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By D Johns, L Murray

This paper discusses pore pressures in the embankments of tailings dams by comparing real world data with common design assumptions. Assessment of pore pressures has implications on material behaviour interpretation from CPT investigations and, therefore, on the design. For example, the assumption of hydrostatic pressure is conservative for limit equilibrium stability analyses but may be un-conservative in assessing the potential for contractive behaviour and strength loss during shearing. This paper presents some real world data, the investigation methods to determine the pore pressures, and subsequent interpretation of CPT data and material parameters such as the state parameter. It also examines the design implications of assuming a hydrostatic pressure distribution, by comparing results from that assumption with those obtained using the real pore pressures.CITATION:Johns, D and Murray, L, 2018. Characterisation of pore pressure in tailings dams and the implications for design, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 239–249 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

IT is most remarkable and valuable property of mediurn and high carbon steels that they should be so susceptible to heat treatment, the wide range of variability in tenacity, ductility, etc, due to the normal influence of the carbon in the untreated material being enormously inereased thereby.The physical properties of steel and other metals are much more closely related to their structure than to their ultimate analysis.For instance, we may by chemical analysis determine the carbon content of a steel to be 0.5% ; but this information alone is insufficient to enable us to say what are the physical properties of the metal.Such a steel may possess 11 tensile strength of anything from 35 tons per sq. in., with much ductility, up to 80 tons per sq. in., with practically no ductility, according to its heat treatment. A microscopie examination, on the other hand, would show the structural composition of the steel, from which its physical properties could be approximately deduced. From this it will readily be understood that the microscope has played an important part in the development of modern rnetallurgy, and to-day it is in daily use for the examination of metals and alloys in the laboratories of most works dealing with the rnanufaeture and working of metals.THE IRON-IRON CARBIDE EQUILIBRIUMTo understand fully the mode of occurrcnce of the different constituents of a knowledge of the Iron-Iron Carbide equilibrium diagram (Fig. I) is essential to heat-treat steel successfully and to interpret microstructures correctly such a knowledge isabsolutely indispensable.A portion of the Iron-Iron Carbide Diagram, dealing with steels below 1000 and containing up to 1 carbon is given below.It should be noted that the diagram deals entirely with pure carbon steels, and does not indicate the influence of the usual so-ealled "impurities" present in all commereial carbon steels...

Jan 1, 1926

The Olympic Dam copper/uranium deposit was discovered in 1975 and subsequently commenced production in 1988 at a rate of 1.5 Mtpa using the sublevel open stoping mining method. In the following five years the operation underwent two optimisation programs that have increased mine output to the current rate of 3.4 Mtpa of ore. The pre-expansion requirements were annual development of approximately 10 000 m and the placement of around 500 000 m 3 /yr of cemented backfill. Previous to 1995 all hoisting was carried out by the Whenan shaft. The Robinson shaft was commissioned during that year to hoist increasing development mullock tonnages and to allow for increased ore hoist via the Whenan system. In 1996 WMC committed to expanding the output of the operation from 85 000 tpa (1996/97 budget) copper metal to 200 000tpa. The corresponding increase in mine ore production requires expansion to a nominal rate of 9.0 Mtpa. To achieve these increased tonnages, major hardware installations will include sinking of a third shaft capable of hoisting in excess of 9.5 Mtpa, a rail haulage horizon utilising automatic trains, expansion of the existing backfill plant to a production capacity of over 1.8 million m 3 /yr, increasing long term development rates to 15 000 m/yr and increasing the production drilling and blasting rates in line with the higher stope production output. This paper provides detail into the intended hardware (shafts, equipment, etc) of the mining system, and outlines the intended long-term operation and management of the operation. Of particular note is the background requirement of ensuring existing production targets are met to provide critical cashflows into the project during the period of expansion.

