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By S. Z. Pethö

Pillar extraction at shallow depths with small pillars that were not originally intended for secondary extraction can provide a huge benefit to the coal mining industry in those areas where a significant percentage of the remaining coal reserves are locked up in small pillars at shallow depths and where opencast mining methods are simply not as cost-effective and practical to implement. A system considering all of the pertinent geotechnical and mining aspects for the safe and efficient pillar extraction of small pillars at shallow depths at Xstrata Coal South Africa (XCSA) has been further developed and implemented as part of an ongoing improvement process addressing all of the relevant legal and associated risk aspects. This work follows on from the previous pillar extraction work carried out at the ATC, Boschmans, and Spitzkop Collieries. The process involved a number of in-house workshops and sessions arranged with all key personnel from Tavistock Colliery, and also included Professor Nielen van der Merwe of the University of the Witwatersrand, a world renowned authority on pillar extraction, towards reviewing and developing the Modified NEVID pillar extraction system employed previously at Boschmans Colliery. The system is currently being employed at Tavistock Colliery with success and no major accidents, with around 655 000 t of coal having been successfully extracted from the pillar extraction panels.

Jan 1, 2012

PREFACE During the past year, considerable effort was devoted to the implementation of the strategic plan that was adopted by the SAIMM in 1986. Good progress was made in a number of areas, while in others the foundation was laid for future progress. Key Objective of the Institute The key objective of the SAIMM is as follows: To identify the needs of its members and to initiate and give effect to the means whereby the requirements for technology and scientific knowledge of the minerals and metals section of the South African economy are satisfied; and to represent and promote the interests of its members.

Jan 1, 1987

The Steering Committee for Minerals and Mining Policy convened two workshops during March 1996 to address the following topics: Business Environment- National and Provincial Powers, Administration and Regulation, Mineral Marketing, Beneficiation, Research and Development, Environmental Issues, Mining Impact on Surface Usage, Southern Africa Regional Issues. Human Resources: Elementary Residual Racism, Housing, Downscaling, Migrant Labour and Human Resource Development. Mineral Tenure: Mineral Rights, System of Access to Mineral Rights, Access to Exploration information, optimal Exploration, Trust Lands. Small-scale Mining. Development of Small-scale Mining, Artisanal Mining.

Jan 1, 1996

By W. D. Northrop

This paper gives an account of the development of a technique whereby the vertical limits of geological horizons may be identified by the use of vertical variograms on the mineral of economic interest. This information may supplement or guide the correct subdivision of the individual horizons into meaning full data sets by diligent geological observation. This process then improves the quality of the variance modelling of the gold distribution in the plane of the individual layers and therefore enables better estimates to be made into the grids or blocks of the mine model. The technique is explained by an account of the development work, which was performed, on duplicate superimposed reef horizons in the Kimberley formations. The paper then shows how the correct approach was developed to evaluate the mineralized layers in a multiple stacked conglomerate layer sequence in the Elsburg reefs of the Witwatersrand Rand System at the Target deposit. The method of categorization of resources according to confidence in the estimate is also explained. The feasibility processes carried out on the three-dimensional model, in accordance with the SAMREC code are also described. An example of the development of a reconciliation process utilizing chip sampling is also explained.

Jan 1, 2003

By R. Ribacchi, P. Tommasi, C. Consorti, P. Campedel

The runout of dry blocky rock avalanches produced by planar rockslides affecting a limestone formation with clayey interbeds is analysed by means of distinct element modelling. Numerical analyses are validated by means of the back analysis of a historical rockslide occurred in the investigated area and physical aspects of the phenomenon evidenced by modelling are discussed. On analyse par la méthode aux élements distincts la distance de parcours des avalanches rocheuses sèches produites par des glissements plan interessant une formation de calcaire à intercalaires argilleux. Les analyses numeriques sont validées à l’aide de la back-analysis d’un glissement historique survenue dans le site en examen. On décrit les aspects physiques su phénomène mis en évidence par la modélisation efféctuée. In diesem Beitrag wird die Reichweite von Steinlawinen besthend aus trockenem blockhaftem Fels mittels der Distinct Element Methode untersucht. Die Steinlawinen werden erzeugt von Rutschungen in einer Kalkstein-Formation mit tonhaltige Schichten betreffen. Die numerischen Berechnungen wurden anhand einer Simulation einer historischen Bergsturzen verifiziert, der sich auf den untersuchten Gebiet ereignete. Auf der Basis der erhaltenen Ergebnisse wurden die physikalischen Aspekte der untersuchten Steinlawinen analysiert.

