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By B E. Hall, J Poniewierski, A J. Hills

Following a review of life-of-asset work at MMG’s Rosebery mine in which a proposal to increase production from 0.8 Mt/a to 1.2 Mt/a was mooted, questions were raised as to the seemingly arbitrary reasoning for the production increase. They included: Did the proposal actually add value? Was the production rate from the mine sustainable? Was it the best identifiable value-adding configuration?A multiple scenario analysis study commenced to model how various cut-off grade values against mill throughput, along with associated capital expenditure, would impact on the potential value of the operation. This was carried out utilising the ‘hill of value’ approach promoted by AMC Consultants.The traditional approach to these studies uses a constant cut-off value (NSR – net smelter return) for the whole mine analysis. This was thought to potentially introduce a large amount of variability to the model as different ore types were thought to have different processing costs and different underground lenses were thought to have different mining costs. With the aim of developing a consistent value measure that would be comparable between the lenses, an alternative measure was suggested for all ore block values in this model, irrespective of lens location.The new measure used was a mine variable value (MVV). This allowed for the variable factors of final metal concentrate production to be removed from the ore value. From a mining point this was the haulage distance from ore source to run-of-mine (ROM). For the mill it was the amount of reagents required, varying based on grade together with the amount of power required for crushing, grinding and tailings handling.From the initial run of the model, preliminary results lead to a conclusion of increased value being gained by either increasing cut-off grade or increased mill throughput rate. The validity of the result was tested using alternative price scenarios, which although changed the absolute value achieved did not significantly change the identified value-adding strategies. The realisation of these value increases identified are however contingent on higher sustainable development rates being able to be achieved mine-wide, higher backfilling rates being able to be achieved and overcoming recognised ventilation constraints. Further detailed studies are being put in place to identify the practicality of overcoming these recognised constraints and achieving the higher-value strategies identified.The ongoing objective of the hill of value model built is to keep the model alive as a life-of-asset planning tool and to continue refining the foundation data, such that various mining strategies can be analysed with increased confidence.CITATION:Hills, A J, Hall, B E and Poniewierski, J, 2014. Mining scenario analysis and mine variable value, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 111–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Y Zhu, D J. Williams, M O’Neill, C Zhang, X Lei

A cover of inert material overlain by topsoil is required over compacted, seawater-neutralised red mud, a waste product from the refining of bauxite to produce alumina. The cover is to be revegetated, and it is necessary to demonstrate that the potential evapotranspirative-driven uptake of salts from the seawater-neutralised red mud will not impact the revegetation. An instrumented column was designed and constructed to test the evaporation-driven uptake of salts from compacted red mud into an overlying cover material with a thickness limited to 600 mm. The PVC column is 1.2 m high, with a 200 mm internal diameter. The column is instrumented with up to ten of each of moisture, suction, salinity and temperature sensors, together with a data logger, designed and manufactured at The University of Queensland (UQ) in Brisbane, Australia. The sensors were installed through the wall of the column at various depth intervals, with each set of sensors located at quarter points around the circumference of the column. Two pressure transducers were installed in the column to monitor the change of water level due to rainfall and evaporation. The column was filled with compacted red mud to a depth of 600 mm overlain by 600 mm of cover material, both sourced from the Queensland Alumina Limited (QAL) site in Gladstone, Queensland, Australia. The column is installed on a building roof at UQ, alongside a weather station, and will be subjected to the prevailing weather conditions for up to 1 year in the first instance, during which time the weather conditions and sensor responses will be continuously monitored. This paper reports on the instrumented column set-up and the early results obtained from the test.CITATION:Zhang, C, Williams, D J, Lei, X, Zhu, Y and O’Neill, M, 2018. Instrumented column testing of salt uptake from compacted red mud into a cover, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 220–226 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By J Wall

The use of electronic detonators in civil tunnelling applications, to reduce vibration in small firings has been successfully utilised for a number of years. As part of the mining industry’s commitment to reducing blast damage during the development cycle in underground mining applications, a series of development blasts using e-Dev™ electronic detonators in a typical mining application was conducted at Resolute’s Mt Wright operations in North Queensland in 2010. Results were based on direct comparisons to the current industry standard of non-electric firings as a baseline, with as many parameters as possible being captured during the trial. Development costs are typically high in most underground mines, especially in capital development headings, which are in waste and therefore of no direct economic value, so by being able to accurately fire to design, costs relating to both ground support requirements and volume of material removed, (and therefore haulage required) can be minimised. A direct comparison of overbreak (ground blasted outside of design) and cast (distance rock thrown from blast) was also made during the trial, as well as close monitoring of the drilling accuracy.

