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By J D. Lubben

Hibbing Taconite is a Lake Superior-type granular magnetite taconite deposit occurring within the Biwabik Iron Formation along Minnesota’s central Mesabi Iron Range. The deposit is situated on the northern margin of the Proterozoic Animikie Basin. The deposit strikes northeast, dips gently southeast, and occupies 10 km of strike length. Mining focuses on 50 m of granular cherty and laminated slaty taconite within the Lower Cherty member.Ores generally consist of a quartz, magnetite, siderite, ankerite, minnesotaite, stilpnomelane, and haematite mineral assemblage. Processing is optimised by exploiting the physical and chemical variations that exist between three major ore types. Taconite ore averages 20 per cent magnetic iron (MagFe), 27 per cent weight recovery (WtRec) and produces a final concentrate with 4.5 per cent silica (SiO2). Since 1976, production has totalled approximately 237 million long tons (Mlt) of pellets (8 Mlt per year rated capacity).Ore processing uses a simple fl ow sheet of autogenous grinding (<0.044 mm) followed by two phases of wet magnetic separation, fi ltering, limestone/bentonite addition, balling, and firing to create pellets averaging 66 per cent total iron. A Liberation Index (LIS) is used as a primary guide for ore grading and metallurgical control. Grind requirements, magnetite liberation and silica grade are closely monitored to ensure plant optimisation and product quality.A recent program of benefi ciation of low-grade ores by in-pit crushing and dry magnetic cobbing has demonstrated that low-grade ores (<17 per cent MagFe, <25 per cent WtRec) can achieve a signifi cant metallurgical upgrade (up to 25 per cent MagFe and 40 per cent WtRec). This operation recovers 60 per cent of the total crushed volume, and has a calculated effi ciency factor (magnetic iron recovery) of 79 per cent. This paper discusses the benefi ts of this upgrading and its effects on ore blending and processing.

Jul 11, 2011

By D Cliff, K Bailey

Traditionally occupational health and safety (OH&S) has been managed for the direct benefits of reducing injury and illness to workers on mine sites. In the current skill shortage climate it is important to recognise the value that OH&S management can have in assisting mines in minimising their exposure to this issue. In times of skills shortage turnover is high as mines poach personnel from each other. This leads to loss of corporate knowledge and loss in productivity through the need to train new personnel in mine-specific operating procedures. In addition absenteeism can significantly disrupt production as there may be no ready replacements available for key jobs. Pressure will be placed upon workers to remain at work even though they are not completely fit for work, leading to presenteeism and consequently loss in productivity. In addition to the threats to routine operation, the loss of management and professional staff can significantly increase catastrophic risk through loss of experience and corporate knowledge. There is increased pressure to focus on events that occur regularly in the here and the now and underestimate the rare, or unlikely, events.The theme of this paper is that by properly addressing OH&S management at mine sites, companies can minimise their exposure to these problems. Put simplistically, a safe and healthy mine is a sustainable and productive mine. Case studies and relevant literature will be used to support this premise.CITATION:Cliff, D and Bailey, K, 2012. Health, safety and sustainability, in Proceedings International Mine Management 2012, pp 53-58 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

Faced with low prices and weak demand in an oversupplied market, the Australian coal industry must seek to further reduce its costs. The paper examines minesite competitiveness of the open cut coal industry in Australia with some references to the coal operations of M.I.M. Holdings Limited. The make-up of F.O.R. mine costs is analysed in order to identify where efforts should be directed to maintain competitiveness. The scope for mine site improvements through changes to working practices, the application of new technology and cost management is examined.

Jan 1, 1987

The mIning operations of Bougainville Copper Pty. Limited are located at Panguna on the Island of Bougainville which is part of the Territory of Papua and New Guinea.C.R.A. Exploration Pty. Limited first established mineralization in the Panguna area in 1964. Exploration work since then has established ore reserves estimated to be 900,000,000 long tons of ore assaying 0·48 per cent copper and 0·36 dwt/ton gold. An economic feasibility study completed in July, 1969 enabled a decision to be made to proceed with a major mining operation. The ore will be mined by open cut methods and will be treated in a conventional concentrator with a nominal capacity of 90,000 short tons/day. The concentrate will be pnmped as a slurry through a 16 mile long pipeline to a port established on the east coast where it will be filtered and dried ready for export. Other supporting facilities for the mine include two towns, a 135 MW steam power station, and access roads.

