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By J Furtney, W Fu, D Nutakor, A Brose

Rock blasting outcomes are often a shared responsibility of both the mine operations group and the mine geotechnical group. From an operational logistics and planning perspective, blasting concerns include optimal fragmentation for subsequent crushing, ensuring the blast is energetic enough to allow easy digging, and understanding the effect of muck from a previous blast on the current blast. From a geotechnical perspective, wall damage and catch bench capacity are the primary concerns. Other concerns for both teams include damage to mine infrastructure by fly rock or blast-induced vibrations, and the stability of open stopes under the pit. This work presents two blast modelling applications (or ‘apps’). The basic app instantly gives fragmentation and wall damage predictions for a given generic blast design. The advanced app loads the current pit contours, reads the blast design from a spreadsheet, and calculates the expected vibration magnitude and peak frequency. The apps have been developed specifically for the Rio Tinto Borates and Lithium Mine in California and are used to support blast design between the operations group and geotechnical group. The basic app instantly gives fragmentation and vibration predictions given a blast design by combining the Kuz-Ram fragmentation model with the scaled distance model for vibrations. The advanced app uses the signature hole method. Blasting outcomes at the mine have improved since using the apps.

Jun 22, 2022

By E Thomas, L McCallum, G Dale, J Bennett, K Reardon-Smith, S Raine

Sustainable closure of coal mines in Australia to a safe, stable, non-polluting condition remains one of the industry’s biggest environmental and social challenges. A significant proportion of mines in the Bowen Basin of Queensland have dispersive spoil. Based on an estimated area of 20,000ha and a rehabilitation cost of AUD$100,000 to AUD$150,000/ha, the instantaneous rehabilitation liability for the Bowen Basin alone is estimated at AUD$2 to $3 billion.Dispersive spoils present problems in post-mining rehabilitated landforms due to increased potential for surface and tunnel erosion, compromising the ability to achieve fundamental mine closure objectives of a safe, stable, non-polluting and self-sustaining post-mining landform (Minserve, 2004). Dispersion results in clay particles being mobilised and transported in water, even at low flow velocities (So et al., 1998; Minserve, 2004), and blocking of soil pores, resulting in surface sealing, crusting and reduced permeability (DNR, 1997; Vacher et al., 2004) which, in turn, further increases runoff (Dang et al., 2018).CITATION:Dale, G, Reardon-Smith, K, Thomas, E, Bennett, J, McCallum, L and Raine, S, 2018. A process-based approach to mine rehabilitation decision making using Bayesian modelling and risk-based principles for dispersive spoil rehabilitation, in Proceedings Life-of-Mine 2018, pp 106–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By A E. Petts

Record iron ore prices and a renaissance of infrastructure in the Pilbara have Flinders Mines poised to move from explorer/developer to an iron ore producer. The potential of the company’s Pilbara Iron Ore Project was first highlighted by the announcement of Rio Tinto’s Caliwingina North deposit to the north and the Fortescue Metals group’s Serenity deposit in the southeast. The success of Flinders Mines’ exploration has been based on incorporating landscape studies into an existing geological framework, and using this to understand the iron-rich materials that were emplaced during the Tertiary. The development of the Delta and Eagle deposit resource models highlights this process. There are three main mineralisation styles at the project; detrital iron, channel iron and bedded iron deposits. They have textural and mineralogical similarities with comparative deposits in the region. Gaining an insight into the geological processes unique to detrital iron deposits and more distal channel iron deposits has been important to understanding the geometallurgy of the mineralisation. The model sits comfortably with other regional oregenesis models and allows a contextual framework to be developed around the timing of deposition of the Fe-rich detritus and pisolitic nodules that dominate the deposits. The exploration model also allows Flinders to explore more effectively for bedded iron mineralisation developed prior to, and since the development of the Tertiary weathering landscape.

