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By Das A. K

Investigations were carried out to understand the effect of liquid viscosity (u = 1 x 10-3 - 5 x 10-' Ns/m2) on the size of primary bubbles formed at high gas injection rates (Q = 100 - 1000 cc/s, U = 0.04 - 0.42 mach) under room temperature conditions using flush tuyere (3 mm diameter) operating vertically upward. Tuyere pressure fluctuations were correlated to the mode of bubble formation by simultaneously filming the bubble and the corresponding tuyere pressure fluctuations displayed on an oscilloscope screen. A simple mathematical treatment is presented to estimate bubble size in viscous liquids. The theoretical results are compared with the experimental measurements.

Jan 1, 1987

By J deVries, A Broodryk, P Kyselica, K McLean

Gwalia gold mine is located close to the town of Leonora in the Goldfields region of Western Australia, some 830 km from Perth. The mine is wholly owned by St Barbara Ltd, an Australian Securities Exchange listed gold producer and explorer. The Gwalia mine is a deep, all-trucking mine and is serviced by a 10 km long decline from surface. Mining is currently 1540 m below surface. Reserves extend to 1820 m below surface and are open at depth. The mine produces in excess of 200 koz of gold per annum.The Leonora area is hot and arid, with a mean annual rainfall of 230 mm and a 95 per cent mean daily maximum temperature of 20.3°C wet-bulb and 35.6°C dry-bulb.The primary ventilation system comprises a 490 kg/s surface exhaust fan, which draws air down a parallel intake system consisting of the decline, and a dedicated fresh-air intake system extending to the bottom of the production zone. Cooling is provided via a surface bulk air cooler serviced by an ammonia refrigeration plant that delivers 150 kg/s of chilled water to the bulk air cooler.The refrigeration plant and bulk air cooler were installed in 2008. The design allows cooling to be increased over time by installing an additional refrigeration plant in a lead lag configuration with the current refrigeration plant when required.Since 2008, expansion and increased depth reached a point where the underground heat load exceeded the installed capacity of the existing 4.0 megawatt rated (MWR) refrigeration plant. In order to maintain the mine design conditions underground, upgrading of the existing refrigeration system was required to bring the cooling capacity to 7.5 MWR.Two expansion options were considered: the addition of an ammonia vapour-compression refrigeration machine similar to the existing one or a lithium bromide absorption refrigeration system using waste heat from the site power station. The original design and layout of equipment on-site meant that either could be used, allowing an assessment of the merits of both when additional cooling was required.The decision was made to install a lithium bromide absorption system on the lead side of the existing ammonia refrigeration plant. This arrangement provides considerable economic benefits, including reductions in site-generated electrical power, generator fuel consumption and carbon dioxide emissions.This paper details the planning, design, installation and commissioning of the absorption chillers.CITATION:Broodryk, A, deVries, J, Kyselica, P and McLean, K, 2015. The design, installation and commissioning of an absorption refrigeration system at Gwalia gold mine in Western Australia, in Proceedings The Australian Mine Ventilation Conference, pp 193–200 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By Marshall T. E, Finfinger G. L

Gulf Coast domal salt mining operations have had sporadic encounters with methane gas emitted without any warning. In virtually all confirmed cases, the methane was localized in methane enriched zones. In a few cases large quantities of methane were expelled rapidly with salt outbursts, resulting in dangerous methane concentrations. Estimates of methane liberated by face blasts in methane-enriched areas is needed in determining how much air should be supplied to the face for proper dilution. A relationship between the gas content of salt samples collected from the face and the amount of methane liberated would be helpful in estimating how much methane will be produced by a face blast. Little is known about the layering or stratification of methane in large area-low velocity airways. This publication reports on three tests conducted by the Bureau of Mines which monitored the immediate return air of four faces during blasting. The test locations were in a methane gas-enriched section that had previously experienced two large outbursts and many smaller ones. A comparison was made between gas content values of face salt samples from the dissolution test and the gas liberation quantities. The characteristic movements of the methane in a large room with low air velocities were charted. This will help to better understand the factors involved in proper placement of methane sensors as a warning system.

