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By G Cavanough, A Olsson, J Rock, A C. Torrance

There are various methods currently in use to determine detonation performance of bulk explosive products including velocity of detonation (VOD), high speed photographic analysis, fragmentation analysis and unconfined detonation of samples. For assessment prior to detonation the current practice is limited to a measurement of cup density. This paper presents additional techniques that have been developed to provide measurement and assessment of bulk explosive products. Techniques applicable prior to detonation include a mobile laboratory to allow on-site chemical and physical analysis of sensitised products and ‘in-hole density’ measurement to monitor the in-hole density during sleep time. Assessment of detonation performance is achieved using detonation pressure sensors. These sensors allow measurement of detonation pressure, average VOD, propagation time and magnitude of the pressure induced in the explosive column by detonation of adjacent blastholes.CITATION:Cavanough, G, Torrance, A C, Rock, J and Olsson, A, 2015. Measurement and assessment of bulk explosive products, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 477–484 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By C McCamley

"The requisite for maintaining optimal carbon concentration levels in a carbon-in-leach (CIL) circuit is of paramount importance in the prevention of gold losses. The process’s ability to recover gold from the aqueous phase is primarily dependent on the carbon loading profile of the CIL train.Newmont Boddington Gold (NBG) have over 2015 tested the Mintek online carbon concentration wmeter (C2 Meter) suitability for effective carbon concentration measurements in their CIL circuit compared to the standard method where the readings are taken twice a shift by the operations staff. The C2 meter works by passing a 1MHz ultrasonic signal through a slurry containing carbon where there is a relationship between the carbon concentration and the attenuation of that signal.It also highlighted another area where the C2 meter could be implemented at NBG whereby the instrument can be as a cautionary device for carbon losses in place of carbon safety screens.Citation:McCamley, C, 2016. Continuous Carbon Concentration Measurement at Newmont Boddington Gold, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 207–212 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Jaczkowski B

The lower orebody (LOB) at Chingola Divi- sion of Nchanga Consolidated Copper Mines Limited (NCCM) accounts for approximately 30 per cent of the total copper production for the company. The uniformity of the geology of the orebody lends itself readily to a computer based ore reserve calculation and accounting system. The mining units are physically defined such that a hierarchical type of com- puter file organisation can reflect the existing physical interdependencies. In 1972, a project team consisting of one representative from each of the mine planning, operational research, and computer services departments was formed to investigate and to define the technical mining requirements of the dynamic ore reserve system (DORS). The system was finally implemented in 1975ò

Jan 1, 1977

By W Kendall

Ore sorting has the potential to reduce the feed to wet plants and in the case of complex orebodies that can significantly reduce the water, energy and reagent consumptions and resulting operating costs for the project. The application of ore sorters has sparked renewed interest and application in the precious and base metals mining industry in recent years as a result of the continuing development of new sensing technology and very fast information processing that is making ore sorters applicable to a much wider range of ores and larger scale operations. The application of ore sorters involves a range of trade-off decisions that have economic impact upon the benefits of ores sorting to the project under consideration. This paper will present some typical trade offs to be considered and their impact in a particular project setting. CITATION: Kendall, W, 2018. How economics drive the application of ore sorting, in Proceedings Complex Orebodies Conference 2018, pp 24–27 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

The concept of æsustainabilityÆ can largely be defined as development that will not compromise the ælivabilityÆ of the planet for future generations. It has multiple dimensions, such as the triple bottom line û environmental, economic and social. And it also includes temporal (now and the future) and spatial (local and global) aspects that have to be taken into consideration to achieve true sustainability.Energy sustainability might be defined as û having the light turn on when you push the switch. It has, of course many more dimensions than this simplistic definition. Coal in Australia has an important role in keeping our lights on, but has its problems that need to be tackled head on to maintain a role in sustainable development.An overriding issue in terms of sustainability for coal is its major contribution to our greenhouse gas emissions. Whilst we have one of the most effective energy sectors in the developed world, based on well-managed, abundant fossil fuels, our greenhouse gas emissions are one of the highest per GDP in the developed world. We have to reduce our ægreenhouse gas signatureÆ.This paper explores the issues of coal utilisation greenhouse gas emissions as an indicator of the fuelÆs sustainability and the potential lower emissions pathways we will have to follow in a future carbon-constrained world.The technology changes will have significant implications for the minerals industry and it is argued that forward-looking coal/greenhouse emissions strategies need to be developed in alliance with the coal (and energy) sector for the minerals industry to maintain its global competitiveness.

