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By D. G. Krige

For the purpose of determining confidence limits for ore grade estimates, an extensive simulated data base was used, which included 1728 ore blocks with ‘actual’ grades and the corresponding estimates based on ordinary and simple kriging. The practical results show that conditional unbiasedness is essential and that acceptable confidence limits can then be set using Normal theory for the simulated error distribution based on the logarithms of the ratios of ‘actuals’/estimates with a variance related to the kriging variance. The mean of the data used to prepare the variogram and the estimated block grade are to be used properly in this approach. A practical analysis was also done of the actual point and block data from a very large mined out Carbon Leader area. The distributions of the actual grades for two levels of block sizes with different levels of variability were fitted using three models, ie. 2-. 3- and compound-lognormal. The trends of tonnages, grades and relative profits for a range of pay limits, as well as the usual tonnage-grade curves, show a practical insensitivity for the choice between the three lognormal models considered.

Jan 1, 2003

By K. Lomberg

In this paper the process of sampling and assaying as it relates in particular to the platinum group elements (PGEs) is presented. A discussion of the geology of PGE deposits is included to provide an understanding of the mineralization that is considered necessary prior to sampling, as this has a direct bearing on the mineral resource estimate and also the selection of an appropriate mining cut. The discussion includes the selection of the sampling technique (drilling or face sampling), the size of the sample relating to the requirements of the laboratory, the potential mining cut, as well as a reference to sampling theory. The selection of an assay technique that is appropriate and will yield the optimal result based on sample turnaround, precision, accuracy, and cost is then considered. Examples are drawn from work undertaken on the Bushveld Complex (Merensky Reef, UG2 Chromitite Layer, Platreef) and Great Dyke (Main Sulphide Zone). A discussion of the appropriate QA/QC programme includes the chain of custody, CRM selection and the QA/QC process. Keywords sampling, assaying, QA/QC, platinum group elements.

Jan 1, 2014

By S. A. C. Liedberg, M. H. Fricker

The conference was divided into a total of 12 different sessions. Apart from the keynote addresses, the papers covered many aspects of open-pit mining, from mine design and blasting techniques to mining operations and equipment, as well as water management and rehabilitation. A number of case studies were also presented. Most of the 68 papers originated from Australia; however, presentations were also made by representatives from Chile, Indonesia, Papua New Guinea, and South Africa. The keynote papers dealt with subjects such as the economics of open pits, project planning of a new large copper deposit, management principles, and rehabilitation strategies.

Jan 1, 1993

By V. E. Ross

These effects were investigated in batch flotation studies, and by the measurement of rest and pulp potentials. At Iow additions of sulphurous acid as the pH regulator, flotation rate increased with increasing concentrations of dissolved oxygen. The recovery of chalcopyrite dropped significantly below a pH value of about 6,5 at 25 p.p.m. of dissolved oxygen, and below a pH value of about 6 at a dissolved-oxygen concentration of 8,2 p.p.m. The rest and pulp potentia Is measured indicated that dixanthogen is the dominant species formed on chalcopyrite surfaces during flotation with sodium ethyl xanthate. The results suggested that the same species might have formed on galena surfaces in the pulp after the ore had been milled in a ceramic mill under nitrogen. Increased additions of sulphurous, sulphuric, and hydrochloric acids increased the rest potentia Is, while the addition of sodium sulphite decreased these potentials.

Jan 1, 1985

By M. Yavuz

Equipment selection in mining operations is an important issue, and also difficult to solve in multiple criteria environments. The paper in question has aimed to develop computer software for solving equipment selection problems in mining. In their paper, Basçetin et al. have analysed two case study problems related to open pit and underground mining method selection. By using Yager?s method1, the authors have selected 18 different criteria in the first case study and 21 criteria in the second case study. However, as emphasized by Ozdemir2, in pair wise comparison matrices the appropriate number of criteria should be seven as the maximum, from the point view of validation, consistency and redundancy. In cases where there are more than seven criteria to be handled, it is suggested that the criteria should be clustered and then the maximum number of clusters and subcriteria of every cluster should be limited to seven4.

