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By C J. Carr

The Ernest Henry Mine (EHM) is owned and operated by Xstrata Copper and is located in North-West Queensland, Australia. The mine is currently undergoing a transition from an 11 Mtpa open pit mine to a large sublevel cave underground mine producing 6 Mtpa. Due to a number of factors, including geometry of the pit and crusher depth, the decision has been taken to develop a hoisting shaft rather than inclined conveyors.During the feasibility study the strip and line shaft sinking methodology was preferred over blind sinking due to scheduling opportunities and interactions with level development. Other methods of sinking considered included large-diameter raise boring, which was rejected due to concerns relating to centreline accuracy. The strip and line decision was reviewed during the tender process where better than anticipated blind sink advance rates and costs were presented. This in turn enabled the higher cost of the blind sinking method to be justified by a combination of reduced risks including schedule and ground water management. This paper discusses the pros and cons of both strip and line and blind sinking methodologies in the Ernest Henry context including sinking rates and total schedule impacts of the two methods, the key risks associated with each method, cost implications of blind sinking and safety implications of the work methods in general. The paper then concludes with the reasoning behind the decision to change to blind sinking for the EHM shaft.

Mar 21, 2011

By M Gasparon, J Harris, T Baumgartl, D J. Williams, M Edraki, P A. Kirsch, D Rowe

RISKGATE, an Australian Coal Association Research Program-funded (ACARP) initiative, has been designed to assist the Australian coal mining industry in improving minimum standards for safety performance, efficiency, operating practice and training. The online system is innovative in that it is built upon a foundation of industry expert knowledge gathered through action research workshops, which is further supported by a broad array of industry, academic and technical resources. In operation, RISKGATE offers a continuum for knowledge transfer and communication of current practice in risk identification, assessment and management in the coal mining industry. The primary mission of RISKGATE is to focus industry attention on prioritising control management as a way to achieve acceptable risk.A Coal Mine Tailings Dam Module has recently been added to the RISKGATE suite. The key risk, or initiating event, associated with coalmine tailings dams is catastrophic failure of the dam, leading to the release of tailings and water. This can occur due to geotechnical instability of the dam itself or of its foundation, overtopping and erosion of the dam, and piping failure of the dam itself or of its foundation. Coalmine tailings dams are also prone to seepage into the foundation and through the dam, particularly during operation when large volumes of water are discharged with the tailings. The most significant risk associated with seepage is the release of potentially contaminated water to the environment. Contamination can take the form of elevated salinity, acidity and dissolved metals. Run-off from coalmine tailings can cause erosion and can also potentially contain contaminants. Desiccation of the tailings surface can result in dust generation and dispersion.The paper presents the background and context of the RISKGATE project, the need for the addition of the RISKGATE Coal Mine Tailings Dam Module, and a description of the developed module, including the five initiating events considered, their causes and associated preventive controls, and their consequences and associated mitigating controls. This paper concludes with a discussion of the ways in which Australia’s coal mining companies are starting to apply the RISKGATE body of knowledge at their sites, which will flow onto the management of their tailings dams.CITATION:Williams, D J, Kirsch, P A, Gasparon, M, Baumgartl, T, Edraki, M, Rowe, D and Harris, J, ?2014. Application of RISKGATE to coal mine tailings dams, in Proceedings Life-of-Mine 2014 , pp 219–230 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By U Singh

This paper presents the evolution of the studies and strategic plans to extend the life of operations at the Savage River iron ore project in north-western Tasmania. The current Life-of-Mine (LOM) plan for the Savage River operations is based on a series of open pits. Drilling has confirmed high-grade extensions of the magnetite resource at depths that exceed practical limits for open pit mining. Grange Resources Limited, the owner of the operation, is investigating underground options – not only to extend the LOM plan but also to maintain peak production at a reduced operating cost while reducing greenhouse gas emissions into the future. What makes this project unique is that it requires introducing a productive and cost-effective mining method to exploit a challenging geotechnical and geometrical orebody in an area of high rainfall. To support the study efforts, the development of an exploration decline, underground drilling programs, and an exploratory drive excavated into the orebody for geotechnical investigation was key to providing the necessary data for a pre-feasibility study (PFS). This paper describes the pragmatic approach and processes to developing the underground mining options study through data collection and then integrating these options into the open pit plans to optimise an overall strategic plan for the Savage River operations. The learnings for operators from this experience are how the technical and pragmatic approaches were aligned to develop the strategic plans, and the importance of timely investment in gathering the necessary data.

