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By M H. Randell, J B. Haines

The Honeymoon Uranium Project comprises the Honeymoon Deposit,Goulds Dam Deposit and Yarramba Prospect in the Southern Lake Fromeregion, South Australia. Both the Yarramba Prospect and HoneymoonDeposit (which includes Honeymoon and East Kalkaroo orebodies) arelocated in the Yarramba Palaeovalley. The Goulds Dam Deposit is about75 km north west of Honeymoon, in the Billeroo Palaeovalley. Exploration for sediment-hosted uranium began in the area in the late1960s, culminating in the discovery of Honeymoon and Goulds Dam inthe early 1970s. In 1982, a 25 L/s demonstration plant was built atHoneymoon to confirm suitability for in situ leaching. The project was put on hold in 1983 due to changes in government policy. Southern Cross Resources Australia Pty Ltd acquired the project in mid 1997. Roll-front deposits form from a migrating geochemical cell, anadvancing reduction-oxidation interface between oxygenateduranium-bearing groundwater and its reduced aquifer host. The source of metal is uranium-anomalous granites, which were eroded fromsurrounding ranges. The weathered granites and resultant sediments are stripped of uranium by oxidised groundwaters, to form solutions carrying uranyl carbonate complexes. The solutions percolate down-slope through permeable sand zones until contacting a reduced environment where uranium precipitates. Uranium mineralisation occurs interstitially between and as thin coatings on sand grains, usually in the form of uraninite or coffinite. The palaeovalleys (previously termed palaeochannels) are incised intounderlying Cambrian/Precambrian basement rocks and filled withsemi-consolidated, largely un-cemented, Tertiary sediments of the Eyre Formation. The late Palaeocene to middle Eocene Eyre Formation is the basal unit of the Tertiary succession in the Callabonna Sub-basin of the Lake Eyre Basin. Further to the north, the Lake Eyre Basin overlies the Jurassic-Cretaceous Eromanga Basin, which comprises much of the Great Australian Basin. Eyre Formation sediments are in turn overlain by the late Tertiary Namba Formation and terrestrial Quaternary units. At Honeymoon, the Eyre Formation includes immature, pyritic,carbonaceous sands and gravels interbedded with lignite andkaolinite-illite-montmorillonite clays. It was deposited by braidedstreams during epeirogenic uplift of the Olary Ranges, accompanied bysubsidence of the Lake Eyre Basin. The Eyre Formation comprises aconsistent stratigraphy of interbedded sand and clay units that arecontinuous over the Honeymoon Deposit but with local variationindicating some hydrological connection between aquifers.In the Honeymoon orebody, uranium occurs within coarse-grained,pyritic sands where the basal sand pinches out between overlyingcarbonaceous clay and the southern palaeovalley slope. Its characteristics are typical of the well-developed, planar limb of a roll-front uranium deposit. Zonal changes related to the reduction-oxidation interfaces across the deposit are readily observable. The orebody extends for nearly 1000 m along the valley margin, is 400 m wide at its maximum and averages about 6 m in thickness. The East Kalkaroo orebody also lies near the southern margin of theYarramba Palaeovalley. It extends discontinuously for approximately 3.5 km and averages 200 m width, with significant uranium present in the Middle as well as the Basal Member. The Billeroo Palaeovalley extends northward for 40 km sub-parallel tothe western side of the Benagerie Ridge, is up to 5 km wide and hasgently dipping banks. Eyre Formation within the palaeovalley isconcealed beneath 90 m of Quaternary and Namba cover, isapproximately 40 m thick, and is sub-divided into three upward-finingunits, which are remarkably similar to the Yarramba Palaeovalleysequence.

Jan 1, 2001

A combination of highly structured, fissile stope hangingwalls and high ground stresses have caused difficult mining conditions in the Main Lode Deeps at Lancefield Gold Mine. Cyclic reviews of ground support and stoping techniques, coupled with geotechnical investigations, and the application of numerical modelling has led to the successful management of stoping operations.

