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By I T. Ross

In the last 50 years there have been tremendous improvements in equipment used in development on underground mines. Compressed air powered jacklegs have been replaced by high powered electro-hydraulic drifters on sophisticated drill jumbos and load haul dump units have taken over from small shovels and rail cars.Despite the increase in power applied in key parts of the development cycle, average advance rates have fallen and costs have increased. The factor that is most often regarded as the main contributor to slowing advance rates is increased support requirements. Whilst there is no denying that the drive to improve safety has resulted in the requirement for more bolting and the installation of a skin support (mesh or shotcrete), this is not the only factor.Within the industry as a whole, many of the basic principles of development appear to have been lost over time. This paper looks at a historical case study and discusses some of the features of old development cycles that are no longer in use. This highlights some of the basics that appear to have been forgotten. These may be indicators to what may provide improvements in the conventional drill and blast development cycle.CITATION:Ross, I T, 2014. Development – back to basics, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 67–74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By T Walsh, S R. Mudnuru

The development of lithium-ion batteries, coupled with the global trend towards electrification of transportation, has led to a dramatic increase in the demand for lithium. The production of lithium from hard rock ores is increasing, and flotation has proved to be an effective means for the beneficiation of many pegmatitic lithium ores. Clariant Mining Solutions has developed a range of novel collectors for the flotation of spodumene and other lithium ores, and this paper presents examples of some of the most recent developments. Fatty acids are the typical collectors for lithium flotation, however the grade and recovery achieved with these collectors is often below the desired level. There are also some significant drawbacks associated with the use of fatty acid collectors, such as the formation of calcium soaps which give rise to filtration problems and the need for acid washing. Several FLOTINOR products have been developed as alternatives to fatty acids. These products offer equivalent or better metallurgical performance at significantly lower dosages than fatty acids. This offers benefits to the flotation circuit as well as potentially reducing the issues associated with downstream processing of the concentrate.

Aug 24, 2022

By S Larbi-Bram, F Shi, E Manlapig

Mining companies have recognised that characterisation of particle breakage plays an essential role in the design and optimisation of comminution circuits. Recently the JKMRC comminution research team has developed a new breakage model incorporating the effect of particle size, and a new breakage characterisation testing device, called the JK Rotary Breakage Tester (JKRBT), which allows rapid testing of particle breakage under high energy single impact and low energy repetitive impact conditions. The latter is believed to be the dominant breakage mechanism in AG/SAG mills. Existing devices, such as the JKMRC Drop Weight Tester, are not suitable for performing repetitive impacts since they are too time consuming. Positive feedback received from mining company sponsors to the new technology has prompted the JKMRC to further validate the device and the model through a formalised experimental test program on professionally designed and manufactured JKRBT machines. The first JKRBT was installed at the Anglo Research laboratory in Johannesburg in March 2007 and four more major mining companies will participate in the project in 2008, with commercial release expected in early 2009. The JKRBT has the potential to revolutionise ore testing, with applications in laboratory impact breakage characterisation of rock samples, drill cores, coal and other materials. It also stands poised to significantly advance the process control of comminution circuits since it is readily adaptable to on-line ore hardness measurement. Can any mine afford to miss out on this technology?

Jan 1, 2008

A series of physical tests have been conducted to determine the actual performance of bunton to shaft side wall connections typically used in new shaft construction in South Africa. The test set-up is described, together with the applied loading, which incorporates a cyclical load component and a quasi-static load component, in an attempt to simulate actual conditions in the shaft. The test results are given and it is shown that generally the performance is adequate, provided double-slotted holes are not used. Generally the fatigue performance is found to be good, with the only exception being cases where the bottom of the bunton is lower than the seating level for the bunton to side wall connection. Arising from the tests, typical design values of connection stiffness, strength and fatigue life are proposed and a design procedure including these three key aspects of connections is described.

