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By A Guillen, J-P ChilFs

Most 3D geological modelling tools were designed for the needs of the oil industry or detailed mine planning and are not suited to the variety of situations encountered in other application domains. Moreover, the usual modelling tools are not able to quantify the uncertainty of the geometric models generated. The potential field method was designed to build 3D geological models from data available in geology and mineral exploration, namely the geological map and a digital terrain model (DTM), structural data, borehole data and interpretations of the geologist. This method considers a geological interface as a particular isosurface of a scalar field defined in the 3D space, called a potential field. The interpolation of that field, based on cokriging, provides surfaces that honour all the data. The 3D model and its parts are always consistent with the observations. New developments allow the covariance of the potential field to be identified from the structural data. This makes it possible to associate sensible cokriging standard deviations to the potential field estimates and to express the uncertainty of the geometric model. It also, for the first time, gives a statistically optimal, geologically sound way of interpolating geology, other than directly joining the dots as you do with CAD. Practical implementation issues for producing 3D geological models are presented: how to handle faults, how to honour borehole ends, how to take relationships between several interfaces into account, how to model thin beds over many kilometres, how to optimise lithological properties and how to integrate gravimetric and magnetic data. We describe all geology surfaces and volumes using implicit functions. These are then rendered onto the required sections, plans, etc. The estimation of orebody grades and tonnes, using an unbiased and optimal geostatistical technique, makes use of the stratigraphically bound 3D geology model. An application to the geological modelling of the Hamersley iron ore district, Australia, is briefly presented.

Jan 1, 2009

By W Dodson, S Dogramaci

Isotopes and hydrochemistry were used to define groundwater flow systems and better understand the hydrogeological setting of the Karijini National Park, which is in the Central Pilbara region adjacent to the Marandoo iron ore mine. Based on the stable isotope composition of the water samples, the data can be divided into two main groups. Groundwater is characterised by depleted dD and d18O, suggesting no significant evaporation effect. Surface water on the other hand is more enriched in dD and d18O due to evaporation. The relatively high concentration of Cl- compared to rainfall and depleted dD and d18O values of groundwater indicate that recharge of the aquifers is occurring during intense rainfall events when rapid infiltration occurs. Evapotranspiration then acts to concentrate ionic species prior to recharge. Relationships between the major ion concentration and catchment area, surficial Tertiary cover and distance between recharge and discharge were identified. The results show that these catchment variables combine to determine unique water chemistry for each sub catchment in Karijini National Park. The TDS concentration of the groundwater in the Marra Mamba Iron Formation that hosts the Marandoo ore body is higher than most of the water bodies surrounding the mining area suggesting significant modification or different recharge mechanisms to that of the Karijini groundwater.

Jan 1, 2009

By G E. Ho, M Anda, S Dallas

Water auditing and water conservation measures are fast becoming the quantitative tools for water balance reporting in the mining and minerals processing sector. Therefore, this paper was written to describe the process of water auditing in a goldmining environment and to contribute towards building an appropriate water management framework for The Cooperative Research Centre (CRC) for sustainable resource processing (CSRP). The research will assist with the assessment of water balances in mining and hydrometallurgical processes and ongoing probabilistic modelling for Newmont Mining Corporation, its wholly owned gold mines, and its joint venture operation of Kalgoorlie Consolidated Gold Mines (KCGM). Kalgold or KCGM are the managers of a joint venture project between Barrick Australia (50 per cent) and Newmont Mining Corporation (50 per cent) at Kalgoorlie, Western Australia (WA). Boddington Gold Mine (BGM), Western Australia, will commence operations this year and manage the new goldmine expansion project. BGM is 100 per cent Newmont owned and will operate to continue mining gold and copper from the existing (BGM) site that was decommissioned in 2001.

