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1. Book reviews Mill Operators' Conference. Parkville (Australia), Australasian Institute of Mining and Metallurgy, 1982. 425 pp. Reviewer: B. K. Loveday Off highway truck haulage. Newman Combined Group, the Australian Institute of Mining and Metallurgy and the Institute of Engineers in Australia. Sep. 1982. Reviewer: B. J. Vorster Environmental engineering in South African mines.Johannesburg, Mine Ventilation Society of South Africa, 1982. 974 pp. Reviewer: A. N. Brown Underground Operators Conference. West Coast Tasmania Branch. Australasian Institute of Mining and Metallurgy. Reviewer: D. R. Aspeling 2. New publications Electric steelimaking in the eighties: challenges and opportunities. Rotterdam, Balkema, 1982. 362 pp. $50.00 or £33. Tungsten: a review, by P. M. Harris and D. S. C. Humphreys. London, Institution of Mining and Metallurgy (Occasional Paper 2), 1983. Members: £3, nonmembers £6. The platinum industry - prospects in recovery. London, Shearson{American Express Ltd (St. Alphage House, Fore Street, London EC2Y 5DA), 1983. £75. The best of E&MJ mining and processing idea book' New York, Engineering and Mining Journal, 1983. 128 pp. Free with subscription to Engineering and Mining Journal. Mining 1983. Harlow (U.K.), Longman Group Limited, 1983. 500 pp. £39.50. Ooncise guide to world coalfields. London, World Coal Resources and Reserves Data Bank Service (14/15 Lower Grosvenor Place, London SW1W OEX), 1983. 380 pp. £45. 3. Canadian publications Asbestos, by G. O. Vagt, 9 pp. Ooal and Coke, by J. A. Aylsworth, 16 pp. Orude oil and natural gas, by R. L. Thomas, 12 pp. Phosphate, by G. S. Barry, 8 pp. Rhenium, by S. A. Hamilton, 3 pp. 4. Mintek reports Report 2102D The recovery of magnesite from dump fines from the Strathmore Mine. (First issued Feb. 1981.) Report 2106D The evaluation of drill cores and a bulk sample from a deposit of andalusite near Thabazimbi. (First issued Mar., 1981.) Report 2108D Evaluation of a grinding aid in batch grinding, classification, and gravity concentration. (First issued Jul. 1981.) Report 2109D The evaluation of an andalusite deposit from Kleinfontein, Groot Marico. (First issued Apr. 1981.) Report M7D The beneficiation of chromite ore from the Ma-l seam near Marikana. (First issued Nov. 1981.) Report M62 A preliminary investigation into the extraction of zinc by direct oxidative leaching of high-manganese sphalerite. Report M76 A mineralogical investigation of a refractory gold ore, and of a sulphide concentrate and calcined tailing from that ore. Report M85 List of unrestricted Mintek publications issued from 1966 to 1982. Report M97 Reduction in metal consumption by the use of alternating lines of higher and lower lifter bars in a rod mill. Report M98 Multivariable control and optimization of the operation of a milling circuit at East Driefontein Gold Mine. Report M101 The potentiality of heat-treated balls in the grinding of gold ores. X-ray diffraction The Southern Transvaal Section of the South Mrican Chemical Institute is to present a mini-course on 'X-ray Diffraction: Theory and Application' in Johannesburg on 18th and 19th October, 1983.

Jan 1, 1983

By H. P. Coetzee, V. J. Solomon

As the price of gold increased, so did the viability of mining previously abandoned unpay areas of Stilfontein Mine. After an assessment to confirm the profitability of mining these areas, it was necessary to re-establish access-ways such as haulages, cross-cuts, and travelling ways. Openingup is a labour-intensive, relatively slow operation, and attempts were made to mechanizeand speed it up. Some of the techniques applied and the results achieved, whether successful or not, are discussed.

