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By W. Wittke, D. Schröder, H. Polczyk

ABSTRACT: The Urft dam, the Diemel dam and the Eder dam are three old masonry damslocated in Germany. The paper describes the rehabilitation measures and the correspondingstability analyses carried out to adjust the dams to today's standards. Remedial works such as theexcavation of inspection galleries, the installation of a grout curtain with a downstream drainagescreen as well as the installation of pre-stressed permanent tendons were carried out. In all threecases the stability of the upgraded dam could be proven on the basis of finite element analyses. ZUSAMMENFASSUNG: Die Urft-, Diemel- und Edertalsperre sind drei alte deutscheSchwergewichtsmauern aus Bruchsteinmauerwerk. Im Beitrag werden Instandsetzungsmaß-nahmen und Standsicherheitsnachweise beschrieben, die erforderlich waren, um die Staumauernan den heutigen Stand der Technik anzupassen. Hierzu wurden Kontrollgänge aufgefahren,Dichtungsschleier mit luftseitiger Dränage sowie vorgespannte Daueranker hergestellt. In allendrei Fällen konnte unter Berücksichtigung der Instandsetzungsmaßnahmen die Standsicherheit derMauer auf der Grundlage von Berechnungen nach der Methode der finiten Elemente nachgewiesenwerden. RÉSUMÉ: Les barrages de Urft, Diemel et Eder sont trois barrages-poids vieux allemandsconstruit de maçonnerie de moellon. Dans cet article, opérations de remise en état et preuves destabilité sont décrits, qui étaient nécessaires pour adapter les barrages à l'état de la techniqueactuelle. À cet effet, des galeries de contrôle étaient creusés, voiles d'étanchéité avec des drains àla face aval et tirants précontraints permanents étaient fabriqués. Dans tous les trois cas, tenantcompte des opérations de remise en état, la stabilité de la barrage pouvait être prouvée à partir decalculs selon la méthode des éléments finis.

Jan 1, 2003

By Jack Levin

Dr Laurence AlIison Bushel, a former President of the Chemical, Metallurgical and Mining Society of South Africa, now The South African Institute of Mining and Metallurgy, was born in Queenstown on 20th June, 1910, and died in Johannesburg on 4th November, 1991. There were three distinct periods in the career of Laurie Bushel, each enlivened by some special interests or achievements.

Jan 1, 1991

By R. o. Cretier, L. A. Cisternas, A. López-Valdivieso, F. Valdes, E. Gálvez, G. Gahona

The size of the particle plays an important role in the flotation of minerals. Comminution allows the release of valuable species and their subsequent recovery. Then, the degree of concentration and recovery will depend on the size of the particle. In this work, we investigated the flotation of coarse particles (-850 +150 μm) of copper ores when using the fluidized-bed separator (HydroFloat® cell) and compared it with the process of conventional flotation with medium size particle (-150 μm) (Metso cell) using seawater. The collector concentration was the main variable studied in terms of copper recovery. The results show that the flotation of coarse particles is feasible using seawater without frother

Jan 1, 2020

By B. J. Kloppers, J. V. Z. Visser, C. J. Horn

"The long-term plan (LTP) in a mineral resource company is defined by the quality of the mineral resource and represents the result of a series of trade-offs to fulfil internal organizational as well as external business and legislative requirements, ensuring ultimate delivery on the defined organizational strategy.The LTP should as a whole align to a coherent and well-defined organizational strategy, working towards a clearly defined objective while still allowing a tactical response to short-term requirements of the organization. The ability to respond tactically to changes in environment, like the unprecedented five-month strike in 2014 on the platinum belt following the 2012 Marikana incident, is a measure of the flexibility of the plan given the agreed strategy.This paper describes the Lonmin process of linking company strategy with long-term planning, tactical planning, and the execution of the plan through an annual planning cycle to maximize organizational flexibility. This flexibility enables mining companies to respond to the many internal and external forces that impact on both strategy formulation and delivery of results that meet shareholder expectations."