Jan 1, 1988

By D Craw, P V. Angus

Gold mineralisation at Macraes occurs as late quartz-carbonate veins within a body of sheared and hydrothermally altered Otago Schist, the Intrashear Schist. The alteration is characterised by the presence of rutile and the absence of epidote and titanite, indicative of an alteration fluid containing >10 mol per cent CO2. In areas of high strain, a fabric of black microshears develops, gradational to mylonitic cataclasite in the high strain zone adjacent to the hanging wall of the duplex shear zone. The microshears contain hydrothermal graphite, inferred to have been deposited from a methane-rich fluid. The mylonitic cataclasite is characterised by abundant pyrite, the absence of albite and extreme grain size reduction. Gold recovery in the CIL processing plant at Macraes can drop to 50 per cent or lower for some unfavourable ore types. Preg-robbing by a component in the ore, possibly graphite, was suspected as the cause. Mylonitic cataclasite was identified as the lithology responsible for the poor recoveries, with the capacity to bind about 30 ppm of gold in the leach tanks. A program of detailed geochemistry and quantitative grain-size measurement using Coulter analysis was undertaken to identify specific mineralogical factors associated with preg-robbing. The results indicate that pyrite, graphite, and extreme grain-size reduction are the factors associated with highly preg-robbing ores at Macraes. The evolution of the mylonitic cataclasite is accompanied by strong potassium enrichment, as muscovite, and depletion in sodium as albite is removed. This suggests that a simple powder XRD ratio of the albite to illite peaks would suffice to distinguish the preg-robbing ore for grade-control purposes.

Jan 1, 1999

By S Juras

The terms measured resources and proven reserves denote the highest level of estimation confidence in all of the major classification schemes. But what do they really bring to today’s project or mine with respect to production planning and expectations? Initial reserve declaration does not need measured resources, just indicated resources. Economic viability of a project is assessed on total reserves with nary a bonus for the amount of proven reserves. Production plans are based on grade and tonnage goals that may only coincidently correspond to proven reserves. So are the measured and proven categories still relevant? Historically, and almost exclusively in underground mines, companies only allowed mining in areas of proven reserves. Some companies still follow that philosophy. But many others will mine a mixture of probable and proven reserves without hesitation. Also what of the undeveloped project in a new district – what is to be made of their declared measured resources and proven reserves? Measured resources are commonly set either by some type of proximity to data scheme or a matter of ‘feel’ based on the qualified person’s experience. The parameters for reserve conversion focus on the project as a whole and then a portion becomes classified as proven reserves almost solely based on whether the resource category is measured. So should the mining industry continue to use these categories of resource and reserve classification? This paper will present arguments about making these categories once again more relevant. A more disciplined usage of these categories may re-introduce their relevancy in public disclosures of resources and reserves. As well a more consistent usage in operations may lead to increased confidence in managing production targets and costs.

