Search Documents

By B Clements, R Dunne, J Dioses, S Hart

In April 2003 plant upgrades in the æLow GradeÆ Cadia Hill circuit were undertaken in order to improve concentrate quality and metal recoveries from the flotation circuit. The major changes involved: circuit reconfiguration to allow all concentrates to be reground to less than 38 ¦m prior to final cleaning; increasing ball charge in the regrind mill to fully utilise all of the installed power; desliming of the cleaner scavenger concentrate to improve the circuit water balance; and the inclusion of a gravity concentrator in the regrind circuit to recover more free gold to bullion.Once the flotation circuit had stabilised under the new operating conditions concentrate launder modifications and increased froth crowding on the scavenger flotation cells permitted the introduction of stronger collectors without compromising concentrate quality or circuit stability.Twelve months on, the copper concentrate grade has increased by two per cent and metal recoveries increased by three per cent and seven per cent for copper and gold respectively. The project capital outlay of approximately $2.0 million has been repaid in less than three months. This paper will review the project from the design, construction and commissioning perspective as well as the subsequent debottlenecking exercise that was required to eventually yield the full benefits of this upgrade.

Jan 1, 2005

By H Askari-Nasab, E Torkamani, M M. Badiozamani, S P. Upadhyay, M Tabesh

"Decision-making in mining is a challenging task. Optimal decisions regarding shovel and truck allocations, aligned with the optimal short-term production schedules, are crucial in keeping the operations in line with the company’s long-term objectives. In this paper, we present two main modelling components as the means to achieve near-optimal operational plans: a mixed integer linear goal programming model to allocate trucks and shovels to mining faces over a shift-by-shift basis so that operating costs are minimised and resource utilisations are maximised through the planning horizon a discrete-event simulation model to investigate the behaviour of a truck-and-shovel haulage system in the presence of uncertainty within mining operations. The goals integrated into the mathematical model are to: maximise production minimise deviations from the target head grade minimise deviations in tonnage feed to the processing plants from the desired feed minimise operating cost.The mathematical model provides shovel assignments and the target productions as an input to the discrete event simulation model while meeting the desired goals and constraints of the mining operation. We illustrate the applications of the discrete event simulation model by presenting a large-scale oil sands case study. The main contribution of this work thus far is the development, implementation and verification of a simulation model with a link to optimal short-term mine schedule and extraction sequence of mining faces, which assists in achieving a high level of mine plan compliance across short-term planning and operational planning time horizons.CITATION:Askari-Nasab, H, Upadhyay, S P, Torkamani, E, Tabesh, M and Badiozamani, M M, 2014. Simulation optimisation of mine operational plans, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 299–312 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 24, 2014

By S McKnight, L Koroznikova, S Hall

Mineral sands represent an important new resource being developed in the Murray Basin, including parts of western Victoria. This paper will outline a simple methodology for mineral sands characterisation, developed as part of the AMIRA-managed project P777 æThe Development of Heavy Suspension Techniques for High Density Separations (Replacement of ClericiÆs Solution)Æ. This project is currently sponsored by three multinational mining companies (De Beers Consolidated Mines, Iluka Resources Limited and Rio Tinto Limited) and is developing an innovative laboratory mineral characterisation procedure that will allow the replacement of the currently employed highly-toxic chemicals.Mineral sand resources almost always contain more than one valuable (and relatively heavy) mineral. Titanium minerals are found with a large range of titanium contents, giving rise to density variation and often subjective mineralogical descriptions. Companies tend to rely on laboratory heavy liquid separation in the evaluation of samples arising from exploration, mining or metallurgical processes. Unfortunately, there are only a limited number of high density (æheavyÆ) liquids and these tend to be more toxic as their density increases. Low-toxicity inorganic solutions, based on tungsten compounds, have been developed that can be utilised at relative densities (RD) up to 3.0. However, beyond this value currently only organic liquids can be used. Diiodomethane (methylene iodide) having a relative density of 3.31 is commonly used; however, this presents significant health and safety hazards. Mixtures of thallium formate and thallium malonate were found in the early 1900s by Clerici to provide liquids having specific gravities between 4.0 and 5.0, hence æClericiÆs solutionÆ. For the characterisation of the heavy components of mineral sand deposits (eg anatase sg 3.9, rutile sg 4.2, ilmenite sg 4.4 û 4.7 and zircon sg 4.6 û 4.8) there is currently no heavy liquid alternative to ClericiÆs solution. ClericiÆs solution is highly toxic and testing is now conducted by very few laboratories worldwide with costs reflecting the chemical costs (though extensive efforts are made to recover and reuse the liquid, plus the requirement of its removal from the mineral samples), the infrastructure costs and health and safety regimes (eg blood testing of exposed staff, inventory management). A simple laboratory technique of density fractionation is being developed, employing suspensions of fine tungsten carbide particles in lithium heteropolytungstate (LST) solutions, that can replace ClericiÆs solution in the evaluation of fine mineral sands samples (eg -250+150 microns). The developing methodology that can achieve low-cost, low-toxic separations at relative densities above 5.0 will be outlined and the comparison of results with ClericiÆs solution presented.

