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By G Baird, M Seto

Reliable evaluation of in situ stress is an important phase in the analysis and design of underground excavations, particularly for evaluating the stability of underground structures to prevent failure or collapse. A technique for the estimation of the full stress tensor based on acoustic emission (the Kaiser effect) is being developed and trialed at the WA School of Mines. The result obtained compare well with the standard over-coring method. The advantages of the technique are that it is relatively cheap, non-time consuming and is applicable to in situ stress measurements at depth in remote regions.

Jan 1, 2002

The cloud transform simulation is a technique used to generate realisations of correlated attributes. The principle of this technique is to partition the scatter diagram between the input attributes into several interval classes and derive for each class a cumulative distribution function (CDF) using only the data pairs of the scatter diagram in that class. The simulation then proceeds like a traditional Monte Carlo simulation but using the derived CDF in each class.The cloud transform simulation has the advantage of being a simple and fast technique that is able to reproduce the uncertainty in the relationship between the two input attributes regardless of whether the relationship is linear or not. However, the technique has three major drawbacks. First, the number of classes has an impact on final simulated results and there is not a robust approach to define such number. Second, simulated results exhibit some saw tooth variations that are unrealistic and third the reproduction of the spatial continuity of the simulated attribute is not guaranteed.This paper presents the use of the quantile regression approach in order to overcome the first two disadvantages of the cloud transform simulation. Details of the technique and how it can be coupled with the cloud transform simulation are presented along with a real case study.

Sep 26, 2011

This report will differ slightly from the traditional scientific and technical discussions given at this type of conference. It will focus on the personal experiences and choices that I undertook when deciding on my graduate position and location after completing university studies. Throughout the duration of my course I had experience in both fly-in, fly-out operations in the Pilbara and residential operations in the West Australian Goldfields. These experiences, though limited, allowed me to explore the two different methods and their pros and cons, and consequently to make my choice for graduate employment. Throughout the duration of my degree I believed it was important to gain a basic understanding of the two methods, focusing on lifestyle and personal interactions. The decision that a residential site suited my personality and lifestyle then allowed me to refine my job applications to a more specific list of mine sites and companies, resulting in a residential position with BHP Billiton at their Iron Ore operations in the Pilbara, Western Australia.

Jan 1, 2005

By A S. Lund

Optimisation of the underground mining production process benefits from informed decision making during the process of explosive rock fragmentation. Selection of the most appropriate bulk explosive products for underground production blasting is an area of endeavour that offers significant economic upside if correctly and thoroughly undertaken. The explosive selection process is facilitated by a clear understanding of:the physical and detonic properties of the alternative explosive options available; the response of different rock masses to these different explosive options; and the importance of maintaining a clear focus on desirable blast outcomes in order to enhance value creation aspects of the mining production process. The level of understanding of these issues is raised through the application of measurement and modelling technology, quantifying the effects of blast design (and implementation) on process outcomes. Homestake Darlot and DynoConsult applied a range of dynamic blast measurement and outcome modelling techniques in order to explore the relationship between rock properties, explosive properties and mining process efficiencies. A campaign of vibration and explosive Velocity of Detonation (VoD) measurement produced feed data for use in vibration and fragmentation modelling during the extraction of one of the major stoping blocks at Darlot Gold Mine. The paper describes the use of these tools and discusses the understanding gained concerning the limitations and capabilities of, and the reconciliation between, a selection of analysis and modelling approaches.