Aug 22, 2011

By H Kundapen, B R. Bolton, H Davies

The Ok Tedi porphyry copper-gold mine is located in the Star Mountains of Western Province, Papua New Guinea. Open-cut mine commenced in 1984 and is due to cease around 2010. The mine produces a total of 88 Mt of waste annually including 58 Mt overburden and 30 Mt tailings, which are discharged directly in to the Ok Tedi River. Mine derived wastes are transported downstream and deposited within the river channel in a variety of bar forms. The prevailing hydrogeological conditions including, velocity, competency, capacity, gradient, grain size and specific gravity, control the deposition and segregation of these sediments. Periodic exposure of the reactive sulfides to oxygen during fluctuations in the river discharge may result in oxidation, localised acid generation and liberation of metals into solution. To evaluate the significance of this issue, Ok Tedi Mining Limited initiated an investigation of the sediments deposited in the upper Ok Tedi River as part of its overall ARD Management Program. The specific objectives were to: evaluate the acid-forming characteristics of identified high sulfide river deposited sediments; characterise geochemically the waters in contact with sulfide-bearing river deposited sediments; map and monitor exposure areas and oxidation depth of deposited potentially acid forming (PAF) sediments; determine the depositional processes controlling sulfide distribution; and assess lag period, oxidation and metal release rates for the sediments. This work included the analysis of sediment and water samples collected on a 50 + 50 metre grid at six gravel/sand bars. The sediment samples were analysed for total sulfur, ANC, NAG, total sulfur and total copper. Water samples were tested for general water quality parameters, sulfate and a suite of dissolved metals including; Al, Ca, Cd, Cu, Fe-sol, K, Mg, Mn, Na, S and Zn. This paper presents the results of these investigations with particular emphasis on the geochemistry of the river sediments and associated contact waters.

Jan 1, 2003

By G J. Wilkie, P A. Revell

The R&D landscape for ore pre-concentration technologies within mining is characterised by the development of individual technologies and point solutions. This presents METS and mining companies with the combined challenge of understanding how to apply pre-concentration technologies to create maximum value, and how to sustainably integrate the technologies into their businesses to maintain the value. The paper will consider the requirements of an integrated pre-concentration system and presents a portfolio of R&D projects that have co-developed and integrated a suite of new precencentration technologies and methodologies across the mining value chain. Focus areas include in-situ orebody characterisation, blast design, real time cross belt mineral sensing, and consideration of how much data needs to be acquired in order to make value based decisions between ore pre-concentration options. An ore pre-concentration workflow is presented to demonstrate how additional optimisation opportunities are enabled both by moving decision points further upstream in the value chain, and by integrating the concepts of pre-concentration into the design of mineral processing equipment. Additionally, several research projects examine the non-technical factors that present barriers to uptake of new technologies within mining companies. Organisational culture, risk management and socio-political factors are discussed and a set of management tools are presented that allow organisations to self-assess their readiness for new technology uptake, along with process models to assist management with identifying and navigating the ecosystem of stakeholders that are decision makers in the use of pre-concentration technologies.

Nov 10, 2020

By P B. Schwann

The commonly accepted genetic theories of Pilbara iron ores and Woodie Woodie manganese ores have often presented them as quite unique. This apparent uniqueness is not confined to just iron and manganese, but is also seen in gold and copper deposits in Western Australia. The published material on iron and manganese ores would seem to have either a quite complicated genesis or none at all. An alternate theory for the origin of these deposits is presented which involves a protore with simple oxidation and pH controls with hydrothermal fluid sources from the diagenesis and dewatering of the underlying strata. This theory explains the distribution, thinning, cold dolerites and very high concentrations of deleterious minerals observed in these deposits. This genesis system is also related to the systems that deposit hydrothermal gold and copper in sediments in the region.This paper presents the author’s observations, sampling and mapping after several decades studying and exploring for the minerals in Australia and locations overseas. All of these theories were developed with (or in spite of!) the guidance of Mal Kneeshaw, but would never have seen the light of day without him and the others presenting here. It is not what I would call scientifically polished, and possibly deserves more detailed studies; it is, however, presented as a discussion paper.CITATION:Schwann, P B, 2015. Related genesis for iron, manganese and gold-copper ores in Western Australia, in Proceedings Iron Ore 2015, pp 327–336 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By B Maybee, L Fava, D Millar

