Search Documents

By B. K. Loveday

A model for the leaching of non-porous particles by B. K. LOVEDAY*, Ph.D. (Fellow) A model has been developed for the prediction of the rate of leaching for an assemblage of non-porous particles in terms of size-distribution parameters. Expressions are developed for batch and continuous operation, and an example of the application of the model is given.

Jan 9, 1975

By A. D. Thomas, K. C. Wilson

Some years ago, the authors developed an analysis of non-Newtonian pipe flow based on enhanced turbulent microscale and associated sub-layer thickening. This analysis, which can be used for various rheologic modelling equations, has in the past been applied to smooth-walled pipes. The present paper extends the analysis to rough walls, using the popular Bingham plastic equation as a representative rheological behaviour in order to prepare friction-factor plots for comparison with measured results. The conditions for laminar-turbulent transition for both smooth and rough walls are also considered, and comparisons are made with earlier correlations and with experimental data.

Jan 1, 2007

By J. N. Van der Merwe

The South African coal-mining industry uses a uniform safety-factor formula for non-squat pillars, incorporating a coal-strength constant that was derived empirically by Salamon and Munro in the 1960s. The constant is 7,2 MPa. Since that time, collapses of pillars at relatively high safety factors have occurred in the Vaal Basin. Analysis of the post-1960s' collapses indicated that the strength constant for the Vaal Basin is 4,5 MPa. A crude method for the prediction of the minimum life span of pillars in the Vaal Basin is presented.

Jan 1, 1993

By P. M. Scott

The South African Institute of Mining and Metallurgy held a colloquium on 'The Selection of Equipment for Underground Mining' in Johannesburg on 22nd September, 1982, which, judged by the interest shown, was an unqualified success. Mintek 50 As announced earlier, the Council for Mineral Technology (Mintek) will be celebrating fifty years of growth in 1984 and is organizing an international conference, MINTEK 50, on its areas of special expertise. Drilling Once again the South African Drilling Association will be holding a technical symposium in 1983. ILAFA Congresses The Instituto Latinoamericano del Fierro y el Acero (ILAFA) has scheduled the following congresses for 1983:

Jan 1, 1983

By N. C. Joughin

Potential for the mechanization of stoping in gold mines by N. C. JOUGHIN B.Sc. Eng., Ph.D. (Rand) (Member) The basic requirements for stoping machines are identified first by examination of the mining rates and productivities attained in conventional stoping, and then by examination of a series of problem areas associated with the shape of the reefs, rockbreaking, rockhandling, and the support and design of the machines. Some of the more important machines being developed are described briefly, and their principal features are compared with the basic requirements identified in the first part of the paper. An estimate of the potential demand for the different types of machines is given.

Jan 1, 1976

By J. D. Wells

An account is given of the planning required for the rehabilitation of land that is to be disturbed by opencast mining, and of the preparation of rehabilitation of land that is to the Inspector of Mines. The plans Include the provisions that are to be made to allow for climatic conditions, land use, vegetation and wildlife, surface-water resources, geology and ground water, soils, land capability, rehabilitation method, location of discard dumps and slurry ponds, pollution control, and costs. . . Monitoring of the operation is the only way that the rehabilitation plan can be improved, and both monitoring and planning are essential when provision is being made for the closure of a mine.

Jan 1, 1986

By J. H. Lazarus

The evolution of backfill-distribution systems for deep gold mines is examined. The status of current technology for the design of backfill-distribution systems is considered with reference to pipeline pressure gradients, pipeline wear rates, and slurry flow regimes. The effect of an increase in the relative density of the slurry on the performance of backfill-distribution systems is illustrated. Future trends regarding the design of backfill-distribution systems are discussed.

Jan 1, 1993

By L. G. Austin

The paper summarizes the current state of development of simulation models for SAG and FAG mills, and gives the results of recent investigations of the physical processes occurring in autogenous grinding. The breakage process is treated as the sum of three regions of breakage actions: normal breakage caused by nipping of particles between media (steel balls or pebbles); abnormal breakage caused by media when the particle or lump is too big in relation to the media to be readily nipped; and self-breakage resulting from the chip¬ping fracture and abrasion of the tumbling action of rock lumps. Each region of breakage action has associated specific rates of breakage and primary progeny fragment distributions. A simplified form of the model was used to predict the performance of an 8 m diameter SAG mill with L/D = 0.5 grinding a copper ore, and predicted maximum capacity and minimum kWh/ton at about 6% ball load at 25% total filling. Two FAG mills of L/D = 2 were necessary to give the same capacity, and the simulations indicated a lower kWh/ton for these mills. For this ore, both systems were technically feasible.

