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NIM reports Report No. 1615 Fluorspar pellets. A survey of the world market and an assessment of future South African production. Report No. 1621 Correction for matrix effects in the analysis of solutions by X-ray-fiuorescence spectrometry. Notices Questionnaire on Technicians The Department of National Education's committee of enquiry into the education, training, utilization, and status of engineering technicians in the Republic of South Africa was established as a result of Resolution 6.3 taken at the Sixth Conference on Engineering Education: The Education and Training of Engineering Technicians. Vraelys oor Tegnici Die Departement van Nasionale Opvoeding se komitee wat ondersoek instel na die opleiding, gebruik en status van ingenieurstegnici in die Republiek van Suid-Afrika is gestig as gevolg van Besluit 6.3 wat geneem is tydens die Sesde Konferensie oor Ingenieursopleiding: Die Opleiding van Ingenieurstegnici. Competition for Student Members of the South African Institute of Mining and Metallurgy Each year the Institute offers a prize (or prizes should the entries warrant it) of up to R100 for the best paper or dissertation on a topic appropriate to the interests of the Institute. The competition is open to all Student Members of the Institute.

Jan 8, 1974

By Y. -H. Chang, Y. -J. Jou, T. -S. Ueng, I. -H. Peng

In order to systematically study the size effect on the shear strength of rock joints, this study used the computer-aided-manufacturing system to reproduce the artificial rock joints for saw-toothed joints, Barton's standard joint profiles of JRC = 4~6 and 18~20, and natural rock joint profiles. We divided, enlarged, reduced, and assembled these joint profiles to obtain joint specimens of various sizes ranging from 75 mm to 300 mm in length. The shear strengths of these joint specimens were tested under different normal stresses using a direct shear test apparatus. The surface conditions of the joints at failure were also examined. The size and geometry effects on the shear strengths of these joints of various sizes and configurations were evaluated based on the test results. Um die künstlichen Trennflächen für reguläre dreieckige Trennflächen, Bartonsche standardmäßige Querschnitte der Trennflächen von JRC = 4~6 und 18~20 und natürliche Querschnitte von Trennflächen wiederherzustellen, benutzt diese Forschungsarbeit das Computergestützte-Erstellungssystem, damit die Maßstabswirkung auf die Scherfestigkeit von Trennflächen systematisch untersucht werden kann. Die Querschnitte werden geteilt, vergrößert, verkleinert und zusammengesetzt, um Trennflächenproben in Längen variierend von 75 mm bis 300 mm zu erhalten. Die Scherfestigkeit dieser Trennflächenproben wird unter unterschiedlichen Normalspannungen mit einem Direktscherversuchsgerät getestet. Die Querschnittszustände der Trennflächen bei Versagen werden ebenfalls untersucht. Nach den Untersuchungsergebnissen werden die Maßstabs- und Geometriewirkung auf die Scherfestigkeit dieser Trennflächen verschiedener Größen und Konfigurationen ausgewertet. Pour étudier systématiquement l’effet de la dimension des fractures des roches sur leur résistance au cisaillement un système de creation de fractures artificielles à l’ordinateur a été employé. Des fractures artificielles triangulaires, profils de fractures de Barton avec JRC = 4~6 et 18~20, et profils de fractures naturelles ont été reproduits. Les profils des fractures ont été arrangés de manière à obtenir des échantillons de longueur entre 75 et 300 mm. Une boîte de cisaillement a été utilisée pour étudier la résistance des fractures au cisaillement, sous plusieurs conditions de contraintes normales. Les conditions superficielles des fractures après rupture ont été étudiées. Les résultats de ces essais, effectués sur plusieurs échantillons de dimensions et configurations variées, ont contribué à établir l’influence des dimensions et de la géométrie des fractures sur leur résistance au cisaillement.

