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By S. Banisi, M. R. Yarahmadi, S. R. Mortazavi

Nowadays the development of automatic on-line sampling systems has enabled large amounts of data to be available to plant managers. These data are inevitably prone to random and sometimes systematic errors. Data reconciliation methods are used to deal with random errors. In these methods, the measured data are adjusted in accordance to their error, so that the mass conservation law is satisfied at the same time. Measured data may also contain systematic errors, using these data in mass balancing software will result in inaccurate or even irrational results. In this paper three methods for detecting systematic errors (global test, node constraint test and maximum power constraint test) were presented. A step by step method to locate the systematic errors was demonstrated. Then, the new version of Movazen©, a mass balancing software, was introduced and used to locate systematic errors in the measurements taken from the Sarcheshmeh pilot plant copper flotation circuit. Keywords: Mass balancing, data reconciliation, random error, systematic error

Jan 1, 2020

By A. Melkumyan, K. Silversides

Chemical assays collected from blast holes have the potential to greatly improve the local accuracy of grade models. Assays must be assigned to the correct domain or they will introduce errors. Boundary surfaces created from the widely spaced exploration holes (~50m) do not provide sufficient resolution to correctly delineate domain boundaries between closely spaced (3-5m) blast holes. This paper demonstrates a probabilistic method for classifying production blast holes near domain boundaries. Gaussian processes models are applied to identify the assays and assay ratios most suited to distinguishing particular domains. These models are combined with the exploration based surfaces to classify the blast holes that can be confidently assigned to a particular domain. A reiterative method is used, where information from the blast holes closest to the exploration holes is used to label blast holes further away. This is tested on two domain boundaries in a banded iron formation-hosted iron ore mine.

Sep 1, 2021

By A. Tosun

Muckpile fragmentation formed by blasting depends on the specific charge factor, the discontinuities in the rock mass, and the rock strength. Determination of the discontinuity characteristics and rock strength is a long and difficult process. These two parameters are directly associated with the rock drilling speed. Therefore, it is the drilling speed of the machine used for the blast-hole, rather than the blasthole discontinuity characteristics and rock strength parameters, that is used in the prediction of muckpile fragmentation before blasting. Primarily, it has been suggested that the muckpile fragmentation values can be correctly determined by establishing correlations between the efficiency of the loader and muck pile fragmentation, since fragmentation is directly correlated with the former parameter. Subsequently, a correlation predicting the drilling speed of the drill machine was developed according to the discontinuity characteristics of the blasting surface and the rock strength. Finally, a correlation was developed predicting muckpile fragmentation according to the specific charge factor and the drilling speed of the drill machine The data was obtained by conducting blasting tests in two different limestone quarries.

Nov 30, 2022

By A. W. Cramb

A three-day symposium on the production of clean steel organized by The South African Institute of Mining and Metallurgy, was held in September 1995 at Vanderbijlpark. It was attended by 151 delegates, who represented the whole of the steel industry in South Africa: Iscor Works, Saldanha Steel, Columbus Stainless, Highveld Steel & Vanadium, Iscor Research & Development, University of Pretoria, and Technikon Witwatersrand, as well as the users of steel products were represented. Professor Allan Cramb held the delegates attention with well-presented research and practical information. He obtained excellent interaction with the delegates by responding in depth to the questions put to him during the Symposium. In summary, he emphasized the following aspects of the elimination of defects during the processing of steel in continuously cast materials.

Jan 1, 1996

By H. S. Sichel

"The valuation of diamond ferous deposits depends on (i) the density distribution, (ii) the size distribution of stones and (iii) the selling price structure prevailing at a particular time.In the density distribution the stochastic variable is defined as the Dumber of individual stones found per sample unit irrespective of the stone size. The density distribution is discrete and allows for barren sample units.As diamonds often occur in clusters, a Poisson mixture distribution is derived which is entirely new, as existing discrete distributions cannot represent the stone number frequencies found in nature.For the sizes of diamonds, which are measured by weight, a new compound logarithmic normal distribution is developed.Combination of (i), (H) and (iii) leads to a meaningful appraisal of diamond ferous ground expressed in monetary value per production unit of mining.Finally, confidence limits are calculated which allow for inference from sampling to recovery."

