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By D Yan, D Connelly

Beneficiation of magnetite is an integral part of the future of iron ore processing. Historically, the focus of Western Australian producers has been on exporting direct shipping ore (DSO) namely haematite. The future for new DSO resources is limited so companies are changing their emphasis into processing the very large, undeveloped magnetite ores in Western Australia (WA), using beneficiation to produce shippable magnetite concentrates. These magnetite resources require higher cost processing techniques such as fine grinding and beneficiation to produce saleable concentrates. This distinct difference, from the DSO ores, has led to the development of a number of new technologies. This paper reviews: the different techniques used for magnetite beneficiation and provides some case studies in the WA industry; the use of mineral liberation analysis (MLA) to describe the nature, grain size, occurrence and associations of the mineralisation;the consideration of coarse cobbing as a critical upgrading; the application of high pressure grinding rolls (HPGR) to save energy; how the field of magnetic separation has resulted in new machines with higher field strength (SLon Separators); ultra fine grinding requirements of magnetite concentrates; andthe application of reverse flotation to reduce silica in the concentrates.

Jan 1, 2009

By B Waldon, M Valastro

A coal dust explosion is one of the most significant risks in the harsh and complex environment of an Underground Coal Mine (UCM). Reviewing literature, regulations and existing systems surrounding explosive dust management shows that there have been few advancements in managing this risk over the past 90 years. Legislation has remained relatively stagnant and minimal systems are implemented in the real world that can simplify, standardise and improve the effectiveness of UCM explosive dust management. To help bridge this gap, Corehesion, in collaboration with an UCM has designed, developed and implement an Explosive Dust Risk Mitigation System (EDRMS) utilising components of Business Intelligence (BI) that is capable of real-world use in industry. To do this the existing explosive dust management process at the associated research mine was evaluated to form high-level and detailed design requirements, focusing on digitally simplifying the procedure, not replicating it. The system was then iteratively and incrementally developed and implemented at the research mine to commence real-world use. The developed BI platform is compared with the existing process to highlight the advancements in performance transparency, efficiency and optimisation of UCM explosion mitigation. This comparison and evaluation of the real-world system implementation at the research mine demonstrate its success in automating procedure steps, providing a readily accessible source of data and enabling a proactive approach to planning and managing explosion risk mitigation. In addition to improvements just for the research mine, this EDRMS created directly address many Queensland regulatory audit findings. By finalising the total system and making the highlighted changes for standardisation, this BI system will have the adaptable capabilities for implementation across the UCM industry. As accurate data availability improves at UCMs, further work can be done to improve the systems’ optimisation techniques and integration of other risks.

Apr 16, 2024

By P Card

Some project managers accept unsatisfactory economic evaluation modelling because they are unaware of what constitutes good practice. They tend to leave it to the evaluation specialist or others to decide. The AusIMM has published on its website a draft set of guidelines for technical economic evaluation which will allow these project managers to take control and demand worldÆs best practices.The style of the guidelines is described and the source of a worked spreadsheet example in Excel is given.Economic evaluation in project management is described. A simple test for the acceptance or rejection of evaluation work is offered. The nature of modelling and evaluation in each of the three study phases of concept, prefeasibility and final feasibility are described. Suggestions on the selection of specialists for each phase are given. The three levels of evaluation thinking are described, namely, modelling, valuation and evaluation. Finally the meaning of æfinancial analysisÆ is explained.The conclusion is that æthe role of an economic evaluation specialist is to create models and evaluations for the whole project team to readily understand and use: it is not to create models for his/her own useÆ.CITATION:Card, P, 2012. What project managers must demand from an economic evaluation!, in Proceedings Project Evaluation 2012 , pp 173-176 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By A T. Spathis, K E. Leslie, K R. Blay