Jan 1, 2003

By S. Zhao, S. P. He, M. Y. Zhu, Y. Tao

"The effect of two refining slags (A: 1.0–1.8 CaO/Al2O3 ratio, 11–20 wt% SiO2; and B: 1.0–1.2 CaO/SiO2 ratio, 25–35 wt% Al2O3) on the inclusion morphology of a carbon structural steel (Q235B) was studied by controlling the balance between the steel and the refining slag at 1600ºC in a Si–Mo resistance laboratory furnace. The results showed that most of the inclusions in the molten steel balanced with slag A were formed by a lowmelting CaO–MgO–Al2O3–SiO2 system with a total oxygen content (T[O]) being fixed at 6–13 ppm. The inclusions in liquid steel balanced with the slag B were mostly formed by the CaO–MnO–Al2O3–SiO2 system, with T[O] controlled to 19–26 ppm. The overall size of the inclusions under balance conditions was higher in the steel reacted with the slag B than that reacted with slag A, with the latter showing more inclusions smaller than 3 um. In order to generate a large number of spherical CaO–MgO–Al2O3–SiO2 inclusions smaller than 3 ??m while decreasing the T[O] in the resulting steel, the composition of slag A should be used. This composition allowed improving the cleanliness of the slab, and is also advantageous for the castability of the molten steel. IntroductionThe sample used in this study was a typical carbon steel manufactured by CQ Steel. The galvanized, tinned, and plastic composite steel plates made of the original plates are used extensively for decorative panels, general dust pipes, drums, instrument cases, switchboxes, and train cars, among other uses. The target control composition is shown in Table I. The S and P contents are usually fixed during production below 0.020 and 0.025 wt%, respectively, with the aim of reducing longitudinal cracks on the slab surface."

Jan 1, 2017

By H. Griesel

The overall supply of platinum is forecast to rise more than the demand, and market deficit will narrow somewhat, but is still substantial at about 480 000 ounces. Because of this deficit, the price of platinum is expected to remain high, not taking into account the impetus from funds and speculators. With this strong demand for platinum and the high price, platinum producers still need to initiate projects to not only sustain current production, but also expand output into the high demand. However, the rise in the platinum price does not entirely offset the drop in revenue due to the strong rand. Consequently, in the current economic environment, executives and managers are under extreme pressure to initiate only the highest yielding projects and implementing them successfully. During the initiation phase of a project, the cost of changing concepts is the least, and strategic project decisions are the most important. It is during this phase that the most value can be added to a project, therefore requiring inputs from highly skilled, creative and experienced people. This paper will discuss thought processes and paradigms during the initiation of projects that will assist project owners in the selection and initiation of successful and profitable projects. The project initiation process will also be discussed outlining selection models, risk analyses and funding considerations.

Jan 1, 2004

By R. J. Hundermark, L. R. Nelson

The critical importance of tap-hole design and management to furnace performance and longevity is explored through examining some of the specific matte, metal and slag tapping requirements of non-ferrous copper blister and matte converting and smelting, ferroalloys smelting and ironmaking systems. Process conditions and productivity requirements and their influence on tapping are reviewed for these different pyrometallurgical systems. Some critical aspects of the evolution of tap-hole design to meet the diverging process and tapping duties are examined. Differences and similarities in tapping practices and tap-hole management are reviewed. Finally core aspects of tap-hole equipment and maintenance are identified that are considered important to securing improved tap-hole performance and life, so pivotal to superior furnace smelting performance.

Jan 1, 2014

By D. Orynbassar, N. Madani

This work addresses the problem of geostatistical simulation of cross-correlated variables by factorization approaches in the case when the sampling pattern is unequal. A solution is presented, based on a Co-Gibbs sampler algorithm, by which the missing values can be imputed. In this algorithm, a heterotopic simple cokriging approach is introduced to take into account the cross-dependency of the undersampled variable with the secondary variable that is more available over the entire region. A real gold deposit is employed to test the algorithm. The imputation results are compared with other Gibbs sampler techniques for which simple cokriging and simple kriging are used. The results show that heterotopic simple cokriging outperforms the other two techniques. The imputed values are then employed for the purpose of resource estimation by using principal component analysis (PCA) as a factorization technique, and the output compared with traditional factorization approaches where the heterotopic part of the data is removed. Comparison of the results of these two techniques shows that the latter leads to substantial losses of important information in the case of an unequal sampling pattern, while the former is capable of reproducing better recovery functions.

Aug 1, 2021

By M. Splaine, W. Davison, D. C. Atkinson

"Since 1964, Nchanga Consolidated Copper Mines, Ltd., has been developing and using production scheduling methods for optimizing its metallurgical operations in the short term (up to one year). Medium-range metallurgical planning has been possible only by successive evaluations of a single-year L.P. A modified version of Rosenbrock's direct search technique has now been developed to allow multi-year optimization of both mining and metallurgy for medium-range planning. The modifications to the search technique have produced a marked increase in computational efffciency for this heavily constrained problem in many variables and the system is a usable planning tool, given a reasonably powerful computer. The plans are 'optimum' in the sense that they yield the maximum present value of the operations.Each of the resulting five-yearly mine plans forms the basis for further detailed metallurgical evaluation by the established production scheduling system."