Jan 1, 2005

By J Evans-Wheeler

"The mandate of the 2005 VALMIN Code to provide ‘(all) reliable, thorough, understandable material information required by investors and their advisers when making investment decisions’ requires that due diligence for tenure be full and thorough. Yet a published due diligence would often appear to be simply a list of tenures allegedly held without any commitment as to the standing of the tenure as safe and secure or otherwise.The value of due diligence for tenure, as mandated in the 2012 JORC Code and the 2005 VALMIN Code, must focus on compliance rather than simply on ‘vital statistics’. Enforcement in every jurisdiction in Australia focuses on penalties (some more harsh than others) for non-compliance, which, in turn and most importantly, reflects directly on security of tenure. Some 22 Acts (on average) impinge on security of tenure and fundamentally underpin the security of any mineral asset.This paper will outline regulatory processes to demonstrate how tenure compliance is achieved and argue that the rigorous application of good practices in tenure evaluation will lead to more of this information being made available on a regular basis.The paper will then focus on further practical examples of tenure compliance failures, the application of these to the requirements of the JORC and VALMIN Codes and due diligence that failed to fulfil the mandate. Examples will be given that alerted other professionals using the JORC Code to complex geological and mining situations of which they were unaware in their valuations.Finally, the author will make a personal plea for tenure to be considered at the commencement of any reporting process.CITATION:Evans-Wheeler, J, 2016. The VALMIN code and tenure compliance – not just a list, in Proceedings Project Evaluation 2016, pp 112–121 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By MáAndrusiewicz, M M. Hilden, M S. Powell, P D. Kay, B Foggiatto

Circuits with unconventional and potentially more complex designs are predicted to become more common in the future as plant designers and operators look to process ores more efficiently. Ideas have been presented on how circuit design may be changed to utilise todayÆs technology to address tomorrowÆs challenges (Powell and Bye, 2009; Powell, Benzer and Mainza, 2011a). High pressure grinding roll (HPGR) installations in various configurations; application of preconcentration plants eg sorting, magnetic or gravity separation; and preweakening devices eg microwave processing; are all examples of technologies having the potential to deliver a significant reduction in comminution energy for ores amenable to these processes. Not only will future novel circuits contain equipment for which models are not as well developed (if at all), many will likely require the ability to respond to variations in feed, and interact with geometallurgical models requiring process adjustments when the ore characteristics change.In order to confidently simulate more complex circuits and accommodate variations in feed type, a significant advancement in modelling and simulation capability is required. This includes dealing with multiple components in the feed, accommodating different competencies of ore, utilising physical separation opportunities and tracking the grade reporting along the different potential processing routes. Developing the means to simulate complex circuits has been a key priority of a collaborative group of comminution researchers working to solve these challenges.Simulations are presented utilising a new configurable simulation interface called the model developers kit (MDK). The MDK is designed to accommodate multi-components and incorporate new models under development. These will be used to demonstrate the potential of flexible circuit design, based on measured ore properties and equipment performance.CITATION:Foggiatto, B, Hilden, M M, Powell, M S, Kay, P D and Andrusiewicz, M, 2012. Simulation of flexible circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 291-298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By T J. McGavin

This paper examines the fire life systems implemented in two existing tunnels and discusses whether the standards used were appropriate. It focuses on the Terrace Tunnel as this upgrade and refurbishment is complete.The New Zealand Transport Agency (NZTA) manages six tunnels on the State Highway network with two of these built in the last seven years. The Terrace Tunnel, opened in 1978, was refurbished with modern fire life safety systems in 2010–2012. An interim upgrade of the Mt Victoria Tunnel, opened in 1931, was also carried out at this time.In present times, few existing tunnels have undergone significant upgrades and refurbishments. The Terrace Tunnel required: new power supplies, control buildings, lighting, wall panels and jet fans, a deluge system, emergency exit lights and way-finding lights, a public address (PA) system, a radio rebroadcast system, lane control sign (LCS) and variable message sign (VMS), an over-height detection system (OHD) and a new tunnel management system.In the absence of suitable guidelines, various standards were used to carry out the refurbishment. The Austroad Guide to Road Tunnels and AS4825 Tunnel Fire Safety, although designed for new tunnels and not specifically intended for existing tunnels, provided a framework. A multi-criteria assessment of risk (MCAT) was carried out to determine the systems to be provided.The Terrace Tunnel has perhaps set a benchmark for refurbishing existing tunnels as few projects of this type have been completed recently. This paper examines the process and the outcomes.CITATION:McGavin, T J, 2014. The refurbishment of the Terrace and Mt Victoria Tunnels, Wellington, New Zealand, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 87–94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By D Wei

