Search Documents

By S Wan, F Zhang, J You, K Tang, X Tang, C Bessada, A Canizarès, Q Zhang, L Lu

Microstructure of CaO-SiO2-based glassy samples with various Al2O3 contents were examined quantitatively by Raman spectroscopy and 27Al MAS NMR (magic-angle spinning nuclear magnetic resonance). Sequence of multiple cluster models of aluminosilicate system modified with Ca2+ and Na+ cations have been designed, and Raman spectra simulation were carried out after geometric optimisation by quantum chemistry (QC) ab initio calculation. The functional relationship between Raman scattering cross-section (RSCS) and stress index of silicon-oxygen tetrahedron (SIT) for aluminosilicates was established, which was applied to the calibration of experimental Raman spectra. Some five-fold coordinated aluminium (AlV, around 5 per cent) and less than 2 per cent sixfold coordinated aluminium (AlVI) were detected by 27Al MAS NMR, while most of aluminium remained in tetrahedral sites (AlIV). The hyperfine quantitative results of Raman spectroscopy and NMR showed a gradually production of AlIV with addition of Al2O3, along with the significant adjustment of Qi species distribution, in which Q1, Q2 reduced and fully polymerised Q4 increased while Q3 showed a non-monotonic variation and obtained the maximum at Al2O3 = 18 mol per cent. Furthermore, the effects of aluminium to bridging oxygen bond types (T-Ob, T = Si, Al) and the degree of polymerisation were also discussed in detail. The evolution of microstructure and its correlation with the viscosity of CaO-SiO2 based melts, incorporating various Al2O3 additives, have been investigated by employing in situ high temperature Raman spectroscopy at 1823 K and viscosity model. These structural features related to composition are essential theoretic foundation to understand their properties. The average Qi evolution culminates in an overall enhancement of the degree of polymerisation. Viscosity was determined utilising a rigorously selected viscosity model, elucidating a consistent upward trajectory as Al2O3 content is incrementally added. Furthermore, a quantitative analysis of the relationship between viscosity and structure was conducted based on the average number of non-bridging oxygen per network-forming tetrahedron (NBO/T). It provides valuable insights for examining and predicting viscosity behaviour of aluminosilicate systems.

Aug 21, 2024

By B Cook, M Karakus, J Light, E K. Chanda

The aim of this research is to develop a model through which the appropriate paste recipe parameters, for example solid content and cement content, can be derived given the stope specific requirements such as stope dimensions, required strength and curing time. A large number of samples and uniaxial compressive strength (UCS) tests were conducted at the Angas Zinc Mine (AZM) paste plant and testing facility. Samples were varied in tailings solids content, cement content and sand content. The results of this testing were modelled to determine the UCS relationship to each of the parameters. The output of this modelling was an easy-to-use program that outputs the design mixture given the stope dimensions and required stope backfill-curing time. This allowed flexibility within the mining schedule for curing times of cemented paste backfill stopes. The optimised schedule using the stope specific mix design, when compared to the standard 14-day curing time used previously, resulted in a smoother weekly mine production schedule. For the modelled 12-week period (one quarter) the 14-day curing time would result in an eight-day shutdown of the mill. The cost for each shutdown is in the order of $125 000/d. Due to the unique nature of each mine’s tailings, this exact outcome would not be directly applicable to another paste fill site. However, the process in this report could be followed for another site to achieve a system similar to the output of this project. This would ultimately lead to a more optimised backfill and stoping cycle and a more optimised mine.CITATION:Chanda, E K, Karakus, M, Light, J, Cook, B and Harris, A, 2014. Optimisation of the paste fill cycle at Angas Zinc Mine, Strathalbyn, South Australia, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 259–264 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By A D. Caccioppoli

