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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 R Schmitt, Y Ghorbani, I McElroy, N J. Bolin, M Parian

Aitik is a large copper porphyry type deposit located in northern Sweden, currently exploited at an annual rate of approximately 45 Mt. The ore’s exceptionally low head grade of 0.25 per cent Cu and varying degrees of hardness across the entire deposit pose challenges to the two fully autogenous grinding lines, each of which comprises a primary autogenous mill in series with a pebble mill. The variability in ore grindability frequently leads to fluctuations in mill throughput. Within the framework of a geometallurgical approach, the present study investigated the relationships between ore grindability and modal mineralogy. For this purpose, drill core samples from different lithologies were subjected to Boliden AB’s in-house grindability tests. This fully autogenous laboratory-scale test generates a grindability index mainly related to abrasion breakage, which is a significant breakage mechanism within autogenous mills. The test results suggested divergent degrees of grindability within and across the selected rock types. A combination of scanning electron microscopy, X-ray powder diffraction, and X-ray fluorescence analyses was performed for the grinding products and bulk mineral samples. The resulting mineralogical and elemental properties were subsequently correlated to the parameters from the grindability tests. It was shown that the main mineral phases, such as plagioclase, quartz, and micas, correlate well with the grindability indices. Similar correlations were found regarding the sample’s chemical composition, attributable to the main mineral phases. A further inverse correlation was established between the sample’s calculated average Mohs hardness and the grindability indices. Moreover, mineral liberation information provided by scanning electron microscopy was associated with the parameters mentioned earlier. The identified relationships between grindability, modal mineralogy, and element grades may help Boliden develop a predictive throughput model for Aitik based on the mine’s block model.

Aug 24, 2022

By P Mulvey, M Stuckey

"Inter-aquifer leakage due to fractures caused by coal seam gas extractions or longwall mining is an important issue for both the gas and coal industries. Currently, predicting stress induced macro-porosity associated with hydraulic fracturing, depressurisation via dewatering or collapse of overlying seams to infill a void left by longwall mining, is problematic. If fractures can be located the fracture can be sealed. Locating fractures is difficult. The non-geophysical approaches to locate fractures has been to consider the mixing of different waters, particularly that of more recent shallower groundwater with older deeper groundwater, via differences in radio-isotopes integrated with geochemical models to predict likely mixing of waters. This approach is applicable under appropriately complex settings; however, it is an expensive technique and is based on the assumption that the daughter isotopes are equally non-reactive which may not always be the case.Potentially a cheaper and faster technique is to consider integrating geochemistry (mineral weathering) and hydrogeology. The chemistry of groundwater, controlled by the weathering of primary rock?minerals and?formation of secondary minerals, can not only be differentiated between geological strata but also within strata as different stages in weathering results in differing impacts on water quality (ie different reactants).Field analysis of pH, electrolytic conductivity (EC), oxidation reduction potential (ORP) and dissolved carbon dioxide together with laboratory analysis of dissolved constituents characterise the chemistry of the water. Collection of rock samples at the time of drilling for bore installation can provide the (only) opportunity to assess the media in which the groundwater resides and migrates through. An assessment of aquifer matrix chemical makeup, via bulk sample chemical analysis, X-ray diffraction (XRD) and petrographic analysis can achieve this.The chemistry of groundwater is dependent on the water velocity. Water at deposition and post-diagenesis dissolution of minerals by hydrolysis and oxidation will result in equilibria of the dissolved phase with the solid phase. Post-depositional fractures caused by either tectonic activity or weathering alter the rate of weathering and thereby the geochemistry. Slow water flow in microfractures results in water in equilibrium with the rock minerals. Faster flow in larger fractures results in water being in disequilibria with rock minerals.Fractures can alter groundwater chemistry by two pathways: changing groundwater velocity, which changes the rate of hydrolysis or oxidation mixing water from different geological strata.Both pathways cause subtle changes in the water chemistry.It is however, the dissolved phase chemical data, which can be observed over time at individual locations and/or at a point in time along a flow path, which allows the hydrogeologist to ælook up-gradientÆ and locate the zone of leakage. Hence, influences on rock/groundwater chemistry, from anthropogenic sources to natural mixing of waters, can be assessed via appropriate interpretation of geochemistry, hydrogeochemistry and flow data.This paper will use the example of the geochemical and hydrogeological characterisation of aquifers within the Hawkesbury and Bulgo Sandstone of the Southern Coalfields to the south of Sydney in New South Wales to demonstrate this approach.CITATION:Stuckey, M and Mulvey, P, 2013. Looking for fractures - integrating geochemistry with hydrogeology to find inter-aquifer leakage above dewatered or collapsed coal seams, in Proceedings Water in Mining 2013, pp 99-108 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 26, 2013

