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By N van Aarde, B A. Moore, S van der Merwe

Frequently materials handling operations are compromised by transfer chute problems ranging from high wear rates, blockages and ineffective loading of the downstream conveyor. This paper will present the design flow implemented to overcome problems in two case studies utilising discrete element modelling incorporating material characterisation.Material testing is relevant in achieving a valid discrete element method (DEM) simulation model and subsequently a valuable design tool for transfer chute assessment and design. It is well recognised that in the current growth and demand for mineral resources, leading to ever increasing conveyor capacities associated with export terminals and mineral processing facilities that transfer chutes are a key focus point. The successful performance of the transfer chute is also dependent on operating with a ærobust rangeÆ of material flowability and handling characteristics. This requirement is crucial in accommodating mineral ores from developing resources, which are often more friable and stickier than in past decades.This paper will include details of chute installations associated with iron ore and coking coal, from the DEM simulations through to the performance of the installed and commissioned plant.CITATION:Moore, B A, van der Merwe, S and van Aarde, N, 2013. Implementation of advanced transfer chute designs, in Proceedings Iron Ore 2013 , pp 445-450 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By M Yahyaei, F Reyes, R Lage, V Jokovic

Equipment wear is strongly related to the performance of grinding circuits. In particular, SAG mills are subjected to the wear of their shell liners and grates. Changes in lifter height and face angle impact mill performance, while classification at the mill discharge is also affected as grates wear out. Moreover, liner mass loss caused by wear affects how operators interpret readings of sensors such as load cells or bearings pressure. Automating and optimising grinding circuits under these constrain becomes challenging due to the nonlinear and dynamic nature of the system. The operation of SAG mill grinding circuits remains largely dependent on human intervention, which frequently results in inconsistencies in performance across shifts, reflecting the operator’s personal preferences, experience, and other human factors. The influence of human factors can be reduced by careful training of operators as well as by automation using advanced supervisory control. The latter approaches could benefit from the development of dynamic process models that consider the effects of wear on the performance of equipment over time. This paper presents detailed industrial data showing the effects of wear on SAG mill performance. Additionally, a dynamic SAG mill model that accounts for these phenomena is proposed and demonstrated in a simulated environment. This model is shown to mimic the effect of wear on the performance of industrial scale mills and the operational constraints they are subject to, thus extending traditional SAG mill models. Incorporating wear into modelling and simulation platforms can improve the understanding of the effects that wear can have on the performance of key assets in comminution circuits and may allow the development of more robust model-based advanced process control strategies.

Aug 24, 2022

Mount Isa Mines' Hilton Mine was brought into large-scale production in 1990/91 at a time of sharply falling metal prices. To ensure the operation's survival and eventual prosperity there was an urgent need to reduce operating costs and increase revenue. A target of a 40 per cent increase in productivity over five years was set. Strategies to obtain the required improvements were developed on the basis of greater involvement and increased contribution from the workforce, major changes to the mining methods and the development and application of new technology. This paper describes the organisational, operational and technological changes that have been implemented at Hilton and presents the results achieved to-date.

Jan 1, 1993

By Schofield D

The problem of production scheduling is sufficiently complex to negate the use of many conventional optimising techniques as there are numerous and diverse factors that must be considered when trying to produce an optimal schedule. These factors include: grade distribution, orebody geometry, production rate capacity, processing constraints and market price of the minerals amongst a variety of others. In addition it may be observed that many of these factors incorporate a degree of uncertainty and any schedule produced must inevitably consider risk as a primary consideration. The very nature of the problem has limited the use of conventional optimisers. Genetic algorithms use methods based upon evolution and natural selection to produce `optimal' solutions to complex system problems. They are extremely flexible and robust in their nature and it is these characteristics that are important in this particular problem domain. A particular strength of the genetic optimisation approach is the ability to handle the multiple and non-linear constraints that are typically encountered in mine scheduling problems. This paper concentrates on the development of a prototype application of a genetic algorithm to the problem of scheduling the output from multiple production points in an underground mining operation. In particular it.describes a system (GO-SCHED) that can be customised to handle a wide variety of underground scheduling problems. GO-SCHED, a Windows-based system, can interface with a variety of databases and spreadsheets for data input and output and provides a simple intuitive approach to the solution of the scheduling problem.

