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By M Dietrich

The paper describes an efficient method for analysing the different attachment kinematics of excavators and other linkages by taking into account digging forces, the workspace and the stability of the machines. The different attachment kinematic systems of hydraulic excavators and a æclassical analysing methodÆ will be presented. The method was integrated as a plug-in for the multibody simulation (MBS) software MSC.ADAMS to create an easy to use solution for design engineers. A comparison of the new MBS-solution with the classical static analysis is a part of this paper and shows the advantages of the new method. This takes into account the manifold and new dynamic analysing opportunities, as well as more detailed models leading to more accurate results.

Sep 26, 2011

By C Jones

When the Paulsens operation was poised to be placed on care and maintenance, Bill Beament and the rest of the Northern Star Resources (NSR) team capitalised on the opportunity to send the Ashburton region’s only operating gold mine into the record books.A three-stage strategy was devised by NSR to pay off the acquisition and maximise the return from the operation. The first stage was to mine the 55 000 oz mine plan and pay off the cost of the acquisition, then maintain profitable production beyond the seven months and re-establish a mine life. The second stage involved an early commitment to a 220 m long diamond drill drive being placed in the hanging wall of the orebody from which the extensions of the orebody could be further explored, allowing the second stage of the plan to come into effect and extend the mine life by converting Inferred Resources into the mine plan. The third stage of the initial plan was to utilise this drill drive and continue to drill deeper holes beyond the current limit of drilling in the ore zones to extend the orebody and increase the mine’s life.With an ever growing desire to further expand, the young company took on the bold move of establishing its own mining services division. A critical element to the success of this was ensuring that the right people were recruited with the appropriate specialised skill sets.Aligning common goals amongst all NSR team members, from the board and senior management to the work force on site, was critical to integrate the new and driven direction that Paulsens had adopted. It was essential to change the focus and a shift in all employees’ attitudes and values from a mine that was all but down and out, to a site that wanted to be kicking some serious goals.Teaming together a passionate and driven leader with a strong allied workforce was always going to put NSR in the best position possible to make Paulsens the success story that it now is. But without the calculated risks and enthusiastic attitude, the little known mine site in the Pilbara might have remained just that.CITATION:Jones, C, 2014. The Paulsens transformation – a shining light under a northern star, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 191–196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By G Britton, P Moynagh

As more than a few mines gradually sink under the weight of emails, whiteboards, notice boards and ever more complex spreadsheets, the holy grail of effective short-term interval planning and control in underground mines is as far away as ever. Despite the mining industry investing ever greater amounts in planning and Enterprise Resource Planning systems, short-term plans become ever more complex and rigid. What the industry desperately needs are not more ‘disembodied voices down the speaking tubes’, but flexible and effective planning systems that encourage people to make reasonable commitments to each other so that everyone can work as a coordinated team to complete the work required each shift.One solution to the challenge has emerged. This paper describes the ‘Fewzion’ shift planning and short interval control system which has been developed at Anglo American’s Moranbah North and Glencore’s Oaky Creek coalmines in Central Queensland. Fewzion has drawn on management theory embodied in Management Operating Systems, Lean and Theory of Constraints approaches to continuous improvement to play a key role in both mines achieving record breaking tonnages.In addition to explaining the Fewzion approach, a case study is presented describing how Anglo American’s Moranbah North improved production by 39 per cent in 2014/2015 and won ‘Coalmine of the Year’ two out of the last four years and how Glencore’s Oaky Creek sustainably improved monthly development meters by 34 per cent within two months of implementing Fewzion.CITATION:Moynagh, P and Britton, G, 2017. How a frontline planning and commitment system improves trust, commitment and results in operations, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 235–240 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By A L. Bennett

