Search Documents

By X. B. Zhao, J. G. Cai

The purpose of this paper is to incorporate the dynamic BB model of rock fracture normal behaviour into Universal Distinct Element Code (UDEC), and to conduct UDEC modelling to predict stress wave propagation across rock fractures. With the incorporation of new dynamic model of fractures, the UDEC is improved in the capability of modelling wave propagation across fractures. In this study, the case of normally incident P-wave transmission across a fracture is modelled, and the effect of dynamic normal behaviour of fracture is concentrated on. Wave transmission coefficient for wave transmission across the fracture with the dynamic BB model is obtained for various combinations of fracture dynamic parameters, as well as different wave amplitudes and frequencies.

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 P J. Terbrugge, O K. H Steffen

Open pit slope design has conventionally been effected as a bottom up function utilising available geotechnical information. This results in a decision criterion based on Probability of Failure and Factor of Safety with a risk assessment being carried out on the proposed design slopes. The design approach recommended reverses the process using fault event tree decision methodology. The consequences of this approach are that acceptable risk criteria have to be determined by mine owners. Slopes are then designed by the technical staff to achieve these corporate goals. Benefits that arise from the process are that the owners take a proactive decision on the risk benefit relationship allowing the technical staff to optimise the geotechnical exploration programme and design.

Jan 1, 2006

By G. A. Brown

Major mining projects are developed with the assistance of lending institutions who provide hundreds of millions of dollars in funding over several years, and of course expect those funds to be returned with interest. Two Australian banks have adopted the Equator Principles, an emerging financial industry benchmark for assessing and managing environmental and social risk in project financing. Project financiers have encountered environmental and social issues that are both complex and challenging, particularly with respect to projects in the emerging markets of Asia-Pacific and elsewhere. There are many recent and historical examples of failures by resource companies to effectively manage their environmental, social, safety and security risks, some of which have caused the project to fail completely, and some of which have caused the temporary cessation of production. These events put the financial institutions' funds at risk through inadequate management capacity and non-compliance adversely affecting the ability of the borrowers to repay the loans. They can also reflect adversely on the reputation of the lending institutions. In assessing these risks, lenders are increasingly looking at the track record of the borrower in its country of origin and in other countries where it operates. Lenders are wary of companies that have one standard for operations in a developed country, where the regulatory environment may tightly control what they do, and another standard for operations in countries where the regulatory regime is perhaps less stringent. Lenders may require environmental and social reviews or audits to be conducted on their behalf by competent third parties prior to a loan being approved, and annually over the life of the relationship. The mining industry's concept of the unwritten `social licence to operate' is highly relevant in relation to the delivery of community benefits that are sustainable post-mine closure. This paper provides examples of recent practices that support financial viability and sustainable development, as well as examples of some failures that have put lenders at risk.

Jan 1, 2007

OPENING SESSION Session Chairpersons: Dr. P.P. Jourdan & Dr. L.A. Cramer Transformation to Tackle the Challenges Facing the Ferro Alloy Industry in the Next Decade R.J. Linnell Electricity Supply in SA ? A 10-Year View T.S. Gcabashe IDC as the Catalyst for Growth in the South African Ferroalloys Industry J. Kriek Development in the Global Stainless Steel Industry V. Muñoz CLOSING SESSION Session Chairpersons: Mr. R.J. Linnell & Dr. O.F.R.A. Damm The Health of Vanadium T.E. Jones Steel Raw Materials - Nickel, Chrome, Stainless Steel Scrap and Manganese H.H. Pariser

