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By J Parmenter

Issues around water û its quality, use, availability and environmental value û can be a major point of tension between mineral projects and local communities. Failure to manage these issues appropriately can jeopardise the obtaining of regulatory approvals for new projects and place at risk the æsocial licence to operateÆ of existing operations. Conversely, there may also be significant opportunities for companies to engage constructively with communities over water issues and to make a positive contribution to the sustainable development of these communities. Using case studies, this paper will explore the various types of social risks and opportunities associated with water and mineral resource development and identify key learnings relating to the management of these issues.

Jan 1, 2006

By F Brenguier, R A. Lynch, G Olivier

The seismic velocities of intact rock are dependent on the applied stress. Unfortunately, the low susceptibility of seismic velocity to stress changes mean that changes in seismic velocity have to be measured extremely accurately to infer stress changes from them. Previously, it was thought that measurements of this accuracy could only be made with active sources or repeating earthquakes. In this paper, we show that the noise generated by mining activity can be used to construct virtual seismic signals with which we can measure changes in seismic velocity accurately enough to see the short- and long-term effects of a production blast on the surrounding medium. The time-dependent velocity variations achieved with this method show that the blast caused weakening of the rock mass for the rock within a radius of 200 m of the blast. The weakening is healed by confining stresses over a period of five days, after which permanent changes in the seismic velocity can be seen. The size and spatial distribution of the seismic velocity changes were compared to modelled changes in static volumetric stress, which supported the notion that seismic velocity changes can be used to measure the redistribution of stress after a blast. The results of this study indicate that this method can be a powerful tool to evaluate the evolution of stress in a mine at a relatively low cost as the data that it uses would normally be discarded.CITATION:Olivier, G, Lynch, R A and Brenguier, F, 2016. Measuring the redistribution of stresses resulting from new excavations with ambient seismic noise correlations, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 873–878 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By S Van Duin, I Porter

This paper discusses how advanced manufacturing technology (AMT), which is fundamentally reliant on and developed via multi-disciplinary skills, has benefitted non-mining industries, and what lessons can be derived from this experience to benefit the mining industry, particularly underground coal mining. Examples of AMT use in æconventionalÆ industry, some drawn from the more than 25 years experience in many different industries of the Automation and Robotics team at the University of Wollongong, are described to show typical benefits, risks and opportunities expected in using AMT. Applying AMT to mining brings many unique challenges and this paper expands on these and then provides practical examples of how a multi-disciplinary team can develop new processes and systems leading to productivity, safety and other benefits for underground coal mining.

Sep 26, 2011

By G M. Tranell, M Tangstad

The CO2 footprints in the production of Mn-ferroalloys and silicon/ferrosilicon are correlated with the fossil carbon consumption. The CO2 emissions may be reduced in the Mn-ferroalloy process by increasing the degree of prereduction and reduction of carbonate materials, while the silicon/ferrosilicon process is optimised based on silicon yield. By changing the fossil reductant into biogenic reductants, the global warming potential will be decreased even more. Even if the reductants are biogenic reductants, there will still be a global warming potential (GWP) in eg the electrode consumption and the CH4 emissions in the charcoal production. To reduce the use of fossil reductants there are also more disruptive technologies like the use of H2 that at least for the silicon production is on a very low technology readiness level (TRL). Using metallothermic processes will reduce the use of carbon but requires carbon neutral metal reductants. Electrowinning can have low CO2 emissions, and the electrowinning of pure Mn is a technology of high TRL. Salt and oxide electrolysis is under investigation for both Mn and Si production however the research is still on a low TRL. The use of CCS/CCU (carbon capture storage/utilisation) is a part of obtaining carbon neutral processes. Last, the energy mix used for these energy demanding processes is discussed.