Jul 11, 2011

By M Hopkins, A Mutale, A E. Vidal da Silva

The Cliffs Nickel Mine extracts a narrow near vertical nickel vein using a mining method of underhand bench stoping with paste backfill. In 2014, at a depth of 400 m below surface, the Northern block of the mine began to experience squeezing within ore development. At first the deformation was localised, within 30 m of the stoping front, but later became pervasive extending across the Northern block and resulting in a hiatus in mine production. The global mechanism is a progressive pillar failure, where the inter-level pillars in advance of the production front could no longer withstand the induced load and progressively yielded. The local mechanism of failure was observed as crushing of the massive sulphide ore and ‘punching’ of the pillars into the ultramafic hangingwall exhibited as floor and sidewall dilation and unravelling of the mafic footwall. The cause of the global mechanism was attributed to a combination of factors, including: high overall extraction ratio, small vertical pillar heights between ore development, high stress in relation to the low rock mass strength, shallow stope front angle, and insufficient ground support capacity. Following the progressive failure, the remnant rock mass conditions across the northern block were severely degraded, with numerous falls of ground that led to a reassessment of the mine plan. Recovery of the Northern block started in 2016 as a staged process. Development of the safe recovery work methodology involved a number of considerations, such as: production sequencing, development access design, ground support, and development of specific procedural controls. The Northern block was then broken into smaller mining precincts based on tactical factors such as location, ease of access, scale of rock mass damage and nickel content. A specific ground support standard and work methodology are employed, while cycle sheets are used to ensure quality and completeness of work. Large intersections showing signs of deformation have either been bypassed or treated using Rocprops to maintain stability during stope production. This approach has been successful in safely regaining access and restarting production in areas that had previously been removed from the mining reserve.

Mar 15, 2021

By A Hutton, C Dick, D Fletcher

Mine and facility closure planning is a dynamic and rapidly evolving landscape. In this landscape, mining companies and industry consultants are generally good at estimating the associated earthworks and rehabilitation costs, because it is æcore businessÆ. Through our extensive work in mine closure, we have found that the safe and cost-effective demolition of mining related infrastructure is often grossly underestimated. Or alternately, it is simply assumed that the returns on scrap steel and the sale of re-usable plant will cover the related costs. With fluctuating steel prices and no guaranteed buyer for the assets, the estimated monetary return is often unreliable and in many cases unrealistic. On this basis this logic is fundamentally flawed. We have found that on most occasions this has meant that closure cost estimates fall well short of what the actual costs are to close the mine.GSSE and Liberty Industrial have worked on over 60 mine closure projects in Australia and overseas of varying scales and across a range of commodity types. An evaluation of these projects has shown that costs associated with the safe demolition and removal of a mining related infrastructure is in the order of 20 - 30 per cent of the total cost at closure. We believe it is one of the top three risk areas associated with mine closure planning and cost estimation, alongside bulk earthworks and the capping of tailings and waste rock storage facilities.Our paper uses examples from recent projects to demonstrate all aspects outlined above. We have also endeavoured to address the following key points related to the demolition and removal of mining related infrastructure:If companies fail to plan appropriately, complicating factors such as contamination, hazardous materials, mobilisation/demobilisation, geographical location, decommissioning standards, site constraints and weather, can add considerable costs to the project and result in variations for the demolition contractor.Closure planning often assumes infrastructure that is no longer required can be utilised by a third party and/or the new land holder. We intend to show that unless adequate consultation and planning is undertaken, this is not beneficial to the mining company, the environment, or the local community.CITATION:Fletcher, D, Hutton, A and Dick, C, 2012. The æsmoking gunÆ of detailed mine closure cost over-run - A review using case studies of the real costs associated with the demolition and removal of infrastructure in mine closure, in Proceedings Life-of-Mine 2012 , pp 325-332 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

The Graham Farmer Freeway Project in Perth, Western Australia, is the largest urban infrastructure project ever carried out in the State. At a project cost of over $360 million, it also ranks as one of the largest in Australia and is even large by world class standards. The project provides a much needed east-west freeway bypass around the CBD of Perth, linking the Great Eastern Highway in the east with the Kwinana and Mitchell Freeway system in the west. The Bypass will have 6.5 kilometres of freeway, a major bridge over the Swan River, several pedestrian overpasses and underpasses, dual use paths, interchanges and flyover bridges and a rail tunnel. The whole project is being carried out over a four-year time frame, due to be complete and open to traffic in June 2000. The project has been divided into two stages, with Stage 1 including the 1.63 kilometre long Northbridge Tunnel, the subject of this paper.

Jan 1, 1999

By J Champa

The mining industry internationally seems on the verge of a major underground support revolution as suppliers, mines, consultants and researchers develop, test and use thin support (structural) membranes (or superskins as they are commonly called) mainly as a replacement for screen/wire mesh. Thick membrane support in the form of shotcrete (sprayed concrete) has been used since the 1950s in underground mines. Shotcrete, in mines, is generally applied at a thickness between 25 and 100 mm depending on the need. Thin membranes are however applied at a typical thickness between 2 and 6 mm. Certain thin membranes have been available for several years (Tannant et al, 1999), but the intense interest in such supports has only grown in the last few years. The interest lies mainly in the potential to safely reduce the mining cycle time and hence improve productivity. There is however considerable confusion concerning such supports, and this paper attempts to clarify certain aspects and dispel certain misconceptions and myths about thin support membranes.

