1970s and early 1980s laid the foundation for the rapid development of mineral exploration and resources during the past decade. An additional driving impetus was the discovery by native artisanal miners of many significant new gold occurrences at Libiri, Essakan, Bouda and Tirahori, during the great droughts of the late seventies and early eighties.

Jan 1, 1998

By D. H. Diering

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

Jan 1, 2000

By T. Könighofer

Processing of copper-cobalt orebodies in Africa?s Copper Belt has received much recent attention with various flowsheet options being developed specifically for the refining of cobalt. The upfront leach and copper refining routes are well understood whereas the refining of cobalt is more complex, requiring numerous impurity removal steps to produce high purity metal. This paper describes an investigation into one of the possible processing steps in the refining of cobalt, namely, cobalt solvent extraction. The paper emphasizes the importance of upstream impurity removal to achieve the required cobalt solvent extraction feed composition. 18% (v/v) Cyanex 272 in an aliphatic diluents is used as the organic phase. The pH profiles in the various stages are evaluated in order to obtain a raffinate containing <10mg/l cobalt and with a low magnesium content reporting to the stripping section. The pH profile is also used to minimize the impurity deportment to the cobalt electrolyte. The effect of adding a pre-neutralization stage before feeding the organic phase to the extraction circuit is investigated. Zinc build-up in the stripping stages is also looked at. It is recommended for the purpose of this study that four extraction stages at an O:A ratio of 1 with a pH profile from 4.9 to 5.7 be employed. The pH is controlled with 40g/l NaOH. A pre-neutralization stage is required, where the organic phase is contacted with 10 M NaOH. Two scrubbing stages are recommended at an O:A ratio of 40, using the cobalt electrowinning advance electrolyte as the scrub liquor. Three strip stages are to be employed at an O:A ratio of 0.67.

Jan 1, 2009

By D. Vogt

South African underground hard rock mines are typically managed using measurements made daily, weekly or even monthly of key parameters such as face advance, readiness to blast, blast success, temperature or dust levels. Safety and health can be greatly improved if a real-time measurement system can inform decision making. To enable this vision of widespread sensing, communication and decision support, CSIR has developed an open standard architecture for communication of sensor data, and a reference implementation using that standard. The standard is called AziSA, which means ?to inform? in isiZulu. AziSA provides an architecture that allows for connection of any type of sensor and that is particularly suited to wireless sensing. On the safety side, the CSIR is developing a suite of sensors specifically around the risk of rockfalls. Sensors such as an electronic replacement for the barring tool, or a thermal sensor that can detect loose rock, can already be used to identify potential hazards in the hangingwall. When these sensors are combined with location and time information in a single database, it becomes possible to build maps of risk and to extrapolate risk into unmined areas. It is also easy to confirm that routine safety procedures like barring are actually taking place. In the future, it is proposed that entry inspections will be made using remote techniques that will not place an individual miner at risk. While miners will still be required to bar or place support, they will do so with a clear idea of which portions of the hangingwall are safe, and which present risk. On the health side, if a network such as AziSA is deployed in the stope, it becomes much easier to monitor the condition of individual miners. The work strain experienced by miners can be monitored through heart-rate sensors, and their core body temperature can be monitored using various novel techniques discussed in the paper. Additional sensors can be added to quantify worker exposure to hazards such as noise or dust. Individual sensors allow for people who are at an unacceptably high risk of developing heat disorders to be treated timeously, and they also allow for team management based on objective measures. Over a longer period, position sensing and environment monitors, or personal dosimetry, provide a powerful management tool to prevent workers from being overexposed to hazards, and to confirm that management instructions are being followed. Cost-effective sensing in the stope is a major challenge, but one that can be overcome through technology like that used in AziSA. Sensing provides opportunities both to make immediate interventions when workers are exposed to unacceptable risk, and to manage the long-term exposure of workers to hazard.

Jan 1, 2010

By J. A. Tyser

The pumping of water from mines in the Central Witwatersrand by J. A. TYSER, Pr. Eng., B.Sc. (Min.) (Associate) This paper describes a system for the removal of underground water in the mines of the Central Witwatersrand, some of which are defunct. The water is pumped by a pump station on 24 level at E.R.P.M. to a surface lime plant and then to a surface treatment plant, where it is treated so that it meets the specification of the Department of Water Affairs relating to the deposition of water in public streams.

Jan 5, 1977

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

Notes on Iron Age copper-smelting technology in the Transvaal by H. M. FRIEDE, Ph.D. and R. H. STEEL (Visitors) Earlier reports on Iron Age copper metallurgy and copper-smelting techniques in the Transvaal are surveyed, and a description and tentative classification of the copper furnaces are given. The analyses of furnace slags and sherds of glazed crucibles from archaeological sites of the Transvaal and the neighbouring Orange Free State pro. vide evidence of copper smelting there in Iron Age times. . An investigation conducted by the Department of Archaeology of the University ofthe Witwatersrand provided information on the details of furnace construction and smelting processes, on the composition of the materials used and produced, and on the making and handling of tools and accessories, such as bellows and tongs, needed by Iron Age smelters. Three models (the KaondejVenda furnace, the Rooiberg crucible furnace, and the Uitkomst furnace) were constructed and operated as a demonstration of Iron Age copper smelting as it was practised in the Transvaal.

Jan 11, 1975

By M. Solomon

During the course of 2011 the nationalization of mines emerged as one of the most contentious and emotive political issues under review. Some four years after the African National Congress electoral conference held in Polokwane, which had led to a change of leadership within the country&apos;s ruling party, elements within the ruling party&apos;s youth league, which had been virulently supportive of the change in leadership, turned on the incumbent President, using the mining question as its rallying call. At issue was the expressed perception that mining has, since the country&apos;s democratization, not delivered the anticipated benefits to the population as a whole, continues to be the preserve of the capitalist element of the South African community, and is therefore in need of radical reform. Aspersions were made that transformation within the industry had failed dismally and that mining companies had not delivered against their commitments to the Mining Charter and social and labour plans. The debate became extremely vocal and heated, evoked dramatic and emotive opinions, and vigorous skirmishes on the matter were fought in the media over much of 2011 and into 2012.

Jan 1, 2013