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By D Sert, A Jayasekara, P Gardin, B J Monaghan, S J. Chew, P Zulli, D Pinson, X F. Dong, R Ferreira

In an ironmaking blast furnace (BF), molten slag and hot metal form in the softening-melting (cohesive) zone and then trickle through the coke packed bed before being discharged from the taphole. During their downward flow, there are significant interactions occurring between liquids and other phases, such as gas and packing particles. Overall, the formation, dripping and discharging of these liquid phases, particularly molten slag, have a significant impact on BF operations in terms of furnace permeability, fuel consumption, process stability, product quality and ultimately, productivity. Hence, understanding the liquid flow behaviour in the BF lower zone is critical for designing optimal operations. In the current investigation, the flow behaviour of slag droplets was investigated at a mesoscopic level using a combined numerical and physical modelling approach. The interaction between slag and carbonaceous materials was studied using sessile drop wetting experiments, slag flow through a funnel and a high temperature packed bed and the Volume of Fluid (VOF) modelling technique. Molten slag flow and counter-current gas-slag flow in the packed bed was investigated in terms of superficial gas velocity, slag properties and packing structure. The gas-slag flow behaviour at a mesoscopic level was numerically visualised, with gas velocity gradually increased up to the flooding point. The strong interaction between gas and slag was uniquely identified, which can cause localised slag flooding as well as gas channelling. Detailed information concerning the effect on slag holdup distribution, residence time and flow patterns of wettability, slag properties and bed structure were obtained. The current investigation highlights the significant role of research at a mesoscopic level in understanding macroscopic slag flow behaviour. Gas channelling, which is a critical phenomenon in a packed bed with counter-current gas-slag flow, is predicted. It can be speculated that significant gas channelling in the BF can inevitably occur prior to operational limits being reached. In the BF process, the formation of permanent gas channelling and large slag rivulets should be avoided to maintain appropriate contact between phases and hence, furnace permeability.

Jun 19, 2024

By K Biegaj, S C. Dominy

A high-nugget effect and presence of coarse gold characterises many styles of gold mineralisation. The effective sampling of these deposits is often difficult because of the relatively low concentrations involved and erratic nature of the gold or other minerals. Geometric and/or metallurgical complexities often compound this effect. Underground development, in-fill drilling and bulk sampling/trial mining are generally required to delineate Ore Reserves. Similarly expensive definition strategies often apply to surface mining in complex orebodies of gold and other minerals, including precious stones. Development, particularly winzing is a historical technique that was used to gather geological, grade and metallurgical data during underground and near-surface exploration. It permits access to the mineralised structure below the surface datum to determine viability. Winzing has always been considered an arduous and dangerous task. Modern winzing technology has led to the development of the Mobile Supersucker – essentially a giant vacuum cleaner with underground and surface capabilities. By the elimination of shovel-loaded blasted winze material into a kibble and hoisting, this system permits safe and highly efficient winzing activities, and allows the collection of bulk samples for grade and metallurgical evaluation, as well as access to the mineralisation for geological and geotechnical mapping. Bulk samples from horizontal development have long been collected to help define mineable grade via pilot processing. However, when defining blocks below current development, there has been over-reliance on ineffective ‘small sample’ drill data. The Mobile Supersucker permits the development of winzes and off-winze sub-levels. These provide critical information to a mine technical team when trying to justify capital to go deeper or commence or deepen an existing open pit. CITATION: Biegaj, K and Dominy, S C, 2018. Lowering risk in complex mineralisation: application of mobile supersucker development, in Proceedings Complex Orebodies Conference 2018, pp 113–115 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