Large tonnages of low-grade haematite ores need to be treated every day in China. One of the mineralogical characteristics of these haematite ores is that the grain size of haematite is smaller than that of quartz and is not uniform in the ores. Therefore, a flow sheet consisting of gravity concentration, low-intensity magnetic separation, high-intensity magnetic separation and reverse flotation is mainly used to separate haematite ores in China, to obtain acceptable beneficiation performance and reduce the operating costs. Nowadays, whether based on mineral processing practice or theoretical analysis, the results show that the application of the above-mentioned flow sheet is able to take full advantage of these mineral processing methods and achieves satisfactory benefi ciation of haematite ores. For example, when the iron grade of the haematite ore is about 29 per cent Fe, a concentrate assaying 68 per cent Fe can be obtained and the recovery of iron is over 80 per cent. In the future, research work on the beneficiation of haematite ores should focus on investigating the most feasible particle size for gravity concentration circuit feed so that the operating costs can be reduced and ultimately the separation performance can be improved.

Jul 11, 2011

By D Cork, R Peet

"Methane is a signifi cant greenhouse gas. Methane is released from coal seams during the mining process, both in surface and underground operations. This uncontrolled release is termed æfugitive emissionsÆ and in underground mines is transferred to the atmosphere in ventilation air, known as ventilation air methane (VAM). The global VAM emissions are over 369 Mt of CO2-e/a (Butler, 2011; US EPA, 2010). Coal mines may abate this VAM or consider abatement should there be a price on carbon. These fugitive emissions are heading towards ten per cent of AustraliaÆs emissions by 2020 (Department of Climate Change, 2011).There are safety issues involved in VAM destruction. Due to the nature of coal, and coalextraction, unpredicted methane spikes above the lower-explosive-limit (LEL) can occur in theventilation air; for example outburst events or ventilation failure. This could lead to a mine fi re ifthe mine ventilation air was connected to a VAM abatement plant and the risks are left unmitigated.CorkyÆs is working with the mining industry to directly address these safety issues. CorkyÆs calltheir technology VAM RAB, which stands for ventilation air methane regenerative afterburner(VAM RAB). VAM RAB utilises the principles of a thermal oxidiser.This paper discusses fi ve independent layers of protection (ILPs) to fi rst stop methane reachingthe thermal oxidiser and secondly prevent the fl ame front from burning away from the VAMRAB. The test work completed or contemplated includes safety integrity level (SIL) assignmentto various vents, barriers and door systems to prevent a fl ammable mixture reaching the VAMRAB, proven rapid response methane monitoring sourced from the petrochemical industry, anddefl agration experiments to test the eff ectiveness of the passive geometry and active engineeringcontrols. These experiments and SIL assessments indicate that it is possible to safely connect theVAM RAB to a working coal mine.Further work is required to upscale the pilot safety work. Refi nement to the design is possible;for example improvement to safety duct controls once trialled at demonstration scale plus thermalenergy capture for power generation or other applications to provide heat. Nevertheless, thispaper shows how safety issues can be managed by a multilayer of protection approach usingvents, barriers and doors, and appropriate thermal oxidiser geometry."

Jun 1, 2012

By S Bright, M J. Masamvu, E K. Chiwandika, S Dandi, S M. Masuka

The depletion of high-grade hard and lumpy chrome ores has forced Zimbabwean ferrochrome producers to resort to low-grade friable ores that have an average of 28 per cent fines against a set limit of 12 per cent. Submerged open arc furnaces currently in use are associated with eruptions within the furnace because of the high amounts of fines, high energy consumption, as well as high SO2 and CO2 emissions. Traditionally employed agglomeration methods such as pelletising and the use of coke in the furnace have been discarded because of the pressure to lower operational costs and to achieve higher profit margins. This research aims to develop a method to incorporate lowgrade friable ore fines and unprocessed coal into production while lowering CO2 and SO2 emissions through a closed direct current (DC) arc furnace. The closed DC arc furnace could incorporate the friable ores and coal while maintaining above 90 per cent reduction rates. Preliminary findings also show that energy consumption could be reduced by up to 35 per cent by incorporating a pre-heating and pre-reduction system using the flue gases from the furnace. In the proposed circuit, the cost of production per ton of ferrochrome might be potentially lowered by an average of 30 per cent.

