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By El-Sayed M. Sherif, J. D. Comins, Erasmus R. M.

Corrosion of copper in aerated acidic chloride pickling (0.5 M HCl) solutions and its inhibition by 3-amino-1,2,4-triazole-5-thiol (ATT) have been investigated using electrochemical techniques and weight-loss measurements, along with Raman spectroscopy. Electrochemical measurements for copper after varied immersion periods of 0, 24 and 48h showed that the presence of ATT and the increase of its concentration significantly decrease cathodic, anodic, corrosion (jCorr) currents and corrosion rates (KCorr), as well as the dissolution currents at 300 mV vs. Ag/AgCl, while increase polarization resistance (Rp), degree of surface coverage (?) and inhibition efficiency (IE%) to a great extent. Weight-loss measurements after different immersion periods of 6 ~ 48h revealed that the dissolution of copper decreased to a minimum and the corresponding IE% increased with ATT concentration increases. The detection of ATT molecules on the copper surface by Raman spectroscopy indicated that inhibition of copper corrosion is achieved by strong adsorption of ATT molecules onto the copper surface. Aerated acidic pickling solutions; 3-Amino-1,2,4-triazole-5-thiol; Copper corrosion; Corrosion inhibition; Raman spectroscopy

Jan 1, 2006

By P. Geldenhuys, D. J. C. Taylor, D. C. Page

This paper gives a technical review of the history, occurrence, mining, and metallurgy of iron in South Africa. The reserves of iron ore worldwide and in South Africa are reviewed, and potential new developments In the iron-and-steel industry in South Africa are examined. The paper concludes that the exploitation of lower-grade iron deposits will probably supplement the reserves of high-grade hematite ore in the distant future, and that, accepting this scenario. South Africa will be well placed to provide iron ore for its expected internal steel requirements, as well as supplying quality Iron ore for the export market.

Jan 1, 1988

By S. Venter, W. E. Stumpf

Some of the factors that govern the choice of a nuclear fuel are briefly discussed, special reference being made to the introduction of advanced carbide fuels into fast-breeder programmes. One of these factors, i.e. the compatibility of carbide fuels with stainless-steel cladding, is discussed in depth. A very sensitive technique for the study of compatibility interactions between fuel and cladding is described in respect to the effects of particle size, specific surface area and surface oxidation of the fuel,and microstructure of the cladding on the compatibility behaviour of the cladding with the fuels. Finally, the need for the development of modified or stabilized uranium carbide fuels is discussed, and some results are presented to show the effects of small amounts of sulphur in these fuels on their compatibility with stainless-steel cladding materials.

Jan 1, 1979

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

By A. C. Legg

BCL Limited operates a nickel-copper flash smelting operation at Selebi-Phikwe, situated in north-eastern Botswana. The original furnace was commissioned in 1973 and produces a high grade sulphide matte, from its own concentrates plus additional custom feeds, which is shipped to refineries in Zimbabwe and Norway for further processing. In 2004 the company embarked on a study to modernize the flash smelting complex, with an emphasis on extending campaign life, improving the furnace integrity and enhancing throughput and process efficiency. First phase initiatives from this exercise, including the fundamental switch to a single concentrate burner operation of the flash smelting furnace, were implemented in July 2007. This paper summarizes experiences prior to implementation, details the specific improvements made to the flash smelting furnace and associated operations, highlights the improved plant performance after modernization, and outlines second phase expansion plans that are currently under consideration.

