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By K Mayank, A N. Mainza, I Govender, M Narasimha, A Mittal

In mineral processing industries grinding is the most energy-consuming process. A tumbling mill is an essential grinding equipment widely used for particle size reduction. Power consumption, impact forces and trajectory paths are critical parameters for characterising a tumbling mill to determine grinding efficiency. The effect of lifters and mill speed plays a vital role in such parameters. However, most of the studies ignore the impact of the lifter and do not investigate the effect of slurry dynamics on charge motion. The focus of the present work is to prepare a computational model that can accurately predict the complex multi-phase dynamics of charge particles, air and slurry inside the mill using a model that couples computational fluid dynamics (CFD) and the discrete element method (DEM). The details of impact forces with lifter profiles and mill speed variations will be refined even further using the CFD-DEM coupling approach. The slurry-air free surface is modelled using the volume of fluid (VOF) method, and the charge motion is modelled using the DEM. The phases are coupled using the interface momentum exchange between the charge and the fluid slurry. The coupled model is validated against experimental results from the positron-emitting particle tracking (PEPT) data. The validated model compares the effect of slurry content on charge dynamics with the dry DEM model. The presence of slurry is observed to dampen the tangential and shear contact forces.

Aug 24, 2022

By C N. Hatton, K Ward

Tailings operations are inherently reactive as operations personnel continuously contend with a concentrator reject feed (tailings) transient in physical and engineering properties, which places a constant constraint on capital and operational spending. It requires a unique skill set to manage the prescribed distribution of tailings under unenviable conditions. Enter the tailings operator, an oftenundervalued commodity and untapped resource that can provide benefits beyond the rigors of dayto- day operational support. Experience consistently demonstrates that skilled and committed operators can serve a vital function in the safe construction of a tailings storage facility. It takes a village to raise a tailings dam. An important part of this process is establishing a culture of operational accountability and ownership. Operator development training is nothing new. However, we find that many of the intrinsic operator skills are left unexploited, and an operator's experiential knowledge base and creativity are commonly overlooked and underutilized. With proper training and guidance, these skills can be harnessed, contributing to safe dam operations. Operator engagement, when properly facilitated, provides tangible benefits ranging from improved tailings engineering properties to reduced closure costs. One important benefit is helping transitioning tailings management from reactive to proactive. There are many processes involved in the reactive to proactive transition process. One element of that process includes engaging operators in the tailings management process and facilitating legacy ownership. The core of operational legacy ownership is measured and described using five-stage operator engagement rubrics. Levels of operator engagement are presented with a description of the incremental benefits of each stage. An important part of legacy engagement is providing the tools to operators necessary for managing the tailings. Therefore, the approach identifies specific methods used by operations personnel to control tailings distribution and in-place properties. The end goal of leveraging operator engagement is to facilitate committed ownership and transition tailings management from an inefficient, reactive process to an improved, cost-effective, proactive practice.

Jul 1, 2021

By D Horacek, I K. Sheppard

Ok Tedi is in a period of transition. By 2008 mill feed will consist of higher levels of high-grade but metallurgically challenging skarn ores. Additionally, the Taranaki pit will start production in 2008 along with the start-up of a new pyrite concentrator. Taranaki ores are very high in sulfur. Sulfur is captured in a pyrite concentrate prior to tailing entering the Ok Tedi River. These and other complex scheduling issues will need to be resolved over a critical three-year period. With these requirements in mind, Ok Tedi contracted AMC Consultants to develop a custom version of the Life of Business Optimisation System (LOBOS¬) to assist medium-term production scheduling at Ok Tedi. LOBOS utilities enable Ok Tedi planning engineers to:import polygon-based reserve data (Blast Masters) from MineSightÆs Interactive Planning Tools (IP Tools); graphically construct block sequencing and material flow constraints; edit constraints defining standard scheduling, processing and financial relationships; define dump and stockpile attributes; and assign capacities to production systems, plants, dumps and stockpiles. LOBOS converts Ok TediÆs production scenario into a mixed integer program (MIP) and submits the resulting model to IlogÆs Cplex MIP Solver. The Solver seeks an optimal production schedule that maximises net revenue per mill hour while meeting all constraints. This paper introduces Ok Tedi and its production requirements and relates these requirements to the facilities developed for an Ok Tedi version of LOBOS.