Jan 1, 2007

By P. Kluge

Mining engineers frequently encounter complex design problems for which the critical components of the design are difficult to quantify or compare. Teams of people typically work on these designs and human perceptions and judgments play a strong role. To assist with this process, the analytical hierarchical process (AHP) as a decisionmaking tool is described in this paper. Although the technique is used in many other disciplines, it is currently not widely used in mining engineering in South Africa. To use the AHP process, the problem should be treated as a hierarchy that defines the goal, the alternatives to reach it, and the criteria for evaluation of these alternatives. Pair wise comparisons are conducted on the criteria of the hierarchy to establish priorities. The value of the technique is that it is simple to test for consistency amongst the pair wise comparisons to ensure that the answer obtained is better than that provided by a random selection. To illustrate the technique, the use of a backfill support system in a platinum mining project was investigated. Ten design parameters, which will be impacted by the use of backfill, were identified and weighted according to their relative importance. The result of the AHP evaluation was that the use of a backfill support system should be preferred to a conventional support system at the mine.

Jan 1, 2011

By R. Chryst, R. Kus

In the Integrated IT Systems proposed by Przedsie? biorstwo Robót Geologiczno-Wiertniczych—Geological and Drilling Company (PRGW) a network connects a database with all of the departments of a mining division. A key element thereof is the common graphics environment—Micro Station supplied by the firm, Bentley. PRGW’s SoftMine software and GMSI’s CadsMine that are used to design and schedule mining operate in this environment. The digital form of the design project facilitates the verification of information and the integration of technical solutions with SAP R/3 type financial—accounting systems. The system has been successfully implemented in the Brown Coal Mine in Poland.

Jan 1, 2003

The Annual General Meeting of the South African Institute of Mining and Metallurgy was held in Kelvin House, Johannesburg, on Wednesday, 27th August, 1980. Mr D. A. Viljoen (President) was in the chair and declared the meeting open at 4.05 p.m. Obituaries President: It is my sad duty to announce the death of the following members of the Institute: T. C. A. Meyer (Past President, 1941 to 1942); E. G. Harding, T. A. Stannard, C. T. Hardy, W. C. Jackson, J. S. Sinton, G. H. Duggan, H. H. A. Muller (Life Fellows); W. M. Frames, K. Gebhard, W. M. Walker, S. L. S. Swart, N. W. Stansmore, H. E. Allen, B. W. F. Towne, R. A. Wilson, D. Waterman (Fellows), R. M. Peterson (Life Member); D. L. Gibbs (Member); B. M. Williams (Asso¬ciate Member); D. B. T. Cresswell, P. G. Guernier (Associates). As a mark of respect to the memory of the deceased, and in sympathy with the bereaved, please rise and observe a few moments of silence. Notules President: Kan ons die notules van die Algemene Jaar¬vergadering, wat op 22 Augustus 1979 gehou was en in die September uitgawe van ons Joernaal gepubliseer is, bevestig? Bevestig.

Jan 1, 1980

By D. A. Viljoent

Historical Background The Empire Council of Mining and Metallurgical Institutions was formed during the early 1920s to foster the holding of British Empire Conferences, and today is representative of the following Institutes: Australasian Institute of Mining and Metallurgy Canadian Institute of Mining and Metallurgy Geological Society of South Africa Institute of Petroleum Institution of Metallurgists Institution of Mining and Metallurgy Institution of Mining Engineers Metals Society Mining, Geological and Metallurgical Institute of India South African Institute of Mining and Metallurgy South Wales Institute of Engineers. The first public suggestion for the formation of a Council that would link mining institutions in various parts of the British Empire came from Mr Frank Merricks, who, as President of the Institution of Mining and Metallurgy, was speaking at the annual dinner of the IMM in 1921.

