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By Goto T, Sato K, Mori N

A field investigation by making use of the seismic method has been carried out in order to comprehend the mechanism of rockburst and gas outburst and their predictive measures. The seismometers were so arranged both on the surface and underground as to enclose a mining panel. Seismic signals detected by the array were recorded and processed by the 32-kwords computer system. At present the system is available for analysing the source location and Richter's scale of each event and for visualizing the distribution of seismic foci and released energy at any mining stage. The magnitude distribution of events can be regarded as a comparable index of the seismic activities among mining panels. An analysis of the spatial density distribution of seismic energy in the mining panel can be useful to distinguish a highly stressed zone from stress released areas. The energy released curve or the rate of energy release determined from seismic data is also a good indication of the seismicity.

Jan 1, 1980

By Kerkhoff G, Wood J

The maximum gas emission into underground workings can be predicted by the use of established methods which have world wide recognition. Changes in gas emission and the influence of the gas and geological environments during longwall mining at Pacific Colliery, were found.to be a typical. The relationship between longwall mining and gassy conditions is found to vary from the European experience because of the different mining and geological conditions encountered, and the higher productivity achieved, by single longwall panels in Australia.

Jan 1, 1988

By L M. Lobato, J C. S Seoane, F J. Baars

The Carajßs Province presents several volcano-sedimentary sequences that comprise the Itacai·nas Supergroup. The rocks represent bimodal volcanism, and clastic and chemical sedimentation in relatively unstable basins subject to recurrent structural events with subsidence and volcanism. The Grpo Parß Group represents one of these sequences with mafic volcanic rocks that enclose discontinuous jaspilite lenses, with development of large high-grade orebodies (Fe >65 per cent). This unit is named the Carajßs Formation and presents peculiar characteristics compared to other iron districts in the world, thereby departing from the classic Lake Superior or Algoma iron formation types. Owing to the dense vegetation, lack of outcrops and harsh landscape, the structural analysis of the district can only be accomplished by combination of regional field work, detailed structural work on the open pits, and remotely sensed image interpretation, in this case Landsat ETM7, JERS-1 images and the SRTM digital terrane model. The regional trend of the several sequences of the area is approximately N-S and the structure is dominated by a flattened flexural fold system with axes moderately dipping WNW, intersected by several strike-slip faults subparallel to their axial plane. The Serra dos Carajßs represents an s-shaped synform-antiform pair, herein named the Carajßs Fold. This regional structure is partially disrupted by the Carajßs Shear Zone that divides it in the northern (Serra Norte) and the southern (Serra Sul) Ranges and also probably prepared the terrane with the development of pathways for mineralising hydrothermal fluids forming large high-grade massive iron bodies. Syntectonic granitic bodies played an important role in the structural evolution of the area as well. They caused localised ductile flattening deformation and thermal contact metamorphism in surrounding terranes. The Estrela pluton, for instance, was responsible for the discontinuity of the regional trend between the Serras do Rabo and Leste. The Carajßs Province is regionally the upper crustal product of a very shallowly eroded dome-and-keel geometry of Neo-Archaean volcano- sedimentary units intruded by syntectonic calc-alkaline intrusives and overlying pre-existing infracrustal rocks. The lithostructural data suggest continental-margin back-arc basin development and closure in an oblique collision belt, with N-S shallow crustal shortening, parallel to the inferred pre-existing strike of the stratigraphy.

Jan 1, 2005

By W R. Hancock

Control of complex machinery through the internet is investigated through the construction of a vehicle prototype developed using off-the- shelf hardware. The vehicle was able to be controlled remotely through the use of a client side interface connected to a steering wheel and foot pedals. By attaching sensors to the vehicle, data could be collected from which one could infer the effectiveness of such a control system. The effect of latency on control was monitored by the introduction of an artificial latency, simulating a wide variety of internet-related issues, such as unstable connections and dropouts. Sensor data could then be used to gain an understanding of how the system could be improved though either control or interface design. A path tracking experiment was conducted to gather controllability data and it was found that such a system is plausible within a reasonable range of latencies. It is expected an area of future research would be an extension of this current project, applying the information gained to real world control systems.

Jan 1, 2008

By Kellerwessel H, Oberheuser

Since its invention by Professor Klaus Schonert of the University of Clausthal, Germany, high pressure rolls comminution has attained near total acceptance as the preferred method of size reduction in the cement industry. Over 300 units have been manufactured worldwide. At locations where the system has been installed, considerable energy savings have been realised. These energy savings are generally in the range of 20 to 30 per cent compared to conventional ball mill circuits. However up to 50 per cent power saving has been achieved at some installations. This technology, with the exception of the diamond industry, has up to now had only limited success in ore processing. This has mainly been attributable to the abrasiveness of ores encountered in this industry leading to high wear rates. These high wear rates have given rise to an unacceptably short life time of the wear surface of the rolls, requiring regular replacement. A new wear surface has been developed which has shown to give a ten-fold increase in service life over conventional surfaces. This, together with developments made in machine design now give the units the ability to attain the high availabilities demanded by the mining industry, and therefore to allow this industry to achieve the considerable operating cost savings offered by the high pressure rolls.