Jan 1, 1995

By Fallins J

THE John Darling Colliery, owned by The Broken Hill Proprietary Company Limited, is situated 12 miles south of Neweastle, NSW and about 1 mile from the ocean. The area of the holding is approximately 10,000 acres, about half of which underlies the Pacific Ocean. The area was proved to be coal bearing by diamond drill boring: this method not only proved the coal to exist, but gave the depths from which could be calculated. It also proved the existence or otherwise of heavy faulting, which is a very important factor in the design of the underground lay-out of a mine. The location of shafts had to be carefuIly studied, and, before final selection, the following salient points had to be considered:Railway communications.Flood waters.Boiler feed water.Surface buildings.Probability of coal washing.Underground haulage arrangements.Lengths of roadways from a ventilating viewpoint.Before the shaft sites were finally selected, an underground design was prepared to determine the direction of the main drives in relation to the boundaries of the holding, and the of the coal seam: the latter, being an important factor in this particular locality, was ascertained by a geological survey of rock outcrops in the neighbourhood. Size of shafts was the next subject for consideration. This was determined by output, number of seams to be worked, amount of ventilation required, and, on...

Jan 1, 1930

By P Bergin, J M. Galvin, J Harris, J Li, P Kirsch, M Shi, B Hebblewhite, B Whittaker, R Mitra, D Sprott

Controlling unwanted ground movement is critical in mining as well as many other highly hazardous environments, such as construction and tunnelling. Sharing knowledge about effective hazard management is paramount to improving health and safety and operational outcomes across industries, and some industry sectors have embraced this openness as part of the way that they do business. In 2010, the Australian Coal Association Research Program funded the RISKGATE project to build a body of knowledge for managing a broad range of hazards across mine sites, lease areas and mine infrastructure within a mine-life or product life cycle perspective (eg from exploration through to decommissioning, or design through to operation). The RISKGATE body of knowledge was assembled from Australian coal industry experts through a semi-structured bowtie analysis-based action research workshop cycle. By capturing operational knowledge from industry experts, RISKGATE serves to provide a cumulative corporate memory at a time of high personnel turnover in the coal industry.This paper presents an overview of RISKGATE topics within the geological and geotechnical domain (strata underground, ground control open cut, outburst, coal bumps and bursts, tailings dams and inrush) with a summary of individual topic structures, as well as showing the contrasts and inter-relationships between these ground management topics. The online user can access information about the causes, controls and consequences related to a priority unwanted event (ie the point at which control of energy is lost) and use this information as a prompt for the development of risk assessments, incident investigation, audits of practice/plans/procedures and for training and development.The paper concludes with a discussion of how RISKGATE can be adapted to other mining domains (eg coal outside of Australia, hard rock mining worldwide, construction, tunnelling) and the opportunity for application of this body of knowledge and the RISKGATE action research process for knowledge management in other highly hazardous environments.CITATION:Kirsch, P, Hebblewhite, B, Sprott, D, Harris, J, Li, J, Shi, M, Whittaker, B, Galvin, J M, Bergin, P, Mitra R and Williams, D, 2014. RISKGATE – shared coal mining knowledge for managing risks across ground management, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 247–254 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By N Steenkamp, L Furstenberg, W Cele, M Richter

