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By Mortimer RR

The Weipa bauxite mining operation on the west coast of Cape York currently mines lb million tonnes of crude ore per year from the Andoom and Weipa mines. Andoom ore is trucked up to 4 km to a rail load station and hauled 20 km by train to the Beneficiation Plant. Weipa ore is trucked up to 7 km to the Beneficiation Plant. Increasing haul lengths and production requirements have led to a progression of larger two axle rear dump trucks and currently he intrcducticn of 145-tonne, three axle L t Dm dump trucks. bith the introduction of the Andoom a operation in 1972, the decision was made to use a railway system to haul crude ore from Andoom to Weipa. This system has proved to be successful from both an economical and operational view point. Due to the successful combination of a truck and rail haulage operation in Andoom, future :evelopment of orebodies requiring increased haul distances and increased production tonnages will probably result in extension r>f the railway system to compliment the trucking operation from the mine face.

Jan 1, 1978

This paper details successful implementation of a revolutionary pit access system involving excavation of an 'in-the-wall' ramp at Three Mile Hill open pit operated by Gold Mines of Coolgardie, formerly Goldfan Limited, at Coolgardie, Western Australia. Three Mile Hill is a medium-size, open pit, gold operation typified by hard, competent, fresh rock conditions from near surface. The project involved construction of a haulage tunnel or decline access located in the wall of an open pit in place of a conventional pit access ramp. Works undertaken as discussed herein included excavation, support, ventilation, dewatering, services installation, commissioning and monitoring. Prior to implementation, the conventional hardrock pit slopes and designs were constrained by the presence of infrastructure and a main road to the North and by adjoining leases to the Southeast. The combination of these factors and economic considerations resulted in a decision to proceed with an innovative in-the-wall ramp access system that is believed to be the first of its type in Australia. Back-analysis indicates that implementation resulted in a cost saving of as much as A$3.6 million and increased mineable pit reserves. The paper deals with the successful implementation and operation of the in-the-wall ramp haulage as well as an economic evaluation that is aimed at drawing some general conclusions on favourable conditions for implementation in other mining scenarios.

Jan 1, 1996

The effectiveness of three different types of longwall chock under the three different types of geological conditions worked recently is outlined. Some provisional analyses of the variation of chock load under the shale roof con- dition are briefly discussed and some problems and solutions of gateway and road- head support outlined.

Jan 1, 1974

By Johns A. L

The concept of the Melbourne Underground Rail Loop and the organ- isation to achieve its construction are covered in the companion papers (Reference 1, 2) and will not be repeated here. The Victorian Railways, as well as being the eventual operator of the Loop when it is completed by MURLA, have also been responsible as "Contractors" to MURLA for the construction of the "cut and cover" or "box" tunnels and related approach works located on existing Railway property. These tunnel connections link the existing suburban system to the new underground works. The following tabulation indicates the significant work volume involved in this cut and cover tunnelling exercise and which is covered in some detail by this paper.

Jan 1, 1981

By Chenggang W, Junhua D

Fragmentation variation laws in loading and non-loading areas are obtained by cement block model blasting experiments under various stemming lengths. A reasonable ratio between loading length and stemming length is worked out according to minimum average fragment size. The present continuous loading structure, for its very long length to be stemmed, leads to insufficient fragmentation in the upper part of bench. So a new loading structure with bottom air cushion is put forward. The author analyzes blasting effects and processes of two loading structures' and proves that there exists a optimal length of air cushion.\

Jan 1, 1990

The influence of strongly chemisorbed solutes such as oxygen and sulphur on the rates of reactions at the gas-liquid iron interface is briefly reviewed. Deductions from recent studies of the rates of decarbur- ization of carbon-saturated liquid iron indicate ideal adsorption behaviour for sulphur over a wide temperature and composition range. This is in fair accord with available infor- mation on surface tensions in the Fe-C-S system. Previously unpublished results for the kinetics of the 14C02-CO exchange reaction are in accord with ideal absorption of oxygen on liquid iron. The derived value for the ideal adsorption coefficient of oxygen at 1550¦C is in quantitative agreement with measurements of the depression of surface tension in the Fe-0 system. Consideration is given to the applicability of such results to the violently agitated systems of steelmaking.

Jan 1, 1980

By Lawson F

Synthetic calaverite (Au Tez) has been prepared and its physical properties checked.Simple flotation tests indicate that the recovery of calaverite should be possible using n-butyl or sec-butyl xanthate collectors under approximately pi I neutral conditions with a copper sulphate activator.Roasting calaverite in air at moderate temperatures resulted in its decomposition with the formation of elemental gold and tellurium dioxide.In alkaline oxygenated cyanide solutions, both gold and tellurium tend to dissolve. At pHs less than 14, about 50 per cent of the tellurium remains as elemental tellurium; however in very strongly alkaline solutions, essentially all of the tellurium is converted to the soluble tellurite ion (TeOl-).However, even at high pHs, the solubility of gold in the cyanide solution is still low due almost certainly to passivation effects.

