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By W. J. Jordaan

The ability of soils to retain and hold cations is called the cation exchange capacity (CEC). Adsorbed cations, however, can be replaced by other cations through the process of cation exchange. Heavy mineral deposits contain a significant portion of slimes including the very fine clay minerals. In most circuits the slimes fraction hampers efficiency and has to be removed during early stages of the process. Being a nonvaluable process stream, the processing of the slimes is a costly exercise. In thickening applications it might be possible to manipulate the ability of clay minerals to retain and hold positively charged cations in order to optimize flocculation and therefore reduce flocculation costs. The CEC value of the slimes could be a measure of this possibility. To investigate this hypothesis, different slimes samples were characterized for size, chemical composition and clay minerals present. The CEC value of each sample was determined and explained in terms of the mineral phases present. Settling tests were conducted and an attempt was made to explain the CEC characteristics of the clay minerals in terms of settling rate. The scope of this investigation was to test the hypothesis and should not be seen as an in-depth study of the subject matter. A greater number of samples and detailed analyses to identify and quantify minerals and phases present would be required to investigate further the relationships between clay minerals in the deposit, CEC and settling rates. Location and geological setting Exxaro KZN Sands is mining a heavy minerals deposit at Hillendale mine located at Richards Bay, South Africa. The orebody consist of a dune some 8 km inland from the coast to the north of eSikhawini. A geological synopsis undertaken by Botha1 concluded that the Hillendale mining area represents a coastal dune sequence that accumulated north of the Tugela River. The northward movement of sediment by long shore drift currents result in a high sand budget on the beaches north of the river youth and is the dominant contributing factor to the accretion of the coastline and development of parallel dune systems along the coastal zone in this area. Beach swash zone processes and enrichment of the fine sand fraction occurs during wind transport off the beach by ascending parabolic dunes that form the coastal barrier dunes. This process results in heavy mineral concentration on the windward dune face and localized enrichment parallel to the dune forms. The aeolian sedimentary facies processes result in the primary concentration of higher grades in the upper silt-enriched reddish brown horizons of the profile. The synopsis by Botha1 further showed that an additional component of heavy mineral concentration can be ascribed to the post-depositional relative enrichment of heavy minerals due to weathering. Therefore, it is likely that the Hillendale orebody protolith was pedogenically weathered to form the homogeneous, silt-enriched, clayey reddish brown to dark red, palaeosol profile that grades downwards into yellowish brown, less clay-enriched sand. Slimes characterization Samples The Hillendale orebody was divided into geochemically discretized zones based on the concentration of ilmenite and other specific minerals and/or phases. Six composite samples were made up from exploration samples taken from Zone 9, Zone 11 and Zone 12. The red and orange horizons within these composite samples were separated and test samples were prepared to conduct test work and analyses. The test samples were submitted for preparation and analysis to characterize the slimes properties. Each test sample was deslimed at 45 µm representing the slimes fraction (-45 µm) and dried at 40°C. The -45 µm slimes samples were then split to conduct size analysis, chemical analysis, XRD and to determine the CEC. Size analysis The size distribution of the composite samples is shown in Table I. The size analysis shows that there is a difference in size distribution between the orange and red horizons of each zone. The orange horizons contain less 850 µ material as well as less slimes (-45 µm). The red horizons contain yore slimes (-45 µm). The size distribution of the slimes fraction (-45 µm) was determined using Malvern size analysis. The cumulative particle size distribution of the slimes is shown in Figure 1. The red horizons of the different zones show similar size distributions. The orange horizons show some differences. However, there is a difference in size distributions between the red and orange horizons.

Jan 1, 2007

COUNCIL AND STANDING COMMITTEES - 1973-1974 Office Bearers: P. W. J. van Rensburg (President), Professor R. P. Plewman and Dr R. E. Robinson (Vice Presidents), J. K. E. Douglas (Honorary Treasurer), and Dr J. P. Hugo (Immediate Past President). Elected Members of Council: Dr M. G. Atmore, G. H. Grange, Dr P. R. Jochens, J. G. Kirchner, Dr D. I. Legge, W. W. Malan, Dr M. D. G. Salamon, L. W. P. van den Bosch, D. A. Viljoen, P. A. von Wielligh. Branch Chairmen: B. T. Hosking (Witbank-Middelburg Branch), E. T. Wilson (Orange Free State Branch). Past Presidents Serving on Council: R. J. Adamson, M. Barcza, H. Britten, H. E. Cross, Professor J. de V. Lambrechts, R. C. J. Goode, Professor D. D. Howat, D. M. Jamieson, D. G. Maxwell, Dr J. T. McIntyre, V. C. Robinson. Ten Council meetings were held during the year, with an average attendance of 19, and the standing committees held 30 meetings. COMMITTEE CHAIRMEN Membership, Dr R. E. Robinson ; Metallurgical Colloquia, Dr R. E. Robinson ; Mining Colloquia, L. W. P. van den Bosch; Awards, P. W. J. van Rensburg; Excursions, P. A. von Wielligh; Dinner, G. H. Grange ; Constitution, Rules and Policy, Dr J. P. Hugo; Adjudicating, P. W. J. van Rensburg; Mines and Works, W. W. Malan; Education, Dr J. P. Hugo. REPRESENTATIVES ON OTHER BODIES Associated Scientific and Technical Societies: Members : V. C. Robinson and D. G. Maxwell Alternates : P. W. J. van Rensburg and Dr J. P. Hugo. Federation of Societies of Professional Engineers Members : J. K. E. Douglas and P. W. J. van Rensburg Alternates : Dr J. P. Hugo and G. H. Grange. South African Council for Professional Engineers Members : R. C. J. Goode and J. K. E. Douglas Alternates: G. H. Grange and Dr R. E. Robinson. Engineers' Liaison Committee (Pretoria): Member: Professor J. de V. Lambrechts Alternate : Dr J. P. Hugo. MEMBERSHIP Seventeen Fellows and Members, twenty-three Graduates, ten Associate Members, twenty-two Associates, thirty-four Students, and seven Company Affiliates were elected during the year. Eleven Fellows and four Members were admitted to retired membership. Five Fellows were elected to Honorary Life Membership. Four Members, two Graduates, and one Student were transferred to Fellows ; eleven Graduates and Students were transferred to Members ; eight Students to Graduates; and four Students to Associates. A statement of membership as at June 30th 1974 and the end of the previous year is given in the following tabulation 30th - 30th June, - June, 1973 - 1974 Honorary Life Fellows 4 - 9 Honorary Fellows 9 - 8 Life Fellows 177 - 170 Fellows 536 - 544 Members 487 - 512 Associate Members - - 10 Graduates 128 - 130 Associates 186 - 194 Students 183 - 173 Company Affiliates 64 - 70 1 774 - 1 820 OBITUARIES Your Council records with deep regret the death during the year of the following members : Dr P. N. Lategan and Dr O. A. Jackson, Honorary Life Fellows and Past Presidents; C. Airth, T. L. Blunt, J. B. Dennison, A. E. Frazer, C. L. Lamb, V. O. Reid, K. Richardson and D. G. Roberts, Life Fellows ; H. F. Allan, J. T. Beaumont, M. Eisenstein, J. C. Hall, C. F. Louw, H. H. McGregor, R. Murchison, and J. E. Williamson, Fellows; and R. B. Miles, Associate. FINANCE The annual accounts, which follow this report, reflect a healthy position and show that measures taken by Council over the last few years to boost income have been successful. A higher income was needed not only to meet rising costs but also so that the services provided by the Institute for its members could be expanded. This year's income of R55 025 showed a further increase compared with last year's figure of R48 307. Income from subscriptions was higher mainly owing to an increased number of Company Affiliates, and this is indicative of the support given by mining and metallurgical companies to the good work being done by the Institute. Further sales of publications of the symposia held over the last few years again made a useful contribution to income of R4560. The first Winter School held in 1973 yielded a surplus of R7495 after the expenses had been deducted from the income received from registration fees. The cost of administering the Institute increased by R2212 compared with the previous year. Included in this was a donation of R1000 to the A.S. & T.S. Trust Fund. The cost of publishing and printing the Journal increased by R2034, but advertising and extraneous sales of the Journal were higher, with the result that the net cost of the