Aug 21, 2024

By G Diprose

Diamond exploration in Queensland is influenced by the South African approach modified by the discovery of diamonds in Lamproite in Western Australia. The current approach is to explore for Kimberlite and Lamproite bodies using indicator minerals dispersed by fluvial and colluvial processes. In the north-west, diamonds are derived from kimberlitic and lamproitic sources, whereas those in the coastal and subcoastal areas of eastern Queensland are associated with xenoliths included in rocks formed during Cainozoic volcanism. In these areas, sapphire is commonly associated with diamonds. In New South Wales diamonds in economic quantities occur in alkali basaltic intrusions and a subduction model has been proposed for these occurrences (Barrows et al, 1996). Exploration for diamonds in Australia increased following the discovery and exploitation of the Argyle mine. State geological surveys have produced digital information on the local occurrences of diamonds. As part of the Smart Mining Initiative (2006 - 2010), the Geological Survey of Queensland compiled a database and report on microdiamonds and diamond indicator minerals from open file company exploration data from 1968 to 2008 from the Department of Mines and EnergyÆs QDEX system. Most exploration in Queensland was conducted with exploration for other commodities. There is no commercial exploitation of diamonds in Queensland and, to date, only rare occurrences of microdiamonds. There is a regional difference in diamond occurrences with the kimberlitic and lamproitic models favoured for the north-western regions of the State and the subduction (S-type model) favoured for the eastern coastal zone linked to Cainozoic alkalic basaltic volcanism. Further diamond exploration is warranted in Cainozoic basalt provinces along the eastern coastal and near coastal regions and in the north-west of the state in conjunction with airborne geophysics flown as part of current Departmental Smart initiatives. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By R Polmear, G Mauger

You wouldnÆt start excavating before testing core samples, so why would you approve a project plan before all factors have been identified, reviewed and addressed? Even a champion sports team made up of the best players canÆt produce optimal results without a well understood and agreed game plan. Could an F1 racing team produce their outstanding performance without rigorous evaluation and testing of the factors for successful performance? Why would we expect a capital works project team to be able to get it right without an understanding and an involvement in setting and implementing the overall game plan and without an understanding of all stakeholder requirements? For International PowerÆs Hazelwood (IPRH) mine in Victoria, the challenge was development and delivery of a 40 year mine plan, ultimately involving relocation of existing mine operations into an adjacent new coal field, land acquisitions and major environmental and other approvals to allow diversion of three streams, a highway, an Over Dimension route and other infrastructure in a political and environmentally sensitive atmosphere. The lessons from International Power HazelwoodÆs (IPRH) experience are: that the clear set of project principles and guiding values ensured delivery of a robust plan; a robust plan can withstand significant change; and value management (VM) played an important role in providing assurance, to all, that the plan was sound at both the strategic and micro levels. This Hazelwood mine project included five major VM workshops. The first was a critical review process in addition to design and cost reviews. This VM workshop was used to analyse, at a high level, the preferred coal mining sequence and design concepts, together with the interaction between design elements, risks and costs. In addition to this, the workshop provided an agreed common pathway for all downstream decisions. A second VM study was conducted to ensure that the proposed plan and design for relocation of the conveying systems from the existing mine into the new field were planned for optimum achievement from a whole of life cost, time, operational and maintenance perspective, plus the logistics of continuing operations while relocating assets. A third study followed to review the Conveyor Transfer Alliance and review functional design. A fourth VM study workshop was formed at the start of Phase 2 Alliance to ensure that the best value for money was being achieved through the current design, schedule and project arrangements and that all interfaces between parties had been reviewed and responsibilities were clear and understood. Other studies are outlined later in this paper. This paper details the evaluation criteria and processes used in the project evaluation that led to the WestField Mine Development.

