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By P Audet, D Doley

The mining industry often embraces mine closure criteria that require the reinstatement of predisturbance or even presettlement (ie historic) ecosystems. However, the extent and severity of disturbance associated with most mining activities mean that critical physical and biological characteristics are irreversibly altered. Consequently, it is rare that a reconstructed landscape can support ecosystems even close to the historic condition, and this rarity is reflected in the small number of mine leases that have been extinguished by attainment of such completion criteria. Novel ecosystems are defined as those in which some or all physical and biotic components are irreversibly different from the historic condition. Recognition of the concept of novel ecosystems allows mine closure criteria to be set according to attainable physical and biological conditions that provide safe, stable and manageable environments with acceptable ecological functions. We propose that a landscape that first maximises physical stability and economy yet will provide a range of environments for vegetation communities and fauna habitats that may be very different from those existing prior to a disturbance should be considered suitable alternatives to, eg targeting idealised historic environments. As a result, mine closure criteria should be established by detailed description of the best attainable physical conditions, with negotiated identification and testing of the most appropriate biological systems for the various parts of the reconstructed landscape. As a general practice, revegetation would use native, but not necessarily local species if the new physical environment is not conducive to the survival and growth of local species. These new ecosystems would need to be managed in perpetuity, although the intensity of management might be low if landscape design and engineering are combined with appropriate species introductions. Here, we suggest an abbreviated procedure that may be adapted in light of local conditions and circumstances for guiding decisions influencing the physical and biological properties of reconstructed landscapes that will enable novel ecosystems to meet realistic closure criteria.CITATION:Doley, D and Audet, P, 2014. Changing restoration priorities in the 21st century – opportunities for novel ecosystem design in mine closure, in Proceedings Life-of-Mine 2014 , pp 649–662 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By J Euston

In the 1990s round flotation tanks were introduced as a result of the lower fabrication costs for larger cells. It was soon observed that round tanks held a number of further advantages over the traditional rectangular cells, such as better hydrodynamics, lower costs and reduced footprint per unit volume.In the last twenty years flotation cell sizes have increased almost exponentially and designs of 250 to 300m3 are a well established standard with plans for full scale pilot installations of 500m3. The option to install these large cells gives flexibility in circuit arrangements and allows efficient and economic matching of flotation lines with modern mill designs. The benefits of scale up are well known with reduced numbers of cells required, lower power costs per unit volume, etc. These benefits will be briefly reviewed with specific reference to the installation of 300m3 to 350m3 flotation cells at the Copperton Concentrator of Kennecott Copper in Utah, USA.The sophisticated techniques required to model these ‘supercells’ have led to a critical review of the fundamentals of flotation science and engineering. In addition to outlining the advantages of large flotation cells, this paper will review the science which supports, and occasionally challenges, the ongoing trend to larger flotation cells.

Aug 8, 2011

By L Clarkson, D Williams, P Redcliffe, F van der Wal

This research presents a snapshot and insight into the trends, patterns, and common considerations identified in the current standing of real-time tailings dam monitoring practice. Based primarily on information derived from concurrent research by the author (in form of a Catalogue of Real-time Instrumentation and Monitoring Techniques for Tailings Dams), challenges and opportunities when transitioning to a real-time monitoring system are discussed. Learnings and key considerations between different monitoring approaches are explored, including themes of limitations and advantages that were observed consistently through global supplier feedback.

Jul 1, 2021

During the later part of 2007 I was lucky enough to visit the Atlas Copco facilities in Sweden, and to see first hand what a large and diverse company Atlas Copco is. The reason this paper calls the Atlas Copco experience a bonanza is that it means a source of great and sudden wealth or luck; a spectacular windfall or a rich mass of ore, as found in mining. I think this aptly describes the scholarship as it has greatly increased my wealth of knowledge of the mining industry. This paper intends to encourage all those eligible to apply for this fantastic scholarship opportunity, and seeks to thank all those involved who made this scholarship the amazing experience that it was. Atlas Copco produces most of its Swedish products in the town of +rebro, and it was here that I spent most of my time, visiting the Underground Rock Excavation group, the Surface Mining Equipment group and Rocktec. I also travelled around Sweden and was able to visit one of OricaÆs manufacturing plants, the Secoroc groupÆs manufacturing plant, the Geotechnical Drilling and Exploration group as well as being fortunate enough to visit the LKAB mine in the Arctic Circle in Sweden. The trip was not all information on Atlas Copco products and services however; I was able to go to the Ice Hotel in JukkasjSrvi and drink Absolut Vodka out of ice glasses, go on a reindeer safari (as well as eat them!), sample the fine meat from a moose, drink local schnapps, attend the Atlas Copco Christmas party, wander around the wonderful city of Stockholm and generally immerse myself in the great Swedish culture.