Jan 1, 2000

By G Balog, T Ormerod, D Sidea

Carrapateena is a copper-gold sub level caving operation located in the Gawler Craton, South Australia. One of Australia’s largest undeveloped copper deposits, the project will be a 4.25 Mtpa underground operation, with an estimated mine life of 20 years (OZ Minerals, 2017). First concentrate production was achieved in December 2019, within the Iron Ore Copper Gold (IOCG) hematite breccia complex. The Carrapateena orebody is overlain by 500 m of barren sediments of the Stuart Shelf, which hosts two aquifers. The cover sequence is dominated by shales, quartzites and sandstones in order of thickness. The cover sequence presented challenges to the mine ventilation system as a result of highly variable rock strengths. On this basis, the site developed the first vent rise, Vent Rise 5 (VR5), earlier than required as a means to test the empirical stability assessment. Assessment for VR5 was completed in 2017, with the mine yet to develop through much of the cover sequence. Due to the geotechnical data available at the time, it was anticipated that break out would occur within the vent rise walls as a function of the low strength Woomera shales. VR5 was developed to 4.5 mᴓ in late 2018. The timing of the VR5 development enabled the site technical team to calibrate empirical stability factors for the assessment of future vent rises. At the time of writing, four additional vent rises have been successfully developed to a diameter of 5.5 m. No significant overbreak has been observed within any of the vent rises. This paper is intended for geotechnical practitioners designing large-diameter vent rises in geological environments similar to the Stuart Shelf where a similar approach to vent rise design may be warranted.

Mar 15, 2021

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 Lee G, Stitt P

The term "industrial minerals" covers a vary wide field. However in Australia this field tends to be characterised by the follow- ing: (1) Relatively low unit values. (2) Product specifications can be exacting compared to the metalliferous field. (3) Product specifications often have to be tailored to the needs of the end user. (4) Beneficiation plants tend to involve low capital outlays relative to the metalliferous field. However they often have to produce products'to a range of specifications. (5) Technology often influences what can be considered as reserves. (6) Because of low unit values industrial minerals tend to be relatively cost sensitive. This is particularly the case in regard to transport. (7) Location of deposits near to major urban areas (markets) dictates a greater pressure on ecological aspects. (8) In Australia there has been a tendency to vertical integration largely due to the restricted market available. Reserves assessment is shown to be critically dependent upon the above Factors.

Jan 1, 1979

By G McKay, M Erskine, S Macklin

The City of Sydney is currently investing in a number of infrastructure projects that require tunnel excavations within the Triassic Hawkesbury Sandstone. It is generally accepted that this formation has high residual stresses of ‘tectonic’ origin, so much so that these stresses have been implicated in a number of well-known failures and problems for tunnelling. These include failure of ‘roof beams’ comprising discrete beds in the crown of tunnel excavations; stress-induced spalling and ‘slabbing’ of tunnel walls; shear displacement between beds causing the failure of rock bolts; strain in adjacent infrastructure and, the necessity for re-grouting of high conductivity fractures due to stress relief dilation after excavation. Whilst there is an extensive published database of in situ stress measurements comprising ‘hydrofrac’, ‘over-coring’ and ‘slotter’ stress measurements, these data indicate a considerable spread of results. The traditional approach to interpreting this data has been to attempt to fit linear correlations to stress versus depth data, based on personal experience and ‘back-analysis’ of monitoring data during construction. However, there are a number of such correlations in the literature and there is divergence of opinion regarding the assessment of ‘background’ in situ stress and appropriate upper and lower bound values for design. This paper provides a brief review of the published data; suggestions on an alternative ‘risk-based approach’ to assigning in situ stresses for design; and, proposals on how in situ stress tests may be conducted in future to improve the quality of the database available to designers.CITATION:Macklin, S, McKay, G and Erskine, M, 2014. A review of the in situ stress database for tunnel design in the Hawkesbury Sandstone, Sydney, New South Wales, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 171–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By J Vann