Jan 1, 2014

By H. Sasao, Y. Obara, A. Hirata

In the upper part of the planned location of the portal of a highway tunnel, there was a steep rock cliff with several unstable rock blocks. It seemed that the risk of those rock blocks to fall was very high. The cut-out to stabilize the rock cliff was monitored with various measuring instruments to prevent the sudden fall of the rock blocks. This paper discusses the measurement of acoustic emission and interpretation of its result during excavation of the rock cliff. We calculated displacements by integrating the accelerogram twice in terms of time, and demonstrated that slight displacements can be calculated from the measured AEs. Dans la partie supérieure de l’emplacement prévu pour le portail d’un tunnel autoroutier, il y avait un escarpement rocheux raide avec plusieurs blocs rocheux instables. Le risque de chute de ces blocs semblait très élevé. Lors de la coupe pour stabiliser l’escarpement rocheux, le suivi a été effectué avec différents instruments de mesure pour éviter la chute brutale des blocs rocheux. Cette thèse présente les mesures d’émission acoustique (EA) et l’interprétation de leurs résultats pendant l’excavation de l’escarpement rocheux. Nous avons calculé des déplacements en intégrant l’accélérogramme deux fois par rapport au temps, et montré que de petits déplacements sont calculables à partir des EA mesurées. Im oberen Teil des geplanten Ortes des Stollenmundes eines Autobahntunnels gab es einen steilen Felsen mit mehreren instabilen Felsenblöcken. Die Gefahr schien sehr groß zu sein, dass diese Felsenblöcke einstürzen können. Beim Abbau um die Stabilisierung des Felsens wurde das Monitoring mit verschiedenen Messinstrumenten zusammengestellt, um den plötzlichen Verfall der Felsenblöcke zu verhindern. Das vorliegende Papier diskutiert die Akustische Emission und die Auslegung deren Ergebnisse während des Abbaus des Felsens. Wir berechneten die Verschiebungen durch zweimalige Integrierung der Accelerogrammen in Bezug auf die Zeit. Die dargestellten kleinen Verschiebungen können aus den gemessten akustischen Emissionen berechnet werden.

Jan 1, 2003

By T. Oberthür

The Great Dyke of Zimbabwe constitutes the world?s second largest reserve of platinum group elements (PGE) after the Bushveld Complex in neighbouring South Africa. Within the Great Dyke, economic concentrations of PGE are restricted to sulphide disseminations of the Main Sulphide Zone (MSZ), which are currently mined at the Ngezi, Unki, and Mimosa mines. Near-surface oxidized MSZ ores have a large potential. Their total resources are in the range of ca. 160 ? 250 Mt; however, all previous attempts to extract the PGE from this ore type proved uneconomic due to low PGE recoveries (<< 50 per cent) achieved by conventional metallurgical methods. Within the ores of pristine, sulphide-bearing MSZ, the PGE are bimodally distributed. Platinum occurs mainly in the form of discrete platinum group mineral (PGM) grains (mainly bismuthotellurides, sulphides, and arsenides), whereas approximately 80 per cent of the Pd (and some Rh) is hosted in pentlandite. Within the oxidized MSZ ores, the PGE are polymodally distributed. Whereas arsenide- and sulphide-PGMs, making up ca. 25 per cent of the original Pt content of the ore, largely remain stable (relict PGMs), the remaining PGMs are disintegrated. The base metal sulphides are destroyed, partly releasing their base metal and PGE contents, and are replaced by iron oxides or hydroxides. Unspecified amounts of the PGE are redistributed and either form secondary PGMs, are found in chemically and mineralogically ill-defined (Pt/Pd)-oxides or hydroxides, or in iron-hydroxides, Mn?Co-hydroxides, and in secondary silicates. The problematic processing of oxidized MSZ ores is attributable to their complex nature and polymodal distribution of the PGE, prohibiting a significant upgrading of the ores by conventional metallurgical methods. Therefore, only bulk leaching methods are viable for ore treatment, and novel metallurgical methods have to be developed for the processing of these ores. Our ongoing work aims at locating the PGE in their mineralogical form in order to understand the mineralogical balance of the PGE in the ores and thereby facilitate the evaluation of metallurgical options for their recovery. A short overview on options and recent advances regarding the recovery of the PGE from oxidized ores is given.

