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By R Osterman

As mining companies have to go deeper in search of ore and coal, the importance of protecting the highwall increases. Wall fatigue also increases with importance of the long life expectancy of a highwall, in particular the impact of fatigue influenced by resonance. Resonance is the tendency of a material to oscillate with greater amplitude at certain frequencies when exposed to a periodic force. Until recently, only dominant frequencies, either natural or induced, were all that could be measured through the fast Fourier transform of the blast-induced wave form.This paper presents a novel method to accurately predict the resonant frequency of a highwall. In fact, the method can predict the natural frequencies between any two monitoring points placed in line with the source of impact, and as such it can be used to determine the resonant frequencies of any physical object. The method not only predicts the resonant frequencies of the material; it predicts the structural response of the total frequency spectrum. This method helps describe the response of a mechanical structure to excitation. It describes the structure’s efficiency in the use of energy, that is, whether energy is dampened or consumed in resonance.The initial predictions have been so accurate that it made it possible to determine the fundamental frequency and the first six harmonics of a highwall in a northern Queensland coalmine. With the use of electronic detonators, the blast can be timed with a repeating delay to create an induced artificial frequency that has been determined to retain the least amount of energy.CITATION:Osterman, R, 2015. Transfer function – new method to accurately predict resonant frequencies of a highwall, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 233–244 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By A Cheatle

GoldcorpÆs Musselwhite mine in north-western Ontario, Canada has in recent years become a world-class deposit. Initially discovered in the early 1960s by Alan and Harold Musselwhite, the then marginal mine eventually started production in 1997 and has to date produced 2.6 Moz of gold. Two million ounces of gold are currently classified as Mineral Reserve and a further 1.2 Moz of gold are classified in the Mineral Resource category for a total gold inventory approaching 6 Moz. Growth of the mineral inventory has been achieved through the successful implementation of strategic planning that sought to extend the mine life through discovery of additional economic zones and increased mined tonnages. Accelerated exploration activity commenced in 2001, at a time when gold price was at its lowest in decades. Focus was placed on building, developing and retaining a highly skilled geological team, maintaining purpose, conducting external reviews and developing a new geological model through research partnerships. Ongoing collaborative research between Lakehead University and Musselwhite mine has seen the development of new structural and geological models through post-graduate and academic studies. Research has included lithogeochemical, stable isotope and structural and metamorphic studies and has led to the evolution of a new mineralisation model (for the mine) and the recognition of brittle and ductile deformation regimes within the mineralised horizons. Exploration drilling continues to provide support for the new geologic model. Gold discoveries have extended known mineralisation 2.3 km along strike from mineral reserves and laterally into parallel zones. The exploration potential to further increase production rates, Mineral Reserves and Resources remains very positive and increases in overall gold inventory are likely. Musselwhite mine has significantly exceeded initial projections for a ten year life-of-mine and a marginal existence.

Jan 1, 2009

Intrusion related Cu/Au mineralisation is localised in Pacific Rim island arcs by arc parallel, termed accretionary structures; or arc normal, termed transfer structures. In Papua New Guinea, NE trending transfer structures, evident on Landsat imagery, represent deep crustal fractures which have facilitated dextral rotation of the mainland during oblique plate collision. Major structures localise intrusion centres, and by rotation, develop ore hosting dilational environ-ments in subsidiary structures. While transfer structures localise the Porgera, Wafi and Yandera porphyry centres, the Frieda Porphyry and associated Nena high sulphidation Cu/Au mineralisation are localised by accretionary structures. The Bulolo Graben, which hosts the Morobe Goldfield, developed during intra arc rifting aided by movement on transfer structures. Crustal thinning has initiated magmatism with which diatreme breccias and fracture controlled mineralisation are associated.