Many open pit mining operations seek to control blasting-related movement of ore and waste to minimise loss and dilution. Tracking the movement of ore boundaries can result in the maximisation of ore recovery and minimisation of waste sent to the mill, thereby optimising the economic performance of the operation.A novel solution for tracking the ore–waste boundary location before and after a blast uses subsurface markers placed along the boundary with all measurements and scans conducted remotely from the blast block. Upon system activation, user-operated equipment on the surface determines the three-dimensional (3D) location of the subsurface markers.The patented system concept combines two electromagnetic mechanisms, magnetic positioning and radio frequency through-rock communications to enable remote battery-powered markers, buried within the rock to be accurately located in 3D space.Field trials at a quarry have demonstrated the system can comfortably handle over 100 subsurface markers with a complete scan, including set-up, taking less than an hour. Location accuracy for each marker in 3D space is better than 0.5 m at a range up to 50 m from the magnetic source, and the system has an overall operational range in excess of 75 m.CITATION:Blay, K R, Spathis, A T and Leslie, K E, 2015. A remote, rapid and accurate three-dimensional ore waste boundary tracking system, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 297–306 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By B Jones, M Chappell

Permanent rock bolts used to support rock tunnels are required to perform for the design life of the structure as a minimum. Quality of installation is critical to the performance over the life of the rock bolt.This paper will present the findings from an in investigation into the integrity of rock bolts installed in an underground hydroelectric power station cavern and access tunnel. The 25?mm diameter rock bolts were installed 50 years ago, tensioned and post cement grouted. Due to a major machine upgrade the whole facility was subject to an asset survey. The owners are responsible for managing the risks associated with the failure of these rock bolts and ensuring the structural integrity of the tunnels and caverns is maintained to continue operations, protect machinery, assure production and more importantly maintain a safe working environment for all employees and visitors.To help manage risk a proactive approach is desired. To this end a test schedule using a non-destructive testing (NDT) system was carried out by Independent Integrity Testing Pty Ltd (i2t). The system used in this application was RokTel™. The system operates by applying a small axial impact to the rock bolt end and measuring the resultant acceleration response. The rock bolt characteristics affect the acceleration response.The data output from the system is analysed principally using Fourier Analysis (FFT) and sinusoidal waves. The energy generated in the bar, the rate of damping and changes in frequency are all assessed. Testing was carried out on 70 rock bolts within the tunnel and cavern. A selection were then over cored, photographed and documented. The data gathered from the testing is then correlated with physical evidence to establish a calibration for the remainder of the rock bolts and assess if this is a viable method for identifying defective elements, and what degree of accuracy can be achieved. The findings will assist with the future assessment of similar hard rock underground?facilities.CITATION:Jones, B and Chappell, M, 2014. The use of non-destructive testing to identify defective rock bolts – a case study, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 275–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

Recent operating experience from West Australian open pit gold mines has shown that geotechnical input into initial design is rare. As a result, ground stability is poor - almost half the pits designed in this way suffer major failure.West Australian experience shows that geotechnical studies for individual mines are site specific, and therefore empirical experience cannot be transported from site to site. Geotechnical studies performed prior to design have resulted in significantly improved pit stability.

Jan 1, 1990

By T Belligoi

Diamond cores and drill chips provide the only direct physical evidence for ore containing rocks. Early characterisation of cores and drill chips is important as it provides critical information for downstream processing. Traditional characterisation techniques include visual logging by a geologist or analytic and spectroscopic methods but they are time consuming and can miss some important textural or geomechanical features.The goal of this work is to evaluate the application of image analysis to iron ore cores and drill chips and to suggest improvements to existing core-scanning and chip monitoring systems. Two samples of massive ore differing by their mineralogy and texture, as well as two different batches of drill chips, have been imaged and analysed. Results are compared in function of the imaging system and the classification algorithms.As a conclusion, despite the necessity for more testing and improvements in calibration and lighting, it is obvious that image analysis technologies can bring a lot of useful information in the perspective of a geometallurgical mapping of the deposit.

