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By P Joyce, A S. Ray, P S. Thomas, J Haggman

Climate change and global warming present a significant challenge as unsustainable levels of greenhouse gas emissions arising from human activities continue to be emitted. The cement industry is responsible for between five and ten per cent of annual world carbon dioxide emissions; most arising from the manufacture of Portland cement (PC). An effective way of reducing emissions is by incorporating supplementary cementitious materials (SCMs) as partial PC replacements. SCMs are silicate or aluminosilicate based pozzolanic materials which, in finely divided form, combine with water and calcium hydroxide (lime), liberated by cement hydration, to form compounds exhibiting cementitious properties. Pitchstone is such an aluminosilicate and has the potential to act as an effective pozzolan for partial replacement of PC. In North Queensland, Australia, a vast deposit of pitchstone is mined and processed for expandable perlite aggregate. During the classification stage of the excavated natural material, waste pitchstone fines (PF) less than 0.5 mm in size are generated. This study evaluates the waste PF as a viable, eco-friendly pozzolan for the partial replacement of PC. The reactivity of the PF is compared to fly ash (FA), using the pozzolanic compressive strength activity index (SAI) after seven, 28, and 91 days ageing at 20 per cent and 40 per cent PC substitutions. PF was found to be comparable to FA as a pozzolan at 20 per cent PC substitution at all ages tested. However, for the 40 per cent substitution blends significant strength was only achieved at 91 days ageing for the FA blend. The pozzolanic reactivity was also investigated using thermogravimetric analysis to determine the degree of free lime present after 91 days. In all cases where an SCM was added, the free lime was observed to be consumed with increasing age.

Jan 1, 2008

By D J. Williams, C Zhang, F E. Herrera Cabrera

Farming on bauxite residue using screw propelled equipment (SPE) has been commonly practised to accelerate dewatering and as it promotes consolidation and enhances storage capacity. However, it is unclear when and how often farming should be conducted during the transition of bauxite residue from slurry to dry solids and how deep each slurry deposition should be. To address this issue, three desiccation tanks were established in the laboratory to investigate how much farming could enhance the desiccation and consolidation of tailings. The cuboid tanks, of 350 mm in height and 300 mm in width and length and with an opening on the top, were placed on load cells to monitor the water loss during desiccation and were instrumented with moisture and suction sensors designed and developed at the University of Queensland to measure the water content profile of the residue. The bauxite residue, composed of silt-size particles with low plasticity, was hydraulically deposited in the tanks as a slurry at 27% solid content, resulting in 100 mm depth of solid material settling. Evaporation was enhanced by placing two identical electrical fans above the tanks. Two phases were conducted. In the first phase, the two tanks were left untouched for evaluating non farmed conditions and for calibrating sensors, while in the second phase, three tanks were subjected to atemporal farming using purpose-built screw propelled equipment. The experiment was terminated when the residue was completely desiccated. This paper reports on the instrumented tank set-up and the results obtained to date.

Jul 1, 2021

By Bruce See J

Oxidation of artificial Imperial Smelting Furnace lead bullion was performed during cooling between 1180 and 820°C in order to attempt to produce a tin-rich dross.The addition of sodium carbonate together with stirring increased the tin content of the dross when oxidation was carried out with air or PbO on zinc-free bullion.Zinc in the bullion during oxidation resulted in a decrease in tin concentration of the dross due to zinc oxidation and copper entering the dross.

Jan 1, 1987

By Caress ME, Knight MD

The eruption 75,000 y ago of the Younger Toba Tuff ignimbrite and associated ash-fall ranks as the greatest known volcanic event of the past million years. The ignimbrite is known to cover 21,000 km2 (it may extend farther under alluvium of the coastal plain) and forms a low-angle depositional shield centered on the Lake Toba caldera. The ignimbrite is largely nonwelded and shows systematic outward decreases in lithic and crystal contents and clast sizes. Coarse lithic lag breccias that occur at places 85 km apart point to two or more vents on a fissure having this length. The extensive associated ash-fall traceable as far as Malaysia and India is evidently a co-ignimbrite ash but could have a phreatomag-matic component. The Lake Toba caldera measures95 x 35 km and is >1 kn deep. It is not a single caldera but comprises several contiguous depressions and grabens diversified by two re-surgent domes. Earlier parts of the caldera are related to at least two earlier ignimbrites including the Older Toba Tuff dated by Chesner at 0.5 Ma. The caldera is elongated parallel to, and is only 25 km from, the great Sumatra strike-slip fault, and it can be considered almost certain that the caldera is in part a kind of pull-apart structure. The ignimbrites are very crystal-rich. There is no reason to think basaltic magma was involved in their emplacement. Together with ash-falls they have a total volume of several thousand cubic kilometers. They can be categorized as originating from partially crystallized granitic magmas that erupted because tectonic pull-apart occurred several times across the pluton. Small rhyolitic lava domes on fault-lines comprise the youngest volcanic products.