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

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

Oct 10, 2016

By R H. Knight

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

Sep 20, 2017

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

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

Mar 15, 2021

By R Wynn, T J. Akroyd, C Costa

In an environment of lower zinc prices, falling revenues and reducing zinc feed grades, Century mine implemented a fast-tracked capital upgrade program in less than 15 months. The program was designed to increase ore milling throughput capacity by 20 per cent and optimise the capacity of the flotation plant to increase zinc recovery by approximately 2.5 per cent whilst maintaining final zinc concentrate grade.A key aspect of this program was minimising capital expenditure by better utilising existing capacity and only adding capacity where absolutely required to address critical processing bottlenecks. By gaining an understanding of plant process bottlenecks and future ore blends, and by carefully selecting appropriate technologies for particular specific flotation applications, maximum return on minimal capital investment was achieved.The close collaborative work achieved between the metallurgy processing department and other operational departments on-site was also critical to the success of this project. This work increased the mining and processing capacity of the mine and port site respectively, such that the full value of the process plant modification could be achieved.Capital payback on this investment was achieved in approximately three and a half months.This case study demonstrates the extra value to a mining business that can be achieved through fully understanding the mining/processing value chain and by careful targeted action to address critical bottlenecks in the processing chain from the mine through to the port site.CITATION:Akroyd, T J, Wynn, R and Costa, C, 2014. MMG Century Mine, a case study – maximising project net present value through targeted capital expenditure and process optimisation against a backdrop of falling metal prices and feed grades, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 417–426 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

It is difficult to evaluate exploration properties in a manner that is transparent, repeatable and easily re-calculated to cater for different geological interpretations, but the risk-based assessment methodology, the Geological Risk Method, developed and described by Lord et al (2001) attempts to satisfy all these criteria. This paper examines a case study example based on valuations of exploration projects conducted by SRK Consulting using this methodology, and describes some of the advantages and limitations of the method.

Jan 1, 2007

By A Calderon, J Harris, M Shi, D Viswanathan, C Ribeiro Duthie, P A. Kirsch

Mineral resource development activities impact the health and well-being of many people, from workers, to families and surrounding communities. In the current environment of corporate social responsibility life-of-mine planning considers that mining activities should be conducted in the best environmentally, socially and economically acceptable way for the entire life of the mine (ie from exploration to decommissioning and closure). In this context, the health impacts of mining extend throughout the life of the community from worker injury and chronic exposure to communicable and non-communicable causes of illness, through to family and community health and well-being. At the inaugural Life-of-Mine conference in July 2012, the authors proposed the life-of-mine in the life-of-community (LOMLOC) matrix as a framework for understanding issues at the interface between resource extraction operations and the surrounding environment.This paper reviews and compares health activities extracted from social and environmental reports published by selected major mining companies with American operations in Canada, Colombia and Brazil. These corporate approaches to public health management are mapped to the LOMLOC matrix to identify and compare trends and behaviour in corporate health investments. This analysis of how companies approach and prioritise health issues in the context of different regions, cultures and environmental drivers will serve as a resource for minerals industry managers, civil society and regulators regarding current health management approaches in this sector.CITATION:Ribeiro Duthie, C, Calderon, A, Viswanathan, D, ?Shi, M, Harris, J and Kirsch, P A, ?2014. Resource company investments in health – a life-of-mine / life-of-community perspective across America, in Proceedings Life-of-Mine 2014 , pp 349–364 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By S S. Kanchibotla, E J. Sellers, L Julian, A Musunuri

Fume events in coalmines are typically associated with wet conditions, soft ground and deep holes. An ACARP research project used laboratory and field testing combined with literature reviews, numerical models and field investigations to characterise the influence of these conditions on the propensity for fume. This paper highlights the results for soft ground and wet conditions and proposes a proactive fume mitigation methodology. A simple numerical model is used to show how fume arises in soft rock that yields more under the loading of high-pressure, water-resistant explosive blends than for ANFO. The blends cool more rapidly after detonation into the lower temperature zone favourable for NO2 production. Low-pressure, high detonation temperature explosives are loaded or charged into soft ground. Water resistance must be considered because soft, faulted and fractured ground can lead to fume from degradation by water flow and non-ideal detonation of product in cracks.A suite of tests were developed to quantify ANFO and emulsion blend performance over time that can be carried out in a mobile laboratory on-site. Index tests such as viscosity measurement and water resistance in beakers are proposed to quantify long-term product performance because small components, such as surfactant, prill impurities and prill fines, contribute to inconsistent product performance. Water ingress experiments and detonation tests aligned with field investigations identified and characterised the role of groundwater in damaging ANFO and causing fume.Fume risk management is achieved using a proposed proactive fume mitigation methodology to characterise influences such as seasonal rain variation, groundwater flow hydrogeology, rock mass strength and structure well ahead of blast design. The design of blasts and selection of explosive products to consider expected conditions will reduce fume, improve efficiency in the mine and offer cost advantages.CITATION:Julian, L, Musunuri, A, Sellers, E J and Kanchibotla, S S, 2015. Mitigation of post-blast fume in soft ground and wet conditions, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 511–518 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By M Dalm

