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By L Nagy, K P. Juhasz

The authors were engaged to optimise a traditional rebar cage reinforced concrete segmental lining by means of finite element analysis (FEA) using macro synthetic fibres for the Shanghai metro extension. The aim of this study was to reduce or entirely replace the original steel reinforcement of the segmental lining, in order to make the precast production process faster and more economic. The outer diameter of the tunnel was 6200 mm, the thickness of the segments was 350 mm.The numerical calculations were performed by Atena Finite Element software, which is based on the combination of Menétrey-William and Rankine failure surfaces on the compression and tension sides respectively. The effect of the macro synthetic fibres was modelled as tension stiffening on the tension surface.A one-to-one full scale model of an assembled tunnel ring using the original reinforcement cages was tested at Tongji University in Shanghai, July 2013. The ring was tested to differing load levels where load and displacement were measured until failure. The author’s first step was to calculate the real displacement characteristics of the original reinforced concrete (RC) ring, then calculate the numerically modelled version, so as to compare them. The material parameters of the concrete and rebar used had been determined through basic material tests conducted at the Tongji University. (Bi, Liu and Wang, in press).The numerical modelling undertaken has shown good correlation with the full-scale physical test results. Optimisation of the lining reinforcement was achieved through the addition of fibres, resulting in a substantial reduction of the steel rebar cages. Several results have been computed with the numerical model using different dosages of macro synthetic fibres, showing that the mass of steel reinforcement could be reduced by 50 and 75 per cent respectively.CITATION:Juhasz, K P, Nagy, L and Winterberg, R, 2014. Full-round numerical modelling of a macro synthetic fibre reinforced tunnel boring machine tunnel in the Shanghai Metro extension, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 477–484 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By D Kent

The introduction of digital technologies into the underground mining industry, in both coal and hard rock mining, has enabled many high bandwidth applications to be adopted by mines.Digital networks based on 802.11 b/g/n open Wi-Fi standards allow for many applications to be run over a single communication backbone. One important application has been tracking personnel and equipment via RFID tags. This tracking application has in turn formed the basis of a Proximity Detection System (PDS) or Collision Avoidance Systems (CAS). The paper discusses the growth in digital technology as the communication backbone in underground mines which has allowed the ‘convergence of technologies’ that has been occurring in the general business world to be available to underground mine operators. Then the paper will focus on the use of the technology in the increasingly important are of risk control around mobile plant underground. The specific use of digital devices for proximity detection, in both hard rock and coal mines, to provide a system that can deliver an additional level of control to the risks associated with people-vehicle interactions underground is discussed. The initial implementation of PDS in the hard rock mining environment is based on two zones of detection, required for large and relatively high speed vehicles. Information will include:•the principles of the underlying technology,•installation learnings and effectiveness, and•change management methodology and issues.The most recent development to integrate Mine Site Technologies (MST) PDS with Frederick Mining Controls’ HazardAvert® System to extend the overall Proximity System’s functionality in hard rock mines and for use in coal mines is overviewed.

Mar 21, 2011

By G Deans, M Longbottom

OZ Minerals’ Carrapateena mine is one of Australia’s newest ‘greenfield’ mining deposits. It will be a 4.25 Mtpa sub level cave underground operation, with an estimated mine life of 20 years. The integration of stakeholder values to inform project development influenced the social and environmental outcomes. A Native Title Mining agreement was developed in 12 months. Project primary approval was obtained 12 months from submission, with achievable licence conditions and one public comment. The project moved from a Pre-feasibility Study in 2016 to construction in 2018. Following recent international dam failures, the Tailings Storage Facility (TSF) was a focus for Government approvals and stakeholder engagement. Significant effort was made into understanding the science around potential effects, impacts and risks. A leading practice Impact Assessment Framework that identified Sources, Pathways and Receptors was applied. A process of failure mode identification and layers of protection analysis was undertaken for robust design controls at each stage, while simultaneously transitioning between downstream and upstream discharge arrangements. Participatory selection of the TSF site and design layout was critical in managing project costs and environmental constraints, and in incorporating cultural heritage constraints and technical risks.