Jan 1, 2015

By Glen Mc Gavigan

The roof of the Sishen cave is being mined in order to exploit 6.8Mt of high grade ore. The cavity is filled with quartzite backfill in order to support the roof in the event of collapse. The cave dips at approximately 37o, is 260m along dip and 70m along strike and has a total volume of 261,391m3. GPS and optical monitoring techniques were attempted to detect subsidence but proved to be impractical. The GroundProbe Slope Stability Radar (SSR) uses differential interferometry to measure sub millimetre movement in a rock face. The SSR was applied in a non production situation and detected subsidences of 38mm/day before visual signs of instability were detected. The rate of deformation detected was slowing as a result of the roof coming to rest on underlying backfill. Monitoring during production drilling detected a sudden subsidence of 18.6mm/hour which resulted in the evacuation of personnel from the area. Further inspection of data showed that the rate of deformation was slowing and production was allowed to continue without further incident. The SSR has helped dispel the fears of workers and has proven that subsidence can be accurately measured and delineated with the SSR.

Jan 1, 2006

By Braam Blom

PK2 Ventilation shaft is part of Paardekraal No 2 twin shaft system that is being developed to replace depleting Merensky reef production at Paardekraal shaft complex. The sinking team at this shaft faced considerable challenge of improving the total sinking cycle in order to be able to deliver the fully equipped shaft on time and on schedule. The cladding support cycle was identified as the tedious and time consuming activity in the overall shaft sinking operation. Reduction in the time required for handling and setting up the support installation equipment, and the time required for subsequent installation of the necessary support has a direct impact on the overall cycle time, and consequently the overall productivity and efficiency of the sinking operation. This reduction in support cycle was achieved by making use of machine carousel. The objective of this paper is to describe the support methodology that was used during the ventilation shaft sinking and the use of the machine carousel to reduce the cladding support cycle. The machine carousel replaces the traditional use of machine kibble in conventional vertical shaft sinking and has been designed specifically for installation of sidewall support at the shaft bottom during the sinking process.

Jan 1, 2009

By Braam Blom

PK2 Ventilation shaft is part of Paardekraal No 2 twin shaft system that is being developed to replace depleting Merensky reef production at Paardekraal shaft complex. The sinking team at this shaft faced considerable challenge of improving the total sinking cycle in order to be able to deliver the fully equipped shaft on time and on schedule. The cladding support cycle was identified as the tedious and time consuming activity in the overall shaft sinking operation. Reduction in the time required for handling and setting up the support installation equipment, and the time required for subsequent installation of the necessary support has a direct impact on the overall cycle time, and consequently the overall productivity and efficiency of the sinking operation. This reduction in support cycle was achieved by making use of machine carousel. The objective of this paper is to describe the support methodology that was used during the ventilation shaft sinking and the use of the machine carousel to reduce the cladding support cycle. The machine carousel replaces the traditional use of machine kibble in conventional vertical shaft sinking and has been designed specifically for installation of sidewall support at the shaft bottom during the sinking process.

Jan 1, 2009

By L. A. Matthews

The embrittlement of the Ti-6Al-4V alloy by hydrogen dosing at elevated temperature has been investigated. Metal coupons were subjected to isothermal treatments in a partial hydrogen atmosphere in the temperature range from 650ºC?950ºC and the degree of embrittlement after treatment was determined by drop-weight impact testing. Embrittlement was found to be inversely related to reaction temperature as a result of the combined effects of greater hydrogen absorption and titanium hydride precipitation at the lower isothermal temperatures. Keywords Titanium, hydrogen embrittlement, impact energy

Jan 1, 2011

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 R. E. Wilmot

This paper is based on the experiences, over many years, on the part of numerous authors in the South African mining industry and that of the hot dip galvanizing process and its application as a corrosion protection system. The paper sets out the extensive development, financial resources and stringent operating requirements of the South African mining industry. After many years of research and operational experiences, hot dip galvanizing and when necessary, duplex systems, have been found to meet the demanding requirements of this particular industry. The paper sets out the requirements from the standpoint of corrosion criteria and is followed with a practical example; ?case history? where the corrosion protection properties of hot dip galvanizing are demonstrated. This case history traces the early investigation of the expected corrosive conditions to be encountered in a new mining operation (now 10 years on) and concludes with two follow up visits to the mine in order to examine actual performance of the corrosion protection system after ten years in service.