Jan 1, 2007

By A Lechner, T Baumgartl, S Arnold, P Audet

When revegetation is a part of a rehabilitation strategy at mine sites in arid and semi-arid environments, its success can be strongly affected by the availability of water prior or during the time of seed dormancy, germination and early growth of seedlings. The semi-arid and arid environments of northern Australia are characterised by highly variable and erratic rainfall and hence the actual weather conditions at and around the time of germination and seedling emergence play a critical role in determining the success of plant establishment and the type of plant community that may develop.Using available climate data, an analysis has been undertaken and a set of indices has been developed which describe the suitability of the climatic conditions for rehabilitation. In total, eight sites from Queensland and one site from New South Wales, Australia have been analysed. It could be determined that regular rainfall and relatively short periods of water-deficit are key characteristics of climate suitability. A comparison of the locations studied allowed the separation into suitable and susceptible locations in terms of the availability of water, amount of rain and duration of drought between rain events.In our experience, specific estimates of climate suitability are rarely incorporated into the design of mined land rehabilitation programs. We consider that the regional intensity, seasonality and extremity of climate represent an overarching component of landscape complexity, which in turn will influence the development of post-disturbance ecosystems in these regions. This paper presents the outcome of climate analyses paired with the development of suitability indices. A conceptual framework is presented explaining the suitability matrix and its incorporation as a prognosis tool to achieve greater certainty for success in rehabilitation development.CITATION:Baumgartl, T, Arnold, S, Audet, P and Lechner, A, 2014. Development of climate-based suitability indices for the improvement of success in rehabilitation, in Proceedings Life-of-Mine 2014 , pp 483–490 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By A Datar, D Mulligan

The extractive phase of broad-scale mining can have major impacts on landscapes and associated ecosystems. Post-mining ecological rehabilitation typically starts with reconstructing topography. A fairly common industry practice has been to use landform elements such as plateaus, terraces, and gentle slopes for stabilisation purposes. However, this approach can lead to the generation of fairly uniform landforms that do not necessarily reflect natural ecosystems. Previous research in undisturbed and agricultural landscapes shows that ecological attributes and diversity in microclimates is positively correlated with landform heterogeneity. An objective of this study was to investigate if those findings are still valid in post-mining rehabilitating landscapes on North Stradbroke Island, Queensland, Australia. We investigated the relationship between landform heterogeneity and status of ecological recovery. The landform heterogeneity is measured through variance in three landform characteristics (relief, slope, aspect) using remote-sensing data and the status of ecological recovery is represented by ecological indicators measured through field surveys. The results indicate strong correlations between landform heterogeneity indices and native vegetation species richness with sensitivity to the spatial scale of investigation. It is recognised that climate, substrate and rehabilitation practices act as primary drivers of rehabilitation success. However, the results indicate that, in some examples, landform heterogeneity (heterogeneity in relief and slope angles) contributes up to 30 to 50?per?cent of the variance in native vegetation species richness. While the primary drivers of ecological recovery are difficult to control over extensive areas and extended time periods, landform heterogeneity provides a tool to indirectly control the micro-environmental parameters to improve ecological recovery. Reducing the uncertainties in the choice of ecological and landform indices and the degree of landform heterogeneity suitable for particular rehabilitating landscapes would be site specific. The introduction of desired landform heterogeneity may provide a very effective tool for significant improvement in ecological rehabilitation across broad-scale post-mine landscapes, an outcome of benefit to industry, government and local communities.CITATION:Datar, A and Mulligan,?D,?2014. Do we need to change the way we set up the stage?, in Proceedings Life-of-Mine 2014 , pp 29–46 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Battino S

ABSTRACT' The high gas emissions associated with coal extraction at some-Australian collieries have provided a need to investigate the methods used to predict these gas levels and the vent- ilation requirements for gas dilution. It is generally accepted that the introduction of longwall extraction in particular is associated with complex ventilation planning problems. These problems are made much more severe when the colliery introducing longwalls is already facing high gas emissions even during the development stages. A forecast of likely gas emissions during the longwall mining process indicated possible ventilation problems in maintaining the necessary ventilation levels to satisfy the statutory gas limitations for various production rates. Although there are sound principles used in world recognised methods of gas emission prediction a new approach developed from the findings of the Barbara Experimental Mine in Poland appears most suitable for Australian conditions. This has been applied to an Australian colliery preparing for longwall mining using statistical methods for air

