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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

By Filigenzi M. T

Stresses around mine openings at depth can cause the surrounding rock to fail, releasing stored strain energy. When this happens, the rock may literally explode or `burst' into the opening without warning. As mining progresses deeper into the earth, the possibility of seismic events and rock bursts increases. Researchers at the US Bureau of Mines (USBM) are currently studying seismic activity in three underground hard-rock mines in the United States: the Homestake Mine, Lead, SD; the Lucky Friday Mine, Mullan, ID; and the Sunshine Mine, Kellogg, ID. Waveforms from seismic events are recorded by personal-computer-based hardware and software. This information is archived and transferred from the mine sites to the USBM via modem communication links. Then, using USBM-developed software, the events are analysed to determine various parameters, including magnitude, frequency, and location. In addition, researchers are modelling the deep levels of the Homestake Mine using a finite-element code. These models generate stress and displacement values for a given loading condition. By studying material properties, in situ stresses, and seismic activity along with actual scope sequencing, researchers can make correlations between stresses induced by mining and the frequency and magnitude of seismic events. Information on seismic events coupled with results from finite-element analyses have increased understanding of rock mass behavior and the mechanisms that may lead to rock bursts. Optimisation of slope sequencing designs as a result of these studies could reduce rock burst hazards.

Jan 1, 1995

Queensland hosts vast deposits of brown and black coal, significant accumulations ranging in age from Permian to early Tertiary. The great diversity of coal resources in the State to some extent reflects the proximity of Queensland to plate-marginal tectonic processes through much of the Phanerozoic eon. Coal is contained within sedimentary basin fills of four fundamental types; 1. extensional, 2. foreland, 3. strike-slip, and 4. intracratonic. Thick (10 m+) though laterally restricted coal bodies are characteristic of extensional and strike-slip basins, whereas coals of more modest thickness but much greater lateral extent are typical of foreland and intracratonic basins.

Jan 1, 1991

Before proceeding I wish to say that the excellent diagrams by which my paper is illustrated are the work of Mr. C. H. Barnes, Constructing Engineer of the Kalgurli Gold Mines Limited, and I am also much indebted to Mr. F. A. Moss, manager of the mine and for the privilege piIling information not previously made public.The limited time at my disposal has coolled to, curtail the scope of my paper to a few practices in ore treatment which are being worked on the Kalgurli Mine, but which I believe are of more than ordinary interest to thp~e Goncerned in modern treatment of gold ores. As an introduction to my subject it is, necessary that I should give a brief outline of the process by whiGh the gold is won from the complex sulpho-telluride ore of the Kalguili mine.My business is not to enter into any discussion as to the relative merits of the two rival sulpho-telluride ore treatment processes at work on the Kalgoorlie field, viz, the treatment of the unroasted ore after shining by solutions of bromocyanide, as against the treatment of the ore-after roasting by solutions of potassium or sodium cyanide either in filter presses or percolating sand vats. Even if reliable costs and percentages of extractions were obtainable in each case, it would not constitute an infallible basis of comparison, as the larger plants would necessarily have an advantage in cost per ton as against the small plants, and the other conditions obtaining are in many Cases dissimilar.

Jan 1, 1903

By Struthers M. A

The basement contact zone, a major fault structure underlying the copper orebodies at Mount Isa, has a significant influence on orebody extraction. The zone is comprised of a variety of weak, barren lithologies which often create very difficult mining conditions, contribute to stope dilution, and have an adverse effect on concentrator recoveries.The geological characteristics of the contact zone are described, and the importance of timely, accurate geological information emphasized.A variety of mine design strategies have been employed to reduce the impact of the contact zone on orebody extraction. Some of these are discussed, together with current trends in the southern areas where orebody geometry and hence mining methods change markedly.Recent developments in ground support techniques, such as cable dowel reinforcement, have significantly improved ground conditions in the contact zone. An example of the methods employed to improve knowledge of ground behaviour is presented. The trend towards increasing automation and larger equipment requires larger excavations; consequently ground support practices and knowledge of ground behaviour must continue to advance. Rock mechanics investigations will remain an essential part of the mine design process.