Mar 21, 2011

By K W. Mills, N R. P Baczynski, J Mylvaganam, D A. Prado, M F. Lee, I A. de Bruyn

"This paper presents the second part of a study of the assessment of rock stress inputs on the performance of various new mining designs at the Ok Tedi large open pit mine in Papua New Guinea. Over the years, four programs of rock stress measurement have been completed at Ok Tedi, each providing different interpretations of the in situ field stresses. Details of three of these programs and interpretations are provided in the precursor to this paper, entitled ‘Rock Stresses at Ok Tedi, Papua New Guinea’ (Lee et al, 2014).This paper explains how the various stress interpretations were utilised in the modelling of the proposed new open pit and underground mining excavations, comparing where possible their expected effects on stability. The modelled performance of three specific mine components have been discussed here as case studies, including: the below-pit drainage tunnel, as the floor of the open pit workings is mined down from 350?m above, to within just 75?m above the crown of the tunnel the stability of the 1000?m high slope of the proposed West Wall cutback the proposed sublevel open stoping extraction sequence in the Gold Coast orebody beneath the East Wall, for which only the likely ‘worst-case’ stress regime was used to assess sequencing and stability issues.The benefits of scheduling the collection of detailed rock stress measurements and other input data from a range of different sources at various stages of the projects are discussed.Alternative in situ stress models have less stability impact on open pit slopes than on underground mine excavations.CITATION:de Bruyn, I A, Baczynski, N R P, Lee, M F, Mills, K W, Mylvaganam, J, and Prado, D A, 2014. The application of rock stress inputs to stability assessments at Ok Tedi Mine, Papua New Guinea, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 43–54 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

By G van Niekerk, M Wortley

Screening is a critical part of many mineral processing circuits and keeping the aperture of the screening media within specification is vital to ensure efficient performance of the processing plant. Typical ways of estimating and/or measuring the wear of the screening media vary from very subjective methods (for instance, using the human eye) to manually checking the width of a few of the more severely worn gaps with a measurement device. Subjective methods can be flawed by human error while manual checking can distort the polyurethane or rubber materials that are used in several types of screening media. All of these errors can cause either premature replacement of panels or, even worse, poor screening of the material.Metso Process Technology and Innovation (PTI) and Metso Screening Media Solutions (SMS) have developed an innovative method that measures screen aperture using advanced image processing techniques. Field trials of the device are presented in this paper, which shows the comparison between the different methods of measuring apertures. Case studies demonstrate how the system, when combined with ScreenTrack, MetsoÆs industry leading maintenance system, and screening media, is providing users with the best possible screening solutions.

Sep 26, 2011

By P Wahyono, H Vega, S Riza, P Vergara, P Gonzalez-Carbonell

PT Freeport Indonesia (PTFI), operating in the Ertsberg Mining District in the Province of Papua, is developing the Grasberg Block Cave copper-gold mine. The site aims to output 160 000 t/d and will be located underneath the current Grasberg Open Pit. Initial studies of the potential to develop a block cave mine in the Grasberg orebody have revealed that the mine will require significant volumes of air. The Grasberg Block Cave (GBC) project requires four primary fans (3750 kW each) to support production at full capacity.Fan #1 commissioning was accomplished successfully on 9 February 2012. However, Fan #2 chamber, which is separated by a 20 m pillar, had not been completed. The main challenge was Fan #2 chamber still needed to be benched. The risk of damage to the critical infrastructure in Fan #1 chamber, including ground support, cracks in pedestals, and misalignment in the impeller shaft were considered. The challenges were blasting the bench without damaging the surrounding infrastructure, completing the work safely and meeting the schedule. This was achieved with the engineering control methodology. This paper summarises the benching process of Fan #2 chamber and its impact upon Fan #1.CITATION:Vega, H, Riza, S, Gonzalez-Carbonell, P, Wahyono, P and Vergara, P, 2013. Excavating an underground primary fan chamber that is adjacent to a fully operational primary fan in PT Freeport Indonesia's Grasberg Block Cave Mine, in Proceedings The Australian Mine Ventilation Conference , pp 115-122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By S Q. Zhao, J H. Wei