Grade control systems within Rio Tinto Iron Ore have proven to be robust, when mining full benches. The Hope Downs 1 operation hosting two Marra Mamba Iron Formation deposits (North and South Deposits) presents a new challenge, where increased mining selectivity due to moderately plunging N-verging folds has made flitch mining necessary in the South Deposit. Poor flitch blasthole sample duplicate results in South Deposit over a 12 month period, compared to North Deposit, have highlighted concerns with grade predictions. In contrast a new grade control methodology (grade splitting) was proposed to alleviate blasthole sampling bias, utilising geological mapping and mineralogical logging, currently practised throughout Rio Tinto Iron Ore Pilbara operations, to estimate theoretical grades for each flitch from a single blast cone assay. To assess this method, reverse circulation holes (RC) were twinned to blastholes establishing an ‘actual’ grade. These blastholes were assayed using current flitch sampling techniques where: flitch positions were estimated, flitch positions were marked with paint, and a full cone sample was taken for ‘grade splitting’. Using these data sets multiple grade predictions were produced, then analysed using Half Absolute Relative Difference (HARD) statistical analysis. In addition to testing these grade control methodologies two other findings were ascertained: an inherent bias in blasthole assays exists particularly in the top flitch, where an average absolute difference of 0.6 per cent in SiO2 and 0.42 per cent Al2O3 was measured; and assays derived where kaolin rich soft shales are intersected were less representative. This is likely to be due to these materials not being properly represented in blast cones. Grade splitting accurately estimated block chemistry, except for a slight under-prediction in Al2O3 and P compared to current grade control methodologies. This method is a viable alternative where grade distribution is stratigraphically controlled.

Aug 22, 2011

By M Sandy, P Bamford

The Challenger Gold deposit was discovered in 1995 by Dominion Mining Ltd in a remote western area of the Gawler Craton in South Australia. Mine development commenced in 2002 with initial production from an open pit supplemented by ore from a very small adjacent auxiliary pit. Development of the underground mine commenced in 2004. The orebody plunge of just less than 30 degrees requires careful attention to mine design. Production from the M1 orebody, with less than 800 ounces per vertical metre (ovm) and very limited æsurgeÆ capacity, requires careful scheduling and implementation to ensure continuity of ore feed for milling. Initial production results from underground stopes included more dilution than anticipated. The narrow, high-grade zones proved to have much more complex geometry than early interpretations had indicated. Greatly improved understanding of the mineralisation controls resulted in important changes being made to the underground mine design and method. Coupled with careful control of development and drilling and blasting practices, this resulted in an immediate reduction in dilution and high recoveries of the resource. The benefits of these changes flowed through in the 2005/06 financial year, resulting in a 150 per cent increase in gold production to 108 080 oz and a sharp reduction in cash operating costs to A$280/oz. This was followed in 2006/07 with production of 108 91 oz of gold at an operating cost of $309/oz and in 2007/08 with 109 326 oz of gold at $367/oz. Production to June 2008 has been mainly from the M1 orebody, with the lowest stoping to date on the 580 m Level (615 m below surface) above development mining on the 520 Level. The rate of vertical advance of mining this orebody has averaged 150 vertical metres per year. The increased current combined JORC compliant resource and reserve position of over one million ounces, now includes the M2 and M3 orebodies with a current total average gold inventory up to 1400 - 1500 ovm. Exploration has intersected other shoots and all shoots are open at depth. The adjacent M2 and M3 orebodies are being developed for stoping. The narrow width of these zones from 1 m up to 4 m will require continued focus on ore zone definition, accurate development and careful drill and blast practice. In addition, to minimise cost increases in the current period of rapidly escalating labour, equipment, consumables and energy costs, high productivities will need to be maintained to allow the established rapid mining advance to continue at low unit costs.

