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By D F. S Natusch, R J. Hooper

Recent lignite investigations indicate their potential as a strategic long-term fuel resource. This potential however would be determined not only by lignite quantity and quality, but also by economic, physical and social resources required to support it. The following discussion uses the example of a typical lignite mining operation to review the major resource requirements. While recognising that the implications of supplying those resources may be as important as their actual existence, this paper has purposely omitted such discussion as this will be one of the main target areas for the next phase of investigations.

Jan 1, 1983

Separation of Minerals Using Electrical Fields The mineral processing industry requires alternative separation techniques to help deal with rising energy costs and decreasing ore grades. Dielectrophoresis is one possible technology. It uses non-uniform electrical fields to separate particles on the basis of their permittivity. In order to determine its viability, the dielectrophoretic force was measured for individual chalcopyrite particles in ethanol. The measurements were made by attaching the individual particles to glass fibres and measuring how far they were deflected by a non-uniform electrical field. Six sizes of chalcopyrite particles were tested and the force was found to increase as a function of particle radius cubed. The particles were also positioned at different points in the field in order to determine the effect of the electrical field gradient. The force was found to increase with the inverse cube of the distance from the centre of the particle to the pin electrode. With the effect of these parameters fully characterised, the single particle test cell can be used to determine the permittivity of single particles of various composition.

Sep 13, 2010

The Ekati Diamond Mine is located on permafrost terrain in CanadaÆs Northwest Territories. The mine rock consists of: diamond-bearing and barren kimberlite; and surrounding waste rock such as granite. The kimberlite occurs in several vertical æpipesÆ that are, or will be, mined using open pits. Early predictions of drainage chemistry at Ekati identified the potential for ARD due to sulfide oxidation from both waste rock and kimberlite. This was surprising for the kimberlite, because neutralisation potentials (NP) are typically hundreds of kg CaCO3 equivalent/t. However, subsequent testwork showed that substantial portions of the NP ædisappearedÆ quickly, apparently due to the unusual non-carbonate mineralogy. In any case, additional predictive work concluded much of the rock was benign and there would be no ARD. Shortly after mining started, ARD appeared from both the waste rock and kimberlite, although a few years passed before the company and its consultants recognised that at least some of the acidic water was ARD. Numerous other processes have been put forward as possible explanations for the remaining acidic drainage, although none have been either confirmed or eliminated. Because: the causes of the ARD and acidity are not known; no causes have been eliminated and more have been added; drainage chemistry was not predicted accurately; and future mining will encounter similar rock. I believe the Ekati Diamond Mine needs high-level assistance to understand current chemistry and to avoid problems with future drainage. Organisations like INAP, MEND3, and universities could provide this assistance.

Jan 1, 2003

By J T. Sharp, M A. Styler, D McGowan, P W. Mayne

Static liquefaction is a geotechnical hazard in mine tailings facilities. Soils that are contractive in shear are susceptible to static liquefaction. Tailings facilities are dynamic structures, typically growing in height each year. Dilative tailings may become contractive under increased effective stress. In this paper we show that Cone Penetration Test (CPT) data can be used to estimate the future state of in-place tailings under changes in effective stress. Susceptibility to static liquefaction is typically evaluated with the CPT by using a clean-sand equivalent normalized cone tip resistance (Qtn,cs) or by estimating the state parameter (?). An alternative approach is to evaluate the soil-state using the yield-stress-ratio (YSR = ?’y/?’v0). If the YSR equals one it is on the normal consolidation line and the soil-state is contractive. YSR values greater than three are typically dense of the critical state line (CSL) and the soil-state is dilative. In this paper we review how to calculate Qtn,cs, ?, and ?’y; and how the YSR can be used to screen for contractive soil behaviour. Unlike Qtn,cs and ?, it is very simple to estimate how the YSR will change due to an increase in overburden stress. This YSR approach was evaluated at three locations that saw increases in overburden of 10 m, 20 m, and 25 m. We show that the ?’y calculations are consistent and the increase in effective stress moves the soil state towards looser soil states. CITATION:Styler, M A, Mayne, P W, McGowan, D and Sharp, J T, 2018. Predicting changes in static liquefaction susceptibility using cone penetration test results, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 317–332 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By B Hiebl, J Martens, L Petzold