Jan 10, 1974

COUNCIL AND STANDING COMMITTEES, 1974-1975 Office Bearers : Prof. R. P. Plewman (President), Dr R. E. Robinson and Dr M. D. G. Salamon (Vice Presidents), J. K. E. Douglas (Honorary Treasurer), and P. W. J. van Rensburg (Immediate Past President). Elected Members of Council: Dr M. G. Atmore, E. Collier, G. H. Grange, Dr P. R. Jochens, Dr D. I. Legge, D. G. Malan, C. T. Shaw, L. W. P. van den Bosch, D. A. Viljoen, H. M. Wells, P. A. von Wielligh. Branch Chairmen: B. T. Hosking (Witbank-Middelburg Branch), D. A. Smith (Orange Free State Branch). Past Presidents Serving on Council: R. J. Adamson, M. Barcza (until May 1975), H. Britten, H. E. Cross, Prof. J. de V. Lambrechts (until December 1974), R. C. J. Goode, Prof. D. D. Howat, Dr J. P. Hugo, D. M. Jamieson, D. G. Maxwell, Dr J. T. McIntyre, V. C. Robinson. Ten Council meetings were held during the year, with an average attendance of 19, and the standing and sub-committees held 74 meetings. COMMITTEE CHAIRMEN Membership, Dr M. D. G. Salamon; Technical Programme-Metallurgy, D. A. Viljoen; Technical Programme-Mining, G. H. Grange ; Vacation School-Metallurgy, Dr P. R. Jochens; Vacation School-Mining, Dr M. D. G. Salamon; Awards, Prof. R. P. Plewman; Excursions, Dr D. I. Legge; Constitution, Rules and Policy, P. W. J. van Rensburg and Prof. R. P. Plewman; Mines and Works, P. A. von Wielligh; Education, P. W. J. van Rensburg. REPRESENTATIVES ON OTHER BODIES Associated Scientific and Technical Societies Members: V. C. Robinson and Prof. R. P. Plewman. Alternates : Dr R. E. Robinson and Dr M. D. G. Salamon. Federation of Societies of Professional Engineers Members : J. K. E. Douglas and P. W. J. van Rensburg. Alternates : Prof. R. P. Plewman and G. H. Grange. South African Council for Professional Engineers Member : R. C. J. Goode. Alternate : G. H. Grange. Engineers' Liaison Committee (Pretoria) Member: Dr J. P. Hugo. Alternate: P. W. J. van Rensburg. MEMBERSHIP Thirteen Fellows, seventeen Members, eleven Graduates, three Associate Members, eighteen Associ¬ates, twenty-six Students, and one Company Affiliate were elected during the year. Nine Fellows, four Members, and three Associates were admitted to retired membership. Eight Fellows were elected to Honorary Life Membership. Three Members and one Graduate were transferred to Fellows, nine Graduates and two Students to Members, six Students to Graduates, one Student to Associate, and one Associate to Associate Member. Six Fellows, ten Members, three Associates, and one Student resigned. A statement of membership as at June 30th 1975 and the end of the previous year is shown in the following tabulation: 30th - 30th June, - June, 1974 - 1975 Honorary Life Fellows - 9 - 15 Honorary Fellows 8 - 8 Life Fellows 170 - 170 Fellows 544 - 536 Members 512 - 523 Associate Members 10 -15 Graduates 130 - 133 Associates 194 - 210 Students 173 -175 Company Affiliates 70 - 71 1 820 - 1 851 [ ] OBITUARIES Your Council records with deep regret the death during the year of the following members: M. Barcza, Honorary Life Fellow and Past President of the Institute; J. A. Boyd, F. E. Keep and J. H. Taylor, Life Fellows; I. D. B. Corner, C. O'G. Deane, R. E. Gilmour, A. C. Hofmeyr, M. W. Howell, T. J. Robin and F. C. Steinhobel, Fellows; J. J. Frankel, Member; T. J. Higgs, Associate. FINANCE The annual accounts, which follow this report, indicate that income again exceeded expenditure by a margin of R21 410 (last year R28 524). This year's income of R71 184 showed a further increase compared with last year's figure of R55 025. Costs, however, also in¬creased, and it is calculated that, excluding non-recurrent costs, the cost of running the Institute in¬creased by R6 654 from R25 501 to R33 155 for the current year. The main increases were involved in secretarial fees, stationery and print¬ing, and in publication of the Journal. All indications are that costs will continue to rise, and we have been advised that the A.S. & T.S. will be increasing their secretarial fees by 25 per cent in the year ahead to meet their rising costs. This year's surplus was derived entirely from the revenue from sales of publications (R13 644) and a surplus from the 1974 Winter School (RIO 654). There can be no certainty that revenue from these sources can be repeated each year. Our funds are in a satisfactory position because of these worth¬while activities, but the administrat¬ion of the Institute should not de¬pend on them. Council will accord¬ingly have to give consideration in the year ahead to an upward adjust¬ment of subscriptions to meet rising costs.

