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From the ventilation aspect, there is a basic difference between advancing and ezreating longwall layouts. Particular rroblems with retreating, using differing mining methods and layouts include high gas emissions, spontaneous combustion and -radients. There is an acceptable method of crntrolling the environment at the return end a retreating longwall face without the use a multiple heading system. Incorporated in the design is the facility to practice xtensive methane drainage, thus ensuring a ntrol of the rate of methane emission into the main roadways. Case studies highlight varying mining editions under which the proposed system of Ctised.

Jan 1, 1982

By Gunther L. M, Rich N

Remapping of the Burdekin Basin has resulted in the subdivision of the three formations (megafacies) previously recognised in the Late Devonian Dotswood Group. Nine dominantly volcaniclastic facies are now identified within the three megafacies, representing coastal plain, floodplain lake, alluvial plain, ephemeral lake and alluvial fan depositional environments. The Dotswood Group was deposited during a major regressive phase that began at the end of the Givetian, continued throughout the Frasnian and ended in the early Famennian.The proposed depositional model completes a southeasterly progradation of coastal plain facies over shoreline and nearshore marine facies established in the underlying Fanning River Group. Uplift and associated acid-intermediate volcanism to the south of the Burdekin Basin, resulted in the deposition of a volcanogenic alluvial fan facies locally preserved along the southwestern margin of the basin. Tuffs and ?ignimbrite were deposited in widespread floodplain lakes which lay behind the coastal plain. An alluvial plain traversed by southward flowing rivers, formed the northern margin of the basin.

Jan 1, 1990

The theory of declining optimimum cut-off grades is more than 25 years old, but for a number of reasons it is still not widely used in industry. A lack of faith in the veracity of estimated grades is not in itself a reason to abandon any attempt to optimise cut-off grades. The use of declining cut-off grades has been thought to cause high-grading, but in fact this is only true if an artificially high discount rate is used in the calculations. Perfect application of an optimum cut-off grade should ensure that only ore generating more than a minimum net return is mined, and that as much as possible of the ore capable of generating that return is mined. Therefore differing mining costs in different parts of some underground mines necessitate local modifications to cut-off grade. Optimisation of cut-off grade is of necessity an iterative process. Integration of that process into a feasibility study need not be excessively time-consuming. A number of approximations can be made to speed the optimisation (any attempt to achieve a high level of accuracy is probably doomed to failure by a lack of precise cost and price projections). A procedure is outlined for optimising cut-off grade during planning of a typical underground mine.

Jan 1, 1991

By Tozawa K, Nishimura T, Sasaki K

Liquidus surfaces in a part of the systems ZnO-PbO-Si02 and ZnO-"FeO"-SiO 2 were constructed by the quenching method. The ex- periments were carried out in air in the system ZnO-PbO-Si02. In the part investigated the primary phases were three ternary compounds (PbO.ZnOòSiO2, 2PbOòZnO.2SiO2 and barysilite), three lead silicates, Zn2SiO4 and SiO2. Iso- therms on the liquidus surface of each primary phase field were determined from 750 to 1300¦C. In the system ZnO-"FeO"-SiO 2 the experiments were carried out in an atmosphere of purified nitrogen. In the part investigated the primary phases were Fe2SiO4, Zn2SiO4 and Si02. Iso- therms on the liquidus surface of each primary phase field from 1150 to 1300¦C and the ternary eutectic (1130¦C, 15.9% ZnO, 48.2% "FeO" and 35.9% Si02) were determined.

Jan 1, 1980

The mining industry is facing tremendous economic challenges. Fluctuating and depressed commodity prices, the ever-increasing pressure from environmental legislation and the competing global opportunities for capital investment are placing enormous strains on every aspect of the mining business. At the same time, mines are generally becoming older and deeper with all the logistical and rock mechanics difficulties that this entails. In the face of these new challenges the industry looks to technological advances to make operations more efficient and profitable. One approach is to develop and implement highly automated and computerised equipment as part of a trend towards major reductions in the underground workforce. This approach requires more capital investment rather than less and requires a more sophisticated and well-educated workforce with skills which are generally in high demand in society as a whole. It is difficult to see how the benefit that can be gained from such technology can justify the expenditures necessary to make it operate reliably underground on a daily basis. Nor is it easy to foresee how the mining industry, based as it is often in very remote areas, will be able to hire and retain sufficient numbers of people to maintain such fleets of equipment. Another approach, and the one which I favour, is the implementation of much greater control over the whole of the mining process. Mining is essentially a very simple process - we break rock and move it. The most cost-effective means of moving and processing the mining product depends entirely on the way it is broken - it depends on primary fragmentation by blasting. I propose that the way forward for the industry in the face of our present difficulties, is not new technology but is to utilise the level of technology which currently exists in ways which have traditionally been regarded as too difficult or too inflexible - improved fragmentation and the use of conveyors. The technical success of this approach depends on the complete re-design of the ore handling system from the face or stope drawpoint to surface. The fundamental issue which determines the success of this approach is designed fragmentation.