Jan 1, 2004

By T Y. Dube

In this paper current net present value (NPV) based mine valuation techniques that take into account market and private risk are discussed and analysed. Potential pitfalls that arise from the application of a portfolio, market or commodity based risk metric to a mining project are identified. An alternative non-simulative framework for quantifying and factoring market and private risk in NPV calculations is proposed and then applied to a hypothetical case study in an attempt to overcome identified pitfalls. Mathematical proof that a static discounted cash flow (DCF) calculation can underestimate or overestimate mine NPV is presented, the conditions for each are outlined and the degree of underestimation defined.CITATION:Dube, T Y, 2012. How the use of market-based risk metrics can undervalue good mining projects and overvalue poor ones, in Proceedings Project Evaluation 2012 , pp 29-34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By Q Qu

Reliable prediction of longwall gas emission sources and rate plays a critical role in mine ventilation and methane drainage capacity planning. Over the years, Australian longwall mines have been using the historic Winter method and the Flugge method in modelling specific gas emissions (SGE). The predicted results often experience high discrepancies from the operational reality. To improve gas emission prediction, post-mining gas contents were measured in several mines in Qld and NSW by safely drilling core holes into the longwall goaf. The results revealed many new insights into gas emission characteristics from different coal seams and the drawbacks of the European methods in their use in high-production gassy Australian longwall mines. Based on measurement data, a new, time-dependent gas emission prediction model has been developed. Considering several factors such as caving, desorption and production rate, the new model can predict more accurate and meaningful gas emissions to meet today’s needs in mine gas emission management. A case study is provided to demonstrate the application of the new SGE model.

Oct 12, 2022

Rio Tinto Iron Ore (RTIO) manages eleven mines in the Pilbara region, Western Australia. Three of these mines have previously or are currently mining black shale that contains varying amounts of pyrite. Several new deposits currently being evaluated and existing mines that may progress below water table in the future, will also encounter this waste material. The black shale presents not just an acid rock drainage risk but also a spontaneous combustion risk. This paper presents the black shale management strategy and provides an overview of the relevant activities undertaken by RTIO. The strategy can be divided into two components which firstly involve defining the risk and secondly involve managing the risk. The mineral waste management plan is used to identify specific mineral waste hazards by:geochemical characterisation of waste material,undertaking mine site specific risk assessments,characterising the receiving environment,identifying sulfidic boundaries in geological and mining models,quantifying the amount of sulfidic material in medium and long-term mine plans, anddesigning and sequencing black shale waste dumps. Once a mine exposes black shale the Spontaneous Combustion and Acid Rock Drainage management plan is used and the major activities are: regular site meetings with a representative from every group that works with black shale;compliance with safe working procedures for site specific and detailed activities;regular training;the use of specific explosives to prevent premature detonation;ongoing geochemical characterisation;acid water management, monitoring and analysis;regular internal and external auditing of procedures and practices; andclosure planning assessments and preparations (ie cover trials, geochemical void modelling, geochemical waste dump modelling). The success of this holistic strategy is evident by the awareness of personnel within the business, thorough understanding of the geochemistry and by undertaking proactive management of black shale during mining. The strategy and management plans adopted by Rio Tinto Iron Ore have activities that other mine sites with potentially acid forming material may like to consider implementing.

