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By Seeley D, Buckley N, Goodall J

Improving the performance and reducing the costs associated with export logistics chains is critical to the competitiveness of export coal mines. The fundamental practices associated with the use of export logistics chains made up of mine, trucking, rail and port operations are being challenged by the advent of third party operators on rail systems and the use of the Internet.Whilst individual mines can improve their processes to drive down their mining costs, they face major challenges in their endeavour to improve the performance of export logistics chains and reduce the significant logistics costs of moving coal from the mine to export ships, via the shared infrastructure of rail systems and ports. There is an increasing realisation that global competition is not only between mines but between coal export regions that are defined by their rail system and ports infrastructure.

Jan 1, 1998

By Pinter R

Several major routes connecting Northern and Southern Europe or Asia run through Austria. These highways have to surmount the alpine range which traverses Austria from west to east. In order to ensure safe driving conditions even in winter, tunnels, at times quite long ones, are necessary. Austria now has tunnels totalling 160 km in length. These tunnels are either already in use or just about completed. The Plabutsch tunnel near Graz will be one of the longest tunnels in the world: approximately 10 kilometers in length. It will be put into operation in the summer of 1987. Before construction could begin, soil and rock conditions had to be investigated by means of a test tunnel. Afterwards, excavation was begun to the full 100 m' cross section. The new Austrian tunnelling method with conventional blasting was used for the major part of the tunnel. It was necessary to have such a large tunnel cross section because a fully transverse ventilation system is installed for environmental reasons. In order to avoid air pollution from the tunnel, exhaust fumes are not allowed to escape from the tunnel portals but from two shafts, each with a diameter of 8.5 m. In this way, exhaust fumes must rise 90 meters or 240 meters before they reach the open air and will thus not affect the city. The ventilation system influences the size of the excavation, and especially the size of the ventilation caverns and the air shafts. All these factors directly influence construction and maintenance costs, and an economical optimisation leads to the appropriate dimensions for the excavation.

Jan 1, 1987

The specification for tender nominated the requirements for ore hoisting and servicing; this showed that one common duty winder could be selected. Foliowing the design of the shaft layout, the merits of fixed or rope guides were compared and the latter selected.The specification called for the supply and installation of the complete hoisting system. Construction of the winder tower and shaft bottom steel work had to proceed while mine development was in progress using the sinking winder and headframe. Guide ropes, winder ropes, and the sky shaft were installed in the shortest possible time, and as the shaft was not equipped with ladder-ways, a second means of access had to be provided.Very few problems were encountered witll the commissioning of the winder, and in the first 2 years of operation the only significant modification was to the circuitry associated witll the moving access platforms.Hoist rope tension checking and adjustment are simple, and non-destructive testing has shown no deterioration of these ropes. The operation of the balance ropes has been very satisfactory but cleaning presented problems in the early stages. Guide ropes have been trouble free and require minimum attention.Normal wear on the PVC rope groove inserts on the winder drum has been negligible.Since the commissioning on fully automatic ·control, the winder has operated with very few, minor delays.

Jan 1, 1969

The "Line of Lade", a generic term by which the great Broken Hill orebodies are collectively known, lies in the County of Yancowinna, New South Wales (NSW) at the south eastern extrenity of the Barrier Ranges. As the township of Broken Hill grew to a city (incidentally it was officially named Willyama but by exerting an enterprising community independence which is still evident today it outplayed officialdom and retained its descriptive name), two major areas of population developed, Broken Hill and South Broken Hill. These two main civic divisions are respectively north west and south east of their dividing line, the surface expression of the orebody. See Fig. 1. The border between the States of NSW and South Australia (SA) is drawn along longitude 1410 East whilst the city of Broken hill's official longitude is 1410 28' 14" East which means it is only 50 km from this political boundary. A latitude of 310 57' 03" South contributes to the harsh climate of high summer temperatures which is not mollified by any significant increase in altitude for Broken Hill is only 300 m above sea level.