Jan 1, 1998

By B Y. Luan, Y Tian, W Zhou, X Lu, Q X. Cai

The unmanned driving technology in open pit coalmines is an important technology that relies on innovation to drive the development of the open pit coal mining industry in China’s transformation of growth drivers and industrial structure upgrading. It is an important path to solve the shortage of mine truck drivers in the future mining, an important way to improve the working environment of open pit mining personnel, and an important foundation for achieving flexible production capacity in open pit mining to cooperate with the coordinated development of new energy. The communication rules at intersections are key to ensuring the safety and efficiency of unmanned driving in open pit coalmines. This paper proposes a collaborative traffic strategy between unmanned trucks for the single bucket unmanned truck intermittent process system in open pit coalmines. Based on the gap theory, this paper analyses the conflict characteristics and establishes a coordinated traffic strategy for the common intersection and merging conflicts of unmanned truck trucks in open pit coalmines, A multi-agent system simulation platform was built to evaluate the coordinated traffic efficiency under different initial average gap sizes of vehicles, with intersection traffic density, vehicle speed, and gap changes as key indicators. The results show that under the simulation conditions of this article, when the initial average gap of vehicles reaches three (four) times or more of the safe distance, the coordinated traffic performance of intersection conflicts (merging conflicts) is better, and the traffic capacity of intersections is close to the traffic capacity without conflicts.

Sep 1, 2024

By R R. Anand

Recent research by CRC LEME from an Australian mineral exploration perspective, has focussed on regolith architecture and mechanisms of geochemical anomaly formation, within transported regolith. Methods have been developed for the rapid production of regolith-landform maps which is the starting point for understanding regolith architecture in the third dimension. Methods for development of 3D regolith models are less well advanced, and require integration of all available geological and geophysical datasets, but still with a heavy reliance on drill-hole information. The base of the transported regolith û the unconformity û remains the most important regolith boundary for geochemical sampling in transported regolith terrains. A new generation portable spectral logger, employing a broader spectrum can interpret important features from drill chips within the regolith. This allows internal architecture, redox fronts and the all-important interface to be objectively identified. Transported lateritic components can provide vectors to mineralisation in depositional regimes. Palaeomagnetic and new radiometric methods which date individual phases of the regolith provide evidence of different episodes, each characterised by different geochemical dispersion patterns in transported regolith. Along with lateritic residuum, calcrete is prime sampling medium. Calcrete is probably enriched in gold through physical and biological processes, rather than straight chemical processes. In South Australia, the lowermost calcrete layer buried within the depositional regime, especially where it lies directly over the silcrete layer at the buried interface, is the desired sampling medium. Certain gum trees, with deep roots in transported regolith have been shown to record anomalous values of gold and basemetals in leaves, twigs and bark. Anomalous metals in acid-sulfate soil seeps can also provide a window through sedimentary cover in respect of mineralisation in the basement. A number of Yilgarn occurrences of gold anomalies in transported cover, strongly infer hydromorphic and biological mobilisation of gold. This inference is supported by micro-analyses of regolith mineral hosts in hardpans and mottled sediments, which show gold and pathfinder elements prefer to reside in goethite and specific types of clay minerals. This creates anomalies in specific mineral phases. However the inference that that these are sites of mobile or labile metal ions remains enigmatic. Similarly there is inconclusive evidence that selective extractions will provide an anomaly not otherwise detected by conventional total dissolution methods. Hydrogeochemistry is a promising exploration tool for basemetal exploration. The importance of microbes in both the dissolution and precipitation of gold in the Australian regolith is demonstrated. We are on the verge of identifying the functional gene sequence of individual active microbes. A consideration of possible mechanisms for creating anomalies in soils above transported regolith, presents difficulties in facilitating upward movement of ions from the watertable to the surface. Perhaps the best avenues of research lies with surrogate soil gases, and biotic transfers.

Jan 1, 2004

By Baafi EY, Chatterjee PK

The quality of mine planning decisions ultimately depends on reliable estimates of the characteristics of the orebody. The quant- ifiable factors such as grades or thickness can be estimated from field data gathered from outcrops or exploratory drillholes. Since outcrop data is necessarily limited to the periphery of a deposit, extensive drilling generally is required. This paper outlines a method for selecting the number and location of additional exploratory boreholes using an iterative procedure based on a mathematical optimization concept called fixed point theory. The method is illustrated through its application to an exploratory drilling program for a coal mine where optimized locations gave a lower estimate of regional and block variances than a manual Choice.

