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By R Rimmelin, C Vergara

Heap leach pads are composed of mined ore, usually crushed, disposed on liners to be processed with leach solutions, and the tail of the process is called “spent ore” which are then transported by conveyor belts to be disposed into dumps. It is often to observe stability problems in these dumps, that could affect the equipment working on it and the continuity of the whole mine process. These problems are related to an excess of water content at the spent ore, therefore the operational efforts are focused onto control this geotechnical parameter.This work presents the results of different geotechnical laboratory testing, using samples of spent ore of a mining operation in the north of Chile. In the last 10 years, 3 campaigns have been made to get samples. Valuable information was obtained to identify how specific operational/metallurgical factors could affect the geotechnical behaviour of the spent ore. Special attention is given to the decision to change the metallurgical process adding salt to the heap leach process and its impact to its hydraulic conductivity.Historically, the process has been based on the leaching of oxides and sulphides materials, in separate campaigns, in which it is possible to observe different geotechnical response in the spent ore generated. Recently, it was implemented a new process in which the materials are blended and salt is added, to improve metallurgical performance in terms of recovery. This change generate impacts in the dump, since the geotechnical parameters are affected; decreasing hydraulic conductivity in about one order of magnitude (explained by the salt added).Changes are shown in the geotechnical parameters of the spent ore, considering that the mining source is the same, and how the operational process and dump design are affected.CITATION:Rimmelin, R and Vergara, C, 2018. Geotechnical behaviour of spent ore – impacts of metallurgical factors, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 369–375 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By G J. Lyman

Sampling of grain for mycotoxins is challenging in that some mycotoxins, such as Ochratoxin A (OTA), have very low permitted levels and the kernels carrying the mycotoxin may be highly localised within the bulk of the grain as ‘hot spots’. Sampling for genetically modified organisms (GMOs) can be fraught with similar problems, especially if the contamination is adventitious and random. Incremental sampling under these circumstances can be shown to lead to a high variance in the sampling result.A new design of sampler for grain and other free-flowing particulates has been developed that is effective in practically eliminating the sampling variance due to distributional heterogeneity (DH).This paper introduces the design and argues that the sampler should be free of sampling variance due to DH.CITATION:Lyman, G J, 2017. A new sampler for grain and other free-flowing particulates, in Proceedings Eighth World Conference on Sampling and Blending , pp 277–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By B Mohanty, D Zwaan

Systematic near-field vibration monitoring of stope blasts was carried out in a large, deep underground mine. A total of 31 production blasts were studied in order to investigate the effectiveness of existing blast designs. This involved the vertical retreat mining method, which requires drilling a raise bore or blasting a slot raise (typically 1.22 m in diameter) using large diameter boreholes (165 mm). The diagnostic technique employed multistation near-field monitoring of blasts with high-g (100 g) and high-frequency (>10 kHz) triaxial accelerometers. The amplitude of the vibrations is correlated with the strain energy transmitted from each explosive deck. The results showed that more than 30 per cent of the explosive decks contributed little energy to the rock breakage process in these blasts, and an equal number contributed only inadequately. These findings are indicative of serious blast malfunctions. The problems can be traced to inadequate deck blast design and possibly to drill hole deviation. The various causes for such malfunctions are discussed and remedial measures suggested.CITATION:Mohanty, B and Zwaan, D, 2015. Assessment of underground production blast designs and blasting performance, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 607–616 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By A Manfrino