Jul 1, 2021

By L Sandery, S Light

Within 22 months of commencing decline development, the Prominent Hill Ankata Underground Project achieved its full production rate of 1.2 Mt/a.In 2010 construction of the Ankata Underground Project was approved. Decline development commenced in November 2010 and the turnout for the first sublevel was reached by August 2011. The first stoping ore was produced in the first quarter of 2012 and production was successfully ramped up to full production during the third quarter of 2012.Diamond drilling commenced in October 2011 and was conducted concurrently with the underground development. This presented challenges as mining and production targets had to be balanced with underground exploration activities. To achieve production on schedule, without adversely affecting the diamond drilling program and future development, meticulous and adaptive planning techniques were required. This included involvement from engineers, geologists, underground operators and underground diamond drillers.The granularity of these planning techniques allowed the management and prioritisation of development and diamond drilling down to an almost hourly basis. A constant flow of information from drill assay results was fed back into the planning systems. This resulted in a constantly evolving mine plan as the orebody was further refined. High priority areas were identified and targeted to allow continued development and a successful rapid ramp up to full production.CITATION:Sandery, L and Light, S, 2014. Managing the diamond drilling interactions in commissioning the Ankata underground mine, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 75–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By L Mollison, K W. Mills, N R. P Baczynski, M F. Lee, I A. de Bruyn

This is the first of two papers concerned with rock stress inputs to various mine design issues at the large Ok Tedi open pit mine in Papua New Guinea. The companion paper (also published at this conference) is ‘The Application of Rock Stress Inputs to Stability Assessments at Ok Tedi Mine, Papua New Guinea’ (de Bruyn et al, 2014).Stresses are a required input for numerical modelling of mine design issues. However, for some operations, like the very large Ok Tedi open pit mine in remote rugged mountainous terrain, direct and representative measurement of rock stresses can be technically difficult and expensive. In such situations, development of an appropriate and sufficient understanding of rock stresses can be challenging.This was addressed for Ok Tedi by considering the following:The tectonic and regional geologic setting of the mine.Results from three different programs of rock stress measurement over 19 years, including hydraulic fracturing (1991), acoustic emission (2007) and overcoring (2010). Some interesting results of the overcoring work are discussed. It was done in a 4 km long drainage tunnel, which intersected a thick monzodiorite intrusive that has metamorphosed contacts to host contact Ieru Formation siltstones; anomalously low horizontal stresses were measured within the monzodiorite.Compilation of rock stress measurements from other New Guinea mines and prospects, both in Papua New Guinea and Indonesian West Papua.Comparisons between the variable Ok Tedi rock stresses and similar data from other porphyry copper deposits.CITATION:Lee, M F, Baczynski, N R P, Mills, K W, de Bruyn, I A and Mollison, L, 2014. Rock stresses at Ok Tedi, Papua New Guinea, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 337–346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By S Williams, N McBride

