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By S Hapugoda, J R. Manuel, M P. Ma, L Lu

Iron ore sinter quality depends heavily on the mineralogy, textures and physical structure of the sinter, which is formed upon solidification of the primary sinter melt. The interactions of the initial sinter melt with its surrounding materials will impact on the properties of the primary sinter melt and consequently the solidified structure of the sinter. By using a high-temperature visualisation system, in situ studies have been conducted on the effects of melt compositions (Al2O3, SiO2 and MgO) on the interfacial phenomena of the sinter melt on a natural iron ore substrate. It was found that the melt composition significantly influenced the wettability between the sinter melt and the iron ore substrate. The interactions between the sinter melt and the natural iron ore substrate were also examined. Such interactions can lead to further changes of sinter melt composition and hence the sinter melt properties that, in turn, further affect the wetting behaviour of the sinter melt.CITATION:Ma, M P, Lu, L, Hapugoda, S and Manuel, J R, 2013. Effects of melt composition on the interactions of sinter melt on a natural iron ore substrate, in Proceedings Iron Ore 2013 , pp 431-440 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

To enable ammonium nitrate-fuel oil (AN-FO) to be used on an equal weight basis with nitroglycerine explosives, smaller diameter bore holes became necessary with consequent modifications to drill steel and burden on holes. Detonation of AN-FO in small diameter holes proved successful both with and without primer charges but some alterations were required to adapt anoloders to the smaller holes.Important factors in training all operators in the new charging method were the retention of improved fragmentation, avoidance of excessive overbreak and keeping wall rock dilution to an absolute minimum. The successful storage of ammonium nitrate in climatic conditions with daily temperature fluctuations above and below the critical 90°F has been achieved.INTRODUCTIONTechnical aspects of ammonium nitrate-fuel oil (AN-Fa) blasting agent are well covered in recent literature. This paper deals primarily with the manner of its introduction as the principal explosive underground at Great Boulder Gold Mines Ltd. and with the many problems encountered in the process. Following reasonably successful experimental firings in June 1962', using granular ammonium nitrate and an anoloder, permission was granted by theWestern Australian Mines Department to carry out test work in selected areas of the mine. The permit allowed for fuse firing only, and for a mixture of AN-Fa containing between 5t and 6 per cent fuel oil, with an adequate primer.The use of AN-Fa on an equal weight basis with nitroglycerine explosives, involved smaller diameter holes with alteration to ground burden and modification to drill steel.Initial tests indicated that it was apparent that AN-Fa could not replace gelignite on an equal weight basis if the...

Jan 1, 1965

By B Putland, I Lovatt, D Schwann, A Cervillin

The Mount Carlton project in Queensland's North East sits on a high-sulphidation epithermal style deposit rich in gold, copper and silver. Mt Carlton is an open pit mining operation with ore processed using a primary crusher, single stage SAG mill and flotation to produce a concentrate for sale. Orway Mineral Consultants (OMC) was involved in the original design of the comminution circuit and the project was commissioned in late 2012, with first concentrate shipped in March 2013. When Evolution sought to optimise the project in 2015, OMC was invited to assist by undertaking a circuit review to identify opportunities for the optimisation. During 2016, the Mt Carlton site team implemented the optimisation strategies developed in conjunction with OMC. These included reconfiguring the SAG mill discharge arrangement, reducing the average ball diameter and allowing the mill to operate at higher speed and under more autogenous conditions. Cyclone operation was changed to constant pressure and the vortex finder size was decreased. The combined strategies improved energy efficiency and allowed higher SAG mill power utilisation. The additional power has been used to increase throughput by 2.4 per cent while achieving a 27µm reduction in product size (P80) to gain downstream recovery improvements. The reduction in grind size has been achieved with only 6.8 per cent increase in specific energy consumption because of a 6.5 per cent increase in grinding efficiency. The circuit product size is also notably more consistent due to the improvements made to the cyclones, providing benefit to the downstream flotation circuit. A significant decrease in ball consumption was also gained, saving hundreds of thousands of dollars a year in operating cost.This paper will discuss the circuit design, start up and will detail the changes made during the optimisation and why these were successful.CITATION:Putland, B, Lovatt, I, Cervillin, A and Schwann, D, 2018. Mount Carlton comminution circuit design, start-up and optimisation, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 517–528 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By M Edhammer

