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By S Agdaca

Leightons is the sole contractor at the Wahana Coal Mine Project (part of the Bayan Group), a multi-seam thermal deposit consisting of 13 coal seams with thicknesses ranging from 20 cm to 500 cm. The average dip of the deposit is 18 - 20°. However the deposit is heavily faulted in certain domains with anticlinal and synclinal structures present causing seams to dip up to 90°. Average thickness of coal inter-burdens range from less than 2 to 12 m. The minimum coal thickness being mined is 20 cm. Coal production is direct mine mouth feed and there is no coal processing plant currently used.Conventional blasting between the highly variable coal horizons in the early phases of the mine life was suboptimal from a production perspective. Drilling short holes with a reduced drill pattern, and on occasions with sloping benches, resulted in low drilling and explosives loading efficiency.A high frequency of small size blasts fired up to two times daily was required with each blast consisting of four up to five small blast areas. Each blast averaged approximately 36 000 bcm thus causing a low utilisation rate of the mining fleet from frequent blast delays and the inability to deploy larger Liebherr 9350 excavators on bench. It was identified that increasing the production targets required a more efficient drilling and blasting process. Furthermore, due to the highly variable nature of the deposit, the existing coal model was determined to not be able to accurately predict the coal seam location prior to blasthole drilling.In August 2009, Leighton Contractors Indonesia and Orica Mining Services with the full support of the Wahana team, initiated through seam blasting trials using electronic blasting systems. Further trials were conducted in November 2009. Trial evaluations indicated that the benefits from decreased lost time events due to blasting, an increased vertical advance rate per blast, and increased overall blast size could be attained while not damaging or diluting coal.Full-scale?through seam blasting has been ongoing since February 2010 for the upper eight coal seams to extract coal seam thicknesses ranging from 20 - 100 cm. This paper will discuss the parameters of the through seam blasting process in Wahana and the resulting benefits to the overall mine production.

Nov 8, 2011

By B Lumsden

During periods of high metal prices and strong metal demand tailings retreatment can be economic. Most tailings retreatment operations are technically challenging, low margin operations, because the easily recovered mineral has already been removed, therefore, process improvements can potentially yield large economic benefits. The Hellyer tailings dam was owned by Intec Ltd and contained 10.9 million tonnes grading 2.8 per cent zinc, 3.0 per cent lead, 88 g/t of silver, 0.16 per cent copper and 2.6 g/t gold. In November 2006 the Polymetals Group, as operator, restarted the Hellyer plant to retreat these tailings. Within a few months the operation had stabilised and Polymetals was meeting budgeted targets of throughput, metal recovery and concentrate quality. Polymetals and Intec then investigated methods that would improve the metallurgical result for this difficult to treat tailings. Since the tailings are fine-grained with 80 per cent <45 ¦m, magnetic aggregation of the paramagnetic sphalerite was evaluated. Magnetic aggregation of an oxidised tailings feed has not been tested before, nor had the technology been available when Hellyer ore was originally processed. Extensive statistical test work showed magnetic aggregation of the sphalerite fines in the zinc cleaner circuit increased total zinc recovery. The increase in the mean zinc recovery with magnetic conditioning was 3.63 per cent, at a statistical level of confidence of 97.8 per cent, and at the same mean zinc concentrate grade.

