Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology

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  • ISSN
    1474-9009

Publications in this journal

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    ABSTRACT: This paper reports the findings from a benchmark study testing several numerical methods, with a focus on the influence of undercut depth on block caving-induced surface deformation. A comparison is drawn between continuum v. discontinuum treatments of the modelled geology. Results were evaluated with respect to different simulated levels of ground disturbance, from complete collapse to small-strain subsidence. The results show that for a given extraction volume, the extent of ground collapse at surface decreases as undercut depth increases. The presence of sub-vertical faults was seen to limit the extent of the modelled caving zones. In contrast, the extent of small-strain surface subsidence was seen to increase with increasing undercut depth. The faults in this case did not have the same limiting effect. Overall, the findings emphasise the importance of balancing model simplification against the need to incorporate more complex and computationally demanding representations of the rock mass structure.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 09/2014; 123(3):128-139.
  • Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 06/2014;
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    ABSTRACT: In order to develop downstream processing routines for iron ore and to understand the behaviour of the ore during processing, extensive mineralogical characterisation is required. Microscopic analysis of polished sections is effective to determine mineral associations, mineral liberation and grain size distribution. There are two main imaging techniques used for the characterisation of iron ore, i.e. optical image analysis (OIA) and scanning electron microscopy (SEM). In this article, a QEMSCAN system is used as an example of SEM methodology and results obtained from it are compared against results obtained by the CSIRO Recognition3/Mineral3 OIA system. Both OIA and SEM systems have advantages and drawbacks. Even though the latest SEM systems can distinguish between major iron oxides and oxyhydroxides, it is still problematic for SEM systems to distinguish between iron oreminerals very close in oxygen content, e.g. hematite and hydrohematite, or between different types of goethite. Scanning electron microscopy systems also can misidentify minerals with close chemical composition, i.e. hematite as magnetite and vitreous goethite as hematite. In OIA, iron minerals with slight differences in their oxidation or hydration state are more easily and directly recognisable by correlation with their reflectivity. In bothmethods, the presence of microporosity can result in some misidentification, but in SEM methods misidentifications due to microporosity can be critical. Low resolution during QEMSCAN analysis can significantly affect the textural classification of particle sections. The main conclusion of this study is that, for low iron content ores or tailings, SEM systems can provide much more detailed information on the gangue minerals than OIA. However, for routine characterisation of iron ores with high iron content and containing a variety of iron oxides and oxyhydroxides, OIA is a faster, more cost effective and more reliable method of iron ore characterisation. A combined approach using both techniques will provide the most detailed understanding of iron ore samples being characterised.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 03/2014; 122(4):217-229.
  • Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 03/2014; 123(1):56-57.
  • Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 06/2012; 121(2):97-108.
  • Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 09/2011; 120(3):158-169.
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    ABSTRACT: At Cliffs Natural Resources Ltd (CNR) crushing and shipping sample stations, precisions are estimated for the sampling, preparation and measurement stages of iron ore sampling in accordance with ISO 3085 (2002). In this standard, gross duplicate samples are prepared at each of the three stages, yielding eight measurement assays. Appropriate calculations of the differences between assay pairs are then made to estimate precision of each stage of sampling. The international standard for checking precision in iron ore sampling, ISO 3085 (2002), prescribes a method for identifying outliers that is ambiguous and possibly inappropriate. The procedure also makes an unnecessary implicit assumption, that the differences between assay pairs are normally distributed. The Anderson?Darling statistic is used to demonstrate that in some cases the assay pair differences have distributions significantly different from normal. When applied at CNR as specified, the standard leads to precision estimates well below the expected values, thus overestimating the sampling method’s capability and limiting the opportunity for real process improvement. This paper suggests an improved method of estimating sampling, preparation and measurement precision. A bootstrap procedure is used to estimate confidence limits for the calculated precision estimates. The proposed method would be suitable for testing blast hole precision. The discussion is supported by extensive simulation modelling of realistic data.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 05/2011; 120(2):65-73.