In 2007, Atlas Copco introduced an integrated tunnel scanner/profiler. The tunnel scanner, which is integrated into the control system, is mounted on the drill rigs, and replaces the previous variants of non-integrated scanner equipment. The Atlas Copco Tunnel Profiler, which is the name of this system, is currently being used by several contractors and mines on various projects in Scandinavia, Finland and Australia. Atlas Copco Tunnel Profiler can scan a tunnel of 65 m2 in just five minutes and is integrated with the computerised control system for the drill rig. This integration means that the results of scanning are immediately available for analysis on the computer screen both in the drill rig and in Tunnel Manager; a software for tunnel and drift planning.In 2008, a method was introduced for locating the drill rig with a total station navigation (TSN) system, integrated into the control system. TSN systems are used by a number of contractors in Scandinavia and Finland, as well as elsewhere in the world. Using a TSN for navigation is in itself not new, but when this is integrated with the control system it provides the opportunity for individual drill rig operators to use this method, without the direct assistance of a surveyor. TSN gives a very precise indication of the drill rig’s position in relation to the tunnel design. An accuracy of ±1 cm compared with the ±10 cm which is normally obtained with the traditional method using tunnel laser and sight plates on the drill rig’s feeder. The closer a tunnel is blasted to its planned profile, potentially the more is saved in terms of less shotcreting, extra rock bolting and other corrective work. A better quality tunnel is the key to better overall economy and today’s technology makes it possible to achieve that goal in every type of tunnelling and mining project.In addition to total station’s ­navigation and Tunnel Profiler, the concept of ‘high precision tunnelling’ also includes:•Software tunnel planning: Tunnel Manager, Tunnel Manager Pro and Tunnel Manager Measure while drilling.•Measurement While Drilling (MWD)collects the various drilling data and the interpretation of these for the early identification of variations in the rock.•Rig Remote Access (RRA) is a support for wireless or wired communication between drill rig and planning office. The result is being able to send planning data to the drill rig and to simultaneously have the facility for logged files to be sent from the rig to the office. There is an option of an external computer logging in to the drill rig’s control system to view menu screens and settings, and remotely troubleshoot and plan appropriate action.

Mar 21, 2011

By S Lloyd, J Chow, S Fitzpatrick, D Greenup

The Tropicana deposit was discovered in 2005 after AngloGold Ashanti followed up an unexplained gold-in-soil anomaly. Discovered in a remote, barely-explored area of Western Australia not previously thought prospective for gold, Tropicana is the most significant gold find in Australia for more than a decade. The new, large scale open pit gold mining operation will produce an annual production of around 330 000 to 400 000 oz over a ten year mine life mining around 60 Mt/a.Process plant construction started in early 2012 and is due to finish in the December 2013 quarter. The mining contract was awarded to Macmahon Holdings (Macmahon) and mining commenced in July 2012 using conventional drill and blast, truck and excavator open cut methods.As a construction and start-up project in a greenfields location, the establishment of mining activities at Tropicana Gold Mine (TGM) involves the implementation of technical and operational systems, including the mining contract. Some of these systems and likely challenges were identified during earlier studies, while others were not foreseen until they were encountered. Alternatively, the time frames around implementation change depending on the changing knowledge of the project and industry environment. These systems include those common to the industry and those specific to the operation and location.This paper examines the implementation and development of a number of the systems specific to the establishment of mining operations, including the history, process and some outcomes. Although expected to be discrete systems to implement, they become interdependent. This linkage between systems further offers challenges and opportunities for the continuous progress of each system and for TGM as a whole.CITATION:Chow, J, Fitzpatrick, S, Greenup, D and Lloyd, S, 2013. Tropicana Gold Mine - mitigating the challenges of a mining start-up, in Proceedings World Gold 2013 , pp 51-60 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By D Yates, C C(te, M Rodgerson

