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Improved roof control in high deformation tailgate environments has been achieved over the last decade through development of stiffer and increased capacity standing support products. æThe CanÆ is one such development, being a steel cylinder containing a weak cementitious fill, designed to essentially fold in upon itself whilst maintaining strength. A laboratory study to better define the relative load contributions of the steel cylinder and fill, the confining interaction between these components and most importantly, the potential impact of varying the steel and/or fill properties is described. This would enable the support engineer to ædial-upÆ the desired strength and stiffness properties and optimise the standing support design with respect to load capacity, stiffness, weight (handling) and cost. Design curves to optimise strength based on steel casing thickness, fill strength (confined and unconfined) and æCanÆ geometry were established. Scaled-down (one-third) samples were used in the test program and found to adequately reflect the loading behaviour of full-scale versions, thereby providing significantly greater scope for further product development at less expense compared with testing full-scale products.

Jan 1, 2005

By S M. Gover

Estimating the probability of failure for embankments is not intuitive. It requires not only an appreciation of the strength of the embankment, but an understanding of the variability and uncertainty in the strength parameters as well. These additional aspects are, in themselves, relatively new to most practicing engineers, and therefore require some discussion.This paper discusses the concepts of probability and uncertainty, and presents a reliability-based numerical experiment, together with a literary study and collation of some of the author’s historical slope stability analyses, to investigate whether a direct relationship between safety factors and probabilities of failure exists for certain levels of uncertainty in strength parameters. In doing so, a useful tool is presented whereby knowing the safety factor of a simple slope or embankment with a consistent level of uncertainty, one can infer an approximate probability of failure.CITATION:Gover, S M, 2018. Linking safety factor to probability of failure, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 384–396 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

In the UK during the 1990s the energy companies had developed a policy of æDash for GasÆ, building large natural gas power stations to produce more than 30 per cent of the UKÆs electricity demand. The price of imported thermal coal was dropping and the electricity generators were putting pressure on the UK coal producers to produce coal at a reduced cost. Imported coal from Columbia, South Africa, America and Australasia had increased their market share in thermal coal sales to over 50 per cent of a 55 Mtpa market. The pressure on the UK coal industry to reduce costs and improve productivity levels from an ever decreasing resource was high. Companies were benchmarking their operations on the imported coal producers and had to realign their organisations, productivity levels and costs to world best practice, not just technically, but in world class organisational management techniques.

Jan 1, 2005

By J Folwell, G Phillips, F Gassner

Geomembranes selected for various applications often start with considering target properties developed by industry organisations such as Geosynthetic Research Institute (GRI), and test methods developed by ASTM and other Standards organisations The geomembrane types are typically, initially selected based on manufacturers recommendations and chemical resistance data from the manufacturer or industry knowledge. Geomembranes considered for this project included materials with material properties that exceeded the minimum target values of various test methods. The difficulty is in selecting which parameters are most important for a particular application and also what service life can be expected for the geomembrane under various chemical and environmental exposure conditions. Accelerated aging testing of candidate geomembranes in simulated exposure conditions can be useful to select the preferred geomembrane and predict the service life of the geomembrane under different exposure conditions. The exposure conditions of immersion in acidic tailings liquor, splash zone and freeboard zone were considered for evaporation ponds on a site with significant heat and UV radiation. Candidate geomembranes considered a range of different types of polyethylene liners. The results of the accelerated aging testing have allowed the selection of the geomembrane for the range of exposure conditions and evaluation of the expected service life of the geomembrane.

Jul 1, 2021

By K G. Harding, E L. Haggard, C M. Sheridan

Mining is a water intensive sector, contributing to declining water resource quality around the world. Improvements to current mine water management practices can help reduce the amount of water utilised by the mining sector and the impact on water resources. Creating a water account can help companies understand water use in their operations and identify areas where water reduction is possible. Water accounting methods include the Water Footprint Network method and the WaterMiner tool.The Water Footprint Network method is used to determine the amount of direct and indirect water used by an organisation either in a process or to manufacture a product. The total water footprint is divided into the blue, green and grey water footprints. Blue water is the amount of water abstracted from surface and ground water resources. Green water is the amount of rain water utilised. Grey water is the amount of freshwater required to assimilate the waste stream to the natural resource and still conform to ambient water quality standards.The WaterMiner tool is a program available via the internet, which can be used to model water use of mineral processing sites. The program reports the amount of raw, worked and treated water used by the process and recommends flows that can be added to reduce the amount of fresh water required by the process.To gain information on mine water management practices in South Africa, a water account for a platinum mine was developed using the Water Footprint Network method and WaterMiner tool. Based on the results, suggestions to reduce the amount of fresh water utilised are made.CITATION:Haggard, E L, Sheridan, C M and Harding, K G, 2013. Water footprint for a South African platinum mine, in Proceedings Water in Mining 2013 , pp 15-20 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