In the context of a case study for an underground gold mine, the value generated by a schedule optimisation tool (SOT) is assessed. SOT is a software tool for underground mine planning that maximises the net present value (NPV) of a development and production schedule. A baseline study measures the NPV of a schedule generated by SOT from a sequence prepared by the site mine planners. Operational resource constraints and precedence constraints are adhered to by the schedule and NPV is evaluated with a financial model including revenues, costs and discount rate, as specified by the mine planner.The case study has several facets in addition to the baselining component. Scenarios were conducted that examined the degree of constraint on operational resources, the projected gold price and unit costs. Life-of-mine schedules subject to optimisation using SOT allowed for equitable comparisons.Haulage was identified as a dominant constraint for the mine. It was one of six operational resources that were used to constrain the optimisation of the mine schedule, with alternative levels for some of these constraints being identified so that their effects on the NPV could be studied. Alternative price projections for gold and different cost projections were identified and their effects on the optimised schedule examined. Price and cost scenarios that brought additional economic material into the schedule at various times in the mine life were considered in comparison to a scenario that assumed no additional economic material would become available.This case study illustrated that the use of a schedule optimisation tool to optimise mine schedules provides mine planners with an ability to perform a wide variety of analyses in a relatively short period of time. Such tools thereby support strategic decision-making that can add significant value to an orebody.The case study demonstrates that by fixing the set of development and production activities to be carried out before optimising the life-of-mine schedule, the mine planners can inadvertently set up a situation where the NPV would be progressively eroded in the last several years of the mine life. This clearly illustrates the need for schedule optimisation to be integrated with life-of-mine planning.CITATION:Fava, L, Maybee, B and Millar, D, 2012. Decision support for an underground gold mining operation - A case study using the schedule optimisation tool, in Proceedings Project Evaluation 2012 , pp 41-48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By B G. Lottermoser

Field and laboratory data combined with computational modelling have been used to predict the pit water quality for the Highway Reward mine. Open pit mining of the Highway Reward copper-gold deposit has produced a final mining void with a diameter of 600 m and a depth of 280 m. This void will be left to fill with ground and surface water once pumping of pit water ceases. Several leaching tables were constructed to simulate weathering reactions and surface water run-off in the major pit wall units during a 200-day leaching experiment. To date, about three-quarters through the experiment, combined run-off from these cells has reached a pH

Jan 1, 2003

By Bruington T, Perkins J, Hutton R

Natural resource developments are among the largest and most challenging projects taking place in the world. They involve capital intensive investment with long lead times and the management of geological, market, technical, operational and financial issues. A clear strategy is required to manage these projects and this strategy is underpinned by a development Philosophy.

Jan 1, 1997

By J Janus, J Krawczyk

Local accumulation of methane in workings of a longwall is one of the most common causes of mining accidents. This gas has many sources: it may leak from goaf through permeable sealings, or through gaps between roof support sections. This stream is then mixed with ventilation air. In the case of auxiliary ventilation ducts, or free jet fans, we have to consider the propagation of a clean air stream in areas with an air-methane mixture. Therefore, modelling the mixing process of methane with ventilation air is important for determining the hazardous areas and thus to ensure safety. Computational fluid dynamics (CFD), specifically the finite volume method, provides tools for such modelling. However, this method requires validation. For this purpose, we have compared measurements with simulations for selected test cases having sufficient similarity to the present problems. In typical methane explosion hazard areas, such as a longwall, it is difficult to make measurements sufficiently to confirm credibility of 3D CFD simulations. As a relevant alternative, an injector methane drainage station placed in an underground gallery has been selected. The stream of drained goaf methane is entrained by compressed air powered injectors and then mixed with ventilation air. Research in this area does not interfere with mining operations, it can be performed safely in a repeatable way. Flow within the site has many similarities to conditions in mine drifts of the longwall area. Comparative research of measuring the methane concentration distribution in the mine drift downstream injector station, with simulations of propagation of the methane stream, was carried out. For measuring the methane concentration distribution in the mine drift a multipoint measurement velocity system developed at the Strata Mechanics Research Institute was used. For the simulation a finite volume method for turbulent flow of gas mixtures was applied. Preliminary results of comparison are shown as graphs and tables.CITATION:Janus, J and Krawczyk, J, 2013. An analysis of the mixing of air and methane in the stream produced by the mine injector station - Presenting preliminary results of measurements and modelling, in Proceedings The Australian Mine Ventilation Conference , pp 49-56 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By OÆShea P. J, Dickson T. W