Jan 1, 2008

By H Bruyn, K Ehrig, V Liebezeit, A Robertson, M Smith, D Grant

"The Olympic Dam geometallurgy program has generated a large quantity of data that has been used to create a geometallurgically enabled block model. An ongoing challenge is to convert data into usable information and embed geometallurgical practices into resource model development and mine planning to assist with the identification of opportunities to maximise value.This paper will discuss the methods used to disseminate geometallurgical information throughout the planning life cycle including data extraction methods from the geometallurgy acQuire database, and the inclusion of a geometallurgy module in the Olympic Dam Stope Reserves database. The use of geometallurgical information in short-, medium- and long-term mine design and scheduling, including its use in grade descriptor development and stope value assessment tools will also be presented. The detail of development of specific geometallurgical models is outside the scope of this paper.At Olympic Dam, the incorporation of geometallurgical capability within the long-term planning team, traditionally the domain of mining engineers, has proved essential in broadening the base of geometallurgical knowledge as well as focusing geometallurgy resources on value-adding areas while providing a holistic risk based long-term plan.CITATION:Liebezeit, V, Ehrig, K, Robertson, A, Grant, D, Smith, M and Bruyn, H, 2016. Embedding Geometallurgy into Mine Planning Practices – Practical Examples at Olympic Dam, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 135–144 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By Motyka J, Adamczyk AF, Witczak S

A case study of migration of a paper factory fluid wastes, on the distance of 5 km from an underground disposal site to an ore mine is presented. The ore mine in question, situated in SW Poland is pumping 3.5 m3/s (ca 300 000 m3/day) of groundwater, producing a cone of depression about 150 m deep and several kilometers wide. The migration of wastes (pollutant) occurs within the carbonate karstic aquifer of Triassic age. The aquifer is about 100m thick and is characterized by the coefficient of hydraulic conductivity equal to 8 m/day on the average. The results of systematic measurements carried out for 13 years enabled to estimate the mean breakthrough curve of the pollutant. On this basis and taking into account the coefficient of hydraulic conductivity as well as the mean hydraulic gradient between the disposal site and the ore mine, the migration parameters of the polluting material, i.e. the real flow velocity, the effective porosity and the longitudinal disper- sivity have been calculated. As the measurements considered a long migration distance of the pollutant, the obtained hydrodynamic dispersion constant (dispersivity), in the authors opinion, is reliable enough to be applied for regional groundwater calculations, regardless of the "scale effect".

Jan 1, 1988

By T Smith, J Hatley

With the increased focus on the need for more uranium mines, this paper presents the design process currently underway for the development of the Millennium deposit in northern Saskatchewan, Canada. This deposit, located 630 - 750 m below surface, will be accessed by two shafts and will be mined by blasthole stoping methods at less than 500 t/d. Mining grade will approximate two per cent U3O8 and mine life is expected to be six to seven years. The project is a joint venture between Cameco, AREVA and JCU. This paper discusses in detail methods used to predict worker radiation exposures, the methods used to monitor the work environment and procedures unique to the uranium industry necessary to minimise worker radiation exposures.