Jan 1, 2007

By D W. Evans

Research into the dynamic properties of ground support elements continues to grow at a global level, given the increasing importance of this field of application within underground hard rock mining. Measuring the mechanical response of such elements under the rapid onset of simulated rock burst loads forms the basis for this experimental work, typically utilising gravitational drop testing methods. This field of research is fundamentally driven by an increasing need for dynamic performance data, given the constant evolution of rock bolting product designs, materials selection, combination testing and specific application needs based on ground types and loading scenarios. A smaller number of globally recognised dynamic test facilities have predominantly lead research within this arena, typically in association with academic institutes, larger industry groups and government research institutes. However, due to the increasing requirement for dynamic performance data, additional facilities have now emerged in order to satisfy the overall demand for test work. These newer facilities are more typically associated with suppliers to the underground hard rock industry, with experimental designs looking to replicate, at least in part, the work of the primary facilities. For standardisation, repeatability and calibration purposes, the cross validation of test data between primary and secondary facilities becomes an obvious and important consideration across this field of research. This paper outlines the development of a new dynamic drop test facility for testing rock bolts, including the structural design and associated high speed data capture system. Based on the utilisation of identical bolt types, material grades, anchoring systems and decoupled ‘free-lengths’, comparative data has been generated to provide cross validation of the new test facility against data generated by a globally recognised primary facility. The cross validation of data provides increasing confidence in the repeatability and accuracy of the new facility as activity continues towards the provision of further experimental test work.

Nov 29, 2022

By C Zschiesche, alam, A Abadias Llamas, A K

An integrated experimental and thermodynamic modelling study of the phase equilibria in the FeOFeO1.5- SbO1.5-SiO2 system in equilibrium with liquid Sb and Sb-Ag metal has been undertaken to develop thermodynamic model of the Na-Si-Fe-O slag system with S-Sn-Sb-Pb-As minor elements based on the experimental investigation of the selected sub-systems. New experimental phase equilibria data at 575–1600°C were obtained for this system using high-temperature equilibration of synthetic mixtures with predetermined compositions in sealed silica ampoules, Fe3O4 basket in sealed silica ampoule, or Re foils, a rapid quenching technique, and electron probe X-ray microanalysis of the equilibrated phase compositions. Experimental results on phase equilibria in the Fe-Sb-Si-O+Sb metal system obtained helped to produce initial set of model parameters in the slag. The primary phase fields of quartz/tridymite/cristobalite (SiO2), 2 high-SiO2 immiscible liquids, olivine (Fe2SiO4), wustite (FeO1+x), spinel (Fe3O4), schafarzikite (FeSb2O4) and valentinite/ senarmontite (Sb2O3) were identified in the binary Sb2O3-FeO, Sb2O3-SiO2 and ternary FeO-Sb2O3- SiO2 systems. Further refinement, particularly the distribution of excess Gibbs energy among the ‘FeO’-Sb2O3-SiO2 and ‘FeO1.5’-Sb2O3-SiO2 interactions, required the study at more oxidising conditions. Oxygen potential was increased using an inert metal (Ag) rather than using the gas flow due to the high volatility of Sb-containing gaseous species. Liquid Ag-Sb alloys with low concentrations of Sb of a few percent were used. At these conditions, the concentration of AgO0.5 in slag was below 1 mol per cent, which had a small effect on observed phase equilibria in the system. In addition, important information on the solubility of silver in slags is produced, which can be valuable when treating electronic recycling materials or primary silver-containing ores through the Pb process. Two main areas were addressed: the spinel-tridymite boundary (40–70 per cent SiO2 in slag) and spinel liquidus near 15 per cent SiO2 in slag. This allowed to deconvolute the separate contributions of the FeO-Sb2O3(-SiO2) and Fe2O3-Sb2O3(-SiO2) systems.