Jan 1, 2014

By L. Robles-Stefoni

"Multiple-point simulation (MPS) methods have been developed over the last decade as a means of reproducing complex geological patterns while generating stochastic simulations. Some geological spatial configurations are complex, such as the spatial geometries and patterns of diamondbearing kimberlite pipes and their internal facies controlling diamond quality and distribution.Two MPS methods were tested for modelling the geology of a diamond pipe located at the Ekati mine, NT, Canada. These are the single normal equation simulation algorithm SNESIM, which captures different patterns from a training image (TI), and the filter simulation algorithm FILTERSIM, which classifies the patterns founded on the TI. Both methods were tested in the stochastic simulation of a four-category geology model: crater, diatreme, xenoliths, and host rock. Soft information about the location of host rock was also used. The validation of the simulation results shows a reasonable reproduction of the geometry and data proportions for all geological units considered; the validation of spatial statistics, however, shows that although simulated realizations from both methods reasonably reproduce the fourth-order spatial statistics of the TI, they do not reproduce well the same spatial statistics of the available data (when this differs from the TI). An interesting observation is that SNESIM better imitated the shape of the pipe, while FILTERSIM yielded a better reproduction of the xenolith bodies. IntroductionThe simulation of geological units poses several technical problems that challenge the capabilities of available geostatistical simulation approaches and their ability to deal with spatial complexity of categorical variables. The spatial geometry of diamondbearing pipes and their internal facies controlling diamond distributions are a specific and well-known difficult modelling problem. The geometry of a kimberlite pipe is typically like an inverted cone (Figure 1); the wider part is known as the crater and is located near the surface, and the narrower, deeper part is known as the diatreme. Xenolith bodies can also be found inside the pipe. A very important contribution to the geological modelling of the contours of the pipe is the measure of uncertainty about the location of the contact between the kimberlite pipe and the host rock."

Jan 1, 2016

By Sylvie Poirier

Researchers at Natural Resources Canada (NRCan) CANMET Mining and Mineral Sciences Laboratories (CANMET-MMSL) and Mining Technologies International (MTI) have designed and built a hybrid diesel-electric mining loader that is the first of its kind to be developed for underground mines. Diesel equipment is popular because of its mobility and most mining operations are reluctant to replace it with tethered electrical equipment despite the obvious elimination of diesel contaminants and significantly lower heat generation (? 35% of an equivalent diesel). However, a diesel-electric vehicle, being currently evaluated by CANMET-MMSL, could be beneficial. In this unit, a constant load diesel generator feeds batteries which, in turn, powers electrical motors that drive the equipment. In a hybrid diesel-electric unit, the constant load diesel generator can be optimized for minimal emissions and hence lower dilution air requirements. This paper will present the project status and the anticipated benefits for mining operations through the application of this technology.

Jan 1, 2008

By A. N. Brown

The Hendrik van der Bijl Memorial Lecture is arranged annually under the auspices of the Pretoria Engineers Liaison Committee. This is a multidisciplinary Committee with representatives from eleven societies and associations, and serves the interests of engineers resident in the Pretoria area. Coal preparation The Japanese Organizing Committee of the 11th International Coal Preparation Congress is now busy making the necessary arrangements for the Congress, which is to be held in Tokyo from 22nd to 26th October, 1990.

