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By M Campbell, A Jeffcoate, J-C Vannay, B Perriaux

Phyllite waste rock at the Simandou Pic de Fon and Oueleba Iron Ore deposits (Guinea, West Africa) variably weather to form clay-rich rocks. This weathering modifies the mineralogical, geochemical and mechanical properties of the phyllites. Final pit walls will largely be formed in phyllite, so it is critical that the slope design takes account of the distribution and variability of weathering within this material. Phyllite intact material strength has been correlated with geochemistry (ie mineralogy) facilitating the establishment of domains of intact rock strength (IRS). In order to calibrate this geochemically-based strength model, core from diamond drilling (DD), comprising a variety of phyllite material types (from soft clay to moderate strength rock), was geotechnically logged to assess intact strength; further validation was achieved by uniaxial compression (UCS) testing and point load tests (PLT). The correlation between geochemistry and strength offers a potentially powerful tool for differentiating basic mechanical properties of the rock mass, especially at Simandou where a significant proportion of the resource drilling is done by reverse circulation (RC). Unlike DD, reliable measurements of material strength from RC samples can prove difficult, especially in clay-rich material. Therefore, gaining information from routine geochemical assay results, independent of the sampleÆs physical integrity, is a valuable and cost-effective source of reliable empirical data. Data acquired using this approach provides an opportunity to develop strength domains, which are integrated into mine planning block models. In combination with other geotechnical characteristics, this can be a valuable input to the development of geotechnical models. This technique has allowed spatially representative rock strength data to be derived and offers the potential for optimising pit slope angles in areas where hitherto conservative design criteria had been assumed.CITATION:Jeffcoate, A, Campbell, M, Vannay, J-C and Perriaux, B, 2013. Modelling intact rock strength of clay-rich rocks with geochemistry at the Simandou iron ore deposit, Guinea, West Africa, in Proceedings Iron Ore 2013 , pp 193-202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By T Clemens, D Trumm

Adopting environmentally acceptable practices in New Zealand is a crucial requirement for mineral wealth development. Recent planned expansions in the coal and gold industry have increasingly placed mining in the media spotlight. A lack of appropriate standard environmental guidelines has resulted in inconsistent responses and assessments of current and proposed mines. These inconsistencies have lead to delays in decisions on developing economic mineral deposits that may have only minor short-term impacts, and have also allowed unacceptable environmental management practices to continue elsewhere. A research collaboration between CRL Energy, Landcare Research, University of Canterbury and University of Otago aims to provide regulator groups and the mining industry with a unified approach to the requirements of the Resource Management Act 1991,the legislation that largely drives the nationÆs environmental policies and guidelines. The tangible outcome of this research program will be water quality and impact management guidelines integrated into a decision-making framework. The result of this unification will assist in the development of viable mineral deposits and minimise environmental impacts. The framework will be derived from a synthesis of three objectives. Objective 1 identifies potential water quality impact. This objective is based on a targeted geochemical study of the lithology and waterways of the West Coast and Southland regions. Objective 2 categorises the degree of impacts on the ecology of receiving aquatic ecosystems and determines the processes that drive aquatic ecosystem recovery. Objective 3 identifies best strategies to sufficiently manage impacted ecosystems, and to prevent future unacceptable impacts. Wide consultation with representatives of the mining industry and regulator groups will occur frequently during the development stages of the framework. It is anticipated that this multidisciplinary approach will provide a robust and coherent, standardised system that will assist in achieving industry and environmental targets.

