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The finite element method of stress analysis is nowadays widely used in the fields of mining, mechanical and civil engineering. This paper presents a short description of the three-dimensional method, in which the elements used are arbitrary hexahedrons. Two examples of the application of the method are presented, namely, calculation of the elastic stress distributions in a coal pillar and in an opencast mine.

By C. M. Sellars, W. E. Stumpf

SYNOPSIS The effects of concurrent recovery, prior creep deformation and concurrent high temperature fatigue on the coarsening of some carbides in steels have been studied. It was found that concurrent recovery enhances the coarsening rate by orders of magnitude and prior creep deformation causes an enhancement of about two times. Finally, concurrent fatigue causes an initial greatly enhanced coarsening rate but after prolonged cycling dissolution of the carbides occurs.

By P. S. Turner

After a brief account of the differences between the control of underground fires and those on the surface, the paper describes the analogue detection system used on the mines of the Anglo American Corporation of South Africa Limited. The system comprises Spanair gas analysers, Becon combustion-particle detectors, a telemetering system, a surface signal-recording and-processing system, and an alarm system. The use of the system is described and illustrated.

Jan 1, 1982

By C. A. Hunt

The problem of materials balancing is reviewed with particular reference to the minerals industry. A broad statistical framework is established that, besides extending the classical estimation problem, allows questions concerning the value of sample information to be addressed. The following are examples of such questions: How much money should be spent on sampling? Which streams in a plant should be sampled? What should be sampled? The approach adopted makes use of Bayesian analysis. The discussion includes an illustrative example involving a simple flotation circuit.

Jan 1, 1985

By L. S. Belyayeva, A. S. Chumak, N. N. Boyko, A. V. Bondarenko

Analysis of results of many years concerned study of the fire hazard parameters of the material of the mine conveyor belts come in for use at the mines of the Ukraine in 1984-2002 that was carried out in the laboratories of the Scientific-Research Institute of Mine-Rescue Work is adduced in the paper. The basic tendencies on raising the fire safety of the conveyor belts that are retraced in their world production are shown.

Jan 1, 2003

By J. P. Hoffman, A. S. M. de Jesus

Additions of boron have been found to increase the hot workability of stainless steels. Boron forms complex chromium-iron borides, primarily at grain boundaries but also on delta-ferite stringers. This paper describes how a nuclear technique based on the track-etch method was used to distinguish between borides and chromium carbides on grain boundaries and to investigate the distribution of boron in stainless steels. The method was found to be sensitive for boron, and made it possible for boron precipitates to be identified on grain boundaries and interphase boundaries.

Jan 1, 1989

By W. A. Te Riele

The National Institute for Metallurgy was the venue for a one-day colloquium on 'The Chemistry of Processes for the Recovery of Gold on Activated Carbon'. Organized by the South African Chemical Institute (Southern Transvaal Section) in collaboration with the National Institute for Metallurgy (NIM) and the South African Institute of Mining and Metallurgy, the colloquium attracted tremendous interest from the mining industry. Some 300 metallurgists, engineers, and chemists were brought up to date on advances in this technology made by scientists of NIM and the Anglo American Research Laboratories (AARL).

Jan 1, 1980

By M. J. Nicol, G. Cromberge

An account is given of the development of a relatively simple model that describes the kinetics of the absorption of gold cyanide on activated carbon. The model is based on the treatment of the carbon solution interface as a homogeneous boundary across which gold is transported at a rate determined by the rate of mass transport to and from the interface. Rate equations derived from this model describe the results of various kinetic experiments under continuous or batch conditions in the laboratory and on operating pilot and full-scale plants.

Jan 1, 1983

By R. J. E. Stewart

Another very successful evening meeting was organized by the Johannesburg Branch of The South African Institute of Mining and Metallurgy on 20th November, 1990, when Mr R.D. MacPherson, General Manager of Richards Bay Minerals, gave a presentation on the Richards Bay operations. The function was held in the Ballroom of the Johannesburg Country Club, and the very high attendance (some 250 people) was indeed a reflection of the high profile of the subject mater. It was also a fitting reward for the efforts of Mr MacPherson and his team, who spent a considerable amount of time and effort traveling the country to present 'the other side of the story'.

Jan 1, 1991

By C. Pohlandt

A literature survey of methods suitable for the determination of cyanides in process streams and effluents is presented. Of the large number of methods published, 92 are examined in detail, emphasis being placed on the selectivity of the methods, i.e. the extent to which they enable one to distinguish between ionic cyanide and metal-cyanide complexes. Methods designed for the determination of 'total cyanide' (i.e. ionic cyanide as well as coordinated cyanide) are evaluated critically. Other aspects of the methods are also considered, such as sensitivity, accuracy, speed, and freedom from interferences.

Jan 1, 1983

By Adams. M. D.

Most of the cyanide lost in carbon-In-pulp plants is due to the reaction of cyanide with base metals and sulphides during leaching. Some cyanide is also lost in the adsorption tanks as a result of oxidative and adsorption reactions with the activated carbon. The high rates of cyanide loss in the elution and electrowinning stages are atributable to hydrolytic decomposition and anodic oxidation, respectively. However, the relative amount of cyanide lost during these two stages is small for a given amount of ore treated.