The paper continues an account, begun in a previous paper, of experimental work carried out by the author whilst a member of the metallurgical staff at the Cockle Creek Works. The general method of the description of the plant and works practice adopted previously has been followed.The paper is a short account of the methods used in and the results of an investigation of the fume losses from the various parts of the plant.MEASUREMENT OF VOLUMETwo independent methods were used. The first depended on a number of pitot-tube measurements of velocity. These readings were taken in the stacks leading from the various furnaces at a considerable height above the ground so as to obtain as regular conditions as possible at the points where the readings were taken.Three openings were made in each stack and the pitot tube inserted into each opening in turn and readings taken at the centres of imaginary areas of equal size. The average velocity in the stack was thus obtained.After four tests had been made at the smelter stack, which removed the gases from all blast furnaces in use, the centre of velocity of the gases for each test was calculated and was found to be practically constant in position. The previous procedure was varied in subsequent tests on this stack by taking a succession of readings at the centre of velocity instead of at various points...

Jan 1, 1925

By F K. R Klose

Malmberget is a sublevel caving mine owned and operated by Luossavaara-Kiirunavaara Aktiebolag (LKAB), a Swedish state-owned iron ore mining company, in northern Sweden. The mine has an annual iron ore production of approximately 15 Mtpa. The current strategy foresees an expansion which will increase the mine’s depth considerably. Ventilation and air conditioning modelling for the planned expansion is ongoing. One of the most influential parameters for ventilation planning anddesign for a deep mine is geothermal gradient, which is crucial for the design of the refrigeration system. It is determined through virgin rock temperature (VRT) measurements carried out at various depth below the surface. This paper details these measurements and the determination of geothermal gradient for Malmberget Mine for the expansion study, which were necessitated by thelack of information for the focus depth and area.

Oct 12, 2022

By Brosnan J. G

Simcoa Operations is the only silicon smelter in the region and since the plant was commissioned in late-1989, has progressed from supplying silicon metal to the secondary aluminium market to the current position of supplying in excess of 90 per cent of its production to the high quality chemical and primary aluminium markets. This position has been achieved through the unique advantage which Simcoa has developed within the industry, namely raw materials, people and Simcoa's ability to adopt and use modern technology. A quality culture was instilled into the workforce prior to commissioning which ultimately led to AS3902 qualification in 1992. Simcoa has continued its quality drive through the formation of 'Simcoa's Quality Leadership Process' which is planned to make Simcoa the best silicon producer in the world.

Jan 1, 1995

By J K. Claflin, S R. La Brooy, A M. Claflin

Rotary kilns have been in service in the gold industry to regenerate carbon for 65 years. At the time oxide ores with gold head grades of 8 to 10 g/t were being treated. Carbon could be regenerated adequately at 650°C and solution losses were less than 1%. Forty years ago, research indicated that heavily fouled carbon from flotation circuits had to be held at 750 to 850°C for ten to twenty minutes for full reactivation (Avraamides and La Brooy, 1987), gold head grades were typically 5 g/t and solution losses typically 0.02 ppm – still less than 1%. In 2017 it was determined (Claflin et al., 2017) that a residence time of less than 1 minute at 750°C can be adequate to reactivate carbon fouled with organics sufficiently to achieve 0.005 ppm solution losses in a flotation tailings leach plant.With the potential for discovery head grades to drop below 0.6 g/t, solution losses of 0.02 ppm represent over 3% loss. Tight operation of the whole carbon circuit is required to keep gold solution losses below 1% going forward.There are alternatives to a rotary carbon kiln, e.g. vertical kilns of which the Minfurn, Rintoul and Combustion Air kilns are examples. The alternative kilns can be heated using electrical heating elements, induction, and microwave. These kilns can operate successfully under the right conditions, however, they are almost exclusively for small carbon throughputs and are not suitable for the large carbon advance rates that are required to process low head grade ore deposits. Large throughput carbon kilns are are almost exclusively fossil fuel fired rotary kilns and the subject of this paper. In the view of the principal author, a fossil fuel fired vertical carbon kiln is preferred to a rotary kiln, however, it is not currently used in the industry.Thermal regeneration of activated carbon has a major impact on gold recovery in the carbon circuit. The carbon kiln and associated equipment constitute 3 to 5% of the capital cost for an oxide processing plant and up to 10% of the capital cost if flotation tails are leached. Despite the capital cost and impact on recovery, the carbon kiln is often poorly selected, operated and maintained.Six years ago Ausenco embarked on the Carbon Kiln Initiative to reduce solution gold losses. This body of knowledge has been published in a series of papers culminating in this paper on how to:1. Select a kiln appropriate for the flowsheet;2. Maintain the kiln to achieve design operation; and3. Operate the kiln to minimise costs and maximise reactivation.CITATION:Claflin, J K, La Brooy, S R and Claflin, A M, 2018. Carbon kiln selection, operation and maintenance, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 251–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Bukeikhanov D. G, Syedin V. F, Sagyngaliyev K. S

