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By P Holtham, K Duffy, L Pyle, W Valery

The mining industry is becoming increasingly focused on pre-concentration due to its potential economic and environmental benefits, particularly for the more complex, low-grade, high throughput operations now being developed. Advances in technology have seen bulk ore sorting (BOS) trialled at several operations. However, BOS should not be seen as a ‘silver bullet’, it can offer significant benefits, but only under the right conditions. Deposits with interspersed mineralogy or disseminated, fine-grained minerals can be difficult for BOS. Large batches of barren or low-grade material are required for BOS to be effective. Hatch has recently completed several studies for clients who believed that bulk sorting was the most suitable pre-concentration technique for their operation, based only on an assumed sorter recovery or on laboratory trials of the chosen sensor. However, minimal consideration had been given to the heterogeneity of the deposit, the achievable separation batch size or sensor repeatability. Evaluation of BOS needs to consider both heterogeneity and sensor suitability. The valuable or gangue mineral must be present in such a way that it can be separated effectively in the large bulk sorting batch sizes, without competing minerals or changing ore characteristics affecting the metal upgrade or recovery. Also, the sensor chosen must be able to detect either the valuable mineral, a proxy for the valuable mineral, or a gangue mineral for rejection with sufficient accuracy and precision (repeatability). This paper presents three recent case studies, emphasizing markers which indicated that bulk sorting was unsuitable for the project whilst highlighting the pre-concentration technologies which were applicable (including particle sorting, and coarse particle gravity separation). The modelling methodology, equipment sizing and forward work plans developed to verify these alternative solutions are also presented, demonstrating the key factors contributing to a thorough scoping assessment.

Aug 24, 2022

By M Hood, X S. L, W J. T Daniel, H Gurgenci

It is believed that disc cutter shape affects rock fracture and therefore cutter performance and cutter life. However, the current generation of disc cutters is made of hardened steel and these cutters wear rapidly and consequently they are unable to maintain their original shape in strong and abrasive rock. This wear problem could be reduced if the cutter was made from a harder material. Unfortunately as material hardness increases so does the propensity for brittle failure. In this study the optimum cutter shapes were identified by studying the mechanics of rock/tool interaction. The results showed that bevel and wedge cutters are better than cutters with dome and flat edges. A new cutter was designed, based on this result, using a harder material to increase the life by a factor of 20.

Jan 1, 1998

By N Winkelmann

Underground coal heating is a significant hazard in some coal mines. The broad principles of how underground coal heatings occur is reasonably known, however the technique for locating the heatings in often inaccessible goaf has been proved to be difficult. Since 2002, CSIRO, with the support of the Australian Coal Association Research Program (ACARP) has been undertaking investigations to apply and develop innovative surface-based radon technique for locating the underground heatings in Australia. This paper presents the progress of the investigation.

Jan 1, 2005

By M P. Cipold, J F. Bachmann, C C. Bachmann, J Ha, H B. Wurst

In washability, the objective is to establish the set of maximum possible separation performance criteria for a given mineral feed. The method of choice for this has been the conventional sink–?float analysis. Using traditional sink–float method it is not possible to sample and automatically measure. This fact, as well as time, cost and safety aspects, as well as required and manageable sample size of the sink–float method have prompted the search for a new approach for establishing separation performance criteria. This is especially important as performance levels of separator plants can be maximised if reliable information based on an analysis of washability in conjunction with particle size distribution, elemental constituency becomes available in time. The new method to establish washability and associated performance information utilises at least two measurement technologies concurrently: single energy X-ray transmission and image processing. For porous or very inhomogeneous materials the results can be refined further by using dual energy X-ray transmission and image processing.If used as a standard laboratory device the continuous build-up of the washability curve allows to evaluate the statistical significance of the sample size during measurement.The measuring method can even be improved if it is combined with an automatic sampling system that feeds a continuous and representative particle stream to the analyser. Then the value of the collected data increases considerably since the washability data are additionally available in time to be considered in the control of the process plant. The washability curve can be derived and is continuously updated based on the particles measured during the past time interval. Older curves and results are stored in a database and can be retrieved for later reference. This technology now enables automated sampling and integrated automated measurement, which was previously not possible.This incorporation of an automated washability monitor at a representative sample gives near real-time data that would impinge positively on the profitability of the plant operation. The method was extensively tested using a range of samples with different densities, varying from 1 g/cm3 (coal) to 5 g/cm3 (iron ore).CITATION:Bachmann, C C, Bachmann, J F, Cipold, M P, Wurst, H B and Ha, J, 2017. Inline analysis of washability parameters for process control, in Proceedings Eighth World Conference on Sampling and Blending , pp 213–218 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Koh P. T L, Varnas S. R

