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Present knowledge of the Pacific floor in- dicates: Postulated subduction zones and/or moving basements overlain by undisturbed sediments. Contiguous mantle convections of conflict ing directions and variable rates. Disharmony between transform faults and mantle convections. =hese features are shown to be difficult to reconcile with conventional hypotheses of sea f 1mr spreading and cast the model into serious doubt.

Jan 1, 1987

By Y Lin, B J. Seligmann, M Hassall, S Micklethwaite

For multi-site mining companies, checking the quality and consistency of the data recorded in risk registers is important for confirming how well mine safety management systems have been implemented. However, this task is complicated by the differences in scope of the site, their particular nature, the complexity of the operations and many other factors that can introduce nuances to the characteristics of the risk registers. We present here an application of a technique called Causal Network Topology Analysis for comparing the quality and consistency of risk registers. By quality we refer to, for example: - missing causal relationships between risks - location of missing controls - focus of risk treatment strategies: prevention versus mitigation controls. By consistency we refer to how causally interdependent are the risk events. There are often causal interactions between the lines of a risk register that mean that the likelihood and consequence scores that are applied to each risk event are not independent. We measure this degree of interactions by: - proportion of independent scenarios per register - efficiency of risk treatment strategy comparison. This approach can indicate quality and consistency differences between registers irrespective of the actual details of the site or operation. This occurs by comparing aspects of the structure of a causal network extracted from how the risk events, causes, controls and consequences causally interact. In this work we compare pairs of registers to demonstrate the approach.

Apr 16, 2024

The Chamber of Minerals and Energy of Western Australia Inc (CME) is the peak resources sector representative body in Western Australia. The paper gives a summary of the role and objectives of the CME, including its history, structure and key program areas. Particular attention is given to the role of the CME in the Eastern Goldfields of Western Australia. The paper details the types of CME membership that are currently in existence. The paper argues that a strong and vibrant CME is vital to secure the resources sectorÆs growth and development in future years.

Jan 1, 2006

By J J. L du Plessis, A Spaeth

The objective of this paper is to demonstrate the efficiency of machine-mounted active explosion suppression systems (AESS). Their proven effectiveness against methane explosions is highlighted, as well as their additional potential when used as an early warning system should frictional sparks occur during the coal-cutting operation at the coalface.Methane and coal dust explosions remain one of the primary and unpredictable risks in underground coal mining. Although technologies such as proactive ventilation, methane monitoring and wet-head cutting systems are widely used as preventative measures, there are no fail-safe controls able to reduce the risk to zero. None of these controls is designed to be able to counter the negligence associated with human error or to deal with rapidly changing face conditions which could lead to flammable gas ignitions. Machine-mounted AESS have been installed on various continuous miners as an additional control to further reduce the risk of ignitions and to act as a safety shield when all the other precautions taken have failed. This was the primary motive for the development of AESS. As an additional feature, the ExploSpot® AESS is being enhanced to identify frictional ignition sources at the coalface that reach a predefined monitoring level. This functionality may serve as a further effective preventative measure.As part of ensuring coalmine operational safety, the detection of frictional ignitions can play a huge role in creating heightened awareness of potentially dangerous situations. By being able to process the frictional spark burning pattern, the AESS could support the decision-making process regarding whether to continue the coal-cutting operation, whether there is a need for maintenance or whether the operation should be stopped completely due to the increased risk of a flammable gas ignition and an ensuing explosion.CITATION:Spaeth, A and du Plessis, J J L, 2015. Enhanced risk reduction using early warning technologies embedded in active explosion suppression systems, in Proceedings The Australian Mine Ventilation Conference, pp 315–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By M Simanjuntak, A M. Supomo

PT Freeport IndonesiaÆs copper/gold operation disposes of approximately 222 000 dry metric tonnes of tailings per day via two thickeners. Reduction of the flocculant dosage rates in each of the tailing thickeners has been achieved with the installation of Clarometers«, modifications to the existing operating DCS control strategy and a change in plant flocculant. This has reduced the flocculant consumption rate in the last twelve months by approximately 20 per cent. It has also highlighted the disparity in the settling rates of the two thickeners. Collaborative efforts between Cytec technical site engineers and Freeport operational personnel have made possible the overall gains achieved in the tailings thickener optimisation.

