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For resources projects with healthy net present value (NPV) and low cash flow volatility, conventional discounted cash flow (DCF) analysis will continue to provide the dominant investment decision-making criteria. However, DCF analysis can be biased because it often applies a single risk-adjusted discount rate (RADR) to compare the value of projects with different risk characteristics. Many of the difficulties with DCF modelling arise from analysts' inability to determine appropriate risk discounts and to estimate expected spot prices inputs for the commodities produced over the life of the project. Modern asset pricing (MAP) is a very valuable complement to DCF analysis in addressing some of these issues. Most papers dealing with MAP, however, while academically rigorous, tend not to be explicit in terms of practical application of this methodology in routine project evaluation. This paper has the objective of reviewing the MAP methodology and of demystifying its complexity, by providing a simple but realistic step-by-step evaluation of a mining project, comparing its DCF and MAP NPV values. The paper concludes that MAP provides a minimum, risk-adjusted `floor' value, thus representing a valuable complement to any DCF valuation.

Jan 1, 2007

By C. A. Cousins

Platinoids in the Witwatersrand system C. A. Cousins. (visitor) Study of the composition, nature and mode of occurrence of platinoid minerals in the conglomerates of the Witwatersrand System leads to some interesting conclusions. Genetic evidence strongly favours a placer origin, while comparison with modern alluvial platinoids supports this view but also indicates that they are very mature alluvials. The compositional patterns and distribution of the platinoids in the Witwatersrand basin suggest the water was saline. Study of the mineralogy was greatly facilitated by the electron-probe.

By L. Pretorius, S. Uludağ

This paper explores how to apply system dynamics principles to surface mining problems towards understanding the consequences of mining efficiencies. Some simulation examples related to machine and people performance have been used to demonstrate systems engineering concepts to mining engineers. The simulation tool used is Vensim, which is widely used in industrial engineering applicable to systems thinking, and systems dynamics. The science and mathematics behind the system dynamics as well as benefits and typical challenges are discussed to explore the applicability to mining problems. The benefit of having one less drill is easily quantifiable with the developed model which is one of many other measurable benefits, using the developed model. Some of the benefits of the improved quality of drill holes are not fully quantified as this depends on the mine specific inputs. There are examples of quantifying this in the other industries using system dynamics tools.

Sep 1, 2021

By R. K. Brummer

The support of stopes and tunnels in South African gold mines subject to rockburst damage requires special attention. The interaction of a seismic wave with either a stope or a tunnel is subject to a number of variables, namely the distance from the source of the event, the ground velocity, the orientation of the excavation with respect to the direction of the seismic wave, and the geology and fracturing around the excavation. This paper discusses these factors in relation to the support requirements in stopes and tunnels. The need for the integration of hydraulic props with stope support and the use of yielding anchors for tunnel support are emphasized.

Jan 1, 1988

By J. N. Baloyi

"In atomic emission and atomic absorption spectrophotometry, the sample is heated to a high temperature and thereby decomposed into atoms and ions that absorb or emit visible or ultraviolet electromagnetic radiation at energies characteristic of the elements involved. The flame test is a very simple form of this technique. The yellowing of a flame by the addition of salt, for example, occurs because the sodium in salt emits strongly in the yellow portion of the visible spectrum. These methods are especially useful for low concentrations of metallic elements in both qualitative and quantitative analysis.Interference on Iep-OES has not always been considered a serious problem, especially in the beginning, when compared with Atomic Absorption Spectroscopy. This was due to the euphoria created by the new technique. It meant that criticism was subdued. The Iep was vastly superior to the Atomic Absorption technique, that the interferences suffered by the Atomic Absorption technique dwarfed the little interferences suffered by the rep-OES technique. This is how rep-OES has had a reputation as an interference free technique."

Jan 1, 2014

By F. H. Deist, J. P. E. Morris, E. Georgiadis

For some years the Collieries Research Laboratory of the Chamber of Mines of South Africa has been engaged in the development and application of computer programmes to aid in the solution of rock mechanics problems. It is the purpose of this paper to introduce some of the programmes having general applicability. A system capable of predicting stresses and displacements induced by large-scale tabular excavations is discussed. A finite element programme especially designed for handling layered continuum problems, and which is being used extensively has been supplemented by an automatic mesh generation facility that reduces problem preparation times considerably. Some typical applications of these programmes are described. An entirely new approach, potentially capable of performing linear three-dimensional continuum analysis at practical cost is introduced.

