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By J Allen, B Oats, S Palaniandy, M Lollback

The Julius Kruttschnitt Mineral Research Centre has conducted an intensive VertiMill® (VTM) survey program at the Cannington mine concentrator as part of the ‘collaborative research in stirred milling technology’ program funded by Metso Minerals. Since 2003, Cannington has progressively added grinding capacity into the circuit through VTMs operating in secondary and regrinding duties. Cannington was one of the first mines to adopt this technology in secondary duty by installing two VTM-1500-WBs as part of a capacity expansion to produce sub-100 µm rougher feed. Subsequently, an additional VTM-800-WB was installed in the lead regrind circuit to prepare sub-20 µm cleaner stage feed.Several surveys were carried out to evaluate the VTM performance over a range of changed conditions. Among the key changes in operating variables were circuit power draw, feed rate and water addition to the bottom of the mill. The average specific energy for secondary duty was 3.7?kWh/t. The lead and zinc regrind mills consume 8.1 and 15.3 kWh/t respectively. Generally, the VTM installations have successfully prepared feed for rougher and cleaner circuits by reducing the top size into the floatable regime with steeper particle size distribution, which has led to enhanced recovery. The survey results show the success of VTM installations in secondary (receiving feed from autogenous circuit) and regrind duties.CITATION:Palaniandy, S, Powell, M S, Hilden, M, Allen, J, Kermanshahi, K, Oats, B and Lollback, M, 2014. VertiMill® performance updates in secondary and regrind duties at Cannington mine, BHP Billiton, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 263–272 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By A E. Waltho, W J. Shaw

Predicting the physical characteristics of various ore types has for long been a difficult problem during mining. Grade control practices tend to concentrate on the chemical grade of the ore. Estimation of physical characteristics such as beneficiation behaviour is commonly limited to the simplistic application of historical averages. Large amounts of geochemical data are often gathered during the exploration and mining stages of a project, especially in ferrous and base metal deposits. In addition to the elements of principal economic interest, samples are often analysed for suites of gangue constituents to determine whether the mineralisation lies within target specifications. This multi-element data is often put to no other use than this simple chemical classification, yet it may present the geologist or metallurgist with valuable insights into the mineral content and physical characteristics of the deposit. Normative mineral estimates have been used as a method for characterising igneous rocks for almost 100 years. The method establishes and applies a set of sequential rules, by which the chemical components of a sample are assigned to mineral components. Provided that it is possible to make some realistic assumptions about the mineral species likely to be present in a rock unit or deposit and their paragenesis, this approach can be extended to a variety of mineral deposits. The geochemical data that are routinely collected when, for example, drilling iron ore and base metal deposits, can be used to derive estimates of normative mineral content. These estimates can be used to characterise physical or metallurgical aspects of the ore, such as density, beneficiation behaviour and metal recovery. This paper examines the application of normative mineral estimates to a variety of practical resource characterisation problems. The potential for predicting the lump and fines proportions of iron and manganese ores is also discussed.

Jan 1, 1999

By N Jeannee, L Rattmann, M W. N Buxton, A deJong, K Nienhaus, A Soares, P Graham, A Korre, J Benndorf, D Buttgereit

The flow of information, and consequently the decision-making along the chain of mining from exploration to beneficiation, typically occurs in a discontinuous fashion over long timespans. In addition, due to the uncertain nature of the knowledge about deposits and the inherent spatial distribution of material characteristics, actual production performance often deviates from expectations. Reconciliation exercises to adjust mineral resource and reserve models and planning assumptions are performed with timely lags of weeks, months or even years.The key concept of real-time mining promotes a change in paradigm from discontinuous intermittent process monitoring to a continuous process and quality management system in the resource extraction process. The framework includes a real-time feedback control loop that rapidly links online data acquired during extraction at the mining face, material handling and processing with a sequentially updatable resource model. This will allow near real-time optimisation of decisions related to long-term planning, short-term sequencing and production control.The proposed framework integrates the following building blocks in a holistic manner: automated sensor-based material characterisationonline machine performance measurementsunderground navigation and positioningunderground mining system simulation and optimisation of planning decisionsupdating techniques for resource/reserve models.This paper introduces the real-time mining concept and the building blocks and provides a review of the state-of-the-art. Technological readiness of necessary building blocks is assessed, and critical gaps for further technology development are identified. The value added is illustrated by means of a case study.CITATION:Benndorf, J, Buxton, M W N, Nienhaus, K, Rattmann, L, Korre, A, Soares, A, deJong, A, Jeannee, N, Graham, P, Buttgereit, D, Gehlen, S, Eijkelkamp, F, Mischo, H, Sandtke, M and Wilsnack, T, 2015. Real-time mining – moving towards continuous process management in mineral resource extraction, in Proceedings Third International Future Mining Conference, pp 37–46 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By P Holtham, K Duffy, W Valery, A Jankovic