Jan 1, 1990

Exploration for economic nickel sulphide mineralisation has often been directed by rationalisations based on poorly understood genetic models. Among those that have enjoyed popularity over the past decade are the "layered gabbro" model and the "basal ultramafic" or Kambalda model. The new discoveries in the Mt Keith-Agnew area could well become a model for future nickel search. Exploration based on even the crudest state- ment of the Kambalda model - prospect the basal contact of Archaean ultramafic complexes for gossanous expressions of sulphide mineralisa- tion - has met with remarkable success. Refine- ments to this model, besides satisfying the geology of any particular deposit, have the major virtue that many of the genetic options - magmatic segregation, hydrothermal transport, sulphurisation, replacement sedimentary, structural control, etc. - are still open. Recent descriptions of highly magnesian silicate melts associated with the ultramafic rocks, do however, place some constraints on the formation of these deposits. Further evidence, from experimental studies on sulphide-silicate and sulphide-oxide phase relationships, and nickel-iron exchange in pyrrhotite, is taken with descriptions of sulphide nickel occurrences in Western Australia to examine genetic models for existing ore bodies.

Jan 1, 1972

By Li YQ, Yoon RH

The photoresponse of natural mineral pyrite and galena electrodes has been studied in aqueous solutions on freshly fractured surfaces (some fractured in situ) using moderate overvoltages. When fractured in situ, the electrode potential of both minerals instantly drops several tenths of a volt. Pyrite exhibits a spontaneous anodic photocurrent at fracture, which indicates upward band bending (depletion layer) on the n-type electrodes. The negative surface charge responsible for the depletion layer is believed to arise from a surface state that is intrinsic to pyrite surfaces, possibly modified by hydroxide ion adsorption. The flat band potential, Vty, of pyrite is at approximately -1.0 V (SCE) at pH 9.2 but to reach V(b, pyrite has to be cathodically decomposed. In contrast, galena assumes the flat band potential at fracture. Subsequent polarisation of galena at potentials positive of Vth produces an anodic photocurrent (upward band bending) and polarisation negative of Vro a cathodic photocurrent. Most of the galena electrodes studied were degenerate n-type and at potentials negative of Vtb, no cathodic photocurrents are observed, indicating the bands cannot be bent downward, consistent with the Fermi level at the surface merging with the conduction band edge near Vn,. Several were close to intrinsic, with the photocurrent changing sign near Vn,.

Jan 1, 1993

Integrated geological interpretation of aerial photographs and Landsat images revealed that the gold mineralisation at Kyauk Pahto took place in a narrow zone of tension fractures within part of a previously unrecognised dextral wrench fault system. The latter is the wider manifestation of the well known Sagaing (right-lateral) strike-slip fault which has a length of more than 1 000 km, and it demarcates the boundary between the Indo-Australian and Asian plates. A subtle, right-handed kink affects the full width of the Sagaing Wrench-fault System at about the latitude of Kyauk pahto, and the extra dilatancy imposed on the tension fracture zone facilitated episodic ingress of mineralising hydrothermal fluids by "seismic pumping".

Jan 1, 1987

By Draper J. J, Lang S. C

Regional geological mapping and facies analysis of the Late Devonian to Early Carboniferous Keelbottom Group of the Burdekin Basin have resulted in a depositional model representing six siliciclastic-carbonate facies. The six facies represent alluvial fan, braidplain delta, siliciclastic shoreline, siliciclastic shallow marine, restricted siliciclastic/carbonate shelf, and carbonate shoal depositional environments. These facies are identified in the Star beds which are equated with and included in the Keelbottom Group in this paper. Facies are repeated throughout the Group, as a result of two transgressive-regressive cycles.The first transgression recognised in the Keelbottom Group began in the mid-Famennian, and followed deposition of the Late Devonian Dotswood Group. It was marked by the deposition of Siliciclastic Shoreline facies in the basal Myrtlevale Formation, which was succeeded by Siliciclastic Shallow Marine facies at the peak of the transgression. The return of Siliciclastic Shoreline facies in the upper part of the Myrtlevale Formation marked the onset of the first regression, which resulted in the progradation of Braidplain Delta facies from the northwest of the basin. During the peak of this regression, deposition in the western part of the basin was dominated by Alluvial Fan facies.