Jan 1, 1994

By D Kavanagh, C Michaud

"A continuous improvement initiative was identified at Kalgoorlie Consolidated Gold Mine’s (KCGM) Fimiston open pit with the goal of reducing bench turnover time and increasing shovel digability by improving fragmentation around previously mined-out stopes. In the past, a higher number of blasts than normal would be required to get through a single excavation area where stopes were present. This is due to the limited reach capability of the drilling fleet from safe ground into restricted areas requiring the drilling of the shot to be done in a staged manner. In addition, the holes that were able to be drilled in the area did not remain open long enough to be loaded with explosives as a result of the poor ground conditions surrounding the stopes.Over the last 18 months, KCGM has trialled drill additives to improve blasthole stability, as well as introducing a remote drill rig allowing holes to be drilled in areas previously inaccessible by manned drill rigs. This has resulted in improved penetration rates in bad ground conditions, improved drill hole stability, better shovel digability, and an overall reduction in bench turnover of at least ten days on the benchmarked 126 days average per bench. KCGM is now in the final stages of the improvement project with the installation of a drill monitoring system on the fleet to allow live data transfer back to the office for analysis, as well as providing improved accuracy on drill holes in restricted areas.Citation:Michaud, C and Kavanagh, D, 2016. Reducing Bench Turnover Time and Improving Shovel Digability, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 19–27 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By D Baas, J Le, R Braun, R Chandramohan, K Hollis, G Lane

The Phu Kham Copper-Gold Operation (Phu Kham) is located in northern Laos, approximately 140 kilometres from the capital, Vientiane. The operation is a producing asset for Australian-based copper and gold producer, PanAust Limited (PanAust) and is operated by Lao-registered company, Phu Bia Mining Limited (Phu Bia Mining). PanAust holds a 90 % interest in Phu Bia Mining. The Government of Laos owns the remaining 10 %.The Phu Kham Operation has recently undergone a series of process improvements to treat the anticipated competent ores scheduled for 2017 and 2018. The operation’s comminution circuit, which comprises a semi-autogenous (SAG) mill and two ball mills, each with 13 megawatts (MW) of installed power, was expected to be SAG mill limited when treating competent basement rock. Ausenco Services Pty Ltd (Ausenco), was engaged to help optimise and enhance the productivity of the Phu Kham comminution circuit over an eight-month period. The work involved participating in and overseeing the redesign of the SAG mill liner systems and developing operational strategies for maximising throughput through to the end of mine life. Ausenco’s comminution optimisation tool, Ausgrind, was used to benchmark and analyse plant data with empirical models, predict circuit performance for varying ore characteristics and evaluate liner wear and predict the life for varying operating parameters. Variances between the actual and the predicted values were assessed in detail to identify missed opportunities, and guiding operating parameters were redefined to maximise throughput and productivity. In combination with the redesigned liner system, optimised process controls for varying ore competencies, and improved operational practices and troubleshooting strategies, increased Phu Kham overall production, exceeding the milling capacity when treating competent ores. CITATION:Chandramohan, R, Braun, R, Lane, G, Hollis, K, Le, J and Baas, D, 2018. SAG mill optimisation and increasing throughput at the Phu Kham Copper-Gold Operation – a success story, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 113–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

Recovery of gold by smelting zinc dust concentrate has been carried on at Lake View and Star, Ltd., since July, 1930, when the Merrill-Crowe precipitation plant was first put into operation.Part I describes the development of current gold-room practice, commencing with the clean-up of the MerrillCrowe plant, a procedure that has not materially changed since its inception, and then shows how modifications to straight roasting and smelting became necessary, following a gradual increase in the copper content of the ore treated by the mill.Present smelting practice converts most of the copper into a mixed copper-lead matte, thE sulphur being supplied by the addition of flotation concentrates containing about 35% sulphur as pyrite. The process yields gold bullion of a sufficiently high grade to send to the Royal Mint, but until 1943, suffered from the disadvantage of giving matte and slag by-products high in gold and silver, that were not recovered directly but had to be sent to a smelter.Part Il gives details, of experimental work cnrried out since 1943 which led .to a process for the satisfactory and economic recovery of not only the gold and silver, but also the copper from these, hitherto, troublesome by-products. Nevertheless, incidence of matte in a smelt has always been considered undesirable, and it is hoped that eventually it will be obviated by removing most of the copper from the zinc slime before smelting.Part III indicates the methods by which this might be achieved, and outlines the experimental work that has been done up to the present.

