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By R. C. J. Goode, W. S. Rapson, W. R. Lawrie, L. W. P. Van Der Bosch

W. R. Lawrie (Member): As all the Institute members present are aware, the Ninth Commonwealth Mining and Metallurgical Congress was held in Great Britain from 3rd to 24th May, 1969. The Congress opened in London and the first week was devoted to technical sessions. Several receptions and other forms of entertainment were held in the evenings. The Congress was attended by some 1 200 delegates, many of whom were accompanied by their wives. As can be imagined a large organisation was needed to cater for all the whims of these delegates, to arrange accommodation and to provide transport for the technical trips, for the receptions and for the sight-seeing tours. Papers presented at the technical sessions proved of great interest. It was stimulating to hear of the developments taking place in the various branches of mining and metallurgy. The discussions which developed between men from so many different countries were thought provoking, led to new friendships and most of us made valuable contacts for the future. There were 141 papers presented in the one week. They were given in four separate halls with two, three and sometimes four papers coming up for discussion in each of the three sessions per day in each hall. Among the more interesting subjects were those concerning off-shore drilling and the facilities for production of petroleum and natural gas. Beach mining at Consolidated Diamond Mines drew a large audience. Automation, mechanization and other technical developments were well described and we were brought up to date with modern techniques of mineral prospecting. There was general discussion on the future of the mineral industries together with comments on the consumption and price trends of these metals and minerals. The future of uranium, of vital interest to us in South Africa, came in for much debate. During the first week, besides attending the technical sessions and seeing some of the sights of London, we were royally entertained. There was a banquet, attended by some I 400 people, where we were welcomed by Princess Alexandra, a reception by H.M. Government in the Banqueting House, and we were entertained at the House of Lords on a terrace overlooking the bustling and rather muddy river Thames. Then there was the visit to the Glyndebourne Opera. It is only in London that at 3 o'clock of an afternoon, nearly 1 000 people all togged up in dress suits and long dresses and carrying packets of sandwiches for supper could arrive at a station to catch a train, and not even cause a stir of interest or a raised eyebrow! This is the way we travelled 60 miles to the opera from London. Surely there can be no more picturesque or romantic a setting for an opera than this large 400-year old red brick manor house nestling in the green valleys of the unspoilt Sussex countryside. It was a glorious evening and though we returned somewhat late and tired, not one of us would have missed this experience. After the first week in London there was a choice of tours of one week to London and the Home Counties, Cornwall, a Geological tour to Scotland, South Wales, and North England. These were followed by further one week tours to Yorkshire and Lancashire, Scotland, West Country and Midlands, a Geological tour of Wales, and a Mining and Geological tour to Jurassic Iron Mines. We then returned to London for the final session and closing banquet. Post-congress tours were arranged to Europe and to Ireland. It was a wonderful Congress, a great experience, we made many friends and may there be many more congresses! . L. W. P. van den Bosch (Member): Much has already been said in appreciation of the excellent organisation and arrangements made for the delegates who attended this Congress. This report is confined to a brief discussion of the personal impressions gained from the papers presented and the technical visits attended. The papers covered a wide variety of subjects ranging from highly theoretical observations to practical descriptions of operations. There were three main themes, VIZ: 1. The attention given to research and its forceful application to practical operation. 2. A steady development in mechanization and automation leading to savings in manpower. 3. Improvization, modernization and adaptation of exisitng facilities. Thoughts on these themes can best be illustrated by comments on some of the industries visited. COAL The National Coal Board (N.C.B.) has been most progressive and all of us have heard of the Bevercotes Colliery with its completely automatic mining and coal handling equipment. This was not, unfortunately, on show but there is no doubt that this is one of the greatest advances in coal mining leading towards continuous production. Coal in Britain is fighting for its life against oil, North Sea gas, imported gases and nuclear power. Output is dropping, the less efficient collieries are closing down and efficiencies are steadily rising as the following tabulation indicates: In 1931: 1 million men produced 300 million tons of coal In 1947: 0.7 million men produced 230 million tons of coal In 1968: 0.4 million men produced 160 million tons of coal

