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The Beaconsfield Gold Mine within the township of Beaconsfield in northern Tasmania has been established in recent years to exploit a known resource in the Tasmania Reef which was mined to a depth of 450 m below surface between 1877 and 1914 yielding 850 000 ounces of gold. Activity at Beaconsfield over the past 30 years has involved drilling to assess the resource and rehabilitation of the top 100 m of the Hart Shaft that had collapsed since the original closure. More recently the mine has been dewatered to the 375 m Level and work is well advanced establishing infrastructure aimed at recommencing production during 1998 - 99. This paper reviews geotechnical studies undertaken to-date and provides a brief overview of some practical methods of analysing ground conditions. It pursues simple observation and analysis as a tool for assessing mine design and ground support options without recourse to extensive monitoring and measurement and avoids the use of elaborate models before the basics are understood.

Jan 1, 1997

By Patridge A. C

Observations of coal stockpiles subject to unusual levels of instability showed that the particular coals exhibited 'gap grading', a relative lack of intermediate size particles. This led to a suggestion that fine coal particles within the pile might have been induced to migrate under the influence of water flow and to concentrate in relatively impervious layers, resulting in local water saturation and reduction of shear strength. To investigate this suggestion, a large test column has been constructed and washed coals with various levels of fines content have been subjected to a downward flow of water. Subsequent examination of the bed of coal within the column confirmed the percolation of fines and their concentration into horizontal layers, and showed the development of zones of saturation above those layers. Shear box tests showed differences in cohesion and internal friction angle between coals with different percentages of fines, supporting the hypothesis that fines percolation may lead to decreased stability.

Jan 1, 1995

The Honeymoon Well nickel sulphide deposits are located in the Agnew-Wiluna greenstone belt, about 45 km south of Wiluna. Both disseminated and massive sulphide nickel deposits are hosted by komatiitic rocks within the deformed and metamorphosed Honeymoon Well ultramafic complex. Fresh ultramafic bedrock is covered by up to 50 m of highly conductive transported material which greatly hampers both exploration and understanding of the bedrock geology. In the early-1970s, mineralisation was discovered by diamond drilling geochemical anomalies defined by wide-spaced percussion drilling over ultramafics that had been outlined by ground magnetics. Subsequent drilling has defined a resource of 158 Mt at 0.71 per cent nickel (based on 0.4 per cent nickel cut-off, 300 m below surface, December 1995) in four deposits. Over the life of the project a wide range of geophysical techniques have been used including airborne and ground magnetics, time domain clectromagnetics (EM), induced polarisation (IP)/resistivity, gravity and downhole techniques including EM, IP and physical property Measurements.

Jan 1, 1996

By Hagan T. O

The problem of rockbursts presents a serious threat to many deep, hard-rock mines. For several decades, the owners and managers of affected mines have been concious of the urgent need to control rockbursts but, to a large extent, their efforts have been hampered by a lack of fundamental knowledge. This paper will attempt to outline the extent and depth of present understanding of the phenomenon and to show how better control may be achieved in the future. It is suggested that it is helpful to distinguish two aspects of the problem: that pertaining to the mechanism of the seismic event and that associated with the mechanism of damage. Understanding damage mechanism will enable development of better support techniques while proper understanding of the source mechanism could lead to better mine planning and improved stoping layouts. In this regard, the practice of partial extraction with systematic strike stabilising pillars is discussed in some detail.

Jan 1, 1986

The Lihir deposit in Papua New Guinea (PNG) contains an estimated mineable reserve of 454t (14.6M oz) of gold in refractory sulphide ore. The Lihir Joint Venture has submitted a proposal to the PNG Government to develop an open pit mine and to install a process plant and associated infrastructure facilities on Lihir Island. The proposed process plant will employ whole-ore pressure oxidation technology, has a design capacity of 2.825Mt/a of ore containing 7.20 sulphide sulphur, and is expected to average 19.3t/a (620,000 oz/a) in gold production during its first 12 years of operation.An extensive program of process development testwork and feasibility engineering was completed to establish the process plant design for the Lihir Project. Summary results of this test-work as well as key design criteria, the process flowsheet, and major equipment selected for the commercial plant are presented and discussed.