The Iron Bridge magnetite mine and infrastructure project is currently in development as a joint venture between Fortescue Metals Group, Formosa and Baosteel. It is supported by an extensive database of reverse circulation drill hole samples analysed by X-ray fluorescence (XRF), with a large subset tested for concentrate mass recovery, concentrate and tail grades by Davis tube recovery (DTR) testing. A limited number of rock physical testing results, including unconfined/uniaxial compressive strength and crushing work index, completes the database.By combining all available information – assays, DTR results, geology, stratigraphy, mineralogy and rock physical results – and using multivariate statistical analysis techniques, the impact of the critical factors that control concentrate quality, mass recovery and grindability characteristics have been outlined. A set of geochemical groups was created by using a cluster analysis technique from the combined XRF-DTR data. These groups allow optimal separation of material with consistently high concentrate Fe grades and mass recovery. This approach is superior to domaining based on stratigraphic logging or mass recovery as it is commonly used in standard magnetite estimation models. Using the results of a normative mineralogy study, the main geochemical groups were given a mineralogical profile fitting their geochemical characteristics. These findings further refined the understanding of the link between the process characteristics of the samples and their geochemical signature and mineralogy.The geochemical grouping defined on head grades and DTR concentrate mass recovery was generalised into a ‘geomet’ code based solely on the routinely assayed head grades, thus bypassing the need for systematic DTR testing. The geomet code identifies spatial domains with homogeneous geochemistry, mineralogy and process characteristics in both oxide and fresh material that form the basis of the current Iron Bridge resource model. The allocation of geometallurgical characteristics in terms of concentration amenability and concentrate characteristics on a block-by-block basis over the whole project allows for an optimum mine schedule and plant feed. This ensures that the desired concentrate characteristics and mass recovery can be better predicted over the life-of-mine, thereby improving the mine’s economics and stability by derisking the mine schedule and optimising the performance of the concentrators. A key benefit of the geomet code devised for the Iron Bridge mine is that it can be attributed in an automated manner to all samples analysed for a routine XRF analytical suite, from exploration to blasthole drilling. This allows each sample to be allocated to a geometallurgical material type with predictable process response in terms of concentrate mass recovery and concentrate quality without the need to complete systematic DTR testing.A standard multivariate analysis coupled with a cluster analysis has allowed the linking of interdisciplinary results between geology, mineralogy, geochemistry, process and metallurgy to better understand, predict and ultimately mine and process the Iron Bridge deposits. This allows plant operations and product quality to be optimised through each stage thanks to the predictable ore characteristics embedded in the mining model.CITATION:Manfrino, A, 2015. Unravelling the factors impacting on concentrate quality by geometallurgical data analysis at Fortescue Metals Group’s Iron Bridge magnetite mine, in Proceedings Iron Ore 2015, pp 567–578 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By C Jones

When the Paulsens operation was poised to be placed on care and maintenance, Bill Beament and the rest of the Northern Star Resources (NSR) team capitalised on the opportunity to send the Ashburton region’s only operating gold mine into the record books.A three-stage strategy was devised by NSR to pay off the acquisition and maximise the return from the operation. The first stage was to mine the 55 000 oz mine plan and pay off the cost of the acquisition, then maintain profitable production beyond the seven months and re-establish a mine life. The second stage involved an early commitment to a 220 m long diamond drill drive being placed in the hanging wall of the orebody from which the extensions of the orebody could be further explored, allowing the second stage of the plan to come into effect and extend the mine life by converting Inferred Resources into the mine plan. The third stage of the initial plan was to utilise this drill drive and continue to drill deeper holes beyond the current limit of drilling in the ore zones to extend the orebody and increase the mine’s life.With an ever growing desire to further expand, the young company took on the bold move of establishing its own mining services division. A critical element to the success of this was ensuring that the right people were recruited with the appropriate specialised skill sets.Aligning common goals amongst all NSR team members, from the board and senior management to the work force on site, was critical to integrate the new and driven direction that Paulsens had adopted. It was essential to change the focus and a shift in all employees’ attitudes and values from a mine that was all but down and out, to a site that wanted to be kicking some serious goals.Teaming together a passionate and driven leader with a strong allied workforce was always going to put NSR in the best position possible to make Paulsens the success story that it now is. But without the calculated risks and enthusiastic attitude, the little known mine site in the Pilbara might have remained just that.CITATION:Jones, C, 2014. The Paulsens transformation – a shining light under a northern star, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 191–196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By A Gray

