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By R. D. Lama

This paper presents the results of a study of the mechanics of methane gas flow in coal. Desorption tests carried out on cylindrical coal specimens showed that an analytical formulation can be made to model the process of gas flow in coal based on an integration of Darcy's law, Fick's law and Langmuir's relation. The diffusivity term in the flow equation varies directly with local gas content. Permeability tests carried out on the same coal result in permeability constants with values higher than equivalent permeabilities obtained from desorption tests by many orders of magnitude. The study also revealed that permeability is highly dependent on the applied gas pressure and the rock stress.

Jan 1, 1987

By P. van Niekerk, V. J. Solomon

Improvements in the drilling and blasting techniques used in the stopes of narrow reefs have caused the clearing of broken rock to become the major cause of delay in the achievement of a regular cyclic operation. This paper discusses the development of a scoop in accordance with a predetermined set of performance parameters. The test results obtained to date have shown that the basic objectives have been achieved within tolerable limits of variation.

Jan 1, 1979

By F. W. Petersen

For the past thirteen years, the Universities of Cape Town and Stellenbosch have hosted an annual symposium to discuss topics relevant to mineral processing. Since 1987, this Symposium has been held under the auspices of the Western Cape Branch of the South African Institute of Mining and Metallurgy, and has become one of the main events on the national conference calendar. In 1989 and 1993, the symposia took the shape of international conferences. This year the 13th Annual Mineral Processing Symposium was organized by the two universities, the Cape Technikon, and the local branch of the South African Institute of Mining and Metallurgy, and was held at the Van Riebeeck Hotel in Gordon's Bay.

Jan 1, 1994

By F. Ma, F. Yang, T. Zhao, P. Dai, Z. Shao, D. Zuo

With the development of modern digital technique, computers have been widely used to monitor and control in retrofitting traditional industries. In Chinese coal industry, some analog monitoring and control systems have been replaced by the modern computer digital systems. According to the development status of Chinese coal industry, this paper presents some technique and its applications of modern digital computer monitoring and control for safety mining production process. The technique has been used in the full digital monitoring and automation control for hoists, coal mining machines, belt transport machines, and whole coal mining production process. With the technique, it has been achieved the better economical and social benefits in safety mining production in China.

Jan 1, 2003

INTRODUCTION The SAIMM publishes technical information on various aspects of the minerals industry through several different media. (a) Monograph Series Books in the Monograph Series are high quality, detailed discussions on specialized topics. (b) Symposium Series This series consists of the proceedings of international conferences which are held in South Africa. (c) Special Publications Series This series covers titles which do not form part of the Monograph and Symposium Series. (d) The SAIMM Journal Papers published in the Journal cover al relevant areas of technical interest by striving for a balanced content and maintaining a consistently high technical standard. (e) School and Colloquia Notes The papers from al local schools and colloquia are published and handed out at registration. Should authors wish to have their papers considered for publication in the Journal, they should adhere to the guidelines outlined below.

Jan 1, 1991

By J. H. Bulloch

The paper gives an assessment of the available data on the linear elastic fracture mechanics involved in stress corrosion cracking and in the behaviour of reactor pressure-vessel materials exposed to a simulated pressurized water-reactor environment. As a result of the different experimental techniques used in the various studies mentioned, only a few detailed conclusions can be drawn. The data from constant-displacement wedge-opening loading (WOL) tests, with the exception of one study, exhibited very limited or no crack extension during exposure periods of up to 14000 hours. The data from constant-load tests indicated evidence of crack extension, but the nature and extent of the crack extension are still unclear. When crack extension did occur, it was exclusively transgranular in nature. Certain differences in the available test data are tentatively explained in terms of the experimental procedures used, and the need for a consistent code of experimental techniques is highlighted.

Jan 1, 1987

By J. P. Kirsch

This paper sets out to clearly identify all elements that make up an effective furnace feed system. These are outlined and the more common types of technology are listed. These technologies all play an important role in the final delivery of all feed materials to the furnace.

Jan 1, 2008

By A. Miller, M. Bétournay

The main objectives of the Mine Mechanisation and Automation program (MMAP) are to enhance health and safety in underground mining operations, facilitate mechanization and automation in narrow- vein and deep mines, provide sound science to regulatory agencies and improve mine profitability. The program, which has a unique underground and surface industrial scale facility, is involved in many multi-partner projects, like hydrogen fuel cell applications, electrification and hydraulification of underground mines, reduction of noise and vibration, miner location device, explosive-free blasting and hoisting. The paper presents an overview of the Mine Mechanisation and Automation Program of Natural Resources Canada and some of the main projects.