Jan 1, 2006

By R E. McIvor, K M. Bartholomew

Classification system efficiency (CSE) is a simple, powerful metric that provides a comprehensive measure of classification system performance. CSE directly quantifies the amount of coarse solids in the mill, and as a result, also directly quantifies the percentage of mill power being used effectively. In this manner, it is an effective, practical grinding energy efficiency metric.Three independent variables drive CSE: circulating load ratio, sharpness of classification, and classifier bypass. Due to practical downstream constrains on per cent solids, improvements realised by increasing circulating load reach diminishing returns as sharpness of classification and bypass deteriorate in the most commonly used classification device, the hydrocyclone. This combination of effects leads to the use of CSE, and its relationship to operational economics, as an objective circuit optimisation criterion.Its simplicity in measurement makes CSE a useful tool for the plant metallurgist, and it is not subject to a great amount of experimental error. CSE provides the plant operator a fast, simple, and effective means to evaluate the performance of the plant classification system. Improvements in CSE relate directly to circuit throughput and energy efficiency. This paper, through description and plant case studies demonstrates the power and utility of this emerging grinding system optimisation metric.CITATION:Bartholomew, K M and McIvor, R E, 2013. Classification system efficiency - a comprehensive closed-circuit grinding optimisation metric, in Proceedings World Gold 2013 , pp 389-394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By S Hapugoda, J R. Manuel, X Cao, B D. McDonald, N A. Ware, L Lu

Roy Hill is a large iron ore mining, processing, railing and port operation in the Pilbara region of Western Australia. Since delivering its first shipments to customers in December 2015, Roy Hill has quickly achieved a 60 Mtpa production rate of lump and fines products. The process plant, principally consisting of wet scrubbing, screening and de-sanding unit processes, was expanded from early 2020 to include operation of a Wet High Intensity Magnetic Separation (WHIMS) Plant. The WHIMS Plant treats tailings to recover approximately 4 Mtpa of ultra-fine (nominally -150 μm) high-grade hematitic concentrate which, after dewatering, is blended into the fines product. Unlike typical hematite concentrates, which consist largely of dense particles with smooth surfaces, the WHIMS concentrate is characterised by very finely microporous hematitic/goethitic particles, reflecting the overall characteristics of the Roy Hill deposit. Detailed test work has been conducted in collaboration with CSIRO to characterise the WHIMS concentrate in terms of its physical and mineralogical properties, and to determine its influence on the granulation and sintering performance of Roy Hill fines – from fundamental/lab-scale and sinterpot perspectives. The results demonstrate that blending of the high-grade hematitic Roy Hill WHIMS concentrate into the fines product can maintain overall sinter quality and positively influence granulation and sinter melt formation, as well as Fe grade.

