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By B A. Webler, P Su, P C. Pistorius

Advanced high-strength steels (AHSS) typically have much higher aluminium concentrations (by an order of magnitude or more) than conventional low-carbon aluminium-killed steels. The resulting lower oxygen activity at the steel-slag interface changes the kinetics and thermodynamics of steelslag reactions. Previous work showed that the rapid transformation of alumina inclusions to spinel inclusions, and spinel to periclase, occurs because of the relatively high concentration of dissolved magnesium. In this paper, experimental results on nitrogen removal by ladle slag are compared with predictions based on the available thermodynamic databases. As in previous work, the kinetics was modelled by assuming mass transfer control, with steel or slag mass transfer limiting. The results show that significant removal of nitrogen by steel-slag reaction is possible.

Aug 21, 2024

By D M. Brady

Underground coal mines in Australia have embraced the use of various inertisation techniques both proactively and reactively. The use of such techniques can have a significant influence on ratios and trends used to monitor the status of the underground environment. Whilst control strategies should never be ignored in favour of preserving the integrity of ratios, the influence and significance of the changes likely to be seen should be anticipated and understood for reliable interpretation of the situation. This paper looks at the influence inertisation techniques can have on results and subsequent interpretation.CITATION:Brady, D M, 2013. The influence of inertisation techniques on gas interpretation, in Proceedings The Australian Mine Ventilation Conference , pp 259-264 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By A Grigg, L Hackett

Alcoa operates two bauxite mines at Huntly and Willowdale, located within the jarrah forest south-east of Perth in Western Australia. Ore reserves are shallow but extensive, and mining pits averaging around 20 ha in size are distributed across a mining region in a mosaic pattern, linked to a centrally-located crusher by a radiating network of haulroads. A mining or crusher region is defined partly in terms of economic haul distances, and new regions are opened once the current regions’ reserves have been mined. Since commencing in 1973, the Huntly mine has constructed and progressively closed three previous mining regions and is presently in a transition from the fourth and current region of McCoy to the new region of Myara. At present rates of production, approximately 450 ha is cleared, mined and rehabilitated each year.The value of topsoil in returning a diverse mix of native jarrah forest plant species and supplying nutrients, organic matter and soil biota to rehabilitated areas has long been recognised. Managing the topsoil resource is therefore a critical element in the success of rehabilitation outcomes, but the distribution and dynamic nature of mining operations pose significant planning and logistical challenges. The regionalised approach to mining at Huntly also presents a range of issues for what are, in effect, soil management plans for episodic mine closure. The nature of mining and rehabilitation operations are described, together with the planning processes that Alcoa follows to quantify, track and report on soil movement. A case study of the Huntly mine demonstrates that an integrated operational and life-of-mine planning process is essential for successful and cost-effective mine rehabilitation.CITATION:Hackett, L and Grigg, A, 2014. Topsoil management for long-term mine operation and closure – a case study from Alcoa's bauxite mining operations in south-west Australia, in Proceedings Life-of-Mine 2014 , pp 609–614 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Nixon J. C, Reynolds C

Three principal features of the ore at Captain's Flat, New South Wales, tend to complicate concentration of the valuable minerals, these being:1. The ore occurs in three more or less separate bodies which vary in texture and mineral ratios. Mining of constant proportions of the three sections, or adequate blending of the ore, is not fully effective, and consequently the flotation section is subjected to feedof varying texture.2. The mineral association in the heavily pyritic ore is extremely intimate. Composite particles exist even at 20 micron sizeI, and probably finer.3. The copper content of the ore averages_about 0,6%, which is high enough to justify recovery of the chalcopyrite in a separate concentrate. A review of the metallurgical history of the mine shows that this feature has been the cause of the several major changes in flowsheet of the flotation section since the commencement of milling.METALLURGICAL HISTORYThe mine started production in January 1939, at the rate of 250 tons per day of sulphide ore, assaying 0·68% Cu, 6·52% Pb, 10·8% Zn, and about 1 dwt. Au and 2 oz. Ag per ton.

