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Now a new generation of computerized drill rigs has been launched and they are based on modern standard PC-computer technology. The rigs have been well embraced by the market and more than 100 units have left the assembly line. The new generation has taken a quantum leap forward with respect to drilling accuracy, logging capabilities, reduction of manpower in some types and serviceability compared to the previous generation of drill rigs. The Can bus technology, well proven in the automobile products, is the backbone in the new generation control system of Atlas Copco. The short-term development is now focused on establishing this new automation platform on other product lines of Atlas Copco products. The long-term objectives is to offer the mining industry Atlas Copco products with one common automation platform. Essential for Atlas Copcois to contribute to the work with the on-going Data Exchange standard between mining machines and mining computer systems (IREDES). Our belief is that an accepted standard will make mine automation programs affordable for a wider base of the mining industry, because of the possibilities to a cost effective integration of different equipment with a minimum of system integration problems and machine specific interfaces.

Sep 1, 2001

Contribution by W.D. Ortlepp? The authors are to be commended for publishing their interesting view of an aspect of deep-level mining technology that is becoming increasingly topical and vitally important. This is the second paper in the journal within four months to deal with the crucial needs of highly stressed tunnel construction, the other being the paper on the design and testing of rockburst support in the February 1994 issue. Both papers re-examine important innovative ideas that are more than a quarter of a century old, but that have not yet been implemented by the industry. It is to be hoped that they will now, taken together, serve as a new starting point for a definitive examination of what constitutes proper tunnel-support design. There can be no question that the need to develop a design approach that will solve the problems of tunnelling at depths of 4000 m or more has now become crucial. Contribution by A.M.J. Vervoort* Although the overall paper is very interesting and the future research (comparison between numerical simulations and underground measurements) will be very challenging, I would like to make some remarks regarding the set-up of the numerical model and the interpretation of the elastic results.

Jan 1, 1995

There are presently no suitable underground mine production scheduling optimisation models available for application to sublevel stope mining. Scheduling underground production for maximum return is therefore still a manual process, which generally involves scheduling production from the next available highest cash flow stope within the operational constraints of the project. In most mining operations, the scheduling problem is too large and complex to guarantee truly optimal results through manual scheduling. This paper reviews some general optimisation studies that have been proposed for underground hard rock mining. Furthermore, an example of a mixed integer programming model is presented for a small conceptual sublevel stoping operation. Comparative results of a schedule generated by a mixed integer programming (MIP) production scheduling model and a manually generated model on a nine stope example is presented. Results indicate that the potential benefits of the MIP production scheduling model for the purpose of maximising NPV are significant. Finally, a new constraint was formulated to limit multiple exposures of fill masses for use in an existing MIP production scheduling model. Testing of the formulation took place on the central stope of the nine stope example, which showed that the formulation performed its task without breaking other operational constraints.

Jan 1, 2007

By A. Chryss, L. Pullum

Shear-thickening suspensions abound throughout the hydraulic conveying industry; at least this is the perception of many engineers running plants where hydraulic conveying is commonplace. In reality, shear thickening behaviour is limited, in the main, to high concentrations of fine particles, including colloidal and biological suspensions, at moderate to high shear rates. In the authors? experience most cases of shear-thickening behaviour have been either simple ?coarse? particle interactions, poor instrumentation techniques, or both. In some cases these were obviously heterogeneous flows, while in others flows that were homogenous, or were thought to be homogenous. Examples, which illustrate this erroneous perception are given. However, the trend towards pastes and complex suspensions that use high concentration carrier fluids means that the underlying slurries for many of these flows may now be truly shear-thickening. Unfortunately, suspensions that might exhibit shear thickening also invariably exhibit slip, or wall-particle depletion. These separate phenomena are difficult to resolve experimentally and many observations of apparent shear-thickening behaviour are in fact obscured or convoluted by slip effects. A method is presented whereby the true flow properties of these high concentration suspensions, and hence accurate prediction of pipeline flows, can be made using a parallel plate rheometer.

Jan 1, 2007

By S. G. Mgenge, J. D. Steenkamp

Tronox Namakwa Sands operates two ilmenite smelters for the production of high-titania slag and low-manganese pig iron. Slag or metal is tapped from one of two product-specific, bi-level tap-holes. In this paper the refractory design specific to the tap-hole refractory layout is described, as well as practices for slag and metal tapping and refractory maintenance. Further developments planned are briefly described.