By E Macmillan

For any processing plant there will be deleterious elements or minerals which affect production or quality, and a strategy to predict their occurrence and mitigate their impact is required. An early objective of the Olympic Dam geometallurgy program was prediction of the acid consumption and gelling behaviour of the ore, which affects leach recovery, throughput and circuit availability. The geometallurgical test program measured the response of a wide range of ore types, and then relationships between mineralogy, metallurgy and chemistry were developed. Thus the drivers of acid consumption and triggers for gelling events could be described in ways that were meaningful to plant operations.To enable optimisation of the mine planning and ore blending processes, the parameters driving metallurgical response must be translated to the block model. Data support is critical in populating a block model. Assay information is easily obtained, but mineralogical and metallurgical information is more expensive and time consuming to collect. Hence population of a block model with mineralogical and metallurgical values using a conventional geostatistical approach is not always possible.An alternative approach employed at Olympic Dam was the development of a suite of assay-to-mineral algorithms. These algorithms were calibrated using all available mineralogical information, and this enabled the calculation of mineral abundances for more than 1.5 million assayed samples. Estimation of the minerals in the block model, and the generation of acid consumption values for each block could subsequently occur.The use of back-calculated mineralogy from assays as part of process model generation is an innovative tool which can be used for mine planning and optimisation and to ensure the plant does not receive any unwelcome surprises. Ultimately, one purpose of geometallurgy is to predict potential processing issues and their drivers so that these can be mitigated. A strategy to achieve this is outlined hereafter.

Sep 5, 2011

By T Sparks

The Collie River catchment, located approximately 200 km south of Perth, covers an area of around 2830 km2 and is the source of run-off to the Wellington Dam, an important irrigation water resource for the Collie Irrigation District. The salinity of the Wellington Dam has increased due to historical clearing and irrigators currently use water with salinity levels approximately twice that of the Murray River in South Australia (Water and Rivers Commission, 2001). The Collie River Salinity Situation Statement (2001), released by the Water and Rivers Commission (now the Department of Water), identified realistic actions that could achieve the salinity reduction target. Subsequent benefit-cost analyses and prefeasibility studies recommended the diversion of the most saline flows in the Collie River away from the dam as an immediate intervention (URS, 2003). The East Branch of the Collie River above the locality of Buckingham (20 km east of Collie) contributes around half of the salt that flows into the Wellington Dam and the diversion and storage of the saltiest flows from the East Branch at Buckingham was identified as a viable option for reducing salinity in Wellington Dam. The proposal had one problem û the water could not be disposed of as quickly as it was diverted. However, in the vicinity of the diversion site were a number of coal mine voids and after preliminary discussions, the Government/Griffin Coal alliance was formed and from this the opportunities have continued. Diverted water would be stored temporarily in an adjacent mine void (Chicken Creek 4 void) and then disposed of to the sea. The disposal options included Western Power CorporationÆs saline discharge pipeline from Collie Power Station, or a new pipeline. The diverted water was also identified as a potential raw source for treatment and use in industry. This has opened up opportunities including desalination, water efficiencies in the power stations, increased reliability of water supply for the power stations, water for new industries, wastewater disposal options and extra water for PerthÆs water supply. In the process of solving the water storage problems the project introduced a range of mine water quality problems û heavy metals and pH û and the Department of Water (DoW) is now working with the mining industry and the Centre for Sustainable Mine Lakes (CSML) to develop treatment and management technologies. The project has received support and funding through the National Action Plan for Salinity and Water Quality (NAP) and it has been possible to accelerate and enhance this project as a result of NAP. The DoW has developed the proposal to an advanced stage and gained approvals for the capital diversion program to go ahead. The partnerships have expanded to include the second mining company, Premier Coal, the Water Corporation, Western Power and the Harvey Irrigation Cooperative. The proposal could feasibly result in a $90 million integrated water management initiative for Collie using the latest technology, mining operations and providing water for value adding industries in the local area. The DoW is not a mining company; however, our experience in managing water in times of shortage, environmental water quality criteria, competition for water and managing community expectations will have the same success factors:consultation and knowing your community and stakeholders, sharing issues and working in partnership can provide results far greater than the initial issue, even brackish water has value, every sector is in competition with each other and has to have a share of the water, an integrated approach can provide opportunities for development in areas of water shortage, and never think of water as wastewater.