In the face of increasing energy costs, limited water resources, more stringent legislation, and lower feed grades, the mining industry is searching for more sustainable technologies and practices. Metso Process Technology and Innovation (PTI) is undertaking a research project, ‘improving the resource and eco-efficiency of mining operations’, to help the industry meet these challenges. The project is investigating alternatives in mining and processing that reduce energy and water consumption, minimise emissions and waste, and maximise the value recovered from the deposit. The targets are to reduce energy usage by more than 30 per cent and greenhouse gas emissions by more than 50 per cent compared to current practice.Key areas of interest were identified across mining and processing operations. These were grouped into the following interrelated work areas for investigation: high intensity selective blasting, in-pit crushing and conveying, preconcentration, energy efficient comminution circuits and technologies, coarse particle flotation, and water recovery optimisation. Investigations have included reviews of industrial data, modelling, simulation, and laboratory and pilot scale trials. In some areas industrial scale trials will commence shortly. This paper discusses the investigations and key findings from the project so far; highlighting the possibilities for reducing energy consumption, water usage and carbon emissions. A particular mining process may incorporate any combination of the alternatives identified and requires tailored solutions based on a detailed understanding of the ore deposit, the process and local conditions. The focus is on improving resource efficiency; creating more value with less impact and consequently a better economic return from the available resource. Technologies exist today that can transform mining into a more efficient industry for tomorrow.CITATION:Duffy, K, Valery, W, Jankovic, A and Holtham, P, 2015. Resource efficient mining processes of tomorrow, in Proceedings Third International Future Mining Conference, pp 227–238 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By O Bascur, A Soudek

Large metallurgical complexes are substantial users of energy, water and assets. To improve the effectiveness of energy and assets the quality of the data and events become paramount for real-time operational management. A lack of resources at the local operations and at the enterprise makes it impossible to process the sea of information and many projects have failed. As such, a novel approach for implementation of continuous improvements at the local level and innovations at the strategic level was implemented at all operating plants at Anglo American Platinum. Sixteen concentrators, three smelters and two refinery process systems were integrated to scale the information for manufacturing services at the local and enterprise level. The new capability of an enterprise real-time monitoring and diagnosis software infrastructure was available to implement many business strategies in tandem. Mineral and metallurgical processing knowledge is used to simplify the implementation of the data model. As such, asset monitoring, energy, production and process control management were implemented in an integrated approach reusing the same data but with different context and time horizons to have a standard methodology for local root cause analysis. This paper will highlight a sustainability management approach to change and empower the local and strategic team to collaborate using a new approach for adaptive reporting and condition-based event management and notifications. The results based on the integrated and collaborative team efforts will be presented. OSIsoft Plant Information system was installed and configured to achieve a targeted reduction in energy consumption of 15 per cent by 2015.CITATION:Bascur, O and Soudek, A, 2014. Implementation strategies for energy effectiveness and sustainability – example of Anglo American Platinum, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 101–108 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By A McGann, P J. Coghill, D Miljak