Mar 29, 2023

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 M Chen, G H. Wang, J R. Zhou, P Yan, W B. Lu

Blast vibration analysis is one of the important topics in the control technology of blast vibration damage. Nowadays, blasting vibration safety standards are based on both the particle velocity and the frequency of vibration and they have been adopted widely and internationally. However, the analysis on vibration frequencies is less studied compared to investigations of peak particle velocity. For the vibration induced by a spherical charge in a viscoelasticly infinite rock mass, an expression of vibration spectrum taking into account the damping effect of rock mass is inferred. Then the attenuation laws of dominant frequencies and centroid frequencies are compared theoretically. For the case of cylindrical charge, dynamic finite element method (DFEM) software of LS-DYNA is employed to analyse the attenuation laws of characteristic frequencies. The research demonstrates that, no matter whether it is a spherical charge or a cylindrical charge, there is a local mutation or fluctuation at some distance when the blast proceeds, while the centroid frequencies conform to a smooth attenuation law. Both the multipeaks structures of vibration spectra and the decay rate difference between high- and low-frequency components contribute to the mutation or fluctuation investigated in this study. Additionally, an increase in longitudinally sonic velocity or the quality factor of rock mass produces an increase in the vibration frequencies, whereas an increase in blast source diameter or the rise time of blast load produces a decrease in vibration frequencies from a spherical charge. In borehole blasting, there is a positive correlation between the vibration frequencies and charge diameter, whereas there is a negative correlation with charge length. And altering the initiation plan will change vibration frequencies to various degrees. Finally, theoretical analysis results were validated by the empirical data from field experiments of Fengning pumped storage power station.CITATION:Zhou, J R, Lu, W B, Chen, M, Yan, P and Wang, G H, 2015. A further study on the attenuation laws of blasting vibration frequency, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 673–682 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

The Rio Tinto Iron Ore group currently estimates grade attributes for mineral resources using ordinary kriging (OK). OK produces a smoothed globally unbiased estimate, but does not capture local variability, which can have significant impact on mine planning and scheduling. The dimensions and the multivariate nature of iron ore deposits make point simulations of whole deposits impractical. With a direct block simulation method the size and speed limitations of point simulations can potentially be overcome, resulting in a viable method for capturing local variability and for providing risk measures into the mine plan and schedules. Some iron ore deposits are highly folded (post mineralisation) and require preprocessing using an unfolding algorithm to properly define the continuity parameters and directions of anisotropy before simulation can proceed. Block co-simulation proceeds in unfolded space and since mine planning require a block-model with regular block-sizes; a regular block-model is unfolded first. This paper discusses a block co-simulation approach that can be used to simulate the irregular blocks resulting from the unfolding process. A section of an iron ore deposit is used for testing the block co-simulation algorithm and the simulation results are compared against the Isatis direct block simulation method. Available blasthole data is also used to validate the behaviour of the block co-simulation algorithm.

Sep 26, 2011

By P V. A van der Westhuyzen

Namakwa Sands is a heavy minerals mining and beneficiation business in the Exxaro Sands Division, and operates along the West Coast of South Africa (see Figure 1). The business encompasses mining, mineral concentration, separation, and smelting operations. Inflated commodity prices and increasing operating costs demands greater attention to the management of process performance and the company wide coordination of resources. Consequently, the task of deploying operational/technical skills and budgets into the most appropriate parts of the business assumes great importance in order to increase productivity from its capital assets. The mineral sands industry is under the same sort of economic scrutiny that all other industries find themselves, and as such, Exxaro – Namakwa Sands has taken the strategic initiative to improve overall resource utilisation within the processing steps and to measure the costs associated with obtaining this value.This paper provides details of the successful implementation of a Kelsey Centrifugal Jig (KCJ) at Namakwa Sands to recover primary and secondary zircon products from the wet gravity (quartz) rejects generated and stockpiled at the Mineral Separation plant (MSP).