Jan 1, 1971

By A Kleinitz, J Halilovic, K Trappitt

Mine operators use grade control to determine the destination of each block of material in the mine. In polymetallic mines, grades are best expressed in dollars: the Net Smelter Return, NSR, per tonne. To estimate NSRs, geologists working on grade control develop models for each geometallurgical domain in the mine. These models may incorporate observations on the mineralogy and grain sizes of the material being examined. The site’s mill operators contribute to the models by providing geologists with statistical analyses that relate assay results and mineralogical compositions to metallurgical parameters, such as the rates of recovery of each economic metal to each of the concentrates produced, and the compositions of those concentrates. The team responsible for sales and marketing of the site’s products contributes to the NSR models by providing details of the costs of shipping concentrates to smelters and refineries; and by providing figures that are specified in the smelter contracts, such as the payability of the metals in each concentrate and the fees charged by the smelter. The mill operators also provide, for the NSR models, equations to estimate the rates of recovery of deleterious materials to each concentrate. Deleterious materials comprise mostly halogens and amphoteric elements, both of which reduce the efficiency of smelters. Furthermore, deleterious materials such as antimony and arsenic may be poisonous to people and to the environment. The sales and marketing team provide specifics of the penalties that smelters impose upon deleterious materials. These penalties may reduce NSRs by tens of percent, possibly to levels below the cut-off grade. Thus, in the blocks that are subject to grade control, mine geologists monitor not only the concentrations of economic metals, but also the presence and abundance of deleterious materials. The preparation and maintenance of models, to estimate NSRs and to assess changes in the levels of potentially toxic materials to be mined, requires close and continuing consultation between corporate departments. There must be strong communication of mine geologists with the mill operators; with the people who market the mine’s concentrates; and, should there be a risk of encountering toxic levels of deleterious materials, with the mine’s health, safety and environmental officers. This co-operation could require radical changes in the structure of many organisations. However, experience suggests that such changes can significantly improve the profitability of a mine.

Mar 22, 2022

By A Innis, A Bye, B McCarthy, S Glover

Technology adoption in the mining industry has been steadily increasing over the past decade, driven by the need to improve operational efficiency, safety, sustainability, and profitability. As mining companies wish to implement solutions to improve mining safety and productivity, various technologies are being integrated into mining operations to enhance processes, reduce risks, and optimise resource utilisation. Adoption of new technologies such as autonomous trucks requires a strong focus on foundational operational technology (OT) and a systems-thinking approach. OT support is critical however, OT is traditionally not considered or integrated into standard maintenance activities. Consequently, sourcing and applying service support to OT systems in real-time has posed significant challenges to date. Neglecting the monitoring and upkeep of these operational technologies and equipment can lead to a host of adverse consequences. Operating instability becomes more prevalent, necessitating reactive measures, and the vulnerability to cybersecurity threats increases significantly. To address OT monitoring and maintenance challenges, a systems wide mindset and remote support discipline must be utilised. Remote operations support refers to real-time, 24/7 monitoring, control and support of site OT: network, production systems, maintenance systems, enterprise systems and mobile and fixed plant through a single interface remote from site. The presence of a disciplined team, grounded in a systems-oriented approach, is of the utmost importance to remote monitoring, given the intricate interdependencies of OT systems. The ability to understand the relationships among multiple systems, coupled with the capacity to distinguish between symptoms and root causes, assumes a pivotal role in operations. Through diligent monitoring and the astute understanding of system thresholds, remote operations support can actively identify and alleviate constraints, in turn, serving as the enabler for transformative advancements in technology output.