Jan 1, 2003

By C. -I. Lee

Since the early 1970s, Korea has constructed many large-scale tunnels and underground storage caverns in response to the rapid industrial development. The rock mechanics engineers have accumulated valuable experiences in the area of underground space technologies. But they still face technical challenges in environmental and safety aspects. To discuss those challenges in Korea, a brief engineering description of underground space projects including oil and gas storage, food storage, pumped storage power plant, transportation tunnels, waterway tunnels, and radioactive waste disposal is presented. Mechanical and hydrological stability analyses of the storage caverns in Korea are also introduced. Depuis le début des années soixante-dix, le développement industriel rapide en Corée a entraîné la construction de nombreuses galeries et cavernes de stockage souterraines. Les ingénieurs de mécanique minière ont donc accumulé des expériences précieuses dans le domaine de la technologie de l’espace souterrain. Cependant, ils font toujours face à de nombreux défis techniques en ce qui concerne les aspects de l’environnement et de la sécurité. Pour présenter ces défis en Corée, l’étude présente décrit les projets d’espace souterrain, y compris le stockage de pétrole et de gaz, de nourriture, centrales de stockage pompé, tunnels de transport, tunnels navigables, et évacuation des déchets radioactifs. Des analyses de stabilité mécanique et hydrologique des cavernes de stockage en Corée sont aussi présentées. Seit Anfang der 70er-Jahre, baute Korea in Folge raschen Industriewachstums viele lange Tunnelsund unterirdische Lagerungsräume. Fachkräfte im Bereich Gesteinsmechanik sammeltenwertvolle Erfahrungen über unterirdische Raumtechnologien. Dennoch stehen sie auch heute nochvor technischen Herausforderungen im Bereich Umweltschutz und Sicherheit. Zur Erläuterungdieser Herausforderungen in Korea folgt eine kurze technische Beschreibung der Projekte zurSchaffung unterirdischen Raumes für beispielsweise Öl- und Gaslagerung,Nahrungsmittellagerung, Pumpspeicherwerke, Straßen- und Wasserstraßentunnels, als auchLagerung radioaktiven Mülls. Mechanische und hydrologische Stabilitätsanalysen derLagerungsräume in Korea werden ebenfalls dargestellt.

Jan 1, 2003

The February General Meeting of the Institute was held in Kelvin House, Johannesburg, on 19th February, 1969 at 4.30 p.m. Mr R. C. J. Goode (President) was in the Chair. There were also present forty-six Members, including Messrs H. E. Cross, A. R. C. Fowler, P. Lambooy, D. G. Maxwell, Dr J. T. McIntyre, Messrs J. A. Nixon, V. C. Robinson and P. W. J. van Rensburg (Council Members), Messrs G. Abdinor, H. F. Allan, R. E. Barnes, M. M. Bayley, J. K. Boyd, R. R. M. Cousens, R. E. F. Cowley, D. Savile Davis, H. J. Davisson, C. T. Fenton, J. Fergusson, J. Fritz, M. L. Fitzgerald, J. M. Gosnell, J. C. Hall, S. A. Hancox, D. M. Jamieson, Dr D. G. Krige, Messrs J. E. V. Leeuwen, A. Louw, C. F. Louw, B. H. L. Leach, R. B. MacGillivray, C. S. McPhail, E. Margo, G. G. Nicolson, E. Pavitt, M. P. Pearse, F. O. Read, Dr M. D. G. Salamon, Dr H. S. Sichel, Messrs D. Storrar, S. G. Taussig, A. H. Taute, E. B. Viljoen and P. A. von Wielligh. Sixteen Associate Members, including Messrs S. T. Baron, W. M. Fitzpatrick, M. R. Fuller-Good, P. R. Garcia, H. G. Gericke, P. D. Hatfield, R. Hemp, G. S. Lee, Miss V. E. Marting, Messrs A. H. Munro, R. C. Power, O. F. Rheeder, G. C. Thompson and N. Zolezzi. Two Graduates, Messrs D. Bosley and J. C. Sutherland. Three Affiliates, Messrs R. K. Briggs, A. B. Cook and G. M. Thain. One Student, Mr P. W. Henrard. Twenty-three Visitors, including Messrs N. J. W. Bell, R. G. Bushell, A. Bryan, J. F. Cillie, C. M. de Beer, Dr F. H. Deist, Messrs D. S. Drake, P. G. du Plessis, R. W. Hodgson, D. M. Hawkins, S. C. H. Kearns, M. D. Labuschagne, L. Munro,R. Murchison and L. Robinson. Secretary, Mr D. C. Visser. Total present: Ninety-two. OBITUARIES The President: "It is my sad duty to announce the death of the following members of the Institute. Edward Frank Jud Bulman, Life Member, who joined the Institute in 1931 and passed away on 7th November, 1968. Elmar Fenton Chapin, Member, who joined the Institute in 1941 and passed away on 17th November, 1968. Solly Rabinowitz Rabson, Member, who joined the Institute in 1944 and passed away on 13th February, 1969. Mr. Rabson was the holder of two certificates of merit for papers presented to the Institute.