Jun 19, 2024

By M, C Silveira, C Ellice, D Christensen

Peak Gold Mines (PGM), a member of the Rio Tinto Group, is an underground and open cut gold mining operation located near Cobar, NSW. A multi-phase study was initiated in 2001 in support of developing a dry æmoisture store and releaseÆ cover system design for the PGM tailings dam, which contains potentially acid-forming tailings material. The first phase consisted of characterising the tailings and potential cover material (waste rock from an open cut operation) as well as soil-atmosphere cover design modelling. The second phase involved construction of two cover system field trials on the tailings dam and installation of a variety of field instruments to monitor the hydraulic performance of the test covers during all seasons of the year. Field performance monitoring commenced in April 2002 and will continue for a minimum of two wet-dry climate cycles (third phase), prior to using the field data for calibration and subsequent validation of numerical models developed for the cover system trials (fourth phase). This paper describes the work completed for the first two project phases and also discusses the initial performance of the cover system trials.

Jan 1, 2003

By P Jones

Fosterville Gold Mine is an underground operation located approximately 20 km northeast of Bendigo and 170 km north of Melbourne. Fosterville is the most productive gold mine in Victoria, producing over 100 000 ounces of gold annually. Access to the underground is via two portals cut into previously mined open pits. Fosterville is 100 per cent owned and operated by Northgate Minerals, a gold and copper producer with mining operations, development projects and exploration properties in Canada and Australia. (Northgate Minerals Corporation, 2010).Underground operations commenced in 2006 with ore production focused on three orebodies – Phoenix, Ellesmere and Falcon. Primary ventilation to the existing operation is provided by wall mounted exhaust fans located underground. This system provides approximately 220 m3/s of primary ventilation to the operations with intake achieved through the portals. Exploration drilling during recent times has uncovered another lode, the Harrier orebody, located 2.2 km to the south of the existing workings. Due to the location of the new Harrier orebody, vent analysis revealed the requirement for a separate source of primary ventilation to service Harrier. Figure 1 shows a current underground long section and the location of Harrier in relation to the existing workings. A number of options were considered, including a parallel decline from one of the existing two portals, however, a 4 m diameter, 350 m deep surface ventilation shaft was selected as the most suitable and feasible option for the mine.In December 2009, geotechnical drilling commenced to determine the most suitable location for the shaft. Site locations were constrained by a number of factors including interaction with current and planned surface infrastructure as well as proximity to nearby community members at the southern end of the mining lease. Results from the geotechnical drilling indicated that the majority of the proposed shaft would be suitable for a 4 m raise bored shaft. However, the top 40 m of the proposed shaft were deemed unsuitable for raiseboring due to zones of weakness that would likely influence the stability of a 4 m diameter shaft (Robinson, 2010). Following independent geotechnical advice and input from experienced raiseboring contractors, it was decided to construct a 40 m presink prior to raiseboring activities.A crane mounted auger was chosen as the preferred method to construct the presink. This method differs substantially from traditional blind sinking methods which are highly labour intensive. The auger, or drill, is designed and built to be attached to a crane base using engineered pivoting cradles. The auger is suspended from the crane jib by pennant ropes attached to hydraulic rams. The auger applies rotation and axial loads to the drilling tools via a telescopic steel bar (Kelly Bar). Drill tools are attached to the bottom of the Kelly Bar and comprise an assortment of drilling buckets and reaming barrels. Drilling buckets cut in situ material and collect the spoil for removal and are used for the excavation of the ‘pilot hole’. Reaming barrels are used to expand the diameter of the excavation by directing cuttings into the pilot hole which are then removed by the drilling bucket. In June 2010, the presink was constructed utilising a crane mounted auger with support to the shaft walls applied via a remote fibrecrete unit. The excavation method involved cutting a series of smaller diameter holes (2.4 m wide) before reaming out to the final diameter (4.7 m wide) in 4 - 5 m vertical increments. Fibrecreting activities were carried out on the backshifts, to ensure the stability of the excavation and minimise interaction between the two units. The presink was completed on time and offered many advantages compared to traditional blind sinking methods, including safety, costs and timing. This paper will examine the benefits of this method as well as lessons learnt and future applications in the mining industry.

