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By J. L. van Niekerk, J. Gunaselvam

This study investigates the use of appropriate seating systems for the control of whole-body vibration exposure in vehicles used in the SA mining industry. Six suspension seats were tested with six test subjects to determine the most suitable seat for an articulated dump truck based on the EM1 requirement in ISO 7096 (2000) standards. Transmissibility functions were measured in the laboratory using the newly commissioned Dynamic Seat Testing Facility with two excitation levels of 1m/s2 and 2 m/s2 r.m.s. in the 0.5 - 30 Hz frequency range. SEAT values were calculated for two input spectrums, the EM1 input spectrum specified as in ISO 7096:2000 and measured road vibration data measured on a typical articulated dump truck. The averaged SEAT value calculations indicated that not one of the seats will qualify as an ISO 7096 (2000) suspension seat but that it is possible to select a seat that will significantly reduce the vibration the driver will be exposed to.

Jan 1, 2003

By Kurt R. P Petersen

This paper discusses the current approaches to modelling the DMS cyclone within the De Beers group. Current efforts are split into short term value-adding process understanding and longer term semi-fundamental analysis of separation mechanisms. To date, the basic applied approach has yielded significant value to the group, enabling operators to focus on simple diagnostic measures to control their process. The more involved modelling approach has given rise to a new understanding of the separation field, in particular that the high density gradients within a cyclone are highly localised, indicating that separation of medium to heavy density material takes place low in the cone. The model has proven to be conceptually robust, but still requires further development and validation to become a complete modelling and simulation tool for De Beers.

Jan 1, 2006

By K. Cybulski

In 2002 a coal dust explosions occurred in the Polish collieries “Jas-Mos” and “Rydultowy” in the Upper Silesia coal basin. In the “Jas-Mos” colliery the coal dust explosion was initiated in the face of gallery by explosives and causing ten death. The stone dust barrier extinguished the flame, stopped the explosion development and saved forty nine miners working in that area. In the “Rydultowy” colliery methane inflammation caused three deaths and seven serious burns and ignited the coal dust explosion. The coal dust explosion was stopped by stone dust barrier and did not cause any victims itself. This paper presents the investigation carried out by the Central Mining Institute Experimental Mine “Barbara” and shows that the stone dust barriers remain still a basic mean for suppression of coal dust explosion in mines. The investigation were aimed at determining the cause of explosion and circumstances that led to their propagation. The evaluation of the state of dust explosion hazard in the areas of accidents have been performed, and the range of flame estimated.

Jan 1, 2003

By V. Riihimäki, M. Luotamo

The Unit of Toxicological Risk Assessment of the Finnish Institute of Occupational Health (FIOH) is conducting a 'Health Risk Assessment for Metallic Chromium and Trivalent Chromium' under the sponsorship of the International Chromium Development Association (ICDA) and the International Stainless Steel Forum (ISSF). This risk assessment will be conducted in accordance with the current European Union legislation in force (Council Regulation 793/93/EEC, Commission Regulation 1488/94/EEC, Dir. 67/548/EEC), but also to meet the regulatory obligations as set out in the European Commission REACH legislation proposal (Consultation Document, the Registration, Evaluation, Authorisation and Restrictions of CHemicals). Further aims include outlining the criteria for the setting of occupational exposure limits for metallic chromium and trivalent chromium compounds. Human Health Risk Assessment according to the current legislation shall entail hazard identification of the toxic end points (acute toxicity, irritation/corrosivity, sensitisation, repeated dose toxicity, mutagenicity, carcinogenicity, reproductive toxicity) including, as appropriate, dose (concentration) - response assessment, and derivation of the N(L)OAELs (No (Lowest) Observed Adverse Effect Level) and/or DNELs (Derived No Effect Level). Exposure assessments for workers, consumers and humans exposed via the environment take into account all the known intended uses. Risk characterisation will compare the typical and/or reasonable worst case exposure estimates to the N(L)OAELs or DNELs to determine Margins of Safety (MOS) for all human populations by each exposure scenario and type of effect, followed by conclusions about the presence or absence of risk. Although all of the key elements of existing legislation remain in REACH, the principal change is that, the burden of proof will be transferred from the member state authorities to industry. The new proposed format of Chemical Safety Report (CSR) will include Risk Management Measures (RMM) as an essential part of the report in addition to the risk assessment. The RMM plays a role in the evaluation of further testing needs and advocating reasons for possible waiwer of requirements. The research programme started in March 2002 and will be completed within the time frame of two years.

