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By A Batnasan

The main techniques for removing phosphorus as an impurity element in iron ores are physical separation (eg magnetic separation, flotation) and chemical separation (acid leaching, alkaline leaching and bioleaching) processes. When phosphorus occurs in iron ores as phosphate minerals (eg apatite), physical separation techniques are available to remove the gangue minerals from iron ores. On the other hand, chemical separation techniques are suitable for reducing phosphorus levels when phosphorus is associated with iron oxides and hydroxide minerals (eg hematite and goethite) in iron ores. In this study, the dephosphorisation behaviour of high‐phosphorus iron ore was investigated using a combined alkaline roasting and water washing route. Roasting experiments were conducted in a laboratory electric muffle furnace using various concentrations of sodium hydroxide (0–50 g/kg-ore) at different temperatures (100–800°C), varying prolonged roasting times (0–2 h), and different particle size fractions (-45 – -250 μm) of iron ore. Subsequent water washing experiments were employed at various pulp densities (30–1000 g/L) and different times (30 s – 60 min) at ambient temperature. Hematite and goethite were the main minerals in the high-phosphorus iron ore identified using X-ray diffraction (XRD) analysis. The iron ore assaying 63.40 mass % Fe (total), 0.240 mass % P, 4.53 mass % SiO2, and 4.87 mass % Al2O3 were determined using X-ray fluorescence (XRF) analysis. The results showed that the dephosphorisation rate of the iron ore was reached 40 per cent under roasting with 50 g/kg-ore NaOH at 300°C for 2 hours followed by water washing for 30 s with a pulp density of 300 g/L, reducing phosphorus level from 0.240 mass % to 0.142 mass %. At the same time, the iron grade was reduced from 63.4 per cent to 59.5 per cent, caused by an iron loss. Results suggest that the phase transformation of goethite induces the dephosphorisation of high-phosphorus iron ore under alkaline roasting conditions

Aug 22, 2022

By G S. Beros, K M. Edwards

Over the past 20 years drum scrubbers have become a widely adopted technology within iron ore beneficiation plants. Generally, the drum scrubbers in use are considered high-capacity machines capable of accepting larger-sized feed material. Together with a water addition to a desired pulp density and a mild energy input, these large rotating machines effect an attritioning action that removes water soluble clays and other deleterious materials. Within the Western Australian iron ore industry, drum scrubbers have been successfully applied to Channel Iron, Marra Mamba, Bedded and Detrital orebodies. The introduction of drum scrubbers has enabled Western Australian producers to satisfy the substantial increase in demand for iron ore from Chinese steelmakers by making the lower-grade sections of the above orebodies economic. However, despite being a relatively simple unit process, the requirements for successful design and operation of these machines are not fully understood. This paper draws on the collective experience of both authors to provide some points to consider for incorporating drum scrubbers into iron ore beneficiation plant flow sheets.

Sep 18, 2023

By K Guilfoyle

AngloGold Ashanti Australia Ltd operates an underground mine below a large open pit at the Sunrise Dam Gold Mine near Laverton in Western Australia. Operations are based on an extensive mineralised zone which has very complex geometry, has a high ‘nugget effect’, and is difficult to interpret and model. Initial underground ore was produced from relatively narrow orebodies dipping from 15º - 70º. Open stopes aimed to selectively extract high-grade ore, using methods including jumbo stripping and longhole drilling and blasting. The complex geology makes it difficult to accurately locate development and stopes in the positions required for profitable production. In narrow stopes, rock mass damage and overbreak dilute ore grades and increase the cost per ounce of gold poured. In flat orebodies, several different techniques have been used to recover blasted ore but overall productivity is low. Thus selective mining can also be slow, costly and recovers only a portion of the available mineral resources. Large longhole open stopes with cemented paste backfill are used to extract multiple zones of mineralisation from the Cosmo and GQ orebodies. Bulk emulsion explosives and electronic detonators are used in all large stope blasts to reduce the risk of misfires and to accurately control blasthole initiation sequences and delay timing. Larger stopes improve productivity and significantly reduce direct mining costs, enabling the use of lower economic cut-off grades which increase the overall recovery of mineral resources. This paper reviews the evolution of open stoping at Sunrise Dam, the various mining methods and drilling and blasting practices used, the results achieved, and the lessons learned.

