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By Hagarty KA

At the northern margin of New Guinea there is a fundamental problem related to the relative timing of arc- continent collision(s) represented in the Papuan Fold-Belt (PFB) and backarc spreading in the Caroline basins. New fission track dates from basement and sediments within major anticlines of the PFB indicate that uplift occurred at 4.0 ¦ 0.5 Ma. The timing is consistent with the fold and thrust shortening (more than 100 km) of the PFB which occurred in the Late Miocene/Early Pliocene as evidenced by the deformed Miocene carbonates and Pliocene molasse deposits. However, in northern Papua New Guinea, earlier work has suggested that ophiolite emplacement and associated metamorphism occurred in the late Oligocene/early Miocene.The evidence suggests that the late Miocene/early Pliocene deformation was of considerably greater magnitude than the earlier obduction event. The Caroline Plate lying north of New Guinea has been interpreted as a backarc basin which commenced spreading in the Eocene and ceased spreading in the Late Oligocene (about 28 Ma). The remnant arc presently docked to New Guinea was active in the Eocene and Oligocene and is believed to be the arc related to the formation of the Caroline Plate. The cessation of spreading of the Caroline Plate has previously been interpreted to be due to arc continent collision during the Late Oligocene/Early Miocene, but such a collision is now known not to have occurred. In the Cretaceous and Palaeocene subduction was to the south beneath New Guinea, but "flipped" in the Eocene to give a north-dipping subduction zone far to the north of New Guinea, driving Caroline Plate backarc extension. This backarc basin reached a limiting size at about 28 Ma resulting in the end of subduction. With the continued northward movement of Australia, Mesozoic oceanic crust was obducted southward onto the New Guinea margin in the Late Oligocene/Early Miocene. In the Miocene south-dipping subduction beneath New Guinea commenced until the now extinct Caroline Plate arc collided with New Guinea in the Early Pliocene, causing extensive regional compression and sinistral strike-slip faulting. This new tectonic framework suggests that backarc basins reach a limiting ridge-trench distance of 1000-1500 knm, beyond which "subduction-pull" cannot drive further spreading so subduction and spreading are terminated.

Jan 1, 1987

By W A. Peppin, D N. Riley, N W. Schulenburg

In June 2008, a joint airborne collection using hyperpspectral systems was tested on a single Twin Otter aircraft. This experiment was designed to incorporate two airborne hyperspectral sensors for geological and environmental projects. Mineral exploration and environmental impact statements are two areas where full spectrum hyperspectral data can document the mineralogy at the surface prior to mining operations. Many previous hyperspectral remote sensing collections were collected on a single aircraft with a single sensor. Mineral mapping using hyperspectral sensors that measure in complimentary regions of the electromagnetic spectrum is cost effective as it allows for the mapping of clays, sulfates, carbonates, feldspars, quartz, garnets and many other minerals. This report describes the experiment using the following two hyperspectral sensors: ProspecTIR, a visible near and shortwave infrared (VNIR-SWIR) sensor with 356 channels and spectral range of 0.4 to 2.5 ¦m, along with a spatially enhanced broadband array spectrograph system (SEBASS), a midwave and longwave infrared (MWIR-LWIR) sensor with 128 channels from 2.5 to 5.3 ¦m and 128 channels from 7.6 to 13.5 ¦m. SpecTIRÆs ProspecTIR system and The Aerospace CorporationÆs Spatially Enhanced Broadband Array Spectrograph System (SEBASS) are pushbroom sensors, have high signal to noise ratios, have similar swath widths and instantaneous fields of view. Examples of data collection experiment will be shown with a focus on mineral/lithologic identification and mapping along with environmental assessment in the western United States. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Rogis J