Jan 1, 1983

Many problems result when coal mine shafts are built in complicated geological conditions and serious shaft lining ruptures have often occurred in the eastern part of China since 1987. Grouting is applied as one of the major measurements for shaft lining ruptures. However, as the general location of reinforcement grouting for shaft lining is deep in or near the bottom aquifer, while using cement grout as the grouting material, the grouting mostly belongs to fracturing grouting in deep alluvium. In these conditions, the mechanism and behavior of fracturing grouting has not yet been understood. From these points of view, this paper describes the mechanism of shaft lining rupture and fracturing grouting and then discusses the effect of grout injection on the stability of shaft lining by means of numerical analysis and field data obtained so far.

Dec 6, 2010

By Eyers G. C

Long Shaft was initially developed using a rail haulage system on every working level comprising battery electric locomotives and granby trucks loaded by rail mounted rocker shovels. Production was commenced using conventional hand held cut and fill mining methods. In an effort to improve productivity and reduce operating costs a mechanised cut and fill stoping method evolved to suit the wider sections of the orebody. To further improve productivity and reduce costs the mechanised levels of the mine are progressively being redeveloped to enable the use of trackless diesel haulage equipment. An added benefit of trackless haulage equipment will be the ability to place development mullock into stopes as Fill.

Jan 1, 1988

By A V. Nguyen

Spherical calcium dioleate particles (~10 ¦m in diameter) were used as AFM (atomic force microscope) probes to measure interaction forces of the collector colloid with calcite and fluorite surfaces. The attractive AFM force between the calcium dioleate sphere and the fluorite surface is strong and has longer range than DLVO (Derjaguin-Landau-Verwey-Overbeek) prediction. The repulsive AFM force between the calcium dioleate sphere and the fluorite surface does not agree with the DLVO prediction. Consideration of non-DLVO forces, including the attractive hydrophobic force and the repulsive hydration force, was necessary to explain the experimental results. The non-DLVO interactions considered were justified by the different interfacial water structures at fluorite- and calcite-water interfaces as revealed by the numerical computation experiments using molecular dynamics simulation.

Jan 1, 2005

A major problem in the continuous casting of aluminium killed strip steel is the incidence of black and grey lines in the strip surface caused by the alumina inclusions. One place for limiting the number of alumina inclusions is by providing favourable fluid flow conditions in the ladle so that the inclusions float out to the surface or adhere to the ladle wall. In laboratory equipment 20 kg of steel was melted in an alumina crucible of 14 cm diameter in an induction furnace. Deoxidation was carried out while the melt was constantly stirred by argon bubbling. Bubble frequencies were measured at the lance tip using a microphone technique. High speed cine photo- graphy was incorporated to measure melt top surface velocities. Experimental results indicate that the rate of removal of inclusions is a function of both the gas input and the power input. However due to unfavourable surface area to volume ratio, reoxidation of the melt took place. Some other experimental difficulties in working at high temperatures are also discussed such as lance design, melting arrangement and sampling techniques.

Jan 1, 1984

The progress between 1983 and 1989 towards Management Guidelines for R16 was extremely slow and painful because protection of the mining heritage was a new function and administrative activity not referred to in any Queensland mining law. Also, until 2 December 1989 the Queensland political climate was anti-preservation. Therefore an understanding had to be achieved between John Hay, the Mines Department and the National Parks and Wildlife Service, to ensure preservation of the mining machinery in situ rather than being removed to a town site such as in Ravenswood.

Jan 1, 1990

By Potter DJ, Firkin GR

The Imperial Smelting Furnace operated by Sulphide Corporation Pty. Limited at its Cockle Creek zinc-lead smelter was recently equipped with tuyeres angled at 25 degrees instead of the usual 10 degrees. This change was prompted by the results of model studies undertaken by tha Research Department of Imperial Smelting Processes Limited, at Avonmouth in the United Kingdom, and by the favourable results of operating trials on the Cockle Creek furnace using bent-tip tuyeres to simulate 25 degree inclination. The use of 25 degree angle tuyeres has made it possible to operate with lower zinc values in discard slag and has improved hearth stability over a wider range of sinter quality and composition.

