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In many practical situations, the samples available to estimate a block of ore are not located on a regular grid. The sample sizes and orientations are not constant, and the number and relative position of the samples used for valuation of each block change from block to block. Estimation of a block W might be very complex and time consuming if each sample in the neighbourhood of the block were considered individually. A practical solution consists of grouping the samples in blocks Wi (i = 1, 2, . . . n) in the neighbourhood of W, and estimating µw as a weighted average of the mean xi of the samples in Wi. Possible ways of grouping the samples are illustrated in Fig. 1 1.1. More complex patterns can be found in the literature (Krige, 1966) To calculate the kriging estimator of pw, we must be able to calculate the variance of xi, the covariance of xi and xj, and the covariance of xi and pµw. The purpose of this chapter is to show how these quantities can be calculated when we ignore the position of the samples in the block Wi. We consider the samples to be randomly distributed in Wi; kriging with this assumption is known as random kriging.

Jan 1, 1978

By T. A. Silva, A. C. Bragança

Lime has been added to the iron ore slurry transported by the Samarco pipeline since its operation start-up in 1977.Initially, internal corrosion was the main concern therefore the reagent was used only for pH correction. Over the last ten years, though, transport of more complex slurries demanded a significantly higher dosage of lime to guarantee adequate rheology control. Several other reagents have been tested for the same purpose yet none has proven to be as effective regarding technical performance, environmental impact and cost. However, an alternative was sought so that the slurry rheology could still be controlled in case lime addition became impracticable. The objective of this paper is to present a technical solution for this matter, which takes into account environmental aspects. It consists of adding soda for pH correction and an organic coagulant as a rheology modifier. The latter is a quaternary ammonium salt which affected the slurry transport properties in the same manner as lime when tested in a laboratory. It showed no plug formation and allowed solid particles to settle, forming a loose sediment after rest. These results indicate a low probability of plug occurrence in the pipeline and the formation of a readily reslurryable sediment upon shutdown of the pumping system. Industrial tests should be performed in order to validate the laboratory results.

Jan 1, 2007

By K. -C. Han, S. -Y. Kim

This study was carried out in a bid to survey Ganboke gold mine in Pala, Mayo-Kebbi Province, southwestern Chad. The Ganboke mine is now being prepared for investigation and development, and the research sought to perform rock properties tests of relevant rocks through its geological survey, rock mass evaluation, and in-situ and laboratory tests and analyze the stability by the means of limit equilibrium method, thereby suggest appropriate methods to design the pit slope and individual benches in Ganboke mine. Targenting GS1-GS1' section with the depth of 180 m and GS2-GS2' section with the depth of 150 m in the survey area, we set the height of the bench at 10 m and 15 m, and the angle of bench at 60o and 70o, respectively, and then reviewed the stability for dried condition and saturated condition. The result of examination indicated that it would be appropriate to set the bench height at 10m and the bench angle at 60o in developing the mine slopes concerned. Cette étude est réalisé dans le but de faire des recherches sur Ganboke mine d'or dans Pala, Mayo-Kebbi Provence, Tchad sud-ouest. La Ganboke mine est actuellement en train de étre disposé à la investigation et le développement, et la recherche a cherché à accomplir les tests de la propriétè des roches par l'intermédiaire de la étude géologique, la évaluation de la masse rocheuse, et in-situ et les tests de laboratoire et à faire l'analyse de la stabilité au moyen de la méthode d'équilibre limite, de ce fait à proposer le methodes propres à faire le plan de la pente et les gradins individuels dans la Ganboke mine. Concernant la section de GS1-GS1' avec la profondeur de 180 m et la section de GS2-GS2' avec la profondeur de 150 m dans l'aire d'étude, nous mîmes l'hauteur du gradin à 10 m et 15 m, et l'angle du gradin à 60o and 70o, respectivement, et alors nous avon reconsidéré la stabilité pour la condition sèche et la condition saturé. Le résultat d'examen a indiqué que il pourrait être propre de mettre l'hauteur du gradin à 10m et l'angle du gradin à 60o en développant les pentes de la mine concerné. Diese Forschung wurde um das Gold Bergwerk zu überschauen in Pala, Mayo-Kebbi Provinz, der Südwesten Chad ausgeführen. Das Ganboke Bergwerk ist jetzt zur Erforschung und Entwicklung vorgebereiten worden, und die Forschung suchte zu ausführen die Prüfungen der Felseigenschaft durch geologischen Überblick, Felsmassewertbestimmung, und In-situ und Lavorversuch auf, und analysieren die Stabilität mittelst der Grenzegleichgewichtsmethode, da-durch schlug die angemes-sen Methoden zu entwerfen die Böschungen und die einzelnen Bänke im Ganboke Bergwerk vor. Für den Abschnitt GS1-GS1' mit der Tiefe von 180 m und GS2-GS2' mit der Tiefe von 150 m in der Überblickfläche, wir setzten die Bankhöhe an 10 m und 15 m, und das Bankwinkel an 60o und 70o, beziehungsweise, und dann zurückblickten die Stabilität für die getrockneten Bedingungen und die gesättigten Bedingungen. Das Ergebnis der Untersuchung anzeigte daß es würde angemessen sein zu setzen die Bqnkhöhe an 10m und das Bankwinkel an 60o in der Entwickelungen vom Bergwerk be-teiligt.