Jul 11, 2011

The Sao Chico gold project is located on the Tocantinzinho trend which is the most mineralised zone in the Tapajos Mineral Field of Brazil (see Figure 1). The Tapajos goldfi eld was the site of the biggest gold rush in Brazilian history in the late 1970s and 1980s when approximately 500 000 garimpeiros (artisanal miners) rushed to the area to exploit extensive areas of newly discovered alluvial gold. Approximately 20 - 30 million ounces of gold were produced from these operations before the easily won alluvial gold deposits were largely depleted. The Tapajos region has had little exploration by modern exploration methods compared to any other equivalent gold fields in the world. The gold occurs in sulfide veins developed in shear zones within Proterozoic granites. Gold grades vary from approximately 15 g/t in the hard rock veins, to up to several ounces per tonne in the supergene weathered upper portions of the veins. Goldbearing vein zones in the weathered profile are free digging. In addition, tailings dumps from previous mining operations contain gold grades of approximately 1 g/t. Metallurgical test work conducted to date indicates that gold recoveries of at least 70 per cent can be achieved via gravity concentration. Gold Anomaly, via its 100 per cent owned Brazilian subsidiary, Gold Aura Do Brasil Mineracao Ltda (GOAB), plans to mine the tailings and weathered vein material by open cut methods to generate a quick cash fl ow and to provide a better understanding of the mineralisation as part of a feasibility study for mining the underlying sulfide zone mineralisation (see Figure 2). Mining will utilise locally hired excavators and trucks and ramp up to a rate of 100 tonnes per day. To treat the gold-bearing material, GOAB has purchased an integrated 'state of the art' gravity concentration processing plant from Gekko Systems of Australia. The processing plant includes a scrubber for clay and oversize removal, coarse gold gravity separation via an inline pressure jig and an inline spinner; and fine gold gravity separation via a Falcon Concentrator. The plant is expected to be operational by late 2010. This is an ABSTRACT ONLY. No paper was prepared for this presentation. 

Aug 1, 2010

By B W. Atkinson, J Docherty

An Australian Working Group has been compiling a guide for operators to use in order to improve the efficacy of their routine and non-routine sampling tasks within their coal preparation process. The guide focuses on unit operations within the process, and not conveyor belts or transfer stations that are adequately covered by the existing Standard ISO 13909.Representative sampling of unit operations is generally an after-thought following plant construction, whether that be a result of oversight, or more commonly, capital cost minimisation during initial construction. Minimising capital cost by avoiding adequate sampling systems is generally a poor decision, since the result is a process that cannot be adequately measured, meaning that it cannot be adequately managed and optimised.The use of the term ‘guide’ rather than ‘standard’ is intentional. Practical means of sampling unit operations within existing plants generally relies on a compromise between sample representativity (minimisation of bias) and sampling feasibility. The guide does not endorse poor sampling practice, but instead offers practical guidance to overcome, to the extent reasonably possible, real-life limitations.When it comes to sampling any particular process, it is almost always necessary to make a professional judgement as to whether or not the proposed samples are likely to be sufficiently representative such that the sampling will be worthwhile. Such judgement needs to be exercised by personnel who understand the principles of sampling, as they apply to the stream being sampled. There are many circumstances where available methods for sampling of a particular stream will be meaningless, and in such circumstances analytical data from that sampling will only serve to propagate poor decision-making.This paper outlines the approach for the guide, the areas it covers and the approaches adopted for different types of unit operations and associated equipment configurations.CITATION:Atkinson, B W and Docherty, J, 2017. A practical guide to sampling in coal preparation plants, in Proceedings Eighth World Conference on Sampling and Blending , pp 241–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By C A. Cooper, G A. Suter