Nov 8, 2011

By J P. Burr

The Waterview Connection will complete a strategic Auckland motorway route linking the south, west and north. The project will include 2.1 km of ‘undrained’ driven tunnels, 500 m of drained cut-and-cover tunnel and tunnel portals.The project is aligned beneath a stream valley of Oakley Creek, which is incised through alluvium and in places overlain by landfill, between Mt Albert volcano and a ridge formed in alternating sandstones and siltstones. The resulting topography, geology and hydrogeology of the tunnel alignment are complex.The Assessment of Effects required estimation of the likely settlements resulting from the tunnel construction and assessment of their effects on the buildings, services and other features. A conservative approach was taken when estimating settlements in order to provide an upper bound estimate of the consequent effects. There are three sources of these settlements: mechanical settlement from the tunnel excavation, mechanical settlement from the displacement of retaining walls and consolidation settlement from the groundwater drawdowns during construction and, in some cases, in the long-term.The settlements from these sources were calculated independently and then combined to identify the most critical effects. These combined settlements were used to assess the potential damage to the buildings, services and other features above and around the tunnels. The combined settlement results generally followed the anticipated trough shape centred on the underlying tunnel but with some noticeable effects relating to the underlying geology and hydrogeology.The effects on buildings were typically assessed as negligible with some areas of very slight to moderate damage predicted. Effects on services are anticipated to be minor but some large and older pipes will require specific monitoring during construction. A monitoring programme is proposed to allow the actual settlement and effects to be compared to those estimated with appropriate responses should those effects significantly differ.This paper describes the methods used to calculate and combine the settlements and assess their effects.

Mar 8, 2011

By R Bourcier, T Rafferty

Following an underground coal mine explosion, it is important that ventilation is quickly restored to ventilate the mine and affect a mine rescue. To achieve this, surface ventilation fans must be suitably protected from explosion damage, but still able to be quickly restored.A review of all Australian coal mine regulations was carried out, revealing that Australia has no prescriptive regulations that specify the design of explosion relief panels and the protection of ventilation fans in the event of an underground explosion.To better define the level of protection required, this paper reviews and extracts details from relevant major international regulations and standards on the subject.A suitable design methodology for the protection of ventilation fans is presented that could be applied in Australia, using a combination of explosion relief panels, appropriate isolation of the fan, and ventilation shaft/mine design.CITATION:Rafferty, T and Bourcier, R, 2013. The protection of surface ventilation fan installations from underground explosions, in Proceedings The Australian Mine Ventilation Conference , pp 169-173 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By J L. Macdonald, G S. King

"The development of a predictive geometallurgical model is a multidisciplinary and iterative task that involves both discovery and integration aspects. In this paper, the authors discuss the concepts of geometallurgical modelling in terms of the underlying relationships that are used to connect geology, metallurgy and economic value, and how the early-stage preparation of a spatial geometallurgical model enhances project value and provides a sound basis for future studies and test work programs.Hot Chili’s (copper-gold-molybdenum) Productora Project, which is located in northern Chile, is a porphyry-copper style deposit that can be exploited using open pit mining and preparation of a saleable concentrate from fresh ore, as well as heap leaching, solvent extraction and electrowinning (SX-EW) extraction of copper from oxide ores. To enhance project value in the Productora prefeasibility study (PFS), Hot Chili developed a geometallurgical model that was used to predict the process responses of both sulfide and oxide ores. The Productora model incorporates test results from mineralogical, metallurgical and comminution testing, as well as other studies completed on a suite of samples collected from the many geological domains of the deposit.Using Bond Work Index and Abrasion Index proxies in the geometallurgical model, Hot Chili estimated the variability of sulfide ore throughput and comminution costs. Heap leach acid consumption in oxide ore was estimated from drill hole calcium concentrations. The model was then used in mine scheduling to identify high and low throughput or high and low acid ore zones so that the processing of these zones could be advanced or deferred to improve net present value (NPV). Additionally, the cost benefits of preparing an early-stage geometallurgy model were quantified through a comparison to a conventional model that was based on test work averages.CITATION:King, G S and Macdonald, J L, 2016. The Business Case for Early-stage Implementation of Geometallurgy– an Example from the Productora Cu-Mo-Au Deposit, Chile, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 125–134 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By T Nassis, P Louw, M R. Fry, T du Toit