Jan 1, 1990

By K M. Watling, F M, G K. Parker

Surface enhanced Raman scattering (SERS) spectroscopy at surfaces under electrochemical control has been applied to elucidate the adsorption of thiol collectors. SERS spectroelectrochemical studies at coinage metal electrodes have been carried out on ethyl xanthate and three iso-xanthates, O-isopropyl-N-ethylthionocarbamate, 2-mercaptobenzothiazole, diisobutyl- dithiophosphinate and butylethoxycarbonylthioura. For each collector, adsorption occurs via charge transfer to form a metal-sulfur bond and, in situations for which the reversible potential of the formation of the bulk phase is known, at underpotentials.

Jan 1, 2005

By C Bellia, A Maldonado, S Strong, H Baxter

This paper discusses the technical and cost benefits of alternative data collection techniques used to collect lithological information, obtain laboratory testing samples and perform in situ testing. A comparison between diamond coring and sonic coring techniques is made using data from a recent geotechnical investigation for a final pit slope cut-back. The impacts of the coring method on laboratory strength testing results, material character testing and, ultimately, the mass strength parameters and subsequent slope design adopted are compared. The sonic coring method was chosen out of necessity and enabled the collection of tube samples of a clay unit of interest as well as bulk samples for material character and geochemical testing. The sonic coring generated unexpected degradation of clastic units, while cohesive clay-dominated units were recovered well. The likelihood that disturbance due to the coring method would result in lower than expected triaxial strength results was recognised ahead of time, with surplus samples collected and single-stage triaxial strength testing undertaken. This testing compared favourably with historic three-stage testing, where sample degradation occurred during the later stages. Material character testing of fine-grained, clay-dominated units was comparable with historic diamond core testing, while grain size estimates for more clastic units tended to be finer than previous results. The use of sonic coring over non-cored methods enabled the collection of material texture data, geotechnical properties and a full suite of geochemical analyses. This provided a comprehensive understanding of the lithological and geotechnical character of the rock and soil mass. A high-confidence geotechnical model was developed. The end result was the development of a slope design that was more aggressive than was previously designed (5° steeper inter-ramp angle), which has proven to be appropriate to the conditions following excavation. Overall, sonic coring was a cost-effective means of obtaining additional geotechnical data for the site.CITATION:Baxter, H, Bellia, C, Maldonado, A and Strong, S, 2015. Case study assessing alternative data collection techniques and analysis methods to assist with geotechnical slope design, in Proceedings Iron Ore 2015, pp 419–428 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By A Noack

Today underground infrastructures, like tunnels and especially wide spread underground mines, are often equipped with ethernet based communication systems. These networks are used for the unified communication of data, voice and video. As these networks stretch along the major tunnels and in increasing scale also into the production areas, a high degree of coverage can be reached. For wireless coverage, standard IEEE 802.11 WLAN access points are being used. In order to provide a maximum availability and reliability, the active components are equipped with battery backup power supplies and the network infrastructure is set up in a redundant way using ring or meshed topologies. This provides a much higher availability compared to traditional phone systems or dedicated data links using a conventional star topology.Distributed computing intelligence that is installed on active network nodes throughout the whole network, additionally supported by a central server system, creates the basis for new mine safety functions introduced in this paper for both coal and non-coal mining. These new safety functions cover the detection of potential emergencies, using the status of the network as a æsensorÆ, as well as dynamically guiding people to safe exits or rescue shelters in case of an emergency. Furthermore, these functions are of important benefit for improving the efficiency of search and rescue operations following a major incident or accident underground.