Oct 5, 2011

Role of Bubbles in the Action of Flotation Agents

Sep 13, 2010

By J Zhou

This paper discusses the implementation of a mixed integer linear programming model for a coal preparation plant. The plant considered consists of primary and secondary heavy media cyclones, hydrocyclones for intermediate fines and froth flotation for the very fine material. The model is designed to optimise the plant settings and product flows to maximise revenues for a given specification for two product outputs. The model can deal with bonus/penalty aspects of the product pricing for products that exceed or fail to meet specification. We report on a model with two separate coal feeds with parallel circuits for the oversize, intermediate and fines streams. The genesis of this model is more than 30 years old but recent improvements in mixed integer programming solvers make a full mixed integer formulation practical. The original model began as an enumeration of cut points with arbitrary rules for product allocation. The product allocation was improved in a linear programming formulation by Gunn (1982) and Sarker (1991 and 1995). Current mixed integer programming capabilities make it possible to replace the enumeration aspects and solve directly as a mixed integer programming problem. The current implementation uses a general purpose modelling language to formulate the model. Open source and commercial mixed integer programming solvers are compared

Sep 26, 2011

By J Channell, G Phillips

"The Chesney deposit, located 4 km south-east of Cobar consists of three copper-gold rich shoots that lie within a larger, copper dominant lode. A fourth gold rich shoot is located adjacent to the main deposit. The deposit exhibits a strong structural control on mineralisation, as brittle deformation during subvertical extension provided the requisite structural traps to precipitate sulfides from solution. It is postulated that the Great Chesney Fault acted as a fluid conduit, conveying fluids to the site of orebody formation. The continual supply of fluids resulted in cyclic brittle deformation when the fluid pressure exceeded the lithostatic pressure and the tensile strength of the Great Cobar Slate.Evidence supports the hypothesis that ore deposit formation was controlled by: a supply of mineralised fluids transported along the Great Chesney Faulta suitable location for the mineralised fluids to accumulate, accommodated by vertical extension and dilation in certain locationsthe creation of suitable structural traps to capture the sulfides. These traps formed as a result of fault-valve behaviour. Understanding the controls on mineralisation enables prediction of the location of other deposits with similar emplacement history, or extensions of current deposits.CITATION:Channell, J and Phillips, G, 2014. Understanding mineralisation controls – a case study of the Chesney deposit, in Proceedings Ninth International Mining Geology Conference 2014 , pp 301–312 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014

Currently an Australian Standard for tunnel fire safety is being developed for road and rail tunnels. Other local guidance relating to tunnel fire safety that has recently become available includes publications by both the Roads and Traffic Authority and RailCorp of New South Wales. Internationally, the World Road Congress has completed its 2004 - 2007 cycle, which has resulted in a number of publications. International developments in rail guidance include a new European Standard regarding fire safety in railway tunnels that will come into effect in July 2008. In addition, the National Fire Protection Association committee NFPA 130 are in the process of revising their standard for fixed guideway transit and passenger rail systems, which is due for publication in late 2009. This paper outlines the status of these and other recently published relevant local and international fire safety guidelines and their implications for tunnel projects in Australia.

Jan 1, 2008

By G B. Ebsworth, J Krokowski de Vickerod

Several drilling programs at Maldon have produced 7790 core samples, which were assayed for gold, with 2825 of the samples assayed for nine other metallic elements. There is a lack of correlation between gold and all other elements. The situation, however, changes dramatically when sorted according to the abundance of arsenic. In the populations where As >200 ppm, there are strong, positive correlations between gold and several elements. There is also a strong positive correlation of Au with the weighted sums and products of all elements with the elemental averages as a weighting factor, and Bi*Sb and Bi*As elemental products. In these populations, there is also a strong positive correlation between the logarithms of Au and logarithms of each element, as well as the elemental sums and products described above. The correlation coefficients increase with higher As cut-off values.All elemental distributions but especially gold show a high-nugget effect and display high skewness and dispersion, low kurtosis, and common outliers. The distributions of their logarithms are several magnitudes less scattered and without outliers. Thus, the logarithmical distribution correlations are best for practical use.Correlation coefficients were T-tested and are statistically significant. The elemental correlations, particularly those of logarithmic values of weighted sums and Bi, could be used as a gold path finding tool at Maldon. After a preliminary assay for gold and arsenic, only samples with As > 200 ppm should be assayed for other elements. Higher values of gold-correlated elements or elemental ratios, in samples with low gold grades, may increase confidence that gold is under reporting due to its highly nuggetty nature.CITATION:Krokowski de Vickerod, J and Ebsworth, G B, 2012. Correlation as a gold path finding tool at Maldon, Victoria, in Proceedings Narrow Vein Mining 2012 , pp 131-144 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By J M. F Clout