It is well understood that designers and constructors must protect the existing surroundings of tunnel construction, particularly in the selection of excavation methods, ground support and waterproofing systems. However, while this can readily address the existing conditions, the tunnel owner and the designers need to consider the changes that are likely to occur during the life of the tunnel. It is typical for transport infrastructure to have a design life of at least a century. While the effects of constructing the tunnel on its surroundings are a short-term effect, the converse case, the protection of the tunnel, and the need to maintain its integrity, will affect developments over and adjacent to the tunnels beyond the foreseeable future. Decisions made during the design phase have the potential either to facilitate development or to hinder it for the long term.Examples principally from Australia, New Zealand, Singapore and Hong Kong show that the provision for future development is addressed in different ways. These have ranged from making no specific provision, putting the onus onto developers to ensure that the tunnels are not affected adversely, to including a loading allowance for future development in the performance specification or contract documents for a tunnel project.These two contrasting approaches have strong points and risks. A highly prescriptive definition of permissible loadings around the tunnel can provide unambiguous guidance for the approving authority and the developer, but runs the risk of being overly conservative to allow for all the envisaged works, while still missing a detrimental combination of effects that theoretically complies with the specified requirements. In contrast, a general requirement to not cause detriment is open to interpretation and potentially difficult negotiations to reach agreement between the tunnel owner/operator and developer and finally the appointed contractor (probably with no contractual relationship with the tunnel owner).In practice, a combination of prescriptive and performance requirements is likely to provide the optimum combination of clarity and flexibility. The author provides examples and recommendations on how such provisions could be structured.CITATION:Bennett, A L, 2014. Protection of ?tunnels in their future environment, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 495–500 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

The Ernest Henry Mine is an open pit copper-gold mining operation located in north-west Queensland, Australia. It is owned and operated by Xstrata Copper with a current concentrator throughput of approximately ten million tonnes per annum. The pit will cease mining towards the end of 2010. Extensive surface diamond drilling has confirmed an extension of the orebody to depths of 1000 m below surface. A prefeasibility study was commissioned in late 2006 to investigate underground mining options with the preferred mining method being an inclined sublevel cave. In February 2008 mining of a decline commenced in conjunction with a feasibility study to further investigate the project. Work from the prefeasibility study indicates that an underground crusher, conveyor and hoisting shaft could be utilised to crush and transport broken ore from the sublevel cave workings to the concentrator. The study suggests that a production rate of five million tonnes per annum could be achieved and sustained for up to ten years. Ventilation designs and requirements will form a large section of the feasibility study. This paper will detail investigations of preliminary ventilation network designs of the proposed sublevel cave. Work has been completed using both Ventsim and VumA ventilation simulation packages. Ventsim was used to provide preliminary estimations and suggest alternatives for: surface fan duties;airflow characteristics (direction, velocity, pressure and quantity); andventilation network design in key mine areas. With mining activities reaching depths in excess of 1000 m below surface an analysis of heat conditions should be conducted. The VumA software package was used to model the thermal properties of the ventilation system. This model will provide a basis for the preliminary decisions on refrigeration requirements for the mine.

Jan 1, 2008

By C Zschiesche, alam, A Abadias Llamas, A K

Lead has the ability to collect and carry valuable metals such as copper, bismuth, antimony, tin and precious metals for their downstream recovery. Therefore, lead metallurgy is key for the raw material supply that our society demands. Lead smelters, excluding lead-acid battery recyclers, tend to process more complex primary and secondary raw materials, which are mostly processed via the pyrometallurgy route. Accordingly, understanding the slag system of these metallurgical processes is key for the efficient industrial operation and recovery of minor elements. Glencore Nordenham is an integrated lead and zinc smelter in northern Germany with a production of 92 000 t of lead and 164 700 t of zinc in 2022. The lead production line processes complex leadbearing raw materials through the direct smelting process. Firstly, the feed mix is smelted in a Top Submerged Lance (TSL – Ausmelt®) furnace, where a lead bullion containing minor metals and a lead-rich slag are produced. Then, the lead-rich slag from the TSL is tapped (via launder) into a Side- Blown Furnace (SBF), where lead oxide is reduced to produce lead bullion (with minor elements) and discard slag. The lead bullion from both stages is refined to produce lead (>99.9 per cent) and recover the minor elements (Cu, Ag, Au, Sb, Te, Bi etc). This paper reflects the experience of operating the SBF after the first five years of operation and describes its ‘PbO-SiO2-FeOx-CaO-ZnO’ slag system. Firstly, the slag system, the furnace operating region and the potential solid phases present are discussed from a theoretical point of view. This theoretical study has been performed using FactSage™ 8.2 and the database developed by the Pyrosearch group at the University of Queensland, Australia (UQPY). Then, the FactSage™ simulations are compared with industrial slag measurements. Finally, some examples on how the slag knowledge gained at Glencore Nordenham can help the industrial operation of the SBF are discussed.