The aim of these analyses was to utilise the latest available production information for the Wandoo operation to determine the optimal blasting parameters, costing information and predicted results (fragmentation, muckpile shape and vibration). Much of the data used as input was made available from the information gathered during the excavation of the test pits during 1995. As with any æplanning stageÆ analyses, many assumptions were required to fill gaps in the available data. The calibration of computer blasting models was conducted using data from the last of the test pit blasts (this blast was carried out in material that closely resembled rock expected to constitute the bulk of the base case design pit). This calibration was refined using observation and experience based judgements to extend the accuracy of the predictions as far as possible. All the simulations were performed assuming that the blastholes will be wet (as instructed by BGM). This has consequently determined that the appropriate explosive for the simulations and the actual blasting will be a pumped emulsion/ANFO blend. The following blast design parameters were derived by determining a likely range of powder factor (from other similar scale gold mines) with a median value of 0.62 kg/m 3 being the powder factor arrived at through the field optimisation process conducted during the test pit excavation. The total swell/displacement percentage (volume after blast/volume before blast) largely determines the diggability of a well fragmented muckpile. Consequently where fragmentation is good any reduction of total swell will probably reduce diggabilty. Any reduction of diggability can and should be traded off against increased gold recovery. In most gold mines, diggabilty will be substantially compromised at the balance which produces the most profit. When these considerations are combined with the cost to drill and blast material, processing costs and the achievement of æacceptableÆ diggibility, the analysis becomes extremely complex and qualitative. Many trends are evident including:the relationship between powder factor (for each blast design) and maximum forward displacement (throw), see Figure 1; and the relationship between powder factor (for each blast design) and drill and blast cost per BCM, see Figure 2. The following blast designs are matched to each of three ore-tonnage alternatives (as supplied by BGM) (Table 1). They are all based on powder factor of 0.62 kg/BCM and are considered optimum from a mining æpoint of viewÆ. The costing of each design includes drilling, explosives and labour cost to load, stem and tie-in holes. Using the available rock data and relying heavily on the wall exposures in the test pit(s), it is the opinion of the author that between 20 per cent to 40 per cent of the final walls excavated in the Wandoo pit would be likely to have the angle between the dominant foliation and the wall plane that is well suited to presplitting and be cost-effectively served by presplit technique. The drilling cost for 125 mm blasthole is about $11.40 per drilled metre and the cost of 40 mm presplit explosive is about $140 per 25 kg (17 metre) case. This implies that the cost to drill and blast presplit on the above parameters would be about $10.90 per square metre of presplit face. The remaining wall area would be most cost-effectively delineated using modified production blasting techniques. This requires the use of modified parameters such as smaller hole diameters, smaller spacing/ burden, higher powder factor, free face firing, less rows per blast and longer delays. These altered blast parameters would usually be applied uniformly across the entire blast fired adjacent to the wall and this ætrimÆ blast would relieve burden away from the wall, into the pit. In simplest terms, this method relies upon maximised burden relief to minimise blast energy applied to the wall. It is only applicable where the material to be blasted is waste since the throw achieved is inconsistent with ore dilution control. The largest charge weight per hole for these analyses is 360 kg and the nearest domestic structure to the proposed Wandoo pit is about 6100 metres distant. From these parameters and assuming a worst case example of rock controlled site factor, the predicted ground vibration is 0.5 mm/sec that is about five per cent of the lower limit set down in AS 2187 part two (1993). This suggests that for the current location of neighbours, ground vibration will not be an issue for the Wandoo operation.

Jan 1, 1999

By C Zhang, I Canbulat, G Fan, D Zhang, C Wang

A clear understanding of the intensity of coal and rock burst is the basis for future research on burst mechanism and control. There has been a wide variety in the description of coal and rock burst damage at different countries using multi-methods, which makes the common understanding even more challenging. Therefore, this paper presents a broad review on the quantifications of intensity of coal and rock burst and seismic risk around the world, considering critical factors including seismic energy, magnitude, peak particle velocity and ejection velocity. It is found that the seismic energy of coal and rock burst can widely range from 0.002 MJ to 60000 MJ, with equivalent Richter magnitude from -1 to 4. The daily seismic energies can be used for seismic risk potential assessment, with energy levels from 0.1 KJ to 10 MJ, which is much lower than the burst sources. The magnitude of the seismic events can be also estimated based on the weight of damaged coal mass and human senses of vibration and sound. For the seismic intensity represented by peak particle velocity (ppv), it keeps constant within fault radius and attenuates with a speed of 1/r4 and 1/r in near and far field respectively, thus it is possible for a small seismic event to induce considerable ppv causing severe damage if the epicentral distance is small enough. There has not been a strong correlation between the ejection velocity and ppv, as seismic energy is only one of the energy sources that contribute to the kinetic energy of burst damage. CITATION:Wang, C, Zhang, C, Canbulat, I, Zhang, D and Fan, G, 2018. Intensity quantification of coal and rock burst risk – a review, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 223–233 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By G Zhao, S Hapugoda, E R. Ramanaidou, P Hapugoda, Y Jin, G O’Brien