Jan 1, 2008

This paper examines some of the important aspects of mineral taxation policies and practices, with reference to the mining tax regimes of selected Pacific Rim countries (see Tables 1 and 2). The following subjects are addressed:what is æmineral taxationÆ?, basis for mineral taxation, types of mineral taxes, objectives of the mineral taxation regime, best practices, and mineral royalties. Many countries, in some cases with the encouragement and assistance of international funding agencies, are actively assessing the international competitiveness of their mining tax regimes with a view to attracting investment. However, these countries recognise that the mining tax regime is not the only consideration that is taken into account by prospective investors. The countryÆs geological prospectivity, physical infrastructure, labour force, political risk, and regulatory system are also important factors in the investment decision making process. Although it is probably true that an attractive mining tax regime will not necessarily attract mineral investment, there is a real possibility that an unattractive regime can drive away investment. For example, Hugo Dummett, general manager for discovery at BHP, hinted recently that BHP could cease exploration in Russia in the absence of positive tax changes. Dummett is reported as saying that if taxes æend up being as onerous as they are now, we really have to rethink why we are hereÆ (Mining Journal, London, November 27, 1998).

Jan 1, 1999

By Sparrow G. J

In a recently completed AMIRA project, 20 samples were searched for gold mineralisation using the automated location facility (ALF) for rare phases on a scanning electron microscope in the CSIRO Division of Mineral Products, Melbourne. The samples were submitted by mining companies in Australia, and Papua New Guinea, and included crushed ore samples, cyclone overflow and underflow products, a flotation concentrate, and 12 tailing samples. Their gold contents ranged from 600 to 0.2 g/t An. Native gold and gold minerals including a gold telluride, gold-silver tellurides, and a gold bismuth mineral, were located in the samples as free grains and associated with other minerals such as pyrite, magnetite, hematite, ankerite, copper sulphides, silicate minerals, and quartz. In the highest grade samples, both micron sized and 200 ¦m grains of gold were found with ALF. It would be difficult to locate such d wide size range of gold in a manual search. Gold mineralisation was located in the tailing samples assaying 0.4 g/t An and higher. In several tailing samples coarse grains of native gold over 40 p.m in size were located. One grain was estimated to have contributed 40 per cent of the gold in the sample. As well as locating gold mineralisation, the ALF examination resulted in the identification of uranium, mercury, and bismuth minerals in the samples. Knowledge of the distribution of these minerals in processing streams could be important in the operation of a concentrator.

Jan 1, 1992

By D Morrison, P Goodman

The cycle time between adjacent stopes is critical to achieving the required production rate from 3500 Orebody; one of the Enterprise Mine orebodies. Current Mt Isa cemented fills require a 90-day cure period which had to be cut to 30 days while maintaining the required strength criteria. The Enterprise Mine Feasibility Study recommended that this be achieved by Cemented Slurry Rock Fill (CSRF), but that on-going research into paste fill be continued. The continuation of the research, in conjunction with overseas visits has recommended that the 3500 Orebody be filled with paste fill, with the potential to fill other orebodies. The paste fill will comprise cyclone and thickener dewatered copper tailings to which Portland Cement (PC) is added before vertical borehole delivery and undergound pipeline reticulation to individual stopes. The benefit is not only re-use of copper tailings but also much reduced binder usage.

Jan 1, 1998

By A Querzoli, B Williams

In late 2014 the Flinders Power Management Team was executing business improvement plans to ensure continued electricity generation until 2028 and beyond. Six months later, in June 2015, the Board announced the closure of the Flinders Power South Australian business, including the Leigh Creek Coal Mine, the Northern and Playford Power Stations located at Port Augusta and the 250km railway line. The announcement was preceded by a brief period of internal planning. A date was soon set for ceasing coal mining operations, being November 2015. The mine is unique in many ways. Located approximately 550km north of Adelaide the site has over 100 years of history and was formerly operated by the South Australian Government. Privatisation in 2000 saw the mine continue operation under Perpetual Leases from the South Australian Government. The leases included exemptions from multiple sections of the Mining Act 1971, obliging primary regulation under the Mines and Works Inspection Act 1920. The coal, being a low rank sub-bituminous brown coal, is prone to self-heating and spontaneous combustion. The mine and company town Leigh Creek were the economic and cultural heartbeat of the community. Facilities at the mine were shared by the community and vice versa. While many mines across Australia and the world enter periods of care and maintenance, few have been actively closed to the point of relinquishment (Bennett and Lacy, 2016). A swift decision to close, followed by a short mining operations shutdown period, presented significant technical and regulatory challenges for both the mine operator and for Regulators. The subsequent joint risk mapping process employed by Flinders Power and South Australian Mining Regulators was a unique real-world example of collaborative mine closure planning and execution. Lessons learnt are valuable for all mines, production facilities and for Regulators, even for those who may wrongly assume that closure is many years away. CITATION:Williams, B and Querzoli, A, 2018. Risk management for minesite closure planning and execution – start now! Lessons from the closure of the Leigh Creek Coalfield, South Australia, in Proceedings Life-of-Mine 2018, pp 68–72 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By M F. Lee