More and more mining companies are becoming aware of the potential benefits of sensor-based ore sorting and process optimisation. This is reflected by a growing number of analysers that are available for drill hole logging, conveyor belt scanning, ore sorting, slurry analysis, etc. These tools all rely on a specific sensor technology that can be used to detect a material property such as colour, density, mineralogy, or chemical elements. However, all sensors have restrictions on the minerals and/or elements that can be detected or inferred. This is caused by the physical mechanisms behind the technology and depends on mineral concentration and compositional heterogeneity of the ore. Since nearly every ore deposit is unique in composition and characterised by different geological features that drive heterogeneity, no one-size-fits-all sensor solution is available. This makes it difficult for mining professionals to find suitable sensing technologies that can help them solve problems and improve processes for their specific ore types.

Sep 1, 2024

By T G. Neville, G Terrey, J Burns

This paper explores recent industry training programs and lessons for supervisors. The Belbin Team Role model was used to increase participants’ awareness of behaviour and its application. The application of the Belbin model to underground, open cut mine and quarry supervisors is discussed.The key to team success may rest with the expertise and experience of its members, but increasingly effectiveness depends on how team members understand, acknowledge and support each other’s behavioural strengths. Discovering strengths is a challenge, both for their measurement and for the encouragement of team members to use the knowledge of themselves and others in the team. Using behavioural models provides a constructive approach and a language for supervisors as they build personal motivation and engagement.Prima facie, the mineral industry’s work may be too vigorous for teams and their managers could be more prone to use ‘solo’ or traditional management styles. Managers and supervisors must know when work allocated to a team is appropriate or where individual effort should be applauded and rewarded. For practical people with well-developed technical skills, improving the soft skills necessary for a supervisor requires some reflection and effort. The Belbin behavioural model can be an effective tool for recognising characteristics that can assist teams to be more productive.Experiencing the Belbin Team Role model as part of an industry qualification is important for supervisors studying to refine their team leadership skills. Data are available for participants to assess the nature of their teams and to confront the appropriateness of the behavioural mix for the work of the team and its individual members.So what are the next steps? All team development must have a place in the strategic thinking and plans of the enterprise. This needs a visible presence of senior managers and supervisors in managing a team culture with practical links to workplace priorities and professional development with continuous improvement.CITATION:Burns, J, Terrey, G and Neville, T G, 2016. Supervisors and teams at work, in Proceedings International Mine Management Conference, pp 125-138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By M I. Roberts

Corporate and workplace culture, as many owners, directors, executives and managers know, is by far the most powerful determinant of productivity. It’s much more significant than buildings and equipment. Yet although no one today would build a building or machine without a plan, few leaders have a plan for building and sustaining a safer and more productive culture.Using practical ways, culture can be planned and shaped as desired. Success requires implementing a project plan for changing the systems that drive behaviours that in turn shape attitudes. The combination of behaviour and attitude together with leadership largely shape culture.To improve performance, leaders need to:1. improve the organisational systems that drive behaviour2. action a project plan for improving specific performance metrics 3. demonstrate leadership that is conscious, disciplined, committed and passionate for purposeful use of human energy.This paper explains all three factors in practical ways with operational and corporate examples. It details understanding and applying the power of fundamental statistical analysis tools to recalibrate, focus and drive proactive leadership that takes responsibility for process improvement, supporting people and ensuring accountability.Experience and practical understanding of human and organisational behaviour confirm that the Measurement ? Analysis ? Reporting system combined with conscious leadership is by far the most powerful driver of behaviour. This wisdom produces profound changes in leadership style and behaviour. It develops outstanding leadership to create and sustain a safe and highly productive culture reliably producing consistently high quality products. It is the key to developing accountability, employee retention and a sustained competitive advantage.CITATION:Roberts, M I, 2016. Building safe, productive cultures and leadership, in Proceedings International Mine Management Conference, pp 163-178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By M Scoble

This paper addresses the importance of collaborative approaches to resolving future mining challenges. It attempts to provide some insight into understanding the theory, measurement, mapping and management of collaboration. This is related to the design and planning for successful research and educational initiatives. Reference is made to Canadian and global case studies and personal experiences.