Jan 1, 1991

Pillar mining methods at the Pasminco Mining Broken Hill Operations are not new. Since mining commenced on Pasminco's leases at the turn of the century virtually every pillar extraction method tried throughout the world has been used. Much of the remaining mineral resource in the Pasminco Broken Hill leases is contained in pillars.However, due to the on-going need for mechanisation with bulk mining methods, and the very peculiar physical circumstances surrounding the formation of these pillars, their exploitation requires the development of a virtually new method based on excavation technology not previously used in the Australian mining industry. Trials of the method are to take place at the southern operations during 1991.

Jan 1, 1992

Environmental considerations were key factors in the design of the Ranger Uranium Mines treatment plant. The mine is located adjacent to the Kakadu National Park and has an average rainfall of 1.6m per annum. Initially, no contaminated water or liquid effluents are to be released from the project area and thus water management is a key design and operating fact. Particulate and gas emission criteria influenced design as did occupational hygiene factors (dust, radon, housekeeping, maintenance access). Equipment selection and engineering standards were conservative and resulted in the plant attaining design performance in less than three months from the date of commissioning. A number of mechanical and operational problems were experienced and are discussed in the paper, however none of these problems have had a significant effect on production.

Jan 1, 1984

By Romanovsky N. P

The Pacific Mobile Belt (PMB) is characterized by old origin and complex evolution both in time and space. As the global structure, the PMB is a narrow tectonic region dividing two plan-etary hemispheres, viz. the Pacific and IndoAfro-Atlantic ones, the relative shifting of which defines the character of many geodynamic processes in this belt. The PMB features inhomogeneity of structure, special matter composition characteristics, sharply broken-out topography, and intensive fields. Generalized anomalies of the gravitational field closely correspond to the PMB boundaries defined by the real features, i.e. the andesite line and distribution areals of Mesozoic-Cenosoic granitoids. The belt boundary position is controlled also by seismic velocity anomalies at a depth of down to 200 km. The modern PMB deformation is defined by the left-hand equatorial shift and rotation of the Pacific Ocean counterclockwise. This rotation is non-uniform in time and of an oscillating character. The motive forces of the phenomenon are considered.

Jan 1, 1990

By Pattinaja MA

Mathematical modelling was carried out to determine the probable convergence and vertical stress patterns around a retreating longwall panel in an underground coal mine in New South Wales. An 'Electrical Resistance Analogue' and a program called 'THREED' based on the displacement discontinuity method were used for the modelling. Parts of the obtained results are presented here and compared with some measurements of convergence at the site. The modelled and measured data agree better qualitatively, than quantitatively.

Jan 1, 1986

By Golab K, Partridge AC, Fletcher CAJ, Holtham P

Spiral concentrators are used globally in the fine coal processing industry to segregate particles, by gravitation, on the basis of density and size. Consisting of an open trough that twists vertically downwards about a central axis, a slurry mix of particles and water is fed to the top of the concentrator. Particles are then separated radially as they gravitate downward. Since their introduction to Australia in the 1940's, the generic design has evolved largely by laboratory trial-and-error investigations of different prototypes. However, this approach has proven expensive and optimal designs have not been necessarily developed. Accordingly, Computational Fluid Dynamics (CFD) analysis has been used recently as an alternative method of investigation, to assume as is envisaged, a role in the design process. To date, CFD models have progressed to simulations of turbulent fluid flow on current production spiral designs, and are continuing to be adapted for inclusion of particles at realistic feed concentrations. To be able to use the models confidently however, laboratory experiments must also be performed to validate the predictions during the development stage. This paper reports the current findings of an ongoing CFD and experimental program applied to one spiral unit. Satisfactory quantitative agreement has been achieved for the fluid and particulate flow characteristics, and although further validations are appropriate, the model already possesses significant potential for use as a reliable predictive design tool.

Jan 1, 1998

By Culshaw MG, Deaves AP, Bell FG

The accurate prediction both of the water ingress into sub-surface excavations and the nearby groundwater pressures is of fundamental importance to the control of the stability and flooding of tunnels or mines constructed below the water table. Predic- tions are usually based on laboratory and in situ permeability determinations together with observations of groundwater conditions in boreholes. Although established theoretical methods provide a basis for prediction, the actual ingress depends on many factors. The objective of this paper is to explore the geological controls on groundwater conditions, and the available methods of prediction of both groundwater flow and pressure are outlined. Salient points are emphasised by reference to a case history involving the construc- tion of a tunnel in a faulted and mixed sequence of sandstones, siltstones, shales and coals. Water ingress quantities have been monitored for a variety geological and geotechnical conditions including heavily faulted and mine disturbed ground. The overall results are discussed with reference to the relevant hydrological and geologi- cal conditions in terms of the geological structure, lithology and rockmass condition as well as the construction methods.