Jan 1, 2006

By W. Guiye, L. Chongjun, L. Huinan, Z. Yangge, H. Long

The current application of copper-molybdenum (Cu-Mo) separation inhibitors is often associated with large dosage, high toxicity, environmental pollution problems. In order to solve these problems, a light sensitive Cu-Mo separation inhibitor LS（light sensitive inhibitor，abbreviated to LS） was developed. In this paper, inhibitory performance, photodegradation rule, and acting mechanism of LS were studied. The subsequent test results showed that, compared with traditional inhibitors, LS has shown comparative advantages, with lower dosage and good inhibiting effect. A series of flotation tests with LS as inhibitor were conducted on a Cu-Mo concentrate. A locked-cycle test showed that a molybdenum concentrate containing Mo 49.88% and Cu 0.6%, with 93.23% molybdenum recovery and a copper concentrate containing Cu 29.92%, with 99.99% copper recovery can be obtained. The photodegradation performance of the reagent was investigated under 365 nm, 254 nm and sunlight irradiation. The degradation of the reagents could be completely achieved by irradiation of three wavelengths of light. However, with the different wavelength of irradiation light, the degradation rate is different, the time required to reach 50% degradation rate being 3 h (254nm), 4 h (solar light) and 6 h (365nm) respectively. The inhibition mechanism on chalcopyrite was studied. FTIR study showed that LS could be adsorbed on the surface of chalcopyrite by chemical adsorption, which could enhance the hydrophilicity of chalcopyrite. Ultraviolet adsorption tests indicated that the adsorption capacity of LS on chalcopyrite surface was greatly affected by pulp pH value, and the proper pH value was 5-9. Keywords: Copper-molybdenum separation, Inhibitor, Light-sensitive, Photodegradation, Mechanism.

Jan 1, 2020

By A. Yañez, J. Yianatos, P. Vallejos, R. Grau

This paper presents an evaluation of the effect that the mineral feed characteristics have on the metallurgical performance in an industrial flotation circuit. Variables such as mineralogy, particle size, solid content and mineral grade were evaluated using a flotation simulator, which was previously developed and validated using industrial data from different concentrators. The metallurgical performance was evaluated not only from the point of view of recovery and concentrate grade, but also by analysing less common variables such as froth carrying rate, froth and collection recovery, water recovery and others. Then, new data from the industrial flotation circuit was used to complement this analysis and evaluate the simulator predictability by comparing simulated and measured data. The results allowed for the quantification of the significant effect that mineralogy and particle size have on recovery and/or concentrate grade. Therefore, the grinding stage and flotation cells design become important factors to avoid a significant loss in metallurgical performance when feed mineral characteristics change in an industrial operation. In this context, an evaluation of cells design and arrangement should be performed to compensate the loss in recovery and concentrate grade in order to find an optimal operating condition. Keywords: Flotation circuits, mineral feed, modelling, particle size, liberation, mineralogy

Jan 1, 2020

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

Mr K.R. Beard was born on 19th December, 1958. He attended Marist Brothers College, Observatory, and Marist Brothers College, Linmeyer. He was awarded a bursary by SEIFSA (Steel and Engineering Industries Federation of South Africa) and gained the degree of B.Sc. Eng. metallurgy at the University of the Witwatersrand in 1982. He is a member of the Engineers' Society of South Africa. Mr G.A. Brown was born on 27th June, 1934, and matriculated at St John's College. He obtained the degrees of RSc. Eng. (Met.) at the University of the Witwatersrand in 1957, and M. Met. at Sheffield University in 1959. He is a member of the Institution of Mining and Metallurgy (UK) and the Society of Mining Engineers (USA). Or LA. Cramer was born in the USA and, having received a B.Sc. degree in metallurgical engineering from the Colorado School of Mines, he emigrated to South Africa in 1971. He enrolled as a graduate student at the University of Natal and successfully completed both an M.Sc. and a Ph.D. degree in chemical engineering.

Jan 1, 1989

By W. C. Joughin

Modern soil mechanics is generally considered to have begun in 1925, when Karl Terzaghi published his book Erdbaumechanik auf bodenphysikalischer Grundlage (Earthwork Mechanics based on the Physics of Soils). These theories were applied to rocks more than 20 years later and the science of rock mechanics became established. Methods of analysis and design have been introduced and applied, and have evolved over time. More recently, the rapid growth in computing power has resulted in more sophisticated analyses, and together with improved monitoring techniques, our understanding of geomechanics has grown considerably. Despite this, geotechnical failures with major consequences still do occur. This is partly due to failure to transfer and apply the knowledge that has been gained, but also there are aspects of geomechanics that are not well understood.