Jan 1, 2009

By C T. Senra, A Souza

Increasing fuel prices, unavailabilty and high prices of tyres have imposed tremendous challenges for large open pit operations. Carajßs open pit mines, one of the largest iron ore projects in the world, has been particularly affected due to the high amount of giant trucks operating in this site. On the other hand, environmental constraints push the mining industry towards reductions in fossil fuels, noise and waste generation. As a feasible response to these requirements, an alternative mining method for open pit mining, aiming to reduce or even eliminate the need for trucks has been developed, based primarily on coal opencast continuous operations. This innovative approach for open pits involves the replacement of trucks by fully-mobile crushers, bench conveyors and ramp conveyors. Two different applications have been developed for exploiting waste and ore at Carajßs largest pit, named N4E. To make it possible, mine planning paradigms should be replaced leading to new conceptual design of open pits. This paper shows two case studies (waste and ore conceptual design) carried out at Carajßs mines to anticipate and put forward the future of open pit mining, proving that our industry would be greatly affected by this new way of exploitation, reducing thousands of tons of fossil fuels. Productivities can be enhanced and environmental performance greatly improved. In this approach mine automation can be easily implemented reducing operating costs and man's fatigue.

Jan 1, 2009

By F Palkovitz, S Wilson, F Felipe

The management of waste from mining operations is a significant aspect of bringing a mineral commodity to final market. The ore beneficiation process and transport/disposal of waste involves significant consumption of costly resources. A number of options exist to dispose of mill waste on surface and as a backfill material. These range in complexity, risk, capital cost, operating cost and ultimately business performance. This paper discusses the value delivered to a business in using dewatering systems including paste as opposed to conventional slurry tailings disposals. This is illustrated through various case studies and serves to demonstrate how paste can add value and reduce risk to a successful business.

Jan 1, 2009

Talvivaara deposits, Kuusilampi and Kolmisoppi, comprise one of the largest sulfide nickel resources in the world with 642 Mt in Measured and Indicated Resource categories. TalvivaaraÆs preferred extraction technology is bioheapleaching, which is already widely used for other metals, notably copper and gold. The company has demonstrated the viability of bioheapleaching technology for the extraction of nickel using the Talvivaara ore. The leaching process is heat generating and therefore suitable for the subarctic climatic conditions. The planned annual metal production is 33 000 t of nickel, 60 000 t of zinc, 10 000 t of copper and 1200 t of cobalt. Talvivaara deposits are well-suited for open pit mining due to a thin overburden, favourable resource geometry and a low waste to ore ratio. The ore is relatively low-grade, but well suited to bioheapleaching due to its high sulfide content. Bioheapleaching is a process whereby metals are leached from ore as a result of bacterial action. The bacteria used in the Talvivaara bioheapleaching process are endemic to the area and therefore well adjusted to the prevailing environmental conditions. The solution is collected at the bottom of the heaps and either re-circulated through the heap or fed to metal recovery. In metal recovery, nickel, copper, zinc and cobalt are precipitated from the pregnant leach solution and filtered to produce saleable metal products. After the metals are removed, the solution is further purified and returned to irrigate the heaps. Mining, bioheapleaching and metal recovery techniques for the Talvivaara mine have been tested in a 17 000 t on-site demonstration trial during 2005 and 2006. Subsequent construction of the mine started in 2007 and commercial production in the fourth quarter of 2008.

Jan 1, 2009

Water resources legislation in Brazil is evolving in a number ways. The nature of water resource ownership has changed in the last constitution (1988) so that now all water remains the property of the state and not the individual. There is also an increasing amount of legislation to control water access from the environment and regulation over water quality for water discharged. Finally, in some regions charging for water has been introduced and this is expected to become more wide-spread over the next few years. Increasing government attention to water legislation creates an increased need for mine sites to improve water management. As a fundamental basis for this, it is necessary to make robust estimates of mine site water balances, which also requires knowledge of the regional water balance to provide context for the mine water use. A conceptual model for mine site and environmental water balance is presented. Issues associated with conventional water monitoring are discussed. It is proposed that introduction of automated monitoring to provide comprehensive and consistent data is attractive. However, there remain a number of cultural and practical impediments to purchase, implementation and maintenance of effective monitoring, which are summarised.

