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Single station group velocities of fundamental made Rayleigh waves over the period range 15-100 s are carguted for five provincial profiles of the West Pacific. Based on recordings of earthquakes around the West Pacific by the W~ (World Wide Standard Seismic Network) stations AFI (Afianalu), HNR (Honiara), WEL (Wellington), PAR (Raratonga) and RAB (Rabaul). The inversion of the derived dispersion curves for average shear velocity-depth structure of the crust, LID and LVL shows that (i) the over-all structure beneath the profile 'westernSamoa-Micronesia-Mariana' is in between that of regions 3 and 4 of Pacific Ocean (Yu and Mitchell, 1979), except that the velocity is slightly lower, (ii) the uppermost mantle beneath the 'Vitiaz Trench' profile between AFI and HNR is similar to that of region 2 of the Pacific - in other words, thin LID and thick LVL; (iii) the structure beneath the ' Ibnga-Keradec Ridge' profile has a thick crust with thick sediments, and LID-LVL velocity and thickness are similar to region 3 of the Pacific; (iv) beneath the profiles ' Tonga/ Kermadec Trench events-RAR station' the structure is intermediate between regions 3 and 4 of the Pacific Crean; (v) from decomposition of the 'Solomon-meriana' profile, the structure beneath the Cntong Java Plateau has a thick crust with thick sediments and the uppermost mantle is similar to that of region 3 of the Pacific clean.

Jan 1, 1990

By T Lancaster

The Mount Gordon operation, consisting of the Esperanza open cut mine and the unique Mount Gordon Ferric Leach processing plant, is operated by Western Metals Copper Ltd at Mount Gordon, 125 km north east of Mt Isa. The processing plant treats predominantly the secondary copper sulphide minerals, chalcocite and covellite. The gangue consists of massive pyrite and a range of silicified siltstones. The processing plant utilises a conventional single stage SAG/cyclone milling circuit, followed by low-temperature/low-pressure autoclave oxidation to produce copper in solution. The pregnant leach solution is treated via conventional SX/EW technology to produce copper cathode. Currently the plant is operating at a nominal production rate of 48 500 tpa copper. The Mount Gordon Ferric Leach technology is the worlds first integrated pressure leach/SX/EW process to be used to treat copper sulphides on a full plant scale. In the last six months, July to December 2001, the plant has emerged from a two-year postcommissioning phase to achieve steady state operation. This has been characterised by high plant availability and consistent production performance in excess of the name plate capacity of 45 000 tonnes. Production rates will continue to increase over the next 12 months to over 50 000 tpa via a planned process of incremental improvements. The pressure leach circuit has consistently achieved availabilities exceeding 95 per cent over the past 18 months. Notwithstanding this, the leach circuit still has a much greater requirement for planned maintenance than SX/EW. For much of the Mount Gordon processing plantÆs operating life, the leaching process has constrained production. Recent developments arising from detailed mass and energy balance modelling have now significantly improved leach capability, resulting in the plant bottleneck being shifted to electrowinning. In order to balance the capabilities of the two circuits however, the surge capacity between leach and SX/EW was increased substantially. This effectively de-coupled the higher capability but lower availability leach circuit from the lower capability but higher availability SX/EW circuit. As a result, electrowinning utilisation has increased to in excess of 98 per cent, which is reflected in a higher overall plant throughput.

Jan 1, 2002

By Juniper LA

ERM Consultants Pty Ltd was established in 1980 for the purpose of introducing a disciplined coal technology and power station planning service, to support Australia's efforts in establishing a major export steaming coal industry. At that time, major coal exploration programs were mounted on more than 50 potential export coal deposits with proven open-cut reserves to export 200 Mt/a of coal. The fact that Australia achieved an export trade of only 30 Mt/a, equivalent to the energy requirements for a population of around 5 million people, illustrates the very small achievement to date. The main reasons for this small export steaming coal growth have been: 1. Failure to convince potential overseas coal buyers of the benefits of coal-fired power generation, and the ability of proper power station design to overcome environmental problems, and achieve reliable operation and long life when burning Australian coals. 2. Failure to promote Australian power engineers to advise on the use of Australian coals, resulting in Northern Hemisphere power station experience dominating in market countries. 3. Failure of governments to draw on privately practising Australian power engineers and coal technologists in technical workshops, presentations and assistance to overseas countries, to ensure that personnel whose business it was to serve the follow-on needs of countries were readily available. The result of these failures has been that: 1. Only a fraction of prospective overseas coal-fired power projects have proceeded. 2. Australia has had no influence in the design of overseas power stations to ensure that potential customers would be confident that Australian coals could be reliably burnt in their boilers.