This paper describes how specific technical and regulatory issues related to water management have been dealt with at Anglo AmericanÆs Moranbah North mine. It compiles the collection of practices that have been implemented since 2010 in response to climatic and regulatory drivers. Operations must continually evolve as they face emerging challenges. For Moranbah North mine, one key challenge is the integration of its mine water system to that of its new neighbouring mine Grosvenor. The commitment to ongoing improvement has placed the mine in a good position to face this particular challenge.Water-related risks were identified then mitigated by technical practices, which have focused on improving underground water management, increasing storage capacity and installing a state-of-the-art control system for the management of water on-site and for releases of mine-affected water to the environment. These practices are supported by an extensive monitoring and audit system that provides confidence in the reporting of activities and outcomes. The strategy has helped the operation with its continual attempts to minimise reliance on high-quality third-party water and improving its interaction with the surrounding environment and community.CITATION:Rodgerson, M, Yates, D and C(te, C, 2013. Leading practice water management at Moranbah North Underground Mine, in Proceedings Water in Mining 2013 , pp 301-310 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By L J. de Lange

As a material asset for mining entities, the resources and reserves (RR) estimation processes are surprisingly underrepresented in the assurance landscape. When press reports expose them being inaccurately reported, or in merger and acquisitions processes, their importance becomes clear. The impact of erroneous RR numbers (both positive and negative) could have a material impact on an entity’s reputation and value.The technical nature and ‘black magic’ connotations of the RR estimation processes are possibly reasons why audit committees are not actively involved with it. Internal auditors avoid the RR processes for similar reasons. Also the traditional approach to obtain assurance on RR is expensive and is therefore only performed when it is absolutely required.However, stakeholders’ expectations of good governance are growing. Part of this increased focus is based on attaining a higher degree of certainty about the current and forecasted position of the entity. Stakeholders are also increasingly more interested in non-financial areas of entities, as the future success of an entity is more than a set of financial metrics.Consequently, the RR estimation processes should be visible on the agendas of audit committees. Monitoring of key controls is required as part of the governance obligations for senior management and the audit committee. So once it is on the audit committee’s agenda, the question then becomes, how will that agenda be supported by an assurance process that is cost-effective?The main objective of the paper is to describe a model of RR assurance that has been effectively applied in some mining companies. The paper discusses one particular approach that provides an audit committee with the required assurance regarding RR processes. The approach ties the assurance needs of the audit committee to the needs of the technical experts in the entity, therefore involving two important figures. It also offers assurance providers with a model to audit ‘through’ the RR processes rather than ‘around’ them. The paper then discusses top-down and bottom-up approaches that provide assurance at different levels of an entity.A governance audit that focuses on the RR processes is suggested as a top-down approach. A bottom-up approach assesses the design adequacy of internal control processes. A hybrid model is described which meets the needs of diverse stakeholders including the audit committee and the RR community.The hybrid model combines the expertise of professionals in both internal audit and RR. The right balance of these skills directed by a singular approach ensures that a credible result is achieved.This approach is not as expensive as some verification approaches used in the industry and can, as a result, be performed on a more regular basis.The last element of the paper looks at implementation of the reporting mechanism. An assurance process aimed at continuous improvement further enhances the robustness and reliability of RR reported by an entity.CITATION:de Lange, L J, 2016. Resources and reserve assurance processes – a framework for improved governance, in Proceedings International Mine Management Conference, pp 21-34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By P Gomez, R Baumgartner, G Escobar

"The Cerro Corona mine consists of a Cu-Au porphyry deposit located in the Andes of northern Peru. The deposit comprises a typical Cu-Au multiphase porphyry mineralisation that has been overprinted by an epithermal event. This has generated a complex pattern of argillic alteration facies, which was accompanied by a locally structural-controlled Au-Cu mineralisation with the presence of gold and limited Cu sulfides and sulfosalts. These features, along with the porphyry-style mineralisation, produced a multifaceted occurrence of gold.Since the beginning of operations at Cerro Corona in 2008 there has been a continuous improvement of the geological and mineralogical knowledge. All mineralogical studies have mainly focused on host rock types and, to a lesser extent, alteration minerals, but little work has been done on the mineralisation itself. As a consequence, limited mineralogical information was available for use in the process optimisation initiatives.In the last two years, a series of mineralogical characterisation studies were undertaken with two main goals. First, to gain an understanding of the mineralisation genesis and second, to obtain a detailed characterisation of copper and gold minerals to support ongoing process optimisation. The first goal was achieved by conventional optical microscopy while the second required electronic microscopy and other microanalyses due to the necessity of quantifying several minerals of interest for the processing.The results were used to refine pre-existing geometallurgical domains, explain copper and gold losses in the flotation process and to some extent, improve copper and gold recoveries. The mineralogical characterisation is an ongoing work. Mineralogy provides the basis for any optimisation exercise since it looks in detail at the material to be treated and therefore, should be part of all geometallurgical programs.CITATION:Baumgartner, R, Gomez, P and Escobar, G, 2016. Comprehensive Mineralogical Characterisation at the Cerro Corona Cu-Au Porphyry Mine – the Fundamental Key for Geometallurgical Applications, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 221–230 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By J Young, S Yu, P Moyo, M Powell, A Musunuri, B Bonfils, S Kanchibotla, P Yaroshak, V Jokovic