Jan 1, 1981

By J. Whitford

The established crown pillar extraction method at Gold Fields Australia Ltd.’s Crusader Mine, leads to the significant dilution and poor recovery of ore due to caving of the overlying loose rockfill. The application of selectively injecting specifically developed ‘FB200’ ettringite (calcium sulphoaluminate hydrate) type cement grout into loose rockfill to form a stabilised rockfill material, enables an artificial crown pillar to stabilise the surrounding rock mass and prevent caving of the overlying loose rockfill during crown pillar extraction. Investigation of the geomechanical criteria for crown pillar extraction beneath stabilised rockfill has enabled the safe and efficient extraction of two crown pillars at the Crusader Mine. La méthode actuelle d'extraction des piliers horizontaux à la mine Crusader dont la propriétaire est le Goldfields Australia Ltd amène à une dilution sensible du minerai, à cause de l'effondrement du remblai peu compacté qui se trouve au-dessus. Par moyen d'injection sélective du coulis de ciment FB200 ettringite (sulfoaluminate de calcium hydraté) qui a été développé spécifiquement pour cette application, un pilier artificiel est crée et celui-ci empêche l'effondrement du remblai pendant l'extraction du pilier de minerai au-dessous. A la suite des études géotechniques de la méthode, deux piliers horizontaux à la mine Crusader ont été extraites, de manière efficace et sûr. Die feststehende Krone Pfeiler Extraktionsmethode beim Crusader Mine von Gold Fields Australien GmbH, führt wegen caving des overlying lockerer rockfill zur bedeutungsvollen Verdünnung und schlechtem Wiederfinden des Erzes. Der Antrag, ausdrücklich entwickelten 'FB200' ettringite selektiv zu spritzen, (Kalzium-sulphoaluminate-Hydrat) Art kittet Mörtelschlamm in lockeren rockfill, um ein stabilisiertes rockfill-Material zu bilden, ermöglicht einem künstlichen Kronenpfeiler, die umliegende Steinmasse zu stabilisieren und caving des overlying während des Kronenpfeilerherausziehens lockeren rockfill zu verhindern. Untersuchung der geomechanical-Kriterien für Kronenpfeilerherausziehen unter stabilisiertem rockfill hat dem sicheren und tüchtigen Herausziehen von zwei Kronenpfeilern beim Crusader Mine ermöglicht.