Sep 26, 2011

By V Pfannenstiel

The United States (US) coal mining industry has been working under comprehensive planning, operating and rehabilitation regulatory requirements for nearly 35 years. The public desire for environmental protection during mining and rehabilitation following mining to achieve post-mining land use and sustainability goals has been a major factor and continues to influence the process. Mining companies have evolved operations to achieve outcomes that address the desired goals and regulatory requirements cost-effectively and successfully. Over the 35 year regulatory period, requirements for more diverse topography, specialised revegetation communities, landform stability and assured sustainability have increased and become more complex. These challenges are effectively met by maximising integration of mine planning and operating with the rehabilitation process. Rehabilitation is then implemented in a more timely and efficient manner and with effective results that achieve desired outcomes, commonly with added value. Peabody Energy (Peabody) has taken this approach in its US operations and this paper discusses an integrated approach and illustrates learnings and results with examples from several of its western US operations.CITATION:Pfannenstiel, V, 2012. Integrated planning, mining and rehabilitation for effective results and sustainable land use - A western United States perspective, in Proceedings Life-of-Mine 2012 , pp 219-232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By P Thompson, B W. Atkinson

Water treatment is not æcore businessÆ for mining companies.Just as mineral ores and coals are unique, each requiring detailed characterisation and pilot-testing to determine their optimum beneficiation route, so too are mine waters, each requiring careful assessment to determine the most appropriate treatment. There are many cases of æregret capitalÆ expenditure, whereby mines have installed off-the-shelf equipment only to find it inadequate for their purposes or grossly expensive and labour intensive to operate.Water may be required for potable purposes, ore processing, dust control and/or irrigation. A major driver will frequently be environmental constraints for off-site discharge. Mine water projects can become very complex, and detailed models need to be prepared and optimised to properly consider the raw water sources, the on-site storages, the on-site uses and the off-site discharges, as well as handling the residuals (by-products) of water treatment. By-products may be in the form of concentrated backwash streams or streams of elevated salt content. Careful management of the by-products is required to avoid recontamination of the source water.Regulators often drive mine owners toward reverse osmosis (RO) so that their discharges can be considered as æzero dischargeÆ in terms of potential pollutants. Such decisions need to be based on site-specific information rather than any form of æblanketÆ requirement. An analogy is that many humans like to consume mineral water rather than ænormalÆ tap water. Receiving environments also accommodate or even prefer their æmineralsÆ and so RO is neither warranted nor sustainable in many cases.This paper presents two case studies for operating mine sites, both of which have a significant excess of water requiring environmental discharge. The examples demonstrate a sensible balance between treatment type, environmental constraints, process implementation and residuals management. LIMN« æthe flow sheet processorÆ was used to model one of the case studies due to the complexity of the water system on that site.CITATION:Atkinson, B W and Thompson, P, 2013. Mine water - optimising for site and environment, in Proceedings Water in Mining 2013 , pp 9-14 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By M Hourn, G Anderson, V Lawson, P Voigt, D Mallah

As mine head grades decline and orebodies become more complex, traditional mineral processing techniques and flow sheets to achieve saleable concentrate become more difficult to design and construct. Mines with lower quality concentrates or concentrates with penalty elements are particularly under threat. The economics of such operations are far more susceptible to metal price fluctuations, concentrate treatment terms and the availability of other, cleaner concentrates. Additional value may be realised for these orebodies through improved recovery by producing a low grade middling concentrate for further processing, in conjunction with a saleable concentrate.The most economic effective way to reduce impurity levels is to do so as early as possible in the mining value chain. Technologies such as fine grinding and fine particle flotation are well established as effective methods for impurity rejection in mineral processing. What is often overlooked is how a hydrometallurgical process could also be integrated in the overall flow sheet to achieve higher overall recovery at the mill. In the base metals environment, this is probably because hydrometallurgical processes are associated with production of metal, or require the use of expensive and toxic precipitating agents once the minerals of interest are in solution. These processes can be very expensive, particularly with rising power costs and poor economies of scale in capital costs associated with low production rates from middling streams. Glencore Technology (GT) has recent experience in the treatment of middling and low grade concentrate streams and also tailings streams to complement a concentrator flow sheet in a refractory gold and base metals setting. The value proposition is the isolation of a low grade middling concentrate from the primary circuit or the tailings stream for upgrading to an intermediate product with an equal or higher grade than the primary concentrate to allow blending for sale. This allows the plant to operate on a more favourable part of the grade-recovery curve while avoiding the expense of metal production. For existing operations this is particularly attractive since it can be added to the flow sheet with no process interruptions. Two case studies are examined showing flow sheets and costings to arrive at the value proposition of the GT low grade treatment flow sheet.CITATION:Voigt, P, Hourn, M, Lawson, V, Anderson, G and Mallah, D, 2017. Economic recovery and upgrade of metals from middling and tailing streams, in Proceedings MetPlant 2017, pp 289–297 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By A Dunne, R Kruger, H Coleman, P G. Laurens