In 2021 the ports of Port Hedland and Dampier in the Pilbara Region of Western Australia handled 900 Mt of iron ore. This ore was produced in the Hamersley’s mines and transported by trains to the ports for subsequent export. Dust, which is generally considered to be particles less than 100 μm in diameter, is generated at all steps in the supply chain. Whilst all dust may have potential impacts on human health and mangroves and buildings a proportion of the dust is classed as respirable (PM10) dust, which consists of particles <10 μm in diameter. In 2021, in response to the community concern with iron ore dust, CSIRO commissioned an internal study to characterise and benchmark the dustiness of the different ores and to develop targeted strategies to minimise dust impacts, without affecting other iron properties, such as stickiness during transportation. A specific concern is that that the dust in the PM10 fraction may contain significant amounts of particulates, such as free silicates which may have health implications for the workers and residents. This study provided detailed mineral and chemical characterisation of the dust generated from the railed fine ore products for five generic Australian ore types: Australian Channel iron Deposit (ACID), Australian Brockman (AB), Australian Marra Mamba (AMM), Australian Pilbara (AP) and Australian magnetite (AM). The dust from these fine ore products were compared to that generated from a sample of Brazilian Hematite (BH) type ore fines. The ores were evaluated for their physical, chemical and mineralogy properties, dust generating potential and understandings of the relationship between the dustiness of iron ores and their physiochemical properties. The size distributions of the railed fine ore products were determined and a suite of analyses were conducted on subsamples of total (-106 μm) and fine (-38 μm) dust. For all the ores, the total dust fraction contains less Fe and more contaminants (SiO2 and Al2O3) than did the bulk ore. The fine dust fraction contained even less Fe and more contaminants (SiO2 and Al2O3) than the total dust fraction. This suggests that the iron ore dust contains more clay and potentially free silica than does the bulk ore. These findings were supported by optical and Scanning electron microscopy analyses of the samples. Dustiness measurements were made for each of the different ores (-106 μm) to investigate the relationship of dustiness of various iron ores with their physiochemical properties and assess their responses to dust suppression by the application of water sprays.

Sep 18, 2023

By D Capstick, M B. Ebell

This paper describes the test work, process design, commissioning and operation of a processing system at the Ergo gold operation that improves the extraction efficiency from gold tailings material. The improvement in recovery is derived from the separation of the gold contained within the sulfides of the tailings material and a dedicated process stream to recover that gold.The sulfides are separated by means of a flotation circuit and that resulting concentrate is subjected to a regrind of below 20 ¦m to enable a greater liberation of the gold. The ultra-fine material is then subjected to a dedicated leach circuit to recover the now exposed gold particles.The case study is an example of the challenges of introducing new technology and methodologies to a well-established operation and thereby attaining improved efficiencies and tangible business benefits.CITATION:Ebell, M B and Capstick, D, 2013. Improving extraction efficiency from Witwatersrand gold tailings using flotation and ultra-fine grinding of concentrates, in Proceedings World Gold 2013 , pp 301-306 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By M Z. Abzalov

Drilling mineral sand deposits has specific challenges, which are different from drilling hard rock deposits: Drilled sequences are represented by non-consolidated free-flowing sands to semi-consolidated clayey sands and indurated layers. Valuable heavy minerals (ilmenite, rutile, zircon, leucoxene) have an average density of 4.6&nbsp;g/cm3, which is significantly heavier than the hosting sand matrix; mainly represented by quartz (density = 2.6 g/cm3). The large difference in the mineral densities can result in sample segregation in the drilling rods and capturing devices causing biased composition of the recovered samples. The drilled strata can contain beds of consolidated sediments, hard pan lenses and concretions. Therefore, chosen drilling equipment should be flexible and permit a switch from drilling the free-flowing sands to hard rock drilling. Thickness of the sand hosted mineralisation varies from several metres to more than 170 m. Mineralisation is distributed above and below the water table. Evaluation of the mineral sands deposits is based on hundreds of drill holes and many thousands of samples, therefore drilling methods should be fast and cost effective. The drilling methods commonly used for mineral sand deposit evaluation, include aircore, triple tube diamond and sonic; including its variants, such as vibrocore drilling technique. The ability of the studied drilling techniques to properly address the above listed challenges in mineral sand deposits, whilst maximising the quality of the obtained samples has been compared in three deposits: Corridor Sands (Mozambique), Richards Bay (Republic of South Africa) and Fort-Dauphin (Madagascar).This study has shown that aircore samples tend to be negatively grade biased, underestimating the heavy minerals content, in particular when drilled intervals are located below the water table. Triple tube diamond core method can produce non-biased samples. However, results can be marred by incorrectly chosen drilling mud. Sonic drilling is a relatively new technique based on a high frequency vibratory technology. It is the only production drilling technique that allows a continuous relatively undisturbed sample of unlithified sands to be obtained. The main limitations of this technology preventing its wider use for developing mineral sand resources are the relatively high drilling costs, in particular when the depth of drilling exceeds 100 m, and speed of drilling advance.