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Xitieshan lead-zinc deposit is located in the north margin of the Qaidam Basin, Qinghai Province, China. It is one of the largest massive sulfide deposits in China and is supposed to be of the sedimentation-exhalation (SEDEX) type. Based on the main ore mineral and sulfur isotopic compositions in sulfides found in the wall rock, the S of the deposit is considered to originate from the mantle, but the fluid potentially mixed with sea water during the hydrothermal circulation exchange. The study of lead isotopes shows that the metallogenic material is characterised by the mixture of orogenic and upper crust sources. The lead isotopic signature of the wall rock is similar to that of the ore, which shows synsedimentary characteristics. According to the composition of the rubidium and strontium isotopic signature, the value of 87Sr/86Sr is lower than the average value of that in the crustal rock, which is larger than that of the mantle. Hence, the metallogenic materials of this deposit mainly originate from the crust, which is related to materials of volcanic rocks activation and migration of the deep hot circulating water. The process of the metallogenic fluid circulation shows continuous interaction with crustal material and lead to continuous enrichment of the ore forming fluids. From the study of the fluid inclusion microthermometry of the ore and the associated minerals combined with the C, H-O, Si isotopes, it is believed that the metallogenic fluid is mainly coming from the mantle or the deep magma chambers. The rising deep fluid then mixes with the sea water. The carbon dioxide escaping and mixing with sea water during the hydrothermal exhalation process leads to the rapid precipitation of the hydrothermal fluid to deposit metal. That is proposed as the principal formation mechanism of the Xitieshan deposit. Further studies are proposed, including obtaining geochronology data from this deposit.CITATION:Zhao, Z X, Wei, J H, Liang, S N and Zhao, S Q, 2015. Advances in research on metallogenic mechanisms for the Xitieshan sedimentation-exhalation lead-zinc deposit, Qinghai Province, China, in Proceedings PACRIM 2015 Congress, pp 487–494 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By E Lima, D Gregory, C Faria, A Lapworth

Open pit mine enterprises are complex systems that depend on multiple parameters such as mineral grade distribution, geotechnical characteristics, economic conditions and engineering requirements, all of which vary in time and space with a different degree of uncertainty. The unpredictable nature of these inputs imposes a risk to mine owners and shareholders which in the worst case can lead to highly undesirable financial outcomes.Desktop studies commonly examine a set of scenarios based on adjusting variables such as commodity prices, mining costs, processing costs, and metal recoveries to understand their relative impact on the economics of a project. It is less common to systematically explore and simulate hundreds of alternative physical designs to understand and compare the financial risk associated with one or more mining projects.This paper presents a risk assessment tool set and methodology that uses web based cloud computing to enable multiple simulations of mine designs to be rapidly and efficiently executed. The methodology includes generating random sets of prices and costs values within their respective probability distributions. Pit designs are then created to maximise the profit for each set of input variables. Various approaches to analysing the results are discussed. Use of the same high performance computing environment for understanding the financial risk associated with the variability of the underlying geological resource model is also discussed, with provided examples using case studies from two of the major mineral producers.CITATION:Lima, E, Gregory, D, Lapworth, A and Faria, C, 2014. Simulating extraction shapes to understand financial risk using high performance computing, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 351–360 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By P Esteves, J L. Bechir, R Galery, C Senna, V Souto