Jan 1, 2009

Aitik, a Boliden owned and operated open pit mine located in northern Sweden, will expand production from 18 Mt per year today to 36 Mt per year copper ore during 2010. The challenge for the mine operation is to double production with a planned increase of the shovel and truck fleet of only 50 per cent. This will be achieved through improved shovel and truck utilisation and productivity. In early 2005 Aitik started projects to enhance the utilisation of truck engine hours and to reduce fuel consumption. Both projects were successful, within a year efficient2 utilisation of engine hours increased from 60 per cent to 75 per cent and fuel consumption was reduced by six to eight per cent. The truck utilisation project focused on minimising idle truck hours by for example four operators on three trucks thus reducing idle engine hours to minimise lost time for breaks and shift changes. Other measures included focusing on improved dispatch usage, parking trucks when overtrucked, etc. Eco-driving was a project together with Swedish Road Administration with the objective to combine economical and environmental savings. To keep the focus on eco-driving a reward was set up for the shift team with the lowest fuel rate over rolling 15 weeks periods. Both activities included a comprehensive training program for mine foremen, dispatchers and truck operators focusing on efficient use of trucks from economic driving to optimised truck dispatching and minimising idle engine hours. Online monitoring of trucks activities and fuel consumption combined with continuous reporting gave shift foremen and management a tool to discuss and follow trends and individual shift team performance. The combination of close monitoring of mainly organisational practices and operator training resulted in significant productivity increase and lower operating costs without any capital investments.

Jan 1, 2007

By R Strand, L Reading, G Keir

A major challenge in managing coal seam gas (CSG) water is predicting how much water will be produced as the industry develops. Klohn Crippen Berger Ltd (KCB) was commissioned by the Queensland Department of Natural Resources and Mines (DNRM) to develop a tool to forecast where, when and how much CSG water will be produced in the Surat and Southern Bowen Basins under various industry expansion scenarios.The water production tool (WPT) uses the Theis equation, a non-equilibrium groundwater flow equation that accounts for the effect of pumping time on well yield in confined aquifers, to predict water production volumes. Where multiple pumping wells are in close proximity, the required pumping rates for coal seam depressurisation are reduced. Therefore, pumping effects are projected spatially to assess interference effects between wells. Water production is then upscaled to the projected scale of the CSG industry within the Surat and Southern Bowen Basins.Two modifications were made to address the dual phase nature of CSG extraction (a transmissivity reduction factor) and the impact of weathering at the eastern margin of the Surat Basin (a ænear edge effectÆ factor). These factors modify relevant hydrogeological parameters in a consistent and defensible manner to more closely match observed water production.The WPT was verified by comparing results to equivalent Theis equation calculations and to type curves provided by CSG proponents. Calibration was achieved by varying the spatial distribution and intensity of the near edge effect factor in conjunction with a chi-squared analysis of residuals.The tool, which is now being maintained and further developed by the Centre for Water in the Minerals Industry (CWiMI), was built to balance numerical complexity against relative flexibility and simulation speed. The result is a tool that can produce statistically relevant results of prescribed scenarios to plan water handling and treatment requirements in discrete zones of operation.CITATION:Strand, R, Reading, L and Keir, G, 2013. Water production simulation tool for coal seam gas operations in Bowen and Surat basins, in Proceedings Water in Mining 2013 , pp 311-320 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By T Purvis, J Calverd, A-K Greve

The Ernest Henry Mining (EHM) underground mine is situated adjacent to the Great Artesian Basin in North Queensland and within a fracture zone. Underground development commenced in February 2008 and has extended to approximately 1000 vertical metres below the surface.Groundwater has been encountered in numerous locations throughout the mine, predominantly on the eastern side of the orebody and often related to fault structures. Most of the groundwater encountered has been managed with conventional pumping systems; however, on occasions large water inflows have been encountered, which have had a significant impact on the planned development of the mine. Some of the intersections encountered had the potential to compromise the mine from a combination of high temperature (over 45°C), high pressure (3500 kPa) and high flows (50–100 L/s).This paper describes three case studies where significant water inflows were encountered and then controlled by the injection of cementitious grout into the rock mass. The case studies are the 1650 mid-shaft heading, the 1325 shaft access decline and the 1625 to 1475 fresh air rise (FAR) raise bore. Each case study includes a brief description of the event that occurred and the grouting equipment and techniques developed to enable mining to continue.The paper also describes the development of a hydrogeological map of the mine, the probe-hole regime used for high-risk headings and the required processes and systems to inject both cementitious grouts and polyurethane resin into the rock mass.CITATION:Purvis, T, Calverd, J and Greve, A-K, 2014. Management of high-pressure groundwater in underground development at Ernest Henry Mine, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 217–226 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By M J. Nimmo