Jun 17, 2024

By J Lombardi

OZ Minerals' Prominent Hill copper-gold concentrator is located 130 kilometres south east of the town of Coober Pedy in the Gawler Craton of South Australia. The concentrator was built in 2008 and commenced commercial production in early 2009. The Prominent Hill concentrator is comprised of a conventional grinding and flotation processing plant with a 9.6Mtpa ore throughput capacity. The flotation circuit includes six rougher cells, an IsaMill for regrinding the rougher concentrate and a Jameson cell heading up the three stage conventional cell cleaner circuit. In total there are four level controllers in the rougher train and ten level controllers in the cleaning circuit for eighteen cells.Generic proportional – integral and derivative (PID) control used on the level controllers alone propagated any disturbances downstream in the circuit that were generated from the grinding circuit, hoppers, between cells and interconnected banks of cells, having a negative impact on plant performance. To better control such disturbances, FloatStar level stabiliser was selected for installation on the flotation circuit to account for the interaction between the cells. Multivariable control was also installed on the five concentrate hoppers to maintain consistent feed to the cells and to the IsaMill. An additional area identified for optimisation in the flotation circuit was the mass pull rate from the rougher cells. FloatStar flow optimiser was selected to be installed subsequent to the FloatStar level stabiliser. This allowed for a unified, consistent and optimal approach to running the rougher circuit. This paper describes the improvement in the stabilisation of the circuit achieved by the FloatStar level stabiliser by using the interaction matrix between cell level controllers and the results and benefits of implementing the FloatStar flow optimiser on the rougher train.

Aug 8, 2011

By M Darvall

Magnetite ore blending has yielded signifi cant performance improvements in OneSteel’s magnetite concentrator. The magnetite concentrator beneficiates magnetite ore from the Iron Magnet Deposit and produces concentrate, which is pelletised, then fed to the OneSteel Whyalla blast furnace. Concentrator feed variability severely detracts from the concentrator’s performance, affecting both concentrate yield and grade, which impacts on all downstream processing costs.A coordinated approach has integrated mine planning, geological modelling and grade control, to minimise concentrator feed variability, through effective ore blending throughout the mining and stockpiling process.Mine planning personnel design shots that extend the full width of the orebody and hence across the stratigraphic profi le. Based on geological information contained in block-outs and in consultation with Geology, the Grade Control team allocates material to each primary stockpile, potentially from every stratigraphic domane in the orebody. This ensures primary stockpiles are designed with maximum practical homogeneity and consistency.Using only primary movement, the allocated ore is stockpiled in a layer-cake fashion. The ore is pimple dumped across the width of the stockpile footprint and on completion of a layer, it is dozed flat with an access ramp that allows dumping to commence on the next lift. The primary stockpiles are reclaimed normal to build direction and the magnetite is crushed, all in, to a concentrator feed stockpile.The ore is sampled at the crusher from a falling stream cut. These assay data, are used for benchmarking and control charting the grade and variability of concentrator feed stockpiles. The concentrator feed stockpiles have demonstrated a statistically signifi cant reduction of within pile variation, between pile variation and pile to pile variation, primarily attributable to the development of ore blending. The concentrator has seen sustained, improved performance as a direct result, which translates into lower concentrate cost per tonne and improved yield and quality.

Jul 11, 2011

By C Paoletti

About 15 years ago the debate on the reliability of sampling procedures for agricultural food and feed commodities was initiated by a few brave scientists who questioned the representativeness of what, at the time, were routine sampling procedures established exclusively on the basis of tradition and practical feasibility. Over time several national and international organisations contributed to the discussion, developing standards and publishing papers either to underline the fact that sampling is always a source of error, in itself, which cannot be overlooked, or to minimise the relevance of sampling on the basis of argumentations linked to time and money limitations. The latter dominated, but is nevertheless impossible to accept from both a scientific and a responsible management perspective. Here the author presents an historical overview of these past 15 years, illustrating the most controversial issues, reporting major achievements in food/feed sampling, highlighting milestones, as well as unresolved problems that still need the attention and contribution from the sampling community. The need to incorporate Theory of Sampling (TOS) into food/feed safety assessment (pre-market), as well as into food/feed safety monitoring (post-market) has recently been highlighted, and the practical applicability of TOS to base food/feed safety decisions on representative sampling, has been explored and documented via concrete examples of risk analysis in different areas of food/feed industrial production chains. Now it is time to move forward and ensure that TOS is fully integrated into the well-established Food and Agriculture Organization (FAO) / World Health Organization (WHO) risk assessment approach, in order to guarantee a transparent and correct universal frame for risk assessment and the subsequent management decision-making process. WCSB8 offers the ideal platform to explore the best way to do so, switching from a theoretical discussion of correct sampling principles for food and feed agricultural commodities to practical recommendations in the interest of consumers, worldwide. These 15 years have also been a personal journey of interesting dimensions, indeed a veritable roller-coaster ride in-and-out of the scientific, technological, industrial and (last but not least) regulatory worlds. The start was WCSB2 in 2004, when I flew to Australia to discover if in other areas sampling had been identified as an unavoidable issue and, if so, what the solution was. There, I found a good travel companion who today is still on my side, to assemble the puzzle and explore how to shape the future, to concretely answer to the 15 years’ quest for proper sampling in the assessment and monitoring of food/feed safety.CITATION:Paoletti, C, 2017. Assessing and monitoring food and feed safety – a 15 year quest for proper sampling, in Proceedings Eighth World Conference on Sampling and Blending , pp 39–44 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By C Smith, J Cilliers, K Hadler