Jan 10, 1975

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 30th August, 1972. Professor D. D. Howat (President) was in the chair. There were also present sixty-two Fellows, twenty-four Members, two Associates, three Students and eighteen Visitors, making a total of one hundred and nine. The President declared the meeting open at 4.05 p.m. OBITUARIES The President: It is my sad duty to announce the death of six members of this Institute. The first of these is Dr A. J. Orenstein, Honorary Life Fellow, who joined the Institute in 1916 and died on Seventh July. Dr Orenstein became almost a legendary figure in Medicine as a result of his work in the control and elimination of malaria during the digging of the Panama Canal and I believe he was actually engaged working until four days before his death. The other members who have died are: F. Meyer, died on 8th June; S. D. Loxton, Fellow, died on 13th May; J. Innes, Fellow, died on l0th January, 1970; O. B. Prentis, a Member, died on 4th June, and J. Brits, Associate, died on 27th June. As a mark of respect to the memory of the deceased and in sympathy with the bereaved may I ask you to rise and observe a few moments silence. MINUTES The President: 'The second item on the Agenda, the minutes of the meetings held on March 22nd and May 10th, 1972, as tabled. May I confirm these minutes'? Agreed. WELCOME TO VISITORS 'On behalf of the Council, may I say how delighted we are to have such a splendid gathering with us on this our Annual General Meeting. Dames en here vir die omvang van my Afrikaanse woordeskat verdien ek weinig lof, boonop is dit nog Afrikaans met 'n Skotse aksent, wat u asseblief moet verskoon. Tog wil ek se hoe dankbaar ons is dat sy Edele, die Minister van Mynwese, dr Koornhof en mev Koornhof vandag hier teenwoordig kan wees. In addition to our own newly appointed Minister of Mines, we are also honoured by the presence of the Minister of Mines of Rhodesia, Mr I. B. Dillon. I think not even our oldest members can recall an occasion on which two Ministers of Mines were present at a meeting of the Institute. It is a particular pleasure to welcome them this afternoon. I am happy to say that Minister Koornhof is an Honorary-Vice President of the Institute, and Minister Dillon is an Honorary Member. The presence of your goodselves, gentlemen, with us this afternoon, I am sure underlines the great significance which we believe both countries attach to the economic exploitation of the vast mineral resources of Southern Africa. For over 70 years, this Institute and its members have been making their contribution to this great task of mineral exploitation, and we feel that your presence with us today, is a token of the confidence of your governments in what this Institute and its members have been endeavouring to do. Also present with us today, is Mr R. C. J. Goode, President of the Chamber of Mines, and Honorary President of this Institute. I was going to say I welcome Mr Goode, but it is rather difficult to welcome a man to his own home, and this is the case with Mr Goode. He is a very distinguished and a very recent past president of this Institute and he remains now, as he has been for as long as I can remember, one of our most active and valuable members. This I think, ladies and gentlemen, is the second rather unique feature of this occasion this afternoon, because no one else can recollect an occasion on which the President of the Chamber of Mines was also a past president and an active member of our Institute. A special word of welcome, Mr Goode. Mr Tommy Gibbs, our Government Mining Engineer, is in a somewhat similar position as he is also a member and an old and valued friend of our Institute, - welcome to you, Mr Gibbs. Mention I think, must be made of the fact that we are very glad to have with us Dr A. J. A. Roux, President of the Atomic Energy Board, and Mr Stanley Craib, President of the Associated Scientific and Technical Societies. Then, within the great family of the A.S. and T.S., we have the presidents, or the vice-presidents of I believe 13 of the constituent societies. These gentlemen, like all the rest of us, have the rather tiring task of supporting and upholding their fellow presidents on occasions such as this. We particularly appreciate their presence this afternoon and the effort they have made to be with us. We are happy to have with us: Dr R. E. Robinson, Director-General, National Institute of Metallurgy, Mr E. Boden, Manager, Associated Scientific and Technical Societies, Dr H. G. Denkhaus, President, The S.A. Institute of Mechanical Engineers, Mr G. Goedhals, Vice-President, S.A. Institute of Electrical Engineers, Mr E. Dalton, President" S.A. Institute of Certificated

By I. Satola, J. Aromaa

In this work we have reviewed methods to classify corrosivity of ground waters. Weight loss and stress corrosion cracking (SCC) corrosion tests have been done for rebar and steel strand. No clear indication of SCC was found. The application of tensile stress to 85 % of yield strength increased general corrosion rate significantly in very corrosive waters. The effect of corrosion protection on the axial behavior of steel strands was determined by double pipe axial tests with different embedment lengths. The results showed a significant difference on behavior between epoxy-coated steel strands, galvanized steel strands and plain steel strand. Dans la présente étude, nous avons passé en revue des méthodes permettant de classifier la corrosivité des eaux souterraines. Des tests portant sur les pertes de poids et sur la corrosion FCC (la fissuration par corrosion sous contrainte) ont été effectués pour les barres d’armature et les torons. Aucune indication nette de FCC n’a été constatée. L’application d’une contrainte de traction allant jusqu’à 85 % de la limite d’élasticité a accru de manière significative la vitesse générale de corrosion dans les eaux très corrosives. L’effet de la protection contre la corrosion sur le comportement axial des torons en acier a été déterminé au moyen de tests axiaux à double tube avec des longueurs d’enrobage différentes. Les résultats ont mis en évidence une différence significative quant au comportement entre les torons en acier à revêtement époxy, les torons en acier galvanisés et les torons en acier standard. In dieser Arbeit haben wir Methoden geprüft, die korrosive Wirkung des Grundwassers einstufen. Gewichtsverlust- und SCC-Korrosionstests wurden für Stahlstäbe und Drahtlitzen durchgeführt. Es wurden keine sicheren Hinweise auf Spannungsrisskorrosionsbrüche gefunden. Bei Anwendung einer Dehnbelastung von 85 % der Streckspannung bzw.Ergebnisstärke stieg die allgemeine Korrosionsrate in stark korrosivem Wasser deutlich an. Die Wirkung des Korrosionschutzes bei axialem Verhalten von Stahldrahtlitzen wurde durch axiale Tests an Doppelleitungen unterschiedlicher Versenkungslänge determiniert. Die Ergebnisse zeigten im direkten Vergleich von epoxidbeschichteten, galvanisierten und normalen Stahldrahtlitzen beachtliche Unterschiede im Verhalten auf.

