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By L O’Connor, S C. Dominy

"Geometallurgy is an important addition to any evaluation project or mining operation. As a discipline, it seeks to maximise the net present value (NPV) of an orebody while minimising technical and operational risk. It also aims to promote sustainable development and initiatives by ensuring that all stages of extraction are performed in an optimal manner from a technical, environmental and social perspective. To achieve these goals, development of innovative technologies and approaches along the entire commodity value chain are being established (Glass, 2016). Geometallurgy has been shown to increase operational stakeholder collaboration, creating an environment for knowledge sharing and improved data acquisition and interrogation, with the end result being the integration of such data into mine planning and scheduling. All of these aspects create better business optimisation, utilisation of staff and targeted and realistic key performance indicators.The mining industry faces numerous challenges including, but not limited to:declining ore gradesgeometrically and/or internally more complex depositsdeep-seated deposits, with potentially high in situ stress regimesincreasing quantities of mine waste that needs to be managed appropriatelyhigher energy, water and chemical costsprocessing of more challenging and refractory ores – textural complexitiesstricter environmental/permitting conditions – so-called ‘licence to mine’increasing demand for specialist metals (eg rare earth elements, In, Ge, Te, Rh, Se, Ga and Li)commodity market volatilitya difficult funding environment.Given these challenges, geometallurgy provides the opportunity to control or at least manage some of them.CITATION:Dominy, S C and O’Connor, L, 2016. Geometallurgy – Beyond Conception, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 3–10 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

"Geometallurgy is a discipline that seeks to improve the sustainability of the extraction of metals and minerals by promoting the smarter use of non-renewable resources, better energy efficiency and greater use of renewable energy. To achieve these goals, development of innovative technologies and approaches are being developed along the entire commodity value chain, starting with exploration and extraction and extending to reuse and recycling. This paper discusses the geometallurgy of industrial minerals with special emphasis on kaolin, a versatile industrial mineral applied in ceramics, paper, paint, plastics, rubber, pharmaceuticals, cosmetics, ink, sealants, adhesives, sanitary ware, glass fibre, toothpaste, animal feed etc. Aspects of kaolin extraction in south-west UK are analysed from a geometallurgical perspective. While geometallurgy already features in kaolin extraction, its role can be significantly expanded by combining advanced in-pit characterisation and orebody modelling with integrated planning and control of the refining and calcination process. This paper highlights the importance of innovation in realising the full potential of geometallurgy.CITATION:Glass, H J, 2016. Geometallurgy – Driving Innovation in the Mining Value Chain, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 21–28 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By J J. Eksteen

"In the platinum group metals (PGM) industry, smelters are often perceived as ‘black boxes’ that have to process concentrates of variable mineralogy and originating from multiple mines operating along strike or downdip from each other in the same geographical region, as is the case in the Western Bushveld of South Africa. However, PGM smelter complexes are much more sensitive to concentrate blend variation than most metallurgists or geologists would anticipate.This paper will review the impact of concentrate blends deriving from a number of concentrators processing ores from the Bushveld Igneous Complex (BIC) on smelting and converting behaviour and the constraints they impose upon smelter operation. Significant variation in behaviour is not only noted between the main mineralisation types, namely the Merensky and Upper Group 2 (UG2) reefs, but also within a given reef type. Due to the way PGMs are mineralised and finely disseminated, concentrators have to grind concentrates ultra-fine to liberate the PGMs and provide a sufficiently high-grade concentrate for smelting.The chemistry and mineralogy of the concentrates vary with the type of mine (open pit versus underground), the reef type and varies along strike; this variation impacts numerous key smelter parameters such as the base metals content, the matte fall, the converter aisle capacity, sulfur dioxide gas production, furnace matte and slag temperatures, and the accumulation of high smelting chromite-spinel minerals that has led to significant smelter upset conditions such as catastrophic furnace hearth and sidewall failures.Due to the production intensity of smelting, ie its high rate of processing per unit volume, smelters have been found to be far more sensitive to rapid variation in concentrate properties, highlighting the need for adequate blend control.CITATION:Eksteen, J J, 2016. Impact of Mineralogical Variation on the Smelting of Cu-Ni-PGM Concentrates, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 321–326 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By A Riles