The current moment experienced by the mineral industry is marked by a series of economic, social and environmental challenges. Among the main challenges, it is important to highlight the decreasing in ore grades with the gradual depletion of the existing deposits, the high volatility in international commodity prices and the operational inefficiencies in the mine, beneficiation, and metallurgical plants. In this context, mining companies are continuously looking for alternatives that minimize production costs and maximize overall production. In addition, recent tragedies involving tailings dam collapses in Brazil, reinforced the need for a more responsible, sustainable, and conscious mining, such as aiming the preservation and rehabilitation of the land environment. In this scenario, the Sensor-Based Sorting (SBS) technology is currently getting more space into the mining market. This separation technology aims the removal of gangue material in coarse particle size fractions, prior to comminution and concentration stages. As a consequence, the technology allows a smaller consumption of energy, water, chemical reagents and other inputs. Moreover, the sensor-based sorting is a dry processing technology and favors the reduction of fine material to be sent to the tailings. The aim of this paper is to provide information regarding the technical and economical evaluation of SBS technology applicability to a zinc silicate mining in Brazil. The project evaluation was performed in two stages: laboratory test work and the execution of a pilot plant. The execution of a pilot plant allowed the technology optimization, quantification of downstream process effects, such as a proper economic evaluation about the technology benefits. Keywords: Sensor-Based Sorting; Particle Sorting; Ore Sorting; Preconcentration; capital expenditure (CAPEX); operating expenditure (OPEX); zinc; comminution; dry processing.

Nov 10, 2020

By E Kasai, D Maruoka, Y Konno, T Murakami

The iron ore sintering process produces approximately three per cent of carbon dioxide emission in Japan because a large amount of coke breeze is used as the main agglomeration agent. Therefore, its suppression has been required. A promising method is to replace the coke breeze with biomass char and iron-bearing materials. In this study, the effect of the utilisation of metallic iron with coke or palm kernel shell char (PKS char) as an agglomeration agent on its oxidation behaviour was examined by a series of experiments using a sintering simulator. The use of PKS char leads to a larger decrease in the pressure drop difference of the sintering bed compared to the case using coke. Furthermore, the oxidation rate of metallic iron was larger in the case using PKS char together than that using coke. It was considered that the oxidation of metallic iron was promoted because the bed-temperature increased at a faster rate and achieved a higher temperature.

Nov 8, 2021

By S R. Pecover

AustraliaÆs opal and sapphire mining industry has fallen from its peak in the 1980s and 1990s into a significant low today. This is not due to exhaustion of the resource, but instead an over-reliance of the Australian miner on achieving a fair price for the gemstone product from offshore middlemen dealers. Gemstone and geological research is also at a low as Federal higher education expenditure has fallen with research institutions relying increasingly on private funding in an environment of restricted autonomy and flexibility for researchers. What little remaining research skills the universities have is being bled into the private sector as a result of the mining boom and encouraged by lower than average academic salaries. Nevertheless, some highly innovative research has been taking place, often by self-funded individuals and retired academics simply with a desire to advance the understanding of the particular branch of science in which they are interested. New models for the formation of sapphire and opal are now beginning to be applied to the exploration for these gemstone commodities. This research, together with well thought out plans for managing the gemstone product through its value-adding steps to the jewellery retail level, has the potential to bring about a resurgence in the Australian gemstone industry.