By J. H. Viljoen, A. Heyns, J. F. Morrison, C. H. Wyndham, N. B. Strydom

Discussion M. J. Martinson* (Associate Member): This is another interesting paper in the series which the Human Sciences Laboratory is publishing on the physiological cost of the more strenuous manual tasks performed underground. As a mining engineer-albeit presently an academic one -this contributor is more concerned with the practical significance of the study in the field of stope cleaning than with physiological niceties, but before discussing some of the practical issues raised by the paper perhaps the authors would care to reply to lay comment on three physiological matters. Firstly, in two places the authors make statements to the effect that the maximum oxygen intake of 'average' (sic) Bantu mine workers is 3.0 l/min. What do the authors mean by 'average'? Maximum oxygen intake in the individual is probably some function of inter alia age, physical fitness, state of health, ambient partial pressure of oxygen, diurnal and/or seasonal changes in metabolism, and possibly cumulative exposure to dust and other occupational contaminants. Since maximum oxygen intake is apparently such an important quality in manual labourers we ought to have a clear picture of its distribution in the entire labour force, and also know precisely how the individual's quantum is affected by factors such as those mentioned above. Secondly, arising out of the same statements and ignoring the reservation implicit in the previous paragraph, is it correct to say that the 'average' Bantu mine worker has a maximum intake of 3.0 l/min? In the August 1966 issue of the South African Journal of Science four of the present co-authors reported the mean maximum oxygen intake of a random sample of 338 Bantu recruits of different tribes to be 2.63 l/min with a standard deviation of 0.542 l/min, and these figures were repeated in a paper published in the November 1968 issue of this Journal. Admittedly the mean maximum oxygen intake of the six subjects used in the present study was 3.05 l/min, but since they were selected on the grounds of previous shovelling experience they can hardly be regarded as being 'average' recruits. Thirdly, it seems to me that the authors are perhaps a little uncritical in their acceptance of the '50 per cent of maximum oxygen intake' level of activity for endurance work. I am not unmindful of the evidence upon which this level is based, but I suggest that the evidence is at best tenuous and that the whole topic of fatigue and 'optimum' levels of productivity under conditions of high muscular activity and considerable psychological stress is a lot more complicated than would appear from the authors' ready acceptance of the 50 per cent level. Under present working conditions the question is largely rhetorical because it would need an army of supervisors to ensure that all members of a typical gang work at 'optimum' levels throughout the shift, but if individual performance should ever become more readily determinable the issue might become crucial to management and malayisha alike. So much for physiological matters; now a few random thoughts on some wider, practical issues raised by the paper. In the paragraph headed Material the statement is made that 'The mixture (of fine, medium-sized and bigger rocks) was considered to be representative of an average underground rock sample'. Elsewhere in the report the authors specifically draw attention to the effect of particle size on the oxygen consumption of men shovelling graded material, and intuitively one imagines that the size distribution of the material being shovelled would be highly significant in a study such as this. Presumably the authors were forced to assess size distribution subjectively because of the lack of objective data on the subject, and possibly the necessity for this assumption highlights how little we know quantitatively about any of the variables in stope cleaning systems. In this connection it may be remarked that although the present study was largely designed to show how dip and stoping width effect energy expenditure in shovelling, no data are given-nor, probably, are they available-to show how the industry's stoping tonnage is distributed in terms of these two factors. It seems to me that if the mining industry seriously hopes to improve stope productivity it must start by measuring the basic variables in existing systems. Elaborating somewhat on the previous paragraph, there also seems to be a tremendous gap between the present study-and its predecessors-and the prospect of gainfully using the information so carefully garnered by the authors. It would be reassuring to hear from the authors that their work on the physiological aspects is being integrated in some master plan for increasing productivity of manual labour. This I fear is not the case, and if productivity has changed at all in recent years I would hazard a guess that the change has been brought about by random factors rather than by systematic engineering design. The Human Sciences Laboratory has worked extensively in stopes in the past, and possibly the time has come when it should widen the ambit of its operations to include engineering-type analyses of cleaning systems, with particular emphasis on the economics of rapid cleaning by manual labour. Perhaps experiments could be conducted with stakhanovite-type gangs consisting of men selected for their high maximum oxygen intake and superior motivation; these men might be offered special incentives in the shape of extra pay

