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Over the past 15 years many world-class gold discoveries have been made in the region. Some deposits, such as Lihir and Porgera in P.N.G., have a contained gold resource that places them among the top dozen deposits ever found on a worldwide basis. Can we see any pattern to these discoveries, or are they the result of good luck or chance by geologists and prospectors who struck it rich? Whilst such discoveries were a feature of the gold rushes of the 1850s and the 1900s, the present boom is now scientifically based. This paper develops an argument that long-tent, multi-disciplinary exploration by experienced geoscience teams underlie the successes achieved. Dis- coveries nearly always reflect a combination of skills, drawn from the areas of geology, geochemistry, geophysics and remote sensing, and a team approach. They do not represent the chance finds of a prospector's pick or such as the Norseman discovery where the gold reef was first noted by the prospector when his horse fell over the outcrop. The following deposits provide major examples of exploration successes within the Australian-Pacific region, it is not an exhaustive list and I have noted other significant producers at the end of this paper. For the Australian mines listed and based on our estimates for 1990 gold production, they represent about 20 per cent of the Australian production total.

Jan 1, 1991

By P Grouhel

In the recent years several new blasting technologies have come into use in surface mines. Electronic initiation, low-density emulsion explosives and modelling software are in regular use throughout the world. In Australia, these new technologies have achieved significant application, largely in open cut coal mines where more than 20 per cent of blasting is now conducted with electronic initiation systems. These new techniques have contributed to the vast improvement in blasting outcomes evidenced by increased recovery of saleable product and faster excavation rates. In large surface mines, OricaÆs unique combination of electronic initiation systems, bulk emulsion explosives and modelling software can be harnessed to target critical value outcomes. This includes targeting better fragmentation, increased ore uncovery rates and better wall stability û all adding to improved mining operation profitability. Orica Mining Services have combined these technologies into a set of offerings called Blast Based Services (BBSÖ). The paper describes applications of these new technologies and possible benefits in large surface mines.

Jan 1, 2007

By Corner NG

A sea bed sampling programme by CRA Exploration Pty. Limited over an area of 12000 km offshore from Westland, Southland and Otago, New Zealand, led to the discovery of the Harvester Prospect, an area of some 67 km2 which averaged 189 mg/m3 gold in surface samples. This area was in water depths of 70 to 100 m and contained a high grade core of 33 km2 which averaged 283 mghn3 gold. The gold recovered was fine grained, averaging 124 microns, and indicated a potential resource of approximately 10 t of gold per metre of thickness. Interpretation of existing seismic and geological data suggested that the gold anomaly may be associated with a unit of sediments 10-40 m thick, probably deposited during a lower sea level stand. Two initial attempts at vibrocoring the anomaly produced inconclusive results. In 1989 a much more powerful vibrocorer with scaled up support facilities and a dedicated 24 It turnaround laboratory were employed. The final results clearly showed that the gold was from an uneconomic surface enrichment.

Jan 1, 1990

By Ennis P. C

The Mt Keith ultramafic intrusive extends for about 200 kilometres from Agnew in the south to Wiluna in the north. It forms the host for a number of nickel sulphide orebodies including Mt Keith and Honeymoon Well. Long fibre minerals are associated with the orebodies. The presence of these minerals impacts on the issue of tailings disposal from several standpoints, particularly the slurry beaching properties and dust generation from dry beaches. Central thickened discharge (CTD) is an innovative method of tailings disposal that involves stacking tailings in a low conical hill instead of storing them in cells. In appropriate circumstances this leads to savings in capital costs and operating expenditure. The method was introduced to Australia in 1981, and is currently employed at four operating mines, Elura and Peak Gold, both at Cobar in NSW, McArthur River in the Northern Territory, and Union Reefs near Pine Creek, also in the Northern Territory. It is the proposed method for Century Zinc and Ernest Henry, both in Queensland. The paper describes laboratory test work and design parameters for the application of the method to tailings disposal at Honeymoon Well and compares them with comparable data for other CTD systems. Of particular relevance for design purposes are beach slope, density, and water recovery. Wind tunnel tests were conducted on the Honeymoon Well tailings samples to investigate dust generation from the dry beach surface and it was concluded that dust generation from an undisturbed beach would not occur because of crusting.