Nov 8, 2021

As mining and extraction processes improve and lower grade ores become economic, mining for most ores have extended to depths beneath the zone of weathering oxidation created over geological history. These deeper openings expose sulphidic formations and reduced mineral species as either primary ore or simply as accessory or gangue minerals in the country rock. This is not new, underground mining for primary base metal and gold have long been familiar with these problems, as have coal and uranium miners. The change is simply that the number of mines exposing sulphidic waste rocks, tailings to the atmosphere and/or leaving behind dewatered sulphidic rock surrounding the mine void has increased the number of sites from where acid mine drainage (AMD) may emanate with consequential problems for the hydrological environment including downstream catchments (Miller et al, 1996). The principles of ecologically sustainable development (Brundtland, 1987) have been more or less ratified by all the developed nations of the world and this has led, amongst other things, to an expansion unprecedented in the research and documentation of means for achieving long-term environmentally acceptable stabilisation of solid wastes of all sorts. These have revealed that AMD problems can be minimised and even reversed in many cases by the integration or co-disposal of biodegradable organic wastes with oxidising sulphidic wastes (Elliott et al, 1996). This paper considers how this might be achieved at mine sites in Australia and the results encountered at some relevant sites.

Jan 1, 1997

By J Nell, J Petersen, X C. Goso

The feasibility of increasing the deportment of titanium species and the stability of the pseudobrookite solid solution (M3O5) in a titaniferous slag was investigated, to facilitate the valourisation of titaniferous slags. Thermochemical simulations using FactSage™ software, ver 8.3 (by Thermofact/CRTC and GTT-Technologies), and equilibration-quench experiments were conducted using an appropriate synthetic titaniferous slag composition in an oxygen partial pressure (pO2) ranging from air to 10-16 atm under non-isothermal conditions. The temperature-pressure phase stability diagram for the synthetic slag containing 37.19 per cent TiO2, 19.69 per cent SiO2, 13.12 per cent Al2O3, 16.00 per cent CaO and 14.00 per cent MgO showed that the spinel solid solution (M3O4) was the primary phase until a pO2 of 10-10.5 atm, thereafter M3O5 was the primary phase until a pO2 10-13.2 atm. M3O4 again was the primary phase between a pO2 10-13.2 and 10-16 atm. The changeover of the primary phase coincided with an increase in the liquidus surface. When cooling the slag in a pO2 of 10-16 atm, M3O5 crystallised as a ternary phase that showed a rapid increase in mass while that of the primary M3O4 phase decreased and that of the secondary perovskite (CaTiO3) phase increased at a slower rate. At 1300°C under sub-liquidus conditions, the contents of M3O5, M3O4 and CaTiO3 were about 20 per cent, 15 per cent, and 11 per cent, respectively. Experimental results showed that the Ti3+/Ti4+ mass ratio in the M3O5 phase, ie a measure of the reduction of titanium species, is not considerably sensitive to equilibration temperature in the reviewed range. Slow cooling and minimum/no oxidation during cooling of titaniferous slag would increase the deportment of titanium species to, and the growth and stability of the M3O5 phase.

Jun 19, 2024

Nine case studies are presented to illustrate how risks can be, minimised or quantified during pit optimisation, utilising Whittle Four-D software. Each case study covers a specific problem that has been encountered from a wide variety of pit optimisations. Case A: Maximising profits when the tenement owner is paid a royalty on tonnes processed. Case B: Allocating product prices, rather than a single commodity price during optimisation. Case C: Quantifying processing costs that are affected by penalty elements in the ore. Case D: Exploration expenditures below current pits can be quantified through the use of simulation techniques. Case E: Alternative strategies can be quantified when pits are restricted by tenement boundaries. Case F: Relocation of mine infrastructure that requires large capital expenditures, can be simulated by allocating costs to an area during optimisation. Case G: Evaluating alternative corporate strategies during pit optimisation. Case H: Sensitivity analysis for price, processing cost and mining cost. Case I: Quantifying the advantages of using additional mining capacity during the early periods of mining.

Jan 1, 1994

By L Klemettinen, A Jokilaakso, D Attah-Kyei, P Taskinen, M Tiljander, D Sukhomlinov, D Lindberg