The appropriate design of liners continues to be an issue on many mills worldwide. Loss of milling capacity especially at liner change, uneven wear lives along the mill, substantial scrap on worn liners, excess mill down-time, undesirably short and unreliable wear lives are all common issues. This paper presents a designed approach to liner optimisation that follows a logical path of initial design and step-wise improvements based on liner wear monitoring. The target is to have a good liner design from start-up, then tune the profiles, heights and thicknesses based on wear monitoring. This is conducted as a team of liner specialist, site personnel and liner supplier. The application to the Pustynnoye SAG mill of JSC Altynalmas in Kazakhstan is presented. The increase in liner life by around 50% along with increased mill throughput of over 20% illustrate the huge benefit of the cooperative triumvirate approach through the gains that can be made in productivity and reduced liner costs.CITATION:Powell, M, Kanchibotla, S, Jokovic, V, Hilden, M, Bonfils, B, Musunuri, A, Moyo, P, Yu, S, Young, J, Yaroshak, P, Yalcin, E and Gorain, B, 2018. Advanced mine to mill application at the Barrick Cortez mine, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 177–196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By P Wood, S Leveritt

This paper will introduce some innovative strategies for simulator training that are intended to improve the level of safety and operational performance of heavy equipment operators. The key strategy is to design simulator training to deliver improved work performance outcomes. This strategy is underpinned by a process for engaging workers in knowledge discovery and transfer that has been developed as an outcome of an Australian Coal Association Research Program (ACARP) funded project conducted at open cut coal mines in Australia. The process is expected to deliver improvements in the safety and operational performance of heavy equipment operators by informing training content about how experienced operators manage unexpected situations around the site. Tapping into the tacit knowledge that experienced operators gather over time can provide site specific and timely information about situational cues used to manage the unexpected. This type of information complements basic skills training by helping the trainee understand the operational context in which the acquired skills will be applied. Inexperienced operators have traditionally gained experience through their own actions, observing the actions of others and by taking the advice of mentors who have æbeen there, done thatÆ and developed operational decision making skills for safe and productive work performance. Leadership and mentoring techniques that contribute to effective knowledge delivery will also be discussed.Other simulator training strategies include refresher training, change management, emergency response training and testing the usability of new equipment and technologies prior to their introduction on-site. A key challenge ahead for the resources sector is the development of knowledge elicitation techniques that suit the operational workforce. A challenge for simulation and modelling professionals is to develop and refine techniques that support cost-effective customisation and regular updates of simulator scenarios.CITATION:Leveritt, S and Wood, P, 2012. Raising the simulator training bar - Strategies for improved work performance and effective utilisation of site-based simulators, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 65-70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

It is no longer adequate when starting a new mine to simply select the best equipment. Today's competitive international commodity markets demand superior efficiency which requires systematic involvement of people in continual improvement of production and commercial processes. True Total Quality of Management (True TQM) principles provide an operating philosophy for maximising productivity and minimising unit costs of output. The presentation will show the practical and successful use of these principles. This paper will introduce the case study and provide background material on True TQM.

Jan 1, 1995

It is no longer adequate when starting a new mine to simply select the best equipment. Today's competitive international commodity markets demand superior efficiency which requires systematic involvement of people in continual improvement of production and commercial processes. True Total Quality of Management (True TQM) principles provide an operating philosophy for maximising productivity and minimising unit costs of output. The presentation will show the practical and successful use of these principles. This paper will introduce the case study and provide background material on True TQM.