Geometallurgy is inherently multidisciplinary and it gains its power to deliver improved outcomes for the minerals industry by bridging silos between disciplines. This cross-disciplinary approach unlocks value, identifies (and avoids) value destruction and provides a pathway to better implementation of an energy efficient and sustainable minerals industry. Despite this promise, we argue that the cross disciplinary approach also represents the greatest threat to the success of geometallurgy. Some key cross disciplinary issues identified are:Geometallurgy has so far evolved in the technical sphere, mainly by collaborations of geologists and metallurgists. Consequently, in many cases the business dimensions and value have not been incorporated. Financial and risk evaluation viewpoints need to be assimilated into the geometallurgical paradigm. In fact, until such measures are integrated into practices, the value cannot be fully demonstrated.The historical and current efforts on geometallurgy have been highly focused on improved sampling and measurement of geometallurgical properties or appropriate proxies. This work has been driven by professional and academic geologists and metallurgical engineers. It is notable that mining engineers (who are critical in the value delivery of geometallurgy through changed planning approaches) have so far been at the margins, or absent. The construction of valid three dimensional (3D) geometallurgical models raises some important organisational, mathematical and geostatistical considerations. The enhancement of resource models to account for geometallurgical aspects must be managed carefully if the full value of geometallurgical thinking is to be realised.The use of 3D geometallurgical models to change business decision making and practices is the real nub of the problem. We believe sophisticated scenario based evaluation methods are required if the potential impacts of spatial rock properties on processes further down the mining value chain are to be realistically evaluated. Such changed practices require ‘whole of value chain thinking’ to embed this change into the business in an ongoing way.Because profitable geometallurgy demands changed approaches to business decision-making and also organisation of the firm (radically changed in some cases), the senior executive viewpoint must be incorporated into the language and thinking of geometallurgy. This is unavoidable if the establishment of a geometallurgical approach to project evaluation, development and operation is to be successful and sustained.A powerful analogy for the problem faced by geometallurgy is the transformation of safety culture in the mining industry in the past 20 years. We argue that, as in the safety revolution, explicit models, cultural change and management of the ‘soft’ dimensions of the problem are pivotal to success of geometallurgy. In light of this, we propose a model (‘the Geomet Curve’) that gives a framework and pathway for geometallurgy in seven steps. The implications of this model for technical and organisational steps required at different stages are discussed.

Sep 5, 2011

By F P. van der Meer, E Lessing, E Matthies

High pressure grinding rolls (HPGR) technology is growing to be a common comminution tool in iron ore processing. The technology finds a wide acceptance and presents specific benefits in coarse ore grinding and closed-circuit grinding in preparation of ball mill feed, right down to the other end of the particle size spectrum for iron ore pellet feed preparation.A growing number of minerals processing plants are facing higher operating costs and difficulties due to a scarcity of process water, which in some cases is a result of more stringent environmental constraints. In addition, many new iron ore deposits are located in more arid regions of the world. These challenges have led to operators taking a new look at dry processing of iron ores.The use of dry crushing and classification technology in cement production from blast furnace slag, clinker material or limestone feed stocks indicates that the technology may be applied in minerals processing. In addition, dry processing provides the possibility of generating a final product from finely disseminated and inter-grown ores at sizes near or well below 100 µm, as may be required for beneficiation techniques such as in fine magnetic separation, flotation or magnetic flocculation.Dry grinding by HPGR has a number of specific features, challenges and opportunities, including balancing power input, moisture content requirements and classification efficiency in the process design. HPGR parameters and the latest HPGR design and sizing capabilities indicate considerable potential benefits from this dry processing technology.This paper highlights some of the specific issues that play a role in dry HPGR application, with respect to energy and materials balances. Examples of dry HPGR practices and process studies in iron ore mineral processing are discussed.CITATION:van der Meer, F P, Lessing, E and Matthies, E, 2015. Iron ore final grinding by high pressure grinding rolls and air classification, in Proceedings Iron Ore 2015, pp 197–204 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By S Marshall, A Fowler

The Augusta underground mine at Costerfield in Central Victoria has been in operation since mid 2006; however, AGD Operations Pty Ltd have explored and undertaken open pit operations in the area for over 20 years. The high-grade, narrow gold-antimony orebody is being mined using both mechanised and hand-held methods, to produce up to 70 000 tonnes per annum at ten grams per tonne gold and six per cent stibnite. AGD Operations Pty Ltd processes the ore on site using gravity and flotation to produce two products; a concentrate which is sold to Chinese smelters and a gravity concentrate which is refined off-site. The circuit achieves up to 30 per cent recovery of gold from gravity methods. There are many challenges in the underground mine, including an orebody with an average width of 300 mm, very poor rock mass conditions in the host rock and variable dips in the ore along strike, between 45¦ and 90¦. The upper levels of the mine have been developed ready for stoping; however, their depths range from 20 m to 70 m below surface in both oxide and transitional material. A major fault structure consisting of mud has been encountered underground and is associated with the orebody causing very poor ground conditions, water inflow and requiring additional reinforcement. The northern limit of the mine is defined by the proximity of historical workings in the South Costerfield mine, which is being continuously dewatered.