External and internal challenges in mining are increasing the difficulty and complexity of operating mines. The external mining environment has a big impact on mining operations and is driving the focus on safety, sustainable mining, green issues, profitability and productivity. There is a very high emphasis on ‘reducing cost to improve’, lower mining and beneficiation costs by eliminating waste/inefficiencies (reduce people, use less consumables, multiskilling, etc). The internal mining environment is getting tougher to operate in, with the deposits being more difficult to mine, more difficult to manage due to external pressure along with issues associated with maintaining quality, etc.Technological and environmental developments too numerous to mention, mean that cost control models, reduction in human resource numbers, as well as other drastic measures to curtail expenditure and increase profitability have become part of everyday business. The capability to manage the mining environment in a systemic manner has been lacking and this increases the pressure for performance on those individuals operating and managing mines.Working smarter has become crucial to ensure that businesses optimise the use of their resources, become more safety conscious, more productive and remain cost-effective, while recognising the importance of sustainable mining now and in the future. The logic of determining and managing to the capability of the mining value chain will be examined and the underlying assumptions or beliefs guiding behaviour and decision-making will be highlighted.In order to identify the obstacles in the mining value chain that hinder achievement of its full potential, the following questions have to be asked:What are the factors that influence the performance of a mining value chain?What is the design capacity of the mine?How can the inherent flow and value capacity of a mine be determined?What types of solutions will allow a mine to operate at its inherent flow and value capacity?This article will discuss the way we plan, measure, assess and manage the mine value chain, by addressing the following factors:balanced capacity versus flow and value capacity designthe use of averagingoptimising individual components in a value chain versus optimising the whole value chain.Optimising flow and value through the mining value chain is one of the three pillars of Mineral Resource Throughput Management (MR™). MR™ is an entrenched and academically supported philosophy that has been successfully applied in the past decade in various mines throughout the world by EXXPLEO, a mining and beneficiation consulting company. EXXPLEO has partnered with HCL (a global IT company) to embed the MR™ philosophy, methodology and toolsets into a formal software product called Synchronised Digital Mining (SDM). The SDM system will provide mining companies with a sustainable platform to effectively apply the MR™ principles and toolsets effectively across all operations targeting increased productivity, efficiency and profitability without having to train operations and management staff into expert MR™ practitioners to successfully achieve the desired results.CITATION:Dunne, A, Laurens, P G, Kruger, R and Coleman, H, 2015. Optimising flow in the mining value chain, in Proceedings Iron Ore 2015, pp 437–442 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