Sep 1, 2024

By G Pattenden, R Hargreaves, P Pettit

"Even with the cyclic nature of mining, when it comes down to it, the bottom line is that whatever direction the commodity market is going there is always a desire to improve the economics of an operation in order to deliver a greater return to investors. Adapting to market pressures by introduction of an operational process change can often have a downstream impact. What may be less obvious is that reconciliation can play an important part in measuring the effectiveness of many operational changes. Through the adoption of best practice reconciliation and related comparisons, it is possible to measure the impact of changes across the mine value chain and identify variability that may have been introduced. Using analytical business improvement tools, examining and monitoring planned changes can be crucial in understanding whether the introduced changes have been effective and whether they have provided the expected result. Using several case studies, the authors will highlight the benefits provided by modern business intelligence tools, which can provide data validation and accurately report data trends related to both planned and unplanned change events.Citation:Hargreaves, R, Pattenden, G and Pettit, P, 2016. Measuring the Effectiveness of Change through Best Practice Reconciliation, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 71–83 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By M Sandy, A Vakili, J Albrecht

Although rock strength anisotropy is a well-known phenomenon in rock mechanics, its impact on geotechnical design is often ignored. No widely accepted guideline currently exists for its characterisation. Anisotropy can significantly control the failure mechanism and progression of damage into the rock mass, particularly in high-stress conditions. As such, it can play a key role in the stability of underground excavations and subsequent geotechnical design.This paper introduces the concept of anisotropy at both intact and rock mass scales. It then presents guidelines for measuring anisotropy and assigning rock mass strength properties. An improved unified constitutive model (IUCM), which can account for more complex failure mechanisms, is then briefly described. This IUCM is used to better understand the typical responses of anisotropic rocks to underground mining and to develop an improved damage classification scheme for these conditions.The application of conventional design methods in anisotropic conditions is shown to lead to significant errors. Two case histories are then presented, illustrating how the proposed methodology can improve the reliability and accuracy of the geotechnical analysis when compared with conventional design methods.CITATION:Vakili, A, Albrecht, J and Sandy, M, 2014. Rock strength anisotropy and its importance in underground geotechnical design, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 167–180 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By A Hughes, S G. Rosin

This paper presents the design and construction approach adopted for the widening and stabilisation of the existing decline tunnel forming part of the Scenic Railway Upgrade project at Katoomba in the Blue Mountains of New South Wales (NSW), Australia. The overall upgrade project included new trains and track, rebuilding of the top and bottom station and installation of a new winch and control system. All the works were undertaken over an eight-month period between August 2012 and April 2013 as part of a $30 M upgrade of the railway.The railway is the steepest cable-driven line in the world at a maximum of 52° extending over 350 m and descending from the escarpment into the Jamison Valley. The track was built in the 1880s for coal haulage and is recognised as a remarkable engineering achievement for its time. The tunnel section extends for about 120 m at the start of the decline and is about 3.5 m wide and 3.5 m high. The tunnel was excavated principally within medium to high strength Banks Wall sandstone and given that the widening only involved about 200 mm of trimming of the crown and sidewall this aspect of the work was not a critical support issue, except at the upslope portal. The tunnel crown however is entirely intersected by a major near vertical shear zone which presented significant challenges for the tunnel stabilisation works.Three-dimensional laser survey scanning was used for definition of the tunnel clearance envelope for the widening, and also to subdivide the tunnel into various geotechnical sections to assist in support design. Specifically oriented rock bolts extending beyond the shear zone into stable rock were used together with mesh, shotcrete and extensive strip drains and flushing points for drainage of the shear zone.Unique aspects of this project were included into the specifications and work methods. This included construction of a mobile working platform for tunnel works, the use of dry shotcrete application, difficult access for rock bolting and limiting vibration during the tunnel trimming works due to the risks associated with crown instability. The works also took into consideration particular safety constraints/work exclusion areas to address the risk of detachment of rock which could mobilise downslope to the track area below. This was required because other works were in progress such as micro-piling and bottom platform works which were being undertaken concurrently with the tunnel work.CITATION:Rosin, S G and Hughes, A, 2014. Scenic Railway Tunnel upgrade in the Blue Mountains, New South Wales – an approach to design and construction, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 607–618 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By M Salu, G J. Kay