Unstable flotation froths, that burst before they overflow, produce no concentrate. Increasing the froth stability to improve recovery is therefore an obvious control strategy. Froth stability can be measured readily as the fraction of air entering the flotation cell that overflows as froth, rather than bursting on the surface; the ‘air recovery.’ Air rate is one of the most significant variables affecting froth stability. It is interesting that froth stability (air recovery) is maximised at a specific air rate, above or below which it decreases. It is important for metallurgists to realise that this maximum froth stability also produces the maximum mineral recovery, without compromising concentrate grade. Flotation cells must be operated at the air rate that produces the highest air recovery. The peak air recovery (PAR) to maximum mineral recovery relationship was first demonstrated by Hadler and Cilliers in 2009. Since then, the relationship between PAR and flotation performance has been widely explored; varying air rate, froth depth and particle size. Industrially, reducing the flotation bank air rate to achieve PAR yielded better mineral recoveries than other down-the-bank air rate profiles. In this paper, we present an overview of these key developments and findings in flotation optimisation based on PAR. Furthermore, using new industrial data, we show that PAR is not just applicable to rougher-scavenger cells, but also to flotation columns. Finally, we consider the future application of such an optimising control concept. CITATION:Smith, C, Hadler, K and Cilliers, J, 2018. Flotation control using froth stability: past, present and future, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 441–454 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By F Hungerford, T Ren

"Gas management has always been a major concern for the ventilation officer of any gassy mine. With an increase of mining depth and gas content, there is a great demand for the development of in-seam drilling sites where boreholes can be drilled for the pre-drainage of gas prior to longwall operation. The ventilation and gas management in the drilling site therefore becomes a critical component of mine safety. In this study, advanced computational fluid dynamics technology was adopted to investigate the aerodynamics of gas emitting from the drilling site and boreholes during normal drilling and, in the case of a sudden gas inrush, from the borehole. In addition, the impact of different ventilation controls on gas removal in the drilling site was investigated. Modelling results indicate that gas accumulation zones could be formed if the ventilation system fails to deliver sufficient airflow to the drill site, especially when a sudden gas inrush from a borehole occurs. The configurations of brattice, layout of ventilation tubes and the gas emission rate all have a significant effect on the gas distribution. Due to variations in site-specific conditions, it would be desirable to conduct modelling studies to assess the effects and efficiencies of a ventilation design for the varying environment on-site before carrying out drilling practice. CITATION: Ren, T, Hungerford, F and Wang, Z, 2015. Computational modelling studies of ventilation management for underground in-seam drilling sites, in Proceedings The Australian Mine Ventilation Conference, pp 239–250 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 31, 2015

By T Stambolie

Mine planning processes are continuously evolving, increasing in complexity, and are required to be developed in shorter timeframes, often missing important steps in the process. Underground coal mines are also moving into more challenging environments, with the more favourable resources having been exhausted. In addition to traditional mine planning processes there is an increasing level of complexities associated with parallel systems including the preparation of Joint Ore Reserves Committee (JORC) compliant estimates (JORC, 2012 and Guidelines Review Committee, 2014) or seeking critical regulatory development consent to undertake mining. There is a clear link between geotechnical considerations and success of mining operations, and therefore it is essential that such considerations are elevated in both status and priority. It is obvious that geotechnical considerations are paramount in any mine, however it is imperative to accept that such considerations, and the collection of information relating to such, are undertaken from the onset of any mining project. CITATION:Stambolie, T, 2018. Elevating geotechnical considerations in the Australian underground coal industry and mine planning process, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 383–391 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By E P. O’Dwyer