Managing productivity and improving efficiency for a healthy return on capital employed have become key mining industry strategies under prevailing tough global market conditions. However, achieving this in a multisystem environment such as a mining operation can be daunting. The field of discrete event simulation offers some relief, giving engineering teams insight into multivariable systems and stochastic processes. It allows for integrated system thinking and domain expertise to be woven into project thinking fibre. Directed system optimisation and therefore improved efficiency becomes possible. Furthermore, capital discipline accrues from optimal upgrade investments. This paper illustrates the practical application of this approach by reviewing a typical case study for a direct shipping iron ore operation. Dynamic simulation was used to establish maximum processing plant capacity under varying material characteristics and identify capital-efficient upgrades for increasing production.The study started with descriptive statistical analysis of existing data. Discrete equipment and system capacities were defined, followed by static plant mass balance calculations to establish bottlenecks and overall static capacity. Equipment ‘uptime’ and ‘downtime’ analyses established system and overall plant availability and utilisation. From this information, a dynamic simulation model could then be developed and initially calibrated against actual plant performance to verify its robustness. Once confirmed to accurately represent existing plant dynamics, system capacity response to variable changes could be tested to ultimately determine maximum plant capacity. Additionally, plant optimisation was incorporated to arrive at optimal upgrade points. Maximum capacity and necessary upgrades were established as a function primarily of feed size distribution. Additionally, the interfacing effects of rehandling feed material to the final product grade and potentially to life-of-mine were established as important outcomes. The results of the study illustrate the value of using dynamic simulation models to realistically and cost-effectively increase throughput.CITATION:Cele, W, Furstenberg, L, Richter, M and Steenkamp, N, 2015. Capacity evaluation of iron ore processing facilities utilising dynamic simulations, in Proceedings Iron Ore 2015, pp 597–604 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Salley J, Gould WD

The stack-gas scubber effluent from base metal smelters often contain 20-100 ppm of oxidized selenium salts. Due to their toxicity, these must be removed from solution prior to release of the effluent to the environment. Many species of microorganisms including Corynebacterium diotheriae, Neurospora crassa, Candida albicans, Escherichia coli and various species of Salmonella are capable of assimilating oxidized selenium and reducing it intracellularly to red amorphous selenium. CANMET in cooperation with several companies has developed a biological process to recover selenium from dilute solutions. The laboratory, mini-pilot plant and the large industrial pilot- plant studies leading to the development of this process will be described.

Jan 1, 1990

By W A. Ducker, R-H Yoon, M Mao

Froth flotation relies on an attractive force between a particle and a bubble to selectively extract particles from a mixture. The range and magnitude of this attractive force is an area of ongoing investigation. We describe measurements of the effect of dissolved gases on the long-range attractive surface forces between a silica plate and a glass sphere in aqueous octadecyltrimethylammonium chloride (C18TACl) solutions. The measurements follow on the work of Sakamoto et al (2002) who have concluded that long-range interactions occur in air-equilibrated surfactant solutions but not in degassed solutions. In the present work, we have measured attractive forces that have a much larger in magnitude than the expected van der Waals force in solutions that were degassed by the same procedure used by Sakamoto et al (2002). We find that the forces are most attractive at 5 + 10-6 M C18TACl, which is close to the charge compensation point (ccp) of the glass sphere. At this concentration, the attractive force decays exponentially with distance and the decay length is 34 in air-saturated solution, and 38 nm in degassed solutions. In both air-equilibrated and degassed solution, the force is quite sensitive to the concentration of surfactant. The force is also sensitive to the pH. We note that our degassing procedure increases the pH of the solution from about 5.7 to 6.6 (presumably by removal of dissolved CO2). We find that the forces measured in degassed solution can be reproduced by using a solution that was equilibrated in air, then the pH was increased by addition of NaOH. Therefore, we conclude that the main effect of degassing in our experiments is to raise the pH. We show that the range and magnitude of the attractive force decreases in the presence of salt (NaCl). This suggests an electrostatic mechanism for the attraction. Possible mechanisms for the attractive force are examined, including the mechanisms that rely on a patchy coverage of surfactant on the silica surface.