Jan 1, 2003

By R. J. Davidson, V. Veronsee

Some of the parameters affecting the elution of gold from freshly loaded activated carbon using pure water as an eluant were studied. The procedure involved pretreatment of the gold-loaded activated carbon with a strong reagent of sodium cyanide and sodium hydroxide, followed by elution of the gold with water. Gold-loaded carbon obtained from three different sources was studied. It was shown that the elution temperature was the most critical parameter, and column operation at I !OCC (gauge pressure of 50 to 100 kPa) is suggested. The effects of variations in the concentration of sodium cyanide required for the pretreatment of loaded carbon and of variations in elution flowrate were also investigated. Both these parameters were found to have only a marginal effect on the efficiency of gold elution. The investigation also indicated that gold-elution rates were affected to a considerable degree by the particle size of the carbon concerned. Higher elution flowrates could be used when carbons of finer particle size were eluted. A modified eluate-collection procedure was also developed during the course of the investigation. Oven-drying of the loaded carbon was shown to have little or no effect on the efficiency of the subsequent gold elution. The calcium and silica contents of the various carbon samples were also determined. It was immediately evident that the calcium content was very considerable in the case of loaded carbons originating from carbon-in-pulp operations. Calcium concentration was particularly high where air agitation had been employed in the carbon-contacting circuit. To some degree, the calcium build-up explains the serious carbon fouling taking place, resulting in a decreased efficiency of gold adsorption. The fouling problem was found to be less severe when mechanical agitation was used. No poisoning by calcium carbonate was observed where the pregnant solution had been acidified before it was contacted with the carbon.

Jan 1, 1979

By N. A. Smith, R. J. Fowell, J. L. Hislam

Abstract: Data are presented from two sites in southeast England, where problems were encountered in tunnelling through ground containing flint. In response to the difficulties, substantial laboratory testing programmes were initiated to determine the strength of the flints.It is shown that the strength varies very considerably, even within a single flint particle and that the practice of estimating unconfined compressive strength by a single multiplier applied to the point load strength index (Is(50)) may give misleading results. The preparation of UCS specimens for testing was found to be very difficult and it is recommended that tunnel machine capacity is assessed relative to Is(50). Résumé: Des données sont presentées sur deux sites dans le sud-ouest de l’Angleterre,où le perçage d’un tunnel dans un sol contenant du silex a posé des problémes. En consequences de ces difficultés, des programmes substatiels de recherché en laboratoire ont été initiés afin de déterminer la resistance des silex. Il est demontré que la resistance varie considérablement, même au sein d’une particule de silex, et que la pratique de estimation de la résistance en compression non confinée, (UCS) par le biais d’un simple coefficient appliqué au ‘point load strength index (Is50)’ pourrait donner des resultants trompeurs. La préparation de specimens UCS destinés aux tests s’est avérée trés difficile et il est recommandé que la capacité de la machine de perçage de tunnels soit calculée relativement au Is50. Zusammenfassung: Daten von zwei Standorten in Südosten von England, wo Probleme beim Tunnelbau durch feuersteinhaltigen Grund antraffen, sind angegeben. Wegen diesen Schwierigkeiten wurden Laboratoriumsforschungsprogramme eingeleitet, um die Festigkeit von Feuersteinen zu bestimmen. Es wurde gefunden, dass die Festigkeit sehr unterschiedlich war, selbst bei einzelnen Feuersteinstücken, und dass die Praxis, die unbegrenzte Kompressionsfestigkeit (uKf) auf Grund eines einzigen Multiplikationsfaktors vom Punktladefestigkeitsindex (Is50) abzuschätzen, zu irreführenden Resultaten führt. Die Vorbereitung der uKf Prüfstücke war sehr schwierig und es wird vorgeschlagen, dass die Kapazität der Tunnelbaumaschine in Abhang der Is50 bestimmt wird.

Jan 1, 2003

By F. Hees, A. H. Bracken, L. I. Boshoff

"Biological cementation of the Mandena heavy mineral sand deposit in Madagascar was causing difficulty in dredge mining and hence in planning and control of production rates. An investigation was initiated to better evaluate the geotechnical properties of the orebody by defining the distribution and geotechnical properties of the cemented strata, in order to generate a site-specific geotechnical model for the deposit. The geotechnical characterization was developed by an integrated approach using several ground investigation techniques such as piezocone (CPTu) testing, geotechnical drilling, standard penetration testing (SPT), as well as laboratory testing. The final outcomes of the investigation included a 3D geotechnical model showing the distribution and extent of the cemented areas, as well as the typical geotechnical parameter ranges associated with each of the defined geotechnical units. The interpretations developed were incorporated into the mine and production planning to ultimately optimize operational planning and control.IntroductionQIT Madagascar Minerals (QMM) is a heavy mineral sand mining operation at Mandena, near Fort Dauphin in Madagascar. During the final planning and commissioning stages of the project, the need to fully characterize the unusual geotechnical conditions was identified and a geotechnical investigation became necessary.Nature of the problemDuring the commissioning phase it was found that mining production was being hampered by biologically cemented/indurated layers encountered within the sands. Closer inspection of the indurated horizons in the dredging face revealed that these layers contain a high loading of bacteria and fungi. It appears that the bacteria produce an extracellular (outside the cell) polysaccharide (i.e. sugar and carbon salts), which form a gelling biofilm to trap nutrients. There are a number of different bacteria. The fungi, on the other hand, produce a network of fibrous strands that bind the sand grains together. Thus both bacteria and fungi probably contribute to the ‘apparent cohesive’ strength or binding of the indurated sand (Lynn, 2008)."