Jan 1, 2001

By E Nettleton, A Melkumyan

Identification of geology and mineralogy in situ on the mine face is essential if mining processes are to be automated for tasks such as exploration, grading and reconciliation. Hyperspectral data acquired from field based platforms are ideally suited to these tasks, and are set to revolutionise the automated mining industry. Changing conditions of solar illumination introduces variation into the hyperspectral signal, which is unrelated to geology, complicating analysis of data. Thus, algorithms must be able to deal with changing illumination conditions and operate in a consistent and probabilistic framework, which is a prerequisite for data fusion with other sensors. To produce accurate classification maps of geology, algorithms must be developed that are effective under different conditions of illumination.The efficacy of three algorithms to classify hyperspectral data for geology mapping on vertical mine faces was assessed. These algorithms are the spectral angle mapper (SAM), and two machine learning methods operating within a fully probabilistic Gaussian process (GP) framework û the squared exponential (SE) and the observation angle dependent (OAD) covariance functions (kernel). Two experiments were done to assess the classification performances. The first determined the performance of the algorithms by classifying hyperspectral data of known rock samples acquired using a field spectrometer. The GP-based methods had a similar performance, with average accuracies and F-scores of 97 and 88 per cent (GP-OAD) and 95 and 81 per cent (GP-SE), respectively. Average accuracies and F-scores for SAM were significantly smaller (80 and 40 per cent respectively). The algorithms were then applied to hyperspectral imagery acquired from a vertical mine face at different times of the day, under very different conditions of illumination. In contrast with experiment 1, SAM and GP-OAD gave results which were superior to GP-SE and were entirely consistent with geology mapped in the field. Compared with SAM, GP-OAD was less sensitive to the effects of shadow and produced classified images that were less noisy. The GP-SE method failed to delineate even gross changes in geology on the mine face. These results show conclusively that in order to use independent training data (spectral library) to classify imagery acquired under a different set of conditions, algorithms must take into account variability in incident illumination. Measures based on spectral distance are inferior to those based on spectral angle.The OAD kernel within the GP framework (GP-OAD) is superior to the other two methods because:it provides a probabilistic framework;it is insensitive to variability in illumination within and between imagery acquired under different conditions; andit can identify and map geological zones on a vertical mine face using an independent spectral library, without a priori knowledge.

Sep 26, 2011

By D R. Seaman, B Adamson, F Burns, B A. Seaman, P Manton

The Telfer concentrator, located in the Great Sandy Desert of Western Australia, consists of a dual train gold/copper operation processing ore from one underground and, currently, two open pit mines with differing mineralogy. The flotation circuit of each train was designed to operate in several modes depending on the feed mineralogy. The majority of ore mined at Telfer is processed in a sequential mode where copper minerals are first floated into a saleable copper concentrate followed by the flotation of an auriferous pyrite concentrate which is treated in an on-site hydrometallurgical plant (carbon-in-leach (CIL)). Gold is recovered as a gravity product within the primary grinding circuit, to the copper concentrate, and to a lesser extent, the CIL circuit.Since Telfer was re-opened, with a new concentrator, in 2004, the processing plant has struggled with poor copper concentrate grades, partially due to the excessive entrainment of non-sulfide gangue minerals in the copper flotation circuit and, more recently, due to composite copper particles produced when processing ore from a supplementary satellite pit that has not previously been processed through the new Telfer concentrator. Gold recoveries in the CIL circuit have also been below industry standard. This paper presents the implementation of recent changes made to the circuit to address these performance issues. The reconfiguration of the circuit has involved the installation of the following major equipment items: two ISAMillsÖ in ultra-fine grinding applications (one in the copper circuit and one in the pyrite circuit), two Jameson Cells to improve fine gangue rejection and a bank of 5 + Outotec TC30s to recovery copper and gold from the reground pyrite stream. The equipment was purchased direct from vendors and an engineering firm contracted to design and install the multi-vendor reconfiguration upgrade.CITATION:Seaman, D R, Burns, F, Adamson, B, Seaman, B A and Manton, P, 2012. Telfer processing plant upgrade - The implementation of additional cleaning capacity and the regrinding of copper and pyrite concentrates, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 373-382 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By S M. Stewart