Jan 1, 2003

INFACON conjures up many things for many people. For the fortunate few who have been actively involved with this event since its inception, it brings back memories of far places, stimulating debates and above all, the people who have over the years contributed to the outstanding success of the Congress and who have added to the wealth of knowledge on all aspects of ferroalloys. The International Ferroalloy Congress (INFACON) has been held every three years since 1974. INFACON X will be held in Cape Town in February 2004. Simple arithmetic shows that next year?s Congress should in fact be INFACON XI. Thus, one Congress was skipped. INFACON 74, as the name implies, was held in 1974, in Johannesburg, South Africa. The event was sponsored by the Ferro Alloy Producers? Association of South Africa (FAPA), the National Institute for Metallurgy (NIM - Mintek as it is known today) and the South African Institute of Mining and Metallurgy (SAIMM). You will see some of the same sponsors involved in INFACON X. Dr. Robbie Robinson, renowned academic and past president of the SAIMM, was the Chairman of the Organising Committee. The editor was Dr. Helen Glen. Anyone fortunate enough to possess a copy of the proceedings of this first Congress will agree that from a literary and technical perspective, it is still the benchmark for subsequent events. A unique feature of INFACON 74 was the use of rapporteurs (my first duty) to ensure that the discussions following the presentations were recorded (in direct speech) as accurately as possible. This involved time-consuming correspondence (can you imagine life before e-mail?) to all parts of the world between the author and the person posing the question, with the rapporteurs acting as go-betweens. It is understandable that the much-awaited proceedings only saw the light in 1975. The names recorded in the proceedings as the members of all six committees read like the who?s-who of the South African ferroalloy industry at the time: Dr. Peter Jochens, Mr. Harvey Reid, Mr. Piet Streicher, Prof David Howat, Mr. Sigurd Selmer-Olsen - to name but a few. The Congress was held in the new, very fashionable and upmarket Carlton Hotel in the CBD. In the Foreword of the proceedings, Dr. Robinson provides an insight into the event. Three hundred and thirty six delegates from twenty two countries attended the Congress, which was opened by the Honourable P.G.J. Koornhof, Minister of Mines. Again, the opening address makes fascinating reading. During the Congress an ad hoc committee was convened as the first International Committee on the Organisation of Ferroalloys Congresses, with representation from the main ferroalloy associations of the world. The following decisions were recorded: ? The Congress would be continued at three-yearly intervals under the name of INFACON ? Every third Congress would be held in South Africa ? NIM (Mintek) would provide the permanent secretariat. Six technical sessions were held, each preceded by a plenary address with a closing address by the session chairman. In all, thirty technical papers were presented. Prior to the closing address, a panel discussion on factors affecting the future of the ferrochromium industry provided stimulating debate in the form of a question-and-answer session. The hosting country for the next INFACON would be announced. Eventually, word got round that the next INFACON would be held in Japan. However, due to unforeseen circumstances, the event was cancelled ? thus no INFACON 77. INFACON 80 was subsequently held in Lausanne, Switzerland from 12th to 16th October 1980. The event was organised by IFPEO, Institut des Producteurs de Ferro-Alliages d?Europe Occidentale. The Congress was officially opened by the President of IPFEO, Mr. R. Björklund, who was also President of the Organising Committee. The technical sessions were held in the Palais de Beaulieu. The Congress was well attended by 400 participants from 28 countries as well as 100 accompanying ladies. A total of four plenary addresses and 18 technical papers were presented. As with the first event, an international panel discussion (questions and answers) preceded the closing address. In his closing address, Dr. Louw Alberts, Chairman of the International Committee on Ferroalloys and President of NIM, presented an insight into the factors affecting growth in the industry and where growth was likely to take place. Twelve exhibitors had stands at the Congress. Attendees could choose from four post-event tours to Belguim/France (SADACEM/Compagnie Universelle d?Acetylene et d?Electro-Metallurgie), France (CUAEM), Finland (Outokumpu Oy) and Norway (Elkem Fiskaa plant).

Jan 1, 2004

By Braam Blom

PK2 Ventilation shaft is part of Paardekraal No 2 twin shaft system that is being developed to replace depleting Merensky reef production at Paardekraal shaft complex. The sinking team at this shaft faced considerable challenge of improving the total sinking cycle in order to be able to deliver the fully equipped shaft on time and on schedule. The cladding support cycle was identified as the tedious and time consuming activity in the overall shaft sinking operation. Reduction in the time required for handling and setting up the support installation equipment, and the time required for subsequent installation of the necessary support has a direct impact on the overall cycle time, and consequently the overall productivity and efficiency of the sinking operation. This reduction in support cycle was achieved by making use of machine carousel. The objective of this paper is to describe the support methodology that was used during the ventilation shaft sinking and the use of the machine carousel to reduce the cladding support cycle. The machine carousel replaces the traditional use of machine kibble in conventional vertical shaft sinking and has been designed specifically for installation of sidewall support at the shaft bottom during the sinking process.

Jan 1, 2009

By E. V. Lilford

A number of countries have introduced codes governing the valuation of mineral assets and securities. The African continent will follow suit in due course considering the importance of the global minerals industry as it relates to the attraction of foreign investment. South Africa is to introduce the Petroleum and Minerals Development Bill legislating the involvement of previously disadvantaged individuals and communities in the country?s minerals industry. One of the challenges facing the successful implementation of such codes and bills lies with the abilities of independent valuators to value mineral properties and projects on a consistent basis. Certain valuation principles and methodologies are applicable in all jurisdictions in the minerals industry. These valuation tools and principles are considered and developed in this report. They have been discussed and developed to encourage minerals valuators to consider and consistently apply the most applicable valuation methodologies.

