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By Mukhopadhaya K. K, Cory A. H

The concept of using travelling magnetic fields created by linear motors was stimulated by Laithwaite who advanced ideas on motors with shaded poles (Laithwaite, 1968), rack and pinion motors (Laithwaite, 1970) as well as low speed, brushless motors and three dimensional motors (Laithwaite, 1973a and 1973b).Sudan (1963) and Sundberg (1969) had applied the concept to metallurgical processes. However, the use of travelling magnetic fields has not been used widely to produce conditions for the separation of magnetic from non-magnetic minera1s or even magnetic materials from non-magnetic materials, although some attempts were made by McCarthy (1922), Davis (1934), Dean, Gottschalk and Davis (1934) and Gottschalk (1934).Laithwaite (1973, a) while working with linear motors made suggestions for designing separators and in the work described here, the observations of Laithwaite and others are extended to determine the characteristics of the motor with a view to using it as a magnetic separator.

Jan 1, 1980

Most of you who are attending this conference are probably Student Members of The Institute and well aware of the advantages which flow from student membership. You will probably agree that the major benefits are: ò Low and subsidised membership fees;

Jan 1, 1994

By Y Zhang

Being analysed systematically, the factors influencing the production of fully-mechanised coal face have been divided into geological, mining technical, and management groups. Artificial neural network-expert systems (ANN-ES) are established to decide the influencing factorsÆ membership grade; genetic algorithm-artificial neural network (GA-ANN) are used to decide the weights; fuzzy comprehensive evaluation method is used to calculate the integration indexes. Finally, the GA-ANN model is established to forecast the production of fullymechanised coal face. It is proved that the model is reliable with higher precision. The production of fully-mechanised coal face is influenced by many factors. However, some influencing factors are neglected by the traditional forecasting methods, the results of which are not precise and hardly be used as a guide for mine production and management. The relation between the production of fully-mechanised coal face and its effecting factors is analysed, and the meta-synthetic AI approaches are used to forecast the production of fully-mechanised coal face.

Jan 1, 2003

Enhancement of Energy Efficiency in Fine Grinding of Copper Sulfide Minerals Using a Pilot-Scale Stirred Media Mill - IsaMill The mineral liberation size of run of mine ores has dramatically reduced over recent years. As a result, the demand for fine grinding which is the most energy-intensive form of grinding has markedly increased in the minerals industry. Furthermore, the fine grinding costs increase exponentially with decreasing product particle size. As a result of the increased energy requirement for fine grinding, it is desirable to optimise fine grinding processes such as stirred media milling (ie IsaMill) to enhance energy efficiency, throughput and the product fineness. In the present study, the influence of slurry rheology, grinding media type and grinding media-to-feed size ratio on energy efficiency in a pilot-scale IsaMill was investigated under certain industrially relevant pulp processing conditions. It was shown that a critical rheological state existed, below which the energy required to achieve an 80 per cent passing (ie P80) 20 ¦m product size was unaffected by shear rheology (ie apparent viscosity and shear yield stress) whilst above which the grinding energy required increased dramatically with increasing shear rheology. Colorado River sand (3.35 mm) showed higher energy efficiency than MT1 ceramic media (2.5 mm) for a target P80 of 20 ¦m in the solids concentration range of 38 to 55 per cent by weight, but the former experienced more than four times the wear rate of the later. The high wear rate of the Colorado River sand may be due to its much lower hardness. For feeds with an 80 per cent passing (ie F80) 70 to 110 ¦m, 2.0 or 2.5 mm MT1 media appeared to be more energy efficient than 3.5 mm MT1 media whilst a media-to-feed size ratio of 41 to 53 is applicable for ~50 ¦m (ie F80) feeds for efficient grinding.