Jan 1, 2009

By M. D. G. Salamon

In view of an urgent need for a simple means of simulating the behaviour of stratified rock masses, a long-dormant linear model is revived, generalized, and discussed in some depth. The model is piecewise homogeneous, consisting of a pile of homogeneous isotropic laminae in which the interfaces between beds are parallel and free of shear stresses and cohesion. The continuity of stresses and normal displacements is assured across the bedding planes and, to maintain simplicity, the theory of thin plates is used as the kernel of the model. The paper covers the case where the rock mass consists of discrete beds in which the layers are arranged either heterogeneously or systematically. The stratification is regarded as uniform when all the layers are of the same thickness and their Young's modulus changes exponentially with depth; and as homogeneous when all the laminae have identical thickness and properties. The case of uniform stratification is also treated on the basis of an equivalent quasi-continuum derived from the basic model. Attention is focused on the derivation of influence functions. It is demonstrated that the quasi-continuous models, when they are available, can replace their distinct-layer counterparts. The homogeneous quasi-continuum, which permits the derivation of its influence functions in closed form, facilitates the determination of the roof and floor convergence. In the case of a significant class of problems, the convergence distribution is defined by a second-order differential equation in the xy plane, which simplifies to a Poisson's equation if the mining excavations are unsupported. With this result, the paper prepares for the solution of a host of practical problems. These solutions are presented in a series of papers that are in the course of publication.

Jan 1, 1991

By A. B. Holland-Batt

The application of Reichert spirals and cone concentrators within the South African mineral industry is discussed, and the procedures used in the acquisition of design data are outlined. Computing techniques developed by Mineral Deposits Limited for the processing of test data for use in the design of production circuits are described.

Jan 1, 1982

By J. C. David, G. Coetzer

The effect of varying aliphatic, olefinic, and aromatic groups in the N- and S-positions of dithiocarbamates was investigated in the selective and bulk flotation of a mixed copper-lead-zinc-iron ore. Selective and bulk flotation were found to be dependent on the type of functional group, as well as on the position of substitution.

Jan 1, 1989

The 91st Annual General Meeting of The South African Institute of Mining and Metallurgy was held at Kelvin House, Johannesburg, on 17th August, 1988. Mr B.c. Alberts (President) was in the Chair, and declared the meeting open at 16hOO. Obituaries The President announced the deaths of the following members of the Institute:

Jan 1, 1988

By C. Hey

The cycloned gravitated tailings backfill system, also referred to as a soft or low density fill, has been implemented at Vaal Reefs. Inhibiting the success of the system was the problem of shrinkage after placement. The problem was overcome by a pressure fill technique which eliminated settlement, contained costs and allowed remote placement. The technique involves the preinstallation of disposable pipes which are filled cyclically until a residual pressure of 0,5 bar of active support is generated in the filled paddock.

Jan 1, 1988

By R. T. Rudd

The impact of slimes-dam formation on water quality and pollution by R. T. RUDD*, B.Sc., AMI (S.A.) CE (Visitor) This paper discusses the mechanics of pollution by slimes dams in the gold- and fluorspar-mining industry, as well as that caused by coal dumps and slurry dams. The effect of coal mining on two typical rivers in Natal is shown and the implications discussed. The implications and trends of sulphates pollution on the Rand Water Barrage in the Vaal River are discussed. The spread of pollutants (sulphates and fluorides) from the Reef and elsewhere, and the impact on urban use and agriculture downstream of the barrage, are illustrated. Conclusions and future policy are outlined.

Jan 12, 1973

By J. D. Flint

A description is given of the extraction of pillars in a seam of coal which normally varies in thickness from 10 feet to 14 feet using conventional trackless mechanised units. By using the pocket and fender method of pillar extraction, the high capital cost of hydraulic supports is eliminated, and a volumetric extraction of 85% to 90% of the seam of coal is possible. This method of mining opens up the possibility of extracting vast tonnages of coal which hitherto would have been left in situ as pillars. The major benefits likely to accrue from this technique are seen as follows: 1. Greater volumetric extraction of the seam; 2. Longer panel life with less frequent transferring of sections; 3. Preservation of our natural resources. The authors deal with the history of this development at Springfield Colliery, discuss the present results and outline the future trends in the light of current experience.

By R. H. Steel

Ingot casting and wire drawing In Iron Age Southern Africa by R. H. STEEL (Visitor) This paper describes the experiments that were conducted in 1974/1975 on two related aspects of Iron Age copper technology in Southern Africa: ingot casting and wire drawing. Three types of ingot were successfully cast: the St Andrew's Cross ingot, the marale ingot, and the musuku. It is suggested that the 'studs' on the musuku are not the remains of broken-off rods as previously proposed by other investigators, but that the ridged pattern is an ornamental feature. Copper wire was successfully drawn with similar tools and according to the procedures described in the literature on African Iron Age wire drawing. It is concluded that these accounts are generally accurate and that the pre-European metal workers are worthy of respect for the results they achieved with primitive methods.