Jan 1, 2004

By R N. Lamb, A N. Buckley

Experiments have been carried out to establish whether time-of-flight secondary ion mass spectrometry (ToF-SIMS) is able to differentiate monolayer and multilayer coverage of thiol collectors on sulfide minerals. The systems investigated were those for which x-ray photoelectron spectroscopy is able to provide an independent determination of the extent of coverage, and included diethyldithiophosphate (DTP) and 2-mercaptobenzothiazole (MBT) on chalcocite, DTP on Ag2+MS prepared by sulfidising metallic silver, and isobutyl xanthate (BX) and MBT on galena. For monolayer adsorption of MBT on chalcocite, peaks from MBTû but not Cu(MBT)û ions were evident. For multilayer coverage, Cu(MBT)2û ions were clearly present, notwithstanding the fact that other data had identified the principal multilayer species as Cu(MBT). For adsorbed DTP on copper and silver sulfides, DTPû and metal(DTP)Hû peaks were observed for monolayer and multilayer coverage. Although the multilayer species was expected to be predominantly metal(DTP), metal(DTP)2û ions were evident for multilayer (but not monolayer) coverage. For the PbS/BX system, intact Pb(BX)2 or Pb(OH)BX ions were not detected for multilayer coverage, although Pb-containing ions heavier than PbBX were. Indeed, for all the systems studied, ToF-SIMS was able to differentiate monolayer from multilayer coverage. In general, however, the SIMS evidence alone might not be sufficiently definitive to effect the differentiation. In the case of collector adsorption on copper and silver sulfides, if the multilayer species detected had been the metal monothiolate only, and had not involved the formation of some metal dithiolate, then ToF-SIMS might not have been able to provide an unequivocal differentiation of the two coverage conditions.

Jan 1, 2005

Major Francis Hamilton Buchanan coined the term `laterite' (Latin; brick-rock) in 1807 for the red earths used for building blocks in southern India. Although these earths were actually weathered basalts, the term is now applied to weathering profiles developed upon a wide range of bedrocks. The Ni-laterites are a special class within the broad laterite family.

Jan 1, 1996

Landscape interpretation, geology and mining history is being successfully used to explore options for sustainable community tourism product development. Recent work by the author in Europe and Australia has indicated the value of adding and producing interpretive information about mine and quarry locations - both active and inactive. This work has allowed for the branding and development of new sustainable community tourism products based on the landscape, folklore, mine and geological heritage.   Communities in rural areas are seeking new opportunities to sustain their local economies. Using a relatively new phenomenon called geotourism as a starting point; they have developed themed products connected to walking/cycling guides, interpretive panels and visitor centres. These themes can be linked to geology, archaeology, botany, local history and to industrial heritage sites such as old mines, to generate local employment. This new geotourism approach has successfully brought a new and greater audience to discover the value of geology and mining history.   Communities have established a unique place for themselves within the tourism marketplace using the geotourism brand. Other communities with an established tourism product are also now using geological and mine heritage via geotourism to rebrand and meet changing global trends. The pooling of resources under the banner of geotourism has led to cost effective marketing, targeting and promotion of products.   Geotourism has emerged strongly in Europe, North America and China in the last decade. The Australian minerals industry now has an opportunity to implement this new branding concept to assist and benefit the communities in which they run their activities. Communities can also take advantage of the potential to develop a sustainable geotourism business around a past or present mineral industry in their vicinity.

Jun 1, 2010

A number of mineral deposits occur in close proximity to the Pacific plate fronts. Among these deposits are gold-silver and the base metal sulphide deposits of copper, zinc and lead. Gold deposits that commonly occur in these areas are of hydrothermal origin. Of these the epithermal deposits have attracted the attention of the exploration geologists as well as the metallurgists. One vital aspect of the activity of the geologists is the development of models for epithermal gold mineralisation in the Pacific Rim. These models can also be used by metallurgists for predicting gold extraction processes. This paper reviews the mineralogy, fineness and the host minerals of gold and examines the data in the light of gold mineralisation in the southwest Pacific Rim. The gold mineralisation models proposed for the Pacific Rim have been used to predict gold extraction processes suitable for the various mineralisation types. Discussed also are the mineralisation and treatment processes of some selected epithermal gold deposits and gold-rich porphyry copper deposits in Indonesia, Papua New Guinea, Solomon Islands, Fiji and New Zealand.