Jan 1, 2005

Mining companies often view water quality as an environmental issue. The importance of water quality as a production related issue in mineral beneficiation is greatly underestimated at many mineral processing operations. While most mine sites have comprehensive water balance data for water quantity, the information regarding the quality of water supplies available on site is limited, inadequate or non-existent. The seasonal variations in process water quality and changes in the composition of various water streams are not known. Despite the fact that water represents about 80 to 90 per cent of the volume of mineral pulp processed in a flotation plant, the influence of process water composition on flotation performance is often poorly understood. The process water used at mineral processing operations is made up from a number of available water sources, which can be classified as recycled water streams or make-up waters. The recycled water streams are commonly the tailings and concentrate thickener overflows, filtrate from the concentrate filtration plant and tailings dam return water. Make-up waters can originate from a variety of sources: surface waters (rivers, lakes, reservoirs, dams), groundwater (wells and springs), mains water (potable water), treated and untreated sewage waters and industrial effluents. Mineral processing plants are increasingly recycling water to reduce demand for fresh water and minimise the discharge of wastewater to the environment. However, increasing water recycling can have adverse effects on process water quality and ultimately on the performance of mineral separation processes. The main reasons for reduced plant performance due to water recycling are the accumulation of organic and inorganic compounds in the process water and increased microbiological activities. Other detrimental effects of water recycling can be increased reagent consumption and inefficient dewatering of tailings and concentrates. Recycling of water also tends to accumulate very fine suspended particles. Excessive amounts of slimes in the process water can also have an adverse effect on mineral beneficiation processes. The main constituents of process water are dissolved gases (oxygen, nitrogen, carbon dioxide), colloidal and suspended solids of inorganic and organic nature (including micro-organisms: dead or alive), dissolved organics (natural organic matter, residual reagents, reaction and decomposition by-products of chemical reagents, impurities in the reagents and metabolites originating from microbiological activities) and inorganic compounds (acids, alkalis, inorganic salts, metal ions, anions and heavy metals). Inputs to the chemical composition of process waters are: dissolution of soluble mineral phases present in the ore, surface oxidation followed by dissolution of mineral particles during grinding and mineral processing, the chemical composition of various make-up waters and recycled water streams, and reagent additions during mineral processing. The beneficial or detrimental impact of process water quality on flotation performance can be attributed to a number of subprocesses: adsorption and/or precipitation of inorganic and organic species present in the process water onto the surface of mineral particles, chemical reactions between process water constituents and the chemical species present on the surface of mineral particles and interactions between the chemical and microbiological species present in the process water and the various reagent species added in solution during mineral processing. Dissolved chemical species such as calcium, magnesium, iron, copper, lead, zinc, nickel, sulfates, phosphates and carbonates can have a strong effect on the electrokinetic properties of oxide and sulfide minerals, at certain pH ranges. Several reactions can occur at the solid-liquid interface that can play an important role in determining surface adsorption of reagents. Solid-liquid interfacial properties of mineral particles can be significantly affected by the conformation of adsorbed and precipitated reagent layers, which in turn are determined by solution chemistry. The chemical and microbiological constituents of process water can have a significant effect on liquid-gas interfacial properties and have a strong influence on froth height, strength and stability during flotation. Water chemistry can play an important role in determining the interactions between minerals present in the ore and the chemical reagents added in the mineral processing plant by altering the reagent-solution and mineral-solution equilibria. These interactions can include dissolution, micellisation and precipitation of reagents, dissolution of minerals contained in the ore followed by hydrolysis, complexation, adsorption and precipitation of dissolved chemical species and reactions between dissolved ions and various reagent species present in solution. All of the above mentioned subprocesses can ultimately have a significant effect on the efficiency of mineral processing operations. In this presentation, a systematic approach for assessing the composition of water supplies available at the mine sites and for investigating the influence of process water quality on the efficiency of mineral processing operations will be discussed. The consequences of mixing different quality water streams to produce the required volumes of process water for some flotation plants will be highlighted. To substantiate the water quality issues described in this paper some examples are given from a metalliferous processing perspective. However, the topics described in the paper are not only relevant to metalliferous processing but to all other type of mineral processing operations as well. In fact the principles described in this paper have also been successfully applied to the coal flotation industry.