Jan 1, 2004

By J Steyn

Block Cave mining is one method used to extract ore from underground diamond mines as well as other massive orebodies such as copper. This necessitates the excavation of many kilometers of tunnel within the ore body. The integrity of these excavations needs to be maintained over a number of years. Most Kimberlites and weak orebodies are extremely susceptible to degradation when exposed to moisture and the atmosphere. It is therefore essential that some form of weathering protection is applied as soon as possible after exposure. Conventional methods of weathering protection such as shotcrete do not easily fit in with the production schedule, hence the need for a more efficient system that could be applied immediately after exposure and serve as a temporary support or even as a permanent support medium. The main advantages of thin sprayed liners (TSL) compared to shotcrete are the ease of application, speed of application, early strength, much reduced transportation of material, less labour intensive and cost effectiveness. Several Thin Sprayed Liners suitable for various mining environments and geotechnical conditions are available and could be well suited as additional support the undercut level development in a block cave where this may be required. TSL offer a cost effective support solution as an alternative to shotcrete in areas where the building of a support structure is not a requirement.

Jan 1, 2008

By S. Sakurai, N. Shimizu

The stability of slopes is a crucial problem not only in open pit mines, but also in civil engineering situations. The deformational behaviour of slopes is in general monitored during/after the excavation by carrying out field measurements where displacement measurements are commonly adopted. In monitoring the slope stability it should be emphasized that the measurement results must be properly interpreted so as to assess whether the slopes are stable or become unstable in the future. In order to interpret the data, back analysis is extremely useful. In this paper a slope stability monitoring system is described. It consists of displacement measurements by GPS, and a back analysis of measured data. The use of GPS has a great advantage, because of the fact that continuous displacement measurements with high accuracy for a large extent of concerned area can be easily achieved. On the other hand, the back analysis can reveal the mechanical characteristics of the ground, which make it possible to assess the stability of slopes quantitatively.

Jan 1, 2006

By A Weber, L MacNamara, H Schreiber

Design and development of the world?s largest flotation cell was completed in 2002. This was the first 257 m3 flotation cell installed in the mineral industry and represents a major development in the design of larger flotation cells. This cell has a 50% increase in volume over the widely installed 160 m3 WEMCO® Smartcell? flotation machine. In the next few years it is anticipated that 257 m3 flotation cells will be incorporated into rougher-scavenger flotation circuits in many more world class copper sulphide concentrators. The prototype 257 m3 cell, No.250 Smartcell? flotation machine was installed at Minera Los Pelambres in the front of Row 1 in the existing rougher flotation circuit. This cell is followed by nine No. 130 Smartcell? flotation cells. After the successful development phase, this unit has been incorporated as part of a row of No. 250 Smartcell? flotation machines at Minera Los Pelambres. A key to the successful development of the equipment has been the emphasis placed on fundamental hydrodynamic scale-up criteria. Hydrodynamic factors include superficial gas velocity, water (pulp) circulation through the draft tube, and pulp mixing (distribution) characteristics. This paper will review the scale-up criteria of the No. 250 flotation cell, and present a case study of the in-plant equipment testing. The case study will document the metallurgical and hydrodynamic performance of the machine. It will also illustrate the economic benefits derived by incorporating larger flotation cells in a modern copper sulphide concentrator.

Jan 1, 2007

By L. K. Smith

The position of Australia as a continuing long-term supplier of mineral sands, and their upgraded products, has been reinforced with the discovery of the extensive mineral reserves in the Murray Basin, an area covering parts of South Australia, New South Wales and Victoria. A major impurity in the Murray Basin is chromium, mainly present in ilmenite concentrates as individual chrome spinel grains. Magnetizing roast treatments are being evaluated as a means of removing the chrome spinel impurity from the ilmenite and as a result of the roast and magnetic separation treatments, the chrome spinels can be expected to be concentrated in the non-magnetic reject fractions. It is from these fractions that attempts were made in this study to recover a chromium-rich product by magnetic fractionation and by application of flotation. The high gauss non-magnetic rejects from the roasting of a primary and a secondary ilmenite fraction were magnetically fractionated to obtain a product with 40.5 and 28.7 per cent Cr2O3,respectively. From the high gauss non-magnetic reject from the roasting of a primary ilmenite, flotation produced a chromium-rich product assaying 29.5 wt per cent Cr2O3at 69.0 per cent recovery. In another test a magnetic fraction assaying 32.9 wt per cent Cr2O3was floated to yield a chromium-rich product with 39.7 wt per cent Cr2O3at 96.4 per cent recovery. X-ray diffraction patterns of all the products indicated that the spinel concentrated was a ferroan magnesiochromite with rutile, ilmenite and hematite as impurities. Since all products were from a single pass, further processing can be expected to remove the impurity minerals and yield higher grade products. The material produced from the Murray Basin ilmenites in this study had similar compositions to commercial chromite ores, except for titania levels that were much higher. The high titania levels were due to residual rutile in the products, but it is expected that this can be removed with further processing. The mineral sand deposits in the Murray Basin are scattered over a wide area and the amount of chromite that may be produced from each of these deposits is unlikely to be sufficient to support an export market. Consequently, any chromite produced in the Murray Basin will most likely need to be processed locally to value added products for a niche market such as chemicals production. Keywords: Murray Basin, ilmenite, chrome spinel, roasting, magnetic separation, chromite ore