Jan 1, 1982

By C. Massola, E. E. M. N. de Guzmán, M. G. Bergermana

The abrasiveness of a mineral or rock is an extremely important topic in the mining industry and is generally measured by the Bond abrasion index (AI). However, to determine such an index by the Bond test requires 1,600 g of sample with particle sizes ranging from ½” to ¾”, which are not available in certain situations, such as ore prospecting, drilling, and geometallurgical studies. In order to investigate the abrasiveness of smaller-sized sample materials, a modified LCPC test was developed, which allows testing fine materials (i.e., 1.0 mm or smaller) to predict wear in ore processing circuits and anticipate possible failures resulting from changes in abrasive characteristics of the ore being processed. The results for 16 different materials indicated a good correlation with the AI and the modified LCPC, resulting in a reliable alternative for the AI. Keywords: Bond Abrasion Index (AI), LCPC, abrasiveness

Jan 1, 2020

By A. A. Bradley, P. J. D. Lloyd, A. J. Freemantle

Developments in centrifugal milling by A. A. BRADLEY,B.Sc. (Rhodes) (Visitor), A. J. FREEMANTLE, B.Sc. Hons. (Wits) (Visitor), and P. J. D. LLOYD, B.Sc. (Chem. Eng.), Ph.D. (Cape) (Fellow) The theoretical and experimental results of a study of centrifugalmills are reviewed. Means for the scaling up of such mills are suggested, and tests on a prototype mill are described. Despite the high lining wear in the centrifugal machine, which reduces its productive availability, its other advantages suggest that there is merit in pursuing its further development.

Jan 6, 1974

By D. Clement

A comparison between hydraulic and pneumatic rockdrills by D. CLEMENT The regulation of compressed-air reticulation systems is very poor compared with that of electrical systems; this means that electrohydraulic rockdrill systems offer greater flexibility, additional power being readily available at the working face. Hydrometallurgy A new journal devoted to all aspects of the aqueous processing of metals is scheduled to appear this year. Entitled Hydrometallurgy, the journal will be published in quarterly issues, one volume per year. Mineral dressing Contributions are invited for the Symposium on Recent Progress in Mineral Dressing in South Africa, which is to be arranged jointly by the South African Institute of Mining and Metallurgy and the National Institute for Metallurgy. Mineraalbereiding Bydraes word verlang tot die Simposium oor Onlangse Vordering met Mineraalbereiding in Suid-Afrika wat gesamentlik deur die Suid- Afrikaanse Instituut vir Mynbou en Metallurgie en die Nasionale Instituut vir Metallurgie gereel gaan word. Rock mechanics The Sixteenth Symposium on Rock Mechanics is to be held at the University of Minnesota from 22nd to 24th September, 1975. The Symposium is the official Symposium for 1975 of the International Society for Rock Mechanics (I.S.R.M.), and the Council for I.S.R.M., consisting of members from 25 countries, will meet during the Symposium. Powder metallurgy The annual meeting on powder metallurgy organized by The Metals Society is this year to be held at the Stratford Hilton Hotel, Stratford-upon-Avon (the notification did not include the date of the meeting). Vacation School The South African Institute of Mining and Metallurgy has great pleasure in announcing its intention of holding a vacation school on the topic of electric-furnace melting. NIM reports Report no. 1681 The determination of sulphur and phosphorus in chromite. Report no. 1687 The viscosities and electrical conductivities of slags associated with the production of high-carbon ferromanganese alloys.

Jan 3, 1975

By C. V. O?Keefe

Volumetric flow and mass flow are two of the critical process parameters needed to understand and control flotation processes, with others being levels, densities, and metal analyses. Both volumetric flow and density measurements can be adversely influenced by entrained air, which will result in artificially high flow readings and artificially low mass flow calculations. Array-based instrumentation has been used successfully to accurately measure both volumetric flow of aerated slurry and the quantity of air entrained within the slurry. The latter measurement has been used to correct density measurements, thus providing an accurate mass flow calculation. A case study involving the use of this technology to measure both flow rates and air entrainment levels at Eland Platinum processing facility (concentrator) will be covered in detail. In addition, with certain traditional flow meters such as electromagnetic meters, erroneous volumetric flow rates can be recorded in the presence of paramagnetic or ferromagnetic material. The use of this array technology to avoid spikes in measurements due to steel fragments passing through the pipe will also be discussed.

