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By Knasmillner

During blasting body wave interaction with geometrical surfaces induces Rayleigh-waves which propagate along free surfaces, e.g. crack faces or delaminated rock layers. These Rayleigh-waves carry most of their energy within a very shallow surface layer and propagate with very little attenuation in real rock materials. Upon interaction with a crack front a very strong mixed mode stress intensity factor may result and lead to fracture initiation. On the basis of experimental photomechanical results the history of dynamic stress intensity factors Kt and K2 will be studied in Detail.

Jan 1, 1990

The Devonian Mount Morgan gold-copper deposit was situated on the western margin of the Calliope Volcanic Are assemblage, in the northern New England Orogen. Recorded production from commencement of mining in 1882 to mine closure in 1989 stand

Jan 1, 1994

By Etheride MA

The evolution of economic precious metal and copper-gold deposits in high-level igneous terranes is dependent on very efficient fluid focussing. This is most readily achieved by contemporaneous deformation, igneous intrusion and hydrothermal activity. Mineralisation in these environments generally occurs in fault and fault-vein arrays developed in the cover sedimentary and volcanics sequences above older regional scale fault systems. Such reactivated fault systems an particularly prone to developing the complex fracture arrays, extreme local dilation and dramatic increases in permcahilit} that are necessary to efficiently focus hydrothermal fluid and produce large mineral deposits.

Jan 1, 1995

The winning and upgrading of mineral raw materials necessarily includes size reduction, which serves the liberation and production of marketable products from highly valuable and bulk materials. For crushing, the following factors can be duly accounted for depending on material type and the selection of the suitable machine: ò producing a particular size distribution, ò producing a particular grain shape, ò selective comminution, ò gentle comminution, and ò producing a size range required by a specific process and/or for a specific product.

Jan 1, 1993

By Stewart WJ

Australia's first offshsore well was spudded in on 27th December 1964 and resulted in the discovery of the Barracouta gas field. Further exploratory drilling led to the discovery of the Marlin gas field in December 1965, the Kingfish oil field in April 1967 and the Hblibut oil field in June. 1967. In September 1968, a small oil reservoir was found in a sand below the main Barracouta'gas reservoir. The Snapper gas field was discovered in May, 1968 Information on exploration activities associated with the discovery of oil and gas in the Bass Strait area may be found in the paper, "Exploration in the Gippsland, Bass and Otway Basins, Australia" by B. M. Hopkins. _ Development of the commercial fields is being undertaken on an equal participation basis by Hematite Petroleum Pty. Ltd. and Esso Exploration and Production Australia Inc. Esso Standard Oil (Australia) Ltd. is responsible for the design, construction and operation of the production facilities.

Jan 1, 1970

Gold at Renco occurs in association with pyrite, pyrrhotite, chalcopyrite and quartz and is confined to a series of brittle fractures and fault breccias (reefs) preferentially developed within an anastomosing ductile shear zone. During late Archaean crustal movements both the orebody and the enclosing host rocks were deformed within a series of east-north-east striking, southerly dipping, shear zones. The reefs within these shear zones are now texturally different to those away from the shear zones, and this difference is reflected by differences in the way the gold is distributed in the two reef types. These differences are not taken irto account by the software package currently being used to generate kriged plans of gold grade and reef thickness and this may explain some of the inaccuracies found in these plans.