Jan 1, 1981

By Aziz NI, Guo H

Most of the existing models of the mechanisms of drilling and cutting processes are oversimplified in both stress state and failure criterion. On the other hand numerical modelling techniques are a more versatile method with great potential for development. In reviewing drillability and predicting performance of excavation machines the empirical tests, which simulate the physical breakage action in excavating processes are seen to be the best in terms of penetration rate predictability. Future methods of determination of drillability should concern the breakage characteristics and rock abrasivity involved in the two basic types of attack, i.e., percussive and rotary drilling.

Jan 1, 1988

By J Zeni

In 2001, the Springvale Coal Mine determined a requirement for a 360 m deep vertical airway to ventilate ongoing underground longwall mining operations. The project, referred to as the Springvale No 3 Ventilation Shaft, was completed in 2003 - 2004 by blind boring a 4.25 m diameter hole from the surface to the coal seam at 360 m depth. The shaft was completed with a 3.5 m inside diameter lining made from a continuous watertight steel and concrete composite pipe. Presented from both the clientÆs and the contractorÆs perspective, the following paper describes the process of constructing a blind bored ventilation shaft for this application. Beginning with the clientÆs definition of the requirements and specifications for the shaft, the paper describes the steps followed by Springvale Coal prior to awarding the contract. Springv aleÆs process involved a thorough site investigation including procurement of geotechnical data for prospective contractors and the management of issues relating to safety, quality and the environment. The clientÆs view is followed by a description of the planning and works performed by their nominated shaft drilling contractor, Ardent Underground Pty Ltd.The contractorÆs description of the works includes the details of the blind shaft drilling and lining construction process used for this application. The design of the shaft lining installed at Springvale Coal was the first of its type to be used in Australia. The successful installation of a watertight composite shaft lining and the safety of the method, which did not require any personnel to enter the shaft or the mine, were among the positive outcomes from the project.

Jan 1, 2005

By Russell F. M

Following the accident in the Peterson section of Mufulira mine in September, 1970, a method had to be found of extracting up to 300 000 tonnes of ore per month from this area without inducing caving. Sandfill mining methods were chosen, necessitating a plant capable of producing both cemented and uncemented fill on a large scale. The paper covers the design and construction of this sandplant which is thought to be unique for its size, as it incorporates three 3 000 tonne capacity settled storage silos, a 500 tonne capacity cement silo, mixing tanks and a control room situated underground. The plant is designed to handle an aver- age of 440 tonnes per hour with a maximum of 660 tonnes per hour for limited periods, delivering either uncemented fill or cemented fill in proportions varying from 1:6 to 1:30. The instrumentation and equipment necessary to give one man operation of the plant is described and the fill mining methods now in use at Mufulira are briefly outlined.

Jan 1, 1973

Excessive use of computers in teaching, especially in self-learning programs, may destroy creativity and initiative. It is essential that engineers remain innovative to develop new technology. Safety legislation may have hindered the Development of mine managers. It may be necessary to develop two distinct streams of mining engineers. One should be biased towards human relations and safety, to 'be a certificated mine manager, and the other should be mathematically based as a high-technology mining engineer who would not necessarily qualify for a certificate of competency without a postgraduate course.