extremely powerful tools for building predictive and generative models. ML can be used for building highly accurate regression and classification models. But without careful data science and statistical analysis, a regression or classification model could be highly biased and completely wrong – and we may not even realise. An example rock density estimation task will be used to illustrate the potential gains and possible pitfalls in using ML and AI in Mineral Resource estimation. What could possibly go wrong? Nothing! For most simple regression or classification problems, very little. For density estimation, using the global mean may be all that is possible, but the resource classification would need to reflect the uncertainty in global estimation of tonnage. Everything! From data collection and measurement, from selecting ML and AI techniques and designing the analysis workflow to our own cognitive bias. The things that could go wrong are vast and may include but not limited to asking the wrong question, not asking questions, data bias, measurement errors, insufficient data coverage, not collecting the right variables, not collecting enough observations, collecting clustered samples, unbalanced data, filtering out data without reason (outliers), clipping data (outliers), relying on automatic feature selection, including irrelevant variables, excluding relevant variables, geological interpretation, changing context, blindly following best practice, splitting small data sets, subsetting large data sets, using the wrong tool for the task, insufficient budget to complete the analysis, not allowing enough time for testing and experimentation (the science), focusing too much on building the model (the engineering), not learning from the data, our assumptions, our preconceptions, and our skill. This paper will explore the question of how training regression models to predict rock density are affected by gaps in the data (missing observations and missing variables). What could possibly go wrong?

May 24, 2023

By I M. Platten

Narrow reef gold deposits are generally less than 4 m in width and relatively complex geological phenomena. They often display variable geometry, attitude, continuity and internal architecture. Economic grades are mostly restricted to specific structural domain(s) and localised within discrete ore shoots that have a nuggety internal grade distribution. On account of the often extended history of geological events, the specific factors localising gold-rich domains are likely to be unique to a particular mine or even reef. These features lead to a high resource risk and require careful management during both evaluation and mining. The gross form, location and global continuity of gold reefs can generally be determined from surface diamond drilling leading to the definition of Inferred Mineral Resources. It is likely that for the definition of Indicated and Measured Mineral Resources underground development and/or close- spaced diamond drilling will be required. Understanding geometry and continuity permits the resource to be more effectively managed, lowering risk/uncertainty. This in turn will allow for well-informed financial and operational decisions. Most importantly, project expectations and milestones can be set at achievable levels.

Jan 1, 2008

By O N. Savassi

A rigorous methodology for prediction of flotation plant performance is presented, which is based on a standardised batch flotation test called the MFT. The work is part of the FLEET program, developed by MinnovEX with the support of seven large mining firms. The methodology is divided into three key steps: direct measurement of the kinetics of true flotation in the pulp, independent of hydraulic entrainment and other froth effects in the batch cell; benchmarking of the industrial plant over a broad range of ore types and operation conditions; and model calibration to describe froth effects in the plant, with a minimal number of parameters. To date, the methodology has been applied with success at several industrial plants, encompassing copper, gold, nickel, iron, lead, zinc and coal operations. This paper includes a description of the laboratory testwork procedure and scale-up to full industrial circuits. Examples of industrial application are also presented.