Jan 1, 2003

By A Fowler

The unpredictability of the location, grade and width of narrow-vein deposits presents difficulties for mine geologists and engineers attempting to estimate, schedule, forecast and mine their deposit profitably. This unpredictability stems not only from the grade distribution within a vein, but also the irregularity of vein geometry in three-dimensional (3D) space. Traditional deterministic methods of modelling vein geometry do not account for the inherent variability of the veins, resulting in significant errors when using limited drill hole information. This paper presents a probabilistic method of modelling narrow-vein deposits using sequential gaussian simulation (SGS), which can quantify this variability and improve production forecasts. Vein geometry, thickness and grade are simulated to provide a number of different equi-probable realisations that each honour the drill hole and face sample input statistics. An example is presented from the Augusta narrow-vein Au-Sb mine in central Victoria, where the simulation results are validated against the input data and survey pick-ups of the veins along ore drives.

Aug 22, 2011

Welcome to this 13th Congress of The Council of Mining and Metallurgical Institutions. It is twenty one years since The Australasian Institute of Mining and Metallurgy last hosted this congress and it is a privilege and a pleasure for The AusIMM to have that responsibility once more. The theme of this congress "The Twenty-First Century - Mining for Mankind" stimulates many thoughts. The first thought that it generates in me relates to the reference to the 21st Century. We are still 14 years away from it and already consideration of the beginning of the next millenium is becoming something of a cliche. If we feel like that about it now, how will we feel at the 14th Congress of the CMMI in 1990, or the 15th in 1994 or the 16th in 1998? If we do all the crystal ball gazing about the 21st Century this week, those poor devils in the 1990s will in fact have nothing to talk about. Of course that is not the case. This is a very appropriate time for those of us concerned with mining and metallurgy to contemplate the next century. Fourteen years is about the extent of forward planning necessary in the mining business. I sometimes feel that most people do not take seriously the need for long range planning in our industry. Politicians, investment fund managers, and others under severe short-term pressure to perform in our hyperactive world may nod in apparent appreciation of our long term plans but their actions in the interests of expediency often betray-them.

Jan 1, 1986

By G K. Robinson

Variations in many aspects of physical and chemical grade are often of concern to mining operations and mineral processing plants. In most circumstances these amounts of variation are predictable. At the time of planning new operations, we should be able to predict the amount of sampling and testing variation which our sampling devices, laboratory procedures and on-stream analysis devices will achieve. We should know how well our stockpiles, reclaimers and bins will homogenise material (or whether segregation will actually increase the amount of variation). We should be able to predict the amounts of variation that will occur on the important time or tonnage scales at the crucial p oints in our proposed operation. And once these amounts of variation are reliably known, mine planning will seem a little bit more like dealing with known knowns rather than like dealing with unknown unknowns.The first step towards quantifying amounts of variation for planned operations is to assess amounts of variation for existing operations. How many operations have estimates of amounts of variation in their databases? How often are people able to partition amounts of variation into amounts due to sampling error, amounts due to sample preparation, amounts due to assaying, and the amount of real variation in the stream of material?CITATION:Robinson, G K, 2012. Making sure that the amount of grade variation is a known known, in Proceedings Project Evaluation 2012 , pp 159-162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By M Lund

Due to operational and regulatory practicalities, pit lakes will continue to be legacies of many open cut mining lease relinquishments. Unplanned or inappropriate management of these significant geographical features may lead to a short-term liability to all stakeholders during mining operations, or to ongoing liability to the local community and environment following lease relinquishment. However, the potential for pit lakes to provide benefit to companies, communities and the environment is frequently unrecognised and yet may be a vital contribution to the sustainability of the open cut mining industry. Improved remediation technologies are offering more avenues for pit lake end use than ever before, at the same time mining companies, local communities and regulatory authorities are also becoming more aware of the benefit these water resources have to offer. Sustainable pit lake management aims to better minimise short- and long-term pit lake liabilities, and yet also to maximise short- and long-term pit lake opportunities as well.