Jan 1, 1986

By Reid T. W

This paper describes the results of investigations into the relationship between specific gravity and chemical composition in the Cockatoo Island orebody, In the early investigations the samples were classified into groups according to porosity. This resulted in high, medium and low porosity groups, the latter being further subdivided into ore and waste. Whole number tonnage factors were assigned to each group. In the later investigations the reciprocals of bulk specific gravity and true specific gravity were ex- pressed as linear combinations of iron, silica and alumina using stepwise regression. The efficiency of the models as predictors was tested by dividing the data into two sets; one of which was used to calculate the regression equation and the other to test the efficiency of the equation as

Jan 1, 1976

The Kyaukpahto gold deposit is located at latitude 23¦ 47Æ 55" N and longitude 95¦ 56Æ 35" E in the Kawlin-Wuntho district, Sagaing Division, Myanmar. Gold mineralisation is hosted in sandstone of the Male Formation (Eocene) and occurs as stockworks and disseminations. The high-grade gold mineralisation is locally concentrated in a breccia zone. The gold deposit is closely associated with a NNE-SSW trending fracture system that forms tensional open fractures. These tensional zones are thought to be directly related to the Sagiang transfer fault system that experienced several hundred kilometres of northward dextral movement during the post-Upper Miocene. Major sulfide minerals are pyrite and arsenopyrite with minor galena, chalcopyrite and sphalerite. Gold mineralisation is associated with intense silicification, sericitisation and argillic alteration. Primary Type I fluid inclusions in the quartz from the mineralised zone are 5 to 15 ¦m across and yield homogenisation temperatures of 239¦ - 310¦C and salinities of 1.2 - 10.9 wt per cent NaCl equivalent. Laser Raman spectroscopic analysis indicates the presence of CO2 and CH4 in Type II fluid inclusions. Sulfur isotope analysis of disseminated pyrite in the ore zone by the laser ablation method indicates d34S values from -5.48ë to +5.53ë. The geology, alteration, ore mineralogy, fluid inclusion microthermometry and sulfur isotope data of the Kyaukpahto deposit are consistent with an epithermal ore deposit model for the deposit. However, the presence of CO2-liquid bearing fluids and the detectable CH4 in the gaseous phase of the fluid inclusions conflict with a typical epithermal origin for the Kyaukpahto deposit. The host siltstone and mudstone sequence, trace element geochemistry, and the disseminated nature of sulfide and gold mineralisation are also common characteristics of a sedimentary rock-hosted gold deposit, and these features may indicate a Carlin-like affinity. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Christie AB, Bull VH

The geological environments of gold deposits are reviewed in relation to the strong resurgence in exploration for gold since 1979. The resurgence is due mainly to New Zealand's geological endowment with gold and its history as a gold producer. Major past production was from Cenozoic placers of Otago and Westland, late Cenozoic epithermal deposits of the Hauraki Goldfield, and the respective Paleozoic and Mesozoic lode deposits of the Reefton and Otago Goldfields. These same geological environments are the targets of current exploration, mainly in extensions of previously mined deposits. On the Westland and Otago Goldfields alluvial and fluvioglacial gravel placers, mainly representing lateral and depth extensions of previously worked ground, are being mined and prospected. Gold production in 1984 was exclusively from these deposits, and the development of mobile concentration plants has resulted in a great increase in mining activity. Mineralised zones adjacent to previously mined lodes in the Hauraki Goldfield, Reefton Goldfield, and at Macraes Flat (Otago Goldfield) are being intensively explored. At Waihi (Hauraki), an open-pittable resource of about 10 million tonnes of ore has recently been delineated. Some new deposit types and little explored environments are also receiving attention. They include: gold-sulphide quartz veins hosted in an alkaline granite dike in west Nelson; hot spring type gold deposits in fossil geothermal (epithermal) systems of Northland, the Hauraki Goldfield and the Taupo Volcanic Zone; and marine placers off the West Coast where an area of auriferous gravels has been outlined near Hokitika. There is potential in known deposits and prospects currently being evaluated for a large increase in gold production by the early 1990s.