Jan 1, 2012

By S. M. Spottiswoode, Linzer. L. M.

We report on further progress in improving seismic locations by using the so-called double-difference method (Spottiswoode and Milev, 1998 and Waldhauser et al., 1999). Double-differences are obtained either using picked arrival times or various measures of time differences obtained from waveform pairs. The double-difference method provides for much improved relative locations by reducing the effect of the errors in the wave velocity of ray paths between each event and each geophone. Further improvements are obtained by using known locations, such as blasts. One of the difficult problems that we have overcome is that of finding the best “weights” for the time corrections. Experience obtained in relative moment tensor inversions by Andersen (2001) suggests that use of median corrections is both more stable and more accurate, even while the locations of the individual events is based on weighted least-squares minimization. A hybrid location program with known reference events has been developed. Tests on a synthetic data set gave relative locations that were much less widely spread than the absolute locations. The use of known event coordinates (blasts) moved the relative locations back towards the real locations. These results are confirmed in preliminary analysis of data from a mine. The absolute locations are adjusted using blast events restricted to the line of tunnel development. Inter-event distances are distributed in a power-law fashion that suggests that the relative location accuracies are improved by a factor of three or more. Nous rendons compte des progrès faits dans l’amélioration des locations de séismes en utilisant la méthode appelée de double- différence (Spottiswoode and Milev, 1998 et Waldhauser et al., 1999). On obtient les double-différences soit en utilisant des temps d’arrivée choisis soit des mesures variées de différences de temps obtenues de doublets de forme d’onde. La méthode de double-différence fournit des locations relatives très améliorées en réduisant l’effet des erreurs dans la vitesse d’onde des trajectoires de rayon entre chaque évènement et chaque géophone. D’autres améliorations sont obtenues en utilisant des locations connues, telles que les coups de mine. Un des problèmes difficiles que nous avons surmontés est celui de trouver les meilleurs coefficients de pondération pour les corrections de temps. L’expérience obtenue dans des inversions de phases tensorielles relatives par Andersen (2001) suggère que l’utilisation de corrections médianes est à la fois plus stable et plus exacte, même lorsque la location des évènements individuels est basée sur minimisation pondérée de moindres carrés. Nous avons développé un programme hybride de location avec des évènements connus pour référence. Des tests sur des données artificielles ont donné des locations relatives qui étaient beaucoup moins étendues que les locations absolues. L’utilisation de coordonnées d’évènements connus (coups de mine) a ramené les locations relatives vers les locations réelles. L’analyse préliminaire des données d’une mine a confirmé ces résultats. Les locations absolues sont ajustées en utilisant des évènements de coup de mine restreints à la ligne du développement du tunnel. Les distances entre chaque évènement sont distribuées comme par loi exponentielle ce qui suggère que les degrés d’exactitude des locations relatives sont améliorés par un facteur de trois ou plus. Wir berichten über einen weiteren Fortschritt, die seismische Positionen unter Verwendung der zu sogenannten Doppel-Unterschied-Methode (Spottiswoode und Milev, 1998 und Waldhauser et al.,1999) zu verbessern. Doppel-Unterschiede werden entweder mit ausgewählten Ankunftszeiten oder verschiedenen Messungen von Zeitunterschieden erreicht, die von den Wellenformpaaren erhalten werden. Die Doppel-Unterschied-Methode liefert viel verbesserte relative Positionen unter Verringerung der Auswirkung von Fehlern in der Wellengeschwindigkeit von Strahlengängen zwischen jedem Fall und jedem Geophon. Weitere Verbesserungen werden erreicht, indem man bekannte Positionen, wie Sprengungen verwendet. Eines der schwierigen Probleme, die wir überwunden haben, ist jenes des Findens der besten "Gewichte" für die Zeitkorrekturen. Die Erfahrung, die in den relativen Momentspannerumkehrungen von Andersen (2001) gewonnen werden bietet den Schluß an, daß der Gebrauch von mittleren Korrekturen beständiger und genauer ist, sogar wenn die Positionen der einzelnen Fälle auf der bewerteten Reduzierung der Methode der kleinsten Quadrate basiert. Ein hybrides Positionsprogramm mit bekannten Bezugsfällen ist entwickelt worden. Tests auf einem synthetischen Dataset gaben relative Positionen, die viel weniger weit gestreut waren als die absoluten Positionen. Der Gebrauch von bekannten Fallkoordinaten (Sprengungen) schob die