In the past two and a half years, over 40 000 metalliferous mining and related services personnel have been trained through an Australian Generic Safety Induction system. This is almost half of AustraliaÆs metalliferous mining related workforce. This remarkable industry acceptance and delivery of safety courses is supported by Acacia Resources, Great Central Mines, Homestake, Newcrest Mining and WMC Resources, amongst hundreds of other mining, exploration and major contracting and services companies. MARCSTA; the Mining and Resources Contractors Safety Training Association (a pro-active not-for-profit self-help group of 24 major contracting companies) developed this generic safety induction. MARCSTA set out to find the æcommon groundÆ necessary to help address the evident safety problems and cost of re-training that were plaguing development of an internationally competitive and productive export industry. The incredible expansion of Australian mining during the decade fuelled a need for out-sourcing, resulting in much larger numbers of contractors on-site. At the same time, changes within Australian legislation, community expectations and the development of huge fly-in/fly-out operations and widespread skills shortages led to a rapid labour turnover and a higher paid workforce. Many Australian mining houses also ran international operations, particularly in South East Asia and head hunted people across the world. The skill levels fluctuated and fell at some local operations. Employers could no longer rely on systematic in-house training of permanent employees to improve safety and productivity as workers could and often did move on. Serious discrepancies in both quality and quantity of safety induction training and work practices occurred. Repetitive, boring and ineffective safety training became an embarrassing and costly burden for companies and workers alike. Then a spate of mining deaths sparked highly publicity, workforce concern and a demand for improvement from government, unions and corporate stakeholders. MARCSTA recognised it had to develop a high-quality safety-training program to satisfy the needs of all employers and be acceptable to others within the industry. This induction system had to be flexible enough to meet differences in legislation between states and industry sectors and be portable to enable cost and time savings for the new transient workforce. Changes in the last two years as a result of evaluating and incorporating various Taskforce inquiries into underground mining fatalities later led to the development of the MARCSTA Underground Safety Induction. This logical development added to the run away success of MARCSTAÆs General Safety Induction and was seen to be essential for many surface mines that were planning to develop underground operations. There are many lessons that MARCSTA learnt during its development that Pacific and South East Asian mining operations can benefit from. The most important of these are the support of stakeholders within industry and the recognition of higher safety and health expectations from workers and government. This goes hand-in-hand with the productivity and return on investment expectations of companies and their shareholders.

Jan 1, 1999

By C Tickell

Achieving occupational health and environmental noise objectives is a major consideration in the planning or operational phase of resource development and industrial projects to meet the needs of the workforce and community and comply with legislative requirements. For material handling systems, ventilation plants, mobile equipment, process plants and fixed infrastructure, noise emissions need to be considered at the design phase. The preferred approach is to provide noise emission technical specifications, but in many cases this is not stipulated. An occupational noise requirement, such as ‘not to exceed 85 dBA at 1 m’, is often provided, but this will not achieve the required occupational or environmental noise objectives and may cause overly stringent requirements when they may not be needed. It should be noted that when developing the technical specification, measuring compliance needs to be taken into account as, in some cases, measuring may be very difficult or even not possible.This paper will discuss the requirements for providing an effective noise specification that ensures the environmental and occupational noise objectives are able to be achieved and that, once installed, compliance can be measured. It discusses planning such as when to set the objective, correlating the appropriate objectives for the environmental and occupational noise requirements, allowing for measurement tolerance, providing a suitable criteria and data format for the suppliers to respond to and methodology to measure compliance. Different phases of a project require different approaches to planning for noise management and these will be discussed in the paper. Examples from 35 years of industry experience will be included.CITATION:Tickell, C, 2016. Preparing effective specifications for occupational health and environmental noise objectives in mining project design and delivery, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 781–788 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By B Zhao

Gas and coal dust, as potential harmful elements (PHEs) produced during mining, are considered two serious threats to the safe mining and the health of miners because of its explosive and pathogenic properties. To solve this problem, compound reagents enhanced water spraying technology was used to control the gas and coal dust in excavation working face in this study, and spray testing platform and wind tunnel were used to investigated the suppression effect for gas and coal dust. In addition, sink test, and agglomeration experiments were also used to analyse its suppression mechanism. Testing results show that the dust reduction efficiencies of compound reagents enhanced water spraying technology for four different particle sizes were 80 per cent, 91.43 per cent, 94.74 per cent and 94.46 per cent, and improved by 14 per cent, 10.86 per cent, 8.42 per cent and 4.25 per cent compared to water spraying. Moreover, the gas suppression efficiency also can be increased more than 20 per cent. Sink test, and agglomeration experiments results show that compound reagent improves the spreading efficiency of the liquid on the surface of the coal by changing its wettability, and this process can not only slow down the desorption rate of gas by forming a water-sealing effect in the coal surface indicated, but also promote the agglomeration of fine-grained coal dust.