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    ABSTRACT: The Macquarie dictionary defines ‘compliance’ as ‘1. An act of conforming; acquiescing, or yielding. 2. base subservience.’. Does environmental compliance mean yielding to environmental forces, or does it mean being subservient to a human perception of the environment? How ‘environmental compliance’ may be defined by the various stakeholders in the mining industry, companies, governments and communities is considered in the light of their possible objectives in requiring ‘environmental compliance’. Examples of potentially conflicting environmental requirements in waste management are considered, particularly operational requirements such as minimal dust generation versus completion environmental compliance requirements of establishing a self-sustaining ecosystem or geomorphologically stable landform. Mechanisms available to establish standards for determining if environmental compliance has been attained are described. These include guidelines (company and government), which can range from detailed (tailings construction) to broad and general (closure strategies); codes of practice, ministerial conditions and regulations are discussed. Some of the strengths and weaknesses these mechanisms are described, using examples from industry experience. The site specific nature of most mine waste management operations means that one approach cannot fit all situations and the fairness of having a solution acceptable in one operation, but not in another is discussed. Does strict compliance with a human perception of the environment and how it functions promote a ‘lowest common denominator’ approach? The potential technology restricting aspects of requiring ‘compliance’ is discussed and the alternative compliance requirements of ‘outcome’ compliance and ‘process’ compliance considered. The time frame for assessing environmental compliance is discussed. The potential use of simulation models as potential tools for assessing future environmental performance is considered. Moreover, it is concluded that ‘environmental compliance’ means conforming to the environment rather than simply acquiescing or yielding to man-made ‘rules’.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 05/2011; 120(2):118-123.
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    ABSTRACT: A better understanding of the detonation performance of an explosive charge can be gained by directly measuring pressure, temperature and velocity of detonation (VOD). This is particularly important with explosives used in the mining industry because their performance is directly influenced by the degree of confinement given by the borehole diameter and the surrounding rock mass. A project funded by the Australian Coal Association Research Program (ACARP) was initiated in early 2009 with the view to design and build cost effective prototype instrumentation to measure the relative differences in detonation pressures and temperatures of commercial mining explosives. The project’s primary focus was on low density explosives. Low density (also referred to as low shock) explosives have been available in various forms for nearly 20 years. There have been significant advances in the availability, reliability and flexibility of these explosives which now offer a range of densities and degrees of water resistance. Their detonation performance is not well understood and cannot be accurately predicted with current ideal and non-ideal detonation codes. It was therefore viewed as important to be able to directly measure pressure and temperature during the detonation process of these complex mixtures in production blastholes. Identifying the pressure release patterns of both conventional and low density explosives under different geotechnical conditions should provide the necessary information to both validate detonation codes and better define input parameters for breakage and fragmentation models. This paper gives a general description of the prototype instrumentation developed and reports on the results obtained to date in both laboratory and full scale conditions.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 05/2011; 120(2):74-79.
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    ABSTRACT: Agnico-Eagle’s flagship LaRonde Mine is exploiting a world-class Au?Ag?Cu?Zn?Pb massive sulphide lenses complex. It is located in the Abitibi Region of north-western Quebec, approximately 650 km northwest of Montreal. With 5 million ounces of gold in proven and probable reserves, LaRonde has one of the largest gold reserves of any mine operating in Canada. These reserves extend from surface down to 3110 m and remain open at depth. The 2250 m Penna shaft, which is believed to be the deepest single-lift shaft in the Western Hemisphere, is used to hoist LaRonde’s ore production of ?7200 tonnes per day. Current mining operations are taking place at over 2400 m below surface. In 2006, the decision was taken to sink a winze in order to access the ore below 2450 m. The new no. 4 shaft extends to a depth of ?2840 m below surface. With the use of ramps the mine will access reserves as deep as 3110 m. Production from shaft no. 4 is scheduled to begin late in 2011, with the full production rate reached in 2013. It is expected that the LaRonde Extension will extend the mine life well beyond 2020. Sinking a winze shaft and building all the necessary infrastructure of a mine at a depth of over 2·8 km poses unique challenges, some of which are discussed.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 05/2011; 120(2):95-104.
