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Optimisation of the Advanced Automation System at Inmet Mining's PyhSsalmi Mine, Finland

Sep 13, 2010

By D R. Anstey

The growing demand for iron ore from Western Australia has led to an increased focus on the development of magnetite and lower grade iron ore deposits. The need to process and beneficiate the ore from these projects can result in the generation of significant quantities of iron ore tailings over the life of a project. Over the coming decades, the management of iron ore tailings will become a significant aspect of the mining landscape in Western Australia.The tailings generated from iron ore projects differ signifi cantly from other mineral tailings currently produced in Western Australia. Iron ore tailings are generated on a scale not matched by any other mineral process and can often contain asbestiform or potentially acid forming components. New iron ore projects are coming under increased environmental scrutiny because of their large scale operations and the sensitive environments in which they occur. This combination of factors creates some unique challenges for the management of tailings generated by iron ore mining in Western Australia.This paper presents the fi ndings of two studies conducted in recent years to overcome the challenges posed by iron ore tailings. The paper discusses the role of laboratory testing in the development of management strategies for asbestiform minerals in tailings. It also presents a numerical modelling approach for evaluating the rates of rise in the storage of magnetite tailings. The paper concludes by outlining how the findings of these studies can be applied to reduce tailings management costs, lower risks and improve environmental outcomes for the management of tailings from iron ore mining.

Jul 11, 2011

By Y Ren

The algorithms employed by the commercial tools are either heuristic algorithm or iterative optimisation of a subsystem. This often results in a suboptimal schedule. In this paper, the author presents a new scheduling algorithm that incorporates with a novel stockpile configuration system, an improved algorithm on multiple processes and a mixed-integer linear programming (MILP) global optimisation model. It can simultaneously optimise stockpiles, blending, multiple processes as well as multiple mines. In addition, it allows the user to interact with the solution to adjust the solution to be practical and desirable.CITATION:Ren, Y, 2013. A simultaneous optimisation tool for open pit mine scheduling, in Proceedings World Gold 2013 , pp 427-432 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By G Harbort

Traditional engineering design for flotation circuits use the “Rule of Thumb” approach. Typically this uses a nominated maximum head grade for design. A scale-up factor is applied to laboratory flotation tests for residence time. This scale-up factor is usually based on a designers experience at other flotation sites and may or may not be relevant to the circuit being designed, or the flotation equipment being used. A small number of locked cycle tests are assumed to represent the ore body and the results of these are often used for financial analysis, independent of changes in mine plan throughput and mineralogy.The engineering “Rule of Thumb” approach is only strictly accurate where there is very little variability in throughput, head grade and mineralogy. It may provide accurate design for mature established operations where a brownfield expansion is being considered but is unlikely to provide accurate design for a new, greenfield site.The use of geometallurgical modeling with floatability component simulation provides a design methodology with significantly less associated risk. The use of geological data for optimisation of operating plants has become a significant part of the modern process mindset. The underlying principle is to use spatial metallurgical information to drive production planning, mine planning, blast design, blending strategies and plant set-up. At a design stage the process designer can use geometallurgical information to evaluate bottle necks and potential design flaws and propose the best investment strategy for the project benefit.This paper details the geometallurgical characterisation of the Andash deposit and methodology used to review the project’s detail design and projected production.