Jan 1, 2003

By P. S. Pashkovsky, S. N. Smolanov

The essence of the method consists in creation of drop of opposite sign at the isolating stoppings, by which air losses through the accident district change direction of their motion. The period of reversal is selected in that way so that air may not find itself in the zone of burning. The method of fighting the fire considered was repeatedly used in the coal mines of the Ukraine. The theoretical basis of efficiency and two examples of use of this method by fighting the underground fires are adduced in the paper.

Jan 1, 2003

By P. Otto, G. Borm, Th. Dickmann, F. Amberg, R. Giese

Based on many years experience, the well proven Swiss Tunnel Seismic Prediction System TSP has been substantially augmented for online geological prognosis in underground construction. In its latest version, the Integrated Seismic Imaging System ISIS provides high resolution seismic images of the rock mass around a tunnel face via an array of standard anchor rods. These rods contain 3D-geophones at their tips and can be readily installed during excavation work. A further innovative component of the system is the newly developed high-power repetitive source for application in hard rock: a pneumatic hammer with laser triggering to be mounted on construction machinery. A user-friendly software package permits online data acquisition and processing, 3D-visualization, and a first geological interpretation. Tomographic images of compressional and shear wave velocity fields at fault zones in metamorphic rock of the Gotthard Base Tunnel in the Central Alps are presented. Das langjährig bewährte Schweizer Tunnelseismische Vorauserkundungssystem TSP wurde inzwischen wesentlich weiterentwickelt. In seiner neuen Version, dem Integrierten Seismischen Imaging System ISIS, ermöglicht es hochauflösende seismische Abbildungen des Gebirges im Vorfeld und Umfeld einer Tunnelauffahrung mit Hilfe einer Anordnung von Felsankern, die an ihren Spitzen 3-Komponenten-Geophone enthalten. Eine weitere Neuerung von ISIS ist die pneumatische Hochleistungs-Impulsquelle mit Laser-Triggering. Eine benutzerfreundliche, interaktive Software ermöglicht die online Datenerfassung und -auswertung, 3D-Visualisierung und eine erste geologische Interpretation. Tomografische Abbildungen von Kompressions- und Scherwellengeschwindigkeitsfeldern an Störungszonen in metamorphem Gestein des Gotthard-Basistunnels werden gezeigt. Basé sur de nombreuses années d’expérience, le système suisse, bien établit, de reconnaissance sismique à l’avancement des tunnels (système TSP), a été sensiblement amélioré pour obtenir une prévision géologique en temps réel durant l’avancement de travaux souterrains. Sa dernière version, le Système Intégré d’Imagerie Sismique (ISIS), fournit des images sismiques haute-résolution du massif rocheux à l’avant d’un tunnel grâce à un réseau de tiges d’ancrage standard. Ces tiges, équipées à leur extrémité de géophones 3 composantes, s’installent très aisément durant les travaux d’excavation habituels. Le élément d’innovation récente concern le nouvelle source très répétitive et de forte puissance pour les applications aux roches dures: un marteau pneumatique déclenché par un système à laser. Un ensemble de programmes informatiques convivial permet l’acquisition et le traitement en temps réel des signaux et produit une vue 3D ainsi qu’une première interprétation géologique. Nous présenterons des images de réflexion d’ondes de compression et de cisaillement ainsi que des inversions tomographiques de zones de faille dans des terrains métamorphiques obtenues à l’occasion du creusement du tunnel de base du Gothard, dans les alpes centrales.