"Three issues of relevance in a modern tailings storage facility (TSF) are:geotechnical stabilitymanaging acid rock drainage (ARD) from pyritic tailingsmanaging the tailings from cyanidation of gold ores. Drawing on examples from both copper porphyry flotation and sulfide-hosted gold ores, this paper demonstrates that giving some weight and importance to the process tails properties upfront can influence the flow sheet and not only improve tailings management effectiveness but also impact positively on economics. In the case of a typical copper porphyry ore with moderate pyrite content, the rougher tail in a conventional high pH selective flotation step is usually classified as potentially acid generating (PAG). To avoid the generation of ARD within the tailings and the requirement for a costly plastic lining, subaqueous deposition is recommended, which in turn has negative implications for tailings stability, consolidation and closure. Adopting a neutral pH rougher stage rejects silicate gangue but recovers pyritic material to the cleaners for a subsequent selective flotation stage, often after regrinding. This effectively quarantines the PAG pyritic material in a much lower volume cleaner tail, which can then be appropriately encapsulated within a larger non-lined flotation tails facility. It also facilitates cyanide leaching of the cleaner tail for gold recovery, with the encapsulated tailings facility being suitable for cyanidation tails storage. A case study from Europe is examined. For gold ores where the gold is sulfide-hosted, but not refractory, a flotation route with cyanidation of the concentrate can similarly produce the majority of tailings as a benign flotation tail and again quarantine the low volume concentrate leach tail in a small encapsulated cell with appropriate residual cyanide management measures applied. Overall economics for intensive leaching of a low volume concentrate stream can also be surprisingly positive. A feasibility study design example of the process and TSF is presented. CITATION: Riles, A, 2016. An Integrated Approach to Optimising All Concentrator Products, Including Tailings, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 341–346 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By Y Xie, L O’Connor, S C. Dominy

"Sheeted vein gold deposits are characterised by multiple subparallel veins and free milling gold. In situ heterogeneity of mineralisation results in grade and process parameter variability, which will increase project risk. Measured variability is often enhanced by poorly designed sampling and test work protocols. Protocols that are optimised within the framework of the theory of sampling to suit the ore type, together with quality assurance/quality control systems, will reduce variability and provide fit-for-purpose results. The geometallurgical approach requires spatially distributed samples within a deposit to support variability modelling. Diverse attributes from core logging, mineralogical/textural determination and small-scale tests are used to measure variability. This contribution emphasises early stage geometallurgical intervention during project development. It presents a discussion of representative sampling in the context of the theory of sampling. A case study presents a protocol that exemplifies how data can be gained from a well-designed and planned program to support a resource estimate and prefeasibility study.CITATION:Dominy, S C, O’Connor, L and Xie, Y, 2016. Sampling and Test Work Protocol Development for Geometallurgical Characterisation of a Sheeted Vein Gold Deposit, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 97–112 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By J Li, A McFarlane, J Yu, L L. Kuhar, R Meakin, N Chapman

"Column leach tests are used frequently to predict recoveries and reagent consumption for nickel laterite heap leaches. These column leaches often run for more than 100 days and therefore require long-term monitoring and data analysis to achieve the desired information. To minimise the cost and time required to obtain relevant information for nickel laterite heap leaching, we have developed a small-scale hydrogeometallurgical laboratory test to serve as a proxy to column, and by inference, heap leaching. In excess of 50 leach tests were conducted using four different small-scale proxy and column leach tests to compare predicted nickel recoveries, acid consumption and leach kinetics and to determine whether insight into potential scale-up effects can be obtained. The most promising proxy test was identified and we achieved a statistically significant recovery and acid consumption correlations between this test and the column leach tests. The accuracy of the small-scale tests was confirmed by column tests run on new laterite ores. This geometallurgical proxy could be of use for the population of block models and process selection during the mine planning phase or for optimisation and control during processing.CITATION:Li, J, Kuhar, L L, Meakin, R, Chapman, N, McFarlane, A and Yu, J, 2016. A Geometallurgical Proxy for Nickel Laterite Heap Leaching, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 335–340 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By C M. W Boyle, E K. C Phuak, A Lewan, E Ryan, M D. Paine, P H. Mackenzie