Physical separation features in almost every mineral processing circuit. The category encompasses a broad range of techniques and technologies including hydrocyclones, gravity concentration methods (including jigs, spirals, centrifugal concentrators, tables, heavy media separators) and thickeners, all of which make use of the inherent density differences between two mediums. It is also possible to include flotation, magnetic separation, and ore sorting in the physical separation category.However, opportunities for enhanced physical separation performance can now go beyond the common practice of optimising unit operations. Improved options exist for feed preparation ahead of the physical separation stage, enabling higher performance and lower cost outcomes for physical separation flow sheets and technologies.The use of new applications in breakage technologies combined with mineral liberation analysis to optimise liberation prior to the physical separation stage provides options for preconcentration and gangue rejection as well as better separation efficiency. The use of low cost gangue rejection and preconcentration can be an intermediate step between mining and processing that allows processing of lower cut-off grades from the mine whilst delivering higher grades to the mill.Optimising flow sheets and technology performance requires detailed understanding of particle size and shape distributions as well as liberation characteristics to suit the particular separation unit, combined with knowledge of the available technologies, their capabilities and the economic impact across the whole mine cycle.CITATION:Gray, A, 2017. The role of liberation in physical separation techniques, in Proceedings MetPlant 2017, pp 147–156 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By J Rutter, D La Rosa, P Walters, M Scott, L Keeney

Bulk ore sorting technologies, whether surfaced based or penetrative, have seen an increased uptake by the mining industry for preconcentration application. As with all technologies, going through the technology validation process is key to de-risking the operationalisation of the technologies and to demonstrate and confirm predicted value propositions. The ability to laboratory calibrate cross-belt bulk sensors is standard practise for sensor vendors, however transitioning the technology from laboratory to real-world application is a non-trivial process. The industry has taken two main approaches to trialling and validating bulk sensing technologies in operational environments, namely:  Construct an off-line pilot facility at scale, or  Install bulk sensing systems on production conveyors Each of these two approaches have significant advantages and disadvantages and require different experimental design programs and analysis methodologies. Consideration of material movement, heterogeneity degradation, logistical requirements, and financial investment all factor into which approach is most suitable for an evaluation scenario. CRC ORE in partnership with mining companies, have conducted several bulk sensor pilot trials utilising different sensor technologies employing each of the two main approaches outlined above. This paper describes the challenges faced, learnings obtained and outlines a position on how to transition bulk sensing technologies from the laboratory into the operating environment. The case studies presented cover a range of commodity types in both open pit and underground operations.

Nov 10, 2020

By S Hapugoda

Iron ore oxide and oxyhydroxide minerals such as haematite (eg various types of martite and microplaty haematite), different forms of goethite, magnetite, hydrohaematite and kenomagnetite were analysed using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) techniques, to determine the type and proportion of deleterious elements present and the chemistry of associated gangue minerals. The aim was to characterise elements potentially deleterious for agglomeration and steelmaking, eg sulfur, phosphorus, aluminium and silicon and correlate their distribution with mineral texture and association, to provide feedback on downstream processing performance and product quality.Examples of characteristic mineral associations are shown from various genetic styles of iron ores, including magnetite banded iron formation (BIF), BIF-derived martite-goethite and skarn-type magnetite ores.A number of examples are presented demonstrating the benefits of the use of combined techniques of reflected optical microscopy, SEM and EPMA data to reliably identify ore and gangue minerals and their associations in different types of iron ores.