Jan 1, 1988

In the traditional analysis of airblast and ground vibration, it is often assumed that only that single blasthole possessing the maximum charge weight (or a small group of blastholes initiating in an 8 ms time window) will determine the peak level of airblast or vibration. This assumption is examined in light of waveform superposition, and is found to be unsound. More rational alternatives are given in which all blastholes (or a selected number of blastholes) are assumed to contribute, in varying degrees, to the peak vibration or airblast. However, it is also shown that there is generally no precise solution for determining the number of blastholes that contribute to the peak level. The technique of waveform superposition does not rely on evaluating which group of holes produced the peak, and so is the preferred method for prediction. Some numerical and analytical models of wave superposition for airblast and vibration are also reviewed and recent approaches discussed. The directionality of airblast, in particular, is analysed in detail using a new superposition model that is constructed of two submodels, onenumerical, the other analytical. This model shows that the airblast from even a single blasthole can be highly directional. The detail of this model is commercially sensitive and will not be discussed. Only results and a broad discussion will be given.

Jan 1, 2004

This paper discusses equipment replacement strategies and specifically addresses the upgrading of technologically superseded equipment. The process of equipment replacement evaluations is reviewed, and areas have been highlighted where currently accepted practice results in a bias towards retaining existing equipment longer than otherwise justified. The Discounted Average Cost Method is described and the advantages of the technique for this style of decision making discussed. Several key issues influencing the replacement evaluation are also presented together with examples from recent consulting work.

Jan 1, 1992

By Erepan P. C

Flash flotation technology was introduced by Outokumpu in 1985. Considerable success was achieved in other plants with similar operations to OTML. Conclusions from site visits and amenability tests performed on plant samples were that the OTML

Jan 1, 1997

By Trumpff H

Opencast Lignite Mining requires topwall strata of seams to be fully depleted and footwall aquifers sufficiently depressurized. To prevent a spread of the cone of depression into protected wetlands some distance away, alternatives had been investigated such as closing water works, underground slurry wall barriers and recharge by infiltration. As a result of these investigations, the infiltration method has been chosen and in a first phase during the next decade it will utilize as much as 55 x 106 m3/year. Using this approach, the survival of the wet lands is assured.

Jan 1, 1988

Tectonic subsidence plots have been calculated for well, extrapolated-well and significant off-well (seismically-based) locations in the Vulcan Sub-basin and adjacent highs (western Timor Sea). The subsidence curves have been normalized to a common datum, the distinctive "near top Permian" marker, and corrected for sediment compaction, palaeobathymetry, eustatic sea-level change and loading effects.Four principal phases of post-Permian basin development are recognised and quantitatively described by integrating the results of the sub-sidence analysis into the regional (e.g. recent Ocean Drilling Program-derived) framework of the tectonic evolution of the North West Shelf. They are1. the Triassic-mid Jurassic Westralian Superbasin intracratonic phase,2. the late Jurassic-early Cretaceous North West Shelf rift phase,3. the mid Cretaceous-Palaeogene North West Shelf subsidence phase, and4. the Neogene-present Timor collision phase. Rapid Triassic tectonic subsidence occurred in an intracratonic setting, possibly subsequent to aborted late Palaeozoic rifting. Intracratonic sub-sidence mechanisms such as deep crustal metamorphism and/or intrustion and regional tectonic compression are invoked in addition to any post-rift thermal subsidence which may have occurred.

Jan 1, 1990

The Hellyer deposit, hosted in the Cambrian Mt Read Volcanics, displays features typical of volcanogenic massive sulphide orebodies. These include a well developed stringer zone, metal zonation within the orebody, a polymict volcaniclastic sequence flanking the deposit and a hangingwall alteration plume in overlying basaltic pillow laves.Mapping and core logging is very detailed in order to extract as much data as possible from the deposit and its host rocks. A geological log suitable for direct computer input was adopted shortly after the deposit's discovery.

Jan 1, 1990

The economic significance of a fundamental understanding of the mineral pyrrhotite is dis- cussed. Particular emphasis is placed on the relationship of other sulphide minerals to the pyrrhotite when it is the major sulphide mineral present in an ore body. Studies of the Kambalda nickel deposit are used to give a better under- standing of (a) the genesis and other character- istics of a particular ore body (b) the textural relationships between pyrrhotite and other sul- phide minerals (c) magnetic properties of natural pyrrhotite, and (e) the oxidation and supergene processes that take place in a sulphide ore body.

Jan 1, 1972