The basic parameters causing outbursts are rock pressure, gas characteristics and the physico-mechanical properties of the coal. The three sets of factors are to some degree interdependent. At Collinsville, the gas characteristics coupled with the physico-mechanical properties of the coal appear to be the major factors contributing to outbursts. The relative importance of rock pressure is uncertain. The following geological parameters appear to be necessary before outbursts can occur. 1. A coal rank greater than 1.2% vitrinite reflectance. 2. Thrust faults with throws greater than 3.Om or strike- slip faults with coal gouge wider than 0.3m. 3. Seam gas emission values greater than 1.1 cm3 /g. Igneous intrusions are the likely source of the carbon dioxide seam gas. Outbursts have occurred at depths ranging from 215m to 265m. They occur at these relatively shallow depths due to: 1. the high rank of coal at the present topographic surface and the high coalification gradient; 2. the relatively high degree of tectonic deformation of the strata; 3. the seam gas characteristics; and 4. the extent of igneous intrusions.

Jan 1, 1980

The advantages of coordinate geometry in design and construction of underground works are apparent for reasons of flexibility, security, computer operations, survey error analysis, and the use of numerical techniques for setting out and checking works. Integration with National or State survey systems is useful in the long term, both at design, construction and future works stage. Equipment and methods are available which permit "absolute" monitoring of structures and strata over long periods,to close toler- ances. This work can be carried out in the limiting urban environment. Rapid data acquisition by semi-automatic devices, or photogrammetry, utilizing electronic data processing is capital inten- sive, but provides more data than analogue surveys (i.e., setting out centre lines) and becomes more attractive with increased labour Costs.

Jan 1, 1976

By R Williams, P Godwin

In a time of changing rainfall patterns and in the light of recent tailings dam failures, there is closer environmental scrutiny for proposed tailings dam construction or expansion. Therefore the elimination of the traditional tailings dam could provide both environmental and cost benefits to an operation. One method to dewater tails is using pressure filtration to achieve lower moistures than what is currently available using other dewatering technologies. Further benefits include a higher rate of filtrate recovery, reuse of waste material and the potential for dry stacking of the filtered tailings cake, thereby minimising both risk and cost. This paper chronicles the replacement of two existing belt filter presses with a single McLanahan recessed plate filter press to dewater a tailings stream at a Bacchus Marsh site. It covers the slurry testing, equipment selection, installation, commissioning and operation of the filter press to achieve the following objectives:• removing the current tailings dam and slimes cells from the existing process to minimise failure risk and reduce the cost of a dam upgrade, as well as operational and maintenance costs• free up the surface area which was previously occupied by tailings dams and slimes cells• recover additional water to be returned to the process• reduce flocculent usage• reduce truck movements and handling.The project’s owner also expects to reduce carbon emissions by over 3000 t over the lifetime of operation as well as substantially reducing operating expenditure. By recognising the carbon reduction benefits, the project owner was able to successfully achieve partial funding through the Voluntary Waste Industry Protocol.An unanticipated, but as yet unquantifiable, bonus for the project was to seek an offtake agreement for the tailings thereby allowing the tailings to be considered a valuable source of beneficiated clay suitable for the construction industry.CITATION:Godwin, P and Williams, R, 2017. Pressure filtered tailings – environmental and cost benefits, in Proceedings MetPlant 2017, pp 324–334 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By C Mann, S Swapp

"The mining industry is often challenged with the task of evaluating narrow vein open pit deposits. A realistic mineable solution from optimisation needs to accurately represent mining dilution and the practical limitations of mining equipment. Open pit dilution is driven according to mining method and fleet selection as this dictates the ‘selective mining unit’ (SMU) that can be practicably mined.Common evaluation methods represent dilution by:a mathematical dilution assumption addition of a dilution skin reblocking of the model to an appropriate SMU.This paper will explore an alternative method of applying dilution by adapting an underground stope modelling tool. By considering an SMU as a stope, automatic stope shape creators such as Datamine’s Mineable Shape Optimiser (MSO) can be used to create wireframes for each mining unit over the entire deposit. Using these wireframes, the model can be subblocked and assigned as either ore (inside the wireframe) or waste (outside the wireframe) prior to optimisation.The MSO process considers SMU geometry and a depth specific value-based cut-off. The result is an optimised solution for the deposit based on practical and achievable mining constraints rather than one based on generalised modifying factors.To evaluate the economic impact of the methods above, results have been costed and scheduled and a comparison of operating cash flows made.Citation:Swapp, S and Mann, C, 2016. Optimisation Improvements for Narrow Vein Open Pit Deposits Using Mineable Shape Optimiser, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 50–59 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By King R. L

