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By Taylor G. R

Fluid inclusions within quartz accompanying several stages of mineralization at Hillgrove are de cri bed. Pyrite-arsenopyrite-gold mineralization shows uncorrected filling temperatures of between 195°C and 250°C. Later stibnite-antimonide-siderite and stibnite-calcite mineralization has filling temperatures between 100°C and 195°C and a bimodal distribution of temperature peaking at 175°C and 145°C, possibly correlated with the two stages of mineral deposition. Secondary included fluids within an earlier generation of deformed quartz veins are derived from hydrothermal fluids contemporary with the main-stage mineralizing fluids described above. Primary inclusions within latestage, cross-cutting quartz-chlorite-calcite veins show these veins to be unrelated to the mineralization.A correlation between filling temperatures and salinities indicates that mineralization accompanied the mixing of a hot, partly saline, fluid (at 5 per cent equivalent NaCI) with cooler, less-saline meteoric or connate water. Over a vertical distance of 200 m, equivalent mineral assemblages were deposited over the same temperature range. Studies on single crystals suggest rapid deposition with fluid temperature dropping 45°C during their growth. Ore mineragraphy and the fluid inclusion data suggest that the metals were transported by sulphur-poor, relatively low-temperature, low-salinity solutions, possibly as carbonate complexe , and that a vertical zonation of the W-Sb-Au mineralization is compatible with the mixing of this hydrothermal fluid with cooler groundwater. Regional metallogenic and geological considerations suggest that ore metals are derived from the remobilization of deep-seated stratabound deposits or from metamorphic fluids expelled from deepseated volcanoclastic sediments.

Jan 1, 1984

By F Clark, M Erickson, J Biggam

Unraveling geological complexity and understanding geological risk are critical components of the challenge that face any mining or exploration venture. This understanding is essential to the successful selection of mineralised domains on which grade estimation relies, so knowledge of the geological characteristics of the mineralised domains is vitally important. æNuggetyÆ mineralisation introduces a higher level of risk and geological observation and intuition may be the only option to ensure that opportunities are realised and ore/waste characterisation is undertaken successfully. Mineralisation at the world class Sunrise Dam gold mine contains a significant coarse gold component, which has necessitated the development of a systematic visual approach to decision making that enables geological staff to determine the potential gold grade in the absence of assay results, and in those instances when assay results appear implausible. The development of the Mineralisation (MZ) Code at Sunrise Dam has assisted in reducing the risk of misclassifying ore as waste and enabled geological control to prevail with confidence where complexity and ambiguity existed.

Jan 1, 2009

Drum winders have now been built to attain depths of 3000 m and more in a single lift in accordance with the South African Code of Practice SABS 0294, which was introduced at the time of the last hoisting conference in 2000. Since then, this code has not only been followed for several winders in South Africa but was also followed in deep mines in Canada. Design of winders and their braking systems are described in the paper. Koepe winders are in use for high payloads of up to 50 t and to hoisting depths of around 2100 m. As known, the stress range of the hoisting ropes is the key parameter for rope fatigue. However, as per the SABS Code of Practice 0294, relying on static design is not the answer to the question of where the limits are for Koepe installation. The paper describes factors that are recognised to have influence in rope life and suggests definition of new design criteria for friction winders in order to get viable solutions for high-capacity hoisting from deep mines similar to drum hoisting.

Jan 1, 2005

By Canning RG, Uusna S, Goodheart BA

The paper outlines the development of"a process for removal of iron oxides from ilmenite, thereby upgrading the TiO2 content of Western Australian ilmenites, from 55 to approximately 90 per cent. In the first stage, the iron oxides are reduced with solid carbon (coal) to metallic iron. Experimental reduc- tions were carried out in crucibles,, a fluidised bed and a small pilot plant rotary kiln. The reduced'ilmenite is,then agitated in aerated water, in the presence of catalysts, so that the iron "rusts" away from the ilmenite'grains and the precipitated iron oxide is easily separable by decantation. The influence of variables on the rates. of reduction and oxidation are discussed, The oxidation rate was exam- ined for both - the' physical oxygen-transfer characteristics and electrochemically by reference to Peurbaix diagrams, which plot redox potential against solution 'PH, The upgraded ilmenite is expected to be an attractive material. for pigment -manufacture,, and the iron oxide has prospects of being a marketable by-product. The process may possibly be. applied, to .other..ores.