Jan 1, 1952

Both here and in Australia, the unique commercial and tax features of joint venture are finding favour in forestry, fishing, technology and infrastructure projects. For New Zealand mining companies, joint ventures provide a means of access to foreign know how and investment funds, while retaining their corporate independence and their hard-earned tax losses.   This paper discusses some of the practical income tax and GST considerations where a joint venture structure is contemplated. The first part of the paper considers income tax, and in particular how joint ventures enable companies to access and carry forward tax losses. It explains why a joint venture may be advantageous relative to a jointly owned company.   The second part of the paper concerns GST and the focus is on two aspects: 1.   Joint ventures may be registered for GST. In some instances they have no choice and are required to do so. Where a joint venture is registered in respect of a taxable activity, the members are not permitted to register in respect of the same activity. This may be problem where the member has incurred its own expenses and the member wishes to register in its own right to claim back the GST on those expenses. This paper explores the issue and possible solutions. 2.   It is not uncommon to see joint ventures claiming GST on the costs of production, and the production being sold (and GST is being charged) by the members. In this paper we consider whether these arrangements have a tax risk, and what can be done to make them technically sound.

Jan 1, 2005

By H Rossiter, C Simpson, J Market, P Jeanneau

Downhole Assay tools are a geophysical method to collect an instigated response from the material surrounding a drill hole and deliver a multielement proxy-assay. They were first tested in the Pilbara at the turn of this century, however since 2011 they have seen a more focused testing and implementation regime with multiple companies across multiple Pilbara mine sites. The increase in the volume of data has led to advances in the measurements and significant improvements to the efficiency of the calibration process. Pulsed Fast and Thermal Neutron Activation Analysis (PFTNA) downhole assay tools collect gamma photon spectra which are characteristic of elemental signatures. One of the key components of the technique is calibrating the spectral signatures to lab assays. Each tool is slightly different due to the organic nature of the crystal detector and therefore responds slightly differently. Environment and hole conditions as well as ore characteristics are among other external influencing factors. Thus, a unique calibration is required for each tool. In addition, not all elements are measured directly, but some are actually characterised by proxy, meaning that if the signal-to-noise ratio for an element is small, it may be easier to identify the mineral or geology in which that element is found and thus infer the concentration of the element. These proxies may differ for each site or geology type within a site. There is a large advantage to build a unique calibration per tool at each site rather than a universal one to be used across the whole province. This then delivers the accuracy and precision of measurements that mining companies require for modern operations. Early work with the tool required several thousand metres of calibration data and several weeks of analysis to build each calibration. This process has now been streamlined to significantly reduce the amount of data required and the analysis time to make it much easier to introduce new tools to a site with an existing model or to create new models. This paper details the calibration process, illustrating the increasing accuracy of the models as training data are acquired as well as the methods for transferring a calibration from one tool to another.

Nov 8, 2021

During a mineral exploration program in an environmentally sensitive area nearMount Painter in South Australia, a helicopter was used to position, construct and service drilling rigs in order to avoid the need to create new access tracks. The drilling program was designed to optimise the advantages of natural landforms in order to minimise the environmental impact of site construction and drilling activities. This minimisation of land disturbance reduced the required amount of rehabilitation measures to the extent where all impacts of the helicopter-supported programme had disappeared within 12 months of completion of work.

Jan 1, 1995

By P M. Ashley, M T. Costelloe

The Mary Kathleen tailings storage facility (TSF) contains 7.1 Mt of uranium mill tailings. This waste repository was rehabilitated in the mid-1980s using a multibarrier dry cover. At the time of mine closure, it was predicted that acid mine drainage (AMD) generation would not eventuate and that uranium, heavy metals and radionuclides would be adsorbed within the tailings and not seep from the TSF into the environment. This study reports on the environmental status of the TSF. Gamma-ray measurements indicate an intact dry cover of the waste repository. However, seepage (~0.5 L s-1) of acid (pH 5.71), saline (0.31 per cent), high conductivity (8.8 mS cm-1), slightly oxygenated (DO 2.6 mg L-1), radioactive waters occurs from the toe of the tailings dam into the former evaporation ponds and local drainage system. Seepage waters are calcium-magnesium-sulfate rich with elevated Fe, Mn, Ni, U and Zn values. Oxygenation of tailings seepages causes the precipitation of Fe and coprecipitation and adsorption of other metals (Pb, U, Y), metalloids (As), rare earth elements (Ce, La) and radionuclides (U-235, U-238, Th-227). In contrast, Ba, Ni, Sr, Mn, P, S, Ca, Mg, Na and K as well as Ra nuclides (Ra-226 and Ra-228) remain in solution until pH neutralisation and evaporation lead to their precipitation in efflorescences and sulfate-rich evaporative sediments further downstream. Dry capping of Mary Kathleen uranium mill tailings has resulted in physical containment of the wastes. The dry cover shows no signs of erosion and radiation levels are within acceptable limits. However, the flow rate of surface seepage from the TSF occurs at a much higher rate than predicted. Also, the neutralising potential and adsorption capacity of the tailings and underlying aquifer were overestimated at the time of mine closure. AMD has developed mobilising metals, metalloids, rare earth elements, alkalis, radionuclides and sulfate from the waste repository into surface water seepages.