Sep 13, 2010

The environmental and social responsibilities of the mining industry have long been recognized by the industry itself, but during the past decade it became one of the main targets for the more radical members of the community. This came as something of a shock to an industry which had always considered that it had acted responsibly within the standards of the day. As far back as early 1968, the Australian Min- ing Industry Council (AMIC) was clipping from newspapers the odd letter written by environmen- talists and critics of mining activities. In those days every such letter was carefully studied to ensure that AMIC, if not having the answers, at least had an understanding of the types of argu- ments then starting to be used against mining activity and in favour of environmental preserva- tion. Within 18 months, the infrequent letter to the editor had become a flood of such letters and feature articles, and the environmentalists' attack on mining activities had been launched in all its Vehemence.

Jan 1, 1978

By Penttila V

The Paleoproterozoic Hitura Ni-Cu deposit in western Finland is in an ultramafic igneous complex composed of two subvertical plug-shaped bodies embedded in intensely migmatised felsic gneisses. The ultramafic complex is not far from a north-south trending graphitic and sulphidic gneiss zone interpreted to be a primary sulphide-graphite unit in the metasedimentary sequence. The sulphide accumulation exists as a zone parallel to the contact of the northern ultramafic body. The ultramafic rock types, now mainly serpentinites, have primarily been olivine adcumulates in the core grading to olivine orthocumulates and pyroxenites towards the margins. Coarse-grained felsic pegmatite veins injected serpentinite where they now exhibit prominent zoned alteration rims of chlorite, antophyllite and talc. The serpentinite core of the body was primarily an olivine adcumulate derived from a tholeiitic or high-Mg basalt parental magma with about 11 wt % MgO. Metamorphism and alteration have totally changed the igneous mineral compositions and the rock types are serpentinites (from olivine adcumulates), ambhibole-bearing serpentinites and amphibole-chlorite rocks (from pyroxenites). As the result of CO2 alteration talc is an accessory mineral throughout the serpentinite. Like silicates, also sulphide minerals are altered. In the core of the body the low-grade sulphide dissemination still reveals primary igneous interstitial forms. The core sulphides are now mackinawite, pentlandite and valleriite instead of primary igneous pyrrhotite and pentlandite derived from Mss. At the marginal zone the heavy dissemination and net-textured sulphides display pyrrhotite-pentlandite-magnetite intergrowths with magnetite films along cleavage of sulphides, mackinawite in pentlandite and exsolution textures of different low-temperature pyrrhotite phases as the result of alteration processes. Mechanically weak rocks, complicated structures and textures of the ore, magnetite and mackinawite intergrowths in pentlandite and readily-floating MgO silicates cause problems in exploitation of the deposit. Solution to problems come from selective stoping, three-step classification in grinding, froth-washing technique and on-line process control based on ore type determination from process data using an expert System

Jan 1, 1996

By F Hungerford

"In-seam drilling has been undertaken for the past 30 years for gas drainage to reduce the risk ofoutburst and lower the concentrations of seam gas in the underground ventilation. The drillingpractices have reflected the standards of the times and have evolved with the development oftechnology and equipment and the needs to provide a safe environment underground. Earlypractice was to adapt equipment from other fields, but with changing emphasis, research anddevelopment by the coal industry has created specifi c equipment, technology and practices toaccurately place in-seam boreholes to provide efficient and effective gas drainage."

Jun 1, 2012

The reduction of titanium tetrachloride to trichloride can be achieved by employing hydrogen and electric arcs. It is possible to produce melts containing up to 50% TiCk in the eutectic mixture of LiCl/KCl by striking a D.C. arc at the surface in the presence of hydrogen and TiCl. vapour. If the electrode IS made to just penetrate the surface of the salt mixture, a hot zone results from the' high resistance contact with both lower chlorides and sintered titanium may be produced. The sintered metal forms just below the melt surface while the trichloride forms at the gaslIiquid junction.The "hotspot cathode" appears to offer a solution to the problem of producing coherent deposits as the spong'e metal can 'be continuously withdrawn in a similar manner to the "calcium process".INTRODUCTIONConsiderable interest has been shown for some years in the possible development of a cheap electrolytic process for the extraction of titanium metal, since a method using simple materials and cheap electric power would materially reduce the cost of production. Even when cheap starting materials are used, however, there exist several general difficulties in the operation of plant which both limit the speed of production and increase the cost of the product. It happens that most of the techniques so far tried produce a powder as cathodic deposit, and when this is the case the following difficulties arise:1. The whole contents of the bath must be treated with solvent in order to extract the 'metal powder which may itself tend to oxidise, and thus become contaminated.2. Fine metal powders, which often contain residual entrained salts, are less easy to consolidate by arcmelting than metal sponge.