The Roy Hill Project is an independent integrated port, rail and mine development in the Pilbara region of Western Australia. The bankable feasibility study for the project was completed in January 2011 by Roy Hill Holdings Pty Ltd, a wholly owned subsidiary of Hancock Prospecting Pty Ltd. The Project will deliver 55 Mt/a of premium quality iron ore to a rapidly growing market with a mine life of over 27 years. This study is based on exploiting a 1.2 Bt bedded resource of microplaty haematite-rich Marra Mamba, from which 562 Mt of reserves has been delineated to date. A further 1.1 Bt resource of detritals and low grade bedded is proposed to be mined once the bedded high grade resource is depleted. Roy Hill lump and fi ne ore products will compete strongly with other Pilbara products. As a low cost producer, Roy Hill is on track to capture four per cent of the global seaborne traded iron ore market. The project decision to proceed is targeted for Q2 2011 to enable first ore on ship by Q2 2014.

Jul 11, 2011

By R M. Arellano, D M. W Harney, M Makhuvha

Mineral resource and ore reserve estimates are founded on two sources of data: tonnage and grade. The tonnage is a product of volume and density; both of which are estimates. Density impacts numerous operational factors, which include, but are not limited to, mine design, mine planning, equipment selection and operational performance. Hence, density is a significant parameter and its determination requires similar care as the measurement of grade. Selecting an appropriate method to determine density, and ensuring its rigorous application, thus reduces risk and can improve operational performance, which in turn increases profit margin.Different Anglo American sites use a variety of practices and protocols to determine density, which is highly dependent on the physical characteristics of the orebody, local conditions and historical practices. Also, individual sites sometimes execute the same method in a slightly different way, which may also affect the outcome of the measurements. In order to gain a better understanding of how density is determined at Anglo American projects and operations, a review of these techniques was undertaken. The objective of the study was to identify and share good practices across the company, as well as to look for improvement opportunities, where applicable. Ten different methods of measuring density, applied to nine different commodities, were identified and described. An additional technique was recently developed by Anglo American Technical Solutions. The core pycnometer is a large gas displacement pycnometer capable of measuring density at high accuracy on full pieces of intact core.This paper provides an overview of methods used to determine density within the Anglo American Group, including quality control and quality assurance aspects. It is not the purpose of this paper to identify a preferred method, but to highlight the importance of choosing the best suited practice for a project or mine site. In addition, a case study comparing two different density determination methods applied to the same rock samples from the Los Bronces Copper mine was undertaken and the results of that study are presented here.Selecting the most appropriate method to determine density and comparing results from two or more techniques against each other, together with other suitable quality control procedures, is considered to be of utmost importance for all mining operations and exploration projects.CITATION:Makhuvha, M, Arellano, R M and Harney, D M W, 2014. Determination of bulk density in Anglo American plc, methods and impacts, with a case study from Los Bronces Mine, in Proceedings Ninth International Mining Geology Conference 2014 , pp 85–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By Emerson J

Drilling has always been one of the most important parts of the exploration process with most companies spending around 25% of their budget on drilling. Although superficially there appears to be little difference in drills and drilling practice a number of major refinements have taken place over the last decade that have significantly changed the drilling scene. One of the most important advances has been in hydraulic engineering giving rise to the Dual Purpose top drive drilling rigs. These have led to significant productivity increases with the high rotation speeds and longer fleets. Downhole technology has also advanced with better hammers, stronger drill rods, impregnated coring bits and improved drilling fluids. Although geologists continue to measure drilling performance on a cost per metre basis, greater consideration is at last being paid to the quality of sample produced. This is particularly the case with RC drilling where quite sophisticated automatic and semi automatic splitting devices have been developed. Drill operators are now required to be experienced in both Diamond coring and air drilling and be better qualified to maintain the more sophisticated machinery. Management of drilling companies or drilling divisions has also had to change to accommodate both the high capital cost of equipment and the demands of keeping drilling a cost effective exercise.