Jan 1, 2017

By Willem J. Marais

The management of unpaved mine road networks on large surface mines rarely results in optimal road maintenance strategies and minimised total road-user costs. This is ascribed mostly to the complex and dynamic combination of variable road networks and loading and discharge points. In a dynamic mining environment - typically those mines in which production is managed by a centralised truck dispatch system ? there is no guarantee that a particular road maintenance intervention will contribute significantly to reducing total road-user costs or increasing productivity. Most large surface mines operating ultra-heavy mine trucks rely on an integrated on-board diagnostic data collation, communication and GPS-asset location system as a real-time fleet management tool. By extending this system to incorporate a multi-sensor analytical procedure in which specific truck vital signs are monitored and filtered, a road defect can be recognised and a trigger level set to relay the location of defects on the mine haul road to the centralised truck data management system. Previous work established the feasibility of the multi-sensor approach to road defect recognition on large mine haul trucks, and outlined the defect recognition, analytical and modelling issues and system limitations. This paper presents the development of the analytical procedure used as a basis for evaluating the truck on-board data to establish maintenance priorities amongst a network of mine roads. Following an introduction to the system architecture, the results of system field trials are analysed and the results discussed in the light of defect density and traffic volume as the primary variables in an approach to prioritising road maintenance. The paper concludes that by supplementing the existing mine communication and asset management systems, road maintenance can be managed on a near real-time basis and maintenance equipment dispatched to where most immediate benefit will realised from a maintenance intervention on the network, thereby generating the maximum improvement in service and reduction in cost per ton hauled.

Jan 1, 2008

By Y. -H. Chang, Y. -J. Jou, T. -S. Ueng, I. -H. Peng

In order to systematically study the size effect on the shear strength of rock joints, this study used the computer-aided-manufacturing system to reproduce the artificial rock joints for saw-toothed joints, Barton's standard joint profiles of JRC = 4~6 and 18~20, and natural rock joint profiles. We divided, enlarged, reduced, and assembled these joint profiles to obtain joint specimens of various sizes ranging from 75 mm to 300 mm in length. The shear strengths of these joint specimens were tested under different normal stresses using a direct shear test apparatus. The surface conditions of the joints at failure were also examined. The size and geometry effects on the shear strengths of these joints of various sizes and configurations were evaluated based on the test results. Um die künstlichen Trennflächen für reguläre dreieckige Trennflächen, Bartonsche standardmäßige Querschnitte der Trennflächen von JRC = 4~6 und 18~20 und natürliche Querschnitte von Trennflächen wiederherzustellen, benutzt diese Forschungsarbeit das Computergestützte-Erstellungssystem, damit die Maßstabswirkung auf die Scherfestigkeit von Trennflächen systematisch untersucht werden kann. Die Querschnitte werden geteilt, vergrößert, verkleinert und zusammengesetzt, um Trennflächenproben in Längen variierend von 75 mm bis 300 mm zu erhalten. Die Scherfestigkeit dieser Trennflächenproben wird unter unterschiedlichen Normalspannungen mit einem Direktscherversuchsgerät getestet. Die Querschnittszustände der Trennflächen bei Versagen werden ebenfalls untersucht. Nach den Untersuchungsergebnissen werden die Maßstabs- und Geometriewirkung auf die Scherfestigkeit dieser Trennflächen verschiedener Größen und Konfigurationen ausgewertet. Pour étudier systématiquement l’effet de la dimension des fractures des roches sur leur résistance au cisaillement un système de creation de fractures artificielles à l’ordinateur a été employé. Des fractures artificielles triangulaires, profils de fractures de Barton avec JRC = 4~6 et 18~20, et profils de fractures naturelles ont été reproduits. Les profils des fractures ont été arrangés de manière à obtenir des échantillons de longueur entre 75 et 300 mm. Une boîte de cisaillement a été utilisée pour étudier la résistance des fractures au cisaillement, sous plusieurs conditions de contraintes normales. Les conditions superficielles des fractures après rupture ont été étudiées. Les résultats de ces essais, effectués sur plusieurs échantillons de dimensions et configurations variées, ont contribué à établir l’influence des dimensions et de la géométrie des fractures sur leur résistance au cisaillement.

Jan 1, 2003

By D. Rankin, H. J. Stucke, W. K. B. Loftus

Discussion: H. J. Wright (Member): The authors are to be congratulated on presenting such a comprehensive and lucid account of bringing a large diamond mine into efficient production from the grass roots. When one considers the vast amount of planning and hard work that had to be put into the project the authors have done a praiseworthy job in condensing the story, so as to present all the important technical aspects, the logic behind the major decisions and the future thinking on the operations, in a concise and readable form. This was the first experience of De Beers personnel in starting a large diamond mine as an opencast project and nor do they employ a large planning staff, most of the planning being carried out by the executive staff themselves. It is operating most efficiently on a large tonnage and it is neatly and very well laid out. In fact, with its model townships, both for European and Coloured employees, tarred roads, recreation club and its grass golf course, it is like an oasis in the arid climate of the North-Western Cape. The key operation of opencast mining is, of course, the planning of the geometry of the pit. This has been adequately dealt with by the authors. It is of interest to consider some of the consequences arising from complete lack of open pit planning, based on actual operating mines. I refer of course to the present, four producing mines in Kimberley. The Kimberlite pipes were all discovered in a short span of time from the year 1870, onwards. They soon became a hive of activity with diggers industriously working their claims at varying rates. The country rock comprises from the surface downwards, some 90 ft of decomposed dolerite followed by approximately 260 ft of soft Karroo shales, which in turn is underlain by a hard competent Ventersdorp lava, known locally as melaphyre. The average water table was just below the dolerite at a depth of approximately 90 to 100 ft. Only the blue ground was mined leaving the waste rock sides almost vertical, and as the depth increased beyond 100 ft, large falls of sidewall started to take place. The shale was unstable and the falls covered