In April 1994 the Victorian Premier announced new State initiatives, collectively termed the Victorian Initiative for Minerals and Petroleum (VIMP), for exploration totalling $16.5 m over three years. The program, initially centred on the northwest of Victoria, the Eastern Highlands and the Otway Basin, is due for completion in June 1997 and has been designed to attract explorers to highly prospective but currently under-explored parts of the State. Major components of the program include acquisition of geophysical data (including airborne magnetics and radiometrics, gravity and seismic data), stratigraphic drilling, geological mapping and mineral resource data compilation. At the completion of the current program, 70 per cent of the State will have been covered by airborne magnetic and radiometric coverage at 400 m line spacing or better (Figure I) while 20 per cent of the State will have been covered by new geological mapping. The completion of database compilations for geochemistry, mine data and exploration licence summaries during the VIMP program is shown in Figure 2. The new airborne geophysical surveys have been flown partly under the VIMP program and partly by AGSO under the National Geoscience Mapping Accord (NGMA). Data from these surveys have been interpreted and incorporated into the geological mapping in order to enhance the quality of map products, especially in areas of Cainozoic cover. The first series 1:250 000 scale geological map coverage of Victoria was completed by the Geological Survey of Victoria (GSV) in 1977, and was based on compilation of historical geological mapping with minor field checking in most cases. The first metric 1:50 000 scale geology maps were also commenced in the 1970s, but were discontinued in the 1980s in favour of 1:100 000 scale map production. Driven by customer survey findings and with the benefit of detailed airborne geophysical data in the 1990s, the GSV reverted to 1:50 000 scale map production in 1995, with 1:10 000 scale maps made in areas of significant gold production. Geological reports still cover standard 1:100 000 scale map areas, but are now accompanied by four 1:50 000 scale maps. These new series 1:50 000 scale geological maps have been supported by comprehensive mine data and exploration licence summary databases in addition to the new geophysics, and benefit from the advances made in structural geological interpretation over the last decade. The new phase of geological mapping in Victoria, commenced under the NGMA in 1990 and accelerated under VIMP in 1994, has been focused in the central Victorian goldfields and eastern Highlands areas of the State (Figure 1). Results to-date have led to a number of major advances in the understanding of the eeoloeical evolution of Victoria.

Jan 1, 1997

By D Adhikary, M Khanal, B Poulsen, H Guo

During longwall mining, the ability to reliably estimate the height of longwall mining-induced fractures is critically important in order to effectively manage mining-induced water inflows and aquifer interference. The extent of mining-induced subsurface deformation, fracture, surface subsidence and aquifer interference is largely controlled by local lithological conditions, mining methods and mine layouts. Therefore for the purpose of quantifying mining impacts it is imperative to incorporate the local geology and mine plan parameters in a mine scale model. Two different numerical models based on 3D continuum (Finite Element Method) and 2D discrete (Discrete element method) domains, respectively, are developed to incorporate the mine site parameters of a study site in Australia. Both the models are calibrated and validated with measured mine data. The continuum numerical modelling method is used to investigate the change in permeability of the overburden strata due to underground extraction considering the full 3D nature of geology and mine layout. The discrete element modelling method is used to simulate the initiation and propagation of fractures, allowing the caving of overburden strata to be represented in a realistic manner, and the permeability enhancement of the strata overlying the goaf to be calculated from first principles. Permeability enhancement in the discrete element model is a direct function of the fractures induced in the deformation/caving process; fracture location, extent, aperture and connectedness. From the numerical modelling under the simulated condition for the mine studied here, it is predicted that the permeability of the caving zone from the goaf to five times the mining height increases by almost six orders of magnitude. In the fracture zone to approximately ten times the mining height, the change in permeability is predicted to be around two to three orders of magnitude. At the height of more than ten times the mining height the magnitude of permeability increased is predicted to be one to two orders of magnitude. CITATION:Khanal, M, Poulsen, B, Adhikary, D and Guo, H, 2018. Modelling of height of connective fractures during longwall mining, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 254–265 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By G Hancock, J Lowry, T Coulthard, W Erskine, M Saynor

