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By H Simpson, C Gimber

The financial evaluation of mining projects drives a whole range of decision-making regarding project viability, project design, operating models and closure philosophy. Net Present Value is a financial assessment approach that is pervasive across the industry and has been widely criticised for driving short-term thinking and leading to poor long-term outcomes and future unfunded closure liabilities. But are there alternative models and what are the impediments to their implementation? This paper aims to outline current and past mine closure practices in the mining industry and questions these outcomes given the changing shareholder investment requirement for alignment with sustainable Environmental, Social and Governance (ESG) goals. Examples are presented of closure programs planned and executed in the later stage of the life-of-mine and explores the benefits that could have been realised by integrating these into concurrent production operations. Examples of simultaneous mine development and closure execution and their benefits are presented, and their relevance to corporate investor branding. This paper also discusses the concept of investor project ownership through to sustainable closure and outlines alternative approaches to responsible, sustainable mine closure. We explore the current mining industry divestment practices to remove closure liability from the balance sheet. These underlying financial practices and Net Present Value approach to Mine Closure and alternative approaches are discussed.

Aug 2, 2023

By M Schmid

German hard coal mining operations have decreased for more than 40 years. Current political decisions are leading to a discontinuation of subsidised black coal mining by the year 2018. This decision will, however, be reviewed once again in the year 2012. The enormous increases in productivity, which were achieved in previous years, have so far not led to an achievement of market requirements. Coal mining at depth of more than 1200 m in multiple seam environments is not yet competitive in global comparison. In 2008 the 24 faces left in eight mines produced about 20 million tonnes of usable steam coal. Management and the workforce will be reduced in parallel; from today until 2012 by more than half. The average age of personnel is increasing dramatically and nearly no new personnel are recruited. With this background in mind, increasing continuously coal mining productivity becomes more and more difficult. Above all, this goal was reached by mechanisation, then by increasing the mining machine power and then by enhanced machine control systems. The first attempts to automatically operate full face equipment from above ground were in the early 1980s. After successful automation of the face equipment, the emphasis is now on mine logistics. Autonomous monorail transport was introduced and tested in 2007. Since the development rate of machine improvements has its limits, the focus is on the full interaction of the total production system. Here information technology (IT) becomes important; the driver for more productivity. Actual developments aim for the complete and general homogeneous IT infrastructure both above ground as well as underground. The explosive environment needs high level investments in safe technology, eg access points for WLAN and fibre optics for underground use (ATEX certification). New technology availability also drives the enhancements of management and process control systems. Innovations in the mining industry often comprise technology advances through the adoption of well-known technologies. With virtual reality (VR) teaching and training systems advanced computational instruments, both in software and hardware development, were applied in the German coal mining industry for ten years. Widening lists of applications as well as the encouraging achievements show the economical benefits of investing in virtual reality technology both for teaching and training and for knowledge management. The paper discusses the actual technical achievements as well as in IT infrastructure utilisation and also in employment of virtual reality based systems. Special focus and deeper insight will be given to the fibre optics and WLAN hardware integration as well as software developments. The pocket personal computer (PC) is used to enhance underground material transport and data acquisition. The knowledge-based maintenance system (KBMS) integrates real-time virtual reality knowledge elements, such as repair process descriptions. It gives access to expert documentation by intelligent search algorithms and 3D representations of major mining machinery.

Jan 1, 2008

By Laros T, Schoenbrunn F

Deep paste thickeners have been proven capable of consistently producing medium to low slump material for disposal without the need for filters. However, proper design of the entire system is critical for a paste project to he successful. Some of the factors that must be carefully considered in design of a paste system include thickener sizing, tailings inipoundineni design, underflow pumping, and control system.

Jan 1, 1998

By S J. Henderson

Over much of Australia, rainfall is highly seasonal and storm-driven. Consequently, operational mines often need extensive earthworks – drains, dams and levees – for protection during the occasional large floods and for water storage against the dry times; however, it has not been appreciated that many of these earthworks will need to function after mining has finished, sometimes, beyond a normal design life for engineered structures.While a mine is operating, standards for design and maintenance are dictated by regulation and risk assessment. For dams and levees – regulated structures – the standards imposed mainly relate to life-of-mine. The levels of risk and maintenance accepted by the mine operator may not be acceptable to another landholder in perpetuity. However, the Environmental Authority cannot be surrendered unless the landholder has accepted responsibility for any unrehabilitated regulated structures (Department of Environment and Heritage Protection (DEHP), 2016).In order for a future landholder to be willing to take responsibility for a dam or levee, the structure should be of value to the business of the property. In addition, its management needs must be consistent with that business; for example, it should be maintainable using skills, equipment and materials normally available to the business.CITATION:Henderson, S J, 2016. Earthworks or landforms? Designing for lease surrender, in Proceedings Life-of-Mine 2016 Conference , pp 151–153 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By R Pax