Jan 1, 1986

By Mortimer RR

The Weipa bauxite mining operation on the west coast of Cape York currently mines lb million tonnes of crude ore per year from the Andoom and Weipa mines. Andoom ore is trucked up to 4 km to a rail load station and hauled 20 km by train to the Beneficiation Plant. Weipa ore is trucked up to 7 km to the Beneficiation Plant. Increasing haul lengths and production requirements have led to a progression of larger two axle rear dump trucks and currently he intrcducticn of 145-tonne, three axle L t Dm dump trucks. bith the introduction of the Andoom a operation in 1972, the decision was made to use a railway system to haul crude ore from Andoom to Weipa. This system has proved to be successful from both an economical and operational view point. Due to the successful combination of a truck and rail haulage operation in Andoom, future :evelopment of orebodies requiring increased haul distances and increased production tonnages will probably result in extension r>f the railway system to compliment the trucking operation from the mine face.

Jan 1, 1978

By J Loeb, R Ramanathan, H Ingham, P Cameron

Most mining operations, including iron ore, maintain a focus on continuous improvement and asset optimisation in their operations. As all the unit operations in the Mine-to-Mill value chain are interdependent, available technologies that address efficiencies across the value chain are once again in the spotlight as companies are driven to improve productivity and maximise mine site profits to increase return on capital invested. Core to continuous improvement is the need to understand the baseline and impact of changes to the process. In this paper, we discuss some of the critical attributes in the Mine-to-Mill process, including their influence on productivity and cost, the need for direct measurement and areas where they should be applied. Many initiatives can be considered to improve Mine-to-Mill processes. Mining operations are planned and executed based on designs and models to achieve the operation's objectives. However, there are many variables in the different parts of the value chain, such as blasting, material handling, crushing and screening. Therefore, measurement of the key attributes establishes the baseline for Mine-to-Mill (or Pit to Plant) performance, which is necessary to understand the impact of any proposed improvements to the process design and execution and monitor the outcomes on an ongoing basis sustain the improvements that have been implemented. This paper focuses on two types of measurement – blast movement and particle size of materials through the Mine-to-Mill process. Several innovative technologies and control loops are readily available to measure these attributes and assist operations to improve productivity and mine site profits. The size of the tangible benefits, which can flow from measuring and optimising fragmentation and blast movement, provide a remarkable return on the investment. Realising these benefits needs a focus outside conventional operation silos as a successful Mine-to-Mill project requires a multidiscipline approach across all the silos in the value chain. Required technologies are available; adding the necessary ingredients of communication and co-operation by all concerned across the silos will ensure the benefits are realised.

Nov 8, 2021

By P Wilson

The Mt. Wright Underground Mine is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. The establishment of the world’s first Sub Level Shrinkage (SLS) mine from a tradition Sub Level Open Stoping operation has proven to be a geotechnical challenge which has required tailored solutions to overcome unique issues. This paper will be broken into two distinct sections that will outline: a brief overview of the mining method and how the SLS method was chosen; and how the SLS is managed and key geotechnical learnings. The story of the world’s first SLS originated from the need of a bulk mining method to ensure the viability of Mt. Wright into the future. Traditional bulk mining methods such as; Block or Sublevel Caving were originally ruled out due to the low natural ‘cavability’ of the orebody and the proximity of the orebody to existing major infrastructure (Decline, Ventilation Rises and Egresses). The first section of the paper will outline the key geotechnical information that helped decide the SLS method in addition to how continuous backfill influenced the design. The second section is intended to address issues that the geotechnical engineers encountered since the inception of the SLS. The feature topic of this section is mining induced stress. Like most bulk mining methods, Mt. Wright had success when the production front was running parallel to the stress (production front being ‘shadowed’ from the stress). This was until a design change, forced by a splitting ore body resulted in this shadowing effect becoming harder to achieve. As a result, rehabilitation and production hole re-drilling become a regular occurrence, which teamed with a strict set of access controls made the production cycle longer and harder to complete. CITATION:Wilson, P, 2018. Mt Wright – geotechnical learnings from a sub level shrink, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 119–132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By A Fitzpatrick