"It is widely accepted that bulk ore sorting could provide a step change in processing of low-grade ores. For this to be achieved a rapid, accurate bulk sensor of grade is required as well as sufficient natural variation of grade in the ore stream. CSIRO trialled a magnetic resonance (MR) sensor capable of measuring chalcopyrite, and by inference total copper grade, on the 1300 t/h Ridgeway portal conveyor. The gauge produced an unprecedented set of data down to a 1 t scale for months at a time. This paper analyses the measured variation and compares it to a simple model derived from the bore core data and mixing within the block cave mine.The model of the small-scale (<1000 t) variation is developed using fractal methods which have successfully been used in the past for copper porphyry deposits showing a power law or near power law distribution of copper grade and vein sizes. These fractal distributions have two features highly favourable for segregating ore, a large proportion of low-grade pods and the large-scale spatial clustering of grade. We show the presence of fractal ordering in bore core data at short range in the Cadia Ridgeway porphyry deposit and measure its persistence in the crushed rock produced by the Ridgeway block cave mine over one month. The model is then extended to demonstrate the effect of varying head grade, mixing and pod (or diversion) weight on bulk sorting efficiency.CITATION:Coghill, P J, Miljak, D, McGann, A, 2016. Modelling Grade Variation in Crushed Ore at Cadia Ridgeway and Its Potential Consequences for Bulk Ore Sorting, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 77–88 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By A M. Myrvang, B Nøst, N Q. Trinh, I S. B Bergh

The iron ore producer Rana Gruber AS is situated in northern Norway just below the Arctic Circle, and has been producing hematite and magnetite concentrates for more than 60 years. Since the late 1990s, the major part of the production comes from a sublevel stoping underground operation after many years of open pit mining. Despite moderate mining depth, the operations have experienced considerable rock stress problems due to quite high tectonic, horizontal stresses. To manage the problems, comprehensive rock mechanics investigations have been carried out by SINTEF, a major contract research organisation. This has included in situ rock stress measurements, laboratory investigations and numerical modelling. Based on this and practical experience, satisfactory design of vertical and horizontal pillars was achieved. At depth, the ore width increases from 30–40?m to more than 100?m. This, together with a major planned increase in production, called for a change of the mining method. After thorough investigations and considerations, it was decided to change to sublevel caving, very much like the LKAB system. The development of the new system has been closely followed up by rock mechanics measures, including 3D numerical modelling and comprehensive monitoring of deformations and rock stress changes. To achieve a satisfactory caving of the hanging wall, all vertical and horizontal pillars in the sublevel stoping area had to be removed. This has been a challenging task, and the development of the caving has been slow until recently. However, now the caving develops satisfactorily.CITATION:Bergh, I S B, Trinh, N Q, Myrvang, A M and Nøst, B, 2014. From sublevel stoping to sublevel caving at Rana Gruber, Norway – rock mechanical aspects, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 323–330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By M Zanin, E Chan, D Xu

An experimental design has been developed to investigate the relative influence of distinct pulp and environmental properties on froth stability in the flotation of a typical porphyry copper ore. In particular, factors such as frother and collector type, feed particle size (P80), solids per cent, composition (chalcopyrite and pyrite content), as well as grinding environment (mild steel versus stainless steel, high and low pH) have been varied in a controlled manner, and the resulting froth stability evaluated. A previously developed froth stability column, based on the Bikerman approach, was used to measure the froth height and half-life in each test. The relative effect of each factor is presented here on a comparative basis. It is shown that frother type is the most important factor, with marked difference in froth stability when switching from methyl isobutyl carbinol (MIBC) to glycol based frothers. Solids per cent and particle size also play a significant role. The grinding environment had lesser effect on the resulting froth stability, although mild steel grinding gave higher froth stability compared to stainless steel grinding. The experimental evidence supports the hypothesis that in porphyry copper flotation the grinding environment influences surfaces oxidation, pyrite activation and the extent of hydrophobic particles reporting to the froth phase. This has an indirect effect on the resulting froth stability, which is however small if compared to the other factors. This work is still in progress, and extension to other mineral systems is planned. However, some insights are offered to operators on the parameters which are more likely to have an impact on froth stability in copper flotation plants.CITATION:Zanin, M, Chan, E and Xu, D, 2014. Empirical evaluation of factors affecting froth stability in copper flotation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 193–200 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By B Maybee

In underground mine planning, many potentially value-eroding decisions are made due to a lack of time and proper evaluation practices. The information required for mine planning decisions goes beyond external sources of uncertainty that are recognised by typical evaluation techniques used in the mining industry, to include technical factors (eg mine development layout) and the ability of a mineral extraction project to achieve its anticipated production levels. Due to the individual characteristics that define underground mining projects, each will exhibit a different risk profile, and thus advanced optimisation and evaluation techniques are required to capture this information.As underground mine planning tools become more sophisticated, mine planners have the capacity to investigate numerous mine sequencing options to identify the best strategy for a given project, creating higher value for shareholders. This paper describes a risk-based evaluation methodology (RbEM) that accounts for financial and technical risk in the evaluation of underground mining projects. While the use of the RbEM has been described in previous works, no benchmarking of the benefits that can be realised from a change in those decisions that are made early in the process has been undertaken. To show the benefits that can be achieved from using the RbEM, this paper updates a case study to which the RbEM was applied, and takes a retrospective look at whether additional value would have been gained by following the strategic recommendation of the RbEM versus a typical optimisation exercise that aims to maximise the net present value.CITATION:Maybee, B, 2012. Can a risk-based evaluation provide a more valuable mine design?, in Proceedings Project Evaluation 2012 , pp 53-58 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By C D. Strickland