Jan 1, 1987

Correlation of Air Recovery with Thin Film and Froth Stability in Flotation

Sep 13, 2010

Gold rooms represent a high security area and preventing theft is a challenging task. Where gravity concentrates or high value unit intermediate products are present, particular and specific security procedures must be put in place. This paper describes the development and implementation which reflects best practice in gold room security. Procedures involving key holder systems, key locks, swipe cards and double locks preventing any one person having access to the gold room, including specific procedures for gravity gold concentrators, will be addressed. The use of monitoring and how to deal with alarms and potential hold ups will be reviewed. The use of cameras and archival DVD recorders is common in gold rooms. The use of electronic surveillance, movement detectors, seismic monitors and the two person policy and gold room entry procedures are described, including how to deal with visitors. The importance of confidentiality regarding smelting and gold pick-up days, plus strategies employed to minimise storing large quantities of gold on site will be presented. The role of metallurgical accounting in providing quality auditable information and the minimum standards of record keeping required is discussed. The role of the Gold Squad will be outlined. Regular auditing and risk analysis and several case studies are cited where security was deficient or improved.

Aug 1, 2010

By P Audet, D Doley

The mining industry often embraces mine closure criteria that require the reinstatement of predisturbance or even presettlement (ie historic) ecosystems. However, the extent and severity of disturbance associated with most mining activities mean that critical physical and biological characteristics are irreversibly altered. Consequently, it is rare that a reconstructed landscape can support ecosystems even close to the historic condition, and this rarity is reflected in the small number of mine leases that have been extinguished by attainment of such completion criteria. Novel ecosystems are defined as those in which some or all physical and biotic components are irreversibly different from the historic condition. Recognition of the concept of novel ecosystems allows mine closure criteria to be set according to attainable physical and biological conditions that provide safe, stable and manageable environments with acceptable ecological functions. We propose that a landscape that first maximises physical stability and economy yet will provide a range of environments for vegetation communities and fauna habitats that may be very different from those existing prior to a disturbance should be considered suitable alternatives to, eg targeting idealised historic environments. As a result, mine closure criteria should be established by detailed description of the best attainable physical conditions, with negotiated identification and testing of the most appropriate biological systems for the various parts of the reconstructed landscape. As a general practice, revegetation would use native, but not necessarily local species if the new physical environment is not conducive to the survival and growth of local species. These new ecosystems would need to be managed in perpetuity, although the intensity of management might be low if landscape design and engineering are combined with appropriate species introductions. Here, we suggest an abbreviated procedure that may be adapted in light of local conditions and circumstances for guiding decisions influencing the physical and biological properties of reconstructed landscapes that will enable novel ecosystems to meet realistic closure criteria.CITATION:Doley, D and Audet, P, 2014. Changing restoration priorities in the 21st century – opportunities for novel ecosystem design in mine closure, in Proceedings Life-of-Mine 2014 , pp 649–662 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By K Williams, W Chen, J Miller

The flow function of an iron ore material governs its flowability characteristics in material handling chains within the resource industry. A uniaxial compression test is able to obtain a flow function more rapidly comparing to the Jenike direct shear test; nevertheless, the results often exhibit lower rankings using the former method. This study aims to investigate the fundamental stress states within the test specimen that lead to this phenomenon, and to introduce a new uniform density specimen preparation method for a uniaxial compression test, in order to achieve comparative flow functions as for a Jenike direct shear test. The minimisation of the wall friction effect and achievement of the critical state when preparing a uniaxial specimen are explicitly discussed. Experimental investigations on flow functions of a suite of Australian iron ore samples were conducted using both the uniform density uniaxial compression test and the Jenike direct shear test. Results from both methods were found to be comparable, providing the specimen exhibits cohesive flow behaviours. The outcome of this research enabled development of a rapid and reliable flow function testing method for cohesive iron ore materials.CITATION:Chen, W, Williams, K, Roberts, A and Miller, J, 2017. Rapid and reliable flow property testing – a modified uniaxial approach, in Proceedings Iron Ore 2017, pp 149–154 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By A Kitchen

For the past decade, demand for Australian resources has reached unprecedented levels, thanks mainly to the emerging superpowers of China and India. Meeting demand has meant miners and governments alike have ploughed billions into capital expenditure projects for logistics infrastructure such as roads, rail and ports, to support the ever expanding number of mines and mineral volumes. In more recent times, however, the effect of the global economic crisis has led to a decline in demand for Australian minerals. The downturn has seen companies lay off workers in droves, and delay or cancel expansion projects, in an attempt to preserve cash flow. Whilst the current economic cycle has hit the mining sector hard, it is an opportunity for companies to take stock of their existing operations and plan for the future. As mining companies grapple for scarce capital resources, it is inevitable that industry consolidation will ensue. This presents challenges and opportunities for both buyers and sellers alike, looking to expand operations, or sell off assets to raise cash.

Jan 1, 2009