Jan 1, 1995

By Torabi S. R, Daly C. R

Wind blast is the sudden movement of air displaced by the massive collapse of roof rock in underground openings and is experienced as a high velocity flow of air through adjacent workings. The initial flow in the outbye direction is often followed by 'suck back', that is a reverse flow of air towards the newly created void. As part of the Wind Blast Project, undertaken by The University of New South Wales, Department of Mining Engineering, a physical model was constructed. One of the functions of the laboratory wind blast model is to provide insight into the dynamics of the interaction between the falling strata and the air being compressed below. During a collapse, some air is expelled into the surrounding roadways while the remainder penetrates towards the top of the roof elements. In this paper two aspects of the rock mass properties which influence the phenomenon are considered: - Flow paths through the falling roof element, ie the permeability of the roof element; - Bed separation prior to the fall which introduces a void above the roof element. A series of tests was carried out utilising the physical model in order to investigate the relationships between the flow of air through the simulated roadways, the variations in gauge pressure above and below the falling roof element, and the acceleration and terminal velocity of the latter, all as a function of the flow paths through the roof element and of the extent of the void above. The results of comprehensive tests using the wind blast physical model suggested that the time history of outbye air flow in the simulated roadway comprises two distinct phases. a) A primary phase, characterised by a high velocity flow of air which exhibits a peak and corresponds to the period during which the roof element is accelerating. The peak air velocity is related to the acceleration of the roof element. b) A secondary phase, characterised by a residual air flow of a lesser velocity than in the primary phase and corresponding to the period during which the roof element is falling at its terminal velocity. The velocity of the residual air flow is directly proportional to the terminal velocity of the roof element. In a monolithic collapse of a roof element it was shown that the presence of flow paths in the roof element increased the air velocity in the roadway in both the primary and the secondary phases. The presence of an air-filled void above the roof element, on the other hand, influenced the air velocity only in the primary phase by increasing the peak air velocity. The overall duration of the process was however decreased as a result. 'plug type' collapses, where roof failure extends to the ground surface, potentially generate the highest peak air velocities likely to be encountered during wind blasts.

Jan 1, 1995

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

Optimum selection of explosives by means of monitoring explosive performance can lead to increased profitability through the control of fragmentation, a reduction in hangingwall and footwall damage and overall drill and blast costs. Studies conducted at the Mount Lyell Mining and Railway Company underground copper mine evaluated in situ the performance of four explosive types. Measurements included monitoring the levels of induced shock energy and the attenuation thereof with distance. The velocity of detonation (VOD) of these explosives was also measured using in-hole techniques. Assessment of these results, together with a knowledge of the rock mass strength, facilitated the selection of an explosive that was best suited to the given rock mass conditions.

Jan 1, 1995

A review is given of the development of the author's ideas on the relationship of ore occurrence to regional dislocations in the earth's crust, presently identifiable in particular areas as linear discontinuities in patterns of geological and geophysical data. Ideas originating from field observations in Broken Hill were developed in conjunction with three-dimensional kinematic deformation models which were devised to simulate rock structures, and to illustrate their response to assumed linear and planar movements at the scale of mine and regional geology. These led to the study of linear features in the pattern of Broken Hill district geology, and to the observation that the Broken Hill lode occupies a "cross-roads" position at the intersection of regional geological lineaments where they cross through and deflect the host rocks. A genetic association was therefore proposed. The recognition of significant regional lineaments requires special techniques and treatments of field data originally developed for the Broken Hill situation. The subsequent application of the work to the Western Australian shield revealed that known major nickel and gold deposits also occur where the host rocks are crossed by one or more regional lineaments. These lineaments were recognised as part of a continental tectonic pattern of major linear trends with which major ore deposits are associated. The ideas were later used in exploration leading to the discovery of the Olympic Dam deposit at Roxby Downs, South Australia, which is related to regional lineaments.