Jan 1, 2003

Results from a study undertaken at a Transvaal colliery on the feasibility of undermining an urban development by conventional bord-and-pillar mining operations in the No. 4 Seam of the Highveld Coalfield are discussed. Surface ground vibrations above production sections were measured, analysed, and then compared with well-accepted guidelines so that the expected effects of vibration on inhabitants and surface structures could be determined. The measurement and scaling of ground vibration from blasting are outlined, and the effects on humans and structures are discussed. It is concluded that residential areas can be safely undermined by conventional drilling and blasting techniques provided certain simple guidelines are followed.

Jan 1, 1987

By J. H. Viljoen, N. B. Strydom, J. S. Greyson, C. H. Van Graan

SYNOPSIS Bad eyesight and poor illumination can contribute to the occurrence of accidents in mines. As one part of a study of this problem, surveys of light intensities have been conducted in 19 gold mines. On 17 of the mines the surveys were on one underground level only, whilst in two of the mines more intensive surveys were conducted by measuring light intensities in all areas to determine any inter-mine variations between the levels of illumination. Readings of light intensity were taken underground at stations, tips, winches, stopes, conveyor belts, waiting places, pump stations, fitters' and boilermakers' workshops, ambulance rooms and in haulages. It is concluded that the average levels of illumination in South African gold mines are comparable with those reported in the literature for mines elsewhere. Standardisation of lighting conditions underground could eliminate inter- and intra-mine variation in illumination levels where they occur. A guide to mine illumination practice would assist such standardisation, and help increase the levels and effectiveness of illumination in mines. Some suggestions are made in this latter connection.

By P. Horrell, K. Rhodes, G. Harrison, J. Dean, D. Sammons, M. Stander

Anglo Platinum have perceived a need to increase the rate of reef development both for new mechanised stoping technology and on conventional new developing mines. The Research and Development Division of Anglo Platinum therefore initiated an experimental reef raise project with a tunnel boring machine (TBM) at Bafokeng Rasimone Platinum Mine (BRPM). The scope of the trial was for the boring of a reef raise 340 metres in length on the Merensky Reef. The boring phase of the trial took place over six months and the average rate of penetration of the TBM was 0,47 metres/hour. TBM utilisation was 22%. The TBM used in the trial was a Jarva MK6 manufactured in 1972 and its design with its backup system was not considered to be an ideal machine for reef development. However it was the intention of the trial to prove the concept of developing with a TBM on reef. In this respect the trial was unequivocally a success. There were many problems and long delays did occur during the boring phase. Nevertheless there is every confidence that a new TBM can be designed specifically for this type of work that will achieve high rates of advance up to (say) 400metres/month and with a more flexible steering system in order to negotiate reef changes. It can therefore be expected that TBMs will be used in the future for reef development on South African platinum mines.

