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By L. du Preez, J. D. Steenkamp

This paper introduces the concept of clean steel production from a pyrometallurgist’s perspective to the broader metallurgical community. A simplistic overview of the steelmaking process from iron ore to car body manufacturing is followed by an introduction to the South African steel industry and the technologies that it utilizes. The process is illustrated by an overview of the flow sheet and technologies for the production of clean steel at Saldanha Steel, South Africa.

Jan 1, 2015

By P. R. Segopolo

"The purpose of the project is to convert current shuttle car utilization on an underground coal mine to best practice by focusing on change-out points and tramming routes, which have a major influence on shuttle car away times. Time studies were an integral part of the project as these enabled the determination of shuttle car away times. An indirect proportional relationship between shuttle car away times and productivity is established. Through the time studies, it is deduced that a third shuttle car will make an insignificant contribution to production when there is only one split open. During this time, maintenance on the third car can be optimized. In order to satisfy the mine’s key performance indicator of keeping shuttle car away times less than 75 seconds, a belt extension must be scheduled after the third split is open. It is established that at any given time, a minimum of two shuttle cars should be used. When cutting on the left-hand-side of the belt road with only two shuttle cars available, the centre and left (left of the feeder breaker) shuttle cars should be used for coal hauling. When cutting on the right-hand-side, the centre and the right-hand-side cars should be used. If only one shuttle car is available, the centre car is the most efficient to use. Alternative anchoring configurations can be employed so as to enable cars (left or right, especially) to reach the opposite extremities of the panel and hence minimize cable length restrictions. Paper written on project work carried out in partial fulfilment of BSc. Eng. (MiningEngineering)"

Jan 1, 2015

By V. Bari?ic

The scheduled power cuts of early 2008 were a disturbing reminder that South Africa needs to expand its power-generating capacity. Low-grade and discard coals, of which South Africa has much, are a source of energy and amenable to combustion in circulating fluidized beds (CFBs). Foster Wheeler (FW) has a long record in developing this technology in boilers. The technology is flexible in burning a variety of fuels; low-grade, high-ash coals, good quality bituminous and anthracite coals, and biomass and waste fuels have all been used. CFB boilers are efficient, reliable and can be designed to meet tight emission standards. In recent years once-through supercritical (OTSC) CFB technology has been developed. It enables the next stage in CFB development to proceed to a medium-scale (500 MWe) utility in such projects as Lagisza, which runs at a net efficiency of nearly 44%. Scaling the technology up to 800 MWe with a net efficiency of>45% is planned to be commercial during 2009. CFB technology can reduce CO2 emissions in the repowering of coal-fired and greenfield power plants. It does so through greater efficiencies and by co-combusting coal with biomass. FW has also developed CFB technology for the gasification of biomass, as, for example, in a pressurized gasifier to produce syngas, which can be used for the production of biodiesel, thereby reducing CO2 emissions from vehicles. Carbon capture and storage (CCS) can potentially cut CO2 emissions in the generation of power from fossil fuels in the short term, provided that it gains public acceptance, that the required regulatory framework is created, and that emission-trading mechanisms or other incentives provide a solid return on the major investments required. Oxyfuel combustion is an option in CCS; Foster Wheeler is adapting its CFB combustion technology for oxy-fuel combustion to meet this challenge. It is developing Flexi-burn?, which enables a plant to be operated either with or without carbon capture. This paper describes the status of CFB technology in terms of boiler efficiency and fuel flexibility. It highlights the advantages of CFB technology for oxyfuel combustion, presents a development plan for Flexi-burn?, and discusses a pressurized gasifier for biodiesel applications.