The present paper describes a method of simulating deposits of com- posite structure by means of computers. The method employs mathematical tech- niques to study the openworks zone formation dynamics in open-pit mines with any mode of the works front ad- vance as well as to determine, on oriented graphs,the optimal direction of openworks expansion.

Jan 1, 1977

By C Balci, D Tumac, A Sheterpour-Mamaghani, E Dogan, A Kocbay, T Erdogan, A Gumus, H Copur, E Altintas

Excavation of vertical and/or inclined shafts in the underground structures requiring careful design and planning. Raise Boring Machines (RBMs) are commonly used for excavation of shafts for different purposes such as ventilation, orepass, and human-material transportation. Proper selection and accurate performance prediction of RBMs are two main parameters affecting the cost estimation and planning/scheduling. Indentation test is one of the most preferred methods that can be used to predict advance rate of RBMs. This study aims at suggestion of new prediction model for instantaneous penetration rate of RBMs based on indentation tests. Different rock (core) samples (with different geological origins) are obtained from the raise boring application projects in Turkey; then, the indentation tests are carried out on them by using a real-life insert (button), which is used in reamerhead cutters investigated in this study. Finally, the statistical relationships between the field performance and the indentation indices are investigated. The study indicates that the brittleness index (the ratio of maximum applied force to corresponding penetration) can be used to predict instantaneous penetration rate of RBMs used in the vertical raise bored shafts excavating rocks having uniaxial compressive strength lower than 100 MPa.

Nov 29, 2022

By G du Toit, P L. Gillot, M Swanepoel

Randgold Resources’ Loulo-Gounkoto Complex is one of the largest gold mining operations in Mali, West Africa. The mine, which is situated on the western border with Senegal, treats more than 4 Mt/a of ore through a conventional three-stage crushing and ball milling circuit followed by a carbon-in-leach plant. Ore supply is achieved by a combination of open pit and underground mining, with the majority of the ore supply sourced from the Gara and Yalea underground mines situated approximately 2 km and 6 km respectively from the gold plant.In 2011, Randgold Resources commissioned Golder Associates to perform an evaluation study for providing structural backfill to both the Gara and Yalea underground mines using the current gold plant tailings. The test work performed as part of the evaluation study concluded the need for a tailings cycloning and dewatering facility capable of producing slurry at a solids concentration of 65 per cent with a particle size distribution that had minimum 25 per cent passing 20 µm and less than 5 per cent of -5 µm material. Tailings desliming was required to ensure a consistent feed quality to the paste preparation plants and to ensure that the system would be capable of handling variation in the feed composition from the gold plant.WorleyParsons, previously TWP Projects, was contracted by Randgold Resources to complete the engineering design for the slurry preparation plant, whilst Golder Associates was retained to complete the engineering design of the two paste preparation plants.This paper discusses the test work, design considerations and engineering design of the slurry preparation plant, termed the ‘intermediate plant’, as well as all ancillary facilities required for the delivery of the deslimed slurry to the paste preparation plants located at the two underground mines.CITATION:Swanepoel, M, du Toit, G and Gillot, P L, 2014. Case study – engineering design for a slurry preparation plant for a paste application in West Africa, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 477–486 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By P Fuller, A R. Penney

Re-commencement of mining in the Western Zone of Beaconsfield Gold Mine following a seismically-induced rockfall fatality in April 2006 required a change of mining method involving drilling and blasting from specially developed drives in the footwall of the orebody. Broken ore is mucked remotely from ore drives on each level. Support in the footwall drives is required to maintain stability during their development and as stopes are retreated, which increases induced stresses and further seismic events are triggered. The paper outlines the challenges involved and methods used to select the footwall drive support to handle both static and dynamic load demand. The importance of load development in the support system, its displacement capacity, the compatibility of support elements and energy absorption capacity of the support system are highlighted. It is usual in any support selection process to ensure that capacity exceeds demand to create a factor of safety. In this case the demands on the system relate to load, displacement and energy absorption and the support system capacity for each must ensure that appropriate factors of safety for each are achieved. The paper shows how these factors are not independent and that selecting a high factor of safety for load can lead to compatibility problems with support elements in the support system.