By Gordon Chunnett, Ron Sheets, David Grant

[Power-Point Presentation]

Jan 1, 2005

By A. Cáceres, L. Navarro, N. Altmann, R. Betinol

Copper concentrate is produced in Chile in the high Andes and transported to the coast for shipping through long distance pipelines. The pipeline and fittings installed have to withstand the high abrasion and corrosion environment of the copper concentrate. To protect the inside tube wall against corrosion, high density polyethylene (HDPE) liner is used. While HDPE liners can protect the steel wall against corrosion, it has also been assumed that the low surface roughness of the HDPE liner also inhibited incrustation caused by calcium carbonate and sulphate deposition. Recent events have indicated otherwise in a couple of concentrate pipelines for which BRASS has provided consultant service. This paper delivers a case study which includes (i) formation of incrustation and adhesion to HDPE liner, (ii) the detection of the incrustation through hydraulic analysis, (iii) the mechanism of removal of incrustation, and (iv) the catastrophic effects of their presence in an emergency situation.

Jan 1, 2007

By H. Wagner

The paper points out that bord-and-pillar mining is the most important method of coal extraction in South African underground coal mines, and advocates that pillar design procedures should be refined to make more rational allowance for the differences in strength properties between various coal seams and roof and floor strata. However, any deviations from well-established design procedures must be based on sound engineering principles and reliable data on the strength properties of the seams and strata concerned. Recent information indicates that practices for the protection of surface structures against underground mining should be revised.

Jan 1, 1980

By W. S. Nel

Training in the mining industry by W. S. Nel, B. A. (Wits) (Visitor) After defining training and discussing the present level oftraining in the South African Mining Industry, the paper proposes the adoption of a centralized training system for the Industry and suggests several ways in which this should function. The finance required for the implementation and running of such a system should be obtained from State aid and from the institution of a levy and grant system for the whole Industry.

Jan 7, 1974

The First International Symposium on Seismicity in Mines, organized by the South African National Group on Rock Mechanics in collaboration with the South African Institute of Mining and Metallurgy, was held in Randburg (near Johannesburg) from 13th to 17th September, 1982. It was the first attempt to provide an international forum for the consideration of seismic problems specifically affecting mines or associated with mining. Numerical mathematics The South African Society for Numerical Mathematics and the Computer Science Department of the University of Natal are organizing the Ninth Symposium on Numerical Mathematics to be held in Durban from 18th to 20th July, 1983.

Jan 1, 1983

By P. J. Lloyd

Society is fully justified in its concern about the environment, but that concern may, at present, be too uncritical It is, for instance, essential to establish that there is a valid environmental impact, and that there is truly a causal link between a human activity and an observed shift in environmental conditions. In establishing these, it inessential to recognize that scientific proof offers consistency, but that it can never provide completeness. Thus, no amount of scientific endeavour can ever prove that mitigation of the effects of human activity will be perfect. Society normally expresses its concern through legislation. The existing legislation in South Africa is reviewed, and it is found that [>legislation regarding water is probably too stringent to be effective, >legislation regarding air and land use is probably too lax, >all the environmental legislation is too fragmented to be efficient, and the Department of Environmental Affairs is hamstrung by inter-departmental rivalry. ] It is accordingly concluded that, if means are to be found for ensuring adequate mitigation of environmental impact in the face of ongoing economic development, it is necessary to establish a Judicial Commission on Environmental Affairs advised by, but given greater powers than, the departments currently active in environmental maters. This Commission should be charged with creating, perhaps over a decade, a body of legislation that would guide development while protecting the environment in its widest sense.

Jan 1, 1994

By M. Kirsten, W. H. Botha, M. H. Fox, J. A. Moolman, A. J. Lathwood

Water is a valuable and in many areas a scarce resource. Governmental legislation regulates the environmental impact of water usage and wastewater disposal through the issue of licenses. These requirements mean that hydrometallurgical refineries must ensure that water consumption and water disposal is managed on a continuous basis in order to prevent the repeal of their operating license. Water balances are often overlooked during the design of a hydrometallurgical refinery. Recent changes in environmental legislation have forced both design engineers and operational management to review water use and disposal within these processes. Unlike concentrators where water can easily be recovered by recycling from tailing dams, water introduced into hydrometallurgical refineries becomes contaminated with soluble metals and thus requires pre-treatment prior to disposal. This paper discusses the various concerns that need to be considered during design and operation of hydrometallurgical refineries with respect to the water balance.

Jan 1, 2007

By S. Selmer-Olsen

New trends and developments in the production of ferro-silicon, ferro-manganese and ferro-chrome alloys are discussed, with emphasis on the general trend to the adoption of large production units. Problems which arise, both of a metallurgical and an electrical nature, due to the use of large electric furnaces, are outlined with specific reference to the limitations imposed by the power carrying capacity of Soderberg electrodes, the furnace resistance and the furnace reactance. The implications of combining high resistance within the furnace with good metallurgical operating conditions are illustrated by considering the production of ferro-silicon and ferro-manganese. The possibility of replacing electric furnaces used for ferro-manganese production, by large low shaft blast furnaces using oxygen enriched blast, is mentioned. The continued use of small electric arc furnaces for ferro-chrome production is also mentioned, and is ascribed to lack of ore suitable for treatment in large furnaces. Agglomeration of chromite ores appears to be a possible answer to this problem.