Jan 1, 1989

By C. Liu, G. Zhu, Y. Liao

"The effect of particle size on the flotation kinetics of a low-rank coal was compared using air bubbles and oily bubbles. Five kinetic models were applied to the data from the tests to derive the relationships between the flotation rate constant, the ultimate recovery, and the particle size fraction. The results show that oily bubble flotation (OBF) resulted in a lower ash content and higher combustible recovery than air bubble flotation (ABF), especially for the -125 ??m size fraction. It was found that the flotation of a low-rank coal in individual size fractions using air bubbles and oily bubbles can be best described by a first-order model with rectangular distribution of tendency to float and the classical first-order model respectively. OBF yielded higher ultimate combustible and ultimate ash recoveries. The flotation rate constants for OBF were higher in all the models except for the fully mixed reactor model. The ultimate recovery values and modified rate constants first increased and then decreased as the size fraction decreased. The trend of the flotation rate constants as a function of the size fraction was similar in all the models except for the fully mixed reactor model. IntroductionFroth flotation is a physical-chemical separation method that is widely used in coal beneficiation for the separation of fine coal particles from associated minerals in water slurries. Since the cumulative recovery of a component in the concentrate is proportional to flotation time, the flotation process can be considered as a time-rate recovery process (Emad, Mohammad, and Bahram, 2010). Therefore, the general mathematical flotation models that incorporate both a recovery and a rate function can describe flotation time recovery profiles.The kinetics of coal flotation, as a measure of coal recovery as a function of time, have been studied in detail by many researchers. Different kinetic models have been proposed and published in the literature. The order and the rate constant are strongly dependent on the flotation conditions, such as the particle size and size distribution, the bubble concentration, the reagent concentrations, and the operating parameters (Zhang et al., 2013). The particle size has been reported to affect the flotation kinetics to a great extent (Yoon, Luttrell, and Asmatulu, 2002; Ntengwe and Witika, 2011). Numerous researchers have studied the aspects of flotation kinetics while paying special attention to particle size (Meftuni and Ibrahim, 1997; Rubinstein and Samygin, 1998; Graeme, 2012). However, the effect of particle size on the flotation kinetics of a low-rank coal has been relatively little discussed."

Jan 1, 2017

By K. Thambi

"A recent amendment to Section 36(11)(e) of the Income Tax Act, 53 of 1968 (Tax Act) now extends the allowable deduction of ‘capital expenditure’ incurred by mining companies pursuant to the Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA). In terms of the Taxation Laws Amendment Bill 2016 (TLAB 2016), the allowable deduction has been extended to include expenditure incurred on infrastructure in terms of Social and Labour Plan (SLP) requirements as per the MPRDA. Interestingly, what necessitated the amendment was the need to recognize SLP requirements and to circumvent administrative difficulties for mining companies and the South African Revenue Services (SARS) in differentiating the use of developmental infrastructure by employees or the community. The successful implementation of such a deduction hinges on a sound SLP system. However, given the challenges within the current SLP system, this amendment could be considered somewhat premature. IntroductionSection 36(11) of the Income Tax Act 58 of 1962 (Tax Act) enabled mining companies to deduct certain capital expenditure in lieu of its other sections. In particular, it made provision for mining companies to deduct capital expenditure incurred pursuant to the Mineral and Petroleum Resources Development Act 28 of 2002 (MPRDA), but excluding capital expenditure incurred in respect of infrastructure or environmental rehabilitation. As such, mining companies could only deduct such capital expenditure that related directly to their employees and not to the wider community (Clegg, 2018).In terms of the Taxation Laws Amendment Bill 2016 (TLAB, 2016) (South Africa, 2016a), the recent amendment to Section 36 extends the relief provided under section 36(11)(e) to include capital expenditure incurred on infrastructure in terms of the Social and Labour Plan (SLP) requirements of the MPRDA. In other words, the capital expenditure incurred by the mining company for the benefit of the people living in mining communities. To qualify for such a deduction, the infrastructure erected or developed by the mining company should reflect what was agreed between the mining company and the Department of Mineral Resources (DMR) as per the SLP requirements of the MPRDA (TLAB 2016)."