The Bureau of Mines has developed and deployed three expert systems to give advice on mining health and safety. These are: dust control for continuous miners, dust control for longwall shearers, and methane control. All three systems query about the nature and extent of the problem. Typical questions asked deal with observed methane levels, ventilation type and quantity, cutting sequence, and what control technology is employed. Advice given does not focus on a single issue, but may suggest a variety of approaches consistent with the ability of the operator to implement the Suggestions.

Jan 1, 1988

By E Mroczek, M Climo, B Carey, M P. Simpson

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The composition and volume of geothermal fluids in New Zealand offers considerable potential for the extraction of various metals and minerals, as well as being a source of heat energy, steam and gases, and for use in generating electricity. While extracting products from geothermal fluids is technically feasible, positive economics is the key driver for commercial success; however, there is no assessment of this opportunity that identifies simple, cost-effective processing technologies and provides a greater understanding of the economic viability and barriers for implementing such technologies. The methodology that will be used to evaluate the commercial opportunities for New Zealand is discussed.CITATION:Mroczek, E, Simpson, M P, Climo, M and Carey, B, 2015. From waste to wealth – mineral extraction from geothermal brines, in Proceedings PACRIM 2015 Congress, pp 133–138 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Underground measurements, observations and computed simulations, started a long time ago were concerning the study of : - occurence of typical rockburst, - inducing, stretching of main fractures in the roof of caved longwalls. They made obvious a foundamental phenomenon of inducing of strata fractures involving contact be- tween two layers quite different in their elastic characteristics : coalseam and rocklayer.. The start of primary cracks in maximum abutment zone takes place in the rock near the contact surface. It is opening of crevasses induced by traction stress component resulting of difference of rigidity of both materials and no sliding on in- terface. Occurence and stretching of these crevas- ses are a rheological phenomenon so that the rate of advance and stops of the face influence the distance between the crevasses and the stretching of these ones. The characteristics of these cracks in space and time affect mining conditions. So it is for fractures proximity and expan- sion inducing eventual blocks formation in longwall roofs in front of faces, for depth and delay of road- ways ribsides fracturing, inducing some rockbursts. In longwalls roofs, cracks initiated in front of a face can be either quite close or quite distant each from the other one, according to the depth of crushed coal in front of the face, which af- fects also extension of the cracks.

Jan 1, 1988

By J J. Cilliers, K Hadler, A W. Stra

This paper examines the use of the FrothSim flotation simulator to improve the performance of an industrial column flotation cell. The performance of an industrial retreat column cell is simulated, and, from the discrepancies between the simulated and experimental results, a problem with the wash water distribution is postulated. The scientific reason for the reduced performance with uneven wash water addition is described in detail. Further simulations indicated the potential for improvement with an even wash water distribution, resulting in both improved performance and reduced wash water usage. The simulated uneven wash water distribution was confirmed industrially, and the headers were redesigned and installed. A sampling campaign to compare the performance before and after the modifications showed that the flotation performance was improved dramatically, with a statistically significant decrease in gangue recovery, without a commensurate reduction in valuable mineral recovery.