Segment and gasket lining in tunnel boring machine (TBM) tunnels; and sheet membrane lining systems in driven tunnels are robust waterproofing systems each with a proven history of performance in Australia and further afield. Where an interface between these two systems occurs, the potential for costly failures is vastly increased and additional attention to detail is required in design, planning and construction. TBM cross-passages represent the most common occurrence of this interface, with steel compression flanges and neoprene gaskets being the typical means of connecting the waterproofing systems. There is a large variance in both detailing these flanges and associated outcomes, which makes this an area where there is room for improvement within the industry.The paper will look to tease out the various issues associated with this interface and how they can be dealt with efficiently with appropriate design measures, robust planning and carefully controlled construction methods.The paper will also look to review the new technologies and systems currently being put forward as potential alternatives, including an epoxy tape system, which has recently been successfully trialled on a project in Europe under high-pressure head.CITATION:O’Dwyer, E P, 2014. The challenge of waterproofing cross passages in segmentally lined tunnel boring machine tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 315–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By J Bolen, I Cameron, M Huerta, M Okrutny, K O’Leary

As greater amounts of fine iron ore concentrates enter the marketplace, new investments in iron ore pelletising capacity are inevitable to deliver these concentrates to steel industry consumers. When investors assess the two well-proven pelletising technologies, the straight grate and grate-kiln, the most appropriate choice may not be immediately evident. Certain technical, market and site-specific factors will favour one technology over the other; investors need to be aware and understand these factors in order to make the best investment decision. Hatch has compared the merits of both technologies regarding plant configuration; type of iron ore processed; energy consumption and flexibility to use a variety of fuels; ability to produce the required pellet quality; required plant capacity and scale; operating and capital costs and environmental performance. A technology assessment checklist that investors should consider when making a new pellet plant investment decision is presented.CITATION:Huerta, M, Bolen, J, Okrutny, M, Cameron, I and O’Leary, K, 2015. Guidelines for selecting pellet plant technology, in Proceedings Iron Ore 2015, pp 45–52 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By M K. C Roberts, M G. Magwaza, J W. L Hanekom, P Piper, R Lousteau

Due to the perceived potential to extract the second economic manganese seam at its Black Rock Operations in the Northern Cape Province, South Africa, Assmang commissioned an investigation with respect to mining method and sequencing of the two orebodies in 2007. Based on this initial study into multiseam potential, conditions and impacts, the rock engineering aspect was expanded to determine conceptual rules to govern the extraction of both manganese seams using the normal bord-and-pillar layout implemented at this operation. This work included the theoretical analysis using basic pillar design practices and numerical modelling, including the use of Map3D, UDEC and Phase2 codes.In 2013, Assmang launched a large-scale investigation into the potential to increase mine output from all possible manganese sources at the operation. Included in this investigation was the requirement to confirm or modify the conceptual multiseam extraction rules to implementation. As part of this confirmation process, stress measurements, borehole camera audits and additional numerical modelling were performed at a particular site on the operation where a limited extraction of both seams had been undertaken. The results obtained from this process provided confidence in the conceptual extraction rules and allowed the derivation of final extraction rules that will be implemented at the operation as the multiseam mining process becomes more widespread.CITATION:Hanekom, J W L, Roberts, M K C, Magwaza, M G, Lousteau, R and Piper, P, 2014. Confirmation of multiseam extraction rules for Black Rock Manganese Operations, Assmang, Northern Cape, South Africa, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 107–116 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By R Dimitrakopoulos, K Kawahata, L Montiel

A method that optimises mining complexes that are comprised of multiple processing destinations, open pits and underground operations is presented. Mining, blending, processing and transportation decision variables are simultaneously optimised while accounting for geological uncertainty. The method uses a simulated annealing algorithm at different decision levels to generate a stochastic-based extraction sequence and processing policies. A case study shows its ability to generate a higher net present value while facing a reduced amount of risk when compared to traditional optimisation methods.CITATION:Montiel, L, Dimitrakopoulos, R and Kawahata, K, 2014. Globally optimising open pit and underground mining operations under geological uncertainty, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 201–212 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By C Czerny, T Elkington, L Lorenzen