Jan 1, 2014

By C. O. Esterhuysen, J. P. Deetlefs, C. A. Wessels

The productivity indices of the Republic of South Africa compare poorly with those of its competitors in the rest of the world. The theory of productivity is relatively simple, and various models are available to demonstrate this. The problem is how to apply the theory in practice and to convert it into a practical management system that will guarantee results. The secret lies in a management approach that aims at a continuous improvement in achievement and that involves the entire work force down to the lowest level in the process. Good management systems ensuring the necessary attention to, among others, management by objectives, finance, personnel, maintenance, planning, and control are a prerequisite for continued improvement and staff involvement. The net result of such an approach is described by the term performance management, which encompasses the total integration of al a company's management systems.

Jan 1, 1989

By F. Riedel

In May 2009 a test work programme was carried out at the sorting laboratory of CommodasUltrasort in Germany which was aimed at establishing the efficiency of X- ray transmission sorting for the recovery of unliberated diamonds in a size range of +8mm. A PRO Tertiary XRT belt sorter with a working width of 600mm and a belt speed of -3mJs was used for the test work. Dual energy X-ray transmission sorting is a type of sensor-based sorting which uses an X-ray scanning system, The attenuation of the transmitting X-rays is measured at two different energy levels, Thereby it is possible to eliminate the effect of the particle thickness on the measurement result. The effective measurement results in a classification by elemental order based on the periodic table.

Jan 1, 2010

By D. Rankin, H. J. Stucke, W. K. B. Loftus

Discussion: H. J. Wright (Member): The authors are to be congratulated on presenting such a comprehensive and lucid account of bringing a large diamond mine into efficient production from the grass roots. When one considers the vast amount of planning and hard work that had to be put into the project the authors have done a praiseworthy job in condensing the story, so as to present all the important technical aspects, the logic behind the major decisions and the future thinking on the operations, in a concise and readable form. This was the first experience of De Beers personnel in starting a large diamond mine as an opencast project and nor do they employ a large planning staff, most of the planning being carried out by the executive staff themselves. It is operating most efficiently on a large tonnage and it is neatly and very well laid out. In fact, with its model townships, both for European and Coloured employees, tarred roads, recreation club and its grass golf course, it is like an oasis in the arid climate of the North-Western Cape. The key operation of opencast mining is, of course, the planning of the geometry of the pit. This has been adequately dealt with by the authors. It is of interest to consider some of the consequences arising from complete lack of open pit planning, based on actual operating mines. I refer of course to the present, four producing mines in Kimberley. The Kimberlite pipes were all discovered in a short span of time from the year 1870, onwards. They soon became a hive of activity with diggers industriously working their claims at varying rates. The country rock comprises from the surface downwards, some 90 ft of decomposed dolerite followed by approximately 260 ft of soft Karroo shales, which in turn is underlain by a hard competent Ventersdorp lava, known locally as melaphyre. The average water table was just below the dolerite at a depth of approximately 90 to 100 ft. Only the blue ground was mined leaving the waste rock sides almost vertical, and as the depth increased beyond 100 ft, large falls of sidewall started to take place. The shale was unstable and the falls covered

Jan 3, 1969

By J. A. L. Napier

Computer programs which rely on the assumption of linear, elastic rockmass behaviour have been used routinely for many years in the South African mining industry to determine the stresses arising in the vicinity of mining excavations. A description is given of the theoretical background and novel solution techniques used in the recently developed MINSIM-D boundary element program. Features of the program include the ability to analyse multiple interacting reef planes at arbitrary orientation to one another, slippage on fault planes and the effects of backfill placement in mined areas. Incremental mining sequences can be modelled, and digitizer and front-end routines have been written to assist in the capture of mining outlines and general problem specifications. A brief indication is given of design problems for which MINSIM-D is appropriate, as well as some future extensions of the system.