Jan 1, 2003

By D Kent

The introduction of digital technologies into the underground mining industry, in both coal and hard rock mining, has enabled many high bandwidth applications to be adopted by mines.Digital networks based on 802.11 b/g/n open Wi-Fi standards allow for many applications to be run over a single communication backbone. One important application has been tracking personnel and equipment via RFID tags. This tracking application has in turn formed the basis of a Proximity Detection System (PDS) or Collision Avoidance Systems (CAS). The paper discusses the growth in digital technology as the communication backbone in underground mines which has allowed the ‘convergence of technologies’ that has been occurring in the general business world to be available to underground mine operators. Then the paper will focus on the use of the technology in the increasingly important are of risk control around mobile plant underground. The specific use of digital devices for proximity detection, in both hard rock and coal mines, to provide a system that can deliver an additional level of control to the risks associated with people-vehicle interactions underground is discussed. The initial implementation of PDS in the hard rock mining environment is based on two zones of detection, required for large and relatively high speed vehicles. Information will include:•the principles of the underlying technology,•installation learnings and effectiveness, and•change management methodology and issues.The most recent development to integrate Mine Site Technologies (MST) PDS with Frederick Mining Controls’ HazardAvert® System to extend the overall Proximity System’s functionality in hard rock mines and for use in coal mines is overviewed.

Mar 21, 2011

By A Mooney, G Balog, P Burns, R Brooks

This paper outlines the rationale for the location of the crusher, geotechnical analysis and basis of ground support design, design and scheduling of the chamber and supporting excavations as well as the operational outcomes and lessons learned. Contributions from mining operations, planning, geotechnical and infrastructure teams enabled the Crusher Station One excavation to be completed on schedule, with opportunities taken for underground mining and infrastructure to work safely in parallel to deliver crusher station infrastructure on schedule. Installation of crusher infrastructure was ongoing at the time of writing.

Mar 15, 2021

By S Thacker, M Noakes

The Newmont Tanami Operations (NTO), formerly the Granites Gold Mine, commenced operation in the mid-1980s with tailings deposition evolving over the past three decades as production has increased and the operation has expanded. Paddock-style tailings storage facilities (TSFs) and in-pit tailings deposition have fulfilled the tailings requirements for NTO over its lifetime with the technical specifications of these facilities improving over time in line with the positive development of standards, guidelines and best practice.This paper reviews the options for tailings storage facilities at NTO and the many considerations that have been analysed and deliberated upon before settling on specific TSF types and designs. It also explains the operating philosophies of the tailings deposition and how the facilities have always strongly maintained the optimum capture and retrieval of water. The current TSF design and criteria is presented, along with the introduction of dry tails harvesting for use in paste production as a backfill product for the underground mine. Tailings deposition and recovery remains a critical function of the Granites process to ensure long-term operation and gold production.CITATION:Thacker, S and Noakes, M, 2015. Newmont Tanami Operations – tailings storage facilities, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 305–314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By R Wolff

One critical factor in open pit mining projects is the estimation of the recoverable reserves. The reason for this is that at the valuation stage there is a lack of information about future metal prices and production costs. Consequently, the estimation of the recoverable reserves needs to be done based on a fixed break-even cut-off grade (BECG), in which fixed expected metal prices and production costs are assumed throughout the operating life of the mine (OLM). In this paper, an alternative technique for estimating the recoverable reserves of an open pit mining project is presented and explained in detail. The main characteristic of this technique is that it estimates the recoverable reserves of the project using mining costs as reference: this is done due to the fact that mining costs are easier to model than metal prices. Another important characteristic of this technique is that it uses the uncertainty of the geology of the orebody, given by simulations of the deposit, to make final strategic decisions, such as the selection of the operating life of the mine and the optimal production rate, which minimise the risk of not achieving future production targets while maximising the upside potential of future rewards. As it will be shown, the final outcome of the proposed technique is the generation of a robust open pit design, that include cutbacks and ultimate pit limits, called the marginal open pit mine design (MOPMD). One characteristic of the MOPMD is that, at each production period, it will be characterised by their respective geological uncertainty, given as probability distributions of ore, waste and metal quantities, and by marginal economical project indicators, such as cut-off grades and metal prices, among others. The details follow in the paper.

