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By R. R. Mankowski, F. J. Cox

Experimental results are presented on the longitudinal atenuation of a kinetic shock wave traveling along a typical mine hoisting cable. Mathematical curve-fiting of the results established these losses to be exponential and tension-dependent. The reflection and power-transmission coeficients of a typical winding drum were also investigated. The degree of penetration of an incident stress wave onto the coil of cable wrapped round the drum is shown to be governed by a second-degree relationship, and is solely dependent on the acceleration of the cable at the cable-drum interface. Although the investigation is limited to the testing of a single hoisting cable, certain qualitative trends that were identified can be generalized and applied to other types of hoisting cable with diferent geometries, elastic properties, and instalations.

Jan 1, 1986

By B. G. Meyburgh

SYNOPSIS As a result of a test programme over a period of approximately ten years and a decision to extend the uranium plant, it was decided to design and erect the first full-scale Purlex Plant in the Republic of South Africa. The plant at Buffelsfontein G.M. Co. Ltd. was commissioned in August, 1968, and to date has produced results superior to those predicted in the original estimates. The capital expenditure was R678 000 for a plant capable of treating 1 600 gallons per minute of pregnant solution. Compared with the conventional resin ion exchange process, it has been found that the saving in production costs is 21 cents per pound U3O8 produced. The amine loss is 10 parts per million, which is equivalent to a total organic loss of 250 parts per million. The uranium loss in the raffinate is less than 0.001 g/l U3O8. The final product is of a high quality and it is probable that it is pure enough to convert to the fluoride directly.

By M. J. A. Leal-Gomes

There is a set of settled ideas in the field of the mechanics of rock mass joints, that need a deep revision, after the last experimental works of several authors. In this paper, this theme is approached under several viewpoints, like the following ones: the essential influence of the mating or mismatching of rock joints on their strength (different strength models are applicable to these two situations, one leading preferably to normal scale effects, and the other to inverse scale effects); Patton's model is a bad formulation of the joint strength, whenever there is a dilation effect in the slidings (actually, the essential consideration of the amplitude of the roughess isn't made by any limit equilibrium model, like Patton's model); the joint strength increases as the width perpendicular to the sliding direction is reduced (previous works of other authors suggested the independence of the strength on that width); the reduction of the anisotropy of the roughness, as the sample symmetry and sample dimensions increase; there is no scale effect in the discontinuity mechanics, if there is no roughness heterogeneity; when only the same roughness and undulation orders are involved in the tests, shorter samples have larger peak displacements and lower shear stiffnesses than larger samples (usually, the contrary is admitted). For all these reasons, there isn't an easy correlation between the small scale tests and the natural large joint scale. Only "in situ" large scale tests have some representativeness. All the above mentioned questions are correlated to each other. Es gibt eine Menge eingewurzelter Ideen im Gebiet der Mechanik von Felsklüften, die, nach den letzten experimentellen Arbeiten von mehreren Verfassern, eine tiefe Überprüfung benötigen. In dieser Mitteilung, wird dieses Thema unter mehreren Blickpunkten angegangen, wie die folgenden: der wesentliche Einfluß des Zusammenpassens oder nicht Zusammenpassens von Gesteinsklüften auf ihre Festigkeit (verschiedene Festigkeitsmodelle sind auf diese zwei Situationen anwendbar, eins, das vorzugsweise zu normalen Maßstabseffekten führt, und das andere, das zu umgekehrten Maßstabseffekten führt); Pattons Modell ist eine schlechte Formulierung der Kluftfestigkeit, immer wenn es einen Dilatationseffekt in den Verschiebungen gibt (in Wahrheit, wird die wesentliche Berücksichtigung der Rauheitsamplitude von keinem Grenzgleichgewichtsmodell beachtet, wie Pattons Modell); die Kluftfestigkeit wächst wenn sich die Breite senkrecht zur Verschiebungsrichtung verringert (frühere Arbeiten anderer Verfasser suggerierten die Unabhängigkeit der Festigkeit von jener Breite); die Verringerung der Rauheitsanisotropìe, wenn die Probekörpersymmetrie und Probekörperabmessungen zunehmen; es gibt keinen Maßstabseffekt auf die Trennflächenmechanik, wenn es keine Rauhheitsheterogenität gibt; wenn nur die gleichen Rauheits- und Ondulationsgrößenordnungen in den Versuchen verwickelt sind, haben kürzere Probekörper größere Spitzenverschiebungen und geringere Schersteifigkeiten als größere Probekörper (gewöhnlich, wird das Gegenteil angenommen). Wegen aller dieser Gründe, gibt es keine einfache Korrelation zwischen den Versuchen im kleinen Maßstab und dem natürlichen großen Kluftmaßstab. Nur "in situ" Versuche im großen Maßstab sind einigermaßen repräsentativ. Alle die oben erwähnten Fragen hängen miteinander zusammen. Il y a un ensemble de des bien établies arrière-pensées idées dans le champ de la mécanique des discontinuités en massifs rocheux qui ont besoin d'une profonde revision, après les derniers travaux de divers auteurs. Dans cet article cette matière est abordée sous divers points de vue, comme les suivants: la signification essentiel de l'ajustement ou du désajustement des discontinuités dans leur résistance. Des différents modèles sont applicables à ces deux situations, une conduisant de préference à des effets d'échelle normaux et l'autre à des effets d'échelle inverses; le modèle de Patton est une mauvaise formulation de la résistance des joints quand il y a effet dilatant dans les glissement. En effet la contribuition essentielle de l'amplitude de la rugosité n'est pas consideré par aucun modèle d'équilibre limite comme le modèle de Patton; la résistance des joints croit au fur et à mesure que la largueur perpendiculaire à la direction de glissement est réduite. Des travaux antérieurs d'autres auteurs suggéraient que la résistance était indépendant de cette largueur; la réduction de l'anisotropie de rugosité au fur et à mesure que la symétrie et les