Jan 1, 2003

By T. Szendrei, S. Tose

The fracturing and movement of rock that occurs in the vicinity of a stemmed borehole charge in open pit mining operations are described by examining the effects of the emitted stress waves – shock and elastic – and the expansion of high-pressure detonation product gases. Three principal modes of momentum transfer to fractured rock are identified, all linked to gas expansion work. This work can be delivered radially (burden), axially (stemming), and in the collar zone (cratering). Flyrock is generated under unusual combinations of blast parameters and rock properties. Although infrequent and seldom predictable, the generation of flyrock can nonetheless be interpreted and modelled in terms of the principal mechanisms of rock projection described in this study. The physical processes underlying these principal mechanisms are identified and will permit the development of predictive models for flyrock velocities.

Dec 13, 2023

This paper presents the development of a regrind facility design at BHP Billiton's Leinster Nickel Operations (LNO) in Western Australia. The recovery opportunity was identified from an analysis of plant operating data together with scanning electron microscope (SEM) measurements on relevant tailings streams from LNO. A laboratory procedure was developed to determine the potential recovery improvement of installing a regrind facility at LNO. The last step in formulating the process flow sheet and defining the process design criteria was to construct and operate a pilot plant, which incorporated four banks of flotation cells and an Xstrata M20 Isa Mill. Pilot plant on/off trials were used to define the expected metallurgical benefit. A prefeasibility engineering design and cost estimate was completed. Following a successful internal business evaluation, a feasibility study is currently underway.

Jan 1, 2007

Mr R. C. J. Goode (President) was in the Chair. There were also present one hundred and thirty-six Members, including Messrs R. J. Adamson, Dr J. M. Bereza, Messrs M. Barcza, H. Britten, H. E. Cross, J. K. E. Douglas, G. W. Holl, Dr J. P. Hugo, Messrs C. J. Irving, P. Lambooy, Prof J. de V. Lambrechts, Mr D. G. Maxwell, Dr J. T. McIntyre, Prof R. P. Plewman, Messrs J. F. Reid, V. C. Robinson, H. Simon and P. W. J. van Rensburg (Council Members), G. Abdinor, C. B. Anderson, H. F. Allan, E. L. Atkinson, V. C. Barnes, J. F. Bennet, W. W. Bath, R. E. Barnes, C. L. Berrange, J. P. Buds, Dr W. Bleloch, Dr L. A. Bushell, Messrs D. L. Carson, D. D. Cornier, R. S. Cooke, R. R. M. Cousens, J. P. Coetzee, W. L. Cousens, J. Daniel, R. Daniel, D. G. Davies, S. K. de Kok, V. S. Dillon, B. S. Dykhouse, Dr H. G. Denkhaus, Dr R. S. J. du Toit, Messrs J. I. L. Edwards, R. C. Espley-Jones, J. C. Ferguson, D. T. Fourie, A. Frost, W. R. Flook, Dr N. P. Finkelstein, Messrs D. F. H. Grave, J. M. Gosnell, E. K. Gibson, R. W. Grout, E. W. Gray, J. S. Hay, F. G. Hill, H. N. Hepker, J. P. Hoffman, C. G. Hodges, D. M. Jamieson, Dr D. G. Krige, Dr N. P. Lategan, Messrs J. E. Laschinger, J. Levin, C. P. Linsell, J. O. Kempe, F. Q. P. Leiding, A. I. Lee, D. G. Malan, W. Malan, H. W. McCulloch, R. D. R. Munro, C. S. Macphail, Dr T. F. Muller, Dr A. J. Nel, Messrs S. C. Newman, G. G. Nicolson, G. Y. Nisbet, J. A. Papenfus, E. Pavitt, W. H. Pittie, P. C. Pirow, P. G. D. Pretorius, N. F. Peverett, R. P. Plaskett, M. P. Pearse, W. Pilkington, T. K. Prentice, Dr R. E. Robinson, Messrs R. B. Richardson, R. St. J. Rowland, R. J. Rouillard, F. O. Read, W. T. Ruhmer, D. Savile Davis, E. F. Statham, K. Smith, H. Simon, G. B. Stern, C. D. Storrar, Dr N. B. Strydom, Messrs J. H. Talbot, A. H. Taute, J. H. Taylor, G. W. Thiel, K. A. Tweedie, W. E. Vance, Dr H. J. van Eck, Messrs L. W. P. v. d. Bosch, P. A. von Wielligh, N. B. Vinson, S. J. Venning, W. M. Walker, D. T. Watt, Dr H. J. R. Way, W. T. L. Wayman, R. G. Williams, L. G. S. Wright and C. F. Ziervogel. Thirty Associate Members, including Messrs E. Collier, G. Douglas, D. H. Gray, H. G. Gericke, R. Hemp, N. M. Hayne, A. Hazell, P. M. Johnston, D. E. Love, Miss V. E. Marting, Messrs R. G. Matthews, P. Malpage, D. Nicolle, R. Pendreigh, J. J. Rosslee, R. W. Shearer, R. F. Taylor, G. C. Thompson and D. A. Viljoen. Three graduates, Messrs G. S. Giles, J. P. Hatfield and J. A. Jones. Five Affiliates, Messrs A. C. Collie, E. Collier, A. B. Cook, W. Jacobs and G. M. Thain. Two Students, Messrs C. J. Bircher and R. P. Henrard.