Jan 1, 2006

This paper will first discuss the fundamental requirements for reliable discharge of backfill by gravity alone at high per cent solids. This discussion will include brief mention of the underlying principles of saturated solids flow contrasted to that of stirred tank or dilute discharge systems. Here the need to possess full knowledge of the flow properties of the stored material will be highlighted. In addition proper account must be made of the silo overflow weir and settling capacity to match plant throughput. Here opportunity will be taken to highlight the complexity of this multi-phase flow situation as well as the general yet paramount requirements for reliable solids flow. It will be shown that by proper attention to the multi-phase considerations gravity discharge of slurries as a consolidated bed with minimal water content is possible. Such high solids discharge results in greatly reduced demand for process water. In addition pumping costs are reduced as is the delay time associated with the mine drainage operation. Confirmation of successful applications will be highlighted by reference to several recent case studies. In the concluding phase mention will be made of the key yet very simple and effective operation techniques which enhance reliable discharge. The simplicity and reliability of properly designed gravity discharge backfill tank systems suggests increased application of this technology by the mining industry.

Jan 1, 1998

The use of mining by-products for beneficial use may face approval, and acceptance barriers. This paper described the use of a sustainability framework to assess the safety, effectiveness and economic value of modified bauxite residue (Alkaloam«) for use on agricultural land in the Peel-Harvey region of Western Australia. The results indicate the merit associated with using this by-product from a safety and, private, community and environmental value perspective. They may be used to indicate the worth of pursuing any future community acceptance and agency approval process.   The use of Alkaloam« for beneficial use on agricultural land in Western Australia was first investigated over 25 years ago. Efforts to gain regulatory approval and community acceptance of Alkaloam« have had a complicated and enduring history. Understanding and assessing the value of a by-product using social and economic considerations, in conjunction with an environmental assessment, provided a more complete evaluation to that previously used.

Jun 1, 2010

By P Yß±ez, G Ferguson

The El Teniente mine produces more than 340 000 tonnes of fine copper per year from an industrial complex of underground mine, concentrator and smelter. Mass caving methods are employed to deliver approximately 95 000 tpd of ore to the mill, from a number of sectors underground, each sector being in effect a large-scale mine in its own right. This mining activity has faced challenges over the course of the last century such as:the capacity of the underground mine has been expanded to maintain and increase output of fine copper; the increasing size of the ore fragmentation forced to change the mining method to achieve the high productivity and profitability required in the business; and to modify the mining methods to continue mining at depth with safety. Fundamental activities in these mining methods, for the successful initiation of caving and subsequent draw, are:undercutting the base of the block or panel by blasting; and excavating of drawbells. The undercutting design evolves mainly on the height of the blasting to manage the change on ore fragmentation. The methodology move away from incorporating massive areas, typical of the block caving method, to a continuos blasting, typical of the panel caving method. Drawbell design changes on geometry, dimensions and sequence of excavation to deal with a corse ore fragmentation and the resolution of mining difficulties in the form of major rock bursts and collapses of production facilities. This paper focuses upon the evolution of the undercutting and drawbell design used at El Teniente mine and techniques under consideration to deal with future caving operations to provide the bulk of the daily production for the foreseeable future.

Jan 1, 2000

In a ætypicalÆ gold deposit each tonne of ore will contain tens of millions of very fine gold particles, whereas; at Bendigo the majority of gold in each tonne of ore is present in just five to 15 very coarse gold particles, a distribution more akin to diamond deposits. At Bendigo the minimum sample size required for good assay repeatability is estimated at 4.5 t for each assay. Drill core samples are several orders of magnitude too small to generate representative assays.The drilling data are characterised by a nugget effect approaching 90 per cent, a very skewed distribution and, on average, under-report in situ grade by 50 per cent to 75 per cent. Since 2002 Bendigo Mining NL has completed 47 000 m of diamond drilling, 1200 m of on reef development, collected and processed 100 bulk samples (150 t each), 800 mini bulk samples (50 kg each) and processed in excess of 25 000 t of ore through a pilot plant. The results of this work have provided the information required to develop and verify a robust grade estimation procedure. No standard geostatistical manipulation of the drilling assay data can generate an accurate grade estimate as the samples and associated assays are not representative of the ore being sampled. The recognition of this fact was critical as a radical transformation of the raw drill assay data was required to develop a workable methodology for grade estimation in such a high nugget environment. The aim of the transformation was to reduce the nugget effect and high variance and so approach a lognormal assay distribution. Ideally the average drill grade would approximate actual in situ grade and the assay distribution would reflect actual grade distribution within the reefs. Following the data transformation simple block modeling within the defined resources allows grade estimates to be made that can be used in the estimation of Indicated Resources and hence Probable Reserves. The grade estimates have been checked by extensive bulk sampling and processing of 25 000 t of ore (three per cent of total resource) through a pilot plant with planned full scale mining to provide the ultimate verification.