Oct 12, 2022

By D R. Anstey

The mining of magnetite iron ore in Western Australia will generate large volumes of waste rock and tailings over many decades. The need to dispose of these materials will result in massive waste landforms that will require significant planning and management. The formation of comparable man-made landforms is relatively common, as exemplified through past practice in gold and iron ore (haematite) mining. Unfortunately, the performance of these landforms, with respect to long-term stability (erosion resistance), the release of low pH seepage water and aesthetic impact, has commonly been disappointing and environmental legacies have been created as a result. Lessons that have been learnt from past, large mining operations indicate that there is a need to rethink the methods of waste disposal and landform development applied to magnetite mining. The environmental compliance criteria applied to magnetite mines for the storage of tailings and waste typically include minimising dust generation (particularly as the tailings and mine waste may contain asbestiform minerals), control of silt, minimising visual intrusion and management of potentially acid forming materials. In addition, the climate of Western Australia and the paucity of both surface and groundwater in the vicinity of the magnetite mines frequently necessitate water consumption to be minimised. This paper discusses the potential to co-mingle magnetite mining waste streams in a variety of ways to concomitantly satisfy the environmental compliance criteria and the operational requirements of the mine. These methods include co-mingling of coarse tailings and waste through dry-stacking, deposition of tailings as a paste, co-disposing of all wastes to form an integrated landform and the co-mingling of all waste streams to produce PasteRockTM (a blend of tailings paste and crushed waste rock). The paper demonstrates how these techniques can be applied to the magnetite mining industry to provide better outcomes than might be achieved using more conventional techniques, currently employed in large-scale mining operations.

Jan 1, 2009

By M Bettison, R Wright, N Taylor

The primary mine planning focus during early study phases of future mining projects is Life of Asset ore production and grade quality, this will always be the situation. While waste schedule optimisation is generally considered in the latter study phases nearing execution for a limited number of schedule periods only and not a true optimisation considering all attributes such as waste destination location, design, cycle time and closure. This can be particularly applicable in large multi-pit bulk mining operations where one approach to meet Life of Asset ore tonnes and grade targets has been to maintain pit development flexibility resulting in large open pit areas and substantial expit Overburden Storage Area (OSA). The value opportunity is to develop a Life of Asset waste schedule source-to-destination optimisation prior to mine development considering all applicable attributes and routinely review throughout the Life of Asset taking account of improved ore and waste knowledge.CITATION:Taylor, N, Wright, R and Bettison, M, 2018. Utilising mine planning to deliver closure landforms through productive movement, in Proceedings Life-of-Mine 2018, pp 96–99 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By T Gibbons, M Korte, C Brent, K Runge

The Barrick Osborne concentrator has gone through a number of upgrades since commissioning and steadily increased production from the original 119 t/h design capacity to 265 t/h milling throughput in 2008. This was achieved incrementally over several years, by maximising operating efficiencies, in order to minimise capital expenditure, and take advantages of economies of scale; but more importantly it was reached with no measurable loss of recovery. Osborne currently processes a blend of under- ground with open pit material from the nearby Trekelano deposit. Following primary/secondary crushing, the material is processed through a rod/ball mill grinding circuit ahead of rougher/scavenger flotation that produces a copper concentrate.Osborne was seeking a further increase in plant throughput of the order of 15 per cent, but at more sustainable levels of secondary crusher plant utilisation. In early 2008, Osborne contracted Metso Minerals Process Technology Asia-Pacific and South America (MMPT) to review the entire process from run-of-mine feed to final copper concentrate. This review would be done concurrently, with surveys of both the crushing/ grinding and flotation circuits being performed at the same time. The outcome would be a steady-state model of the complete flow sheet allowing the crushing/grinding model to interact with the flotation circuit model such that overall process optimisation was possible. Two key outcomes for the operation are exploration of the operating limits of the currently installed plant, and projection of the logical next stage of potential capital plant expansions. This paper covers Part B or the flotation component of the project. A separate paper discussing Part A or crushing and grinding is also being presented at this conference. Surveys of the Osborne flotation circuit were performed along with a comprehensive review of the cell characteristics including measurements of the gas and froth phases of individual flotation cells. These data resulted in a size-by-size floatability component model of the complete circuit. This circuit model was then used to perform steady-state simulat- ions to evaluate options to improve both overall circuit and individual cell performance. The grinding circuit model discussed in a separate paper or Part A of this project was then used interactively with the flotation circuit model to recommend the best operating regime to maximise overall efficiency. For example, the balance between increased crushing and grinding costs versus higher copper recovery and final concentrate grade. Due to changes in market conditions in the fourth quarter of 2008, the focus was shifted to prioritising operational changes rather than capital expansion modifications, in order to improve circuit performance.