Jan 1, 1948

By H-S Yang, H Park, S-J Kim, Y-H Ko, H-S Kim, S-H Cho, J-K Kim

An investigation was undertaken to devise a new method for reducing dust spread during blasting demolition utilising water tube and detonating cord. Modelling of smooth particle hydrodynamics (SPH) with AUTODYN software was initially completed to determine the expected diffusing behaviour of the water tube. The actual behaviour was then captured with high speed videos during each experiment, and each result analysed in detail. Water mist diffusion was generated and analysed by changing three key variables. In sequence, these included changing the location of detonating cord in the tube, the charge quantity and the tube diameter.As a result of experiments and simulation, optimum design for ideal diffusion behaviour was suggested and each behaviour of water mist was classified by diffusing shape of water tube as the design criteria.CITATION:Ko, Y-H, Kim, J-K, Kim, S-J, Park, H, Kim, H-S, Cho, S-H and Yang, H-S, 2015. Mist diffusion experiment and evaluation of water tube for blasting demolition dust control, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 809–814 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By J Rubio

This work presents design features of an innovative in-line mixing helical (coiled) reactor for flocculation and flotation as a solid-liquid separation process for suspended particles (including liquid droplets). The device has been named flocs generator reactor (FGR), a compact system whereby the flocculation of particles is assisted by the kinetic energy transfer from the hydraulic flow through the reactor and/or by the injection of microbubbles (30 - 70 ¦m). The flow mixing presented a plug flow regime with a low dispersion degree, promoting the required hydrodynamic conditions to disperse the polymer flocculant (cationic polyacrylamide) and to generate æstrongÆ flocs of Fe(OH)3 or clays (as colloidal model systems) with aggregation using an anionic polymer, Al2(SO4)3 and poly aluminium chloride (PAC), and oil emulsions destabilisation with a high molecular weight cationic polymer. The solid-liquid separation of the flocs was then achieved either by settling or by flotation with microbubbles. This paper discusses advances in this new in-line flocculation-rapid flotation device to remove æaerated aggregatesÆ, aggregates with entrained and entrapped bubbles. Studies were carried out with different models of FGRs (varying the length:volume ratio) and process efficiency (mainly kinetics) evaluated as a function of polymer concentration and some operating parameters, namely, feed flow-rate, air:solids ratio and residence time. Results showed that the aerated flocs are readily floated with rising rates in the order of 120 mh-1, values higher than those obtained for the settling of the non-aerated flocs (18 - 24 mh-1). The FGR requires short residence times and generates dense, well structured flocs (with a mass fractal dimension, dF of about three) which withstand high shear forces. Mechanisms involved appear to include small bubble formation and their rapid occlusion (entrapment) within flocs, nucleation of bubbles at floc/water interfaces, polymer coiling as a result of æsalting outÆ effects at the aqueous/air interface and plug flow type of mixing (flocculation). Successful examples of emulsified oil and solids removal from water are shown and because in all cases high efficiencies were obtained (>90 per cent removal). Due to the high process efficiency and high loading capacity shown, the FGR appears to have good potential as an in-line flotation-separator device in applications requiring high rate solid-liquid or liquid-liquid separations.