Jan 1, 1995

By H Zhang, A Lawrence

To accommodate the fast growing need for services in Singapore’s Marina Bay downtown area, Marina South, the construction of a common services tunnel (CST) was required. The CST includes various services such as telecom cables, power lines and water pipes. A deep excavation and temporary earth retaining system (TERS) was required to facilitate the construction of the tunnels. Marina Bay is reclaimed land over thick soft marine clay which is likely to be still consolidating. The deep soft marine clay poses a big challenge for deep excavations in downtown areas where highways and sensitive structures are close by. This paper presents a case study of part of the CST Phase 1B and 2 at Marina South, in particular a 26 m deep excavation supported by a 46 m diameter temporary caisson. The construction started in late 2006 and the basic structure was completed in early 2011. The caisson was formed by 1.0 m thick overlapping diaphragm wall panels with a capping beam and three ring beams at different depths. Two-dimensional finite element analyses were conducted to predict the ground settlement, lateral displacement, bending moment and hoop stresses in the diaphragm wall and ring beams during different excavation stages. A comprehensive instrumentation and monitoring scheme was established to verify the design predictions, control excavation safety and trigger the contingency plan to protect public safety. The impact of construction activity, unbalanced temporary stockpiles and adjacent deep excavation for a mole removal will be discussed.CITATION:Zhang, H and Lawrence, A, 2014. A case history of a deep excavation in a big circular shaft in Singapore marine clay, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 581–588 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By D J. D'Astoli, M D. Goodz

In 1993 a detailed review of drill sample yuuluy was rouxluard through twin and triplet drill holes using open hole, crossover suhreverse circulation (RC) and diamond drill methods. Advances in face-sampling RC methods demanded a further review of the validity and reproducibility of drill sample data. A program was undertaken to drill three RC holes using the latest technology (new face- sampling bits, dust suppressers, cyclones and compressors). Volumetric and mass studies were undertaken to review sample recoveries. Modal analyses on indicator minerals were logged to interpret the relative degree of mineralisation. Ambiguities in the results were immediately apparent and the consensus was for follow-up twin diamond holes using HQ3 coring tubes. The most mineralised RC hole was selected for the first twin diamond hole. This RC hole (MS 313) encountered one intersection of >0.47 g/t; in contrast the diamond hole (MS 342) had nine intersections at > I g/t. Results at hand show definitively that face-sampling RC drilling is not acceptable as a method of exploration for gold deposits of the Woods Point type. Furthermore it is demonstrated that RC drilling should not be used for any type of exploration of high-grade gold vein deposits related to highly fractured or porous hostrock, or areas of previous mining activity. Methods are proposed for reviewing of rates of sample recovery, distribution and cross-contamination. Comparisons also show that in limited metreage reconnaissance drill programs, diamond drilling is more similar to percussion in per metre costs, than it is credited with, and always provides more bang for the Buck.

Jan 1, 1997

By I D. Gregson, A Gandhe, A S. Garcia, K M. MacAndrew

"Falls of ground still cause around one-third of all underground mining fatalities. The recent introduction of mechanised room and pillar working into Indian coalmines is an example of the application of new design by measurement and safety monitoring strategies, which can be used to reduce falls of ground risks in mines.Rock Mechanics Technology, now part of Golder Associates UK Ltd (Golder), is providing rock bolt support and pillar design services to the mines using a design by measurement approach. This involves in situ monitoring to confirm support and pillar designs and pillar extraction sequences.Site examples are given of the support designs determined and the monitoring programs undertaken for both design and safety.Routine safety monitoring of roof movement using telltales is also described. A new auto warning telltale has been developed specifically to warn of imminent caving as pillars are extracted.The approach used by Golder has played a major role in ensuring the success of these projects. As a consequence, mechanised room and pillar working is now firmly established in India, and wider application is planned to help meet future demand for coal.The experience confirms that the design by measurement method for this application has important advantages over conventional design approaches using analytical or empirical methods. Firstly, it measures the design performance or outcome rather than trying to calculate or predict it. Secondly, it provides the opportunity for the design to be adjusted to obtain the optimum outcome. Thirdly, it can do this at a local level, so that the support design can be matched to changing conditions to give the most cost-effective design. Finally, it incorporates long-term monitoring of support performance, again at a local level, so that subsequent change can be identified to enable corrective measures to be implemented in a timely manner and to ensure that ground control safety is maintained.CITATION:MacAndrew, K M, Garcia, A S, Gregson, I D and Gandhe, A, 2014. Application of design by measurement for support and pillar design in mechanised room and pillar coal mining in India, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 65–76 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

