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By G. Poropat, A. R. Guest, H. P. Grobler

At the De Beers Consolidates Mines operations it is common practices to perform Geotechnical mapping of the newly exposed faces in the waste and ore rock. The purpose of Geotechnical mapping is to quantify the in-situ fracturing of a rockmass that in turn is required during the planning and application of a mining method. Whether it is to determine slope angles, caveability, impact of blasting or support requirements. This mapping involved a cumbersome and time consuming procedure that requires individual examination and description of the natural inherent fractures exposed by mining. During highwall mapping in an open pit this can be a safety concern due to the duration of time spent below a highwall. The advantages gained through the recent introduction and application of SiroVision® allows safer mapping, an increase in statistical fracture population, archiving of rock faces and the more accurate reflection of the true mapping. This paper aims to describe in detail the application of the recently developed SiroVision®, photogrammetry software, to replace conventional face mapping. A De Beers Consolidated Mines, il est pratique courante de faire une cartographie géotechnique des tailles récemment exposées dans le rocher stérile ou minerai. Le but de la cartographie géotechnique est de quantifier la fracturation in-situ d’une masse rocheuse, qui sera nécessaire lors de la planification et application d’une méthode minière, que ce soit pour déterminer les angles des galeries inclinées, les possibilités de foudroyage, l’impact du dynamitage, ou les besoins en supports. Cette cartographie nécessitait une procédure longue et compliquée qui demande l’examen individuel et la description des fractures naturelles propres exposées par l’opération de mine. Pendant la cartographie de parois dans une exploitation à ciel ouvert, cette opération peut être dangereuse à cause du temps passé sous la paroi. Récemment, le lancement et application de Siro Vision apportent l’avantage d’une cartographie plus sûre, une augmentation des statistiques de population de fracture, l’archivage des tailles de roches, et le reflet plus précis de la cartographie. Le but de l’étude présente est de décrire en détail l’application du développement récent de Siro Vision, logiciel de photogrammétrie, pour remplacer la cartographie de taille conventionnelle. Bei den De Beers Consolidates Mines Operationen ist es gängige Praxis geotechnische Aufzeichungen des Taub- und Erzgesteins neu geöffneter Abbaustellen zu erstellen. Zweck dieser geotechnischen Aufzeichnungen ist die vor-Ort-Quantifizierung des Bruches der Gesteinsmasse, welche im Gegenzug während der Planung und der Anwendung einer Abbaumethode erforderlich ist, sei es um einen Neigungswinkel festzustellen, Abbaubarkeit, Auswirkung von Sprengungen oder Anforderungen an Unterstützungen. Die Aufzeichnungen waren mit umständlichen und zeitaufwendigen Prozeduren verbunden, die eine individuelle Prüfung und Beschreibung der durch den Abbau freigelegten natürlichen inhärenten Brüche, verlangten. Dies kann auf Grund des Zeitraumes der unterhalb einer Flözoberschicht verbringt wird zu einer Frage der Sicherheit werden wenn die Aufzeichnung einer Flözoberschicht im Tagbau erfolgt. Die Vorteile auf Grund der jüngst erfolgten Einführung und Anwendung der SiroVision® gestatten sichereres Aufzeichen, eine Zunahme in der statistischen Menge an Gesteinsbrüchen und eine akkuratere Reflektion der tatsächlichen Aufzeichnungen. Diese Arbeit hat zum Ziel im Detail die Anwendung der kürzlich entwickelten SiroVision®, eine photogrammetrische Software, die die konventionelle Abbauortaufzeichnung ersetzen soll zu beschreiben.

Jan 1, 2003

By J A. H Campbell

AK6 is a Cretaceous aged kimberlite located in the north-east of Botswana, close to Debswana's Drapa and Letlhakane Mines. It was discovered by Debswana in 1969, but was considered unattractive from an economic perspective. In 2003, Debot Prospecting Pty Ltd ('Debot') re-assessed the area and with the advent of new prospecting technology, particularly large diameter drilling ('LDD') and more detailed ground geophysical surveys found AK6 to be of interest. In 2005, the Boteti joint venture was formed between Debot and African Diamonds plc ('AFD'), which covered a number of Prospecting Licenses, including that which contained AK6.