Jan 1, 2009

By G du Toit, P L. Gillot, M Swanepoel

Randgold Resources’ Loulo-Gounkoto Complex is one of the largest gold mining operations in Mali, West Africa. The mine, which is situated on the western border with Senegal, treats more than 4 Mt/a of ore through a conventional three-stage crushing and ball milling circuit followed by a carbon-in-leach plant. Ore supply is achieved by a combination of open pit and underground mining, with the majority of the ore supply sourced from the Gara and Yalea underground mines situated approximately 2 km and 6 km respectively from the gold plant.In 2011, Randgold Resources commissioned Golder Associates to perform an evaluation study for providing structural backfill to both the Gara and Yalea underground mines using the current gold plant tailings. The test work performed as part of the evaluation study concluded the need for a tailings cycloning and dewatering facility capable of producing slurry at a solids concentration of 65 per cent with a particle size distribution that had minimum 25 per cent passing 20 µm and less than 5 per cent of -5 µm material. Tailings desliming was required to ensure a consistent feed quality to the paste preparation plants and to ensure that the system would be capable of handling variation in the feed composition from the gold plant.WorleyParsons, previously TWP Projects, was contracted by Randgold Resources to complete the engineering design for the slurry preparation plant, whilst Golder Associates was retained to complete the engineering design of the two paste preparation plants.This paper discusses the test work, design considerations and engineering design of the slurry preparation plant, termed the ‘intermediate plant’, as well as all ancillary facilities required for the delivery of the deslimed slurry to the paste preparation plants located at the two underground mines.CITATION:Swanepoel, M, du Toit, G and Gillot, P L, 2014. Case study – engineering design for a slurry preparation plant for a paste application in West Africa, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 477–486 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By A Datar, D Mulligan

The extractive phase of broad-scale mining can have major impacts on landscapes and associated ecosystems. Post-mining ecological rehabilitation typically starts with reconstructing topography. A fairly common industry practice has been to use landform elements such as plateaus, terraces, and gentle slopes for stabilisation purposes. However, this approach can lead to the generation of fairly uniform landforms that do not necessarily reflect natural ecosystems. Previous research in undisturbed and agricultural landscapes shows that ecological attributes and diversity in microclimates is positively correlated with landform heterogeneity. An objective of this study was to investigate if those findings are still valid in post-mining rehabilitating landscapes on North Stradbroke Island, Queensland, Australia. We investigated the relationship between landform heterogeneity and status of ecological recovery. The landform heterogeneity is measured through variance in three landform characteristics (relief, slope, aspect) using remote-sensing data and the status of ecological recovery is represented by ecological indicators measured through field surveys. The results indicate strong correlations between landform heterogeneity indices and native vegetation species richness with sensitivity to the spatial scale of investigation. It is recognised that climate, substrate and rehabilitation practices act as primary drivers of rehabilitation success. However, the results indicate that, in some examples, landform heterogeneity (heterogeneity in relief and slope angles) contributes up to 30 to 50?per?cent of the variance in native vegetation species richness. While the primary drivers of ecological recovery are difficult to control over extensive areas and extended time periods, landform heterogeneity provides a tool to indirectly control the micro-environmental parameters to improve ecological recovery. Reducing the uncertainties in the choice of ecological and landform indices and the degree of landform heterogeneity suitable for particular rehabilitating landscapes would be site specific. The introduction of desired landform heterogeneity may provide a very effective tool for significant improvement in ecological rehabilitation across broad-scale post-mine landscapes, an outcome of benefit to industry, government and local communities.CITATION:Datar, A and Mulligan,?D,?2014. Do we need to change the way we set up the stage?, in Proceedings Life-of-Mine 2014 , pp 29–46 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

With the advent of the resources boom in the late 1960s most of the larger scale resources projects in Australasia were commissioned on an æowner miningÆ basis, where the mine owners owned and operated the primary mining equipment. Then, in the 1980s with the arrival of the gold mining boom in Western Australia and elsewhere, a change occurred û most of the mining activities were carried out on a contract mining basis. Over recent years, however, there has been a marked trend amongst larger Australasian open pit mining operations back towards owner-controlled and operated mining operations. The reasons for this are many and are addressed in the paper, but centre on the concept of the owner being prepared to assume more of the mining risk in exchange for the advantage of not having to pay a contractorÆs profit margin. Where mining contracts are entered into, the older æschedule of ratesÆ format is being replaced with less adversarial and more entrepreneurial contract alternatives involving operating cost and risk sharing in a spirit of æfair dealingÆ. Leasing and maintenance issues have also been influenced in recent years by the advent of more flexible contract arrangements with equipment suppliers. Group purchasing has also had some influence for project operators. For many mine owners, the optimal risk management profile involves a practical offsetting of the assumption of mining risk on the one hand, against the removal of litigation risk and potentially reduced operating costs on the other. Potential pitfalls may arise where equipment size and type requirements vary with time or where manpower management, mining flexibility, job skills or safety exposure factors are relevant. These issues are commented on in the context of some well known examples, and an update is provided on contract mining versus owner operation in large scale Australasian open pit mining generally.