Jul 11, 2011

By T Baumgartl, B Richards

The association of specific plants and plant communities with soils developed over underlying superficial orebodies and mineralisation has been long recognised. It has given rise to the use of plant indicators for geobotanical exploration as a regular component of primary minerals reconnaissance where there is an undisturbed vegetation cover. That the chemical composition of indicator plants is a measure of their soil environment has further led to biogeochemical prospecting methods for minerals and its use in the mapping of underlying ore deposits. Where there is a strong surface expression of metal and metalloid anomalies, concentrations of potentially phytotoxic elements may reach a level at which they have strong selective impacts on plant populations. In such circumstances, natural selection has operated in the development of a unique flora composed of plant species and individuals with genetically-based tolerances to the stressed environment in which they continue to survive. These plants are called metallophytes. Metallophytes occur globally on all metalliferous sites, both in pristine undisturbed environments and in areas of mineral workings, ancient and modern. However, the best-developed primary metallophyte vegetation is found in the most ancient areas where there has been a long-term evolutionary impact of the underlying geology through ore weathering and dispersion of metals into the rhizosphere zone. Natural selection of metal-tolerant races of plants in these largely undisturbed areas can eventually lead to speciation and the development of an endemic regional metallophyte flora (Baker et al , 2010). Mineral wastes resulting from mining activities also allow colonisation by metal-tolerant individuals leading to the establishment of metallophyte communities. The distribution and extent of such communities is determined by regional and local factors relating to climate and substrate conditions and the availability of suitable plant resources on which natural selection can operate (Baker, 2009).The ability of metallophytes to tolerate extreme metal concentrations commends them as the optimal choice for ecological restoration of mineral wastes and metal-contaminated sites. Metallophytes have recently also spawned several novel phytotechnologies, including phytoremediation and phytomining (Chaney et al, 2000, 2005; Baker and Whiting, 2008). Action towards conserving the global metallophyte resource base is imperative because many species are under threat of extinction from new and extensive mining activities (Whiting et al, 2004). This has been identified as a priority in the Mining, Minerals and Sustainable Development (MMSD) Project of the Global Mining Initiative in 2002 but positive responses from the minerals industry have been slow. The last decade has, however, seen an ever-increasing interest in metal-tolerant and metal-accumulating plants, both from an academic standpoint and their use in revegetation and phytostabilisation (Tordoff et al, 2000; Baker and Whiting, 2008; Baker, 2009). Few studies have highlighted the need to conserve and develop these unique plants (Whiting et al , 2004). This presentation identifies future research needs for the conservation and exploitation of the global metallophyte biodiversity and its potential in sustainable mine closure. CITATION:Baumgartl, T and Richards, B, 2012. Evaporation and salt transport under variable climatic conditions, in Proceedings Life-of-Mine 2012 , pp 179-186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By M S. Fenzel

Increased environmental regulations and pressures have created changing and new demands for tailings management strategies in a variety of mining applications. Critical among these items is the disposal of tailings as the pursuit of increased yields and lower costs have driven the application of different process technologies. With a number of technologies having a niche application focus, the belt filter press has been utilised for decades as a cost-effective and versatile option for dewatering different types of mineral tailings and other waste process streams. One of the critical advantages of the belt filter press is the technology’s ability to adapt and work in numerous plant designs, operating conditions and applications. As permitting and disposal options have become more stringent, plant designers, operators and equipment suppliers must develop comprehensive and site-specific economic, design and process evaluation techniques to ensure proper equipment selection and system design for belt filter presses or any other dewatering technologies. This paper will explore these techniques in relation to belt filter presses (with reference to other technologies) in a variety of different applications, along with other considerations to ensure a successful tailings dewatering system and disposal design. Summaries of equipment performance characteristics, operating and maintenance strategies and optimisation techniques will also be addressed in conjunction with the belt filter press’s adaptability to different plant designs and the resulting tailings characteristics.CITATION:Fenzel, M S, 2015. Analysis and adaptability of belt filter presses and other technologies for tailings dewatering over a range of mineral processes, plant designs, conditions, regions and operating philosophies, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 35–44 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By Dorricott M. G

Ballarat Goldfields NL is developing an exploration decline at Ballarat East using a Mitsui Miike S-125 roadheader. To-date, 530 in of advance has been achieved at an average rate of 16.1 m/week. Roadheader availability has averaged 94.3 per cent, and pick consumption has averaged 0.016 per m. Ground support has involved pattern rockbolting with split sets, 100 mm thick fibre reinforced shotcrete, and steel sets as required. The slower than expected advance rate has mainly been due to difficult ground conditions. It is expected that a further 970 in of decline will be mechanically excavated before a drill and blast system becomes more economical.