Business intelligence (BI) and business analytics (BA) are established IT technologies that are used extensively in the business environment. This paper discusses the use of these technologies in production environments and beneficiation plants.Assmang’s Khumani mine is an iron ore operation located in the Northern Cape, South Africa. Assmang Limited is jointly owned by African Rainbow Minerals Limited and Assore Limited. This paper presents a case study of a BI solution applied to this plant, which is used by metallurgists, supervisors and all levels of operations and management to extract and analyse data to control and optimise the operation of the plant.The main advantage of adopting an established BI solution is the ease with which production personnel can extract and analyse data. The data is easily presented in familiar spreadsheets and no IT staff or specific training is required to achieve this.The solution adopted at Khumani mine uses a data mart with a multidimensional model (called an online analytical processing (OLAP) cube) acting as the main repository and source of data. The OLAP cube simplifies the access and analysis of plant data.The OLAP cube stores data in a specifically-designed way, which allows extraction and analysis to be performed quickly. It is designed to hold large amounts of data on a long-term basis, which could be for the life of the plant. It also performs automatic aggregations over many dimensions on a background process.A major benefit in adopting such a BI solution is that it allows common BA methods to be applied. This is due to both the efficient long-term storage of data and the availability of standard BA tools. BA tools are now able to perform data mining, predictive analytics, forecasting and other machine-learning algorithms. This paper presents the possible use of such advanced data analysis methods in a beneficiation plant.CITATION:Fry, M R, Nassis, T, Louw, P and du Toit, T, 2015. The use of common business intelligence and analytics tools in the operation and optimisation of iron ore process plants, in Proceedings Iron Ore 2015, pp 129–138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By D A. Williams, J C. J Boshoff

The properties of tailings that emanate from laterite nickel processing plants are significantly different to most other mine tailings. They typically comprise a mixture of fine materials that are made up of altered clays, chemical residues and salts. Neutralisation processes that are undertaken prior to tailings discharge result in a high proportion of gypsum in the tailings. The salinity of the pore fluid is commonly higher than 140 g/L of salts, dominated by magnesium sulfate. Hydraulically-placed tailings that undergo solar evaporation typically reach dry densities of less than 1 t/m3 of insoluble solids. In situ water contents after many months of drying may be as high as 80 per cent, and peak undrained shear strengths are unlikely to be greater than 20 kPa.This type of material is not conducive to upstream raising, from both a practicality and overall slope stability perspective. Even at rates of rise of less than 1 m/a, it is difficult to effect upstream raising on unaltered laterite nickel tailings. However, the authors have successfully designed and implemented upstream-raised laterite nickel tailings storage facilities. The upstream raises have been formed from both imported natural materials and air-dried and compacted tailings borrowed from the tailings beaches.Drying and associated strength gain has been achieved through various means of mechanical intervention, repeatedly exposing a zone of tailings to the atmosphere for evaporation. Field trials have been undertaken to optimise the approach, and the findings from the trials have been implemented in practice to allow stable upstream raises to be constructed. The cost savings and reduced environmental impact compared to high-volume downstream raises have been significant.CITATION:Williams, D A and Boshoff, J C J, 2015. Upstream raising of laterite nickel tailings storage facilities, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 271–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By O C. Aitken

Mining project developers are committed to taking on all the challenges and obligations of financial risk management. It is interesting that our current models of project finance have not changed markedly in principle for some 700 years, yet the rules which prepare the way for effective project assessment and subsequent loan management still do not seem to be well understood by project or corporate developers. Probability and gravity fill the opposing trays of the golden balance of financial risk. Understanding the relationship between these opposing, but intimately related elements is critically important for successful risk management. It is important to move beyond the qualitative approach and use quantitative methodologies to measure the financial impact of the occurrence of each major risk. We live in a world where the only constant is change and thus it is not surprising that a bankerÆs life is still governed by assessing, measuring and pricing risk. Banks are attracted to funding well managed companies with strong cash flow projects. But we are more risk averse compared with the credit appetites of late last century. This attitudinal shift has resulted in tougher term sheets for the early 21st century, encompassing more conditions, warranties, undertakings and stronger cash sweep provisions. Banks require well balanced portfolios to achieve an acceptable spread of risk, thus there is a more restricted market for small company lending than that available to large multi-project corporate entities with less concentrated risk profiles. Because of this focus, junior company debt finance remains comparatively expensive and especially so for more challenging geographical and political environments.