Jan 1, 2008

Morning Star Gold aims to enter the ranks of Australia's gold producers, revitalising the Eastern Victorian Goldfi elds in the second half of 2010 - the fi rst gold production in around 50 years from the Morning Star Gold mine, which was once Australia's largest under WMC. This presentation will outline the redevelopment of the Morning Star Gold Mine from exploration to production. Morning Star Gold NL's (MCO) key project area is centred at the historic mining town of Woods Point and nearby Matlock (to the southeast) and Gaffney's Creek (to the northwest), all of which are located in the lower part of the Victorian Alps roughly 60 kms south of Mansfield. Morning Star has literally numerous historic mines and gold bearing 'dykes' on its tenements, many with a rich production history of high-grade gold from quartz reefs and alluvial sources. The area encompassing the Woods Point goldfi eld and the multiple high-grade gold bearing dyke structures located north towards Jamieson and south towards Walhalla formed one of the most significant mining fields in Australian history. Historical gold production was at least 155 t or around six million ounces of over a century of mining with an average production grade exceeding 27 g per tonne. The bulk of this recorded production came from just a handful of mines and of those only three were mined to any great depth. One of the key historical production hubs in this area was the famous 'Morning Star' mine, which is situated adjacent to Woods Point township. The Morning Star mine produced almost one million ounces at 27 grams per tonne, operating fairly continuously between 1861 and 1959 with a break after Jan 1939 due to the devastating 'Black Friday' bush fi res across eastern Victoria. During the early 1940s, the Morning Star was Australia's biggest gold mine. The Morning Star mine along with Walhalla ensured that this goldfield was third behind Bendigo and Ballarat as Victoria's biggest hardrock gold production centre. Morning Star Gold has rebuilt its 100 per cent owned 'Morning Star' mine with a view to producing gold in the second half of 2010. Morning Star is exploring its regional dykes in order to estimate an overall gold endowment and rank local production sources to feed its proposed mill at the Morning Star mine site. Key initial targets (all within 11 kms of the Morning Star mine) are the Waverly, All Nations, Rose of Denmark, Hunts, Wallaby and Loch Fyne dykes, all of which historically produced high grade gold, much of it gained from only shallow workings above the water table in the weathered zone of rocks. Historically the Morning Star mine was developed over 24 levels to a depth of 940 m via one large vertical shaft and a smaller, deeper inclined shaft at the 1900 feet level underground. At present MCO has dewatered and completely refurbished all infrastructure to the ten level (~310 m below surface). MCO knows there are a number of substantially under-explored and undeveloped or partially developed but not stoped areas within the Morning Star mine. As a result, MCO has been carrying out extensive channel sampling and an underground diamond drilling program targeting areas of the mine that were largely unexplored and undeveloped by the last operators of the mine - Western Mining Corp Ltd (Gold Mines of Australia). Four thousand, fi ve hundred pages of archival WMC records have helped the cause significantly. The shaft refurbishment and reconstruction stage is complete. This has been a program that originally commenced back in 1993 and has cost around $22 M. This refurbishment paved the way for the extensive underground resource focused diamond drilling program, which MCO completed in 2008 with two company-owned and operated drill rigs from drill cuddies on level 9 (900 feet underground) of the mine. This drilling, which encountered some stunning grades intersections and multiple visible gold hits, has outlined further production opportunities including 0.4 m @ 1392 g/t Au (MS 410). Metallurgical testing conducted by Gekko Systems of samples obtained from the exploration program found gravity concentration and a leach circuit gave recoveries of ~95 per cent to 99 per cent, or ~92 per cent from gravity alone at a coarse crush (300 ¦m). Currently, the plan is to use gravity to fi rstly produce dore bars on-site from the free milling gold and secondly a saleable concentrate for CIL processing off-site. A purpose built 10 t/h (~80 000 t/a) gravity treatment plant was subsequently ordered from Gekko and is expected to be installed onsite and commissioned in the Q3 2010. The plant features fi ne crushing with a vertical shaft impactor, followed by gold concentration by inline pressure jig, inline spinner and Wilfley table. This is an ABSTRACT ONLY. No paper was prepared for this presentation.