Western Australia (WA) has been a significant world producer of titanium minerals (rutile, ilmenite and leucoxene) and zircon for over 55 years. In 2010, despite global difficulties, WA accounted for 12 per cent of world production for zircon, ten per cent for ilmenite, and eight per cent for rutile. With downstream processing, titanium minerals (ilmenite, rutile, leucoxene) and zircon exports for 2010 were valued at $511 M (Department of Mines and Petroleum, 2010).Production is dominated by two areas of the Perth Basin, namely the Eneabba and the Bunbury-Capel regions, which are located 240 km north and 200 km south of Perth respectively. Mineralisation is within Cenozoic beach or near shore dune deposits at three broad altitudes related to the present coastline, and two older higher sea-level still-stands. The titanium-zircon minerals presumably were derived from the underlying Mesozoic sediments of the Perth Basin. Contrary to expectations, age dating suggests that the ultimate source of most of this mineralisation was not the adjacent Yilgarn Craton. With the cooperation of industry, the Geological Survey of Western Australia has mapped all known significant titanium-zircon mineralisation within the Perth Basin. This mapping has identified ‘strategic mineral resource protection areas’ that should be set aside for future mining, ‘sterilised’ and ‘mined’ areas that generally do not restrict land use options, and ‘possible strategic resource areas’ which have exploration potential for hosting titanium-zircon mineral deposits.The Perth Basin is currently undergoing rapid residential and industrial development. By informing all stakeholders of the locations of potential mining areas, the titanium-zircon mapping has the ability to reduce future land use conflicts, and facilitate sequential land use planning. Appropriate planning measures are being implemented to ensure that the Western Australia’s titanium-zircon minerals industry remains strong and viable in the future.

Oct 5, 2011

Upgrading of Indonesia's Bauxite by Washing Method There were eight bauxite samples used in this research, three samples from Kijang contain total SiO2 18.36 - 29.16 per cent, Al2O3 40.12 - 48.36 per cent, Fe2O3 4.27 - 5.13 per cent, one sample from Tayan, contains total SiO2 4.69 per cent, Al2O3 38.95 per cent, and Fe2O3 19.67 per cent, and four samples from Mempawah contain total SiO2 33.5 - 44.8 per cent, Al2O3 29.8 - 35.9 per cent, Fe2O3 7.29 - 9.88 per cent. All of those bauxite ores have not fulfilled the requirement for Bayer process yet; therefore simple up-grading using a rotary drum scrubber is needed. The scrubbing process was carried out with time variable up to 60 minutes with solid percentage applied was 50 per cent and rotary speed was set up 30 rev/min. The bauxite was washed by following steps: scrubbing, screening, drying, and finally it was analysed to show chemical content. The washed bauxite produced has size fraction that is retained on the 1.7 mm of screen opening. The result of the research shows that the higher alumina content of the raw bauxite, the longer washing time is needed moreover the higher quality of the washed bauxite is produced. The highest alumina content of the washed bauxite was 53.67 per cent with the alumina recovery was 89.66 per cent and the concentration ratio of 84.80 per cent was achieved within 20 minutes of washing time of the raw bauxite (Al2O3 48.36 per cent). The washed bauxite resulted from this research is suitable as a raw material for Bayer process.