Jan 1, 2006

By J Shillabeer

Paste backfill has been adopted by many underground mines in North America and a growing number elsewhere. Paste offers a number of advantages. This paper suggests wider applications of paste technology to surface tailings disposal and water management. Advantages include improved overall stability, potentially easier permitting, smaller water inventory and earlier reclamation. It may be feasible to use the same plant to prepare backfill and to dispose of surplus tailings. Example cost models are given to illustrate potential applications.

Jan 1, 1998

By L R. Sousa, M He

Rock burst is common in deep underground excavations and is characterised by a violent ejection of block rocks from excavation walls. It is critical to understand the phenomenon of rock burst and particularly the failure mechanism. Laboratory experiments are one of the ways. For that purpose, a rock burst laboratory test system was developed at the State Key Laboratory for Geomechanics and Deep Underground Engineering at the China University of Mining and Technology, Beijing. A true triaxial test system, designated the Deep Underground Rock Burst Analogue Test Machine, was developed, which can transfer a stress state from three-direction-compression on six surfaces to the compression on five surfaces with one set free. The rock burst experimental system comprises an acquisition of acoustic emission signals, a high-speed recording in order to accurately record the kinetic characteristics of rock fragments ejected during a rock burst event and the possibility of infrared thermography showing the surface temperature of the samples. In this paper, analyses of typical results from rock burst tests are presented with a description of the obtained results. The mechanisms of rock burst are illustrated, and a rock burst classification is proposed based on these laboratory tests. For the control of rock burst, the constant resistance, large deformation (CRLD) bolt or anchor is presented for accommodating the large displacement of surrounding rock masses and absorbing the impact of the sudden release of rock burst while outputting a constant resistant force in response to the external load. The CRLD bolt or anchor has had practical applications in underground mines. Finally, in situ tests performed in a tunnel at Qingshui coalmine, China, are analysed in detail.CITATION:He, M and Sousa, L R, 2014. Experiments on rock burst and its control, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 19–32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By J T. Carswell, N A. Schofield