Jan 1, 2006

By P Audet, D R. Mulligan, D Doley

This analysis attempts to reconcile existing ecological theories, rehabilitation planning goals and implementation constraints in the form of a rehabilitation paradigm that considers potential and pragmatic ecosystem transformation pathways. The framework prioritises multiple developmental scenarios for post-disturbed landscapes within a continuum of ecological outcomes. A feature of the framework is that ænovelÆ ecosystems and agro-ecosystems, having a range of commercial and societal values, are valid outcomes spanning the conceptual divide between the ecological functions of under-rehabilitated versus re-instated ænaturalÆ landscapes, especially in a changing environment. Landscape suitability analyses are considered to be fundamental to the incorporation of regional landscape and climate in the implementation of land rehabilitation and management strategies. Altogether, the paradigm could facilitate the identification of widely pertinent rehabilitation goals having direct implications at the regional scale of restoration ecology and acceptance of the need for ongoing commitment to the management of disturbed environments.CITATION:Audet, P, Doley, D and Mulligan, D R, 2012. Can ænovelÆ ecosystems offer suitable rehabilitation alternatives for post-mined landscapes?, in Proceedings Life-of-Mine 2012 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By D Mee

The Western Mining site at Olympic Dam, near the community of Roxby Downs in South Australia is one of the largest orebodies of its type in the world. It contains known reserves of over 10.6 M tonne of copper, with economic secondary metals including uranium, silver and gold. In 1996, an expansion project was commenced to increase mine production approximately threefold, to produce 200 000 tonnes pa of copper, 4600 kg pa of uranium oxide, 3600 kg pa of gold and 50 000 kg pa of silver. This expansion included both underground mining and surface processing investment. Because of the scale of operations, it was decided that ore should be transported underground by a railway system. In July 1997, ALSTOM Automation and Control Limited (then Cegelec Australia Limited), was awarded the contract to deliver a control system to manage and automate the rail haulage system for Western MiningÆs Olympic Dam Mine, as part of this major upgrade and extension project. This paper explains the overall design and the approach taken to implement route selection, route locking, train interlocking and track topology using normal industrial control equipment such as Programmable Logic Controllers. Included is a discussion of how this automation has improved the productivity of the haulage system by more than 15 per cent.

Jan 1, 2000

By T Davis

Cameco Corporation operates the high-grade 140 tpd fly-in/fly-out underground McArthur River Uranium Mine in Northern Saskatchewan in a joint venture with Cogema Resources Inc. Reserve grade is in excess of 20 per cent U3O8 with current mining grade averaging 16 per cent U3O8. Due to the high radiation potential of the ore, the non-entry mining method of raiseboring was chosen to minimise worker radiation exposure potential. The raisebore and extraction horizons are located in waste rock with the orebody located between horizons. Ore produced by raiseboring is delivered by LHD to an underground SAG mill and is then hydraulically hoisted to surface receiving facilities after underground thickening to 50 per cent solids by weight. Concrete backfilling is utilised. The orebodies at McArthur River are adjacent to water bearing sandstone. Ground freezing is therefore employed to isolate the ore from this water bearing ground. Calcium chloride brine at -35¦C is circulated through a series of cased boreholes to establish freeze walls up to 25 metres in thickness. At 18 000 000 lb of low cost U3O8 production per annum, McArthur River ranks as the worldsÆ largest uranium mine. Over 50 per cent of the workforce resides in this sparsely populated area of Canada with approximately 40 per cent being of aboriginal ancestry. Site operations must cater for winter temperatures as low as -50¦C.

Jan 1, 2002

By M, C Silveira, C Ellice, D Christensen

Peak Gold Mines (PGM), a member of the Rio Tinto Group, is an underground and open cut gold mining operation located near Cobar, NSW. A multi-phase study was initiated in 2001 in support of developing a dry æmoisture store and releaseÆ cover system design for the PGM tailings dam, which contains potentially acid-forming tailings material. The first phase consisted of characterising the tailings and potential cover material (waste rock from an open cut operation) as well as soil-atmosphere cover design modelling. The second phase involved construction of two cover system field trials on the tailings dam and installation of a variety of field instruments to monitor the hydraulic performance of the test covers during all seasons of the year. Field performance monitoring commenced in April 2002 and will continue for a minimum of two wet-dry climate cycles (third phase), prior to using the field data for calibration and subsequent validation of numerical models developed for the cover system trials (fourth phase). This paper describes the work completed for the first two project phases and also discusses the initial performance of the cover system trials.