Jan 1, 1999

By W Curlewis, D Hake, Z Cuthbert

The South Island Line (East) will be a medium-capacity railway covering approximately 7 km from Admiralty Station to South Horizons Station on the south side of Aberdeen Harbour in Hong Kong, with intermediate stations at Ocean Park, Wong Chuk Hang and Lei Tung.South Island Line (East) Contract 904 project is located on the island of Ap Lei Chau at the southern side of Hong Kong island and requires extensive construction works to be completed in close proximity to the existing residential estates of South Horizons and Lei Tung. The project also has areas of significant cultural heritage, including 18th and 19th century temples and historical gravesites. Owing to the site access constraints and location for the project, detailed planning and methodology innovations have been required to ensure the most effective and responsible means of delivering the project works. To excavate the tunnels using drill-and-blast techniques in these restricted locations, the maximum instantaneous charge weight that could be fired while blasting was severely limited. To overcome these restrictions, the project team developed and pioneered the use of ‘deck loading’ in Hong Kong to minimise the impact of blasting operations and has successfully implemented double- and triple-deck blasting operations during the completion of tunnel excavation works.Upon completion of the drill-and-blast excavation, the tunnel lining works were completed using both in situ concrete lining with travelling forms and permanent shotcrete works.CITATION:Curlewis, W, Cuthbert, Z and Hake, D, 2014. SIL904 Hong Kong – Drill and Blast Tunnels, station blasting innovations (double- and triple-deck blasting) and lining solutions, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 21–28 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By F Clark, J T. Carswell

Ore definition for final stope planning is often a challenging prospect in underground (UG) gold mines which exhibit high geological and grade variability. Unlike the grade control (GC) scenario in an open pit (OP), the ability for the mining geologist to plan a sampling campaign which effectively characterises the underlying mineralisation is fraught with difficulty. UG sampling patterns are strongly clustered and typically not dense enough to characterise the spatial and statistical properties. Very commonly, sample volumes are not large enough to provide a reliable grade estimate of the surrounding rock. These factors critically affect our ability to accurately map out ore positions and estimate metal quantities.At Sunrise Dam, traditional UG sampling and modelling techniques have proven to be an unreliable strategy for successful stope planning and extraction. The problem was first observed during the final cut-back in the open pit for which the mineral resource model was constructed from UG diamond drilling. Open Pit grade control reconciliations were strongly positive for both tonnage and grade compared to the resource model. Underground workings missed significant quantities of ore which was laterally defined by open pit reverse circulation (RC) GC drilling. Upon examination it was realised that the cause of the problem was one of inadequate sample density and sample support, the implications of which potentially affected the entire UG mine.As part of a broader study into underground grade control procedures, detailed reconciliation of initial stope production from the GQ domain also pointed to inadequate sampling as a major constraint to effective grade control and reserve conversion.To overcome this deficiency, dense 115 mm wet RC grade control drilling and conditional simulation modelling has been successfully implemented with the intent to replicate the grade control process in the open pit. The increase in sample density and sample volume has proven to be a very effective tool for mapping out highly complex mineralisation. A marked improvement in stope definition, reserve conversion and Mine to Mill reconciliations has been demonstrated on the back of an innovative approach to UG grade control.CITATION:Clark, F and Carswell, J T, 2014. Using reverse circulation drilling to improve sampling in a complex underground gold operation – an innovative approach to underground grade control at the Sunrise Dam Mine, Western Australia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 143–152 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By A M. Avis

This paper presents an overview of recent developments in the Environmental Impact Assessment (EIA) process to provide the background for a more detailed analysis of environmental and social constraints that the Heavy Mineral Mining industry has encountered over the past decade. Four cases studies are reviewed to provide a context for further analysis and identification of cross cutting environmental and social issues that either resulted in the projects not proceeding, or in the Australian case study, places existing operations under significant pressure from anti-mining lobbyists. The Xolobeni project, from the Eastern Cape in South Africa, is presented as the primary case study because it is recent, topical, and accessible; and raised numerous issues related to mining in a sensitive environment. A proposal to mine an area adjacent to the Okefenokee swamps in 1997 was also met with strong opposition from various environmental groups in Georgia, USA. This case study is briefly reviewed to further understand what ultimately resulted in the project not proceeding. Opposition to mining at North Stradbroke Island is reviewed to identify current issues more applicable to a developed country. A further review of a strategic assessment undertaken at Wavecrest, Eastern Cape, South Africa is provided in support of possible solutions to the challenges identified in the case studies. Important common themes were identified, including in some cases unfortunate timing of the environmental studies, but in all cases opposition was due to ecological sensitivity, landscape quality and sense of place. In one case study limitations to the EIA process included inadequate detail in the specialist investigations and insufficient information on mitigation. In all cases public participation was a limitation. It was either insufficient; flawed through possible bias; too ‘top down’ and required engagement with mobilised, motivated lobbyists. There was also insufficient investigation of social impacts, particularly amongst rural communities directly affected by a project. Generally alternatives were inadequately considered, a recognised limitation of project level EIA. It is concluded that the EIA process should be started as early as possible (at prefeasibility), and that investigations should be expanded from a typical fatal flaw assessment to one that applies methodologies used in strategic assessment. In particular, opportunities and constraints of the natural and social environment should be assessed in the context of the mining option as well as other options, to allow for a more meaningful assessment of alternatives. Public participation must form an important part of this initial study, despite the potential risks associated with public engagement at an early stage in the project. The application of the IFC Performance Standards; and expanding the scope of the EIA into an environmental, social and health impact assessment will lead to a more rigorous procedure, and result in more defensible products which could successfully unlock the key to the resources in these sensitive areas.