Jan 1, 2002

By R Young

Independent Project Analysis (IPA) is in the business of benchmarking the performance of capital projects on behalf of owner companies in the processing and extractive industries. IPA assesses between 500 and 800 projects each year. The projects are conducted globally and range in size from about $1 million to over $30 billion. Using the data, we are able to benchmark the performance of Australian projects against the rest of the world. This presentation focuses on the performance of large (greater than $100 million) projects that involve chemical or thermal processing.We regularly hear calls for more processing to be conducted in Australia but on the other hand industry leaders are concerned about the poor success rate of solids processing projects in Australia. Data gathered by IPA indicates that there is good reason for the concern. Out of a sample of 31 large processing projects conducted in Australia, 23, or 74 percent, were classed as failures. This performance is significantly worse than for similar projects in other parts of the world. The presentation analyses why the performance is worse and demonstrates that many of the reasons behind the failures were manageable by the project team. Furthermore, members of the project teams on at least half the failed projects knew that the projects were on a path to failure before the project was authorised but could not be heard.The presentation discusses how large projects that involve process design and, in many cases, new technology, need to be set up for success. *This is an abstract only. No paper was prepared for this abstract.*

Aug 8, 2011

Optical sensors have emerged during the telecom boom in the late 1900s, due to the availability to low-cost telecom-grade optical components. It's only after the telecom industry's fall in 2004 that optical sensors became sufficiently developed to be a viable technology for real-world applications. Geotechnical applications have long relied on electrical sensors such as thermocouples, strain, and the venerable vibrating wire to measure physical phenomena. Although these are well suited for a large variety of applications, electrical sensors cannot be used for all applications: these are vulnerable to noise, hazardous voltages and corrosion, limiting the environments in which they can be used. In addition, electrical wires can also become an issue when sensors require external excitation or are distant from the measurement system. Finally, changes in physical properties of electrical sensors and systems over time makes regular calibration a necessity - not easy to do when these are permanently mounted on structures. Optical sensing systems are non-conducting and use light to perform various measurements. There are several optical sensor technologies available, each with different strengths and weaknesses. In addition, there are different methods of interrogating optical sensors, each of which also present different strengths and weaknesses. To make matters worse, configuring the interrogation and scaling to physical units can also be challenging to the unprepared engineer. This paper will present a holistic view of optical sensing, presenting the different optical sensor technologies and interrogation techniques. Sample optical sensing systems will be revealed and top considerations for optical sensing will be presented.

Nov 25, 2010

By G Baird, M Seto

Reliable evaluation of in situ stress is an important phase in the analysis and design of underground excavations, particularly for evaluating the stability of underground structures to prevent failure or collapse. A technique for the estimation of the full stress tensor based on acoustic emission (the Kaiser effect) is being developed and trialed at the WA School of Mines. The result obtained compare well with the standard over-coring method. The advantages of the technique are that it is relatively cheap, non-time consuming and is applicable to in situ stress measurements at depth in remote regions.