Jan 1, 1994

The Mt Whaleback open cut mine South Wall is, in part, developed as an unbenched dip slope. The remainder of the rock slope consists of asymetrical overturned folds which have been locally truncated by major low angle faults. The Mt Whaleback orebody is structurally controlled and therefore extensive structural geology input has gone into the final rock slope design. The design is based on normalised 40 m geological cross sections, but the inherent complexity of the geological structure of the orebody yields a high degree of uncertainty within that interval. There- fore, the final slope bench face and the penultimate bench faces are mapped in detail to accurately establish the geological contacts and struc- ture. The knowledge of accurate geology of final and penultimate faces plays a very important role in the design of controlled perimeter blast- ing. Accurate geology is established mainly by face mapping, and by hole geological evaluation of blastholes to locally refine the current Geologi- cal model.

Jan 1, 1989

By Weller K. R, Trahar W. J

The Mount Lyell Company treats some 2.3 million tonnes of ore annually, mined from a number of orebodies on the field. Blended ore is essentially a quartz-sericite schist containing about eight per cent of pyrite and three per cent of chalcopyrite. Four-stage crushing and two-stage ball milling are followe by selective flotation for copper. Pyrite is recovered from the coarse fraction of dopper circuit tailings. A detailed survey involving examination. of 82 samples provided information on the size- by-size behaviour of the principal ore constituents throughout the grinding, copper flotation and pyrite flotation sections of the circuit. Results for the copper and pyrite flotation sections are presented in the paper, and it is shown that over half the copper reporting to the final tailing (5% of copper in the feed) is plus 100 microns and that the major pyrite loss is in the desliming cyclone overflow. These data proVide a basis for assessing potential methods of circuit optimisation.

Jan 1, 1977

The mining of remnant coal reserves at the Liddell Open Cut is subject to a number of risks. These risks are of both a technical and financial nature. Liddell Open Cut is principally a conventional truck and shovel/loader operation, supplemented by a highwall coal augering operation. There are significant areas of divergence from more conventional operations including working in close proximity to a major dam, working up dip from an operating underground mine, and working through areas where there has previously been underground extraction. In addition the site has major long-term rehabilitation requirements. This paper, rather than concentrating on specific detail of areas of risk, presents the spectrum of geological, design, operational and post-mining risks that accrue to the various areas of activity in this open cut operation. The balance of this paper then provides an outline of the strategies employed by Liddell Coal to manage their potential impact.

Jan 1, 1994

By Manlapig EV, Davis JJ

A methodology for modelling dense medium cyclones is presented for cyclones operating under conditions which avoid particle interference or apex crowding. Particle interference and apex crowding are shown to result in less efficient separations and represent undesirable regimes of dense medium cyclone operation. In order to avoid apex crowding, suitable medium to ore ratios and apex diameters should be used. Cyclone density differentials should be kept below approximately 400kg.m 3 to limit loss of efficiency due to excessive particle recirculation within the cyclone. The relationship between size-by-size partition curves shows that the flow split and density of the medium within a cyclone can be related to two new parameters, the pivot partition number and pivot density. The parameters are common to each partition curve in any set of size-by-size data and are mathematically related to the familiar performance characteristics, ecart probable (Ep) and separation density. The resulting expression confirms that the Ep and separation density are directly related.