Oct 5, 2011

A belt of serpentinized ultrabasic rocks intrudes a moderately folded geosynclinal sequence of fine to coarse sediments, acid, intermediate, and basic volcanics as well as a batholithic mass of granitic rocks. The ultrabasic body contains small included masses of melanocratic and leucocratic rocks, together with chromium, copper, zinc, and nickel mineralization.

Jan 1, 1969

By D R. Anstey

The mining of magnetite iron ore in Western Australia will generate large volumes of waste rock and tailings over many decades. The need to dispose of these materials will result in massive waste landforms that will require significant planning and management. The formation of comparable man-made landforms is relatively common, as exemplified through past practice in gold and iron ore (haematite) mining. Unfortunately, the performance of these landforms, with respect to long-term stability (erosion resistance), the release of low pH seepage water and aesthetic impact, has commonly been disappointing and environmental legacies have been created as a result. Lessons that have been learnt from past, large mining operations indicate that there is a need to rethink the methods of waste disposal and landform development applied to magnetite mining. The environmental compliance criteria applied to magnetite mines for the storage of tailings and waste typically include minimising dust generation (particularly as the tailings and mine waste may contain asbestiform minerals), control of silt, minimising visual intrusion and management of potentially acid forming materials. In addition, the climate of Western Australia and the paucity of both surface and groundwater in the vicinity of the magnetite mines frequently necessitate water consumption to be minimised. This paper discusses the potential to co-mingle magnetite mining waste streams in a variety of ways to concomitantly satisfy the environmental compliance criteria and the operational requirements of the mine. These methods include co-mingling of coarse tailings and waste through dry-stacking, deposition of tailings as a paste, co-disposing of all wastes to form an integrated landform and the co-mingling of all waste streams to produce PasteRockTM (a blend of tailings paste and crushed waste rock). The paper demonstrates how these techniques can be applied to the magnetite mining industry to provide better outcomes than might be achieved using more conventional techniques, currently employed in large-scale mining operations.

Jan 1, 2009

By T Rohde, P Defferrard

In 2010 a store and release cover (the cover) was constructed on the south waste rock dump (SWRD) at Century mine. This also included aerial seeding of province native trees and shrub seeds. The purpose of the cover is to reduce percolation into the potentially acid-forming (PAF) waste rock by maintaining a compacted reduced permeability layer (RPL) at near-saturated conditions. This is achieved by overlaying the RPL with a 1.5 to 2 m thickness of soil-mulch. The soil-mulch has a hummocky final surface that captures rainfall, so it does not runoff, allowing it in part to infiltrate, with excess water removed by evaporation and transpiration. The RPL is the trafficked surface of the SWRD.The unsaturated behaviour of the cover is being monitored by instrumentation including volumetric water content and matric suction sensors and a weather station capable of estimating evapotranspiration. The instrumentation allows for direct measurement of infiltration into the cover, storage of rainfall, percolation through the base of the cover and in situ soil water characteristic curves (SWCC).The key functions used to describe the unsaturated behaviour of the cover materials is the SWCC and the unsaturated hydraulic conductivity function. The SWCC is a plot of soil water versus soil suction. It provides the loci of moisture states of a soil from the saturated to the dry state.The paper presents the results of five years of monitoring. It shows that total infiltration into the top of the SWRD was about 1.6 – 3.7% of cumulative rainfall over five years, with most of the infiltration going into storage within the cover. Runoff from the top of the dump is not allowed therefore, the remaining 95% of the total rainfall was lost to evaporation or as lateral flow when infiltration reached the RPL. The paper presents some simple analyses of the wetting by rainfall infiltration of the cover, leading to breakthrough at the base. Field data are used to support the analyses.Presentation of the SWRD water balance is also included in the paper using SVFLUX™GE which is a finite element model that simulates water transport through a saturated or unsaturated medium.CITATION:Defferrard, P and Rohde, T, 2018. Five years of cover performance monitoring and modelling for a store and release cover at Century Mine, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 179–189 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By R E. McIvor, K M. Bartholomew