Jan 1, 2005

By T Kojovic, S J. Windle, J Sullivan

"The Geometallurgical Mapping and Mine Modelling (GeM) comminution index (CI) was developed as part of the AMIRA P843 GeMIII project. Drill core geochemistry samples were passed through a Boyd Crusher with standardised settings and the resulting particle size distribution (PSD) was measured using sieves.Disadvantages of the original measurement were the relatively coarse crush size, requiring a second pass of crushing for geochemical sample preparation, and the limitation of throughput caused by the sieving step. At Antamina, the measurement has been modified to use a 2.2 mm crusher size setting, which permits a single pass. The PSD is measured using a Camsizer, an automated optical sizing instrument. The Camsizer sample is a +180 µm fraction, used to avoid passing too many fines through the instrument and slowing down the measurement. In the sieving step, the weights of the two fractions are recorded and subsequently used to normalise the distribution measured by the Camsizer. In this way, the throughput of the Camsizer can match that of the Boyd Crusher. The PSD data are therefore measured without penalising the throughput of the sample laboratory.The normalised PSD distributions are used to derive modified CI parameters, based on the slope and intercept of the breakage product size distribution, which are indirect measures of the material breakage hardness.Fifty samples were selected as a training set, each sample a composite of five or six individual assay intervals and each with its own measured CI. The average PSDs were calculated for the composites and used to calculate a composite CI. The intact half of the core, approximately 40 kg, was tested to measure the BWi, A*b and crushability. The results were used to develop predictive algorithms for these hardness parameters.A further 50 composites were chosen for lab testing, to serve as a blind test of the algorithms. The paper reports on the test results and the incorporation of the modified CI data and predicted hardness parameters into the Antamina block model.CITATION:Windle, S J, Kojovic, T and Sullivan, J, 2016. Use of a Modified Comminution Index to Predict Bond Work Index and SMC A*b at the Antamina Mine, Peru, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 153–160 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

Teleseismic travel time residuals measured on 600-1000 km seismic arrays across the Rio Grande and East African rifts provide evidence for upper mantle low velocity zones beneath each rift of velocity contrast 6%-8%. Refraction studies show thinning of the crust below the rift axes. Regional uplift which extends hundreds of km either side of the axes, is isostatically compensated by negative density contrast at depth. Since the refraction argues against compensation by thickened crust, compensation in the upper mantle low velocity zones is suggested. Temperature effects alone can not explain the reduced velocities. Generation of a few percent of partial melt is the most probable source of the reduction. A passive extensional mechanism is investigated for the Rio Grande rift in which hot asthenosphere intrudes the lithosphere raising its temperature and generating moderate melting. It requires less than 1% extension to explain the melting but a prodigious 26% to raise the temperature from a pre-rifting continental geotherm to the solidus. Geological estimates find that extension is less than 10% over the uplift zone. Such a mechanism is possible only if the prerifting lower lithosphere geotherm lies closer to the solidus than that of stable continent. This is supported by the observed high heat flow in the Rio Grande rift uplift region which, given the long time constant for thermal diffusion, reflects elevated temperatures at depth well in advance of the onset of rifting.

Jan 1, 1987

By C J. Greet

Oil can enter a flotation circuit from a number of sources (for example, from mining equipment, oil leaks from the grinding equipment and coatings on the grinding media, but to name a few). Folklore generally states that any oil that contaminates the ore entering the flotation circuit is considered to have a negative impact on flotation. That is, a loss in concentrate grade and recovery.This represents a dilemma for some grinding media suppliers, who use a variety of quenching medium (air, polymer, oil or water) to achieve the desired physical properties of the ball. In the case of high chrome grinding media it is necessary, in some instances, to quench in oil to give the ball the right degree of toughness, which invariably leads to these balls having a thin film of oil on their surface. Once the grinding media arrives on site and site personnel recognise that the balls are “covered” in oil, they generally insist that the oil will have a deleterious impact on flotation performance.Obviously, any supplier “worth their salt” would take remedial action at the point of manufacture to minimise this problem. However, does quenching oil actually present a significant “threat” to the flotation process? This paper provides both laboratory and plant data describing the effect quenching oil has on the flotation of copper sulphide ore, with surprising results!

