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By D. Limpitlaw, A. Alsum, D. Neale

"Ecological footprint analysis (EFA) was first described in 1996 as a measure of carrying capacity appropriated by human activities. EFA is a resource and emissions accounting tool designed to track the demand on the biosphere’s regenerative capacity. Ecological footprints are increasingly used as indicators of organizational and corporate environmental performance and product sustainability. There is a compelling argument to develop an EFA tool for mining companies.To determine the size of a mine’s ecological footprint, land requirements for all categories of consumption and waste discharge must be summed. This land is only made up of the ecologically productive land and water in various classes (cropland, pasture, forests etc.) required on an ongoing basis to provide all energy and material resources consumed and absorb wastes.A challenge in conducting an EFA for a mine is the shortage of accessible data. Undertaking an EFA for a corporation or individual site entails compiling consumption and emissions data (which can be used for other reporting applications). The footprint results themselves highlight the most critical aspects of an organization’s impact on the environment and provide a platform for focusing actions and for educating the workforce to improve their contribution to best-practice operations. This paper discusses the benefits and challenges of undertaking an EFA for a mining company, and provides examples of the various components of ecological footprints associated with mines, as well as showing how an EFA can be used to understand and communicate some of the impacts associated with mining activities.IntroductionFundamental biophysical and economic limits are now being experienced in many countries around the world. Herman Daly, a former World Bank economist, described this scenario as ‘uneconomic growth’, where the costs of growth exceed the benefits (Daly, 2005). This occurs when the economy’s expansion encroaches excessively on the surrounding ecosystem, sacrificing natural capital. Under such conditions the sacrificed natural capital is more valuable that the resulting economic growth. Consequently, the world faces largescale threats to sustainability and especially to the viability and continued existence of the ecosystems that support human settlements (El Zein et al., 2014). In recognition of this sustainability imperative, mining companies are increasingly concerned with their ecological footprint (EF)."

Jan 1, 2017

By R. du Preez

Tati Nickel is currently operating a hydrometallurgical demonstration plant in Botswana, using the Activox® process developed by LionOre Technology to produce nickel cathode and a cobalt salt from a sulphide concentrate. Cobalt is extracted using Cyanex 272. This reagent also extracts all the iron, aluminium, copper, zinc, and manganese from the nickel stream. Versatic 10 carboxylic acid is then used as extractant to recover nickel from the stream, separating it from calcium and magnesium, and upgrading it to provide a suitable advance electrolyte for nickel electrowinning. However, the selectivity of Versatic 10 for nickel over calcium is limited, and gypsum formation in the extraction circuit is a problem when attempts are made to maximize the recovery of nickel. Mintek has developed a synergistic system with Versatic 10 for improved separation of nickel from calcium and magnesium. Laboratory testwork was conducted on the raffinate of the cobalt solvent extraction circuit to optimize the Versatic 10/Nicksyn? (Mintek synergist) system to be employed. Extraction and stripping parameters suitable for this stream were optimized in the laboratory and then applied on the demonstration plant. A commercial batch (0.5 tons) of Nicksyn? reagent was produced for the demonstration plant. The laboratory testwork results and the demonstration plant performance are discussed in detail in this paper.

Jan 1, 2007

By A. H. Mokken, G. K. I. Blendulf, G. J. C. Young

A study of the arrangements for pulp discharge on pebble mills, and their influence on mill performance by A. H. MOKKEN, B.Sc. (Eng.) (Rand) (Fellow), G. K. I. BLENDULF, M.Sc. (Stockholm) (Member), and G. J. C. YOUNG, B.Sc. (London) (Member) Although used for many years in the gold-mining industry, the conventional pan lifter at the discharge end of a pebble mill has hindered attempts at optimization of speed of rotation and pulp flow. A theoretical approach to flow patterns in pan lifters has pointed to limitations in the capacity of these lifters, with capacity decreasing as speed of rotation is increased. Complete elimination of the pan lifter by the adoption of peripheral or end discharge has resulted in a marked increase in pulp flow and an improvement in power utilization. Assays of the gold content of pulp discharged after a mill stoppage from mills fitted with pan lifters show values well in excess of the current milled grade, which indicates an accumulation of gold particles in the mill and, therefore, a longer retention period. The same could apply to other heavy minerals and metals present in the ore feed or worn off mill linings and metallic grinding media. Examples are osmiridium, fine iron and iron alloys, and copper and sulphide minerals. This phenomenon is attributed to the higher specific gravities of these metals and minerals, causing them to migrate towards the mill shell, from which position they are not readily removed by the lifters at the discharge end of the mill. The close association of gold particles with iron and sulphide minerals in the crevices of mill liners might be conducive to the formation of coatings on the gold. Assays of samples of milled pulp taken from a mill designed for end discharge show a lower accumulation of gold. The accumulation and nature of these gold particles are being studied at present. With increasing diameters of pebble (or autogenous) mills, peripheral or end discharge appears to be the preferred method of pulp removal.