Oct 5, 2011

Large mining operations need equipment that consistently performs as expected. The most effective way of ensuring this is to have a defined life cycle with an optimised maintenance strategy. The determination of this life cycle is an economic decision, influenced by the construction and utilisation of the equipment. An effective life cycle costing (LCC) tool must be able to process the many variable factors involved.Many factors influence the costs that are associated with a machine over its life. The most variable of these are the costs of maintaining the equipment. Maintenance costs are dependant not only on the utilisation of the machine, but also on the strategy that has been developed to support the machine through its life. A combination of supplier support, component changes, regular servicing and unscheduled maintenance needs to be modelled, based on a variety of drivers. Traditionally spreadsheets have been used to model these factors, but the increasing complexity of the situation can make spreadsheets unwieldy and difficult to manage. A database solution that breaks each activity into its constituent components, links them to an associated mine plan driver and then aggregates the result is the ideal tool to provide a time based cost profile. The evaluation of a number of scenarios, representing different maintenance strategies/life cycles can be rapidly undertaken. Auditability through inbuilt tools is required to provide easy tracing of data. Use of the host company's account structure allows for reporting against the standard chart of accounts.

Dec 6, 2010

By P Voulgaris

The Osborne Mine commenced production from an open pit in December 1994 with the first ore being hauled from underground one year later. Currently all ore is hauled up a decline by trucks until the shaft system is commissioned in early-1998. The mine is hosted within a multiply deformed and complex sequence of metamorphic, igneous and metasomatic rocks of mid Proterozoic age that are concealed beneath 20-40 metres of Mesozoic sedimentary cover. Epigenetic and largely hypogene copper - gold mineralisation occurs in a close spatial relationship with quartz - magnetite ironstones and is an important example of a significant mineralisation style in the Mt Isa inlier. Life of mine concentrator production, to year end 1997, totals 3.2 Mt of ore at 3.40 per cent Cu and 1.13 g/t Au. Total metal produced was 97 000 tonnes of copper and 2900 Kg of gold (95 600 oz) from some 348 000 tonnes of dry concentrates averaging 28.01 per cent Cu and 6.99 g/t Au. At the start of 1998 OsborneÆs total measured and indicated resource was stated at 11.38 Mt at 3.24 per cent Cu and 1.21 g/t Au with an ore reserve of 11.42 Mt at 2.90 per cent Cu and 1.09 g/t Au. Exploration efforts in and around the mine have been increased since 1996 and have resulted in an early success, with a 28 per cent increase in ore reserves since mine start-up, and the establishment of a 1.5 Mt inferred resource open to depth. During 1997 the performance of the concentrator has exceeded expectations with throughput having been increased to 1.45 Mt per annum. The Mining Cycle at Osborne has proceeded from discovery through feasibility and is currently seen to be in the latter part of the development stage and/or the early part of an expansion stage. This paper will describe the role of geology and exploration within these stages and will highlight how a number of key interpretations and decisions based on geology have both favourably and unfavourably affected the project.