Jan 1, 1983

The Great lady gold deposit presented the challenge of providing a new grade control system for an usual type of orebody in the Eastern Goldfields. Mineralisation occurs as secondary enrichment about a quartz sand - granite saprolite contact 30m below surface. The ore horizon, which averaged 2.5m thickness, was near-horizontally disposed in contrast to the typical steeply dipping, shear hosted deposits of the region. A trial mining operation was undertaken on the richest, most continuous portion of the deposit to test the economic viability of this type of orebody. Controlling and minimising vertical ore dilution was considered crucial to the profitability of the operation.An understanding of the grade distribution combined with the practicalities of mining produced a grade control system which allowed for the mining of 1/2rn composited grades on level lm benches. Ore mining was combined with strict monitoring of levels, truck destinations and ore boundaries. Ore reconciliation results showed this system to be effective.

Jan 1, 1990

By Elford H. S, Hughes J. F

The object of this paper is to bring before Members of the lnstitute the very important and much discussed question of scientifically prospecting for ores, oil, coal, etc.The paper is divided into three sections:SECTION l - Description of Geophysical Prospecting methods.(1) Sound-Vibration.(2) Magnetic.(3) Gravitometric.(4) Electrical.(a) Equipotential.(b) Electro-magnetic.(c) Schlumberger.(d) General.SECTION II - General discussion of Cicophysical Prospecting.SECTION III - Appendices.(1) Systematic summary of methods of survey.(2) Table of electrical conductivities.(3) Bibliography.SECTION I - DESCRIPTION O:F GEOPHYSICAL PROSPECTING METHODS.(1) SOUND-VIBRATION.THE transmission of sound waves or vibrations underground will depend on at least three factors: (a) Type of Rock. - Hard, dense rocks wiII transmit sound waves much more quickly than softer, more porous rocks. In the former the speed may be eight times that of the latter.(2) Uniformity of Rock. - Any variation in the texture, hardness, etc, wiII have an effect on and direction of transmission of the waves.

Jan 1, 1927

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 Garland W

Access to geoscience reference informa- tion including mining and mineral processing has increased considerably in the last five years in Australia. This has been due principally to the use of computer-based information storage and retrieval systems. The main reference data base for the mineral and petroleum industries and disciplines in Australia is the Australian Earth Sciences Information System (AESIS), cooperatively developed and coordinated by the Australian Mineral Foundation (AMF). AESIS is created on the CSIRO computing network (CSIRONET) which has a CYBER 76 host computer located at the CSIRO Division of Computing Research (DCR) at Canberra. Data entry was until recently carried out by AMF using a dedicated line through the Adelaide CSIRONET node to the CYBER 76 interactive system. Data entry is now done directly at the AMF on a DEC PDP 11/44 mini computer that is also a host work station on CSIRONET. Data collection via magnetic tape media input from other computer-based systems is under development. The software used for data entry and management of the data base was developed by CSIRO CILES Systems Development Group. For public interactive online use the AESIS data base is transferred by tape to AUSINET - the Australian information net- work run by ACI Computer Services, Melbourne, where the data base is converted to a form suitable for the IBM STAIRS software. CSIRO facilities at DCR Canberra are used to produce computer type-set camera ready products and output in microform, on magnetic tape or as graphic display. Keywords: Earth sciences information, Computer applications, Information storage and retrieval, AESIS, Data bases, Australia.

Jan 1, 1983

During the past 18 months a rock mechanics project has been in operation at Renison Limited. The project was established to identify and investigate key problem areas that would affect future production at the Renison mine. An in-house approach was adopted, using shall compact equignent, to investigate ground behaviour. Information on the rock stress field was considered to be particularly important for an understanding of ground behaviour. A high horizontal stress component exists, which enables large flat dipping spans of hanging wall to be opened up, with support being provided by post pillars. The amount of support provided by these post pillars has been found to be low.

Jan 1, 1982

By Boger D. V

Two industrial case studies in which detailed investigation of the flow behaviour of mineral slurries is used to assess the feasibility of pipeline solid transport are described. The first example deals with the pumping of highly concentrated bauxite tailings to disposal, while the second exam- ple examines the possibility of transporting high-density Victorian brown coal slurries which previously has been thought as uneconomical. It is demonstrated that these typical solid handling problems can be solved by a good understanding of the rheology of suspensions.