"Rio Tinto Iron Ore (RTIO) has an extensive history in the application of geometallurgy to the iron ore value chain. Fundamental to this has been the geological logging of material types which are assigned processing attributes such as lump per cent and density. Initially these were used for product (lump and fines) grade predictions in relation to grade blocks to be used within short-term planning horizons.More recently the predictive reach of the material types and their associated processing attributes has been extended due to their inclusion into geological block models. These predictions can now be used to influence mine plans across multiple planning horizons in such a way that the extremes of geometallurgical properties can be pre-empted and managed thus improving efficiency. Spatial material type domains are also used in the planning of metallurgical drill holes to ensure greater representivity of material than was typically obtained by chemical and/or stratigraphic criteria alone.Material type logging has also been enhanced by the introduction of modern, rapid mineralogical techniques that have complemented visual logging. This has enabled the identification and quantification of contaminant minerals and their relationships with host ore types to be established. This data is used to better manage product grade predictions and identify risks to the short-term plan.Work is ongoing in RTIO to further refine logging based predictions and in addition apply them to new areas of the business. This work requires collaborative and multidisciplinary teams working on an integrated approach combining geology, metallurgy, technology and innovation, mine planning and technical marketing.CITATION:Paine, M D, Boyle, C M W, Lewan, A, Phuak, E K C, Mackenzie, P H and Ryan, E, 2016. Geometallurgy at Rio Tinto Iron Ore – a New Angle on an Old Concept, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 55–62 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By A McGann, P J. Coghill, D Miljak

"It is widely accepted that bulk ore sorting could provide a step change in processing of low-grade ores. For this to be achieved a rapid, accurate bulk sensor of grade is required as well as sufficient natural variation of grade in the ore stream. CSIRO trialled a magnetic resonance (MR) sensor capable of measuring chalcopyrite, and by inference total copper grade, on the 1300 t/h Ridgeway portal conveyor. The gauge produced an unprecedented set of data down to a 1 t scale for months at a time. This paper analyses the measured variation and compares it to a simple model derived from the bore core data and mixing within the block cave mine.The model of the small-scale (<1000 t) variation is developed using fractal methods which have successfully been used in the past for copper porphyry deposits showing a power law or near power law distribution of copper grade and vein sizes. These fractal distributions have two features highly favourable for segregating ore, a large proportion of low-grade pods and the large-scale spatial clustering of grade. We show the presence of fractal ordering in bore core data at short range in the Cadia Ridgeway porphyry deposit and measure its persistence in the crushed rock produced by the Ridgeway block cave mine over one month. The model is then extended to demonstrate the effect of varying head grade, mixing and pod (or diversion) weight on bulk sorting efficiency.CITATION:Coghill, P J, Miljak, D, McGann, A, 2016. Modelling Grade Variation in Crushed Ore at Cadia Ridgeway and Its Potential Consequences for Bulk Ore Sorting, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 77–88 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By I M. Platten, Y Xie, B W. Cuffley, S C. Dominy

"Geometallurgical programs require the collection of representative samples for geochemical, mineralogical and metallurgical test work. Such protocols must be designed to suit the style of orebody in question. The distribution, proportion and size of gold particles have a direct impact on the effectiveness of sampling and test work protocols, and the gold recovery processes employed. Characterisation studies focusing on ore mineralogy, and gold particle deportment, size and distribution are required. High resolution X-ray computed tomography provides a non-destructive method for analysing the 3D nature of gold in rock samples. It can be used to calculate the modal abundance, particle size and distribution of gold in the sample volume. This paper presents a case study of the imaging of in situ gold particles in a high-grade gold ore. The Nick O’Time reef system comprises laminated quartz veins, which locally bear extreme grades of up to 100 oz/t gold. The mineralisation has previously been characterised from both a mineralogical and metallurgical perspective. Eight visible gold-bearing vein samples were scanned using X-ray microtomography. Microtomographic data were integrated with previous mineralogical and metallurgical test work outputs.CITATION:Dominy, S C, Platten, I M, Xie, Y, Cuffley, B W and O’Connor, L, 2016. Characterisation of Gold Ore from the Nick O’Time Shoot (Tarnagulla, Australia) Using High Resolution X-ray Computed Tomography, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 241–254 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By J. Grubb