Jan 1, 2003

By M McDonald

KiwiRail has a goal of significantly improving passenger rail services to west Auckland, as part of its DART (Developing Auckland’s Rail Transport) suite of projects. The New Lynn Rail Trench (NLRT) project was a significant component of this work. The NLRT project facilitates essential doubletracking of the Western Auckland line, and provides a new commuter transportation hub within a busy town centre.The 1.5 km stretch of track through the New Lynn town centre has bisected the township for over 80 years. Double-tracking the line provided the opportunity to grade-separate road and rail, which would help to re-connect both sides of the township and enhance public amenity and safety.KiwiRail employed an Early Contractor Involvement (ECI) procurement model engaging a consortium comprising Fletcher Construction, Beca Infrastructure and Synergine to develop a Design and Construct solution.With weak soil conditions and high groundwater levels, a diaphragm wall construction method to form the trench walls was selected as the best solution. Further challenges to construction included working within a narrow rail corridor constrained by buildings along much of the boundary, and a requirement to keep the existing line open for rail services. Detailed construction planning was required to ensure rail and construction safety in a constrained space whilst building the trench walls, propping these walls during excavation, and constructing the base slab in the most efficient way possible.This paper will detail the geotechnical conditions and the additional constraints that made this rail trench a challenging structure to design. It will also describe the fi nal design and construction methodologies that were employed, that allowed very successful completion of the project.Additionally, this paper will review the design and construction lessons applicable to the current Victoria Park Tunnel project, and indeed for all future cut and cover tunnel projects in the Auckland isthmus.

Mar 8, 2011

By S Bouzalakos, W Timms, H Malli

Combining ultramafic mine tailings and acidic mine drainage via mineral carbonation to sequester carbon dioxide, presents an opportunity to minimise waste on mine sites. Low pH mine water with trace element concentrations can be effectively treated by high magnesium mine tailings, a useful source of finely ground reactive matrix. By using milled tailings for mineral carbonation, there are negligible energy requirements for communition of ore rocks to reduce particle size. This study aimed to assess the technical applicability of reacting ultramafic tailings and acidic mine water through mineral carbonation technology in the mining industry. Dissolution has been identified as the rate limiting stage in mineral carbonation; hence the study focused on identifying optimal dissolution conditions. Ultramafic tailings (particle size <100 µm) derived from serpentinite ore, were reacted with a typical mine water that was synthesised in the laboratory. Through variances in the solid to liquid ratios and temperature of dissolution, a maximum five per cent magnesium dissolution efficiency was reached at 50 g/L and 100°C. The acidic mine water was neutralised (from pH <2 to pH ~6) and iron, copper and zinc ion concentrations reduced significantly during the formation of solid precipitates. Carbonation was undertaken by injecting carbon dioxide into the magnesium-rich solution to form stable carbonates. The experimental work demonstrated proof of concept; however, dissolution efficiency and carbon dioxide sequestration was low, indicating that further research would be required before larger scale implementation.CITATION:Malli, H, Bouzalakos, S and Timms, W, 2015. Ultramafic mine tailings to treat acidic mine water and lock away carbon through mineral carbonation, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 133–136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

Valuers of mineral properties should be aware that accountants are a major user of their opinions of value. Reliance by accountants can range from obtaining comfort that book values in balance sheets are not overstated to establishing values by which to assess the fairness of a takeover offer. Accountants using mineral property valuations clearly can't be expected to have the same level of expertise as the valuer and ""second guess"" the valuation. But they do have an obligation, under the ASC guidelines and their own professional standards, to'check the logic and reasonableness of the valuation before being able to rely on it. This means reviewing the valuation report for general sensibility, discussing the methodologies and assumptions with the valuer and being satisfied as to his competence and independence. This paper outlines how accountants use mineral property valuations, the level of scrutiny applied to such valuations and the problems commonly encountered in practice by accountants seeking to rely on them. The paper also explains how values of-mineral properties are established in company balance sheets and why these often differ, quite validly, from fair market values.