Jan 1, 2006

By P Mesquita, A Nolan

Using a scientific-principled definition of global socio-ecological sustainability can be a useful basis for planning precious and base metal mining projects. The mining industry faces key challenges of; viability of the minerals industry; the control, use and management of land; national and local socio-economic development; environmental management; materials stewardship; and access to information. Using a framework for strategic sustainable development to assess the current reality of mine project development has resulted in identifying areas of strength and opportunities for improvement between current best practices and a desired vision of sustainability constrained by science based principles. These gaps indicate opportunities to strengthen current strategies, tools, and actions with a deeper understanding of socio-ecologic systems and a first-order, principled definition of sustainability, enabling success in moving towards achieving a sustainable society, ie sustainability. Evaluation of mine project development and their impacts on ecological and social systems using a systems perspective which recognises the underlying principles of operation, delays, feedback loops and response to change highlight specific opportunities to create value for social, economic and ecologic systems. Envisioning this future for mining projects within a sustainable society can be done by evaluating their development and operations guided by the sustainability principles. Performance indicators play a key role in measuring progress towards achieving sustainability goals yet it is necessary to consider whether indicators capture the whole systems perspective. Connected to this broader view, indicators can contribute much value to the mining industryÆs sustainability journey. This paper examines how current processes for mining projects can be developed using a whole systems perspective and measured using holistically designed performance indicators.

Jan 1, 2009

The O.K. deposit occurs within a belt of cherts and spilitised basic volcanics near the western margin of the Hodgkinson Province. The tabular to lenticular shape and gross conformability of the ore bodies; the common occurrence of colloform, framboidal and banded textures in the ores; the lack of significant alteration adjacent to the massive ore horizons and the apparent restriction of stockwork mineralization to the foot-wall side of the massive ore zone at the O.K. mine, all favour a syngenetic origin for the massive sulfide bodies. Furthermore, the micro- structural evidence suggests that the ores have undergone the same deformational history as the country rocks. The invariable association of the ores with spilites; the S isotope values and Co-Ni contents of the pyrites, together with the primitive metal assemblage (Fe, Cu, minor Zn) strongly favour a basic magmatic source for the sulfides. It is suggested-that the sulfides were probably precipitated sub aqueous- ly during a hiatus in volcanic activity. The O.K. deposit is of the cupreous pyrite variety, but unlike other well known occurrences of this type, it does not con- stitute part of an ophiolite complex. While the host volcanics exhibit strong ocean floor tholeiitic affinities, no associated ultra

Jan 1, 1978

The Research on Refined Gold Bullions Surface Upgrading

Sep 13, 2010

The ongoing need for improved fuel economy, longer engine life, reduced emissions and greater power output has driven the need for lower charge air temperatures. Cuamins will introduce a split loop, single water pump approach to low temperature aftercooling (LTA) in 1987 with the introduction of its 1492 kW (2000 BP) 16 cylinder K Series engine. The LTA system selection process considered performance, durability, fuel economy, and total engine installed cost. The split loop system selected takes full advantage of the engine cooling characteristics to provide optimum charge air temperatures at all speeds, loads and ambient temperatures. Computer simulations and engine tests were used to determine performance for each charge air cooling alternative. The split loop system chosen offers many advantages compared to the other alternative systems studied which included air-to-air and dual loop (two radiator, two water pump) systems.

Jan 1, 1986

By Hellsten KJ, Butt CRM

Major Francis Hamilton Buchanan coined the term `laterite' (Latin; brick-rock) in 1807 for the red earths used for building blocks in southern India. Although these earths were actually weathered basalts, the term is now applied to weathering profiles developed upon a wide range of bedrocks. The Ni-laterites are a special class within the broad laterite family.