By Z. Zitron, G. J. de Korte, D. W. Horsfall

This paper summarizes work carried out on the treatment of fine coal, nominally classified as minus 0,5 mm (wedge-wire screen), which is removed from the raw coal prior to the treatment of the plus 0,5 mm sizes. The minus 0,5 mm coal divides, for treatment purposes, into fines, nominally between 500 and 150 !tm, and ultrafines, nominally minus 150 !tm. Studies on processes for the treatment of minus 0,5 mm coal are discussed, and the lower size limit beneficiated is indicated for each process. The installation and operational results from a pilot froth-flotation plant treating minus 150!tm coal are described.

Jan 1, 1986

By H. Willenberg, J. S. Coggan

ABSTRACT: Although individually both continuum and discontinuum numerical analyses provide useful means to analyze rock slope stability problems, complex failures typically involve mechanisms related to both existing discontinuities (i.e. discontinuum) and deformation and brittle fracture of intact rock (i.e. continuum). One such example is the 1991 Randa rockslide in the southwestern Swiss Alps, where failure involved several complex mechanisms, which require the consideration of progressive failure and rock mass strength degradation. This paper presents results from a series of hybrid finite-/discrete-element models directed towards the explicit modelling of brittle fracturing in natural rock slopes, enabling the modelling of progressive failure, from initiation, through to the development of catastrophic failure, transport and deposition. RÉSUMÉ: Si les modélisations numériques de type continu ou discontinu fournissent des outils utiles pour l’analyse de problèmes de stabilité de pentes rocheuses, elles montrent de sérieuses limitations lorsque des mécanismes de rupture complexes impliquent des processus liés autant aux discontinuités préexistantes qu’au développement progressif de nouvelles fractures. Ceci se retrouve typiquement dans l’exemple de l’éboulement de 1991 à Randa dans les Alpes suisses du sud-ouest, où la rupture a impliqué plusieurs mécanismes complexes nécessitant la prise en considération de la fracturation progressive ainsi que de la dégradation de la résistance des masses rocheuses. Cet article présente des résultats provisoires d'une série de modèles hybrides orientés vers la modélisation explicite de la fracturation de pentes naturelles, permettant la modélisation de fractures progressive de leur initiation jusqu’à leur développement, leur rupture catastrophique, leur transport et leur déposition. ZUSAMMENFASSUNG: Obwohl numerische Kontinuum- und Diskontinuum-Berechnungen einzeln nützliche Ergebnisse zur Stabilitätsanalyse von Felshängen liefern, sind komplexe Felsrutschungen typischerweise mit Mechanismen verbunden, die sowohl durch bestehende Trennflächen (s.a. Diskontinuum-Ansatz) als auch durch die Deformation und das Versagen intakter Felsbereiche (s.a. Kontinuum-Ansatz) bedingt werden. Ein Beispiel für einen solchen Sachverhalt ist der Bergsturz von Randa 1991 im südwestlichen Teil der Schweizer Alpen, bei dem die Rutschung mehrere komplexe Mechanismen umfasste, so dass “progressive failure” und Verminderung der Gebirgsfestigkeit in Betracht gezogen werden müssen. Dieser Artikel beschreibt vorläufige Ergebnisse einer Reihe von hybriden Modellrechnungen (Finite-/Diskrete-Elemente). Diese haben zum Ziel, explizit das bruchhafte Versagen natürlicher Felshänge zu modellieren, wobei das progressives Versagen im ganzen modelliert wird, von der Anfangsphase über die Entwicklung zum katastrophalen Versagen und den Transport und die Ablagerung der Rutschmassen.