Although the Mt Charlotte gold resource was discovered in 1893, it was only in 1954 that geologists correctly interpreted drill data and defined a large low-grade orebody. The mine has been a large, low-cost and profitable producer since 1962 when bulk mining commenced using cut and fill. From 1968 a combination of long hole open stoping with delayed mass blasting was used. This proved to be an excellent mining method for the large, separate subvertical orebodies. The structured but otherwise good quality rock allowed very large stopes to stand unsupported. Exceptionally large equipment, for its time, was used to efficiently mine, muck and move the ore at low-cost. The mine only just survived severe cost pressures in 1974-76, due to very low gold prices. Better gold prices in 1979 and a need to access deeper ore meant a bold commitment to sink the Cassidy Shaft and refurbish the mine to sustain future profitability. In 1997 the Sam Pearce Decline connected to the underground workings, making it profitable to mine upper level remnant ore. Mining-induced seismicity has been a feature of mining at Mt Charlotte. The main cause has been shearing on structures. A mine-wide seismic system was installed in 1994. Large seismic events have occasionally made management question whether a safe working environment can be maintained. Thorough investigations led to an understanding of the problem and development of procedures to minimise seismicity.

Jan 1, 2000

By Kyle J. H, Misra V. N

The most recent development in gold processing is the increasing use of heap leaching for the extraction of gold from low grade ore, and old tailings dumps. The reason for this trend is mainly to do with economics. The advantage of heap leaching is the considerable saving in both capital and operating costs. However, not all ores are amenable to heap leaching. It is only applicable to well oxidized ores that have suitable permeability char- acteristics, and the gold recovery is poorer than by conventional process. In this study, an attempt has ben made to ascertain the heap leaching characteristics of Western Australian gold ores on the bench scale using multiple, appropriately sized leach columns. The influence of particle size, flow rate, column depth and leaching time on the rate of gold extraction was determined. The percolation rate of cyanide leaching solution was deter- mined with and without gypsum additions. Efforts were also made to minimise particle segregation, fines migration and solution channelling during leaching, so as to improve solution percolation, gold extraction rate and recovery.

Jan 1, 1991

The seam gas content at Westcliff Colliery is 12-15m3/tonne of coal.Composition ranges from 99% CH4 to 52% C02 in one area. Desorption rates are proportional to gas contents and CH4 is preferentially desorbed. A crushed zone of reduced permeability advances with the face - at Westcliff ribside crushed zones are 2.5 to 6.5m wide. Poor strata control widens crushed zones. 12 months of pre-drainage allowed 2 heading development and longer pillars to be used in a virgin area instead of 3 or more headings without drainage. Machined coal may lose as much as 1.6m3/tonne being conveyed out of Westcliff Colliery. Experience differs from mine to mine. Permeation is affected by time, strata movements, changing water content, and changing stress. Permeabilities vary from lOmd for Pittsburgh Seam to less than 1 and for the Bulli Seam. All these data and differences await further investigation.