Jan 1, 2004

By H. Ozturk

In this paper, the computer program ‘SHAFT’ developed for estimation of support requirements for circular mine shafts is introduced. Theory of support design is based on the analytical solutions of circular excavations under non-hydrostatic loading (Detourney and St. John1), and Lame’s thick-wall cylinder theory (Timoshenko6). For rock mass strength property determination Hoek-Brown failure criterion (Hoek et al.2) is used. Mainly two types of support, concrete and steel are taken into consideration as a support member. Program is written in Quick Basic language. Input parameters of the program are shaft radius, number of zones having the same properties along the shaft depth, and depth, unit weight, horizontal to vertical stress ratio, GSI, and uniaxial compressive strength of intact rock of each zone, and compressive strength and safety factor of support member. Output of the program is the graphical representation of shaft with the required support member and thickness throughout the depth of the shaft.

Jan 1, 2003

Dr R. E. Robinson, Pr. Eng., obtained a B.sc. (Chem. Eng.) cum laude from the University of the Witwatersrand in 1950 and a Ph.D. (Eng.) from the same University in 1953, where he was awarded the Haikes Memorial Medal for Industrial Chemistry. Professor G. G. Garrett was appointed Professor of Physical and :Fabrication Metallurgy in the Department of Metallurgy at the University of the Witwatersrand in June 1980, and in January 1984 he became Head of the Department. Mr P. A. van Wielligh, Pr. Eng., climbed the mining ladder in the hard way, starting as a Mine Surveyor in 1936 and working his way up as Chief Surveyor, Underground Manager, Mine Manager, and Consulting Engineer, to Executive Director, including the intermediate steps. Mr H. E. James, Pr. Eng., is a graduate in Chemical Engineering from the University of the Witwatersrand. Both his B.sc. degree (1961) and his M.sc. degree (1964) were obtained on bursaries, the former from Gold Fields of South Africa and the latter from the Atomic Energy Board. Mr G. Pienaar, Pr. Eng., obtained a B.Eng. (Met) in 1967 and an M.Eng. in 1973, both from the University of Pretoria. Dr A. K. Haines, Pr. Eng., obtained all his degrees from the University of Natal, finishing with a. Ph.D. in 1971. Mr B. C. Alberts, Pr. Eng., obtained his academic training at the University of Pretoria, where he was awarded B.sc. degrees in both agricultural engineering (1963) and mining engineering (1965). Mr H. C. van Zyl, Pr. Eng., holds B.sc. degrees in mining engineering (1968) and civil engineering (1972), both from the University of Pretoria.

Jan 1, 1984

By J. Lux, B. Clermont

Magotteaux, with the co-operation of Anglo Platinum, has erected a fully instrumented pilot plant at Frank concentrator, which is being used to study the influence of a variety of grinding parameters. This paper will discuss only the influence of mill speed and pulp density on secondary stage grinding. A Ø0.82 x1 m open circuit mill was used with reclaimed Merensky tailings as feed. The conclusions apply to this pilot plant but further investigation needs to be done to verify whether the same trends will be applicable to a large industrial-scale mill.

Jan 1, 2004

[Dr. N.A. Barcza (Chairman) Mr. R.J. Linnell (Vice Chairman) Mr. J. Basson Dr. L.A. Cramer Mr. W.A. Gericke Dr. N.C. Machingawuta Mr. C.S. Mahony Dr. L.R. Nelson Mr. D. St J. Slater Mr. B.J. van der Walt INFACON X TECHNICAL PROGRAMME COMMITTEE Dr. L.R. Nelson (Chairman) Mr. W.A. Gericke (Vice Chairman) Mr. W. Barrett Mr. T.R. Curr Dr. O.F.R.A. Damm Prof. R.H. Eric Mr A.M. Hearn Mr. A.R. Jamieson Dr. N.C. Machingawuta Mrs. L. Mthombeni Mr. F.X. Prins Mr. J. van Tonder ]