The sizing of a starter dam for a Tailings Storage Facility (TSF) involves balancing many competing demands. It should cost as little as possible, be high enough to store tailings until the first raise can be constructed, it must be able to contain water safely, and it must be designed in such a way that the long-term integrity of the higher raises are not compromised, among other things. In addition to these demands there is the complication of the behaviour of the process plant, and the tailings during commissioning. Variations in slurry density, excess water in the TSF, initial settled density of the tailings, reliability issues, and beach slopes above and below water can all impact the way the tailings beaches are developed and ultimately impact the ability of the starter dyke to contain the required volume of tailings and water.The conventional approach to the design of a TSF starter dyke is to begin looking at the elevation required for a set of deterministic design parameters, find ways to reduce the size or volume of it as much as possible to reduce cost, and then possibly look at the sensitivity of some of the input parameters. This paper discusses a stochastic modelling approach for starter dykes that allows a wide range of design inputs to be simulated quickly, with an envelope of possible results produced. The sensitivity to different parameters can also be examined to understand which design inputs have the biggest impact on the required dyke sizing. By integrating the 3D TSF modelling tool Muk3D with GoldSim, it will be demonstrated how a wide range of scenarios can be evaluated and how that information can be used to make better decisions about the selection of design options.CITATION:Cooper, C A and Suter, G A, 2018. Starter dyke optimisation with Muk3D and GoldSim, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 466–475 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By G S. Beros

In 2019 the Chinese Ministry of Ecology and Environment issued guidelines promoting the implementation of ultra-low emissions in the iron and steelmaking industry. These guidelines aim to drive improvements in air quality through the reduction of particulate matter (PM), sulfur dioxide (SO2) and nitrogen oxide (NOx). Secondly, it also represents an initial means to commence decarbonisation of the industry. The ultra-low emissions guidelines propose that well over 80 per cent of China’s production capacity will achieve these targets by 2025. In response, many sintering operations have implemented numerous improvements to the process that result in significant efficiency gains. Of note is the adoption of deep bed sintering where, with some modifications to equipment, the sintering bed depth is increased resulting in sizable reductions of SO2 and NOx emissions. This paper will also provide an overview of the requirements to introduce deep-bed sintering into an operation and highlight test work completed which quantifies the resultant reduction in emissions.

Nov 8, 2021

By Skinner W, Netting A. K O

Surface analysis of ore samples collected from corresponding concentrate and tailings process streams is now a widely used tool in many Australian base metal sulphide concentrators, particularly those involved in AMIRA projects. The use of tec

Jan 1, 1997

By C F. Stokes

The Trident Gold Deposit has been successfully developed by Alacer Gold (formerly Avoca Resources Limited) into a 1.3 Mt/a operation in the space of four years from discovery to first gold pour (2008). The current in situ Resource for Trident is estimated to be 5 900 000 t @ 5.0 g/t for 940 000 ounces at a cut-off of 1 g/t or 2 g/t depending on ore style. Production to date (Alacer and previous owners) is in excess of 500 000 ounces. The deposit lies towards the southern end of the Norseman-Wiluna Greenstone Belt in the Archaean Yilgarn Craton, where it is centred on the historical Higginsville Mining Centre, midway between the world class gold centres of St Ives (+15 Moz) and Norseman (+6.5 Moz). Trident is hosted primarily within a thick, weakly differentiated gabbro with subordinate mafic and ultramafic lithologies and comprises a series of north-northeast trending, shallowly north plunging ore zones. The deposit comprises two main mineralisation styles; large wallrock-hosted ore-zones comprising sigmoidal quartz tensional vein arrays and associated metasomatic wall rock alteration (Eastern Zone, Western Zone and Apollo) hosted exclusively within the gabbro; and thin, lode-style, nuggety laminated quartz veins (Athena and Artemis) that formed primarily at sheared lithological contacts between the various mafic and ultramafic lithologies. The initial interpretation of the Trident Deposit was based on steeply-dipping structures controlling the zones of mineralisation, with much of the targeting and drill-testing aimed at this style of orebody. Subsequent exposure of the orebodies has identified a series of shallow-east dipping mineralised systems (interpreted to be large reverse shears) that at their intersection with the steep-dipping structures cause significant gold enrichment. It is postulated that both orientations are primary fluid pathways with the intersection between the two resulting in zones with significantly high concentrations of gold mineralisation (in excess of 300 000 ounces). This new understanding on ore controls at Trident has identified that the thin lode-style shear-hosted laminated veins are continuous for over 1700 m along strike as they step en echelon down-plunge. In addition, a repetition and periodicity to the intersection between these steep dipping lode-style systems and the shallow-dipping mineralised zones (estimated to be 700 - 900 m down-plunge) has been identified which has considerably increased the down-plunge potential of the Trident Deposit.