Jan 1, 1964

The products required by customers today have become far more complex and consequently more demanding to handle. And thereÆs the dilemma. Nowadays, people tend to stick to a trade for just a few years instead of for a lifetime, and this means that the customerÆs employees cannot be expected to get more than general knowledge of how to handle modern mining and construction equipment. To meet this challenge, major steps are being taken by suppliers to make their æmusclesÆ more user-friendly. Also the supplier is assuming a larger share of responsibility for the product including operators training, supply maintenance services and, in many cases, performance guarantees. In other words, the supplier is today supplying a function or an activity rather than just muscles. Some of the new generation drill rigs have been on the market for a few years and reliable experience has been collected and is addressed in this paper. Some of the information is well supported by figures while others are just statements from users of the rigs.

Jan 1, 2005

By K Lee, K Fernando, S Rayner

Copper-gold ores have been technically difficult and uneconomical to process due to high consumptions of cyanide. Many copper oxide and sulphide minerals react with cyanide to form copper cyanide complexes, partly contributing to the high level of weak-acid dissociable cyanide in the tailings which is normally experienced during the processing of copper-gold ores. The cost for detoxification, if required for treating these tailings, would further inhibit the development of these copper-gold resources unless the cyanide used for leaching was recovered. Several technologies have been proposed to process copper-gold ores, aiming to recover copper as a co-product and cyanide for recycling in conjunction with the leaching process. A critical review of these processes reveals that a pre-concentration stage (solvent extraction or resin ion exchange) is required. Cyanide is recovered by the conventional Acidification-Volatilisation-Regeneration technique in most cases. A critical evaluation is also provided on technical aspects related to the use of Vitrokele Technology and a newly developed Elutech process in processing copper-gold ores, in particular with its application at May Day Mine.

Jan 1, 2000

By R Lau

In recently completed road tunnel projects in Queensland, such as the Airport Link and the Clem7 tunnels, there is a smoke duct running along the roof of the carriageways to extract smoke in case of fire. In New South Wales, no road tunnels have a smoke duct. In the Melbourne City Link tunnels, there is a small smoke duct running along the roof. All of the tunnels are safe as claimed by the designers and authorities. However, there is significant cost associated with providing a full size smoke duct compared with no smoke duct. This paper is going to present a comparison of the road tunnel safety with a smoke duct and those without one from a risk perspective. It further discusses the cost-effectiveness of such provisions and whether similar levels of safety could be achieved without a smoke duct.CITATION:Lau, R, 2014. Smoke duct or no smoke duct for road tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 83–86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

The Central Extended Orebody is located within the Cracow Goldfield approximately 360 km northwest of Brisbane and approximately 220 km west of Bundaberg. It is an epithermal gold deposit hosted by the Late Carboniferous to Early Permian Camboon Andesite. The lode was mined by open cut methods and produced 170 458 tonnes of ore at 5.62 g/t gold.The geology of the rit is relatively simple, comprising two rock types, trachyandesite and rhyolite which have been sub-divided into several units. The trachyandesite is sub-divided into three rock types: brecciated trachyandesite which is the most widespread, hydraulically fractured trachyandesite hosts the mineralisation and the third sub-unit is chloritised hydraulically fractured trachyandesite and has no associated mineralisation. The mineralisation is confined to quartz veins in hydraulically fractured trachyandesite. Several phases of brecciation and subsequent quartz and quartz/adularia vein injection are evident although not all phases are mineralised. Two rhyolite dykes intrude the trachyandesite one is monolithic, the other is sub-divided into hydraulically fractured rhyolite (barren), silicified rhyolite and auto-brecciated rhyolite.

Jan 1, 1993

By Zenari L, Kent D

As our mines introduce more sophisticated production technology into their operations, the dependence on communication systems is markedly increased to allow the management of the technology. However the attention given to the communication systems has lagged that given the production equipment - namely LHDs, trucks and jumbos. At times it was treated as after thought. However, this is changing as the degree of automation increases in our mines. The communication system is now being given much more priority and is genuinely becoming a part of the mine design. The transfer of information around underground, as well as between the surface and underground, is an essential day-to-day activity, with the aim being a smoothly run operation. However the mine environment is far from static, and situations arise - such as breakdowns or other incidents - that require swift analysis of the issue, its cause and its remedy. Also, as communication systems become more sophisticated their use in areas, other than direct data flow, become available. The importance of communication, its development, and new areas being impacted by communication is the subject of this Paper.

Jan 1, 1997

By Bevan JE

The US Bureau of Mines is conducting research to improve the health and safety for underground coal miners, and the efficiency of the mining systems that are used. In 1986, the Bureau began a major research effort on the technology for computer-assisted mining systems for underground coal mines. The initial target was technology for continuous mining machines that would allow them to extract coal by computer-assisted operation. Technology areas being investigated include guidance systems, machine condition systems, computer systems, machine control, human-machine interfaces and planning. In each of these areas, individual system development has progressed to where underground testing of these systems will begin in 1991.In addition to coal extraction, the Bureau has also begun research for the development of technology for computer-assisted roof bolting. The Bureau is developing technology for a "smart" roof bolter that would be able to sense and analyze strata conditions to determine the requirements to provide a competent roof. The system would determine the location of the hole, drill the hole to length, and select and install the appropriate bolt.