Jan 1, 2009

By C A. Chaves

During most of its history, the metallurgical industry has been seen as a source of pollution for the environment. However, during the second half of the 20th century, as the world environmental legislation became more protective and the global environmental conscience consolidated, this landscape began to change. Metallurgical activities have become increasingly related to the social and environmental impacts caused by human activities. With the adoption of environmental management in steel plants, there has been a significant change in steel-related activities which have begun to introduce modern plants, managed with environmental, social and productive efficiency. More and more, steel companies search for a decrease in negative impacts of their industrial operations on the environment, fitting them to the current environmental legislation and even increasing productivity and profitability. The steel industry has started to become a clean and more efficient industry. This work presents a case study of a sustainable steel plant project, located in an environmental preservation area. The project includes treatment and reuse of industrial liquid effluents, air emissions control, noise control, recycling, recovery and adequate waste management. It also incorporates production processes using clean technologies, capable of coproducing energy resources which may be used in the plant showing how is it possible to produce steel with environmental and social responsibility and even increase the enterpriseÆs profitability.

Jan 1, 2009

Addressing community concerns in relation to an economic activity, particularly when it causes significant community impacts, is especially important for the development of extractive industry projects. Pipelines comprise an integral part of many hydrocarbon developments, which may cause different effects on local economic development, communities and the environment compared with open cast mines. This paper explores community impacts associated with a case study of the oil pipeline æEastern Siberia-Pacific OceanÆ in the Republic of Sakha (Yakutia), Russia. Based on semi-structured interviews, conducted in 2006 - 2008 in Russia, the paper investigates claims of local communities about potential impacts of the pipeline development of their environments and economic activities as well as community claims for greater involvement in sharing the benefits from this major infrastructure project. A community of Indigenous people, Evenk, is likely to be most profoundly affected by the development due to impacts on their traditional activities such as hunting and reindeer herding. The paper examines in detail the regional economic, social, environmental and Indigenous peoples concerns over the construction of the oil pipeline and investigates actions and methods adopted by community organisations to voice their concerns about the pipeline development. Finally, the paper assesses the process of interaction between the pipeline developers and regional stakeholders.

Jan 1, 2009

This study explores two evolving 3D surveying technologies, photogrammetry and laser scanning, and applies them to deformation monitoring of rock faces and mine highwalls. A quantitative analysis focused on 3D coordinate determination is performed. Furthermore, a qualitative assessment directed at the practicality and viability of each system operating near a rock face or in a mining operation is undertaken to reveal one systemÆs deficiencies over the other. Two photogrammetric and four laser scanning surveys aimed at optimising accuracy and precision within a short period of data acquisition are conducted on the rock face at Organ Pipes National Park, Keilor, Victoria. The accuracy and repeatability of each survey is determined using a combination of iWitness photogrammetric, and Cyclone laser scanning software. The 3D coordinates of targets placed on the rock face are determined by triangulation and resection principles within a bundle adjustment. The coordinates determined by each system are then compared in a 3D transformation. Controlled deformation conditions are established to determine the precision to which each system can detect movement in the rock face. An object of known dimensions is placed on the rock face to simulate deformation. The relative orientation of images taken for the pre- and post-deformation photogrammetric surveys provide an overall 3D point accuracy of 1.255 mm and 1.804 mm respectively. A 3D transformation shows discrepancies of less than ¦22 mm (RMS) between the geometry of the photogrammetric and laser scanning models. Both systems are able to detect the simulated deformation to a precision of 50 mm. This work also identifies how to obtain millimetre accuracy for 3D coordinate determination of rock faces, thereby providing a quality data set for surveyors, geotechnical engineers and mine geologists. Photogrammetry is shown to be a mobile, time and cost-effective technique that is more amenable to mining operations than terrestrial laser scanning. However, both systems demonstrate that they are capable of detecting movements that may lead to failures in the rock face, and possibly endangering human life. The implications are significant for surveyors, geotechnical engineers and mine geologists working in mining operations where enhanced safety conditions, increased productivity and lower operational costs are important considerations.