Jan 1, 2010

By J. H. Cloete, S. M. Bradshaw, D. K. Chibwe

"The primary function of a tundish in the steelmaking industry is to serve as a buffer tank, accepting molten steel from the batch ladle process and allowing it to be cast continuously. However, modern steelmaking has more stringent demands for the quality of the steel product, requiring increased control over the properties of the molten steel before casting. For this reason tundishes have been developed as metallurgical reactors to serve as the final step in refining of the molten steel by removing non-metallic inclusions, preventing the formation of new inclusions, and promoting chemical and thermal homogeneity. In this study the flow behaviour in a four-strand tundish was investigated by means of a half-scale water model as well as numerical modelling. Both the numerical study and physical model were used to characterize residence time distribution (RTD) in the vessel and calculate properties pertaining to the tundish flow regime. Three different tundish configurations were investigated: a bare tundish with no flow control devices, a tundish with a turbulence inhibitor and a tundish with both a turbulence inhibitor and a dam.The physical and numerical models showed that a tundish without flow control devices was prone to significant short-circuiting. A tundish with a turbulence inhibitor was shown to be successful in preventing short-circuiting and provided surface-directed flow, which aids inclusion removal in the slag. Despite the benefits of the use of turbulence inhibitors, it was observed that the upward-directed flow increased the maximum turbulence kinetic energy near to the surface by approximately 120% compared with the bare tundish. Therefore the potential for slag entrainment should be considered during the design and operation of tundishes utilizing turbulence inhibitors."

Jan 1, 2014

By E. Moosavi, K. Tolouei

In mine production scheduling problems are well-known, where most are categorised into deterministic and non-deterministic NP-hard problems because of their complexity. Many researchers have attempted to solve the problem by applying various optimisation techniques. While using traditional methods they observed extreme difficulty in solving highly complex problems. In the 1990s, many researchers addressed long-term production scheduling (LTPS) by using simulated annealing, the genetic algorithm, the tabu search algorithm, and the ant colony algorithm. These algorithms are known as the meta-heuristic algorithms, and have proved to be the most efficient algorithms for solving LTPS thus far. The firefly algorithm is one of the best methods for visualising problems related to LTPS, and provides the best possible optimisation. It is one of the simplest methods, and easy to apply to any NP-hard problem. The experimental, and comparison with other recently published algorithms shows that the proposed algorithm is feasible, and is an effective approach for long-term production scheduling problems. The results indicated that a better solution is obtained by the proposed method, compared to other methods in terms of cumulative net present value, and average ore grade. Additionally, the CPU time via the proposed model is roughly 2.52% higher than the other method.

Sep 1, 2021

By C. Steyn, J. D. le Roux

A dynamic model is used to represent the single-stage closed grinding mill circuit at Mogalakwena North Concentrator. The circuit consists of a ball mill closed by a hydrocyclone. The circuit is modelled according to a semi-mechanistic non-linear dynamic model available in literature. An algebraic routine is used to fit model parameters to steady-state process data. Preliminary validation results against dynamic data indicate that the model is capable of capturing the main dynamic trends of the plant. Since classical system identification techniques proved insufficient to produce accurate models; the non-linear model can be used as a reliable source for model-predictive controller design. Keywords: Grinding, modelling, process control, parameter estimation

Jan 1, 2020

By E. G. Galvez, E. Mate, L. A. Cisternas, C. Cruz, L. Cortés, M. E. Osorio

Designing and optimising flotation circuits are critical for mineral beneficiation plants, and therefore several procedures have been published. The modelling of flotation circuits with the objective of design and optimisation is problematic in that different approaches are used for the modelling of flotation units and regrinding units. Usually, regrinding models are based on particles characterised by their size, while flotation models are based on species characterised by fast and slow classes. The relationship between particle size and liberation can be used, but it requires laboratory studies that are time-consuming and costs are high. It is therefore not surprising that few studies on flotation circuit design and optimisation include flotation units and regrinding units simultaneously. In this paper, it is proposed to model the regrinding stage using species characterised by fine-slow, medium-fast, and coarse-slow flotation species. In deep, the regrinding model is derived from a population balance approach based on flotation species. The fraction of these species at the feed and product of the grinding unit is determined by flotation tests. Then, based on these data, the model parameters can be determined by a regression estimation procedure. A local ore was used to validate the model. Keywords: Modelling, flotation circuit, grinding circuit, process design