Classification system efficiency (CSE) is a simple, powerful metric that provides a comprehensive measure of classification system performance. CSE directly quantifies the amount of coarse solids in the mill, and as a result, also directly quantifies the percentage of mill power being used effectively. In this manner, it is an effective, practical grinding energy efficiency metric.Three independent variables drive CSE: circulating load ratio, sharpness of classification, and classifier bypass. Due to practical downstream constrains on per cent solids, improvements realised by increasing circulating load reach diminishing returns as sharpness of classification and bypass deteriorate in the most commonly used classification device, the hydrocyclone. This combination of effects leads to the use of CSE, and its relationship to operational economics, as an objective circuit optimisation criterion.Its simplicity in measurement makes CSE a useful tool for the plant metallurgist, and it is not subject to a great amount of experimental error. CSE provides the plant operator a fast, simple, and effective means to evaluate the performance of the plant classification system. Improvements in CSE relate directly to circuit throughput and energy efficiency. This paper, through description and plant case studies demonstrates the power and utility of this emerging grinding system optimisation metric.CITATION:Bartholomew, K M and McIvor, R E, 2013. Classification system efficiency - a comprehensive closed-circuit grinding optimisation metric, in Proceedings World Gold 2013 , pp 389-394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By T Leidich, M Van Zyl, H Lacy

Mining ‘as usual’, until the most recent decades has resulted in limited landform planning and a general lack of mine waste landform design. Material characterisation, mine planning and dedicated professionals undertaking these tasks were rarely available or in place at the majority of mines. This has led to landform instability, erosion, sediment and poor quality water emanating from mine landforms. In many cases rehabilitation and reclamation failed and these sites have ‘landform features’ that are difficult to relinquish or leave and have little or no apparent land use. In many cases mined landscapes around the world have resulted in a less functional and degraded environment, with deleterious impacts on surrounding ecosystems.This situation is now slowly being addressed, as global companies, academics and practitioners and their organisations have started to exploit the ideas from an integration of earth sciences and mining through the application of planning software dedicated to the design of landforms.This development has had its genesis primarily in the United States. We suggest that process has been driven, in recent decades, by the application of resources in response to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), (USA Congress 11 December 1980) and other mine reclamation legislation enacted by federal and states regulators in the USA. The combining impact has seen a huge transfer of capital back from the public purse and ‘potentially responsible parties’, into abandoned mines to affect control, remediation, and reclamation/rehabilitation of those mines.Given this investment in rehabilitation and reclamation, people engaging in the business of landform planning have had the opportunity to address landform reclamation of historic and active sites. The skills of engineers and scientists with improved technology, waste rock characterisation and modelling tools have been combined resulting in the evolution of landform design and in mine planning of active mines. This has delivered cost-effective, sustainable mine closure designs for over 30 years. Integration of mine design with an understanding of geomorphic principals and the natural landscape, coupled with waste and soil characterisation, yield a positive result. Recently work has been applied across large and small-scale projects by companies. As these processes develop, ideas and concepts are evolving that active mines, or mines in the early planning stages, could use to help reduce double handling, and in the long run reduce overall project and closure costs, more effectively attain the desired final land use, and enhance the industry’s reputation and licence to operate.CITATION:Leidich, T,?Lacy, H?and Van?Zyl,?M,?2014. Application of design concepts and engineering controls necessary to deliver well-designed and rehabilitated landforms, in Proceedings Life-of-Mine 2014 , pp 55–66 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By T D. Jolly, L A. Balzan, A R. Harris, Z Bauk