Jan 10, 1969

A wide range of drill holes and process streams are sampled for resource estimation, grade control and contractual purposes in the minerals industry. However, despite the availability of training courses, conferences and both national and international standards on correct sampling practices, it is still surprising how often little attention is given to ensuring that representative samples are collected for analysis. The reason for this is that the responsibility for sampling is often entrusted to personnel who do not appreciate the significance and importance of sampling, with cost being the main driving force rather than whether the sample is representative of the material from which it was extracted. This seriously undermines the precision and accuracy of the analyses subsequently generated and can render the analysis process a total waste of time and money and expose mining companies to serious, potential, financial losses. Company management needs to reverse this situation and ensure that sampling is given the attention it deserves to generate representative samples for analysis.

Jan 1, 2009

By L. Thomson

"The smelter at Sudbury Integrated Nickel Operations, located in Sudbury, Ontario, operates a single electric AC furnace. This furnace treats nickel sulphide concentrates produced by Glencore and third-party feeds and as such its performance is key to the company’s nickel supply chain. Currently the plant has two shutdowns per year in order to carry out significant repairs on matte tap-holes.Improved monitoring systems that enable better prediction of tap-hole wear have been a continued focus. The electric furnace is an essential piece of the smelter flow sheet requiring the need for planned tap-hole maintenance along with robust systems for management according to to this plan.The ability to meet our goal of zero harm is ensuring that safe practices are in place. Detailed procedures and cool-down practices have been implemented to ensure that required matte chemistry and temperature criteria can be met during the period leading into a shutdown for tapblock maintenance.A significant repair of the electric furnace will take place in 2015. During this rebuild, the sidewalls and matte endwall will be replaced. There is work underway to improve wall and matte end performance in an attempt to extend the time between rebuilds. This paper will review the approach taken towards this end."

Jan 1, 2014

Geological mapping makes an important contribution to orebody knowledge during the evaluation of structurally controlled gold veins. Orebody knowledge comprises an understanding of mineralization characteristics relevant to evaluation, mining, processing and environmental issues and allows project expectations to be realistically set. Structural interpretation to define continuity and mineralization controls is a key part of geological risk reduction and the reporting mineral resources using the JORC and other codes. The Dolgellau gold belt is a small British field that produced an estimated 150 000 oz from narrow quartz veins. Historical records, recent exploration and production data, published material, and accessible surface and underground exposure provide a valuable case study. Previous mapping has shown the general geometry of vein systems, but tends to accentuate gross geological continuity. Recent work has attempted to determine internal vein architecture and examine the significance of the historical views of ore shoot controls. The work resulted in the definition of vein continuity scenarios for the gold belt and evaluation expectations associated with each. This has, in turn, led to a realistic view of what can be achieved from an evaluation and project development perspective.

Jan 1, 2009

By N. F. Mashinini

Optimization of current control systems, proper maintenance and efficient training of personnel are recommendations made to control the amount of dust that underground employees are exposed to on a daily basis in the coal mining industry. This dissertation forms as part of Sasol Mining?s commitment to protect the health and safety of their employees by suppressing and controlling dust at their mines. This study aims to understand the relationship among mining processes, exposure to dust and dust suppression control measures. The research phase of the project was done at the Sasol Mining Secunda complex where underground visits were undertaken to investigate current control systems and also new systems that are being implemented by Sasol Mining. This work was important because it helped determine the sources of dust underground and also to identify the shortcomings of current control systems and to test the efficiencies of the new systems implemented at Sasol Mining. The most important result of the research work was the identification of which underground operators were exposed the most to dust as this assisted in designing a dust suppression system for the areas where these operators worked. The main conclusions of this study are that the current control systems are sufficient for controlling dust and ensuring dust compliance if they are used efficiently and maintained properly.