By S. K. De Kok

Over a period of three years, since samples first became available, laboratory and pilot plant experiments have been conducted to develop a method of treatment to recover copper and zinc in saleable grades of concentrates from the Prieska complex sulphide orebody. These experiments have been based on adaptations of principles investigated by research workers and applied to similar ore types throughout the world. The differential flotation process finally worked out involves a comparatively coarse grind, flotation of the copper at near-neutral pH with the use of a zinc-cyande sphalerite depressant, followed by flotation of the reactivated sphalerite. This procedure has had such success that the construction of a full-scale plant is proceeding with confidence that the small-scale operations will be duplicated or improved upon. It is to be expected that the large plant will follow the pattern of almost every flotation plant that has been built in that modifications to the circuitry and reagent systems will be made as experience is gained.

By G. Song, X. Liu

The global coal industry has changed significantly in recent years. In this paper we analyse the coal production and consumption, imports and exports, and coal prices in China and other major coal-producing countries during the past four decades. The analysis shows that global coal production and consumption have declined over the last three years, in striking contrast to the continuous growth for most of the past 35 years. Australia, Indonesia, and Russia have become the world’s major coal providers, while China, India, and the USA, and Germany are the major coal consumers. The world’s, and China‘s, coal industry can be classified into four stages of development: the stable growth phase, stable phase, rapid growth phase, and high-quality phase. Coal prices rose in the world’s four major coal markets in 2016 after four consecutive years of falling prices. The elimination of overcapacity and production-optimizing operations in China could assist in achieving a demand and supply balance.

Aug 8, 2024

By S. Poirier, J. -M. Facteau

The gold mine sector is presently facing low gold prices as well as technological challenges. Its competitiveness and survival will depend on new mining methods and equipment to improve ore extraction. In 1999, Natural Resources Canada has invested new funds over a period of three years at CANMET’s Experimental Mine to establish the Narrow-Vein Mining Project. A team of engineers and researchers specialized in mining, mechanics and electronics engineering are working to meet the critical need of ore-extraction technology. CANMET’s programme in mechanization and automation for narrow-vein mining had, prior to 1999, realised several important achievements, many in co-operation with a consortium of mining companies(Soredem). The investment of new funds in this area will contribute to develop technologies to improve the productivity, as well as health and safety conditions of the narrow-vein mining industry. Several important impacts of this project will be monitored. In particular, a database of methods and equipment used in narrow-vein mining is being developed. A key thrust is to identify operators’ needs with respect to the development and automation of mining methods and equipment. Based on those needs, research and development projects will be created. The paper will present the objectives of the narrow-vein mining project and some of the results, including the web site developed to present the results of the project.