Aug 1, 2010

By T Ireland

The Project Hobson tunnel excavation was the first use in New Zealand of an earth pressure balance (EPB) tunnel boring machine (TBM). The tunnelling on the project was very successful and break-through was achieved three weeks ahead of program, demonstrating that tunnelling can be undertaken in Auckland with a high degree of cost certainty.Project Hobson involved the replacement of an existing 90 year old above ground sewer that crosses Hobson Bay in Auckland, New Zealand, and which had reached the end of its economic life, with a 3 km long, 3.7 m internal diameter segmentally lined bored tunnel. The NZD$ 118 M project has provided several environmental benefi ts to the Owner, Watercare Services Ltd and the local community:· provide capacity to meet projected growth in the region,· virtually eliminate wastewater overflows into Hobson Bay and the Waitemata Harbour, and· remove an obtrusive visual feature and open up the bay for recreational purposes.Auckland’s bedrock is a weak sandstone/siltstone (East Coast Bays Formation), subject to infilled paleovalleys. The geology in the region has been significantly influenced by volcanic activity; 49 volcanoes are present within 20 km of the city centre.The paper describes the design and construction challenges for the projects, including TBM performance, ‘sticky spoil’ management, and risks associated with basalt lava flows and two paleovalleys. The paper also highlights the reasons for the success of the project, including a rigorous approach to risk management during design, and effective planning during construction. Other useful data such as the effect on the watertable caused by closed face tunnelling, and ‘faceloss’ estimates derived from settlement arrays are included in the paper.Project Hobson also saw the successful implementation of a Geotechnical Baseline Report – one of the first uses of this type of document in Australasia.

Mar 8, 2011

By E Corpuz, J Weissman, S Winter, R Evans

The surface-to-inseam (SIS) directional drilling technique has been utilised at Oaky Creek Coal for more than a decade to predrain both the Oaky No 1 and Oaky North mining areas. The cumulative drilling program constitutes a total of 140 lateral and 200 vertical holes, and 405 km of lateral drilling.The use of SIS gas drainage has been successful with the following site-specific benefits being recognised:ability to drain German Creek seam gas contents to residual gas levels of new mining areas within an 18-month period from commencement of well productionstructural geological verification of the mine design well in advance of development mining occurring in an areaability to conduct successful predrainage of the overlying Aquila seam to reduce subsequent goaf emissions.Appropriate and up-to-date geological knowledge during the design and drilling process is a significant influence to achieving success. Vertical production wells need to be located in a position that is most effective to remove water from hole. The lateral hole should not include intersections with significant geological structure.SIS drilling provides continuous seam roof/floor data to help define seam geometry and locate geological hazards with high accuracy. In faulted ground and with variable seam gradients, SIS data can resolve geological ambiguities from seismic sections and enhance seam correlation that would otherwise be available only from discrete and closely-spaced infill vertical exploration drilling.Here, we review some examples of SIS configurations and practice to highlight key learnings in drilling long inseam holes (up to 1900 m per arm) ahead of development and mining. Aspects on prerequisites, evolution of network design, tolerances and drainage outcomes in a variety of geological situations are discussed as technical basis towards a viable and effective SIS drilling program.CITATION:Corpuz, E, Evans, R, Weissman, J and Winter, S, 2015. Surface-to-inseam (SIS) drilling at Oaky Creek coal mine – SIS design aspects and drilling environment, in Proceedings The Australian Mine Ventilation Conference, pp 93–104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By G Harbort

The use of geological data for optimisation of operating plants has become a significant part of the modern process mindset. The underlying principle is to convert spatial geological data into metallurgical information to drive production and mine planning, blast design, blending strategies and plant set-up. Increasingly the process designer is required to interface with geological and mining staff to propose the best investment strategy for a project’s benefit.The geometallurgical model development for the Zafranal copper-gold project commenced in March, 2010, several months after the start of a major drilling campaign by AQM Copper Inc. The initial evaluation stage required review of historical Teck RC data to determine areas of metallurgical interest within the project. As drilling transitioned from RC to diamond drilling, core that was considered representative of the resource was selected and subjected to MLA mineralogy analysis. When coupled with sequential copper analyses this allowed calibration of an assay derived mineralogy model, allowing process concept options and a preliminary test program to be developed. This Phase 1 test program provided a preliminary process design, operating costs and anticipated concentrate grades and recoveries. Both this data and resource estimation were used to generate a preliminary Whittle pit optimisation based on maximising net smelter return, which in turn fed into a preliminary mine plan. The preliminary mine plan, in conjunction with geological logs and core results was used to develop a phase 2 metallurgical test program, where variability tests were conducted throughout the resource and composites formed to investigate specific years of the mine plan in locked cycle flotation. In addition comminution tests were modelled against geometallurgical domains allowing comminution components values to be calculated for 36?000 m of core. A flotation geometallurgical model was developed and incorporated into the resource model allowing concentrate grades and recoveries to be estimated on a block-by-block basis.