"The undertakings described in the paper titled “Study on correlation of quantified coal rank with self-heating temperature” by Wang and Luo in the November 2015 issue of Mining Engineering (Wang and Luo, 2015) are mathematically sustainable and an acceptable extension of work performed by Smith and Lazzara (1987) for the U.S. Bureau of Mines. The paper is not an accurate explanation of the currently accepted leading practice for determining the propensity of a coal seam for spontaneous combustion. The paper could lead a practitioner to an oversimplified conclusion on how to determine the propensity of a coal seam to spontaneously combust.The spontaneous combustion of coal is a complex and not fully understood reaction. What is understood is that many more factors other than selfheating temperature (SHT) and coal rank are required to sufficiently evaluate the risk of spontaneous combustion in a particular coal seam. A superficial assessment can lead to an improper response to the risk. Some statements on the next steps through an appropriate literature search would have made the authors’ conclusions more credible.The SponCom 2.0 software, updated by the National Institute for Occupational Health and Safety (NIOSH) in 2011, provides a path for evaluating the susceptibility of a coal seam to spontaneous combustion. In addition to proximate and ultimate analyses to establish coal rank, and therefore an estimate of SHT, the program includes the history of heatings, friability, seam thickness, overburden thickness, rider seam presence, pyrite presence, face and butt cleat densities, geothermal source presence and other geological features in the assessment. Mining conditions including floor heave, rib sloughage and rate of advance are also assessed to conclude a propensity for spontaneous combustion."

Jun 1, 2016

By J. Kretschmann, R. Amiri

"The Sangan iron ore mines (SIOM) in Iran are located in a remote area near the Afghanistan border. The SIOM deposit contains a geological resource of 1.1 Gt (1.2 billion st) of mostly magnetite with an iron (Fe) grade ranging from 27 to 61 percent. The Iranian government plans a stepwise development of SIOM in cooperation with private companies to satisfy the growing demand of the Iranian steel industry. Sustainable development is an influential ethical concept in mining all around the world. However, a successful realization of a sustainable development plan is not possible without a foundation on the core values and regarding the specific circumstances of the individual mining country. This paper introduces SIOM and describes sustainable development activities undertaken during its development. From the early stages, these activities have been realized to secure the acceptance of the stakeholders in the region. To evaluate their effects, indicators were filtered to the ones with the highest priority for the stakeholders. Moreover, Islamic values and Iranian regulations and their influences on SIOM were analyzed.Mining industry in Iran The Islamic Republic of Iran holds 68 types of minerals, including salt, sand and gravel, gypsum, chrome, lead, zinc, copper, coal, gold, iron, etc., with 33.5 Gt (37 billion st) of proven reserves and more than 51.7 Gt (57 billion st) of potential resources. Iran is ranked among the 15 major mineral rich countries (1). In accordance with the statistics published by Statistical Center of Iran (SCI), there were 5,316 active mines and 84,922 employees in the whole country in 2012-2013 (2) and, according to the statistics published by Central Bank of Iran (CBI) in 2011, the share of this sector in the gross domestic product (GDP) of the country was 1.2 percent (3)."