Jan 1, 1996

By G Pitkin, D Sorley

The purpose of any consultancy is to provide a superior service for their client. Organisational structure is a key element in providing this service and differentiating between consultants.In an organic organisation the emphasis is on effectiveness, problem solving, responsiveness, flexibility, adaptability, creativity and innovation. Such an organisation is able to respond in a timely manner to change because employees are empowered to be creative, to experiment and to suggest new ideas. The process of innovation is triggered by employees throughout the organisation in a collaborative manner.Problem solving becomes a core competence of the consultancy. A multidisciplined approach arrives at superior solutions that are rigorous, holistic, achievable and often novel. It allows the mining consultancy to extract the most from a very talented and experienced team.This paper highlights the advantages of an organic structure for a mining consultancy and how to implement such a structure. It draws on examples of innovative problem solving from feasibility and strategic studies carried out in Australia and Africa.CITATION:Pitkin, G and Sorley, D, 2016. Organic management structure – its advantages in a mining consultancy, in Proceedings International Mine Management Conference, pp 155-162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By H Peiming, W Sakurai, Y Matsuhisa, H Shimazaki, Y Fukahori

Oxygen and carbon isotope mapping of hydrothermally altered wall rocks was applied to the blind ore prospecting of skarn Pb-Zn deposits in the Kamioka mining district, centralJapan, where the wall rocks consist of heterogeneous rock units. The results (d18OSMOW of -1.1 to +17.3ë and d13CPDB of -5.0 to +4.8ë for limestones, and d18OSMOW of -0.8 to +12.5ë for silicate rocks) show isotope zonations of the wall rocks with depletions in heavy isotopes (18O and 13C) toward the centre of mineralization. The isotope zonations likely formed by interaction of migrating thermal waters with the wall rocks during the mineralisation. The heavy-isotope depleted zone, which indicates higher temperature or higher water-to-rock ratio of the system, occurs in the footwall of a fault, indicating that the fault played the role of main conduit of the ore-forming fluids. A heavy-isotope depleted zone was also found in an area, where significant mineralisation had yet to be identified. Recent drilling in this area has intercepted a zone with a grade of 16.0% Zn, 0.8% Pb, and 35g Ag per metric tonne at a depth of about 360 m.

Jan 1, 1995

By J L. Carpenter, S M. Iveson, K P. Galvin

Wet beneficiation of iron ore fines less than 1 mm typically involves a desliming stage ahead of the fine gravity separation such as spirals. The desliming is achieved using a bank of cyclones. The reject ultra-fines emerge in the overflow stream at relatively low pulp density, contain high proportions of low-value slimes, but also well-liberated iron ore ultra-fines below 0.045 mm in size; however, recovering the valuable iron ore ultra-fines from this overflow stream presents a significant challenge due to the need to remove such a large amount of water and slimes.The REFLUX™ Graviton consists of distinct 3D-printed modular units, based on REFLUX™ Classifiers, which are rotated at high speed in a large centrifuge. This system has previously been investigated under semi-batch conditions, demonstrating the potential for precision separations with significant capacity. It has been shown that the throughput advantage of the inclined channels and G forces multiply. This is the first paper presented showing the performance of this system under continuous steady-state conditions. Ultra-fine silica in the size range of 0 to 0.045 mm was fed to the Graviton at different volumetric rates, fluidisation rates and pulp densities ranging from 2 wt per cent to 30 wt per cent, in order to develop a fundamental understanding of the system’s performance. Experiments were then repeated using ultra-fine iron ore.CITATION:Carpenter, J L, Iveson, S M and Galvin, K P, 2017. Separation of ultra-fine particles using the REFLUX™ Graviton, in Proceedings Iron Ore 2017, pp 141–148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

There is a significant amount of historical mining and exploration information available. This information is often distributed throughout a number of reports or plans, available from a variety of sources, and in many differing formats. The ability to capture paper-based historical information in a modem digital format provides mining and exploration companies with valuable information that can be used in a number of ways; for example, reassessments of exploration or mining work previously undertaken, or used in conjunction with current exploration information.   The purpose of this paper is threefold. Firstly, to present the paper-based historical information; highlighting some of the problems encountered, solutions to those problems, and any assumptions used. Secondly, to present the historical data in digital format, and demonstrate the tools available to analyse geological and associated information, and finally, to illustrate some of the potential future applications of the information, including mining optimisation, mine design and scheduling.   The Glenorchy scheelite/gold prospect has been used as an example. Within the overall prospect two smaller areas were selected. The Mount McIntosh and surrounding areas, focuses on exploration and surface excavation information. The Mount Judah area (State and Kelly-Taylor workings) focuses on underground mining and exploration information.  