Jan 1, 2004

By D Brereton, C J. Moran

Intensive resource extraction, in the form of multiple mining operations, presents significant assessment and management challenges for resource developers, governments, community and the environment. Cumulative impacts, ie the successive, incremental and combined impacts (both positive and negative) of an activity on society, the economy and the environment, can place significant pressure on social, economic and environmental capital and render conventional mine-by-mine approaches to management ineffective. Cumulative impacts can be what are most important to environments, communities and economies surrounded by multiple mining operations because cumulative impacts are what they experience. There is much to gain from increased consideration of cumulative impacts. Unmitigated impacts have the potential to delay or even prevent expansion of mining in existing and prospective areas. On the other hand proactive management of cumulative impacts can benefit regional environments and communities and contribute to the industryÆs social license to operate. Resources are often not the limiting factor to better cumulative impact management. More effective coordination of existing resources may go a long way toward mitigation and enhancement, and better planning and assessment may help avoid impacts and exploit opportunities for efficiency gains through reduced duplication. In this paper we draw from working examples to present five practical assessment and management strategies applicable to resource companies to enhance positive, and avoid and mitigate negative, cumulative impacts. The strategies are presented based on their capacity for achieving outcomes, ease of implementation and cost effectiveness and are drawn from a multi-year study on the assessment and management of cumulative impacts in the Hunter Valley, New South Wales and a follow-up study to improve cumulative impact assessment and management practice in the Australian coal mining industry, both reported elsewhere.  

Jan 1, 2009

By O Bascur, A Soudek

Large metallurgical complexes are substantial users of energy, water and assets. To improve the effectiveness of energy and assets the quality of the data and events become paramount for real-time operational management. A lack of resources at the local operations and at the enterprise makes it impossible to process the sea of information and many projects have failed. As such, a novel approach for implementation of continuous improvements at the local level and innovations at the strategic level was implemented at all operating plants at Anglo American Platinum. Sixteen concentrators, three smelters and two refinery process systems were integrated to scale the information for manufacturing services at the local and enterprise level. The new capability of an enterprise real-time monitoring and diagnosis software infrastructure was available to implement many business strategies in tandem. Mineral and metallurgical processing knowledge is used to simplify the implementation of the data model. As such, asset monitoring, energy, production and process control management were implemented in an integrated approach reusing the same data but with different context and time horizons to have a standard methodology for local root cause analysis. This paper will highlight a sustainability management approach to change and empower the local and strategic team to collaborate using a new approach for adaptive reporting and condition-based event management and notifications. The results based on the integrated and collaborative team efforts will be presented. OSIsoft Plant Information system was installed and configured to achieve a targeted reduction in energy consumption of 15 per cent by 2015.CITATION:Bascur, O and Soudek, A, 2014. Implementation strategies for energy effectiveness and sustainability – example of Anglo American Platinum, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 101–108 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By J Jones, J Blunt

"The requirement for environmental approvals and associated environmental impact assessments (EIAs) is now commonly regarded as a key milestone and body of work during project development. EIAs can be undertaken at various phases during project development, generally either:\ during the scoping or prefeasibility studies, where limited project information is available and the mitigation and management measures of the EIA become a set of criteria and commitments that control project design during the feasibility study, as an iterative approach whereby mitigation and management measures are developed through an integrated process with the engineering team, and measures are included in the feasibility study cost model following the feasibility study, where detailed project design information is available, the cost model is complete, and the EIA is an assessment of a fixed project with limited opportunities for mitigation and management measures to be integrated into engineering design. This paper investigates the advantages of integrating EIA into life-of-mine planning during the feasibility study phase, using the Tampakan Copper-Gold Project (the Project) as a case study. The Tampakan Project is located in the Philippines on the southern island of Mindanao. The Project involves the proposed development of three main areas of infrastructure:a large-scale, open pit copper-gold mine and associated mine site infrastructure (including tailings and mine waste storages, fresh water dam, concentrator, etc) a power station, port and filter plant (PPFP), located approximately 60 km from the mine a pipeline and transmission line linking the mine and PPFP sites.Examples of engineering measures developed through an iterative process to mitigate and manage predicted environmental and social impacts include design of water management infrastructure, modification of the disturbance footprint (eg roads realigned to avoid critical habitat) and realignment of project infrastructure to minimise impacted water catchments.CITATION:Blunt, J and Jones, J, 2012. Integrating environmental impact assessment into life-of-mine planning, in Proceedings Life-of-Mine 2012 , pp 143-152 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 10, 2012