Jan 1, 2004

By S. G. Gendler

One of the ways of trauma and occupational diseases level reduction is noted to be the improvement of the labour protection measures planning. As an indicator for prospective trends determination in the labour protection planning improvement sphere economic risk has been proposed to be used. The trauma and occupational diseases analysis based on the correlative and regressive methods has been carried out for the “Vorgashorskaya” mine of Pechora coal basin. Trauma and occupational diseases occurrences frequency and economic losses value have been estimated. Trauma and occupational diseases economic risk distribution analysis has been presented in respect to the different subdivisions and occupational groups of “Vorgashorskaya” mine.

Jan 1, 2003

By I. R. Firth, D. L. Taylor

Metal mining operations, in particular gold mining operations, use intensive ore control procedures in order to manage the extraction of ore zones from benches containing both ore and waste material. Typical grade control procedures rely on blast hole samples to indicate ore grade. Statistical techniques and geological controls are then used to create two-dimensional polygons, which indicate zones of material designated as ore. These ore-polygons are calculated using pre-blast material locations and are generally not corrected for rock movement caused by blasting. This lack of correction appears to exacerbate the material mischaracterization problem of sending ore to the waste dump and/or waste to the mill. One Nevada gold mining company has estimated that this could be a $10 million per year problem for their operations. Using a simplified vector field algorithm, a method of taking point movement data and interpolating post-blast positions for all nodes in a polygon has been developed. Currently working in 2-dimentions (X-Y), this algorithm utilizes the movement vectors calculated from pre-and post-blast positions of targets placed in a blast, to generate a spatial transformation function for any point on the bench. This transformation is then applied to the nodes of the ore-polygons to produce modified dig lines ore polygons reflecting distortion and movement resulting from the blast. The method as implemented uses common mine planning routines and is performed using the Surpac software suite. The method may be adapted to use any pre-and post-blast point movement data available, and most mine planning suites include the simple interpolation algorithms used. Keywords: Blast movement; Ore control; Open pit blasting; Grade control

Jan 1, 2003

By J. A. Venter, M. K. G. Vermaak

There are practical indications that flotation recovery of palladium bismuth tellurides is poor. This work tested whether this can be caused by a lack of interaction of the collector with the telluride. Impedance measurements, voltammetry and Raman spectroscopy were performed to determine the interaction of dithiocarbonate collectors (KEX) with Pd-Bi-Te. Impedance measurements showed lower capacitance values in solutions containing KEX indicating the formation of a continuous surface layer. Anodic and cathodic polarization diagrams show the mixed potential tobe higher than the reversible potential of the xanthate-dixanthogen equilibrium reaction; hence the formation of dixanthogen on the surface is possible. Electrochemically controlled in situ Raman spectroscopy did indicate the presence of bulk diethyl dixanthogen on the surface. Raman spectroscopy has confirmed the co-presence of xanthate with dixanthogen, indicating that xanthate retains its molecular integrity when it adsorbs on the surface of the Pd-Bi-Te. As a result, the mineral surface is expected to be hydrophobic and a lack of collector interaction with the mineral is not the reason for low PGM recoveries experienced. Keywords: Raman spectroscopy; Pd-Bi-Te; ethyl xanthate; platinum flotation; Great Dyke; Pd-bearing bismutho-tellurides and moncheite.

Jan 1, 2004

By E. Yan

Electrostatic separation has been a mainstay of minerals sands flowsheets for over 50 years. Recent electrostatic developments have shown better conductor/non-conductor separation than technology previously available. Results to date show significantly increased separation efficiency over prior-art high-tension roll electrostatic separator (HTR). These improvements allow greater simplification of MSP circuits by minimizing re-circulating loads. The distinct features of the eForce include: 1) A provision that minimizes the affects of particle size to improve separator performance, 2) an enhancement of the design and arrangement of the static electrode providing a greater attraction force for separating fine conductive particles, and 3) inner roll and outer plate electrode configuration to improve separation efficiency and throughput capacity. Key Words: eForce, Electrostatic, Ion bombardment, HTR, Separation Efficiency, Electrostatic Classifier