Jan 1, 1990

Geological hazards such as faulting, basement ridges, and zones of "thin" (

Jan 1, 1998

By Myers I. A, Peters S. G, Bultitude R. J, Dowling K

Gold-quartz and antimony-gold-quartz veins in the Hodgkinson Province are hosted by subgreenschist to greenschist facies metasediments and show no spatial association with granitic rocks. They commonly parallel axial plane foliations or occur in brittle to brittle-ductile shear zones. Detailed mapping in the Hodgkinson goldfield indicates that vein systems are isolated in distinct structural and lithologic domains by post-mineralization faulting. Gold-quartz and antimony-gold-quartz veins have distinctive mesoscopic textures characteristic of the mesothermal vein environment. Some of the antimony-gold-quartz veins are located on domain boundaries which truncate the gold mineralization. In. some areas, tin and tungsten-tin mineralization which are spatially related to Late Palaeozoic granitoids appear to postdate the gold-quartz and antimony-gold-quartz mineralization.Oxygen and hydrogen isotopic studies of vein and alteration assemblages associated with these diverse ores provide constraints on fluid sources and have implications for the origin of mesothermal gold mineralization. The available isotopic data are consistent with a dominantly magmatic source for tin and tungsten-tin mineralization although there is evidence of a late-stage meteoric component in some tin-mineralizing systems. Although a distal magmatic contribution cannot be entirely discounted, the gold-quartz and antimony-gold-quartz veins were probably deposited from deeply

Jan 1, 1990

By Borshoff J, Coles R

The Rum Jungle Uranium Province is lo cated on the western margin of the Pine Creek Geosyncline approximately 60km south of Darwin. Uranium was discovered in the Embayment area (Whites Deposit) in 1949, spurring active ex- ploration and leading to the discovery of the Rum Jungle Creek South Deposit in 1959. With the discovery of the Alligator Rivers Uranium Field, new criteria in the understanding of the controls for mineralization sparked a re- surgence of exploration activities in the Rum Jungle area. Uranerz Australia Pty. Ltd. (UAL) commenced exploration in the area in the late 1970's in joint venture and in its own right. Two domal Archaean granitic complexes, the Rum Jungle and Waterhouse Complexes, domi- nate the area. They are unconformably mantled by Lower Proterozoic sediments metamorphosed to middle to upper greenschist grade. The Lower Proterozoic sediments are unconformably over- lain by remnant blocks of Carpentarian sand- stone, generally preserved in downfaulted blocks. Over a six year period extensive geolo- gical, geochemical and geophysical programs were conducted to reinvestigate previous target areas and locate new prospective zones. Exten- sive shallow bedrock drilling showed that lo- cally the stratigraphic succession is quite variable and cannot always be divided into an ordered succession for correlation with groups and formations established by the Bureau of Mineral Resources (BMR). Deformational events resulting in intraformational recumbent folding and overthrusting also account for repetition of certain lithotypes.

Jan 1, 1984

By Wright R, Stock E. C

The Windarra nickel deposits known to date comprise two sulphide orebodies located at Mount Windarra and South Windarra. These orebodies, which are 15 km apart, lie within an ultramafic complex at or near its footwall contact with a banded iron formation. The Windarra deposits are 270 km north-northeast of Kalgoorlie in West- ern Australia which was the centre of a major nickel exploration programme fol- lowing the discovery of nickel deposits at Kambalda in 1966. Surface indications of the Mount Windarra orebody were discovered in 1969 by Mr. Ken Shirley while prospect- ing the Laverton area for Poseidon Ltd. (then NL). The mineralisation was loc- ated by systematic prospecting for goss- anous material associated with aero-mag- netic anomalies and ultramafic rocks. The South Windarra deposit was dis- covered in 1971 by the Union-Hanna- Homestake Joint Venture, by exploring along the strike extension of the mount Windarra ultramafic-banded iron format- ion contact. A detailed ground magnet 1. Acting Operations Superintendent, Windarra Nickel Project, Windarra, W.A. 2. Senior Geologist, Windarra Nickel Project, Windarra, W.A. 3. Mine Geologist, Windarra Nickel Project, Windarra, W.A.

Jan 1, 1973

By Gregory L. M, Phillips G. N

Although it has long been recognised that there is a diversity of minerals associated with Victorian gold deposits, the degree to which this mineralogy is systematic or haphazard has remained uncertain. Recent work by the authors and students under their supervision permits a sharp delineation of the boundaries between different mineralogical domains, and these are interpreted in terms of recent rapid advances in Victorian tectonics, and the regional framework of Victorian gold geology described in Phillips and Hughes (1996).