Jan 1, 2020

Two column flotation cells have been installed as single-stage rougher cleaners at Batu Hijau. The objective was to provide additional residence time in the cleaner circuit to maintain maximum recovery during high mill throughput and high feed grade periods. Installation of the columns has allowed the relatively coarse, well-liberated rougher concentrate and the relatively fine, low-grade scavenger concentrate to be treated separately, improving metallurgical performance in the cleaner circuit. Plant results show that the columns produce a high-grade concentrate at an average stage copper recovery of approximately 80 per cent. There is also indication of increases in both overall plant copper recovery and final concentrate copper grade. In addition, the operability and stability of the cleaner circuit has greatly improved.

Jan 1, 2007

By K. B. Le Bron, T. van Aard

The empirical pillar strength formulae have been widely, and in most cases successfully, applied to design underground pillars for mines in the Bushveld Igneous Complex (BIC). This paper presents the case for combining the empirical method with numerical modelling when it comes to crush pillar stability analyses. The benefits include an understanding of potential failure mechanisms, which may then be accounted for in the designs. In addition, the impact of weak layers, such as shear zones, the impact of the dip of the orebody, differences in layouts, such as holing widths and the presence of advanced strike gulleys (ASGs) immediately adjacent to the crush pillars, and stress regime (k-ratio) may be studied using numerical modelling, as it is not accounted for in the empirical method.

Mar 5, 2025

By T. Ito, N. Tokashiki, H. A. Bilgin, Ö. Aydan, T. Akagi

This study is concerned with the electric potential induced by deformation, fracturing and sliding of non-piezoelectric geomaterials. In experiments, the acoustic emissions together with electric potential measurements were also measured in order to see how the so-called seismic electric signals are associated with new fracture occurrence and propagation and sliding in case of existing discontinuities. The outcomes of this experimental study may explain why such electric potential variations may occur during the fracturing and sliding of non-piezoelectric geomaterials. On the basis of these outcomes, their possible implications in geo-engineering and geo-science are discussed. Ce travail concerne 1e potentiel électrique produit par la déformation, 1a fracture ou le glissement du matériel géologique non-piézoélectrique. Aux expérimentations, on a mesuré 1es émissions acoustiques avec le potentiel électrique afin de constater la relation entre les phénomènes de glissement ou de formation et de propagation de nouvelles fractures le long des discontinuités existantes. Les résultats de ce travail expérimental expliquent pourquoi de telles variations de potentiel electrique se produisent durant le glissement ou la fracture du matériel non-piézoélectrique. Sur la base de ces résultats, on a discuté de leurs éventuelles implications dans les domaines de 1a géologie et de 1a géo-ingénierie. Diese Studie befasst sich mit dem elektrischen Potential das durch die Deformation, Bruchbildung und Gleiten von nicht-piezoelektrischen Geomaterialien induziert wird. In Experimenten wurden die akustischen Emissionen zusammen mit elektrischen Potentialmessungen gemessen, um zu sehen, wie die so genannten seismischen elektrischen Signale mit neuer Bruchbildung und Ausbreitung sowie Gleiten im Falle von vorhandenen Diskontinuitäten verbunden sind. Die Ergebnisse dieser experimentellen Untersuchungen könnten erklären warum elektrische Potential Schwankungen während der Bruchbildung und dem Gleiten von nicht-piezoelektrischen Geomaterialien entstehen. Auf der Basis dieser Ergebnisse, wurden ihre möglichen Implikationen in Geoingenieurwissenschaften behandelt.

