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By G. J. McDougall, M. J. Nicol, O. L. Wellington, R. G. Copperthwaites, R. D. Hancock

X-ray photoelectron spectroscopy showed that the adsorption of gold cyanide on carbon in the presence or absence of electrolytes and acids proceeds by the same mechanism. Although the identity of the gold cyanide adsorbate is not known, the mechanism appears to have an initial adsorption stage that involves the adsorption of an ion pair: Mn+[Au(CN)-2]n where Mn+ is a metal ion (for example Na+, K+ and Ca2+) that has a lower solubility than the Au(CN)-2 anion in the adsorption medium, followed by a reduction step in which either a sub-stoichiometric Au(CN)x surface species or a cluster-type compound of gold is formed.

Jan 1, 1980

Now a new generation of computerized drill rigs has been launched and they are based on modern standard PC-computer technology. The rigs have been well embraced by the market and more than 100 units have left the assembly line. The new generation has taken a quantum leap forward with respect to drilling accuracy, logging capabilities, reduction of manpower in some types and serviceability compared to the previous generation of drill rigs. The Can bus technology, well proven in the automobile products, is the backbone in the new generation control system of Atlas Copco. The short-term development is now focused on establishing this new automation platform on other product lines of Atlas Copco products. The long-term objectives is to offer the mining industry Atlas Copco products with one common automation platform. Essential for Atlas Copcois to contribute to the work with the on-going Data Exchange standard between mining machines and mining computer systems (IREDES). Our belief is that an accepted standard will make mine automation programs affordable for a wider base of the mining industry, because of the possibilities to a cost effective integration of different equipment with a minimum of system integration problems and machine specific interfaces.

Sep 1, 2001

By R. J. Dippenaar, W. H. Van Niekerk

The relationships between coal properties, the strength of coke, and the performance of a blast furnace were investigated by means of correlation studies, and a linear programming model was developed for the prediction of a coal blend based on these relationships. The unique feature of this approach is that it utilizes a knowledge of the minimum blast-furnace coke requirements, rather than the maximum attainable coke quality. The model predicts the least expensive coal blend that would still comply with the minimum coke-quality requirements of blast furnace. The study also confirms the existence of a relationship between the rank and caking parameters of coal, and the hot strength of coke. The effect of coke-oven operating parameters on coke quality is also discussed.

Jan 1, 1991

By J. Svoboda, W. J. C. Venter, R. N. Guest

The use of gravity or magnetic separation followed by upgrading on a shaking table recovered about 25 per cent of the copper and lead minerals, at a combined metal grade of 20 per cent, from the final flotation tailing at the Tsumeb Mine. Magnetic separation recovered the copper minerals more efficiently than the lead minerals; it also recovered finer particles more efficiently than standard gravity separators. However, the grade of the concentrate produced by magnetic separation was not of sufficiently high grade, and further upgrading by gravity separation was necessary. It was decided to install an 'all-gravity' plant, which would have the added advantage of acting as a monitor or 'policeman' on a plant that receives a fairly variable feed.

Jan 1, 1988

By A. Kijko, C. W. Funk

Methods for the analysis of seismic hazards in mines are reviewed as illustrations of the techniques that are being used in some South African mines. The classical parameters that describe a hazard are the seismic activity rate, ?, the Gutenberg-Richter value, b, and, occasionally, the maximum regional magnitude, mmax The activity rate is calculated readily owing to the inherent simplicity of its definition. The evaluation method presented for the Gutenberg-Richter b value takes into account the presence of mmax Three statistical procedures are described for the assessment of mmax which the maximum observed magnitude, Xmax a crucial role. Often, the configuration of mine seismic networks is changed, or the networks are improved, which inevitably gives rise to changes in the completeness of the seismic catalogues. The routine analysis of seismic hazards must account for these time dependent changes. A method for the evaluation of hazards is reviewed that accommodates varying levels of quality in the catalogues. Finally, the concept of the volume of ground motion (VGM) is presented. This is a technique that allows for most aspects of seismic hazards in mines. The advantage of the VGM is that a hazard can be described by one physically significant value: the volume of rock (cumulated over a time period) in which the ground motion exceeds some critical particle velocity. Data from the gold mining region in South Africa known as the Far West Rand is used in a demonstration of the discussed methods of hazard analysis.