Jan 1, 2005

By C Hamilton

Stawell Gold Mines (SGM) is an underground mining operation located in Victoria, Australia. The mining method employed is long hole retreat stoping, utilising up and downholes and artificial concrete pillars. Stawell is currently mining the Golden Gift and Magdala orebodies.Access to the Magdala and Golden Gift deposits is via 6.0 m wide by 5.5 m high declines developed at a gradient of one in eight to one in seven from the surface to a depth of 1500 m, with a planned depth of 1650 m. From the declines, cross cutting drives are developed to intersect the orebodies. Orebodies in the Gift system are discrete lodes which are generally mined from a bottom up centre retreat to minimise geotechnical stresses.Ore development fronts are currently located between 1000 m and 1500 m below surface, with all ore being hauled to the surface using a fleet of 60 tonne underground trucks. With the use of conventional pyrotechnic long period (LP) delays, broken rock of combined ore and waste is thrown 10 m from the face and the materials hauled to the surface. The majority of the mullock from development is consumed in the underground as backfill.With the use of Orica Mining Services eDev™ Electronic Blasting System for Tunnelling, the waste is thrown up to 40 m from the face, while majority of the ore is left 5 - 10 m from the face, effectively segregating ore and waste. This enables significant recovery of gold values with minimal loss and significantly reduced dilution. By using this technique in ore drives with a 30:70 waste to ore ratio, SGM is able to haul 24 000 tonnes less mullock to the surface annually. Resue mining is applied to narrow vein headings and gives a 40 per cent grade increase at the faces as well as increasing the economic footprint of development. This will also contribute to an improved grade profile for the year from 3.98 - 4.16 g/t Au and allow extra capacity for ore haulage from stoping and for milling.This paper describes the application and the successful blast outcomes achieved using the eDev™ Electronic Blasting Systems for resue mining at SGM. Results to date, since commencement in March 2010, have been achieving significant benefits in terms of ore grade as confirmed by geologists grab sample grades. Face advance have also shown improvement with better breakage of perimeter holes giving improved face profile. These benefits are delivering increased productivity and safety performance when compared to other resue firing techniques.

Mar 21, 2011

By S Meffre, S Golding, K Zaw, J McPhie, R James, S Suphananthi

The Chatree deposit is located in the central portion of Loei Fold Belt, which extends from Lao PDR in the north through centralThailand to Cambodia in the south. Epithermal gold-silver mineralisation at Chatree occurs as veins/veinlets and stockworks with minor breccia in volcaniclastic and volcano-sedimentary rocks of andesitic to basaltic andesite composition and Permo-Triassic age. This preliminary oxygen isotope study mainly focuses on vein quartz of Au-Ag bearing mineralization (Stage 2) and a few samples of late Stage 4 quartz ¦ calcite veins. Quartz from Au-Ag bearing mineralisation has oxygen isotope values ranging from 8.1 to 12.3ë with the lowest values generally occurring at the deeper level (140 m below the surface). The late barren quartz ¦ calcite veins (Stage 4) tend to have higher oxygen isotope values ranging from 11.9 to 12.0ë. The oxygen isotope composition of the Chatree ore fluids were calculated at 250¦C, 300¦C and 350¦C based on homogenisation temperatures of fluid inclusions. The calculated oxygen isotopic composition of the Chatree ore fluid ranges between -1 and 6ë that overlaps with both meteoric and magmatic compositions. This shift in oxygen isotope compositions may relate to processes such as water rock-interaction and/or mixing of meteoric and magmatic fluids. It is interesting to note that the lowest quartz oxygen isotope values are spatially more or less confined to the prominent structures in the centre of the major ore zones. These structures may have been acted as conduits for higher temperature magmatic fluids. The quartz oxygen isotope values increase outwards from the centre of the main ore zones to the margin of the pits possibly due to mixing of magmatic fluids with lower temperature meteoric water. Whole rock oxygen and hydrogen isotope studies are in progress to investigate isotopic trends in the wall rock away from the ore zone. The systematic variation of oxygen isotopes in quartz from the mineralised veins and adjacent wall rocks could potentially be used as a vector to ore. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Nickel ores from three different mines, Digger Rocks, Cosmic Boy and Flying Fox, are treated at the Forrestania concentration plant. The ore types vary from oxidised supergene ores to primary pyrrhotite+pentlandite ores. Mineralogical investigations on the ore and process samples have been carried out in different stages of process development. One of the studies was done with the samples collected from the flotation circuit in 19 June 1994 when the Cosmic Boy ore was processed. The process products were screened, and the size fractions were analysed for the main elements by appropriate analytical methods. Mineralogy of the products was studied microscopically and composition of the sulphides was analysed with an electron microprobe. Liberation of the main sulphides in the flotation feed was determined with the point-counting method, and weight percentages of the minerals were calculated using chemical and mineralogical data. The typical sulphide assemblage of the Cosmic Boy ore is violarite, pentlandite, pyrite, pyrrhotite and chalcopyrite. Violarite dominates over pentlandite (ratio being 70 per cent to 30 per cent), and pyrrhotite is strongly replaced with pyrite and magnetite. One of the most common mineralogical features of this ore type is secondary magnetite, which occurs as narrow rims in porous violarite or in association with secondary pyrite. Serpentine, talc and chlorite are the main gangue minerals. In the milled feed (76 per cent -74 ¦m) locked particles between nickel and iron sulphides are common. About 41 per cent of total pentlandite occurs as pure liberated particles, and 33 per cent as locked grains with violarite. Liberation degree of violarite is 55 per cent, and the most common type of locked particles is violarite+magnetite, carrying about 20 per cent of total violarite. To achieve a recovery of 80 per cent for pentlandite, all the particles containing at least 50 vol-% pentlandite should be floated into the nickel concentrate. Correspondingly recovery of 80 per cent can be reached for violarite if all the particles containing at least 65 vol-% violarite are floated.