Jan 1, 2002

By R Berry, A Escolme

"Predictive geometallurgical models are being developed for the Productora Cu-Au-Mo deposit based on geochemistry to reflect variability in Cu species based on Cu sequential leach data (ie oxide, transitional-oxide, transitional-sulfide, sulfide and non-recoverable Cu).Productora, located in the coastal range of northern Chile, is a magmatic-hydrothermal tourmaline breccia-hosted, structurally controlled Cu-Au-Mo deposit hosted by a thick sequence of Jurassic rhyodacitic volcanic rocks. North and north-west striking fault sets control the distribution of mineralised breccias. Alteration is widespread, complex and pervasive. Hypogene alteration assemblages range in composition from distal magnetite-amphibole, to sodic-calcic, to sodic, to phyllic, to proximal potassic. Low-temperature advanced argillic assemblages are locally juxtaposed next to proximal high-temperature K-feldspar-tourmaline assemblages. The dominant hypogene Cu phase is chalcopyrite.A simple Cu species classification scheme based on sequential leach data and S per cent was devised to account for non-recoverable Cu (ie non-sulfide Cu), which is insoluble in weak acids. Through machine learning, a proxy for this Cu species classification scheme was developed based on: depth, Ca per cent, Cu per cent, Fe per cent, K per cent, Mn ppm, S per cent and Ln(Cu/S) plus logged regolith class, thus allowing classification to be extended to areas of the deposit where no sequential leach data are available. The modelled data has been used to generate deposit-wide 3D models for Cu species classification.The validity of the proxy Cu species classification model is being tested against the results of flotation analysis. Initial results indicate that geochemical proxies can be used to successfully predict Cu species class and provide a high density of classification data.CITATION:Escolme, A, Berry, R and Hunt, J, 2016. Predicting Cu Species Classification Using Geochemistry at the Productora Cu-Au-Mo Deposit, Chile, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 113–118 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

The gold salting fraud at Busang on the island of Kalimantan, Indonesia was exposed in early 1997 and resulted from the independent drilling, sampling and assaying of PT Freeport Indonesia which reported assays from the South East Zone with negligible concentrations of gold. Since then, a number of legal actions directed at former Bre-X directors, consulting firms and financial or broking institutions are at various stages and are based on numerous allegations surrounding the supposed existence of obvious and numerous warning signs or æred flagsÆ. These include: the absence of references to visible gold in the drill logs; the alluvial nature of the gold grains; the high gravity recoveries; the invalid comparison with Kelian; the absence of outside scrutiny and the lack of external review/audit and surface depletion of gold. The focus on the red flags has been at the expense of the numerous positive indications or ægreen flagsÆ. These include the morphology and chemistry of the gold grains, the gravity testwork, the amalgamation results, the role of external consultants, the results of a review by one of North AmericaÆs leading minerals auditing groups, the behaviour of the gold at surface and the presence of references to visible gold in the drill logs. The flawed nature of the discussion of the technical facts surrounding Busang has prevented a meaningful and informed discussion about what actually happened and has, therefore, prevented the formulation of meaningful remedies for the future.

Jan 1, 2002

By S Henderson, J V. Lawless

The worldwide association of low-sulfidation epithermal gold mineralisation, bimodal rhyolitic-basaltic volcanism and rifting is confirmed in New Zealand. In the currently productive Coromandel epithermal-gold province reported Ar-Ar dating of adularia from low sulfidation deposits falls into two groups at 6 and 7 Ma. Bimodal rhyolitic-basaltic volcanism has been reported to be K-Ar dated at 9 to 7 Ma and 6 to 5.5 Ma. Epithermal gold mineralisation in Northland is spatially associated with bimodal basaltic-rhyolitic volcanism, with rifting cogenetic with that in the CVZ. The Taupo Volcanic zone (TVZ) is sufficiently young that the presence of a segmented rift with recent bimodal rhyolitic-basaltic volcanism can be genetically associated with epithermal gold mineralisation, which occurs as both fossil occurrences and in active geothermal fields. This reinforces the known potential prospectiveness of the Coromandel area and increases that of Northland and the Taupo Volcanic Zone.

Jan 1, 2005

By K Tungpalan, E Wightman, M Edraki, E Manlapig, L Keeney

The depletion of easily mined high-grade ore bodies resulted in the industry having to exploit lower grade, complex resources (Albanese and McGagh, 2011; Darling, 2011; Randolph, 2011). The trend is now towards mining and processing of low-grade and complex ores (Darling, 2011; Yingling, 1990). Variable geological and mineralogical characteristics, and complex mineralogy and texture can result in large variations in metallurgical response and also cause challenges in processing. (Carson, 1995; Lorenzen and Barnard, 2011; Yingling, 1990). Variability and the complex nature of ores are fundamental sources of risk that often cause the greatest economic impact (Dusci et al., 2007; Williams and Richardson, 2004). Hence it is important to effectively characterise these types of ore bodies and assess their processing performance (ie recovery, grade). To enable this, there is a need for the following: (i) characterisation of geological, mineralogical and metallurgical variability in the ore body; (ii) effective selection of drill core with characteristics that represent the range of ores in the entire ore body. CITATION: Tungpalan, K, Manlapig, E, Keeney, L, Wightman, E and Edraki, M, 2018. A systematic approach of sample selection to predict processing performance of an ore body, in Proceedings Complex Orebodies Conference 2018, pp 67–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By A Späth