Jan 1, 1994

By J. Gilliland

The Grootegeluk coal-beneficiation plant was erected in the Waterberg coalfield, near Ellisras in the Transvaal, to supply Iscor's steelworks with a predetermined tonnage of coking coal in accordance with strict quality requirements. This plant has to handle a high tonnage of raw coal, which is not easy to beneficiate, in order to produce 1,82 X IQ6t of coal. Extensive tests were conducted on borehole cores and a mass sample of coal obtained from the area. These tests were carried out on a laboratory and pilot-plant scale, and were aimed at the establishment of the most effective beneficiation methods and the choice of suitable equipment. This led to the completion of a full set of design and manufacturing drawings that resulted in the project approach . described in this paper.

Jan 1, 1982

By A. Fouchee, N. Naudé, K. Schommarz

"This article presents laboratory test work conducted on an African haematite ore to determine the influence of the flotation pulp pH on the final iron grade and recovery. Results show that a combination of an isodecyl ether propylene amine/amino acetate and 1,3-propanediamine, N-(3-(C10-C16-alkyloxy)propyl)-derivatives collector is suitable for separating haematite from quartz. Higher iron grades were obtained at pH levels between neutral and pH 9. This underlines the importance of the surface charge effect of the ore on its flotation characteristics. The results serve as good baseline conditions for further optimization. IntroductionBeneficiation of iron ore by flotation is widely used in Brazil, India and China. In Africa, however, this practice is not yet commercially developed.The aim of this test work is to serve as a starting point by establishing suitable pH conditions for the development of a practically implementable reagent suite, which will then be included in a larger beneficiation circuit for producing high-grade iron ore sinter feed.In the literature, African iron ore types are graded as low-grade (60.0–62.9% Fe; 8.6– 12.5% SiO2 and insolubles), high-grade (66.0– 69.9% Fe; 0.8–4.5% SiO2 and insolubles), and meduim-grade as the remaining portion (Astrup et al., 1998). The low-grade ore used in this work contains less than 60% Fe.For Brazilian ores consisting of a combination of haematite and quartz, it is common to use corn starch as a depressant and ether amine blends as collectors with additional frothing characteristic (Araujo et al., 2005). Work by Turrer and Peres (2010) shows the possibility of using other depressants successfully as well.The main mechanism of the reverse flotation of quartz from iron ore is based on the electrostatic theory of flotation. This is due to the strong pH dependence of the zeta potential of the mineral edge planes on silicate particles (Fuerstenau and Pradip. 2005)."

Jan 1, 2016

By G. P. Dyke

The MRMR Classification System was developed specifically for mining applications, namely caving operations, and is one of three rock mass classification systems used in the South African mining industry today. Increased usage of the MRMR Classification System has raised concerns that it does not adequately address the role played by discontinuities, veins and cemented joints in a jointed rock mass. To address these concerns, Laubscher and Jakubec introduced the In-Situ Rock Mass Classification System (IRMR) in the year 2000. Although the IRMR System is more applicable to a jointed rock mass than the MRMR System, a quantitative comparison of the MRMR and IRMR Classification Systems indicates that there is not a significant difference between the resultant rock mass rating values derived from the two Classification Systems.