A research team at the Iron and Steelmaking department at Primetals Technologies has established new upgrading measures for improving the efficiency of the beneficiation process in ironmaking plants, relying largely on pre-existing equipment. After the upgrade, the iron content in the final iron ore concentrate was shown to be significantly higher. Remarkably, the costs for employing the respective measures are surprisingly low.This case study is based on a Kazakh iron and steel producer, whose beneficiation process is currently generating a magnetite concentrate with a final iron content of 65.65 per cent. The study shows that the implementation of Primetals Technologies’ intelligent modification measures to the current beneficiation process, the realisation of more effective dewatering, and the utilisation of an innovative binder lead to an increased iron content in the resulting pellets, reaching a concentration of 69.17 per cent (iron ore concentrate) and 66.5 per cent (pellets).The current operation consists of three closed circuit grinding stages, four stages of low intensity magnetic separation, vacuum disc filters and straight-grate pelletising. By dividing the slurry after the second stage of grinding and the third stage of low intensity magnetic separation, it is possible to divert the more iron-rich fines before they would enter the third grinding stage and the fourth stage of magnetic separation. This then reduces the load on the existing third stage ball mill. Afterwards, the ground material is treated in an additional low intensity magnetic separator and mixed with the previously diverted fraction of the fines. An improved filtration procedure, combined with the application of a highly sophisticated binder, further reduces the amount of additives needed, so that a genuine direct reduced (DR)-grade iron concentrate is produced as a result.All laboratory, pilot and pelletising test work was executed at Primetals Technologies’ laboratories in Austria.CITATION:Martens, J, Petzold, L and Hiebl, B, 2017. Enabling iron ore concentrate for the production of direct reduced iron with pre-existing beneficiation lines, in Proceedings Iron Ore 2017, pp 227–232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By A Hekmat, M Fuentes, F Armijo, R Castro, F Rodriguez

Interpreting the behaviour of granular material and simulating the gravity flow are complex processes in cave mining methods. In this paper, a new Cellular Automata based code – FlowSim – is used as a flexible tool to simulate the gravity flow and subsidence zone in block caving mines. The simulation results of the gravity flow model in a real scaled mine as well as a scaled physical model are presented in this study. In this research, FlowSim was first calibrated at a mine, based on the information obtained from smart markers. These markers were located in five points of the second block of the Esmeralda sector, at the El Teniente copper mine, Codelco, Chile. The calibration was performed with the objective of reducing the discrepancy between the extraction zone defined by markers in the mine and FlowSim outputs. Regarding the mine data, FlowSim was calibrated with the minimum error of ten per cent between real and simulated results. Then, the calibrated FlowSim model was used to simulate the flow behaviour of a scaled physical model. This model was constructed in the Block Caving Laboratory of the University of Chile to scale down the same block of the Esmeralda sector with the scale of 1:200. The FlowSim outputs show that this software enables the simulation of the gravity flow of the scaled model with less than five per cent discrepancy in grade and dilution entry to the drawpoints. According to the obtained results, this paper recommends FlowSim as an appropriate tool which can improve the design of production level in block caving and can enhance the prediction of the subsidence zone and dilution entry.CITATION:Castro, R, Hekmat, A, Fuentes, M, Armijo, F and Rodriguez, F, 2016. FlowSim – a versatile flow simulation tool to quantify extraction and design alternatives for block caving, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 645–652 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By B M. Guerin

In this paper, some of the constraints to applying bioremediation to the decontamination of polluted soils are introduced. Particularly, attention has been given to those associated with the geology of the polluted site. Areas which require further research have been addressed and indicate that geologists will play a key role, alongside microbial ecologists and engineers, in designing and implementing bioremediation strategies.