May 1, 2019

By M. Hermanus, N. Coulson, N. Pillay

"SynopsisThis paper assesses the effectiveness of the Mine Occupational Health and Safety Leading Practice Adoption System (MOSH) and its potential to improve mine health and safety in South African mines. Developed by the Chamber of Mines, which represents the majority of the country's large scale mining employers, MOSH was devised to accelerate progress towards achieving health and safety milestones, which were set by tripartite agreement in 2003. The paper documents and builds on the findings of a study conducted by the Centre for Sustainability in Mining and Industry (CSMI) in 2011 that evaluated MOSH strategy, structures, and process of implementation.The study found that MOSH operated across the mining sector, was directed and dominated by experts and, despite best efforts to include other stakeholders, was led by employers. Statutory worker health and safety representatives and structures were not integrated into the complex change process developed by MOSH. The Mine Health and Safety Inspectorate (MHSI) and organized labour were ambivalent about direct involvement in MOSH and preferred regulatory measures to enforce the participation of mines. MOSH interventions were not targeted at mines with a poor health and safety record, and MOSH lacked a baseline from which to track impacts on sector-wide health and safety performance. The leading practices most widely adopted by mines were designed to improve, rather than fundamentally alter, existing practice. Although the depth of engagement with MOSH among stakeholders and on mine sites varied, mining companies, labour representatives, and the Mine Health and Safety Inspectorate (MHSI) saw the programme as significant.IntroductionIn 2011, the Chamber of Mines commissioned the Centre for Sustainability in Mining and Industry (CSMI) to evaluate the progress and effectiveness of the rollout of the Mine Occupational Health and Safety Leading Practice Adoption System (MOSH). CSMI, based in the School of Mining Engineering at the University of the Witwatersrand, is an independent research centre conducting health and safety research relevant to all major stakeholders in the mining sector. The purpose of the evaluation was to identify the factors that enabled or hampered the adoption of new technologies or practices. The timing of the evaluation, two years before the deadline for the 2013 safety and health milestones, allowed time for adjustments to be made. This paper summarizes the results of the evaluation and includes further analysis and discussion of the nature of the programme and the conditions that act to advance it or it hold back."

Jan 1, 2015

By N. Mashaba, D. Botha

The aims of this study were to investigate the factors that influence women’s engagement in technical positions in the South African mining sector and to determine what could be done to promote their successful participation. A convergent parallel mixed-methods research design was used to ascertain the factors that facilitate, inhibit, and influence engagement. In the quantitative phase of the study, questionnaires were circulated to women employeees; and in the qualitative phase, semistructured interviews were conducted with employer representatives, most of whom were human resource personnel. Confirmatory factor analysis showed that the three-factor structure (vigour, dedication, and absorption) of the Utrecht Work Engagement Scale fit the sample data reasonably well. Although there is room for improvement, respondents demonstrated acceptable levels of engagement in their work. On the other hand, the qualitative findings showed that employee engagement is impacted by unfavourable working conditions, work–life balance, and the mining industry’s male-dominated work culture. The findings showed that employee engagement should be elevated to a core human resource function. To increase the participation of women in mining, human resource professionals are encouraged to collaborate with mine supervisors, managers, and employees to develop programmes that promote employees’ absorption in and dedication to their work.

Nov 6, 2023

By E. C. de Beer

"SynopsisA number of important areas in nuclear fuel cycle, at both the front end and back end, offer ideal opportunities for the application of non-destructive evaluation techniques. These techniques do not only provide opportunities for non-invasive testing of e.g. irradiated materials, but also play an important role in the development of new materials in the nuclear sector. The advantage of penetrating radiation used as probe in the investigation and testing of nuclear materials makes X-ray and neutron radiography (2D) and tomography (3D) suitable for various applications in the total nuclear fuel cycle. The unique and different interaction modes of the two radiation probes with materials provide several opportunities. Their complementary nature and non-destructive character makes them most suitable for nuclear material analyses, analytical method development, and the evaluation of the performance of existing nuclear material compositions. This article gives an overview of the X-ray and neutron radiography/tomography applications in the field of nuclear material testing, and highlights a few of the success stories. Several selected areas of application in the nuclear fuel cycle are discussed to illustrate the complementary nature of these techniques as applied to nuclear materials.IntroductionDuring the development of new materials for the nuclear industry, materials testing and characterization are of the outmost importance to maintain safety standards and reliability. No compromise on safety in the workplace in any area within the total nuclear fuel cycle can be tolerated, and therefore most in-situ material characterization and testing is conducted by certified and qualified personnel schooled in destructive and non-destructive testing (DT and NDT) methods. Certification and qualification in NDT can be obtained through many training centres in South Africa in accordance with European, American, and other international standards (SGS, n.d.; SAIW, n.d.; African NTD Centre, n.d.)."