Jan 1, 2003

Historically, mine ventilation practices as it was referred to then and which was enforced by legislation of those days, focused primarily on the conditions in the working place and little attention given to actual exposures of workers to contaminants in the working environments. With the advent of the Leon Commission of Inquiry into Safety and Health in the South African Mining industry in 1994, findings in the report indicated that more attention should be given to occupational health of workers. The upshot of this report resulted in the promulgation of the new Mine Health and Safety Act (MHSA) with certain sections of it devoted to all the aspects of occupational medicine and occupational hygiene. This paper describes the present situation with regards to statistics on occupational hygiene performance and compensation paid out to persons who have contracted occupational diseases, as well as the way forward in terms of legislation implemented in September 2002 on the chronic and acute issues affecting the mining industry in SA.

Jan 1, 2003

By R. Kus´

The paper presents the comments on the advantages of implementing an integrated system of managing mining exploitation in hard coal mines, as well as the comprehensive integration of information on the process of deposit exploitation with economic data, so as to achieve an optimum technical and economic effects. The principles of constructing the production management system have been presented, thanks to which the management boards are provided with reliable technical and economic information on a mining company via information technology. The strategic direction of a company’s operation may currently be verified according to the external conditions that change over time (the information on the deposit, force majeure events, changing expectations of customers, etc.).

Jan 1, 2003

By F. T. Cawood

This paper focuses on the role of the coal mine surveyor at the start of the 21st century. It demonstrates that surveyors must look beyond their legal appointment and pursue opportunities to add value at an operational or corporate level of the company. It also exposes the shortfall of statutory appointments in defining the surveyor?s role in terms of key business drivers of the company. One such an opportunity is the potential role of the surveyor in mineral accounting and quality assurance to meet mine requirements, market specifications and standards pertaining to corporate governance and reporting. Finally, some thoughts are expressed on what can be done to elevate current practice to best practice and how to achieve this goal

Jan 1, 2007

The heap leaching of base metal ores can be applied within a number of different scenarios, each requiring its own set of parameters to be determined during the metallurgical testwork programme. The occurrence of acid-gangue reactions and its concomitant precipitation reactions is a factor common to all cases, and requires that the optimal irrigation acid strength be found that optimises the combination of extraction kinetics, acid consumption and possible premature blinding of the heap due to precipitation reactions. For the heap bioleaching of base metal sulphide ores the oxygen requirement needs to be determined for the design of the aeration system, and the operating conditions employed need to also facilitate bacterial growth over and above the acid strength optimisation mentioned above. For the heap bioleaching of chalcopyrite, the need to preserve heat in the heap becomes yet a further parameter of critical importance. For the heap leaching of uranium ore a choice is required between either chemical or bacterial oxidation, based on economic and processing factors. Frequently the operating parameters need to be determined for a circuit in which heap leaching is combined with tank leaching and/or pressure leaching. The processing implications and metallurgical testwork approach for each case is discussed.

Jan 1, 2007

Mr Colin M. Spence took office as President of The Federation of Societies of Professional Engineers on 1st July, 1984. Colin Maynard Spence was born in November 1921, and was educated at the Durban Preparatory and High Schools, in both of which he was a Dux Scholar. He graduated from the University of Natal in 1942 with a B.Sc. degree in civil engineering. In 1958 he received a Diploma in Town Planning from the same university. Cessation of Membership In accordance with Clauses 7.6.1 and 12.1 of the Institute's Constitution, Rules and Policy, the following members have been struck off the Membership list.