"As underground mines increasingly face the challenge of maximising production without losingfocus on safety excellence, the ability to predict the eff ectiveness of mine seals and stoppings andthe identifi cation of defects plays an increasingly important role in mine ventilation management.While technologies for sample testing installed seals provides signifi cant assurance, the difficulty of conducting tests in operational environments, combined with the production impact of destructive testing procedures, has led to the development of a new method for non-destructively testing ventilation control devices (VCDs). This paper addresses the challenges of in situ testing and reviews the approaches previously employed to verify the quality of VCD installations. It then describes a new testing methodology jointly developed by Whitfield Minerals PTY Ltd and Parsons Brinckerhoff (PB) and the range of tests that have been carried out in the laboratory, above ground, at trial underground sites and in active coal mine operations. Although this is a new approach to testing underground VCDs, the method employs recognised testing equipment in a new application. The aim of the new non-destructive technology is to not only verify the thicknessand therefore overpressure rating compliance, of new VCDs, but to allow mine operations t oidentify and locate defects in installed VCDs without causing damage to the material structure.Currently it is difficult, time-consuming and costly to carry out physical sampling and testing ofevery VCD. Therefore, a reliable and accurate means of non-destructively testing concrete andplaster seals in situ will provide substantial operational and safety benefi ts to the underground coal mining industry."

Jun 1, 2012

By R Pozo, F Reyes

Codelco Chile is currently developing the El Teniente û New Mine Level Project (NMLP) in order to increase ore production by seeking to mine the ore deposit located under the current operational orebody. Reserves of 2000 million tonnes (Mt) have been quantified, which will be extracted as from the year 2017 by using the panel caving and progressive sinking method. Codelco and SKM Minmetal (SKM) jointly developed the project prefeasibility stage (PFS), closing these studies in March 2008. The first part of the project approach is to replace mine production currently feeding the Colon concentrator facilities with 137 000 tonnes per day (t/d), focusing attention on a production increase from the year 2026 up to 180 000 t/d. Project efforts have also been centred on maximising the contribution of new technologies for both construction and operational phases of the New Mine Level, together with selecting the best mine infrastructure to keep El Teniente operations going on for the next 50 years. Implicit in this is the inherent improvement of a variety of current Mina El Teniente process and management practices. The plan is to reduce actual mine operational risks and take advantage of new opportunities afforded by the project, which is in effect a greenfield project with respect to the implementation of fundamental changes in the labour and business environment. In addition, issues related to human resources, maintenance and management, materials handling, establishing centralised operations and accesses, automation and remote operations control and power efficiency could also be addressed. The project, beyond the New Mine Level exploitation, considers the mineÆs future potential, with a second deeper exploration in prospect named Deep Level. Finally, the project identifies features that would add value to the mine operations, in an initiative named æSpace for Future TechnologiesÆ. This will allow the eventual implementation of new electrical equipment and the application of mechanised technologies and other process improvements for the mine development.

Jan 1, 2008

By Thomas W

Due to record low tin prices and an uncompetitive position in world markets, the Renison tin mine has undergone three major phases of restructuring in the last three years. This has involved substantial job losses, almost all of which have been through voluntary retrenchments. Retrenchments took place in 1988, 1990 and 1991.The last phase of restructuring was the most dramatic, as many aspects of the operation of the mine were changed. New pay structures were introduced, and the miners' contract system was scrapped. Drastic pay cuts occurred in many areas, although the opportunity was also taken to increase pay at some of the lower levels where inequities existed. Work practices were changed, as was the management structure.

Jan 1, 1992

By Hoffmann CF, White NC, Tedder IJ, Wood DG

Since the discovery of Pajingo in 1984, the northern Drummond Basin has emerged as a significant new gold province, and has become the focus of intense exploration for epithermal gold mineralisation. Prospects in the Conway area are hosted by felsic to intermediate lavas and volcaniclastic rocks near the base of the Drummond Basin sequence. These Drummond Basin rocks appear to represent favourable hosts to mineralisation because they are cut by structures which could have focussed and channelled fluids on a regional scale, and because they constitute a possible source of gold and, perhaps more significantly, sulphur for the transport of gold. Prospects in the Conway area are up to 15 km2 in area, and are of the adularia-sericite type. They illustrate many of the classic features (siliceous sinters, alteration mineralogy, and fluid characteristics) recognised in epithermal deposits. K-Ar dating of sericite alteration in three of the prospects has produced a range of ages from 283 to 334 Ma, suggesting that the systems are the product of multiple hydrothermal events.

