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By R. M. Lamya

A semi-empirical kinetic model was developed for the atmospheric leaching of a Ni-Cu matte in copper sulphate-sulphuric acid solution. Kinetics of the leaching process was studied as a function of initial copper ion concentration, initial acid concentration, temperature, stirring rate and particle size distribution. The kinetic model was developed on the basis of the leaching mechanism and chemical reactions of the leaching system investigated, and was evaluated by comparing the model predictions to experimental data. The model was found to satisfactorily fit the trends in the leaching of the metals, namely copper, nickel, cobalt and iron.

Jan 1, 2009

By Alan Bauer

SYNOPSIS A discussion is presented of the advances that have been made in rotary drilling in recent years and it is indicated how and why these drills have replaced percussive equipment even in the hardest formations at larger than 7 in. diameter. A method is presented showing how it is possible to estimate drill requirements and how to optimize drilling and blasting costs for a particular situation. To do this it is necessary to have, in addition to drill performance data, a knowledge of comparative explosive performance. Current methods of doing this are therefore critically appraised. As hole diameters have increased for overall drilling and blasting economies the question of fragmentation arises. In North America this has been approached on a try-it-and-see basis giving results that, in general, have been very satisfactory. The current drilling and blasting practices in North America are reviewed and reference made to the factors of importance in slope control.

By L. H. W. Walker

As part of an overall design of a computer based mining managerial system, the geological and mineral estates management disciplines find themselves centrally placed in terms of producing fundamental data both before and during the mining operation. Computerisation of all aspects of these fields of endeavour has come to be seen as essential for complete integration with other mining orientated disciplines. Release 1 .l. of the Anglo American system of mineral estates management has been tested and is in the process of being implemented at several Anglo American Gold Division mines.

Jan 1, 1987

By M. Andersson, R. Elsrud

The quality and the production rate for the mining operations in the Garpenberg mine has been much improved due to a new system, that presents the latest exploratory and planning data for the driller at the moment he deploys the drill rig at the face. Other components in this improvement work are better planning procedure, large-scale production system with longer rounds and introduction of new drill rigs in the mine. The new Rig Control System (RCS) for the new series Atlas Copco Boomers L2C has made it possible to develop this system for production drilling in the Garpenberg mine. The ABC Regular has been extended with map navigation and drill plan generator. The driller will have the best estimate of the orebody in front of him and the best drill plan for that orebody. The customer’s specific system will also become a standard Atlas Copco product for the Boomer ABC drill rig family.

Sep 1, 2001

It is a great honour to officiate at the celebration of the centenary of the South African Institute of Mining and Metalurgy. Tonight's festivities bring back happy memories of my association with South Africa's mining industry during my tenure of office as Minister of Mineral and Energy Affairs. They also remind me of the illustrious personalities who have preceded me on this podium. The Pioneers They include Sir Percy Fitzpatrick, who spoke in 1909 on the eve of the Union, General Smuts, and, on many occasions during the 1920s and 1930, Jan H. Hofmeyr. The basic issues addressed by them continue to enjoy the Institute's attention today, namely the optimal and safe exploitation of our country's mineral resources and cost-effective extraction of minerals from their ores. Translated into the Institute's key objective it reads: To initiate and give effect to the means whereby the requirements for technology and scientific knowledge if the minerals and metals section if the South African economy is satisfied.

Jan 1, 1994

By L. Cornish, P. A. Olubambi, J. H. Potgieter

Four 22%Cr series duplex stainless steels alloys containing varying nickel contents of approximately 5, 7, 9 and 13% were melted in a vacuum induction furnace, hot rolled, solution annealed and water quenched. Their corrosion behaviour was investigated in sulphuric acid and sodium chloride solutions using a potentiodynamic polarization technique. Increasing nickel contents have appreciable influence on their corrosion behaviour. Polarization curves show similarities in the uniform corrosion behaviour of the alloys in the solutions and a significant difference in their pitting behaviour in chloride environments. Alloy 2209 generally exhibited highest resistance to uniform corrosion while 2213 displayed distinct and best pitting corrosion resistance. Their corrosion behaviour were attributed to the influence of nickel on phase modification, microstructural refinement, and the probably types of films formed in different environments. Keywords: Duplex stainless steel; Nickel; Microstructure; Phase modification; Corrosion

Jan 1, 2006

By E. H. R. Schümann, H. Wagner

SYNOPSIS The paper gives a detailed overview of the history of subsidence engineering on South African collieries. Surface displacements resulting from total-seam extraction are discussed, and the important role of local geology is highlighted. It is shown that the differences in subsidence behaviour between South African and European collieries can be attributed to the presence of competent strata in the overburden of South African coal seams. Criteria are given for the prediction of the most important subsidence parameters, and a new model for the simulation of surface subsidence above total-extraction panels is introduced. The final section of the paper deals with the damage to surface structures caused by total-seam extraction. A brief summary of the most important undermining experiments on South African collieries is given, and it is concluded that local experiences of damage compare with those in Europe.