Jan 1, 2009

By A. W. Dougall, T. M. Mmola

"SynopsisThe global resources and commodities market has become highly competitive. While southern Africa’s abundance of minerals resources is still unrivalled, it has lost considerable dominance in terms of production output. The sustainability of southern Africa’s mining industry is increasingly becoming dependent on its ability to manage the performance of its operations well. A valuable tool for monitoring and managing performance is the use of key performance areas (KPAs) – which are those areas of performance that are reflected explicitly or implicitly in the vision and strategies of an organization and reflect the critical success factors of the organization. This paper is a review of key performance areas in the southern African mining delivery environment. The KPAs discussed in this paper have been identified by comparing KPAs of the several mining houses engaged in surface mining operations in southern Africa and then extracting those KPAs that are common to most of them. Although the authors support the view that each organization should develop KPAs to specifically fit its needs, the study reveals that five KPAs – safety and health, costs, product quality, fleet management, and delivery should form a default list that covers the key areas that any organization should consider when choosing KPAs. KPIs are those subsets of KPAs that we measure in order to manage KPAs.IntroductionThe global resources and commodities market has become highly competitive. While southern Africa’s abundance of minerals resources is still unrivalled, it has lost considerable dominance in terms of production output. The sustainability of southern Africa’s mining industry is increasingly becoming dependent on its ability to manage the performance of its operations well. A valuable tool for monitoring and managing performance is the use of key performance areas (KPAs), which are ‘those areas of performance that are reflected explicitly or implicitly in the vision and strategies of the organization’ (Barker, 1997). The terms KPA and KPI (key performance indicator) are often used interchangeably – whether correctly or erroneously is debatable. KPIs are ‘quantifiable measurements, agreed to beforehand, that reflect the critical success factors of an organization’ (O’Neill, 2007). Each KPA probably has multiple KPIs associated with it."

Jan 1, 2015

By D. Nyungu

Despite observations of spalling and damage of mine excavation wall rock in the Bushveld Complex (BC) over the passage of time, there have been very few time-dependent or creep tests carried out in South Africa on rock, particularly on BC rock types. The research described in this paper deals with the investigation of stress and strain conditions influencing spalling of wall rock in BC mine excavations, and the influence of time on the tensile strength of several BC rock types. Time-dependent laboratory testing of BC rocks was carried out in indirect tension. The results show that the magnitude of the tensile strength of BC rock types is approximately 5% of their uniaxial compressive strength magnitudes. The average long-term uniaxial compressive strength of the BC rocks, interpreted from the axial stress-volumetric strain graphs, is 56% of the UCS value. The long-term tensile strength is shown to be less than 70% of the normal tensile strength. Extension strains at tensile strength failure ranged between 0.16 and 0.21 millistrain. Values corresponding with the long-term tensile strength are less than 70% of this range, namely, 0.11 to 0.15 millistrain. These results represent new knowledge, since such rock testing and analysis does not appear to have been carried out previously on BC rock types. Elastic numerical modelling was carried out to illustrate the extents of tensile stress zones and extension zones around of typical BC mine excavations. The models showed that large zones of extension strain can occur around BC excavations, and that the magnitudes of the extension strain can substantially exceed the critical values determined from the laboratory testing. The implication of this is that there are substantial zones surrounding BC mine excavations that will be prone to time-dependent spalling conditions and perhaps more significant failure.

Jan 1, 2014

By B. P. Watson

The first crush pillars on the Bushveld platinum mines were introduced at Union Section in 1978. Before the introduction of crush pillars, serious problems were experienced when stoping advanced to a point 30 m to 40 m on both sides of the centre gully. At least three to four stopes were collapsing per month. The introduction of the pillars stopped the stope collapses in the mining area where they were introduced. The residual stresses of these pillars were never measured; however, the successful elimination of the ?back-break? problem suggests that the original pillars had a residual strength of at least 8 MPa. Apart from back analyses, very little work has been done to determine the residual strength of crush pillars and only very recently have any measurements been made. The lack of knowledge in this field has resulted in pillars being designed based on experience. Concerns about stope collapses, similar to the Coalbrook disaster, have led to larger pillars being cut in more recent times. If such pillars were cut in brittle quartzites they would always fail violently but the ductile nature of the Merensky Reef generally allows large pillars to fail without bursting. Occasionally, however, one would burst in a working area. Increased incidence of bursting has been reported on some mines at deeper levels but most of these bursts occur in the back areas. Nevertheless, the incidence of bursting increases the risk of falls of ground in already dangerous areas, and the larger pillars decrease the extraction ratio. This paper describes the evaluation of stress measurements conducted in two boreholes over a crush pillar with dimensions 2.5 m x4.0 m, and a height of 1.2 m. Boussinesq equations for vertical and shear stress were used to analyse the original measurements and provide a stress profile across the pillar as well as the residual strength of the pillar. The results showed an unexpectedly high peak stress of 280 MPa at the centre of the pillar and a residual strength of 48 MPa. The reason for the high residual strength is suspected to be the result of the stiff environment under which the pillar failed and the small height of the siding on the up-dip edge of the pillar. More measurements should be conducted on several mines to establish a range of residual strengths for narrow crush pillars.