An integrated and dynamic water balance and water quality model for a proposed base metal mine has been created using the GoldSimÖ software package. The model was initially developed to address the water quality of the Tailings Management Facility pond and how pond discharge would potentially affect downstream water quality. However, due to changing project objectives, the modelling has expanded over time through an iterative process to encompass the full mine site and all receiving environment water quality. The model results have been used as part of the mine planning/design process but are also intended to be used for the environmental impact assessment and permitting process. The model has been built to allow for changes to input terms to be readily made as additional data becomes available. The model results serve as a prediction of water quality and the potential project impacts to the receiving environment water quality. This paper presents the process by which data from a wide variety of sources was used to construct the model and how the model results were used to guide development of a conceptual water management plan. In addition, the role of the model in establishing proposed discharge criteria will be highlighted. The model has been delivered as a fully functional application with the intent that the end-user can be other than the modeller, the development of this aspect shall also be covered. CITATION:Fitzpatrick, A, 2012. Predictive site-wide water quality modelling as a tool for mine planning and permitting - A recent Canadian example, in Proceedings Life-of-Mine 2012 , pp 71-78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By H Lemos, E Nunes, D Jacobson, R Costa, L Ono, A Alves, H Delboni Jr

Oversize rock breaking and metal tramp removal are key issues for reducing primary crusher downtime, as well as improving the safety associated with its operation. Remote operation of such tasks would thus not only increase productivity, but also reduce the risks related to work in confined spaces, fall risks, and overhead hazards. These issues are particularly relevant in high-capacity operations such as iron ore mining, where large machines are in continuous operation. This article describes the architecture, construction and advanced testing of a novel remotely operated robotic mechanism for assessment and removal of metal tramp from primary crusher chambers. The system essentially includes a robotic-arm equipped with a hydraulic clamp tool for handling oversize material, as well as an oxy-flame module for cutting metal pieces entrapped within the primary crusher cavity. The first industrial unit was delivered to a large iron ore mine in Brazil, where the installation and testing is scheduled within the coming months.

Nov 8, 2021

By Jensen B

The investigation of the explosion characteristics of nine Bowen Basin (Central Queensland) dust samples in a suitable coal dust explosion chamber using a new dust concentration probe provides several advances in the area of coal dust explosibility testing. The 20 litre explosion chamber, of novel design, uses rotation of the main body of the chamber together with air jets for dust dispersion, and allows testing of different types of explosion initiators and analysis of the explosion characteristics of coal dust/methane mixtures of varying concentrations.A new development was a dielectric dust probe for the measurement of coal dust concentration. A capacitive micrometry technique was successfully adapted to measure dust concentration. The system uses a ratio-transformer bridge for measurement of small changes in a capacitive probe designed to sample a representative volume. The device is accurate, and is capable of operating in the hostile environment within the explosion chamber.The explosion chamber and dust probe characterise the explosive potential of coal dust samples by determination of the dust lean limit concentration in varying mixture with methane. Plots of lean limit points obtained in this way present an explosion curve for each sample which indicates the potential of the coal dust/methane to explode under the conditions of initiation in the chamber. The explosion curve obtained for each sample presents a unique signature that appears to reflect the physical and chemical characteristics of the dust.The results from this series of laboratory experiments appear to provide a useful index and indicate potential areas of interest for future research.