Fluctuations in periodic reconciliations between the mine and the mill are an expected and common experience in mining and processing operations. These fluctuations are caused in part by errors in the estimates of tonnage and grade of the mined material as well as errors in the millÆs assessment of the material processed. Keeping these errors small and unbiased is an important aspect of an efficient operation whose primary goal is to derive maximum benefit from the exploitation of the mineral resource.These fluctuations in periodic reconciliations can also mask subtle but economically important problems which may take years to identify and resolve. Such problems can result from a poorly-conceived model of the mineralisation which affects both the spatial distribution of the ore as well as the tonnage - grade distribution over the range of cut-off grades. Poorly conceived models of the mineral resources and ore distribution can arise as a result of insufficient and inadequate?drilling and sampling of the mineralisation, inappropriate?application of geological?constraints in the estimation process and the use of inappropriate methods to estimate the block grade distribution. This paper presents three case studies from gold and copper mining operations, two of which experienced significant problems with their mine to mill reconciliations over extended periods of time. For the gold mine in case study 1, sampling problems were ultimately considered to be the main cause of the poor reconciliations between grade control predictions and the mill which persisted over a period of 18 months. In addition, incorrect application of resource modelling methods contributed significantly to a mismatching of the mill capacity with the mine at the beginning of operations. For the underground copper mine in case study 2, a change in the approach taken to resource modelling brought marked improvements in ore definition and more accurate predictions of ore grade and better production forecasts.The third case study describes the background to the expansion of production to exploit a large tonnage of lower-grade stockwork mineralisation in an open pit gold mine. Several years of favourable Mine to Mill reconciliation data from the mining and processing of higher grade and lower grade stockwork styles of gold mineralisation provided the confidence in the approach to grade control to support the expansion plans during a period of low gold prices.The paper is intended to complement the discussion of mineral resource estimation methods and risks in Section 6.1.3 of the Mine ManagersÆ Handbook to be published by the Australasian Institute of Mining and Metallurgy (Schofield, 2012).CITATION:Schofield, N A, Moore, J and Carswell, J T, 2012. Mine to mill reconciliation - Three case studies, in Proceedings International Mine Management 2012, pp 161-172 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By P J. Terbrugge

The concept of vertical pit mining has been developed as an alternative mining method for the exploitation from surface of small, vertical or near-vertical, massive orebodies down to depths of some 200 m, where ore extraction from conventional open pit excavations is rendered uneconomic due to high associated waste:ore mining ratio. Systematic lateral support maintains vertical pit sides, thereby minimising waste mining volumes. Stability analysis techniques have been developed for design of this lateral support, with the support quantum, primarily comprising long cable anchors, dependent upon country rock strength characteristics and pit configuration. Where the cost of support is less than the cost of the comparable conventional pit waste excavation, vertical pit mining becomes an economically viable alternative, additionally providing the benefit of reduced environmental impact and rehabilitation requirements for the mining area. The technique has been successfully applied for the mining of a chrome deposit in Zimbabwe to an 80 m depth, believed to be unique in the world, and a full feasibilty study for a 3000 m2 diamond pipe has been carried out for mining to 200 m depth.

Jan 1, 2000

By M A. Rhamdhani, K Avarmaa, A Putera, J Chen, G Brooks

Silicon-based photovoltaic cells are currently the most dominant types applied to convert solar energy to electricity. In solar-grade silicon (SG-Si), the control of boron (B) and phosphorus (P) is very critical. Generally, these elements are difficult to remove into acceptable sub-ppm levels from lower grade Si. This study investigates slag treatment as a process for Si refining, focusing on the behaviour of P and B. The experiments were conducted by equilibrating Si-B-P alloys with 43 wt per cent SiO2 – 47 wt per cent CaO – 10 wt per cent Al2O3 slag under inert atmosphere at 1500°C. Different crucible materials were used (Al2O3, SiO2 and MgO), which determined the primary saturation phase for the system and modified the final slag composition accordingly. The samples were equilibrated and analysed with microanalysis techniques (EPMA (electron probe microanalysis) and LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry)). New standards were prepared and applied in the LA-ICP-MS analyses. Experimental results show that silver is essentially fully dissolved in silicon, as well as most phosphorus with LP ( = wt per cent P in slag/wt per cent P in Si) between 0.1–0.3. The distribution coefficient of boron was measured to be between 1 and 2. The crucible material used had an influence on the phase compositions and slight influence on the distribution coefficients of boron and phosphorus. The experimental results provided new accurate data when considering applicability of slag treatment as a technique for Si refining and Si PV cell recycling.