Jan 1, 1995

By L O. Filippov, I V. Filippova

Subsea massive sulfide deposits have particular mineralogical compositions and textural features differentiating them from onshore ore. When extracted from salty water and exposed to the air, massive sulfide samples strongly oxidise and soon become covered by thin layers of iron, copper and zinc-rich sulfates and oxides, as well as elemental sulfur. The textural properties vary according to the degree of maturity and the sample position within the hydrothermal deposit. Because of the variation of secondary mineralisation and porosity level, sea floor massive sulfides respond differently from terrestrial ore to processing methods. Froth flotation, commonly applied to separate all types of sulfides from the gangue minerals, is one possible treatment technique to process sea floor ore. Sulfide recovery rate is, in most cases, excellent (>90 per cent). However, separation of the various mineral phases is difficult to obtain even when applying known methods used for onshore ore. Moreover, the flotation behaviour decreases dramatically with time of conservation, even when the samples were stored in a confined environment. High pH range, which is a good way to depress pyrite and therefore to favour the flotation of copper and zinc sulfides, does not have the same effect on subsea ore. Consequently, careful flotation procedure should be elaborated to obtain efficient mineral separation for this specific marine ore.CITATION:Filippov, L O and Filippova, I V, 2015. Processing of subsea massive sulfide ores by flotation – similarity and features with terrestrial ores, in Proceedings Third International Future Mining Conference, pp 239–244 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By F Diaz, G Hovestadt, B Friedrich, D Latacz, M Sommerfeld

The metallurgical sector significantly contributes to the global carbon footprint and encounters the challenge of developing more sustainable production methods. This study introduces novel approaches aimed at reducing CO2 emissions within the industrial sector, some of which have been developed up to the demonstration scale. In two case studies, urban waste from the agricultural sector (corn, olives, coconut etc) and waste electrical or electronic equipment (WEEE) recycling residues (shredder light fractions (SLF)) were subjected to thermal treatment. The resulting materials were then used as substitutes for conventional fossil-based reducing agents in both the copper and ferroalloy industries. Furthermore, hydrogen was employed at different scales to assess its efficacy as a reducing agent for recovering metal oxides from fayalitic copper slags. Our findings reveal promising prospects and defined specific challenges for the integration of these alternative reducing agents in the industry. The synergistic use of pyrolysed SLF, bio-coke, and hydrogen presents a viable pathway to significantly diminish CO2 emissions while simultaneously improving the sustainability of the metallurgical sector.

Jun 19, 2024

By A N. Parry

In May 2018 Kasbah Resources Limited (“Kasbah”) completed an ore sorting test work program which was a precursor to releasing in July 2018 an updated Definitive Feasibility Study (“DFS”) for the Achmmach Tin Project in Morocco, which it is proposing to develop along with its joint venture partners. The testwork program evaluated ore sorting as a pre-concentration option to achieve early elimination of gangue and the low-grade component of ROM feed, thereby potentially:  Significantly upgrading the head grade of tin to the downstream processing plant.  Significantly reducing the required throughput capacity (and projected capital expenditure) of the downstream processing plant.  Reducing total consumables, power and water requirements in downstream processing.  Increasing the recovery of tin in the gravity and flotation circuit due to the higher feed grade achievable with ore sorting.  Reducing tailings tonnage, tailings cost and environmental footprint.  Using sorter rejects for mine backfill or road base applications. Key aspects of the design of the metallurgical testwork program centred around the need to ensure that samples representative of ROM ore feed (including projected mining dilution) were selected for the ore sorting testwork. The design and implementation of the ore sorting bulk testwork program is described, as well as a summary of the test work results and a discussion of the enhancement of the project economics reported by Kasbah, which led the company to adopt ore sorting as part of the proposed processing circuit in the updated 2018 DFS.