Jun 17, 2024

By G Zhang, I Glacken

Multiple indicator kriging (MIK) has been used in the minerals industry for some decades. As one of the non-linear estimation methodologies, MIK has advantages related to resolving multiple or mixed populations, high variability data and strongly skewed distributions. Applying the MIK methodology requires a lot more effort when compared to other non-linear methodologies, for example localised uniform conditioning. This is due not only to the variogram modelling for multiple indicators, but the validation is also very important because the panel model is fundamental for follow-up work, including the generation of recoverable resources at the local or SMU scale. Apart from this, only a few reported case studies of MIK have documented post-processing of the estimated modelled distribution, representing the probability distribution at point scale at un-sampled locations. The MIK post processing should include the change of support from the point scale to the panel scale, and then the extraction of quantile values from the panel conditional cumulative distribution function (CCDF) for localisation of grades into the SMUs within each panel, based on a ranking estimate marking the SMUs from high to low. In this paper, we present a case study on a gold deposit with the MIK method with full-post processing implemented for recoverable resources. The MIK point estimate was carried out with an indirect lognormal change of support from point to panel scale, and localisation was done with a custom script. The localised uniform conditioning (LUC) method was also applied for comparison purposes. The comparison shows that MIK has advantages compared to LUC when comes to capturing the high-grades, especially when mixed or varying anisotropy is present within the mineralisation.

May 24, 2023

By C S. Kelsey, J R. Kelly

Australia is presently enjoying the fruits of a booming iron ore market. Expectations are that market strength will be supported in the short to medium term by increasing feedstock demands from steel mills, as world economies rebuild post-Covid-19. However, as cost and environmental pressures increase the longer-term market outlook will be dominated by product quality. The ‘flight to quality’ will place increasing demands on direct shipping ore miners as they compete to maintain their standing in the iron ore marketplace. China will progressively disengage from its dependence on Australian imports, leaving miners under increasing pressure to boost product quality and diversify outlets globally. Australia has vast deposits of low-grade magnetite ores located mainly in remote and arid regions of the continent. This paper proposes a dry grinding and magnetic separation process to produce premium concentrate grades from the low-grade ores, to assist in meeting future product quality demands. The premium grade concentrates could be either blended with lower quality direct shipping ores or marketed separately. The proposed dry concentration process involves the pairing of Vertical Roller Milling (VRM), a mature technology widely used in the cement industry, and Planar Magnetic Separation (PMS), a new methodology, which has been developed to the threshold of commercialisation by the private Australian company Cyclomag P/L. Two laboratory prototype planar magnetic separators with field strengths of 1800 gauss and 6000 gauss have been built and tested on a range of magnetite ore types over the past three years. In each case, following grinding to liberation sizes, a combination of roughing and cleaning operations has produced pellet grade concentrates. Vertical roller milling has competed successfully with conventional media milling in grinding cement clinker, limestone and blast furnace slags. A key advantage of dry VRM/PMS processing is its potential adaptability to stepwise modular development, which can minimise initial capital investment, while generating early revenue streams to cope with unpredictable market volatility.

Nov 8, 2021

By C Jacobsen, N Harries

Assessing and managing instability hazards is an essential activity when working with unstable natural slopes and excavated open pit mining slopes. Slope monitoring has become the standard technique for the management of geotechnical risks associated with mine slope instability hazards. In recent decades, a proliferation of new monitoring techniques such as terrestrial radar, satellite InSAR and LIDAR have become standard operational tools, complementing conventional survey-based monitoring solutions. A reliable monitoring system should identify and record incipient anomalous slope movement. Although the most obvious purpose of a monitoring system is safety related, slope deformation and performance monitoring also enhance the understanding of slope behaviour and assists in improving system design and implementation. For a monitoring system to be considered an effective early warning tool, it needs to operate in real-time and should be linked to the mine’s emergency communication systems. Terrestrial radar systems have been developed that can provide near real-time measurements, at a high level of precision and covering broad areas in all weather conditions. This has had a positive impact on the management of geotechnical risks in operational conditions. The technology adoption of RADAR in mine monitoring has significantly progressed in the last 20 years from technology enthusiasts, to visionaries, to pragmatists to conservative users. However, the increasing adoption of RADAR cannot reduce or remove other monitoring techniques that often have important benefits; even if these technologies cannot be used as a real-time operational tool. An increasing awareness on the importance of combining data from different monitoring techniques to develop a holistic picture of all possible geotechnical hazards is a current industry trend. This is proving to be an excellent foundation for managing hazards associated with slope instability in open pit mines, and is only expected to improve with time with the adoption of new technologies based on big data and Artificial Intelligence (AI).