Jan 1, 1996

A small-charge rock excavation method based upon the Penetrating Cone Fracture (PCF) technique has been demonstrated to be capable of excavating the hardest of rocks. The PCF technique involves drilling shallow holes in the rock which are then pressurised at the bottom by a propellant charge device. A controlled fracture is initiated at the hole bottom comer and propagates in such a manner as to excavate the rock at an energy efficiency three to five times better than explosives. Due to the low flyrock velocities and airblast pressures realised with PCF breakage, the method may be used in close proximity to equipment and personnel and is thus ideally suited for integration into continuous hard rock excavation systems. Over the past 18 months full-scale testing of the PCF method has been carried out in mines in the US and Australia. This testing has utilised a 76 mm diameter gas injector for hole pressurisation and employed propellant charges ranging from 80 to 320 gm. In addition to extensive data on rock excavation performance, data on ground motion, dust, carbon monoxide and air blast have been obtained. These data indicate that none of the parameters associated with PCF breakage are detrimental to the development of PCF-based, continuous-excavation machines. Machines employing the PCF method may range from simple single-boom machines for secondary breakage and small precision-blasting jobs to integrated systems with several booms, continuous mucking capabilities and ground-support equipment for drifting and tunnelling.

Jan 1, 1993

By N Green

The production of approximately 550 000 tonnes of æwhiteÆ or chrysotile asbestos fibre between 1972 and 1983 at the Woodsreef Mine in New South Wales left behind 24 million tonnes of tailings and 75 million tonnes of waste rock and overburden. The Woodsreef Magnesium Project is designed to extract the 23 per cent magnesium content of the tailings to produce magnesium metal and magnesium alloys, the latter with aluminium from the New South Wales smelters. Further value will be added to the tailings waste with the downstream production of magnesium alloy sheets and cast products for the transportation, electronics and other consumer goods industries. The mine opened in 1918 and closed in 1983 becoming derelict. There has been minimal expenditure on rehabilitation compared with that recommended in reports commissioned by the New South Wales Government. The tailings dump has been designated æasbestos wasteÆ by the EPA and will be eliminated through the magnesium refinery process of the Project with the dissolution of the remaining chrysotile fibres. The benign waste from the refinery process will consist principally of silica with some iron. Significant energy savings are expected from innovative new processing technology, in the alloy formation and in the application of the light weight, cast and sheet metal products, particularly in the transportation industries. Globally, there are very large resources of similar tailings with hundreds of years of useful productive lives that could be converted into the metal of the 21st Century, magnesium, and its alloys, to assist pollution and greenhouse gas reduction from transportation industries. No new mining and minimal feedstock preparation is required. Unlike potential producers using carbonate rocks such as magnesite and dolomite that have to be mined, the asbestos tailings composed principally of non-fibrous serpentinite do not contain any carbon dioxide.