Jan 1, 2003

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 D. D. Marsden

This paper discusses the concentrations of sulphides and total sulphur in widely spread regions around mine residue deposits, from which rain-water run-of can enter the Vaal River system. Analyses of borehole samples from several deposits are used to establish typical sulphur head grades. It is shown that a high percentage of al the oxidizable, and hence leachable and pollution-causing, sulphur has already been removed. When the residues were fresh, water that came from the deposits was highly polluted, but the dissolved solids from these residues are today of very minor significance. The data are supported by analyses of the drainage streams.

Jan 1, 1986

By E. A. Brinkmann

A kinetic model framework for single particle kinetics in combined diffusion and adsorption processes is presented. The framework applies to the general case in which both diffusion and the adsorption reaction play important roles in determining the overall rate in processes where the migrating species can both adsorb and accumulate. The technique, which should be applicable to a wide range of reaction mechanisms, consists of an iterative integration procedure for the coupled diffusion and reaction equations. The case of a reversible linear adsorption reaction rate is developed. In order to verify the technique as a legitimate method of model development, an analytical solution for the identical case is derived and compared to the numerical solution. Excellent agreement exists between the two solutions.

Jan 1, 1987

Ausmelt is supplying commercial quantities of an alkyl hydroxamate flotation collector AM28 for flotation of oxide and supergene base metal ores and tailings. AM28 is a non-hazardous product used as a ten per cent to 50 per cent solution in dilute potassium hydroxide. It is a selective flotation collector for oxide or oxidised base metal minerals and replaces conventional sulfidisation for oxide mineral flotation. At Radio Hill, the AM28 is used in conjunction with traditional sulfide collectors, which allows simultaneous flotation of oxide and sulfide copper minerals. The Fox Resources Radio Hill copper concentrator near Karratha, Western Australia, is currently configured to treat supergene copper ore sourced from the West Whundo open pit. This Archean VMS type copper deposit has been deformed and remobilised with uplift, erosion and weathering to form a significant supergene zone. The sulfide copper minerals present in the upper zone are digenite and chalcocite with lesser chalcopyrite and covellite. Oxide copper minerals present include cuprite, with lesser malachite and azurite. Gangue minerals include quartz, talc and chlorite. Plant trials at Radio Hill are reported for supergene West Whundo ore, where the AM28 was stage added into the circuit at nominally 80 g/t. Plant data over three months shows the copper recovery increased consistently from around 50 - 60 per cent to above 70 per cent when AM28 was added. This has been proven statistically. The grade of the concentrate was consistent with and without AM28, at nominally 22 - 24 per cent copper.

Jan 1, 2007

By B. G. Fordyce, W. B. Parker

A description is given of the methods used in management planning, pit-equipment selection and maintenance operator training, and formal organization of mining personnel.