Sep 1, 2001

By F. Pinto, J. V. Lemos, A. Sousa, L. Ribeiro e Sousa

The Rossio railway tunnel was built in 1890 crossing several formations involving limestones, basalts and also sandy and clayey formations. Due to the fact that it is an old underground structure rehabilitation and repair works were performed, namely at Km 0,900 and in a zone crossed by a new tunnel from the Lisbon Metro. Reinforcement support systems were designed in the Rossio tunnel in order to prevent its stability. In this paper, repair works and anchor tests performed at km 0,900 are presented, as well as the monitoring system implemented in order to observe the structural effects induced by the construction of the works. For the interpretation of the obtained information complex 3D models was built, permitting the simulation of the sequential excavation scheme used, non-linear behaviour of the different formations, and the support systems used. Der 1890 erbaute Rossio Eisenbahntunnel durchoertert mehrere Formationen, einschliesslich einer Kalkstein-, Basalt- sowie einer sandigen und tonigen Formation. Auf Grund des Alters des unterirdischen Bauwerks wurden Instandsetzungs- und Reparaturarbeiten im Bereich km 0,900 sowie im Kreuzungsbereich mit einem neuen Tunnel der Lissabonner U-Bahn durchgeführt. Aussteifungssysteme wurden entworfen, um die Stabilität des Rossio Tunnels zu gewährleisten. Im Folgenden werden die Instandsetzungsarbeiten und Anker Tests im Bereich km 0,900 sowie das Messystem zur Ueberwachung der strukturellen Auswirkungen der Bauarbeiten dargestellt. Zur Interpretation der gewonnenen Informationen wurden komplexe 3D Modelle entwickelt, die eine Simulation des Bauablaufs und die Anwendung nichtlinearer Stoffgesetze fuer die verschiedenen Formationen und Aussteifungssysteme ermöglichten. Le Tunnel ferroviaire du Rossio a été construit en 1890, traversant des différents terrains comme des calcaires, des basaltes et aussi des formations limoneuses et sableuses. Dû à l’ancienneté de l’ouvrage, des travaux de réhabilitation et réparation ont été faits, nomment au km 0,900 et dans la zone traversée par le nouveau tunnel du Metro de Lisbonne. Des systèmes de support renforcé ont été conçus pour le Tunnel du Rossio de façon à rassurer sa stabilité. Dans ce papier, on présente les travaux de réparation et les essais d’ancrage réalisés au km 0,900, et aussi, le système d’auscultation mise au point pour l’observation des effets structuraux induits par les travaux. De façon à interpréter l’information résultant de l’observation, des modèles 3D complexes ont été utilisés, permettant la simulation de la méthode séquentielle de l’excavation, du comportement non - linéaire du terrain et, aussi les systèmes de support utilisés.

Jan 1, 2003

By Y. Sagawa

The Hishikari Gold Mine consists of epithermal vein type Au-Ag deposits, each of which has several veins standing almost in parallel each other and inclining 70 to 90 degrees. The veins have 1 to 3m widths and are extracted mainly by drifting and bench stoping with waste rock fill. The Hishikari has tried to optimise the stope dimensions by the Potvin’s Stability Graph Method, which is well known as an easy and effective tool to design appropriate stope dimensions. The method, however, has some limitations of application due to its simplicity so that it has been used only in limited cases. The authors developed a new numerical approach, based on 2D FEM solu-tion for the stability analysis. As a result, it has been possible to solve the Hishikari situation. The authors also introduce the concept of the design approach and compare the results obtained by us-ing the approach with the database of the Stability Graph Method for validation. La mine d’or Hishikari se compose de gisements d'Au-AG avec des types de filons épither-maux dont chacun a plusieurs veines qui sont presque parallèle les unes par rapport aux autres et sont inclinées de 70 à 90 degrés. Les veines ont de 1 à 3 m de largueur et elles sont principalement extraites en creusant et en abattant des bancs de roches encaissantes. Hishikari a essayé d’optimiser les dimensions du chantier d’exploitation avec la méthode de graphique de stabilité de Potvin, bien connue comme un outil facile et efficace pour avoir des dimensions de chantier d’exploitation appropriées. Toutefois, la méthode a certaines limites d’application dues à sa sim-plicité de sorte qu’elle a été utilisée seulement dans des cas limités. Les auteurs ont développé une nouvelle approche numérique, basée sur la solution 2D FEM, pour l’analyse de stabilité. Par conséquent, il a été possible d'expliquer la situation de Hishikari. Les auteurs présentent le concept de l'approche et ils comparent les résultats donnés en l'employant avec la base de données de la méthode de graphique de stabilité pour la validation. Die Hishikari-Goldmine besteht aus Au-Ag-Ablagerungen mit epithermalen Adern, die jeweils mehrere Adern aufweisen, die mit einer Neigung zwischen 70 und 90 Grad nahezu parallel zueinander verlaufen. Die Adern haben eine Breite von 1 bis 3 Metern und werden überwiegend durch Vortrieb von Stollen und Bergversatz abgebaut. Hishikari hat versucht, die Abmessungen des Abbauorts durch das Potvins Stabilitätskurvenverfahren zu optimieren, das als einfaches und effizientes Mittel für die Erzielung angemessener Abmessungen des Abbauorts bekannt ist. Das Verfahren weist jedoch aufgrund seiner Einfachheit einige Anwendungsbeschränkungen auf, so dass es nur in einigen Fällen benutzt worden ist. Vor diesem Hintergrund haben die Autoren einen neuen numerischen Ansatz entwickelt, der hinsichtlich der Stabilitätsanalyse auf der 2D-FEM-Lösung beruht. Dadurch wurde es möglich, das Problem von Hishikari zu lösen. In diesem Dokument stellen die Autoren die Grundlagen des Ansatzes vor und vergleichen die erzielten Resultate durch Benutzung der Datenbank des Stabilitätskurvenverfahrens zur Validierung.