Jan 1, 2005

By B Taylor

The Perseverance deposit is the most southerly known economic copper/gold deposit within the Cobar gold field. The deposit is situated approximately 12 km to the south-southeast of Cobar and is essentially blind to surface with the top of economic mineralisation occurring 750 m below ground level.Based on the December 2010 resource estimate (inclusive of reserves and net of depletion) the deposit contains 3 011 000 tonnes at 6.1 g/t Au and 0.90 per cent Cu (590 000 oz of gold and 28 000 tonnes of copper). The deposit is comprised of four principal lenses, the Perseverance, Hulk, Zone B, and Hercules lenses. In excess of 90 per cent of the known resource tonnes are contained within the Perseverance and Hulk lenses. The deposit is shear related and hosted within lower Devonian rocks of the Cobar Basin. The competency contrast of rhyolites juxtaposed against sediments by the Peak-Perseverance shear is the principal control on mineralisation. Both the Perseverance and Hulk lenses are primarily hosted by brecciated rhyolites juxtaposed against Chesney formation sediments across the Peak-Perseverance shear. This faulted rhyolite sediment contact roughly defines the global orientation of the deposit. The Perseverance lens continues within the shear for up to several hundred metres beyond the extent of the faulted rhyolite sediment contact. Mineralisation within the shear beyond the faulted rhyolite contact zone is hosted by sheared silicified sediments. The Perseverance lens remains open at depth and to the south.The Zone B and Hercules lenses, which are significantly less important in tonnage terms, are hosted by rhyolite breccias within the main body of the rhyolite and appear to be only tenuously related to the Peak-Perseverance shear. Within the Perseverance lens, the presence of northeast trending high grade breccia veins developed oblique to the north-south trending shear system has led to the development of steeply north plunging high grade ore shoots within a globally north-south trending mineralised domain. These high grade shoots have limited horizontal continuity but significant down plunge extent.The presence of coarse gold and the resulting strongly skewed nature of the gold grades, in conjunction with controls on mineralisation which are not parallel to the mineralised domain, has led to predictive difficulties regarding stope performance.Strong heterogeneity of the gold content of the ore and geological controls on mineralisation which are not parallel to the global trend of the mineralisation impose a set of difficulties which sound geological control is helping overcome.

Aug 22, 2011

By M Oyarzún

Direct relationships between rock texture and BWi (grindability index) have been established based on geological and metallurgical information supported by optical microscopy observations, gathered from 731 samples.Each recognised rock texture is observed to be related to a certain BWi range and, this texture is also characteristic of distinct lithological subunits (recognisable at mapping scale). Therefore, this relationship may provide an important tool for early milling in situ estimation.Since each textural type is a response to rock formation conditions, the causality of the relationship between BWi and texture is based on such conditions and, particularly, on the interfacial free energy among its components.According to the abovementioned textural features, the greater the free interfacial energy between mineral components, the greater the necessary energy required to break its grain boundaries and, consequently, the greater the necessary energy required for milling.If the textural evidence indicates that the rock was able to adjust the shape and/or size of its components – in a natural tendency of all systems to minimise energy– then the necessary energy required to break its grain boundaries will be lower.

Sep 5, 2011

By D P. Murphy, R F. Dewhirst

Traditionally closure has been seen by the Resource sector solely as a green or an environmental issue, focused primarily on the requirement to rehabilitate the site following cessation of production activities. In addition to operational, maintenance and production aspects of processing plant design, future design teams will need to take a more holistic view and consider an increasing number of sustainability issues including safety in design and cleaner production as well as closure itself. Sustainability principles being adopted by industry such as the Minerals Council of AustraliaÆs Enduring Value Framework are now broadening our understanding of closure. While issues around the closure of tailings dams and associated infrastructure have been widely studied, few investigations have looked closely at the implications of closure on the design of minerals processing plants. It is likely that design teams may be able to make a significant contribution to meeting industry objectives by adopting innovative designs which, in addition to meeting production objectives, deliver sustainable and cost effective plant closure outcomes. This presentation explores the opportunity for innovative design of mineral processing plants through the assessment of alternative closure objectives. This assessment specifically looks at current industry standards and statutory requirements, as well as potential risks and opportunities associated with each objective. Alternative design strategies to meet these objectives are discussed.