Jan 1, 1997

By Bloom M. S

Epithermal vein and breccia hosted Au mineralisation at the Kerimenge prospect, in the Wau district, Papua New Guinea, occurs within a block of multiply fractured dacite porphyry of Pliocene age, and is localised on intersecting regional fault structures, marginal to the eroded vent of a Late Pliocene-Pleistocene maar volcano (diatreme).Au mineralisation is primarily controlled by the steeply dipping Kerimenge Fault zone, which hosts a basal zone of silicified breccias,transitional laterally and vertically to networks of fracture controlled veins.Early quartz+pyrite veins, deposited from CO2 rich, NaCl saturated, boiling fluids pre-date the main phase of Au mineralisation. Four stages of Au bearing vein mineralisation have beenrecognised. Quartz+sulphide veins (stage 1) and partially coeval quartz+sulphide+carbonate+ adularia veins (stage 2) occur marginal to silicified breccias, and are associated with quartz+sericite+pyrite wallrock alteration. Similar depositional conditions prevailed for stage 1 and stage 2 mineralisation. Mineralising fluids underwent two stage boiling at temperatures of 145 to 2300 C. Boiling resulted in the loss of approximately 3 wt.% CO to the vapour phase. 2 Fluid salinity was probably I wt.% NaCl or less.

Jan 1, 1990

By S H. Algie, E J. Knoblauch, I A. Lovatt, S G. Doig

Mill operating teams are expected to engage in a perpetual quest for process improvement – pushing the boundaries of practical process limits and testing new technology to achieve the next step-change in plant performance. Often the barrier to improvement lies in gaining management approval for process changes.Getting approval for investment in novel technology carries an added degree of difficulty, particularly in risk-averse operations, when it challenges conventional wisdom. A case in point is a new technology for controlling variability in slurry distribution. There is a widely held view that less-than-specified classification efficiency and spraying and roping of individual units in a hydrocyclone cluster, must be accepted as unavoidable. That these are wholly correctable deficiencies resulting from unequal loading of the individual units seems a bold claim. Wouldn’t the high turbulence of pumped slurries overcome all potential for segregation of solids? This paper discusses how the task of developing confidence in a new technology can be approached by a combination of physical modelling at small scale, and full-scale operating experience. Proving efficacy then leads to the next task: demonstrating value. Again, the particular technology serves as an example that could be of value to others developing relatively low-cost technologies. A high-pay-off as an investment may be achieved with improvements in metallurgical performance that are small in relation to normal process variations. This has led to an exploration of how process simulation modelling could be used, in conjunction with production data, to provide a benchmark for the expected change, which could be expressed in monetary terms.The next goal, which is currently being achieved in operating plants, is to realise the greater value now available through the optimisation of cyclone configuration, which becomes practical when the confounding effects of cluster instability are removed through equal loading.CITATION:Doig, S G, Algie, S H, Lovatt, I A and Knoblauch, E J, 2018. Investing in new process improvement technology: reducing the risk of implementation – a way forward, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 571–584 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Perring CS, Vearncombe J. R, Ho SE, Groves DI

Large Late Archaean greenstone belts in Western Australia, Canada and Zimbabwe, contain abundant mesothermal gold, volcanogenic massive base-metal sulphide, and komatiite-associated Ni-Cu mineralization. These greenstone belts are similar in many respects to convergent and accretionary plate margins found in the Pacific rim; modem environments which are cor-respondingly rich in gold and base-metal mineralization. The giant gold placer deposits of the Late Archaean Witwatersrand Basin (the world's largest gold producer) formed in a foreland or retro-arc basin; in a similar tectonic setting to much modem placer mineralization around the Pacific. Gold and volcanogenic base-metal sulphide mineralization are abundant in Late Archaean terranes and the Pacific rim because1. gold mineralization is a product of convergent margin tectonics, and 2. accretion in convergent margin orogens provides the best chance of preserving base-metal mineralization related to submarine volcanism.It is therefore likely that the abundance of gold and base-metal sulphide mineralization in the Late Archaean reflects the widespread growth and sta-bilization of continental crust via tectonic processes broadly similar to those operating in the present Pacific basin.