Jan 1, 2008

By B Wu, B W. Lei, B J. Duan

When a coalmine fire occurs, it is crucial to judge the developing trends inside the fire area by analysing the changes of gas concentration in order to formulate the proper rescue measures. At present, few researchers have focused on the relationship between the changing trend of gas product and basic characteristics of fire in the coal fire extinguishing process. To study the relationship of basic characteristics of coalmine fire during the extinguishing process, an experimental platform for coal combustion in a confined space was built, and gas production, flame image and coal temperature during the extinguishing process were monitored and analysed by an online continuous gas analysis instrument, camera and thermocouple. Research shows that during the burning phase of the coal sample in the confined space, the flame zone decreases gradually due to insufficient gas supply. The size of the flame zone fluctuates and shares a positive correlation with CO concentration, while sharing a negative correlation with O2 and CO2 concentrations. Then, in the extinguishing phase, the increasing rate of CO2 concentration and the decreasing rate of O2 concentration both decrease gradually, but CO concentration would rise for a period before it eventually decreases. Coal temperature continues to rise in the open flame stage and does not go down until the flame is extinguished.CITATION:Lei, B W, Wu, B and Duan, B J, 2015. Experimental study on extinguishing characteristics of coal fire in confined space, in Proceedings The Australian Mine Ventilation Conference, pp 279–284 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By D David

Amongst those whose task it is to design tumbling mills and other comminution machines there is an almost religious divide between devotees of the Bond method and devotees of other methods developed in more recent times. For a decade or so the issue was between the Bond power-based methods and the JKMRC (JK) simulation based approach. The newest method to challenge the status quo is power-based and was developed by Steve Morrell. As the title suggests, this paper will take some liberty at concluding that Fred Bond and Steve Morrell may be separated by history, but not by their approaches to their individual contributions to the science of comminution. Another driver for the paper is that although it is good to have diversity of thought, the existing divisions are problematic for those of us signing public disclosure documents. If alternative design methods produce materially different outcomes for the mill duty, then at least one of them is wrong or being used incorrectly. At some point the unsustainable argument may need to be put in a court of law that we metallurgists have two or more materially different design methods, each of which is correct! Therefore, perhaps a resolution is needed before this occurs?The works of both Fred Bond and Steve Morrell are each directly related to their contemporary grinding mill design and operational environments. Both their approaches are empirical, borne of observing and measuring real world situations. Both worked with theories that preceded them, gathered their own data and then each saw shortfalls in the status quo.Fred Bond was an escapee from revolution, a victim of The Great Depression, and had several near death experiences during his early site-based career. Perhaps he was fortuitously rescued from himself when asked by Allis Chalmers (A-C) to set up its rock testing laboratory in Milwaukie in 1930. Fred’s testing led him to conclude that neither the Kick nor the Von Rittinger theories explained his measurements. His writings on the failings of these old theories caused a divide between devotees of the old and new methods at that time. After many years, and much thought and plotting of data (the old way!), he came up with his now-famous equations (and his Third Theory) which have stood the test of time, certainly in the world of Bond-era machines.Coming from England via several African diamond mines, Steve Morrell immersed himself into the comminution world of the JK in Brisbane about a decade after Fred passed on. The JK had developed its semi-autogenous grinding (SAG) simulation framework using its own pendulum breakage tester, itself a derivative of the twin pendulum impact device invented by Bond decades earlier. At the JK Steve developed his authoritative Tumbling Mill Power equations and was involved in real world analysis of comminution problems on the global stage. Steve’s JK experience coincided with the demise of the rod mill, the rise of autogenous grinding (AG) and SAG milling and a rapid expansion in concentrator capacity.Morrell left the JK to pursue his own interests, which included ongoing consulting work, now demanded by the comminution world. He then turned to investigating a growing list of discrepancies between the opinions of designers and theoreticians, and the factual outcomes. The Morrell Method of design arose from this re-examination of ore testing, real world operating data and these glaring and expensive discrepancies between design and outcome. The elements necessary for a relook at the world of rock breakage were in place!CITATION:David, D, 2017. Steve and Fred would have been mates – a comminution design evolution story, in Proceedings MetPlant 2017, pp 2–11 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By G Byrne