Jan 1, 1992

Clinoptilolite as a Low-Cost Solution to Remove Heavy Metals from Water in Mining and Mineral Processing Industry

Sep 13, 2010

Bubble Load Measurements in Flotation - A Critical Review of Current Practice

Sep 13, 2010

By R C. A Minnitt

The Witwatersrand Supergroup is host to the world’s largest gold deposits. The location, quantity, grade, continuity and other geological characteristics of a Mineral Resource are either known, estimated from specific geological evidence and knowledge, or interpreted from a well constrained and portrayed geological model. Establishing such a model is an integral part of the evaluation process in the Anglogold Ashanti (AGA) group, and is referred to as a Geoscience Business Model for the mining operations. The geological model established over the years has relied on detailed descriptions of the mineralisation, and understanding of the regional and local geology of the Witwatersrand sediments, in the West Wits and Free State goldfields. The processes of data collection in regard to underground stope and developing mapping, structural and sedimentological mapping, and the geological inputs to mine planning systems are described, together with aspects of drilling, sampling, grade control, and data management. Anglogold Ashanti’s Geoscience Department employs a complex and unique process to generate the Mineral Resource, including a 3D geological structure model of the orebodies which are usually highly faulted, and a robust mineralisation/facies model on which the decisions about domain boundaries are established. A Mineral Resource Inventory System (MRIS) has a dynamic graphic interface to the resource database that is used for compiling the resource statement. It is also used to determine the gold-called-for, as well as short and long-term planning. A unique estimation process using the extensive closely spaced stope face sampling database and the more widely spaced surface drilling information is used in combination in the Macro Co-Kriging estimation. The use of different support sizes in the C0-Kriging process is preceded by the equally unique ‘clusterisation’ and ‘acceptorisation’ procedures by which the data are quality controlled and assured prior to their use in the kriging process. The Mineral Resource and Ore Reserve estimates are classified according to the SAMREC code through a method that ensures that they are compliant, auditable, transparent and reconcilable with previous Mineral Resource and Ore Reserve statements.

Aug 22, 2011

Electronic noses are being used in the processing industries and in fields such as environmental and occupational hygiene to detect a wide variety of problems from contaminated foods to toxic chemicals in soils. Recently, research has been conducted into the use of these devices for detecting spontaneous combustion in mines with the aim of producing a method for early detection of a developing heating. Gas samples were collected from both SimtarsÆ 16 m3 large-scale spontaneous combustion reactor and the University of QueenslandÆs two-metre column. The samples were analysed using an electronic nose. GCMS and HPLC were used to identify some of the components present. A number of issues both from a practical mine situation and a scientific standpoint have been identified that need to be addressed before these devices can be used to detect a developing heating. Aluminised bags routinely used in the mining industry to collect gas samples for analysis of the permanent gases are not suitable for use with electronic nose devices as they have a æfingerprintÆ from the polymer lining that interferes with the coal heating fingerprint. Tedlar bags used for environmental gas sampling are also unsuitable due to their fingerprint. Gas samples can be collected in glass gas bulbs with aluminium seals and successfully analysed. However the aluminium foil used to seal the bulbs is a restricted item in underground mines. It was also found that the volatile organic fingerprint of the coal heating was extremely weak at temperatures below 130¦C. Before a useful application can be developed, further investigation into the chemical species present in the off-gases from Australian coals is required.

Jan 1, 2005

By W Blair, J Bosman

The measurement of ferrosilicon rheology and characterisation of the parameters that have a direct influence on medium rheology provide the basis for evaluating, comparing and selecting an appropriate size and shape of medium to maximise separation efficiency in a dense medium application. The role of medium viscosity on particle separation in both static and dynamic separators is illustrated using relevant theory. The primary measurements of rheology are medium viscosity and stability. These in turn are determined by particle size, particle density and particle shape which in turn can be quantified. Additional characterisation parameters are also discussed. Different areas of application where ferrosilicon characterisation can be used are also discussed.CITATION:Bosman, J and Blair, W, 2017. The practical characterisation of ferrosilicon for dense medium applications, in Proceedings Iron Ore 2017, pp 135–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By T Wootton

The Barrytown ilmenite pilot plant was commissioned in two stages using Westport Titanium Project heavy mineral concentrate. The wet concentrator was commissioned on the 17 December 1989 and produced magnetic concentrate from this date.   The Drymill was commissioned on the 27 January 1990 and produced product grade ilmenite successfully from the onset.   The commissioning period was exceptionally short by normal standards and few problems were encountered. This paper concludes with general observations of operations of the pilot plant.