Jan 1, 2008

By M Wieloch, D Wimpenny, M Chappell

Fibre-reinforced geopolymer concrete (FRGC) contains no Portland cement or steel reinforcement, but instead uses synthetic fibre reinforcement and a geopolymer binder. The use of geopolymer binder in lieu of Portland cement reduces the concrete’s embedded energy (CO2 emissions) whilst the use of synthetic fibres eliminates the issue of reinforcement corrosion, thus enhancing the overall long-term durability of concrete. This paper presents the development of FRGC during a three-year project funded by the Victorian Science Agenda and a consortium of five organisations. The work involved laboratory and field trials and the production of prototype tunnel segments that have been subject to durability and fire testing.FRGC has exceeded the performance of the Portland cement-based control mix in terms of flexural strength, chloride diffusion, water sorptivity and drying shrinkage. Furthermore, the FRGC segments subjected to a simulated hydrocarbon fire test did not exhibit explosive spalling; however, the creep of FRGC was approximately three times that of the steel fibre-reinforced Portland cement-based control mix. The compressive strength and tensile splitting strength of the FRGC were also lower than the control mix. These differences need to be allowed for in the design using FRGC.Prototype bolted tunnel segments of up to 0.8?t mass have been produced from FRGC using standard production techniques and ambient curing. These were successfully produced within a 24-hour production cycle. Cut sections through the segments showed good compaction and even distribution of fibres. The estimated carbon footprint of tunnel segments produced using FRGC is approximately 70 per cent less than that of Portland cement-based segments containing 25 per cent fly ash and steel reinforcement.The results to date indicate that FRGC has the potential to produce a new generation of tunnel segments and, in general, precast concrete products with increased durability and substantially reduced carbon emissions compared to the Portland cement-based concrete with steel reinforcement.A summary of further research carried out by CH2M HILL into a complete elimination of ferrous inserts from segmental concrete tunnel lining is also summarised in this paper. The use of non-ferrous connectors for radial joints in combination with the FRGC technology in the manufacture of tunnel segments will effectively lead to development of a new generation of segmental tunnel lining systems.CITATION:Wimpenny, D, Chappell, M and Wieloch, M, 2014. Fibre-reinforced geopolymer concrete – an innovative material for tunnel segments, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 345–352 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By T D. Jolly, L A. Balzan, A R. Harris, Z Bauk

"The availability of real-time data in any process control system is critical for effective management of that system. At MMG LXML Sepon Copper Operation in Lao PDR, controlling the copper grade of the feed to the leaching circuit is paramount for maximising both productivity and copper recovery. Since 2008, real-time analysis data has been available to the process engineers from the Geoscan on-belt analyser installed on the Copper Mill feed conveyor, and highly accurate results on copper grade have allowed the process engineers to strictly control blending to overcome the variability in plant feed grade. The availability of real-time analysis data is crucial, as effective sampling of this stream is both difficult and error-prone, being only a snapshot in time of highly variable ore stockpiles, as well as having significant laboratory turnaround delays. Periodic sampling is used to verify the Geoscan data as accurate. Since its installation, the copper result has been the most critical output of the Geoscan. In recent times, the process engineers have sought to utilise other results from the Geoscan to further improve and control the process. One measurement of particular interest involves the real-time measurement of calcium and magnesium as a gauge of ore feed gangue acid consumption. To satisfy this end, accurate measurement of calcium and magnesium is becoming increasingly more important and has been the subject of ongoing collaboration between Sepon and Scantech, the manufacturer of the Geoscan. This paper discusses this work, describing the calibration process and results obtained, while also providing a basis for Geoscan use in operations to enable enhanced process control for all potential Geoscan users.Citation:Balzan, L A, Jolly, T D, Harris, A R and Bauk, Z, 2016. Greater Use of Geoscan On-belt Analysis for Process Control at Sepon Copper Operation, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 231–238 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By I Elias, E Moya, S Chaffer