Aug 8, 2011

By K Blay, C McCamley, P Petrucci

The Newmont Boddington Gold (NBG) processing plant was designed for 35Mt/y with ball mills expected to deliver a combined new mill feed rate of 4837 tonnes/hr. Since beginning commercial production in late 2009, the plant has steadily increased throughput to meet design capacity in 2014 and reached 37 Mt/y in 2015. Through improved efficiencies, changes to the milling circuit have taken place since commissioning to take the plant beyond its design to an actual throughput of 39.0 Mt in 2017 and a budgeted throughput of 39.4 Mt/y this year.The NBG milling circuit has four parallel ball mills, each consisting of a 7.9 x 13.4 m ball mill with twin 7.5 MW fixed speed motors in closed circuit with twelve 650 mm cyclones. Each mill is fed by two wet screens with the undersize gravitating to a mill discharge hopper where it is combined with the ball mill discharge and pumped to hydrocyclones for classification. The cyclone underflow is re-ground to a target P80 of 150 µm.This paper will focus on process improvements made to the NBG milling circuit which include cyclone reconfiguration, fine screen panel redesign, implementation of an expert control system, mill power draw increase and grinding media changes to take NBG beyond its design throughput.CITATION:McCamley, C, Petrucci, P and Blay, K, 2018. Going beyond design at Newmont Boddington Gold, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 497–508 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

During operations, mining and metallurgical processes may generate effluents such as tailings water, acid mine drainage (AMD) and seepage and process acid streams. Depending on the type of ore and the metallurgical process, these effluents may contain one or more toxic compounds (eg acidity or alkalinity, cyanide, ammonia and/or nitrate, heavy metals, total suspended solids (TSS), sulfate) in elevated concentrations requiring treatment before their discharge to the environment or recycle/reuse in the process. Natural oxidation of sulfide minerals present in mining wastes (eg tailings and waste rock) at mining sites may generate AMD, which is characterised as a low pH, high acidity effluent containing heavy metals and sulfate. If generation of AMD cannot be controlled and/or prevented, AMD needs to be collected and treated for neutralisation of acidity and reduction of metals and TSS to meet regulated water quality standards. It is important to note that some of these compounds may persist in run-off from mine sites, even after the mine and processing facilities are decommissioned. Treatment of mining and metallurgical process effluents can be accomplished by means of various physical, chemical and/or biological methods. The mode of process application may vary from the use of either specifically designed, controlled and automated facilities or passive systems. Lime neutralisation and precipitation is the most common method used in the mining industry to treat AMD. To reduce the problems associated with disposal and long-term storage of the resulting sludge, the use of a high-density sludge process (HDS) has become a preferred option. The use of other chemical reagents, waste or by-products from other industries, and biological sulfate reduction methods can also be considered as viable options for site-specific situations. Recently, several passive treatment systems have been designed and successfully operated, even in the cold North American climate. This paper will discuss available options and provide insights for selecting a suitable method for a given situation using case studies from projects conducted by Golder Associates around the world over the last decade.

Jan 1, 2006

The state of sampling practice in South African minerals industry must be appreciated in the context of the changes that the country has recently lived through. These include the entrepreneurship and investment in local mineral developments, the 'unbundling of mineral assets', the rising foreign control of South Africa's mineral assets, developments in the regulatory environment, and the training that has come to the industry through international experts. In terms of their financial contribution the five most important commodities in the South African mining industry include gold, platinum, non-ferrous metals, ferrous metals, and coal. International Organization for Standardization (ISO) standards form the basis for international trade in two of these commodities and have had a steadying influence on sampling practice over the years. The contribution of the minerals industry to the economic well-being of South Africa and the strong financial links between good sampling practice and minerals marketing, has acted as a driver for improved sampling practice. The state of sampling practice at mining operations of the five main commodities was found to be quite widely divergent with 'pockets of sampling excellence' in each of the commodities. The stages of mineral development at mines for each of the commodities have been described in terms of the sampling sites, sampling mechanisms, and associated problems at different stages of mineral production from exploration, through face sampling, blasthole sampling, and in-mine grade control, ore processing and handling, metallurgical subsampling, process subsampling, and subsampling in the laboratory. In each case the principal errors were identified and their potential impact on value erosion was estimated. In the final analysis it is evident that the greatest problems arise in the early stage of mineral development, and that ferrous metals and coal are particularly susceptible to loss of value through poor sampling practice. Several examples of value lost through poor sampling at the marketing stage that arise from breaching contract specifications, either in terms of grade or sizing, are described. The conclusion is that larger companies with larger ore deposits and greater human, financial, and capital resources are probably more compliant with 'best sampling practice' than smaller companies. Finally the message that equipment suppliers are sending is that business is booming and the awakened awareness of the issues around sampling practice are translating into rands and cents spent on improved sampling equipment.