Jan 1, 2002

By GA Harrison

The introduction of Extra Low Profile (XLP) mechanised equipment within Anglo Platinum is aligned with the overall New Mining Technologies strategy to focus on continuing modernization of our mining operations to achieve injury free sustainable production and cost effective mining technologies. The method allows for the introduction of a suite of XLP and Low Profile (LP) equipment in a narrow reef (1,2m) mining environment. For the first time it is now possible to achieve total trackless mechanisation at these stoping widths and XLP Breast mining has the potential to add more value when benchmarked with conventional mining and other mechanised methods. Various types of XLP equipment were tested at different sites within Anglo Platinum and this paper describes the XLP equipment evolution to-date. It concludes with recommendations on our future strategy regarding implementation and roll out of the XLP technology within Anglo Platinum.

Jan 1, 2008

By B. J. Ralph, I. J. Corrans, B. Harris

In the first section, a brief background to the practical and theoretical aspects of bacterial leaching is presented. Descriptions are given of present and potential methods for exploiting bacterial leaching in metal-winning. In the second section, the results of recent research are presented. The aim of this work was to obtain a greater understanding of the mechanism of bacterial leaching of sulphide minerals. Bacteria were observed to catalyse leaching reactions by oxidising ferrous ions to ferric ions, by removing protective films at the mineral surface and by depolarising cathodic areas.

By J. A. L. Napier, J. S. Kuijpers

SYNOPSIS This paper demonstrates that the horizontal stresses induced by the creation of a tabular scope in a single mining step are always tensile at the centre of the stope span, but that compressive stresses are actively generated in hangingwalls and footwalls during sequential mining. A stress-distribution mechanism is introduced, and is used to explain the results for elastic behaviour, and for inelastic behaviour both during a single mining step and during multiple mining steps.

Jan 1, 1991

By P. Falcão Neves

A detailed analysis of the geomechanical behaviour in rock cutting with a diamond saw is provided to obtain a better understanding of the mechanisms involved in the process. The energy of elastic deformation (before failure) and plastic deformation (post failure) was determined in uniaxial compression tests as well as the energy consumed per unit volume in the cutting process. The test samples are White and Ruivina marbles from Borba - Vila Viçosa in Portugal. Correlations between total deformation specific energy and cutting specific energy, normal and tangential forces and diamond indentation are analysed, and some conclusions are presented.

Jan 1, 2012

By M. A. Kujoana

Following on the design of good mining layouts and regional support systems, and the implementation of sound strata control practices, stope support is the ultimate strategy to combat the hazards of rockfalls and rockbursts. The primary function of stope support in intermediate and deep level mines is to stabilize the rock mass immediately surrounding stoping excavations, that is, the zone of fractured rock which behaves in elastically around stopes. Support design is a process resulting in a support system which is both practical and meets or exceeds by a factor of safety the requirements for a particular geotechnical environment. The aim of this project was to design a support system, which accommodates the factors of rockfalls and rockbursts. The pack support unit must be easily handled, less costly and can be used in stopes without any significant convergence. The project tested the structural stability of packs to their expected deformation, in order to design a height to width ratio for stopes where little convergence is expected.

Jan 1, 2009

By P. Falcão Neves

A detailed analysis of the geomechanical behaviour in rock cutting with a diamond saw is provided to obtain a better understanding of the mechanisms involved in the process. The energy of elastic deformation (before failure) and plastic deformation (post failure) was determined in uniaxial compression tests as well as the energy consumed per unit volume in the cutting process. The test samples are White and Ruivina marbles from Borba - Vila Viçosa in Portugal. Correlations between total deformation specific energy and cutting specific energy, normal and tangential forces and diamond indentation are analysed, and some conclusions are presented.

Jan 1, 2012

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