Nov 22, 2011

Currently all engineering schools face a common problem, an ever expanding technological base which must be presented to students within a fixed time period. Traditionally the programmes of study taken by engineering students destined for employment within the mineral industry include formal instruction in aspects of management to an extent greater than that presented in other engineering disciplines. Providing an adequate coverage of an expanding technological base within a fixed time span can lead to a reduction in the time available for 'non-technical' subjects, such as 'management'. This situation calls for periodic review of course contents and allocations of time. Following consultation with an Advisory Committee representing the mineral industry, mining research establishments, and kindred teaching institutions, the University of Melbourne has revised its mining programme. This programme is offered as an example of how aspects of management such as communications, economics, labor

Jan 1, 1980

By R Cannings, J Wallace, M McCamley

The mining industry continues to have major disasters (Bingham Canyon, Pike River, Upper Big Branch, Mount Polley and Samarco), which often have a devastating effect on the enterprise, in terms of personnel deaths and injuries, environmental destruction, and financial and reputational loss. These disasters are not imposed from outside the business or organisation, they are almost always a function of loss of control of the management of the organisation’s critical assets and processes that they contain or to which they are exposed.Asset integrity is discussed as an effective response to business risks in order to mitigate, control and recover from loss scenarios that could expose a mining operation to significant property damage and business interruption, or even total loss. Vital to this process is the identification and control of risks to critical assets. Components of a critical asset assurance program are presented for discussion.Formal risk assessment has a longer history in industries other than mining, eg petrochemical, nuclear, military, aviation and space industries. Risk assessment is a structured, proactive approach to understanding and improving risks, as opposed to a reactive ‘fix-it-when-it-breaks’ mentality. Risk assessment techniques were triggered by major public disasters, such as the Flixborough chemical plant disaster (1973), Three Mile Island nuclear plant event (1979) and others.Today, most industries see risk assessment as an inherent part of their business, but do mining sites capture business risks that are related to major loss scenarios, which could have a significant impact on the operation?Does your risk assessment process:- involve a team having the right skill set so that the discussion is both stimulated and technically sound?- use generic assessment when a site-specific assessment is needed?- fail to consider all possible outcomes, including maximum foreseeable loss (MFL)?- fail to identify all hazards and controls associated with a particular activity?- fail to monitor controls effectively?This paper addresses the issues identified by these questions and provides some direction for developing a risk management process where business risk associated with critical asset integrity is integrated with other business and safety and health risk processes to provide a robust method for managing your business. Case studies and common findings from critical asset failures are used to support the need to include critical asset assessments as part of business risk management processes.CITATION:Wallace, J, McCamley, M and Cannings, R, 2016. How robust are your asset integrity management processes? In Proceedings International Mine Management Conference, pp 53-64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By S Robinson, A Turner, R Dale, C Butler