Jan 1, 1987

By B. Geelhoed

Gy's formula for the variance of the fundamental sampling error (FSE) is based on a model that assumes independent selections of particles. A generalization of this model, which can theoretically lead to more realistic representation of actual sampling processes, was, for the first time, experimentally verified by repeated sampling from a well-mixed batch consisting of particles of zirconium silicate of two different sizes. The predictions for the sampling variance made in Gy?s theory and in the more general model were compared with the experimentally observed sampling variance. During the experiment performed here, the variance prediction made in the theory of Gy ranges from 0.96 × 10?7(g2/g2) to 0.95 × 10?7(g2/g2), which is approximately a factor 60 lower than the experimentally observed variance (5.76 × 10?6(g2/g2)). The difference between the Gy prediction and the experimentally observed variance cannot be fully explained by the uncertainty in the experimentally obtained variance due to the finite number of degrees of freedom. Therefore, the difference is likely to be a significant effect. This shows that, under the experimental conditions, Gy?s formula for the variance of the FSE probably undervalues the sampling variance, unless an empirical correction factor for grouping and segregation is applied in the theory of Gy. The new theory resulted in a variance prediction of 6.00 × 10?6(g2/g2), which is much closer to the observed variance than the Gy prediction. This indicates that the generalization of Gy?s theory offers an outlook for providing a better variance prediction than the Gy predictor in the case of dependencies between particle selections. The results are discussed. Keywords: sampling, variance, parameter for the dependent selection of particles, Gy, experiment.

Jan 1, 2009

By C. Musingwini

The South African platinum mining industry is using a number of different mining methods, including variations of the same method, to extract the narrow reef tabular platinum deposits of the Bushveld Complex. These mining methods fall into three broad categories, namely conventional, mechanised and hybrid mining. A question sometimes asked in the industry is whether mechanized mining methods are more efficient than conventional mining methods. An objective answer requires the methods to be evaluated against multiple criteria simultaneously, whereby each criterion has a relative degree of importance in the overall decision. The most efficient method is the one that scores highest on each criterion. However, some of the criteria can be conflicting, such as by increasing dilution the shaft head grade decreases. The analytic hierarchy process (AHP) methodology was selected for the study because it is used to solve problems of this nature. A survey was carried out to determine the relative importance of each efficiency criterion by drawing on the knowledge and experience of mine technical services and project management practitioners in the industry. Efficiency data for four different mining methods drawn from the Egerton (2004) study were used as a case study. The conventional mining method ranked as the most efficient mining method from the four methods considered. The exercise indicates potential for the AHP to be used in the South African platinum mining industry as a tool for selecting optimal layout designs, conduct regular evaluation of the performance of production shafts, or objectively evaluate line managers for promotion. The work described in this paper is part of the methodology used in a current PhD research study at the University of the Witwatersrand. Keywords: Analytic hierarchy process (AHP); multiple criteria decision analysis (MCDA); decision-making; conventional mining, hybrid mining, mechanized mining.

Jan 1, 2008

By S. A. Abdel Sabour

Strategic decisions in the mining industry are made under multiple technical and market uncertainties. Therefore, to reach the best possible decision, based on information available, it is necessary to integrate uncertainty about the input variables and model financial risk of the project?s merit measures. However, this provides few useful insights to decision-makers unless accompanied by modelling management responses to uncertainty resolutions. It is widely acknowledged that conventional decision-support methods based on static, no-change, discounted cash flow (DCF) techniques such as net present value (NPV) and internal rate of return (IRR) tend to provide inaccurate value estimates. This could mislead the strategic decision-making process and result in significant value losses. This paper aims to model financial risk related to uncertainty about market variables such as metal prices and foreign exchange rates. Other sources of risk that are related, for example, to geology and production costs are not considered in this work. The article outlines a flexible financial model that integrates uncertainty about market variables and management flexibility to react to uncertainty resolutions into mine project valuation using a real-options valuation technique based on Monte Carlo simulation. Significance of information generated from this simulation-based flexible valuation model to the strategic decision-making process is tested using an illustrative case study of a Canadian mining project. The project is a typical multi-metal, open pit mine that produces copper and gold. In this case, there are three uncertain market variables, which are: copper and gold prices and US$/CAN$ exchange rate. Financial valuations are carried out using both the conventional static DCF method and a flexible real-options model. In the flexible model, management flexibility to decide whether to go ahead with the next expansion or terminate production operations is integrated. Results show how the flexible financial model can enhance the decision-making process.