Feed ore variability, the major disturbance into a mineral processing plant receives considerable attention operationally, and at research and strategic levels to ensure that the throughput of the ore are maintained at all times whilst encouraging a sustainable approach to recovering the valuable minerals from ore bodies. Effort and insights from mineralogical and processing characterisation (eg. ore hardness) of sub-ore body domains allows sequencing for processing to ensure consistency and throughput for the size sensitive grinding unit processes. Optimising the blast fragmentation has benefit as does pre-concentration using ore sorting. Blending of ore domains with different characteristics is common for operations. In recent years a number of technologies have become available for on-line and more rapid assessment of ore and have been discussed in a recent paper by Cameron et.al. (2016) as an opportunity for further utilisation of mine-to-mill (and mine to product) strategies. Current concepts have focused on extensive characterisation of ores so that current control practices can be realised and made more effective with relatively slow measurements and actuation. CITATION: Pax, R, 2018. Dynamic concepts for mine to mill operation and optimisation, in Proceedings Complex Orebodies Conference 2018, pp 124–125 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

The addition of a thallous salt to the cyanide leach of a calcined pyritic concentrate causes a marked increase in the"rate of extraction of gold. This probably is due to the activation of passive gold by.th,e. thallous ions'.''Lea'd, bismuth, and mercury salts, which should produce ' a, similai effect, fail to do so. It is postulated that'this latter result, together with'the reprecipitation of silver at low cyanide levels, is due to the presence of soluble sulphide. The use of thallous salts to reduce leaching time is discussed briefly.

Jan 1, 1964

By C Catania

Mining companies and operations across the globe typically target best practice financial management, along with a focus on economically driven mine plans. Not only is this inherent in running a successful mining business, but also critical in addressing investor scrutiny. The standards for social and environmental practices is less consistent than this, with most companies adopting standards that are driven through legislative and compliance requirements of the nations in which they operate. Although there is still room for improvement, Australian is a country that stands at the forefront of social and environmental legislation, driving more sustainable planning practices for mining operations, with an ever-increasing focus on mine closure considerations. Of the many nations yet to reach such a legislative position, Kazakhstan is a place where some companies are driving towards world class standards beyond what is government mandated. CITATION:Catania, C, 2018. World-class mine planning for a sustainable future in Kazakhstan Mining, in Proceedings Life-of-Mine 2018, pp 6–7 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By A Gibbs

Culture and leadership go hand in hand, especially when it comes to investing in safety. But the reality is that most safety leaders haven’t been taught the fundamental soft skills needed to lead effectively. In fact, only one in four safety leaders demonstrate effective skills and behaviours. Furthermore, when compared to its peers in other high-risk industries, our research indicates mining has the most room for improvement when it comes to effective safety leadership. In this presentation safety culture, climate and leadership will be outlined. Additionally, research data collected from our clients, across a variety of industries, will be shared to inspire reflection on the value of safety leadership. Finally, strategies to empower leaders and increase safety leadership behaviours will be described.

May 5, 2022

By C Tomlin, C Gimber

Historically, key closure risks have been studied during operations and then further assessed as cessation of mining approaches. Only in the past couple of decades or so has progressive rehabilitation and closure become an integral part of regulatory frameworks, sustainable mine planning and more recently, new project and development planning. It is now broadly accepted that the best closure outcomes occur when rehabilitation and closure are properly considered upfront, during the early stages of a mine development project and well before mining occurs. Increasingly, regulatory processes are requiring more diligence on early closure planning, often as part of the environmental impact assessment (EIA) and approvals process, rather than later in dedicated closure study phases. There is an opportunity to use the information generated during this phase to make better decisions on project selection, design, mining methodology and all other facets of the mining operation.