An important part of planning for the rehabilitation of uranium mine sites is the ability to assess the geomorphic stability of the final landform, over time frames ranging from decades to millenia. Depending on the environmental conditions, erosion features such as gullies may incise into containment structures, potentially leading to the exposure and transport of encapsulated radioactive material. Further, erosion may lead to increased sediment loads and the transport of other mine-related contaminants off-site and into downstream waterways. While erosion may be monitored and assessed over the short term (years to decades), the longer-term behaviour (centuries to millennia) of such landscapes is not within any meaningful human management time frame. Landscape evolution models (LEMs) can provide information on soil erosion rates at decadal or centennial scales over large spatial scales, and evaluate the sensitivity of these processes to environmental changes. However, an important issue associated with the use of models is the ability to assess the reliability and accuracy of the model. In this paper, the CAESAR-Lisflood LEM is tested for its ability to predict soil erosion from a series of 30 m × 30 m experimental plots specifically constructed for this purpose on a trial rehabilitated landform at the Ranger Uranium Mine in the Northern Territory, Australia. Model predictions of bedload and suspended sediment loads from the erosion plots were compared with field measured observations collected over four wet seasons from the trial landform. Once calibrated for the specific site hydrological conditions, the predicted sediment yield – specifically, bedload – demonstrated an excellent correspondence with the field data. However, longer-term simulations of ten years identified an exhaustion effect in sediment yield from the landform. These latter results indicate that a weathering function needs to be incorporated into CAESAR-Lisflood to ensure confidence that the CAESAR-Lisflood LEM will be able to correctly predict the long-term evolution of a rehabilitated landform once it has been?constructed.CITATION:Lowry, J,?Saynor, M,?Erskine, W, Coulthard, T and Hancock, G, 2014. A multi-year assessment of landform evolution model predictions for a trial rehabilitated landform, in Proceedings Life-of-Mine 2014 , pp 67–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

A Kellogg type computer model of the slag fuming process is applied in reverse to derive some thermodynamic properties of components in lead blast furnace slag. At 1200¦C, the average activity coefficients calculated were 3.40 (S.D. 0.50) for ZnO referred to the pure solid; 0.657 (S.D. 0.022) for PbO referred to the pure liquid; for the ratios y 3.175 y (referred to the Feo.9450, Fe304 pure solids) 4.19 (S.D. 1.15), and for yCaS/ 1CaO (referred to the pure solids) 5.10 (S.D. 2.96). Statistical relationships were derived for these activity coefficients and ratios as functions of the composition of slag, which contained in molar percentages 1.9 - 12.6% ZnO, 19.8 - 24.9% Fe0.9450, 0.9 - 1.6% Fe304, 0.002 - 1.9% PbO, 16.1 - 18.6% CaO, 25.9 - 31.0% SiO2, 4.8 - 5.5% MnO, 9.2 - 10.3% A101.5, 1.2 - 1.4% CaS, and 5.1 - 9.6% "Mgo" (the balance).

Jan 1, 1980

By S Wainio, P J. Beckett, T Miller

Lichens are a symbiosis of fungi and algae. Air borne elements and gases are absorbed very efficiently over the entire surface of the lichen, because they have no protective structures such as a waxy cuticle or stomata. A survey in 1977 (one year before the Sudbury Regreening program began), indicated that several Cladonia spp had invaded the soil in Sudbury’s open birch woodlands. Pollution sensitive species such as Cladonia rangiferina and C. mitis occurred 20–25 km from the smelters. It was anticipated that the improvements in air quality and reclamation efforts would allow a natural invasion of pollution sensitive species into what once was a lichen desert that surrounded the smelters. The purpose of this project was to study the invasion of terricolous (soil-inhabiting) communities of lichens and mosses on reclaimed land in the Sudbury region 45 years after commencement of the Sudbury Regreening Program.