Jan 1, 2015

By L. Chanderman, C. E. Dohm

"Mineral Resource estimation (MRE) and classification are highly dependent on the confidence in the model of the orebody geometry, known as the geological model, within which the estimates are constrained. An understanding of the geology of a deposit is thus fundamental to the Mineral Resource evaluation process. The geological model is a function of the structural and depositional complexity of the geology captured by drilling information, which is limited in the early stages of a project. The information effect has a significant impact in terms of the interpretation of the geology as well as the estimation of grade continuity and the resultant risk associated with the Mineral Resource estimate and classification.Therefore, as new drilling information becomes available, it is necessary to update and refine the geological model to appropriately constrain the resource estimates. The grade information is also updated, including statistics and the spatial correlation characteristics. This refinement is based on geological interpretations derived from the drillhole information that becomes available throughout the life of the mine; orebody knowledge that comes from working experience of the deposit, as well as familiarity with the software package used for modelling, is also important.In updating, the potential to identify new resources in previously unknown areas may be realized. The opposite may also occur where previous interpretations of ore continuity are refuted. Both scenarios could result from a better understanding of the geology of the deposit and thus a more realistic MRE, which reduces geological risk. This paper describes how newly drilled advanced grade-control holes for a gold deposit in Mali were used to refine the 3D geological model for the deposit in an attempt to identify the potential for additional oxide ore using conventional geostatistical evaluation techniques."

Jan 1, 2017

By G. C. Thompson

'Increased underground extraction of coal' was the theme selected for the 1981 mining vacation school, which was held at the University of the Witwatersrand in January and February. The response of the industry to the invitation to register was so good that three separate schools of one week each were arranged between 26th January and 13th February. In terms of the total number of delegates, some 225 actually attending, the school can be described as the most successful ever organized by the Institute.

Jan 1, 1981

By S. Marx

More than twenty years ago Sasol, ISCOR, and some parastatals played a major role in ensuring that South Africa had sufficient technical skills. When the economy became tight and business and government were pressurized to decrease costs, the first budgets that were reduced were the training budgets. It seemed to be too expensive and too time-consuming to train apprentices. According to Stacey2, this is a major strategic issue facing the mining industry in South Africa. Two factors added to the shortage of skills challenge: ? Skills erosion and job losses ? Artisans ? currently the economy produces 5 000 but the need is 12 500 ? Level of mechanization in South Africa less than 10 per cent ? Average age of operators and artisans is 50 ? Greater awareness of occupational health effects of hand-held drilling. ? Workplace challenges ? The impact of HIV/AIDS and other employee wellness issues ? Changes and challenges in workplace environment i.e. the mining industry.