Jan 1, 2008

By Axel Schulze

HUGO PETERSEN has developed from the traditional firm of the same name that was established in 1906 in Berlin and is an engineering company specialising in general plant engineering now based in Wiesbaden. HUGO PETERSEN has many years wide-ranging experience in process plant engineering, primarily in the field of Sulphuric Acid Processes and Gas Cleaning. Together with its main shareholder, Chemieanlagenbau Chemnitz GmbH (CAC), a company with over 40 years experience in the international plant engineering business, HUGO PETERSEN implements turnkey new plants from initial consultancy right through to commissioning. In addition, HUGO PETERSEN can offer its clients improvements and revamps of existing plant systems. Initial consulting, planning and implementation take place within the context of a lean company organisation with experienced engineers and specialists. In all respects, many years of experience guarantee expertise over a wide range of possible applications For clients from the chemicals and metallurgical industries, as well as those in metals processing, HUGO PETERSEN GmbH?s breadth of experience means not just an efficient introduction to new methods and processes, but also their full implementation. In addition, along with design and construction for individual components, the company?s range of services also covers supply of complete plants, as well as modernisation projects and revamps in line with local conditions and existing quality requirements With own technologies and patents in the field of gas cleaning and sulphuric acid, supplemented by licences and cooperation projects, HUGO PETERSEN ensures expertise over a wide range of applications. With specialists and expert knowledge in these fields of application, HUGO PETERSEN is your partner of choice, supporting you and bringing your acid, and project to a successful conclusion.

Jan 1, 2009

Primary roof support represents the first line of defence against rockrelated falls of ground in underground mines, and improper utilization or misunderstanding of the applicability and behaviour of primary support can be costly from a safety standpoint. This is a major concern for underground mines, as roof support is the single most costly expense from a mining operational perspective. This is further backed by the evidence that, in the USA, hundreds of injuries and fatalities still occur each year because of rib, roof, and massive roof falls. Additionally, the fully-grouted passive rebar, fully-grouted tension rebar, and resin-assisted mechanical anchor bolts, which constitute a large portion (89%) of the 68 million bolts installed each year in underground mines in the USA can vary in cost quite dramatically. To mitigate this concern a study was conducted in 2010 by the National Institute of Occupational Safety and Health, in conjunction with Southern Illinois University of Carbondale, to assess the performance of primary roofbolts in underground coal mines for improved safety and cost. This was accomplished using underground roofbolt monitoring solutions, field data, and numerical modelling to better understand the quasi-static behaviour of underground coal mine roofs and the response behaviour of the bolts. In particular, over 170 instrumented extensometers, closure meters, shear meters, fully-grouted passive rebar, fully-grouted tension rebar, and resin-assisted mechanical roofbolts were installed at three coal mines across the USA. Of these three mines, two used the room and pillar extraction method and the other used the longwall extraction method. There was no evidence to indicate a difference in performance of the active primary roofbolts compared with the passive primary roofbolts. Additionally, in the initial loading phase, the active bolts showed no difference in loading, indicating that tension bleed-off is of more of a concern than originally thought. Lastly, for the initial computer modelling studies, challenges still remain in obtaining a good match to the in situ bolt measurements and replicating the discontinuous roof rock and in situ bolt behaviour over time.

Jan 1, 2014

By Kevin Peacocke

The future of Gravity ? Primary mineral recovery ? Enhancement of existing process efficiency ? Pre-Concentration ? Alternative? or ?New? production

Jan 1, 2006

By A. Yamik

This research study includes studies carried out on the recovery of unburned carbon in the ashes of Tuncbilek Thermal Power Plant. Bottom ashes have been identified by X-ray diffraction and X-ray fluorescence. These samples are potentially of class F type and have significant amounts of unburned coal. According to the ash amount that units in the thermal power plant produce, and the analyses of the samples mixed, which used certain amounts in flotation tests, it was found that the bottom ash includes 91.47% ash in dry form and 8.53% combustible matter, and the lower calorific value is 491 kcal/kg. Optimum flotation conditions to get the unburned carbon were subsequently determined by examination of the optimum flotation grain size, pulp density, collector type and amount, depressant type and amount, frother type and amount, agitation speed, and froth-taking time. While the lower calorific value of the thermal power plant bottom ashes of the 3rd , 4th and 5th units and the mixed bottom ash sample was, respectively, 959, 469, 279 and 491 kcal/kg in dry form, it increased to 2490, 1312, 786 and 1348 kcal/kg in the product obtained as a result of flotation in optimum conditions. Key words: ash, conventional flotation, unburned carbon