In this study, the use of carbon neutral biochars as reducing agents in the pyrometallurgical treatment of nickel slag was investigated at 1400°C in order to recover valuable elements such as copper and nickel from the slag. A large amount of slag is generated during the nickel matte smelting. Nickel slag contains valuable elements such as copper, nickel and cobalt, which can be recovered. Disposal of this slag results in loss of resources and may cause pollution of the environment. It is important to retrieve these metals for environmental and economic reasons. In this study, the slag was reacted with non-fossil reducing agents (biochar) which were produced from hydrolysis lignin and black pellet biomass pyrolyzed at 600 and 1200°C and with metallurgical coke for comparison. The reduction experiments were done at 1400°C for 15, 30 and 60 mins under inert gas atmosphere. The samples were quickly quenched and analysed with Electron Probe X-ray Microanalysis (EPMA). The results showed that the use of biochar resulted in faster reaction kinetics in the reduction process compared to coke. The fast reaction kinetics is attributed to the relatively high content of volatiles in this biochar, leading to gas formation and thus mixing of the sample material. Moreover, thermodynamic modelling was also performed using FactSage™ to simulate equilibria with different amounts of biochar. The metal to slag distribution coefficient calculated from the results of thermodynamic modelling were consistent with experimental results. In addition, thermodynamic calculations confirmed that nickel is reduced rapidly and it deports to the metal alloy phase. As the reduction progresses or extra reductant is available for reactions, more iron is deported to the metal phase. The calculations also revealed that Zn vaporises into the gas phase.

Jun 19, 2024

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 R P. Varden

This paper looks at the design of the Bentayga raisebore with subsequent back analysis using a LiDAR survey. A search for LiDAR raisebore assessment publications shows little work has been done on this subject. The paper examines the empirical design and RS2 modelling assessment with the bored condition. The high resolution of the LiDAR enabled mapping of weak structures that were located on the geotechnical investigation hole the orientations of which could not be determined. In addition, the scan showed were water ingress was occurring, potential stress overbreak and structural controls on stability. The LiDAR results were able to confirm no additional support work such as a shotcrete liner is necessary. The LiDAR results have been analysed in one metre increments as volume of overbreak against the empirical stability criteria (McCracken & Stacey 1989). The future use of LiDAR mapping over a range of rock mass conditions will provide quantification of the established empirical assessment improving its reliability. It is also a useful and accurate tool to monitor long term stability of a raisebore due to stress change or ore pass due to wear.

Mar 15, 2021

By Yamada K, Abe H

Magnetic scanning type mass spectrometers have been given improved sensitivity with a large dynamic range and considerable resolution by the addition of a computer-controlled electric equipment. A mass spectrometer equipped with this newly developed electric system was applied to studies of the activities of liquid iron-silicon alloys and of liquid iron-phosphorus alloys at 1600¦C. The range of silicon concentration was 5.8at%-51.1 Si= at%, and values of ySi -3.1+0.15 and es 11.5 +1.5 were obtained. The concentration range of phosphorus was 1.3at%-5.7at% and a value of eP=7.3+0.1 was obtained.

Jan 1, 1980

By J Zhou, L Crompton, K P. Galvin, J L. Sutherland, C P. Lowes, C Bezuidenhout, J Bijzet

Platinum Group Metal (PGM) bearing ores from the Upper Group 2 (UG2) reef often contain significant concentrations of chromite which can potentially be upgraded to produce a saleable product. A common approach is to implement gravity separation on the PGM flotation circuit tailings. However, where the particle size range of interest is broad and the lower size limit ultra-fine, the challenge is how to maximise the recovery at a saleable product grade without compromising throughput. This study was concerned with the performance of a REFLUX™ Classifier for beneficiation of a PGM bearing chromite ore and the benefits of size classification. The sample had a nominal top size of 0.5 mm and was processed over the complete size range and in two discrete size classes following classification at 106 µm. The primary goal was to produce a concentrate exceeding 40 wt. per cent Cr2O3, ideally approaching 42 wt. per cent Cr2O3, with minimal PGM losses above 106 µm. A major challenge was to process at the required solids throughput in a single stage with the feed pulp density constrained to a nominal upper limit of 30 wt. per cent solids. It was found that varying the controller density set point of the REFLUX™ Classifier produced strong control of the product grade. Products as high as 41.1 wt. per cent Cr2O3 were produced at 78.6 per cent recovery for the +106 µm material, while in the −106 µm portion the product grade was as high as 41.4 wt. per cent Cr2O3 at 83.2 per cent recovery. Processing the feed in discrete size classes enabled the volumetric feed and fluidisation rates to be optimised for a given application; hence, superior performance was achieved at the finer sizes. This work has demonstrated the value in considering feed preparation as well as technology selection in developing a robust process solution.