Jan 1, 2012

1. Book reviews Phosphate rock, a bibliography of world resources. London, Mining Journal Books Limited, 1984. £10 (surface mail), £12.25 (airmail). Reviewer: P.Le. Grubb Ok Tedi, by William S. Pintz. London, Mining Journal Books Limited, 1984. 206 pp. £19 (surface mail), £22.25 (airmail). Reviewer: R.P. Plewman 2. Publications of the Canadian Mineral Policy Sector Lime by D.H. Stonehouse. 5 pp. Phosphates by G.S. Barry. 9 pp. Statistical summary of the mineral industry in Canada. 77 tables. Talc by M. Prud'homme. 6 pp. Zirconium by M.A. Boucher. 6 pp. Cement by D.H. Stonehouse. 13 pp. Gypsum and anhydrite by D.H. Stonehouse. 7 pp. Regional review by T.M. Buch. 12pp. SaltbyG.S. Barry. 7pp. Silicon, ferrosilicon and silicon carbide by D.G. Law-West. 6pp. SulphurbyB.W. Boyd. 9pp. Mineral Report 31. Canadian Minerals Yearbook 1981. Available from the above address at $40.75 per copy. 3. Mintek reports Report M18D The recovery of pyrite and gold from acid-leach residues from the Merriespruit Gold Mine. (First issued Feb. 1982; reissued Mar. 1984). Report M2OD The separation of ore from Cooke into high- and lowgrade fractions. (First issued Feb. 1982; reissued Mar. 1984). Report M33D Explanatory tests on the reduction of the sulphur content of sponge iron. (First issued Apr. 1982; reissued Mar. 1984). Report M43D Beneficiation tests on andalusite-bearing shales from a farm near Thabazimbi. (First issued Aug. 1982; reissuedMar. 1984). Report M129 The determination of tin, niobium, and tantalum in pegmatite by X-ray-fluorescence spectrometry. ReportM131 The determination of copper and nickel in iron- and chromium-bearing materials by a pressed-powder technique and X-ray-fluorescence spectrometry. Report M135 The installation of a 100 kV A plasma furnace at Mintek. The selection and installation of a 100 kV A a.c. plasma Report M136 The determination of gold in activated charcoal by use of a loose-powder technique and X-ray-fluorescence spectrometry. Report M140 The effect of physical and chemical factors on the corrosivity of a synthetic mine water.

Jan 1, 1984

By S. Heukelman

Zincor uses O2 enrichment (up to 26% O2 in the fluidizing air) to increase the processing rate of zinc concentrates in the fluidized bed roasters. The aim of this study is to determine whether O2 enrichment can be reduced by introducing micro-pelletized concentrate into the feed blend, while maintaining current roaster feed rates and calcine quality. It was found that, with a load of 20% micro-pellets introduced into the feed blend, that O2 enrichment could be reduced by 60%. It was determined that entrained particles spend on average between 0.46 hour and 2.44 hour in the roaster, compared to particles remaining between 3.93 hour and 4.00 hour in the bed overflow. This compares well with a radioactive tracer test performed by Spira. The required reaction time for micro-pellets was found to be less than the residence time inside a Zincor roaster. The result achieved indicated that the average particle residence time inside the roaster was increased successfully in order to compensate for the longer reaction time required to roast micro-pellets at lower levels of O2 in the fluidizing air.