Jan 1, 1990

By G Williams

Somewhat to the surprise of many heavy mineral sands (TiO2 and zircon) producers, there are important geological structures within their typical placers and aeolian sands deposits that affect plant metallurgical performance. After many years of operations, even experienced producers have encountered unexpected changes in production, product quality and recovery. After looking in all the obvious (but wrong) places, it is recognised that the mine has advanced into ore with different separation characteristics. Metallurgical process response can vary significantly between ore sourced from different geological domains. The mineral characteristics that are exploited for effective separation may be associated with differences in the depositional environment, or be post-depositional in origin. Surface coatings that interfere with electrostatic separation might be associated with paleo-water table movements. Major storm events in the deposition history can also leave distorted mineral assemblage through stranded formations or incisions in older deposits.Apart from the influence on capital and operating costs, geometallurgical variances add another dimension to orebody modelling. Each domain could have specific recovery, mineral assemblage and product quality values to be considered in the value model. Project success is often directly dependent on understanding the geometallurgy of the resource. Tailoring the exploration and early process flow sheet development programs to account for such variances should be standard practice. Such practices have had a chequered history in the mineral sands industry, with sophisticated processes having been developed, only to be shelved for ‘economic’ reasons, and then once again ‘discovered’ when problems re-emerge.It is clear that knowledge gained through a higher level understanding of the changing mineral separation characteristics and advance warning of mineral behavioural differences can mean the difference between lost recoveries and disappointed customers or well timed capital plans and maximised revenues.

Oct 5, 2011

By J Simpson, M Johnston

Recently Mount Isa Mines undertook a study to review the lead-zinc orebodies to extent of resource and reserves and determine the new life-of-mine schedule, as the Mount Isa and Hilton orebodies had not be reviewed for many years. Also, the recovered value of the Mount Isa, Hilton and George Fisher orebodies had been increased by major performance improvements in the lead-zinc concentrator. The Mount Isa Lead-Zinc concentrator processes fine-grained lead-zinc ore from the Mount Isa, Hilton and George Fisher orebodies. These orebodies have varying levels of pyrite and large variation in the grain size and texture of the galena, sphalerite and pyrite. This variation has a large effect on the recovery of the lead and zinc in the concentrator. Some ores achieve 90 per cent recovery at target grades, yet other ores are unable to achieve æsaleableÆ concentrate grade, with no metal being recovered to concentrate and therefore effectively losing the contained metal to the final tailings. Models were created to predict the metallurgical performance of these orebodies, to better reflect the variation that occurs. These improved metallurgical models and economic data allowed the determination of the Net Smelter Return (NSR) for each block in the geological block model. This NSR is the return to MIM of the metals contained in concentrate. The NSR was used as the cut-off grade criteria when determining the value of the ore. This formed the basis of the lead-zinc life-of-mine schedule and the optimisation of the lead-zinc business.

Jan 1, 2003

By A Smith

Rock masses usually exhibit scale dependent mechanical properties primarily due to presence of discontinuities and their inhomogeneous nature. One of the essential preconditions for selection of appropriate strength and deformation parameters of a rock mass in relation to tunnel design is assessment of the scale of the joint network relative to the scale of excavation. In tunnel design practice, scale effects are estimated indirectly using small-scale unconfined compressive strength (UCS) tests and rock mass classification based empirical correlations. Large-scale UCS tests have the benefit of direct assessment of anisotropic and scale dependent properties of a rock mass.This paper presents results of a large-scale UCS test on a jointed siltstone. A 450 mm diameter sample with inclined bedding planes was cored and tested in uniaxial compression until failure with load and displacement measurements. The aim of the test is to determine strength and deformation parameters and correlate them with results of small-scale UCS tests of the same sample. The relationships between the small-scale and large-scale rock mass parameters were validated against published correlations from the literature.