Jan 1, 1991

By W. T. Ruhmer

Slimes-dam construction in the gold mines of the Anglo American Group by w. T. RUHMER. Pr.Eng.. B.Sc. Eng. (Met.) (Fellow) Current practices generally in accordance with the principles of design and operation of slimes dams within the Gold Mining Division of the Anglo American Corporation are described. Although many of the details given are either obvious or have been amply dealt with elsewhere, these have been included for the sake of completeness. The selection of suitable ground for the deposition of slimes, the initial design and construction of a slimes dam, and its consequent operation are presented in logical sequence. Emphasis is placed on the code of practice for the construction of slimes dams issued by the Chamber of Mines of South Africa, and draft regulations (Water Act of 1956) dealing with pollution. Operating costs are included, and possible future trends are discussed.

Jan 2, 1974

By J. R. de Wet

The behaviour of mild steel in aqueous cyanide solutions similar to caustic cyanide elution solutions was investigated at high temperature in electrochemical experiments. The anodic polarization diagrams of mild steel indicated that steel may undergo active dissolution under these conditions. The rare occurrence of gold plating in practice is the result of the limiting of the anodic dissolution of the steel by the presence of a passive layer on the steel. This passive layer is stable only in a certain potential range, and the free corrosion potential attained determines whether the steel will be passive or active. For conditions typical of elution columns, several corrosion potentials are possible, depending primarily on the initial condition of the steel and the concentration of oxygen in the solution. If these conditions result in the formation of a passive layer on the steel, changes in concentration and temperature will not necessarily result in plating since the layer may exist in a metastable form.

Jan 1, 1993

By R F. Sandenbergh, Y Wei

The flotation separation of the Rosh Pinah ore into lead and zinc concentrates are based on the selective flotation of the lead containing minerals followed by the activation and recovery of the zinc sulfides. In the present work the influence of the composition of the water on the selective flotation of the lead containing minerals is reviewed and the results given of the laboratory investigation of the influence of activating species such as silver, lead and copper, on the selective recovery of lead minerals from the Rosh Pinah ore. It was found that it was difficult to prevent the activation of the sphalerite by the metal species in solution in the absence of cyanide, and that colloidal precipitates most probably also serves as a significant carrier of these activators in the flotation circuit. Removal of heavy metal species from the solution by means of an adsorbent is possible, but most probably not practical.

Jan 1, 2007

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 K. I. Afewu, L. C. Woollacott

The design of in-pulp adsorption vessels in the gold industry has, for the most part, been seen as a problem involving the suspension of fine particles o ore in a slurry. The need for the vessel to be designed as a mass-transfer contactor has received insufficient attention. The current series of papers addresses this need The previous paper considered the question of the scale dependence of the film transfer coefficient. This paper examines the mixing considerations that are relevant. A review of the literature and an examination of a limited set of data provide some insight into the mixing conditions needed for the dispersion of the particles of adsorbent. The mixing requirements for the suspension of the ore particles are also considered, and conclusions are drawn in regard to the design of mechanically agitated vessels for gold in-pulp adsorption circuits.

Jan 1, 1995

By D. S. Loubser

The technique of backfilling in the gold mining industry is dependent on the dewatering of slurry to form a solid support system. In many cases flocculants are added to the slurry to increase the rate of dewatering. To ensure that a stable support is obtained it is important that the chemistry, application and limitations of these flocculant additives are understood. Flocculant additives have to be added at a point where minimum shear will occur. (Shear occurs when a flocculant is exposed to excess energy resulting in breakdown, of the floc.) To ensure that optimum results are obtained it is important that personnel involved are trained to use the flocculant additives and dosing equipment correctly.

Jan 1, 1988

By Y. Zhen, N. Topliffe, G. Shou

The typical service life for a long distance slurry pipeline is15 to 25 years. Determination of wear rate for a pipeline could have a high economic impact on the pipeline project. Wear is a combination of chemical corrosion and mechanical abrasion. The contribution of each factor has to be determined project by project. Normally, chemical corrosion dominates the pipe wear in fine slurry pipelines. These pipelines have been designed with a velocity between 1.5 m/s and 2.5 m/s. Solids are suspended with high homogeneity across the pipeline section. Bottom wear is not much greater than the top wear and not sensitive to velocity. The wear pattern in the pipeline transporting medium coarse solids, such as milled ore and tailings, is different. Wear concentrates on the bottom of pipeline and the outer bends, and is more sensitive to flow velocity. Wear distribution along the pipelines is similar.