Jan 1, 2012

By Y. H. Suh, H. C. Lee, D. S. Kim

A progressive karst formation and its influence upon engineered structures in the ‘phil-karst’ rock mass draw a tunnel engineer’s special attention to a long-term stability and the maintenance issues. Karst sinkholes of any size beneath the railway bed cause train wrecks or long interruptions in train traffic during rehabilitation work. The collapse of cave roof, called a ‘doline’, is in general connected to the cave by the gradual dissolving of the rock, developing into subsidence and sink-holes. The principal conclusions obtained from the field experiments are as follows: It is found that the development of karst cavity shows a relationship with a structural geological line and it is necessary to define the dominant directions of joint and geological layer (formation). The relation-ship between the water flow and joint direction can be used as an indicator of cavity presence in their direction. In addition the direction of in-situ stress can play a role in the development of karst cavities. A risk map of karst scenario is produced for the tunnel supporting systems with rock type classifications in water-soluble karstic rock mass. Eine fortschrittliche Karst-Formung und sein Einfluß auf angelegten Strukturen in der Phil-Karst-Felsenmasse wecken einem Tunnelingenieur eine besondere Aufmerksamkeit zu einer langfristigen Stabilität und der Wartungsausgaben auf. Karstensinkhöhlen in irgendeinen Größen unter dem Eisenbahnbett sind die Ursache der Zugeszerstörung oder der langen Unterbrechungen in Zugverkehr während Rehabilitationsarbeit. Der Zusammenbruch von Höhlendach, d.h. ein “doline”, ist im allgemeinen an die Höhle, die durch das allmähliche Auflösen des Felsen zu entstehen ist und sich in die Subsidence und Sinkhöhlen entwickeln, angeschlossen. Die Hauptschlüsse, die von Feldenprüfungen erhalten wurden, sind folgendermaßen: es wird gefunden, daß die Entwicklung von Karstenhöhlung eine Beziehung mit einer strukturellen geologischen Linie zeigt und es notwendig ist, die vorherrschenden Richtungen von Gelenk und geologischer Schicht (die Formung) zu definieren. Die Beziehung zwischen dem Wasserablauf und der gemeinschaftlichen Richtung kann als ein Anzeiger von Höhlungsanwesenheit in ihrer Richtung benutzt werden. Zusätzlich kann die Richtung von In-Situ-Spannung eine Rolle in der Entwicklung der Karstenhöhlungen spielen. Für das Tunnelunterstützungssystem, welches mit Felsentypenklassifizierungen in wasserlöslicher Karstic-Felsenmasse, ist eine Risikokarte von Karstenszenar hergestellt. Une formation progressive de karst et son influence sur les structures tracées dans la masse de roche "phil-karst" retiennent l&apos;attention particulière des ingénieurs de tunnel aux problèmes de la stabilité à long terme et du maintien. Les creux de karst de toute la taille sous le chemin de fer causent les accidents de trains ou de longues interruptions pendant le travail de réhabilitaion. L&apos;effondrement du plafond de caverne qui s&apos;appelle "doline" s&apos;est, en général, connecté à la caverne par dissolution progressive de la roche, en devenant l&apos;affaissement et les creux. Les conclusions importantes venant des experimentations sur le terrain sont suivants: d&apos;abord, le développement de la cavité de karst montre le rapport avec la ligne géologique de la structure et il est nécessaire de définir les directions dominantes du joint et la couche(formation) géologique. La relation entre l&apos;écoulement de l&apos;eau et la direction du joint peut être utilisé comme un indicateur de la présence de la cavité dans leur direction. De plus, la direction sur place peut contribuer au développement des cavités de karst. Le plan risqué de karst s&apos;est produit pour le système d&apos;appui du tunnel avec les classifications du type de roche dans la masse de roche karstique qui est soluble dans l&apos;eau.

Jan 1, 2003

By Deur T. A. M. Saayman

Die sesde jaarlikse Ingenieursimposium is in September by YSKOR, Vanderbijlpark gehou. Rierdie simposium, wat deur Ingenieurs-in-Opleiding georganiseer word, bied aan die Ingenieurs-in-Opleiding die geleentheid om referate te lewer oor projekte wat gedurende hul drie jaar opleidingsperiode uitgevoer word. Continuing education courses The following courses are to be given in the near future in The Netherlands. Coal trade, transportation, and handling . The 4th Coal Trade, Transportation and Handling Conference and Exhibition, CoalTrans &apos;86, will take place the Rai Congress Centre, Amsterdam, from 10th to 12th June, 1986.