Aug 8, 2011

By N S. Weerasekara, S Town, E Lessing, J A. De Torres

Philsaga Mining Corporation (Philsaga) had three main aims in converting their lining system from steel to metal cap. They wanted to increase mill availability, minimise localised high wear and optimise particle breakage to deliver increased efficiency within the milling circuit. Combining Discrete Element Method (DEM) modelling and empirical interpretation of liner wear resulted in a rigorous approach to understanding the impact of mill liners on overall mill performance. This new understanding was subsequently used to not only derive a new lining design to optimise performance and thereby improve overall plant economics, but also to guide further lining development.In this work, detailed DEM modelling, developed from actual plant data, together with optimising liner design for wear paved the way towards the installation of a Metal Cap lining system at Philsaga’s Ø6100 mm SAG Mill. The results were a reported increase in SAG mill throughput of 16 – 20 per cent due to improved breakage through more efficient use of installed power, a reduction in localised high liner wear with overall increase in liner life and reduction in liner replacement time. Site also reported an increased gold recovery of 2 per cent which the improved breakage might have contributed to. This paper will present the design challenges and compare the Metal Cap lining systems performance against Steel lining system. CITATION:Weerasekara, N S, Lessing, E, Town, S and De Torres, J A, 2018. Metal cap versus steel lining system at Philsaga Mining Corporation’s Ø6100 mm SAG mill, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 653–664 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By T Niitti, J Turunen, P B, A Rinne

In todayÆs marketplace, with high metals prices, many operations are faced with the challenge of improving recovery in the particle size ranges which are normally difficult to recover. This presentation focuses on the various methods used to alter the flow dynamics in a mechanical flotation cell, thereby improving metallurgical results. Modern computational fluid dynamics (CFD) tools have been used in the design phase, with subsequent validation at the plant. Some of the validated variables include mixing profile, power draw and local air hold-up. This presentation underlines how modern CFD analysis can be used to screen and select different approaches before commencing costly trial-and-error experiments at plant scale. Two methods of affecting flow dynamics are discussed û firstly, by altering the geometry of the rotor-stator area and, secondly, by fitting additional features in the tank. The rotor-stator area can be modified to provide more concentrated turbulent kinetic energy or, respectively, to provide more pumping efficiency with less attrition. The tank can be fitted with various additional features, aimed to create different particle suspension profiles. The benefit of both methods is that they can be applied not only to newly installed flotation technology, but also to existing plant cells, thus enabling potential improvement in the mixing profiles, solids suspension, tank sanding and metallurgical performance. Results of several sitesÆ tests are discussed in terms of flow variables measurement as well as metallurgy. This paper demonstrates the effects of different flow dynamics on the mixing profiles and metallurgical results of existing mechanical flotation cells.

Jan 1, 2006

By M R. Asef

Although generation of environmentally harmful hydrogen sulfide is considered to be related to sour gas fields, sweet gas reservoirs and waste fluids, travertine springs and geothermal fields may also produce acid gas (H2S and CO2) under certain conditions. The potential parameters influencing such a possibility need to be fully investigated to evaluate the extent of the consequences and predict hydrogen sulfide generation accordingly. Reports on hydrogen sulfide production at different regions and fields were gathered worldwide for the cases when some of them did not have such a problem previously. In order to inspect different aspects of these case studies, some other regions with no hydrogen sulfide content were selected as control. In all cases water samples were taken carefully for chemical analysis in the laboratory. Besides, mineral compositions were characterised in some cases for better evaluation. In order to give a thorough prospect of hydrogen sulfide production, a geochemical model was prepared. In situ engineering geological conditions, especially pressure and temperature, were assigned in the model to investigate the possibility of H2S generation using PHREEQC software. The results of modelling revealed that although many similarities existed between mineral compositions of the cases, certain formations were particularly prone to hydrogen sulfide generation. For better evaluation, important exchangeable cation ratios such as potassium/sodium, calcium/magnesium and ion proportions like sulfate and chloride were calculated as trends of the formations. As expected, the model could successfully monitor a higher ratio of SO42- and Cl- in potential H2S generator formations. Wide variation in percentage of HCO3- was considered as a secondary observatory parameter for better estimation. In addition, it was noticed that higher anion content created an environment ready to absorb any cations and this makes H2S generation easier. Finally, using correlations between predictors and estimators for low depth and deep samples defined the degree of effectiveness for every sample.

