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By R Kersten

The note describes an exercise on the simulation of the frequency and size of seismic events on the basis of the frequency distribution of the events and their inter-arrival times (Le. the frequency distribution of the time elapsed between events). From the suite of available results, those of one simulation for a period of three months are included. The tentative conclusions drawn from the exercise indicate that the overall seismic activity in an area can be predicted for a time period, that structurally complex areas will have a higher incidence of seismic events than other areas, and that the position and time of an event cannot be predicted by the use of a wide-spread system such as that used at present.

Jan 1, 1985

By J. A. L. Napier

The application of excess shear stress as an aid to the design of mine layout is reviewed, and the critical parameters required to describe slip on a plane of weakness are noted. A design procedure that is required to model the cyclic build-up of excess shear stress is described. A number of simple examples of mine layouts on two reef planes intersecting a fault plane are then considered to illustrate the application of the design concept and to highlight some of the pitfals that may be encountered

Jan 1, 1987

If you have problems or questions relating to the installation of this disc, please either telephone Document Transformation Technologies at (+27 12) 667 2074, or e-mail: nigel@doctech.co.za Si vous avez des problèmes relatifs àl?installation de ce disque, veuillez appeler Document Transformation Technologies au (+27 12) 667 2074, ou nous écrire par courrier électronique: nigel@doctech.co.za Produced by: / Produitpar:Document Transformation TechnologiesP O Box 560 ?Irene ?0062 ?South Africa.Tel: (012) 667 2074; Fax: (012) 667 2766; International Code (+27 12) e-mail: doctech@doctech.com website: http://www.doctech.co.za

Jan 1, 2004

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 In Chinese coal industry, some analog monitoring and control systems have been replaced by the modern computer digital systems.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

By J P. van Dyk

The dramatic strengthening of the rand against the dollar as well as a decline in quantity and quality of locally available concentrates have had a dramatic impact on Zincor?s operations during the previous two years. Zincor has responded with the implementation of a number of technical improvements to the process to decrease cost and increase revenue and plant flexibility. Among the initiatives is the pre-leaching and pelletising of the zinc concentrate, de-bottlenecking and process improvements in the leach and purification circuits, the introduction of cathode washing and automated cathode stacking in the cell house and the installation of a new furnace to produce pre-alloyed jumbos. This paper will describe these initiatives and others that Zincor have recently taken to stay competitive in changing global base metals market.

Jan 1, 2005

By L. C. Woollacott

Some of the factors that may influence the reliability of a consistent material balance derived from plant data were investigated, data taken from a sampling of the Iow-grade tin-flotation circuit at Rooiberg A Mine being used as the basis for the investigation. The importance of subjecting a calculated balance to a thorough analysis of its sensitivity to erors in assay and flow rate measurements is highlighted. Several simple guidelines are derived from the analysis of the Rooiberg data, and these appear to be generaly applicable to process-evaluation exercises and to the technique used for the smoothing of material balances.

Jan 1, 1987

By I. J. Barker, D. A. Vetter, G. A. Turner

The modeling of the uranium-leaching process, and the logging of data from a plant for the evaluation of the model, are reported. A phenomenological approach was adopted in the development of the model. A set of eight chemical reactions was chosen to represent the complex chemistry of the process, and kinetic expressions for these reactions were incorporated in differential equations representing mass and energy balances. These equations were coded in FORTRAN to form a program that simulated the process, and that allowed averaged and continuous data from the plant to be compared with the model. This allowed the model to be 'tuned', and to reveal a number of minor

Jan 1, 1989

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 R. Hemp

The first part of this paper describes the collection of barometric pressure measurements in a mine and their statistical analysis, which shows the effect of variations in barometric pressure, both on the primary emissions of methane gas into the workings (whether from fissures or from the surrounding strata), and on the flow of air to and from large unventilated, or poorly ventilated, areas. The second part of the paper deals with a study, based on computer simulations, of leakage flows of air into and out of sealed areas, and the reduction of such flows by the use of adequate seals.

Jan 1, 1994

It is shown that, when a flat-bottomed indentor is pressed into the surface of a strong rock, the normal force necessary to cause failure of the rock is reduced substantially if a shear force is applied to the indentor. A mathematical analysis is described, which shows that higher stresses are induced in an elastic material close to the free surface of the material ahead of a punch when a shear force together with a normal force is applied to the punch. Therefore, failure of the material would occur with lower forces applied to the punch. Stress trajectories show that fractures develop in the rock along lines of maximum principal stresses.

Jan 1, 1978

By A. J. Jager, G. R. Adams

The pattern of mining-induced fractures ahead of stope faces in deep-level gold mines, as revealed by petroscopic observations, is described. It is shown that there are zones of fractured and unfractured rock ahead of the face, which are about I m wide and continue as discrete entities for at least 12 m parallel to the face and at least 5 m vertically. These zones do not form continuously as mining progresses, but develop from time to time, leaving a solid zone between the fractured zones. The maximum depth of fracturing ahead of the face depends on the rate of energy release.

Jan 1, 1980

By J. J. Geldenhuys

Premier of the North-West Province, Mr Molefe, foreign dignitaries and guests, ladies and gentlemen. It is a pleasure and also a special honour for me to have been invited here this morning to make this address. The xv Congress of the Council of Mining and Metallurgical Institutions is, by its very nature, an extremely important event for the international minerals industry. But I believe that this specific Congress assumes an even greater significance because of the profound and far-reaching changes that have taken place in South Africa this year. These are exhilarating times, a period when so much in our country has altered and when so much has to be done so quickly to build positively on our bold political decisions.