Jan 1, 1986

By V. Sheikhzadeh, S. M. H. Haddad, M. Saghaeian, N. Esmaeili, R. Hejazi

One of the most significant features of iron ore concentrate (pelletising feed) is the specific surface area (SSA) that affects the achievement of desirable pellet properties. There are various methods to determine this parameters and currently, the most common is the Blaine air permeability method. However, due to the simplified assumptions including spherical and identical particles and 50% bed porosity, the Blain test does not provide accurate results. In fact, these two suppositions are far from reality. In this research, comparison of SSA measurement ways are investigated, containing laser diffraction testing and Blaine air permeability, on samples with different SSA, obtained from Ball mill and high pressure grinding rolls (HPGR). The output data showed that the calculated amounts of SSA by means of laser analysis were far greater than any other one. Furthermore, in the same results of Blaine air permeability tests on samples comminuted by different grinding methods, it was observed that the SSA figures from the laser diffraction method for HPGR products were almost 800 units greater than Ball mill ones. Keywords: Pelletising feed, specific surface area, Blaine air permeability, laser diffraction testing

Jan 1, 2020

By J. Autio, H. Malmlund

The excavation damage zone (EDZ) caused by drill and blast excavation consists of intense damage adjacent to the remaining half barrel of the blast hole, new fracturing induced by the blast and reactivation of pre-existing fractures. The properties of intense microfracturing adjacent to the half barrels of remaining blast holes are based on study of rock samples from ZEDEX-tunnel and it’s extension at Äspö and the Research tunnel at Olkiluoto in Finland. The new and reactivated fracturing is based on results of mapping of slots cut in the rock in ZEDEX-project. The zone of increased porosity adjacent to half barrels, which penetrates to a depth of some centimeters was studied by using novel 14C-PMMA method. The penetration of the radial fractures, which is an order of magnitude deeper, was studied by mapping using color penetrant. Results of EDZ studies carried out at Äspö HRL in Sweden and in Research Tunnel at Olkiluoto show that the properties of EDZ can be affected significantly by engineering design. The result imply that the additional pore volume caused by distinct fracturing around the blast holes caused by state-of-the-art smooth blasting technique could be of the same order as that of the damaged zone adjacent to the surface of the half barrels. Durch Bohr- und Sprengarbeiten entstandene Eigenschaften der Auflockerungszone: Die durch Bohr- und Sprengarbeiten entstandene Auflockerungszone besteht aus einem großen, an das Resthalbrohr des Bohrloches angrenzenden Schaden, neuer Rissbildung und einer Reaktivierung der bereits existierenden Risse. Die Eigenschaften einer immensen, an die Halbrohre der Restbohrlöcher angrenzenden Mikrorissbildung beruhen auf einer Studie über die aus dem ZEDEX-Tunnel gewonnenen Gesteinsproben und deren Fortsetzung im Untertage-Labor Äspö (Hard Rock Laboratory, HRL) in Schweden und im Forschungstunnel bei Olkiluoto in Finnland. Die neue und reaktivierte Rissbildung basiert auf den Auswertungsergebnissen der Schlitze, die bei dem ZEDEX-Projekt ins Gestein geschnitten wurden. Die Zone der vermehrten, an die Halbrohre angrenzenden Porösität, die in ein paar Zentimeter Tiefe eindringt, wurde anhand der neuen 14C-PMMA-Methode untersucht. Das Eindringen der etwas tiefer gelegenen radialen Risse wurde anhand eines farbigen Eindringungsmittels untersucht. Die in Äspö und Olkiluoto durchgeführten EDZ-Studien zeigen, dass die EDZ-Eigenschaften wesentlich durch Engineering Design beeinflusst werden können. Das durch Bohrarbeiten verursachte Hohlraumvolumen der Rissbildung um den Tunnel herum ist ähnlich wie das Hohlraumvolumen der Bruchzone um die Bohrlöcher herum. Caractéristiques d’une zone endommagée par le creusement résultant d’un creusement par forage et dynamitage: La zone endommagée par le creusement résultant d’un creusement par forage et dynamitage présente un endommagement intense adjacent au demi-cylindre restant du trou de mine, une nouvelle fracturation et la réactivation des fractures préexistantes. Les caractéristiques de la microfracturation intense adjacente aux demi-cylindres des trous de mine restants reposent sur l’étude des échantillons de roche en provenance du tunnel ZEDEX et de son extension au laboratoire souterrain d’Äspö (« Hard Rock Laboratory » ou HRL) en Suède et du tunnel de recherche d’Olkiluoto en Finlande. La fracturation nouvelle et réactivée repose sur les résultats du placement des rainures sur la roche dans le projet ZEDEX. La zone de porosité accrue adjacente aux demi-cylindres et pénétrant à une profondeur de quelques centimètres à fait l’objet d’études recourant à la nouvelle méthode 14C-PMMA. La pénétration des fractures radiales, considérablement plus profondes, a été étudiée par placement en utilisant un agent pénétrant coloré. Les résultats des études EDZ effectuées à Äspö et à Olkiluoto montrent que les caractéristiques de l’EDZ sont susceptibles d’être affectées de manière significative par la conception technique. Le volume vide de fracturation résultant du dynamitage autour du tunnel est du même ordre que celui de la zone concassée autour des trous de mine.service.