Jan 1, 2003

Council and Standing Committees, 1979-1980 President: D. A. Viljoen. Senior Vice-President: Dr P. R. Jochens. Junior Vice-President: G. Y. Nisbet. Honorary Treasurer: Dr D. G. Krige. Immediate Past President: Dr M. G. Atmore. Members of Council: J. D. Austin, A. N. Brown, J. A. Cruise, C. E. Fivaz, J. S. Freer, P. N. Harris, H. E. James, Dr R. P. King, Prof. F. Q. P. Leiding, Dr B. K. Love¬day, D. G. Malan, C. S. Macphail, J. C. Mostert, H. G. M. Rose, G. C. Thompson, R. A. von Maltitz, Dr H. Wagner. Past Presidents Serving on Council: R. J. Adamson, H. Britten, J. K. E. Douglas, Prof. D. D. Howat, Dr J. P. Hugo, D. G. Maxwell, Prof. R. P. Plowman, Dr R. E. Robinson, Dr M. D. G. Salamon, P. W. J. van Rensburg, P. A. von Wielligh. Chairman, Witbank-Middelburg Branch: R. B. Smith. Chairman, Orange Free State-Klerksdorp Branch: W. C. Mather. Materials Engineering Division, Chairman: Dr J. P. Hugo. Secretary: G. Pienaar. Standing Committee Chairmen: Membership, G. Y. Nisbet; Technical Programme Metallurgy, H. E. James, (Prof. R. P. King) ; Technical Programme Mining, H. G. M. Rose; Vacation School Metallurgy, J. C. Mos¬tert; Vacation School Mining, J. D. Austin; Awards, Dr M. G. Atmore ; Excursions, A. N. Brown ; Adjudications, Dr M. G. Atmore ; Constitution, Rules, and Policy, Dr M. G. Atmore ; Monograph Series, Dr M. G. Atmore ; Training and Career Guidance, P. A. von Wielligh (D. G. Malan) ; National Phoenix Committee, Dr R. E. Robin¬son; 1982 Council of Mining and Metallurgical Congress, Dr M. G. Atmore ; Mines and Works, Dr M. G. Atmore.

Jan 1, 1980

By M. Matabane, T. Khati

"Accurate delineation of the contact between a kimberlite pipe and country rock at production level depths is a challenge due to limited geological data. Geological information is obtained from widely spaced diamond core boreholes which are drilled either from surface or from higher mining levels within the pipe. Kimberlite pipe/country rock contacts are notoriously irregular and variable, further reducing the confidence in contact positions defined by the drill-holes. At Finsch Diamond Mine (FDM), the opportunity arose to further improve the confidence in the contact positions relative to the planned slot (end) positions of each sublevel cave tunnel during the development stage of these tunnels. As a result, the accuracy of the 3D geological model has improved.The use of diamond drill core for this purpose is expensive due to site establishment requirements. The lengthy time taken during site establishment also delays the development of tunnels and support cycles, thereby extending the completion dates. FDM has reduced delays during development by adopting percussion drilling, in conjunction with gamma ray logging. The S36 drill rig is mounted on a moveable platform and does not require a costly and lengthy site establishment. The holes are generally drilled (0°/flat) on grade elevation, and these holes could also be drilled from the rim tunnels (developed in waste) into the kimberlite pipe. A single-boom production drill rig is normally used to drill holes about 20 m in length.On completion of the contact delineation drilling, gamma logging of the holes is conducted using the GeoVista geophysical sonde (or probe) to log the natural gamma signature of the dolomite/ kimberlite contact. The advantage of this tool is that the readings are continuous within centimetre intervals, and due to contrasting characteristics between kimberlite (rich in clay minerals) and dolomite, the contact position can be determined accurately. The better definition of contact positions also adds value to tunnel stopping distance in terms of developing the tunnel’s slot at the optimum distance from the contact (easier blasting of longhole rings, avoidance of contact overbreak and premature waste ingress, and other matters relating to extraction of ore from these tunnels). This method is highly successful and has reduced development costs (on-time completion), improved definition of the pipe’s contact position for geological modelling, improved blast design, and mitigated early waste ingress by maintaining the contact’s integrity."