Mar 8, 2011

Many of the large refrigeration plants used in, the cooling systems on deep South African gold mines are situated on surface where they are exposed to seasonally and diurnally varying climatic conditions, and to a diurnally varying demand for cooling made by the mine. It has been traditional to accommodate the seasonal variation in climate by manual control applied to the plants at appropriate times of the year, and the plants have normally been specified to conform passively to the diurnal variations. This paper introduces new strategies for the active automatic control of the plants on a diurnal cycle, and shows that attractive benefits in energy and chilled water resource management can be accrued through the use of these strategies. The results have been derived through the modelling and simulation of a representative refrigeration plant.

Jan 1, 1985

By P Martin, A Somarin, S Bailey

Field-based research was conducted to investigate the performance of field portable X-ray fluorescence (FPXRF) in the analysis of reverse circulation (RC) drill chips in iron ore exploration. For years, FPXRF has been considered unsuitable for iron ore exploration due to the limitations of the elements it is capable of analysing for, in particular its inability to measure light elements (Mg, Al, Si, P, S). With the advent of the use of silicon drift detectors (SDD) in FPXRF, light elements are now measurable elements. However, doubt over the appropriate use of this new technology still exists due to the absence of reliable comparative field data. These doubts concerned the ability of the FPXRF data to correlate strongly with the laboratory assay of the same samples. It was believed that inconsistent grain size and other variables not being controlled would contribute greatly to this perceived unreliability.We tested RC chip samples on-site in the Pilbara, with the portable Thermo Scientific Niton XL3t X-ray fluorescence (XRF) analyser for a range of elements including Fe, Mn, Al, Si and S and then compared the results with laboratory assay data. A strong correlation indicates that the FPXRF results are reliable. Furthermore, to show the effect of simple sample preparation, we also analysed pulps of the same samples in the same way.The correlations were good for all of the elements of interest for the RC chip samples (R2 values between 0.82 and 0.9), and excellent for the pulps (R2 values between 0.89 and 1). The results also showed a direct correlation between sample preparation and improved quality of results with the FPXRF. This indicates that FPXRF can produce data from unprepared RC chips for Al and Si that, when compared with laboratory assays, is reliable for a field application in drilling and grade control. CITATION:Somarin, A, Martin, P and Bailey, S, 2013. Non-destructive analysis of diamond core for light elements using Niton field portable x-ray fluorescence, in Proceedings Iron Ore 2013 , pp 117-230 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By M Taylor

The Project Specification and Technical Requirements documents associated with several recent large road tunnel projects within Australia have specified the application of AS/IEC 61508 – FunctionalSafety of Electrical/Electronic/Programmable Electronic Safety Related Systems at very high performance levels for the various control and fire life safety systems associated with such facilities.This paper seeks to explore the implications of referencing this standard within the road tunnel services context in terms of practicality, complexity and cost, whilst providing some examples of how a high safety integrity level (SIL) level can theoretically be achieved given current hardware availability.

Mar 8, 2011

By R N. Humphries, R J. K Thompson

Large-scale coal mining in South Wales dates back to the late 18th and early 19th centuries with the birth of ironmaking on an industrial scale. This rapidly gave rise to new and large communities with immigration from far and wide across the United Kingdom (UK). These new communities were largely dependent on coal mining and served as the main form of employment and social cohesion until the industry’s demise in the 1990s. With wholesale mine closure and the concomitant loss of employment, the extensive environmental degradation and chronic mine-related illness left a deep scar on the psyche on many still living in the South Wales mining communities. This coupled with memories of strife in the 1980s has resulted in ongoing hostility toward the surface coal mining of the remaining accessible coal reserves in the proximity of these communities.The purpose of this paper is to set out the historical basis of the concerns of these legacy mining communities in South Wales and explain how they are being positively addressed by both the recently evolved planning and regulation system and by today’s surface mining industry. Reference is made to experience gained from two recent applications for surface coal mining adjacent to former mining communities. Ways are suggested in the approval process that surface mining can work in more harmony with the local communities through working partnerships between the mining company, the authorities and regulators and the affected communities. It is concluded that partnership is key to creating a more responsive mine-operating culture and a means to securing approval for future surface coal-mining prospects in South Wales, and probably elsewhere too.CITATION:Humphries, R N and Thompson, R J K, 2014. Surface mining and legacy mining communities in South Wales, UK, in Proceedings Life-of-Mine 2014 , pp 399–412 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014