Jun 1, 2016

By L. Yuan, A. C. Smith

MFIRE, the mine-fire simulation program of the U.S. National Institute for Occupational Safety and Health (NIOSH), is widely accepted as a standard for assessing and predicting the impact of a fire on the mine ventilation system and the spread of fire contaminants in coal and metal/nonmetal mines. MFIRE has been used by U.S. and international companies to simulate fires for planning and response purposes. It is a dynamic, transient-state, mine ventilation network simulation program that performs normal planning calculations. It can also be used to analyze ventilation networks under thermal and mechanical influence, such as changes in ventilation parameters; external influences, such as changes in temperature; and internal influences, such as a fire. The program output can be used to analyze the effects of these influences on the ventilation system. Since its original development by Michigan Technological University for the former U.S. Bureau of Mines in the 1970s, several updates have been released. In 2012, NIOSH completed a major redesign and restructuring of the program with the release of MFIRE 3.0. MFIRE’s outdated Fortran programming language was replaced with an object-oriented C++ language and packaged into a dynamic-link library. However, the MFIRE 3.0 release included no change or improvement to the fire-modeling algorithms inherited from its previous version, MFIRE 2.20. This paper reports on improvements that have been made to the fire-modeling capabilities of MFIRE 3.0 since its release. These improvements include the addition of the t-squared fire as a new fire-source model and the ability to include available heat-release-rate versus time data, the addition of a moving fire source for conveyor-belt fire simulations, improvement of the fire location algorithm, and the identification and prediction of smoke-rollback phenomena. All of the improvements discussed in this paper will be included in MFIRE 3.1 and released by NIOSH in the near future.

Jun 1, 2016

By R J. Butcher

Many deposits have been evaluated as potential block caves over the last 20 years due to the perceived benefit of low operating costs. However, block cave projects are typically capital intensive, with mass mining providing high throughput rates that required large investments in mining, processing and utilities infrastructure. While the key economic metrics in deciding to proceed with a caving project are typically net present value (NPV) or internal rate of return, these may not represent the best decision metrics for some companies. Where a caving project is competing for scarce capital amongst other projects in a company’s portfolio or where the caving project is the only project being evaluated by a company trying to raise capital, other metrics may be more appropriate. This paper explores the use of present value ratio and the minimising of maximum negative cash flow as suitable metrics in determining alternative strategies. Trade-offs between optimising for economic value and capital efficiency measures allow for decision-makers to evaluate potentially higher-risk, higher-capital and maximum NPV projects against lower-risk, lower-capital projects.CITATION:Stewart, C A and Butcher, R J, 2016. Block cave evaluation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 809–816 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By F Brenguier, R A. Lynch, G Olivier

The seismic velocities of intact rock are dependent on the applied stress. Unfortunately, the low susceptibility of seismic velocity to stress changes mean that changes in seismic velocity have to be measured extremely accurately to infer stress changes from them. Previously, it was thought that measurements of this accuracy could only be made with active sources or repeating earthquakes. In this paper, we show that the noise generated by mining activity can be used to construct virtual seismic signals with which we can measure changes in seismic velocity accurately enough to see the short- and long-term effects of a production blast on the surrounding medium. The time-dependent velocity variations achieved with this method show that the blast caused weakening of the rock mass for the rock within a radius of 200 m of the blast. The weakening is healed by confining stresses over a period of five days, after which permanent changes in the seismic velocity can be seen. The size and spatial distribution of the seismic velocity changes were compared to modelled changes in static volumetric stress, which supported the notion that seismic velocity changes can be used to measure the redistribution of stress after a blast. The results of this study indicate that this method can be a powerful tool to evaluate the evolution of stress in a mine at a relatively low cost as the data that it uses would normally be discarded.CITATION:Olivier, G, Lynch, R A and Brenguier, F, 2016. Measuring the redistribution of stresses resulting from new excavations with ambient seismic noise correlations, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 873–878 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By G Brudek, P Elestedt