Sep 1, 2023

The key functions of project evaluation are to assess potential profitability and to develop an effective operational design. For mining projects, design aspects include mining methodology, ore treatment methodology and production rates. All of these characteristics impact on project economics and overall value. Resource models, which form the ultimate basis of project evaluation, typically consist of tonnes above cut-off, grade above cut-off and the spatial distribution (connectivity) of tonnes/grade above cut-off, for one or more variables. Dilution, ore loss and metallurgical recovery are all modifying factors applied to the resource model during evaluation and determination of profitability. A key issue is: how is the value determined? In addition to traditional combination of in situ tonnes/grade, the following merit serious consideration: the concentration of deleterious elements, throughput rates, mining/processing costs and - importantly - metallurgical recovery. Geometallurgy is an emerging field targeted at integrating these issues by identifying either direct measures or proxies for throughput (hardness, grindability), recovery (liberation, mineral shape/texture, etc) and concentrate quality from easily collected macro-, meso- and microscopic data. These 'geometallurgical variables' drive project costs and revenues in a fundamental way. For geometallurgical characterisation to have a real impact on business design, it must enable improved mine planning. When creating spatial estimates for such variables, it is preferable to find proxies that can be measured as close to the intact rock mass as possible. However, spatial estimation of proxies for geometallurgical properties and responses is complex and requires special consideration. Unlike grades, both proxies and absolute measures of geometallurgical variables are not necessarily linear or additive and therefore require very careful geostatistical consideration. In some cases, models must predict extreme values of geometallurgical attributes rather than averages. Incorrect characterisation of metallurgical recovery/throughput can (and has) led to misspecification of the scale of projects, and thus can be seriously value destructive. Aspects of geometallurgy have long been important in iron, bauxite, manganese and coal deposits and are increasingly on the radar for base and precious metal miners. However, as more metallurgically complex deposits are developed and mining of large-scale, low-grade deposits becomes more commonplace, the importance of characterising the metallurgical response in order to generate properly optimised projects will rapidly increase. It is possible that in many `traditional' (ie grades and tonnes) reserve models, the variables that drive the project are missing!

Jan 1, 2007

The AK6 kimberlite is situated 25 km south of the Debswana Orapa Mine in Botswana and was discovered by De Beers geologists in 1969 during the follow-up of geophysical targets in the Orapa area. The kimberlite was not extensively pursued at the time as the initial bulk sampling indicated it to be of limited size and low grade, factors largely contributed to by the basalt breccia capping. Completion of high resolution integrated geophysical techniques and drill bulk sampling to depth recovered 97 tons of kimberlite during 2003 and 2004, which led to the increased size and grade estimates. Bulk sampling by Large Diameter Drilling (LDD, 23 inch diameter) commenced in 2005; 13 holes were drilled to a cumulative depth of 3,699 m and 689 carats of diamonds were recovered. In July 2006 the De Beers Mineral Resource Classification Committee classified these Phase I LOO results at a High Inferred level with an average grade of 24 carats per hundred tonnes (cpht) at a bottom cut-off of +1 mm, and a modeled average diamond value of 150 dollars per carat. A second phase of LDO drilling was initiated in 2006, and bulk sampling by trenching commenced in 2007 in order to deliver a resource estimate at indicated level. An Indicated Resource of 11.1 million carats at an average grade of 22 cpht was declared for the deposit mining lease application lodged in 2007.

Jan 1, 2010

By A. F. Collings

The processing of heavy mineral concentrates can be enhanced by the use of power ultrasound to clean their surfaces of oxidation products and fine coatings, mainly through the large, but very localized forces, produced by cavitation. Results are presented of the application of power ultrasound to remove coatings from the surfaces of mineral sand concentrates in order to improve the sharpness of their high-tension separation and, in some cases, the quality of the low iron components such as zircon. Improvements of 10–15% in recovery and up to 20% in grade compared to unsonicated material were achieved in a single stage laboratory high-tension separation. Cavitation also ensures that a fresh, clean surface is presented to leachants during the leaching of suspended solids. At the same time, the effect of cavitation and the shearing effect of the sound wave passing over the solids ensure that the saturated boundary layer is kept to a minimum if not completely removed. This application of power ultrasound helps to speed up leaching processes as applied to the removal of excess alumino-silicate contaminants in some ilmenite. Keywords: Ultrasound, power ultrasound, heavy minerals, processing.

Jan 1, 2003

By A. F. Lee

A pick-up apparatus capable of yielding quantitative results has been described. Studies of some collector-mineral systems have been presented to illustrate the versatility of the apparatus and prove the validity of results.