Sep 5, 2011

By D M. Brady

Underground coal mines in Australia have embraced the use of various inertisation techniques both proactively and reactively. The use of such techniques can have a significant influence on ratios and trends used to monitor the status of the underground environment. Whilst control strategies should never be ignored in favour of preserving the integrity of ratios, the influence and significance of the changes likely to be seen should be anticipated and understood for reliable interpretation of the situation. This paper looks at the influence inertisation techniques can have on results and subsequent interpretation.CITATION:Brady, D M, 2013. The influence of inertisation techniques on gas interpretation, in Proceedings The Australian Mine Ventilation Conference , pp 259-264 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By D J. Williams

The majority of surface tailings storage facilities continue to employ sub-aerial tailings slurry deposition. Surface TSFs are typically sized and operated in a way to minimise the initial capital cost of the facility, driven largely by the net present value approach to accounting. This generally leads to too small a storage, too fast a rate of rise of the tailings, and difficulties in managing supernatant water. In turn, this results in wet and soft tailings deposits of high moisture content and low density, and the need for frequent and costly tailings dam raises. Further, such tailings deposits often do not facilitate closure and rehabilitation of the facility. Globally, there are on average over two failures annually of such tailings dams, resulting in loss of life, damage to infrastructure and environmental impact downstream, and the loss of company shareholder value and reputation. Recent high profile tailings dam failures are threatening the mining industry’s financial and social licence to operate.Among the physical processes that tailings undergo on sub-aerial deposition are beaching, hydraulic sorting down the beach according to particle size and specific gravity, settling, consolidation, and desiccation on exposure to the sun and wind. Beaching and hydraulic sorting have proved difficult to test at laboratory scale and difficult to model, and are best assessed in the field. Settling, consolidation and desiccation may be assessed at laboratory scale, but to date there has been an absence of tests to form the basis for the design and management of tailings deposition, and ultimate closure and rehabilitation. The paper describes recent advances in tailings testing methods, including a purpose-built slurry consolidometer that tests the settling and consolidation of tailings from a slurry consistency, simulating increasing tailings depth to about 50 m; and a purpose-built instrumented column that tests the settling, self-weight consolidation and desiccation of a surface layer of tailings, also from a slurry consistency. Selected test results from these two apparatus are presented in the paper, together with brief descriptions of how they may be used to better design tailings slurry deposition. In addition, planned further advances in tailings testing methods are briefly described.CITATION:Williams, D J, 2018. Recent advances in tailings testing methods, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 8–37 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By A Vickerfält, J Huss, J Martinsson

The European Union has listed vanadium (V) as one of the critical raw materials for the transition to a future green society, as stated in the Critical Raw Material Act, written by Grohol and Veeh (2023). In the steelmaking industry based on V-containing iron ore, V is a possible by-product from the slag. A requirement for slags to be suitable for V extraction is a V content preferably above 8 wt per cent as V2O3 and a phosphorus (P) content below 0.1 wt per cent as P2O5. Hence, it is important to keep V in the slag phase while the P is moved to the metal phase during the steelmaking process.

Aug 21, 2024

No paper available.