Jan 1, 2009

This paper describes the development of an approach to sustainable development for application at the feasibility study stage for a proposed bauxite mine near the community of Aurukun, south of Weipa on the western coast of Cape York Peninsula, Queensland, Australia. The general environment for development was complex in all dimensions. In particular, the socio-demographic profile of the Aurukun community (population 1200) characterised it as being amongst the most disadvantaged communities in Australia. The traditional owners of the area, the Wik and Wik-Way people, were at the forefront in the efforts of Indigenous people in Australia to secure land rights over the past 30 years, and they had previous experience negotiating an Indigenous Land Use Agreement (the Western Cape Communities Coexistence Agreement) with Rio Tinto Alcan, the operators of the Weipa bauxite mine. Through this they had shown a well-founded sense of entitlement with respect to the development of resources on their traditional land. The Queensland State Government had recently cancelled an existing mining lease over the bauxite resource as the holder of the tenement had not fulfilled the terms of a development agreement that had been in place for 30 years. The Government was anxious to avoid any future æbankingÆ of the resource, and had decided to offer tenure to the resource on an international competitive basis, subject to the requirements of the Commonwealth Native Title Act 1993. This would require a negotiation process with traditional owners and potentially involve companies with whom the traditional owners had no existing relationship (typically developed during the projectÆs exploration phase) and who possibly had no project development experience in Australia. As well, the State Government envisaged an approach to development that drew on the significant work that industry and other stakeholders had undertaken over the previous ten to 15 years, commencing with the mining, minerals and sustainable development (MMSD) process. This work was aimed at rectifying acknowledged deficiencies with industry recognition of stakeholder interests, in particular with respect to environmental management and socioeconomic development. The approach adopted aimed to define the strategic community interests and sustainable development outcomes to which the development of the resource would be expected to contribute, and to embody these within an easily usable management structure that could be applied to each stage of project development from feasibility study through to mine closure. The logical framework (AusAID, 2006; ICMM, 2005) was the management tool utilised to order the identified interests and desired outcomes. The structure included components aligned with the key areas of development interest expressed by the community, and the initial baseline sustainable development plan (SDP) developed established component objectives, outcomes, indicative outputs and activities for the feasibility stage of the project. This established an objective framework to guide potential bidders when developing their response to the State GovernmentÆs Request for Proposal. The paper will describe the evolution of the competitive process and the parallel process for development of the SDP. While the institutional environment was politically and socially complex, the use of simple visual representations of the environment and the analysis and ordering of issues, objectives and criteria through methods such as stakeholder analysis and the logical framework approach, enable the development of a dialogue on the contribution that the development of a mining project can make to sustainable community development, and for the development of an agreed program of community support to capture the contribution. The use of the logical framework was found to have good functionality for plan development. Achieving plan outcomes though, is highly dependent on the skill of key project personnel in facilitation, team building, conflict resolution and leadership, as well as their ability to influence the behaviour of key stakeholders with the capacity and authority to require the integration of local economic development criteria in to key project development decisions.