Jan 3, 1969

By T. Tholana, P. N. Neingo

"A mineral resource constitutes the principal underlying asset of a mining company, and must be exploited and managed in such a way that maximum value is derived from it. Various asset management frameworks applicable to physical assets are available. This paper focuses on the extension of an asset management approach, particularly the Publicly Available Specifications (PAS) 55 asset management framework and the International Organization for Standardization (ISO) 55000 series of standards, to mineral assets. It is concluded that PAS 55 and the ISO 55000 series of standards can be extended to manage mineral assets, resulting in an integrated approach to sustainably optimize value from the company’s mineral assets. The benefits include improved returns on mineral assets, maximum mineral asset utilization, creation of an organizational culture focused on quality and continuous improvement, and assurance to stakeholders that the mineral assets are being efficiently managed over their entire life-cycle. In the context of this paper, a ‘mineral resource’ refers to both Resources and/or Reserves as classified by the SAMREC Code. IntroductionMining involves the extraction of valuable mineral resources from the Earth’s crust. A mineral resource is unique among natural resources in the sense that it is a wasting asset, which means that its value depreciates continuously with extraction. In addition, it is often impaired from time to time as commodity price changes (Macfarlane, 2011a). Since a mineral resource is a wasting asset there is a single opportunity available to optimize value from its extraction. Mine planning involves identifying a strategy to exploit the mineral resource in a way that maximizes value at an acceptable risk level throughout the life of mine (LOM). This optimum extraction strategy changes as economic conditions change, particularly commodity prices, as well as with improvements in orebody knowledge as mining progresses. It is the mineral deposit that competitively distinguishes two different mines and dictates the location of a mine; hence the adage ‘the orebody dictates’. Therefore, a mineral resource is the primary tangible asset possessed by mining companies and must be managed in such a manner that maximizes its value at an acceptable risk level (Macfarlane, 2011a)."

Jan 1, 2016

By Piotr M. Kapias

Keywords: extraction, lead refining, Pb-Tl solutions, PbCl2-TlCl solutions. The theoretical part of the paper presents an analysis of the conditions of Tl extraction from Pb using different extractants and determines the activity coefficients in liquid solutions of Pb-Tl and PbCl2-TlCl. The dependence of the solution activity coefficients upon the composition and temperature is presented in the form of Krupkowski and Krupkowski-Fitzner equations. An analysis and evaluation were made of the influence of the methods of PbCl2 introduction into a Pb-Tl solution upon the efficiency of the Tl extraction process under thermodynamic equilibrium conditions. The analysis made it possible to formulate relevant equations describing the dynamics of the process of Tl extraction from Pb under stirring conditions as well as under the extractant injection into the liquid Pb-Tl solution conditions. In the part concerning experimental work, results are given for tests on the Tl extraction process from Pb-Tl liquid solutions of initial Tl content of approximately 0.05% mass using PbCl2 or, alternatively, Cl2(g) conducted in laboratorial scale. The tests made it possible to establish the influence of time, temperature, mass and the method of introducing the extractants into the liquid upon the level of Tl extraction from a Pb-Tl solution. Labels used in the text. WT1m - TI content in metallic phase, % mass WT1s - TI content in chloride phase, % mass wpTlm - TI content in metallic phase in initial state, % mass W°Tlm - TI content in metallic phase in equilibrium conditions, % mass m°m - initial mass in metallic phase mm - mass in metallic phase mPbC12 - lead chloride mass fed to the system MPbC12-TIC1 - mass in chloride phase MPb - lead atomic mass, g/mole MT1 - thallium atomic mass, g/mole K - Nernst distribution coefficient Xi - mole friction of solution component X°PbC12 - mole friction of PbC12 in saturated solution X°T1C1 - mole friction of T1C1 in saturated solution T - temperature, K R - gas constant, J/(mole K) k - kinetic equation constant, 1/(%-min.) ?i - solution component activity coefficient e - extraction rate, %

Jan 1, 2008

By Z. Hou

ABSTRACT: Short-term strength, damage and healing boundaries for rock salt are experimentally determined and integrated into the Hou/Lux-MDS damage-healing model. This model can be used to describe the mechanical behaviour of rock salt during a damaging process (under high stress to strength ratios) as well as during a healing process (under very low stress to strength ratios with high confining pressure). The development of the damage and the stress to strength ratio in the excavation damaged zone (EDZ) of a storage cavern under a minimum internal pressure as well as the development of the healing of damage and the stress to strength ratio under a subsequent maximum internal pressure are investigated project-related. The results of the investigation make it possible to shift the permissible minimum pressure boundary down, allowing the optimisation of decisive economic characteristics of storage caverns. RÉSUMÉ: Le comportement court terme, l’endommagement et les conditions de colmatage pour le sel gemme ont été étudiés expérimentalement et intégrés dans le model endommagement-colmatage Hou/Lux-MDS. Ce modèle permet de décrire le comportement mécanique de sel gemme pendant le processus d’endommagement (sous fort rapport contrainte-résistance) et le comportement du processus de colmatage sous très faible rapport contrainte-résistance avec forte pression de confinement. Le développement d’endommagement et le rapport de contrainte-résistance dans une zone d’endommagée (EDZ) d’une cavité de stockage avec un maximum de pression de soutènement ont été étudiés. Les résultats de cette étude permettent de conclure qu’il est possible de baisser la pression de soutènement, et par conséquent d’optimiser les caractéristiques économiques décisives des cavité de stockage. ZUSAMENFASSUNG: Für Steinsalz werden Festigkeits-, Schädigungs- und Verheilungsgrenze experimentell ermittelt und in das Schädigungs-Verheilungs-Modell Hou/Lux-MDS integriert. Damit kann das mechanische Verhalten von Steinsalz sowohl bei einem Schädigungsprozess (mit hohen Ausnutzungsgraden) wie auch bei einem Verheilungsprozess (mit niedrigen Ausnutzungsgraden) beschrieben werden. Projektbezogen werden die Schädigungs- und Ausnutzungsgradentwicklung in der Auflockerungszone einer Speicherkaverne unter einem minimalen Innendruck sowie die Verheilungs- und Ausnutzungsgradentwicklung unter einem anschließenden maximalen Innendruck untersucht. Die Untersuchungsergebnisse erlauben, die zulässige Minimaldruckgrenze nach unten zu verschieben, so dass entscheidende wirtschaftliche Kenngrößen von Speicherkavernen optimiert werden können.

