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By S. A. Hosseini, O. Asghari

"The quantification of mineral resources and evaluation of process performance in mining operations at Gole Gohar iron ore deposit requires a precise model of the spatial variability of three variables (Fe, P, and S) which must be determined. According to statistical analysis there are complex multivariate relationships between these variables such as stoichiometric constraints, nonlinearity, and heteroskedasticity. Due to the impact of these complexities in decision-making, they should be reproduced in geostatistical models. First of all, in order to maintain the compositional and stoichiometric constraints, additive log-ratio (alr) transformation has been applied. In the next step cosimulation, using stepwise conditional transformation (SCT) and sequential Gaussian simulation (SGS) has been used to simulate multivariate data. Through statistical and geostatistical validations it is shown that the algorithms were able to reproduce complex relationships between variables, both locally and globally. IntroductionThe key steps in mining projects are the quantification of mineral resources, definition of mining reserves, and production scheduling. They rely on the construction of a block model that is used to represent basically the spatial distribution of ore grades (Montoya et al., 2012). The determination of grades and tonnages affects risk assessment and economic evaluation of mining projects. Evaluation of process performance in mining operations requires geostatistical modelling of many related variables (Barnett and Deutsch, 2012). Iron ore quality is characterized by multiple variables: not only the iron grade but also the contaminants that interfere in the subsequent steel manufacturing processes. Consequently, the spatial variability of multiple variables must be determined. Key variables are frequently correlated, and such correlations must be honoured during estimation and simulation. Data from iron ore deposits constitutes compositional data; furthermore, relationships the between assay data are often heteroskedastic."

Jan 1, 2016

By R. D. Cromarty, J. Du Toit

"Penetration of matte into tap-hole bricks causes detrimental refractory wear, which can lead to furnace breakouts. The ability of the tap-hole clay to form a protective layer on the brick, thereby limiting matte penetration was investigated by examining the interaction between platinum group metal (PGM) matte, tap-hole clay, and alumina-chrome refractory bricks on a laboratory scale.Samples containing clay and brick as well as samples containing clay, brick, and matte were heated to different temperatures to establish the clay-brick interaction and the extent of matte penetration. The greatest degree of physical contact between the brick and clay was achieved at curing temperatures of 600°C. Poor clay-brick contact was observed in the sample that was heated to 900°C.Matte displaced the clay in the clay-brick-matte sample that was heated to 1350°C, with significant matte penetration into the brick. Less matte penetration was observed when the clay-brick-matte sample was heated to 1500°C. Less matte penetration was also observed in the claybrick- matte sample in which the clay and brick were pre-baked at 800°C, and the sample then reacted with matte at 1350°C. IntroductionFloatation concentrate from ore from the eastern Bushveld Complex of South Africa, specifically the Platreef, Merensky, and UG2 reefs, forms the feed to the Polokwane platinum smelter (Hundermark, De Villiers, and Ndlovu, 2006). The ore from the UG2 Reef has a high chromite content, which requires high operating temperatures (1500–1700°C) to avoid chromium spinel build-up in the furnace hearth. These high operating temperatures lead to matte superheats in the vicinity of 500– 600°C, which put increased demands on the refractory materials (Nelson et al., 2005).Upon tapping, the matte moves through the tap-hole, which consists of an aluminachrome refractory brick-lined tapping channel (Hundermark, De Villiers, and Ndlovu, 2006). The flow of molten matte is stopped by the injection of tap-hole clay to form a plug in the tap-hole. The tap-hole clay hardens and strengthens during curing to obtain the required hardness and refractoriness against penetration, corrosion and erosion (Nelson and Hundermark, 2014)."