Jan 1, 1996

By Mercer JK

This paper gives a description of the research undertaken by an explosives manufacturer to give better technical advice to the Mineral Industry. Blasting Physics is defined as giving a systematic and coherent account of the initiation and subsequent effects of high explosives upon the surrounding medium. As a result of this work a mathematical model based on the gener- ally accepted mechanism of blasting has been developed. The mechanism and the resulting model are briefly outlined. IFrom'this model the effects of burden, spacing, blasthole diameter, rock and explosive properties upon fragmentation and heave can be calculated. Using these calculations it is then possible to see how variations in frag Imentation and heave can affect the overall production costs of a mine whether it is surface or underground. The overall costs are made up of a number of individual costs - drilling, blasting, loading, hauling and crushing. ach of these operations influences or is influenced by fragmentation and heave s these costs are inter-related, the

Jan 1, 1975

By E Taylor, F Lebbing

The $2.5 billion EastLink project is a 39 km tollway and includes twin three-lane, 1.5 km long, undrained driven tunnels with cross passages every 120 m. The hard rock tunnels are being built to avoid passing the motorway through the Mullum Mullum Valley and help preserve the unique flora and fauna in the area. The design of the permanent concrete lining and waterproofing system for the EastLink tunnels was both innovative and practical, to meet the demanding environmental and production constraints of AustraliaÆs largest road project. This paper describes several key aspects of the tunnel design and construction, including: design of fully tanked, permanent concrete tunnel linings for the main tunnels and cross passages to withstand 37 m head of water pressure in combination with potential rock loading in the future;optimisation of the tunnel shape to minimise the amount of reinforcement required and the design of special welded mesh which was developed within manufacturing constraints;100 year design life and durability considerations in every aspect and detail of the design including concrete mix design and stray current mitigation;development of a precast invert solution for the main tunnel permanent concrete lining to enable faster lining construction and to minimise risks to the tunnel membrane associated with fixing reinforcement and construction traffic;development of prefabricated reinforcement details for the junctions between the main tunnels and the cross passages to enable faster construction and minimise risks to the membrane associated with fixing reinforcement; andincorporating the tunnel drainage sump at the lowest cross passage in the alignment, resulting in deep excavation to satisfy the required storage volumes for drainage.

Jan 1, 2008

By Butters S. E, Deslandes J. V

The selection of loading and haulage equipment in a proposed or oper- ating mine is vital in ensuring the cost effective achievement of produc- tion targets. To assist in the evaluation of different haulage systems, a truck haulage simulation model has been developed at BHP Melbourne Research Laboratories. The operation of the model is described and exam- ples of an actual application at Mt. Whaleback Mine is presented.

Jan 1, 1989

The initially cautious approach taken towards ground support and reinforcement at the Porgera Underground Gold Mine in the Highlands of Papua New Guinea has evolved rapidly in the two years since stoping commenced. The confidence to continue the evolution process has grown from an increasing knowledge of mining conditions as stoping has progressed, to the extent that reinforcement requirements have decreased by 50 to 75 per cent depending on local circumstances. Changes to mining practices have significantly assisted and influenced this process.Empirical observations of ground behaviour, assisted by a deliberately selective extensometer monitoring program, provided the stimulus for early changes to ground support and reinforcement practices. Further optimisation of the ground support and reinforcement effort is being pursued through an active monitoring, measuring and analysis program. Ultimately, situation rather than site specific design will ensure continuing high quality ground support and reinforcement installations. However, local structural and lithological factors will continue to become more critical as the optimum position is reached.

Jan 1, 1993

Interaction between rock and fluid plays a critical role in rock engineering ventures such as stimulation of oil and gas wells, geothermal energy recovery and nuclear waste isolation. Robust and reliable design of the related services and underground facilities is based on understanding of the mechanics and chemistry of the coupled hydromechanical- thermochemical processes. This paper explores the application of the theory of such processes in minerals engineering, with particular reference to rockburst mitigation, in situ solution mining and cavity completion of coal-bed methane production wells.

Jan 1, 1995

A new experimental procedure for determining the solids flux curve is detailed. The procedure is based on measuring the concentration at various heights of a bed of settled solids formed during a semi-continuous sedimentation test. Unlike conventional thickener area calculations, the test procedure demonstrates the dependence of the flux curve on the system feed flux. At a given feed flux, there was good agreement between the solids flux curve determined by the method and continuous sedimentation results. The widely used method of Kynch was found to be restricted to relatively high effective feed fluxes and consequently there was poor agreement with continuous tests at low feed fluxes. The flux curve determined by the method of Coe and Clevenger was invalid for all feed fluxes. A case study shows how the required thickener area would vary for a number of fine coal processing options.