Aug 2, 2023

By T R. Gibbons, I Grayand

Geotechnically massive strata may lead to a host of problems during longwall mining. These include windblast on initial goaf fall, sudden loadings on powered supports, periodic weightings, fractures that may propagate to surface, and extreme subsidence problems. It is essential to identify these problems prior to mining and to appropriately deal with them. The problem is essentially that the rock mass does not breakup evenly and when it does so it tends to produce large blocks which may suddenly move. The rock types that produce these problems tend to be massive sandstones, massive siltstones and sometimes igneous sills. The fundamental problem with these is that they do not breakup readily. This is because the ratio of stress they are subject to compared to their strength is low. Thus, the shallower mines with lower stresses are more subject to this problem than deep highly stressed ones with similar strength rock.

Nov 29, 2022

By Fletcher G

This paper will outline the design process, and the constmction and rehabilitation techniques proposed for the external waste dumps associated with the mining of the Wolfang Basin coal measures.The basin is located to the north of Clermont and immediately west of the Bowen Basin in Central Queensland, Australia. Development of the Clermont Coal Mine is planned for the mid-1990s after adequate sales commitments are obtained to allow the project to proceed.

Jan 1, 1992

Stope control information at the C.S.A. mine is obtained by diamond drilling inclined holes from within the stapes. Practical mining outlines are determined from complicated ore contours by a joint mining engineering and geological study. Production holes to achieve this outline are individually marked up and checked. Stope control also extends to selective mucking of ore mixtures for metallurgical reasons and to marginal ore and waste mixtures for economic reasons.

Jan 1, 1969

By J Isarua, R Mabiria

The Ok Tedi copper and gold project, located in the Western Province of Papua New Guinea, commenced operations in 1983. The open cut mine has undergone several significant transformations throughout its project life including changes of ownership, mine life extensions and varying production performance profiles. As of today, the Ok Tedi Mine is a 100 per cent PNG owned company (67 per cent State and 33 per cent Western Province and Communities) and has a life-ofmine plan extending out to about 2032.

May 5, 2022

By Hughes CA

The need to recover metals from low grade deposits, old tailings, etc., combined with improvements in equipment design and the development of new extractants, has resulted in solvent extraction (SX) metal recovery reaching new importance (Webster & Ferron, 1993). The basic principle of solvent extraction is the use of an equilibrium system in which a metal ion is transferred from an aqueous phase into an organic phase, (Equation 1), (Ritcey, 1984). M + E ME . (1) The organic extractant (E) is usually specific for a certain metal ion (M) and forms a metal complex in the organic phase, leaving the impurities behind in the aqueous phase. To recover the metal, the equilibrium is reversed and the metal ion is transferred back from the organic to another aqueous phase in a process called stripping. The metal is then recovered from the aqueous strip solution, usually by electrowinning.

Jan 1, 1990

By R Justa Cámara, L M. Pinillos Lorenzana

Barcelona Metro Line 9 (Line 9) is an essential infrastructure, improving the transversal transport in Barcelona by connecting the greater part of the currently existing radial lines. The purpose of Line 9 is to create a peripheral line surrounding the city of 1.6 million people (metropolitan area exceeds five million), and includes 52 stations, of which a total of 32 are deep shafts and 19 transfer stations in a densely populated area with several geographical constraints.The tunnel has an inner diameter of 10.90 m, bored with an earth pressure balance (EPB) tunnel boring machine (TBM) in soil sections with precast concrete lining type universal ring and segments 40 cm thick.A single tunnel solution was adopted, driven by functionality and costs savings. The internal tunnel section is divided into two levels to allow for one way rail transit including the platforms in each station on each level in order to optimise the space created by the TBM excavation and comply with the operational needs. The division in two areas of the tunnel was carried out through the construction of a horizontal slab resting on the tunnel segments with a constant thickness of 40 cm at the central part of the slab and supporting side walls.CITATION:Justa Cámara, R and Pinillos Lorenzana, L M, 2014. Two transit levels in one tunnel tube – an innovation in Barcelona Metro Line 9, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 387–398 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By X Zhang, Z Guang, R Lin

To improve the existing process of a large-scale scheelite concentrator in Jiangxi Province, this paper presents an advanced process æselective flotation of copper and flotation desulfurisation û rougher flotation of scheelite û heating-stirring and cleaning of rougher concentrate at normal temperature without reagent removalÆ. The test work was conducted on an ore sample containing 0.75 per cent tungsten (WO3), and the following technical indices were obtained: 1.03 per cent of the scheelite concentrate yield, 65.37 per cent of the concentrate grade and 86.31 per cent of WO3 recovery, indicating that the study achieved the objective of improving the tungsten recovery. The technical key of this process is to employ combined regulators and direct flotation of the slurry after being heated, which not only assured the technical indicators of beneficiation but also simplified the process.