Jan 1, 2009

By K Jupp, T J. Howard

Cliffs Natural Resources Pty Ltd (CNR) operates iron ore mines in the Koolyanobbing region of Western Australia, about 50 km north of the town of Southern Cross. Ore is trucked from three geographically isolated sources to the crusher at Koolyanobbing, where it is blended before and during crushing. Lump and fines products are produced and railed to Esperance for ship loading and export to Asian customers. CNR is examining alternative processing paths, from mining to ship loading, with the aim of improving efficiency and reducing costs. Modifications to the system must be consistent with potential future expansions and maintain the low inter-shipment grade variability on which CNR prides itself and has built a strong relationship with its customers. In searching for the optimum process design, many options from mine face to ship loading must be evaluated and compared. Pilot plant studies are infeasible, while complex mineralogical interactions, competing goals and numerous possible system configurations limit the applicability of theoretical analysis. It was therefore concluded that simulation modeling would provide the confidence to take the next step into production trials. This paper describes techniques applied at CNR to simulate grade variability resulting from potential process design changes. The simulation models are easily run Excel-based modules, with each module representing a different part of the process. The modules use extensive Visual Basic macros driven by Excel's user-friendly interfaces. Presentation of the results is enhanced by Excel's excellent graphical capabilities. The simulation software stores and graphically presents time-stamped data from a run, enabling detailed analysis of different process configurations. Final success of a simulation run is measured by inter-shipment variability (standard deviation and process capability) and in-process ore tonnages. Meaningful results from the simulations require the initial input data contain the same correlations present in the real production environment, between the mineral components, production linkages and across time. The data also have to allow simulation of potential changes to mining method and introduction of new pits into the blend. Mining data from the real operations under study are therefore used, with average grades and variability adjusted to match potential future development proposals. It is also necessary to filter out medium and long-term variations from the production data as this variability is best controlled through the conventional medium to long-term mine planning process, not by the process design being studied. The filtering was carried out using a Fourier transform technique, which is described.

Jan 1, 2009

By J R. Manuel, M J. Peterson

Selected drill core samples from a Ferrobamba-limestone-hosted, magnetite-haematite skarn deposit, located in the Apurimac department of the Andahuaylas-Yauri skarn/porphyry belt of south-eastern Peru, were mineralogically and texturally characterised to gain a preliminary indication of the deposit's potential as an iron ore resource. Optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy/electron probe microanalysis (SEM/EPMA) techniques were utilised to determine the characteristics of magnetite, haematite and/or goethite dominated ore types, including variations in the relative proportions and textural relationships of the ore and gangue minerals. The deportment of elements deleterious to processing performance (eg copper, sulfur and potassium) was determined and the beneficiation potential of the samples was briefly assessed. In drill core sections, the ores are grey to reddish in colour, massive and 'metallic' to dark brown and earthy in character, moderately hard and porous (macro and microporous), with variable gangue infill. Ores often appear weathered, typified by ochreous goethite staining and common minor goethite (except in dense core fragments), occasionally exhibiting a more friable texture with coarse magnetite/martite grains. Silicates and lesser carbonate gangue are visible as blue-green to beige to white scaly and/or shaly surface coatings, and finely particulate infill, often goethite stained. Sulfide-rich ore types also occur in part of the deposit, but are restricted to specific drill holes. Magnetite grain size is relatively coarse, compared with magnetite from typical banded iron formations, whereas discrete silicate gangue is mainly bladed/fibrous and/or layered and micaceous in form. XRD analysis indicates the presence of vermiculite, serpentine, stilpnomelane, chlorite, actinolite and clays. There is a spectrum of ore types representing the gradation from 'fresh' (magnetite-dominated) to oxidised and weathered (martite/goethite-dominated). Martite-dominated samples are generally higher in grade, due to leaching and removal of silicate gangue, resulting in higher macroporosity. Where gangue has been leached out, partial replacement by vitreous goethite and/or hydrohaematite is typical, often preserving the fibrous/layered characteristics of the original silicates.