Sep 26, 2011

By R Kroukamp, G Rech

CRONIMET Australia in cooperation with Speciality Metals International, the mining lease holder of the Mt Carbine Tungsten mine, have demonstrated the preconcentration and processing of large (>12 million tonnes) tailings and mine waste dumps on site in far north Queensland. The first stage of this project has proven the economic viability of preconcentration using sensor-based particle sorting whilst ensuring high recovery of industry critical tungsten minerals – wolframite and scheelite. Sensor-based sorting technology have enabled the production of a sorter product to feed the existing wet gravity plant ensuring higher recoveries and increasing concentrate production. Processing of 1,000 tonne low grade samples using the TOMRA x-ray transmission (XRT) ore sorter installed on site, has reduced the volume of material entering the downstream wet processing plant by up to 60%. The sorted 10-25mm size range produced the highest upgrade ratio (product/feed) of 24:1 and achieved sorter concentrate grade of 1.52% WO3, sorter waste grades below 0.014% WO3 and metal recoveries of up to 93.4%. The appropriately sized, barren sorter waste material is also sold as aggregate and other quarrying products and thus adding to the overall economic benefit of the project. The utilisation of the sorting technology on site has produced an economically viable project, significantly reduced capital cost, and reduced the time to market of the final tungsten concentrate. The next phase of the project includes design and installation of a larger two sorter plant capable of over 150t/h feedrate.

Nov 10, 2020

By MáAndrusiewicz, M M. Hilden, M S. Powell, P D. Kay, B Foggiatto

Circuits with unconventional and potentially more complex designs are predicted to become more common in the future as plant designers and operators look to process ores more efficiently. Ideas have been presented on how circuit design may be changed to utilise todayÆs technology to address tomorrowÆs challenges (Powell and Bye, 2009; Powell, Benzer and Mainza, 2011a). High pressure grinding roll (HPGR) installations in various configurations; application of preconcentration plants eg sorting, magnetic or gravity separation; and preweakening devices eg microwave processing; are all examples of technologies having the potential to deliver a significant reduction in comminution energy for ores amenable to these processes. Not only will future novel circuits contain equipment for which models are not as well developed (if at all), many will likely require the ability to respond to variations in feed, and interact with geometallurgical models requiring process adjustments when the ore characteristics change.In order to confidently simulate more complex circuits and accommodate variations in feed type, a significant advancement in modelling and simulation capability is required. This includes dealing with multiple components in the feed, accommodating different competencies of ore, utilising physical separation opportunities and tracking the grade reporting along the different potential processing routes. Developing the means to simulate complex circuits has been a key priority of a collaborative group of comminution researchers working to solve these challenges.Simulations are presented utilising a new configurable simulation interface called the model developers kit (MDK). The MDK is designed to accommodate multi-components and incorporate new models under development. These will be used to demonstrate the potential of flexible circuit design, based on measured ore properties and equipment performance.CITATION:Foggiatto, B, Hilden, M M, Powell, M S, Kay, P D and Andrusiewicz, M, 2012. Simulation of flexible circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 291-298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By C Smith, R I. Maczkowiack, P D. Erskine