Jan 1, 1979

By S. J. C. L. Peeters

Geographical information systems (GISs) provide sophisticated functionalities t1tat can be used by the personnel in many aspects of the mining industry to visualize, analyse, and manipulate spatial and tabular data. This paper presents an experimental case study for Hartebeestfontein Gold Mine. It shows how data from different computer systems can be brought together into a GIS by use of the Arc/Info and ArcView programs.

Jan 1, 1996

By H. A. D. Kirsten

The paper reports on loading tests conducted on shotcrete reinforced with mesh and various types of steel fibre, and compares the results with the energy absorbing capabilities of 16 mm rebar shepherd's crooks. It is concluded that mesh-reit1forced shotcrete has sufficient energy-absorbing capabilities to contain rockbursts of significant magnitude, having greater energy absorbing capabilities, even at a thickness of 50 mm, than 16 mm rebar shepherd's crooks. Fibre-reinforced shotcrete has energy absorbing capabilities of the same order as, or better than, those of 16 mm rebar shepherd's crooks, but its performance is erratic.

Jan 1, 1995

By D. Brazier, W. Laing, D. Nixon

Keywords: Pyrometallurgy, furnace, smelter, copper, Palabora The Palabora copper smelter has operated for the past 38 years, treating concentrates produced at the mine site. Palabora has reduced captive material by almost 40 per cent with the transition from a large open-cast to a smaller underground mine. The smelter and refinery complex was designed to treat 120 kt contained copper units per annum, with the underground only supplying 70 per cent of the feed. The agreed strategy was to import enough concentrates to maximise production and reduce operational unit costs. This transition has presented the Palabora management with new challenges both in technical and financial aspects.

Jan 1, 2006

By H. L. Monro

The price received for a commodity decreases as the quantity sold increases. all other factors remaining the same. This has been the position with gold since it was demonetized in August 1971. The result is that the marginal revenue per kilogram of gold decreases steadily with increased production. If operating losses are to be avoided, the marginal cost of production must not exceed the marginal revenue. This requirement, although not seriously violated by most invididual mines, is not met by the industry as a whole, resulting in large losses of income to the State and the shareholders. These losses are increasing, and a way of curbing or reversing this trend is described.

Jan 1, 1984

By H. J. E. Hamel

Some aspects of the deformation behaviour and temperature rise during instantaneous compression loading of high purity aluminium By H. J. E. HAMEL The influence of deformation speed on the deformation behaviour of high purity aluminium was investigated. By varying the initial height-to-diameter ratio a considerable influence on the deformation behaviour could be noticed. Lubrication of the specimen end faces was found to have an influence on the flow behaviour and on the roughness of the specimen interface at pressing platens. The results of temperature measurements during deformation agree with work-hardening behaviour of the specimens. Flow curves calculated with the measured temperature rises do not agree with results obtained at lower strains by other workers. The possible reasons are discussed.

By A. P. W. Briggs

Difficulties with the screening of large volumes of pulp to remove plus 600 /km material before the adsorption circuit and to retain plus 20-mesh carbon in the adsorption contactors have largely been solved, with the result that the plant can now handle its design throughput. The elution and electrowinning processes have been modified to simplify the circuit, but the regeneration of carbon remains unsatisfactory. The production of fine carbon in the plant can lead to increased gold losses, and this carbon must be collected and treated. Collection methods for fine carbon and some indications of the quantity of the carbon and its gold values are given.

Jan 1, 1983

By H. M. Dus, D. J. Smith

Resistivity tests indicated that, at temperatures lower than 1450°C, reducing agents alone, as well as burdens consisting of high-carbon ferrochromium and reducing agents, exhibit wide differences in resistivity. These differences are less pronounced at elevated temperatures. The resistivity of a reducing agent and the volume fraction it occupies are important factors controlling the resistivity of burdens of high-carbon ferrochromium. A mathematical model is formulated to describe the dependence of the resistivity of mixtures of conducting and insulating particles on the particle sizes and the volume fraction occupied by the conducting phase. The resistivity of burdens of high-carbon ferrochromium is high if the particle size of the reducing agent is larger than that of the other components of the burden. A number of reducing agents showed small variations in their reactivity towards chromite ore in the solid state. However, with chromite ore in the liquid state, reduction proceeded more rapidly with reducing agents occupying larger volume fractions. During the smelting of manganese ore, high initial rates of reduction were observed for reducing agents that had a high reactivity towards carbon dioxide and a high content of volatile matter, and that occupied a large volume fraction. High liq'uid-state reactivities were observed for reducing agents occupying a large volume fraction and having a Iow degree of graphitization.