Jan 1, 1991

Design and construction techniques used to develop two highway tunnels in inaccessible mountainous terrain are described. Measures used to adapt the design to the unusual geology and topography are discussed, as well as measures to adapt the construction methods to available equipment, materials, and skills. Sharp local variations in geoloqic conditions resulted in field modifications to both design and construction techniques. The geology is a volcanic ash and breccia-agglomerate at one site, a jointed andesite at the other, which is also the site of a major landslide. Both rock reinforcement in the form of pretensioned and grouted rock bolts with a shotcrete lining,and rock support by struc- tural steel sets with a reinforced concrete lining were used. A canyonside location and high lateral in-situ stresses required modification of design procedures. Pilot tunnels at both sites resulted in adapting the designs to site conditions with large savings in lining costs, disclosing problem areas in advance of the main excavation, and cushioning of blasting pressure to minimize stability problems.

Jan 1, 1976

One of the most difficult places to ventil ate in any mine is the working face area of an advancing mine heading. With an ever changing configuration, continual modification and extension to the ventilation system is necess- ary to maintain an adequate supply of fresh air and to control mixing and recirculation. Methane emissions and high dust levels as coal is broken and removed from the face area can produce unhealthy and dangerous conditions if ventilat- ion is not adequately monitored. An understanding of the air flow patterns which develop through use of different face ven- tilation systems can be reached by undertaking underground measurements or through observations using physical models. Tests undertaken by the author to determine the adequacy of different system-configurations are discussed together with approaches adopted by others working in the United States. Various new methods have been proposed for improving face ventilation beyond that sustained using conventional brattice curtain or tubing systems. The adequacy of some advances adopted by mining companies to improve ventilation while maintaining output efficiency is discussed.

Jan 1, 1983

By J Walasiak

In the climate planning of mines and tunnelling with anticipated poor climatic conditions, and especially in case of longer working shifts, the main question is whether it can be reliably prevented that certain climatic limits laid down be exceeded. Working at high temperature and/or humidity can lead to reduced human working energy û a very important economic aspect û and to a risky lack of concentration on the part of the miners or to heat collapse and extremely dangerous heat stroke. With the Deutsche Montan Technologie GmbH (DMT) climate prediction programs, both the dry and the extremely significant humid heat transfer can be calculated. This is due to the high planning reliability involved. With the help of these climate prediction programs it is already possible to determine the anticipated climatic values for the operation phase as early as the planning stage of new ore or coal fields or of tunnel construction projects and to design the optimum air cooling system for every underground project with due regard to technical and economic aspects.

Jan 1, 2005

The source and origins of the hydrothermal fluid of orogenic, or quartz-vein lode-gold deposits remain uncertain and disputed: Resolution would likely have a significant affect on exploration strategy. The gold-carrying fluid is interpreted to be a low-salinity mixed aqueous-carbonic fluid of near ambient pH and redox state, that may be derived either magmatically through crystallisation of granites at depth in the crust or through metamorphic reactions in a range of rock types. Classic isotope and geochemical tracers of fluid source have not differentiated these possibilities and have produced conflicting conclusions. Mass balance calculations show that fluid composition will be modified by wallrock reaction between source and deposit, and tracers should not be expected to give clear indications of fluid source. Fluid oxidation state can also be modified along flow paths. Tracers should be interpreted with care and with view to possible modification. Modelling of full flow paths and examination of the hydrothermal histories of proposed source rocks may be alternative approaches to determining fluid source.

Jan 1, 2002

Many metallurgical beneficiation and primary concentrating processes rely upon discrimination of products from gangue based on particulate density of the different minerals and combinations of minerals in an ore. The basic definition of density is simple, but the apparent density that minerals exhibit when in the environment of commercial densimetric separation processes is more complex and is ill-defined. Measurement of the apparent density displayed by minerals in their separation situation is essential if modelling of plant performance is to be meaningful or when comparison of an existing operation with a æperfectÆ separation constitutes a part of an audit or of a plant control function. Seven methods of dividing ore samples into discreet density fractions are examined and criticised in this paper. The shortcomings, difficulties and potential errors arising from the use of each method are evaluated. Most of the techniques described have been used by the author and generally their faults are understood and the resultant first-hand experience has been used to overcome these faults. A simple new computer-assisted technique for developing meaningful densimetric data is described.