Sep 13, 2010

By M Fahey, A B. Fourie

Over the past ten years, the mining industry has witnessed the introduction of a new and innovative mine filling technique known as paste fill, which consists of placing full stream tailings with small amounts of binder and water into underground stopes. Paste fill has benefits over traditional backfill methods, such as higher solids contents than hydraulic fill and easier transportation than rock fill. From a geotechnical perspective, the behaviour of very fine material in a fully saturated state can be complex, particularly when binder is added. Previously, there has been no rigorous solution to understanding the paste fill deposition process, resulting in uncertainty regarding critical aspects such as barricade load calculations. This uncertainty has the obvious consequences of potential barricade failures (including at least 12 over the past four years), and for many operations attempts to deal with this uncertainty has led to excessively conservative filling schedules, restricting production. This paper presents an application of Minefill-2D, the first rigorous model capable of representing the paste fill deposition process. The model couples the processes of material accretion, consolidation and cement hydration to calculate the distribution of stress around a stope (including the total stress applied to barricade structures) during filling. Minefill-2D is a finite element numerical program, which has been verified using laboratory element tests, centrifuge tests and in situ measurements (Helinski, 2008). The authors present a sensitivity analysis, carried out using the model, to demonstrate some of the critical and less critical aspects relating to paste backfill deposition. The results of this sensitivity analysis are used to devise a fill management strategy that can be utilised to minimise the risk of barricade failures and maximise fill rates where appropriate.

Jan 1, 2008

By S Rogers, D Stead, E Eberhardt

The last decade has seen a major increase in use of the discrete fracture network (DFN) approach applied to cave mining problems, often integrated within more complex geomechanical simulations. Because the value of the DFN model directly depends on the quality and quantity of available field data, there is the need to apply dedicated mapping procedures to collect sufficient structural data at the required engineering scale. This paper attempts to address several key questions about DFN modelling; for example: are current methods for fracture mapping suitable for DFN modelling? What are the critical parameters that we need to measure and what do we need to change in the current practice? Particularly at the earlier stages of a cave project, engineers may have to account for the lack of appropriate data, which manifests itself in the form of increased uncertainty and the difficulty to characterise variability in an objective manner using a limited set of data. DFN models could in principle be generated using limited data by assuming statistical distributions for the sampled parameters; however, engineers would need to be aware of the implications that such limited knowledge (and increased uncertainty) would have on stability analysis, fragmentation analysis and mine design. When used correctly, a DFN approach offers practitioners the opportunity to:maximise the use of fracture data collected from mapping of rock exposuresgenerate more realistic synthetic rock mass modelsprovide estimates of natural fragmentation that also account for rock mass variability.CITATION:Elmo, D, Eberhardt, E, Stead, D and Rogers, S, 2016. Discrete fracture network modelling – importance of accounting for data uncertainty and variability, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 845–852 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Y Durkheim, P Saunier, L Ameglio

"In the last decade Afitex developed the Draintube™ geocomposite, which provides simultaneous drainage and waterproofing functions. This new type of drain tubes planar geocomposites (DTPG) differs from other geocomposites as the drainage core is composed of multiple corrugated and perforated pipes instead of biaxial or triaxial nets. It is furthermore associated with needle-punch stitched layers of non-woven geotextiles, which act either as capillary mediums or as filters.In this paper, the structure of the Draintube™ drainage composite is presented along with its key properties and the drainage mechanism associated with its particular structure.The relevance of this kind of structure is then reviewed based on past and current laboratory bench evaluations and field installations for mining applications such as the covering of acid rock drainage (ARD) tailings for the Central Manitoba Mine (Canada) site-rehabilitation; and as a pregnant solution collection layer in heap leach pads.Some of the demonstrated critical advantages of Draintube™ in the mining industry are as follows: reduction of the thickness, hence lower volume of granular drain layers improvement of fluid and gas collection and reduction of the hydraulic load reduction of secondary collector network mechanical protection of the sealing membrane fast and economical installation of interlifts stability under extreme conditions (compression, temperature, pH) increased stability of entire covering system and reinforcement of protection of dykes filtration of the covered material customised drainage positive connection of the geocomposite to collector pipes enable leaks detection (using a conductive textile layer) with an electrical test.CITATION:Saunier, P, Ameglio, L and Durkheim, Y, 2015. Tubular drainage and lining geocomposite for mine tailings and heap leach pads, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 297–304 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 27, 2015