Jan 1, 2008

By Z. van Zyl

The southern African coal industry is facing the reality that coal reserves are becoming deeper and harder to mine than before. Alternative visions need to be considered to offset the impact of these challenges on productivity, cost, and profitability. One of the main challenges is to maintain current production levels under more difficult conditions, and improve productivity where conditions allow. There is a need to move from the reactive event-based management system towards the more adaptable and flexible process-based management system. This paper focuses on underground coal mining, but the principles are also applicable to other commodities and mining methods. This paper is based on research undertaken by the personnel from Mining Consultancy Services Pty Ltd (MCS) on trends in the underground coal mining sector, as well as practical experience over a period of 16 years in the field of electronic monitoring of mining machinery and productivity optimization.

Jan 1, 2015

By J. J. Stacey

Large mining companies generally follow the distributed ownership corporate model, with a board of directors responsible for decisions that affect both shareholder value and stakeholders of the company. The board is simultaneously responsible for setting the culture and values of the corporation, which drive performance and priorities. Companies listed on the Johannesburg Securities Exchange (JSE) commit to sustainable development in various ways, either by virtue of implementing the King Code of Governance 2009 (King III) and/or through their own public reporting on social and environmental matters. Many mining companies make public statements regarding their support for environmental stewardship, ethical behaviour, and fair treatment of communities. It is a local, regional, and indeed, global phenomenon that companies fail to deliver on these statements. Research was carried out through the Institute of Directors of Southern Africa in 2007, and followed up in 2012, regarding directors? understanding of sustainable development issues, the relative priorities, what is needed for ?radical change? to effect sustainable development, and what enables or constrains the latter. Pertinent findings of both surveys are presented in this paper, and it is suggested that ?on-the-ground? performance may be indicative of the nature of leadership and decisions in the topmost ranks of the company. The results indicated that environmental concerns fall consistently below social issues. Financial capital ranked most important, and while environmental issues are recognized as being of strategic concern for the long-term, they ranked as being the lowest importance of all ?Five Capitals? (Financial, Manufactured, Social, Human, and Natural). Social capital ranked second lowest, with black economic empowerment being the only high-priority social issue. There is also evidence that certain companies within the mining sector fail to recognize their absolute dependence on natural resources. Much is made in academic and popular literature of the need for a new type of leadership for the radical shift to sustainable development: at company level this implies therefore a new type of director. The research found that only 14 per cent of directors felt that board decisions are consistent with their personal values; while intentions are strong to behave ethically and serve sustainable development, actions to give effect to these intentions lag significantly. Respondents indicated that the top impediments to courageous leadership for sustainable development related to personal issues of maintaining the image of being a director, fear of appearing weak, fear of being a lone voice, and bowing to board-colleague peer pressure.

Jan 1, 2014

By L. Holappa

Ferroalloy production is an energy-intensive industrial sector with significant CO2 emissions. In this paper the current situation in ferroalloy processes is discussed from the standpoint of global environmental issues, trends and development. Progress and data of ferroalloys production are frequently compared with the steel industry, which is a closely related sector and the main user of ferroalloys. Emission factors of processes and electricity production are examined as well as possibilities and future scenarios of how to diminish CO2 emissions. As a part of this study a questionnaire was submitted to experts in the field of ferroalloys worldwide to survey opinions on the ferroalloy industry today and in the near future (2020). Eighteen questions concerning raw materials, energy, environmental aspects, by-products and economic aspects were responded to by seventeen experts, the answers were analysed and conclusions were drawn. Keywords Ferroalloys, energy, CO2 emissions, electricity, sustainability, questionnaire.

Jan 1, 2010

By D. Diering

Having agreed to perform this task, I naturally started to wonder what on earth I was going to talk about, and on reviewing the literature I was surprised at how little I knew and how much I?d forgotten about the origins of this industry. For example: ?I?d forgotten that the Chinese invented black powder at least 1 000 years ago, back in the 10th century (although some say this invention occurred 2 000years ago). ?I didn?t know that Roger Bacon was the first person in the Western World to give exact directions for the making of gunpowder in 1242 and to understand its potential. Pepper?s Playbook of Metals quotes:?...above all, he is named as the discoverer of gun-powder, a material which has brought more wonderful changes in the great family of man than the most potent elixir that could have been devised to prolong life?.

