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By K Smith

This paper presents an assessment of the Robertson (2010a) method within the CPTu inversion parameter framework of Been et al. (1987), using CPTu calibration chamber data presented by Jefferies and Been (2015) and in other literature to assess the validity of the method, with particular focus on applicability of the method to TSFs (i.e. its applicability to loose silts and silty sands). The assessment demonstrates that although the method estimates values of k consistent with calibration chamber data, the method estimates values of m that are generally 1.5 to 2 times greater than calibration chamber data. As a result of this, the method generally overestimates Ψ for values of Ψ less than 0, and underestimates Ψ for values of Ψ greater than 0. This may result in both overly conservative assessment of materials as potentially liquefiable and unconservative predictions of material behaviour for loose materials.

Jul 1, 2021

By G J. Lyman, F S. Bourgeois

As the prices of metals slide, financial control of mineral processing operations becomes more and more important. Control of a mineral processing operation implies measurement of grades, recoveries and losses, with every effort being made to recover more product from the same feed. Shareholders become more concerned with the transparency of the operations and the corporate governance.There is only one way to achieve this and this is by sampling and making good use of the results of that sampling. Sampling systems that provide only 'rough' figures are not good enough. Similarly, a competitive position in the marketplace demands close control of product quality. Maximisation of product output demands that the product just meet the specification so that product yield is maximised. Decisions based on precise sampling results carry less risk that those based on imprecise results.This paper reports some recent advances in sampling theory that permit full quantification of sampling distributions, not just the sampling variance as has been possible in the past. These advances can be used together with simulation methods to tie down sampling precisions and develop calculations that quantify decision making risk when using the sampling results. A number of examples illustrate the use of the new advances and a final example indicates the development of risk analysis curves in the coupling of sampling precision to sale of a commodity.CITATION:Lyman, G J and Bourgeois, F S, 2015. Sampling, corporate governance and risk analysis, in Proceedings MetPlant 2015, pp 27–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By R O’Sullivan, D Taylor, J G. McLellan, B Miller

The Mount Isa copper deposit is located adjacent to the city of Mount Isa, Queensland, and lies within a series of Palaeoproterozoic to Mesoproterozoic Superbasins. The deposit is hosted almost entirely within the Urquhart Shale (US), a unit of the Mount Isa Group sediments and part of the Isa Superbasin. The copper mineralisation is separated into two distinct orebodies: the X41 mine (1100 and 1900 orebodies) and the Enterprise mine (3000 and 3500 orebodies). The orebodies are situated in the hanging wall of the major controlling structures, the Paroo Fault, which has juxtaposed older basement Eastern Creek Volcanics against the younger Mount Isa Group sediments cf 1655 ± 4 Ma. Conjecture remains over the exact timing of this thrust event. However, it is clear that inflections on the Paroo Fault have a close association with the orebodies and are an important structural feature in the mineralisation of the Mount Isa copper deposit.The life-of-mine is reducing steadily and new geomechanical modelling techniques were employed to target structurally controlled mineralised zones in three dimensions. Following a structural review of the mine using underground mapping, structural data and core shed observations, a conceptual 3D mine model was constructed utilising existing data modelled in MineSight®. This conceptual model included all the main lithological units and structures. The conceptual model aimed to test the effects of deformation on the main lithological and structural components of the system and attempted to highlight areas of anomalous stress and strain that may indicate a higher likelihood of fluid focusing and mineralisation potential. This project was focused on testing the latter stages of a D3 event (NE–SW compression) and D4 event (SE–NW compression), which are considered to be responsible for the current location of the mineralisation.The fully coupled 3D finite element analysis models resulted in highlighting anomalous patterns of stress and strain and subsequent fluid flow as a result of the two deformation events. The NE–SW D3 simulation provided the best correlation with the known distribution of mineralisation. This event also indicated several areas on the Paroo Fault and within the US that have potential to host further areas of mineralisation. The SE–NW D4 simulation provided less of a correlation with known mineralised zones. However, this event may have been responsible for post mineralisation re-mobilisation of copper on a relatively small scale. Areas of maximum shear strain, shear stress, volumetric strain and fluid flow correlated well with areas of minimum principal stress and provided the best overall match with known mineralised zones. Furthermore, several additional highlighted areas provide a high potential for further discovery of copper mineralisation. Recent exploration drilling north of the Enterprise mine 3000 orebody, utilising geomechanical modelling as part of the targeting criteria, intersected copper mineralisation, providing further validation of the modelling results.CITATION:McLellan, J G, O’Sullivan, R, Miller, B and Taylor, D, 2014. Geomechanical modelling of the Mount Isa copper deposit – predicting mineralisation, in Proceedings Ninth International Mining Geology Conference 2014 , pp 197–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

