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By W. K. Osae

A value assessment model which uses deal objectives, financial and non-financial indicators as a guide to assess value creation in mergers and acquisitions. The extent to which post- merger deal objectives are achieved and the potential benefits derived from mining deals that may not necessarily be financial of nature, but which are necessary to sustain and enhance future performance, were considered. The pre-merger and post-merger performances based on some financial indicators that reflect profitability for shareholders were also used. This value assessment model was used to assess four major deals that have occurred in the South African mining industry since 2003 as part of a postgraduate dissertation. In this paper, the Harmony and ARMgold merger is used as an example of how the model can be applied. The model?s relevance and applicability can also serve as a guideline in developing a framework or holistic guideline in assessing whether mining BEE deals in South Africa create value.

Jan 1, 2011

By E. Cetin

Orebodies that contain more than one economically important mineral are generally evaluated by parametric cut-off grades. This approach often leads to mis-valuation of mineral deposits because cut-off grades are not based on the grades of each individual mineral and, because of the parametric formulation, are only indirectly related to the individual grade distributions. The only realistic approach is a formulation that accounts separately for each component mineral. The grid search method can be used as a means of multi-mineral cut-off grade optimization in this context. This paper describes the use of the grid search method in cut-off grade optimization for multi-mineral deposits. The authors introduce the general concepts of the method and formulate its application to cut-off grade optimization; they describe a software implementation of the method that can accommodate cut-off grade optimization for mineral deposits that contain up to three economic minerals. Keywords cut-off grade, optimization, grid search, multi-mineral deposits.

Aug 1, 2013

By J. C. D. Gush

Paper written on project work carried out in partial fulfilment of Laboratory-scale testwork was undertaken to recover oxidic copper-cobalt minerals by froth flotation, which requires maintaining a certain sulphide level in the pulp. To improve control of the sulphide concentration, an electronic closed-loop system was designed that responds to the potential output of an ion-selective electrode. The PID control was improved by adding a pre-emptive control and a self-calibration feature; a data logging facility is also included. An inexpensive valve design was incorporated using locally available parts. The operating results of this control design are presented.

Jan 1, 2005

By J. P. De Carvalho, R. Dimitrakopoulos

This paper presents an actor-critic reinforcement learning (RL) method to allocate trucks and shovels in open-pit mines, while defining short-term production scheduling of an industrial mining complex, given new information collected during operations. This new data obtained from sensors update the uncertainty of the orebody models. The RL agents interact with the mining complex environment; exploring the solution space, learning actions to improve metal production and equipment utilisation. A case study is presented at a copper mining complex, highlighting the method’s ability to adapt and make informed decisions while collecting new information.

Sep 1, 2021

By J. O. Roux

The Impala Platinum Limited Base Metals Refinery in Springs, South Africa, refines convertor matte containing base metals and PGM?s (platinum group metals) using a hydrometallurgical process. In addition to a PGM-rich concentrate that is further refined, the Base Metals Refinery produces nickel (in powder or briquette form), copper cathodes and cobalt powder. Five leaching stages are utilized to remove the base metals and impurities from the PGM concentrate. The project described in this paper involves a radical redesign of the second stage leach autoclave with the aim of reducing maintenance costs and downtime, increasing throughput and ensuring a safer working environment. The second stage leach process at the Base Metals Refinery, produces a PGM-rich residue through the extraction of copper and any remaining base metals from the first stage leach solid residue material. Leaching is performed in an autoclave operating at a pressure of 600 kPaG and a temperature of 140°C to 150°C. Concentrated H2SO4 is added to the feed to produce a solution with a free acid content between 10 and 30 g/L and a pH of less than 2. Oxygen is passed into the 1st and 2nd compartments of the autoclave. As a result of the aggressive, highly oxidizing conditions within the autoclave, the original design utilized a heavy wall carbon steel shell with lead lining and two layers of acid bricks. The bricks acted as a wear resistant material and ensured a low surface temperature at the skin of the lead lining, whereas the lead lining acted as a corrosion barrier to protect the steel shell. These brick lined autoclaves were heavy, maintenance intensive and prone to catastrophic failure. A radical autoclave redesign was needed to reduce the high costs of manufacturing, installation and operation. Finite element modelling was used to optimize the design and various high alloy materials were investigated for the application. Based on extensive test work, the carbon steel shell was replaced with duplex SAF 2205 stainless steel in the new design. The use of this highly corrosion resistant material, eliminates the need for the lead and brick linings and reduces the wall thickness requirements substantially, resulting in an increase in the available volume for the same external shell dimensions. The vessel is welded in circular sections to form an elongated, impermeable, cylindrical body, with several agitator nozzles and compartments. The first new duplex stainless steel unit has been in continuous operation for more than 24 months and its performance has exceeded the highest expectations. The design was so successful that a patent has been registered. The major benefits of the new stainless steel design include increased throughput, improved performance, less downtime and a safer working environment. Lead has been eliminated and replaced with a more environmentally safe material, and the total lifespan of the vessel has been extended. In addition, the autoclave project has made significant developments in advancing the field of welding and optimizing the integrity of welding quality standards in South Africa.