Jan 1, 1982

By X Hu, Z Pokrajcic, R Embry, P C. Stewart, J Carpenter, E Jones

Whilst the value of Pit to Plant and Mine to Mill optimisation has been proven since the 1990s, sustaining the productivity and efficiency gains typically requires ongoing test work, blast trials, plant surveys, and model calibration services. In contrast, the input to digital twin Pit to Plant or Mine to Mill optimisation is tens to hundreds of millions of tonnes of standard mine operating data. This paper presents a series of digital twin case studies from across the mine value chain, including machine learning testing methodology, model accuracy statistics and the application of Shapley Additive Explanations (SHAP) for model interpretation. These case studies demonstrate how machine learning and data fusion ore tracking connects hundreds of millions of tonnes of downstream performance data to produce digital twin models (operating models that are continuously updated and integrated into the wider Mine to Mill/Pit to Plant ore tracking system). Digital twin modelling software has been used to add block model variables for dig-rate, crusher and mill throughput, recovery (tailings grade), lump yield, product grade and product quality, fines yield and fines in lump. Block-by-block predictions are added to the geological resource and grade control block models as new block model variables. These new block model variables are used across all mine planning time horizons from life-of-mine planning to daily schedules. In addition to the materials handling and geometallurgical prediction case studies, the paper also presents digital twin case studies for drill and blast simulation and plant set point optimisation. The case studies show how digital twin simulation enables drill and blast engineers to simulate the effect of different blast designs in different blast domains using the mines operating data. Plant set point optimisation applies mathematical optimisation algorithms to the machine learning model to provide live operational decision support to metallurgists and plant operators. The digital twin machine learning case studies demonstrate a digital and sustainable paradigm for Mine to Mill and Pit to Plant optimisation.

Jun 22, 2022

By H Kurth, L Balzan

On-belt analysers have been used since the early 1980s in the coal sector to measure ash content in real time for diverting material on conveyors to remove waste, bypass beneficiation and allow suitable material to proceed to the wash plant for processing. Since 2008, a GEOSCAN-M elemental analyser has been used on an overland conveyor in South Africa to divert direct-shipping quality iron ore to bypass a jig plant. This paper focusses on recent evaluation work to determine the suitability of an on-belt analyser to upgrade the processing plant feed in a copper-gold operation.Copper-gold ore samples from New Gold’s New Afton Mine near Kamloops, BC, Canada were tested to assess measurement accuracy over short time increments. A two-minute measurement increment has been used in the minerals sector as a compromise between good measurement accuracy and a useful tonnage (haul truck equivalent size or smaller). At New Afton, this increment represents approximately 35 t of material. Segregation decisions are currently made after visual and sometimes analytical determination, at increments of approximately 500 t to designate material as ore or waste at the drawbell in the cave.Results of test work including the composition range and expected accuracies by element are shown. The operation, which is not mine constrained, was evaluating the potential for ore upgrading through waste and low grade increment diversion to upgrade ore quality feeding the mill. Prompt-gamma neutron activation analysis (PGNAA) was considered as the company recognised that it would measure through the full conveyed cross section continuously and produce multi-elemental measurements unaffected by particle size, dust, moisture content, layering and segregation, mineralogy and belt speed.GEOSCAN analyses over various analysis periods will be collected to identify variability in the conveyed material quality and used to generate tonnage-grade curves so that an optimal diversion (bulk sorting) tonnage increment can be determined. Measurement increment time can be customised to suit site requirements. CITATION:Kurth, H and Balzan, L, 2017. Assessing bulk sorting suitability at the New Afton mine, in Proceedings MetPlant 2017, pp 315–323 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By S Steffen, S Talu, J Poulsen, G Watt, A van As, J S. Ooi

The economic success of cave mining projects is significantly influenced by the secondary fragmentation size distribution of the caved orebody and making the fragmented ore available for extraction. If the cave does not propagate as predicted, it may lead to stalled cave growth and/or localised preferential caving. This can cause significant ore loss and the inclusion of excessive waste in draw columns, both of which damage the economic value of the project. Uncontrolled caving can have severe consequences for the safety and economics of mines. Such safety risks include air blasts due to the formation of excessive air gaps and damage to infrastructure due to surface subsidence. Monitoring the cave-back delivers critical feedback that is required to exert control over its propagation and reduce the likelihood of adverse consequences. Current methods for monitoring cave propagation include access through open holes, microseismic monitoring systems, time domain reflectometers and extensometers. All of these monitoring systems rely on stable holes for installation and ongoing data collection. However, cables in holes often get sheared due to ground movement in the seismogenic zone well ahead of the cave front, rendering the systems useless. To resolve this issue, Elexon Mining, with the support of Rio Tinto, developed the Networked Smart Marker system, which is based on Elexon’s Smart Marker technology. This system provides a more robust and versatile alternative to other cave monitoring systems as the data is transmitted wirelessly through rock, and thus is not vulnerable to hole shearing/dislocation experienced with current cave monitoring systems. Installations at the Argyle block cave have proven that the Networked Smart Maker system can continue to provide information on the cave-back’s location long after all conventional monitoring systems have failed. This paper summarises the findings from these installations and highlights the benefits for all geotechnical monitoring systems reliant on the stability of drill holes to remain functional.CITATION:Steffen, S, Poulsen, J, Van As, A, Talu, S, Watt, G and Ooi, J S, 2016. Wireless system for monitoring cave-back propagation, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 251–256 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By R Witt, M Lowing