Jun 19, 2024

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

The Goonumbla district of central-west New South Wales, Australia, hosts four significant porphyry Cu-Au deposits that contain a combined probable ore reserve of 71.7 million tonnes at 1.2 per cent Cu and 0.5 g/t Au. Mineralisation in the Goonumbla deposits is associated with narrow, pipe-like intrusions of quartz monzonite porphyry, in which several intrusive phases have been recognised. Five textural characteristics have been used to distinguish the various intrusive phases recognised in the Goonumbla porphyry deposits: (1) phenocryst abundance; (2) nature of the groundmass; (3 and 4) proportion and mineralogy of the mafic and non-mafic phenocrysts; and (5) the presence or absence of anhedral quartz grains in the groundmass. In addition, each intrusive phase is classified according to its estimated original quartz, alkali feldspar and plagioclase contents. Features common to all of the intrusions are that they contain two types of plagioclase and two or three types of K-feldspar phenocrysts in variable proportions. Most of the intrusions also contain apatite micro-phenocrysts. The groundmass textures range from aphanitic through granular to euhedral K-feldspar in a quartz matrix. With only one exception, all of the intrusive phases recognised are either quartz monzonite porphyry or mafic (>5 per cent mafic minerals) quartz monzonite porphyry. The exception is a biotite - phyric monzodiorite, which occurs in the basal portions of one of the deposits. Textural variants of intrusive phases at Goonumbla have been investigated to establish whether specific combinations of characteristics indicate mineralised intrusions, while others suggest barren ones. Some correlations between intrusion types and Cu and Au grade have been recognised. The most important textural characteristic that relates to high grade mineralisation appears to be the low proportion of mafic minerals, because the quartz monzonite porphyry intrusions hosting most of the mineralisation in the two deposits studied contain

Jan 1, 1999

By B Belle, M Biffi

Cooling of coal mines in the Bowen Basin, characterised by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be required to focus their cooling resources more intensively to manage a challenging thermal environment where virgin coal temperatures of over 50¦C at a depth of 500 m are expected. Currently, mine cooling systems are employed to maintain the wet bulb temperatures (WBT) to below 27¦C at which point the risks of heat stroke or other heat-related issues are manageable. The capacities of these systems are in the range of 6 MWR to 10 MWR. The relationship between high working temperature environments and injury frequency rates is well established. Therefore, provision of appropriate cooling strategies and understanding their optimum performance and suitability are important to Australian coal mines of the future. This paper evaluates the underground temperature profiles of deep, gassy coal mines with propensity for spontaneous combustion and proposes the long-term cooling pathways to effectively manage thermal hazards. Thermodynamic modelling is performed on a longwall face and includes air leakage effects from goaf streams at various locations along the longwall face. The strategy summarises the application of underground bulk air cooling, chilled water sprays on the shearer and the resulting temperature profiles. Considering the new mining projects planned for the Bowen Basin region, a review of implementable cooling strategies such as mid-gate mobile bulk air coolers (BACs), spot coolers, underground bulk air cooling and the use of chilled water to enhance the positional efficiency of cooling plants, are discussed in this paper. Finally, the comparison of ærentalÆ versus æownershipÆ of cooling plants is analysed as part of long-term cooling strategies.CITATION:Belle, B and Biffi, M, 2013. Cooling pathways for deep Australian longwall coal mines of the future, in Proceedings The Australian Mine Ventilation Conference , pp 223-236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By F Clark, B Catto