Jan 1, 2008

Past work on the ignition of methane-air mixtures by coal-cutting picks is reviewed, with special reference to the factors that contribute to ignitions and ways of reducing them. The main conclusions obtained from this review are outlined for the following aspects: mechanisms of ignition, methane concentrations, and the roles of rock types, cutting parameters, cutting tools, and water. However, many of these factors have been investigated on a qualitative, rather than on a quantitative, basis. A considerable amount of effort over a long period has been expended in this area of research. It is shown that a number of the factors influencing ignitions by machine picks have been researched adequately, but that there is still work to be done. Research is continuing in this area, being concentrated primarily upon the ignition potential of the coal-cutting pick.

Jan 1, 1985

By P. R. Jochens, D. D. Howat, A. A. Hejja

The effect of the reactivity of lime on desulphurization efficiency in the basic oxygen furnace A. A. HEJJA, Dipl. Ing. (Budapest) (Visitor) D. D. HOWAT, B.Sc. (Glas.), Ph. D., F.I.M. (Fellow) P. R. JOCHENS, Pr.Eng., M.Sc. (Eng.) Rand, Ph.D., A.I.M. (Member) The iron charged to the basic oxygen furnace at the steel plant of Highveld Steel and Vanadium Corporation has a relatively high sulphur content. Considerable emphasis is therefore placed on the reactivity of the lime. An investigation of the lime used at the steel plant showed that its reactivity had deteriorated considerably both during transport from the supplier (Northern Lime Company) and during storage and handling at the steel plant. The deterioration on the steel plant is the more severe, and is due to hydration and carbonation. Rapid deterioration is a characteristic of highly reactive lime when exposed to the atmosphere. Plant tests showed that the desulphurization efficiency decreases with a decrease in the reactivity of the lime. The addition of slag rich in manganous oxide to the furnace considerably improved the efficiency of desulphurization that can be achieved with limes of lower reactivity and with lime that has deteriorated. A decrease in particle size of lime of lower reactivity greatly increased the desulphurization efficiency. Less lime of higher reactivity is required for the same degree of desulphurization to be achieved. Lime of higher reactivity gives rise to slags with lower ferrous oxide contents and hence the steel yield is increased.

By G. Peinaar

Superhardening is a new development by which a substantial increase in hardenability above the normal can be achieved in Iow-alloy steels. This paper concerns the reversible temper-embrittlement behaviour of steels with a superhardenability characteristic. Steels of type BS 530A40 with manganese modifications varying from 0,72 to 1,27 per cent in the superhardenable and conventional condition were compared. It was concluded that superhardenability in itself does not affect the susceptibility of a particular steel to temper embrittlement. However, an increase in manganese content, which was intended to increase the base hardenability of the steel, caused serious deterioration of the temper-embrittlement properties. As the use of manganese, chromium, and nickel to increase base hardenability results in an increase in susceptibility to temper embrittlement, it is suggested that this effect should be countered by the addition of 0,2 to 0,3 per cent molybdenum.

Jan 1, 1984

By M. Splaine, W. Davidson, D. C. Atkinson

Since 1964, Nchanga Consolidated Copper Mines, Ltd., has been developing and using production scheduling methods for optimizing its metallurgical operations in the short term (up to one year). Medium-range metallurgical planning has been possible only by successive evaluations of a single-year LP. A modified version of Rosenbrock's direct search technique has now been developed to allow multi-year optimization of both mining and metallurgy for medium-range planning. The modifications to the search technique have produced a marked increase in computational efficiency for this heavily constrained problem in many variables and the system is a usable planning tool, given a reasonably powerful computer. The plans are 'optimum' in the sense that they yield the maximum present value of the operations. Each of the resulting five-yearly mine plans forms the basis for further detailed metallurgical evaluation by the established production scheduling system.

By A. W. Bryson, J. D. le Roux, B. D. Young

Several rate models for the adsorption of gold cyanide from aqueous solution onto activated carbon are given in the literature. The purpose of this study is to critically examine their ability to simulate the adsorption process over a wide range of conditions. An account is given of a comprehensive set of experimental work on the kinetics of gold adsorption onto a coconut shell- based activated carbon. Equilibrium isotherms were also determined. It is concluded that the homogeneous surface-diffusion model fits the experimental data reasonably well and provides a good balance between simplicity and descriptive accuracy. The model contains two parameters: the extra-particle mass-transfer coefficient and an effective intraparticle surface-diffusion coefficient. Both can be evaluated readily from simple adsorption experiments.