Feb 1, 2019

Exxaro installed their first ultra fines treatment plant at Leeuwpan Coal mine. The plant is now fully operational and results already show that the plant has great potential. The plant was designed and installed by DRA. Several challenges were faced during the installation due to the space constraints in the Leeuwpan plant. Efficiency tests were conducted on both modules after commissioning and showed very promising results. A lower ash product with a higher yield can be produced with the fine coal dense medium cyclones compared to the spirals previously employed.

Jan 1, 2010

By S. W. Jacobsz, E. P. Kearsley, N. K. Schoeman

A physical modelling approach was adopted to simulate the process of cave mining propagation at various horizontal to vertical stress state ratios, and image data was captured and used to characterize the resulting failure mechanisms. Image processing was integrated into the study to determine minor principal strains in models to identify where critical extensional strains had been exceeded relative to crack propagation. The study exhibited a scale factor magnitude of 119 using a calculated critical extensional strain value of 0.014% for the modelling material used. It was perceived that cave propagation occurred through successive parallel extensional ‘fracture bands’ in all cases, as noticed in models of prior studies, deviating from that described by the Duplancic model. Cracks tended to bisect regions of minor principal strain equal to the critical extensional strain, which suggests ‘fracture banding’ is an acceptable failure mode for brittle, rock-like materials. Moreover, it was found that models with lower horizontal to vertical stress ratios (K ratios) showed a greater degree of vertical development of the caving mechanism (at similar vertical stresses), while the vertical extent of the cave was suppressed in models with higher K ratios. Models subjected to larger vertical stresses experienced slower cave formation in latter time-steps. These models exhibited larger two-dimensional caved perimeters and areas, respectively.

Nov 30, 2022

By J. E. Dickinson, R. Campbell, M. J. Cole, K. P. Galvin, M. C. Cole

It is common practice in the beneficiation of iron ore ultrafines to apply reverse flotation, and hence float the gangue minerals, leaving behind a high-grade iron ore product. Given the difficulty in floating particles finer than 20 μm, especially those finer than 10 μm, it is necessary to subject the feed to desliming ahead of flotation. There are two problems with this approach. Firstly, given the known inefficiencies of cyclones, desliming needs to be aggressively applied to particle sizes upwards of 45 μm to ensure all the offending ultrafine gangue is removed. Secondly, desliming also removes a significant portion of the valuable iron ore. Thus, a significant portion of the ultrafines, including the iron ore, is lost to the tailings. This paper examines the direct flotation of iron ore fines using the Reflux Flotation Cell. The RFC operates using a concentrated bubbly zone, in the absence of a conventional froth zone, for delivering strong counter current washing through an inverted fluidised bed of bubbles ahead of the product discharge. A system of parallel inclined channels in the lower part of the cell provides enhanced segregation of the bubbles from the tailings, preventing the loss of air bubbles into the tailings. Experiments conducted under semi-batch conditions produced encouraging results with concentrates of ~65% Fe grade in a single flotation stage. Comparatively, up to five successive batch flotation stages were required when using a laboratory scale batch mechanical flotation cell to achieve similar Fe grades. For a given grade, lower Fe recoveries were typically achieved by the RFC. This was attributed to the effective prevention of ultrafine particles succumbing to hydraulic entrainment under a positive bias flux, as well as an increasing feed volume involved in the semi-batch operation using inverted fluidisation water for cleaning. Overall, similar grade-recovery curves were produced, however, significantly higher grades were obtained by the RFC and with fewer separation stages. Keywords: Desliming flotation, iron ore, modified release analysis, reflux flotation cell

Jan 1, 2020

This report describes the investigational work on the development of a fire-assay method capable of concentrating, in a button of nickel sulphide, all six of the platinum-group metals present in samples of ores, concentrates, and mattes. In the method adopted, the sample is fused with a mixture of sodium carbonate, sodium tetraborate, nickel carbonate, and sulphur. The nickel sulphide formed during fusion collects the noble metals and carries them to the bottom of the crucible. The nickel sulphide button is dissolved, and the noble metals are isolated and determined. The coefficients of variation range between 1,0 and 4,9 per cent for the various platinum-group metals when they are present in concentrations between 0,3 and 75 p.p.m.