Jan 1, 2000

By A. Singh

The control of flotation plants is by no means trivial. Flotation is one of the most interactive minerals? processing operations. The interactive nature of flotation circuits results in oscillations of levels and hence of grades and recoveries. Also, poor level setpoint tracking and disturbances have negative influences on grades and recoveries. The result is an unstable plant with limited scope for optimization. An advanced controller, FloatStarTM, has been developed to provide tight control and to reduce the amount of disturbances in flotation levels. It has been shown on a number of plants that the system results in faster and better setpoint tracking, better regulatory control and faster settling times after start-ups and disturbances. The successful stabilization provided by FloatStar has made it easier to investigate the area of optimization on flotation circuits. Mintek has identified the need for a more meaningful set of setpoints or aeration rates to use as a basis for control than levels and have advocated flow control by looking after residence times. When the feed conditions change, the ideal solution would be an algorithm or strategy that finds the new optimum conditions rather than just having an unguided hunt from the previous point. A multivariable flow-optimizing algorithm, a new module in FloatStar, has been developed to calculate optimum level setpoints and/or aeration rates that will aim to optimize the residence times, mass pulls and circulating loads within a flotation circuit. Keywords: flotation, regulatory, FloatStar, start-up, disturbance, residence times, circulating loads

Jan 1, 2003

By J. A. Caldwell, G. E. Blight

The metropolitan area of the Witwatersrand has grown up around the Witwatersrand gold mines. Most of the mines have now been abandoned, but deposits of waste material remain and have been surrounded, and in some instances covered, by urban and industrial sprawl. This paper describes the development of geotechnical measures for the abatement of air and water pollution from abandoned gold-residue dams in the Witwatersrand area. The measures include the stabilization of the surfaces of the dams to prevent wind and water erosion, the terracing of slopes to minimize erosion, and the construction of catchment walls and dams. The measures were developed in terms of the set of guidelines for environmental protection adopted by the Chamber of Mines of South Africa in 1979.

Jan 1, 1983

By A. Kostin

GIS and multivariate geometric distribution have been used to predict the association of high-level intrusives with hydrothermal alteration related to iron oxide Cu-Au (IOCG) mineralizing systems. Several examples in the Russian northeast are presented in this paper. IOCG ore deposits can have enormous geological resources containing significant reserves of base, precious, and strategic metals, and hence are economically attractive targets for mineral exploration. To date, examples of this type of mineralization have not been reported from the northeastern area of Russia. The Tarinskiy ore cluster, located in Eastern Yakutia, shows brecciated altered rocks with sulphide and iron oxide cement, which is typical for IOCG mineralization of the iron oxide Cu-Au±U type. This cluster was formed near surface and is linked with the Rep- Yuruinskiy pluton. It has potential to host new world-class precious metal deposits in northeastern Russia

Jan 1, 2014

By D. Lusinga

Hydrocyclones are a common feature in almost all mining operations in the world, serving mainly as classifiers. Some of their advantages include low capital costs, low space requirements and their ability to reduce residence time in closed circuit grinding processes. Although an extensive body of literature exists for hydrocyclones, these devices are still inherently inefficient, and more research is currently being undertaken, particularly in the field of modelling. In the vast body of hydrocyclone literature published so far, there has been little or no effort devoted to analysing the effect of the cone force ratio on the performance of hydrocyclones. The cone force ratio is defined as the ratio of the spigot to the vortex finder diameter (Shah, 2005). In this study a total of 44 tests was carried out in a custom-built rig at the University of Cape Town. These tests were aimed at evaluating the effect of the cone force ratio on the performance of as mall diameter hydrocyclone. The cut size and water split were used as the criterion for evaluating the performance of the hydrocyclone. Results from the tests showed that the cut size decreased with an increase in the cone force ratio. The cut size also appeared to decrease as the calculated locus of zero vertical velocity (LZVV) shifted inwards. The water recovery to the underflow appeared to increase with an increase in the cone force ratio. The effect on the cut size of adjusting the cone force ratio was found to be higher for a coarser feed than it was for a finer feed.

Jan 1, 2009

By R. Cao

Geostatistics was initially developed in the mining sector, but has been extended to other geoscience applications, including forestry, environmental science, soil science, and petroleum science and engineering. This paper presents methods, workflows, and pitfalls in using geostatistics for hydrocarbon resource modelling and evaluation. Examples are presented of indicator variogram analysis of categorical variables, lithofacies modelling by sequential indicator simulation and hierarchical workflow, porosity modelling by kriging and stochastic simulation, collocated cokriging for integrating seismic data, and collocated cosimulation for modelling porosity and permeability relationships. These methods together form a systematic approach that can be effectively used for modelling natural resources.