Open cut coal-mining has been conducted in the Bowen Basin region of central Queensland for almost five decades, and has disturbed an estimated area of 140 000 ha of agricultural land until 2011. Approximately one-third of the area disturbed by mining has been rehabilitated to pastures or bushland. However, none of the rehabilitated land has yet been assigned a specific end-use. This research project develops an approach for assessing end-use risks for the regionÆs mined land, and develops risk assessment models for selected end-uses. First, a web-based survey of stakeholders was used to identify risks to be assessed. The risks identified were surface erosion, subsurface erosion, bushfires, weeds and feral animals. The survey also identified possible end-uses of bushland and grazing. Second, conceptual risk models were developed based on the risk assessment concepts of likelihood and consequence specified in the Australian and New Zealand risk assessment standards. Likelihood was modelled using site characteristics and management factors that influence the occurrence probability of risks (eg surface erosion), while consequence was modelled using a set of site condition indicators and condition thresholds (changes in root-zone water-holding capacity, soil erodibility, vegetation ground cover and soil organic matter and transition probability to a non-preferred ecosystem type).The factors influencing likelihood and consequence for each risk have been integrated using Bayesian networks. The next step in model development is to parameterise the Bayesian networks using existing equations, empirical datasets, or expert opinion where data are not available. The parameterised models will be used to assess grazing and bushland end-uses against erosion, bushfire, weed and feral animal risks for rehabilitated mined land sites, with the purpose of identifying the relative risks associated with each end-use, and the landform design specifications and land management practices under which end-use risks are minimised.CITATION:Maczkowiack, R I, Smith, C and Erskine, P D, 2012. Risk assessment models for post-mining land use, in Proceedings Life-of-Mine 2012, pp 33-42 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By P Ridley

EnergyAustralia’s Sydney Central Business District (CBD) cable tunnel network will form a loop 6.2 km in length. The 3.2 km long, 3.5 m, diameter city east cable tunnel (CECT) currently in design, will complete the loop in 2014. This paper discusses the ventilation design of the CECT, considering operation for four functions:1. normal (unmanned),2. access (manned),3. purge, and4. emergency fire modes.The dominant design criterion which determines the required ventilation capacity for CECT is the specification of an upper air temperature limits of 35°C (dry bulb) and 24°C (wet bulb) for manned access, during all ambient weather conditions and cable heating loads. Simplistic static heat transfer analyses do not yield a sufficiently accurate calculation of tunnel air temperature and humidity to provide a safe and yet economical design. The primary refinement in the analysis discussed in this paper is associated with modelling of the system’s dynamic behaviour.Our means of analysis is through a thermo-fluid-dynamic simulation of the interactions between the diurnally and seasonally varying loads (cable heat generation, ambient air conditions and groundwater inflow), tunnel airflow and the resulting tunnel air temperature and humidity. These simulations are validated using experimental data from the existing city south and city west cable tunnels.Fire life safety scenarios are also analysed and discussed in association with the ventilation design. Ventilation strategies are developed for dealing with such emergency fire situations.The understanding and insight provided by the work offers the ability to optimise ventilation plant provisions in future cable tunnels, particularly long and high energy density tunnels.

Mar 8, 2011

By J Herd, J Rowe, M Cutbush, d F. Aziz

WearApp provides expertise for assessing the degradation of removable screening media panels on vibrating screens right in a user’s pocket. Through the WearApp application, users can simply take a picture of a panel using their mobile, enter some basic information and have the application assess the wear to provide a recommendation for whether the panel needs to be replaced. Where traditional mechanisms for assessing panel wear only measure a few points across the panel face and rely on having personnel with specialised knowledge available to perform the assessment, WearApp uses deep learning models to analyse the entire panel face and support the user to make an informed decision. The application works through analysing a panel image and using a model to automatically detect the corners of the panel. Given the known dimensions of the panel, this enables the application to calibrate the pixel size against a known reference. A second set of models then detect the apertures and measure their dimensions. With the aperture dimensions defined the application assesses the wear of the panel through referencing a stored 3D model of the aperture. Finally, the data from each aperture is collated and the wear of the entire panel face defined. Since WearApp performs measurement of the entire panel face, it also allows the user to perform a more detailed analysis of the panel’s wear profile. Where typically, the panel wear is only measured in a few locations, WearApp’s analysis enables users to visualise the panel wear across the entire panel face, identifying areas of high wear that could be leading to premature panel replacement. Additionally, because the entire panel face is measured the change in screening efficiency can be calculated accurately for the worn panel, even taking into account the impact of aperture pegging by small rocks.