Jan 1, 1996

By K H. Esbensen

Optimisation of a real-time at-line monitoring system for control of industrial granule coating quality is presented. The system is based on a fluorescence imaging system, because fluorescence originates in the interiors of enzyme granules but is significantly quenched by a polymer coating (which is needed due to environmental precautions). We have developed an image analytical system for direct prediction of coating quality, which is based on application of the Angle Measure Technique (AMT) for image complexity characterisation; AMT is briefly described. The first part of the presentation addresses pixel sampling strategies within a digital industrial image, inherent in application of AMT, in which the unfolded image is regarded as a one-dimensional object in analogy with 1D process sampling in Theory of Sampling (TOS). The effects of random, stratified and systematic pixel selections in the unfolded image are evaluated. Also factors such as the fraction of image pixels and the effects of specific unfolding strategies (there are three principal strategies, termed æchopÆ, æsnakeÆ and æspiralÆ respectively) are investigated. It turns out that unsuspected artifacts are sometimes produced, related to the specifics of the unfolding procedure, which interferes with a straightforward 1D TOS process sampling analogy. These artifacts have a wider interest û among others, for 2D sampling û and therefore receive special attention in this presentation. The optimal pixel selection strategy for the AMT algorithm is found to be systematic or stratified sampling (not surprising according to TOS) of 500+ initiating points, but need to be unfolded in the novel spiral- or snake-wise fashions in order to effectively counteract these artifacts. This also has a general impact on various suggested standard schemes for 2D grid-sampling, among others, from the geoscience realms. The second part of the presentation is directed towards optimal image analytical sampling of a continuous series of fluorescent images (imaging of conveyor belts of æinfinite lengthÆ), ie optimisation of process image sampling. The minimum number of images needed to uphold a sufficiently good on-line estimate of the quality control (QC) parameter in question is found to correspond to the relatively high sampling rate of 15 - 20 per cent, which can be shown to be related to an intrinsic very high measurement error level (25 per cent) of a mandated analytical reference method.

Jan 1, 2005

By Bell I. F

In 1985, ZC Mines (now Pasminco South) had been unprofitable for some years due to a combination of high operating costs, low metal prices, low head grade and an aging and inadequate mining infrastructure. However, the resource of metal in the ground was still of world class, even after some 80 years of mining. A major study, which was to be of two years duration, was therefore commenced to establish a practical and profitable long term mining strategy and to cost the infrastructure options needed for its support and thus form the justification for a capital expenditure program to take the mine profitably into the 21st century and its second century of operation. This paper discusses the rationale behind the methodology adopted and the nature of the results achieved in one aspect of the study - the determination of the mineable resource and the relationship between the head grade/quantity of the economically mineable resource and the variables of cut-off grade, cost structure, annual production rate and metal prices/exchange rates. The basis of the study was the designing of some 5000 scopes to mine out the entire resource for a range of cut- off grades and the assembly of the detailed physical data thus obtained in a stope-by-stope data base for financial and other analysis. Those scopes which were shown to be economically mineable were then scheduled for two optimum annual production/cut-off grade/metal price combinations to provide life-of-mine cost and value of production cash flows.

Jan 1, 1992

By M Warnken

Major cities are not only the focal point for AustralianÆs work, leisure and homes, they also are the focal point for the flow of resources into the built environment, motor cars and transportation and urban consumables. The steady increases in æstockÆ and waste generation, in line with GDP growth, means that cities will become the mine sites of the future if the inherent value is recovered from these materials at end of life. The urban waste stream can be characterised as containing approximately nine per cent hydrocarbon-based materials; 57 per cent biomass-based material; 28 per cent fully mineralised materials that are inert, five per cent metals and less than one per cent of problematic materials that are potentially hazardous and toxic. In order to convert these wastes into value added inputs into the economy, a number of technological interventions are required. These æurban waste mining techniquesÆ revolve around source separation and material streaming. One issue that needs to be overcome when determining which mining technique to implement, is identifying the option that will deliver optimal value, both from a financial and a sustainability perspective. The difference between embodied energy and calorific value is a case in point. Highest net resource value (HNRV) is a concept that can assist in choosing between different resource recovery options. The assessment can be done at a strategic level, or can be used to work out material specific issues. For example, used tyres can be recovered for their energy content at an approximate cost of $120 per tonne, whereas mechanical processing of used tyres can deliver a net benefit of $192.