Jan 5, 1975

Palabora Mining Company is operating a copper block cave mine in the Limpopo Province of South Africa. The mine was developed in the late nineties with a target ore reserve of 220 million tonnes of carbonatite at 0.69% copper. At 30,000 tonnes per day the operation had an estimated life of mine of approximately 23 years. Cave induced open pit side wall failure occurred in late 2004 with 130 million tonnes of waste reporting to the bottom of the open pit. This failure resulted in potential sterilization and dilution of the ore reserve and subsequent reduction in life of mine. Physical and numerical modelling indicated potential losses of up to 30% of the original ore reserves. Cave Management tools based on throughput principles are utilized to manage the failed waste ingress and ensure an optimum life of mine. Extracting the maximum rate possible, as soon as draw points are commissioned, with the view of achieving the highest production in the short term, is any mining operation?s goal as more money is required sooner. This approach, of course, improves the cash flow but presents a risk in the cave propagation profile as overall draw control is compromised. At Palabora it is evident from a Mineral Resource Throughput Management (MRTM) point of view that maximum production in the short term is not the solution. If high production rates are achieved and the profile of the cave is not manage correctly, this results in failed waste reporting to draw points earlier with adverse effects on grade. This would effectively and significantly shorten Palabora?s Life of Mine. The applications of good MRTM principles are required to assist the value chain for sustained profitability. The process commenced with change management paving the way for a better understanding and a holistic view for all role players.

Jan 1, 2007

By R. M. Falcon

The paper opens with a summary of the major factors responsible for spontaneous combustion in coal discards. These include heat arising from the oxidation of coal and pyrite, and from the weting of dry or oxidized coal and pyrite; and certain petrographic conditions leading to self-ignition of the coal such as low rank, the presence of a high proportion of reactive constituents, and the occurence of highly porous and botanicaly structured inertinite macerals, The analyses of 6 samples from 2 discard dumps in the Witbank coalfield are included, which show that, according to a three-grade classification of liability to spontaneous combustion, one dump is 'reasonably liable' and the other is 'most liable', It is pointed out that factors other than liability to self-ignition determine the possible utilization of such discards, and that the prevention of oxidation is of great importance if they are to be utilized and spontaneous combustion to be prevented,

Jan 1, 1986

By B. H. Kim, S. K. Chung

RMR, Rock Mass Rating, is one of the famous rock classifications. However, RMR was proposed empirically and absolutely depends on the experience of engineer. Therefore, engineering verification is needed for RMR system itself. In this study, the factor analysis and the multiple regressions were performed in order to evaluate the validity of rating factor of RMR. Also numerical analysis was carried out using the FLAC based on Taguchi method, a kind of robust designs, in order to examine the support of tunnel corresponding to the revaluated RMR. As the result of the analysis new RMR was proposed with five minimized factors of intact rock strength, RQD, spacing, persistence and roughness of discontinuities. RMR est un des procédés de la classification du roc qui sont généralement utilisés. Mais RMR s'appuie sur l'expérience et se absolument soumet à l'expérience d'ingénieur. Il est donc nécessaire de vér- ifier techniquement sur le système de RMR. Dans cet étude, on met à exécution l'analyse du facteur et la régression multiple pour évaluer la convenance de la cause de classification de RMR. De même, pour évaluer le support du tunnel selon RMR réestimé, on a exécuté l'analyse de la valeur numérique par FLAC qui se base sur la lois de Taguchi, laquelle est une sorte de système du plan robuste. Selon le résultat de la régression multiple, il est proposé de nouvel RMR à partir de l’intensité de roc intact, RQD, l'espacement, la persistance et la rugosité RMR ist eine der weit benutzten klassifikationen fuer die felsenstuecke. Da aber RMR erfahrungs- maessig ist und ueberwiegend von der persoenlichen Erfahrung eines Ingenieurs entschieden ist, ist es mit Sicherheit notwendig, das RMR-system selbst technisch zu ueberpruefen. In diesem studium waren die faktorenanalyse und mehrfachregressionanalyse durchgefuehrt, um die gerechtigkeit der klassifikationenfaktoren von RMR zu bewerten. Ferner war noch eine numerische analyse mit ben- utzung von FLAC aufgrund der Taguchi-methode, eine art technik der robust design, eingefuehrt, um die tunnelstuetze infolge der neubewertung von RMR unterzusuchen. Gemaess der mehrfach regression analyse wurde eine neue RMR, die sich aus 5-eingeschraenkten faktoren wie intact rock strength, RQD, spacing, persistence und roughness von discontinuities zusammensetzen, in vorsch- lag gebracht