Jan 1, 1991

By J Robinson, L D’Uva

"The Gold Fields group and Gekko Systems have successfully worked together on multiple projects, including at the St Ives, Agnew and Granny Smith operations in Western Australia, and the Damang operations in Ghana, with gravity recovery design, technology installation and optimisation the key driver on each occasion.In 2014, Gold Fields Australia identified an opportunity to challenge the historical thinking at Granny Smith and reassessed the benefit of upfront gravity gold recovery. The historical approach had been to employ gravity on the tailings stream of the carbon-in-pulp (CIP) circuit, recovering sulfide minerals into a concentrate from spiral concentrators for further liberation of gold via a regrind circuit.Gekko was engaged to assess the implementation of a gravity circuit within the grinding area, and to perform a comprehensive gravity recoverable gold test program. Test data was fed into the AMIRA P420 BCC Gravity Model to confirm the gravity recovery potential of the ore, and for process design basis generation. Height, space and capital limitations proved to be a design challenge. However, collaborative learnings throughout the project ensured the design and operation of a reliable and economic gravity gold circuit. Ultimately, the Granny Smith gravity circuit was a success, satisfying all the project objectives and yielding consistent, measurable benefits. On average, the gravity circuit recovers 33 per cent of total gold, resulting in an increase to overall gold recovery by 0.7 per cent.This paper highlights the key project drivers for Gold Fields, and the development of the Granny Smith free gold gravity circuit. It details application of test work and modelling, and the challenges and learnings encountered during the design, installation and commissioning stages. This paper seeks to demonstrate that continuous improvement in a long standing operation can be beneficial to overall circuit flexibility and increased ounce production.Citation:D'Uva, L, Robinson, J and Bell, T, 2016. Defying Gravity - Brownfield Continuous Improvement, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 135–144 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By P Thompson, D Rose, S Yu, W Baum, R Zahn, D Meadows, G Hall

Opportunities to improve mill operations are often cited by mining companies and recognised in many concentrators spread throughout the world but are not always followed through. Copper-molybdenum concentrator operations are challenged by a continuously increasing list of detrimental factors. They include deteriorating ore characteristics and poor mineralogical information on deeper ores, water quality and availability, steel wear and increasing power costs. Rapidly declining productivity, sustainability and environmental factors, new taxes, mining industry global skill set shortages, to name but a few, must also be considered. The days of maximising value by just increasing production or simple cost cutting are fading and will not be sufficient for the future of more complex mineral processing operations and larger plants. As a result, FLSmidth’s Global Process Technology Group has launched a plant and process optimisation program based on mineralogical and metallurgical surveys.Copper-molybdenum concentrators of the future need a paradigm shift. Modelling and simulation tools alone are not the answer to complex mineralogical associations and larger scale equipment and operations. Detailed area by area review aimed at identifying process constraints in terms of equipment and operating practice in conjunction with robust diagnostic work, ie mineralogical and metallurgical characterisation, are mandatory for process optimisation. The navigational beacon, for all operations who want to remain competitive, will be ‘process efficiency’. Since the use of automated mineral analysers has become more readily available and reliable, mineralogical-metallurgical plant surveys have proven themselves as the most efficient tool for optimising plant performance.The following paper will illustrate how operations can move toward eliminating under-performing flow sheets, fixing run-away flotation conditions, maximising individual process equipment performance, preventing shortcuts in Bond work index testing which may cause the failure of comminution models and minimising costly and time-consuming ‘debottlenecking’. As previous plant surveys have shown, the net project cash flow can be increased by 50 to 200 per cent if a combination of robust ore characterisation and plant process mineralogy is performed. The combined plant survey approach has been demonstrated successfully in a multitude of operations. This includes the use of key ore types in concert with statistically sampled process streams, bench-scale metallurgical tests and automated mineral analysis on a size-by-size basis.CITATION:Meadows, D, Hall, G, Rose, D, Thompson, P, Baum, W, Zahn, R and Yu, S, 2014. Copper-molybdenum concentrator surveys using mineralogy and process benchmarking tools to improve overall plant performance, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 315–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By A Rantala, J Timperi and J Kaartinen, T Maksimainen, O Haavisto