Jan 1, 2014

By N. P. Mahumapelo

This paper is based on a study to determine the potential beneficiation opportunities for marble from Griekwastad in the Northern Cape Province. The marble was characterized mineralogically by X-ray diffraction. Major and trace elements were determined using inductively coupled plasma-optical emission spectroscopy. The sample was crushed, and the crushed material beneficiated by tumbling and polishing. The resulting beads were incorporated into a variety of jewellery and other decorative items. It is concluded that the beneficiation of Griekwastad marble presents a good opportunity for value addition and job creation, provided that an effective marketing strategy for the products can be developed..

Jan 1, 2014

By J. K. E. Douglas

PRESIDENTIAL ADDRESS Given by Mr J. K. E. DOUGLAS, M.Se. (Eng.) (Rand) SYNOPSIS Lime is the most widely used and the cheapest chemical alkali known to man and virtually every product we use or eat has required lime in some phase of its manufacture. Its use goes back to the earliest days of man and many ancient buildings and writings bear testimony to this. The manufacture of lime involves quarrying, crushing and screening of limestone and the burning of the sized stone in kilns of which there are several types. The earliest kilns were of very crude design and only in comparatively recent times have large capacity, automated and scientifically controlled kilns been developed. The history of the South African lime industry is largely that of the three main lime companies and their story is briefly told. No other material used in industry has a greater diversity of uses or more varied functions and lime has applications in most South African industries. The main applications are in the production of gold and uranium, iron, steel and ferrochrome, carbide, sugar and paper and for water treatment, agriculture and building. The Republic is well endowed with high quality limestone and the conclusion is drawn that many other minerals will have been exhausted before we run out of limestone with which to process them. The expansion of the lime industry has in the past kept pace with the requirements of industry and the future demand is expected to grow in parallel with the growth of these industries. Since the war this growth has been phenomenal and with our expanding populations and abundance of raw materials it should continue in the years ahead. Limiting factors are the shortage of skilled labour and the distance from export markets. Confidence is expressed that the challenges of the future will be met and that the lime industry will continue to make an important contribution to the growth and prosperity of South Africa. INTRODUCTION Lime, gentlemen, is known to all of you. Like myself, most of you have undoubtedly found it to be, on the appropriate occasion, a most pleasant flavouring for gin. But this lime, or rather its juice, was in earlier days more than just a flavouring. In the days of sail it was vital to the health of sailors as a deterrant against the scourge of all sea-going men-scurvy. It thus played a small but important role in the opening-up of trade routes around the world on which was based the original wealth of many of today's more advanced nations. I propose to address you on the subject of lime this evening, not the citrus variety I have just mentioned, but the most widely-used and cheapest alkali known to man, which, largely unsung, plays an even more vital part in modern industry than did its namesake in the development of inter-continental trade. In the time at my disposal, I propose to tell you something of the history, geology and technology of lime manufacture. Then I will briefly sketch for you the development of this industry in South Africa and indicate the role it plays in supplying the requirements of many of our important industries. Finally we will attempt to look into the future. The importance of this chemical alkali to our modern civilization is seldom fully appreciated-virtually every product we use or eat has required lime in some phase of its manufacture, either directly or indirectly. It is one of those basic materials, along with iron, coal, sulphur, salt and petroleum without which industry and, in fact, our modern way of living could not exist. Fortunately, nature has endowed the world with a plentiful supply of the limestone from which lime is derived and most countries have deposits adequate for their requirements. As a result, not only has there been little trade in lime products between countries but in the past the widespread occurrences of limestone have set a pattern of numerous small plants each serving a limited area. These plants were generally crude affairs incapable of producing a quality product. It is not surprising that, in an industry comprised of small producers with limited financial resources and in fierce competition with each other, there was little interchange of information. Technological development was therefore slow and the industry tended to be regarded as a backyard operation. Its popularity was not enhanced by the fact that lime is difficult and unpleasant to handle if proper facilities are not provided. In recent years the lime industry has undergone very radical changes to meet the more exacting requirements of today's more sophisticated consumers. Only since the war have the larger companies emerged with proper management, highly mechanized plants and a scientific approach. HISTORY Lime was one of the first chemical reagents used by man and consequently lime burning is one of the oldest of the chemical industries. The use of limestone dates back to the stone age when primitive man used limestone to build fireplaces, construct shelters and make crude tools and weapons. It is probable that lime was first discovered by him when the stone in these fireplaces disintegrated to a white powder which he could use for decorative purposes. The first recorded use of limestone was when huge blocks of limestone were used to build the pyramids of Egypt in 4,000 to 2,000 RC. It was not long after this that the beauty of marble, which is in fact a limestone, came to be appreciated and it found wide application in sculpturing and for decorative wall construction. Originally lime, mixed with sand, was used mainly as a mortar for building purposes, the earliest record of its use for chemical purposes being in 350 B.C. in a report of the wreck near Marseilles of a ship carrying a cargo of linen and lime 'for its bleaching'1. Cato mentioned the burning of lime kilns in 184 B.C. and the Romans made extensive use of both limestone and lime for highway construction. A treatise on architecture by Vitruvius who had an official position in the rebuilding of Rome under the Emperor Augustus remained for nearly two thousand