Sep 1, 2001

By A. J. S. Spearing, M. Sharifzadeh, K. V. Jessu

Empirical pillar design methods are commonly used in the mining industry. The parameters within which these methods are valid are frequently unknown to the user or ignored. In addition, empirical design may not consider essential parameters such as blasting effects, orebody dip and the presence of geological structures, which all adversely affect the stability of the pillars. This can result in potentially serious pillar design strength over-estimates. Although the commonly based tributary area method is generally conservative, as the spans are seldom that large relative to the depth, failing to consider other relevant parameters can result in errors. Problems associated with an under-designed pillar can range from a local pillar collapse to a catastrophic chain reaction collapse (or run). Over-designed pillars are generally safe but reduce the extraction of the orebody, thus adversely affecting the profitability of the mining operation. We used laboratory tests and numerical modelling to understand the effects of pillar orientation, blasting and the presence of discontinuities on pillar strength. Reduction factors were developed with these models to be implemented in conjunction with the existing empirical pillar design methods. For any pillar or mine design, once it is implemented, the actual performance of the system must be checked regularly by observation and monitoring and adjusted if needed. The pillar design approach outlined in this paper can better optimize the pillar mining method by considering other generally ignored but important parameters, thus improving safety, productivity, and economic aspects.

Oct 1, 2022

By H. A. D. Kirsten

The structural competence of mesh- and fibre-reinforced shotcrete was investigated in two series of tests on full-scale panels. It was found that uniformly distributed loading was marginally less demanding than point loading, mesh reinforcement was superior to fibre reinforcement, Dramix fibre and Melt Extract fibre were similar in reinforcing characteristics, and 30 mm to 35 mm was an optimum fibre length. Furthermore, the consistency of the fibre content could not be assured on practical mining sites, and an average fibre content of about 1,5 per cent was the maximum that could be obtained for fibre lengths not exceeding 35 mm. Also, owing to its greater flexibility, shotcrete reinforced with diamond mesh was preferable to fibre-reinforced shotcrete in mining excavations subject to squeezing conditions. In view of the difficulties associated with assuring the consistency of the fibre content in mining applications, it appears that the sophisticated attributes of fibre-reinforced shotcrete can be effectively exploited only in civil-engineering applications in which quality assurance is subject to explicit contractual control. Load-deflection curves, together with measurements of compressive stresses in the surfaces of some of the panels, enabled the ultimate flexural strength of reinforced shotcrete to be rigorously formulated, and rigorous design procedures for shotcrete subject to bending and direct thrust to be developed. The application of the procedures is demonstrated in a practical design case in which the moments and thrusts in a tunnel lining are determined in a numerical analysis of the interaction between the lining, the surrounding rock, and the rock-reinforcing system.

Jan 1, 1992

By I. H. Clark

A variety of backfills is presently being placed in different gold mines. The backfills are pumped as slurries to stopes where they are discharged into some form of retaining paddock. The effectiveness of fill as a support medium will depend on a number of factors. These can largely include (i) inherent properties of the material, e.g. particle size, shape, distribution and com- position, and (ii) conditions of placement. The terminology required for describing backfills is introduced, and the various laboratory-measured properties are presented for a variety of fills. Finally, the properties of the fills as they are placed underground are discussed.