Jan 1, 2003

By B. R. Broekman, D. W. Penman

Discussion by P.J Lloydt Broekman and Penman describe (J.S. Afr. Inst. Min. Metal., vol. 91, Aug. 1991, p. 261) the addition of sodium cyanide and zinc sulphate to the flotation feed at Prieska. They note that for &apos;safety sake, lime was added to the rod mil to raise the pH to 9,5&apos;, and that &apos;personnel working in the vicinity of the rod mil were required to wear gas masks&apos;. Author reply to P.J. Lloyd We thank Dr Lloyd for his interesting contribution. As he correctly points out, the Prieska float had run with cyanide solutions at pH values of 6,4. In fact, it ran safely for extended period with the pH slightly below 6.

Jan 1, 1991

By G. van Aswegen

The geometry and morphology of a set of low-angle fractures around a stope in a deep Witwatersrand gold mine are explained in terms of extension fractures forming under variable conditions of stress. Primary extension fractures (E1) form some distance ahead of an advancing stope along the s1, s2 plane. With stope advance, a couple of these fractures end up in a stress regime conducive to transpressional shear and a secondary set of extension fractures(E2) is formed at a high angle to the primary fractures. i.e. at a low angle to the stope. As the E2 fractures are undermined, they migrate into a stress regime of transtensional shear and a third set of extension fractures (E3) may develop between E2 fractures. These have sigmoidal shapes, being parallel to the E2 fractures at the E2 discontinuity where s3 is negative, and curved through the unfractured rock between E2 fractures where s3 is positive at the instant of fracturing. The fractures all display fractographic features characteristic of dynamic extension failure with striae indicative of the direction of rupture propagation and the local, instantaneous orientation of s1.

Jan 1, 2012

By S. Jeon, J. Kim, H. Lee

Though the importance of the engineering rock mass properties such as deformation modulus, cohesion and friction angle is emphasized, the researches on the reliability of these values are rarely performed. By using modified Takagi-Sugeno (TS) fuzzy inference system, a fuzzy model was developed based on the data obtained from domestic tunnel construction sites, and the ability of prediction was compared with the empirical equations conveniently used for estimating these values, which finds that fuzzy model is better than empirical equation. Sufficiently large database, however, is required for training the fuzzy model for more accurate prediction. Obwohl die Wichtigkeit der technischen Eigentümer der Felsenmassen wie zum Beispiel Verformungsmodulus, Bindekraft und Reibungswinkel betont werden, wird die Forschung auf der Zuverläßigkeit dieser Werte selten durchgeführt. Mit modifiziertem Takagi Sugenos (TS) Flaumigenschlußsystem wird die Flaumigenmodelle von den Daten, die von inländischen Tunnelbaustellen erhalten werden, entwickelt. Zum Schätzen dieser Werte ist es viel günstig, Flaumigenmodell zu benutzen, als zu adoptieren die empirische Gleichung für die Fähigkeit der Voraussage. Genügende große Datenbank wird aber zum Ausbilden flaumigen Modells für genauere Voraussage erfordert. Quoique l&apos;importance sur la caractéristique d&apos;ingénierie de la masse de roche comme le module de déformation, la cohésion et l&apos;angle de friction, soit soulignée, la recherche sur la confiance de ces valeurs est rarement effectuée. Avec le système modifié de Takagi-Sugeno(TS) fuzzy inférence, le nouveau modèle fuzzy s&apos;est développé. Après avoir estimé sa valeur, nous pouvons savoir que ce modèle fuzzy, basé sur les données venant du chantier de construction de tunnel national, est mieux que l&apos;équaton empirique. Pourtant plus de données de base sont indispensables pour produire le modèle fuzzy plus précis.