Jan 1, 2002

When preparing an appraisal, valuation or feasibility study for a new mining project it is difficult to imagine the technical, economic, social and environmental context that the project will occupy in ten or 15 years time. This paper is about our ability to foresee the future, the choices available now in matching the project to that future context, and about the flexibility that exists in adapting the project to a changing environment. The author draws upon his experience of project reviews, valuations and feasibility studies in the mid to late 1980s in Australia and New Zealand to explore how the project context has changed since key decisions were made and what this tells us about decisions made today for future projects.

Jan 1, 2004

AustraliaÆs current interest in renewable energy is based on a desire to reduce the countryÆs greenhouse gas emissions. Wood from sustainable sources offers a unique opportunity to combine greenhouse gas benefits with other significant environmental and social benefits, including salinity mitigation, carbon sequestration, soil replenishment and rural industry. The challenge is to make renewable energy from wood in a cost competitive manner, so that this broad range of benefits may be best realised. Bioenergy and carbon products are of great interest as new, commercial forestry products that can drive large-scale environmental tree planting:In Western Australia, Enecon has worked with Western Power Corporation to build the first full-scale plant for integrated processing of mallee eucalypts, to produce activated carbon, renewable power and eucalyptus oil. It is intended that this plant is the first of a number of such plants to help catalyse environmental tree planting in Western Australia. New technologies being developed overseas may provide competitive bioenergy in areas where traditional markets for wood do not exist. For example, pyrolysis converts wood into a bio-oil that may be transported to remote sites for power generation in gas turbines. Pyrolysis also produces wood char. Pyrolysis and wood-to-ethanol technologies, coupled with short rotation coppicing trees, offer the long-term prospect of large-scale production of renewable fuels around the country.

Jan 1, 2006

Some fundamental aspects of recent single-particle fracture studies are reviewed. Findings from this research shed new light on the utilisation of energy during comminution operations and provide useful pointers to new research directions that could lead to significantly better comminution machines. Two methods for quantitatively predicting mineral liberation during comminution are reviewed. These methods have been developed into useful practical procedures, but they are almost unknown in the mineral processing community. Their use should promote the consideration of mineral liberation as an important variable to be considered during the design and operating control of comminution circuits.

Jan 1, 1993

The Mount Kasi gold deposit in Vanua Levu represents an epithermal, high sulphur, gold-enargite system occurring within a volcanic caldera of Middle to Upper Miocene age. High level breccia pipes flare upward and form flat lying, near surface, mushroom shaped sheets parallel and near to the present land surface. The upper portions of the pipes contain explosion breccias which are capped by sandy siliceous sinter-like beds and are cut by alunite veins. Outlying intercalated scoriasceous lavas and breccia sheets show evidence of subsidence within a shallow basin. Detailed mapping of breccia types, intensity of silicification and the presence of multiple quartz veining and enargite abundance outlined blocks of more consistent gold mineralization within the breccias. This work has provided a model for mineralization which will aid future exploration and ore reserve estimations. A significant eluvial concentration of gold occurs in soils overlying the breccia sheet.

Jan 1, 1987

By R B. Venugopal, P Staples

The selection of the mode of transport for moving bulk materials is never a simple task as there are various concerns/considerations applied to the selection of the most practical and cost-effective mode of transport to be used to move bulk materials. This paper examines various alternatives for moving ore from a mine at the top of a mountain to a process plant below (some 5000 m apart and a vertical drop of 650 m). The terrain of the mountain section of the route has added its own specific requirements, resulting in the final selection of a pipe conveyor for this application. The paper further addresses the final selection of hardware used in the implementation of the solution.

Jan 1, 2005