Fluid flow, heat transfer and combustion in a nickel flash smelter have been investigated by numerical modelling and flow visualisation. The three-dimensional numerical model incorporates turbulent two-phase fluid dynamics, radiative heat transfer and combustion. The main features include the use of the k-E turbulence model, the Lagrangian tracking of particles, radiative heat transfer based on the spherical harmonics method, and chemical reactions. The predicted flow fields are in good agreement with data obtained from a series of flow visualisation experiments on a cold water model. The interaction mechanism between the fluid flow and the solid particles is examined for a range of particle sizes both with and without injected oil in a series of simulations. The heat transfer in the shaft is dominated by combustion and radiation, whereas the ignition of particles is influenced by the particle size and the added oil. Flow and temperature fields for both gas and solid particles are presented as well as the fraction of sulphur removed from the particles.

Jan 1, 1992

By W Patton

Investment decisions in the mineral resources sector are made on the basis of an assessment of the economic potential for a mineral deposit. Given the supporting information for the location, scale, and quantity of the commodity of interest, miners and investors aim to make risk-informed decisions when considering further investment. The objective of resource classification is the synthesis of various types and quantities of geologic information used in resource model construction to assign confidence categories to the estimated mineral resources, which can then be used to support informed economic decisions. In this paper a risk-based classification scheme for iron ore mineral resources using conditional simulations is presented. The method involves categorisation of each block according to a confidence level, considering expected recoveries from a kriging model over mining production volumes. The realisations of the simulated model are used to assign risk-based confidence categories to zones of the ore deposit. One motivation for this work is to assess the sensitivity of the scheme to geologic uncertainties. Specifically, that which uncertainty in the layout of mineralising alterations and weathering overprints influence variabilities of associated rock properties and the likelihood of obtaining expected ore recoveries. It is shown these risks have material implications for a project’s economic potential. How the scheme can be extended to the grade control context and the value subsequent grade control activities is also quantified.

May 24, 2023

By A Gibbs

The mining sector has been a leader in investing in safety improvement initiatives, yet relatively few mining organisations can accurately track the positive effects of these initiatives or identify areas that may require more attention. The consequences of not taking safety seriously are severe, and unfortunately injuries and fatalities are continuing to occur across the mining sector (Brady, 2019). There is a tendency to turn to lag indicators such as All Injury Frequency Rate (AIFR), Total Recordable Injury Frequency Rate (TRIFR), and Lost Time Injury Frequency Rate (LTIFR) to track these outcomes. As outlined below these approaches are inherently flawed and a renewed focus is needed on indicators within the control of leaders, indicators that have high predictive validity for future events and data that is used in a way to enable learning and change.

May 5, 2022

Comparatively recent Tasmanian legisla tion established a series of rigid control standards for environmental protection just as ma spectacular expansion of the mining industry was nearing completion. Upgrading existing protection to obtain the necessary licence to operate under these new regulations required further major works and involved a considerable outlay of non- productive capital at a time when escalating costs and falling metal prices were straining economic efficiencies to the limit. Late in 1974 a major environmental protection scheme was commissioned by the Electrolytic Zinc Company of Australasia Limited at Rosebery on the West Coast of Tasmania. This 4 million dollar project was specifically developed by the Company ahead of and to meet the new standards for control of total effluents discharged from its zinc-lead -copper-pyrites mine and concentrator.