Schalker Eisenhütte und Maschinenfabrik GmbH, Nordic Minesteel Technologies and Bombardier Transportation have developed an evaluation tool that considers the main cost drivers of the rail, truck and conveyor haulage systems on the market today. In almost every circumstance, the advantages of a haulage solution are clear. A haulage system is outlined that is fully automated, including driverless operation, and that provides increased tonnage, safety and equipment life and reduced maintenance downtime. The haulage system has been implemented by a number of companies, including Codelco, LKAB and Freeport’s Grasberg mine. CITATION:Brudek, G, Elliott, R P and Elestedt, P, 2016. Moving mORE for less, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 535–542 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By D Elmo, M Scoble, Y Liu, B Klein, J Scholar, S Nadolski

A cave-to-mill study being conducted at the New Afton block caving operation demonstrated the potential for sensor-based ore sorting equipment to reject waste and improve the grade of feed to the mill. The lack of selectivity and potential for dilution entry associated with the block cave mining method results in many caving operations having to mine and process material that is below cut-off grade at certain stages of production. Online monitoring and bulk sorting systems have the potential to alleviate this problem and improve the productivity of caving operations while reducing energy and water requirements for each tonne of concentrate produced.As part of the cave-to-mill study, the suitability of a range of sensors, such as X-ray fluorescence and induction-type sensors, to sort mine production at the New Afton mine was investigated. Results showed that the discrimination of ore and waste can potentially be carried out by implementing surficial sensors into the material handling system. The study also showed that a combination of sensor outputs could be used to identify a certain ore type so that pre-emptive changes can be made in the mill to improve beneficiation performance. Overall, the outcomes of the study on implementing sensor systems at block cave mines are considered to be of significant relevance to a number of existing and future caving operations.CITATION:Nadolski, S, Klein, B, Elmo, D, Scoble, M, Liu, Y and Scholar, J, 2016. Investigation into the implementation of sensor-based ore sorting systems at a block caving operation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 393–400 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By A Flatten, F Reusch

Recent advances in the disciplines involved in simulating large mining operations provide increasingly precise and accurate methods for the study of cave mechanics; however, in large regional-scale models, hydrological aspects are often neglected or studied independently from the mechanical problem. There exists a great demand for a unified approach to study and simulate both the mechanical and hydrological phenomena that allows for a more detailed understanding of the effects of groundwater flow, dewatering and the impact on block cave mining operations.This paper presents a numerical framework that combines three-dimensional regional-scale hydrological simulation techniques for groundwater flow, together with non-linear continuum–discontinuum rock mechanics models, provides such a unified modelling approach. The underlying simulation technique is based on a coupled parallel solution formulation adopting single-phase fluid flow formulations into a discontinuous, strain softening and dilatant finite element model. This approach is adopted for the presented case study of a realistic block caving example in a simplified unidirectional coupling formulation, to investigate the effects of the mechanical analysis on the hydrological response. Here, particular emphasis is on the non-linear coupling of the deformable and strain-softening solid skeleton and fluid phase; eg the change of hydraulic properties with evolution of damage in the rock mass and large-to-intermediate scale structures due to ongoing caving operations. The importance of discontinuum structures is discussed, as mining-induced fault reactivation significantly influences the hydrological response.CITATION:Flatten, A, Reusch, F and Beck, D, 2016. The application of hydromechanical mine-scale modelling for large block caving operations, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 341–348 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By S Steffen, S Talu, J Poulsen, G Watt, A van As, J S. Ooi