Jan 1, 2003

By C. Ntsele

Stirred milling technologies have firmly established themselves in concentrator circuits as energy-efficient alternatives to tumbling ball mills. High and continued increases in electricity costs, coupled with the ever-increasing power consumption by primary grinding circuits due to declining head grades of ore-bodies, provides a compelling case for these technologies. Additionally, the ability to successfully deploy stirred milling in coarse grinding applications extends the range of use in concentrators, thus increasing the opportunity matrix for energy optimization in a flowsheet. This paper therefore details methodologies and strategies that can be applied to evaluate the optimum stirred milling solution for different concentrator applications. These methods and strategies will focus specifically on the two major stirred mill machine types; namely, gravity-induced (VERTIMILL? grinding mill and Nippion-Eirich tower mill) and fluidized (SMD, Isamill?, Knelson-Deswik mill, etc. ). Finally, case studies from circuits across industry and laboratory tests will be used to illustrate the energy benefit from the use of stirred mills.

Jan 1, 2012

By A. F. Collings

The processing of heavy mineral concentrates can be enhanced by the use of power ultrasound to clean their surfaces of oxidation products and fine coatings, mainly through the large, but very localized forces, produced by cavitation. Results are presented of the application of power ultrasound to remove coatings from the surfaces of mineral sand concentrates in order to improve the sharpness of their high-tension separation and, in some cases, the quality of the low iron components such as zircon. Improvements of 10–15% in recovery and up to 20% in grade compared to unsonicated material were achieved in a single stage laboratory high-tension separation. Cavitation also ensures that a fresh, clean surface is presented to leachants during the leaching of suspended solids. At the same time, the effect of cavitation and the shearing effect of the sound wave passing over the solids ensure that the saturated boundary layer is kept to a minimum if not completely removed. This application of power ultrasound helps to speed up leaching processes as applied to the removal of excess alumino-silicate contaminants in some ilmenite. Keywords: Ultrasound, power ultrasound, heavy minerals, processing.

Jan 1, 2003

By N. A. Barcza

This publication records the proceedings of the Tenth International Ferroalloys Congress, INFACON X, and the third INFACON hosted in South Africa. The Proceedings of the previous two South African congresses in 1974 and 1992 serve, as this volume does, as a valuable record of the papers presented at these important events. This publication comes at a time in South Africa?s democratic development where the theme ?Transformation Through Technology? is very appropriate. The ferroalloy industry has played an increasingly significant role in transformation and black economic empowerment in South Africa, particularly through the advancement and sharing of technology. INFACON X plays an important role in this process, and the stakeholders and organisers of this Congress are thankful for the opportunity to hold this event at this time of transformation in our country. The world of ferroalloys, as well as that of the steel and stainless steel industries, has continued to change rapidly. Recent innovations, better use of resources, increased awareness of environmental issues and ongoing efforts to improve occupational health and safety are among the topics addressed at INFACON X and in these Proceedings. The theme of ?Transformation Through Technology? has been chosen to reflect the regional and global developments in the ferroalloy industry, and the crucial role that technology plays. The Proceedings of INFACON X, the first Congress in Southern Africa of the new millenium, represent a milestone in the technical developments in this major global industry. It contains almost eighty papers in twenty Sessions, from authors in twenty countries, covering raw materials, reductants, energy, electrodes, refractories, furnace design, post taphole services, modelling, simulation, control, sensors, fundamental issues and the applications of ferroalloys as related topics. The major ferroalloys, namely ferrochromium and ferromanganese, are covered extensively in many interesting papers. This comes as no surprise, since South Africa is the leading producer of ferrochromium and also plays a major role in the supply of manganese ore and alloys. Papers on ferronickel, silicon and ferrosilicon ensure that all the large-volume ferroalloys are addressed. These Proceedings of refereed papers of high quality will serve the ferroalloy industry for many years to come, as has been the case with previous INFACON events. For the first time in the history of INFACON, the Proceedings will be available both in bound and in a searchable electronic CD-ROM format. We appreciate the time and effort that the authors and referees have devoted to making this publication a really valuable document. Their contributions are recorded for posterity and reflect the advancements they and their colleagues have made to benefit the ferroalloy industry. Without these ongoing improvements, the industry would stagnate and not fulfil its role in the advancement of mankind. All papers included in these Proceedings were peer-reviewed by at least two referees. About 130 referees were sourced internationally to fulfill this function, and their valuable technical and editing inputs are gratefully acknowledged. Finally, I would like to thank the Technical Programme and Publication committees, led by Dr. Lloyd Nelson and Dr. Noël Machingawuta respectively. Without the tireless efforts of these individuals and their Committee members, the technical programme and these Proceedings would not have been the success they certainly are.