Jan 1, 1991

By Franz E. Pawlek

Synopsis This is a summary of investigations in the field of pressure leaching carried out at the Institute for Extractive Metallurgy of the Technical University of Berlin-West during the last seven years. The efficient dispersion of gas in a liquid and its dissolutions as well as the events at the phase boundary when leaching ZnS are reported. At the end two examples are given for the use of pressure leaching in the processing of smelter by-products. INTRODUCTION About 20 years ago, experiments were independently started in Canada and in Berlin on the subject of dissolving sulfidic ores without preliminary treatment by means of leaching under increased oxygen pressure. In Canada ammoniacal solutions were mainly employed, and F. A. Forward and his co-workers were successful in applying this process on a large industrial scale1, 2. This process is used in Fort Saskatchewan to produce about 15,000 tons of Ni per year. In Berlin, investigations were started on leaching with acid solutions3, 4. This process had also been used on a large industrial scale in the D.S.A., but the choice of unfavourable working conditions led to great difficulties, and to giving up this process for industrial use. Later on in Berlin work was carried out especially on the kinetics of pressure leaching 5, 6, 7, 8, 9 and its applications to the processing of smelter by-products, in particular of mattes and speisses10, 11, 12, 13, 14. The dissolution of ores and by-products can be subdivided into four steps: 1. the efficient dispersion of the gas, so that its dissolution occurs over as great a surface area as possible, since only the dissolved oxygen reacts with the solid, 2. the suspension of the solid, so that the entire surface can take part in the reaction, 3. the phase boundary reaction, 4. the removal of the reaction products. The first two steps belong to the field of process engineering and will be discussed from this point of view. The aim of these experiments15 was to find out first of all the limits of efficiency of self-sucking stirrers in solutions of low viscosity with regard to the mass transfer. In addition, the effect of ultrasonics in the same reaction system was studied. The experiments were carried out in a lucite container as shown in Fig. 1. Four baffles of 0.1 d width were in the stirring vessel. The height of these baffles was adjustable. For every experiment one litre of liquid was used. An infinitely variable direct current motor, which was fixed with a hollow shaft, served as the driving power for the stirrer.

1. New books Specialty steels and hard materials, edited by N. R. Comins and J. B. Clark. Oxford, Pergamon, 1983.482 pp. Hardcover £55.50. Papers presented at an international conference on advances in flow measurement techniques, edited by H. S. Stephens and B. Jarvis. BHRA Fluid Engineering (Cranfield, Bedford, MK43 OAJ, England), 1982. £36. Papers presented at Fourth European Conference on Mixing, edited by H. S. Stephens and D. Goodes. BHRA Fluid Engineering (Cranfield, Bedford, MK43 OAJ, England), 1982. £36. Papers presented at an international conference on hydrocyclones, edited by H. S. Stephens and G. Priestley. BHRA Fluid Engineering (Cranfield, Bedford, MK43, OAJ, England), 1982. 248 pp. £27. Controlled atmospheres for heat treatment, by R. Nemenyi. Oxford, Pergamon, 1983. 225 pp. Hardcover 20, flexicover £7.50. Electrochemical techniques in corrosion testing and research, edited by J. S. Scully. Oxford, Pergamon, 1983. 150 pp. Flexicover £9.45 2. Book reviews Off highway truck haulage, by the Newman Combined Group. Parkvine (Victoria), Australasian Institute of Mining and Metanurgy, 1982. Reviewer: B. J. Vorster Elsevier's mineral and rock table, compiled by P. Lof. Reviewer: A. Wedepohl Field geologists' manual, by B. A. Berkman. Monograph Series No. 9, Australasian Institute of Mining and Metanurgy, 1982.295 pp. Reviewer: R. A. G. Cuipers 3. Mintek reports Report M56 A computer programme for the evaluation of process routes in the production of ferrochromium. Report M61 An atomic-absorption programme for the Apple 11 Plus computer. Report M63 A general-purpose data logger. Report M65 A preliminary survey of the corrosivity of water in gold mines. Report M66 A review of corrosion inhibitors: theory and practice. Report M67 The determination of total cyanide in solutions containing uranium and gold. Report M68 The suitability of Doppler flowmeters for use in the minerals-processing industry. Report M70 The preparation and certification of two reference materials of South African manganese ore. Report M78 A n evaluation of the Leeds laboratory-scale flotation cell. Report M79 The determination, by X-ray-fluorescence spectrometry, of gold and uranium on resin. Report M80 The installation and commissioning of a Siemens SRS200 sequential X-ray-fluorescence spectrometer. Report M81 The application of the inductively coupled plasma system to the simultaneous determination of precious metals. Open-pit and strip mines The South African Institute of Mining and Metallurgy and the Mining Alumni Society of the University of Pretoria are organizing an International Conference on The Planning and Operation of Open Pit and Strip Mines in Pretoria from 9th to 13th April, 1984. Other Institutes co-sponsoring the Conference are The Canadian Institute of Mining and Metallurgy, The Institution of Mining and Metallurgy, and The Society of Mining Engineers of AIME.