"X-ray fluorescence (XRF) is the most common technique used for online slurry assaying in base metal flotation applications. Typically, assays from feed, concentrate and tailings slurries are used to monitor and control the flotation circuit, with possible additional sampling locations in other main slurry flows inside the circuit. The elemental content detection from the XRF spectrum is relatively straightforward as the spectrum contains element-specific peaks whose height corresponds to the element concentration in the sample. However, centralised XRF analysers measure the elemental concentrations line-by-line, which may increase the sampling interval for an individual line and cause unnecessary response delays, especially in large flotation plants. Reflectance spectroscopy is an emerging technique that can be used to obtain more frequent measurements from slurries. The measurement is based on the mineral-specific absorbance of light in the visible and near-infrared (VNIR) wavelength range. Due to this relatively inexpensive and simple measurement system, it is possible to conduct the measurement simultaneously in several slurry lines. However, the information contained in the VNIR spectra is more difficult to interpret as concentrations of all the minerals in the sample contribute to the measured spectrum and changes in solids content, particle size and mineralogy disturb the elemental content estimation. Therefore, frequent calibration of the measurement is required. This study presents the application of combined reflectance spectrum and XRF measurements for rapid online slurry assaying in a copper-nickel flotation plant. The XRF assays are utilised as calibration samples for the reflectance spectrum measurement, keeping the calibration model up-to-date. The rapid reflectance spectrum analysis is then used to provide an almost continuous estimate of the slurry contents, enabling further improved process monitoring and control.Citation:Haavisto, O, Maksimainen, T, Rantala, A, Timperi, J and Kaartinen, J, 2016. Reflectance Spectroscopy with X-ray Fluorescence for Rapid Online Assaying in a Copper-nickel Flotation Plant, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 85–92 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By J Joy, A Bye, G V. Kizil

This paper presents an application of the newly developed risk-cost-benefit (RCB) framework to support risk management decisions for the selection of wall monitoring technologies at an open cut mine site. The RCB framework quantitatively assessed the risk of unstable slope-induced wall failure and its impact on both loss of life and coal recovery. The RCB framework was utilised in the selection of an optimum group of risk-controls to effectively manage the risk of wall failure to ensure safety and optimal production occurred. The RCB framework incorporates mathematical modules that integrated RCB calculations and risk-control effectiveness assessments to determine the risk reduction and financial impact of the examined safety initiatives.This paper provides an overview of the five-staged RCB framework, incorporating the RCB decision support tools, RCBGEN (Risk-Cost-Benefit Generator) and RCEMETHOD (Risk-Control Effectiveness Method), and demonstrates its application to slope stability risk management at the case study site. The RCB charts are designed to display a balance between risk, cost and benefit for easy interpretation by decision makers to support the objective selection of an optimum suite of risk-controls. The RCB analysis revealed that a combination of ævisual inspections, automatic extensometers and radarÆ for fast- and slow-wall failures with structure were sufficient to reduce the probability of loss of life (PLoL) to the æModerateÆ zone as defined by the Australian Geomechanics Society (AGS, 2007) for the case study site. The new framework presented in this paper provides a method to effectively determine the suitability of risk-controls and supports industry efforts to reduce risk to as low as reasonably practicable (ALARP).CITATION:Kizil, G V, Bye, A and Joy, J, 2012. Risk-cost-benefit analysis of early warning technologies impact for wall failure risk management in surface mines, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 55-64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

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 J Seery, N Savage, A Wilson, L Nicholas

Geological modelling provides a means of spatially representing the three dimensional distribution of geological information to downstream stakeholders. The geologist completing the modelling work intimately understands the varying degrees of confidence, assumptions and extrapolation required to honour the data. Geological models are often taken and used by stakeholders without fully understanding this modelling process. This can lead to confusion amongst stakeholders when the geological model shows variable reconciliation. A method for visually communicating the confidence of the spatial distribution of geological models has been created by the Rio Tinto Iron Ore structural geology group for use primarily in geotechnical engineering investigations. A numeric confidence rating is assigned to each geological data point used in the creation of a geological surface. This is based on data type, collection method and reliability to indicate potential error in distance from its modelled location. In regions of sparse data, confidence ratings are inserted based upon the geologistÆs experience and knowledge of the geology, whereas mapped geological contacts or drill hole intersections are assigned a higher confidence rating. A regular grid of points is registered to the geological surface and each of these grid points is assigned a confidence rating using an inverse distance weighting using a nearest neighbour approach. The resulting grid is colour coded according to the confidence rating to provide a visual representation of the variable confidence of the geological surface in three dimensions. Subjectivity and bias from the geologist is minimised by critically analysing the input geological data and then applying this methodology to represent the confidence in the spatial characteristics of geological models. Understanding of this confidence enables mining professionals to make informed decisions and identify areas that require further geological investigative work. CITATION:Savage, N, Nicholas, L, Wilson, A and Seery, J, 2013. Visual communication of geological confidence - a move toward a less subjective approach, in Proceedings Iron Ore 2013 , pp 169-174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By B J. Beven, A Harris, L Balzan