Jan 1, 2009

Fig. 4 and 5 of the paper 'The analysis of ventilation and cooling requirements for mines' by J. van der WaIt, E. M. de Kock, and L. K. Smith are positioned incorrectly in the February issue (J.B. Afr. Inst. Min. Metal., vol. 83, no. 2, Feb. 1983). Extractive metallurgy of zinc At a professional development seminar to be held in Montreal (Canada) from 18th to 22nd April, 1983, specialists from industry and university will discuss the extractive metallurgy of zinc from ore to finished metal with special emphasis on the theory and practice of modern technology.

Jan 1, 1983

By H. E. James

The 13th Congress of the Council of Mining and Metallurgical Institutions (CMMI) was held in Singapore from 11th to 16th May, 1986. Tours to Australia, Malaysia, Thailand, South Korea, and Japan took place the week before and the week after the Congress. Registrations By far the largest contingents at the Congress were from Australia (157 delegates and 65 affiliates) and South Africa (127 delegates and 99 affiliates). The other 25 countries represented at the Congress accounted for 118 delegates and 37 affiliates. Thus the total registrations amounted to 402 delegates and 201 affiliates.

Jan 1, 1986

By W. K. Brinsden

The Australian Institute of Geoscientists (AIG) held their fifth successive annual seminar at Observation City, Scarborough, in Perth on 15th November, 1990. The title of the seminar was 'Strategies for Grade Control'. The Seminar attracted 158 delegates, including 10 speakers. In addition to geoscientists, the attendees included mining engineers, metallurgists, and mining analysts. The welcoming address was given by Rob Duncan, Chairman of the Westem Australian Branch of AIG, who said there is a strong demand for this type of seminar in Western Australia (WA). It helps geoscientists to keep up with former colleagues and to keep abreast of technical developments.

Jan 1, 1991

By J. A. Cox, R. P. H. Willis, J. R. Dixon, A. D. Pooley

The paper describes the issues that should be considered when introducing mechanization to a mining operation. In South Africa, traditional methods of mining are well entrenched after more than a century of mining. To successfully change from these methods requires an integrated holistic approach that considers all aspects of a mining operation including setting of objectives, selection of personnel, recruitment, training and remuneration policies, organizational design, mine design, equipment selection, maintenance philosophy, standards and procedures, and monitoring and control. The paper makes reference to experience gained during a variety of on-mine case studies in drawing generic conclusions and making recommendations.

Jan 1, 2004

By V. M. Lovell, N. P. Finkelstein

Fundamental studies of the flotation process: The work of the National I nstitute of Metallurgy N. P. Flnkelsteln and V. M. Love Presented at the Colloquim on Flotation, March 1972, and published in the Journal, July, 1972. AUTHORS' REPLY TO DISCUSSION In his contribution to our paper Dr Lloyd makes two criticisms: The first criticism, as we interpret it, is that the agglomerate flotation process that we described is not really necessary because previously described processes effect almost the same results or could be made to give the same results by including sufficient paraffin in the reagent combination.

By I. E. Lane

Conventional demand management techniques invariably fail to offer optimum control flexibility in an operationally complex gold mining environment. An improved control system for electrical demand management is proposed. The system is designed to provide more effective load scheduling and control strategies by means of a computer aided demand management system (CADMS). The objective of the CADMS is to provide a responsive computational aid and adaptive control system for effective demand management. The system consists of a short term load forecasting module, an interactive load scheduling module, an incentive based electricity cost allocation module and a power management information module.

Jan 1, 1987

By G. Sommer, R. P. Chaix, G. T. W. Ormrod

Recent developments in the instrumentation and automation of uranium-processing plants by G. SOMMER, Ing. (Grad.) (Visitor), G. T. W. ORMROD (Visitor), and R. P. CHAIX, B.Sc. (Visitor) The paper discusses work at the National Institute for Metallurgy on the evaluation of measuring techniques for the automatic control of free acid in leaching. of the ratio of ferric to ferrous ion in leaching, of pH in liquid-liquid extraction. and of uranium in loaded solvent. Commercially available instruments. and the modifications that have been made to adapt them to South African uranium plants, are also described.