Jan 1, 2008

By T. Orupold

This paper covers the commercial development of gravity separation of fine particles using a Lamella High Shear Rate REFLUX? Classifier (REFLUX? Classifier), focusing primarily on coal applications. The REFLUX? Classifier is a fluidized bed device that incorporates a system of closely spaced parallel inclined channels located above the fluidized bed. These channels make it possible to achieve a significant suppression of the effects of particle size, resulting in a highly effective separation on the basis of density. The improved gravity separation performance is shown to be remarkably high, with a significant reduction in the variation of separation density with particle size, and a significant reduction in the change in Ecart probable error (Ep) with size. The first full commercial-sized units of the REFLUX? Classifier were field-tested in late 2009 in coal applications. More recently, the technology has been applied in fine particle separation in minerals applications and there are a number of full-sized units operating in chrome applications in South Africa. Initially, pilot-scaled units (typically the RC?300) were trialled in iron ore, mineral sands, and manganese plants amongst other minerals, typically after other technologies failed to achieve the desired results. Currently a number of laboratories globally are carrying out more testing in minerals applications. More than 50 RC? units are now operating in coal and minerals applications. This paper introduces the REFLUX? Classifier technology, identifies commercial applications, and gives some commercial results.

Jan 1, 2014

By J. van Zyl Visser

The advancement in Information Technology has resulted in a change in workflow practice in our Mineral Resource Management (MRM) offices on the mines and at our corporate office. This paper discusses the AngloGold approach in defining an IT strategy for MRM, a brief overview of systems usage and benefits. AngloGold has gone through a transformation phase and has positioned itself as a world-class, low cost producer. To support this objective, an initiative has been launched to provide the MRM division with an integrated MRM technical suite of systems with support of a Management Information System. Technical systems for a tabular orebody are not freely available and hence it took AngloGold almost seven years and a significant amount of capital to develop an integrated suite of technical systems. AngloGold MRM IT adopted the typical Zachman framework (value chain) approach in the analysis process and formulated the final deliverable in terms of AngloGold’s strategy. Major benefits have been realized through the ability to change planning scenarios in a short period of time and hence be able to increase reserves and NPV. The development of MRIS, which will become the flagship in AngloGold’s portfolio of systems is in phase two and this system will allow AngloGold to publish Resources and Reserves as per SAMREC and the JORC Code at will. The availability of information at all levels of the operations has made making decisions easier and hence some specialized reports such as the Basic Mining Equation were developed from the Corporate Data warehouse and from the MRM reporting database. Decision Support Systems(DSS) such as Business Objects and Oracle Express are now being used to assist in the process. The decision to use Business Objects to replace SAS reporting as the core reporting tool has resulted in the empowerment of the user and major cost saving as far as the use of consultants to set up standard reports.

Jan 1, 2003

By H. Moslemi

Metal sulphides are usually semiconductor and their electrical conductivity is low; therefore they are sources of electrons and promote electrochemical reactions. This phenomenon is of significant importance in sulphide flotation. The formation of a hydrophobic surface on the sulphide minerals is the result of various electrochemical reactions. Potential difference in the mineral-liquid interface plays an important role in the kinetics of the reactions, and consequently, on the flotation behaviour of sulphides. The value of the potential difference is influenced by different oxidation-reduction reactions at the interface area, and is measured by a two-electrode system in which an electrode is applied as reference electrode. In this study, we attempted to measure open-circuit potentials of pyrite, pyrrhotite, and steel electrodes with respect to the reference electrode. To verify the results, two reference electrodes, saturated calomel and gold, were used. Time-potential relations with respect to both reference electrodes show that the potential of both pyrite and pyrrhotite increases with time; however, this trend decreases for steel except when at pH 12. The results show a potential drop by an increase in pH value, except for steel, for which the opposite holds. This paper discusses galvanic interactions between minerals and grinding media in the grinding circuits, as well as among other minerals in the flotation processes.

Jan 1, 2012

Good blasting practices based on the careful application of explosive energy lead to significantly safer mining operations. Case studies demonstrate how the selection of the correct charge mass, explosive type and round design are vital for extracting the exact amount of rock required and preventing spurious damage to the remaining rock mass. In other cases the explosives are applied to precondition the rock mass, design rockburst resistant support, prevent damage to important excavations and reduce the exposure of miners to unsafe conditions. The Hybrid Stress Blasting Model is used to understand the explosive rock interaction and to illustrate and contrast good and bad blasting practices. In all cases, good supervision is required to continue safe mining according to the design. Keywords Blasting, safety, production, preconditioning, explosives, numerical modelling, drop raising, vibrations, and presplitting.