Aug 22, 2011

By P Moarefvand, M Osanloo

The anticipated economic life of the mine, which defines the rate of mine production, is dictated initially by the design capacity of the mill/concentrator and the production capacity of the mine relative to the grade and tonnage of ore that can be encompassed by the pit design. A small pit will result in smaller investment and cash flow; in contrast, a larger size of pit will increase capital investment and annual revenue. Since open pit mine design and long-term production sequencing are essentially based on three-dimensional block models, changes in block dimensions leads to different mine sizes, and therefore changes in the mine life. The physical characteristics of the deposit, such as reserve tonnage and ore grade, affect the expected future revenues from the mining project, and consequently they affect the life of the mine. Large blocks will increase the recoverable ore reserves and production rates and hence increase the mine life. This paper discusses the effects of the block dimension on the commercial ore reserve, grade-tonnage curve and its effect on the production rate, ultimate pit size, mining cost and consequently the mine life. The result shows that block height is the most effective parameter governing the economical life of the mine.

Sep 26, 2011

As a result of cheap Maui gas and plentiful hydro-electricity, over the past few decades New Zealand has enjoyed some of the cheapest energy of any OECD country. The situation is changing; at best we are facing some radical changes in energy use, at worst we are facing a crisis resulting from the following:   Cause 1: Maui gas will be exhausted by 2012. Distorted pricing and supply contracts; resulted in Huntly Power Station, a coal mine mouth generator running on 70 per cent Maui gas until very recently!   Cause 2: Investment in new generating capacity (and transmission) is woefully inadequate; as a result hydro lake levels are being continually pushed to the limits.   Cause 3: Distorted thinking is everywhere, for example; æWe will find more cheap gasÆ. æGas is clean û coal is dirtyÆ. Hot air  û ægreen alternatives such as wind generation will save usÆ. æNo NuclearÆ. The outcomes of the distorted thinking will be price increases, then shortages (there is nothing like "black-outs" to focus national thinking) and finally recession.   But what can NZ do? - Mine Coal. Coal jump-started the industrial revolution, it can provide the transition to post-gas and oil. NZ has the second highest reserves of coal per capita in the world, yet we use less that any other country with significant coal reserves. Our exports of our best coal have increased threefold, yet out own consumption has remained static at about 1-1.5 Mtpa for the last 30 years. Our coal is NZ owned and inexpensive relative to other energy sources, even allowing for infrastructure and environmental costs.   What can we do? We as mining professionals can promote informed responsible development and investment in the country's mining and energy business. We can galvanise public opinion on issues such as æunbundlingÆ our entire energy chain from mine-to generator-through transmission, even if the nuclear issue has to wait! With oil above US$70/bbl substitution is feasible. For individuals, there is always solar!

Jan 1, 2006

Problems caused by water discharge from surface mine ventilation shafts can be significant and are usually unforseen. The discharged water is often hyper-saline or acidic and can cause environmental degradation over a wide radius. It can also lead to recurring power pole fires and primary fan breakdowns. A range of solutions to the water discharge problem has been implemented in many Australian mines. In most cases the solutions have been ad hoc, with the overall cost and effectiveness varying tremendously. This paper reviews and contrasts the practicality and effectiveness of the various available remedial options.