Jan 1, 1990

With the continued implementation of stricter limitations on the discharge of excess process water from all existing and future mining and metallurgical operations, the design and operation of the entire process water circuit must form an integral part of any total operational package. It is far better to æanticipate and circumvent the problemÆ rather than be forced into an expensive remediation program after the event. By far the greatest problem relates to the treatment and disposal of what is generically known as acid drainage. In simple terms, an acidic metal sulfate solution is generated by a series of chemical and biological reactions as soon as most sulfide minerals are exposed to air and water. Treatment of this solution by one or more of a wide range of chemical and physical options can involve substantial capital and operating costs, although there are recent processing options that yield saleable by-products, thereby reducing the financial liability of what is effectively a waste stream. This presentation provides an overview of the Australian situation compared with the rest of the world and outlines the basic features of a number of the more advanced passive and active acid drainage options.

Jan 1, 2004

By C Harrison, A Bowskill

The Ambuklao hydroelectric dam was originally constructed in the 1950s in the remote and mountainous region of the northern Philippines. Following its construction the dam has suffered heavily due to siltation and a partial collapse of the intake structure due to a 7.8 magnitude earthquake that struck the region in 1990. Between the years 1990 and 1999 the power station progressively lost its capacity to generate power. In 1999 the owner took the power station out of commission. The power station remained idle over the next 12 years. In 2008 the power station was sold to a new owner who commissioned the rehabilitation works.The rehabilitation project restored the operating status of the power station in June 2011 and increased its capacity from 75 MW to 105 MW. The civil contract of the rehabilitation project required the construction of a new intake structure behind an in situ rock coffer dam on the edge of the existing reservoir, new 6.2?m diameter × 124?m deep blind sunk shaft behind the intake structure, which connects to a new 6.8?m horseshoe profile headrace tunnel that ultimately connected onto the existing vertical penstocks which feed three No 35 MW Horizontal Turbines rated at 155?m head.The unique challenge in rehabilitating this existing hydropower station involved finding solutions that would conclusively deal with the challenging geological and hydrogeological conditions associated with excavating new tunnels and a drop shaft beneath a live dam.McConnell Dowell was awarded the civil works package for the rehabilitation works in August 2008. The Ambuklao rehabilitation program took 33 months to complete.Over 600?m of tunnels were excavated in highly weathered and often challenging geotechnical conditions via drill and blast with the extensive use of high-pressure fissure grouting to control groundwater ingress that was surcharged by the dam.This paper focuses on the use of high-pressure fissure grouting that took place to enable the excavation of the new waterway system and intake structure.CITATION:Bowskill, A and Harrison, C, 2014. High-pressure fissure grouting for drill and blast tunnelling, Ambuklao, Philippines, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 141–152 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

Pilot-Plant Testing of Ammoniacal-Cyanidation for Gold Recovery from Copper Gold-Bearing Ore The results of pilot-plant tested ammoniacal-cyanidation of gold recovery from copper gold-bearing ore are presented in this paper. This ore is from a deposit of Russian Federation with gold and copper grade 9.5 g/t and 0.4 per cent, respectively. Copper is largely present as malachite and azurite. The presence of chalcopyrite and bornite is also observed. In order to recover gold, gravity is recommended. Two options of ammoniacal-cyanidation using leaching of gravity tails, CIP and filtration, were tested. It was found that ammoniacal-cyanidation using filtration of leaching tailings and recycled solutions is the most optimal option. The proposed flow sheet provides for 89.7 per cent gold recovery from gravity tailings at the consumption of NaCN 0.9 kg/t and (NH4)2CO3 7.5 - 9 kg/t. Compared to conventional cyanidation, this technology decreases the consumption of sodium cyanide from 4 up to 0.9 kg/t at the same gold recovery. It can be recommended for the treatment of copper gold-bearing ores with the similar composition.