Jan 1, 2011

FEBRUARY GENERAL MEETING The January General Meeting of the Institute was held in Kelvin House, Johannesburg on 21st January, 1970, at 4.30 p.m. Mr V. C. Robinson (Vice-President) was in the Chair. There were also present eighteen Members, Messrs M. Barcza, A. R. C. Fowler, R. C. J. Goode, Prof J. de V. Lambrechts, Messrs T. C. A. Meyer, J. A. Nixon, V. C. Robinson and P. W. J. van Rensburg (Council Members), C. A. Border, D. F. H. Grave, S. D. Hill, A. F. Lee, W. L. le Roux, C. S. Macphail, D. L Starkey, S. G. Taussig, W. T. L Wayman and Dr A. Whillier. Three Associate Members, Dr M. I. Brittan, Messrs R. Hemp and M. J. Martinson. One Student, Mr R. P. W. Henrard. Two Visitors, Dr N. G. W. Cook and Mr J. B. Smith. Secretary, Mr D. C. Visser. Total present: Twenty-six. 1. OBITUARY The Vice-President: "It is my sad duty to announce the death of the following members of the Institute: Reginald Gordon McConnell, Member, who joined the Institute on 24th April, 1946 and passed away on 26th September, 1969. James Henry Moore, Member, who joined the Institute on 28th February, 1951 and passed away on 2nd January, 1970. As a mark of respect to the memory of the deceased and in sympathy with the bereaved I would ask those present to stand and observe a few moments silence." 2. MINUTES The Vice-President: "May we confirm the Minutes of the General Meetings held on 15th October and 19th November, 1969, as published in the December, 1969 issue of the Journal?" 3. MEMBERSHIP The Vice-President: "I have pleasure in announcing that the names of the under-mentioned candidates, having been published in accordance with By-Law 5.2.2, Council has elected them to membership of the Institute in the following grades: Member: Woodford Anson Gilbert. Associate Members: Michael John Harvey Tonking, Schalk Willem Vorster, Edward Alfred Cole, Johannes Godlieb Bosch. Graduate: Leonard Raymond Kilpatrick. Affiliates: Clive Frere Knight Pouiton, David Philip Ayliff, Kenneth Gillings, Edward Gilbert East. Students: Stirling Graham Low, Petrus Stephanus van der Merwe, Louis Johannes Fourie, Clive Maxwell Winterstein. MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate Member to Member: Albert Arthur Hazell, Neville Martin Hayne. "I welcome the newly elected members to the Institute and congratulate the members who had been transferred to a higher grade. 4. GENERAL BUSINESS The Vice-President: "I wish to announce that except for the student prizes awarded at the November meeting, Council has decided to make no awards for 1969. Are there any further matters to raise under the heading of General? If not, we will proceed to the next item on the agenda which is the presentation of tonight's paper. 5. PAPER FOR PRESENTATION The Vice-President: "Professor Starfield may I call on you to deliver the paper entitled "A rapid method of calculating temperature increases along mine airways". After the presentation of the paper, the Vice-President said: The Vice-President: "Thank you very much, Professor Starfield. Gentlemen, I think that many of you here, who have to do with the design of mines in an age where costs and difficulties generally, are increasing at a rate which we find almost impossible to keep up with, I would agree with you that we are fortunate to have a band of people like Professor Starfield, and others who are dedicated to producing the tools, and methods which we need to sort out these problems. I am sure that you would agree with me, that the old rule-of-thumb methods are finished forever, that we can never go back to the methods which served us in the past, when we were close to the surface and had not met the conditions which we are meeting now, and which we are going to meet in an increasing degree in the future. It is to people like Professor Starfield, with these clear, completely logically described new methods, that we look for the solution of our problems in the future. I think the whole problem of layout of any mine, is one where you can reliably prognosticate what you are likely to find in a variety of circumstances to meet the wide range of things which must happen when you consider the costs in these modern operations. Thank you very much, Professor Starfield, for coming and giving us this paper. Thank you for making plain to me how these mathematical models of yours are used. I am sure that what you have said will be a very valuable addition to the archives of this Institution. Thank you very much, indeed, and Gentlemen, will you please show your appreciation in the normal way." (Applause). Professor J. de V. Lambrechts, Mr R. Hemp and Dr A. Whillier then contributed to the discussion. (These contributions will appear in a later issue of the Journal.) PAPERS OPEN FOR DISCUSSION The Vice-President: "Listed on the agenda are papers open for discussion. I would suggest that anyone wishing to contribute to these papers submit their contributions to the Secretary in writing." CONCLUSION The Vice-President: "I wish to thank members and visitors for their attendance, and now declare the meeting closed." The meeting closed at 5.30 p.m

By A. Nhasengo

Paper written on project work carried out in partial fulfilment of B. sc. Eng (Mining Engineering) The purpose of this investigation was to assess the mining strategy for steep reefs at Mine A mine in 2005 and 2006. Reefs steeper than 35° were discovered when production commenced at the mine. At that time reefs steeper than 35° were not popular in South African tabular gold mines, therefore new techniques of mining them had to be developed. The underhand mining method was chosen for this purpose. The project was about assessing ventilation, support costs, local support cycles, adherence to the mine?s support standards, mine planning and efficiencies of the underhand mining method. The project work was covered by doing a literature research for underhand mining methods and performing a literature review of the mining methods, support methods, ventilation standards at Mine A. Underground visits were conducted at Mine A mine for data collection, and Mine B was visited to obtain information on support costs and efficiencies. During the investigation it was realized that the underhand mining method was an appropriate method for mining steep reefs; however, there were some challenges related to ventilation and support installation. Efficiencies could be realized with the underhand mining method and planning and scheduling were not different from breast mining.

Jan 1, 2007