Jan 1, 2009

By S. Nana, M. B. Cortie

Duplex stainless steels containing high levels of manganese and copper and lower-than-normal levels of nickel were produced and evaluated. The experimental alloys containing 3 per cent copper by mass could not be successfully hot-rolled. Alloys containing less than 2 per cent copper could be hot- and cold-rolled without difficulty. The wrought experimental alloys that contained copper were found to offer some advantages over the 2205- type duplex stainless steel in sulphuric acid at 52°C. Resistance to pitting attack was governed primarily by the chromium, molybdenum, and nitrogen contents, and one of the experimental alloys was superior to the 2205-type alloy in the ferric chloride test. It is concluded that manganese is a useful substitute for nickel in duplex alloys, but that further work is required before the present alloys, or variations of them, could be commercially viable.

Jan 1, 1993

By K. Tobór-Osadnik, M. Wyganowska, A. Manowska

"The behaviour of employees is an essential issue in the field of occupational health and safety. Safe behaviour is to a large extent determined by, apart from motivation and preventive actions, an employee’s attitude towards hazard. Thus, attention should be given to defining employees’ attitudes, and following that, to the possibility of correcting and shaping these attitudes in relation to hazard and obeying occupational health and safety regulations. The authors have focused on the analysis of employee attitudes to health and safety regulations in Polish coal mining companies, taking into consideration earlier research on the behaviour of selected employees. The paper presents the methods used to identify Z-type (passive) behaviour. Next, this behaviour is analysed to identify differences between a Z-type employee (enslaved) and other employees. To conclude, the paper presents a list of possible motivational tools that may be used to encourage occupational health and safety in Z-type employees. IntroductionThe technical state of equipment and conditions in the workplace greatly influence occupational safety. However, the deciding factor influencing the rate of accidents in the workplace is the frequency with which employees practise risky behaviour. Factors such as the social conditioning of conduct and motivation for organizing safe work conditions have been included in the notion of creating a positive culture of work safety. This notion has been approved as one of the main goals in management (Studenski, 1996).Safe behaviour is to a large extent, apart from motivation and preventive actions, determined by an employee’s attitude towards hazard. All actions undertaken in the field of occupational health and safety, including training, motivational systems, or imitation of behaviour resulting from a high culture of occupational safety in a given work environment, will not bring about the desire effects if workers have an inappropriate attitude towards occupational health and safety regulations."

Jan 1, 2017

By Mark Craddock, Johan Swanepoel

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

Jan 1, 2007

Mr Philipus Albertus von Wieligh, a former President of the Chamber of Mines and Executive Director of Johannesburg Consolidated Investment Company, died in Johannesburg on Thursday, 28th December, 1989. He is survived by his widow, a daughter, and two grandchildren. Mr Von Wieligh served the mining industry for 45 years. The P.A. von Wieligh Park in Hilshaven on the West Rand is named after him.

Jan 1, 1990

By J. B. Parry

Three types of high-strength cold-rolled steels are discussed. Two are currently being developed at Iscor: rephos phorized steel and niobium microalloyed steel. Heat treatment after cold rolling is carried out in batch annealing furnaces. A third type, dual-phase steel, which requires a continuous annealing treatment for economic production, is also described. The properties, strengthening mechanisms, and applications of these three steels are examined.

Jan 1, 1983

A back-propagation model, which is typical of the models used in the science of artificial neural networks, was applied to the prediction of gossans from the southeast area of Habei Province in China. A success rate of 100 per cent was achieved. The results show that the neural-network approach is good, and that it can be used effectively in the prediction of multi metallic deposits.

Jan 1, 1995

By G. Nino de Guzman, L. C. Woollacott

The isotherms that are usually taken to represent the force 'driving' the adsorption in carbon-in-pulp processes may change from contactor to contactor. This paper reports on an investigation into the extent to which this Isotherm shift is Influenced by the changes in oxygen and cyanide concentration that occur in operating plants. The impact of the isotherm shift on the reliability of simulation results is examined.

Jan 1, 1993

By R. Rubin, P. A. Laxen, G. S. M. Becker

An account is given of developments in the use of activated carbon for the recovery of gold from cyanide solutions. The carbon-In-pulp process employed at the Homestake Mine is described, and its various applications in South Africa and their effectiveness are discussed. Probable future work on the carbon-in-pulp process and other possible applications of carbon for the recovery of gold are outlined.

Jan 1, 1979