Sep 1, 2024

By S Wilkinson, S Black, L van den Berg

"The mine ventilation system plays an important role in mitigating human exposure to diesel particulate emissions (DPM), exhaust gases and heat in underground mines. The mine’s secondary ventilation systems are critical for diluting contaminants when working at the face of a heading. To improve these systems it is important to understand and visualise the localised air flow profiles. We have considered an approach that includes both tracer gas measurement–modelling to analyse this complex flow behaviour in a heading. The use of tracer gas enables reliable measurements of flow behaviour and differentiation between the contributions of various contaminant sources including DPM. A pilot study was conducted to demonstrate how tracer gas can be used to directly measure the effectiveness of ventilation dilution in a heading during shotcrete activity. This activity is considered to be one of the more challenging areas for diesel exhaust exposure management. Exposure sources include the diesel engine of the spraying equipment (Spraymech) and concrete agitator truck (Agi) that supplies the shotcrete. During operation both the Spraymech and Agi operators are located outside the equipment’s air-conditioned cabins and both are exposed to diesel exhaust. In the pilot study tracer gas was injected directly into the Spraymech exhaust stream. This allowed thorough mixing, ensuring the tracer gas was able to track exhaust gases and particulates released to the heading. The release was repeated at three different headings with varying degrees of secondary ventilation controls. The study showed that small changes to the secondary ventilation system can significantly impact the contaminant concentration. It also demonstrated that tracer gas can be used to isolate different contaminant sources. The intent is to use this technique in a more comprehensive study to develop best practice guidelines for secondary ventilation installations. This paper presents the technique used and the preliminary results from the pilot study. CITATION: Wilkinson, S, van den Berg, L and Black, S, 2015. Application of tracer gas flow profiling to improve secondary ventilation practice – a pilot study, in Proceedings The Australian Mine Ventilation Conference, pp 345–352 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 31, 2015

By E R. Ramanaidou, M A. Wells

Reflectance spectroscopy is now an established technique for mineral exploration and ore characterisation. The efficacy of the technique as a tool to characterise the main iron ore and gangue mineralogy at African Minerals Ltd’s Simbili iron ore deposit in north-central Sierra Leone was tested through reflectance spectroscopic analysis of 13 000 pulped drill reserve samples using CSIRO’s HyLogger-1™ system. Specifically, integration of reflectance spectral data with more traditional methods of analysis, such as geochemical analysis and Satmagan measurements, characterised the mineralogy (ie hematite versus goethite) of the oxidised ore at Simbili, quantified the Al associated with goethite and hematite and evaluated the distribution of the main gangue minerals – kaolinite and gibbsite. Relative changes in the Fe2+/Fe3+-bearing oxide and silicate mineralogy, based on mineral indices derived from reflectance spectroscopic measurements, appeared well-related to changes in the ore profile mineralogy consistent with the main ore types identified at Simbili, as representative of an oxidised banded iron formation sequence. Spectral calibration models, developed from a well-characterised training set of mineral mixtures, representative of the oxidised ore zone mineralogy were used to quantify the distribution of Al associated with kaolinite and gibbsite and the iron oxides, goethite and hematite. Combining these mineral spectral parameters with compositional data enabled the differentiation of Al-substituted goethite and hematite and resulted in the identification of low Al-bearing, or ‘clean’, goethite and hematite from high Al-bearing, or ‘dirty’, goethite and hematite. Spectral quantification of the iron oxide Al composition provides a far more rapid means of quantifying the Al substitution in iron oxides at the deposit scale compared to traditional techniques such as X-ray diffraction analysis. It also enables a level of volumetric characterisation and the potential for large-scale (ie three-dimensional) mapping, which was not previously possible with other techniques. The potential of the technique was also highlighted when mapping the distribution of the main Al-bearing contaminants (gibbsite and kaolinite) identified in the oxidised ore zone at Simbili. Delineation of such zones provides a guide to managing the most appropriate processing options (ie upgrade potential) within a mineralogical framework. Three-dimensional modelling of the gangue phase distribution may also allow the mapping of lithological and/or structural controls that may be prevalent at Simbili. This work highlights the value in the application of HyLogging™ technology for rapid resource characterisation, particularly for volumetric identification and mapping the distribution of both the economic and gangue phases, which otherwise would be difficult to achieve. As such, the technique can provide a fast and inexpensive means to evaluate ore and gangue mineralogy at the deposit scale and provide a first-pass assessment of the mineralogy and compositional attributes, with the potential to better predict ore metallurgical properties.CITATION:Wells, M A and Ramanaidou, E R, 2015. Waste not, want not – delving deeper into the Simbili iron ore deposit using HyLogging™ scanning technology, in Proceedings Iron Ore 2015, pp 337–346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By M Lak, R Amiri, A Haratian, M Asghari, S Haji