Jan 1, 2004

By B. K. Loveday

The South African Institute of Mining and Metallurgy hosted a School on 'The Practical Design of Comminution Processes' at Megawatt Park (near Johannesburg) on 14th to 16th May, 1991 Derek Barratt, a Senior Consultant of Wright Engineers, Canada, and the main speaker, provided a good insight into how Wright Engineers design milling circuits, particularly large semi-autogenous mills. He was ably assisted by Jens Lichterof Allis Mineral Systems, who described some interesting examples of pilot-plant testwork and summarized South African milling practice. Mike Moys of the Witwatersrand University spoke on the influence of pulp viscosity on mill performance, and Johan Engelbrecht and Jeremy Bosman of Multotech

Jan 1, 1991

By I. Gil, J. -C. Roegiers

Abstract Hydraulic fracturing is a technology that has been utilized for more than 50 years in the oil industry. It was originally used for stimulating hard, brittle formations which typically exhibit low permeabilities and roughly linear elastic behavior. Nonetheless, an increasingly important segment of the industry is currently stimulating very soft and poorly consolidated formations; where the assumptions of ideal elasticity and relatively small fluid leakoff fail to hold (e.g. Gulf of Mexico, West Africa, Alaska, East China). In these rocks, hydraulic fracturing stimulation has been used for several years to control and solve critical production problems such as sanding and formation damage (caused during completion and drilling operations). Although successful1, the application of this method has not been accompanied by robust fracturing modeling techniques. In addition, long term production increases were often not materialized. In other words, engineers have been able, via trial-and-error, to avoid major ‘operational’ problems but with no optimization of such treatments. Thus, most hydraulic fracturing projects carried out in poorly consolidated rocks render unexpected results. A recent worldwide survey on net pressures by the Delft Fracturing Consortium (Papanastasiou, 1997) indicated that net pressures encountered in the field are 50% to 100% higher than the net pressures predicted by conventional fracturing simulators. The difference is yet higher for the case of poorly consolidated formations (Pak, 1997). The theory for the construction of a fully coupled elastoplastic three-dimensional hydrofrac simulator, specifically conceived for unconsolidated rocks, is presented in this paper. This novel model calculates the dimensions and changes in shape of the fracture(s) being created during hydraulic fracturing operations. No assumptions are made regarding either shape or geometry of the crack(s). Three main failure criteria are used simultaneously in this model: tensile and shear stresses, and volumetric strain. Incremental forms of the governing equations of equilibrium and fluid flow are presented. The scheme chosen for solving this problem is the finite elements method, which allows both equations to be solved simultaneously at any instant in time. Résumé La fracturation hydraulique est une technologie qu’a été utilisé pour plus que 50 ans dans l'industrie pétrolière. Elle a été utilisée au début pour stimuler les formations dure et fragile que typiquement ont des perméabilités basses et un comportement élastique à peu près linéaire. Néanmoins, un segment plus important de l'industrie stimule actuellement des formations mal consolidées; où les suppositions d'élasticité idéale et de relativement petite fuite de fluide ne se tiennent pas raison (par exemple le Golfe de Mexique, l'Afrique d'ouest, Alaska, la Chine de l'est). Dans ces roches, la stimulation avec fracturation hydraulique a été utilisée pour plusieurs années pour contrôler et résoudre les problèmes critiques de production comme les dommages de formation et d’ensablement (causé pendant les opérations de l'accomplissement et forage). Bien que prospère, l'application de cette méthode n'a pas été accompagnée de techniques robustes pour le modelage de fractures. En outre, les augmentations à long terme de production n'ont pas été souvent concrétisées. En d'autre termes, les ingénieurs ont pu, via le procès et l’erreur, éviter les majeur problèmes ‘opérationnel’ mais avec aucune optimisation de tels traitements. Ainsi, la plupart des projets de fracturation hydraulique ont été exécuté dans des roches mal consolidées et ont rendu résultat totalement inattendu. Une récente étude mondiale sur les pressions nettes par le Consortium Delft pour Fracturer (Papanastasiou, 1997) a indiqué que les pressions nettes qu’ont été rencontré dans le champ sont environ 50% à 100% plus hautes que les pressions nettes prédites par les simulateurs fracturant conventionnels. La différence est pourtant plus importante pour le cas de formations mal consolidées (Pak, 1997). La théorie de construction d'un simulateur elastoplastic d’hydrofrac à trois dimensions entièrement couplé, en particulier conçu pour les roches non consolidés, est présentée dans ce papier. Ce nouveau modèle calcule les dimensions et les changements dans la forme de(s) fracture(s) étant créé pendant les opérations de fracturation hydraulique. Aucune supposition n’a été faites en ce que concernant la forme ou la géométrie