Industry, especially extractive industry, must now give serious attention to the impact its operations have on the natural environment and on the economic, social, and cultural context within which it operates.   While this obligation is statutorily managed, there has been a recent shift towards a culture of self responsibility. Industry is now talking about earning its ôsocial licence to operateö and the importance of maintaining the ôtriple bottom lineö, thus adding environmental and social performance to the usual financial criteria used to measure organisational performance. The social context within which companies operate has also become more sensitive with industry responding to a growing public expectation that it conduct itself in a way that strives for sustainability by operating and developing in a way that meets the needs of the present without compromising the ability of future generations to meet their own needs.   There are glowing accounts of industries engaging and collaborating with the communities within which they are based. In amongst these are also some disasters which result from cultural assumptions, industry created dependencies and the failure to attain community buy-in despite significant investment by the industry involved.   There are also remarkable stories of communities, and action groups within communities, being a significant catalyst for positive change of their natural, cultural and social environment. In amongst these stories there are also accounts of long and drawn out battles; adversarial situations where no one wins; a litany of mistrust, tricks and tactics, with the better resourced party ultimately achieving its primary objectives at the cost of the other (and at the cost of any potential fruitful, mutual relationships).   So what makes the difference in achieving the positive rather than negative outcomes? The answer lies in the way the outcomes are achieved. Building relationships based on good communication, respect for divergent views, mutual understanding, and the development of trust and empathy, makes it possible to identify shared goals and objectives that best meet the needs of all parties.   Research indicates the mining industry is making good progress in developing policy and commitment to community development and engagement but that, ætranslating commitments into improved practices at the site level remains one of the industryÆs toughest challengesÆ. (Australian Government - Community Engagement and Development Handbook October 2006 @ page 49.)   This paper considers the merits of a process of community collaboration and what it has to offer in terms of meeting that challenge.

Jan 1, 2007

By K Muller, T Oosthuizen

Blast exclusion zones are instrumental in protecting equipment and personnel. When there is no constraint in footprint, the exclusion zone can be enormous, practically eliminating the hazard of flyrock. Unfortunately, this may not always be the case and in many circumstances the blast design needs to be altered to suite such scenarios. When a conservative design approach is taken, it could completely eliminate any form of ejection, whether it is from the free face or the bench itself. The degree to which typical flyrock models describe fragment motion through air with ballistic flight equations are not justified when such a high level of control is applied. This paper examines various methods of risk analysis and suggests an approach to be used for controlled blasting.The outcome of principles discussed in this paper can be seen in video form (Mavmedia, 2014).CITATION:Muller, K and Oosthuizen, T, 2015. Should the blast exclusion zone be based on a qualitative or quantitative analysis? A practical implementation conundrum, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 425–428 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By D J. Logan, J Jackson

"As of 1 December 2014, the 2012 edition of the JORC Code requires Ore Reserves to be defined by studies at the pre-feasibility or feasibility level. This paper examines how the pathway for most mining developments is determined in the Pre-Feasibility Study and how a trade-off must be made between the need to make the best decision, the constraints of limited time and resources, and the level of the project’s accuracy and uncertainty in terms of value. Issues considered include framing the scope of the study, planning for robust decision-making and ensuring effective communication between the diverse disciplines within the team.An inherent conflict exists between the immediate value added to a mining business from an increase in ore reserves resulting from a ‘quick’ Pre-Feasibility Study and the long-term value of pursuing a development strategy based on proper investigation and evaluation of the options. Recognition and resolution of this conflict is necessary if a project is to progress into future development stages, both in a timely manner and with the optimal development alternative and strategy.The challenge for project developers and those conducting the Pre-Feasibility Study is to understand what the key deliverables are (ie an Ore Reserve statement, option selection, business evaluation, forward work plan or risks) and how to follow good practice to ensure that these deliver value.CITATION:Logan, D J and Jackson, J, 2016. The pre-feasibility study – big choices, little time, in Proceedings Project Evaluation 2016, pp 122–132 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