Jan 1, 2003

By J. Sjöberg, P. Lundman, E. Nordlund, C. Quinteiro

Abstract In the Kiirunavaara underground mine, crude ore is transported through ore passes from the production levels to the main haulage level. Failure and stability problems have occurred in some of these ore passes, with increasing frequency as mining depths increase. In this paper, selected results are presented from a research project run by LKAB. The presentation focuses specifically on stability analysis. Numerical models were used to identify failure mechanisms, in conjunction with empirical data and engineering judgment. The most important controlling factors governing failure and damage in ore passes were quantified. A causative model was established in which failure mechanisms and failure development were described. This model was used to formulate a prognosis of future ore pass stability, and for recommending remedial measures. Résumé Le transport du minerai entre les niveaux de production et le niveau principal de transport, à la mine de fer de Kiruna, se fait par des passes à minerai. Avec la profondeur d'extraction grandissante, les problèmes de stabilité au niveau de ces passes à minerai se sont multipliés. Les résultats d'un programme de recherche sur la stabilité des passes à minerai à la mine de fer de Kiruna sont présentés dans cet article. Les mécanismes de rupture ont été identifiés à l'aide de modèles numériques, de données de terrain et du jugement empirique des ingénieurs. Les facteurs principaux controllant l'instabilité des passes à minerai ont aussi été quantifiés. Un modèle a été établi dans lequel les mécanismes de rupture et le développement des dommages ont été décrits. Ce modèle a été utilisé à fins prédictives et remédiatives. Zusammenfassung In der Grube Kiirunavaara wird das gewonnene Erz über Sturzschächte von den Abbauebenen zu der Hauptförderebene gefördert. Mit zunehmender Tiefe des Abbaus sind vermehrt Standsicherheitsprobleme in den Sturzschächten aufgetreten, die teilweise zu Verbrüchen geführt haben. In dem vorliegenden Beitrag werden ausgewählte Ergebnisse einer Forschungsarbeit des LKAB präsentiert. Dabei wird der Schwerpunkt auf die Standsicherheitsuntersuchungen gelegt. Zur Ermittlung der Bruchmechanismen wurden numerische Modelle in Verbindung mit empirischen Daten angewendet. Die wichtigsten Einflußfaktoren für das Versagen der Sturzschächte wurden ermittelt. Es wurde ein Modell zur Beschreibung der Bruchmechanismen und des Versagensablaufs aufgestellt. Dieses Modell wurde verwendet, um die Standsicherheit zukünftiger Sturzschächte zu prognostizieren und um Sanierungsmaßnahmen zu erarbeiten.

Jan 1, 2003

[Consider a square block W in an ore body S2, to be valued from one centre sample w, and one corner sample w2 (Fig. 9.1). The sample set is ws = Iw,;w21. We can estimate the block average µw by the average of the sample values x, and x2: µw = 'z (x, + xz). (9.1) The error made is measured by the estimation variance: o' (ws to W) = 2 - (ws; W) - - (ws;ws) - - (W; W). (9.2) However, we know that the centre sample w, gives more information about the block value than the corner sample w2. In the example studied in § 8.4, where w, and w2 were considered to be points, we found that of (w, to W) was nearly one third smaller than o2E (w2 to W), therefore when estimating W one should give more weight to w, than to w2. In general, when evaluating a block W from a set of n samples ws, where WS = l w;w2; ... wn1, a better estimator of µw can be obtained if we give different weights to the sample values, depending on the size and the positions of the samples. Some desirable properties of such an estimator µw are: ? It should be a linear function of the sample values xi: n µw = bi xi (9.3) =t where bi = weight given to sample x . ? It should be unbiased, i.e. its expected value should be equal to the true block value: E [µw - µw] = 0. (9.4) ? The mean squared error of estimation of µw should be a minimum E [(µw - µw)2] = a minimum. (9.5) The estimator which satisfies these properties is a minimum variance, linear and unbiased estimator, and is known as the kriging estimator. The corresponding error of estimation is the kriging error. This estimator is also known as the BLUE (for Best Linear Unbiased Estimator) estimator. This was named by Matheron in acknowledgement of the early work of Krige's in the optimization of the evaluation of the South African gold mines. The following notations will be used: µK kriging estimator. o2k = o2K (w,, to W) kriging error.]

Jan 1, 1978

By J. E. Quintanilha de Menezes, L. Ribeiro e Sousa, I. Ferreira

The Paradela dam has a spillway that makes it possible to discharge a maximum flow of 400 m3/s, the water discharges being on the river Sela, about 2km upstream the river Cávado. After the first use of the spillway, some landslides have occurred on the right bank of the river Sela as a result of the erosion generated on its base about one hundred meters near some houses of a small village. This paper presents a study performed for the slope stability where finite element results are taken into account. A monitoring program was established that essentially consisted of measuring sub-horizontal displacements in points located in boreholes at different depths and also phreatic levels. Some monitoring results are presented. Le barrage de Paradela a une décharge d’eau avec un débit maximal de 400 m3/s sur le fleuve Sela dans un endroit situé environ 2km sur l'amont du fleuve Cávado. Après la première utilisation de cette décharge, quelques glissements se sont vérifiés sur le versant droit du fleuve Sela résultant de l’érosion générée sur sa base dans une zone à 100 mètres de quelques maisons d’un petit village. Ce travail présente une étude réalisée concernant la stabilité du versant avec la considération des résultats des éléments finis. Un programme d’auscultation a été mis en place pour mesurer les déplacements sub-horizontales sur des points situés en forages à des différentes profondeurs. Quelques résultats de cette monitorization sont présentés. Der Ueberlauf des Padela Dammes ermoeglicht das Ablassen einer max. Wassermenge on 400 m3/s in den Sela Fluss, ca. 2 km flussaufwaerts des Cávado Flusses. Nach Inbetriebnahme des Ueberlaufes traten in ca. hundert Meter Entfernung zur Wohnbebauung eine Dorfes Erdrutschungen am rechten Ufer des Sela Flusses auf, die auf Erosionen am Flussbett zurückzuführen waren. In der vorliegenden Studie wurde die Boeschungsstabilitaet unter Beruecksichtigung von Berechnungsergebnissen der Finiten Element Methode untersucht. Es wurde ein essprogramm ausgearbeiten, das im Wesentlichen auf Messungen der Untergrundverformungen in verschiedenen Bohrlochteufen sowie auf Grundwassermessungen beruht. Im Folgenden sind einige Messergebnisse dargestellt.