Jan 11, 1975

By R. J. Davidson, N. Schoeman

SYNOPSIS The paper describes each of the stages in a carbon-in-pulp (CIP) or carbon-in-leach (CIL) plant, and details the steps that can be taken to achieve effective carbon management by referring to practices at the Daggafontein CIP plant. This approach was adopted because of the difficulty in summarizing current carbon management in the many varying operations in South Africa, Daggafontein being chosen as a high-tonnage dedicated well-run plant of recent design. Because of the major role played by the consumption of carbon in the operating costs of CIP and CIL plants, an attempt is made to develop a series of indexes based on quality parameters and price that can be used as a guide In the selection of carbon.

Jan 1, 1991

By B. Z. Weiss, N. R. Comins, F. Blum

Some aspects of the mechanical behaviour of chromium-containing dual-phase 3CR12 steel were investigated as a function of the temperature and strain rate. The yield stress was found to depend on both the temperature and the strain rate, with no substantial differences between the longitudinal and the transverse directions. The strain-rate sensitivity decreased with increasing temperature. The yield stress could be presented as a function of a temperature-strain-rate parameter. Impact test results showed substantial differences between the energy absorption of the transverse and longitudinal specimens above the ductile-brittle transition temperature. Changes in energy absorption with temperature were gradual for specimens in both orientations, and the transition from ductile to brittle behaviour occurred between 373 and 173 K. Strain rates ahead of the tip of notches with different geometries were calculated and measured experimentally.

Jan 1, 1990

By Z. T. Bieniawski

Estimating the strength of rock materials by Z. T. BIENIAWSKI, Pr.Eng., D.Sc.(Eng.) (Visitor) A practical approach for estimating the strength behaviour of rock materials is presented. The demand for data on rock properties in engineering design is considered, and it is shown that, based on the trends observed in the South African mining industry during the last twenty years, simple and easy-touse methods for the estimation of the uniaxial and triaxial strength of rock materials are needed. It is shown that the uniaxial compressive strength of rock can be conveniently determined from the pointload strength index, which is obtained underground on unprepared rock cores. The triaxial strength of rock can be estimated for most practical purposes from empirical strength criteria. Two such criteria are proposed that allow estimation of the triaxial strength for rock materials to about 10 per cent. The only input required for these criteria is the uniaxial compressive strength. The validity of the practical approach outlined in this paper is confirmed from the experimental tests conducted on some 700 rock specimens representing five rock types. A practical example for the prediction of rock strength is given.

Jan 3, 1974

Contribution by W.D. Ortlepp? The authors are to be commended for publishing their interesting view of an aspect of deep-level mining technology that is becoming increasingly topical and vitally important. This is the second paper in the journal within four months to deal with the crucial needs of highly stressed tunnel construction, the other being the paper on the design and testing of rockburst support in the February 1994 issue. Both papers re-examine important innovative ideas that are more than a quarter of a century old, but that have not yet been implemented by the industry. It is to be hoped that they will now, taken together, serve as a new starting point for a definitive examination of what constitutes proper tunnel-support design. There can be no question that the need to develop a design approach that will solve the problems of tunnelling at depths of 4000 m or more has now become crucial. Contribution by A.M.J. Vervoort* Although the overall paper is very interesting and the future research (comparison between numerical simulations and underground measurements) will be very challenging, I would like to make some remarks regarding the set-up of the numerical model and the interpretation of the elastic results.