Nov 10, 2020

By D Brereton, C J. Moran

Intensive resource extraction, in the form of multiple mining operations, presents significant assessment and management challenges for resource developers, governments, community and the environment. Cumulative impacts, ie the successive, incremental and combined impacts (both positive and negative) of an activity on society, the economy and the environment, can place significant pressure on social, economic and environmental capital and render conventional mine-by-mine approaches to management ineffective. Cumulative impacts can be what are most important to environments, communities and economies surrounded by multiple mining operations because cumulative impacts are what they experience. There is much to gain from increased consideration of cumulative impacts. Unmitigated impacts have the potential to delay or even prevent expansion of mining in existing and prospective areas. On the other hand proactive management of cumulative impacts can benefit regional environments and communities and contribute to the industryÆs social license to operate. Resources are often not the limiting factor to better cumulative impact management. More effective coordination of existing resources may go a long way toward mitigation and enhancement, and better planning and assessment may help avoid impacts and exploit opportunities for efficiency gains through reduced duplication. In this paper we draw from working examples to present five practical assessment and management strategies applicable to resource companies to enhance positive, and avoid and mitigate negative, cumulative impacts. The strategies are presented based on their capacity for achieving outcomes, ease of implementation and cost effectiveness and are drawn from a multi-year study on the assessment and management of cumulative impacts in the Hunter Valley, New South Wales and a follow-up study to improve cumulative impact assessment and management practice in the Australian coal mining industry, both reported elsewhere.  

Jan 1, 2009

By J Jones, J Blunt

"The requirement for environmental approvals and associated environmental impact assessments (EIAs) is now commonly regarded as a key milestone and body of work during project development. EIAs can be undertaken at various phases during project development, generally either:\ during the scoping or prefeasibility studies, where limited project information is available and the mitigation and management measures of the EIA become a set of criteria and commitments that control project design during the feasibility study, as an iterative approach whereby mitigation and management measures are developed through an integrated process with the engineering team, and measures are included in the feasibility study cost model following the feasibility study, where detailed project design information is available, the cost model is complete, and the EIA is an assessment of a fixed project with limited opportunities for mitigation and management measures to be integrated into engineering design. This paper investigates the advantages of integrating EIA into life-of-mine planning during the feasibility study phase, using the Tampakan Copper-Gold Project (the Project) as a case study. The Tampakan Project is located in the Philippines on the southern island of Mindanao. The Project involves the proposed development of three main areas of infrastructure:a large-scale, open pit copper-gold mine and associated mine site infrastructure (including tailings and mine waste storages, fresh water dam, concentrator, etc) a power station, port and filter plant (PPFP), located approximately 60 km from the mine a pipeline and transmission line linking the mine and PPFP sites.Examples of engineering measures developed through an iterative process to mitigate and manage predicted environmental and social impacts include design of water management infrastructure, modification of the disturbance footprint (eg roads realigned to avoid critical habitat) and realignment of project infrastructure to minimise impacted water catchments.CITATION:Blunt, J and Jones, J, 2012. Integrating environmental impact assessment into life-of-mine planning, in Proceedings Life-of-Mine 2012 , pp 143-152 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 10, 2012

By B A. Webler, P Su, P C. Pistorius

Advanced high-strength steels (AHSS) typically have much higher aluminium concentrations (by an order of magnitude or more) than conventional low-carbon aluminium-killed steels. The resulting lower oxygen activity at the steel-slag interface changes the kinetics and thermodynamics of steelslag reactions. Previous work showed that the rapid transformation of alumina inclusions to spinel inclusions, and spinel to periclase, occurs because of the relatively high concentration of dissolved magnesium. In this paper, experimental results on nitrogen removal by ladle slag are compared with predictions based on the available thermodynamic databases. As in previous work, the kinetics was modelled by assuming mass transfer control, with steel or slag mass transfer limiting. The results show that significant removal of nitrogen by steel-slag reaction is possible.