Nov 29, 2022

By L A. Balzan, F Nieuwenhuys

GEOSCAN on belt analysers have been widely utilised in iron ore for nearly two decades. Since the first installations in 2003, the availability of accurate and reliable grade data has become standardised across iron ore mines in the Northern Cape in South Africa, where various streams are monitored continuously to ensure the optimal functioning of plants. Assmang Khumani has been at the forefront of technology adoption, and has implemented 19 GEOSCANs at various locations throughout the plant, monitoring run-of-mine, stockyard feed, beneficiation plant feeds, and products. Over the years, collaborative advances in the technology have allowed for numerous benefits and gains to be made. In recent times, there has been a concerted effort on the development of analysis for phosphorus in the material flows, and based on Scantech’s experience in the phosphate industry, this element has now been calibrated to achieve statistically acceptable and repeatable accuracies for real time analysis of this element on many of Khumani’s GEOSCAN analysers. This paper provides an overview of GEOSCAN use at Khumani, while focusing on the development of phosphorus analysis. A case study of analysis results is presented for a range of analysers that have been calibrated for this element, as well as a discussion on the benefits obtained as a result of this analysis.

Nov 8, 2021

By D Clarke, I Minniakhmetov

This paper describes the application of the SBRE framework to model the Olympic Dam deposit, one of the largest copper and uranium deposits in the world. Geostatistical simulations are the best practice for quantifying uncertainty in the mineral value chain and estimating resources. However, these simulations are currently undertaken on an ad hoc basis in the mining industry due to the high requirements in computing resources and capabilities in advanced geostatistics. The SBRE project provides a standard framework to test, build, and run conditional simulation workflows, which has been applied to the Olympic Dam deposit. Conventional geostatistical methods face challenges when modelling the Olympic Dam deposit, such as non-stationarity, non-linear correlations, and a large number of grid blocks to simulate. To address these challenges, a combination of methods was used, including projection pursuit multivariate transform, trend-residual decorrelation, pluri-Gaussian simulations, and turning-bands simulations. Various tools and applications were used to build the model, including in-house developed applications, Autovariogram software (Varify), and the RMSP python library. All computations were accomplished on the AWS cloud using the EC2-Batch service. The final set of simulations was validated using various methods, such as grade-tonnage curves, histograms, swath plots, and variogram reproductions, as well as validation using historical samples back-testing. The study highlights the importance of an automated, modular, and scalable framework in the development of conditional simulation workflows and describes the learning gained from trials of different combinations of methods and software

May 24, 2023

By E Williams

The role and importance of a well designed test work program during the development of an orebody is often underestimated. A test work program should be tailored to deliver very specific answers to relevant questions. With a clear purpose, the results from the test work program will enhance the outcome of the feasibility study and provide the information required to meet the requirements of all stakeholders. With regard to test work programs there are three main areas that should be considered: orebody characterisation and definition, process flow sheet development and engineering design information.Orebody definition relies on reliable analytical methods to characterise and assess the economic minerals present in the ground. In mineral sands, the physical processing characteristics of the minerals play a significant role in the definition of an orebody. The analytical method therefore has to be customised using a combination of laboratory techniques. These techniques can include heavy liquid separation, gravity separation and magnetic separation and are usually combined with chemical and mineralogical analyses to create a picture of the orebody. During the definition phase of test work programs, an appropriate analytical technique has to be developed to evaluate drilling samples, but also to support the information collected during flow sheet development.Process flow sheet development is usually done once there is a reasonable understanding of the size and variability of the orebody. Selecting the best sample for test work is critical, as any flow sheet design is tied to the specific characteristics of the sample used for development. There are other factors that can improve the outcomes of flow sheet development test work, including the skills and knowledge of the operator and allowing sufficient time to process and analyse the results. Very often this work is conducted under pressure with limited time and resources, only to result in a suboptimal flow sheet. During this phase of flow sheet test work, iterative testing will provide the information required to develop an optimal metallurgical flow sheet. The data collected will provide indicative recoveries and yields that are required for feasibility studies.Equipment specification is often included as part of process flow sheet development. This includes comparative test work between different equipment suppliers, assessment of operating conditions such as the loading to determine the number of processing units required, as well as other design information required such as particle size distributions, density and operating temperatures.While restricting the time and costs expended on test work programs may seem to meet a short term need to meet investor requirements, neglecting to develop a proper framework of the requirements that has to be met in the long-term can lead to significant long-term cost overruns. This is mainly due to a need to repeat test work, or do confirmation test work, as insufficient information was collected during the initial program.