Jan 1, 1987

The art of flotation may be divided into two distinct branches, namely:-1. Collective flotation.2. Selective flotation.(1) Collective flotation is applied when all the valuable minerals in an ore are required in one concentrate, leaving ,only gangue minerals in the tailing. The method is applicable, for instance, to such ores as auriferous copper sulphides associated with gangue minerals only, or to silver lead ores low enough in zinc and other valuable minerals.(2) Selective flotation is applied when there are present in an ore two or more valuable sulphides, which cannot be subsequently efficiently treated unless they are separated from one another as well as from the gangue. For example, a silver-Iead-zinc ore, or a copper-gold-iron ore; where the iron is not required with the copper gold concentrate.In order to make these operations practicable chemical reagents have been developed, having power to exert definite actions on the various minerals when brought into contact with them in a water pulp.COLLECTIVE FLOTATION.In order to bring about collective flotation it is generally necessary to add to the pulp a frothing agent and an activator or activators for all the minerals which it is desired to float.SELECTIVE FLOTATION.The object of selective flotation is to activate the mineral which is to be floated, and at the same time to prevent all other minerals from floating.

Jan 1, 1936

By Yanagase T, Nakamura T, Ueda Y

The possibility of removing the phos phorus and sulphur contained in steelmaking slag has been studied by observing directly through the microscope melts heated on Pt- filaments. After a CaO crystal was placed in the molten slag, distributions of P, S and other elements formed around the CaO crystal were determined with the aid of EPMA. The results indicated that a layer of 2CaO SiO2 is formed on solid CaO in CaO-Si02 melts. Then between CaO and the newly formed compound the molten slag tends to migrate through cracks. For higher Fe 2 03 contents, the layers of the compounds 2CaO.Si02 and 3CaO SiO2 formed around the CaO crystal are not continuous but look more like particles, which promotes the dissolution of CaO. Phosphorus in slag was found to be enriched in the 2CaOòSi02 layer. Phosphorus in the 2CaO SiO2 phase is not related to the primary slag composition, being about 5-7% P205.. Sulphur in slag,as well as the phos- phorus,was concentrated in the 2CaO.Si02 phase. Disintegration due to weathering observed for slags produced in these investigations appeared to be due principally to hydration of lime.

Jan 1, 1980

The Permian coal in the Muja Coal Measures of Collie Basin of Western Australia has a subdued lustre because of the fine laminations of lithotypes, and the dominance of dull and dull banded lithotypes with minor bright, bright banded and fusinous types. The maceral composition of the coal is variable, however the macerals of vitrinite and inertinite groups dominate and the exinite and mineral matter contents are low. The lithotypes have low concentrations of trace elements and the boron concentration is between 10 - 100 ppm recorded only from the dull lithotypes. On the basis of organic petrology, the inter-seam sediments, flora and the very low concentration of boron, the depositional environment postulated for the coal is braided, fluvial and fluvio-lacustrine with marked fluctuations in the water table. The low water table in the environment accounts for fusain and inertodetrinite in the coal.

Jan 1, 1996

By S Hapugoda, H Han, L Lu

Sinter quality depends heavily on the mineral phases, textures and physical structure of the sinter, which are formed upon solidification of the sinter melt. The interaction of sinter initial melt with its surrounding materials will impact the properties of the sinter melt and consequently the solidified structure and quality of resultant sinter. Spreading and penetration are two important phenomena dictating the interaction of the initial melt with its surrounding materials, such as nuclei and adhering fines. In the present study, the penetration behaviour of an initial melt into various natural iron ore substrates of different ore types during sintering was studied using a laboratory scale penetration testing procedure. The penetration depth and width were found to increase with temperature and vary with the type of iron ore due to their unique pore structure and mineralogical texture.

Nov 8, 2021

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 C M. Sennitt, M J. Spadafora

Systematic field evaluation of known gold and clay occurrences in South Korea has led to the recognition and discovery of both high and low sulphidation gold-silver epithermal systems. These are associated with Cretaceous acid-intermediate volcanic centres in the southern parts of the peninsula. The high sulphidation deposits such as Seongsan and Kohung are characterised by pervasive silica-alunite-dickite-pyrophyllite alteration with anomalous arsenic geochemical signatures. Gold mineralisation is associated with fine grained marcasite and pyrite. A low sulphidation quartz vein system observed at the Tongyoung mine comprises multistage colloform banded quartz-carbonate assemblages, with minor manganese and base metals. Gold and silver occur as electrum and tellurium minerals. Some deposits such as Gasado and Dogcheon display both high and low sulphidation alteration assemblages. Early pervasive silica-alunite-pyrophyllite alteration caps formed by acid fluids with a significant magmatic component, occur above cryptocrystalline colloform banded vein systems. The quartz vein stage hosts the precious metal mineralisation and appears to have been deposited by later neutral fluids generated in part through mixing with meteroric water.