Jan 1, 2003

By S. K. Murphy

A partial shaft pillar extraction project was embarked on at a mine in the West Wits mining region in South Africa. Prior to the extraction, a rock engineering assessment was conducted with the main objective being to establish which areas of the shaft pillar could be extracted without unduly affecting the stability of major infrastructure within the shaft pillar. Standard numerical modelling methods were used to conduct this assessment and several areas were identified for extraction. However, during the extraction process, it was found that the infrastructure was affected more than was originally predicted by linear elastic modelling. In addition to this, several large events resulted in far more large aftershocks than would normally be predicted. In order to gain an understanding of this phenomenon, seismic data was integrated with numerical modelling as follows: > The seismic data in the form of displacements was integrated in 3D space within the model to assess the effect of static stress changes associated with seismic activity > Data from large events was integrated onto specific structures, where displacements associated with large events were integrated onto the plane of structure in question. This paper describes the methodology and results obtained from each of the above processes and include insights into the mining process that were previously unfathomable using standard linear elastic numerical modelling. The way forward for this rock engineering assessment of partial shaft pillar extraction is also discussed.

Jan 1, 2012

By K. Isaac, S. O. Bada

This research focuses on the co-firing of discard coal with refuse-derived fuel (RDF) to utilize this abundant resource in South Africa for energy generation and reduce the volume of waste disposed of at landfills. The potential of a coal with a high ash content (> 40%), which is a grade used in some power stations in South Africa, and its combustion compatibility with two different RDFs in terms of emission reductions has been established. Gaseous emissions and ash residues from the combustion and cocombustion of the coal, two different RDFs and coal/RDF blends of different proportion were analysed. One of the RDF samples contained mostly paper (PB) and the other mostly plastic (PL). Co-combustion ash from the discard coal and RDFs showed a decrease in chloride and alkali metal contents as the coal ratio in the blend increased. The slagging propensity of the co-fired blends was found to be very low, while the propensity for fouling decreased from high to medium for all the blends with < 75% RDF. Cocombustion of RDF with coal showed a decrease in SO2 emissions from 387 ppm (discard coal) to 50 ppm for the sample containing 25% coal discard plus 75% PL. A 15% PL to 85% coal blend also reduced NOx emissions from 145 ppm (100% PL) to 88 ppm. The lowest CO2 emission observed was 6000 ppm for the blend of 85% discard coal plus 15% PB. It was established that the most favourable fuel blend that can produce the lowest sulphur emissions if used for power generation is the 25% coal discard plus 75% PL sample.

Aug 2, 2022

By S. F. Burks

"This paper develops themes explained at two SAIMM platinum conferences. Optimization techniques can be used to significantly increase the value of mining businesses by enabling better long-term planning decisions. Open pit and underground mine design, mine scheduling, cut-off grade and blending, stockpiling, and the linking of these to flexible elements of the metallurgical recovery processes are all evaluated together. Transport or sale of intermediate products and the requirements of the product metal markets can also be considered. Experience shows that net present value (NPV) can be increased significantly, usually even before the expenditure of significant amounts of project capital. Recent studies of NPV have aimed to simultaneously evaluate the impact of the optimized financial solution on the non-financial features of a project or operation.The case study presented comprised a commercially orientated review of the prefeasibility study designs and cost estimates of a platinum group metal (PGM) project in South Africa, followed by value chain optimization and sustainability studies of the project carried out simultaneously to identify potential value uplifts to be gained and guide the owners’ team going forward into the feasibility study phase. Some of the major aspects of the project that were found to have significant potential to add value included enhancement of the business model by the application of activitybased costing and theory of constraints, focus on the highest net value portions of the orebody in the early years of production, enhanced and optimized scheduling of the underground mining operation, application of dynamic grind and percentage mass recovery from ore to flotation concentrate (also known as percentage mass pull) to optimize revenue, application of elevated cut-off grades early in the life of mine, matching of the mining and processing capacity, expansion of the operation subject to capital availability, and installation of downstream processing facilities subject to regional third-party capacities.The investigation of non-financial project features focused on demonstrating that a financially optimized solution could also have a number of other benefits. These are mentioned briefly in the paper, which aims to present the status of the project at an early stage of its development."