Jan 1, 2003

By L. S. Linda, P. G. H Pistorius

Ferritic stainless steel is utilized to fabricate automotive exhaust systems using a ferritic weld metal. Ductility of the weld metal is higher if its microstructure contains a significant proportion of equiaxed grains. The formation of equiaxed (rather than columnar) grains is favoured by a higher titanium weld metal content. In this study, the Ti content of ferritic stainless steel weld metal was changed by using Tifree (Type 436) and Ti-containing (441) ferritic stainless steel as base metals. The metal-cored welding consumable contained 0.4% Ti. Gas–tungsten arc welding and gas–metal arc welding processes were compared. The weld metal Ti content ranged from zero to 0.5% Ti, as determined from scanning electron microscopy supplemented by inductively coupled plasma optical emission spectroscopy. Cross-sections of the weld beads were subjected to point counting (to estimate the fraction of equiaxed grains) and image analysis (to estimate the average grain size). Point counting proved to be more reliable. The fraction of equiaxed grains was sensitive to the Ti content, but not to the welding process. Below 0.4% Ti, the fraction of equiaxed grains gradually increased with an increase in the weld metal Ti content; above 0.4% Ti, the fraction of equiaxed grains rapidly increased with increasing Ti content. The transition in behaviour at 0.4% Ti corresponded to a Ti content at which Ti-rich precipitates became stable at the estimated liquidus temperature of the weld metal.

Jul 2, 2022

By R. S. J. Du Toit

SYNOPSIS This paper is based on a thesis dealing with the problem of basing the current rate at which money is collected from mine owners to pay compensation for pneumoconiosis in the future, on the current dust hazard on mines. The certification of pneumoconiotics and the incidence of pneumoconiosis are discussed against the background of existing legal provision for collecting funds for compensation. The various pneumoconiosis indices are considered. In the data analyzed, the only pneumoconiosis index common to a number of classes of mines is the time it takes to develop pneumoconiosis. Sets of dust indices and pneumoconiosis indices are computed. Expressions are derived for the time it takes to develop pneumoconiosis as a function of the dust hazard, and for the collection of funds as a function of the time available for collection. From these two expressions follows an expression for the rate of collecting funds as a function of the dust hazard.

"Chairman: Professor H. S. SICHEL Rapporteur: Miss M. I. WATSONPapers:Unrolling of Copperbelt orebodies by J. H. E. Perry and V. H. WiikAn exploration model for tabular orebodies by G. S. Koch and R. F. LinkHarmonic analysis of copper and gold occurrences in the Arbitibi area of the Canadian Shield by F. P. Agterberg and A. G. FabbriMathematical models of orebodies by M. J. Newton and A. G. Royle Estimation of lateritic-type orebodies by A. JournelIn his presentation Mr Wiik said that unrolling could be regarded as a reversal of the natural process of folding, so that the aim of an unrolling procedure would be the reconstruction of original pre-tectonic conditions. While simply formulated, this aim might not always be achieved. The geometrical relationship between points on the deformed surface and corresponding points on the original surface is process-dependent, and a true reconstruction could be achieved only if the deformation history were known in detail.In this computer unrolling procedure all these complexities were ignored. Referring to one particular marker horizon, Mr Wiik said that it was assumed in the procedure that this marker was deposited as a horizontal stratum and that it had subsequently been deformed by simple flexure-type folding.The procedure allowed the geologist to incorporate his knowledge and conception of the deposit through repeated re-contouring with dummy points. This 'manumatic' aspect of the procedure had proved invaluable, not only in resolving specific unrolling problems but also in making the system more acceptable to the geologists in general.Unrolling served towards removing what might be termed `tectonic noise' superimposed on the primary distribution patterns for regionalized variables such as metal content and orebody thickness. From this point of view, variograms derived on the basis of unrolled-plan co-ordinates should be more meaningful in terms of depositional environment than are variograms calculated from a normal map projection.Mr M. M. Oosterveld remarked that it appeared from the paper that there were problems in applying the unrolling technique to ore reserve calculation, and asked whether there were not other methods that might be used for that purpose.Mr Wiik replied that at present unrolling played only a minor role in practical ore reserve estimation within Roan Consolidated Mines, Limited. The techniques currently in use differed from one orebody to another, but in general they involved projection onto a vertical longitudinal section or a horizontal plan, with subsequent grid interpolation by means of a standard computer contouring package."