By S Bluhm, R Funnell

Creative mine-designs are constantly being applied in the deep platinum mining industry in South Africa. Recently, this has resulted in deep hot mine-designs including room and pillar, bord and pillar or stall and pillar layouts and the use of in-stope trackless mechanisation. In these mines, the ventilation systems use refrigerated air and high fan pressures and as a result ventilation leakage can have a huge impact. Leakage is a serious impediment to cost-effective operation and potential leakage in future projects is a major factor in judging project viability. This paper describes certain mine layouts and quantifies the extent of the leakage. Based on typical field data, a range of seals from ævery poorÆ to ævery goodÆ was defined and used to estimate overall leakage. Within these mine networks the ventilation pressure, temperature and density all vary significantly and with the multiplicity of leakage paths it was necessary to make use of the VUMA-network simulation package. For the examples examined, the leakage was found to be up to 85 per cent for æpoorÆ category seals and up to 50 per cent for ægoodÆ category seals. The total air flow (and refrigeration) requirements grow exponentially with strike distance due to the compounding effects of higher pressure and more leakage paths. It is shown that beyond certain depths and strike distances the leakage will become so great that it will be impossible to operate cost-effectively û even with ægoodÆ seals. Indeed, in these examples the projects were not considered viable in their original format because of the high ventilation-cooling costs and the mine-designs were modified to include footwall drive systems û the cost of which was justified by the reduced strategic risk to operating ineffectiveness due to leakage.

Jan 1, 2005

By Y Li, D J. Williams, E Topal

A mine waste rock dump does not have any intrinsic value, yet is an inevitable structure in surface mining operations. Since the purpose of mining is to maximise profit, possible expenditure reduction in hauling waste rock to the dump, which can represent up to 50 per cent of the total operating cost, is highly desirable. Apart from cost, potential acid mine drainage (AMD), due to seepage from surface waste rock dumps containing reactive waste rock, could threaten the ecological balance, drinking water supplies and irrigation systems downstream from a mine site. In order to minimise these potential risks, selective placement of benign and reactive waste rock, and the encapsulation of reactive waste rock by benign waste rock, need to be carried out during the construction of the rock dump.In this paper, a new methodology, based on mixed integer programming (MIP) is developed to manage waste rock dumping. The model aims to minimise waste rock haulage costs by locating the optimum destination(s) for each waste rock block, while at the same time controlling the placement of reactive waste rock to minimise the potential for AMD. Tests on small-scale virtual data demonstrated that the model is capable of dealing with selective placement of different waste rock types, encapsulating reactive, potentially acid forming (PAF) waste rock, and stockpiling benign waste rock for encapsulation and rehabilitation purposes. The solution time for the MIP model is far less than the traditional manual approach, and the resulting schedule is up to 46 per cent more cost effective.CITATION:Li, Y, Topal, E and Williams, D J, 2012. Mathematical approach for better mine waste rock dumping management, in Proceedings Life-of-Mine 2012 , pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By P Corbett, P Sheffield

Springvale Mine is an underground coal mine in the western coalfield of New South Wales which utilises retreat longwall mining technique. The mine encountered significant gateroad floor heave issues during retreat of LW415. Floor heave has subsequently impeded longwall advance as well as longwall bolt up and recovery to some extent during the extraction of the next five longwalls. Floor heave at Springvale Mine develops throughout the lifecycle of the mine roadways, and is most prevalent in longwall gateroads. Floor heave has been measured as early as 2 weeks after roadway development and continues to develop through the post-development phase, with a rapid increase in close proximity to the longwall face. This paper presents a case study of the evolution of understanding of floor heave behaviour at Springvale Mine based on geotechnical characterisation, an intensive convergence monitoring program (roof and floor movement) and spatial correlation of monitored locations with longwall face position. The analysis considers previously known factors contributing to floor heave including mining depth, geological and physical properties of the rock mass and mine design geometry. Investigation results indicate a strong correlation between floor heave magnitude and roof dilation magnitude, geophysically inferred faulting in underlying strata, areas of localised stress concentration and mine roadway dimensions. This paper also discusses the predictive model which was developed as a result of the study, which is now the basis of the floor heave removal program used to manage roadway convergence at the mine. Floor heave monitoring, prediction and management strategies (including floor reinforcement and removal) are also discussed. CITATION:Sheffield, P and Corbett, P, 2018. Managing floor heave in an underground longwall coal mine, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 78–94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By Y M. Lee, Y Hong, B C. Kim