By A. D. Thomas, K. C. Wilson

Some years ago, the authors developed an analysis of non-Newtonian pipe flow based on enhanced turbulent microscale and associated sub-layer thickening. This analysis, which can be used for various rheologic modelling equations, has in the past been applied to smooth-walled pipes. The present paper extends the analysis to rough walls, using the popular Bingham plastic equation as a representative rheological behaviour in order to prepare friction-factor plots for comparison with measured results. The conditions for laminar-turbulent transition for both smooth and rough walls are also considered, and comparisons are made with earlier correlations and with experimental data.

Jan 1, 2007

By J. A. Tyser

The pumping of water from mines in the Central Witwatersrand by J. A. TYSER, Pr. Eng., B.Sc. (Min.) (Associate) This paper describes a system for the removal of underground water in the mines of the Central Witwatersrand, some of which are defunct. The water is pumped by a pump station on 24 level at E.R.P.M. to a surface lime plant and then to a surface treatment plant, where it is treated so that it meets the specification of the Department of Water Affairs relating to the deposition of water in public streams.

Jan 5, 1977

By T. A. Claasen

Exceptionally low yields in the coking-coal fields of the Soutpansberg area in the northern Transvaal, are taxing the skill and ingenuity of preparation engineers. The coals are highly intergrown, and a series of crushing and washing steps may be required to extract the maximum usable tonnage. In addition, novel preparation techniques may have to be employed. This paper, which is a case study of work recently undertaken, gives a general account of raw coal properties, emphasizing those related to maximum recoveries, and outlines the steps involved in the design of appropriate flow sheets based on laboratory studies.

Jan 1, 1980

By C. R. Speers, M. I. Forsyth

The paper describes how stress analyses were used to show the defect of a tunnel's shape on the overstressing potential of its periphery. The best profile was found to be that of a horizontal ellipse, for which there was little significant scaling, permitting temporary support to be incorporated into a permanent tunnel support system. This investigation was followed by the modeling of several support systems for tunnels with a horizontal-ellipse profile, which showed that such a profile can reduce the installed support required for a tunnel of different cross section by an average of 57 per cent.

Jan 1, 1994

The support of stopes by means of yielding timber props, with or without hydraulic props, is common in the mining industry. This paper discusses the ability of these support systems to absorb energy during a rockburst, and further investigates their capability to withstand a range of ground velocities. It is found that the rate of stope closure prior to a rockburst strongly influences the behaviour of these support systems during the rockburst. It is recommended that hydraulic props be used in conjunction with yielding timber props in these conditions, and that yielding timber props with an increased yield range are desirable.

Jan 1, 1991

By C. Kliem

Geological, tectonic, geochemical and geophysical data were utilized for the mineral resource assessment of the Biga Peninsula in NW Turkey. During the deductive phase of the project multivariate statistical methods were applied to accentuate characteristic parameters which sufficiently describe the different types of Pb - Zn mineralization. The parameters most likely to be indicative of mineral occurrences were determined. In the following prognostic phase these parameters were further statistically treated to determine favourability indexes for the occurrence of a deposit within each cell of the training area. Preliminary results of probabilistic, univariate and multivariate methods are presented.

Jan 1, 1987

By I. H. Clark

In some mining situations, backfills are not only required to be free-standing but are also expected to provide hangingwall support. It may therefore be specified that the backfill withstand a certain calculated stress within a given time. Given the materials available, the choice of backfill composition is not always straightforward, and an approach to the evaluation of cemented tailings backfill is therefore proposed. The general use of such a method will greatly assist in both the scientific analysis of the material properties for industry-wide purposes of comparison and decision-making as regards the choice of fill.

Jan 1, 1988

By C. M. Suhr

n order to validate the borehole analysis valuation procedure commonly used in the South African gold mining industry, a simulated orebody was used to create borehole values which would serve as data for the procedure. After confirming the distribution, calculating the variance size of area relationship, estimating the block variance, and calculating a profit measurement for each set, comparisons were made to the known population parameters. Results show only one overall bias (in the estimation of the lognormal third parameter), which is carried throughout the analysis. The remainder of the analysis is unbiased, validating the procedure.

Jan 1, 1987