By H. W. Glen

The use of a personal style (mainly active voice and first person) makes technical writing more pleasant to read, and helps the writer to express his meaning clearly and to avoid many of the stylistic errors normally encountered in that type of writing.

Jan 1, 1979

By W. J. Kotzé

Die derde colloquium van die Spesialiste-afdeling van die SAIMM is op 19 November 1980by die Universiteit van Pretoria gehou en is deur sowat 40 mense bygewoon. Dr J. P. Hugo tree as Voorsitter op en heet al die aanwesiges welkom, en stel elke spreker om die beurt aan die vergadering voor.

Jan 1, 1981

By P. C. Schutte, J. R. Smith

The objective of ergonomics is to enhance the effectiveness and efficiency with which human tasks are carried out. Furthermore, the objective is to improve desirable human values. This can be achieved by enhancing safety, reducing fatigue and stress, increasing comfort, increasing job satisfaction, having greater user acceptance and thereby improving the quality of life. Mechanization has influenced the prevalence of injury, mainly due to the application of human physical effort as the power source. With mechanization, the operator’s function is now essentially one of control rather than being an energy source, however the risk of injury has not diminished. Mechanization in itself has introduced inefficiencies, health risks and physiological stress. The major objectives of ergonomics are discussed through examples of acceptable and less successful implementation of ergonomics within mechanized mining. The influence of the machine system on the human is addressed and practical solutions to improve and optimize the interaction of the human and the machine are outlined. Furthermore, practical examples of control and display integration, anthropometric and biomechanic influences on design, orientation, posture and stereotypes are used to accentuate the advantages of the application of sound ergonomics principles to the specialised area of mechanized mining.

Sep 1, 2001

By J. M. Musadaidzwa

Skorpion Zinc is located 25 km north-west of the small settlement of Rosh Pinah in southern Namibia. Commissioned in early 2003, Skorpion Zinc became the first mine-to-metal operation to commercially apply a purely hydrometallurgical process route to exploit a zinc oxide orebody. The novel technology, known as The Modified ZincexTM Process patented by Tecnicas Reunidas, comprises sulphuric acid atmospheric leaching, zinc solvent extraction (SX) and electrowinning (EW) to produce London metal exchange (LME) Special high grade (SHG) zinc. Forming the core of the process, the SX step has thrived in its role as a barrier to impurities and also in the upgrading of the pregnant liquor solution (PLS), converting it into a loaded electrolyte (LE) sufficiently rich and pure for EW. Against this successful run, a number of challenges have, however, been encountered in SX due the emergence of upset conditions largely emanating from upstream processes. This paper outlines some of the major deviations that have beset the SX process in its first five years of continuous operation. Impurity excursions, temperature depressions, changes in phase continuity, excess aqueous entrainment, the effect of colloidal silica and the accumulation of rare earth elements on the organic phase will be discussed in detail. Keywords: skorpion zinc, solvent extraction, the Modified ZincexTM Process (MZP) DE2HPA, aqueous entrainment (AE), loaded electrolyte (LE), standard liquid validation (SLV) test, organic continuity, aqueous continuity (AC), electrowinning, colloidal silica, phase disengagement time (PDT), rare earth elements (REE).

Jan 1, 2009

By R. J. Mason

The paper discusses the claim that the remains of mines in Southern Africa date from ancient times, rather than from a more modern period. The evidence indicates that these mines were excavated by Iron Age Black people, who moved into South Africa from about A.D. 100 onwards. Details are given of the finds made in 1981 in an investigation of the remains of copper mines in the Dwarsberg, which probably date from the nineteenth century.

Jan 1, 1982

By J. P. McDonald, P. L. Mattison, J. M. W. Mackenzie

A variety of processing problems in the hydrometallurgical extraction of uranium in the U.S.A. are contrasted with those in South Africa. In U.S. plants, for example, problems are often encountered in the separation of vanadium, molybdenum, and uranium, and in the contamination of the circuit with organic acids. South African plants often experience problems with dissolved silica in the feed, clarification of feeds, and problems associated with synthetic polyelectrolytes. Individual situations are examined, along with the analytical techniques that assist in solving specific problems. Successful approaches that have been applied to mechanical and chemical problems in' uranium solvent-extraction plants are discussed.

Jan 1, 1981