Jan 1, 1995

By E Kasai, D Maruoka, Y Konno, T Murakami

The iron ore sintering process produces approximately three per cent of carbon dioxide emission in Japan because a large amount of coke breeze is used as the main agglomeration agent. Therefore, its suppression has been required. A promising method is to replace the coke breeze with biomass char and iron-bearing materials. In this study, the effect of the utilisation of metallic iron with coke or palm kernel shell char (PKS char) as an agglomeration agent on its oxidation behaviour was examined by a series of experiments using a sintering simulator. The use of PKS char leads to a larger decrease in the pressure drop difference of the sintering bed compared to the case using coke. Furthermore, the oxidation rate of metallic iron was larger in the case using PKS char together than that using coke. It was considered that the oxidation of metallic iron was promoted because the bed-temperature increased at a faster rate and achieved a higher temperature.

Nov 8, 2021

By T Casten

Freeport IndonesiaÆs DOZ (Deep Ore Zone) mine is scheduled to commence production in the second half of 2000. The DOZ will produce 25 000 tpd using mechanised block cave mining methods and will have a number of major improvements when compared to previous block cave mines in the district. The DOZ will have an independent and improved ventilation system, a flexible and efficient truck haulage system, and a more reliable crushing and conveying system than in previous underground mines in the district. This paper will describe the mine plan, haulage, and ventilation systems, and compare them to those used in other operations in the district.

Jan 1, 2000

For many crushed aggregate producers will the finest fraction minus 4 mm represent a problem. The fine material will fetch a much lower price than the coarser products, and may even be difficult to sell in some markets. The blasting operation will strongly influence the generation of fines after both blasting and crushing. Drill hole deviation together with the drill hole diameter, powder factor and velocity of detonation are the most important blasting parameters with regard to the generation of fines. Drill hole deviation is often ignored, and many operators will just reduce the drilling pattern in order to avoid hard bottom and an excessive number of boulders. The paper presents a technical and economic analysis of how drill hole deviation will lead to an increased generation of fines in crushed aggregate production. The analysis shows that the loss of sales revenues will be much higher than the extra costs for drilling and blasting caused by compensating for drill hole deviation by putting in more holes.

Jan 1, 1999

This paper examines the cost and economic consequences of varying a number of key factors in the course of developing and operating new underground longwall coal mines with both shallow and deep cover in New South Wales. The economics of the project are assessed for the first 20 years of mine life using the discounted cash flow method with produc- tion and selling price being determined to provide break even costs for a range of minimum rates of return.

Jan 1, 1988

The theory of declining optimimum cut-off grades is more than 25 years old, but for a number of reasons it is still not widely used in industry. A lack of faith in the veracity of estimated grades is not in itself a reason to abandon any attempt to optimise cut-off grades. The use of declining cut-off grades has been thought to cause high-grading, but in fact this is only true if an artificially high discount rate is used in the calculations. Perfect application of an optimum cut-off grade should ensure that only ore generating more than a minimum net return is mined, and that as much as possible of the ore capable of generating that return is mined. Therefore differing mining costs in different parts of some underground mines necessitate local modifications to cut-off grade. Optimisation of cut-off grade is of necessity an iterative process. Integration of that process into a feasibility study need not be excessively time-consuming. A number of approximations can be made to speed the optimisation (any attempt to achieve a high level of accuracy is probably doomed to failure by a lack of precise cost and price projections). A procedure is outlined for optimising cut-off grade during planning of a typical underground mine.

Jan 1, 1991

By G R. Ballantyne, G Lane

Dry milling circuits that include high pressure grinding rolls (HPGR) or vertical roller mills (VRM) and air classification have replaced dry ball milling in cement production, but how do they compare to wet milling and classification circuits in mineral processing plants? Two case studies are presented that compare the energy efficiency, wear, liberation and capital cost of dry and wet milling circuits. In both case studies the VRM and HPGR consume half the energy of a wet tumbling mill for the same duty. However, the dry classification system tends to significantly erode the energy benefits. A number of improvement opportunities are presented that have the potential to improve the energy and capital efficiency of dry milling circuits. These improvement opportunities focus on the dry classification system that consumes significant energy in heating and fan power requirements and requires a large proportion of the footprint.