Jan 1, 1989

By Bartrop S. B

Mount Isa mine has a long history of successful exploration since discovery 70 years ago. Remaining reserves, although substantial, exist in a scheduling framework which involves long-term production from new ore sources with attendant technical risk and major capital investment. Current exploration aims to incrementally increase reserve tonnage to maintain existing production levels as well as to provide a buffer for potential start-up delays from new ore sources. Exploration also aims to increase the net present value of the operation by discovering new major orebodies around the Mount Isa and Hilton mines.

Jan 1, 1993

By Corrans I. J, Yan D. S

The CIP process for gold recovery has enjoyed widespread application in most gold-producing countries. The development of a mathematical model of the CIP process has value for use in process design, process optimisation, and process control. Mathematical model development through laboratory experimentation is an important step in the design and optimisation of the CIP process. For this purpose, data has been generated through small scale laboratory leaching and adsorption tests both in batch and continuous mode. This test program has been carried out on specific ores of various types prior to the application of the models to production CIP plants utilising these ores. The applicability of leaching models derived from batch experiments was tested in a continuous five stage CIP pilot plant. The models were then adapted to scale-up the batch to the small scale continuous operation.

Jan 1, 1991

By G MacSporran, I Sheppard

The practical application of LaneÆs theory on optimum cut-off grade policy has to date proved difficult for selective stoping in large-scale underground mining. The key to determining an optimum cut-off grade is the ability to rapidly perform complex mine layout designs combined with rapid output of multiple potential schedules. This paper describes aspects of the detailed investigation into estimating a practical static cut-off grade for the two main orebodies in Mount Isa MineÆs Enterprise Mine. Rule based automated scheduling software was used to evaluate thirteen different stoping layouts (including design infrastructure and capital development) of the Enterprise MineÆs two main orebodies, with over 200 schedules generated. The investigation illustrates the application of commercially available software to solve the problems of generating multiple cut-off grade stope designs and achieving the otherwise insurmountable task of rapidly generating and valuing multiple scenarios for each stoping layout. Each scenario was evaluated using modelled net cash flows of the mining, concentrating and smelting operations of the company and calculating NPV. The cut-off grade for each orebody was selected based on the cut-off grade that achieved maximum NPV û with an appropriate production rate. Underground mine scheduling is a complex task involving the adherence to a number of simple scheduling rules and the balancing of several competing drivers. The study also found that: while each scheduling rule itself is simple, the compounding complexities of their interaction preclude manual scheduling from being a realistic option. there is a maximum sustainable rate of production possible for any given stoping layout, and that the actual maximum production rate is also a function of the required number of years of sustainable production. the optimal cut-off grade was different for each orebody û a recognition of the impact of the different characteristics of each orebody.

Jan 1, 2003

The firing of mass blasts at Isa Mine is a normal operating practice. Both electric and non-electric initiating systems are being used for this purpose. The advantages gained by large firings relate to the Planning, Scheduling, Services and Production functions of Isa Mine. More efficient us"e is made of manpower due to the concentrated charging effort and con- tinuity of the charging operation. In addition, the requirement for ring firing personnel to work at the edge of large stope voids is reduced. Better fragmentation results from the interaction of adjacent detonating rings of blastholes and in flight collisions. With mass blasts there is also less chance of large blocks of ore, created by faults or joints, falling into the stope and creating problems at the drawpoints. The formation of a large tonnage of broken ore facilitates production at scheduled rates from that stope source. The weight of explosive detonating during a mass blast can be considerable. Isa Mine has achieved satisfactory blasting results without excessive ground vibration levels and present knowledge indicates that pillar ground stab- ility has been maintained.

Jan 1, 1978

The introduction ofa submerged entry tundish nozzle incorporating a cylindrical internal space for argon distribution to its inner bore slab is described. In co-operation with the refractory supplier, four major phases of nozzle development have been undertaken. Problems as well as successes are outlined.Significant reduction in alumina clogging ofnozzles has been achieved along with a decrease in nozzle consumption, using resin bonded alumina graphite with up to 4 different materials "zoned" to give resistance to thermal shock, gas leakage, and erosion.