Jan 1, 1956

The exploration methods used by the British Coal Corporation in 1990 improve the geological reliability of underground coal production. Although some of the techniques in common use have been proved to be effective, their limitations are recognised and concentration has been on the increasing integration of direct and remote sensing techniques. Attention is focussed onto first seam workings in sections of at least 2 metres in the depth range of 400-1200 metres and covers both surface and underground exploration. The case studies of exploration techniques and their effect on mine design at several existing collieries are representative of a wide range of geological environments within the more productive British coalfields. Notwithstanding such improvements in exploration and geological reliability, further new exploration technology is currently being investigated or trialled by British Coal.

Jan 1, 1991

By Yang RL, Bailey ML

During overburden blasting operations in dragline pits, coal edge losses along the lowwall edge of the new pit are often experienced. In tonnage terms, losses can be significant. With the thick seams at Callide Mine, 20,000 tonnes of coal can be lost along a 600 metre pit. In addition to the immediate dollar value of the coal, replacement of this coal (from which overburden has been removed) will be from higher ratio and higher cost pits in the future. Unit costs of production for the remainder of the coal uncovered in the current pit increase. Experiments involving variation of blasthole inclination and/or amount of standoff on the front row of blastholes have given no significant improvement in the coal edge loss control.

Jan 1, 1988

By S Ellis, J McMullen, M Habner

A new leaching regime was implemented at Kalgoorlie Consolidated Gold MinesÆ (KCGM) Gidji plant on a cyanide leach of ultra-fine ground sulfide concentrate. High lime concentration and lead nitrate were used to overcome the refractoriness of the fine sulfides (high reactivity of fine sulfides with the presence of gold tellurides). The leach pretreatment stage was shown to be detrimental and was shut down. Lime titration was introduced as part of the process control. It was shown that the leach could be performed at low dissolved oxygen, (ie 3 - 5 ppm) to avoid sulfide oxidation and the associated high cyanide and lime consumption. Plant results showed reduced cyanide consumption (40 per cent) and an accelerated leaching rate, whereby most of the gold was dissolved in 24 hours compared to 72 hours used previously. Similar work was performed at KCGMÆs Fimiston plant, which leached a combined ultra-fine ground sulfide concentrate along with the slimes fraction from hydrocycloning the bulk flotation concentrate. The use of lead nitrate, high lime and carbon-in-leach generated a faster leaching rate and minimised adsorption of gold on fine pyrite particles. The grind, previously controlled with a P80, was replaced by a P98 to give a better operational indication of top size hydrocyclone performance. Before the implementation of the changes, average leach residues for slimes and UFG were respectively 4.0 g/t and 5.5 g/t. With the modifications to the leaching regime, average leach residues were lower by 1.5 - 2.0 g/t. Whilst significant improvements have been demonstrated, further work is progressing at KCGM to further reduce ultra-fine concentrate leach tail grades, and also to improve the understanding of concentrate refractoriness and the factors responsible for differences between laboratory and plant leach results. Estimated profits since the implementation of the new approach are in the range of $A3.5 million per year.