Jan 1, 1983

By V. Korobko, M. Byantogtokh, N. Byambadorzh, V. Bysov

A three-stage operative planning of mining operations in ore opencasts is considered. The hierarchy of monthly-weekly, weekly-daily, daily-shift planning is offered. For the fastest elimination and deviations in problematic situations a level is analysed and weekly-daily or monthly-weekly operative plans are being constantly updated. Operative planning is formulated on information received of preparation and working of mining panels. The electronic maps of these panels are considered for automated operative planning. On the data of the registration of blasthole drillings on a panel, the position of blasthole entry, their depth and the number of a line are determined. The geologist specifies boundaries of ore grades by the bored silt. The qualitative characteristics of ores are determined by the chemical analysis of slime or magnetic logging of blastholes. The missing geologic information is obtained by interpolation on the data of detailed and operational explorations. During working of the mining panel the technologists mark the movement of shovels, associating this movement to blastholes. For this purpose technological attributes are used: when was the blasthole drilled, what drill-rig participated in drilling, what shovel was used and when was it worked? Around each blasthole the zone of its influence is built up. It represents a discrete, elementary volume of ore or waste. The discrete form of the data is most convenient, as it allows step-by-step methods to be employed of the scheduled tasks in many and various combinations. The account panel working technology avoids ‘combination’ explosions. The elementary blocks should be placed in a trajectory of shovel movement and the trajectory can not be arbitrary. It’s determined by the technological rules of extracting and loading of mine mass. In linking to blastholes, the trajectory of shovels is simulated by the sum of step-by-step moving from one elementary block to another. For this purpose a geometrical linkage of blastholes is used. At a railway haulage, or complete mining with truck haulage, the trajectory of movement is a shuttle along the front of operations in the panel. At a selective mining of ores the number of possible directions is limited to three: moving of a shovel by idle running along the front of operations in the panel, frontal pull all the way down of the panel, and withdrawal. The technologically acceptable trajectories of shovel movement are stored for the following estimation and selection of the best. The estimation is carried out on mathematical models with criteria on the method of the least squares of deviations based on preset parameters from the plan, uniform loading of shovels, and mixing of ore at unloading points. The equations of balance type and directive parameters of the plan, as well as technological restrictions of solid and of elementary blocks within the limits of a trajectory are the restrictions of the model. Depending on an industrial situation it is possible to choose one of the predetermined models. The presented technique is used for longitudinal shovel bench at the Erdenet ore-dressing company.