The usefulness of laboratory studies - petrology and mineragraphy in the search for, and investigation of, mineral deposits should not be exaggerated, but it should not be overlooked, because such studies will always contribute to an understanding of the geology of the deposits, and can on occasions provide invaluable information not otherwise available. A few examples furnished by the investigations of the Mineragraphic Section of the Commonwealth Scientific and Industrial Research Organisation will show this.Petrology.In the early stages of the investigation of the King Island scheelite deposit, during the war, when the nature of, the deposit was not understood, a series of samples embodying the exposed rock types was submitted to the Mineragrap;hic Section for petrologicalexamination by the Mineral Resources Survey. It was at once apparent to the petrologist that the King Island scheelite ore was a contact metamorphic deposit, in which a series of argillaceous shales, calcareous shales, impure limestones and limestones had beenintensely metamorphosed. The shales had been converted to finegrained biotite and actinolite hornfels, according to their lime content, and the impure limestones to fine-grained diopside hornfels, garnetdiopside hornfels and garnet hornfels (calc-flint), the garnet being the lime variety grossularite. The limestones, however, after being first converted to marbles, had suffered intense pyrometasomatism, involving substitution of immense quantities ,of silica and' iron for lime and carbonate, and had been converted largely to a coarsegrained garnet rock, in which the garnet was the lime-iron variety, andradite. The silica and iron were derived from the mineralising solutions of the adja,cent ,granite. intrusion, responsible for the contact metamorphism, and were accompanied by tungsten and some molybdenum. The tungsten in the presence of so much mobile lime, was precipitated as schecelite, much of it finegrained and enclosed in or intergrown, with the andradite garnet or the quartz interstitial to the garnet.It was apparent that the King Island scheelite deposit, was a perfect example of selective pyrometallomatic replacement in a bedded contact metamorphic deposit. The bedded nature of the original rocks was preserved, and the scheelite was practically limited to the original limestone beds, 'Which had been so much more susceptible to replacement after recrystallization, than the other sediments. The further geological study of the deposit then resolved itself into the task of mapping the folding and faulting of the deposit, with bore cores to provide the stratigraphic sequence, and establish the number of scheelite-bearing beds.A second example is provided by a petrological investigation of the mineral composition and genesis of the talc deposits of the Gumeracha district of South Austral.ia, which was undertaken at the request of the South Australian ,Mines Department, in conjunctionwith mapping of these deposits. The field geologist mapping the deposits was experiencing some difficulty in interpreting the structure...