By D Teyhan, J Kirsch

Traditionally, most Australian iron ore mining operations have been surface-based. Processing plants were designed to handle dry ores. In recent years mining operations in the Pilbara have progressively moved below the water table exposing wet, sticky ores which have caused lost efficiency in screening operations as particles tend to agglomerate and adhere, blinding screening media. Miners and vibrating screen manufacturers have experimented with a shift from linear motion to elliptical motion screens. Elliptical motion conveys and lifts particles. Effective on flat deck (horizontal and inclined) or sloping decks it can be configured to provide a controlled transport rate, applying pressure in all directions to maximise screening efficiency. In practice, elliptical motion screens have proven to be effective in dislodging sticky particles from screening media, reducing blinding rates and improving screen efficiency. Moisture and clay content change during the life of a mine. These changes are sometimes the effect of seasonal rainfall, in other cases due to increased groundwater and clay content as mining operations go deeper. To compensate for such changes and optimise screen efficiency, changing the ‘shape’ of elliptical screen motion is required. This has traditionally required shutting down processing plants and making mechanical screen adjustments. Plant downtime is costly and machine adjustment has been a ‘trial and error’ practice. This paper will explore the results of a field trial that is currently underway in Brazil of a next generation elliptical motion screen design that allows operators to make changes to exciter rotational direction, speed and screen stroke angle, through electronic drive phase control. The machine’s electronic drive system synchronisation is enhanced for stability with a unique mechanical timing system. Operating at up to 6 g, screen adjustments can be made on the fly without stopping production. Early trial results are showing up to 50 per cent improvement in screen efficiency compared with traditional elliptical motion machines under certain feed conditions.

Aug 24, 2022

Waihi Gold Mining Company Limited, a wholly owned subsidiary of Normandy Mining Limited, operates the Martha gold mine, located in the township of Waihi, New Zealand. The operation, an unincorporated joint venture, comprises Normandy Mining Limited (67.070/0) and Otter Gold Mines (32.94%). Since gold was first discovered at Waihi in 1878, it has formed a key part of the region's economy. In 1909 the Waihi mine was described in a report to Parliament as æthe most important gold mine in Australasia and one of the greatest in the world.Æ That was a record year for production, with 416,813 tons of ore mined and some 1,120 men employed. Today the mine produces up to 1,250,000 tonnes of ore annually, and the project employs some 234 men and women. In 1999 the value of the gold and silver produced ($59 million) made up 47% of Waihi's estimated GDP. Waihi Gold has made significant contributions to the Waihi economy, community and the Hauraki region as a whole. Since the mine was re-opened in 1987, thousands of local people have benefited from the mine. In 1999, consents were granted allowing an extension to the mine life (the Extended Project) and this will result in a further seven years of economic benefits resulting from mining activity. The Company has undertaken extensive consultation throughout project planning, construction, operations and rehabilitation. Ongoing liaison and involvement with all community sectors, including Tangata Whenua and Iwi, local residents, recreational groups and schools remains an integral part of the operation. Throughout the life of the modern Martha Mine, the Company has actively supported the local community in the form of donations, sponsorships, the provision of amenities, and by participating in community events. A well established environmental team exists at the site. Environmental and community performance is measured by an independent five-assessment process, and the Company is committed to achieving excellence through ongoing improvement programmes and staff awareness. When the mine is closed, the open pit area will be transformed into a recreational lake, and the tailings storage facilities will be rehabilitated to become a combination of wetlands, grassed areas and ponds. Resources will be provided by the Mine to ensure the rehabilitated site remains in a safe and self-sustaining, stable condition in perpetuity. The mine is regarded as a showcase on a world standard of how a modem mining operation can successfully coexist with the nearby community.