Jan 1, 2003

By Q. Fu, Q. Wang, L. G. Wen, M. X. Jia, J. J. Zhao, J. W. Zhou

The BGRIMM process mineralogy analyser (BPMA) is a new automated mineralogy software platform developed in China. This system consists of the BPMA software platform, controlling a combination of commercially available scanning electron microscopy (SEM) and energy dispersive Xray spectrometry (EDS). The BPMA software controls SEM and EDS through their application programming interfaces, to form an auto-SEM and EDS system that automatically acquires BSE images and X-ray spectra, respectively, and classifies minerals by spectrum-matching. After automated measurement and mineral identification, various quantitative process mineralogical data (e.g., mineral composition, mineral abundance, mineral liberation and intergrowth relationships, mineral associations, particle and grain sizes, particle density distributions, calculated assay, elemental deportments, mineral grade recovery and elemental grade recovery, etc.) would be calculated quickly, accurately and automatically. The BPMA could be used for ore characterisation as a new advanced automated mineralogy technology. Keywords: BSE image; X-ray spectrum; automated mineral identification; quantitative mineralogical investigation; automated mineralogy

Jan 1, 2020

By C. Montoya

This paper shows, through a case study, the impact of multivariate grade modelling upon mine design and mine planning. A deposit explored by drill holes is considered, in which the grades of five elements (copper, silver, molybdenum, arsenic, and antimony) are of interest. Forty alternative models of the deposit are constructed by fitting the joint correlation structure of the grade variables and using conditional cosimulation. In addition, a reference model, obtained by averaging the alternative models, is also considered. The study shows that the resulting mine design (final pit characteristics and production schedules) is sensitive to the grade model under consideration, and that the design based on the reference model may not be optimal when compared to the alternative models based on cosimulation. However, when assuming a given long-term plan and extraction sequence, the grades and net present value (NPV) calculated on the reference model are unbiased with respect to those calculated on the alternative models with the same extraction sequence. The latter allow assessing the possible dispersion of the actual grades and NPV around their expected values, and are useful for the planner in order to determine the probability of meeting given production targets and of exceeding or falling short of given threshold grades. Additionally, unlike cosimulation, the separate simulation of each grade variable leads to unrealistic resource models and to biased results in mine design and mine planning. This approach should therefore be avoided, unless the grade variables are spatially uncorrelated.

Jan 1, 2012

By D. J. Bosman

The impoved densification of sludge from neutralized acid mine drainage. by D. J. BOSMAN, B.Sc., (Member) The paper describes an investigation aimed at finding a solution to the accumulation of acid mine drainage in the old workings at Coronation Collieries, Kromdraai. The problem involved the neutralization of the acid in the water, without the large volumes of sludge and the large amounts of dissolved solids that usually result from neutralization. Pilot-plant work on the site using a limeneutralization process developed at Bethlehem Steel Corporation (U.S.A.) showed this to be a feasible method. A sludge of 22 per cent density was obtained under optimum operating parameters. The amount of suspended solids in the overflow water was very high, but this does not give rise to concern because the full-scale plant at Kromdraai will practise secondary sedimentation by running the thickener overflow through large dams with a theoretical retention time of 25 days. An analysis of the theory underlying the process is also made.