Jan 1, 1950

By L Mikhael Gurieff, D Baas

The Phu Kham Copper-Gold Operation (Phu Kham Operation) is located in the Lao People's Democratic Republic and is owned and operated by the Lao-registered company, Phu Bia Mining Limited (PBM). Australian-headquartered copper and gold producer, PanAust Limited holds a 90 per cent interest in PBM; the Government of Laos owns the remaining 10 per cent. The Phu Kham Operation was commissioned in 2008 with an initial concentrator nameplate throughput of 12 million tonnes per annum (Mt/a). Subsequent improvement projects, including the Phu Kham Upgrade Project (PKU), completed in 2012, and the Phu Kham Increased Recovery Project (IRP), completed in 2013, increased the design throughput to 18 Mt/yr. In 2016, the actual mill throughput exceeded 19 Mt/a, this throughput is budgeted to be maintained until the end of 2020.The concentrator flotation circuit upgrade, completed during the IRP, called for a non-selective bulk sulphide concentrate to be generated from the rougher circuit. This in turn caused the mechanical flotation cells in the cleaner circuit, particularly those in the second cleaner bank, to become volumetrically overload. The overload reduced the cleaner circuit performance to approximately 92 per cent copper recovery at a 23 per cent copper concentrate grade, below the expected 95 per cent recovery. This bottleneck restricted copper units entering the plant to approximately 14.5 tonnes per hour (t/h) due to uncontrolled recirculating load build-up in the mechanical cleaning circuit.Maintaining the operating methodologies would have led to a copper production shortfall beyond 2016, to address this shortfall the Phu Kham Operation looked to optimise the Jameson Cell and mechanical cleaner circuit performance. The work included fundamental application of flotation practice and modelling, mineralogical analysis, bubble size analysis, plant surveys and test work. The results were used to develop and implement an innovative automated control system strategy incorporating flotation theory and operating strategies. The automation has the ability to quickly adapt to disturbances in the circuit and maintain optimised performance with little or no intervention by flotation operators.Upon completion, cleaner recovery increased to 95 per cent at a final concentrate grade of 23 per cent copper, and copper units entering the plant increased to 17.5 t/h.CITATION:Baas, D and Mikhael Gurieff, L, 2018. Developing flotation circuit control and automation for the Phu Kham Copper-Gold Operation concentrator, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 37–58 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Kentwell D. J, Cusak C. J, Harvey-Kelly F. E L, M D. Goodz

The Morning Star Gold Mine presents an example of a prolific operation with considerable historical records, mine workings, drill hole logs and countless plans from greater than 20 adjacent mines which have now been consolidated to form the current project. Implementation of 3D computer modelling in the planning stages has provided an additional tool to integrate and refine geological models as a guide to some exploration strategies. It has allowed for a re- interpretation of the host rock units, dimensional constraints, new exploration extensions and provisional resource modelling. The initial consideration of this project was to integrate 135 years of mining history into a single database. Each historic mining area had an unrelated mine grid, often established parallel to the long axis of their main stopes; some were based on magnetic or true north. Survey plans were in chain, imperial or metric units. Through the manipulation and rotation of old grids, previously unrelated mine workings began to form continuous mineralised zones, with unmined portions still remaining in between the existing development. Furthermore the current drillhole database of >433 holes showed numerous confirmatory intersections of new mineralisation. A series of tiered tables were created within a relational database to derive guidelines for assessing data to attribute a Mineral Prospectivity Value [MPV] based on key indicators of mineralisation. Indicator logging now forms the basis of geological descriptions.

Jan 1, 1997

Applicaton of Agricultural Residues from Pyrolysis in Flotation of Black Coal

Sep 13, 2010

By R Zhang, X Huang, M Zhou, X Lv, C Bai

Iron ore sinter accounts for a large proportion of blast furnace ferrous burden in Chinese steel mills. Depleting high-grade iron ore resources and spreading complexity of iron ores in mineralogy and morphology have made it more difficult to utilise iron ores efficiently and economically. In this paper, the physical properties of iron ore particles were characterised using mechanical sieving, laser sizing and gas adsorption. From those measurements, two physical indices (fractal dimension of the particle size distribution and surface morphological factor) are defined as important variables for optimising the granulation performance of iron ores. The moisture capacity and the contact angle of iron ore particles with water were also measured to determine the strategy of water-feed in the granulation process. It can be concluded from the experimental results that an increase in the fractal dimension of the iron ore particles will lead to a better granulation performance, while an increase in moisture capacity with a range of 12.8 ~ 14.8 per cent would increase the optimum water content where the granule packed bed achieves its best permeability. Furthermore, the optimum permeability varies inversely with the moisture capacity of the sinter mixture.CITATION:Huang, X, Lv, X, Zhang, R, Bai, C and Zhou, M, 2013. Iron ore characteristics and their application in optimising the granulation process, in Proceedings Iron Ore 2013 , pp 261-268 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By D T. Ribeiro, J F. C L Costa, J C. Koppe