Aug 24, 2022

By S Das

Deposit-10/11A is situated in the iron rich Bailadila region of India comprising haematite ore of average grade 65 per cent Fe. The deposit production line was commissioned in the year 2002 having a capacity of 5 Mt/a. The plant has the state of the art mineral processing equipments.The ore is transported from mines to crushing plant by means of dumpers. The ore is comminuted in two stages to get 150 mm top size product and this product is transported through conveyor system and is stored in silos as feed stock for beneficiation plant. In the beneficiation plant this crushed product is wet screened in two stages to produce a product of lump (-150 + 10 mm) and fines (-10 + 3.15 mm). The product of -3.15 mm top size is fed to primary classifier for a size separation at 150 µm. The resultant product (-3.15 mm + 150 µm) is dewatered and transported to fi ne ore product stock yard through conveyor system. The minus 150 µm material from classifier overflow is fed to cyclones (508 mm cyclone battery with an apex of 65 mm) for desliming at 45 µm and to recover ultrafi nes (-150 + 45 µm). The cyclone overfl ow slimes (-45 µm) along with water is treated in lamella thickeners to recover process water. The thickener underflow material is transported to tailing pond (discharge rate is 300 m3/h at a specific gravity of 1.4) by pumping through HDPE (high density poly ethylene) pipeline and the over flow water is being recirculated. The water requirement for beneficiation is approx 1.5 m3 per ton of ore.This paper aims at identifying and quantifying the factors that affect the overall plant performance (grade and recovery) during the different seasonal variations especially in the rainy season (mid-June to end October). The effect of seasonal variations on unit operations such as milling, classification, thickening and filtration are discussed. Specific cases are presented as examples and recommendations are formulated.

Jul 11, 2011

By B Belle

Dust sampling is pivotal in estimating the ‘dose’ of dust exposure and in deriving dose-response curves in epidemiological studies. Over the last half century, gravimetric sampling has been the fundamental means for dust exposure monitoring using recognised respirable size-selective standards. In Australia, a gravimetric sampling technique has been followed since 1983 using the Higgins-Dewell (HD) type cyclones (AS2985). The re-emergence of ‘Black Lung’ or Coal Workers Pneumoconiosis (CWP) in Queensland, Australia has re-kindled the need for better understanding of personal dust monitoring, compliance determination, accuracy, timeliness of sampling results and dust control systems. Reporting dust levels in real time empowers miners and operators to take immediate action to avoid being exposed to excessive airborne dust. Two decades of intensive research in the USA has led to the introduction of gravimetric based continuous personal dust monitors (CPDMs) called PDM3700 as compliance tools. The new real-time mass based sensor is a continuous mass based dust monitor using the Tapered Element Oscillating Microbalance (TEOM) principle and is regarded as significantly superior to the current gravimetric sampling methodology.Recently the overall respirable dust standard in USA coalmines has been reduced from the historic 2.0 to 1.5 mg/m3. This paper provides the results of a comparative pairwise study of an existing gravimetric sampler and the PDM3700 carried out in 3 different Australian underground mines. The field results consistently suggest that there is a significant ‘measurement bias’ between the current gravimetric HD sampler and the PDM3700 monitor operated using a similar HD type cyclone. The results show that the currently used cyclone measurements are approximately 59 per cent higher than the ‘auditable’ PDM3700 monitor data at the current compliance limit of 3 mg/m3. Based on a review of the extensive data collected, the differences can in part be attributed to the aerosol size selectivity of the samplers with the current gravimetric sampler used in mines, collecting more larger sized particles (D90 of 15 µm). This finding has significant consequences for historic exposure results and their use in medical surveillance programs, as well as the current approach to non-compliance determination.CITATION:Belle, B, 2017. Pairwise evaluation of PDM3700 and traditional gravimetric sampler for personal dust exposure assessment, in Proceedings Australian Mine Vent Conference 2017, pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

The Harmonious Design on the Beneficiability for the Pt-Pd Ores Containing High MgO Gangue in Yunnan

Sep 13, 2010

By F Sandrone, J-P Dudt, J Zhao, E Paltrinieri

Tunnel boring machines (TBMs) excavation is nowadays more and more considered a valuable alternative to conventional tunnelling. As a matter of fact, thanks to its advantages such as greater rate of advance and safer working conditions, the application of TBMs has increased significantly in recent years. Despite the possible excellent performance of TBMs in favourable ground conditions, the advance rates could be significantly slowed down or even obstructed in limiting geological situations. This obviously traduces in potentially longer tunnel construction times and higher costs and, therefore, in a preference for conventional method. One of the major geological hazards encountered during tunnel construction, is related to the presence of fault zones or heavily jointed and fractured rocks. The most common geotechnical problems resulting from tunnelling in these difficult conditions include the instability of the excavation face, instabilities of side-walls producing large overbreaks on the tunnel profile, excessive deformations in case of squeezing grounds, frequently changing stresses in terms of magnitude and direction, high water inflows, etc. The decisions aids for tunnelling (DAT) is a model and a computer code that can be used to evaluate the influence of the uncertainties related to both the geological/geotechnical conditions and the construction process on final tunnel construction time and costs. In this framework, the DAT is used for assessing the effects that challenging ground conditions may have on tunnelling operations in terms of costs and delays. This is done by simulating the tunnel construction considering several geological profiles. The aim of the study is comparing different excavation methods (ie drill and blast versus TBM) in changing ground conditions along the tunnel alignment ranging from good rock, to very poor and fractured formations. The results show the impact, in terms of changing construction time and cost, of the excavation method versus the ground conditions.CITATION:Paltrinieri, E, Dudt, J-P, Sandrone, F and Zhao, J, 2014. Comparison of excavation methods in different ground conditions with the decision aids for tunnelling, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 573–580 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By R J. Goldfarb