Jan 1, 2008

By C Muñoz, N Ortega, J Vergara, D Avilés

Mass blasts have been the subject of extensive studies because of their potential benefits in mining operations. However, it has not been possible to advance due to the paradigm that states that the blasts near the designed final wall or to critical structures have to be low tonnage. Another reason is the absence of specialised simulation programs to more precisely determine the influence of the energy released by blasting to the rock mass. There are some studies that demonstrate the possibility of massive blasting that maintain the design of the final slope (Farias and Santander, 2014). It should be noted that these studies develop the concept that the size of the blast should not increase the peak vibration in the rock mass.The study was carried out in partnership with Los Colorados Mining Company. Analysis, reconciliation and wall control for two types of blasts were performed:blasting production: approximately 850 000 t, with special wall control considerationsblasting of approximately 950 000 t over the entire width of the bench.Monitoring systems were used in the near field and far field using examination of holes in order to obtain information to assess the impact on the rock mass and then to compare these to conventional blasting combining production and contour blasting.The results show that for a large blasted volume, production and/or those generated from toe to crest on the bench did not produce more impact in the rock mass than the conventional blasting.The conclusions drawn from this study are:an improvement in the excavation rate of 7500 t/h that is higher than the maximum rates normally obtainedthe peak vibrations of the P wave generated by both blasts did not exceed the peak particle velocity criteria (Vergara and Muñoz, 2014)holes examination indicating no difference in their entire length, in pre- and post-blast reviewover US$2 000 000 savings generated in the year (estimated by the client) (Avilés, 2014).CITATION:Vergara, J, Muñoz, C, Ortega, N and Avilés, D, 2015. Benefits related to applications of a mass blast in open cut mining, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 625–632 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By L Dyer, A Keith, G D. Corder

As mining activity moves to remote and less developed locations globally, a holistic approach to mine development is fundamental for achieving a balance between strong financial returns and corporate social responsibility and transparency. Key inter-related fundamentals such as social licence to operate, life-of-mine operational planning, minimising environmental impacts and, most importantly, attractive investment returns for the mining company all contribute to the viability of any new mining project.However, the typical practice in the mining industry is often to treat environmental and social/community aspects as separate compliance issues that are dealt with at minimum cost and disruption to the project and resulting operation. This often results in less than optimum environmental and social outcomes, and presents considerable liabilities at the time of closure when rehabilitation programs continue to require funding when all revenue has ceased.The five capitals model seeks to identify each of the key contributors to sustainable development as financial, manufactured/physical, social, human and natural to formulate a type of triple bottom line approach balancing these often competing project factors. The SUSOP® sustainability risks and opportunities framework, developed by the mining industry, bases its approach on the five capitals model and proposes an approach that breaks down enterprise silos to identify innovative solutions for life-of-mine sustainability. This framework has been developed with the nature of mining projects in mind in order to produce approaches and outcomes relevant throughout the life cycle from the planning phases, through project design and construction into operation and closure.This paper argues the need for a more holistic approach to the development and operation of mining projects, and presents case studies where a holistic approach has been applied, in whole or part, and discusses the lessons learned from these case studies.CITATION:Corder, G D, Keith, A and Dyer, L, 2014. A capitals based approach – leading innovation in planning for life-of-mine sustainability, in Proceedings Life-of-Mine 2014, pp 499–512 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By C J. Greet, S Jacques

In most instances, the application of high-chrome grinding media results in an increase in the recovery of the valuable mineral(s). The authors have published data from a number of plant-based case studies, which indicate that it is not unreasonable to expect a recovery increase in the vicinity of 1.5 to 2.0 per cent for a copper ore. It is of interest to understand where the increase in recovery is coming from. That is, is the additional copper recovery the result of improved fine particle flotation or is it due to an improvement across all size fractions?This paper aims to answer this question. Laboratory flotation tests were completed using forged steel and a high-chrome alloy on a volcanogenic massive sulfide copper ore. The unsized data indicated that the application of high-chrome grinding media to this ore resulted in an improvement in both copper recovery and copper concentrate grade. A detailed kinetic analysis of both the copper sulfide and gangue minerals was completed that clearly shows that the change to a more inert grinding media produced significant increases in the flotation rate constants (both fast and slow) across all size fractions. It is also possible to observe that the change in pulp chemistry has resulted in a decrease in the flotation kinetics of the -20 micron pyrite, while the coarse pyrite recoveries have increased, presumably because of an increase in the flotation of the chalcopyrite/pyrite composite particles.CITATION:Greet, C J, Jacques, S and Kinal, J, 2014. Recovery-by-size kinetic analysis to determine where metallurgical improvements occur when converting to high-chrome grinding media, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 217–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By J Penman, N Turner, H Liu

This paper aims to present a snapshot of the risk profile for tailings storage facilities within Western Australia by comparing the spatial distribution of known facilities against common geohazards such as cyclonic activity, climate, and peak ground accelerations from earthquakes. The analysis also includes an assessment of proximity to populations at risk including towns and sensitive receptors including significant river systems and wetlands.