Jan 1, 2005

Commercial or potentially commercial deposits of coal occur in Australia in strata ranging in age from Permian to Tertiary. The coals of each period tend to show a community of petrographic character and significant differences as compared with coals of other ages. In particular- many of the Permian coals are unusually rich in inertinite whereas the Jurassic and Tertiary coals are typically very rich in vitrinite. The majority of the coals show evidence of deposition in environments subject to relatively minor marine influence. Except for some Tertiary and Permian coals the content of mineral matter tends to be high. Outcrops of coals of bituminous rank appear to be largely restricted to the eastern margin of the Australian continent. In this region vertical rank gradients are generally higher than in the other sedimentary basins and uplift and the removal of cover has occurred to a greater extent. To the west of the Tasman geosyncline, coal of bituminous rank generally occurs at considerable depths (usually in excess of 1 km and in some areas only at depths of over 2 kms), and in most areas coals at shallow depth are of sub-bituminous or brown coal rank. The controls of the distribution of coal type and rank have considerable economic significance and the unusual characteristics of Australian coals, especially with respect to coal type, make the direct application of overseas technology to Australian coals inappropriate.

Jan 1, 1975

Designing and constructing OxianaÆs Sepon gold and copper operations in one of the most remote areas in Laos has been a great achievement; one which was recognised by the engineering industryÆs highest accolade û the Australian Engineering Excellence Award in 2005. The developing nation of Laos has no previous mining or heavy industrial experience, but the support of the Lao Government and a remarkable Lao workforce has enabled the project to be developed and operate as well as it would anywhere else in the world.When making a decision to invest offshore, several geophysical and jurisdictional criteria need to be considered. Laos offers unparalleled prospectivity, a central location with growing infrastructure, a ready workforce and a developing but supportive regulatory regime. In addition, the Sepon copper project has exceptional characteristics, including its high grades, location near the surface, leachable qualities, access to hydropower and the ability to produce cathodes on site. These attributes and its location in the centre of a region hungry for resources contributes to the projectÆs excellent economics.

Jan 1, 2006

By D Stow, M Edmondson

Lemington coal mine is operating in an environmentally sensitive area in the Hunter Valley, NSW, Australia. Late in 1999 the southern pit was developed using a series of box cut blasts. After the initial development the area would have been free dug due to the soft, well-jointed nature of the deposit. However, it was decided to trial drill and blast to determine if shovel productivity could be improved to enable an overall mining cost reduction. The initial trial blast results were less than satisfactory with both environmental issues occurring and the desired shovel productivity not being achieved. An audit of the blasts indicated that wet ground and the presence of soft clay inter-bedded with harder rock caused the poor blast results. Also, water-affected explosive product combined with explosive energy loss into soft ground led to flat spots and tight digging in the hard band areas, resulting in the lower dig rates. Lemington Mine and Orica Explosives developed a plan to match the rock with the appropriate explosive type and energy. This resulted in a number of blasts over a six-month period using a new non fuming explosive product, æNovaliteÆ. The results have been excellent with the environmental issues being totally resolved and dig rates improved, enabling reductions in mining costs. This has allowed the mine to continue with their exemplary record of environmental management whilst achieving operational efficiencies.

Jan 1, 2001

Regional problems, such as political risk and debt reschedulings, in Pacific Rim nations coupled with the price volatility of gold mean that multi-faceted financing packages are needed to offset the many risks inherent in a new gold mine development. The cross-border risks of getting money back out of a producing mine may require the involvement of export credit agencies, multilateral government banks, or political risk insurance. Variations on forward gold sales, gold loans, or offset structures can also enhance the flexibility and safety for the providers of both the debt and equity. The region will become as large a gold producer as South Africa by 1990. The large dollar amounts for both investment and revenues realised are of great significance to the economies of many of the Pacific Rim countries especially as a means to increase foreign exchange earnings.