"The availability of real-time data in any process control system is critical for effective management of that system. At MMG LXML Sepon Copper Operation in Lao PDR, controlling the copper grade of the feed to the leaching circuit is paramount for maximising both productivity and copper recovery. Since 2008, real-time analysis data has been available to the process engineers from the Geoscan on-belt analyser installed on the Copper Mill feed conveyor, and highly accurate results on copper grade have allowed the process engineers to strictly control blending to overcome the variability in plant feed grade. The availability of real-time analysis data is crucial, as effective sampling of this stream is both difficult and error-prone, being only a snapshot in time of highly variable ore stockpiles, as well as having significant laboratory turnaround delays. Periodic sampling is used to verify the Geoscan data as accurate. Since its installation, the copper result has been the most critical output of the Geoscan. In recent times, the process engineers have sought to utilise other results from the Geoscan to further improve and control the process. One measurement of particular interest involves the real-time measurement of calcium and magnesium as a gauge of ore feed gangue acid consumption. To satisfy this end, accurate measurement of calcium and magnesium is becoming increasingly more important and has been the subject of ongoing collaboration between Sepon and Scantech, the manufacturer of the Geoscan. This paper discusses this work, describing the calibration process and results obtained, while also providing a basis for Geoscan use in operations to enable enhanced process control for all potential Geoscan users.Citation:Balzan, L A, Jolly, T D, Harris, A R and Bauk, Z, 2016. Greater Use of Geoscan On-belt Analysis for Process Control at Sepon Copper Operation, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 231&ndash;238 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By D Frost, G Harbort, T Lipiec, N Deonarain

"The use of flotation columns has remained a contentious issue among mill operators. There are those who consider them an essential part of any mineral processing operation, while others consider them a necessary evil, which should only be installed if there is no alternative. Lastly, there are those who believe they should not be installed, no matter how great the perceived benefit.This paper provides an analysis of over 4000 installed flotation columns, contained in the Amec Foster Wheeler flotation database. Changing trends in column flotation use by type, commodity and geographical region are discussed. The effect of changing commodity prices and the China ‘phenomenon’ are reviewed. Special reference is made to the changing face of column flotation in Australia.Of note is the fact that after falling to a 20 year low in installed flotation column capacity in 2014, flotation columns during 2015 went through a resurgence in popularity. This resurgence was in direct contradiction to depressed metal prices and was driven by brownfield optimisations to reduce off-site costs, particularly in base metals. A case study is presented comparing the benefits of column flotation at high commodity prices with low commodity prices.Citation:Harbort, G, Deonarain, N, Frost, D, Lipiec, T and David, D, 2016. Changing Trends in Column Flotation Use - Their Impact for Australian Mill Operators, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 93&ndash;104 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By M R. Dehghan, H Mansouri, A Hakami, M A. Ebrahimi Farsangi, F Faramarzi

Today, it is accepted that rock fragmentation by blasting affects loading and hauling operations, and also directly influences on downstream processes such as crushing and grinding. In this research, the influence of rock fragmentation by blasting on the performance of three mills at Gol-e-Gohar iron ore mine No 1 was studied. Firstly, the fragmentation of conventional blast patterns in iron ore (5 &#215; 6 m) was studied using image analysis and the performances of three mills were monitored. Then, a new blast pattern (4 &#215; 5 m) was designed and nine blasts were carried out using this pattern. Increasing the powder factor form 1650 gr/m3 to 2480 gr/m3 by changing the blast pattern design showed that mill throughputs increase five per cent to 30 per cent for the new pattern.CITATION:Hakami, A, Mansouri, H, Ebrahimi Farsangi, M A, Dehghan, M R and Faramarzi, F, 2015. Study of the effect of blast pattern design on autogenous and semi-autogenous mill throughput at Gol-e-Gohar iron ore mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 315–320 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By J J. L du Plessis, S Viviers, G Ratner