The Mako domain comprises the Mako lodes at Sunrise Dam Gold Mine, Western Australia. This domain was initially bulk or æbucketÆ domained for the open pit resource in 2000, due to complexity in defining the lodes as a result of low drill density. Negative ore tonnage and positive grade and ounce reconciliations were experienced during mining of the domain in the mega-pit, though only small volumes of the domain were mined. Significant amounts of exploration and underground grade control drilling has been completed since the initial bulk domain interpretation and greater geological understanding of the mineralisation controls and geology of the lodes now exists. Mako provides approximately 50 per cent of the ore tonnes and ounces for the North Wall Cut-back, the latest open pit phase of mining at Sunrise Dam. The importance of Mako to mill supply and life-of-mine planning, as well as past reconciliation performance necessitated a reinterpretation of the domain to increase confidence for mining. Historic exploration drilling, underground grade control drilling and detailed pit-wall mapping were used to build mineralised subdomains within the confines of the original domain. These reflect more closely the spatial extents and geological controls on the mineralisation. A new resource model using the multiple indicator kriging (MIK) technique was generated using the new domains. It resulted in a decrease in tonnes and ounces but increase in grade for the sum total of the new domains compared to the old æbucketÆ domain. This is attributed to the increased selectivity and structural constraints imposed by the new domains. A retrospective comparison of the Mako grade control from the mega-pit versus the new resource model was conducted, which æreconciledÆ 103 per cent tonnes, 106 per cent grade and 110 per cent ounces. This has provided confidence that the new model is a better estimate of the lodes. Qualitatively, the new model is a better representation of the geology and extent of the mineralised structures with significant areas of change identifiable. Grade-tonnage plots comparing the 2006 and 2008 models show that most tonnes have been shed from the low-grade û subeconomic grade cut-offs. This is mostly attributable to the volume reduction of æoreÆ in the 2008 model compared to the 2006 model, where the true mineralised zones are captured by the new domains. The reinterpretation and remodelling of Mako is an example of an evolved domain model and shows that mineralised zones need to be differentiated adhering to the geology and geological controls on mineralisation, which are understood largely due to increased drilling density coupled with mapping.

Jan 1, 2009

By A Lines

This paper addresses a gap in longwall multi-seam interactions and their predictions, providing a case study for future multi-seam operations for both anticipated conditions and a method for understanding the changes in stress regime. Multiple panels were modelled with the results analysed and compared to panel experiences to validate the parameters and properties. The software chosen (LaModel) is a numerical modelling package designed to model stresses and displacements on thin deposits. It utilises a displacement-discontinuity variation of the boundary-element method and has been used extensively throughout both the United States and Australia in multi-seam operations. Analysis of the results demonstrates a clear correlation with the above workings and regions of significant strata instability. This provides the opportunity going forward to analyse new models and incorporate into mine planning and geotechnical designs. Continuous site-based assessment should be undertaken at multi-seam operations to better understand and quantify likely vertical stress levels within the workings. With a detailed analysis of models prior to extraction and a review of models post extraction. Further research is required as LaModel is limited to vertical stress and it is likely that interactions impact both the horizontal and shear stress regime. 3-dimensional modelling could further assist in this understanding, combined with a thorough stress monitoring regime. CITATION:Lines, A, 2018. Modelling multi-seam interactions for longwall mining, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 185–195 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

The nation of Fiji is located the South Pacific on the æRim of FireÆ some four hours flying time from the eastern sea board of Australia. It is a tourist destination situated on the main route from Australia to the Americas. Fiji is a developing country that has had a fewsetbacks but the country has able, happy people that are very resilient. Most importantly, the country is a safe destination for tourists and businesspeople as the local people are friendly, have good ethics, and most speak English. Fiji is a very willing nation, hungry for knowledge and advancement. The Fiji geological setting on the æRim of FireÆ, that runs from New Zealand across the Pacific through Fiji and on to Papua NewGuinea, has many large deposits of gold and copper. Fiji is an exciting destination for mineral explorers with discoveries of gold, silver, manganese, bauxite, iron and copper. Gold was first discovered in 1921 and the first two mines opened in 1935; one of which was Emperor Gold Mining Company (EGM) the other being Mt Kasi. EGM mines gold on the margin of the Tavua caldera, some 85 km north of the Nadi international airport. EGM has operated continuously for close to 70 years, producing approximately 6.9 million ounces of gold and has an underground reserve of 847 600 ounces with a total mineral resource of 12 335 600 tonnes at 10 g/t (as given in the Emperor Mines Limited Annual report 2003). The mineralisation in Fiji is very exciting and it is common to discover spectacular intersections and outcrops, which are typical for this type of epithermal narrow vein mineralisation, but be aware that the orebodies are variable and not easy to understand.