Jan 1, 1987

A broad zone of intra-plate volcanism occurs for some 3000 km along the E. Australian coastal regions, extending from far northern Queensland southwards to Tasmania, westwards to western Victoria, and into southeastern South Australia. The age range, taken over the whole region, extends from Eocene to Holocene. Wellman & McDougall (1974) recognised the occurrence of three distinct types of volcanic occurrences: (a) Lava field provinces, dominantly basaltic and commonly strongly undersaturated, but of variable size. Large lava fields are especially exemplified by the younger provinces in northern Queensland (e.g. Nulla, McBride), and western Victoria. (b) Central volcano provinces, in which a reasonably well defined volcanic edifice is discernable. Such provinces are built of mildly undersaturated to saturated mafic lavas, but are also characterised by felsic volcanism (and often substantial mafic and felsic intrusive phases). Examples are the Springsure-Minerva Hills province, the Tweed and Focal Peak Shields (southeastern Queensland to northeastern N.S.W.), and the Nandewars, Warrumbungles, and Canobolas volcanic centres (N.S.W.). (c) A single leucitite province in N.S.W. Wellman and McDougall (1974) were able to show that the central volcano provinces exhibit a remarkably regular southward age migration pattern, the calculated migration rate being 66 + 5 mm yr , and these authors interpreted this in terms of the northward passage of the Australian plate across a fixed 'hotspot' within the upper mantle. The leucitite province also fits this migration pattern. The lava field provinces apparently exhibit more erratic regional age distribution patterns, but Sutherland (1981) has interpreted the data in terms of a multiple 'hotspot' model. It is noted, however, that the youngest areas of volcanism (Pleistocene 1. Department of Geology and Mineralogy, University of Queensland, St. Lucia, Brisbane, Queensland

Jan 1, 1987

By Thompson J

A programme of testing and evaluation has been in progress at Isa Mine for the last four years with the objectives of rationalising ground support practices, improving installation quality and increasing productivity of ground support functions.Numerous innovations have been successfully implemented. These include the introduction of swellex rockbolts as the major form of temporary support, the use of splitset rockbolts as the primary means of support for the hangingwalls of cut and fill stopes and the introduction of dowels with pumped cement for general long term support.The installation of swellex bolts has been successfully mechanised throughout the mine using Tamrock automatic rockbolters and Atlas Copco BUK 11R drilling rigs modified for this purpose.

Jan 1, 1985

South Australia was founded as late as 1836, forty- eight years after New South Wales, yet within five years had announced the first discovery of metals in Australia. Throughout the 1840s the mining of silver-lead, then copper, spread north through the Mount Lofty and Flinders Ranges creating a thriving industry, years before the discovery of gold in the eastern colonies in 1851. The first significant mine was Kapunda (1842), followed by the much bigger Burra (1845) and other copper finds at Tungkillo, Worthing, Cal- lington, and North Rhine.

Jan 1, 1987

By Luke K. A

Pressure on production at New Zealand China Clays has led to the development of a dewatering control loop for fine halloysite china clay. The development was based on the analysis of data from the automation of plate and frame filter presses. The analysis of the data has led to process changes, and the ability to quickly solve dewatering problems. As a result of control in the dewatering circuit press times have reduced on average 117% and output has increased proportionally.

Jan 1, 1989

By J Krawcz, S Wasilewski, W Mironowicz

Barometric pressure and its variation in deep underground workings have a considerable effect on ventilation conditions. Pressure changes which create transient states of air flow and air parameters in workings are especially significant. Experiments have shown that pressure changes have a remarkable effect on air parameters at mine workings and hence, attempts to evaluate the scale of this phenomenon are of value. Continuous monitoring of the barometric pressure on the surface of mines allows for the detection of changes in pressure which undoubtedly influence alternations of pressure in the underground areas of mines. Very important factors are the internal disturbances of pressure within a mine ventilation system due to variable conditions of fan operation and the operation of a winding machine where a mine cage moving in a shaft causes piston like disturbances. Local transient disturbances caused by temporary opening/closing of air stoppings due to personnel or underground transport traffic are of importance. The results of over two years of observations of barometric pressure and its influence on pressure variation in underground mine workings are presented in this paper. The observations were possible through the installation of pressure sensors at selected points of the downcast shaft in a mine. Of interest are the observations of the transient states of pressure and other air parameters caused by emergency fan stoppage, movement of a mine cage and changes due to the opening of air stoppings. Data acquired during experiments of opening and closing air stoppings were used for the validation of a flow model in a long working.

Jan 1, 2005