Jan 1, 2004

By Sterns UJ, Weller KR

Grinding to sizes less than 80 per cent passing 20 ¦m in both primary and regrind circuits is becoming increasingly important in processing metalliferous ores, as many of the remaining orebodies are very fine-grained and refractory. The process of very fine grinding, however, is expensive, and neither the performance nor the design criteria are well understood. This paper presents some findings from a collaborative research program, one of the objectives of which has been to better understand and improve the performance of very fine grinding circuits. Data from surveys of an industrial tower mill grinding circuit are reviewed and analysed using the population balance models of the CS]RO and 7KMRC. The performance of both models with regard to changes in feed size distribution, ball load and feedrate is assessed using these data. From comparisons between pilot and full scale tower mill operation a prototype scaling methodology is also presented which shows promise in allowing the models to be used to predict the effect of changes in mill Design.

Jan 1, 1993

By M Devia, J Rapkoch

This paper is intended to help design engineers, operating staff and plant managers understand the principles of metallurgical gas handling systems design. It also explains operating, safety and energy savings issues that the designer should take into consideration in the design of process off-gas systems for sulfide smelters. Primary smelting reactors, converters, and other off-gas sources impose challenging duty requirements on the various components of the gas handling systems. This paper reviews the design of common system components including the hood for gas capture at the system inlet, gas conditioning, gas cleaning, ductwork, dampers, hot gas fans, and the appropriate use of instrumentation and controls. The engineer must also be aware of how ductwork system effects and heat losses influence system performance. Also, the analysis of a recently-designed gas handling system will be reviewed, which includes high-strength SO2 gas from a smelting reactor, asymmetrically located Peirce-Smith converters, and a gas mixing chamber to mix the gases before they are sent to two acid plants of different sizes.

Jan 1, 2005

For decades strip mining with discon tinuously operating 'draglines and shovels has been the most economical operation method in the shallow hard coal opencast mines of Aust- ralia, North-America and some other countries. Continuously operating equipment such as bucket chain excavators and bucket wheel excavators in combination with conveyor belt systems, conveyor bridges and stackers had been deve- loped in Germany; during the last 25 years this type of equipment has been further developed in order to allow a high degree of rationaliza= tion as to opencast mines in unconsolidated overburden in Germany, in many European couh- tries, in India and in Victoria. The differing compactness of the layers to be mined, the increasing mining depth, the adverse over- burden to coal ratio and geotechnical con- ditions account for the combined use of con- tinuously and discontinuously operating equip- ment and systems. This paper is to demonstrate some projects showing the combination of continuously and discontinuously operating equipment which aims at optimizing opencast mine operations. It will be reported on the following combinations: - combined use of bucket wheel excavator/

Jan 1, 1981

By G J. Sparrow, M J. Fisher-White

A mineral and chemical characterisation study was conducted on ilmenite-rich heavy mineral concentrates sourced from the western sector of the Eucla Basin in southern Australia. Test work involved using X-ray diffraction (XRD), scanning electron microscope (SEM) and electron microprobe-based characterisation methods. Results showed considerable variability in the degree of ilmenite alteration between deposits with TiO2 contents varying from 53 - 63 wt per cent TiO2. Notwithstanding variability between individual deposits, the samples all had [Ti]/[Ti+Fe] ratios >0.5 consistent with a mineral assemblage of hydrated ilmenite or the hydrated, Ti-rich alteration phase pseudorutile (Fe3+2-x Ti3O9-3x (OH)3x). Accessory phases consisted of rutile (primary and secondary), zircon, aluminosilicates, quartz, Fe oxyhydroxides and spinels. Results for the most altered material are broadly comparable with data for ilmenite concentrates from the eastern margin of the basin. The mineralogy of the western Eucla Basin concentrates and the minor element composition of the ilmenite grains suggest they could be upgraded to synthetic rutile by a modified Becher process.

Jan 1, 2008

By Hinton A. T

Three, and possibly four, distinct types of quartz-vein associated gold mineralisation are recognised in New Zealand. They are: epithermal, schist-hosted, metagreywacke-hosted and metamorphic core complex associated types. Each has a unique geological environment and structural regime which has provided the gold source, scavenging mechanism, emplacing mechanism and geometry. Each has a characteristic suite of associated metals and trace elements. The first three types form economically important gold deposits while the fourth type have been historically worked for gold and base metals. Intense exploration is currently being focussed on all four types.The epithermal type is typified by the extensive vein systems of Martha Hill, Karangahake and Golden Cross and numerous smaller examples. The veins were deposited in a near surface active volcanic environment from deeply circulating hot water. Their structure is tensional, veins are vertical-to sub-vertical and have limited depth. Their geochemistry is identical to that in active felsic hydrothermal centres in the central North Island. Major minerals are gold, pyrite, arsenopyrite, galena, chalcopyrite, sphalerite and argentite.

Jan 1, 1990