Drilling and sampling are responsible for most of the costs during mineral exploration, especially in multi-elements and polymetallic deposits, such as iron, manganese and bauxite deposits. On these deposits, often it is necessary to estimate multiple attributes at several granulometric fractions, ie distinct particle sizes. This paper investigates the effect of sampling at a close spacing grid only the head grades for the multiple chemical species in iron ore deposits. The remaining required data at the various grain sizes are sampled at a sparse grid. The derived geological model is checked for precision and accuracy comparing the output obtained against a model obtained using a complete isotopic data set including head grades and chemical analysis at each granulometric fraction analysed at all sampled positions. Among the several tested alternatives, the best procedure for dealing with the posed problem involved utilising the correlation coefficients between the grades at distinct fractions to obtain an isotopic database prior to interpolation. Cokriging was the method used, based on the intrinsic coregionalisation model. Estimates were obtained with the quality needed for the proposal of the study. Results showed that at least 50 per cent of the blocks were estimated with errors less than ten per cent relative to the grades obtained at the reference model, using only 15 per cent of the granulochemical data employed to obtain the reference model. The methodology also preserved the correlations between the attributes in their several granulometric fractions on the estimated model.

Sep 26, 2011

By A M. Lechner, S Arnold, M J. Gillespie, P D. Erskine, D R. Mulligan, A T. Fletcher, A Gordon

Mine ecological monitoring schemes are often conducted only to address compliance and in some cases do not have the sufficient statistical power or understanding of ecological systems to assess, quantitatively, the meeting of rehabilitation targets or mine impacts. Monitoring schemes for rehabilitation commonly rely on analogue sites or premining baselines (reference sites) to assess whether rehabilitation sites are ecologically similar and thus successfully rehabilitated. In the case of monitoring for mine impacts, if the impacted sites diverge from reference data, the site is considered to be impacted. Fundamental to any monitoring scheme is testing the sampling design to ensure that it can detect these differences if they are present through adequate sample sizes (ie statistical power). However, a good understanding of the ecological system is required to ensure that differences detected are ecologically significant. Modelling ecosystem properties can provide a quantitative understanding of how ecosystems change over time and space, in response to natural environmental variations and thus aid in determining significant ecological differences. Furthermore, modelling methods can be used to predict future ecosystem states. Within the ecological literature, guidelines for robust statistical monitoring designs and modelling methods exist but are not routinely being used in the mining industry. This paper uses simple examples to discuss: problems with current compliance monitoring methods; importance of robust statistical techniques; and how modelling can assist rehabilitation assessment and guide monitoring schemes. The aim of this paper is to describe general monitoring and modelling methods that could be potentially used for mine site monitoring and closure assessment. These methods are often considered by mining companies as an extra expense that provide little practical benefit, and the domain of academia; however, engaging these methods may be more cost-effective in the long-run than conducting untargeted monitoring schemes that give no confidence to regulators on whether rehabilitation criteria have been met. Furthermore, monitoring programs in mining contexts provide a good opportunity to better understand long-term ecological patterns and test the application of more rigorous modelling approaches as the life of many mines tends to be greater than ten years.CITATION:Lechner, A M, Arnold, S, Fletcher, A T, Gordon, A, Erskine, P D, Gillespie, M J and Mulligan, D R, 2012. Embracing modern ecological methods - Monitoring and modelling for mine closure, not compliance, in Proceedings Life-of-Mine 2012 , pp 25-32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