Jan 1, 1990

By A. N. Brown

Rock breakage by drilling and blasting is fundamental to every hard-rock mining operation. The subject was an apt choice for a mining school because many technological changes have taken place since the subject was last presented some ten years ago. However, because of the development of surface mining, it was decided that two schools should be held: one for underground mining, and the other for surface mining. The School on Underground Mining was held at the University of the Witwatersrand in February 1986.Copper 87 COPPER 87 is an international conference organized by metallurgical and academic institutions of two of the largest producers of copper in the world, Chile and Canada.

Jan 1, 1986

By N. O. Lotter

Evaluation errors and value frequency distribution models of the gold ore bodies in the Witwatersrand and Free State systems are reviewed. It is found that the low-grade sections of the data are prone to the largest evaluation errors, and that an understanding of the shape of the value frequency distribution is essential to the calculation of mean grade. The evaluation of a mineral process for a particular ore requires attention to mil-feed sampling, sample processing, and monitoring. In particular, the calculation of a representative mass of mill-feed sample (Ms) should take account of size-by-size value variance. Alternative Ms models are discussed.

Jan 1, 1995

By W. O. Ortlepp

This note considers the most fundamental concepts of support design for deep underground openings and discusses them briefly in the context of tabular stoping and deep hard-rock tunnelling. It concludes that the conventional re-bar, mesh, and lacing methods that have been widely used in deep gold mines are quite inappropriate for the support of highly stressed tunnels. The following is suggested as the criterion for adequate dynamic support: the energy absorbed by a support unit (yielding through some acceptable limited displacement) should exceed the kinetic energy generated by the mass of rock that is intended to be retained by that unit.

Jan 1, 1995

By J. C. Vreugdenburg, W. A. H. Poppmeier

An overview of methods of manufacture is presented, as well as the results of laboratory experiments on the making of stainless clad steels. , It is concluded that stainless clad steel can be made in South Africa with existing rolling equipment, and that good bonding between the two materials depends on clean mating surfaces, proper edge welding, and a minimum reduction of 25 per cent at a rolling temperature of 120O"C. In practice, a minimum reduction of 70 per cent at 1100cC is recommended. : Suggested applications for clad steel include parts and equipment for the chemical, petrochemical, marine engineering, and mining industries, for the building sector, and for household appliances.

Jan 1, 1991

By S. W. Evans, G. Pienaar

Weldable steel plate with a good combination of strength and toughness is currently produced from 0,12 to 0,28 per cent carbon low-alloy steel heat-treated by roller quenching and tempering. Alternatively, steel plate of the same strength can be produced at a lower production cost by the use of very-low-carbon steel (0,03 to 0,08 per cent carbon) processed by in-line quenching without tempering. This paper reports the results of experimental work on these steels, and compares them with the properties of conventional steel. On thinner sections, it was found that the properties of the experimental steels compare favourably with those of conventional grades.

Jan 1, 1989

By A. Smith

After the introduction of mechanized bord-and-pillar development at Dumacol in 1958, pillars were being developed at a much faster rate than they could be extracted by hand loading methods. Efforts were therefore made to increase the rate of pillar extraction by mechanization. Following two partially successful mechanized stooping trials in 1964 and 1971, it was decided that mechanized pillar extraction with 1 m3 cable-reel front-end loaders should be introduced. The first section to employ the new equipment started production in May 1979, and the mine now has four mechanized pillarextraction sections in operation. Considerable improvements in production, productivity, safety, and percentage extraction have been achieved.

Jan 1, 1985

By A. P. Van Wyk, G. Pirnaar

The effect of vanadium on the susceptibilities of chromium and chromium-nickel steels to reversible temper embritlement was evaluated. The steels investigated were approximately equivalent to steels of as 970 Grade 708A42 and as 970 Grade 817M40, the major difference being that molybdenum had been replaced by vanadium in various concentrations. It was found that the vanadium had a detrimental effect and, in al the concentrations tested, enhanced the susceptibility to reversible temper embritlement of both the chromium and the chromium-nickel steel. The detrimental role played by vanadium in reversible temper embritlement is explained by a consideration of the effect of vanadium carbide, as well as of free vanadium, in solid solution in ferrite.

Jan 1, 1987

By M. Timucin

High-temperature phase relations in the Pb-PbS system were established by the quenching of samples equilibrated in evacuated and sealed silica capsules. The liquid-miscibility gap seen in some previously published phase diagrams was not observed. The thermodynamic activities of PbS in liquid solutions of this system were derived at 1473 K from the isopiestic equilibration of samples belonging to this solution series with Cu2S-PbS melts of known PbS activities. The behaviour of Pb-PbS melts was found to be compatible with a subregular solution model. This model also made it possible to obtain an analytical liquidus for PbS that was in excelent agreement with the experimental determination.

Jan 1, 1988

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