Jan 1, 2016

By D. J. Bosman

Rapid fouling of condenser tubes in underground refrigeration plants is a frequent occurrence. It leads to low heat transfer efficiencies, with consequent serious reduction in capacity and increase in the horse-power requirement of the units. High pressures develop in the condensers, and frequent cleaning of the tube bundles is required. The cleaning operation takes up to 8 hours and in some cases results in significant loss of production. One of the possible causes of fouling is deposition of scale, but this can be readily overcome by controlling the concentration of the water. When water evaporates, the dissolved solids remain behind; thus evaporation increases the amount of dissolved solids per unit volume. If half the original volume evaporates, the concentration of the dissolved solids is doubled and the water is said to have a 'concentration' of two. Concentration may be controlled by regulating the amount of water allowed to bleed from the system. The actual concentration value required is a function of the chemical analysis of the circulating cooling water. In one instance, where the problem of scale formation had been eliminated, fouling still persisted, and the possibility of excessive quantities of dust in the re-circulating water was investigated. A dispersing reagent was added to the condenser cooling water as a means of preventing sludge deposition in the condenser tubes. As shown by curve A in Fig. 1 the reagent addition did not decrease the rate of fouling.

By A. Moerman, M. Verreault, V. Falmagne

Noranda has been involved in the development of technologies for automated mining vehicles since 1988, and has contributed in transferring the technological foundation for the suite of SIAM products now being commercialized by STAS. Some of these technologies are now mature and available for commercial implementation in operations where a strong business case can be made for the use of automation. Noranda has successfully implemented or is commissioning the Tele-remote, Auto-loading and truck Guidance technologies at two of its operations, based on operating needs and economic justifications. Operator acceptance, training and maintenance issues have been addressed in order to ensure the reliability and availability of the automation components. These represent the most significant challenges encountered and addressed during the implementation period.

Sep 1, 2001

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 27th August, 1969, at 4.15 p.m. Mr. R. C. J. Goode (President) was in the Chair. There were also present seventy Members, ten As¬sociate Members, two Affiliates, one Student and twelve Visitors making a total of ninety-five. The President declared the meeting open at 4.20 p.m. OBITUARIES The President: "It is my very sad duty to announce the deaths of the following members of the Institute: Mr James Charles Napoleon Humphreys, a Life Member who joined the Institute on 1st April, 1935, and passed away on 6th February, 1969. Mr Michael John Worrall, Graduate Member, who joined the Institute in 1960 and passed away on 2nd June, 1969. Mr Eric Adam Conrad Dickson, Associate Member, who joined the Institute on 13th June, 1952 and who passed away on 8th June, 1969. Mr Robert Jack, Associate Member, who joined the Institute on 2nd August, 1956, and passed away on 14th June, 1969. Mr R. A. H. Flugge-de-Smidt, Honorary Life Member and Gold Medallist, who joined the Institute in 1922 and passed away on 17th June, 1969. Mr John Gordon Craig, a Member who joined the Institute on 23rd August, 1960, and passed away on 6th August, 1969. As a mark of respect to the memory of the deceased, and in sympathy with the bereaved, I would ask you to rise and observe a few moments silence." MINUTES The President: "May we confirm the Minutes of the General Meeting held on 18th June, 1969, as published in the July, 1969, issue of the Journal?"-Agreed. WELCOME TO VISITORS The President: "We are honoured this afternoon by the presence of the Institute's Honorary President, Mr R. S. Cooke, President of the Chamber of Mines of South Africa, and by one of our Honorary Vice-Presidents, Mr T. L. Gibbs, the Government Mining Engineer, as well as by the presence of many distinguished guests, to all of whom I extend a most cordial welcome. We are happy to have present, Mr S. C. M. Naude, Director of the Witwatersrand Technical College, Mr G. A. P. Louw, Vice-President of the Associated Scientific and Technical Societies, Mr R. P. Randall, Senior Vice-President of the South African Institute of Electrical Engineers, Mr W. T. L. Wayman, President of the South African Institution of Mechanical Engineers, Mr D. F. Odendaal, President of the Institution of Certificated Mechanical and Electrical Engineers of South Africa, Mr E. Haacke, President of the Institute of Land Surveyors of the Transvaal, Mr B. L. Loffell, Vice-President of the South African Institution of Civil Engineers, Mr J. F. Leatherbarrow, President of the South African Institute of Assayers and Analysts, Dr W. S. Rapson, President of the Joint Council of the South African Scientific Societies, Dr P. L. Carman, President of the South African Chemical Institute, Mr F. Jackson, President of the Federation of Societies of Professional Engineers, Mr W. E. Kirkwood, President, S.E.I.F.S.A., Mr J. Steele, President of the South African Institute of Foundrymen, Mr M. Waite, President of the South African Institution of Welding, Mr M. R. Gericke, President of the South African Council of Professional Engineers, Mr G. C. Sowry, Chairman, Witbank-Middelburg Branch, Mr T. Groenewald, Chairman of the South African Chemical Institute (Southern Transvaal Section), Professor O. B. Volckman, Chairman of the South African Institution of Chemical Engineers, Mr H. W. Le Roux, Chairman of the South African Federation of University Engineer¬ing Students, Dr R. E. Robinson, Director of the National Institute for Metallurgy, Mr P. H. Anderson, Deputy-Chairman of Rand Mines Limited, Mr E. Boden, Manager of the A.S. and T.S. and Count Folchi-Vici, from Italy, who has lime interests in this country. I also extend a very special welcome to the lady guests here this afternoon, and to all the visitors." MEMBERSHIP The President: "I have pleasure in announcing that the names of the following candidates, having been published in accordance with By-Law 5.2.2, Council has elected them to membership in the following grades: NEW APPLICATIONS Members: Stuart Denston Hill, Robert Roy Richardson, Gert Paulus van der Vyver. Affiliates: Henry Clifford Read, Allen Edward Hooper, Alan Edwin Edkins. Graduates: Lester Winston Sturgess, Erroll Vincent Bosman. Students: Terence Vernon van Heerden, David Curtis Lindley. MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate Member to Member: Andries Willem van Zyl, Roy Lardner, Nugent Gerald Ward Comyn. From Student to Graduate: Michael John Worrell (now passed away), Peter John Hamilton Short. I wish to welcome the new members to the Institute, and to congratulate those members who have been transferred to a higher grade." ANNUAL REPORT OF THE COUNCIL AND ACCOUNTS FOR THE YEAR ENDED 30th JUNE, 1969 The President: "Ladies and gentlemen, It is with much pleasure that I present to you the Annual Report and Accounts for the year ended 30th June, 1969. These have been laid on the chairs and before calling for their adoption I would like to make a few comments. The Accounts show an excess of expenditure over income of R2,124 and our Honorary Treasurer, Mr D. G. Maxwell, will in due course comment on this. The main difficulty has again been the cost of the Journal and I think most of you are aware of the changes that we propose to make. I shall be sorry to see the last of our old format but then I have always had rather a con¬servative outlook.