This paper is based on a case study from a mine site that operates two gyratory primary crushers. These crushers were encountering problems, which included inconsistent P80, reduced liner life tonnage and, on some occasions, catastrophic failure of the liners.As part of an evaluation process, both crushers were ‘mapped’ using a technology for condition monitoring and modelling of the crusher’s wear components. The technology provides comprehensive coverage of the crusher’s concaves and mantle at 100 mm intervals. It also automatically assesses wear rate between inspections and determines the highest wear areas. Outcomes include projected optimum reline dates at target replacement thicknesses, the identification of asymmetrical wear patterns, and the accurate measurement of open and closed (OSS/CSS) side settings.A comprehensive study was performed to optimise the performance of both these crushers at site. Over a period of seven liner service lives, the strategies to improved performance included liner analysis (concaves and mantle profile analysis), tonnes per day (t/d) and tonnes per hour (t/h) analysis, mantle reutilisation, detection and control of loose concaves, and detection and control of uneven wear and hot spots.These strategies resulted in the improved mechanical and operational performance of both crushers through concave and mantle redesign, OSS/CSS control, accurate wear forecasting plus other initiatives.As a result of these initiatives, the site now experiences benefits which include consistent product size, increased tonnes per hour (t/h) for both crushers and the liner life tonnage has doubled. Additionally, further benefits include less downtime for crusher liner maintenance and the reduced cost of inventories by mantle reutilisation.CITATION:Elias, I, Chaffer, S and Moya, E, 2015. Improvements in service life and cost reduction for gyratory primary crushers through mantle and concaves optimisation – a case study, in Proceedings Iron Ore 2015, pp 115–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By B Murphy, N Strong, J Albrecht

Rio Tinto’s Argyle Diamond Mine has a history of underperformance with delivery of ore from the underground operation to the surface for processing with no real clarity in sources of loss and value. In order to increase underground production performance, the basic concepts of the Theory of Constraints model were applied to the Argyle underground production system. This prompted a revised view on bottlenecks and contributors to value loss and ultimately leading to record breaking mine performance. System loss reporting to demonstrate the best opportunity to drive value, departmental detail to develop tools to identify improvement opportunities and clarity across the team to ensure alignment and clear lines of communication were critical to the project success.

Mar 15, 2021

By G Hall

BHP BillitonÆs (BHPB) Yandi ore deposit is a channel iron deposit (CID) in the Pilbara district of WA. The ore is predominantly a goethite-hematite pisolite and overlays a clay at the base of the deposit. Knowledge of the location of the contact prior to mining is critical to maximise ore extraction and minimise contamination from and mining of the underlying clays which contain high levels of alumina. The contact between the iron ore and the clay is highly irregular. Traditionally the contact has been delineated by closely spaced drilling û this can be expensive and since each drill hole only provides a point sample measurement, irregularities in the contact surface can be missed. In September 2001, three high resolution geophysical techniques were trialled to see if they could be used to improve the efficiency and accuracy of ore delineation. The three techniques were resistivity imaging, ground penetrating radar and electromagnetic conductivity imaging. The resistivity data showed a favourable correlation with the available ground truth data from drilling. Using this ground truth data as a calibration, an interpretation of the depth to the base of the channel iron deposit (CID) ore was constructed for the areas surveyed. A significant attribute of the method is that the position of the base of the ore is imaged continuously along the lines that are surveyed rather than at discrete points. No continuous well defined ground penetrating radar (GPR) reflections were observed from the base of the CID ore. There did appear to be some correlation between the range of echo times that reflections were observed and the drill data, however the precision to which the range of echo times could be estimated was of the order of several metres and therefore not adequate to replace current procedures. The electromagnetic data showed good correlations with the existence of shallow clays but did not discriminate between variations in CID ore depth. This technique is therefore not suitable for mapping the base of the CID ore but may still be useful as a rapid tool for mapping the position of clay bands.

Jan 1, 2002

By Jin C, Shuyi L, Yuanbiao Z

This paper describes the structure, performance, principle and effectiveness of a new laboratory type of composed-forces field separator utilising the composition of the magnetic force, vibrating force, pulsating force, gravity and fluid-viscous force etc to separate fine feebly magnetic valuable minerals. Compared with the pulsating high gradient magnetic separator, this separator possesses unique advantages of higher enrichment ratio and higher recovery of the magnetic component.

Jan 1, 1993