Active explosion barriers are used to contain and suppress a methane gas and/or coal dust explosion propagation, including localised mine fires. Early research indicated that these active explosion barriers could be used on a mechanised cutting machine, making it the only technology that could suppress an explosion during its propagation phase at the cutting face. Thereby not only adding protection during mining operations but also reducing the development of toxic gases, fatal temperature increase and fatal overpressure build-up. During their evolution over the last two decades, further advantages of Active explosion barriers were proven in mine operations in countries such as South Africa and China. Characteristics such as effectivity, efficiency, mobility and space restrictions allow these systems to be used in various locations within a mine operation, including highwall operations. This improved technology contribution to safer coal mining was recognised by mine operators, workers and regulators. The Queensland’s Recognised Standard 21 (Resources Safety and Health Queensland (RSHQ), 2021) stipulated active explosion barriers as a technology to ensure the safety within their underground coalmines. The mobility and flexible implementation of the active explosion barriers allow a feasible and practical solution for all critical locations for explosion and fire management in an underground coalmine. The conformance to the Recognised Standard can be achieved all underground coal mining operations such as Bord and Pillar, and Longwall mining. This paper describes the conformance, implementation and use of Active explosion barriers for Longwall mining and development as well as Bord and Pillar mining in Queensland’s underground coalmines.

Oct 12, 2022

By K Faure

At Sams Creek a gold-bearing, peralkaline granite pophyry dyke intrudes Ordovician-Silurian metapelite and quartzite. The granite porphyry dyke has a thickness of up to 40 m, extends discontinuously for about 8 km, and intrudes thin lamprophyre dykes along its contacts. The granite dyke and gold-bearing sulphide and quartz-siderite veins within it have been deformed and recrystallised during several phases of folding, the youngest of which is Early Cretaceous.   The unaltered granite porphyry is composed of phenocrysts of perthite, arfvedsonite, aegerine and quartz in a groundmass of the same minerals, with accessory ilmenite, rutile and fluorite. K-Ar dates of amphibole from the granite gave ages of 226 and 246 Ma, but these ages may be a minimum due to resetting during the thermal and deformation events that have affected the area. Unpublished Ar-Ar data on amphibole from the granite show disturbed spectra with high temperature steps around 300-315 Ma, which is consistent with the age of A-type granites in the Buller region. Further age dating of primary and hydrothermal minerals in the granite is continuing. At least three stages of hydrothermal alteration have been identified in the granite. Stage I alteration is characterised by high fO2 magnetite-siderite ¦ biotite, which is cut by thin quartz-pyrite veinlets (Stage II). These are cut by Stage III sulphide, quartz and siderite veins, and pervasive silicification represented by quartz-perthite-albite-rutile ¦ pyrite-siderite-sericite assemblages overprints the earlier alteration stages. Lamprophyre is altered to a siderite-chlorite-sericite assemblage. Stage III sulphide veins are composed of arsenopyrite + pyrite ¦ gold ¦ galena ¦ sphalerite ¦ chalcopyrite ¦ pyrrhotite ¦ graphite, deposited by low fO2 H2S fluids. The gold contains 18-30 wt% Ag and up to 1 wt% Bi. Temperature of vein formation was estimated from vein quartz fluid inclusion homogenisation temperatures (Th 260-355oC, average 330oC), arsenopyrite-sphalerite thermometry (310-365oC) and quartz-albite stable isotope thermometry (340oC). The altered granite and the veins have been deformed, and recrystallised and competent sulphide minerals are fractured and brecciated. Alteration and mineralisation are confined to the granite porphyry and adjacent lamprophyre.