"Sandfire Resources NL- (‘Sandfire’) DeGrussa definitive feasibility study (DFS) identified geometallurgy as a major factor in achieving optimum plant performance at the DeGrussa mine. A geometallurgical initiative was created to proactively investigate this issue, and a key initial achievement was the 2013 paper by Condon et al (2013) on developing a working geometallurgical model from first principles. Significant advancements in Sandfire’s geometallurgical understanding since that publication now shape how information is presented and communicated.The main geometallurgical parameters so far identified as critical factors affecting plant performance are Cu:S ratio, iron sulfide mineralogy, talc carbonate content and sphalerite content. Apart from specific mill strategies, geometallurgical issues have been managed through communication between departments and strategic run-of-mine (ROM) pad management.This paper uses the current theories of geological evolution of the volcanogenic massive sulfide (VMS) deposit at DeGrussa, to discuss the variability between the orebodies C1, DeGrussa (sea floor mounds) and C4, C5 (sub-sea floor replacement) to highlight the different issues each orebody is expected to encounter when processing.A zone of altered low-grade mineralisation surrounds the main orebodies at DeGrussa, referred to as a halo. Talc minerals are often patchy within this halo and often cause significant recovery issues during processing. This halo has been successfully modelled using MgO as a proxy. The ability to model the talc material assists with both identifying potentially problematic zones for processing and geological interpretation of the ore deposits evolution.Early in geometallurgy studies at DeGrussa it became apparent that it would be useful to identify processing performance prior to mining. This necessitated the incorporation of specific sulfide species into the mining block model. These attributes are interpolated from the logged sulfide estimates allowing a clear picture of the abundance of each mineral type within a defined area.In conjunction with the block model a geometallurgical factor (GMF) graph was developed, identifying sulfide mineralogy based upon mineral assays. These two recent additions to the model provide a clear picture of the nature of the ore sources that will be presented to the processing plant.The future of geometallurgy at DeGrussa will see these tools used to aid mine scheduling with a view to further improve processing recoveries.CITATION:Butler, C, Dale, R, Robinson, S and Turner, A, 2016. Geometallurgy – Bridging the Gap between Mine and Mill: a Case Study of the DeGrussa Geometallurgy Program, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 77–88 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By H Tran

Local communities are undertaking an increased role in mine project decision making processes, associated with growing pressure and expectations from regulators, financiers and the general public. This is particularly evident in international projects within developing economies. Environmental and social issues are often complex. Solutions demand difficult choices and trade-offs between sustainable development dimensions: economic growth, social equity and environmental integrity. Proactive stakeholder engagement can play a critical role in assisting decision-makers in determining the operational reality of sustainable development by jointly exploring project trade-offs between proponents and affected stakeholders. Good stakeholder engagement has other potential benefits, ranging from reduced financial risk due to regulator delays, legal disputes or negative publicity to increasing market share through good public image. Approaches to consultation and disclosure have changed from short-term regulatory based focuses, to longer-term, strategic tools for relationship building, proactive risk management and new business identification. Approaches to consultation form a significant opportunity to contribute to overall social sustainability. This paper discusses, based on authorsÆ experience, the broader concept of stakeholder engagement and its contribution to social sustainability of the mining industry. The focus is on key considerations for an effective stakeholder engagement. Three case studies outline how broad based, proactive stakeholder engagement can contribute to improved operation and overall sustainability. The case studies include: a greenfields project in Ghana; a long-term mine in Australia; and an open-pit mine in Vietnam.

Jan 1, 2009

During 2009 the technical services staff at Barrick Gold Corporation's Australian Business Unit conducted a review of their five underground mines that utilise pastefill as the backfill component for these operations. Of the five mines reviewed three use dry tailings and two use wet tailings plants. The primary aim for these reviews was to determine whether pastefill was the right option to be used, and if not, what where the alternatives. The reviews undertaken focus on several areas including, paste plant operation, reticulation and barricade techniques, the geotechnical requirements for pastefill in regards to the current mining methods, the consideration of alternative methods, capital and operating cost histories compared to initial estimates, and a cost benefit analysis of pastefill against other mining methods. The main benefits from the use of pastefill is increasing the extraction of the resource, reducing or eliminating the need to leave pillars. In some mines the use of pastefill is geotechnically driven, to manage high stress environments or mining induced seismicity. A third benefit of using pastefill in some circumstances is that it reduces dilution, however it is considered that this is not a valid argument for most of the mines reviewed. At two mines no alternative to pastefill was determined, whilst differing extraction and filling strategies were potentially identified at the other three mines. The reviews developed cost benefit curves for those sites that had alternative mining methods to assist in determining whether pastefill is the right option to use for any particular stope. At the grades typically mined in each operation, pastefill was the preferred option to use. In all mines, pastefill was determined to be the best option at this time.

Nov 25, 2010

Dynamic Simulation of an Alumina Refinery

Sep 13, 2010

By S Marshall, A Fowler

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

Jan 1, 2008