Jan 1, 1990

By Coombes J, Richards W. L

The objective of this paper is to illustrate, in a practical way, how both geologists and mining engineers can use conditional simulation to add value to their decisions. Inherent assumptions, requirements and essential components of condition

Jan 1, 1998

By Duncan GR

Having passed through a number of previous phases the best longwall results in Australia have shown a significant increase in the last two years. The results expected from a longwall face can be estimated from the ideal production rate, determined by the capacity of the equipment and the conditions in which it is installed, the utilisation, and the available operating hours. Back analysis of the results achieved suggests that, on average, recent improvements arise from the higher capacity equipment recently installed; the utilisation has in fact reduced slightly. Review of the constraints which limit the longwall results, i.e. shearer speed, AFC capacity, support, advance rate, and man travel speed, shows that little improvement can be expected in the ideal production rate in thinner seams. In thicker seams the AFC often proves the overriding constraint and further increase in equipment size could lead to increased future ideal production rates and is expected. In all cases a concerted effort to increase the utilisation achieved is likely. For deep mines with thin to medium seams this offers the most viable path to improvement; by contrast thick seams with highwall/shallow access may benefit from further increase in equipment size.

Jan 1, 1988

By Erceg MM

The Waft River gold deposit is hosted by low grade metasediments which have been intruded by a dacite/andesite porphyry complex. Wafi River is classified as a high sulphur, epithermal type gold deposit having: a high sulphur content, a close association with calc-alkalic igneous rocks, zoned advanced argillic and argillic alteration, and enargite group minerals. Gold occurs as minute inclusions in pyrite and pyrrhotite within intermediate dickite/kaohnite - interlayered illitic clay alteration zones. Central leached silicic, alunite and pyrophyllite zones and peripheral chloritic zones are low in gold. The gold mineralisation at Wafi is interpreted to have been predominantly caused by mixing of hot upwelling acidic magmatic mineralised fluids with cool, neutral meteoric/hydrothermal fluids within permeable sediments. Locallised high grade breccia zones are encountered within the porphyry. An initial resource in excess of I million ounces Au has been defined.

Jan 1, 1990

The evolution of Hall process alumina reduction technology is des- cribed with particular attention to the pot lines. Future directions of tech- nological change are considered. It is predicted that the Hall process will continue to be the avenue for aluminium production for some time to come.

Jan 1, 1982

By Howarth W. J, Sowerby B. D, Watt J. S

On-line analysis systems have found widespread application in the metalliferous mineral and coal industries. The continuous analysis and rapid response of these systems has led to improved control of mining, processing and blending operations, with increased recovery of valuable minerals and coal combustibles.The paper reviews developments in on-line analysis by CSIRO and Mineral Control Instrumentation Ltd which led to the award of the Australia Prize 1992. These commercialised systems analyse mineral and coal slurries; determine the ash and moisture contents of coal on conveyors, and the moisture content of coke on conveyors; and determine the carbon content of fly ash. These gauges are estimated to have resulted in productivity increases valued at $50 million per year to Australia.

Jan 1, 1993

By Peters S. G, Beams S. D

CONCEPTS AND REGIONAL GEOLOGY The Charters Towers region holds many keys to the metallogeny associated with the complex geological development of eastern Australia during the Palaeozoic. Tectonic, magmatic and volcano-sedimentary depositional episodes can be identified and related to the chronological development of batholithic host rocks (Clarke & Paine, 1970; Henderson, 1986; Murray, 1986). Pre-batholithic basement rocks in the north (Charters Towers Metamorphics) consist of a package of amphibolite grade schists interlayered with and intruded by gabbros and diorites (Peters, 1987). To the south (Seventy Mile Range Group) greenschist facies Cambro-Ordovician rocks overly some of the basement. The lower age of this basement is not constrained, parts of it could be as old as Pre-Cambrian. Mid-Ordovician (approx. 470 my) to Lower Devonian (approx. 400 my) age I-Type granitoid plutons of the composite Ravenswood batholith intrude the pre-batholith basement and the Seventy Mile Range Group. Igneous activity was initiated again in the Carboniferous with the extrusion of rhyolitic lavas and pyroclastics associated with porphyry and high-level intrusive complexes (Wyatt et al., 1971). The Ravenswood block is bounded by Devonian and Tertiary sedimentary sequences of mainly continental provenence.

Jan 1, 1989