Jan 1, 2000

By D Teyhan, J Kirsch

Traditionally, most Australian iron ore mining operations have been surface-based. Processing plants were designed to handle dry ores. In recent years mining operations in the Pilbara have progressively moved below the water table exposing wet, sticky ores which have caused lost efficiency in screening operations as particles tend to agglomerate and adhere, blinding screening media. Miners and vibrating screen manufacturers have experimented with a shift from linear motion to elliptical motion screens. Elliptical motion conveys and lifts particles. Effective on flat deck (horizontal and inclined) or sloping decks it can be configured to provide a controlled transport rate, applying pressure in all directions to maximise screening efficiency. In practice, elliptical motion screens have proven to be effective in dislodging sticky particles from screening media, reducing blinding rates and improving screen efficiency. Moisture and clay content change during the life of a mine. These changes are sometimes the effect of seasonal rainfall, in other cases due to increased groundwater and clay content as mining operations go deeper. To compensate for such changes and optimise screen efficiency, changing the ‘shape’ of elliptical screen motion is required. This has traditionally required shutting down processing plants and making mechanical screen adjustments. Plant downtime is costly and machine adjustment has been a ‘trial and error’ practice. This paper will explore the results of a field trial that is currently underway in Brazil of a next generation elliptical motion screen design that allows operators to make changes to exciter rotational direction, speed and screen stroke angle, through electronic drive phase control. The machine’s electronic drive system synchronisation is enhanced for stability with a unique mechanical timing system. Operating at up to 6 g, screen adjustments can be made on the fly without stopping production. Early trial results are showing up to 50 per cent improvement in screen efficiency compared with traditional elliptical motion machines under certain feed conditions.

Nov 8, 2021

By M J. Nugus

The structural models developed by exploration and mining geologists are most commonly concerned with the ‘main structures’ or key constituents that pertain to the associated mineralisation. To this end, it is recognised that the geological and exploration models, which are developed, are essentially ‘fit for task’ and the scale-related variances are not always realised at an early stage. In fact, in many cases anomalous intercepts along different trends and of variable apparent continuity have often been neglected as ‘back scatter’ and not important. Recognition of the importance of subordinate structures as mineralising hosts suggests that additional opportunities exist outside the primary and main structures. History shows that opportunities are often not realised where gold is hosted in orientations not parallel to the predominant trend of the schistosity, main fault or shear zone.Another reason for the importance of subordinate structures can be understood from their roles in a percolation network. Subordinate structures can access the large fluid fluxes provided by backbone elements, but, as dangling elements, they provide greater opportunities for gold precipitation mechanisms and hence may constitute essential parts of the resource. Therefore, the role, understanding and consideration of the smaller-scale and orthogonal structures should be considered during all facets of exploration, resource development, delineation and mining.

Aug 22, 2011

By R Goddard

An alternative stoping method has been adopted for narrow vein stoping at the Tasmania Mine in Northern Tasmania. Colloquially described as ‘Radial-in-Reef’ (RiR) stoping, the method employs the drilling of radial rings in the plane of the Reef from a drill stub located at the geographic centre of the proposed stope panel.Production from the Western Zone of the Tasmania Reef has been undertaken remotely from the Reef since 2007, after a detailed geotechnical engineering analysis indicated that the integrity of the sill drives could not guarantee an acceptable level of confidence should an anticipated seismic event occur within a radius of 10 m. The key tenet of the remote mining approach was the exclusion of personnel from sill drives once stoping had commenced. The remote mining method had to be ‘retrofitted’ to four existing stoping blocks totalling 11 sill drives which totalled 160 m vertically. The remote mining method proved to be complex, cumbersome and very expensive. However, the ore was extracted successfully.By early 2010, previously developed ore had largely been exhausted and the future development with an orebody open at depth presented the opportunity to review the current extraction method. However, the new extraction method needed to maintain the tenet of excluding personnel from sill drives of active stoping blocks, but seek opportunities to reduce the difficult and costly aspects of the previous method. The new ‘Radial-in-Reef’ stoping reduced the development requirement from six to two drives per ore block. Cost implications aside, the significant reduction in prestoping extraction ratio was expected to also reduce the likelihood of seismicity. Transverse production rings were designed to be drilled radially from a drill stub mined from a mid-stope footwall drive. Stopes totalling up to 7000 tonnes were planned be fired in a single electronic blast. Extraction was designed to take place from a basal sill drive under teleremote operation. At the time of writing, the method was under trial.