Reduced intrusion-related gold deposits have become a new, low-grade, large-tonnage exploration target during the last decade. The best recognized examples of such deposits are recognized throughout the Tintina Gold Province of the northern North American Cordillera. Because such examples may have many features in common with orogenic gold deposits, such as anomalous Bi, W and Te, low salinity and CO2-rich ore fluids, and a spatial/temporal association with igneous rocks, confusion and controversy have now become commonplace in classification of many gold deposits formed along convergent margins. The best discriminators of IRGS are likely to be their: +        regional location in deformed shelf sequences on the inboard side of a series of accreted terranes and within terranes that also contain important tin and (or) tungsten deposits; +        local spatial association of gold ores with cupolas and contact aureoles of relatively reduced, alkaline-leaning, and volatile-rich plutons; +        post-deformational timing of gold deposition; +        extremely low sulfide content (commonly <1 vol %) of ores within igneous bodies and the outward zoning, through proximal skarns and to distal base metal-rich veins, from the causative pluton; and +        low grades (<1 g/t Au) of auriferous sheeted vein systems in pluton cupolas.

Jan 1, 2005

By K A. Campbell, K A. Rodgers

The Plumduff sinter occurs at Whenuaroa, near Puhipuhi, approximately 30 km north of Whangarei. It is one of three residual sinters in the southern portion of a mid- to late-Pliocene geothermal system. The deposit consists of many large sinter breccia boulders, including rudrocks (coarse breccias), scattered around the flanks and summit of the small conical hill of Plumduff. Three types of sinter breccia occur: (i) rudrocks consisting of large, angular to sub-angular clasts of layered sinter up to 0.8 m across, as well as smaller clasts of sinter (20 - 100 mm dia), and fragments of stromatolitic structures; all clasts are supported in a matrix of microcrystalline, transparent to translucent to milky quartz; (ii) fragments of layered angular to irregularly mottled sinter of white to grey or bluish hue supported in a translucent to opaque silica matrix; (iii) smaller, matrix-supported breccias with clasts both partially surrounded and/or penetrated, by a clay-like weathering rind, and sinter conglomerates with rounded to oblate clasts. Three principal types of fabrics constitute the bulk of the sinter: (i) stromatolites, including columnar, palisade and filamentous networks, showing progressive silicification, in fenestral, tufted to clotted fabrics; (ii) peloids and pisoids; (iii) plant-rich facies in which various silicified plant species occur in a silica matrix. All fabrics have counterparts in hot spring deposits in the Taupo Volcanic Zone formed at temperatures from 75¦C to 35¦C. Also present is steam-condensate-produced alteration: kaolinite and alunite as well as boulders of quartz lattice texture. Cinnabar only occurs in sinter on the north and south central slopes of the hillside. No quartz veins or geyserite were recognised.

Jan 1, 2001

In general, the metallurgical industry has so far been slower than the chemical industry to adopt ion exchange materials for industrial processes. The atomic energy industry presents a marked exception to this general situation, and the literature shows a rapidly increasing use of ion exchange techniques for the recovery of atomic energy metals on scales ranging from the ultra micro up to that of the largest mining operations. In many cases, the processes used would be equally applicable to more common metals and it is hoped that this review will be of interest to metallurgists outside the specialised atomic energy field. The review is intended to describe developments of ion exchange processes made during the last three years. Earlier studies have been summarised by Kunin and Preuss (1956) and Roland (1957). In order to restrict the number of references discussed, purely analytical procedures have been omitted and only those processes which have been conducted on a reasonably large scale or which, from their nature, areclearly capable of being upscaled, have been considered. The paper is divided into five main sections concerning respectively:Water treatment and effluent disposal.Metal recovery and purification.New ion exchange materials.New ion exchange equipment.Membrane cells.WATER TREATMENT AND EFFLUENT DISPOSALA high proportion of atomic reactors, and particularly those of American design, are cooled by water which is...