Aug 24, 2022

By E S. Weiss, S P. Harteis

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) has conducted full-scale explosion experiments, to evaluate the strength characteristics of various seal designs, used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests conducted within the multiple entry section of PRLÆs Lake Lynn Experimental Mine (LLEM) is currently the only accepted test method used by the Mine Safety and Health Administration (MSHA), for deeming a seal design suitable for use in American mines. These explosion tests are labour intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. The PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept, that can facilitate the in situ testing of seals in an operating mine. Two chambers within LLEM and one within PRLÆs Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from these chamber tests compare favourably with those from the large-scale explosion tests in the multiple entries. In addition to testing seal designs at the required 20 psi static pressure level, the chamber test approach also allows for the determination of the sealÆs ultimate design strength. Size-scaling relationships for predicting the strength of seal designs as a function of entry size are also presented.

Jan 1, 2005

By Z Fu, E Topal, O Erten

"Mine waste rock management involving waste rock movement and placement, is a critical aspect in the planning of open pit mining operations, as the waste rock haulage cost can be the largest portion of the mine operating cost. The concept of sustainable development in the mining industry also encourages environmentally friendly waste dumps that have zero hazards to people and the surrounding environment. Therefore, a detailed waste management schedule must satisfy economic and environmental considerations. However, the available tools in the market cannot provide optimal waste dumping schedules to meet all these constraints. This paper introduces a user-friendly and automatic tool to optimise the waste dumping schedule, which minimises the haulage cost, and covers the encapsulation of reactive materials to minimise acid mine drainage problems. This tool has been developed by using a new mixed integer programming (MIP) mathematical model that considers both single-lift and multilift dumping scenarios. The application of the proposed tool on a data set collected from a gold mine shows that the multilift dumping scenario has provided a more flexible and economical waste dumping schedule than the single-lift scenario, and both scenarios satisfy environmental requirements.Citation:Fu, Z, Topal, E and Erten, O, 2016. A Modified Software Tool for Mine Waste Rock Dump Planning, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 229–242 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By H Weitz

Bateman Engineering provided process technology and engineering design to China Yunnan Metallurgical Company (CYMCO) for a 30 MW DC furnace for the production of high-grade titanium dioxide slag.Following the successful commissioning of the furnace during the latter part of 2009 and the first quarter of 2010, a period of adverse circumstances resulted in having to operate the furnace without feed and at a low power input for a period of time. When normal feed resumed, a layer of solid material was detected on the slag-iron interface during sounding measurements. The condition of the iron was also significantly altered. The iron temperature was much higher than the design value, but the carbon content had decreased to such an extent that a large amount of iron solidified in the furnace, which made iron tapping very challenging. The slag temperature was increased in order to melt the solidified iron. However, severe sidewall damage resulted, which finally led to a burn-through. A number of samples were taken from the slag that remained in the furnace. These samples were analysed to determine the chemistry and phase profile throughout the slag bath. The mechanisms of formation of the high melting-temperature phase on the slag-iron interface are discussed, as well as procedures that can be applied to prevent a recurrence of this phenomenon. Some recommendations are made for instances when furnace feeding is interrupted for an indeterminate period.

Oct 5, 2011

By A Golev, G Corder

The concept of the circular economy has been gaining traction both in Europe and China.In Europe the Ellen Macarthur Foundation see their mission as accelerating the transition from a linear take-make-dispose economic model to a circular model that is restorative and regenerative by design, and aims to keep products, components and materials at their highest utility and value at all times. The Chinese Circular Economy initiative is effectively a sustainable consumption and production program utilising cleaner production, industrial ecology and life cycle management approaches to meet the national challenges of maintaining rapid economic growth while simultaneously enhancing environmental quality and maintaining social progress. A key characteristic of both of these circular economy initiatives is to design out, reuse or minimise the generation of waste.The mining sector, by definition, is represented by linear rather than circular activities, by supplying resources to society. However, being one of the world’s largest waste generators, the sector can adopt similar logic to that of the circular economy to improve its sustainability performance. Waste is a critical issue along the whole metals value chain, from mining waste to eventual end-of-life products, such as scrap steel from construction and demolition waste or the growing problem of electronic waste.CITATION:Corder, G and Golev, A, 2016. Can mining be part of the circular economy or is it squaring the circle?, in Proceedings Life-of-Mine 2016 Conference , pp 121–123 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By D Whitworth