By Henk van der Bijl, Sean Rogers, Eugene Sidorski, Alan Carpenter

The electrode column is the heart of the submerged arc furnace. Superior electrode performance provides improved furnace performance. This paper describes the main features of the electrode column that delivers superior performance in furnaces worldwide, developed by Pyromet. Pyromet?s electrode comprises the compact slipping device, lower electrode assembly, upper and lower mantles, self-adjusting electrode seal, paste heaters, and Pyromet?s patented innovative electrode breakage detection and length determination system. Pyromet?s slipping device features compact interlocking clamping rings, incorporating fail-safe spring-loaded design. The interlocked clamping rings distribute the clamping force over a larger area of the electrode casing, preventing damage. The slipping device assembly features a low maintenance modular design that allows rapid slipping cycle times, back slipping, and compatibility with Pyromet?s electrode breakage detection and length determination system. Pyromet?s lower electrode assembly consists of the contact shoes, pressure bellows, pressure ring and heat shields. The contact shoes and pressure ring are designed for long, trouble free operation whilst the pressure bellow configuration equalise contact pressure and current distribution. Furthermore, the contact shoes incorporate a self cleaning feature, ensuring optimum electrical contact. The segmented design offers easy maintenance. Pyromet?s clients experience less down time due to longer component life. Pyromet?s remote adjusted electrode seal assembly reduces the rope seal working temperature, increasing rope life. The self compensating rope seal clamping force ensures an effective seal as the rope wears. Pyromet?s electrode breakage detection and length determination system detects electrode breaks utilising Pyromet?s electrode holder and data processing system. The length measurement system controls electrode length, eliminating the occurrence of short electrodes. The length measurement system furthermore eliminates the need for manual electrode length measurement, reducing associated production losses during furnace burn downs.