Jan 1, 1980

By P. J. Petit

The strategic mission of the South African mining industry is to extract the mineral assets in an energy efficient, economical and safe manner. Drilling has received particular attention in the last few years. As the operations move away from the power source, conventional and old drilling technology result in poor penetration rates, increased drilling shift lengths, slow face advances and limited stope efficiencies. The need for an alternate mining method, performed by a skilled workforce, to increase productivity, has led to the development of the electric rock drilling system for in-stope mining operations. The focus of this paper is a systematic evaluation of the electric rock drilling system as a function of production and technical parameters, in the platinum orebody. The particular electrical reticulation system is illustrated. Power usage, problems experienced, and solutions are described. The safe use of the recently developed drill is elaborated upon by describing protection devices. The testing and certification process, for approval by the recognized authorities, are documented. The testing and certification process, for approval by the recognized authorities, are documented. The human factor is also considered. Known detrimental factors of high noise exposure, vibrations levels and oil emissions are reviewed. In conclusion, recommendations on future strategies for the implementation of electric drilling technology within the mining and construction industries, is included.

Jan 1, 2006

By J. C. Coetzee

In this article, a case is made for the importance of the transfer and management of tacit knowledge to ensure continued sustainable competitive advantage within the pyrometallurgical industry in South Africa. The state of knowledge management (KM) is assessed through a theoretical and empirical study. The empirical part of the study was conducted by means of a survey questionnaire. An important prerequisite within the research entailed determining the current state of KM within the pyrometallurgical industry, and the findings are presented throughout this article. The research argues for initiatives to address the high turnover of pyrometallurgical knowledge workers. This industry needs to entrench tacit knowledge and therefore address the problems associated with the continuous loss of inherent specialized knowledge. Appropriately, emphasis is placed on identifying initiatives required to embed and retain not only human capital lost through mobility, but rather retaining tacit knowledge through a practical KM framework.

Jan 1, 2012

By A. Marek

The safe and optimal installation of roof support remains one of the biggest challenges in underground mining today. Traditional hand-held, roofbolt installation in conventional mining has been replaced, in a lot of mining operations, by mechanized equipment. This was a first step to moving the operators out of the unsafe working environment and a start on the trend toward a changed support regime in mechanized mining. However, the challenge of handling of the drill steel itself, as well as inserting resin cartridges and bolts, remains a major hazard and the cause of many lost-time injuries. The paper describes and discusses developments in this area, of mechanized bolting and on-board automation, presenting solutions to known problems, achievements to date, and future developments. The solutions presented will identify with addressing customer needs while touching on possibilities for further technology changes, keeping focus on the safety aspect for operators and the need to bring the operators even further away from the unsafe working environment. The-state-of-the-art technology in mechanized bolting equipment is presented and a brief outlook on the past, current, and future developments is given.

Jan 1, 2012

By C. Chapman, M. G. Reading, M. P. Amsden

Computer control of flotation at the Ecstall concentrator By M. P. AMSDEN, C. CHAPMAN, and M. G. READING Ecstall Mining Limited, a subsidiary of Texas Gulf Sulphur Company, operates the Kidd Creek Mine, a 10000 tons per day base metal producer, near Timmins, Ontario. Two different types of ore are mined and milled: copper-zinc and silver-lead-zinc. At the highly automated Ecstall concentrator the ores are processed by selective flotation in three individual circuits. One of the most important metallurgical tools for process control is a sample system incorporating continuous on-stream X-ray analysis. Recently this system was automated further by the addition of computer control of reagents for two copper-zinc flotation circuits. The computer programs, utilizing optimum seeking methods and smelter contract terms, have increased copper recovery by 1,1 per cent, zinc recovery by 1,4 per cent, and have reduced reagent costs by 16 per cent. Although not expected, copper and zinc concentrate grades were improved slightly as well.

By R. J. Mostert

The role of hardenability in the development of high-strength low-alloy (HSLA) steels is discussed. The applicability of the superhardenability treatment. a steel making technique for increased hardenability, to HSLA steels is indicated, and the literature on this treatment is reviewed. Several low-carbon superhardenability HSLA steels were designed by use of published superhardenability multiplying factors. It was found that the hardenability of these low-carbon steels can be increased to the same extent as that of medium-carbon steels. The mechanical properties as determined in normalized bars indicate that the superhardenability treatment can be used successfully in the production of low-carbon hot-rolled HSLA steels.

Jan 1, 1984