Jan 1, 1992

Currently there is considerable interest in the production of DRI in Western Australia to take advantage of intense interest from the Asian market. Most DRI is produced using gas-based processes and is used as a feedstock in electric arc steel furnaces, otherwise known as mini-mills. This paper critically examines the technical and economic issues of various gas-based DR processes available today and recommends the most effective and attractive processes suitable for Western Australian iron ores.

Jan 1, 1996

The progress of longhole open stoping (LHOS) at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited (ZC/NBHC) is described. The design of a novel sloped wall longhole stoping method at NBHC which should allow the cuplete extraction of the orebody without the formation of pillars and with minimal dilution of the ore with sandfill is reviewed.

Jan 1, 1983

By Tilyard P. A

Recent exploration has established depos its of nickel sulphide in several areas of Western Australia. To assist in their develop- ment Amdel has investigated the beneficiation of many samples from these deposits and has estab- lished flowsheets for the recovery of nickel values by flotation. Metallurgical data are presented for the samples according to four factors which were encountered in their respective treatments.

Jan 1, 1973

By Brown K, Francis D

The Yallourn Open Cut Mine has recently commenced mining operations in the new East Field which will supply the 1450MW Yallourn W Power Station for the rest of its 30 year design life. The authors describe the design and implementation process followed during the rehabilitation of the areas disturbed by works associated with mining in the East Field. One area of the East Field, the old external overburden dump, has been of particular interest and is discussed in detail. A discussion on the fire protection considerations is included as these are critical and often misunderstood as being contrary to good rehabilitation design practice. Finally, the development of a master plan for the rehabilitation of the Yallourn Open Cut in general, incorporating the East Field work, is discussed.

Jan 1, 1992

By Shining Z

The strength and deformation of more than two hundred coal samples have been tested in the condition of triaxial compression. The regression equation showing the relationship between coal strength and pressure in the pores, as well as confining pressure, was obtained. The appropriate calculation for stress-strain curve was carried out. Further, an analysis shows the variation of coal strength and its modulus of elasticity in methane medium.

Jan 1, 1992

With the evolution rate of technologies, earthmoving equipment users are establishing vision statements for their operation out to and in some cases beyond 2000. Autonomous systems are receiving a lot of 'press' - and rightly so, as they hold a potential for achieving quantum leaps in productivity and cost gains. Caterpillar feels that it is important that the infrastructure of on-board systems are understood and can be utilised more in the near term to `grow' a user up to the stage of autonomous operation.

Jan 1, 1997

A portable surface impedance meter has been tested extensively over a wide variety of geological formations both in Australia and elsewhere. It has proved a useful geophysical too] for relatively shallow mapping (i.e less than 100 metres depth) of faults, intrusions, dykes and conductive ore veins and can be used as a depth probe for overburden and glacial ice. Case studies involving coal seam mapping at Collide (Qld. Australia), galena ore vein location at Zeehan (Tas. Australia) and glacial ice probing on the Brewster Glacier (South Island, New Zealand) are detailed. The first results of a similar unit using a lower frequency with consequential increase in depth of penetration will be presented. The application of VLF measurements to monitor blasting in mines and in the location of earthquake epicentres will also he introduced.

Jan 1, 1987

By Wright J. K

A description is presented of the results of reduction experiments using a laboratory reduction apparatus in which simulation of the gas and temperature profiles which occur in direct reduction shaft furnaces is achieved using microcomputer control. The apparatus allows continously changing reduction conditions to be impressed on lump or pellet samples to simulate the environment that is experienced by iron ore burdens during their transit down the shaft of a direct reduction furnace. Three pellet samples and three lump ore samples were reduced in the apparatus. Comparative reduction curves and strengths after reduction for the materials were obtained over a range of reduction temp- eratures using Midrex-type gas compositions. The resulting reduction and strength curves show considerable variation in behaviour and reflect the physical and chemical variations in the individual ore and pellet types. A comparison is made of the reduction rates and modes of reduction of the samples reduced under "conventional" test conditions using a single unchanging gas composition and the simulated shaft furnace reduction conditions. It was observed that the course of reduction is very different in the two procedures and the major influence of temperature on the strength of the reduced product is noted.

Jan 1, 1987

By Tran T

The kinetics of cementation of silver chloro-complexes from sodium chloride solutions onto copper and zinc was studied using rotating disc electrode system. The activation energies were found to be 10.8 and 30.5 k7/mole, in a 3M NaCl solution on copper and zinc discs, respectively. Higher dissolution factors were obtained on zinc disc, due to hydrogen evolution, whereas, copper dissolved close to the predicted values. Scanning electron microscope studies were conducted both on copper and zinc- cdiscs-to evaluate the deposit morphology and its effect on reaction kinetics. Two stage deposit growth was observed both on copper and zinc discs. Smooth, coherent initial deposit followed by tree-like secondary dendrites formed on copper, whereas, scattered bulbous initial deposit followed by porous dendrites was typical on zinc disc.