Jan 1, 2007

By Page-Shipp. R. J., Elizabeth Harris

A study of the response of South African white gold miners to exposure to dust in their working environment yielded large quantities of dust data. Analysis of this data (presented in summarized form) reveals a variety of interesting relationships, including the shift-long exposure of different occupational groups, the dust levels due to various mining operations, relationships between different dust-measuring procedures and time trends in dust levels during the shift. The statistical probability of contracting silicosis at various levels of exposure to this dust is reported briefly. A new method of using microscope counts to estimate the respirable mass of dust samples is given in an appendix.

By Northrop. I. N.

Hardmetals possess extremely high hardness and wear resistance, which render them ideal for applications such as metal-cutting tools, rock-drilling tools, and industrial wear-resistant parts like dies, punches, and seals. However, hardmetals are britle, and show poor resistance to impact and shock. They can therefore rarely be used unsupported, and it is common practice to attach hard metal working parts to a more resilient tool holder or support, which is normally made of steel. . . . Owing to the widely differing physical and mechanical properties of steels and hard metals, the Joining of one to the other is problematic, and the method used must be chosen with care. This paper reviews several methods available for the joining of hardmetal to steel, and discusses the advantages and disadvantages of each.

Jan 1, 1987

By A. Koursaris, H. M. Friede, A. A. Hejja

The features of smelting slags from South African prehistoric sites and of related cinder material are described. Chemical analyses of twelve slag samples found in the Transvaal, Swaziland, and Botswana are reported and discussed. An attempt is made to establish a relationship between these slags and the ores collected at the Early Iron Age site of Broederstroom, which date between AD 350 and AD 600. The liquidus temperatures of29 slags were determined by the use oh hot-stage microscope. The major mineral phases of 16 slags were identified by X-ray diffraction and microscopic examination. It appears that the slags investigated were formed at temperatures below 1250°C or - in some cases - at temperatures only marginally in excess of 1250°C.

Jan 1, 1982

The refractoriness of the gold in many of the pyritic ores from the eastern Transvaal is due mainly to the association between the gold and the sulphides, but it can be due to the presence of graphltlc carbonaceous material, which complicates the recovery of the gold by virtue of its adsorption activity. In an examination of the roasting characteristics of three flotation concentrates from the Barberton area, It was found that the gold in the concentrates occurred mostly in two forms: in very fine gold particles distributed within the arsenopyrite, and in a slightly coarser form loosely associated with the pyrite. Direct cyanidation of the concentrates gave gold extractions of from 16 to 30 per cent. After the concentrates had been roasted at temperatures of 650 to 700°C for 20 minutes with rabbling, the extractions varied from 86 to over 90 per cent. Examination of the residues after cyanidation indicated that gold was present in the porous calcines or in the calcined sulphide product. This observation, together with porosity measurements, suggests that physical encapsulation of the gold particles is the main reason for the refractory behaviour of the gold in the calcines.

Jan 1, 1988

To the trustees of The SAIMM Scholarship Fund We have audited the annual financial statements of The SAIMM Scholarship Fund set out on pages 587 to 592 for the year ended 30 June 2005. These financial statements are the responsibility of the trustees. Our responsibility is to express an opinion on these financial statements based on our audit. Scope We have conducted our audit in accordance with International Standards on Auditing. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes: examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audit provides a reasonable basis for our opinion. Audit opinion In our opinion, the financial statements fairly present, in all material respects, the financial position of the trust at 30 June 2005 and the results of its operations and cash flows for the year then ended in accordance with South African Statements of Generally Accepted Accounting Practice.

Jan 1, 2005

By G. P. Dyke

The MRMR Classification System was developed specifically for mining applications, namely caving operations, and is one of three rock mass classification systems used in the South African mining industry today. Increased usage of the MRMR Classification System has raised concerns that it does not adequately address the role played by discontinuities, veins and cemented joints in a jointed rock mass. To address these concerns, Laubscher and Jakubec introduced the In-Situ Rock Mass Classification System (IRMR) in the year 2000. Although the IRMR System is more applicable to a jointed rock mass than the MRMR System, a quantitative comparison of the MRMR and IRMR Classification Systems indicates that there is not a significant difference between the resultant rock mass rating values derived from the two Classification Systems.