The Dutwa Nickel Project is a nickel laterite atmospheric leach project located in Tanzania that has been under development by African Eagle Resources plc (2012). A bankable feasibility study (BFS) has been progressed to evaluate mining of the resource (107 Mt at 0.92 per cent Ni) followed by hydrometallurgical processing on-site to make a mixed nickel-cobalt intermediate product. The unique relatively high silica contents in the Dutwa deposits, as opposed to limonite, which is more commonly occurring in nickel laterites, presented the possibility for beneficiation of the ores to enhance the leach feed nickel grades and provide economic benefits in terms of operating and capital cost efficiencies.Geometallurgical relationships, based on the results of an extensive variability metallurgical test work program for beneficiation and leaching, were developed for the BFS, which resulted in an improved understanding of ore classifications within the deposit and their responses. The geometallurgical information obtained has been instrumental in making key preliminary techno-economic decisions, such as forecasting whether or not mined material should be beneficiated and was ultimately used to drive the mine plan towards the prioritisation of areas within the deposits that delivered the best cost efficiencies and overall project economic outcomes.CITATION:Elkington, T, Lorenzen, L and Czerny, C, 2013. The use of geometallurgical relationships in process route selection and mine plan optimisation for the Dutwa Nickel Project, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 207-216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By P J. Fairfield

This paper reflects on the author’s experience working in site-based technical and management roles over a 29 year period, and the past 12 years in internal and external consulting roles. It discusses the author’s experiences and observations of operations management, and the significant value of the technical specialist’s role in providing management with information on what to base tactical decisions, which may or may not be part of a defined strategy.The landscape of mine management changes with the cyclical nature of commodity prices driving operating and capital prudence, as operations change their focus from expansion and growth to staying in the game. The role of the mine manager and management team in navigating through these changing times, attitudes and stages of the project life can influence the success or otherwise of many projects.Technical knowledge is one of the key drivers in realising or destroying the value of a project or operation. As managers focus on people management, management systems and processes, recognising and understanding value in underlying technical knowledge, and getting back to the fundamentals/basics, can be overlooked. In reaction to the fluctuating commodity cycle, managers implement changes through optimisation, fast tracking or parallel streaming, expansion projects and changes in the application of technology. These responses occur against the background of changes in the appetite for risk, acceptance of project uncertainty and changes in personnel which result in a loss of knowledge and experience – often at critical times.This paper shares the author’s experiences and lessons learnt in dealing with and observing these issues. The author questions whether we really understand our projects and are valuing the most important asset, our people and, in particular, the technical specialist and their experience and knowledge.CITATION:Fairfield, P J, 2016. Staying in the game – the importance of engineering-based decisions, in Proceedings International Mine Management Conference, pp 67-74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By A M. Mueller

St Helena tunnel is the centrepiece of the Pacific Highway upgrade from Tintenbar to Ewingsdale, abbreviated and commonly known as T2E. At the deepest point the twin tunnels run 45 m below the ridge line of St Helena Hill, located about 5 km west of Byron Bay. The tunnel breakthrough was achieved early in 2014 and the works for permanent lining will be completed in early 2015.Once the project will be handed over to the public in 2015, T2E will deliver a safer highway and uninterrupted traffic flow between New South Wales and Queensland. The design speed in the project area has been set to 110 km/h by the client Roads and Maritime Services (RMS), which will reduce the travel times between Brisbane and Ballina to just over two hours.The two tubes of the tunnel have been designed to accommodate three lanes in each direction with shoulders and walkways on either side of the carriageway. These requirements result in a huge cross-section of about 20 m width and an excavated area of about 210 m2.With the tunnel alignment being situated in basaltic rock, St Helena tunnel is conventionally driven. The selected excavation method was predominantly drill-and-blast with temporary support being installed immediately after the excavation. Despite the wide span of the tunnel, the geology allowed the tunnel perimeter to be supported by only rock bolts and a layer of shotcrete over the majority of its length.Due to environmental reasons one of the approval criteria of the project was that the tunnel must not have a detrimental long-term impact on the groundwater system within St Helena Hill. Consequently the tunnel has been designed as a fully tanked structure with a waterproofing sheet membrane installed on the temporary shotcrete.The permanent structure of the tunnel has to meet a 100-year design life and it is designed as a cast in situ concrete lining. Considering the water pressure on the lining the concrete is reinforced with a significant amount of bar reinforcement.The presented paper provides a more detailed explanation of the geology and the consequential temporary and permanent support measures together with the waterproofing system.CITATION:Mueller, A M, 2014. Pacific Highway upgrade from Tintenbar to Ewingsdale (T2E), St Helena Tunnel, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 419–424 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By A Riles

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

Jun 15, 2016