Jan 1, 1998

Permeability and fluid pathways in fracture-controlled hydrothermal systems are governed by a dynamic competition between permeability-creation processes and permeability-destruction processes. Permeability evolution is coupled with the evolution of fluid pressure and stress states. Key permeability-creation processes are micro-scale to macroscopic fracture growth, and the generation of damage zones during co-seismic slip on faults or aseismic creep on faults and shear zones. The competing permeability-destruction processes include crack-healing and sealing, compaction and pore cementation. High rates of permeability destruction in hydrothermal systems require ongoing permeability enhancement to sustain high fluid fluxes and ore genesis.   In aseismic regimes, competition between permeability-creation processes and permeability-destruction processes can lead to continuous flow in deep level hydrothermal systems. However, in seismogenic regimes, rapid co-seismic permeability-enhancement is followed by progressive permeability-destruction in the intervening interseismic periods, and leads to episodic flow. The results of high pressure experiments are used to illustrate how pore fluid factors and stress states are dynamically coupled with permeability evolution in hydrothermal regimes. Particularly in the seismogenic mid- to upper crust, large changes in permeability during the seismic cycle govern relative rates of change of fluid pressure around active faults and shear zones. Rapid, post-seismic recovery of pore fluid pressures, relative to rates of shear stress recovery, leads to growth of hydrofracture networks prior to successive fault rupture events.   Pre-rupture hydrofracture networks do not develop where post-rupture fluid pressure recovery is modest relative shear stress recovery. At elevated temperatures, low rates of pore fluid pressure recovery relative to shear stress recovery promote ductile shear failure and grain-scale permeability enhancement within shear zones prior to rupture events.   The influence of pore fluid pressure cycling, shear stress cycling, and deformation processes in controlling the evolution of permeability, flow localisation, and flow anisotropy at the deposit scale are illustrated for mesothermal and epithermal lode gold systems.

Jan 1, 2005

By J Wheeler

The objective of this paper is to examine the operation of high frequency screens in closed circuit grinding, where the outcomes achieved indicate favourable economic gains at the comminution stage and downstream processes, including flotation, dewatering, and filtration operations. The classification process in grinding circuits has been slowly evolving within the last century. The history of classification devices brings to mind rake classifiers and spiral classifiers, which although having higher efficiencies compared to hydrocyclones, were not able to keep pace with the evolution of concentrator equipment treating higher tonnages. This higher tonnage throughput has tended to drive the concept of utilising hydrocyclones as the classification stage in closed grinding circuits. The comminution process is commonly the most energy intensive stage of mineral processing. Researchers have determined that the classification stage in the comminution process has the greatest potential for improvement. This paper is intended to inform mineral process engineers of the benefits that high frequency screens offer over hydrocyclones. This will be done by reviewing the purpose for the evolution of classification in the comminution process, documenting past and recent studies, and explaining the modern technology that is currently available.

Aug 8, 2011

By S Mitra, D O’Dea, N Barrett, T Honeyands, P Zulli

The steel industry continues to explore and demonstrate technologies that decrease its greenhouse gas emissions, especially in blast furnace ironmaking where alternate operating conditions will be required. As the furnace has been optimised over many years, it is approaching the minimum fuel rate possible with coke and Pulverised Coal Injection (PCI). Alternative operating conditions are therefore required to further decrease greenhouse gas emissions. Because of this, hydrogen has been proposed as a reducing agent in the blast furnace. Injection of hydrogen through the tuyeres was assessed using a comprehensive 2D blast furnace global model. The model was calibrated to a blast furnace operating with PCI as a base case and various approaches to hydrogen injection assessed, with a particular focus on displacing PCI. The maximum hydrogen injection rate of 19.5 kg H2 per tonne of hot metal was predicted, limited by decreases in the raceway adiabatic flame temperature and top gas temperature. Internal blast furnace conditions, such as gas composition and reduction degree were also predicted. Holistic analysis was performed to estimate the effectiveness of hydrogen injection on reduction of greenhouse gas emissions. Based on these results, the changes in blast furnace operation and emissions under hydrogen injection are discussed.

Nov 8, 2021

India is on fast economic growth. Even in the turbulent years of global crisis, it could achieve a growth of over eight per cent. In recent past, Indian Government has been contemplating a faster growth in all the sectors of economy so as to make the nation an economic power in the world.Steel is a versatile material. It has its role in most of the major industrial activities, such as infrastructure, automobiles, urbanisation, consumer durables and other. In other words, steel is a part and parcel of industrial expansion, urban and rural development. It is rightly admitted that steel acts as pillar of any development model. Volume of steel consumption is the barometer which measures economic progress and/or industrial status of any country.India and China are the two countries in Asia which have the significant impact on the global steel industry. Of course, China is much ahead of India in consumption level of steel.