During operations, mining and metallurgical processes may generate effluents such as tailings water, acid mine drainage (AMD) and seepage and process acid streams. Depending on the type of ore and the metallurgical process, these effluents may contain one or more toxic compounds (eg acidity or alkalinity, cyanide, ammonia and/or nitrate, heavy metals, total suspended solids (TSS), sulfate) in elevated concentrations requiring treatment before their discharge to the environment or recycle/reuse in the process. Natural oxidation of sulfide minerals present in mining wastes (eg tailings and waste rock) at mining sites may generate AMD, which is characterised as a low pH, high acidity effluent containing heavy metals and sulfate. If generation of AMD cannot be controlled and/or prevented, AMD needs to be collected and treated for neutralisation of acidity and reduction of metals and TSS to meet regulated water quality standards. It is important to note that some of these compounds may persist in run-off from mine sites, even after the mine and processing facilities are decommissioned. Treatment of mining and metallurgical process effluents can be accomplished by means of various physical, chemical and/or biological methods. The mode of process application may vary from the use of either specifically designed, controlled and automated facilities or passive systems. Lime neutralisation and precipitation is the most common method used in the mining industry to treat AMD. To reduce the problems associated with disposal and long-term storage of the resulting sludge, the use of a high-density sludge process (HDS) has become a preferred option. The use of other chemical reagents, waste or by-products from other industries, and biological sulfate reduction methods can also be considered as viable options for site-specific situations. Recently, several passive treatment systems have been designed and successfully operated, even in the cold North American climate. This paper will discuss available options and provide insights for selecting a suitable method for a given situation using case studies from projects conducted by Golder Associates around the world over the last decade.

Jan 1, 2006

By S Dorrington, J Olsen, N Kinkaid

Several studies have been conducted on the economic analysis of mining near-Earth asteroids for resources for use in Earth orbit. While these studies use detailed economic figures of merit, they often use many invalid assumptions in the trajectory design. Factors such as the energy and propellant requirements are estimated with analytic methods, however, the stay-time at the asteroid and the spacing of repeated launch opportunities are not taken into account. The work outlined in this paper attempts to combine detailed trajectory design methods with newly defined economic figures of merit to improve the economic assessment of asteroid mining missions. The study focuses on asteroid 2014 EK24, a near-Earth asteroid with very Earth-similar orbital properties.CITATION:Dorrington, S, Kinkaid, N and Olsen, J, 2015. Trajectory design and economic analysis of asteroid mining missions to asteroid 2014 EK24, in Proceedings Third International Future Mining Conference, pp 281–288 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By J Planner

As Australia’s coal and iron ore export volumes increase to meet international market growth, port terminals, mining operations and rail transport systems can be the source of increased dust emission. Current and future sustainable expansion must minimise dust emission from bulk handling and transport operations located in close proximity to residential areas. Lower level dust emissions can be controlled by operational measures such as water addition to products, and use of water spray on stockpile surfaces. Recent research has shown that higher levels of dust emission can be more effectively controlled by understanding and treating the dust characteristics of each individual bulk product. Application of this research, progressively being applied at Australia’s coal and iron ore port terminals and rail transport systems, is achieving compliance with health standards and minimising dust nuisance effects to an acceptable level.

Nov 22, 2011

Some 50 miles of tunnel have been driven in the Snowy Mountains Area since tunnelling commenced in 1951. Hates have improved progressively due to the know-how of American supervision and use of large matched equipment of modern design.The work has been carried out by contractors, working almost exclusively under schedule of rates contracts. The Authority has maintained active research into tunnelling problems, especially that of support, and this has resulted in considerable economies and improved rates of progress. The contractors also have sought economies both by management and equipment techniques. Ammonium nitrate came into favour as an explosive essentially because of its lower cost, and handling techniques have improved progressively. Rock conditions preclude use of the "Mole" type equipment in its present stage of development, but one contractor introduced the "sliding floor" and this could exert a great influence on future tunnelling methods.Examination of tunnels that have been in service for some time confirmed the quality of the work and endorsed the policy of continued research and development.GENEHALThe Snowy Mountains Scheme provides for the diversion of the Snowy and Eucumbene waters through two transmountain tunnels to the western river systems. These diversions, together with additional regulations provided for waters already flowing inland, will provide an average additional discharge of 1,818,000 ac it per year for irrigation.Furthermore, approximately 6,000 million kWh of electrical energy will be generated annually in power stations with a total installed capacity of some 3,000,000 kW (Fig. 1.).INVESTIGATIONThe aim of investigation work is firstly to collect sufficient information to allow the overall scheme to be planned and then to follow up with detailed information on eachproject. The correct balance for all aspects of this work is a matter for keen judgment, as the tunnels must be planned...