Jan 1, 2016

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 22nd August, 1973. Dr J. P. Hugo (President) was in the Chair. There were also present 64 Fellows, 20 Members, 5 Associates, 3 Students, and 34 Visitors, making a total of 126. The President declared the meeting open at 4.05 p.m. OBITUARIES The President: It is my sad duty to announce the death of the following members of the Institute C. Boocock, R. J. G. Moore, M. P. Pearse, and A. I. Sussman, all Fellows, and W. T. Dalling, a Life Member. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I ask you to rise and observe a few moments&apos; silence. MINUTES Die President: Item twee op die agenda is die bekragtiging van die notules van die jongste Algemene Vergadering van die Instituut. Daar die notules in die Augustus uitgawe van die Joernaal gepubliseer is, vra ek u toestemming dat dit as sulks bekragtig word. Toestemming verleen. WELCOME TO VISITORS The President: It is my very great pleasure to welcome all the distinguished guests who have honoured us with their presence this afternoon; in particular, a hearty word of welcome to the Honorary President of the Institute, Mr Plumbridge, the President of the Chamber of Mines. You are doubly welcome here, sir, and we thank you for your presence. Also to that old member and stalwart, the Honorary Vice-President of the Institute, Mr Tommy Gibbs, the Government Mining Engineer-you&apos;re very welcome, Mr Gibbs. Then, we are particularly privileged this afternoon to have an Honorary Member with us, the Minister of Mines for Rhodesia, Mr Dillon. You will recall that he honoured us with his company last year. Mr Dillon, we are very appreciative and hope that this is now a standing arrangement. We are also honoured by the presence of some thirteen Presidents, Vice-Presidents, or Chairmen of our sister scientific and technical organizations. I shall rapidly read their names, but they must all feel assured that they are very welcome here today. Firstly, one of our own Past Presidents and members, Mr Geoff Goode in his capacity as President of the Associated Scientific and Technical Societies of South Africa; Mr L. R. Robinson, President of the South African Institution of Mechanical Engineers, and Mrs Robinson; Mr G. Goedhals, President of the South African Institute of Electrical Engineers ; Dr Antrobus, President of the Geological Society of South Africa, and Mrs Antrobus; Mr T. V. Dean, Vice-President of the Institute of Land Surveyors of the Transvaal, and Mrs Dean; Mr R. M. Stroh, President of the Mine Ventilation Society of South Africa; Mr Ken Steele, President of the Association of Mine Managers, and Mrs Steele; Mr Mike Gericke, President of the South African Council for Professional Engineers; Mr R. G. Matthews, President of the Institute of Mine Surveyors of South Africa; Mr P. H. Pettifor, President of the Institute of Production Engineers, London, and Mrs Pettifor ; Dr Nico Stutterheim, Chairman of the South African Institute of Chemical Engineers, and Mrs Stutterheim; Professor F. A. van Duuren, Chairman of the Engineers&apos; Liaison Committee in Pretoria; also, I haven&apos;t spotted him but I trust he is here-Mr Alex Bain, who is Chairman of this Institute&apos;s Witbank/Middelburg Branch. To one and all, ladies and gentlemen, a hearty word of welcome. Not last on our list, a word of welcome to Mr Eric Boden, the Manager of A.S. and T.S. We also have with us I trust, Dr Deist, and his good lady-Dr Deist will be figuring in our proceedings later this afternoon. Also Mr Barcza and Mrs Barcza. Mr Bareza, a former President of the Institute, also has a task to perform. Then, I hope two of our student prize winners are here-Mr Beetge and Mr Painting. Then we also have Mr Roberts, who is welcome in his capacity as co-author with Dr Deist. Then, last of all, a hearty word of welcome to Dr Helen Glen (I am not sure whether she has arrived yet, but she is certainly due to come)-the new Honorary Editor of the Institute&apos;s Journal. MEMBERSHIP The President: I have pleasure in announcing that, their names having been published in accordance with By-law 5.2.2, the following have been elected by Council to membership in the following grades Fellows: W. G. Jayes and F. K. Wright Members: D. W. Penman, A. W. Bryson, and D. L. Gibbs Graduates: R. J. Adey, J. P. Bond, R. C. Dunne, G. M. Entwhistle, J. M. Rendu, J. P. S. Turner, and A. P. van Jaarsveld Associates: A. Ellis, B. R. Hambly, A. J. Johansen, and G. W. Tregoning

Jan 10, 1973