Dec 6, 2010

By K Haga, G Danha, A Shibayama, L L. Godirilwe

The hydrometallurgical separation and enrichment processes provide an effective way to selectively recover metals from relatively dilute multicomponent sulfuric acid leach solutions. The multicomponent leach solution utilised in this study contained 0.3 g/L Cu, 0.34 g/L Ni, 0.13 g/L Co, and 2.96 g/L Fe, which was obtained after high-pressure oxidative acid leaching (HPOAL) of the copper-nickel smelter slag. The solvent extraction (SX), precipitation, and xanthate complexation processes were employed to recover and upgrade Cu, Ni, and Co from the leach solution. Batch SX tests were carried out using a countercurrent two-stage mixer settler extraction column, and LIX 984N (10 per cent v/v) as a copper extractant. Fundamental parameters influencing the extraction process such as pH, mixing speed, H2SO4 concentration, and organic/aqueous (O/A) phase ratio were investigated. For copper enrichment in solution, a combination of two extraction stages and two stripping stages were employed. Copper was successively separated from Fe, Ni, and Co under optimised extraction conditions (pH 2, 400 rev/min, O/A 0.25, and 20 min contacting) and stripping conditions (175 g/L H2SO4, 400 rev/min, O/A 4, and 20 min contacting). About 97 per cent of copper was extracted with low co-extraction of Fe, Ni, and Co of about 5.90 per cent, 1.47 per cent, and 2.53 per cent, correspondingly. A final Cu-rich solution containing 23 g/L Cu was obtained with a very low Fe concentration of 0.05 g/L. Additionally, for iron removal from the Ni/Co raffinate solution, more than 99 per cent of iron was precipitated at pH 4 by the addition of a calcium carbonate (CaCO3) suspension, with low co-precipitation of nickel and cobalt of around 3.68 per cent and 2.27 per cent, respectively. Furthermore, about 83.6 per cent of nickel and 99.4 per cent cobalt were co-precipitated from the solution by potassium amyl xanthate (PAX) solution at pH 6. The Ni and Co xanthate complexes were thermally decomposed and recovered as cobalt oxide (CoO) and nickel sulfide (NiS) solids.

Aug 24, 2022

By L P. Trout, D G. Reid

PanAust Limited (PanAust) has successfully constructed and commissioned two mining operations in Lao PDR over the past decade and undertaken major studies for three new mine developments. The management of potentially acid generating mine waste and tailings in close proximity of local communities sensitive to water discharge quality have been recurring themes that have confronted PanAust’s project study, development and operational teams. Further compounding challenges, such as the effects of intense annual tropical monsoonal conditions, staging of embankment raises and regular lifting of spillway structures, integrating mine waste and tailings management into production plans and ensuring the long term stability of structures, have been addressed by implementing leading practice management solutions.A recognition of the criticality of managing the substantial business risks associated with these crucial activities led to the early establishment of a governance structure to ensure that the highest standards are embraced for planning and execution. Importantly, these are guided and monitored by a panel of highly experienced and qualified international specialists reporting directly to PanAust’s Managing Director – the Tailings Independent Review Panel. The stewardship process has been effective in identifying potential shortcomings in management systems and has led to enhanced executive commitment to risk informed designs, assurance and overall process rigour.CITATION:Trout, L P and Reid, D G, 2018. PanAust Limited’s approach to mine waste and tailings stewardship, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 135–155 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By E Ben-Awuah