Jan 1, 1983

By Balint F

The Izok massive sulphide deposits are located in the Northwest Territories of the remote western Canadian Arctic. Together they represent one of the highest grade undeveloped zinc-copper resources in North America. Metall Mining Corporation is presently engaged in a feasibility study on developing the Izok property as well as actively exploring for additional reserves. The Izok deposits are Archean-aged, volcanogenic massive sulphide (VMS) bodies hosted within and near the top of a thick sequence of predominantly felsic pyroclastic rocks. The hangingwall package includes additional felsic volcanoclastics, dacitic and basaltic flows, thin sulphide-rich iron formations, and turbiditic sediments. The felsic volcanics are intruded by syn- to late-hydrothermal dacitic dykes and sills and post-hydrothermal gabbroic dykes and sills. Both intrusives are interpreted to be volcanic feeders to overlying flows. All lithologies are cut by much later irregular granitic pegmatite dykes and regionally metamorphosed to pyroxene homfels grade. The deposits occur within a large kilometre-scale soda-depleted alteration zone. The immediate footwall and hangingwall rocks to the deposits are characterised by zones of muscovite-biotite (with or without sillimanite), lesser chlorite-biotite-cordierite (with or without anthophyllite), and locally intense silicificified and albitised zones. All lithologies have been affected by a later calcic metasomatic alteration. As currently defined, the Izok Zn-Cu-Pb-Ag deposits comprise a cluster of four complexly-zoned composite lenses: the Northwest, North, Central, and newly discovered Inukshuk deposits. The first three deposits are amenable to open pit mining while development of the Inukshuk deposit will require underground methods. The combined mineral inventory of the Northwest, North, Central and Inukshuk deposits at present totals 15.6 million tonnes with a grade of 2.4 per cent Cu, 13.8 per cent Zn, 1.4 per cent Pb, and 74.6 g/t Ag.

Jan 1, 1993

Intermontane valleys form unusual features of compressive mountain belts both in the sharp topographic break they represent and in the strike-slip displacements often associated with the valleys. Such strike-slip motion seems hard to reconcile in the actively deforming Andes where reconstructions have indicated nearly perpendicular Cenozoic plate convergence. Detailed study of a part of the Argentine Andes between latitude 31-33¦S suggests that, although strike-slip displacements may have largely created a prominent intermontane valley system, no Holocene strike-slip displacements are observed amid the relatively active compressional deformation along the mountain belt flanks. New plate reconstructions, treating the Nazca plate as two microplates separated by fractures along the Nazca Ridge, predict large components of strike-slip motion between the South American and Nazca Plates for the period from 10 to 5 Ma. These reconstructed plate motions are consistent with strains derived from recent kinematic analyses of minor faults along the southeast margin of the Puna plateau and the general timing of tectonic phases in the Andes.

Jan 1, 1987

By J Zhang, O Ostrovski, C Zhang D Cai, Q Wang

The conventional CaO-SiO2-based mould fluxes are not suitable for high-Al steel casting because of the strong reaction between silica in the flux and aluminium in the steel strand. In the process of casting of high-Al steel, flux composition changes; with the decrease of the silica concentration and increase of alumina. Knowledge and understanding of the effect of the Al2O3/SiO2 ratio on flux structure and properties are useful for flux design for the high Al-steel continuous casting. This paper investigated the effect of the Al2O3/SiO2 ratio on structure, viscosity, phase composition of fluxes quenched at different temperatures and heat transfer of CaO-Al2O3-SiO2-B2O3-Na2O-Li2OMgO- F fluxes. It was found that flux melting temperature increased with the increase in Al2O3/SiO2 ratio. Viscosity of the flux melts increased significantly with the increase of the Al2O3/SiO2 ratio from 0.7 to 1.2, reaching the maximum value, and then decreased with further increase of the Al2O3/SiO2 ratio. Raman spectroscopy analysis revealed that the change of the Al2O3/SiO2 ratio led to the change of aluminate and silicate structural units. The turning point for viscosity was attributed to the change in the degree of flux polymerisation. X-ray diffraction (XRD) analysis showed that increasing Al2O3/SiO2 ratio increased crystallisation tendency of the fluxes. Heat transfer measurement by infrared emitter technique (IET) revealed that increasing Al2O3/SiO2 ratio led to the decrease in heat flux which is correlated well with the increased crystallinity of the flux. The results suggested that the flux with Al2O3/SiO2 ratio 4.3 is the best candidate among the studied CaO-Al2O3-based mould fluxes for casting of high-Al steel.