Jan 1, 2002

By B Dodd

This paper details how the Australian Securities and Investments Commission (ASIC), as a disclosure and conduct regulator, approaches regulation of continuous disclosure, capital raising and control transactions in the mining and resources sector, and the reasons for the approach. In examining this topic the paper considers the Joint Ore Reserves Committee (JORC) Code (JORC, 2004), the VALMIN Code (VALMIN Committee, 2005), the relevant ASX Listing Rules and the relevant provisions of the Corporations Act 2001 (Corporations Act). This paper discusses ASICÆs approach to expert reports and disclosure with reference to Regulatory Guides 111 Content of expert reports and 170 Prospective financial information.CITATION:Dodd, B, 2012. Issues in capital raisings and disclosure, in Proceedings International Mine Management 2012, pp 3-14 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By E Philippa, B Miller

Material characterisation, ore sequencing and process capability are commonly regarded as the key parameters to consider in designing and operating an effective pit to plant supply chain. Therefore, an understanding of rock mass properties is the starting point for controlling the presentation of problematic material to the ore handling plant and optimising process utilisation. There are different methodologies for characterising problematic material and ore handleability which exist across a spectrum of sophistication. At one end of this spectrum are simple indices built using first principles geology and at the other are complex algorithms developed using advanced analytical methods, machine learning and ore traceability. Regardless of the method, without an integrated process for careful management of problematic ore, material handling delays (ie blocked, bridged, blinded and buried events) will interrupt the stable flow of production. The ability of the ore control geologist to mitigate these delays is central to the ore handleability challenge. This paper describes a quick and easy solution that links the presentation of ore to the operating window at the crusher. This operating window is based on material characterisation, using the physical, textural and mechanical properties of the rock mass, and crusher performance. It also describes how a basic problematic ore index (POI) can be developed using ore tracking to the production face, petrographic studies of ore texture and mineralogy, and existing variables in the geological model. Finally, this paper will demonstrate that by coding the POI into the geological model for mine planning, together with performance monitoring through compliance to plan routines, material handling delays at the crusher can be reduced, unlocking significant resource value.

Mar 22, 2022

By S A. McManus

With the advances in software speed and capability, many of us now are running multiple scenarios on entire models rather than just testing small areas or a few blocks. In the authors experience both the geological and geostatistical academic theory and our rules of thumb, often prove un-useable or incorrect in the real world we work in. The only way to truly validate and tune our models is to complete the entire model and ‘see if it works’. If it lacks some property we were expecting, then we need to find out why and/or run different scenarios to see what changes. This is not always possible with tight project timelines but we find ourselves doing more and more of this sort of thing, and in so doing, understand that every deposit is different and requires its own ‘rules’ to get valid and useful results. For the purposes of this paper, this process is termed Empirical Geostatistics. Take Clayton Deutsch’s ‘all realisations all of the time’ concept a step back. Before you even think of simulating, test the alternate realisations generated by alternate parameters such as different domaining, varying search neighbourhood parameters etc.

Mar 22, 2022

By B Haase, R Saha

Conditional simulation (CS) has been extensively used in metal industry to assess uncertainty of geo metallurgical variables to build robust distributions around grade tonnages across different time horizons. Coal’s entry to nonlinear stochastic modelling is relatively new and this paper summarises the work done at BHP to enable its practical usage from production time frames to Life of Asset planning. CS in coal using Sequential Gaussian Simulation (SGS) is used to understand resource confidence around specific variables within pre-defined boundaries of spatially continuous domains for each coal seam. The variation between simulations for a given parameter reflects uncertainty. This paper demonstrates the use of CS to profile resource based upon agreed seam/parameter uncertainty thresholds which affect planning, forecasting, extraction and inform identification of key production risks and defining mitigation strategies. The end goal is to de-risk long-term plans by optimising infill data collection and improve stability in short-term planning through increased understanding of confidences locally rather than at global resource definition stages. The paper also briefly discusses the use of automated workflows and systems to minimise the time spent on the process to enable use in decision-making.

Mar 22, 2022