Oct 5, 2011

By K Devencorn

The development of robust, economical transport infrastructure has been identified as a key driver to sovereign economic growth. Notwithstanding the value of undeveloped mineral resources, unless they can be brought to market they are of little value. Within a global context, the continent of Africa probably faces one of the most significant transport driven economic development programs as countries strive to unlock their much sought after resources.The UN’s Africa Review Report on Transport (United Nations Economic and Social Council, 2009) provides an excellent context for the issue facing African countries and the potential for investment in transport to solve many of the intrinsic problems they are confronted with. With little exception, economic development in Africa is very likely to be driven ‘off the back’ of transport development – and more specifically from heavy-haul rail as a means by which economic wealth can be derived from export of the continent’s vast natural and mineral resources to the world. The report found:transport is a key driver of economic development and poverty reduction;road transport is the most dominant mode in Africa;the ‘Cost to Market’ of African goods is hampered by the reliance upon road transport;the cost of road transport is not just economic – 19 per cent of the world’s road fatalities were recorded on African roads;African railways are seen to be disjointed and under-utilised;Africa’s ports are key to export trade - yet only six ports (three in Egypt, and three in South Africa) handle about 50 per cent of the continent’s total container traffic;the cost of transport is increasing making African trade even less competitive; andsignificant negative impacts of Africa’s reliance on road transport – health, and greenhouse emissions.We understand that mining the resource is only part of the solution – it has to be put to market at a competitive landed cost.Most African countries face huge costs associated with transport development and ongoing operation – in many cases beyond their available resources.The Australian rail industry has faced and solved many of these challenges.

Nov 22, 2011

By Q Yang

This paper describes the design and construction of three 7.2 m span access ramp-tunnels to the three level underground car park of the newly redeveloped Top Ryde City Shopping Centre in northern Sydney. The tunnels were to be excavated without significant impact on the overlying Devlin Street, one of the busiest arterial roads in the Sydney metropolitan area and a major link in the Sydney road network. The interpretation of the geological conditions indicated that the tunnels would be driven in a formation of heavily jointed, extremely weathered to fresh Triassic Ashfield shale with some structural features such as dyke, fault and shear zones identified in the available boreholes logs. Both empirical and numerical methods were used to design the tunnels and to predict the ground surface settlements. The design solution, which was influenced by the relatively small scale nature of the work and the current demands on the tunnel construction market, included presupport, initial support and permanent steel fibre reinforced shotcrete (SFRS) lining. The interactions of the driven portals with cut and cover sections and the proposed deep excavation of the new shopping centre were considered at the design development stage and in the construction phase to ensure the safety of the live road. The tunnels have been successfully constructed and are now operational.

Mar 8, 2011

By N Herault

PT Freeport Indonesia recently completed preproduction development and construction of the Big Gossan underground copper and gold mine, located in the Ertsberg mining district of Papua, Indonesia. Production has commenced with an expected ramp-up to full production of 7000 tonnes per day in 2012. The Big Gossan utilises an open stoping mine method with paste backfill.In order to deliver ore to the mill, which sits in a valley above the ore deposit, an underground production shaft and hoisting facility was designed and constructed as the key component of ore haulage. The design and construction of the Big Gossan shaft posed many challenges to the project team. Available shaft design and construction expertise were limited as this was the first shaft of its kind in Indonesia and the project was undertaken during a time of high industry demand for new shaft systems. Construction resources were also limited due to the remote location and competition with existing, producing mines for these resources and skills. The project also taxed the ability of Freeport to provide services and resources to this as well as their other projects.Completion of the Big Gossan shaft was a milestone in PT Freeport Indonesia’s plan to fully transition ore production to the underground environment in this decade.This paper deals with the various challenges faced by PT Freeport Indonesia and shaft contractor, PT Redpath Indonesia, during the construction of the Big Gossan shaft and offers suggestions to improve future shaft projects of a similar nature.

Mar 21, 2011

By V Lawson

Vale’s Sudbury Clarabelle Mill processes Cu/Ni ores from a number of mines in the Sudbury basin in Ontario, Canada. Bulk sulphide flotation produces a copper-nickel concentrate with pyrrhotite as the major diluent. After successful commissioning of the Voisey’s Bay Cu/Ni Mill (VBN) in Labrador, a miniplant campaign on Clarabelle ore with the VBN flow sheet produced a significant recovery improvement over current performance. In 2001, the Mill Redesign Project moved grinding energy into rock/sulphide and pentlandite/pyrrhotite separation and in 2006 Cu/Ni separation was re-introduced to Clarabelle Mill to produce a saleable Cu concentrate. The projects were a great success. What remained was to simplify the Clarabelle flow sheet by introducing the missing components found in the VBN flow sheet. This project known as CORe has evolved through many stages including the mining boom and surviving the 2008 economic downturn and it is scheduled for completion in mid 2013. This paper outlines some of the challenges faced in this major brownfields project – organizational, technical, financial and operational.