Aug 21, 2024

Forty years ago Dr Pierre M Gy, a metallurgist, introduced variography as applied to monitoring a process. Consequently, his followers used the variogram to elaborate meaningful process control charts, especially since 1993. The name æChronostatisticsÆ was suggested several times by Gy as a logical name for this new science. The intent was to draw a parallel between the variogram identifying the variability components affecting a process parameter as a function of time, and the variogram used in geostatistics identifying the variability components of a given mineral content as a function of space. Heterogeneity problems encountered have indeed strong similarities. However, there is a fundamental difference. The variogram used in geostatistics is often stationary within a given type of mineralisation. While investigating a dynamic process through Chronostatistics, there is no such thing as a stationary variogram. Still, the evolving variogram provides essential information about subtle, often overlooked process difficulties. Chronostatistics is especially useful for management to take advantage of existing data that are often a forgotten source of valuable information to pinpoint recurring structural problems. The superiority of Chronostatistics over conventional statistical process control approaches is that it links observations to the inherent heterogeneity of materials under investigation, therefore to the sampling theory. Chronostatistics is like opening a new world to the metallurgist, making the process variability speak in a more comprehensive and in-depth way. Several case studies are presented to demonstrate the potency of this new science. For each of them, observations lead to solutions for continuous process improvement, therefore attractive economic opportunities. The philosophy is this: if a control chart shows a process is out of control, it must also suggest logical and pragmatic directions for solutions. The intent of this presentation is to vastly expand on these valuable, almost forgotten ideas.

Jan 1, 2006

By Lyman GJ, Davis JJ

Models which have been presented in the literature consider only selected aspects of dense medium cyclone operation, are empirical in nature and generally relate only to severely limited ranges of operating parameters. This paper reports progress towards development of a more comprehensive and robust model. The data base consists of partitioning parameters developed using density tracers and conventional coal sampling and analysis techniques, together with recordings of parameters such as cyclone dimensions, feed pressure, medium size distribution and product media densities.. These data were drawn from 15 Australian coal preparation plants. To elucidate the effects of important operating parameters on medium behaviour and on the partitioning of large particles a series of pilot scale tests was also conducted. The present model consists of eight sub-models which relate to particular aspects of dense medium cyclone operation such as medium flowrates and densities, or size- by-size separation densities and Eps. The model structure follows a logical progression which clearly demonstrates the importance of understanding medium behaviour before attempting to predict partitioning performance. The model also attempts to define the conditions under which yield losses due to unstable "surging" discharge may occur.

Jan 1, 1987

By M de Freitas Silva

One of the main steps during the decision-making process of long-term mine planning is the definition of the optimal sequence of extraction, which usually is synonymous with maximising the discounted cash flow of the project subjected to several constraints arising from aspects of technical, physical, and economic limits.Open pit mine production scheduling (OPMPS) comprises several intricacies related to its size and uncertainty of input parameters. Due to its complexity and prohibitive size, traditional mine planning usually relies on heuristic or metaheuristic methodologies which are able to provide good solutions in a reasonable amount of time. However, most of the uncertainty that surrounds the mining complex is ignored leading to non-realistic results.In this paper, a new heuristic approach is explored in order to solve a stochastic version of the OPMPS problem accounting for geological uncertainty in terms of metal content, multiple processing streams, and stockpiling option. The methodology involves generating an initial solution by solving a series of subproblems and this initial solution is improved using a network flow based algorithm.The algorithm was applied to a relatively large gold deposit with more than 119 thousands blocks. Results have shown that the methodology is promising to deal with large-size mine instances in reasonable time.CITATION:de Freitas Silva, M, 2014. Solving a large stochastic integer programming model for production scheduling at a gold mine with multiple processing streams and uncertain geology, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 389–396 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014