Dry magnet separators are used to upgrade and beneficiate a wide variety of minerals such as hematite and magnetite materials. In recent years advances in dry magnetic separators have improved their performance. Fine particle separation is one of the main areas which still remain weak. This paper will present a new design of fine particle drum separators which used for particle size less than 3 mm. A big problem in processing of iron ore is the grade and recovery of mineral values in the fines fraction. The new design high efficiency drum separator is developed to handle fine feeds. In this drum separators both of the drum shell and magnetic yoke rotate in opposite direction. the results showed that when the material feed size was = 1298 μm, drum shell speed was 42.5 rev/min, magnetic yoke speed was 100 rev/min and the maximum intensity of magnetic field was at = 30° the feed grade increased from 50.87 to 65.67 in concentrate box, increase to 60.45 in middle box and tail grade was 24.44. The total achieved recovery for both concentrate and middle box was 81.89 per cent.

Nov 8, 2021

By A Reschke

The Thiess John Holland Group is undertaking the design and construction of Brisbane’s Airport Link Project, the largest single investment in transportation infrastructure in Australian history. Twin Herrenknecht TBMs are being used to bore parallel road tunnels from Kalinga Part in Toombul through to Lutwyche, a distance of 2.45 km. At 12.48 m, these tunnel boring machines (TBM) are the largest diameter machines, outside of Japan, to incorporate annular two-component type grouting through the tailskins.Grout design, preparation and injection have been given particular attention in this project in order to push the boundaries of achievement. Laboratory testing was conducted on various mix designs to ensure the contract specifi cations for grout strength could be met. To study the mechanics of the grout injection process, Herrenknecht supplied a test rig which duplicates the grout injection systems on the TBMs. Multiple recipes were tested, carefully selected to balance the requirements of rapid strength development with high mobility (to completely fill the void between the segmental lining and the ground) and minimal bleed.Team Mixing Technologies, Canada, was selected as the grout plant provider based on the technical performance of their high shear colloidal mill mixers. Field results have shown that the colloidal mixer prepared grout gives almost double the strength of an identical grout prepared by a paddle mixer.

Mar 8, 2011

By J Bean

Iluka Resources Ltd developed the Jacinth-Ambrosia Mine (Jacinth) in the Eucla Basin during 2009 and 2010. In this arid climate the operation relies on hyper-saline groundwater from a palaeochannel for process and potable water supplies. The water is hyper-saline, acidic and mildly reducing, with high ferrous iron concentrations. Ferrolysis commences on exposure of water to oxygen, resulting in increased acidity and the conversion of dissolved ferrous iron to insoluble ferrihydrite. The unstable groundwater forces a careful balance between interventions relating to maintaining pipeline efficiency, corrosion protection and processing aspects. Providing an oxidising environment at the head of the pipeline will result in the precipitation of akaganenite and goethite in the pipeline, which over time reduces pipeline efficiency. However, sending too much ferrous iron forward may reduce processing performance.The processing plant experiences changes in water chemistry in response to the variability of iron concentrations and pH within the pipeline, and the spatial and chemical variability of ore. As the main orebody at Jacinth contains little buffering capacity a source of carbonate in the overburden is carefully used to allow the cost-effective control of process water pH.This paper highlights the importance of understanding the chemistry of saline make-up water, ore, and overburden when designing water treatment facilities and heavy mineral processing facilities.