Escalating electricity costs are one of the biggest operational cost drivers in mining. The trend to use high-powered auxiliary fans delivering increased airflow to meet the dilution requirements of diesel equipment, together with the reliance on ducted systems rather than traditional flow-through systems to ventilate areas, increases the overall energy requirements of ventilation systems. To manage and reduce electricity costs energy management systems can be implemented, inefficient operating units can be replaced and the operation of energy-consuming components of ventilation systems can be optimised.This paper describes the process followed to design and develop an energy-efficient axial flow auxiliary fan. The fan-targeted design was based on static pressure and volume flow rate requirements incorporating higher overall fan efficiencies. A brief overview of the results is given, including the aerodynamic design procedure using computational fluid dynamic (CFD) analysis. The mechanical design criteria used, including stress analysis on the rotor and designs to improve the vibration levels of the fan, are also presented. Through this study it was demonstrated that the aerodynamically designed rotors using profiled and twisted blades improve the total fan efficiency considerably when compared with some of the older-generation fans using cambered plates. The latter were typical in the mining sector in South Africa at the time of the study where average overall fan efficiencies of standard cambered fans less than 63 per cent and some of the older-generation cast aluminium blades have peak overall fan efficiencies of about 65 per cent. Peak overall fan efficiency of more than 80 per cent was achieved by using the described design and development process. Additional benefits are that the fans are quieter due to the better aerodynamic design and have a longer operating life due to reduced vibration levels.In conclusion, the use of CFD to develop fans to deliver the required volume flow at the required pressure allows quicker design turnaround time. It furthermore allows the ventilation engineer the option to specify a specific fan and is not limited to an off-the-shelf catalogue fan. It thus allows engineers to purchase a fit-for-purpose energy-efficient fan. The introduction of reliable fan control systems may, however, still result in the biggest cost benefit for underground mines.CITATION:du Plessis, J J L, Ratner, G and Viviers, S, 2015. Design and development of energy-efficient secondary axial flow fans, in Proceedings The Australian Mine Ventilation Conference, pp 337–344 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By C Jones

Ridgeway Deeps is a block cave (BC) located down dip of the operating Ridgeway sublevel cave (SLC) mine. The BC is located approximately 210 m vertically below the lowest SLC level and approximately 1100 m below surface. Due to the mine layout containing a number of common pieces of key infrastructure the activities of both were interlinked.When investigating project construction options for the BC, a number of potential risks were identified including a conflict of priorities between operational and project deliverables and the varying safety and work methods between an owner mining approach in the SLC and a potential contractor workforce in the BC. This led to a review of the construction philosophy and the opportunity to utilise the existing SLC workforce as the basis of all activities in the mine. It was identified that a number of synergies existed with the current SLC operators and mine supervision including common work practices and the opportunity to build on the unique SLC skills of the operators and supervisors which could then be used at other Newcrest caving mines.With the commitment to this philosophy of building on the existing SLC crews and supervision the number of employees reporting through the superintendent underground operations grew from 95 to 245. This increase led to a restructuring of the reporting and work requirements of the superintendent, foremen and shift bosses. In order for the foreman and shift bosses to focus on running the larger crew numbers for the full 12 hour shift the mine superintendent became a pseudo human resources manager taking over all non-mine focused activities including overtime allocation and work and behavioural performance management. In simple terms, ensuring there were competent bums on seats when and where required. As the additional workers were recruited to top up the existing employee numbers, their employment history was used to place them in the most suitable roles. For example, those with building industry experience were placed on the civil construction crews and those with a farming background were used as truck drivers, nippers or on the service crews. To cope with the increased number of new starters a number of key personnel were seconded from the crews into the training group to act as on shift trainers. This initially caused a reduction in mine performance as the main operators were reassigned but it proved a valid move as the time for new operators to reach acceptable levels was significantly reduced with safe operating standards being maintained. This paper discusses how the Ridgeway Deeps Project was delivered on time and under budget whilst at the same time retaining its position globally as an operation to be benchmarked against.

Mar 21, 2011