Mar 21, 2011

By R M. Krek

The haulage system used to convey ore from an underground mine to a surface stockpile at the mine process plant is a vital component of the mine’s overall infrastructure and economic viability. The system selected has a significant impact on the set-up of the mine and the access to the underground mine. In turn, the set-up of the mine and the access to the underground mine have a significant impact on the system.A number of haulage technologies are available to transfer the ore from the underground workings to the surface stockpile, including hoists, conveyors, rail and trucks.This paper focuses on the shaft hoisting and inclined conveyor haulage technologies. These technologies have been used consistently to deliver ore from at depth and/or at high tonnage. Previous reviews of the appropriate vertical haulage systems have nominally been restricted to the respective systems only, with no consideration for any other scope or issues that may affect the selection. The selection of the appropriate vertical haulage system, whether shaft hoisting or inclined conveying, needs to consider numerous key factors.CITATION:Krek, R M and Northcote, A E A, 2014. A holistic viewpoint for selecting the vertical haulage system – shafts and conveyors, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 289–296 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By S J. Clarke, G Sieders

Double corrosion protection (DCP) rock bolts have evolved to become complicated assemblies comprising numerous components. This complexity is mainly associated with durability considerations including potential exposure to adverse groundwater conditions and ensuring separation of dissimilar metals within the bolt assembly itself.Recent progress in the construction of glass-fibre reinforced polymer (GRP) rock bolts have the potential to provide a viable alternative to conventional steel rock bolts in civil tunnelling applications. The durability of the material results in a much simpler bolt detail and permits the use of resin rather than solely cement based grouts.This paper presents the findings of the comparative structural testing of GRP bolts with conventional DCP steel bolts. The axial load performance, including stiffness, ultimate capacity and ductility of bolts are compared. Shear behaviour of bolts is considered, including durability issues associated with damage to the plastic sleeve used in DCP bolts.The paper also considers other issues which are relevant to the design of temporary and permanent rock bolts used in tunnel support, such as initial tensioning and grouting. Long-term performance, including durability and creep are also reviewed.CITATION:Clarke, S J and Sieders, G, 2014. Comparison of glass-fibre reinforced polymer rock bolts with double corrosion protection steel rock bolts for use in tunnel applications, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 237–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By H Chalcraft, T D. Mullen

Conditions encountered at a recently completed brownfields mining project provided valuable insight into, and development of, techniques for working in and around known underground mining voids in an open cut environment. The careful application of underground blasting principles to a pit environment and successful excavation whilst maintaining appropriate stand-off distances were two primary areas of innovation enabling the success of the project.Mary Mac Hill is a gold deposit situated less than 2 km south-west of the town of Laverton, Western Australia. It is owned and mined by Crescent Gold Limited. Previous underground mining by various other mining companies has left an extensive network of underground horizontal development, subvertical stopes and shafts, some of which daylighted at surface. This was identified as potentially posing substantial risks, which would prevent the application of conventional mining methods. Two major stopes were located under a hard banded iron ridge topped by a peak of cap, connected variously by narrow drives and vertical development. Due to the proximity of the first of these stopes to the surface, its dimensions and governed by procedures and advice provided by externally engaged engineers, Crescent Gold could not access the area of the ridge immediately overlying the stope using conventional open cut mining methods. This was the first of many hurdles surmounted in mining this deposit.The following report outlines how the challenges this geometrically complex deposit presented. Solving these problems enabled the team to mine the contained gold ore to a completed design, without subjecting personnel or mining equipment to harm due to a void breach incident. This paper outlines the numerous complications and difficulties Mary Mac Hill posed and explains the strategies developed to overcome them. The report also presents technical mass blasting details explaining two of the critical crown pillar blasts.CITATION:Mullen, T D and Chalcraft, H, 2012. Mary Mac Hill - The challenges and strategies of successful open cut mining: A complex underground gold deposit riddled with a network of complicated voids, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 89-96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012