Jan 1, 1988

By L. A. Cornish, I. A. Mwamba, R. A. Couperthwaite

"In previous work by the authors, it was established that additions of 0.2 at.% Ru to an Fe-40 at.% Al alloy improved the corrosion and oxidation resistance of the alloy. The alloy was produced by mechanical alloying and spark plasma sintering and the work showed that nonequilibrium processing was able to significantly refine the grain size of the material. The sintered material had a higher hardness than the as-cast material and the change in grain size did not significantly affect the oxidation and corrosion. In the present research, the mechanically alloyed powder was coated onto a mild steel substrate using cold-spray coating at a gas pressure of 10 bar and a temperature of 500°C. The coatings were found to be 5–10 um thick, although thicknesses of up to 30 um were observed. The coated materials were subjected to oxidation and corrosion tests to determine the effectiveness of the coating in increasing the oxidation and corrosion resistance of mild steel. This was done to determine the effectiveness of cold-spray coating as a technique to coat these mechanically alloyed powders. IntroductionPrevious work conducted by Mintek (Couperthwaite et al., 2013, 2015) investigated the effect of precious metal additions on the structure, oxidation and corrosion properties of an Fe-40 at.% Al (Fe- Al) alloy. Initial work determined that additions of more than 0.5 at.% precious metal did not improve the oxidation and corrosion properties of the materials and in some cases even decreased the resistance to corrosion. Further work identified Pt and Ru as beneficial additions to the FeAl alloy. Four alloys were then produced by mechanical alloying and sintering (FeAl–0.2 at.% Pd, FeAl–0.2 at.% Ru, FeAl–0.5 at.% Ag, FeAl–0.5 at.% Pt). These alloys were all successfully produced by melting and casting and mechanical alloying sintering and it was found that the nonequilibrium processing greatly decreased the grain size of the materials compared to the ascast materials. It was found that the additions of Ru and Pt were still the most beneficial to the oxidation and corrosion properties, with Ru being considered the most beneficial."

Jan 1, 2016

By D. J. Adams, R. G. Gürtunca

CONTRIBUTION BYJ.F. CURTlS The paper, which in an exemplary manner records the monitoring of backfill behaviour, falls short in the 'rock engineering' stated in the title. Just what the objective of the rock engineering was is obscure.

Jan 1, 1992

By A. R. Barnes, C. W. P. Finn

The prereduction and smelting characteristics of UG-2 ore were studied and compared with those of Winterveld chromite ore. The UG-2 ore proved more reducible, and substantial prereduction (over 70 per cent reduction after 30 minutes at 1250oC) was obtained. No difficulty was experienced in the production oh high-carbon ferrochromium alloy containing 48 to 50 per cent chromium. Calculations of the energy balance show that UG-2 chromite has lower total energy requirements (both on the basis of unit of ferrochromium produced and of total chromium content). More than 50 per cent of the energy required for reduction can be supplied outside the smelting furnace.

Jan 1, 1983

By M. Berjak, D. M. Hawlins, R. B. MacGillivray

SYNOPSIS The paper describes a method of producing iso line plans using a mathematical technique for interpolating between boreholes, and its computer application. The iso line plans are used for assessing the value parameters of an ore body. The computer programme also produces means and standard deviations to supplement these iso line plans. The mathematical techniques tested for the production of a satisfactory fit of the data were the polynomial, Fourier and moving average technique. The iso line plans are used for assessing the quality of the ore and other salient features such as depth to the floor of the ore body at different points, with a view to deciding how best the ore may be mined. The plans are plotted by the computer to any scale required. INTRODUCTION To assess the economic exploitability of an ore body many tedious and repetitive calculations must be carried out. Observations of borehole or development samples have to be processed yielding measures of ore reserve and quality in each sampled area, and also measures of the worth of the ore body as a whole and of variation in quality from section to section of the ore body. The observations made on the ore (which we shall term 'value parameters') may embrace a variety of characteristics of the ore. Obvious value parameters are those directly related to the economics of mining, viz. assay values, ore body thickness and depth below surface. Other value parameters however may be almost as important. In the case of coal for example a purchasing contract may specify limits of acceptability on other value parameters such as calorific value, ash content or the percentage of volatile matter. In this case, a detailed study of these value parameters will also be crucial. This detailed study must include an assessment, not only of the body as a whole, but also the regional variation in value of the parameter. An obvious and satisfactory way of displaying this variation is by drawing iso lines of constant value parameter on a map of the ore body and supplementing this with the means and standard deviations of the value parameters taken over all boreholes. Such plans, considered together, show up the zones of significance. The relatively stereotyped nature of the operations involved in this process makes it amenable to computer solution. In order to produce iso line plans on the computer we require some mathematical formula for producing a 'valuation surface'-a mathematical