Fortescue Metals Group flagship operation, Cloudbreak, is located in the Pilbara region of Western Australia. The mine is capable of delivering an annualised production rate of 40 Mt/a. Positioned 50 km to the east of Cloudbreak is Fortescue’s Christmas Creek operation, which has a combined processing capacity in excess of 50 Mt/a. Following on from these successes, Fortescue advanced development of its western Pilbara mines at the 60 Mt/a Solomon Hub. These processing installations place Fortescue in a strong position to deliver on a guidance of between 155–160 Mt/a for financial year 2014/2015.As Fortescue enters a phase of asset consolidation and debt repayment over expansion, the business is commanding stronger performance through enhanced plant operating practices and mine site cost reduction initiatives. To this end, the strategic placement of instrumentation is an area being given greater consideration. Access to real-time information pertaining to conveyed materials is of major interest to operators for making timely process control decisions. Fortescue has recognised the importance of accurate and up-to-date process information about their ores and hence, has adopted the use of Scantech’s Geoscan mineral analysers at two of their mines.There are two Geoscans at Cloudbreak; one on the ROM feed conveyor and another on the final product conveyor. These allow the in-feed material grade characteristics to be assessed. Moreover, the final product stream can be monitored to ensure product quality is maintained within acceptable quality tolerances. A third Geoscan is installed at Christmas Creek mine on a conveyor that transfers final products to Stockyards.This paper discusses the use of the Geoscans in these installations, including benefits to Fortescue’s operations, as well as functional considerations such as the impact of maintenance and calibration. A discussion of recent advances by Scantech is provided including enhancements to the calibration process and minimising plant downtime, along with a summary of results obtained.CITATION:Balzan, L, Beven, B J and Harris, A, 2015. Geoscan online analyser use for process control at Fortescue Metals Group sites in Western Australia, in Proceedings Iron Ore 2015, pp 99–106 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By R H. Knight

Production mine geology must be accurate and efficient in order to reduce risk and ensure that ore value and mining operation revenue are maximised. Present grade control practices are commonly based on outmoded and inaccurate 2D geological mapping techniques where spatial relationships are estimated by eye, sketched by hand and projected to arbitrary reference planes. The 3D mapping approach outlined in this paper integrates 3D photogrammetric imagery with implicit modelling techniques to enable more accurate grade control and reconciliation in underground mines. High-resolution stereo photographs are taken of daily ore development headings. Ore contacts are traced directly on a 2D face photo using a stylus and rugged tablet. Area-weighted face grades are estimated and calculated on mapped 2D face planes. In the office, a 3D photorealistic mesh is processed and georeferenced. 2D face mapping data is transformed into its actual 3D location and true 3D mine mapping is performed by digitising oriented 3D polylines representing ore contacts and other geological features directly onto the image surface. Three-dimensional spatial relationships are fixed, eliminating the projection error of traditional 2D methods. Ore envelope and waste solids are modelled within the closed, drift-round mesh. Volume-weighted ore envelope and round grades, as well as round volume and tonnage, are calculated. Ore/waste classifications, grade, tonnage and per cent dilution are quantified per round, visually assessed in 3D and reconciled with short- and long-term models on a daily basis. Updated geological continuity models provide geological guidance in development headings under geological control and accurate 3D structural and form-line mapping improves definition drilling and stope planning. Three-dimensional imagery provides a permanent detailed survey and geological record of mine workings that can be revisited virtually to reinterpret geological ore controls in light of new observations and insights. In addition images can be used to monitor daily production performance, create training scenarios for miners, engineers and geologists and prepare management presentations. This approach adds value to underground mines by improving the accuracy and efficiency of mine geology practices. The method is particularly effective in mines with visually distinct and geometrically complex orebodies, such as those in the Balmat zinc mine located in New York State, USA, which are used to illustrate the method.CITATION:Knight, R H, 2017. 3D mine mapping – improving grade control and reconciliation in underground mines using photogrammetric imagery and implicit modelling techniques, in Proceedings Tenth International Mining Geology Conference 2017, pp 203–212 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017