Jan 1, 2009

By A Valero, G M. Mudd

There is active debate and research around the most suitable indicators to assess the sustainability of mining. The most common approach is to report a range of data for a given mine site (or less preferably, a company total), such as inputs, outputs, benefits and potential costs. The most popular protocol in use (and growing rapidly) is the Global Reporting Initiative (GRI). However, these measures are numerous and still do not allow a single over-arching indicator to be developed. Other measures, such as known mineral resources over time, do not account for critical challenges such as declining ore grades, increasing wastes and poorer quality ores or more difficult mineralogy. By adopting a thermodynamic approach to sustainability, through the concept of æexergyÆ, it is possible to incorporate into a single measure the effective quality of mineral resources. Exergy involves the assessment of the minimum energy costs involved in producing a mineral resource with a specific chemical composition and concentration from common materials in the environment. The exergy of a mineral resource is evaluated from mineralogic composition, concentration (or ore grade) and, of course, quantity, by multiplying the unit exergies with the tonnes of the resource produced (or consumed). Since exergy is a thermodynamic quantity (ie energy or joules), it is additive across different minerals, such as iron ore to gold to copper or even oil and gas or coal û making it an ideal indicator to assess mineral resource sustainability at the industry scale rather than the individual mine scale. This paper briefly outlines the theoretical basis for exergy, and then presents a range of commodity case studies showing the application of exergy to the Australian mining industry. Overall, the usefulness of exergy is clearly demonstrated for use as a broad indicator of the sustainability of mineral resources at the national or even global scale.

Jan 1, 2009

By D Henderson, M Germain

The beneficiation of iron ore deposits to yield haematite and magnetite concentrates for steel making processes typically require the use of one or a combination of wet processing techniques based on gravity, magnetic or froth flotation processes. With the need for more cost-effective technologies with a lower water demand, a re-examination of dry processing techniques has been initiated. For example, a dry processing capability may offer an advantage where suitable quality and quantity of process water hinders the development of a particular resource. This paper describes recent laboratory test work for the production of high grade concentrates using dry electrostatic techniques for -300 ¦m haematite and magnetite ores and compares them with magnetic separation techniques.

Jan 1, 2009

By A Tomsett, R Kidd, Z Casley

Bivariate recoverable resource estimation aims at predicting the recovered metal for a secondary variable when a cut-off is applied to a primary variable. The choice of a consistent geostatistical model is advisable to allow a robust estimation from exploration data of the primary and secondary metal recovery functions on a generic selection block (selective mining unit û SMU) within large panels. Ore processing decisions at Lihir Gold LimitedÆs Lihir Gold Mine are based on the gold and sulfur estimates of SMUs from production (grade control) data. The predictive model from exploration data at Lihir is based on the estimation of a recoverable resource for gold by Uniform Conditioning (UC), with an estimate of the sulfur grade being provided by Ordinary Kriging of panels. While univariate UC is adapted to the diffusive nature of the gold mineralisation (Ladolam orebody) at Lihir, the independent estimation of sulfur, through ordinary kriging, fails to capture the potential spatial correlation that exists between gold and sulfur mineralisation. This paper presents a practical implementation of bivariate UC, which better represents in the resource model the spatial correlation between gold and sulfur. Incremental economic gains through improved definition of material categories and scheduling are investigated, and the particular impact on the process of geological interpretation and domaining is emphasised.

Jan 1, 2009

One of the earliest and continuing challenges in driving sustainable development in large scale resource industry projects is around the issue of assessment û how do you measure the sustainability of a mineral operation? One of the key road blocks when confronted with this challenge is the temptation of technical folks to reach for a definition of sustainability or sustainable development. But definitions, by definition, have boundaries and limitations that serve to constrain thinking û they limit the thinking of what we can achieve with sustainability (it also acts as a barrier that constrains innovation). Rather than seeking definitions, better understanding of the core perspectives around sustainability and their application to the minerals industry provides a much more powerful platform from which to conduct assessments. But it is only when these perspectives are combined with the right framework and supporting techniques that the complex becomes doable. With the support of the perspectives and the framework, various assessment and measurement methodologies can be used; the challenge is communicating to stakeholders the sustainability character of the project in ways that are meaningful and to which people can connect. Assessment is not about finding the best or most accurate methods that fulfil strictly academic and possibly abstract requirements. The challenge is to help people understand what the impacts are, and what the value contributions will be, in a format and language that make sense in their world-view.