By D. Limpitlaw

The origins of mine closure practice have influenced the way in which it is implemented by companies and regulators. Mine closure practices essentially started developing in the 1970s in countries with advanced economies and mature mining industries. In these settings, the emphasis was justifiably placed on restoration of the landscape and an attempt was made to return to the ?natural? pre-mining land cover. These practices continued to evolve and incorporated socio-economic and cultural aspects, especially after the Brundtland Report in 1987 and the subsequent Earth Summit in 1992. Today mining is increasingly occurring in remote parts of developing countries where there may be significant need for infrastructure such as roads, clinics, and schools. The costs of returning land to low (economic) value pre-mining use may be far greater than establishing a viable postmining land use that could potentially add value to the community and take pressure off sites for greenfield development elsewhere. Furthermore, natural resource limitations (such as topsoil availability) may limit the degree to which the historical land cover can be re-established. Establishing post-mining land uses may aid in mitigating the loss of employment that is inevitable when mines close. Stakeholder participation in establishing post-mining land cover and land use options is critical for long-term success. Similarly, third parties must be identified to support the development of the post-mining land use This paper draws on the experience of the authors in several developing countries and presents a case for maximizing re-use of mining infrastructure. The paper does not advocate the adoption of poor rehabilitation standards, nor or the wholesale destruction of land capability, but rather leaving key infrastructure in place for post-mining use that may support sustainable development.

Jan 1, 2014

By P. van der Heever

The genesis of Simrac?s technology transfer practices and future initiatives are discussed in this report. Simrac produces a relatively large volume of research-based health and safety outputs that must be communicated to its tripartite stakeholders and to other interested and affected parties. The wide spectrum and complexity of the transferables, together with the diversity of end-user needs and skills of the recipient population, necessitate customizing of technology transfer practices. In an attempt to optimize this process, a variety of practices are employed. Information is transferred by means of publication and dissemination of a variety of reports (paper, website and CD).Knowledge transfer is directed to health and safety practitioners by means of workshops, seminars, best practice booklets, handbooks and textbooks. Promotion of recently completed projects is directed at targeted recipients by means of project launches. Only isolated cases of piloting and implementation of technologies have been undertaken due to lack of resources and past organizational focus. It is anticipated that Simrac?s new organizational structure and management system, together with end-user involvement by industry champions, from project inception to implementation, will enhance the effectiveness of the technology transfer process.

Jan 1, 2002

By A. Nuric, S. Nuric, L. Kricak, M. Negovanovic, S. Mitrovic

"SynopsisRotary drilling with rolling tricone bits is the most widely used method for drilling large-diameter blast-holes in large surface mining operations. This drilling method is applicable to a wide range of soft to hard rock materials. This paper presents a fuzzy model for predicting the penetration rate of tricone rotary blast-hole drilling. The model is based on data obtained during the drilling of blastholes in rocks with various uniaxial compressive strengths in the Veliki Krivelj open pit mine, Bor, Serbia. The model was developed using the fuzzy logic toolbox of MATLAB with the Mamdani inference system. The fuzzy model was tested with 23% of the total dataset. The results obtained show the high reliability of predicting the penetration rates. Although there are possible limitations in applying the model to other open pit mines because of differences in rock properties, the prediction methodology applied in this paper can be used in many other predictions of the penetration rates.IntroductionAccording to Tamrock, rotary blast-hole drill operations depend on four important elements:•,Torque in the drill string drive sufficient to turn the bit in any strata encountered•,A high bit loading capability (pulldown force) sufficient for optimum penetration•,An air volume sufficient to remove chips generated during the drilling and to provide cool air to the drill bit bearings•,The selection of the proper type of bit for the material being drilled (Tamrock, 1984).The effects of rock mass parameters on the choice of the type of tricone bits were investigated by Kricak (1997)."

Jan 1, 2015