Aug 8, 2011

By C Hamilton

Stawell Gold Mines (SGM) is an underground mining operation located in Victoria, Australia. The mining method employed is long hole retreat stoping, utilising up and downholes and artificial concrete pillars. Stawell is currently mining the Golden Gift and Magdala orebodies.Access to the Magdala and Golden Gift deposits is via 6.0 m wide by 5.5 m high declines developed at a gradient of one in eight to one in seven from the surface to a depth of 1500 m, with a planned depth of 1650 m. From the declines, cross cutting drives are developed to intersect the orebodies. Orebodies in the Gift system are discrete lodes which are generally mined from a bottom up centre retreat to minimise geotechnical stresses.Ore development fronts are currently located between 1000 m and 1500 m below surface, with all ore being hauled to the surface using a fleet of 60 tonne underground trucks. With the use of conventional pyrotechnic long period (LP) delays, broken rock of combined ore and waste is thrown 10 m from the face and the materials hauled to the surface. The majority of the mullock from development is consumed in the underground as backfill.With the use of Orica Mining Services eDev™ Electronic Blasting System for Tunnelling, the waste is thrown up to 40 m from the face, while majority of the ore is left 5 - 10 m from the face, effectively segregating ore and waste. This enables significant recovery of gold values with minimal loss and significantly reduced dilution. By using this technique in ore drives with a 30:70 waste to ore ratio, SGM is able to haul 24 000 tonnes less mullock to the surface annually. Resue mining is applied to narrow vein headings and gives a 40 per cent grade increase at the faces as well as increasing the economic footprint of development. This will also contribute to an improved grade profile for the year from 3.98 - 4.16 g/t Au and allow extra capacity for ore haulage from stoping and for milling.This paper describes the application and the successful blast outcomes achieved using the eDev™ Electronic Blasting Systems for resue mining at SGM. Results to date, since commencement in March 2010, have been achieving significant benefits in terms of ore grade as confirmed by geologists grab sample grades. Face advance have also shown improvement with better breakage of perimeter holes giving improved face profile. These benefits are delivering increased productivity and safety performance when compared to other resue firing techniques.

Mar 21, 2011

By K Zunica, A R. Penney

The principles of three-dimensional geological modelling are well understood and routinely used. Sample data is collated and geostatistical tools used to ensure that sample data is suitable for its end use, which is typically a block model that is appropriate for mine planning. What has become increasingly apparent is that physical rock properties and geotechnical parameters need to be incorporated into the three-dimensional geological model to create an integrated mine model.The approach to the collection of geotechnical information is not as highly prescribed and controlled as collection of geological data. Commonly, the geotechnical data set is incomplete and inconsistent, with little consideration of what the end use will be by those collecting the data, or how the geotechnical data might relate to the geological data. In some cases, specific geotechnical investigation programs are completed, yet correlation between those programs and previously collected data is rarely undertaken to the same level of diligence as found in the geology field.There are some obstacles that need to be considered when attempting to incorporate geological parameters, such as grade, lithology, and geological domains with geotechnical information such as rock quality designation (RQD), rock mass rating (RMR), rock strength, and geotechnical domains into the same three-dimensional block model. Interpolation or geostatistical estimation methods used for grade estimates might not be appropriate for many components in rock characterisation, particularly search geometries. A number of examples are provided to illustrate issues underlying some of the data collection procedures, and their effects on three-dimensional geotechnical modelling.The example presented attempts to highlight generally observed shortcomings in the collection of geotechnical information, parameters which need to be considered when combining geological and geotechnical data into the same model, and the benefits of having a combined block model from the beginning of a project.CITATION:Zunica, K and Penney, A R, 2014. Integration of geological and geotechnical data for three-dimensional modelling, in Proceedings Ninth International Mining Geology Conference 2014 , pp 291–298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By M Reid, H Arbon