By T Baumgartl, J Burgess, B Emmerton, P D. Erskine

Large-scale open cut mining in the Bowen Basin has been undertaken for over 40 years. During this period, improved mechanical capability and economics have allowed extraction to greater depths, resulting in post-mining landforms of increasing height. Rehabilitation practitioners face significant challenges in stabilising these landforms and require a comprehensive understanding of the Bowen Basin Coal Measures strata likely to be disposed of during mining. Knowledge regarding the potential behaviour of differing spoil materials (following disturbance) provides a rationale to maximise short- to medium-term surface stability of constructed landforms by identification, salvage and advantageous reuse of cladding resources as a means to minimise erosional risks.CITATION:Emmerton, B, Burgess, J, Baumgartl, T and Erskine, P, 2016. Bowen Basin coalmine spoil classification for improved mine rehabilitation outcomes, in Proceedings Life-of-Mine 2016 Conference , pp 142–147 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By J Ross

The foundation of effective leadership is communication. You can have all the leadership theories, models and training you want, but in the end it is all about leaders talking to, listening to and understanding the point of view of those below and above them.The foundation of effective safety is peoples’ behaviours. Every incident, every near miss and every safe act comes down to what one person does and how that affects themselves and others. We tend to focus these behavioural considerations on the people at the ‘coal face’, those most in harm’s way. But it is the individual behaviours of everyone in the organisation, particularly those at the top, which are just as (if not more) important. The foundation of effective safety leadership in the mining industry is that it starts at the top, with the individual behaviours of leaders. The behaviours of each and every leader will be reflected in their teams. And where their teams are made up of leaders, these leaders will pass these behaviours on to their teams and so on. It’s the sum total of what people see their leaders do and what they do as a result, that creates the ‘culture’ of the business – and it’s this culture that makes or breaks how safely people work.

Mar 21, 2011

By R Kahnt, S Jahn, D Baacke, M Eckart

Relocation into the Lichtenberg open pit mine of about 110 million m3 of sulfide-bearing and ARD-generating waste rock piled up on the surface is the most important and cost-intensive single surface restoration project conducted by WISMUT GmbH at the former Ronneburg uranium mining site. The waste rock comprises for the most part Palaeozoic shales, limestones and diabases with pyrite contents of up to seven per cent. Waste pile relocation began in 1992 and is scheduled to be completed by 2007. The approach used for relocation has been extensively described elsewhere (Jakubick et al, 1997; Hockley et al, 1997; Chapman et al, 1998; Paul, 2003). Following completion of the backfill that will be up to 60 m above the initial ground level, a dry cover will be placed on top of the backfilled mine wastes. The area to be covered amounts to about 220 ha. Design planning for the final cover placement of which is to begin in 2004 had to be based on a comprehensive cost-benefit analysis over and above compliance with legal requirements. The crucial question to be answered in this respect was to determine û in addition to the expenditure required to ensure reuse, radiation protection and soil protection û the extent to which additional time, effort and money were justified in order to minimise contaminant release from the unsaturated portion of the backfilled pit contributing to total releases into the ground water and possibly achieve savings in long-term operating costs for the on-site water treatment plant. Optimisation was based on contaminant balance modelling for the entire site reproducing dominant physical and geochemical processes. Among the specifics underlying the cover design is that contaminant release from the backfilled open pit must not be considered independently of that from the adjacent flooded underground mine and that a major part of the backfilled open pit will also be submerged. Following weighing of cover-related short- and long-term costs it was found that higher construction costs for the various cover options will not be offset by cost savings in the long-term water treatment. As a consequence of pit flooding, even a costly multiple cover including an impermeable layer will only insignificantly impact on concentrations and loads at ground water spill over points. As a result of comprehensive studies and investigations, a combined cover of cohesive soil material from on-site excavation overlain by a 0.4 m thick storage layer to restore natural soil functions for revegetation was derived and submitted for approval. Together with hydraulic measures, this approach is to meet any requirement in terms of radiology, water protection, stability, erosion protection, and reuse.