Long-term water management is typically ignored in mine closure planning. A review of 73 mine closure plans dating from 2007 to 2013 shows that, on average, relinquishment is proposed to be achieved in 11 years. A separate review of 57 mines in actual closure shows that only five have so far achieved relinquishment with an average closure period of 14 years after production cessation. The remaining 91 per cent of sites in closure have an average closure duration to date of 21 years - and still going.A common issue among those sites in closure is water management, with a further common issue being acid and metaliferous drainage (AMD). Of the closure plans that were reviewed only one site had allowance for long-term (>50 years) of water treatment. Of the sites in actual closure 25 per cent have reported that they expect such long-term water treatment, with many acknowledging that in perpetuity treatment is probable.Clearly there is a gap between what is being allowed in closure plans and the reality of closure. There are a number of factors leading to the optimism of the closure plans, including unrealistic assumptions, pressures to reduce closure cost provisions and the technical complexity of many AMD issues.Long-term water management is a reality that needs to be acknowledged and addressed. If addressed early in the mine life cycle the impacts for mining companies can be reduced.CITATION:Byrne, G, 2013. Long-term water management - the forgotten legacy of mine closure, in Proceedings Water in Mining 2013 , pp 163-168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By R Strand, L Reading, G Keir

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

Nov 26, 2013

By M T. Nguyen, S Vink, M Ziemski

On any given mine site the water system is contingent upon its initial design. Through time the initial design is adjusted by a myriad of water management options in order to improve water system performance or to adapt to a new production capacity or method at the mine site. These options generally do not comprehensively consider energy requirements, so it is unlikely that any given mine water system will be optimised in terms of both water and energy uses. Thus this may simply shift constraints of efficiency of one resource dimension, water, to another, energy. As a result, changes in water systems would cause more energy-related issues to mining companies. For example, the companies would have an increase in operational cost and/or pay more for carbon tax with changes in their water system. Therefore, in order to avoid undesirable and potential unforseen energy and infrastructure issues in a mine life cycle, it is essential to select suitable water management options for a mine considering both water and energy resources simultaneously.Considering water and energy criteria in evaluating water management options consists of net water volume availability, net operational energy demand and net water replacement energy demand. Ideal water management options should be high in water volume availability but low in both operational energy demand and water replacement energy demand. A water option would also be favourable if it has low potential of causing adverse environmental impacts such as lowering groundwater tables due to groundwater withdrawal, or elevating saline constituents in surface waters when reusing brine for dust suppression. However, these environmental impacts are not considered in this analysis.This article presents a graphical method to assess mine water management options, based on these three criteria. The proposed method to assist in screening mine water management options includes two main steps:1. categorise water management options into prioritised groups2. rank the options within each prioritised group.The method is applied to a gold mine and presented in this article as a worked example. CITATION:Nguyen, M T, Vink, S and Ziemski, M, 2013. Selection of mine water management options considering both water and energy impacts, in Proceedings Water in Mining 2013 , pp 29-34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By G Capes, L Morizzi, N Mitkas, E Jones, D Grant

This paper describes the mining setting for the sub-level open stoping (SLOS) mining method used at Olympic Dam (OD), and investigates the range of stope performance conditions encountered over 30 years of production, using a qualitative description of the factors influencing performance. Utilising a continuous improvement tool, the Plan-Do-Check-Act (PDCA) process, and a forward-looking rock mechanics program, the intent is to identify the key factors driving productivity and performance to create a stable and achievable long term mine plan.

Mar 15, 2021

By A Giblett, B Putland

This paper provides a simple guiding framework for grinding circuit optimisation, focussing on common themes in past optimisation success stories, the conditions for success and techniques that can be employed to identify and define opportunities. Many significant grinding circuit improvements have been reported for operating plants, based on recurring themes such as the optimisation of mill feed size, mill liner design, process control, critical size, grinding media and classification. The paper condenses these experiences into a set of simple questions for the operator to ask, and provides guidance towards identifying and achieving the optimisation goals.CITATION:Giblett, A and Putland, B, 2018. The basics of grinding circuit optimisation, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 129–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018