Tanking of tunnels is now often specified when inflows exceed as little as 1 L/s/km with a unit distance of 100 m. To demonstrate inflows over a 100 m segment of a tunnel are less than 0.1 L/s with a standard error of 0.01 L/s by timed, gravity filled, volume measurement up and downstream of the segment, the measuring cylinder volume (L) must exceed 10 Q, where Q is the flow in L/s, and the number measurements taken and averaged must exceed 20 . If a standard error of 0.02 L/s is acceptable then 5Q2 measurements must be taken and averaged. If gravity filling is not possible then the number, n, of repeat pumped container measurement required is given by: where: is the 100 m section leakage is the volume filling time is the standard error of volume measurementZ is the standard normal variateK is a coefficient dependent on physical measurement conditions Based on analysis of field data an indicative coefficient of variation of volume measurement is ~0.05.

Jan 1, 2008

By G Guy, J Summerville

Over the past five years in coalmine slope evaluation the application of 3D modelling has increased significantly as software has become more user friendly but also areas requiring evaluation have become increasingly complex. Often simplistic 2D Limit Equilibrium modelling and analysis has been poorly used to solve slope stability issues by back analysis and subsequent forward predictive analysis. A plane strain condition with slope movement perpendicular to the slope strike is assumed where in reality the problem is more complex. This often leads to a misinterpretation of the failure mechanism because the failure mechanism being modelled in 2D does not generally represent the actual failure mechanism observed in the pit, with 2D modelling often oversimplifying a slope. This paper presents a case study where the initial slope assessment and remedial design evaluation was undertaken as a 2D Limit Equilibrium model which led to an overly conservative and costly remedial solution being implemented. Subsequent modelling of the slope using both 3D Limit Equilibrium and Finite Element methods were able to provide a better understanding of the structural complexities associated and correlate well with slope monitoring data to create a more realistic outcome.

Nov 29, 2022

By Morley C

The Mount Charlotte gold mine is located 0.75 km east of the General Post Office in Hannan Street, Kalgoorlie WA and about 3.5 km north of the Fimiston Operations on the famous Golden Mile.Mechanised underground bulk-mining at Mount Charlotte has been in continuous operation since 1963. For the 30-year period ending December 1992, the mine produced 22 million tonnes (Mt) of ore for a recovery of 2.73 million ounces. During 1991/92, the mine produced 1.53 Mt of ore at a head grade of 3.15 gramshonne (g/t) for a recovery of 135 822 ounces.The principal ore source at Mount Charlotte has been the Charlotte Orebody which is now largely mined out. Since 1990, approximately 75 per cent of production has been sourced from the Reward Orebodies. The Charlotte Orebody was a relatively homogeneous quartz stockwork with simple geometry and average bulked grades in the range of 4.0 to 5.5 g/t. This is in contrast to the Reward Orebodies and the more recently defined Charlotte Deeps and Maritana Stockworks, which have complex grade distribution and geometry with lower average bulked grades (2 to 4 g/t). The lower grades are principally due to the decreased density and volume of stockwork venation and related vein halo alteration. Typically, these stockworks comprise a patchy mosaic of quartz veins and vein swarms, with irregular distribution and geometry within the quartz gabbro host rock.

Jan 1, 1993