Jan 1, 2003

By SAIMM Journal

COLLOQUIUM ON COMMINUTION The Institute has arranged a colloquium on the above topic to be held on 13th March, 1973, at Kelvin House. The following papers will be presented: 'Peripheral Discharge Mill', by A. H. Mokken, Union Corporation Limited

Jan 1, 1974

By G. E. Blight

The mining industry is making increasing use of pumped tailings fills. The properties that affect the performance of tailings fills are described by means of typical examples. They are the particle-size grading for maximum density, the water content for pumpability, settlement after placing, compression and drainage under stress, shear strength, and resistance to shock loading.

Jan 1, 1979

By P. C. Seligmann

The theory of firing of electric detonators is developed insofar as it affects the design of blasting circuits. Practical values for the firing conditions suited to detonators of local manufacture are tabulated. The design principles of blasting circuits are outlined. This information can be used by mine management to ensure that electric blasting will be done efficiently and economically.

Jan 1, 1979

By R. P. King

The ideas leading to the formulation and utilization of a flotation model are developed. The main theoretical and experimental work that has been carried out by the National Institute for Metallurgy Research Group at the University of Natal is presented. The two experimental flotation plants available to this Group are described.

By B. C. Alberts

Rapid and effective handling of run-of-mine, waste, and treated materials is vita.! to every step of resource development and recovery. Modern mine managements have planned and engineered systems for the handling of ever-larger tonnages. Where traditional methods have not proved to be costeffective and adequate, managements have pioneered the development of new materials-handling systems in the mining industry.

Jan 1, 1983

By J. M. Stewart

The purpose of my few comments is to try to create a healthy perspective to constructively link considerations of the sessions to follow to those of the earlier sessions. I propose to do this by considering some of the issues and priorities related to the development of backfill systems and technology for South African gold mines.

Jan 1, 1988

By H. L. Monro

CONTRIBUTION BYP.J.D.LLOYD The thought-provoking paper by Monro deserves serious consideration. If he is correct, the practice of selling gold forward should cease forthwith. However, similar arguments may well be advanced against the selling forward of many other commodities, and this runs counter to the success of futures markets worldwide. If, indeed, the practice were basically flawed, then such markets should long since have failed.

Jan 1, 1992

By F. P. A. Robinson, J. W. Fourie

Austenitic stainless steels are welded using low-heat inputs. However, owing to differences in the physical metallurgy of austenitic stainless steels and duplex stainless steels, low-heat inputs should be avoided for duplex stainless steels. This paper highlights the differences in solidification mode and transformation characteristics of these two types of alloys. Recent work on the effect of heat input on the properties of weldments of duplex stainless steels is reviewed.

Jan 1, 1990

By J. P. M. Hojem, C. Dimitriou, N. C. Joughin

This paper describes the design and construction of the first experimental underground rockcutting machine from measurements of cutting forces determined in tests on small rock specimens in the workshop. The deficiencies of this design, revealed by stoping with almost identical rockcutting machines, are described. An account is given of the design and construction of further experimental machines incorporating substantial improvements which made them technically feasible for use in production.

By P. H. S. W. Kulatilake

The paper introduces a computer simulation technique to estimate the target detection probabilities associated with search surveys. The technique takes into account the inherent randomness associated with the distributional properties of geologic targets. Use of the technique is illustrated through examples. The paper provides information as to how this technique can be used in obtaining the optimum sampling pattern and optimum spacing associated with target detection surveys.

Jan 1, 1987

By R. K. Brummer

The support of stopes and tunnels in South African gold mines subject to rockburst damage requires special attention. The interaction of a seismic wave with either a stope or a tunnel is subject to a number of variables, namely the distance from the source of the event, the ground velocity, the orientation of the excavation with respect to the direction of the seismic wave, and the geology and fracturing around the excavation. This paper discusses these factors in relation to the support requirements in stopes and tunnels. The need for the integration of hydraulic props with stope support and the use of yielding anchors for tunnel support are emphasized.

Jan 1, 1988

By M. J. H. Tonkins, C. C. Crosson, G. Paterson

The development of drilling and blasting practice at Palabora Mining Company Limited by c. C. CROSSON, Pr. Eng., A.C.S.M. (Hons), BASe. (Min. Eng.) Toronto, M.!.M.M. (Member), M. J. H. TONKING, Pr. Eng., A.C.S.M., BASe. (Min. Eng.) Toronto, M.I.M.M. (Member), and G. PATERSON, B.Se. (Min. Eng.) Glasgow, M.!.M.M. (Visitor) Open-pit drilling and blasting practice at the Palabora Mining Company Limited is described, with particular reference to the development of aluminized slurry explosives. Rotary drilling of primary drill holes, drilling patterns, and blasting techniques for use with slurry explosives are described.

Jan 2, 1976