Aug 21, 2024

INCREASE OF THE OIL CONSUMPTIONIt is of the greatest interest to study the prospects open today for the petroleum industry by looking back to the past years.The' results for the past 15,years can be said. to be- satisfying; - the develop-ment of the petroleum industry has sustained a very fast tempo and the world consumption of energy has around the years 1960-1961 - reached aòpeak figure.Undoubtedly, the petroleum industry is the principal beneficiary of the growth of world, energy demand. For the caning years a slackening of the rate of expansion is'. likely to be expected; but will. not alter the general trend. This ' slackening of expansion may be explained, partly by a better use of the energy consumed and by the increased use of new types of energy, mainly natural gas.Although.the development of world energy demands follow structural and tech-nical modifications".,-At. can be foreseen, without any doubt, that the petroleum products. consumption. vri 11 be less affected than any other type of energy by this limited reduction in the rate of increase.

Jan 1, 1962

By V Salamakha, K Tang, G Si, J Oh, X Wu, Z Yu

The development of machine learning (ML) algorithms has led to promising advances in lithology classification from geophysical logs, which is indispensable in various underground engineering applications. Due to the resolution and availability of logging data, ML models can recognise lithology change in a definitive form at a fine scale (0.01 m). While the results from previous models indicated promising performance in the classification, the robust capability of generalising lithology prediction to unseen data may not be true for those models due to: (1) data bias caused by borehole selections, and (2) logging data mismatches among boreholes. To this end, this paper aims to investigate the generalisability of ML models and seek potential improvements. Four ML models were selected to be trained on single reference boreholes to test the other (as unseen) in the same region, which includes Support Vector Classifier (SVC), Random Forest (RF), eXtreme Gradient Boosting (XGBoost) and Residual Neural Network (ResNet10). The data set involves 11 boreholes from a coalmine in north-western Bowen Basin (Queensland, Australia): density, gamma ray, neutron, and sonic logs are selected as inputs. Additionally, a data adaptation method is applied for better generalisability. The results show that there is an accuracy trade-off between the same borehole and unseen boreholes across the models. It also indicates a 16–43 per cent reduction in model performance when generalising the predictions (in marco-F1 score), while the adapted data sets can contribute to a around 12 per cent improvement. This study provides a fundamental understanding of the model generalisability when using a single borehole, essential for further correlating boreholes for regional lithology classification; the adaptation method can improve the generalised accuracy, and reduces the labour to label lithology, which facilitates the identification of gas storage mechanisms, geological/geophysical modelling, and stratigraphic analysis.

Sep 1, 2024

By B Oostendorp, R van der Merwe, P

In order to assess whether polysaccharide depressants are strongly or weakly and reversibly bound to the surface of talc, a series of experiments was conducted on New York talc in which the floatability of the talc in a microflotation cell was determined. The talc was conditioned in solutions of carboxymethyl cellulose (CMC) or guar gum in 10-2 ionic strength Ca(NO3)2 or Mg(NO3)2. The talc was then washed with four successive aliquots of water, or cation solution, to try to remove the polymer and the flotation response of the talc was assessed. CMCs of different charge (DS) were used to assess the effect of charge on the strength of bonding. The results show that CMC and guar gum could be removed to a large extent from the talc surface by washing with water (the floatability was restored), however very little could be removed from the surface by washing with cation solution. The higher charge CMC was easier to remove from the talc planes in the absence of cations than the lower charge CMC. Thus CMC bonding to talc has been shown to be irreversible or very slowly reversible only if cations are present, implying that cations are necessary to keep the polymer bound to the surface of the planes to effect depression. The presence of ions in solution also had the effect of maintaining surface coverage of the talc by guar gum.