Jan 4, 1974

The Institute of Lighting Engineers of South Africa The Institute of Lighting Engineers of South Africa (ILESA) was constituted in May 1972 and now has over 70 members. The first Annual General Meeting was held on 15th August, 1973, at the Philips Auditorium, when the first presentation of membership certificates was made. Book Reviews Der Hochofenprozess. Das kinetischdynamische Simulationsmodell des Vereins Deutscher Eisenhiittenleute.Diisseldorf, Verlag Stahleisen M.B.H., 1973. Jones, M. H. and Woodcock, J. T. Ultraviolet spectrophotometry of flotation agents with special reference to the determination of xanthate in flotation liquors. London, Institution of Mining and Metallurgy. 1973. 25 pp. £2,50. Notice VI INTERNATIONAL CONGRESS OF ENGINEERS The above congress is to be held in Barcelona from 6th to 10th October, 1974. NIM reports Report No. 1568 A computer programme for the estimation of parameters in flotation. Report No. 1571 The commissioning of a direct-reading spectrometer for the analysis of silicate rocks by use of the graphite-pellet technique. Report No. 1579 The determination of tin tn geochemical- survey samples. Report No. 1587 A preliminary investigation of the flotation of copper-activated sphalerite without the use of collectors. Report No. 1589 Preliminary investigations into the flotation of tin dioxide, cassiterite, and some related gangue minerals. Professional . engineers Reference (18/19/1) 22nd November, 1973 Dear Sir/Madam, From time to time questions are being asked publicly concerning registration of professional engineers. These questions mainly concern the time it takes to finalise applications, especially those of applicants who do not hold a recognised engineering qualification. Professionele . . Ingenleors Verwysing (18/19/1) 22 November 1973 Geagte heer/dame, Van tyd tot tyd word daar vrae in die openbaar gestel oor die registrasie van Professionele Ingenieurs. Vrae gaan veral oor waarom dit so lank neem om aansoeke af te handel, veral van aansoekers wat nie 'n erkende ingenieurskwalifikasie besit nie.

Jan 3, 1974

By R. T. Rudd

The impact of slimes-dam formation on water quality and pollution by R. T. RUDD*, B.Sc., AMI (S.A.) CE (Visitor) This paper discusses the mechanics of pollution by slimes dams in the gold- and fluorspar-mining industry, as well as that caused by coal dumps and slurry dams. The effect of coal mining on two typical rivers in Natal is shown and the implications discussed. The implications and trends of sulphates pollution on the Rand Water Barrage in the Vaal River are discussed. The spread of pollutants (sulphates and fluorides) from the Reef and elsewhere, and the impact on urban use and agriculture downstream of the barrage, are illustrated. Conclusions and future policy are outlined.

Jan 12, 1973

By A. J. H. Newell, K. Doherty

A copper-gold project has required a number of trade-off studies underpinned by test work to settle on pragmatic flowsheets and throughputs to support a pre-feasibility study that provides a compelling financial case. The primary trade-off studies were based on the mine schedule, ore type feed-grade recovery relationships, likely concentrate grades and typical marketing terms as well as the estimated capital and operating costs for a range of throughputs and mining strategies. Secondary trade-off studies were conducted for specific circuits and additional processing options. Although the details of these studies are not presented, the technical options and subsequent flowsheets are discussed. While the flowsheets will be optimised during the feasibility study stage, the basis is now fixed for the four ore types that would be mined from the copper-gold orebody. The ore types, resulting from a strong weathering profile, exhibit a wide range of copper mineralisation and gold associations, as well as gangue types. They display a range of characteristics that necessitated a nuanced approach to flowsheet development. The primary separation techniques that have been employed include gravity, classification, flotation and leaching while a range of comminution methods have been selected to suit the properties of the ore types. While technical issues are important factors in terms of maximising the quality of separations, recoveries and revenues, attention to material handling, equipment characteristics, the mine schedule, and capital and operating costs are equally important considerations for settling upon a suitable and robust flowsheet. Keywords: Flowsheet, testwork, studies, saprolite gold, native copper, chalcocite, chalcopyrite

Jan 1, 2020

By R. Altındag, D. Akbay

The point load index is a simple, fast, and inexpensive method for determining rock strength and can be applied both in the field and in the laboratory. There are, however, some disadvantages and limitations to the method, and the test results can be affected by the person carrying out the test, the rock characteristics, or the test device. In this study we describe an investigation into how the point load index value is affected by the shape of the conical platens used in the test. Point load index tests were carried out using different devices fitted with conical platens of different spherical radii, and on a modified device which circumvented the limitations/disadvantages. It was seen that the point load index value increased as the platen radius increased, as expected. In the case of testing using non-standard conical platens, an equation is proposed to normalize the point load index value with respect to the standard spherical radius value.