Jan 1, 1989

By Cocker J, Urosevic M

Seismic methods have become common for the detection of low-throw faults ahead of underground coal mining. Surface seismic methods cannot theoretically be used where dykes occur, because seismic waves transmit from the surface down to the seams, and reflect back to the surface. Consequently, where sub-vertical structure such as dykes occurs, the surface seismic method fails.The ability of seismic methods to image dykes depends on the geometry used, the dyke thickness and the seismic wave propagation mode in relation to dyke composition and internal structure. Surface seismic methods find it difficult to distinguish between faults/fractures and very thin dykes (1-2m in thickness) when the dyke's thickness is less than the seismic wavelength. Consequently, borehole seismic methods have to be used to detect the presence of such thin dykes.

Jan 1, 1998

By Frith RT, M D. Goodz

Drilling has been accepted as a major exploration tool. However its use in mine planning and development has been overlooked.This need for drillhole data was highlighted during the redevelopment boom of the central Victorian gold mines. During the 1980's numerous old mines were evaluated and successfully drilled to yield mineable parcels of quartz reefs close to existing workings.Invariably the initial decision was always to attempt reopening and rehabilitating existing access. The four case studies described have proceededsufficiently to show that major cost savings would have been made if underground drilling had been used as the main tool in mine planning.Savings not only in expenditure, but in the time required to make key decisions. In two cases the mines would have experienced far earlier expansions in production. In one case the mine would be currently producing rather than awaiting further finance. In the fourth example, the decision to case development would have been much earlier providing capital to other projects.

Jan 1, 1990

By Susanto A

As part of the current NERDDC funded project studying Dragline/Hopper/ Crusher/Conveyor systems for overburden removal, an investigation was carried out to assess the feasibility of automating the swing-to-dump phase of the dragline digging cycle in order to main- tain consistent performance of spotting the bucket above the hopper prior to dumping. The study involved design of automatic position controls for the hoist, drag and swing drives and simulation of detailed mathe- matical models of the three electromechanical systems and their associated electrical control schemes. The design of the hoist and drag systems to position the bucket in the boom plane is relatively straightforward. Simulation results show fast and accurate performance, with no evidence of interaction between the two drive systems through the ropes. The design of the swing position control system involves special strate- gies to cater for variable inertia and to damp the pendulum oscillations of the bucket. The use of a bucket pendulum model and variable dynamic compensation embedded within the feedback control loop, along with optimal speed/angle slowdown trajectories, has yielded fast and damped positioning responses under simulation.

Jan 1, 1989

By Lu T. K

A new type of rockbolting system, the self drilling rockbolt, has been studied to develop a 'single pass' bolt for use in rockbolt installation in underground engineering. This single pass bolt forms the basis of a Rapid Face Bolting system which will reduce the amount of time spent in securing a roof during the operation of a continuous miner in the development of a panel.The installation efficiency and anchorage tests were performed in the laboratory on the self drilling bolt and the traditional resin anchorage. bolt. The results of both bolts are cmmnared.

Jan 1, 1993

By P Bethune

Back Creek is a tributary of the Condamine River. It flows in a northerly direction across the existing Commodore coal reserves. The diversion of Back Creek was proposed to minimise sterilisation of the reserves. The approval process required a Waterworks Licence application, under the Water Resources Act 1989 (Qld), for the construction of a stream diversion channel and floodway. The diversion was designed using the æreference reachÆ approach, which mimicked existing properties of Back Creek. The following design standards were developed for the diversion: the diversion corridor width was 500 m; the diversion geometry was specified for both the low-flow channel, and the floodplain; material properties were specified for both the low-flow channel lining and the diversion bund; compaction standards for both the low-flow channel and floodplain were set; and the diversion rehabilitation included a riparian corridor and pasture land with clumps of native trees and shrubs. The following performance criteria were developed for the diversion: velocity regimes were replicated for the design events considered, in an attempt to avoid increasing the diversion flow velocities in comparison with the existing creek flow velocities; sediment transport calculations indicated that no significant change in sediment transport was expected within the diversion; overburden settlement estimates for the spoil placed in the corridor were summarised, and will be monitored throughout the construction process; geotechnical stability of the proposed Eastern Pit Buttress and the diversion bund configurations was confirmed; and groundwater impacts were assessed. Construction techniques, monitoring and further investigations are also discussed in this paper.

Jan 1, 2003