Aug 2, 2023

By A Specht, A Müller, V Montenegro, S Winkler, E Klaffenbach, A Schmidt

In the process of primary copper smelting in flash smelting furnace (FSF), the ratio of iron to silica (Fe/SiO2 mass ratio) primarily determines the slag viscosity and magnetite formation. Viscous slag does not only cause difficulties in daily operation, such as in tapping, it also increases the copper losses to slag. Thus, keeping the Fe/SiO2 mass ratio at the desired level is an important aspect of FSF and slag cleaning furnace (SCF) operation. In this study, the improvement of the Fe/SiO2 mass ratio was conducted in two steps: First, the optimal Fe/SiO2 mass ratio was derived based on thermodynamic data. Based on this analysis, appropriate control limits were determined. Second, this range of favourable Fe/SiO2 mass ratios was implemented into operation by an advice-based control system, which suggests the addition of silica based on the analysis of SCF slag. As this approach was successful, the same advice-based control system principle was adapted for the coke addition to the SCF. After testing the new advice-based control for several months, the production data confirm the predictions by thermodynamics: since the prediction was implemented as an advisor, the copper and magnetite content in SCF slag is significantly reduced and viscous slag is reported less often by operations.

Aug 21, 2024

By M Yahyaei, F Vos, J Siliezar

Site-based case studies (including data collected from industrial surveys) and their application in evaluating circuit performance, have a significant role in developing reliable process models. Such models are useful to both plant metallurgists and researchers. Appropriate process models enable the plant metallurgist to assess the impact of different operational parameters on the overall circuit performance. They also provide the researcher with a detailed understanding of process behaviour in response to changes in ore characteristics and process conditions (ie plant throughput, ore competence, ore type). Thus enabling the identification of effective operating factors, and allowing them to be ranked in order of their influence on the process response, which eventually develops into a process control tool in the hands of plant operators.The above approach has been developed and applied at the Julius Kruttschnitt Mineral Research Centre (JKMRC) separately for both comminution and flotation processes. In recent years, the JKMRC has attempted an integrated approach by developing process models that incorporate the impact of upstream processes on downstream processes. This is not possible using the traditional approach of separate comminution and flotation surveys, so conducting integrated plant surveys is crucial for success in developing integrated process models. This paper summarises industrial experience gained while conducting such an integrated plant survey at Glencore’s Ernest Henry Mining operation near Cloncurry in north Queensland. An appropriate approach should be taken to enable the alignment of different requirements from different processes during the plant survey. This, as well as the challenges faced in integrating comminution process models with flotation process models, are identified.CITATION:Yahyaei, M, Vos, F, Powell, M S, Siliezar, J and Perkins, T, 2014. Challenges in developing integrated process models based on industrial survey data, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 437–446 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By S Nkwanyana, I Govender

Batch experiments in a 0.6 m diameter mill have shown that improvements of about 13 per cent in the efficiency of energy utilisation can be realised in ball mills by replacing 25 per cent of the ball charge by an equivalent volume of cost-free critical size pebbles from AG/SAG mills. For a mill of a given size, speed and charge filling, the rate of size reduction of ore particles depends on (i) the frequency of grinding media collisions (ii) the probability of capture of ore particles between the colliding grinding media (iii) the probability of fracture of the captured particles. The probability of fracture depends on the magnitude of collision energy. The distribution of collision energy into shear and impact events determines the relative strengths of attrition breakage and impact breakage. The efficiency of energy utilisation depends on which of the two mechanisms of breakage is more desirable in a particular milling stage. In this paper collision data from a series of DEM simulations of a mill charged with steel media and a mixture of steel media and pebbles is presented in energy spectra and spatial distribution maps. The data provides the necessary detail to elucidate the improvements in the efficiency of energy utilisation in ball mills when using a mixture of pebbles and steel media.

Aug 24, 2022