Jan 1, 1986

By W A. Ducker, R-H Yoon, M Mao

Froth flotation relies on an attractive force between a particle and a bubble to selectively extract particles from a mixture. The range and magnitude of this attractive force is an area of ongoing investigation. We describe measurements of the effect of dissolved gases on the long-range attractive surface forces between a silica plate and a glass sphere in aqueous octadecyltrimethylammonium chloride (C18TACl) solutions. The measurements follow on the work of Sakamoto et al (2002) who have concluded that long-range interactions occur in air-equilibrated surfactant solutions but not in degassed solutions. In the present work, we have measured attractive forces that have a much larger in magnitude than the expected van der Waals force in solutions that were degassed by the same procedure used by Sakamoto et al (2002). We find that the forces are most attractive at 5 + 10-6 M C18TACl, which is close to the charge compensation point (ccp) of the glass sphere. At this concentration, the attractive force decays exponentially with distance and the decay length is 34 in air-saturated solution, and 38 nm in degassed solutions. In both air-equilibrated and degassed solution, the force is quite sensitive to the concentration of surfactant. The force is also sensitive to the pH. We note that our degassing procedure increases the pH of the solution from about 5.7 to 6.6 (presumably by removal of dissolved CO2). We find that the forces measured in degassed solution can be reproduced by using a solution that was equilibrated in air, then the pH was increased by addition of NaOH. Therefore, we conclude that the main effect of degassing in our experiments is to raise the pH. We show that the range and magnitude of the attractive force decreases in the presence of salt (NaCl). This suggests an electrostatic mechanism for the attraction. Possible mechanisms for the attractive force are examined, including the mechanisms that rely on a patchy coverage of surfactant on the silica surface.

Jan 1, 2005

The control system of a mine winder or other variable speed drive has many component parts that must work together to provide the required functional performance of the machine, together with comprehensive safety features, reliability, maintainability, user-friendliness and efficiency. Modern winders use digital control technology extensively and hence software design is a major part of the overall system. It is not practical to simulate an entire mine winder in a single computer model because of the sheer mathematical complexity of the behaviour of many of the components. However, most component parts can be simulated quite easily, and related parts of the control system software can be simulated. Such simulations allow control software algorithms to be developed and tested in isolation from the real plant. Tests can be performed on the model without fear of injury to personnel or damage to the valuable plant. For example, speed regulator control algorithms and stability settings can be adjusted to and beyond the limits of stable operation, and near optimum settings can be found. This is particularly important, for example, when designing closed loop controls for emergency brake systems. Obviously, care must be taken to ensure that the computer model of the plant is realistic and takes into account as many non-linear features of the real plant as possible. Pure mathematical analysis of some systems is very difficult to perform when non-linear plant behaviour is involved. This paper shares a number of practical simulation experiences performed using commercially available software such as Matlab and Simulink to simulate various parts of the control system of a mine winder or other variable speed drive. Demonstrations of the operation of several different computer models are shown during the presentation of the paper.

Jan 1, 2005

By Gordon N

The in situ behaviour of claystone floors associated with the Wallarah, Great Northern and Fassifem Seams has been studied using a comprehensive suite of stress and displacement monitors. The instrumentation was supplemented by in situ and laboratory testing of the claystone materials. The instrumentation demonstrated that the presence of claystone floors is associated with floor heave, extra rib spall, and settlement of the pillar into the floor. Horizontal floor extensometers showed that the depth of extrusion of clay was limited to 1-2 in. A pore pressure transducer installed in a claystone floor demonstrated the possible existence of short-term undrained behaviour of the claystone. Long term swelling of destressed claystone was also documented. Settlement of pillars into claystone floors can be analysed using simple elastic theory. The assumption of plane strain is valid for most claystone thickness/pillar width aspect ratios. Floor heave can be analysed using bearing capacity concepts. However, it is considered that heave is the result of local bearing capacity failure in the rib spall zone. The advantage of this model is that the bearing capacity equation can be applied without resort to unrealistically high factors of safety.

Jan 1, 1992