Jan 1, 1999

This paper considers three aspects of cemented fill practice and research in Mount Isa. Firstly, an account is given of the use of Portland cemented hydraulic fill both in MICAF sills and in recovery of major horizontal pillars in the 650 copper orebody, where, during mining, cemented fill has regularly been exposed on unsupported vertical faces up to 90 ft high. In the paper the main considerations are the role and specifications of the fill used but also included is a brief description of fill preparation and placement.Data resulting from a Portland cemented hydraulic fill sampling, curing and testing campaign covering about 18 months of operating practice are presented, analysed, and discussed. These yield information indicating the mode of operation of a fully-automated fill preparation station, as well as a means of comparing field and laboratory strength results. A technique with potential for use as a fill quality control without actual strength testing is also described. The data collected showed that the fill station can operate within tolerances set on product quality, that laboratory and field strength results are comparable, and that rapidly obtained fillsample properties such as moisture content and void ratio can be related to cement content and strength, and hence used for quality control.Results of a fill research programme conducted by the author in Mount Isa since early 1968 are presented involving Portland cemented hydraulic fill and alternative, cheaper additives for cementing hydraulic fill. The most significant alternative to Portland cement is quenched and ground copper reverberatory furnace slag, whIch behaves as a pozzolan, reacting strongly with any available lime to produce cementitious hydrated calcium silicates and allowing Portland cement reductions of at least 50 per cent without strength loss.

Jan 1, 1971

Radioisotope X-ray and neutron techniques of analysis can be used for the determination of a wide range of elements in minerals. The most important applications of these techniques to the mineral industry are for on-stream analysis of slurries and solids, and for geological assay. The radioisotope X-ray techniques are the more developed ones and two installations for on-stream analysis are in routine use in mineral processing plants in Australia. Neutron techniques are being developed, and should prove valuable for geological assay of large numbers of mineral samples, for borehole logging, and for specific on-stream analysis when the cost of the equipment is warranted.

Jan 1, 1969

The Coke Ovens Laboratory at Australian Iron & Steel, Port Kembla has been involved in the analysis of seam gases and mine airs for approximately twenty (20) years. This period has seen many developments and changes in the techniques used to the point when the current techniques are equal to other labora- tories involved in similar analyses. The laboratory has NATA registration for the analysis of mine airs and gases. Apart from routine testing of seam gases, ventilation airs and gases emmitted from coal bore cores a number of projects have been undertaken. These have served a twofold purpose, one to provide information to the customer, generally Collieries Research and Technology and secondly in developing the skills and capabilities of the Coke Ovens Laboratory. This paper discusses the development and services available at the Coke Ovens Laboratory for the analysis of gases and airs from collieries.

Jan 1, 1983

To provide suitable backfill material for the cut and fill mining method being used to extract ore from the C.S.A. mine, flotation tailings are deslimed in single stage cyclones. The sand fraction is stored on the surface in unagitated storage bins before being pumped underground, while the slime portion is thickened and pumped to a residue dam. Design and operating details of the sand preparation and storage sections are given.The initial preparation of a stope for filling, consists of laying percolation and decantation drainage pipes on the sill floor. Preparation for fllling of subsequent lifts consists of rearing up the ventilation pipes at the ends of the stope, preparing the decantation system, and building a barricade or wall. The fill is carried to, and discharged into, the stope through 4 in. diameter pipes and filling of any section is carried out 24 hr/day normally without supervision. The fill is retieulated underground to the 1200 ft level through rubber lined pipe installed in the upcast shaft. Boreholes of 3 in. diameter drilled from the1200 ft level convey fill to the 1800 ft level. The mine drainage system is basically designed to handle the water associated with hydraulic filling. A system of primary and secondary sumps has been installed to handle the percolation and decantation drainage from stapes and to allow settling of fines before the water is fed to the main pump station.A programme of investigation into the properties of the emplaced fill is in progress. Results to date indicate that the fill as presently placed and drained, will not cause any problems in the mining of vertical orebodies by cut and fill methods for lifts in excess of 300 ft.