Jan 1, 2004

By K Shannon, A Shaw

The Hilton and George Fisher deposits occur 22 and 24 km north of Mount Isa, NW Qld, Australia respectively. Both deposits occur as deformed Proterozoic, sediment hosted, stratiform orebodies hosting Pb-Zn-Ag (Hilton) and Zn-Pb-Ag (George Fisher) mineralisation. The two deposits are separated by approximately 2 km of strongly faulted barren shales, mudstones and siltstones along strike. Despite this, correlations between the Hilton and George Fisher deposits have previously been assumed on the basis of textural, lithological and geochemical similarities, but previously lacked specific details to prove exact stratigraphic matches.Feasibility drilling allowed broad correlations based on the position of siltstone pillars separating individual orebodies. However the position of continuous potassium-rich, siliceous and cross-fractured tuffaceous marker beds (TMBs) often used as stratigraphic markers within the Hilton Mine were initially unrecognised within the George Fisher stratigraphy where they are erratically silicified and often not cross-fractured resulting in correlations being difficult to prove. As a more detailed knowledge of TMB locations at George Fisher was gained it was possible to look for corresponding TMBs within the Hilton orebodies. Recent underground stope definition drilling at the two locations enabled specific TMBs, stratigraphic units and even individual sedimentary beds to be matched between the two locations, despite the large separation between mines.The correlation between the two deposits has implications for future exploration drilling north of George Fisher. If a specific stratigraphic horizon can be determined within one hole, positioning of further drillholes can be more accurately planned. The significance of having stratigraphic matches between Hilton and George Fisher also has implications for correlations with other Isa Valley deposits. Convincing preliminary TM and stratigraphic correlations have already been made between George Fisher and the Isa Lead Mine 24 km to the south.

Jan 1, 2002

By S Watson, L Martinez

Mine projects are complex opportunities that demand a constant assessment of uncertainty, ie risk and upside potential. This is because the value of a mine project is typically influenced by many underlying economic and physical uncertainties, such as metal/mineral prices, metal/mineral grades, costs, schedules, quantities, and environmental issues, amongst others, which are not known with much certainty at the beginning of the project. But, is uncertainty an enemy or an ally of the mine planner/analyst? To answer this question, this paper first assesses and elaborates upon the general concept of uncertainty. It then looks at the different sources of uncertainty in a mining project, such as the orebody, costs and product price uncertainties, and their effect on the final project value. Next, a general?review?of current mine evaluation techniques highlighting their limitations when dealing with uncertainty is made. Finally, an extended evaluation and risk management framework that addresses the existing uncertainty in the (greenfield/brownfield) mine evaluation process is proposed. One important characteristic of this framework is that it uses and manages uncertainty in order to generate additional value to the project; this is done through operational and managerial flexibility, which allow mine planners to minimise/maximise project risk/upside-potential giving a more realistic estimate of the projectÆs market value - this is shown in practical and simple examples occurring at different stages of a mine project, such as exploration and operation. Final conclusions are provided at the end.CITATION:Martinez, L and Watson, S, 2012. Uncertainty - An important source of (additional) value for mine projects, in Proceedings Project Evaluation 2012 , pp 131-140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

Study on the Interaction Mechanism of Flotation Reagents and Rare-Earths-Bearing Phosphate Ore

Sep 13, 2010

By A T. Spathis, M L. Lawlor-O’Neill

A methodology for the inversion of a scaled charge weight superposition model to predict peak particle velocity (PPV) has been examined. The inversion involves two steps: first simulated annealing is used to get an initial estimate of the model parameters; and second, these parameters are used as input to a quasi-Newton non-linear optimisation method, used to refine the value of the parameters. The methodology recovers the three required parameters (two charge weight scaling parameters and a time window width) and does this directly from a single production blast for a given point of interest. It has been tested on a synthetic example and recovered the input model parameters successfully in the presence of introduced noise with a coefficient of variation ranging up to ten per cent. Another test used the vibration measurements of three tunnel blasts monitored during the construction of the Citybanan tunnel in Stockholm. In this case, the three model parameters are found from one blast and for a given point of interest, and the PPV at the same point of interest is predicted for the second and third blast fired in the same vicinity as the first blast. The three blasts used different firing sequences. The predicted PPV limits use a confidence interval determined from the scatter in the peak levels obtained from the single calibration blast. The methodology was able to predict an upper bound for the PPV in 21 of the 26 tunnel blast vibrations studied. These predictions improve on a previous study involving the same model but which did not use the inversion process above. Given this reasonable success, further testing of the method on other data sets and alternative forward prediction models is recommended.CITATION:Lawlor-O’Neill, M L and Spathis, A T, 2015. An inversion method for the prediction of peak particle velocity in blasting, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 97–108 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By R Millar