Jan 1, 1990

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 Mostyn G

In the last three decades various theories have been presented to allow the estimation of the force required to cut rock. These have generally relied on an hypothesised mechanism of chip formation.The paper presents results of an experimental program completed on an unjointed artificial rock in which the force and chip geometry were measured during deep cutting with a quarter scale bulldozer tyne. The program included various depths of cut and artificial rock of varying strength. The experimental results are compared with predictions based on three expressions for cutting force. Generally the measured forces are within the range of those predicted but none of the methods predicts the cutting force with any accuracy. It is considered that the discrepancies are due, in part, to the fact the that actual shape of the chip formed in deep cutting is quite different to that assumed in developing the theories and thus the theories cannot be expected to predict the cutting forces. It is concluded that Evans and Nishimatsu's theories predict lower bound estimates of the horizontal cutting forces. Deliac and Fairhurst's approach appears to over estimate the forces required to cut rock. New methods of prediction are required based on the observed mechanisms of failure.

Jan 1, 1993

By Miller J. D

The mechanism of adsorption of gold from alkaline cyanide solutions by carbon has been the subject of much research over the past decade. In this paper, the nature of the gold cyanide adsorption phenomenon is investigated, particularly with respect to carbon substrates and associated surface adsorp- tion sites.

Jan 1, 1991

By Flann R. C

A small modification to current industrial practice should lead to better nickel powders for use in alloying, electroplating, and powder metallurgy. Nickel powder compacts sold for alloying are not always suitable for electroplating applications, since some presently used commercial powders will expand on sintering. Further, such nickel powders are unsuitable for use in the production of powder metal parts, because of expansion during heating of the near-net-shape preforms. Research in these laboratories has enabled the elimination of expansion, and led to techniques for the production of compacts suitable, in particular, for commercial use in both alloying and electroplating. The techniques include: powder pretreatment, cold pressing and sintering, hot pressing, and hot pressing and sintering. In this way compacts are readily prepared with densities of at least 93 per cent of solid nickel, and these, when used as anodes in Watts general purpose and bright baths, give both cathode current and plating efficiencies of 90-98 per cent.

Jan 1, 1979

By Murphy MW, Klaric SD

The history, operation and design of the Secor continuous rod production process is described. The effective operation of the plant is influenced by accurate monitoring and control of molten metal properties, mould release application, coolant application and composition and correct setting of all operating parameters. The continuity of operations, which is an essential feature of this type of plant, is also greatly influenced by the service life of wear parts in the operation. This paper deals with three principal wear parts which come into direct contact with copper during operation, these are:

Jan 1, 1985

By Andrews JRG

Chrysotile asbestos is a valuable resource. Used as a reinforcement in asbestos cement, products are obtained which are cheap, are not attacked by vermin, do not rot or support growth of fungi and are unaffected by water or humid conditions. Such products are of great value in the developing countries where inexpensive and durable building materials and pressure pipe are very important to development, housing and water supplies. Concern over the adverse effects of inhaling asbestos has led to the introduction of increasingly stringent controls world wide on the quantities of airborne asbestos per- missible in the occupational situation. Wet processing has the potential for virtually eliminating the environmental concerns with asbestos dust both in fibre production and in the materials handling section of the manufac- ture of asbestos cement products. In addition, high efficiencies associated with wet process- ing mean that better yields are obtained and that the tailings which are dumped have a lower residual asbestos content. Since early 1977, ICI Australia and Woodsreef Mines have been engaged in a programme of research to develop and evaluate a wet mill- ingprocess to produce, from ore and existing tailings, high grade fibre suitable for use in asbestos cement products. The process has been developed through microscopic studies, labora- tory bench scale experiments, work in a small scale semi-continuous plant and product evalua- tion on experimental size Hatschek asbestos cement machines. A prototype mill with a normal feed rate of 1z tonnes per hour and capable of producing pipe grade asbestos from Woodsreef ore has been constructed and was operational from January, 1982 to July, 1983. A range of asbestos cement products have been made successfully on full scale Hatschek machines using fibre from ore and tailings milled in the prototype mill. Economic evaluations indicate that a wet process mill would be cheaper to build, operate and maintain than an equivalent dry process plant. A commercial plant has been designed 1. Manager New Process Development, Woodsreef Mines Limited, Barraba, Australia. 2. Senior Lecturer, Department of Chemical Engineering, Monash University, Vic, Australia. formerly Senior Research Officer, Research Department, ICI Australia Limited

Jan 1, 1986

This paper will describe the exploration project which led to the discovery of the La Escondida porphyry copper deposit in northern Chile and will serve as companion paper to the description of the geology of Escondida being presented by J M Ojeda. The author would like to express his appreciation to Robert Hickman, Chairman of Minera Escondida, for permission to present this paper.In July 1978, a proposal was made by J D Lowell to Robert Wheaton, then Exploration Manager of Utah International, that Utah fund a "grass roots" program exploring for porphyry copper deposits in northern Chile. Wheaton expressed interest, and it was agreed that Getty Oil Co also be invited to participate. A joint venture agreement for the Atacama Exploration Project was signed January 1, 1979, between Utah, Getty and Lowell. The project was managed by Lowell who reported to a management committee which through most of the project consisted of Lowell, Francisco Ortiz, Robert Wheaton, Maurice Young, Sigfried Muessig and Louis Rove. Oliver Warin and Jim Bratt participated in the committee in the last phase of the contract. Special thanks are due Louis Rove of Getty and Maurice Young of Utah who made contributions throughout the course of the project. Francisco Ortiz was resident manager through most of the project.

Jan 1, 1990

By Hilde TWC

Synthesis of GLORIA side-scan sonar and other geophysical data has provided morpholo- gical and tectonic details of the interaction between the Nazca and South American plates along the Peru Trench (80S-15¦S). Our analyses suggest that a new propagating rift of the Galapagos type is evolving along the Mendana Fracture Zone (MFZ). Subduction induced rift- ing of the Nazca plate is accompanied by organized seafloor spreading for the last 3 Ma at least. GLORIA sonographs and bathymetric mapping show an 8-10¦ divergence in MFZ width towards the Peru Trench. The fracture zone comprises numerous ridges and troughs and a lack of sediment cover in the axial part. Young magnetic lineations (anomalies 1-2A) are observed within the fracture zone wni.cn are orthogonal to the older Nazca plate lineations. The central anomaly narrows west- ward and can be observed up to 400 km seaward of the trench whereas anomaly 2A is terminated about 200 km from the trench axis. Recent SeaMARC II sonar mapping in the region shows large igneous blocks in the Trench axis to the north of MFZ but absent to the south. We believe these blocks represent young seafloor of MFZ rift/spreading center broken off from the ridges as they subduct along the Peru Trench. The MFZ rift is propagating west- ward at a rate of 115 km/Ma (25 km/Ma relative to the South American plate). Given the present rates of accretion at the East Pacific Rise and of propagation along MFZ rift, the Nazca plate will be divided into two parts in about 35 Ma.