Mine planning is the backbone of all mining enterprises and determines the profitability or otherwise of any mining investment. Providing high quality ore and tailings containment at the right time are the main drivers in oil sands mining. Recent environmental and regulatory requirements also makes waste management an integral part of mine planning in the oil sands industry (Directive 074). Due to the limitation of lease area, the pit phase advancement in oil sands mining is carried out simultaneously with the construction of tailings dykes in the mined out areas of the pit. These in-pit dykes are constructed to hold tailings that are produced during the processing of the oil sands ore after an initial external tailings facility. Most of the materials used in constructing these in-pit and ex-pit dykes come from the oil sands mining operation, making it necessary to have a plan for supplying the dyke material. The research problem here is categorised as: determining the order of extraction of ore, dyke material and waste to be removed from a predefined ultimate pit limit over the mine life that maximises the net present value of the operation û a strategic schedule; anddetermining the destination of dyke material that minimises construction cost depending on the construction requirements of the various dykes as per their designs û an operational schedule. There has been developed, implemented and verified a theoretical optimisation framework based on mixed integer goal programming (MIGP) to address the oil sands long-term production scheduling and waste management problem. The research introduced the development of multiple material types and multiple destination optimisation techniques using MIGP in the context of mine planning. This study presents an integration of mixed integer programming and goal programming in solving large-scale mine planning optimisation problems using clustering and pushback techniques.

Sep 26, 2011

By R A. Pax, B Cornish

"Although it is well known and easily experienced that the feed size distribution influences the throughput and stability of operation of a semi-autogenous grinding (SAG) mill, the details are poorly understood since it is often only the input and output measurements that are used to identify unfavourable in-mill conditions. Load cells and power monitoring are sometimes used but are generally poor indicators of the mechanisms that lead to such unwanted conditions.At the MMG Century operation a 12-microphone array around the SAG mill using non-contact acoustic measurement methodology has been used to diagnose the in-mill conditions to facilitate improved throughput and stability of operation. Use of acoustic measurement and control has provided a demonstrated increased throughput of at least 20 per cent as well as improved stabilisation of the mill. Since the information derived from the acoustic noise from a mill allows discrimination of the behaviour of the steel balls and the rock, a number of in-mill conditions can be identified with signals that include toe and shoulder angles, water holdup and the ball to rock ratio.Feed size variations, measured online with an imaging system, have been used to determine their effect on the internal charge behaviour. It has been found that circumferential segregation of steel balls and rock occurs as well as poor mixing of large rocks. Both of these effects are not conducive to optimal breakage rates of different size fractions. Longitudinal segregation effects also occur. This paper presents and discusses these results and illustrates how the new acoustic knowledge can be used to manage and improve mill operation and stability.Citation:Pax, R and Cornish, B, 2016. Understanding Size Effects of Semi-autogenous Grinding (SAG) Mill Operation as a Pathway to Solving Feed Disturbances - Case Study using the MMG Century SAG Mill, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 321–330 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By K Rozlapa, P Waters, H Middlemis

A major challenge for closure planning at mining operations below the water table is evaporation from final void pit lakes and concentration of salts, which can impact on downstream groundwater (and surface water) flows and quality. Where such impacts are deemed unacceptable, the closure approach that is often adopted is to infill the final voids with waste rock to above the pre-mining water table to prevent the development of a pit lake and subsequent evaporative losses. BHP Billiton Iron OreÆs Marillana Creek (Yandi) mining operations face these issues. The orebody is a channel iron deposit that forms the major aquifer in the region, which will be completely mined as a series of elongated open pits over tens of kilometres. The major constraint on mine closure planning was the stripping ratio of less than one, which means that there is insufficient waste rock to infill all areas to the pre-mining water table. Hydrogeological investigations and groundwater modelling indicated that standard mine closure approaches would result in pit void lakes becoming saline sinks unless the residual void geometry was optimised to minimise evaporation and maximise throughflow. The solution developed is a cost-effective long-term mine plan that meets all mine closure objectives, and involved:the selective infilling of all pits, largely using run-of-mine waste dumping with limited re-handling; the diversion of the major part of up-catchment creek flows around the mining operations to allow mining of the resource under Marillana Creek crossings, which in turn restricted overall aquifer recharge and reduced the elevation of the long-term water table; the diversion of some minor creek tributary flows into specific locations within the mine path to induce hydraulic gradients to maintain groundwater throughflow and water quality; and close integration of mine plan optimisation (mining and waste dumping schedules) with groundwater modelling scenarios to achieve acceptable environmental outcomes. This approach is designed to result in no reduction in downstream surface water flows or quality, maintenance of adequate downstream groundwater throughflow to support groundwater dependent ecosystems, and no reduction in the beneficial use status of the downstream groundwater resource.

Jan 1, 2006