Jul 1, 2021

By C T. Senra, A Souza

Increasing fuel prices, unavailabilty and high prices of tyres have imposed tremendous challenges for large open pit operations. Carajßs open pit mines, one of the largest iron ore projects in the world, has been particularly affected due to the high amount of giant trucks operating in this site. On the other hand, environmental constraints push the mining industry towards reductions in fossil fuels, noise and waste generation. As a feasible response to these requirements, an alternative mining method for open pit mining, aiming to reduce or even eliminate the need for trucks has been developed, based primarily on coal opencast continuous operations. This innovative approach for open pits involves the replacement of trucks by fully-mobile crushers, bench conveyors and ramp conveyors. Two different applications have been developed for exploiting waste and ore at Carajßs largest pit, named N4E. To make it possible, mine planning paradigms should be replaced leading to new conceptual design of open pits. This paper shows two case studies (waste and ore conceptual design) carried out at Carajßs mines to anticipate and put forward the future of open pit mining, proving that our industry would be greatly affected by this new way of exploitation, reducing thousands of tons of fossil fuels. Productivities can be enhanced and environmental performance greatly improved. In this approach mine automation can be easily implemented reducing operating costs and man's fatigue.

Jan 1, 2009

By C Dick

Over the past three decades, mining operations have seen a significant increase in the use of contractors for mining, camp management and catering, recruitment, maintenance, power management, and commissioning. More recently contractors have been engaged for stores and logistics, OH&S, environmental, exploration, training etc. In some countries, such as South Africa, the trend is towards total outsourcing of all aspects of a mining operation which is coordinated by the owners’ management team.During the Global Financial Crisis (GFC) more Australian companies considered and/or took on this approach to recruiting for both projects and operations as mining companies were forced to rethink their corporate strategies as commodity prices plummeted to low levels, pushing operations and projects into potentially financially unviable territory.This paper discusses the labour recruitment, commissioning and operating strategy of Western Areas NL (WSA), with the assistance of Independent Metallurgical Operations Pty Ltd (IMO), as it progressed construction, commissioning and operation of the Cosmic Boy nickel concentrator at the Forrestania Nickel Project during and post GFC. The use of IMO contractors allowed Western Areas to mitigate labour cost risk during the uncertainty caused by the GFC and let their management team focus on the task of bringing a new operation into viable and profitable production.

Aug 8, 2011

By A Bennett, S Arndt

Minerals and Metals Group Pty Ltd (Golden Grove Mine) commissioned a comprehensive study of the life of mine using advanced 3D stress modelling. Essential input into the modelling was the proposed mining sequence, itself the culmination of years of planning and geotechnical experience gained in comparing actual performance to predictions. The modelling approach addressed the whole of mine at a scale of 5 km. There were however several magnitudes of scale to address, from the scale of laboratory testing (0.05 m), to drive size (5 m), extraction size (50 m) and stope size (500 m). Scaling was therefore an integral part of the procedure. The constitutive rock properties in terms of peak and post-peak behaviour varied with the scale. At the laboratory scale, the constitutive relationships for all the main rock units were determined in 3D as well as recovering the in situ stress using the rock memory technique, deformation rate analysis (DRA), whereas at the larger scale the properties were varied to match observations.The modelling, using non-linear analysis to account for rock mass yield and peak-residual strength, demonstrated that if the planned extraction sequence and stope geometry had been pursued there was a high probability of large volumes of excess shear stress being released. However, it was not possible to identify whether the excess shear stress (ESS) will release as one large event or many smaller events. The mining approach was to modify the extraction sequence/stope geometry to manage the hazard. This is where the economic advantage can be realised.Alternatively or in combination with further modelling, the volume identified with the predicted high ESS or energy release could be intensively explored for structures having adverse orientation to the stress change and with sufficient areal extent to release the ESS. The microseismic data can be interrogated for the likelihood of a large event to support the hypothesis of a singular release versus multiple releases of smaller events. If the initial planned extraction sequence had to proceed as designed, changes to dimensioned stopes would be recommended for risk mitigation. Mine planning could as an option, modify the sequence and the extraction could then be remodelled.CITATION:Bennett, A, Arndt, S and Dight, P M, 2014. The economic advantages of detailed geotechnical assessments for extraction sequencing, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 243–250 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By J Joy, A Bye, G V. Kizil