Jan 1, 1986

Flat jack stress determinations in selected colliery roadways have revealed a range of measured stress from 330-p.s.i. tension to 3,750 p.s.i. compression. Photoelastic examination of loaded plastic and actual rock mo.odel mine openings has shown that the primary horizontal stress required to attain these measured stresses would be from one to three times the superincumbent vertical load.Examination of roof movement with a. borehole oxtensumeter and a series of anchors at various horizons to 30 feet in a. vertical roof borehole showed that when a standing face waa.s advanced the roofmovement was practically confined to the lower two feet. The ma.j ority of this movement occurred during the 36 hours after mining at this face commenced.The use of a. radioactive isotope and a. scintillation counter in a. pair of parallel bcreholes promises to be sensitive and accurate method of roof bedding plane crack detection.

Jan 1, 1963

Close spatial relationships between the deposits of the Etheridge Goldfield (23,000 kg of bullion) and various regional geological and geophysical features suggest that genesis of the ore deposits was a multi-stage process that started with magmatic and metamorphic stages in the mid-Proterozoic, climaxed with structural and hydrothermal stages in the late Palaeozoic and terminated with an oxidation enrichment stage in the Cainozoic. Acceptance of this hypothesis permits classification of the Georgetown region into areas likely to contain deposits of the Etheridge type and those unlikely to do so. Consequently there is little scop- for the discovery of extensions of this field. However, the stratigraphic interval between the source rocks of the Etheridge field and stratigraphically higher host rocks of the Croydon field may contain disseminated replacement gold deposits of the Carlin type. The potential host (pyritic carbonaceous, and locally dolomitic siltstone of the Candlow Formation) is locally faulted and cut by granitoids and the extension of a mineralised, long-standing zone of structural weakness.

Jan 1, 1980

By Loo C. E

Thirty two polyacrylamide flocculant samples were selected from the wide range offered to the Australian coal industry. An extensive test program was conducted to consider the properties of the flocculants, the substrates, the process conditions and the water chemistry encountered in coal preparation plants. The study indicated that flocculants with molecular weights of 12 to 14 million and degree of hydrolysis around 40% gave the best "average" performance over a wide range of process conditions. The pick-up and filtration of fine coal was demonstrated on a pilot scale to be a critical function of flocculant properties. This study also showed that the agitation intensity during flocculation was a critical parameter in determining the settling rate of the slurry and the clarity of the resulting supernatant. An electronic meter to measure agitation intensity was designed, constructed and tested to demonstrate how, for the first time, laboratory results can be implemented in operating plants.

Jan 1, 1989

By Demin SS

Slow seismotectonic movements along the in-clined deep fault zone under the compressional horizontal stresses are supposed to be the prin-cipal mechanism controlling the structure and processes in the active ocean margins. Within the scope of the plane strain problem a simple 2-D geomechanical model for the evolution of an island arc system is investigated. We consider a homogeneous elastic half-plane with a shea-ring surface crack. The key element of the model is viscous interaction between the crack sides, the viscisity varying with depth. The model dif-fers from the classical steady-state mode of subduction by nonstationary creep processes on deep faults and by possibly cyclical development of the transition zone.A numerical modeling of the stress-strain state within the island arc system through time was carried out using a semianalytical approach. The results of simulation are in good agreement with geological, geophysical, and seismological data.

Jan 1, 1990

By Kandemir H, Stafford G

The Croydon Gold Mine is located in northwest Queensland and is a joint venture between Central Coast Exploration N.L. and Pancontinental Mining Ltd. The mining operation commenced in 1987 and consists of satellite open pit mines feeding a central Carbon-In-Pulp gold Treatment Plant. The gold mineralisation is hosted by quartz veins within the Croydon Volcanic Group and the Esmeralda Granite, a cogenetic igneous suite of Middle Proterozoic age. The mineralisation comprises gold and silver with associated basemetals. The gold and silver electrum occurs as extremely fine free grains. The gold distribution is heterogenous occuring across the full vein width, or restricted to the footwall or hangingwall. The average mineral resource grade is 3.5 g/t. The deposits are all hard rock and mining is carried out by drill and blast technique. All mining activity is carried out by a mining contractor. Mining is by a selective mining method which entails the drilling, blasting and extraction of the hangingwall waste prior to orebody extraction.