Jan 1, 1995

By P. R. Jochens

SYNOPSIS This review article first highlights the past performance of the industry and discusses the manner in which the development of the industry has followed a logical progression from mining to the production of mineral and metal products of specification purity. Then the numerous constraints against a greater contribution by the industry are enumerated. Attention is drawn to the extent of further processing that can be undertaken in the context of mining and metallurgical processing, not only to indicate the benefits that can be derived from the added-value conferred on a mineral or metal commodity during each stage of its further processing, but also to point out some important corollaries of further processing. The many opportunities and challenges for an increased contribution by the minerals and metals industry are then reviewed. This major section includes a list of commodities for which increased penetration of export markets could be sought because the increasing resistance level (a term developed in this paper) has not been attained; a list of commodities that are imported at present, many of which could be produced locally on the basis of identified resources and expertise; a list of commodities for which additional uses should be developed so that South Africa, which possesses the largest reserves and is the largest exporter, can increase its production rate; and examples of commodities for which further processing is still at an early stag*..

Jan 1, 1985

By R. J. Davidson

The chemistry related to the adsorption of gold, uranium, and transition-metal ions onto algal biomass (activated carbon) is related to the genesis of the Witwatersrand. Detrital gold being washed into the early basin, together with cyanide generated in the atmosphere, would have solubilized as the stable aurocyanide complex, the necessary oxygen being produced from the photosynthesis of carbon dioxide by primitive algae. Pebble-type conglomerates, while providing for the free movement of solutions containing the vital nutrients for prolific algal growth, would have screened of the sunlight, which would otherwise have degraded any free cyanide in solution. With the subsequent decomposition of the algal deposits, it is surmised that carbon-rich layers having adsorptive properties similar to those of activated carbon formed in the conglomerates. Under these conditions, gold (silver) in solution would have been adsorbed selectively as the cyanide complex, together with uranium as the carbonate complex. Any transition-metal ions present would also have been adsorbed onto such a substrate. The subsequent burial and compression of the gold-rich conglomerate with temperatures rising to about 400DC would then have reduced the adsorbed gold to the metal in a single segregated gold-silver metal phase (95 to 99 per cent of the contained gold), while leaving behind a sulphide phase rich in iron, base metals, and arsenic and containing some gold and silver. The recrystalization of this later phase may explain the presence of the rather consistent contents of secondary pyrite in the Witwatersrand conglomerates. Similarly, uranium minerals, some rich in titanium and carbon, may also have formed. An adsorption model would explain the very consistent trends in the gold-to-silver ratios of individual reefs in the Witwatersrand, which suggest an extensive hydrothermal system approaching isothermal equilibrium. Also, as gold grades increase, so silver grades generally decrease, indicating the sequential displacement of silver by gold as classically obtained with activated carbon.

Jan 1, 1990

By S. A. Forrest, B. Clarke

Trends in PGM demand?The conference paper will cover a concise analysis of demand trends, which will include the major PGM end-use sectors (autocatalysis, jewellery, glass, petroleum, nitric acid, medical/dental) and will touch on the investment sector. Reference will be made to environmental legislation affecting global emission standards, trends in PGM loadings and the substitutability of platinum and palladium in this end-use sector. Observations will also be made on the jewellery sector, and the development of Chinese and Japanese demand. Trends in primary and secondary PGM supply?Similarly the paper will summarize historic and current global mine supply and primary production trends for PGMs, referencing recent expansions, their deliverability, and other projects coming on line. Consideration will be given to the grade and geology of PGMs worldwide and metallurgical developments. PGMs produced as by-products of base metal production and early PGM recycling estimates will also be appraised. In order to gain a wide-ranging appreciation of the industry?s long-term cost trends of producing virgin PGM metals, the paper will look at the cost and profit dynamics of global production on a regional basis (Western Bushveld, Eastern Bushveld, Northern Bushveld, Zimbabwe, USA, Canada and Russia). Extrapolating tomorrow?s PGM market and forecasting metal prices?Based on established industry trends and market practices Stephen Forrest will conclude by unveiling a variety of thought-provoking extrapolations of today?s and tomorrows platinum, palladium and rhodium markets to conference delegates. Importantly, having highlighted major developing PGM market trends in end-use (specifically on the elasticity of demand to high metal prices), primary and secondary PGM supply trends, in addition to presenting a carefully reasoned forecast of industry supply costs and margin trends, Stephen Forrest will conclude by estimating long-range PGM metal price trends. Other relevant market factors including industrial production, global currency rates and regional political factors will be deliberated.

Jan 1, 2006