Jan 1, 1977

Updraft sintering of lead concentrates was introduced at Port Pirie in 1955 and since that time a considerable amount of investigational work has been carried out in the laboratory and on the plant with the objective of improving both the understanding of the process and its practical application.From this work it is now possible to predict trends in design and operation, which should result in capital savings and increased efficiency of future updraught plants.INTRODUCTIONOver the last 70 years a remarkable advance has been made in the method of preparing lead concentrates for smelting in the Port Pide blast furnaces of The Broken Hill Associated Smelters Pty. Ltd. (RH.A.S.). Beginning in 1889 with heap roasting, the process progressed to Ropp roasters and Huntington-Heberlein pots in various combinations, then to multiple small Dwight Lloyd (D.L.) downdraught machines. In 1940 two large 10 ft by 50 ft D.L. downdraught machines were installed, and finally in 1955 updraught sintering was ,introduced with the installation of the present 10 ft by 99 ft sinter machine.At the time this last machine was built it was the first unit of its type and thus, of necessity, an experimental machine. During the eight years it has been operating a considerable amount of investigational work on sintering has been carried out both on the plant and in the laboratory.It is now felt that sufficient information is on hand to predict at least tentatively, some of the future developments in lead sintering, whereby both the quality of the sinter and the rate of production may be improved. This will result in a considerable reduction in smelting costs.

Jan 1, 1964

By R P. Varden

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

Mar 15, 2021

By 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

Australian coals tend to be young in geological age and high in ash by world standards; preparation of the coal before marketing is almost universal. On the basis of float and sink data from 39 locations in the Eastern Australian coalfields, the coals are placed in four categories representing increasing difliculty in their washability characteristics. These seem to be related neither to the geological age nor the geographical position of the deposit and Hunter Valley coals, for example, span all categories. The influence of crushing on the washability of Australian coals is briefly considered and from limited data it is concluded to be appreciably smaller than for British or North American coals. A strategy for the float and sink analysis of Australian coals is proposed and the influence of washability characteristics on current trends in the selection of separating processes for coking and steaming products is discussed.

Jan 1, 1979

By T Baumgartl, L Zhou, D Mulligan, L Huang

The rapid production and accumulation of mineral processing wastes in the environment can present serious threats to environmental quality and human health. Phytostabilisation with native plant ecosystems is, in many cases, a preferred option for rehabilitation of mine waste storage facilities. However, much of the literature has focused on species selection in short-term experiments to test their suitability under the often extreme chemical conditions in the wastes without addressing the fundamental requirements – ie hydrogeochemical stabilisation and functional root zones. As a result, successful examples of phytostabilisation of mine wastes such as base metal tailings have been rare, especially if success is defined as meeting the completion criteria of non-polluting and sustainable land system at rehabilitated sites. Conventional capping options to isolate reactive tailings/wastes by using physical break and/or sealing layers are often not reliable in the long term (particularly under semi-arid climatic conditions) and, in many cases, they may not be feasible in the field due to the large areas to be covered and the lack of adequate suitable materials at mine sites. By using sulfidic tailings as an example, we have proposed a new paradigm for phytostabilising mine wastes – ecologically engineered pedogenesis in tailings involving accelerated physical, chemical and biological weathering of tailings minerals to achieve hydrogeochemical stabilisation and the development of soil functions, soil horizons and functional root zones.Ecologically engineering functional root zones firstly requires controlling geochemical reactivity in the wastes (ie hydrogeochemical stabilisation), which can cause polluting effects in the root zone and plant toxicity. By means of ecological engineering, in situ weathering of primary minerals (eg pyrites) in tailings may be accelerated by adding functional materials (eg functionalised biochars and organic matter) in the waste slurry during the process of deposition. This will remove or diminish key risk factors (eg potential acidity in tailings and elevated soluble heavy metals) in the solid phase, before placing growth media for reconstructing root zones and transplanting/sowing target plant species. However, much of the acidity, soluble metals/metalloids and other salts would be transported out of the solid phase into the wastewater, which can be addressed by on-site water treatment facilities during mine operation. The trajectory and state of engineered pedogenesis in the weathered tailings may be manipulated to provide specific soil horizons within future root zones that are dynamically evolved toward fully functional soil subsystem within rehabilitated plant ecosystems.CITATION:Huang, L, Baumgartl, T, Zhou, L and Mulligan, D, 2014. The new paradigm for phytostabilising mine wastes – ecologically engineered pedogenesis and functional root zones, in Proceedings Life-of-Mine 2014 , pp 663–674 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