Jan 1, 2004

By D Morgan, D Sato, B Lumsden, S Senanayake

Laboratory flotation tests on fresh cyclone overflow samples are a useful tool to troubleshoot and indeed to improve plant performance; however, reproducibility between laboratory flotation test and plant performance is important for interpretation of the laboratory tests and hence their usefulness. Chemical reproducibility can be achieved with the addition of the required reagents; however, reproducing the physics of forces and energy in a 5 L cell compared to a 50 000 L plant cell or a 500 000 L plant cell is not generally studied or discussed. For some tests such as collector evaluation the physics of the flotation process may not be critical, but for some evaluations in the laboratory, it can be important.All flotation plants suffer from losses of valuable <20 µm mineral. Selective mineral aggregation has long been recommended to improve the poor flotation recovery of <20 µm sulfide minerals; however, successfully testing any type of selective sulfide mineral aggregation’s effect on flotation recovery in the laboratory on practical plant samples requires reproducing plant cell physics. The energy input per litre and the forces in a laboratory cell are vastly different to a plant cell. Reproducibility between laboratory and plant tests requires that these differences be minimised. The physics of the laboratory flotation cell is particularly important when fine mineral aggregation tests are carried out.This paper outlines a modified laboratory aggregation and flotation method that closely reproduces plant performance in a laboratory test.CITATION:Sato, D, Lumsden, B, Senanayake, S and Morgan, D, 2014. Development of a laboratory flotation method to test plant mineral aggregation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 173–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By D David

Amongst those whose task it is to design tumbling mills and other comminution machines there is an almost religious divide between devotees of the Bond method and devotees of other methods developed in more recent times. For a decade or so the issue was between the Bond power-based methods and the JKMRC (JK) simulation based approach. The newest method to challenge the status quo is power-based and was developed by Steve Morrell. As the title suggests, this paper will take some liberty at concluding that Fred Bond and Steve Morrell may be separated by history, but not by their approaches to their individual contributions to the science of comminution. Another driver for the paper is that although it is good to have diversity of thought, the existing divisions are problematic for those of us signing public disclosure documents. If alternative design methods produce materially different outcomes for the mill duty, then at least one of them is wrong or being used incorrectly. At some point the unsustainable argument may need to be put in a court of law that we metallurgists have two or more materially different design methods, each of which is correct! Therefore, perhaps a resolution is needed before this occurs?The works of both Fred Bond and Steve Morrell are each directly related to their contemporary grinding mill design and operational environments. Both their approaches are empirical, borne of observing and measuring real world situations. Both worked with theories that preceded them, gathered their own data and then each saw shortfalls in the status quo.Fred Bond was an escapee from revolution, a victim of The Great Depression, and had several near death experiences during his early site-based career. Perhaps he was fortuitously rescued from himself when asked by Allis Chalmers (A-C) to set up its rock testing laboratory in Milwaukie in 1930. Fred’s testing led him to conclude that neither the Kick nor the Von Rittinger theories explained his measurements. His writings on the failings of these old theories caused a divide between devotees of the old and new methods at that time. After many years, and much thought and plotting of data (the old way!), he came up with his now-famous equations (and his Third Theory) which have stood the test of time, certainly in the world of Bond-era machines.Coming from England via several African diamond mines, Steve Morrell immersed himself into the comminution world of the JK in Brisbane about a decade after Fred passed on. The JK had developed its semi-autogenous grinding (SAG) simulation framework using its own pendulum breakage tester, itself a derivative of the twin pendulum impact device invented by Bond decades earlier. At the JK Steve developed his authoritative Tumbling Mill Power equations and was involved in real world analysis of comminution problems on the global stage. Steve’s JK experience coincided with the demise of the rod mill, the rise of autogenous grinding (AG) and SAG milling and a rapid expansion in concentrator capacity.Morrell left the JK to pursue his own interests, which included ongoing consulting work, now demanded by the comminution world. He then turned to investigating a growing list of discrepancies between the opinions of designers and theoreticians, and the factual outcomes. The Morrell Method of design arose from this re-examination of ore testing, real world operating data and these glaring and expensive discrepancies between design and outcome. The elements necessary for a relook at the world of rock breakage were in place!CITATION:David, D, 2017. Steve and Fred would have been mates – a comminution design evolution story, in Proceedings MetPlant 2017, pp 2–11 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By Y Li, Z Fu, D J. Williams, E Topal