Jan 1, 2001

By M Sykes

Gold was initially discovered at Ballarat in 1851. After initial alluvial mining, underground quartz mining commenced in 1853, continuing until 1918. The historic miners were considered to be capable of mining anywhere in the world after overcoming the difficult conditions within the Ballarat goldfields. Whilst mining has changed dramatically since the early 1900s the challenges with underground mining at Ballarat have not. Modern pumping systems cope with the moderate water inflows. However, modern machinery and efficient mining methods influence opening sizes and extraction techniques. In some cases modern techniques have accentuated the challenging ground conditions and complex orebodies that were faced by the historic miners. As the Ballarat East project has progressed towards production, technical challenges relating to geomechanics and mine planning are being resolved resourcefully.

Jan 1, 2008

By S W. Richards, J Buys

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Magmatic arcs are prime targets for porphyry- and epithermal-style mineral deposits, although settings within continental arcs and/or tectonically-thickened crust generally tend to be more prospective than intra-oceanic arcs in extensional settings. In this paper, we report new geochemical and geochronological data on igneous rocks of the Western Belt of the Vanuatu intra-oceanic arc. Dating of igneous hornblende (Ar-Ar) and zircon (U-Pb) from the igneous rocks place their formation in the late Eocene to Miocene. In most respects, these are typical arc igneous rocks. However, they contain inherited zircon grains with significant age populations at ca 2.8–2.5 Ga, 2.0–1.8 Ga, 1.75–1.5 Ga, 850–700 Ma, 530–430 Ma and 330–220 Ma. This inheritance signature is unlike anything recognised from the oceanic realm of the south-west Pacific, but, in general, does match the age of the major crustal blocks of the Australian continent. An exception is the significant proportion (~20 per cent) of zircons of Rodinia breakup age (~800 Ma), which previously has not been found in eastern Australia or the south-west Pacific.We propose that part of the Vanuatu arc basement comprises a ribbon of continental material rifted from northern Australia prior to, or during, the Cretaceous. The presence of ancient continental material within the Vanuatu island arc may help reconcile the relatively large thickness and low density of the crust of Vanuatu, and may enhance the prospects for significant porphyry and epithermal ore deposits in the region.CITATION:Spandler, C, Buys, J, Holm, R J and Richards, S W, 2015. Remnants of ancient Australia in Vanuatu – implications for south-west Pacific tectonics and mineralisation potential, in Proceedings PACRIM 2015 Congress, pp 183–188 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The exploration and mining risks are investigated and compared to the risks of smelting, secondary processing and other normal industrial activities. This study concentrates on the risk before, or at the investment decision. Internal and external risks are distinguished. Internal risks are the risks inherent in every engineering design and common to all projects. The main external risks are the financial risk, changes in prices, location problems and geological factors. Financial risks concern every capital-intensive and export-oriented project and cannot be considered as typical mining risks. Changes in prices, i.e. the market risk, concern every industry using raw materials, but the market risk is especially accentuated in the mining industry. Problems of location and infrastructure are normally more significant in mining than in other projects, and geological risks are unique to mining. All these risks associated with mining projects combine to form a risk at least twice as high as that for other normal industrial activities. Within the range of profitability of mines, which on average is the same as in the manufacturing industry, only a few highly profitable mines exist. These few mines are the sole reward for the high risks taken.

Jan 1, 1986