Jan 1, 2006

By G du Toit, P L. Gillot, M Swanepoel

Randgold Resources’ Loulo-Gounkoto Complex is one of the largest gold mining operations in Mali, West Africa. The mine, which is situated on the western border with Senegal, treats more than 4 Mt/a of ore through a conventional three-stage crushing and ball milling circuit followed by a carbon-in-leach plant. Ore supply is achieved by a combination of open pit and underground mining, with the majority of the ore supply sourced from the Gara and Yalea underground mines situated approximately 2 km and 6 km respectively from the gold plant.In 2011, Randgold Resources commissioned Golder Associates to perform an evaluation study for providing structural backfill to both the Gara and Yalea underground mines using the current gold plant tailings. The test work performed as part of the evaluation study concluded the need for a tailings cycloning and dewatering facility capable of producing slurry at a solids concentration of 65 per cent with a particle size distribution that had minimum 25 per cent passing 20 µm and less than 5 per cent of -5 µm material. Tailings desliming was required to ensure a consistent feed quality to the paste preparation plants and to ensure that the system would be capable of handling variation in the feed composition from the gold plant.WorleyParsons, previously TWP Projects, was contracted by Randgold Resources to complete the engineering design for the slurry preparation plant, whilst Golder Associates was retained to complete the engineering design of the two paste preparation plants.This paper discusses the test work, design considerations and engineering design of the slurry preparation plant, termed the ‘intermediate plant’, as well as all ancillary facilities required for the delivery of the deslimed slurry to the paste preparation plants located at the two underground mines.CITATION:Swanepoel, M, du Toit, G and Gillot, P L, 2014. Case study – engineering design for a slurry preparation plant for a paste application in West Africa, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 477–486 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

For the mineral industry, sustainability seems to mean socially positive and ecologically neutral mineral extraction. Mines are financed and developed in response to demand for their products. The purpose of my paper is to indicate the potential dimension of demand. As part of an unrelated study which I undertook ten years ago, it became apparent that there is a persistent relationship within communities between infant mortality and mineral use; greater mineral use corresponds to a lower rate of infant mortality. This comes as no surprise; sufficient potable water, a reliable supply of food, hygienic waste disposal, hot water and refrigeration all improve the chances of survival of the more vulnerable members of any community. The predictable provision of these facilities requires the application of minerals. This relationship is supported by a table (Appendix 1) included in the UNICEF publication, æThe State of the WorldÆs Children 2001Æ. This table lists regional infant mortality rate (IMR) statistics from around the world, including a listing for æindustrialised countriesÆ. Such countries experience an IMR lower by an order of magnitude than any other region. æIndustrialisedÆ inevitably involves the use of metallic and energy minerals. The principal use of copper is in the generation and distribution of power; it is fundamental to any industrialisation. IMR is a valuable connection because it quantifies caring for the young, a vital strategic driver of human behaviour independent of time, place, fashion or economic circumstances. I have tabulated the population, IMR and the copper demand per head of population for countries containing over 99 per cent of the population of the world in the years 1950, 1960, 1970, 1980, 1989, and 1999. These countries have been consolidated into four groups, Very High, High, Medium and Low rates of infant mortality (UNICEF has used this terminology; the Low group includes all the æindustrialised countriesÆ). The purpose of this consolidation was to reduce the volume of work, to dampen out the impact of regional wars and business cycles, and to dampen out the variable quality of information. Based on the pattern of the copper demand, population and IMR over the last 50 years, I have projected the likely copper demand in 50 years time. A dominant feature of my tabulation is the increase per decade in copper use per head and a corresponding reduction of the IMR. The word æuseÆ is preferred to æconsumptionÆ because it is estimated that over 80 per cent of all the copper ever mined is still in circulation There are two major influences at work; one is the absolute increase in population (UN estimates for 2050 are updated periodically) and the second is the movement of countries into a higher pattern of use and lower IMR. For example the Medium group in 1989 had an infant mortality rate approximating that of the Low group in 1960. With the population of the Medium group (which includes Russia and China) forecast to reach 2.6 billion in 2050, the world copper demand in that year will be significantly greater than the present figure. Nevertheless it will not be as great relatively as the increase of over 300 per cent in the last 50 years.