Jan 1, 2009

By H Fletcher

Iron Ore Holdings Ltd (IOH) is an emerging junior iron ore company that is actively developing projects in the Central and Western Pilbara region of Western Australia. IOH commissioned URS Australia Pty Ltd (URS) in mid-2008 to prepare environmental assessment documents for the Phil’s Creek Project, which was rapidly moving into the development phase. This project comprised a small open cut iron ore mine that was expected to deliver approximately seven million tonnes over a five year mine life.IOH faced several challenges in the environmental assessment process for the Phil’s Creek Project. Although the Phil’s Creek Project attained approval but has now been placed on hold, it is a useful case study to discuss these challenges and how IOH addressed them. Several important lessons were learned through this process that can assist other proponents in addressing environmental challenges in a constructive and proactive manner.One major challenge faced by IOH related to the endangered northern quoll (Dasyurus hallucatus). Another challenge was the unusually high species richness of troglofauna recorded within the project area, with several species initially known only from within the proposed pit footprint.Meeting and overcoming these challenges has provided IOH with an increased understanding of the level of input required for consultation with government departments regarding environmental assessments, and this should stand the company in good stead for developing future tenements. Challenges in regards to the environmental assessment process may be faced during future developments, but IOH’s experiences to date and the lessons learned from the Phil’s Creek Project, will help pave the way for successfully overcoming them.

Jul 11, 2011

By S Li, Y Lei, X Wu, C Ma, W Q. Zhang

The failure of roof of thin bedrock working face under loose aquifer in a coalmine can lead to water-sand inrush disaster. Based on the accident of water-sand inrush in 30108 working face of a mine in Shaanxi province, China, the mechanism of water-sand inrush is theoretically analysed. The process and critical conditions of water-sand inrush in working face are reproduced by numerical simulation where the bedrock thickness is 20 m, the clay layer thickness is 40 m and the mining height is 6.5 m. The study found that under the condition of thin bedrock and thick clay layer, the characteristics of the clay layer have a significant inhibitory effect on the development of the fractured zone, and the development of the water-conducting fractured zone is incomplete and insufficient. However, in the process of continuous mining of multiple adjacent working faces, the strength of the clay is gradually reduced by the influence of mining and the erosion of water, and the height of the fractured zone is gradually increased. In the subsequent mining process of the working face, the roof is more likely to be cut-off and lead to water-sand inrush. From the initial failure of the clay to the final crack directly through the surface, the shear strength of the clay is reduced by about 52 per cent. Further simulation found that in addition to the characteristics of the clay layer itself, the main factors affecting the water-sand inrush in the working face caused by overburden failure also include the difference in bedrock thickness and strength, and the difference in coal seam mining height. With the increase of bedrock thickness, the development height of the fractured zone increases gradually with increases of bedrock thickness when the cutting failure of overburden rock no longer occurs. With the increase of mining height, the height of water flowing fractured zone also increases, but the cracking ratio gradually decreases. Therefore, it’s of great practical significance to systematically study the mechanism and critical conditions of water and sand inrush in mines and the main influencing factors for preventing similar accidents in mines with similar conditions.

Nov 29, 2022

In todayÆs evolving and globalised world, mining companies are being pressured to move beyond compliance towards long-term sustainability and sustainable development. Companies are expected to æengageÆ communities and measure the success of these engagements without a clear understanding of æhowÆ to do this. This move, away from compliance, develops more of a focus on sustainability and æcommunityÆ social responsibility rather than corporate social responsibility. This shift leads to the development of world-class projects that provide sustainable development for people, reduce the incidence of costly delays, and promote good global citizenship for companies. The process of æengagingÆ communities in mining project design and development leads to sustainable development, a stronger license to operate, and a reduction in social and political risk. To create this mutually beneficial relationship between communities and companies, communities must be æengagedÆ in the project development and risk assessment processes as early as possible, preferably during the exploration or the concept phases. How to create this æengagementÆ and manage this risk will be discussed.

Jan 1, 2007