Sep 13, 2010

By D A. Williams, P J. Chapman

The acceptable rate of rise of the tailings beaches on upstream-raised tailings storage facilities (TSFs) is critical to life of mine planning. This is illustrated through a case study in Western Australia presented in this paper. Accurate estimates of expected beach slopes, the maximum rate of rise at which the tailings can be placed, and the dry density that the tailings solids will achieve after deposition (stored density) are required in order to design TSFs that will allow upstream raises to be constructed safely and economically. Where operations have been occurring for some time, these three parameters are able to be measured and can be well-defined. If process plant throughputs are proposed to increase through mine expansion, for example, increasing the rate of rise of the tailings can compromise the potential for upstream TSF raising, thus influencing the viability of such an expansion, the timing for its implementation, and significantly increase costs.This paper outlines how rate of rise can be a key constraint, and that ‘rules of thumb’ that are typically applied may not result in the outcomes they were meant to achieve. An example of an experimental method to justify an increase to the ‘rule of thumb’ ~2.5 m/year limit for gold tailings in a semi-arid climatic setting is discussed, followed by rate of rise modelling that ultimately framed the decision-making process for a mine expansion. The rate of rise modelling method was adopted to carefully distribute tailings deposition across four TSFs, comprising nine separate tailings cells, in order to maintain appropriate rates of rise. The implications resulting from various deposition splits are presented, including the need for expansion. In addition, this paper outlines the effect of rate of rise on the state (density) of the tailings after deposition, and provides commentary on how anecdotally acceptable rates of rise, based on the aforementioned ‘rule of thumb’ of 2.5 m/year may not provide assurance of geotechnical stability through the tailings achieving a dilative state, as has been thought in the past. An example of the influence of rate of rise on the state of the tailings, with respect to air-drying and the critical state line (CSL) for the material, is presented. The data indicate that reducing the rate of rise may allow a higher dry density to be achieved through air-drying (evaporative desiccation), sufficient to move the material from the contractive to the dilative zone (i.e. from above the CSL, to sufficiently below it).CITATION:Chapman, P J and Williams, D A, 2018. The importance of rate of rise in life-of-mine planning of an upstream raised tailings storage facility – a case study, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 350–360 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

Preliminary work being undertaken on the optimisation of decision strategies for an open-pit metalliferous deposit is presented. The Optimal Control method has been selected rather than the easier to implement Dynamic Programming method of optimisation since a fundamental criteria of Dynamic Programming is violated. Essentially a system of state equations and decision variables is developed for the operation under consideration.

Jan 1, 1984

Following the Coalbrook Colliery disaster in 1960, Salamon and Munro (1967) established the well known empirical coal pillar strength formula in South Africa. This formula has prevented further violent multiple pillar failures. In 1996, a back analysis of the collapsed and uncollapsed cases in Australia led to the development of the Australian empirical coal pillar strength formulae. The original collapsed and uncollapsed coal pillar database of Salamon and Munro (1967) was updated in 2006. This study introduced various strength formulae for different coalfields and seams in South Africa through back analyses of collapsed and uncollapsed cases. Today, the resultant pillar strength formulae from these previous studies and the behaviour of coal pillars are mostly well understood and applied with confidence. However, it was assumed in the previous studies that the behaviour of pillars is not time dependent; therefore, the formulae established do not provide an associated time to failure of coal pillars. This paper attempts to evaluate the so called 'Geometrical Limits' concept to provide the Australian coal mining industry with a tool to assess the long-term behaviour of bord and pillar workings where the pillars are prone to failure due to spalling of ribs. In order to achieve this outcome, the principles of the safety factor concept and the probability of failure calculated using the coal pillar strength formulae have also been evaluated and practical design examples are presented in this paper.

Nov 25, 2010

This paper describes the past, normal and advanced practice of optimisation in mining. It then discusses what needs to happen for the mining industry to make full use of what is now available.

Dec 6, 2010