The Golden Pig mine has embarked on a diamond drill program design philosophy that increases flexibility of the program by greatly increased drill pattern densities. The use of standard broad pattern diamond drilling at the Golden Pig mine has previously lead to operational inefficiencies and impacted significantly on the costs of the mine. The diamond drill program philosophy and its interaction with mine planning is explained. The case study of the E lode mining as used to internally justify the increased drill densities is detailed.

Jan 1, 2002

By M D. Melville, B C. T Macdonald, T D. W

The surface waters in regions with acid sulfate soils (ASS) can contain high concentrations of acidity and dissolved metals. These soils cause problems for agriculture, construction and development. The water can be neutralised through many techniques, however a technique that is low in maintenance and low in cost is most desirable. Due to the vast spread of ASS along AustraliaÆs coastline an expensive and high maintenance solution would not be cost-effective. In this study, a passive treatment system that has been used to neutralise acid rock drainage has been applied to treat ASS water. This system is commonly referred to as an oxic limestone drain (OLD) or an anoxic limestone drain (ALD) depending on the waters dissolved oxygen concentration. The system that has been developed for ASS has a similar closed system to the OLD or ALD, that traps the carbon dioxide which forms when limestone reacts with acidic water. It has been called a closed tank reactor (CTR) and is constructed by placing limestone into an airtight tank. A common problem that will occur when acidic water with a high concentration of dissolved metals reacts with limestone is the formation of metal oxy-hydroxide precipitates. These precipitates can coat or armour the limestone and reduce its reactivity. To minimise the accumulation of precipitates in the CTR, perforated subdrains have been installed. It is anticipated that high water pressure and flow through the subdrains will remove some precipitates. A sump has also been installed at the base of the tank to collect precipitates that settle under gravity. The CTR has been tested for 70 days at a sugar cane farm located at McLeods Creek, NSW. Within this time the sump and subdrains have been used to flush the system. An orange solution was produced during flushing and it is believed to contain iron and aluminium precipitates. The initial performance of the CTR raised pH by at least one unit. Almost all dissolved aluminium was removed and more than half the dissolved iron. The total titratable acidity ranged from 17 - 92 mg/L CaCO3 in the initial month of monitoring. After passing through the CTR the acidity was reduced to zero. The performance of the CTR during the last few days of monitoring decreased. This is believed to be due to a pulse of water with higher acidity and dissolved metal content that lasted a week. In this pulse, the acidity reached 307 mg/L CaCO3 and the total dissolved aluminium reached a maximum of 24 mg/L. Higher concentrations of dissolved metals may have been the cause for lower performance due to increased precipitation and coating on the limestone.

Jan 1, 2003

By T W. C Stambolie

Longwall mining is a form of underground mining and the principal extraction method for underground coal mining in Australia. The method is used in the mining of both thermal and metallurgical coal. The primary market for thermal longwall mines is that of the export market where price is governed against the Newcastle Thermal Benchmark index (globalCOAL, 2016).Australia’s thermal coal export outlook is considered moderate due to slower demand from major importing countries, as well as slowing domestic production. However, ‘Australia is projected to increase its share of world thermal coal exports and become the world’s largest exporter over the medium term as lower prices, increased domestic use and infrastructure constraints limit growth from other key suppliers’ (Office of the Chief Economist (OCE), 2016, pp 25, 58). On the contrary, and as a result of current global coal price trends, the basic economic principles of underground longwall coal mining are heavily stressed. From a life-of-mine perspective, influencing return on investment is at its greatest during project evaluation and execution. Appropriate and realistic economic assessment is paramount to ensuring the right outcomes are achieved under the current economic challenges.CITATION:Stambolie, T W C, 2016. Thermal coal industry – is longwall mining currently a life-of-mine option in Australia?, in Proceedings Life-of-Mine 2016 Conference, pp 57–61 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016