Jan 1, 2008

By G. P. Dyke

The MRMR classification system was developed specifically for mining applications, namely caving operations, and is one of three rock mass classification systems used in the South African mining industry today. Increased usage of the MRMR classification system has raised concerns that it does not adequately address the role played by discontinuities, veins and cemented joints in a jointed rock mass. To address these concerns, Laubscher and Jakubec introduced the In-Situ Rock Mass Classification System (IRMR) in the year 2000. Although the IRMR system is more applicable to a jointed rock mass than the MRMR system, a quantitative comparison of the MRMR and IRMR classification systems indicates that there is not a significant difference between the resultant rock mass rating values derived from the two classification systems.

Jan 1, 2008

By A. Refahi

For predicting the energy consumption during the size-reduction process, the Bond approach is often used. In this work, the PFC3D discrete element method (DEM) software was employed to model the crushing behaviour of some rocks with different mechanical properties in a laboratory jaw crusher. FLAC3D software was adopted to analyze the stress distribution in the rocks. The rocks studied were modelled as granular assemblies in the shape of a sphere and/or a cube located between two jaws, and the work done by the jaws in the crusher was determined. Nine different types of rocks were studied and the energies consumed by the crusher were compared to those of the Bond comminution energy estimated from the Bond index. There is considerable difference between Bond crushing energy and work done by the jaw crusher for rocks. It appears that the Bond approach is not a suitable method for predicting single particle fracture energy done by the crusher. To verify the results obtained from DEM models, the fracture behaviour of the crushed rocks was examined and was compared to the PFC3D results. The tensile mode of fracturing is favourably modelled by the PFC3D software while the delamination mode cannot be well modelled by PFC3D software. Keywords: jaw crusher; discrete element method; crushing energy; Bond index

Jan 1, 2009

By Sabine Verryn, Johan de Villiers

"Through the application of the Rietveld method, X-ray diffraction analysis has developed into a fully quantitative method for phase analysis. The Rietveld method itself has progressed from an unstable method that required constant operator intervention to a stable and robust method suited even for routine analysis. The method however, requires a good initial calibration and periodic checks on its precision and accuracy.Several examples from minerals processing, pyrometallurgy, and materials science show the strengths and applicability of the method. The limitations and sources of error are also discussed.1. IntroductionDiffraction of X-rays by matter has been used for more than 80 years, initially to elucidate the structure of crystalline matter, and to investigate the bonding between atoms. The first development of powder diffraction cameras and the later development of X-ray diffractometers saw the development of methods to identify phases and to try to quantify them in mixtures. A comprehensive database and search-match techniques have been developed over the ensuing years. Effective and accurate quantification had to wait for the so-called Rietveld' analysis where the total diffraction pattern is used and where the crystal structure data for the constituent phases are needed as input. Overlapping of diffraction peaks of different phases is handled without difficulty and reliable results can be obtained in spite of this occurrence.The development of methods for structure analysis from powder data has also progressed rapidly and more and more complex structures are being solved from first principles, i.e. without knowledge of unit cell or space group data. Because of the ease of use of the Rietveld method, it is finding increased application in metallurgy, especially in the quantification of phases of importance in minerals processing, in pyrometallurgical processes, and in materials characterization. This study will examine the principles of the Rietveld method, its application in metallurgy, and finally also the common pitfalls that need to be avoided.2. Rietve1d AnalysisAs the Rietveld method compares the experimental diffraction pattern with one calculated from known crystal structure data, the following data are needed:•,An XRD Pattern with as Iowa background as possible. This should have good resolution and high diffraction peak intensities. With modem X-ray detectors, this can be achieved in minutes rather than hours.•,Instrumental parameters such as goniometer radii and slit sizes are needed. These are the so-called ""Fundamental parameters"". They are used to calculate the shapes of the resultant diffraction peak profiles that are caused by the instrument. The parameters are used to correctly separate the instrumental effects on the diffraction pattern from the sample effects."