The invitation to speak today was in the form of a single sentence instruction: How does your company run and how do you communicate from top to bottom? It looks like I'll have to let you into our little secret. The team at Croesus know what works for us but we've never talked about it with others - least of all presented it at a conference such as this. In fact we tend to avoid the jargon normally associated with Best Practice or TQM, however in our own way, each of our staff are 100 per cent loyal to our company's aim to maintain and strengthen our commercial success. Just how we achieve this at Croesus is the subject of this presentation today, but first a little history. My dear old grandfather arrived in Kalgoorlie, as a mining engineer 100 years ago. Do you think he would have chuckled if someone suggested to him that a hundred years later we would just be starting to understand Kalgoorlie's geological mysteries? Well, here we are 100 years later and Croesus Mining is fortunate to be part of a generation now realising the true potential of Kalgoorlie's Goldfields. This provides us with a very fertile field in which to sow the seeds we can obtain from the World's Best Practice in Mining and Processing. With each new mineral deposit being discovered, old theories are being exploded. Each new deposit has a personality of its own, leading to some belated pioneering theories of where to drill next, and how to reduce internal costs so that we can win the war against constantly increasing external costs. What we have now and what the old timers didn't have is a huge database of geological input spanning several gold booms and a couple of nickel booms. My only interest in history is to pick up the points that may help us for our future. This is what we are doing in our company which is something of a David, in the David to Goliath range of mining companies in Australia. As a humbling thought; of the 115 164 tonnes of gold that the world's mines have produced throughout history, four tonnes have been produced by Croesus Mining. That's equivalent to 0.003 per cent of the total world's gold production. In the past financial year we achieved a dividend yield of five per cent. To put this into perspective, that's over twice the dividend yield of BHP, Australia's largest company. As we are somewhat less known than BHP, let me spend a few moments giving some particulars of our company's background.

Jan 1, 1995

By R Klepper

Separation of leach residue suspended solids from pregnant liquor solution is an important step in hydrometallurgy flowsheets. Alternative flowsheet options are counter-current decantation (CCD) thickeners or counter current washing (CCW) horizontal belt vacuum filters. Extensive sedimentation and vacuum filtration simulations have been completed by FLSmidth on leach discharge slurries to indentify equipment capacity and performance. These data were used to compare Capex and Opex for CCD versus CCW alternatives. In addition, Capex and Opex for large horizontal belt vacuum filters with filtration areas greater than 250m2 are compared to current state of the art sizes of 150m2. This paper presents this information and discusses various advantages and disadvantages.

Aug 8, 2011

By I Manege, S M. Bennett

The PT Kaltim Prima Coal (KPC) operation is a large scale coalmine operating on the east coast of Kalimantan (Borneo), Indonesia. Originally developed under a coal contract of work (CCOW) with the Indonesian Government, new legislation has led to uncertainty as to the actual life of the mine, the size of the operating lease or mining area, the rehabilitation compliance requirements and other areas of concern. The actual life-of-mine (LOM) plan is therefore in a constant state of flux and must be updated and modified with every new piece of information.Under the CCOW system, the mine life ran from the first year of production (1992) for 30 years (2021), with the potential to extend for a further two ten-year periods. KPC has always intended to run until at least 2041. Under the new legislation, the potential term of the CCOW (to be replaced by a mining license) is open to interpretation, resulting in KPC having to prepare plans allowing for a LOM that may end in 2021, 2031, 2041 or a range of other possible periods of time.Uncertainty about legislation (and hence the mine life) possible production rates and available work areas; variable coal prices and costs; varying management contexts; the substantial reserves available; difficulty sourcing dump space; potential rehabilitation costs and the dependence of a community of over 100 000 people on a single operation sees the LOM and mine closure teams preparing dynamic yet thoroughly robust plans that are updated on multiple occasions per year.This paper will describe the procedure followed by KPC and the potentially show stopping issues that must be dealt with.CITATION:Bennett, S M and Manege, I, ?2014. Life-of-mine planning in a dynamic environment, in Proceedings Life-of-Mine 2014 , pp 379–388 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