Mar 1, 2010

By E Nye and T Schroeter, B Muir, M Kitson, M Gonzalez, D Mares

The single track North Strathfield Rail Underpass (NSRU) consists of a dive structure either end of a 148 m long driven tunnel skewed under three live railway tracks. The tunnel is 8 m high, 9 m wide, with a horseshoe profile, excavated by full face using a road header. Ground cover varied between 2.5 m to 3.5 m. Settlements were 5 mm to 15 mm (the latter due to a dyke). A one pass synthetic fibre reinforced shotcrete lining was installed (no lattice girders or steel sets were used). A system of automated robotic total stations was used to provide real time monitoring of the rail track and associated ground formation. No disruption to train services occurred.CITATION:Gonzalez, M, Kitson, M, Mares, D, Muir, B, Nye, E and Schroeter, T, 2014. The North Strathfield Rail Underpass – driven tunnel design and construction, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 369–374 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By J P. Evert

Didipio gold-copper mine operation is situated in the island of Luzon, approximately 270 km north of Manila in the Philippines, in an area of high seasonal rainfall. The hydrogeological water flow model implied that there would be high connectivity between regional structures and underground operations. This model predicted that underground mine groundwater inflows were expected to quickly rise as the decline progressed to a peak of 510 L/s. Designing a capital pump station to deal with 510 L/s has its own challenges, however developing the decline down to the required level, always dealing with 300 L/s of water and constructing the pump station is extremely challenging and required a robust water management plan and mine design. When dealing with expected high volumes of water, underground mine design and scheduling plays a key role in protecting electrical infrastructure, equipment, secondary pumps, and the decline from flooding. A good drainage system and controlled dewatering plan is essential for safety and progress. This paper details the dewatering techniques and mine designs required to accomplish decline development with high water inflows as used in the Didipio project. It will describe the learnings and outcomes that are achievable with a flexible design, as new structures are mapped, and water intersections are increased. It also highlights the potential for adaptability in mine planning to provide evolving improvements or to evade problems that are expected from the constant reconciliation of data recorded during development.

Mar 29, 2023

By Z Li, Z Yan, T Htet, S Zhang

During the pyrometallurgical processes, a substantial quantity of high-temperature ironmaking and steelmaking slags, generated at temperatures ranging from 1400 to 1600°C, is wasted, as the heat contained in these slags is released into the environment during the tapping process without effective utilisation. On the other hand, a significant amount of energy is required to reheat the cold materials for the manufacturing of glass and mineral-wool, often necessitating the addition of high-silica materials to facilitate the production process. In this study, an innovative approach is presented to harness the heat present in molten metallurgical slags to directly produce new raw materials for glass and mineral-wool manufacturing while simultaneously reducing energy consumption and mitigating CO2 emissions. The theoretical amount of waste glass that can be effectively added in the process has been estimated via thermodynamic calculation. Experimental assessments were conducted to examine the impact of high-silica waste materials on the dissolution, melting and fluidity. Potential recipes for glass and mineral-wool manufacturing were suggested and an assessment of the energy savings, and reduction in CO2 emissions with manufacturing of glass and mineral-wool using this innovative approach were included. It was determined that the processes could lead to a reduction of over 26 kg of CO2 emissions per 100 kg of new material used, primarily due to the utilisation of heat from slag and the accelerated smelting process.