Mar 21, 2011

By J T. Carswell

Best practice mine sampling should provide a detailed quantification of all potential sources of error at each stage of sampling, sample preparation and assaying.Quality assurance (QA) should include testing for and quantifying potential sampling errors, and should be the basis for establishing ongoing sampling protocols, should set error limits and define quality control (QC) procedures. QA should be within the framework of Theory of Sampling (TOS) but may not involve the estimation of the sampling constant and the application of Gy’s formula.Best practice QC should be carried out efficiently and in a timely and cost-effective manner with regular reporting against the guidelines established by QA.This paper provides an assessment of, and checklist for, current best practice sampling QA/QC with examples from operating gold mines including the QA/QC of underground (UG) reverse circulation (RC) grade control.CITATION:Carswell, J T, 2017. Best practice sampling QA/QC for gold and base metal mining – including how to assess the applicability of underground reverse circulation grade control sampling, in Proceedings Tenth International Mining Geology Conference 2017, pp 297–304 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By L Drowley

The Adelaide Desalination Plant (ADP) draws raw sea water into the facility and returns saline concentrate to the Gulf St Vincent via subsea conduits. This paper describes the detailed design and construction methodologies developed for the cross connection tunnel excavation. The paper concentrates on key design elements which include:· lateral breakout support of the segmental tunnel lining,· ground improvement grouting in the zone of the cross connection tunnels due to extremely variable and weak ground conditions, and· excavation methodologies and proposed support types of the riser to tunnel cross connections.The design process consisted of developing concepts, detailed risk assessment, three-dimensional (3D) finite element modelling and structural analysis for temporary support of tunnel lining; functional design of the ground improvement grouting and the temporary support; and permanent lining design of tunnel to ocean riser connections in a mixed soft ground/hard rock environment.The paper also presents conclusions of the design based on construction data available, and highlights the close collaboration between the design team and construction team.

Mar 8, 2011

By J R. Robinson

Prior to mine development, exploration drilling within the Luise Caldera on Niolam Island encountered gold mineralisation to the northwest of the main Minifie and Lienetz orebodies. This mineralisation was referred to as the Kapit orebody, and ten diamond drill holes were subsequently completed over the area to investigate its economic potential. Several significant mineralised intercepts were returned. These were interpreted using the orebody model developed for Lihir at that time which invoked a strong horizontal control to mineralisation. Additional consideration was given to the elevated geothermal temperatures encountered, the proximity of the mineralisation to the ocean, and its perceived depth below sea level, resulting in the Kapit area being given a low priority for follow up investigation. As a result, no further work was completed over Kapit until recently. The Kapit orebody was the target of an intense diamond drilling programme during 2002/2003. Data from this latest round of drilling has significantly improved understanding of the mineralisation and associated geology. The significant orebody now delineated at Kapit substantially differs from past interpretations, and the latest data has upgraded its economic potential. A resource estimate and other critical studies completed in 2003 enabled an updated reserve statement to be issued in February 2004 including the Kapit mineralisation for the first time. Total Probable Reserves at Kapit stand at 25.2 million tonnes (Mt) at 5.28 grams of gold per tonne (g Au/t), for a total of 4.3 million ounces (Moz) of contained gold.

Jan 1, 2004

By M Simanjuntak, A M. Supomo

PT Freeport IndonesiaÆs copper/gold operation disposes of approximately 222 000 dry metric tonnes of tailings per day via two thickeners. Reduction of the flocculant dosage rates in each of the tailing thickeners has been achieved with the installation of Clarometers«, modifications to the existing operating DCS control strategy and a change in plant flocculant. This has reduced the flocculant consumption rate in the last twelve months by approximately 20 per cent. It has also highlighted the disparity in the settling rates of the two thickeners. Collaborative efforts between Cytec technical site engineers and Freeport operational personnel have made possible the overall gains achieved in the tailings thickener optimisation.

Jan 1, 2003

By J Manuel, A Trudu

Regulations on the emission of particulates from sinter plant stacks are becoming increasingly stringent and reducing these emissions by improving gas cleaning systems is a significant cost to the sinter plants. This paper describes an investigation into the emission of particulate matter from an iron ore sinter bed during the sintering of a Japanese Steel Mill (JSM) style ore blend in a 300 mm diameter pot grate test facility. Several techniques were trialled to determine a reliable method to sample the quantity of dust emitted and determine the mechanism of dust emission from the sinter bed. The nature of the dust was also examined using chemical and size analysis as well as optical and scanning electron microscopy. The paper discusses the techniques used to carry out the program as well as results on dust loading measured during sintering and the nature of the dust captured.