Oct 15, 1971

By J. Engelbrecht

Understanding the deportment of minerals in size fractions has already led to improvements in the flow sheets for platinum minerals beneficiation. There are, however, more potential changes in the flow sheets that may improve the recovery of platinum group metals or reduce the costs of beneficiation before refining. Based on known technology of pre-concentration, milling, gravity concentration, flotation, and magnetic separation a number of potential alterations or additions can be considered and motivated based on the mineral deportment in size fractions.

Jan 1, 2012

By Brian Wyatt, Neil Webb, Marcel Roche, John Thirkettle

Recent developments in survey techniques and measuring equipment now allow for an accurate assessment of external coating condition and cathodic protection performance. These developments build on 20 years of experience of using Direct Current Voltage Gradient (DCVG) and Close Interval Potential Survey (CIPS) methods. The techniques use the latest advances in measurement systems coupled to a bespoke data processing system. The paper describes tests and trial surveys carried out on a hydrocarbon transmission pipeline in West Africa during 2005. The survey works described and conclusions drawn are from the data collected. Of particular interest are the apparent capacitance effects which are thought to occur under disbonded coating and the characteristics that these may show on the integrated CIPS and recorded DCVG profiles. This paper was originally presented at the Cefracor conference in Aix, France, in June 2006 The pipeline was originally installed on a phased basis between 1989 and 1994. The external coatings were three layer polyethylene factory coating and shrink sleeve field joint coating. An impressed current cathodic protection system was installed. The pipeline has subsequently been affected by disbondment of the coatings. It was a primary objective of the trials to attempt to identify such affected areas. In addition to a technically detailed account of the survey works undertaken and the results obtained the authors will consider the practical and commercial aspects of these surveys with input that provides a perspective from the specifier, pipeline surveyor, pipeline operations personnel and the pipeline owner. It is intended that the data presented will provide greater awareness of the benefits and limitations of the techniques used and their role for both stand-alone interpretation and the integration of the survey information with other inspection methods used for external corrosion assessment. The application of the described techniques is well developed and proven to locate and characterise through?coating defects and to provide a full audit of cathodic protection status. However, the possibility of the techniques being able to indicate disbonded coating is unproven and further tests and trials are planned which may allow a greater understanding of the electrical characteristics which are believed to be associated with disbonded coatings which may or may not be filled with an electrolyte. Further work is currently planned in West Africa, South Africa and Scotland in order to improve the understanding of this technique and to determine if the reported indications do actually represent a method of locating disbonded coatings. Keywords: External Coating, Cathodic Protection, DCVG, CIPS, corrosion assessment.

Jan 1, 2006

By J. A. Maritz, D. F. Malan

Pillar strength is affected by pillar shape, but this has largely been ignored in past research studies. Bord-and-pillar layouts are typically designed using empirical strength equations developed for square pillars. Owing to the poor quality of pillar cutting, many hard-rock pillars have an irregular shape and it is not clear how this affects pillar strength. Furthermore, the strength of rectangular pillars in comparison with square pillars is also difficult to quantify. The ‘perimeter rule’ is widely adopted for rectangular pillars, but its applicability for pillars with irregular shapes has never been tested. We used numerical modelling in this study to investigate the effect of pillar shape on strength. An analytical limit equilibrium model of a square and a strip pillar also provided useful insights. For slender pillars, the strength of a long rib pillar is essentially similar to that of a square pillar. In contrast, for rib pillars with a large width to height ratio, there is a substantial increase in strength. The study found that the perimeter rule should not be used for irregularly shaped pillars. Displacement discontinuity modelling, using a limit equilibrium approach, is proposed as an alternative to determine the strength of these pillars.