Jan 1, 1994

By P. Maais

This paper gives an account of the development of a plant for the differential flotation of mixed sulphide ore, special reference being made to the separation of copper and zinc sulphides. The uniqueness of the geology, mineralogy, and metallurgy of each complex ore-body is stressed. Consideration is given to the scale-up of laboratory data, and to some of the factors involved in the design of milling and flotation plants for this type of ore. Process control and development are discussed, as are the human requirements for the optimum operation of a concentrator.

Jan 1, 1980

By J. Keyser

The realization of an Integrated Technical Resource Asset Management System (ITRAMS) has so far evaded all software developers in the mining industry. The major factors that have prevented the development of such a system are limitations on software, hardware and network systems. Several factors have come together at Venetia Mine, which has made the undertaking of such a project both possible and desirable. This has led to the formation of a strategic partnership between Venetia Mine and Gemcom Software International Inc. This partnership is dedicated to develop and provide an Integrated Technical Resource Asset Management System based on Microsoft Back Office architecture, Gemcom for Windows™ and the MinRas system. This paper will elaborate on the phased approach of the integration of systems into the core repository, mechanisms of integration, the functionality of the system, final results, techno-economic benefits and general project management issues.

Sep 1, 2001

By D. vas As, Constance M. Vleggaar, P. D. Toens

A facility at the National Nuclear Research Centre, Pelindaba, for the calibration of gamma survey meters used in uranium-prospecting operations by P. D. TOENS, D.Sc. (Fellow), D. van ASt, M.Sc. (Visitor), and CONSTANCE M. VLEGGAAR, B.Se. (Visitor) Ground radiometric surveys in uranium prospecting have in the past suffered from two serious shortcomings. Owing to varying instrument sensitivity and the often arbitrary height at which readings are taken, it has been impossible to compare results obtained in different surveys and, moreover, to relate such readings to actual U30s concentrations. A set of calibration sources designed to overcome these problems has recently been constructed on the site of the National Nuclear Research Centre, Pelindaba. A discussion of the standards applied and the instrument calibration procedure is presented.

This paper illustrates the application of numerical modeling methods, in conjunction with limit-equilibrium techniques, to the location of critical slip surfaces in slope-stability problems. Initially, the Spencer slice-based method of analysis is introduced, together with a dynamic-programming algorithm for slip-surface location. This limit-equilibrium method is assessed critically through the use of an illustrative problem. The technique is then extended to locate the critical slip surface for a similar slope, but with more complex constitutive and yield relationships for the material comprising the slope. To this end, the use of the stress field generated from a finite-difference program, together with a dynamic-programming search routine, is presented as an advanced technique of slope-stability analysis for engineers.

Jan 1, 1993

By R. P. King, L. C. Woollacott

To date developments in the simulation of carbon-in-pulp (CIP) adsorption circuits have focused primarily on the modeling of adsorption. This series of three papers describes a development in a direction that has received less attention, i.e. the need for a detailed description of the movement of carbon and slurry in continuous CIP and carbon-in-leach (CIL) plants. A new simulator has been developed based on the population-balance approach for modeling the movement of carbon and slurry. Existing adsorption and leaching models are evaluated in this paper in order to establish which are appropriate for use in the new simulator. The details of the simulator are given in Part 2 of this series.

Jan 1, 1990

By J. A. Wates

The paper examines the consequences of dam building with slime of high water content, and therefore Iow relative density, such as the tailings usually associated with the extraction of uranium. It shows how a Iow relative density reduces the practical maximum rate of rise, and hence the establishment cost, of slimes dams built by conventional means. Further hidden costs of such tailings dams are examined. It is concluded that dewatering of tailings before their disposal is the most cost-effective means of increasing the rate at which a particular dam can be constructed, or of reducing operating or stability problems on existing dams. In the longer term, underground disposal seems to be a feasible alternative. However, it is pointed out that there are other factors that can compound the operating difficulties, and that these should be investigated before remedial steps are taken.

Jan 1, 1983

By M. U. Özbay

A series of blasting experiments was carried out in an up-dip stope of a gold mine using short-perioddelay electric detonators. The main object of the investigation was to show the interactive effects of short-delay blasting. The delay range over which observations were made was restricted to between 10 and 200 ms. To quantify the blast results, data were collected on fragmentation, throw, position of muckpile, and ground vibration. For comparative purposes, blasting parameters for conventional pyrotechnic sequential firing were also measured. The paper describes the most relevant parts of the study and gives the experimental results. The interactive effects of short-delay blasting are analysed, and some aspects of the breaking mechanism are discussed.

Jan 1, 1985

By H. M. Friede

An experimental study of iron-smelting techniques used in the South African Iron Age by H. M. FRIEDE, Ph.D. and R. H. STEEL (Visitors) The main factors involved in the primitive smelting of iron (ore, charcoal, temperature, air supply, process control) were evaluated in an experimental furnace that was constructed to the pattern of an Iron Age furnace found at Melville Koppies Nature Reserve, Johannesburg. In particular, the characteristics, action, and efficiency of skin bellows were investigated to gaina better understanding of the air-supply system used. Sixteen specimens of iron ore, slag, and metallic iron (excavated material and material produced in the experimental furnace) were submitted to analysis. The results of the analyses are reported and discussed.

Jan 6, 1977