Jan 1, 1992

The future of the Tasmanian mineral industry can only be estimated from a knowledge of the past, and armed with this knowledge an orderly plan for the future can be developed. Brief mention is made of the major historical developments through to the present day, with past and future development areas clearly mapped. Areas of importance which have been discussed are divided into the mining of metals, fossil fuels and non-metals; and the process- ing and extractive industries. Discussion then follows on the current general non-insular pressures on the mining industry, the energy crisis, scrap, world shortages, new techniques, inflation, and the effects of exploration on the environment. This is then followed by a discussion of the advantages of Tasmania as a mining state and a cataloguing of the present exploration and some possible areas of future development. From this a suggested plan emerges for the future development of the Tasmanian mineral industry, to incorporate the latest technological advances and by planning to meet the challenge of survival and growth in a turbulent environment.

Jan 1, 1977

A failure criterion for coal is proposed in which a distinction is made between brittle and "pseudo-ductile" failure. This criterion is then used in the development of new equations for coal pillar strength, including a transition from brittle fracture to pseudo-ductile yielding. In addition, equations are obtained which allow the äritical minimum pillar dimensions to be calculated to avoid "catastrophic" and "ultimate failure". The use of these formulae is then demonstrated by comparing the results with pillar case histories derived from the literature.

Jan 1, 1986

By Denholm W. T, Rankin W. J

The reduction of zinc from lead blast furnace slags using hydrogen was studied at 1300¦C as part of a laboratory investigation of zinc fuming. To perform the experiments, 300 g "spent slag" was melted in a crucible. Hydrogen was then injected into the slag through a lance and fresh blast furnace slag was added regularly in small quantities over a period of 40 minutes. Zinc added in the fresh slag was reduced and the zinc level of the bulk slag attained a steady state value of between 1 and 9% after about 10 minutes, depending on the gas injection rate. Because of the high reactivity of hydrogen, bulk supply of hydrogen to the slag was the rate limiting step at the flow rates used and it is believed that the gas-slag reactions in the system were at equilibrium. A partially/stabilized zirconia cell with a Ni/NiO reference electrode was immersed in the slags during the experiments and the steady/state oxygen potentials of the slags were measured. By using the experimental oxygen potential values and calculated values of the steady state concentrations of zinc in the offgas, the activity of ZnO in the slags was calculated from the Gibbs's free energy change for the reaction:

Jan 1, 1989

By Setterfield TN, Jones GFP, Tua P, Davis B, Antonio M

The Emperor gold deposit occurs on the western margin of a 5 Ma caldera in a large, mafic shoshonitic shield volcano on the island of Viti Levu, Fiji. Products from two major pulses of post-caldera intermediate volcanism filled the caldera. Caldera collapse-related steep and flat faults and zones of shattered rock provided per- meable conduits for vertical and lateral fluid migration and favourable sites for ore deposition. One large hydrothermal system, operating concurr- ently with extrusion of the second pulse of resurgent volcanism, may have produced porphyry- style alteration within the caldera, epithermal mineralization at Vatukoula, and weakly minera- lized, siliceous veins and breccias in an outflow zone northeast of Vatukoula.

Jan 1, 1987

By Pollard D. M

Chalcopyrite samples from two different localities were leached in oxygenated mixed chloride-sulphate lixivants at elevated temperatures and atmospheric pressure. The oxidation of chalcopyrite was found to follow predominantly linear kinetics. The slope of the major region was dependent on stirring rate, oxygen flowrate and chloride concentration while only slightly dependent on the surface area of the sample leached. This region was found to predominate only at low temperatures. The oxidised chalcopyrite releases cuprous and ferric ions into solutions. Chloride ions complex these dissolved ions to effectively move the equilibrium of the leaching reaction to the right. When the level of chloride in solution was below 6 g/l, the unstable cuprous ions were found to reprecipitate with sulphur as covellite. When no chloride was present and the lixivant was a solution of sulphuric acid then ferric sulphates precipitated. The overall leaching reaction occurring in the leaching system is: CuFeS2 + 5H+ + 1.25 02 = Cu 2+ + Fe 3+ + 2S¦ + 2.5H20

Jan 1, 1987

By Whitworth NR, Fox MJ, Henley RG

The coal mass flow monitor was developed to measure the instantaneous mass flow rate of pulverised coal to the copper reverberatory furnace at Mount Isa. The instrument was calibrated with an isokinetic coal sampler which was installed immediately downstream from the coal mass flow monitor. Readings from the coal mass flow monitor were used to control the feedrate of coal to the furnace and this helped to stabilise the furnace operation.Coal samples obtained from the isokinetic coal sampler were also sized using a Leeds and Northrup Microtrac analyser. The coal size was critical to reverberatory furnace performance. These developments significantly improved the overall combustion control of the furnace and gains of ten percent were made in the furnace thermal efficiency. Testwork on an auxiliary arch coal burner is also reported.

Jan 1, 1985