This paper demonstrates an application of a recently developed Risk-Cost-Benefit (RCB) Framework to environmental risk management in the mining industry. The environmental application of the RCB Framework as part of an ACARP project (Kizil, Bye and Joy, 2012) involved a thorough selection process with site visits and in-depth discussions with the case study siteÆs environmental management team. Under their guidance, the highest risk of environmental impact at the case study site was identified as æroad subsidenceÆ at the time when the project work was undertaken. This paper presents the unique application of the RCB Framework to examine the risk of mining-induced subsidence and its impact on one of AustraliaÆs busiest highways, with a traffic volume of 38 000 vehicles per day (NSW RTA AADT, 2008). The RCB Framework was employed to assess the optimum group of controls for road subsidence risk management to ensure highway availability while mining occurs. Whilst this paper focuses on road subsidence, the methodology employed can be directly applied to other environmental concerns including preparation for mine closure, rehabilitation planning and waste management. The RCB Framework incorporates mathematical modules which were developed to enable complex yet tightly integrated RCB calculations. The process integrates the risk-control effectiveness assessment to determine that the selected safety initiative is financially beneficial to the mine site and company. This concept has been applied to a number of high-risk mining areas targeting safety, productivity and environmental issues. This paper introduces the five-staged RCB Framework, incorporating the RCB tools RCBGEN (Risk-Cost-Benefit Generator) and RCEMETHOD (Risk-Control-Effectiveness Method), and demonstrates its practical application to the risk management of a road subsidence case study. The case study looks at potential pavement damages, in particular, the occurrence of pavement stepping on the surface of the highway as a result of vertical subsidence. This type of road damage was previously experienced at another major inter-city route while underground mining occurred in the region where the case study site is located. The RCB Framework has been successfully applied to the analysis of the road subsidence case study and determined the risk reduction and financial benefits of implementing a range of risk-controls. User-friendly RCB Charts to provide an aid for decision-making were produced. The value of using the RCB charts to achieve balance between risk, cost and productivity in the decision-making process for risk management has been explained. The case study determined that pavement slots and fibre-optic cable monitoring were relatively low-cost and effective controls applied in the mining industry for the first time at a global level.This paper supports the industryÆs ongoing efforts to manage risk to ALARP (as low as reasonably practicable) and achieve æzero harmÆ by providing a new Framework to more effectively establish the adequacy of controls.CITATION:Kizil, G V, Bye, A and Joy, J, 2012. Application of risk-cost-benefit analysis to highway subsidence due to mining, in Proceedings Life-of-Mine 2012 , pp 197-206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By S Kowalczuk, S V. L Barrett

The potential for adverse surface settlement during tunnelling in soil and rock poses a significant risk to the successful completion of any tunnelling project. Undesirable ground movement may lead to unacceptable level of damage to surface infrastructure, buildings and the environment, resulting in safety concerns as well as causing significant delays and costs to a project. One of the empirical methods which is commonly used to predict surface settlement in the early stages of a project’s development is the volume loss approach as described by Mair, Taylor and Burland, 1996. This method was developed for use in soft ground; however it has also been applied in weathered and soft rock to provide an initial indication of potential surface settlements along a proposed tunnel alignment. This paper presents some initial thoughts on the use of this method in weathered and soft rock and the associated limitations which need to be taken into consideration when interpreting the results. This includes complex weathering profile cases where the strength and stiffness of the ground does not necessarily increase with depth.CITATION:Kowalczuk, S and Barrett, S V L, 2014. Initial thoughts on application of the volume loss approach for estimates of surface settlement due to tunnelling in weathered rock, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 641–646 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014