Jan 1, 2002

By T BoBo, D La Rosa, P Cameron

Efficient pre-concentration using natural and induced deportment starts with effective blast design. Leveraging these characteristics using Size-Based Grade Engineering® techniques requires detailed understanding and measurement of the particle size distribution (PSD) of the Run of Mine (ROM) ore. In turn, blasts must be designed to optimise fragmentation for the pre-concentration method. To be successful, fragmentation outcomes must be predicted and measured as part of the blast design process to account for the response ranking of the rock mass. The upgrade achieved using Size-Based Grade Engineering® methodologies will rely on the proportion of feed that reports to the screen undersize, so particle size distribution of the feed stock is of paramount importance if the potential benefits are to be achieved and maintained. Measuring actual fragmentation in the ROM ore and comparing with predictions allows the modification of subsequent blast designs to optimise fragmentation for pre-concentration scenarios. Automating this process can deliver significant increases in productivity and mine site profits. This paper discusses the importance fragmentation plays in Size-Based Grade Engineering® and explores technologies and methodologies used to measure it, consistently ensuring the best outcomes.

Nov 10, 2020

By J Ta’ala, M Handyside

Mechanical sampling from conveyors has historically been a staple in the iron ore industry when information related to chemistry, sizing and moisture is required. In order to comply with ISO 3082:2009, samples can be taken either on a mass or time basis provided no bias is introduced by periodical variation in quality or quantity. With the introduction of mechanical sample carousels, you also have the opportunity to collect samples on a mass or time basis. In order to optimise automatic sample stations in a changing production environment, BHP Billiton Iron Ore (BHPBIO) has developed a simulation model that enables the various combinations of mass–mass, mass–time, time–time and time–mass to be investigated.The sample station model can utilise actual (variable) feed rates to achieve high resolution and enables the simulation of sample size variation. Cutter speeds and other settings can then be adjusted to better optimise the performance of the sample station with regards to optimal sample size as well as ensuring the sample station is in compliance with ISO 3082. The model can also assist process engineers in adjusting settings to better optimise the sample station and reduce unwanted events such as blockages. The model can be easily modified to conform to various sample station designs. This paper demonstrates the use of the model and the benefits that can be achieved.CITATION:Handyside, M and Ta’ala, J, 2014. Simulating time versus mass basis?sampling, in Proceedings Sampling 2014 , pp 155–164 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By F Clark, J T. Carswell

Ore definition for final stope planning is often a challenging prospect in underground (UG) gold mines which exhibit high geological and grade variability. Unlike the grade control (GC) scenario in an open pit (OP), the ability for the mining geologist to plan a sampling campaign which effectively characterises the underlying mineralisation is fraught with difficulty. UG sampling patterns are strongly clustered and typically not dense enough to characterise the spatial and statistical properties. Very commonly, sample volumes are not large enough to provide a reliable grade estimate of the surrounding rock. These factors critically affect our ability to accurately map out ore positions and estimate metal quantities.At Sunrise Dam, traditional UG sampling and modelling techniques have proven to be an unreliable strategy for successful stope planning and extraction. The problem was first observed during the final cut-back in the open pit for which the mineral resource model was constructed from UG diamond drilling. Open Pit grade control reconciliations were strongly positive for both tonnage and grade compared to the resource model. Underground workings missed significant quantities of ore which was laterally defined by open pit reverse circulation (RC) GC drilling. Upon examination it was realised that the cause of the problem was one of inadequate sample density and sample support, the implications of which potentially affected the entire UG mine.As part of a broader study into underground grade control procedures, detailed reconciliation of initial stope production from the GQ domain also pointed to inadequate sampling as a major constraint to effective grade control and reserve conversion.To overcome this deficiency, dense 115 mm wet RC grade control drilling and conditional simulation modelling has been successfully implemented with the intent to replicate the grade control process in the open pit. The increase in sample density and sample volume has proven to be a very effective tool for mapping out highly complex mineralisation. A marked improvement in stope definition, reserve conversion and Mine to Mill reconciliations has been demonstrated on the back of an innovative approach to UG grade control.CITATION:Clark, F and Carswell, J T, 2014. Using reverse circulation drilling to improve sampling in a complex underground gold operation – an innovative approach to underground grade control at the Sunrise Dam Mine, Western Australia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 143–152 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014