The Grootegeluk coal beneficiation plant is situated near Ellisras in the Waterberg coal= field in the Transvaal, RSA. At this plant 15 million tons of coal bearing material per annum are beneficiated by means of two-stage heavy medium bath and cyclone plants. Because of the very low yield of 12 % coking coal product, run= ping costs are of the - utmost importance. For this reason extensive tests were carried out to establish the most effective crushing and bene= ficiation methods and suitable aquipment. At the second heavy medium separation stage, the near-gravity material (+ 0,1. g/cc) amounts to 45 % and daily plant performance ana=lysis is required to ensure acceptable plant efficiency. Beneficiation processes for the -0,5 mm coal originally considered were froth flotation, shaking tables, heavy medium cyclones and water- only cyclones. When the froth flotation route was decided upon, further test work was done to enable selection of the equipment most suitable for the particular requirements.

Jan 1, 1987

By J Ding, H J Peng, S B. Zhu, L Hou, J R. Zhang, S Y. Wu

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Numerous Fe-Cu-Au-rare earth element (REE) deposits have been identified within the Palaeoproterozoic Dongchuan Group of the Kangdian region of SW China. Geochronologic and geochemical data of the dolerite dykes and other volcanic rocks reveal extensional activity occurred about 1.7 Ga called ‘Kunyang Rifting’. The Kangdian region underwent variable degrees of extension, meaning that breakup in the central part of this region occurred earlier than in the north. Research on microphysiography, isotopic geochemistry and inclusions of the Yinachang typical Fe-Cu-Au-REE deposits suggest that the dominant mineralisation fluid is high-temperature, high-salinity magma fluid, containing alkalic components, volatile phase and Cu-Au. Metasomatism and mixing between this magmatic fluid and carbonaceous wall rock and meteoric water caused the precipitation of Fe, REEs and Cu-Au. A chalcopyrite Re-Os age from the Yinachang deposit obtained during this study is some 50–100 million years younger than the timing of emplacement of the deeply sourced Haizi and Dongchuan dolerites. The Yinachang deposit is a typical iron oxide-copper-gold (IOCG)-type deposit, and the presence of this and other deposits in the Kangdian region indicates that the region hosts an intraplate extension-related IOCG system within the western edge of the Yangtze Block, China.CITATION:Hou, L, Ding, J, Zhang, J R, Zhu, S B, Wu, S Y and Peng, H J, 2015. Proterozoic iron oxide-copper-gold mineralisation in the Kangdian Region, south-west Yangtze block, China – a case study on the Yinachang Fe-Cu-Au-rare earth element deposit , in Proceedings PACRIM 2015 Congress, pp 255–264 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

As Coal Mining Areas develop, problems relating to strata control increase. The "easy" coal has been extracted and the future development lies in the direction of greater depths of cover and more difficult strata conditions. To provide solutions to the problems encountered the techniques of constructing and testing physical models have been developed and refined. With a sound knowledge of model theory allied to practical experience, mining research engineers use physical cemented material models to examine, assess and solve mining problems relateu to strata behaviour and environment. For a model to provide the answer to a particular mining problem it is essential that as much information as possible be obtained from the mine or area of a mine which the model is to represent. Details relating to the strata, geological malformations, and the stress environment must be collected and collated to ensure reliable results.

Jan 1, 1976

By Liu Y

Mathematical modelling of scrubbers in development and longwall operations in underground mines produces useful results. Mathematical modelling on the mounting of scrubbers on longwall supports shows that the number of scrubbers and the air quantity through the scrubber are the two important parameters. Increase in both these parameters results in decrease in dust levels at the tail gate. The critical factors are scrubber efficiency and the ratio of the air through the scrubber/total air quantity.Results of parametric studies conducted to establish factors which have dominant influence on the effectiveness of the scrubbers on dust levels and high gas build-up in the scrubber show that for use of scrubbers in development headings, the order of importance of parameters in relation to dust concentration in the scrubber area is: scrubber efficiency, rate of production, specific dust make/tonne, leakage factor, intake dust concentration, recirculation factor and air quantity through the scrubber.The equations developed for mathematical analysis and the detailed results of modelling provide useful data on recirculation of emitted gas in the use ofscrubbers for dust control.

Jan 1, 1995