Aug 21, 2024

By R Domotor

Brisbane’s Airport Link is Australia’s largest road infrastructure project, worth a total value of A$4.8 billion. The project is using surface and underground blasting to excavate hard volcanic rock, Brisbane Tuff. This paper tells the story of the most challenging and difficult blast of the whole project: the removal of a remnant pillar of rock (approximately 2250 m3) next to a major arterial road and within 100 m of existing infrastructure including a number of heritage listed buildings, residences and privately owned sensitive receivers. The pillar consisted of a hard rock wall (Brisbane Tuff) between 2 m and 6 m thick, 15 m high and 35 m wide; with in situ precast concrete piles embedded within 1 m of the boundary of the pillar. Orica Australia Pty Limited was contracted by Thiess John Holland, to perform the work in this area, including design, modelling, drilling and loading of the explosives, as well as blast clearance and shotfiring. Access to the area was limited so all explosives and equipment, including the 20 t drill rig, had to be lifted in and out by crane. Due to the nature of the blast, with infrastructure 5 m directly in front of the 15 m high face, there was only ever going to be one chance to get this blast right. This was an extremely complex blast which required the use of a number of different types of packaged explosives, as well as special timing techniques only made possible by using electronic initiating systems. This type of blast is high risk, and is more typical of a building demolition in the urban environment. The blast was fired on the 25 September 2010, and was highly successful. The environmental results for vibration and overpressure were well under the imposed limits, and the embedded concrete piles remained undamaged.

Nov 8, 2011

By P W. Wypych, D Curry, A P. Grima

The market has become highly competitive for engineering and equipment vendors, who are challenged to reduce costs while improving efficiency and productivity of mine operations through plant improvements and expansions. Although conveyor transfer systems account for a small percentage of the infrastructure cost of a mine, they form an integral part of the process supply chain. Malfunctions or suboptimal performance can result in substantial financial cost from delayed start-up, unscheduled downtime, reduced throughput and increased maintenance costs.Discrete element modelling (DEM) is a powerful simulation method used to virtually prototype and test the performance of transfer equipment throughout a design cycle. When developed and applied correctly, DEM can provide insight into performance that exceeds the traditional analytical methods, especially when dealing with complex ore properties, behaviour and/or situations.Using case studies sourced from the authors’ recent research and industrial project work, this paper will address the industry goal to increase efficiency and productivity as well as the methods available to the engineers responsible for delivering designs that meet the aims of this strategic approach.The main focus of the paper will be the new calibration technology, which has been developed by the authors to generate DEM material models that are linked to real-world properties and flow behaviours via unique dynamic testing and innovative parameter calibration methods. These calibrated DEM material models can be deployed by engineers into their existing workflows, whether it be for feasibility studies, concept or final design, plant troubleshooting or optimisation.This new technology allows engineers to gain greater insight than that provided by traditional approaches to the design of transfer chutes and other process equipment and also allows informed design decisions to be made that meet industry efficiency and productivity requirements.CITATION:Grima, A P, Curry, D and Wypych, P W, 2015. New discrete element modelling calibration technology to facilitate the increased efficiency of ore handling and processing operations, in Proceedings Iron Ore 2015, pp 449–464 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By C Boyle

Brockman 2 mine is located in the Pilbara of Western Australia and is operated by Rio Tinto Iron Ore. Mineralisation is hosted by synclines where there is structural complexity to focus fluid flow. Mineralisation is hosted by the Brockman Iron Formation. Mining is on 10 m benches and blastholes spaced at 6 - 8 m apart are geologically logged, sampled by shovel cuts, and assayed using X-ray fluorescence for ten chemical variables. Blast blocks are digitised by mine geologists to assign destinations of material within blasts. Resource evaluation drilling is on a spacing of 50 m × 50 m across known mineralisation and consists of recent reverse circulation drilling and older open hole percussion drilling. Sampling of resource evaluation drilling is by rotary splitters or riffle splitters, and assaying is by X-ray fluorescence for ten chemical variables. Ordinary kriging of resource evaluation produces a long-term resource model. This study examines whether mine planning would be improved by using a blasthole estimate to extrapolate grades into deeper benches and merging the blasthole estimate with the long-term model made using resource evaluation drilling. The two estimates are merged into one model using an inverse weighting based on kriging variance. However, reconciliation results in a test bench show the original estimate made using resource evaluation drilling more closely matches mine geology block outs than does the merged model. This is due to a local trend of more high grade and higher iron grades of high grade in the area. The blasthole estimate of deeper benches must use extrapolation and it is diffi cult to take local trends into account. In contrast, the estimation using resource evaluation drilling is mainly interpolation and is better able to handle local trends.

Jul 11, 2011