Jan 1, 2003

By N. W. Munro

SYNOPSIS Certain disadvantages associated with the use of Anfex have been raised on previous occasions. This interim investigation shows that by loading at lower pressures the sensitivity to initiation of Anfex can be improved. Associated with this is a reduction in velocity of detonation and charge density which should lead to more desirable fragmentation. The effect of lower loading pressure on other factors is also considered. INTRODUCTION Discussion at the Symposium on the use of Anfex in Underground Mining, conducted by the South African Institute of Mining and Metallurgy during May 1968 showed that there was considerable uncertainty and diversity of opinion on the characteristics of Anfex and its method of application. Some of the disadvantages associated with the use of Anfex were: Inadequate sensitivity to initiation; Excessive fragmentation of the rock and damage to the hanging and footwalls; Wastage as a result of blow-back; Poor water resistance. As a result of this, further investigations on the properties of Anfex have been carried out and, although these have not reached finality, it is considered that a progress review may be of interest and assistance to the mining industry. EXPERIMENTAL TECHNIQUE The work was carried out on a laboratory-scale where, for test purposes, the explosive was loaded into 1 in. (nominal) internal diameter steel pipes unless otherwise stated. Charging was conducted with a 1 in. (nominal) Schutte-Koerting eductor having a 0.2 in. internal diameter venturi nozzle, the Anfex being fed into the eductor from a conical hopper fitted directly above it. A 5 ft long copper loading tube with outside and internal diameters of 3/4 in. and 5/8 in., respectively, was fitted to the discharge end of the eductor. The remote end of the loading tube was inserted into the test pipe so that it was about 6 to 8 in. from the closed end of the pipe. The loading apparatus was withdrawn as the pipe filled, maintaining approximately the same stand-off distance throughout the operation. REVIEW Sensitivity to initiation Sensitivity of Anfex to initiation was found to deteriorate when the dynamic pressure of the air to the eductor was increased. This was attributed to increasing charge density and it was found that at a charge density of about 1.05 g/cm3, which

The annual General Meeting of the Branch was held in the St. Helena Club on Wednesday, 4th August, 1971 at 8.00 p.m. Mr N. A. Honnet (Immediate Past Chairman) was in the chair. There were also present Mr V. C. Robinson, President of the South African Institute of Mining and Metallurgy. Nine Fellows: Messrs J. R. F. Handley, C. J. Isaac, J. Lorenzon, J. M. Meyer, C. Mostert, D. A. Smith, S. L. S. Swart, I Thomas and R. G. Williams. Five members: Messrs R. Campbell, A. H. Edwards, K. Pearce, G. P. Rundle and R. B. Sutherland. Five graduates: Messrs J. E. Andrews, E. J. Shillaber, M. H. Smith, T. R. Stromsoe and D. J. van Niekerk. Two associates: Messrs A. Paschalides and D. S. Robinson. Eight visitors. Total present: Thirty-one. MINUTES OF THE PREVIOUS GENERAL MEETING As the minutes of the General Meeting held on the 16th June, 1971, had not been published in the Journal, the Chairman moved that the adoption and discussion thereof be deferred to the next General Meeting. This motion was adopted unanimously. The minutes of the General Meeting held on the 10th February, 1971, were taken as read. The adoption, which was proposed by Mr D. A. Smith and seconded by Mr J. M. Meyer, was carried unanimously. At Mr Honnet's request, Mr V. C. Robinson took the chair during the presentation of the Chairman's Annual Report. CHAIRMAN'S ANNUAL REPORT 1970/71 1970/71 Committee-Office Bearers: Chairman - J. N. Saunders Vice Chairman - G. Y. Nisbet Immediate Past Chairman- N. A. Honnet. Due to the sudden retirement of Mr J. N. Saunders, the committee, at a meeting on the 3rd February, 1971 elected Mr G. Y. Nisbet as Chairman with Mr J. M. Meyer as Vice Chairman. After the transfer of Mr Nisbet to C.D.M., the committee, as a meeting on the 12th May, 1971, decided that Mr Meyer hold the Chair in an acting capacity for the remainder of the year. Committee members: Messrs C. J. Isaac, J. G. Kirchener, L. O. W. Leimer, R. S. Pearson, I. G. Thomas and A. von Holdt. Transfers of several office bearers and committee members resulted in Messrs J. M. Meyer, D. N. Smith and G. C. J. Young being co-opted onto the committee.

The May General Meeting of the Institute was held in Kelvin House, Johannesburg, on 21st May, 1969, at 4.30 p.m. Mr J. K. E. Douglas (Vice-President) was in the Chair. There were also present twenty-two Members, including Messrs F. P. Bath, M. Bareza, A. R. C. Fowler, D. M. Jamieson, C. M. Mavrocordatos, D. G. Maxwell and J. A. Nixon (Council Members), Messrs T. Davidson, G. L. Diering, E. T. Dunstan, D. E. H. French, K. Hodgson, O. A. E. Jackson, A. F. Lee, A. Louw, D. L. Starkey, R. K. Wheeler and M. Youngworth. Four Associate Members including Messrs D. Blair Hook and G. R. Still. One Student Mr N. A. Barcza. Thirteen Visitors, including Messrs S. H. Ash, D. L. G. Bayne, E. Bayne, S. Bell, W. S. Garrett, L. S. Gibbs, R. C. Hamilton, M. Maguire, D. Rose and J. D. van Niekerk. Total Present: Fourty-one. OBITUARY The Vice-President: "It is my sad duty to announce the death of the following member of the Institute: Thomas Spence Haldane, Member, who joined the Institute in 1924 and passed away on 21st December, 1968. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, those present stood and observed silence for a few moments. MINUTES The Vice-President requested that confirmation of the minutes of the previous meeting be held over as they would only be appearing in the Journal of the following month. He also requested that confirmation of the minutes of the 75th Anniversary Meeting be held over. MEMBERSHIP The Vice-President: "I have much pleasure in announcing that the names of the under-mentioned candidates have been published in accordance with By-Law 5.2.2, and Council has elected them to membership of the Institute in the following grades: Members: Gideon Jacob Haumann, Peter John Cumming, Ian Stanley Dudman, Roderick Goldston Murchison. Associate Members: Francois Alwyn Beyers Fouche, Alan Marsh, Johannes Petrus van der Westhuysen, Waldo Edmund Stumpf, Ian Nicholas Ridley. Affiliates: Lutgerus Kolver Jooste, Roger Ainsley Ralph Kebble, Edward John Wainwright, Lewis William Davies. Graduate: Clive Graham Knobbs. MEMBER TRANSFERED TO A HIGHER GRADE From Student to Associate Member: Diethard OUo Eduard Fahrbach. I welcome the newly elected members to the Institute and congratulate the member who has been transferred to a higher grade." (Applause).