Jan 1, 2014

There are presently no suitable underground mine production scheduling optimisation models available for application to sublevel stope mining. Scheduling underground production for maximum return is therefore still a manual process, which generally involves scheduling production from the next available highest cash flow stope within the operational constraints of the project. In most mining operations, the scheduling problem is too large and complex to guarantee truly optimal results through manual scheduling. This paper reviews some general optimisation studies that have been proposed for underground hard rock mining. Furthermore, an example of a mixed integer programming model is presented for a small conceptual sublevel stoping operation. Comparative results of a schedule generated by a mixed integer programming (MIP) production scheduling model and a manually generated model on a nine stope example is presented. Results indicate that the potential benefits of the MIP production scheduling model for the purpose of maximising NPV are significant. Finally, a new constraint was formulated to limit multiple exposures of fill masses for use in an existing MIP production scheduling model. Testing of the formulation took place on the central stope of the nine stope example, which showed that the formulation performed its task without breaking other operational constraints.

Jan 1, 2007

By M. R. Khalesi

A method is proposed to estimate the gold content of the ore in the size intervals during size reduction. The method uses the population balance model to trace the gold deportment through the size fractions and monitor the generation of liberated gold grains during the size reduction. The model is calibrated using batch grinding test results of a gold ore. Preliminary results show that the model can be calibrated with a minimum of parameters compared to conventional grinding-liberation models. Keywords: simulation, liberation, gold, exposure, grinding

Jan 1, 2009

By E. Harris

Frithia humilis is an endangered succulent plant species. Its distribution range overlaps with the coal fields of Mpumalanga and it is therefore threatened by opencast mining activities in particular. One of the 11 known populations of F. humilis was translocated from a licensed coal mining site to three suitable receptor sites within the species? distribution range. A longterm monitoring programme was initiated to track the progress of the newly established populations. Temporal trends in population demography, size classes, and fecundity were recorded. Population numbers of size classes fluctuated annually. However, flower frequency increased over time and seedling recruitment contributed significantly to population growth. Receptor sites with similar geological conditions to the donor site had more persistent cohorts, which suggest that such sites should receive priority during the translocation of endangered edaphic specialists. This study not only confirms that a Frithia humilis population can successfully establish after a translocation, but also serves as an important baseline for future comparative purposes to gauge the long-term success of the translocation effort.

Jan 1, 2014

By B. O. Odera

The Pt-based alloys have a high potential for replacing some Ni-based superalloys (NBSAs) used in the highest temperature and most aggressive environments, and vanadium would be a beneficial alloying element. Six alloys of average compositions Pt-26.6Al-9.1V, Pt-23.1Al-17.8V,Pt-9.6Al-21.1V, Pt-17.4Al-6.4V, Pt-22.3Al-7.9V, and Pt-6.0Al-10.1V (all in at.%) were manufactured by arc-melting and examined in the as-cast condition using scanning electron microscopy and X-ray diffraction (XRD). Five samples were heat treated at 1 000°C for 1 500 hours and water quenched, then examined. The phases were identified using energy-dispersive X-ray spectroscopy and the identities were confirmed by XRD. In most of the samples, the phases existing in the as-cast condition were different from those at 1 000°C after ~1500 hours heat treatment. A solidification projection, an isothermal section and a liquidus surface projection were determined for the Pt-rich corner.

Jan 1, 2012

The inherent weakness of the Zincor and similar iron removal processes is the relatively high undissolved zinc loss associated with the iron residue. High soluble zinc losses also occur due to poor filterability of the iron residue even though it may be limited to intermittent events. This work focussed on defining the optimum operating window for the Zincor iron removal process where iron is mainly removed in the form of amorphous, intermediate iron phases such as schwertmannite and ferrihydrite. In terms of the main operating conditions, optimum filterability was achieved under the following conditions: pH of 3.0, temperature as high as practically possible (70C), at least 25 kg/m3 seeding, and a retention time of at least 4 hours. When increasing the temperature from 60C to 70C, the required residence time decreased by almost 50%. Undissolved zinc loss was also reduced from 8% to between 2% and 3% by using a basic zinc sulphate/zinc oxide mixture as neutralising agent to effect iron removal.

Jan 1, 2003