Jan 1, 2014

By F. T. Cawood

This article offers a personal and independent view on the threats to the sustainability of the South African minerals industry. It argues that if the six identified threats of insufficient spending on research and development, general standard of education, nationalization, inadequate infrastructure, Aids prevalence and labour inefficiency are not acted upon as a matter of urgency, the future of the mining industry, along with its important contribution to the economy, is at risk.

Jan 1, 2011

This paper describes an interactive personal computer program, ENVIRON, which simulates cooling and ventilating systems on gold mines. An example of the practical application of the program is given and proposed future developments are discussed. The program consists of two main modules, HEATFLOW and VENT- FLOW. HEATFLOW calculates the heat loads and the effect of air coolers, while VENTFLOW estimates the air flow distribution. As the calculation of the heat loads requires a knowledge of the air flow and vice versa, the two modules are run iteratively until the solution converges. The program is written in Pascal and runs on any IBM-compatible personal computer.

Jan 1, 1987

Book review Doyle, William S. Strip Mining of Coal; Environmental solutions. Park Ridge (New Jersey), 1976. 352 pp. $32. Surface mining of coal is still in its infancy in South Africa. The environmental repercussions following large-scale disturbance of the land surface, and the secondary effects of the disposal of waste products and effluents from mining, have not yet become apparent.

Jan 1, 1977

By A. A. Oakes, P. M. C. Wilson

This paper describes some aspects of the planning of a new colliery which commenced production in the Middleburg district in 1966. An account is given of some of the problems encountered in the early years of operation and of what was done to solve them. The conclusion is reached that design of plant and machinery should be flexible to permit multiplication of units.

By C. J. Alberts

The perception exists in many organizations that, once an energy management system is employed, there need not be any further adjustments to such a system. This is not true, as the field of energy management is a dynamic field, and constant feedback and adjustments are needed to enhance the efficiency of a system to the point that substantial pay-back can be obtained. It is stressed that for any energy management system to be successful, careful planning should permeate through the organization, from the top level decision-makers to the workplace. This paper describes a dynamic technique by which energy management strategies can be evaluated by viewing the effects of the strategies on the organization as a whole.

Jan 1, 1997

By R. C. More O’Ferrall

The author mentions some of the problems he has encountered, together with their solutions. These include the stoping of isolated pillars, the reduction of the size of shaft pillars, the stoping of a new horizon above or below a horizon that has already been stoped out, and the mining of thick bands of reef left behind in the footwall or hanging wall.

Jan 1, 1981

By G. Akdogan, I. Mwandawande, S. M. Bradshaw, M. Karimi

The mixing characteristics of industrial flotation columns were investigated using computational fluid dynamics (CFD). Particular emphasis was placed on the clarification of the relationship between the liquid and solids mixing parameters such as the mean residence time and axial dispersion coefficients. The effects of particle size and bubble size on liquid dispersion in the column were also studied. An Eulerian-Eulerian method was applied to simulate the multiphase flow, while additional scalar transport equations were introduced to predict the liquid residence time distribution (RTD) and particle age distribution inside the column. The results obtained show that particle residence time decreases with increasing particle size. The residence time of the coarser particles (112.5 μm) was found to be at least 60% of the liquid residence time, while the finer particles (19 μm) had a residence time similar to the liquid. The results also show that an increase in the particle size of the solids results in a decrease in the liquid vessel dispersion number, while a decrease in the bubble size increases liquid axial mixing. Finally, the simulated axial velocity profiles confirm the similarity between the liquid and solids axial dispersion coefficients in column flotation.