Jan 1, 2002

By J P. Sykes, T C. McCuaig, J E. Vann

Resources added to the global metal inventory through exploration over the past 15 years have been generally of poor quality (declining grades, recoveries and lack of acceptable financial return). Similarly, companies opting for an acquisitions-based strategy have had to pick from a group of poorer quality resources left from previous exploration booms, and will struggle to deliver this metal to market economically. Increasing difficulty in obtaining sufficient social and community acceptance of mining projects and potentially an energy-constrained future may exacerbate this problem, redefining what is considered ‘ore’. There will need to be more focus on deposit quality, defined as sustainable margin in the future business environment.Traditionally there has been a lack of translation of ‘mineralisation quality’ back to mineral project design and mineral exploration. This disconnect is due to two main factors: the first is technical – inherent deposit variability; and the second is organisational and socio-psychological –the mindset of explorers and project managers themselves.There are four elements to value realisation for a mineral deposit: (1) social licence to operate; (2) geological factors (depth, geometry, water and geotechnical, and geometallurgy – influenced by texture, mineralogy, chemistry and grades); (3) financial engineering (capex, opex, future commodity prices, future energy prices), and (4) operating factors (production rate, recovery, energy consumption). These elements are strongly interdependent, and geology underpins and drives linkages between them. A quality deposit addresses all of these elements and thus can be developed in a time frame that allows acceptable returns to the owners of the invested capital.Geological drivers of the above elements can be measured and mapped throughout a deposit. Moreover, when viewed in the context of mineral systems, a predictive understanding of the common causative processes of quality (despite deposit-scale variability) is emerging, and with it the ability to target quality of mineralisation, not just quantity of mineralisation.The second factor is a ‘heuristic software problem’. Current lines of education (and consequently organisational and professional structures) are discipline-based, producing ‘silos’ that do not speak each other’s language and work with different ‘mental models’. People who effectively recognise systemic links between these silos are called ‘boundary spanners’, of which we propose two distinct types: outside-insiders and inside-outsiders. Outside-insiders are people who are within a community, but recognise advances in outside fields and effectively integrate them into the community. Inside-outsiders start outside of a community, and successfully bring new ideas into it. Common traits in boundary spanners are: they seek exposure to (and embrace) key ideas that are outside of the framework of their own specialisation; they have high mental processing ability (MPA) – the ability to connect systems that are currently not perceived to be connected; and they introduce ideas from outside a field into a new context in a way that re-frames the field.The challenge is to identify and nurture potential boundary spanners that can build critical links, in particular between the (largely geoscientific) mineral exploration mindset and the (largely non-geoscientific) project development mindset. Critical linkages to be built are between mineral system science, targeting science, and whole of value chain modelling.CITATION:McCuaig, T C, Vann, J E and Sykes, J P, 2014. Mines versus mineralisation – deposit quality, mineral exploration strategy and the role of ‘boundary spanners’, in Proceedings Ninth International Mining Geology Conference 2014 , pp 33–42 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By I Cameron

Simulation is increasingly being used to analyse mineral processing operations and explore efficiency options. Engineers that use simulation are rightly concerned with the quality and applicability of the underlying models. However, many of these models have a significant empirical component, and the best structure for this component may not be apparent. There is an opportunity to improve the quality and application range of these models by exploring potential structures for this empirical element. One approach to this problem is the use of structural optimisation, which is a formalisation of the model development process. This method searches through a family or hyper-structure of candidate models for a model that is optimal with respect to some measure of model quality. This method has been applied to the modelling of an industrial flotation circuit. The result was a model that was a significant improvement over a number of standard models reported in the literature. Structural optimisation provides a method to compare potential models in a systematic and efficient way, and hence to improve the structure of process models.

Jan 1, 1998

By C Torrisi, J Andreatidis, M Duffy

BHPÆs Cannington process plant was commissioned in October 1997. The Cannington ore contains high grades of silver, lead and zinc but also contains high levels of fluorine which must be removed to produce a marketable concentrate. As a consequence the plant is more complex than the typical base metal concentrator. Some of the features of the Cannington operation include a single stage autogenous mill, multiple stages of flotation cleaning, two leach circuits, pressure filtration and a paste fill plant. The start-up and achievement of design performance for new lead/zinc operations has traditionally taken much longer than for gold or copper operation and is littered with many tales of woe with feasibility targets often not achieved (Agarwal, Brown and Katrak, 1984; Bulatovic and Wyslouzil, 1999; Leung, Andreatidis, Woodall and Alford, 1996; Sherman, 1999; Ward, 1998).

Jan 1, 2000