A frequent challenge in mine water management and mine design is estimation of precipitation and extreme rainfall given a short record of site meteorological data. For remote mine projects, typically only a few years of rainfall data are available, which is far too short for estimation of design rainfall event, such as the 1-in-100 year storm. A frequency-paired approach is presented for comparing daily precipitation records from a mine site with a long-term regional station and provides the basis to transpose the long-term record to the mine site. This allows a long-term synthetic precipitation record to be developed for the mine site that can be used to undertake site water balance studies, determine pond storage requirements, assess water supply options and address other surface water management issues. Conventional approaches are based on chronologically-paired data and when applied to daily data generally yield poor correlations between stations. In the frequency-pairing approach, statistical distributions (two-parameter gamma distribution) are fit to daily data from two stations and used to calculate daily and extreme precipitation values for the short-term site (which is typically a mine or other project site). The method is demonstrated using data from two meteorological stations located along the south coast of British Columbia, Canada. Use of a fitted two-parameter gamma distribution (or other distribution) provides a sound theoretical approach to comparing precipitation data from two sites and the basis for transposing a long-term record to generate synthetic precipitation series and extreme rainfall values at mine sites.CITATION:Millar, R, 2013. A statistical approach for deriving project design rainfall, in Proceedings Water in Mining 2013 , pp 273-276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

Any Australian who knows of the poverty of the early settlers in the first few years following the arrival of Captain Arthur Phillip with his "first fleet" at Botany Bay must feel proud of the progress that has been made in the 174 years that have elapsed since that momentous occasionGFor all its attractive appearance as reported by Captain Cook and Sir Joseph Banks, the shores of Botany Bay and of Port Jackson proved most ,inhospitable, and the accessible country surrounding them anything but suitable for sustaining the life of the small settlement. It is well known that during the first 15 or 20 years the hardy colonists and un-tfortunate convicts were close to starvation on several occasions and were only saved by the arrival of supply ships, which were dependent on the vagaries of wind and current, and the hazards of the uncharted seas they had to -navigate-.When Australia was little more than a miserable penal settlement, Great Britain was one of the great-powers of the world, and the U,.S.A. was an independent nation with a growing degree of prosperity that even then gave promise of its mighty awakening to become, as it has, a e.olossus of industry and commerce,-and the. leader in living standards of the world to-day.Australia, from such a shaky, and comparatively recent start, has risen to a position in which its living standards rank very high in comparison with those of most of the nations of Europe and America. Exact com-parisons are hard to fix because of the wide variety of factors involved .but the Institute of Pab?Lic Affairs .(Victoria) places Australia fifthin the world, excelled only by the U.S.A., Canada, Sweden and Switzerland. The next best after Australia are the United Kingdom, West Germany and France.How we achieved such a high standard of living is a vast subject for study but some of the economic aspects of our climb from abject poverty to a position of near affluence can readily be identified.