Oct 5, 2011

By M Rayner, C Tsouris, A Komelkov

X-ray fluorescence (XRF) is a widely accepted technique for the elemental analysis of iron ores and their concentrates. Wavelength-dispersive, or WDXRF, and energy-dispersive, or EDXRF, spectrometers offer distinct advantages for particular applications, elements and concentration ranges and are, therefore, more complimentary than people might realise. A key example is the ability of EDXRF to identify, and often quantify, unexpected elements in production samples that would typically be missed by routine WDXRF. In this paper we discuss recent technological advances in XRF and present a novel application example that demonstrates the additional technical and practical benefits of using both EDXRF and WDXRF to characterise iron ores and concentrates.CITATION:Tsouris, C, Komelkov, A and Rayner, M, 2015. A novel approach to the characterisation of iron ores and concentrates using recent advancements in wavelength- and energy-dispersive x-ray fluorescence spectrometers, in Proceedings Iron Ore 2015, pp 591–594 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By S Goff

The Northern Sewerage Project (NSP) is a $650 M infrastructure project that will increase the capacity of the sewerage system for Melbourne’s growing northern suburbs while also helping to protect the Merri and Moonee Ponds creeks by significantly reducing the number of sewage overflows that can occur after heavy rainfall. The NSP consists of two stages: Stage 1 (NSP1) will be owned and operated by Melbourne Water Corporation, and Stage 2 (NSP2) will be owned by Yarra Valley Water and operated by Melbourne Water Corporation.Glass-fibre reinforced plastic (GRP) was used on both NSP stages, however, since Stage 1’s schedule for installation of GRP was slightly ahead of Stage 2’s, this paper will only focus on Stage 1’s use of GRP.NSP1 involves the construction of 7.9 km of new sewer tunnel ranging in diameter from 1.6 to 2.5 m, five main access shafts at depths of up to 65 m, and connections to the existing sewerage system including several access manholes. Construction began in 2007, and project completion is expected in 2012.The original design for NSP1 specified the use of high-density polyethylene (HDPE-) line precast concrete pipes as the final tunnel lining and HDPE-lined reinforced concrete for the access shafts and manholes. During construction, the rising cost of precast concrete pipes and the introduction of an additional GRP pipe supplier in the market justified a review of the tunnel final lining material. The contractor-proposed GRP pipe alternative was accepted for the final tunnel lining based on time and cost savings that were possible without compromising the design intent. After gaining experience with GRP through this design change, Melbourne Water Corporation reviewed and accepted GRP as the final lining for five smaller connection manholes. The use of GRP for the manholes was particularly inventive as the redesign made use of the approved tunnel GRP pipes as both a structural and corrosion-resistant lining.This paper discusses the use of GRP on NSP1; how the change in material, from concrete to GRP, affected the design philosophies assumed during detailed design; and how construction methods were modified to handle the less rigid GRP material. Details on the structural, hydraulic and durability considerations for the design are included, as are details about the time and cost savings and the quality and safety improvements that were achieved during construction.

Mar 8, 2011

Vertical retreat open stoping (VROS) is a variation of sublevel open stoping (SLOS) that has been introduced at Cannington to minimise the influence of subvertical geological structures during stope extraction. The first application of VROS is described, where structures within the stope resulted in a change in firing sequence and the extraction of two complete sublevels in a single blast. The use of electronic detonators is critical to the success of VROS and their application is described. Numerous benefits of using VROS have been identified and are described. To date, eight stopes have been successfully mined using VROS. In addition to the first application of VROS, two further case studies are described.

Jan 1, 2005