Jan 1, 2007

By H. M. Friede

Notes on the composition of pre- European copper and copper-alloy artefacts from the Transvaal by H. M. Friede. Ph.D. (Visitor) Seven copper artefacts (five ingots and two ornaments) found at prehistoric sites in the Transvaal were submitted to analysis. All the artefacts showed a high copper content and a relatively Iow level of impurities. A little-known ingot type from the Limpopo Valley ('nail' ingot) is described, and its analysis is given. The analysis of two copper ornaments that come from sites dated to the 5th Century AD. and the 11th Century AD. showed the constancy of the composition of copper articles over long periods. The well-known 'Blaauwberg Ingot' was re-analysed, and the results showed that this ingot cannot be regarded as a true bronze. Analytical values for the composition of three brass artefacts from Bambandyanalo (Mapungubwe), Northern Transvaal, are given. Some aspects of pre-European bronze manufacture and brass smelting, and of early metal trade from the East Coast into the interior of South Africa, are discussed.

Jan 2, 1975

By A. L. Bleloch, A. M. Starfield

This paper is concerned with heat flow in the plane of a typical cross-section of a deep underground airway. A new algorithm, called the quasi-steady method, is presented for the calculation of rock temperatures in that plane. The algorithm is used in the computation of heat and moisture transfer rates from the rock to the ventilating air for an airway that is wet on part of its circumference and dry elsewhere. The speed and accuracy of the new method are demonstrated on a microcomputer, and it is argued that this method offers a considerably more versatile and physically meaningful alternative to previous methods for the prediction of increases in air temperature along mine airways. The algorithm is also used to explore the concept of a uniformly wet airway that is equivalent to a partly wet airway in terms of its effect on the ventilating air. The concept is shown to be reasonable, but more complex than one might have anticipated. Finally, several useful extensions and applications of the new method are suggested.

Jan 1, 1983

In a gold CIP/CIL circuit, adding new circuit water to a final tails thickener and then directing the thickener overflow to the head of the circuit significantly reduces the cyanide concentration at the TSF discharge spigot. The new water is used to dilute the final tails. The dilution and recycle of the tails in this manner may have the added benefit of reducing reagent consumption, in some cases to the point where the reagent savings justify the expenditure and Cyanide Code compliance is achieved at no extra cost. Potential circuit configurations and water recycles can be modelled by splicing a flowsheeting and thermodynamics package, such that changes to the composition of the water can be reduced to chemical speciation with a Gibbs free energy minimisation enabling a complete understanding of the circuit water chemistry.

Jan 1, 2007

By Nareetsile S., J. Kabwe

In the past few years Orapa and Letlhakane Mines have investigated various new technologies to enhance and improve production. The goal has been to improve productivity, reduce operating costs and make the mines more profitable The advent of Global Positioning Systems (GPS) in the early ’80s brought about the realization of this concept. Orapa and Letlhakane Mines started using GPS in 1999 and it is now used atLetlhakane mine for surveying, vehicle tracking and dispatching and for floor control system. Orapa Mine uses GPS in surveying, floor control and drill navigation. It will also be used for vehicle tracking and dispatching in mid-2001 following the installation of a fleet management and control system. The introduction of GPS at both Orapa and Letlhakane mines have improved productivity and reduced operating costs in the areas of drilling, topographic survey and floor control. In vehicle tracking and dispatching GPS has allowed for real-time information management for timeous decision-making which optimized fleet run time hours.

Sep 1, 2001

By Y. G. Che, M. Brown, R. L. Gandhi, M. D. Watson

Slurry pipelines have proven to be an economical method of mineral concentrate transport over long distances. Some of these pipelines are internally lined with high-density polyethylene (HDPE) to avoid internal corrosion. HDPE is an inert and extremely smooth material, and it was believed hat scale deposits would not form on it. However, there have been instances of scaling on HDPE lined pipes. Scale problems have also occurred on bare steel pipes. In this paper experience with scale problems in some of these pipelines will be summarized. Alternatives available for control of scale problems will be discussed, and a success story for the control of scale problems in the 300 km long Century zinc and lead slurry pipeline will be presented.

Jan 1, 2007

By T. N. Moore, E. M. De Souza

This paper details a study conducted in Canada on the use of a drill with two different types of elastomer-covered handles in place of the standard steel handles. One type of handle was covered with a relatively stiff elastomer with a durometer of 70 (referred to as the plastic handle), and the other was covered with a more compliant elastomer with a durometer of 56 (refered to as the rubber handle). It was found that, compared with the steel handle, the overall acceleration at the interface between the plastic handle and the drill operator's hand was 2,5 times less, and that between the rubber handle and his hand was 3 times less. This reduction occurred predominantly in the frequency range above 500 Hz, and was greater with increasing frequency. However, an analysis based on the methodology of an international standard (which places greater importance on low-frequency vibration), indicated that the reduction in vibration levels was minimal. ~he driller himself felt that operation with the plastic and rubber handles was more comfortable, the rubber handle being preferred.

Jan 1, 1991