Jan 1, 2006

By F C. D Michelin

Blast fumes are a significant health risk to underground workers, containing several dangerous gases such as carbon monoxide (CO), nitrogen oxides (NOx) and ammonia. To ensure safe working conditions, workers are not normally allowed to re-enter a mine until the gases are cleared. To predict if gases can be cleared efficiently, simulations can be performed to estimate the gas levels following a blast. For accurate modelling, a calibrated airflow simulation is required in addition to blast-specific parameters such as the yield rate (representing the amount of gas released per kg of explosive) and the dispersion factor (representing how quickly the gases can enter the air stream from the explosive site). Those parameters are not easily determined, as they will vary from blast to blast. Many post-blast gas recordings on mine sites were studied and the correct parameters were determined to ensure an accurate gas simulation. The variability of the results was then analysed and correlation to known parameters is suggested. Finally, recommendations on how to determine the correct parameter are presented.

Oct 12, 2022

By A Sainoki, D Fukuda, K Shioya, C Zhang, M Sharifzadeh, T Yamaguchi, S Saydam, J Kodama, C A. Amagu, Y Fuji

In an open pit mining, ensuring stability of rock slope has been one of the major challenges. As the instability of rock slopes can results in slope failures; consequently, endanger the lives of workers, affect mining operations, and often lead to economic losses. Therefore, it is practical important to study the stability of rock slopes to ensure safe, smooth, and effective mining. The stability of rock slope of about 130 m height at Higashi-shikagoe limestone quarry, which has experienced slope failures four times since 1996, was assessed. The rock mass at the quarry is consists of mainly limestone, schalstein and slate rocks intersected by clay seams of about 70 m thick at footwall of the rock slope. Previously, the effects of limestone excavation at the foot of the rock slope and shear failure due to rainfall infiltration have been investigated. Although clay is widely known to plays a vital role in the stability of slopes in engineering projects including mines, but its impacts on slope deformation at the study quarry are not adequately examined. Therefore, the present study addressed the impact of presence of clay on slope deformation at Higashi-shikagoe limestone quarry by employing both field displacement measurements and numerical simulation. Firstly, surface displacements measured by automated polar system (APS) for over eight years were analysed to understand the overall characteristics of the slope deformation. The measured results show that the displacement gradually decreases with time. The maximum displacement of about 100 mm was observed at middle of the rock slope. Secondly, the effect of deterioration and plastic behaviour of the thick clay layer were simulated using two-dimensional finite element method (2D FEM). The simulated results reveal that the clay exhibited deterioration by water contact and plastic behaviour arising from mining activities at the footwall of the clay zone. Based on the characteristics of the measured and simulated results, it was found that the displacement induced by the effect of deterioration of clay is more noticeable at the north side of the quarry whereas displacement induced by excavation is quite significant at the south side of the quarry if clay behaves as an elasto-plastic material.

Nov 29, 2022

By I C. Carrasco, V G. Mirada, J F. D Domingo, F S. Leite

This paper investigates ore loss and dilution produced by rock movement in bench blasting. A total of four blasts, in which electronic detonators have been used, were monitored in Cobre Las Cruces Open Pit Mine (FQM Ltd) in Gerena (Sevilla, Spain). Rock motion has been obtained in 137 points of the free face and 6 points inside the block. Multiple liner regression has been applied to predict rock motion and estimate ore dilution as a function of hole coordinates, rock contacts, powder factor/hole, amount of explosive per blasthole, burden, spacing, hole length, stemming length, explosive energy, hole row, subdrilling, blast sequence, stiffness ratio, blasthole distance to free face, rock density and Young’s modulus. The model is statistically significant with a determination coefficient over 0.8. Rock motion measurements in 31 more points have been used to validate the model and to show a reduction in ore dilution.CITATION:Domingo, J F D, Leite, F S, Mirada, V G and Carrasco, I C, 2015. Dilution, ore grade and blast movement calculation model, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 71–78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015