Sep 1, 2001

With the increased variability of today's large-scale mining operations, consistent flotation performance is important to improving and sustaining overall recovery through the circuit. The Newcrest Telfer Mine has implemented advanced process control technology to obtain stable level operation and consistent mass pull in the copper rougher and scavenger flotation circuits. The final result has been an overall reduction in variability, which impacts on both copper and gold recovery. This paper describes the methodology and implementation of the improvements in control at the Newcrest Telfer Mine as being an essential part of the business for minerals processing.

Jan 1, 2007

By use of a finite-difference model of an experimental galvanic cell, the effect of a resistance in the metalic conduction path on the potential and current distributions in the cell was predicted. The model predictions were compared with experimental measurements of potential profiles (measured by use of a scanning reference electrode) and galvanic currents. The predictions agreed well with the experimental measurements. Apart from this model, which is applicable in macroscopic cells (Le. with an electrolyte of low conductivity), a calculation procedure was developed to predict the effect of an external resistance on the galvanic current in a microscopic cell (high conductivity). The responses of the galvanic currents in the microscopic and macroscopic cells to changes in the external resistance were compared. From the similarity of the responses, a simple practical procedure for the evaluation of the external resistance (meter resistance) that can be tolerated is proposed.

Jan 1, 1989

By I. M. MacGregor

This paper discusses the possible use of petrological data and proximate analyses in the prediction of cutting forces for coal. It is restricted to the development of univariate predictors based on data from thirteen collieries in five major Transvaal and Orange Free State coalfields and three coal provinces. The aim of the work was the identification and development of the best predictors of mean peak cutting force and Hardgrove grindability index from among the independent variables evaluated. The data, which were obtained by use of the penetrometer developed by the Chamber of Mines Research Organization, were processed according to the SPSS computer package. The analysis revealed reasonable correlations between the Hardgrove grindability index and (1) the volatiles and vitrinite content in the Vereeniging-Sasolburg and South Rand Coalfields, (2) the contents of vitrinite, vitrinite plus exinite, and minerals plus inertinite in the Eastern Transvaal Coalfield.

Jan 1, 1985

By V. M. Lovell, N. P. Finkelstein

The concepts involved in flotation research are discussed and aims are presented. Three different method. of investigation can be used, all of which are applied at the National Institute for Metallurgy (N.I.M.), and these are the empirical, trial and error method, the chemical engineering method, and the physicochemical approachs This paper is devoted to the last of these. Because of the complexity of the physicochemical interactions involved, the work has, to a large extent, been concentrated on only one aspect, viz. the interaction between the mineral surface and reagents in solution, which was considered of major importance in the understanding of the process. The aspects on which work has been done are the concentration of uranium, the reaction between salt minerals and fatty acids, mixed xanthate-cationic collector systems, and the reaction between sulphide minerals and thiol reagents. Selected problems from the first two of these are discussed in some detail and deal with the agglomeration flotation of uranium and the chemical control of the flotation process for phoscorite. A detailed discussion is also presented of the progress made in the understanding of the interaction between sulphide minerals and thiol reagents, which is of more general application. Finally, an indication is given of the future direction of physicochemical research at the N.I.M.

By K. Grossauer, W. Schubert

For tunnelling in poor and heterogeneous ground a reliable on-site short-term prediction is required to allow a safe and economical construction. With the use of absolute displacement monitoring data and advanced software for evaluation of the data in combination with a routine update of the geological model a considerable increase in the reliability of the short-term prediction could be achieved. The paper deals with theoretical considerations, numerical studies and case histories from alpine tunnels in heterogeneous rock. Tunnelbau in schlechtem und heterogenem Gebirge erfordert auf der Baustelle eine verlaessliche Kurzzeitprognose, um ein sicheres und wirtschaftliches Bauwerk gewaehrleisten zu können. Die Verwendung von absoluten Verschiebungsmessdaten und deren Auswertung mit Hilfe von hoch entwickelten Softwareprogrammen in Kombination mit einer laufenden Aktualisierung des Gebirgsmodells ermöglicht eine erhebliche Erhöhung der Verlässlichkeit von Kurzzeitprognosen. Dieser Beitrag beschäftigt sich mit theoretischen Ansätzen, numerischen Modellen und Fallstudien von Tunnelvortrieben in heterogenem Gebirge. La construction de tunnels dans la montagne hétérogène de faible résistance exige un pronostic fiable à court terme sur le chantier, afin de pouvoir garantir un ouvrage sûr et économique. L'utilisation des données de mesure de décalage absolues et de leur évaluation à l'aide de logiciels sophistiqués en combinaison avec une mise à jour courante du modèle de la montagne permet une augmentation considérable de la fiabilité des pronostics à court terme. Cette contribution présente des approches théoriques, des modèles numériques et de cas pratiques de progressions de tunnels dans des montagnes hétérogènes.