Jan 1, 1963

By R Milton, D Hake, H Sprague

The North Western Sewer tunnel extends over 11.5 km in the North Western suburbs of Melbourne.The $253 million tunnel project provides a critical link in the Melbourne Sewer Network. The existing sewers fail to service the increasing demands of the growing population of the North West regions of Melbourne. This project will protect the environment and improve the standards of service of the existing system. This paper concentrates on Section three of this project, consisting of the final 4 km of the Contract, three access shafts and a cut and cover section of tunnel.Transfield Tunnelling as Head Contractor constructed the tunnel for Melbourne Water Corporation, with Enetech Streamline, formally Streamline Australia, a trading arm of Melbourne Water acting as Superintendent.Excavation of Section three of this project commenced in September 1994 and project completion is scheduled for October 1998. The tunnel passes below the residential suburb of Essendon, through some of the most challenging ground conditions ever attempted to be tunnelled in Australia.

Jan 1, 1999

By T J. Grandfield

Paste fill has been used successfully at Henty Gold Mine for the past five years. It has allowed 100 per cent extraction of the orebody, stabilised poor ground and enabled wide sections and offsets to be mined safely. However, there are a number of inefficiencies in the current paste fill system. These include the low output from the drum filter, the addition of aggregate to the paste to compensate and the trucking of paste from the plant to the portal. These inefficiencies have increased the operating cost of the paste fill system and caused a number of operational challenges such as blockages and increased pipe wear. These challenges have been partly overcome by taking ownership of the paste fill process, improved quality control and better communication. Henty is currently developing two new orebodies, the Mt Julia and the Darwin and has an opportunity to build an efficient paste fill operation. This is likely to be a high density paste system without aggregate, either located above the new orebodies or located at the plant and pumped to the new site.

Jan 1, 2002

By B Beale

Bow-tie analysis is a commonly used tool in the Major Hazard Facility sector to identify, display and control risks that have the potential to pose serious harm to personnel. It is a simple but powerful risk management tool that displays traditional risk assessment outputs as easily interpreted ‘bow-tie diagrams’. These are an effective and versatile communication format that can be applied to any type of risk (eg safety, environmental, assets etc) and as such show great benefit in managing operational hazards in mining.

May 5, 2022

By R F. Cota, C Freeman, A Heberle

"The Lamego mine is an underground gold mine in the Iron Ore Quadrangle in Minas Gerais state, Brazil. The mine produces 48 to 50 koz per annum, as part of the larger Cuiabá-Lamego Complex. This combined unit is AngloGold Ashanti’s largest gold producer in the Americas, contributing with 310 to 320 koz per annum.The mine started production in 2009, utilising cut-and-fill mining methods.A mining method change was trialled in 2014, introducing open stope methods. The key benefits proposed from this change are considered to be: improved safety by eliminating re-entry mining methods reduced mining costs/increased productivity from utilising bulk-mining operations.The results from the trial were encouraging, and open stoping participation expanded beyond a trial.Production from open stope areas reached 180 000 t (40 per cent of total run-of-mine; ROM) in 2015. While the change in mining method resulted in higher production rates, it also introduced a critical issue in terms of stope recovery rate.Average underbreak (unplanned loss of ore) in the larger open stopes reached 21 per cent in 2015. To manage this ore loss, a project targeting higher recovery was structured with three primary components: analyse current performance to define contributing factors (design process gaps, operating practices) investigate corrective actions apply corrective actions and maximise team engagement to ensure changes become standard practice.Within six months of commencement, a range of contributing factors had been identified, and the majority of the associated corrective actions implemented, including increased team engagement to ensure changes were not ‘once off’ actions.The outcomes show a clear reduction in underbreak (average ~12 per cent for 2016), with further improvement opportunities identified. The challenging target is now to achieve a further reduction to 10 per cent underbreak as the average for 2017. The results contributed 1400 oz and additional US$ 0.5 million to the cash generation profile for 2016.CITATION:Heberle, A, Freeman, C and Cota, R F, 2017. Increasing stope recovery in an underground gold mine by using effective analysis, corrective action and employee engagement processes, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 117–122 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 16, 2017