Jan 1, 2011

By S. A. Ziebold

There is often a need to increase capacity through existing mist eliminator installations without significant tower modifications. Often there is not enough extra space outside existing vessels unless more expensive changes can be justified. Also, plant downtime must be considered. The challenge in retrofitting is to overcome velocity limitations inherent in the design while at the same time extend performance capability. The solution most often is to create new ways to add extra filter area while remaining constrained to the existing space. This strategy, however, can dangerously backfire if basic design principles are not followed. Mist eliminator design is a complex integration of many conflicting performance parameters. Often the objective is to increase scrubbing capacity while maximizing collection efficiency and service life and minimizing operating pressure drop (energy cost), particle regeneration (re-entrainment) and overall maintenance costs. Results of plant retrofitting using mesh pads, impaction fibre beds and diffusion fibre beds are presented based on actual plant projects. Often the retrofit project can be more effective by increasing the scope and combining other new plant equipment with the upgrade such as new tower components. In some cases, the type of mist eliminators can be upgraded from impaction type (velocity dependent) to Brownian diffusion type (velocity independent) if additional downstream protection or reduced emissions are desirable, especially at turndown rates. Trade-offs between different fibre bed types and styles are discussed as they relate to performance and maintenance.

Jan 1, 2007

By J. Loubser

The concept of caring is in most cases confused with material needs and not psychological needs. By giving employees a job, most managers think that employees should be grateful and return the favour by being loyal, productive and working safely. Other managers hold the view that employees can be lucky to have a job. To show and demonstrate that management are caring for the safety of the workforce requires involvement, dedication and commitment. Obtaining the trust and respect of the workforce should be the main thrust of any organization because within trust and respect lie the secret of optimal safety performance. In the last 70 years, all the fatalities and serious injuries that occurred in the mining industry can be traced back to one thing, non-caring. The same safety non-compliances are still observed, reported and planned against as 70 years ago, and strange as it may sound, the same injuries occur the same way. The question could be asked: Does the mining industry need more risk assessments? More codes of conduct? More engineering. Or does the mining industry need more caring?

Jan 1, 2010

By B. P. Watson

Uniaxial tests performed on core from instrumented sites at Amandelbult 1 shaft, Impala 10 shaft and Union Section Spud shaft showed a nonlinear elastic relationship between applied load and induced deformation. This nonlinear behaviour does not appear to be dependent on borehole orientation but in the case of the Amandelbult and Union sites appears to have been influenced by the stress condition of the rock mass at the time of drilling. Cores drilled at these two sites under destressed conditions, such as over a stope, showed a linear elastic response to the applied load whereas most of the cores drilled under relatively high radial stresses were nonlinear. The Impala 10 shaft tests, however, all showed strong nonlinear behaviour irrespective of the stress condition of the rock mass at the time of drilling, although high stress conditions may have influenced the severity of the nonlinearity. A comparison between underground stress change measurements and an elastic model indicated that the rock mass became nonlinear when the virgin stress condition was relaxed to about 10 MPa. The cores for laboratory testing were retrieved from vertical boreholes drilled up from the centre of a stope and from horizontal boreholes drilled over pillars and stopes at about 600 m, 1 100 m and 1 400 m below surface for the three sites respectively. The k-ratios under virgin conditions were estimated from sockets, modelling and stress measurements to be 1.0, 1.3, and 0.5 for the Amandelbult, Impala and Union sites respectively. Of the three sites, therefore, Impala 10 shaft appears to have had the highest virgin stress state. Tests performed on similar rocks from shallower depths at Impala Platinum essentially showed a linear relationship between stress and strain. From the small Impala Platinum rock test database available to the project, it appears that the nonlinear elastic behaviour initiates at this mine from about 1 000 m below surface and seems to become progressively more nonlinear below this depth. In addition, the nonlinear elastic rocks are weaker, have a lower Young?s modulus and a higher Poisson?s ratio than their linear elastic equivalents. Interestingly the tangential Poisson?s ratios of the nonlinear elastic materials are often greater than 0.5 at 50% of the failure stress, suggesting an early failure initiation. The paper describes the microscope and modelling work done to determine the causes of the nonlinear behaviour and discusses some implications of the behaviour for deep-level mining.