Jan 1, 2005

By A Keddie

Standard microeconomic theory suggests that the behaviour of mineral extraction and processing firms with respect to their demand for water can be modelled and a market demand for water subsequently derived. Such a model, although an abstraction of the real world, should be able to predict the responsiveness of quantity of water demanded to change in price, and, change in demand to a range of factors including: expectations about reliability of supply, changed commodity prices for mineral production, and change in water technology and storage at mine site. This paper demonstrates that the price of water is particularly responsive to changes in demand and that although price increases would result in some additional supplies, physical constraints on supply suggest that the industry will be paying considerably higher prices for water in the future. It is recommended that the mining industry undertakes quantification of possible price increases to position itself to minimise the impact on their operating costs as well as to make responsible capital investment decisions to facilitate future expansion or commissioning of new mines. Substantial investment is required to commission a new mining venture with expected rates of return subject to risk and uncertainty due to fluctuations in world commodity markets as well as reliability of secure supplies of inputs. If a reliable supply of water was subject to uncertainty and water was a critical input for production, then the initial mine design would typically consider a range of production decisions contingent on levels of uncertainty with respect to water supply. These states or sets of water supply, will affect production decisions and future water demand. Modelling production decisions contingent on different states of nature, termed the state-contingent approach, provides a number of insights about producer behaviour under uncertainty. This paper investigates the assumptions underlying the derivation of the market demand for water by the mineral resource industry and identifies the drivers of demand and the responsiveness of the industry to change in price and supply, particularly in relation to capital investment in water-use technologies. The usefulness of these models to the mining industry is considered by reference to the increasing demand for water by the industry in Queensland, in a climate of water shortages.

Jan 1, 2006

By A McRae

Much of western New South Wales is characterised by an extensive regolith formed during more than 60 million years of exposure, weathering and erosion. This cover includes intensely weathered in situ regolith and superimposed transported materials of variable thickness, commonly in complex palaeochannel systems. Mineral exploration in this region has been considerably hampered by the cover, which can complicate or maskgeochemical anomalies and also obscure geophysical signatures. A detailed multi-disciplinary study of part of this region, centred on the Cobar-Girilambone area has demonstrated a methodology for exploring through this regolith. The approach involves regolith-landform mapping to establish the main landscape and palaeolandscape elements and to determine the nature and spatial occurrence of different regolith materials. By combining knowledge of the surface distribution of different regolith-landform units with available 3D information on the regolith and geophysical data it is possible to construct simplified derivative maps or exploration ægoÆ maps, which can be used to advise appropriate exploration strategies or help interpret acquired exploration data. This study has also established the major regolith controls on geochemical dispersion and determined key background element associations. These regolith-related element associations can result in highly variable background levels for many trace elements and need to be understood and factored into the analysis of geochemical data for different regolith sampling media. With better knowledge of the regolith it is possible to select the most appropriate exploration techniques and sampling media for a given area, as well as apply appropriate normalisation procedures to the acquired data. Exploration success can be greatly improved by using many existing techniques in æregolith smartÆways.

Jan 1, 2004

By M Pizey, P Lindsay

Coal mining has been occurring on the Stockton Plateau for over 100 years. As a result of both natural conditions and mining activities, surface water on the plateau is known to have low pH and elevated metals concentrations, a condition known as acid rock drainage (ARD). Solid Energy New Zealand Ltd (SENZ), as owners of the current mining operations at Stockton desire to understand the nature and causes of ARD at Stockton to determine whether commercially viable options can be developed to improve the water quality to levels acceptable to the local community and regulators. A series of integrated water quality investigations have been performed towards developing a characterisation of the water quality on the Stockton Plateau and receiving waters. The investigations performed include: design and implementation of a water quality monitoring program to collect a satisfactory base of water quality data from which to develop an understanding of the water quality and its variability, and to collect data regarding the range of flow rates that occur in the principal streams; development of a hydrological model for the Plateau with the ability to predict flow rates at key locations on the plateau and on the Ngakawau River; field investigations of the bio-diversity of the plateau and surrounding areas, to develop a snapshot of the health of aquatic communities and whether streams draining mine workings are æadversely impactedÆ; eco-toxicology; waste dump seepage water quality monitoring at selected basal springs, drilling, investigations and permeability and geochemical testing; data processing of a range of historical data and the newly acquired data for the development of empirical relationships that describe the water chemistry system and its relationship in turn to flow rates in the streams; simulation of the long term water quality record for the measured parameters (pH, acidity and metals concentrations), based on the hydrological model and the empirical relationships developed from the new database; and preliminary development and examination of mitigation options for the ARD issues at the mine. The study has progressed towards design of pilot studies of options for mitigation of the generation of the ARD as well as treatment of the discharges. It is the integrated approach adopted by SENZ from an early time in the investigations, that has enabled fast-tracking of the pilot engineering trials. This paper presents the results of the field investigations and eco-toxicology studies and demonstrates the value of predictive modelling of water quality in the study area, even at a very early stage in the remedial engineering design process.