By S C. Dominy

Gravity amenable gold ores are those that after comminution produce liberated particles, composites and/or carriers that can be recovered by gravity separation means. Recovery depends upon mineralisation type and the comminution and concentration method used. Any in situ ore with more than 20 per cent of gold greater than 100 µm in size is likely to have a strong gravity recoverable component. A less traditional approach is where the gold is sulfide-locked and the gold carrier plus any liberated gold is recovered via continuous gravity recovery following fine crushing. Specific tests are undertaken to determine the level of gravity amenable gold within a deposit. The principal methodology is the gravity recoverable gold (GRG) test, which consists of three sequential liberation and recovery stages. For continuous gravity recovery (CGR), the sample is fed over a laboratory Wilfley table to simulate continuous recovery of the gold. Tails from the feed can be progressively re-ground and re-tabled to develop a grade-recovery curve. Primary geology and gold particle size-distribution have a strong effect on the mass of sample required to provide representative results for both tests. Where low-grade ore contains very coarse gold, substantially larger sample masses are required. Experience has shown that GRG and CGR values can vary throughout an orebody, particularly within different geological-grade domains. A testing regime must consider sample frequency and support.

Sep 5, 2011

By V Matousek, A Sellgren, R Visintainer, G McCall

A 4-component model for settling slurry pipe flow has been previously described by Wilson et al (2006) and Sellgren et al (2014) to predict pipeline friction loss (hydraulic pressure gradient) over a range of slurry compositions: from fine to coarse particle size, narrow to broad particle size distribution, and low to high solids concentration. The method applies a weighted average of established pipeline models for various settling slurry flow regimes, according to the volume fraction of solids falling within the applicable size range for each model. Further development of the model was undertaken by Visintainer et al (2017a, 2017b), based on a comprehensive set of laboratory tests in 203 mm (8 inch) and 103 mm (4 inch) pipelines, and it was also adapted to the modelling of slurry pump performance derates. However, this work was all performed with solids having a specific gravity near 2.65, as is typical for many mineral processing and dredging applications. The goal of the present work is to test the applicability of these models for settling slurries having a higher solids specific gravity, as may often be seen in the mineral processing of iron ore deposits. To that end, a test program was carried out in a 103 mm (4 inch) pipe loop using various compositions of an iron ore product having a solids specific gravity of 4.75 and containing both coarse and fine solids. By screening and flushing operations, a range of particle size distributions were created having different proportions of the coarse and fine elements. In all, 19 tests were performed with d50 particle sizes ranging from 50 μm to 3.2 mm and delivered solids concentrations from 10 per cent to 43 per cent by volume. Particle size distributions varied from very narrow to very broad, with d85/d50 ratios ranging from 1.75 to 26. Pipeline pressure gradient and pump performance data were collected and used to test the applicability of the previously developed 4- component models and to propose improvements to the models for the handling of high-density solids.

Nov 8, 2021

By P J. Terbrugge

The concept of vertical pit mining has been developed as an alternative mining method for the exploitation from surface of small, vertical or near-vertical, massive orebodies down to depths of some 200 m, where ore extraction from conventional open pit excavations is rendered uneconomic due to high associated waste:ore mining ratio. Systematic lateral support maintains vertical pit sides, thereby minimising waste mining volumes. Stability analysis techniques have been developed for design of this lateral support, with the support quantum, primarily comprising long cable anchors, dependent upon country rock strength characteristics and pit configuration. Where the cost of support is less than the cost of the comparable conventional pit waste excavation, vertical pit mining becomes an economically viable alternative, additionally providing the benefit of reduced environmental impact and rehabilitation requirements for the mining area. The technique has been successfully applied for the mining of a chrome deposit in Zimbabwe to an 80 m depth, believed to be unique in the world, and a full feasibilty study for a 3000 m2 diamond pipe has been carried out for mining to 200 m depth.

Jan 1, 2000