Jan 1, 1987

By Munro DL

The Mary Kathleen uranium deposit is in north-west Queensland, approximately halfway between the townships of Mount Isa and Cloncurry, at long. 1400 009 E and lat. 200 44' S. The deposit Iwas discovered by prospectors of the Walton McConachy Syndicate early in July, 1954, and climaxed a very intensive ground search by hundreds of part-time prospectors. during the uranium boom from March to July 1954ò Numerous small deposits, mostly in the vicinity of Mount Isa, were discovered in various rock environments, but Mary Kathleen is the only large deposit and, apart from a few tons of hand sorted material from the Milo lease, is the only deposit that has been worked. Exploration of the surrounding area, and proving of the economic worth of the deposit, were conducted from the time of discovery until February 1956 by a geological team camped near the deposit. Proving was carried out by drilling a pattern of vertical and inclined diamond drillholes at fifty-foot centres over the outcrop. An adit was driven eastwards through the deposit. Metallurgical research and design work in the South Australian Department of Mines Adelaide Laboratories were based on core samples and bulk samples from the deposit. The signing of a contract in March 1956 with the British Atomic Energy Authority to supply 4500 short tons of uranium oxide allowed mining to commence, and enabled the planned construction of water supply, township and treatment plant to proceed. The open out mine and plant are now serviced by a modern township, four miles away, which is connected to Cloncurry and Mount Isa by road. Although little field work has been done since the exploration phase, this paper differs in interpretation from a previous paper (Matheson and Searl, 1956) in that it is based on a revised structural inter- pretation (Compana, 1958), detailed mapping of progressive exposures in the open out, and a re-examination of diamond drill cores.\

Jan 1, 1968

Instantaneous outbursts of coal and gas have occurred in Australia in the Sydney Coal Basin since 1895 and in the Bowen Coal Basin since 1954. The largest has been about 500 tonnes of coal and so their magnitude and character have not approached those experienced in some other countries. The occurrence of CO2 with some Australian cases provides some similarity with the worst affected areas in France and Poland.The proneness of seams depends on coal rank and seam gas composition, among other factors. The proneness of places depends on depth, structure, intrusion, tectonism and other factors affecting the geometric, physical and chemical uniformity as well as details of mining. As a phenomenon due to gas and stress, prevention can be achieved by relief of high gas and/or stress condition. Alternatively, controls can be applied to render mining safe for personnel. Unfortunately day-to-day prediction is not widely and reliably achieved to allow selective use of prevention or control. The initial rate of desorption is the most promising day-to-day indicator.Various researches include gas conditions and parameters, stress and failure conditions and parameters, coal variables and geological variables in relation to prediction, prevention and control. Some assistance in research may derive from study of analogous phenomena of instantaneous outbursts of salt and other rocks and gas. It is concluded that in the Sydney and Bowen Basins, any coals with less than 30 per cent Volatile Matter (VM) ash free dry (afd) at depths over 200 m could be prone. Proneness increases with depth, with lower volatile content, with geological disturbance including faulting, intrusion and recent tectonics, with increased CO2 in seam gas, with narrow work and with other factors. Much more research is needed.Unfortunately outbursts are needed too, to provide the research with realistic data. With the problems of mechanism and prediction still being unsolved much research remains to be done. No present aspect of research is satisfactorily resolved.

Jan 1, 1983

By Mallett CW, Hobbs BE

This study examined the structures of the Bowen Basin in central Queensland, Australia, by a series of lineament analyses. These studies were carried out using published geological maps, NOAA-AVHRR imagery, and LANDSAT MSS. Comparisons between these various data sources allowed the discrimination of the nature of the observed lineament sets and the time of their development. These data, which have been verified by field work, allowed the development of an integrated structural model of the Basin as an area of compression. This is considered in the light of a plate tectonics framework for northeastern Australia. The study showed that geological structures of great significance to mining operations, such as strike slip faults and large thrusts, could be identified and mapped using a combination of satellite imagery and field investigation. The small scale view of the satellite imagery also facilitated the development of a structural model for the Bowen Basin.

Jan 1, 1986