Jan 1, 1985

By J I Stewart

The Copper Canyon deposits, occur in proximity to the regionally distinctive formational boundary between the Staveley Formation and Marimo Shale. The mineralisation here is associated with breccias, veins, and alteration zones near the base of the Marimo Shale unit and in the underlying evaporitic dolomite-dololutite dominant Staveley Formation. The Marimo Shale unit, in its basal 60 metres, is highly carbonaceous and hosts ubiquitous but minor diagenetic (?) copper-pyrite, and on occasion, extensive albite-microcline alteration centres, pyritic (cobaltiferous)-quartz veins, and microcline-quartz_+plagioclase veins or veinlet arrays. The most significant mineralisation, such as at the Greenrnount prospect, consists of a shallowly dipping package of alteration zones overprinted by multiple generations of pink-orange microcline-quartz-chalcopyrite-pyrite-(arsenopyrite) and albite-calcite- phlogopite veins. Accessory mineralogies in most of these mineralisation styles consist of tourmaline, monazite, rutile, and apatite. Chalcopyrite (and secondary chalcocite) and gold are associated with each generation of alteration but are best developed in the later stages of veining. In the underlying Staveley Formation, which is a conformable transition between the Corella Formation limestones and the Marimo Shale, chalcopyrite (cobaltiferous)-pyrite mineralisation occurs as disseminations in pre- and syntectonic breccias, and with disaggregated silica pseudomorphs (after thinly bedded evaporitic sulphate beds) and associated dolomitised limestone-calcilutite. Although this mineralisation may be partly diagenetic in origin the 200 in thick evaporitic packages are also host to a locally widespread (2 to 4 km long and 200 to >500 metres wide) and pervasive 'redrock' styled microcline-dolomite¦hematite alteration. Within this gross alteration package there also seems to be a consistent association with narrow (10 to 100 metres wide), linear (stratabound) semi-massive magnetite-hematite-microcline and quartz-chalcedony replacement zones. Like much of the nearby Corella Formation the Staveley Formation, under the Marimo Shale, has undergone dissolution, paleo-solution karsting (breccias) and tectonic brecciation such that the precursor lithological details have been progressively obliterated. The post-diagenetic to post-tectonic fluid pathway development and metasomatic alteration history of this important lithostructural package of rocks has been traced from preliminary studies only. The ability to do so is largely due to the absence of significant regional and contact metamorphic overprinting, and the local preservation of precursor sediment profiles. It is proposed that both the base of the Marimo Shale and parts of the underlying evaporitic-limestone-dololutite have acted as conformable fluid pathways for hydrothermal and (perhaps) diagenetically derived, Cu-Au-(¦Co ¦As) K-Na-Ti-REE bearing, fluids and brines.

Jan 1, 1994

By Shining Z

The properties of coal or rock containing gas are very important both for studying coal and methane outburst mechanism and for controlling underground rock in mining. The rheological fracture properties of coal containing gas were studied to obtain its rheological fracture principle both in microscopic scale and in macroscopic scale. The application of this principle is successful in explaining coal and methane outburst mechanism and for putting forward a rheological hypothesis of coal and methane outburst.

Jan 1, 1992

Hamersley Iron Pty. Limited mines and pro cesses iron ore from two orebodies at Tom Price and Paraburdoo, situated in the North West of Western Australia. Conventional open pit mining methods are used at both sites in that material is drilled and blasted in benches, loaded by shovels and hauled to the Primary Crushers or dumped on waste or low grade material stockpiles. The present drilling fleet, consisting of eight high capacity Bucyrus Erie Rotary drills has evolved from an initial fleet of a large number of small percussion rigs. There are significant physical differences between the ore types encountered at both mines which nec- essitate the drilling of smaller diameter blast holes at Paraburdoo than those at Tom Price. The drilling practice at each site is dis- cussed, with examples of performance achieve- ments under varying drilling conditions.

Jan 1, 1978

The accurate calculation of ore reserves is one of the most important functions under- taken at a potential or operating mine. In recent years there has been a trend towards recommending more and more complex techniques for the calculation of reserves. However these are not always necessary and many improvements could be made by the use of all potential data and a heavier geological input. An ore reserve should be the result of geological not mathe- matical or engineering reasoning. All ore reserve estimates are wrong and the important thing is to.recognise why they-are wrong and to take action to minimize the errors. Geostatistics and other complex mathematical techniques may appear to answer all our needs for ore reserve accuracy but there are many drawbacks, not least of which is the communi- cation gap which may develop between the operator and both management and production Personnel.

Jan 1, 1979

By Callcott R

Prediction of raw coal size distributions and those generated by processing are examined using spreadsheets and the matrix analysis of breakage processes. Run of mine coal size distributions are predicted from the lithotype properties using a

Jan 1, 1998