Jan 1, 2003

P.W.D. ROSTER OF CONSULTING ENGINEERS (Extract from a letter from the Secretary for Public Works) In recent years a large number of professional engineers has entered the consulting field. Although the names of most of these have been placed on the Department's roster of consulting engineers either as a result of representations made by the South African Association of Consulting Engineers or by applying direct to the Department there are still some who seem to think that canvassing through an influential person is necessary to obtain commissions from the Department. The Department's roster is open to all registered professional engineers who are suitably experienced to undertake consulting work and commissions are awarded strictly on merit. I shall appreciate it, therefore, if registered professional engineers who wish to be considered for commissions by the Department could be advised that they must apply, in the first instance, to be placed on the Department's roster. On receipt of such an application a questionnaire listing all the information required by the Department will be forwarded to the applicants for completion and returning to the Department for record purposes. All names which appear on the roster are taken into account when a commission has to be awarded, due consideration being given to factors such as geographical position, seniority, capability and compatibility. AMERICAN SOCIETY OF MINING ENGINEERS 1970 FALL MEETING AND EXHIBIT The Secretary for Commerce has passed to us a letter received from the American Society of Mining Engineers, reading as follows: "We would be delighted to have South Africa attend our meeting next year and to exhibit some of their mining equipment in our Technological Information Exchange. The 1970 SME Fall Meeting and Exhibit will be held in St. Louis, Mo., October 21-23, 1970, at the Kiel Auditorium. The AIME WorId Conference on Lead & Zinc Mining and Metallurgy will be an integral part of our meeting-and an added incentive to attend. It should be understood that we discourage the showing of actual mining equipment and encourage the manufacturers and suppliers to send their engineers to man the booths. We hope that the exhibits will endeavour to put across their story by means of photographs, drawings, models and literature, rather than by display of prototypes of the actual equipment. We will be happy to welcome manufacturerers from South Africa as well as the mining engineers who, from time to time, have registered at our meetings." For further particulars, interested parties may write to the Society of Mining Engineers, 345 East 47th Street, New York, N.Y. 10077, D.S.A.

By C. L. E. Swartz, I. J. Barker, J. H. Schubert

A dynamic simulator of the leaching and adsorption cascades of a gold plant was developed and used to compare the effect of various disturbances on the overall efficiency of the plant. These comparisons show which disturbances most critically need to be controlled to optimize plant performance. The simulator was based on an existing gold plant. Dynamic and steady-state data were collected on the plant and were used in the modeling of the process. Simple dual-rate models are used to describe the leaching and adsorption processes. Mole-balances of various species take into account the changes of concentrations in the leach, and also the movement of pulp and carbon up and down the adsorption cascade. Fluctuations in the flow rate, density, and cyanide concentration of the feed to the leach have a negative effect on the efficiency of the leach, while carbon attrition was found to be an important factor in decreasing the efficiency of the carbon-in-pulp (GIP) section. Badly regulated transfers contribute towards the decreased efficiency of the GIP section, but overflows and carbon leakage have only a limited long-term effect. Various carbon profiles and transfer schemes were studied, and the results indicated that a slightly heavier loading at the bottom of the cascade is beneficial, while the type of transfer is relatively unimportant.

Jan 1, 1993

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

OFS Branch Minutes of the General Meeting Held at the President Steyn G.M. Ltd Canteen on Wednesday, 13th November, 1974, at 3.55 p.m. Mr D. A. Smith (Chairman of the O.F.S. Branch) was in the Chair. There were also present: Nim reports Report no. 1696 The preparation and certification of a reference sample of a preciousmetalore. Report no. 1705 The effects of various matrix elements on the efficiency of the fire-assay procedure using nickel sulphide as the collector. Report no. 1720 The initial development of processes for the direct leaching of iron-nickelcopper mattes containing platinumgroup metals, and for the production of ferronickel.

Jan 5, 1975