Jan 1, 2009

By M. Viljoen

South Africa has produced more than a third of the total gold mined throughout history and remains a major although, until recently, no longer the largest producer of gold. South African gold production peaked in 1970 with an output of 1 000 t, a major component of the western world?s gold production, with the development of the country?s economy having been based largely on this mineral wealth. The costs and difficulties of increasingly deep-level mining, coupled with increasing labour costs and the low gold price until relatively recently, have seen production fall steadily since then, with the closure of many mines including those of the Central Rand Goldfield in the mid seventies. Thus in 1998, only 464 t were produced, with 342 tons being produced in 2004. In 2006, 275 tons of gold were produced and after more than 100 years was the last year as the world?s largest gold producer. In 2008 gold production was 221 tons, making South Africa the third largest gold producer after China (292 t) and the USA (234 t). Gold production would have been lower if it had not been for massive tailings dam retreatment operations that started in the late seventies, including in the Central Rand Goldfield. Mining of a remaining deep and lower grade shallow resources has now also become a major focus and has recently lead to a rebirth of reef mining on the Central Rand Goldfield.

Jan 1, 2009

By W. J. Kempson

As a result of the rising electrical energy costs in South Africa, a method was sought to reduce the overall electrical consumption of typical shaft systems. A typical shaft configuration was analysed and the primary energy consumers were identified. The ventilation fans for this system were found to consume 15% of the total energy of the shaft system. It was calculated that more than 50% of this energy is consumed by the shaft itself, more specifically, by the pressure losses that occur in the shaft as the ventilation air passes through it. In order to ensure that the theory being used for the evaluation of these shaft systems is accurate, a total of five shafts were instrumented and the actual pressure losses over the shafts plotted against time. These shafts were then analysed from a theoretical perspective. Finally, in order to ensure a thorough understanding of the behaviour of the ventilation air in shaft systems, the systems were simulated using computational fluid dynamics (CFD) techniques. There were significant discrepancies between the theoretical analysis and the CFD simulation during the initial comparisons. This discrepancy lessened as the complexity of the CFD models increased, until when the complete shaft was modelled using the full bunton sets, the pipes, and the flanges, the difference between the theoretical evaluation and the CFD simulation was small. This result demonstrates that the theory is insufficient and that the interrelated effect of the buntons and fittings has not been fully appreciated by current theory. The final phase of the work presented here was to evaluate the costeffectiveness of using different bunton shapes and shaft configurations. It is shown that the increase in the pressure losses and therefore the direct operating costs of the shaft can vary by as much as 80%, depending on the bunton configuration chosen. The placement of the piping in the shaft can increase the pressure losses, and therefore the direct operating costs of the shaft, by as much as 12%, depending on the placement of the piping in the shaft; this effect includes the use of flanges. The use of fairings on a large cage can reduce the resistance that the cage offers to the ventilation flow by as much as 30%. This, however, does not translate into a direct saving because as the cage moves through the shaft, the overall effect is transitory. These savings can be significant when the items highlighted in this work are applied correctly. Keywords shaft design, ventilation, energy consumption, modelling, CFD.

Dec 1, 2013

By M. Yavuz

Determining the most convenient plant location is one of the most commonly encountered problems in engineering applications. This paper presents a fuzzy multiple attribute decision making (FMADM) model which is developed for the selection of the optimum plant location for natural stone factories in the mining industry. The criteria affecting the decision making process in natural stone industry were determined to solve the plant location problem in the FMADM model. To determine the optimum plant location for a new natural stone factory, which is planned to be established by a mining firm located in the Eskisehir region of Turkey, an analysis was carried out by incorporating the method and the analytic hierarchy process (AHP) method. The analysis shows that the Yager?s method can easily be applied to the selection of plant location in the natural stone and mining industry when the difficulties encountered in the application process of the AHP method is taken into account. Keywords: Natural stone, plant location, decision making, Yager?s method, analytic hierarchy process (AHP).

Jan 1, 2008