May 2, 2022

By T. Moyo

"The oxidative leaching of chalcopyrite in ammoniacal solutions has been evaluated using electro-analytical techniques and controlled bulk leaching studies. The anodic dissolution process has been established to be a sevenelectron transfer process under nitrogen in ammonia–ammonium sulphate solutions and ammonia–ammonium carbonate solutions, which suggests that the sulphur is oxidized to thiosulphate and the copper and iron released as Cu+ and Fe2+ in these systems. The deportment of Fe2+ and S2O3 2- is affected by choice of the ammonium salt used in the leaching process. In the perchlorate salt, only five electrons are transferred, supporting formation of different sulphur species as proposed for the sulphate and carbonate salts. Scanning electron microscopy and energydispersive spectroscopic analysis of the mineral surface after leaching indicate presence of an iron–sulphur surface layer completely free of copper in the sulphate system, an iron-rich surface layer in the perchlorate solutions, and absence of surface layer build-up in carbonate solutions. XRD analysis of a bulk leach residue from leaching in ammoniaammonium sulphate solutions showed the surface layer to be mostly amorphous (90%). The crystalline content (10%) is composed of 95% polymorphs of anhydrous iron oxide hydroxide FeO(OH). Choice of ammonium salt and the hydrodynamic environment of leaching have been shown to influence the presence or absence of the surface product, as well as its nature. IntroductionHydrometallurgical processes for copper extraction provide a viable route to recover the metal from mixed and low-grade ores, as well as overcome the environmental challenges faced by the traditional pyrometallurgical processes. Chalcopyrite is not only the most abundant of the copper sulphides, but also the most stable, making it recalcitrant to hydrometallurgical processes. Hence, hydrometallurgical processing of chalcopyrite continues to be an attractive area of research due to the vaguely understood surface chemistry of the mineral in different aqueous media. Different routes for hydrometallurgical treatment of chalcopyrite can be followed. These include thermal treatment prior to leaching, direct leaching and direct electrochemical leaching (Venkatachalam, 1991). Direct leaching of chalcopyrite can be carried out in various solution systems, as reviewed by Roman and Benner (1973) and Venkatachalam (1991). Ammoniacal solutions are attractive and effective lixiviants that form stable amine complexes with some base metal cations while rejecting iron. Leaching of chalcopyrite in ammoniacal solutions in the presence of an oxidant is possible due to the stabilization of copper (I) and copper(II) by ammonia at elevated pH levels. In oxygenated ammonia solutions, it has been suggested that chalcopyrite dissolves according to Equation [1] (Beckstead and Miller., 1977a):"

Jan 1, 2016

By L. C. Woollacott

A computer-aid is described that is designed to calculate steady-state material balances for ore-dressing circuits. The program determines the material balance from a specification of the process condition. No mathematical models or data adjustment techniques are employed. As such the program complements existing simulation and material balance 'smoothing' packages. The process condition is specified using performance indicators. These are significant parameters in the industry with which all practising mineral processors are very familiar. The program employs an equation-oriented technique for material balancing and so has had to deal with the difficulties peculiar to that approach.

Jan 1, 1987

By R. C. Dunne, W. A. Gilbert, I. J. Corrans, K. S. Liddell

After bench-scale and pilot-plant tests in which it was shown that wet high-intensity magnetic separation (WHIMS) can achieve good recoveries of gold and uranium from Witwatersrand residues, a production size machine was installed at a gold mine. The mechanical and metallurgical performance of this machine have been satisfactory, and the economics of the process are attractive. WHIMS can be combined with other unit operations like flotation for the optimization of overall gold and uranium recoveries. This concept is shown to be relevant, not only to operations for the retreatment of tailings, but to processes for the treatment of coarser material. In the latter, there is a saving in energy consumption compared with the energy required for the fine grinding of the total feed, and a material suitable for underground backfill can be produced. Improved. more cost-effective WHIMS machines currently under development are also described.

Jan 1, 1983

By J. O. Marsden

The copper industry is cyclical with the price determined by market forces (i.e. the balance between supply and demand for the metal.) The period of each cycle typically varies between 6 to 9 years. These cycles drive decision making for exploration, new project and mine development, mine closures, process improvement, research and development, and technological innovation. The gold industry is fundamentally different from copper in that supply and demand do not, alone, determine metal price and many other factors play a key role, including global and regional financial conditions, political stability, and the global future economic outlook. However, the gold price experiences trends and longer term cycles that similarly drive business decision making. This paper examines developments in the copper industry that have occurred over the past few price cycles (approximately 20 years) and explores how the lessons learned can be applied to gold extraction. A number of specific examples and opportunities are discussed in detail, including; technology development and innovation, cost control and business improvement, material characterization, comminution equipment, biological heap leaching, and concentrate pressure leaching.

Jan 1, 2009