Jan 1, 2008

By A Stradling

For a geometallurgical program to be successful, linkage must be made between the geologists and geostaticians who understand and model the orebody, the metallurgists who determine the value that can be extracted from the different geometallurgical units, and the mine planners who develop and optimise the plan to extract maximum economic value from the resource. One of the primary purposes of geometallurgical models is in the determination of the economic cut-off between ore and waste. Recognition of the level of confidence required in the estimation of grade, throughput and recovery is critical to the planning of a successful geometallurgical program. It also helps clarify the scope of work needed to mitigate risk at each stage in the development of a new mine projectThis presentation provides some of the author’s experience with development and application of geometallurgical models for existing base metal operations. It discusses how geological units defined by lithology, structure, alteration etc, can be translated into geometallurgical ore types defined by mineralogy, ore hardness, and flotation behaviour. Examples of how these characteristics have been used to estimate key economic parameters such as mill throughput and flotation recovery at two brown-field operations are provided. The first example relates to the modelling of metallurgical performance at Teck’s Red Dog zinc-lead mine in Alaska. Prior to 2000, zinc, lead and silver recoveries from a block of ore at Red Dog were either assumed constant, or were varied according to simplistic models. Throughput was not thought to vary substantially between blocks, so an average value was used for each blended stockpile. It is quite possible that some ore-value blocks were classified as waste, and some waste-value blocks treated as ore, as a result of poor understanding of the true economic cut off across the wide range of ore types observed at Red Dog. After an extensive flotation test program, the first assay-based zinc recovery model was developed for the Main pit reserve in 2003.**This is an abstract only. No paper was prepared for this abstract**

Sep 5, 2011

By Anievas JB, Sevillano AC

This paper describes the acquisition, exploration, development, initial operation and subsequent financing of the Bulawan mine by means of a listing on the Toronto Stock Exchange of a subsidiary of the parent company, Philex Mining Corporation.Located on the island of Negros in the Philippines the property is unique on at least two counts: it is a disseminated gold deposit that occurs in a region of predominantly porphyry copper mineralisation; and it is a gold deposit that is mined by a bulk method of extraction (front and block cave) instead of the normal selective mining methods.

Jan 1, 1997

By A R. Bonani, M P. Pe±a

The optimisation of slope angles, that is to say, increasing them, compared to the original design is always the subject of analysis of stability for geotechnical engineers and economic analysis for planning engineers. Questions to be answered include: What is the acceptable risk? What factor of safety? What probability of failure or reliability? The Rosario Open Pit has a history of failure, poor quality rocks and high pore pressures. It was decided to deepen the pit below the programmed design to test the practicality of different design approaches, which if successful, could be used to improve the economics of mining at Collahuasi. The revised slope design has factors of safety in the range of 1.0 to 1.2, probabilities of failure of ten to 38 per cent, and increased slope angles of between 3¦ and 5¦ with respect to the original design. The pit deepening with these design slopes will deliver an extra two million tonnes of ore which will have a significant positive impact on mining economics.

Jan 1, 2007

By A He, J Li, J Pan, J Clout

The removal of sulfur from SO2 containing flue gas is improved by adsorbing SO2 into solution with manganese ions as catalyser, however, burnt lime slurry has to be added to modify solution pH and the CaSO3 by-product is of low economic value. In this paper a novel one step process for simultaneous manganese leaching-desulfurisation of flue gas is presented. An investigation of the effect of process parameters included flow rate and SO2 concentration in flue gas, adsorbing time, solution to solid mass ratio, leaching time, and their impact on the oxidation and removal of SO2 from flue gas. The catalysing mechanism of manganese ions on the oxidation and SO2 removal was demonstrated by calculation of the species originating from manganese ions and SO2 in the solution according to solution chemistry. SO2 removal in the adsorbing solution took place at pH 5 - 6, where manganese ions dominantly occurred as Mn2+, and the chain reactions for oxidation of SO2 starting from HSO3- were improved by the presence of Mn2+. SO2 bearing flue gas was effectively desulfurised by leaching rhodochrosite (MnCO3), with desulfurisation of the flue gas and modifying the solution pH being achieved simultaneously, and MnSO4 of high economic value recovered from the leachate. 85 per cent manganese leaching and over 70 per cent desulfurisation of the SO2-bearing flue gas were achieved with only one adsorption stage under optimum conditions.

Jan 1, 2004