Jan 1, 1994

By D T. Ribeiro, J F. C L Costa, J C. Koppe

Drilling and sampling are responsible for most of the costs during mineral exploration, especially in multi-elements and polymetallic deposits, such as iron, manganese and bauxite deposits. On these deposits, often it is necessary to estimate multiple attributes at several granulometric fractions, ie distinct particle sizes. This paper investigates the effect of sampling at a close spacing grid only the head grades for the multiple chemical species in iron ore deposits. The remaining required data at the various grain sizes are sampled at a sparse grid. The derived geological model is checked for precision and accuracy comparing the output obtained against a model obtained using a complete isotopic data set including head grades and chemical analysis at each granulometric fraction analysed at all sampled positions. Among the several tested alternatives, the best procedure for dealing with the posed problem involved utilising the correlation coefficients between the grades at distinct fractions to obtain an isotopic database prior to interpolation. Cokriging was the method used, based on the intrinsic coregionalisation model. Estimates were obtained with the quality needed for the proposal of the study. Results showed that at least 50 per cent of the blocks were estimated with errors less than ten per cent relative to the grades obtained at the reference model, using only 15 per cent of the granulochemical data employed to obtain the reference model. The methodology also preserved the correlations between the attributes in their several granulometric fractions on the estimated model.

Sep 26, 2011

During the course of an investigation into the fundamental chemistry of the cyanide process, it became evident that the usual method of determining protective alkalinity was not completely satisfactory. T.he routine method for the determination of protective alkali by first removing free cyanide by the addition of silver nitrate, followed by titration of alkali with dilute acid using. phenolphthalein as indicator, can be shown to give correct results only when the alkali is a strong base. For other sUbstances, the alkali so determined is not the protective alkali. In view of the complications associated with the presence of zinc in cyanide solutions the discussion will be restricted in the first place to solutions free from zinc. Until the chemistry of simple cyanide solutions is placed on a quantitative basis it will be difficult to elucidate the behaviour of complex mill solutions.By the use of physico-chemical theory, it is possible to treat certain aspects of 'the chemistry of cyanide solutions in a manner which not only illustrates the important variables involved, but which also shows the need for care in interpretIng results obtained by conventional methods.In the following, comparatively simple systems are discussed; the principles established should be of use in interpreting the behaviour of more complex solutions. The methods described are not intended for routine work, but may be regarded as supplementary to the usual analysis carried out for the control of plant solutions, or as alternatives to be used when the latter do not appear to be satisfactory.

Jan 1, 1948

By A Crawford, P Manton

Telfer is a gold/copper operation, currently operating one open pit mine and one underground mine. The ore processing plant consists of two parallel trains involving semi-autogenous mill, ball mill and crusher (SABC) grinding, flotation and leaching. Due to receiving relatively high grade underground ore for over half of its total feed, Train 1 frequently experienced cleaning circuit overloading during high production periods. This resulted in losses in recovery and ineffective concentrate upgrade. As a quick and simple solution, the Train 1 copper flotation circuit was reconfigured to send concentrate from the first two rougher cells directly to the final concentrate and return the cleaner scavenger tailings to the third rougher cell. These modifications have resulted in a 1.4 per cent increase in plant copper recovery with no change in final concentrate grade. Preliminary results also indicate gold recovery has increased by more than 1 per cent since the circuit reconfiguration. Other benefits include less spillage, more friendly circuit to operate and a more consistent metallurgical performance. Focus for the next phase of optimisation is on concentrate upgrade. A number of opportunities have been identified and are currently being investigated, including staged reagent addition, single stage cleaning of the first two copper rougher concentrates, regrinding of the remaining copper rougher concentrate prior to cleaning and process control based on a machine vision system.

Jan 1, 2009

The mining industry has a well deserved reputation earned over the years for innovation, engineering, management and the quick application to mining of emerging technology. The cumulative result is the economic exploitation of lower grade resources. The developments during the last decade have done nothing to tarnish the reputation. There are many that come easily to mind: the use of contractors for both surface and underground operations, a trend toward mine management contracts, the increasing recognition of the economic potential of ground support, and the development of physical measures to achieve it, - sophisticated measures to analyse blasting , and thus improve fragmentation, - instrumentation to assist geotechnical appraisal, - the development and application of the powerful and flexible, excavator, - the evolution of measures to improve grade control, - massive improvements in equipment productivity and reliability built largely around the application of hydraulics, - the development of powerful computer packages for orebody modelling, mine design and extraction, - simple "dense" fill systems, - maintenance management techniques including the greater use of off-site maintenance of exchange components, - the utilisation of communication systems for data transfer.

Jan 1, 1989