Jan 1, 2003

By I. E. Teymenson, L. A. Bakhvalov

Irrational usage of mineral commodities leads to depletion of natural resources and various ecological violations in natural environment. Fulfilment of a number of measures and strategic decisions by given problems requires a correct forecast of trends of social-economic systems. For solving the task of long-term forecasting special procedures, considering Kondratyev’s big cycles of world conjuncture, have been embedded into algorithms of unknown parameters identification and recovering of factors of different countries mineral resources production and consumption models. In the paper the classification of long cycles types, existing forecasting algorithms on the basis of Kondratyev’s ‘long waves’ or ‘K-waves’ and the modified algorithm, developed by us, which allows to reduce time and financial expenses and to improve the forecast quality, are presented. Furthermore, the article includes several forecasts of mining branch corrected models factors, received by us, permitting complex prognosis of economic and social development of different scale and control level systems. In the paper workability of proposed forecasting algorithms on the base of ‘K-waves’ and adequacy of created models to researched processes are proved.

Jan 1, 2003

By GA Harrison

The introduction of Extra Low Profile (XLP) mechanised equipment within Anglo Platinum is aligned with the overall New Mining Technologies strategy to focus on continuing modernization of our mining operations to achieve injury free sustainable production and cost effective mining technologies. The method allows for the introduction of a suite of XLP and Low Profile (LP) equipment in a narrow reef (1,2m) mining environment. For the first time it is now possible to achieve total trackless mechanisation at these stoping widths and XLP Breast mining has the potential to add more value when benchmarked with conventional mining and other mechanised methods. Various types of XLP equipment were tested at different sites within Anglo Platinum and this paper describes the XLP equipment evolution to-date. It concludes with recommendations on our future strategy regarding implementation and roll out of the XLP technology within Anglo Platinum.

Jan 1, 2008

By R. Zivojinovic, S. Vujic

The structural age of the capital mining machinery, representing a part of the system of the Electric Power Industry of Serbia, has been dictated by the initiation and development of open pit coal mines. For example, the oldest bucket wheel excavators were installed some thirty-four years ago, and the average life of the relevant machinery exceeds twenty-two years. Operation of both capital equipment and machinery has direct effects on economic and business activities of open pit mines, and consequently forced us to make a decision and study thoroughly the problem of establishing the optimum exploitation life of capital mining equipment at the open pit coal mines of the Electric Power Industry of Serbia. The aim of this paper is to define and discuss the relative problems as well as to find out the possible solutions and establish the methodology for estimating the optimum exploitation life of machinery. The study was successfully carried out by a team of scientists engaged from and coordinated by the Department of Computer Science of the Faculty of Mining and Geology, University of Belgrade. This paper presents the key observations covering the subject problem. Keywords: Mining, Opencast exploitation, Coal, Optimization, Exploitation life, Capital machinery, Electric power industry, Dynamic programming.

Jan 1, 2003