Jan 1, 1962

By H Ishikawa, H Zhou, M Spagnolo, R Halomoan, S Palaniandy

The Karara Mine concentrator commenced operation in November 2012 to produce high-grade magnetite concentrate. The circuit consists of three stages of comminution plus magnetic separation at each stage for early gangue rejection. High-Pressure Grinding Rolls (HPGRs) are used for fine crushing, followed by ball mills and TowerMills in secondary and fine grinding duties respectively. In recent times, the plant throughput rate has had to exceed design by 18% to maintain the targeted concentrate productivity. Meanwhile, the ore hardness has increased by 25% to 15 kWh/t, leading to changes in the circuit operation and design. These changes led to coarser and harder feed to the TowerMill circuit that affects the subsequent separation processes. Nippon Eirich (the TowerMill manufacturer) has partnered with Karara Mining Limited (Karara) to optimise the TowerMill circuit operation to achieve a circuit product with an 80% passing (P80) of 35 µm. Several activities, including a TowerMill circuit audit and performance evaluation, multi-component analysis, modelling and simulation, were carried out as part of the optimisation exercise. The circuit audit results revealed that the TowerMill circuit feed size F80 had increased and ranged from 67–75 µm. The circuit product P80 ranged between 42–55 µm. The average circuit specific energy was 3.4 kWh/t. Moreover, the differences in density between magnetite and gangue minerals had affected the hydrocyclone performance where the efficiency curve exhibits coarse end deflection indicating that low-density coarse material was bypassing to the overflow stream. A multi-component analysis was carried out to further investigate the coarse end deflection of the hydrocyclone efficiency curve. The analysis showed that the magnetite and gangue minerals had different cut sizes of 32 and 64 µm respectively. Furthermore, 33% of the magnetite (below 35 µm) was being recycled back to the mill due to the density effect. Based on these findings, several recommendations for process improvement were identified and implemented including:• converting to a bottom feeding configuration to improve the grinding efficiency in the mill• additional grinding power in the fine grinding duty to compensate for the increase in plant throughput and ore hardness• improved classification efficiency by converting to smaller size hydrocyclones. Simulation studies carried out to evaluate the impact of these implementations had indicated that a P80 close to 35 µm with a steeper size distribution could be achieved by using the bottom feed configuration with additional grinding power. The TowerMill circuit was converted to bottom feed configuration and the performance was evaluated. The operating work index, size specific energy and circulating load were 30% lower than the top feed configuration, indicating that the bottom feed configuration had a higher grinding efficiency. This paper discusses the outcome of the circuit audit, multicomponent analysis, circuit simulations, improvement strategies and quantification of the improvements. CITATION:Palaniandy, S, Spagnolo, M, Halomoan, R, Zhou, H and Ishikawa, H, 2017. Fine grinding circuit process improvement at the Karara mine concentrator, in Proceedings MetPlant 2017, pp 101–120 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

This paper sets out to discuss how alluvials - particularly mineral sands, tin and gold have adjusted to meet the problems of lower grade and more difficult physical political and economic conditions. The mineral sands industry seems to have adapted satisfactorily but less so with tin and gold.

Jan 1, 1996

By M F. Gazley

The amphibolite-facies metabasaltic rocks of the Mine Mafic Package at Plutonic Gold Mine, Marymia Inlier, Western Australia, contain an estimated total endowment of 12.2 Moz of Au, which includes 4.71 Moz of past production and 2.77 Moz of reserves and resources; the remainder comprises lower-grade inventory. Over 65?000 multi-element analyses of whole-rock core and face channel samples from the underground workings of the deposit have been collected by portable X-ray fluorescence (pXRF) using a handheld Innov-X Omega pXRF unit. The analyses were performed on pulverised samples through paper bags, and were corrected using a pulverised, matrix-matched, reference standard. This method of data correction compares favourably with conventional XRF analyses performed on the same samples.A preliminary study based on pXRF analyses from a small number of drill holes found that a geochemical stratigraphy was evident in the pXRF data, and that this stratigraphy strongly controlled the location of Au mineralisation. The present study incorporates a much larger pXRF data set that samples a greater volume of diamond drill core and face channel samples and presents the data in a three-dimensional (3D) framework.This data set allows an investigation of the mineralogy of Au mineralisation with varying geochemical associations across the deposit. Historically, there has been a strong relationship identified between As and Au, which has caused issues with metallurgical performance, rendering some areas of the deposit only marginally economic. Utilising seamless data integration of the pXRF data set allows for recognition of the different styles of Au mineralisation using elemental concentrations and ratios from the multi-element analyses (Au:As, Au:As:Cu, As:Cu vs. K:V), and to visualise the distribution of these different mineralogical associations in 3D. The results of the 3D modelling and geochemical characterisation of the different styles of Au mineralisation are currently the focus of an extensive metallurgical testing program, the preliminary results of which are presented here.

Aug 22, 2011