The economic success of cave mining projects is significantly influenced by the secondary fragmentation size distribution of the caved orebody and making the fragmented ore available for extraction. If the cave does not propagate as predicted, it may lead to stalled cave growth and/or localised preferential caving. This can cause significant ore loss and the inclusion of excessive waste in draw columns, both of which damage the economic value of the project. Uncontrolled caving can have severe consequences for the safety and economics of mines. Such safety risks include air blasts due to the formation of excessive air gaps and damage to infrastructure due to surface subsidence. Monitoring the cave-back delivers critical feedback that is required to exert control over its propagation and reduce the likelihood of adverse consequences. Current methods for monitoring cave propagation include access through open holes, microseismic monitoring systems, time domain reflectometers and extensometers. All of these monitoring systems rely on stable holes for installation and ongoing data collection. However, cables in holes often get sheared due to ground movement in the seismogenic zone well ahead of the cave front, rendering the systems useless. To resolve this issue, Elexon Mining, with the support of Rio Tinto, developed the Networked Smart Marker system, which is based on Elexon’s Smart Marker technology. This system provides a more robust and versatile alternative to other cave monitoring systems as the data is transmitted wirelessly through rock, and thus is not vulnerable to hole shearing/dislocation experienced with current cave monitoring systems. Installations at the Argyle block cave have proven that the Networked Smart Maker system can continue to provide information on the cave-back’s location long after all conventional monitoring systems have failed. This paper summarises the findings from these installations and highlights the benefits for all geotechnical monitoring systems reliant on the stability of drill holes to remain functional.CITATION:Steffen, S, Poulsen, J, Van As, A, Talu, S, Watt, G and Ooi, J S, 2016. Wireless system for monitoring cave-back propagation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 251–256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By M Svartsjaern, D Saiang and K Mäkitaavola

The Kiirunavaara mine is a large-scale (28 Mt/a) iron ore mine located in northern Sweden. The mine is owned and operated by Luossavaara-Kiirunavaara Aktiebolag (LKAB) using sublevel caving (SLC). The SLC area underlies an open pit decommissioned in the 1950s, the current main SLC haulage level is situated at an depth of 1100 m. The main orebody dips 60 degrees to the east with a distinct boundary defining the hanging wall to the east and footwall to the west. Since the 1980s damage has been observed both in the footwall rock mass as well as on the footwall crest of the open pit. Recent investigations indicate that the underground footwall damage is primarily controlled by large-scale slope failure mechanisms. Structurally controlled near-vertical planar shear failures in the upper footwall appear to be driven or facilitated by a step-path like curved shear failure situated in a zone starting ca 250 m, and intersecting the SLC about 100 m above the active mining level. To confirm this failure evolution a pilot underground measuring system has been designed and installed to monitor the expected rock mass displacements indicated by numerical models based on the above mechanisms. The systems consists of 50 m time domain reflectometry (TDR) coaxial cables installed in the footwall both across and away from an estimated damage extent boundary to monitor shear movements along natural joint surfaces. The TDR installation is combined with long extensometers to facilitate differentiation between diffuse shear and rock mass normal expansion. Additionally, a low-tech system of tape extensometer lines are installed in drifts and stopes running perpendicular to the ore strike to monitor horizontal displacements in the infrastructure as the footwall ‘slope’ loses confinement during mining advance when the mined out areas are replaced by caved rock from the hanging wall.CITATION:Svartsjaern, M, Saiang, D and Mäkitaavola, K, 2016. Underground footwall monitoring at the sublevel caving mine – Kiirunavaara, Sweden, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 773–780 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By R Long

The founder of social psychology is sometimes identified as Kurt Lewin. In a 1947 article, Kurt Lewin coined the term ‘group dynamics’. He described this notion as the way that groups and individuals act and react to changing circumstances. Lewin theorised that when a group is established it becomes a unified system with unique dynamics that cannot be understood by evaluating members individually. The discipline of social psychology really emerged out of World War II and tackled questions associated with human judgement and decision-making by the Nazis. For a comprehensive look at the development of social psychology look at Abelson, Frey and Gregg (2004).Social psychology is concerned with the way social arrangements affect human judgement and decision-making. What the author has done is apply the knowledge of this new discipline to an understanding of risk, safety and leadership. This paper will explain some of the developments in social psychology, such as the discovery of the bystander effect, Groupthink, bounded rationality, heuristics, risk homeostasis and the Milgram effect.The social psychology of risk tackles the way decisions are made about risk in their social context. Unless organisations understand that decision-making is socially conditioned, they are unlikely to be able to tackle the complexities of culture change or the development of risk maturity.The paper will offer a new understanding of why people do what they do, how risk makes sense and why a ‘dumb down’ approach to safety is dangerous. A model will also be presented that shows the pathway to risk maturity.CITATION:Long, R, 2016. The social psychology of risk, safety and leadership maturity, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 31–42 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016