Jan 1, 2004

By W N. Qin, B Zhang, W Z. Huang, X S Mo

Mengzi Mining and Metallurgy Co, Ltd (MMMC) polymetallic ore contains recoverable amounts of tin, lead, zinc, pyrite and other valuable minerals. With the change in orebody, the run-of-mine (ROM) ore changed from lead zinc rich ore to tin rich ore, where the current ROM ore contains 0.45–1.25 per cent tin, 20–25 per cent sulfur, and 0.20–0.35 per cent copper. The previous processing flow sheet was designed to recover lead zinc rich ore and it is clearly not suitable for recovery of the current tin rich ore, where the tin was already overground and tin recovery was only 50.19 per cent. The Mengzi Mining Company has recently modified the concentrator circuit by incorporating rod mill and high efficient Derrick fine screen. As a result of the improved classification efficiency, the overgrinding of the tin ore was minimised and the recovery of tin was improved by 20.71 per cent, ie from 50.19–70.90 per cent. An additional $10 M revenue per annum can be achieved as a result of the modification.CITATION:Qin, W N, Huang, W Z, Mo, X S, Zhang, B and Wheeler, J, 2014. Application of high efficient fine screen to improve the recovery of tin concentrate, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 487–492 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

The detailed engineering of a coal preparation plant is important from the point of view of optimum constructibility, operational security, ease of maintenance, operating costs, meeting environmental goals, safety, plant housekeeping and reduced corrosion and erosion. This paper reviews the several large coking coal preparation plants engineered by Fluor Australia in the past 10 years, and changes and trends apparent for detailed engineering of future plants. Areas of engineering to be covered are coal feed preparation, conveyor design, plant layout, electrics and instrumentation, noise attenuation, erosion and corrosion protection, magnetite handling, rejects and tailings disposal and coal stockpiling and blending.

Jan 1, 1982

By K Rees

In the ideal world of an underground mining engineer, all narrow vein orebodies would be perfectly straight and continuous, thus would be a dream to mine. However, this is usually not the case. Narrow vein orebodies generally occur in association with shear zones and while shear zones do form linear trends, they most commonly preserve undulating expressions that need to be closely monitored, particularly when overprinted by post-formed structures. The surge in mines using fibrecrete as a primary form of ground support effectively reduces the time available for geological interpretation down to a 30 minute window between bogging and shotcreting. Thus, if the quality of the data collected is not up to scratch, then there is only a limited ability to reassess using 2D face photographs. To negate this, Xstrata Nickel AustralasiaÆs Cosmos mine has upgraded its data collection procedure. Geological information is now collected using photogrammetry survey, producing 3D images of the drive. Once created, the digital image of the drive is loaded into Vulcan, thus enabling geological interpretation to be carried out along entire drives, between levels and in association with all other data (eg drill holes, seismic data, etc). In addition to this, the 3D image can be used to accurately model the location of the ore, enabling stoping panels to be confidently positioned to maximise grade and minimise dilution. However, with the focus at Cosmos changing from narrow vein mining, to bulk mining methods in a more geotechnically complex terrain, the use of the 3D images has become paramount in understanding the structural geometry. Continual interpretation of the data has enabled drive profiles to be maintained through the increased use of ground support in poor ground and the redesign of development to enable optimal intersection of structures. Nevertheless, while the collection of quality data is important, it is only the effective use of the data, which enables significant gains in understanding.CITATION:Rees, K, 2012. The benefits of using photogrammetry in the geological interpretation of the Cosmos nickel mine, in Proceedings Narrow Vein Mining 2012 , pp 145-148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

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

INAP was formed in 1998 by a number of major mining companies, with a view to sharing acid rock drainage knowledge and experience, and to coordinate global research on the management of sulfidic mine wastes. INAP is now moving to further strengthen its global role by networking with regional organisations that are active in the area of ARD, including MEND 3/NEDEM 3 in Canada, the ADTI in the USA and ACMER in Australia. The INAP-Regional Organisation partnership will be formally launched at the 6th ICARD.

Jan 1, 2003

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