Since sintered ore is the primary source for producing molten iron in the blast furnace process, maintaining stable quality despite the utilisation of low-grade iron ore is crucial. However, conventional analysis methods, such as chemical composition, ore size distribution and types of iron ore, have limitations in developing the utilisation of new low-grade iron ore and predicting sintered ore properties. Sintered ores are formed through a complex melting process of granule particles consisting of iron ore, flux and fuel. Consequently, it has been investigated that analysis methods which apply the reactive properties of iron ore to predict sintered ore characteristics. In this study, we estimated the properties of iron ore by simulating the assimilation process of coarse ore, which influences the bonding strength of sintered ores and quantifying the degree of assimilation reaction. Pseudo particles were formed by granulating coarse ore (1–3 mm) with adhering fines, which act as primary melts and sintered at 1623 K. The bonding strength of individual sintered ores, formed from 11 different types of iron ore, was measured using a simplified Tumbler Index (TI) test and each value was indexed as the Iron ore Reactivity Index (IRI). By investigating the relationship between the degree of assimilation depending on iron ore properties and the characteristics of sintered ore, we demonstrated that sintered ores formed from more reactive iron ore exhibited stronger bonding strength. Moreover, when blending conditions resulted in a higher Iron Blending ore Reactivity Index (IBRI), the physical properties of sintered ore improved. The development of this analysis method is expected to not only enable careful consideration of iron ore usability but also allow for the advance prediction of sintered ore qualities by deriving the IBRI.

Sep 18, 2023

By T Takayama, M Matsumura, Y Konno

The steel industry accounts for 14 per cent of domestic CO2 emission in Japan, and iron ore sintering process occupies approximately three per cent. While Fe content in iron ore is gradually decreasing. So, the amount of concentrated iron ore will increase in the future. We have focused on magnetite concentrate as sinter materials, because magnetite can be easily magnetically beneficiated. However, it is experienced that blending magnetite ore resulted in increasing Fe2+ component in the iron ore sinter, which results in lower reducibility. Therefore, promoting the oxidation reaction from magnetite to hematite in the sintering process is countermeasure for reducibility. In addition, this promotion causes increase of oxidation heat, which results in high sinter strength and reduction of coke. It is assumed that the oxidation of magnetite tends to proceed in the cooling stage, where the oxygen partial pressure increases after the combustion of fine coke, but there are few studies on the effect of heat profile, especially cooling path. The purpose of this study is to design the effective sintering heat profile to promote oxidation of magnetite ore, especially, to investigate the effect of cooling path on sintered ore microstructure. In this study, magnetite ore and magnetite reagent were respectively mixed with calcium carbonate reagent. Then the mixed samples were pressed and formed into cylindrical tablets for simulating the adhesive layer of a pseudo particle. Through examining influence of maximum temperature and cooking rate on oxidation reaction of magnetite, we confirmed that the oxidation reaction of magnetite is suppressed at above 1350°C for maximum temperature, compared to 1300°C. Sintering at lower temperature is desirable because hematite is stable below 1350°C in the Fe2O3-CaO phase diagram.

Nov 8, 2021

Current attitudes by exploration companies towards working on another party's exploration permit or equivalent vary widely. That this is so is due to the virtual absence, on the one hand, of anything in the mining legislation in any jurisdiction that establishes what are the exclusive rights to explore, as opposed to apply for a mining tenement, that the grant of such an authority conveys on the holder, and on the other hand, of any code of ethics or set of guidelines to proper practise. By contrast, in most states and territories, if not all, it is an offence to enter onto a mining tenement, other than to cross it, without the consent of the holder, although until recently most field personnel would have been unaware of this and most explorers would have transgressed at one time or another. A similar vacuum exists where aerial surveys are concerned. There are in fact no guidelines. It has always been assumed that a party wishing to carry out such a survey was free to do so, without even an obligation to notify the holders of any tenements or permits in the area to be surveyed, let alone make available to them any data from the survey. Concepts of 'geophysical trespass' now being tested in the US also raise the possibility that data won from adjoining ground using geophysical techniques may be privileged. Attitudes now appear to be changing. In the absence of legislation or any code of practise, what does the industry regard as ethical behaviour? Do we need to define the rights and obligations of various parties more clearly, and if so, what should they be and to what extent will it be necessary to confirm them by legislation as opposed to adopting a code of practise? Will the existence of such a code in fact improve corporate practise?

Jan 1, 1995