Jan 1, 1961

The Greymouth Coalfield contains New Zealand's greatest known resource of bituminous rank coal. The coals are of very high quality, with low ash and sulphur contents and a range of other properties that makes them desirable for a wide range of uses. In fact only a few producers around the world today can offer coals with such exceptional properties. This suggests that Greymouth coal has potential as a premium export trading commodity. These assertions have been largely confirmed by a comprehensive exploration drilling programme funded by Mines Division û Ministry of Energy between 1979 and 1984. The program, forming part of the NZ Coal Resources Survey, was carried out under contract by Lime and Marble Ltd. The drilling of 49 deep, predominantly cored, holes at 1000 m intervals over the coalfield has generated a vast amount of data. It has shown the existence of three major potentially minable coal deposits containing 233 x 106, 33 x 106 and 15 x 106 tonnes of coal in ground. Investigations have at this stage only identified targets and these estimates represent 'in ground' resources, not recoverable reserves. Recent geological studies as well as past and present mining have clearly highlighted the problems posed by the complexity of the coalfield geology. The coalfield lies within a mobile zone in the earth's crust known as the Paporoa Tectonic Zone, which has been active from at least mid-Cretaceous to the present time. Currently this factor poses the greatest obstacle to the determination of mining possibility of the, defined deposit and ultimately will strongly influence any future mining development. The Greymouth Coalfield has, however, had a long and eventful mining history spanning the last 120 years, where 32.5 x 106 tonnes of coal has been won from over 100 mines. In spite of the problems facing development, the large quantities and exceptional quality of the remaining coal will act as a strong inducement to persevere with this difficult but potentially valuable resource.

Jan 1, 1985

Active geothermal fields show many of the characteristics seen in hydrothermal ore deposits but there are important differences as well. There are, for example, many differences in geology and chemistry between individual geothermal fields, even some nearby, and these include variations in host rock types (volcanic, sedimentary, plutonic and metamorphic), structures controlling fluid flow (normal, lateral, and, rarely, reverse faulting occur) and hydrological setting (valleys to elevated terrain).

Jan 1, 1986

By G Tripp, G Lorusso

The Velvet gold orebody (153 Koz Au) is located near the Kanowna Belle gold deposit in the Boorara Domain of the Kalgoorlie Terrane, a subdivision of the Archaean Eastern Goldfields Superterrane (Swager et al, 1990). Gold mineralisation at Velvet is hosted within an intrusion of intermediate composition that broadly follows a sub vertical hanging wall splay of the Fitzroy Shear Zone.Velvet was discovered in 2003 during an underground exploration drilling program targeting potential strike extensions to the Kanowna Belle deposit. Diamond drill hole KDU1595 returned a downhole intercept of 36 m grading 4.6 ppm Au approximately 500 m west of the deposit and at a vertical depth of 700 m below surface in the immediate hanging wall of the primary Kanowna Belle host structure, the Fitzroy Shear Zone. Subsequent drilling completed following the initial discovery, from both surface and underground collar positions, failed to replicate this result.In 2014, KDU1595 was resurveyed gyroscopically and the mineralised intercept correctly located. Additional drilling was undertaken to follow-up the repositioned discovery hole. Challenges included poor drilling angles through the Fitzroy Shear Zone, excessive deviation during drilling and the unknown geometry of the target. Navigational drilling helped to successfully penetrate the Fitzroy Shear Zone and in April 2015, drill hole KDU3234 returned a significant downhole intercept of 45 m grading 5.6 ppm Au.Additional drilling success resulted in a decision to develop a 600 m drive to serve as a dual-purpose access for further exploration and mining. This was a potential risk considering that the orebody geometry was unknown and all significant drilling results were clustered within a 50 m × 50 m panel. Development commenced in June 2015 and the first ore cut taken in April 2016. Geological mapping and structural interpretation, together with multi-element and spectral analysis of drill samples has enabled several other target areas to be identified for exploration. The Velvet mining area is critical to continued production at Kanowna Belle. Geological understanding must advance as mining progresses to ensure continued resource growth and optimal extraction of reserves.CITATION:Lorusso, G, Rogers, J and Tripp, G, 2017. Velvet underground exhumed – discovery and development of a new mining front at the Kanowna Belle gold mine, in Proceedings Tenth International Mining Geology Conference 2017, pp 169–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017