Jan 1, 2003

By D. L. B. Pollnow

Tinplate, and electrolytic tinning at the Iscor works, Vanderbijlpark by D. L. B. POLLNOW, B.Sc. (Chem.), M.Sc. (Met.), D.Se. (France) The paper first describes tinplate as a product, dealing with its structure and its advantages to the packaging industry. It then describes Iscor's electrolytic tinning line, which is one of the largest Halogen units in the world. Details are given of the process and of the equipment used.

Jan 1, 1977

By D. E. Scheck

A computer-aided blast design consultant system has been developed. The software consists of two modules: one uses theoretical and empirical formulae and procedures to design a blast based on user supplied geological and mechanical data, while the other is an expert system that analyzes blast vibration problems and recommends remedial action using knowledge based rules. The system is currently undergoing field evaluation.

Jan 1, 1987

By C. A. Cousins

Platinoids in the Witwatersrand system C. A. Cousins. (visitor) Study of the composition, nature and mode of occurrence of platinoid minerals in the conglomerates of the Witwatersrand System leads to some interesting conclusions. Genetic evidence strongly favours a placer origin, while comparison with modern alluvial platinoids supports this view but also indicates that they are very mature alluvials. The compositional patterns and distribution of the platinoids in the Witwatersrand basin suggest the water was saline. Study of the mineralogy was greatly facilitated by the electron-probe.

By K. R. Vost

This paper reviews the theoretical methods used in South Africa for the prediction of heat pick-up and air-temperature gradients along main haulages. These methods include those of Starfield, Ramsden, McPherson, and Goch and Patterson. The differences in predictions based on typical airway conditions are explained as being due to differences in the mathematical models on which the predictions are based. The largest discrepancies were found for dry airways and for airways with bulk air coolers. The errors in predictions of the effect of machines and coolers that have been running for only a few months are calculated, and the limitations of various simplified methods are discussed.

Jan 1, 1982

By G. Whittle

An important aspect of the project evaluation process is the achievement of a clear and quantitative understanding of the primary drivers influencing project value and risk. A business scenario-based approach is required to ensure that the project meets value and risk hurdles over the short, medium and longer term. Adopting an optimising approach can aid significantly in the development of a project concept into a business that is optimal and sustainable in the longer term. Through the application of case studies, based on work performed with various mining organisations during the last five years, this paper will demonstrate how project value and robustness can be optimised. Experience has demonstrated that applying this approach results in significant value improvements and risk reduction - primarily by application of a rigorous, fact-based analysis and optimisation process that rapidly increases management team understanding and insight of key driver of value and risk.

Jan 1, 2007

By T. Puhakka

Simulation is a way to obtain quickly today future information on how planned systems will most likely behave in various selected situations. This information may then be used to optimize the system and its components and maximize the performance and output. Simulation is a way to fine-tune the layout, match the mobile fleet and optimize the schedule and the way of working to meet the desired production requirements. Simulation provides a glimpse of the upcoming operation, ‘future today’ and helps to predict its restrictions and sensitivity to various aspects. OptiMine™, the Sandvik Tamrock Corp. and CyberCube Oy developed simulation tool is designed to simulate underground rock flow and match suitable technology with various layout options. This tool can be used to view what-if situations and determine what kind of impact mastered changes have to production. The findings of critical points in the layout and working procedures at an early stage of a new mine can help to optimize the layout and material flow. OptiMine™is modular based simulation tool that combines the supplier machine knowledge and traffic guidance with mine operational know-how and mine environment. It is developed to work in a way that an effect of an individual incident, such as the effect of one additional turn in a continuous loading cycle to the daily capacity can be identified. The reported output can be used for economical impact evaluation of selected options. This paper discusses the use of simulation in general and the way the OptiMine™ simulation tool operates and how it may be used for operation, technology and material flow optimization.

Sep 1, 2001

By J. Preussner, U. Glatzel, R. Völkl, S. Prins, M. Wenderoth

Platinum base alloys are very corrosion resistant and have got a high melting point. Similar to Ni-base superalloys, which are used for jet turbines, the hardening effect of the intermetallic L12Pt3Al phase is used to receive a material that is creep resistant at high temperatures. Chromium is added to the alloy system to stabilize the L12phase down to room temperature. With the right amount of nickel the misfit and shape of the precipitates can be controlled. Various alloy compositions have been melted and analysed. With scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) a microstructure can be observed, which is very similar to the one in Ni-base superalloys. To support alloy development with simulations, a thermodynamic database of the Pt-Al-Cr-Ni system is about to be established. The SEM and EDS measurements provide useful input to the thermodynamic optimization. Also many data from the literature have been used to receive the best approximation. The Cr-Pt binary phase diagram has been reassessed and the latest results of thermodynamic modelling are presented.

Jan 1, 2006