Mine waste rock is unavoidable in the recovery of ore by open pit mining methods. Effective management of waste rock movement covers the removal and placement of the waste rock, generally in a surface dump in the most cost-effective way while satisfying the long-term environmental expectations. Since the 1960s, there has been significant research carried out into planning of ore movement from open pit mines such that the overall net present value (NPV) of the project can be maximised. Currently, several software packages are available to achieve this task as a common practice within the mining industry. However, planning of mine waste rock movement is still achieved manually, as the available software does not consider optimal waste rock movement and dump design. This paper describes a tool to optimise waste rock placement, which minimises the haulage cost while creating environmentally friendly waste rock dumps through selective placement and encapsulation of the reactive waste rock in the dump. The embedded methodology in this tool has been developed based on the mixed integer programming (MIP) modelling technique to optimise the waste rock movement. The methodology provides an easily-manipulated and fully-automatic tool for professionals to complete waste rock dump scheduling in four main steps: data input, model construction, model computation and solution retrieval. The application of the new tool into a real case project in this paper shows that it can determine economically and environmentally optimised waste rock dump schedules in an acceptable time frame.CITATION:Fu, Z, Li, Y, Topal, E and Williams, D J, 2015. A new tool for optimisation of mine waste management in potential acid forming conditions, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 333–342 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By N L. Turner, K Ehrig, V Liebezeit, D J. Robinson, L L. Kuhar, N Francis

Conventional industry tests used to determine leach recoveries are often fully monitored and may be time-consuming and expensive. Such tests may be limiting in geometallurgical applications where large numbers of samples are required to be processed for characterisation of an ore deposit. BHP Billiton currently use a fully instrumented leach test for characterisation of Olympic Dam uranium-rich samples. Researchers at the Commonwealth Scientific Research and Industrial Organisation (CSIRO) were approached to develop an alternative to these full-scale leach tests that could allow for the ranking of samples in terms of their leachability. The novel geometallurgical test was required to use samples of small mass and be affordable and rapid.Three leach test protocols were pursued in developing the small-scale tests. Kinetic leach tests were performed using mild conditions at higher pH, low temperature and low oxidation reduction potential, moderate conditions at intermediate pH, temperature and oxidation reduction potential and aggressive conditions at lower pH, higher temperature and higher reduction potential.This paper presents results from 44 leach tests on 11 samples with varying uranium mineralogy. The developed small-scale tests correlate well with data from the more costly conventional industry laboratory tests, indicating the possibility of using this alternative test as a geometallurgical leach proxy. Simple regression analysis confirmed the importance of pH, reduction potential and temperature on uranium extraction. Experimental data were fitted to published leach models to predict uranium leach extraction for a range of operating conditions.The ultimate aim of the test work is to combine a limited number of large-scale calibration tests, a large number of small-scale geometallurgical tests and leach models for geometallurgical sample characterisation and evaluation of a wide range of scenarios or processing options.CITATION:Turner, N L, Kuhar, L L, Francis, N, Liebezeit, V, Ehrig, K and Robinson, D J, 2013. Development and testing of a small-scale uranium leach for geometallurgical applications, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 345-350 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013