Jan 1, 2003

By C Roche, G M. Mudd

The Morobe Province of central Papua New Guinea (PNG) has been mined for gold for nearly a century, although it is only in the past decade that large-scale modern mining commenced. The Hidden Valley gold-silver project began construction in mid-2006 and production by August 2009, and is located in the mountains above Wau in the headwaters of the Watut River. The mine is owned and operated by the Morobe Mining Joint Venture (MMJV), which also owns the Wafi-Golpu project, comprising the Wafi gold deposit and Golpu copper-gold deposit, situated in the Watut River Valley. Together they represent a potential mine of the scale of Ok Tedi or Bougainville or bigger. The MMJV is owned in equal shares by Newcrest Mining from Australia and Harmony Gold from South Africa. Although Hidden Valley was the first large-scale mine in PNG to engineer and build a tailings storage facility, poor environmental management during construction and early operations led to significant erosion of waste rock and sedimentation impacts throughout the ~200 km length of the Watut River. Since then, substantial efforts have been made to improve environmental management, especially waste rock placement and storage and water quality management. While the impacts from the Hidden Valley project appear to be reducing, the saga has heightened concerns by many along the Watut River and across PNG about ongoing impacts from mining.This paper presents the results of an ongoing project in the Morobe Province conducted by the Mineral Policy Institute examining the historical, current and future impacts of mining, including community views, social and environmental impacts and the monitoring and regulation of mining. Overall, there is a clear need to more fully integrate social and environmental issues into life-of-mine planning and go above and beyond regulatory requirements. In this way, some of the lessons learnt – by the community, MMJV and government – can be incorporated before, during and long after mining.CITATION:Mudd, G M and Roche, C, ?2014. Mining in Morobe, Papua New Guinea – impacts, assurance and self-determination, in Proceedings Life-of-Mine 2014 , pp 313–336 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By R Sinclair, D Landwehr, I Hunter

"The Syama Gold Mine, located in southern Mali, was established in 1990 by Broken Hill Propriety Limited (BHP). The operation began treating oxide, and in 1994 it transitioned to processing hard and refractory ore based on ‘whole-of-ore’ roasting. In 1996, BHP was succeeded by Randgold Resources and the operation ran until 2001, when it was placed into care and maintenance.The Syama ore is classified as a double refractory ore with pyrite occluding the fine grained gold present in the ore and high levels of organic carbon presenting a challenge in terms of preg-robbing behaviour. The ore is extremely competent and this combination of metallurgical features was the main source of metallurgical problems encountered by the previous owners.Resolute Mining Limited (RML) acquired the Syama project in 2004. Following a feasibility study and the development of a revised processing flow sheet the plant was recommissioned in 2008 using a combination of old and new equipment. The revised flow sheet enabled primary sulfide ore to be treated by flotation and roasting of the concentrate to produce a calcine suitable for conventional carbon-in-leach (CIL) processing.Commissioning and ramp up of the plant was a troubled process, with monthly gold production being as low as 3000 oz in 2010. Poor availability of equipment and lower-than-forecast recoveries were the primary contributors.During the last five years, RML has utilised a systematic approach to improve production, focusing on mechanical reliability, metallurgical recovery and process bottlenecks. Modifications to the circuit have been as a result of both innovation and the application of technological improvements. Improvements have been made to the flotation, roasting and CIL circuits and RML has introduced a deslime circuit to treat flotation concentrate, in addition to the very successful commissioning of a new 1 Mt/a oxide circuit in December 2014. These changes have resulted in gold production increasing to more than 20 000 oz per month in 2015.This paper presents the processes, change implementation and outcomes of the modifications made to the sulfide circuit to address the availability and recovery problems.Apart from the expansion of an existing, world-class deposit and discovery of new resources, future improvements on the path to a class-leading gold mine include the continued reduction of the unit cash cost, increase in overall sulfide circuit gold recovery, increased throughput through continued innovation and consistency in the plant’s operation.Citation:Sinclair, R, Hunter, I and Landwehr, D, 2016. Syama Gold Mine - the Journey towards a Class-leading Gold Mine, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 213–224 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016