Hillgrove Resources (HGO) commenced open pit mining in 2011 and from 2011 to 2016 the geology team experienced a consistent negative reconciliation between grade control estimated copper (Cu) grade and the mill received grade. For the first four years, despite trialling various grade control strategies, the monthly variance between geology and mill copper grades fluctuated between -5 per cent to -17 per cent Cu metal depending on the style of mineralisation.In 2015, HGO embarked on various measures which resulted in changes to grade control practices under the advice of consultants. These changes to grade control sampling, estimation and block out practices resulted in six to seven months of consistently poor Mine to Mill reconciliations from -25 per cent to -28 per cent Cu.In an effort to mitigate these poor reconciliations the geology team reintroduced the preconsultant block out and geology driven grade control methods. Blockout reconciliations from this point emulated those seen originally from -8 per cent to -12 per cent (Cu per cent). Early in 2016 the geology team introduced conditional simulation for grade control as opposed to ordinary kriging to better characterise the grade distribution, introduced separate estimation parameters appropriate for every zone of mineralisation, implemented a maximum profit function to optimise the selection of ore and waste, and retained the geology driven block out processes. Since March 2016 the mine has experienced consecutive months of positive Mine to Mill reconciliations, the first seen in six years. Year to date the expected copper metal is within 1 per cent of mill reconciled copper metal.This paper will compare the various sampling methods, estimation algorithms and block out procedures from the past six years to arrive at a robust open pit operating procedure applicable for mineralisation with high short scale variability.CITATION:Reid, M and Arbon, H, 2017. Setting new standards at Kanmantoo – effective grade control procedures, in Proceedings Tenth International Mining Geology Conference 2017, pp 401–408 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By G Haywood

This paper presents the evolution of the planning, scheduling and mining practices at the Yilgarn Star underground. The paper will concentrate on the principals of æjust in timeÆ and the impact of such practices on mine planning and scheduling and subsequent development and production. The principals of æjust in timeÆ were developed to minimise the impact of creep and time dependent failure of the ground in the ore and hangingwall zones. These zones are characterised by altered schistose material with inherent weak rock strengths compounded, at depth, by the maximum principal stress of the virgin stress field approaching the UCS of the rock mass. Yilgarn Star underground has and continues to develop the æjust in timeÆ methodology to ensure the continued viability of the mine. The mine continues to use longhole open stoping mining methods to ensure high levels of productivity with minimal dilution and at an acceptable cost of production.

Jan 1, 2002

By B Shi, Y Li, L Ma, F Zhou

Subsurface fires are a common threat to coal mining, as spontaneous combustion of coal can potentially result in gas combustion and explosion. Fire-proof techniques, such as grouting, foam, or colloid injection, are not in a position to function ideally, due to the limited coverage and stopping the extinguishment substance from reaching the fire location. Liquid nitrogen, as a kind of all-submerged fire prevention or extinguishing method, can rapidly extinguish fires, thus preventing gas explosion and minimising extinguishment time. Injecting liquid nitrogen through boreholes is an important way during the period of mine catastrophe. But liquid nitrogen is not effective enough in infusion; technical issues restrict the development and utilisation of liquid nitrogen fire prevention and extinguishing technology. Immediate infusion of liquid nitrogen is usually associated with ‘air slug’ (the balloons and bubbles in the pipeline which hinder the flow of low-temperature liquid), which blocks pipelines for liquid nitrogen injecting. Another issue is that the pipeline tends to be damaged due to freezing, which undermines the injecting efficiency of liquid nitrogen and its application result. In order to solve the problems of the low efficiency and some other related field issues in liquid nitrogen perfusion, the ground–underground high efficiency liquid nitrogen injection technology were developed. Implementation of liquid nitrogen infusion techniques in Chinese coalmines achieved the goals of fire prevention and air-cooling. The technique presented in this paper is efficient in absorbing heat, and consequently, displacing oxygen and combustible gases. Field tests at Rujigou and Yangchangwan Coalmine justified the efficiency of the technique. By using this technique, there was no waste left behind, which may impede the subsequent production. The presented technique is of great benefit to the social, economic, and environmental aspects of mining operations, and will have broad applications in fire prevention for large-scale coalmines.CITATION:Zhou, F, Shi, B, Li, Y and Ma, L, 2015. Key techniques and engineering applications of stereoscopic liquid nitrogen infusion for coalmine fire prevention, in Proceedings The Australian Mine Ventilation Conference, pp 291–298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015