Jan 1, 1989

The movements of the major continental cratons and the distribution of the principal tectonostratigraphic terranes are reviewed in the Circum-Pacific region during Phanerozoic time. It is concluded that major periods of orogeny and consolidation of accreted terranes in the Circum-Pacific region is best correlated with periods of advance of cratonic blocks over the Pacific Ocean basin combined with relative convergent to transpressive motions between the cratons and the Pacific Ocean plates. Continental collisions and collision of terranes with continental margins has not been a significant geodynamic process in Circum-Pacific tectonic evolution. The permanency of the Pacific Ocean basin throughout 500 MA is remarkable. It appears no continental block or large continental fragment has ever entered or crossed the Pacific Ocean basin since early Paleozoic time. This area where no continent has entered for 500 MA is almost coincident with the present Pacific Ocean basin and seems associated with the 25 to 100 meter geoid high which dominates the present-day figure of the Earth.

Jan 1, 1990

Ore deposit modelling is becoming an increasingly accepted tool in mineral exploration. Successful models have already been proposed for several ore deposits of base metals and gold, but tin has so far received comparatively little attention, perhaps because of an excessive preoccupatioi with alluvial operations. This situation is rapidly changing and some of the world's most profitable and newly commissioned tin mines are large, primary tin deposits. Some basic principles of ore deposit modelling are briefly reviewed and the fallacy of an excessive reliance on grade tonnage diagrams based on the tin industry worldwide is discussed. The four proposed models and submodels of large, hard-rock, tin deposits focus on basic concepts such as the spatial relationship with "tin granites", depth of emplacement and the level of erosion. General concepts are drawn. The modelling of large primary tin deposits is reviewed not only in its geological and exploration aspects but also in its mining and economic implications.

Jan 1, 1986

By Hall G

The Mount Isa silver-lead-,zinc deposit possesses a number of features which sets it apart from usual occurrences of ores containing those metals. The deposit has been described in vario:us papers, but development upon deeper levels during the past two years has, yielded much information not hitherto published. Purpose of the present paper is to furnish a unified and coherent perspective by tracing briefly the full rock deformational and mineralization processes responsible for the ore deposition. The paper represents the outcome of ten years' organized geological effort at Mount Isa. Information contained in it supersedes that previously published.A bibliography of published articles relating to Mount Isa ore deposition is appended. In preparing the present paper previously published data have been drawn upon freely wherever applicable. The authors are especially indebted to the papers by Grondijs and Schouten, and by O'Malley and McGhie, which present results of systematic microscope studies of thin and polished sections from comprehensive suites of Mount Isa ore.

Jan 1, 1942

By A Turns

In a survey conducted by symplexi with underground miners in Australia; 78 per cent of participants believed that ‘safety’ is all about people. If ‘safety’ is about people, then is the mining industry focusing on the wrong thing? It would be fair to say that the mining industry is heavily systems focused. Companies develop a safety management system and use this to show regulators that they comply with legislation – however, that is only half of the picture.

May 5, 2022

A massive cobalt-containing pyrite orebody occurs in banded albite-quartz-biotite rocks at Thackaringa, some 30 km SW of Broken Hill. Because of the world-wide shortage of cobalt during the late 1970s, serious consideration was given to the development of a suitable flow-sheet to recover the cobalt from this ore. Details of a pressure leaching process in which more than 90 per cent of the cobalt is extracted from a pyrite concentrate are presented.

Jan 1, 1983

In the last two years the Commission for the Environment has received four Environmental Impact Reports (EIR) for Audit and has been or is involved with at least four environmental impact assessments (EIA) related to mining. The EIRs have included Weavers Coal Mine, the Monowai-Maratoto mining proposal, the Martha Hill mine and the Wainui Road Mill. The EIAs are related mainly to coal fields in the Waikato but also included a further EIA on Martha Hill.

Jan 1, 1986