Jan 1, 1984

By U. Kumar

Product designed characteristics like reliability and maintainability affect maintenance cost, service performance, and therefore product support strategy must be defined during design stage in terms of these two dimensions. Furthermore product support and service delivery strategy has considerable influence on the total life cycle cost and the economic viability of industrial systems/products. he paper presents a concept for the development of service delivery strategy for industrial products with a special reference to mining systems. In this paper we emphasize that the strategy for product support should not be centred only on ‘product’ but it should also take into account the service delivery capability of the manufacturers/suppliers and users service organization, users competence and capability, product use location, logistics and infrastructures, etc., to arrive at the best performance and economic results. Such strategy should invariably include services supporting the client apart from considering services supporting the product. The discussion in the paper is based on the experiences from the manufacturing industry engaged in manufacturing of mining systems and the observed trends in technology and management of operation and maintenance of mining systems. Keywords: Maintenance and product support, Service supporting client, Service delivery strategy, Products reliability and maintainability, Product use location, Operating environment, etc.

Jan 1, 2003

By J. D. Steenkamp

In a paper presented at the Heavy Minerals Conference 2001 a laboratory scale investigation on the beneficiation of an ilmenite containing waste stream by magnetizing roasting was reported1.This waste stream contained a high concentration of ilmenite, which was contaminated by chromite and other gangue minerals. Interpretation of the results of the investigation was based on the assumption that during magnetizing roasting of an ilmenite concentrate, under the oxidizing conditions, the magnetic properties of the chromite would remain constant. In this article thefollowing hypothesis was tested: The magnetic susceptibility of chromite would remain constant during magnetizing roasting of an ilmenite concentrate under the oxidizing conditions reported by Gouws and Van Dyk1. The results of this study indicated that the hypothesis is not true. The increase in the magnetic susceptibility is not significant though and it is expected that it will not influence the final ilmenite quality to a large extent. Based on the assumptions that the bulk magnetic susceptibility of the waste stream samples represents that of the ilmenite in the waste stream, and the bulk magnetic susceptibility of UG1 chromite that of the of chromite in the waste stream, the results also served to confirm that the waste stream with a high chromite content should be roasted under oxidizing conditions, in a reactor with a well-defined retention time distribution (i.e. a fluidized bed reactor), at a roasting temperature of 750°C (rather than the higher temperature ranges of 800°C and 850°C).

Jan 1, 2003

By John M. L Lewis, Antoine F. Mulaba-Bafubiandi

In the irradiation of ore particles by microwave energy preferential absorption of this energy occurs in minerals having specific dielectric properties (Bradshaw, 1999). This leads to a selective heating of the various components of within the ore particle matrix. The result is a differential thermal expansion of such components and the resulting induced stresses become ideally concentrated at mineral grain boundaries (Kingman et al., 2000). Dependent upon the relative composition of absorbent, opaque and reflective components this may lead to enhancement of the inter-granular fracture of the ore particles in the initial comminution process (Fandrich et al., 1997). The potential is thus a greater proportion of free mineral grain within the fractured ore particle that may lead to improvement in subsequent mineral separation processes. As the composition of the ore dictates the result of such a treatment (Kingman et al., 2000) it is essential to evaluate the response of each ore sample on an individual basis. This paper reports on results obtained from two ore samples: the one being the zinc ore from the Black Mountain mine (South Africa) and the other a pre-concentrated sample of handpicked cobalt?copper mixed oxide ore from the Gecamines (DRC). The equipment and methods used to simulate the comminution of the samples and evaluate the level of the value liberation will be described along with the results obtained. Using King (1975), Kanellopoulous and Ball (1975), and Gungor and Atalay (1998), a comparison between the behaviour upon microwave irradiation of sulphide and mixed oxide ores leads to conclude that while the technique (i.e. microwave irradiation) is appropriate to the zinc sulphide ore, it does not seem to lead to exceptional results for the oxide.

Jan 1, 2005

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