Nov 1, 2021

By B. R. Broekman, K. J. R. Ford

Over the last decade significant development and use has been made of a simulation model that describes the HCFeMn smelting operations in Assmang Ltd. This spreadsheet based, semi-empirical, predictive model is derived from data from the submerged arc furnaces at Assmang?s Cato Ridge, KwaZulu-Natal smelter site. Departures from the empirical base case mass balance due to changes in the ores, reductant feeds and operating parameters are accounted for by use of fundamental relationships and heuristic type ratios which are applied in an iterative manner in the model. The model performs a sequential set of calculations to iteratively converge on a fully consistent mass and energy balance solution, which predicts Mn alloy and slag output masses and compositions for a given set of feeds. 440 MWh per operating day is used as the basis of energy input. The paper describes the key model components, assumptions made and calculation approach. Added to the mass and energy balance is a cost and revenue balance, which allows prediction of the economic performance for each simulation. Substantial use of the model has been made in simulating the performance of the current Assmang HCFeMn furnaces for both smelter investigations and future production planning. The model has also been a valuable tool in the strategic analysis of the use of future Mn ores and has formed the vital link between mine ore grades (metal and slag elements) and the expected alloy output, grade and profitability. Additionally, the model has been used in benchmarking exercises to predict other Mn smelting operations with remarkable accuracy. The paper highlights some aspects of the approaches taken in using the model to benchmark Assmang?s own furnace performance and cost competitiveness with other producers. For Assmang the development and application of this modelling technology has led to transformation in understanding of the Assmang HCFeMn furnace operations and increased awareness of the potential of its Mn ore bodies.

Jan 1, 2004

By V Kveldsvik, N Ragvin, T Eiken, G Grøneng, G V. Ganerød

Catastrophic rock slope failures have caused destructive tsunamis in Norwegian fjords. At the Åknes rock slope the tsunami generating potential is large due to the potential large volume involved in a possible catastrophic failure. Widening of the upper crack has been recorded since 1986, and in recent years, a quite extensive investigation and monitorin campaign has been conducted. Data from some of these investigations are presented and analysed with respect to a preliminary evaluation of the stability of the slope.

Jan 1, 2006

By W. P. Channon, J. B. See

The reduction of fluxed and non-fluxed manganese, ores by ferromanganese silicide by W. P. CHANNON, B.Se. (Eng.), M.Sce. (Eng.) Wits. (Visitor) and J. B. SEE, B.Sce. Hons., Ph.D. (New South Wales), M.I.M., M.I.M.M. (Member) In South Africa, medium-carbonferromanganese is produced by the silicothermic reduction of slags containing MnO. Because of its importance in the production of refined ferromanganese, a study was made of the reaction between a premelted South African Mamatwan manganese ore and various ferromanganese silicide reducing alloys, with and without fluxing agents. Because the reaction is highly exothermic, temperature appeared to have little effect on the rates of manganese transfer to the metal and silicon transfer to the slag, and an apparent equilibrium was rapidly approached. Limits were determined for the favourable effects of fluxing additions, and manganese recoveries were found to decline as the ratio of CaO to MgO decreased as a result of the addition of basic flux. The recovery of manganese passed through a maximum, and subsequently decreased for variations in the ratio of alloy to ore. The results obtained, when used in conjunction with other physicochemical data related to this slag-metal system, suggest optimum slag compositions for the efficient manufacture of medium-carbon ferromanganese from Mamatwan ore.

Jan 3, 1977

By M. G. B. Wheeler

SYNOPSIS This report outlines the development of a model to simulate the radiometric sorting of gold- and uranium-bearing ores. The developed program indicates the optimum mass, reject percentage, and expected reject gold and uranium grades for a radiometric sorter. It achieves this by statistical analysis of the data gathered from a large sample of rocks in the required size range for a particular mine. The program can be used in the optimization of existing sorters, as a design tool for new radiometric sorters, and in feasibility studies on radiometric sorting.

Jan 1, 1989