Jan 1, 2004

The Ernest Henry Mine is an open pit copper-gold mining operation located in north-west Queensland, Australia. It is owned and operated by Xstrata Copper with a current concentrator throughput of approximately ten million tonnes per annum. The pit will cease mining towards the end of 2010. Extensive surface diamond drilling has confirmed an extension of the orebody to depths of 1000 m below surface. A prefeasibility study was commissioned in late 2006 to investigate underground mining options with the preferred mining method being an inclined sublevel cave. In February 2008 mining of a decline commenced in conjunction with a feasibility study to further investigate the project. Work from the prefeasibility study indicates that an underground crusher, conveyor and hoisting shaft could be utilised to crush and transport broken ore from the sublevel cave workings to the concentrator. The study suggests that a production rate of five million tonnes per annum could be achieved and sustained for up to ten years. Ventilation designs and requirements will form a large section of the feasibility study. This paper will detail investigations of preliminary ventilation network designs of the proposed sublevel cave. Work has been completed using both Ventsim and VumA ventilation simulation packages. Ventsim was used to provide preliminary estimations and suggest alternatives for: surface fan duties;airflow characteristics (direction, velocity, pressure and quantity); andventilation network design in key mine areas. With mining activities reaching depths in excess of 1000 m below surface an analysis of heat conditions should be conducted. The VumA software package was used to model the thermal properties of the ventilation system. This model will provide a basis for the preliminary decisions on refrigeration requirements for the mine.

Jan 1, 2008

By Troman L, Groutsch J. V

The Kwinana Nickel Refinery began operations in 1970 processing sulphide concentrates from Kambalda using the Sherritt Gordon pressure leach and hydrogen reduction process to produce nickel metal as powder and briquette. Over the years a number of changes have seen the refinery capacity increased from the original design capacity of 15 000 tpa nickel on an all concentrate feed to its current design capacity of 42 000 tpa nickel on an all matte feed. This paper outlines the changes in plant equipment and process for the most recent refinery expansion from 35 000 tpa to 42 000 tpa which have been implemented since 1992.

Jan 1, 1996

By Jankola W. A, Delong O. J

Historically, the silica content of zinc concentrates treated at Cominco's Trail Operations has been low. Silica in the roaster calcine seldom exceeded 1.5 per cent because of the low silica content of concentrate from Cominco's Pine Point mine. With the shutdown of Pine Point, alternate sources of concentrate were required and it was anticipated that calcines containing greater than two per cent silica (with excursions above three per cent) would have to be treated. Previous experience indicated that the existing leaching circuit could not tolerate such high levels. Therefore, a research program was undertaken to identify the key factors affecting silica precipitation; to compare different process alternatives; and to make recommendations for modifications to the existing plant. A project to modify and upgrade the leaching circuit has now been completed. Calcines with higher silica contents are successfully treated, but the upper limit of the circuit is unknown. The results of the research work will be discussed and the new leaching plant will be described. Recent operating results will also be presented.

Jan 1, 1993

By J Dwyer, G Turner, D Pridmore, M Urosevic

Due to their ability to produce high-resolution images of the subsurface to great depths, seismic surveys provide critical inputs to almost all oil and gas exploration projects. However, with some notable exceptions, seismic surveys have rarely been used in mineral exploration. In the past, this was due to both technical and financial reasons. Significant developments on both fronts mean that seismic surveys can now offer substantial benefits to mineral exploration and mining, and surveys conducted for exploration can provide important data sets for mine planning over the life of a mining project.We present case history data that show that seismic surveys can greatly assist with mapping the 3D distribution of lithologies and alteration and, in favourable circumstances, directly detect mineralisation in and around mineral systems. As a result of their high spatial sampling density, seismic surveys are also highly effective at mapping structures that can remain undetected or poorly characterised by drilling alone. These structures may host or provide important vectors to mineralisation. They can also be particularly important when planning shafts, raise bores, declines, stopes and open pit walls. A further benefit of seismic surveys is that they can remotely provide information on geotechnical rock parameters that are used for rippability, slope stability, blasting and ground support.CITATION:Turner, G, Urosevic, M, Pridmore, D and Dwyer, J, 2015. Exploration and mining unified through seismic imaging, in Proceedings Third International Future Mining Conference, pp 117–122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015