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    ABSTRACT: A detailed analysis of stope performance data from the narrow vein Kundana Gold mine in Western Australia has been made using the extended Mathews stability graph method and comparative statistics. For these Kundana stopes, a poor correlation was found between stope stability and both the Mathews stability number N and hydraulic radius HR. Given that both N and HR correlate well with stability in the vast majority of Mathews method case histories, this suggested that there is an overriding influence on stability at Barkers not accounted for in the Mathews method. Drill and blast issues were isolated as the most likely cause of this poor correlation. Blast pattern was found to have a statistically significant effect on overbreak. In terms of the drill and blast patterns used at the mine, the inline pattern performed significantly better than both the ‘staggered’ and ‘dice-5’ patterns for the vein geometries at the time. Undercut footwalls were found to behave in a similar manner to non-undercut hangingwalls. There was no evidence that backfill abutments behave differently from solid rock abutments in terms of determination of stable stope dimensions. Drillhole accuracy was indirectly examined by considering the effect of stope heights within the limits of 13?20 m. Within these limits, stope height did not affect the magnitude of overbreak.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 05/2011; 120(2):80-89.
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    ABSTRACT: Blast induced rock damage has been related to peak particle velocity (PPV) by many researchers. Some researchers have estimated threshold values of PPV for rock damage by using the Holmberg?Persson near field formula (modified in this paper) and by extrapolation. In this paper, we propose a mathematical formula for assessing the extent of the damage zone by extending the formula proposed by Holmberg and Persson (1979) for the near field vibration approximation. This model gives the damage envelope when plotted in space (x,y). To test the acceptability of the proposed model, a crater blast experiment has been carried out in a surface mining bench with 1 m long and 32 mm diameter drill holes. The holes were loaded with 250 g (0·4 m) of explosive. Vibrations were monitored close to the blast site to establish the vibration predictor. The blast site was seismically imaged before and after the blast. The seismic images (pre- and post-blast) were analysed to determine the extent of rock damage and the damage envelope was computed using the proposed model. It was found that the damage envelopes obtained from the proposed model and from seismic imaging are in close agreement and it can thus be inferred that the proposed PPV based model is a valid means of determining the damage zone. In addition, the damage zones predicted from seismic images were 2?30 times larger than the physically measured crater volumes. Seismic imaging has thus been found suitable for determining the damage extent with reasonable accuracy.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 05/2011; 120(2):90-94.
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    ABSTRACT: Over the last 10 years, Landloch Pty Ltd has developed and applied a distinctive approach to the design of final waste dump shapes and the management of their rehabilitation. Various elements of that approach have been recommended and/or adopted by both industry and regulators to greater or lesser degrees, and with varying levels of both commitment and success. This paper briefly outlines the approach applied, and discusses its limitations and successes, using examples from a number of mine sites. It then considers alternative approaches to landform design that have been advanced, including use of generic guidelines, attempts to mimic natural landscapes, and attempts to simply mimic advanced design methodologies. Conceptual weaknesses of those alternative approaches are reviewed, and potential for further refinement is discussed, again, using data from various sites.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 05/2011; 120(2):112-117.
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    ABSTRACT: The ability to determine the position and orientation of vehicles in real time is a key enabling technology for automation, traffic management, and to ensure safety in the presence of multiple operating vehicles. As explained in this paper, despite some misguided advertising within the mining community, a technology comparable to the satellite based global positioning system (GPS), does not yet exist for underground operations. This paper reports on the preliminary results of a study to develop a relatively low cost and robust method for obtaining globally consistent maps of underground mine environments, the purpose of which is to support the creation of a map based underground positioning technology. The described mapping technique is based on an approach from the mobile robotics research literature and is demonstrated by using data acquired with a load?haul?dump (LHD) machine at two Nordic mines.
    Transactions of the Institution of Mining and Metallurgy, Section A: Mining Technology 02/2011; 120(1):18-24.