Jan 1, 1987

By B. Mulcahy, M. Valenta

"The purpose of executing a project in a stagewise fashion is to evaluate all potential options in a cost-effective manner and develop an understanding of the project drivers, thereby minimizing overall project risk to the client. Among the more valuable tools for this exercise are production and financial models that can be used to quantify the sensitivity of the project to the critical parameters.The mine and concentrator used in this case study are located on the Kalahari Copper Belt, which extends from Zambia through northern Botswana into Namibia. This area of Africa has seen very little industrial development and the project will create much-needed employment and development in the region.The success of this project thus far can be attributed to the close cooperation between the geological, mining, and metallurgical disciplines. Regular updates of projected capital and operating cost estimates coupled with project outputs guided the teams in optimizing their various discipline models, ultimately delivering a compelling argument for the execution of the project. Key to the success was the development of a geometallurgical model for the prediction of concentrate tonnage, grade, and recovery for the life of the mine from the mining plan.This paper summarizes the metallurgical findings and the outcome of the various project stages. The development of the model is discussed, as are the challenges faced in developing a suitable metallurgical process route. IntroductionThe Kalahari Copper BeltThe Kalahari Copperbelt, which extends from Zambia across northwest Botswana into Namibia, is considered to be a broad time equivalent of the Central African Copperbelt, with a similar style of mineralization. However, at shallower depths (<25 m), chrysocolla and malachite exist in significant proportions in certain geological areas. As illustrated in Figure 1, the project is located in the Ghanzi-Chobe Fold Belt which forms part of the Kalahari Copper Belt. The Ghanzi Group, which overlies the lowest stratigraphic unit (the Kwebe Formation), consists of three formations, namely the Ngwako Pan, the D’Kar, and the Mamuno Formation (Hall, 2012)."

Jan 1, 2016

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 &apos;tuned&apos;, and to reveal a number of minor

Jan 1, 1989

By F. P. A. Robinson, C. R. Thomas

Stress-corrosion studies on materials used for surgical implants * by C. R. THOMAS and F. P. A. ROBINSON Samples of Vitallium (a cobalt-chromium alloy), 316L stainless steel, and titanium T318 were subjected to the boiling magnesium chloride test so thattheir susceptibility to stress-corrosion cracking could be determined, and their behaviour under service conditions was then assessed. Stress-corrosion cracking was confined to the stainless-steel samples, while gross pitting was detected in the samples of forged Vitallium. It was concluded that the use of stainless steel should be avoided for long-term surgical implants. Surface imperfections on the stainless steel are generally the cause of pitting, from which stress-corrosion cracks are sometimes propagated.

Jan 11, 1976

By J. A. L. Napier

An essential requirement for the planning of the global capacity of a mine is a knowledge of the functional relationship between the production level and the capital expenditure necessary to establish that level. An underlying mechanism connecting capital expenditure and mine production capacity is proposed in terms of a characteristic profile of the expenditure that both precedes and succeeds production expansion. By the assignment of a representative shape to this profile, the capital expenditure of individual mines can be modelled. The empirical values describing the characteristic profile are computed for a number of gold mines, and an attempt is made to explain variations in the model coefficients from mine to mine in terms of physical parameters such as shaft depth, shaft concentration, and average rate of depth increase during the life of the mine.

Jan 1, 1981

[Council for 1993/94 President Dr H. Scott-Russell President Elect J. A. Cruise Vice Presidents Senior D. A. J. Ross-Watt Junior P. D. K. Robinson]

Jan 1, 1994

Council for 1998/99 President R.P. Mohring President Elect J.R. Dixon Vice Presidents Senior junior M.H. Rogers Dr L.A. Cramer Immediate Past President Honorary Treasurer Dr N.A. Barcza J.A. Cruise

Jan 1, 1985

COUNCIL FOR 1989/90 President Dr O.K.H. Steffen President-elect Mr H.G. Mosenthal Senior R.D. Beck Vice Presidents Junior ].P. Hoffman Immediate Past President C.E. Fivaz Honorary Treasurer Dr H. Wagner

Jan 1, 1990

COUNCIL FOR 1987/88 President B.C. Alberts President-elect C.E. Fivaz Vice Presidents Senior Junior Dr O.K.H. Steffen H.G. Mosenthal Immediate Past President Dr H. Wagner Honorary Treasurer Dr H. Wagner

Jan 1, 1988

COUNCIL FOR 1988/89 President C.E. Fivaz President-elect Dr O.K.H. Steffen Senior H.G. Mosenthal Vice Presidents Junior R.D. Beck Immediate Past President B.C. Alberts Honorary Treasurer Dr H. Wagner

Jan 1, 1989

COUNCIL FOR 1990/91 President H.G. Mosenthal President Elect RD. Beck Senior J.P. Hoffman Vice Presidents Junior Or H. Scott-Russell Immediate Past President Or O.K.H. Steffen Honorary Treasurer OrH. Wagner

Jan 1, 1991

Council for 1995/96 President D.A. J. Ross-Watt President Elect Dr N.A. Barcza Vice Presidents Senior R.P. Mohring Immediate Past President J.A. Cruise Junior J.R. Dixon Honorary Treasurer J.A. Cruise

Jan 1, 1996

[Council for 1993/94 President Dr H. Scott-Russell President Elect J.A. Cruise Vice Presidents Senior D.A.J. Ross-Watt Junior P.D.K. Robinson Immediate Past President J.P. Hoffman Honorary Treasurer J.A. Cruise]

Jan 1, 1994