May 3, 2023

By G. Drennan, A. Cameron

"South African mining operations depend on the skilled professionals produced through the tertiary education sector. In geoscience courses at the University of the Witwatersrand, which lead into the mining sector, there has been a significant increase in student intake over the past 15 years. This increase has been characterized by a radical shift in demography: in classes where white male students once formed the majority, black female students are now in the majority. This demographic shift appears closely linked to policies addressing issues of social justice and transformation in post-apartheid South Africa. We document this change and consider the role played by employment equity legislation (as in the Mining Charter) and corporate social investment strategies in the mining industry, notably through bursaries offered to black female students. We also look at the changing needs of the industry, where the critical need for managerial skills, not just technical knowledge, is highlighted through data from surveys of past students and industry managers. Our findings indicate the need for a curriculum adjustment to meet these changing requirements, as well as more rigorous selection criteria for bursars than simply gender, race, and appropriate matric results. IntroductionThe South African economy has historically been linked to mining and the exploitation of mineral resources. South African mining operations are dependent on the professional labour that is produced through the tertiary education sector, with critical thinking, teamwork, and the art of negotiation having been identified as the crucial skills required for this industry (Sideropoulos, 2014). Over the past three decades the South African system of education has gone through a period of dysfunction that it is struggling to rectify (Maphai, 2014). This has impacted on the levels of academic preparedness of students applying for places in higher education. Concurrently, government and university policies have widened access to higher education in response to the need to address issues of social injustice and transformation related to South Africa’s history of apartheid. As a result, the number of students admitted to universities has increased dramatically. In the School of Geosciences at the University of the Witwatersrand (Wits), the increase in student numbers has been accompanied by a significant change in demographics: classrooms which in the past were dominated by white males have given way to classrooms in which black females are often in the majority. This demographic shift is related to legislation such as the Mineral and Petroleum Resources Development Act and the Broadbased Socio-Economic Empowerment Charter, developed to reshape the socio-economic and equity frameworks of the country (Botha and Cronje, 2015). Requirements aimed at transformation in terms of management, skills development, and employment equity, together with corporate social investment (CSI) requirements, have resulted in bursaries being made available to attract students from designated groups, which in turn has increased the number of black students, and notably black female students, taking courses in geosciences. However, due to the economic downturn, instability in the mining industry has recently resulted in the downsizing of some mines, with international investors pulling out of South Africa. This instability resulted in devastating strikes across all sectors of the mining industry (Stewart, 2013) and in Marikana, an important platinum mining area, the strike culminated in a deadly shoot-out between miners and police. The resulting tensions spilled over into the gold mining sector, resulting in further strike action, shaft closures, and retrenchments. These challenges have implications not only for the mining industry in South Africa, but for the tertiary education providers whose graduates would have been absorbed into the mine-related workforce."

Jan 1, 2017

By S. Liaghat, J. Rosenkranz, P. Semsari Parapari, S. Chehreh Chelgani, A. Tohry

It is commonly accepted that the energy consumption for comminution within mineral processing is responsible for around 3% of the global electrical energy usage. However, it was clearly noted that inside mills, less than 1% of this energy efficiency is actually consumed for particle size reduction. Therefore, monitoring of grinding parameters and modelling of product particle size distribution (e.g. characterised by the 80% passing size P80) play an essential role in operating costs of a mineral processing plant. Several empirical models have been introduced for the prediction of the P80. Since in the industrial scale usually a few numbers of grinding variables are monitored, these models cannot identically be used in plants. In addition, these empirical models do not always indicate the magnitude of correlations between milling variables. This study proposes to introduce the Hilbert-Schmidt independence criterion (HSIC) as an intelligent model for exploring linear and nonlinear relationships between grinding variables and P80 for an industrial scale data assessment. HSIC can rank variables based on their importance and help to select the most effective one for the generation of predictive models. HSIC modelling through various monitored grinding variables (ball charge, feed input rate, F80, power draw and work index) of an industrial plant indicated that F80 as a feed property has the highest effect on P80 of the ball mill products. Modelling results highlighted that the P80 can be accurately predicted, based on effective variables by using a HSIC model. These outcomes showed that HSIC as a powerful modelling tool can assess the relationships between monitored grinding parameters, select the most effective grinding parameters and satisfactorily predict the P80. Keywords: Product particle size, variable importance measurement, Hilbert-Schmidt independence criterion, mill charge

Jan 1, 2020