Jan 1, 1969

Using normal low pressure filtration methods for the dewatering of fine china clays, the best that can be achieved is cakes with about 30% moisture. In order to get the moisture levels down to acceptable levels the traditional method used is thermal drying, which is both costly and dust creating. It was to improve this process that ECC International embarked upon a programme of development of filtration equipment using high pressure to achieve significantly lower moisture levels. This development work investigated several design philosophies and culminated in the production of two quite different solutions. The High Pressure Plate Press uses round plates / chambers of one metre diameter and a filtration pressure of 70 bar. This press is fully automatic and produces a surface dry cake that has sufficient plasticity for the further processing that is required on specific qualities of china clay. The TUBE PRESS on the other hand uses a unique design configuration and operates at a filtration pressure of 100 or 140 bar, depending upon the model. The TUBE PRESS produces a brittle, surface dry cake that is easy to handle and a filtrate that is usually crystal clear. The TUBE PRESS achieves a much higher degree of separation than is possible with conventional equipment, which is particularly important if the filtrate is the product. Over the past 15 years plants incorporating both HP Plate Presses and TUBE PRESSES have been installed in the china clay operations of ECC International and are giving excellent trouble free service. The TUBE PRESS has also proved to be extremely versatile, effectively dewatering a wide range of fine particled slurries, in a number of diverse industries.

Jan 1, 1989

Rock bolting has become the most important method of ground support at Mount Isa. Various types of rock bolts are used to suit the different applications and requirements. To apply rock bolting techniques satisfactorily, it is necessary to have some knowledge of the nature of the rock, the type of rock failure, any stress redistribution which may occur during the intended life of the rock bolt and the time for which ground support is required. At Mount Isa there are a number of dif- ferent applications of rock bolts for ground support, and some trends in rock bolting techniques.

Jan 1, 1971

Comminution of solids is surely one of the oldest technologies which even in this day and age of DNAs, chips and space exploration continues to challenge our scientific acumen and engineering ingenuity. In essence, this challenge is two-fold. One, as much as three to four per cent of all electric power generated world-wide is consumed in crushing and grinding primarily because the utilisation of energy is woefully poor. Studies have shown that the efficiency of mechanical size reduction processes is of the order of 1.5 to 12 per cent only (Schoenert 1986). Two, with the grinding technologies available to us, we have, at best, inadequate and, at worst, almost negligible control over the shape of the comminuted particles, size dispersion of the ground mass, and the sharpness of mineral liberation. Low energy efficiency and lack of control in the sense mentioned above have far-reaching implications for resource conservation, performance of down stream unit operations, and damage to the environment. Our problem is in fact central to the mineral-energy resources triangle shown in Figure 1 which depicts the close interrelationships among mineral resources which are becoming poorer in content and more complex in mineralogy each day, energy resources which are depleting rapidly without any viable alternate on the horizon, and environmental concerns which can no longer be ignored. It is evident that any improvement in the efficiency of the comminution process impacts directly on the control of environmental damage, conservation of energy and the economics of the operation. These concerns have special relevance for the processing of non-ferrous ores.

Jan 1, 1992

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

In many metal mines in China,the 70B2 series of fans has been used for main fans for a long time.These fans generate higher static pressures than are required for the relatively high equivalent orifices of the ventilation systems of many of the mines. As a consequence, their running efficiency is common only around 30%. The loss of power is significant.

Jan 1, 1988

By Golosinski T. S, Jorgenson J. D

Several methods are available for inspections of mine shafts. These involve use of inclinometers, moving beams, inertial platforms and decelerometers. Inspections which use decelerometers are of most interest since they allow assessment of conditions of shaft steelwork, conveyances and the shaft itself. This assessment is based on recording and analysing dynamic behaviour of shaft conveyances. Sample inspections of several WA shafts confirm feasibility of using this method for periodic shaft Inspections.

Jan 1, 1995

By Misra VN

The carbon-carbon dioxide reaction is the rate determining step in industrial processes such as the rotary kiln direct reduction process for iron ores. The use of brown coal as a reductant in the rotary kiln process has been shown to result in higher throughputs and lower kiln temperatures. No experimental data has been reported on the effect of coal type or the use of brown coal chars. Methods of carbon-carbon dioxide reacti- vity measurement are discussed. None of the methods have been related to direct reduction practice. No standard test has been developed to assess the reactivity of brown coal chars to carbon dioxide. For routine comparative work the gas analysis method of Okstad and Hoy appears to be the most suitable although some modification to the experimental conditions is required. For detailed kinetic studies direct weighing techniques are to be preferred. The factors affecting the reactivity of brown coal char to carbon dioxide are reviewed. Numerous factors such as the origin of the coal, pretreatment and ,physical and chemical differences have been found to affect the reactivity of brown coal chars but no data has been reported on the effect of coal type on reactivity to carbon dioxide.

Jan 1, 1980