Jan 1, 2003

The Hemersley Ranges are located in the North West Division of Western Australia and extend, approximately, from latitudes 21¦ 30! to 23¦S and longitudes 117¦ to 120¦E. Their mean height above sea level is'. 2,000 feet, and they rise from 600 to 800 feet. above the gen- eral level of the tableland which extends south-east from the coastal town of Roebourne.. Mt. Bruce, the highest peak, is 4,024 feet above sea level. The ranges are intersected by numerous north-flowing streams, dry during the greater part of the year, which have carved deep gorges, and it is in these that the principal deposits of orocidolite outcrop. The presence -of the mineral was first recorded in 1917., but the deposits remained untouched until 1937 when reports of a strong market demand for-croeido lice resulted in considerable prospecting and mining activity, particularly in Yampire, Wittenoom and Daleis Gorges. . It was established also that the blue asbestos belt extended from Willi- Wolli Springs north-west to Millstream Station, i.e.,-over a.:length of 180 miles and a width of 20 to 30 miles. A number of attempts were made to develop aid treat the Yampire and Wittenoom'Gorge deposits from 1938 onwards, but, for a ,variety of reasons, none of these-proved successful. Current production,. is wholly by Australian Blue Asbestos Pty. Limited at Wittenoom Gorge. This company commenced operations at the Wittenoom Mine in 1946, with an output of 601.8 long tons of- fibre,. and later transferred tb the Colonial Mine about one mile to the north-west. Output has been increased steadily to an' average of 12,000 to 14.,000.. long tons; per annum over the past six years. The total Western Australian output to the end of 1962 is reported by the Mines Department as 110,013 long tons valued at úAl2,403,728..

Jan 1, 1964

By E Nettleton, A Melkumyan

Identification of geology and mineralogy in situ on the mine face is essential if mining processes are to be automated for tasks such as exploration, grading and reconciliation. Hyperspectral data acquired from field based platforms are ideally suited to these tasks, and are set to revolutionise the automated mining industry. Changing conditions of solar illumination introduces variation into the hyperspectral signal, which is unrelated to geology, complicating analysis of data. Thus, algorithms must be able to deal with changing illumination conditions and operate in a consistent and probabilistic framework, which is a prerequisite for data fusion with other sensors. To produce accurate classification maps of geology, algorithms must be developed that are effective under different conditions of illumination.The efficacy of three algorithms to classify hyperspectral data for geology mapping on vertical mine faces was assessed. These algorithms are the spectral angle mapper (SAM), and two machine learning methods operating within a fully probabilistic Gaussian process (GP) framework û the squared exponential (SE) and the observation angle dependent (OAD) covariance functions (kernel). Two experiments were done to assess the classification performances. The first determined the performance of the algorithms by classifying hyperspectral data of known rock samples acquired using a field spectrometer. The GP-based methods had a similar performance, with average accuracies and F-scores of 97 and 88 per cent (GP-OAD) and 95 and 81 per cent (GP-SE), respectively. Average accuracies and F-scores for SAM were significantly smaller (80 and 40 per cent respectively). The algorithms were then applied to hyperspectral imagery acquired from a vertical mine face at different times of the day, under very different conditions of illumination. In contrast with experiment 1, SAM and GP-OAD gave results which were superior to GP-SE and were entirely consistent with geology mapped in the field. Compared with SAM, GP-OAD was less sensitive to the effects of shadow and produced classified images that were less noisy. The GP-SE method failed to delineate even gross changes in geology on the mine face. These results show conclusively that in order to use independent training data (spectral library) to classify imagery acquired under a different set of conditions, algorithms must take into account variability in incident illumination. Measures based on spectral distance are inferior to those based on spectral angle.The OAD kernel within the GP framework (GP-OAD) is superior to the other two methods because:it provides a probabilistic framework;it is insensitive to variability in illumination within and between imagery acquired under different conditions; andit can identify and map geological zones on a vertical mine face using an independent spectral library, without a priori knowledge.

Sep 26, 2011