Jan 1, 2009

By D Tanzil, H Jones

Every mine will close! Charting a profitable course through mine operations to acceptable mine completion requires that risk and opportunity management planning of the mine life begin as early as possible in the life cycle. Management targets and metrics are required to identify and navigate the course to successful mine completion based on economic, social and environmental criteria. This paper outlines the application of The Metrics NavigatorÖ principles to the life cycle of a mine site. In general, metrics are required to make key strategic ideas apparent, transforming those ideas into a manageable set of quantitative measures that guide communication and decision making. For example, the chemical industry has established metrics that focus on the life cycle impacts of its products and eco-efficiency of their processes. Other industry sectors have focused attention on workplace and community well-being outcomes. These management metrics are necessarily organisation-specific, aligned to stakeholdersÆ expectations and the strategic outcomes sought, as well as the cause-and-effect relationships underlying key issues. Recently, the Global Environmental Management Initiative (GEMI), a consortium of multi-national companies, developed The Metrics NavigatorÖ. The guidance document provides a structured process for assessing and developing metrics for key environmental, social, and economic issues based on business and stakeholder perspectives. It incorporates best practices learned from the chemical and other industry sectors and has since been applied to develop metrics that guide life cycle strategies. The paper examines how the life cycle of a mine site could benefit from experiences in other industry sectors where sustainability metrics have guided strategy. It considers the potential application of The Metrics NavigatorÖ process to the life cycle of a hypothetical Australian mine site using the processes that have been successful in other industry sectors.

Jan 1, 2009

The issue of retrenchment is a topic of considerable relevance for the Papua New Guinea (PNG) mining, petroleum and gas industries. The unique environments in which Porgera Joint Venture (PJV) and other similar operations operate are likely to confront these industries with particular dilemmas that will require a range of investments to mitigate the problems associated with retrenchment and employment. This paper discusses retrenchment and employment in the PNG mining industry using the specific case study of PJV. The paper deals with the issue of employment and retrenchment of local workforces in the PNG context, which presents a serious challenge for the resources industry and the achievement of sustainable development objectives. The issue of future retrenchment of the workforce as a result of mine closure is an obvious challenge for both PJV and the Porgeran community at large, who have now come to rely upon both the employment opportunities presented through the mining. This paper examines these challenges and in doing so highlights some progress made by PJV. The paper also discusses downsizing, strategic practices and holistic approaches of retrenchment and employment. In doing so the paper highlights issues that have been overlooked in both academic and applied studies from global and local perspectives in the PNG mining sector. The latter sections articulate the relevance of the information provided by the case study in the wider context of retrenchment. The conclusion promotes a perspective that a great deal more investment will be required by all stakeholders to respond to the challenges of managing retrenchments and mine closure.

Jan 1, 2009

By I M. Platten, C J. S Sangster, Y Xie

The Cononish gold-silver deposit is a steep, relatively narrow quartz-vein system, with a current total mineral resource of 154 000 oz Au and 589 000 oz Ag. The northeast-southwest trending system was emplaced into late Proterozoic metasediments, and postdates metamorphism and associated Caledonian Orogenic foliations. Assay and mineralogical data show that gold and silver is spatially associated with sulfides in quartz. The main sulfide is pyrite, but galena, chalcopyrite and sphalerite occur in small amounts. Gold occurs as electrum, with minor native gold, and silver occurs additionally as tellurides and native metal. The gold/electrum is fine-grained, generally less than 100 microns in size. The main ore shoots plunge 45¦ south-west, have a 40 m to 80 m intersection with the existing underground development and extend between 40 m and 260 m down plunge. Small-scale sulfide-bearing domains within the vein carry the highest gold grades. They collectively define the ore shoots, where one or two, and rarely three, of the domains are present at an individual site in the vein. Discontinuity of individual domains, variation in domain thickness and internal heterogeneity results in short scale variation in grade across the structure. Geological mapping along a 1.2 km exploration adit has provided critical æconditioningÆ data to support resource evaluation based on development and relatively wide spaced drilling. In addition, it has provided an indication of potential challenges that could be encountered during production.

Jan 1, 2009