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By D Willis, A Shanahan, C Jacobs, T Luxner

The application of tunnel boring machines (TBM) for reef mining is a unique practice with benefits over current mining methods given the right geology and geometry of the orebody. The Stillwater Mining Company (SMC) of Nye, Montana, USA operates two mines for obtaining platinum metals. The operation is currently using a 5.5 m diameter open-type machine for further mine development, as well as another TBM that they own.The latest 7.1 km bored tunnel, known as the Blitz Tunnel, will be routed parallel to the ore deposit in igneous mafic intrusive rock, and will be used for the life of the mine operation. It will be used to map the ore deposit, and provide a rail haulage route.Detecting the reef in relation to the TBM requires careful analysis. Diamond core drilling occurs ahead, above, and alongside the machine at every 150 m. The core is drilled, logged, and interpreted on the spot, concurrent with boring. Based on the data, the TBM is readjusted so that it stays on the correct bore path.This paper will highlight the application and benefits of TBM usage for reef mining, with detailed descriptions from the mine site.CITATION:Willis, D, Jacobs, C, Luxner, T and Shanahan, A, 2014. Tunnel boring machine usage speeds up development at Stillwater Mine, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 683–690 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By S Das

Deposit-10/11A is situated in the iron rich Bailadila region of India comprising haematite ore of average grade 65 per cent Fe. The deposit production line was commissioned in the year 2002 having a capacity of 5 Mt/a. The plant has the state of the art mineral processing equipments.The ore is transported from mines to crushing plant by means of dumpers. The ore is comminuted in two stages to get 150 mm top size product and this product is transported through conveyor system and is stored in silos as feed stock for beneficiation plant. In the beneficiation plant this crushed product is wet screened in two stages to produce a product of lump (-150 + 10 mm) and fines (-10 + 3.15 mm). The product of -3.15 mm top size is fed to primary classifier for a size separation at 150 µm. The resultant product (-3.15 mm + 150 µm) is dewatered and transported to fi ne ore product stock yard through conveyor system. The minus 150 µm material from classifier overflow is fed to cyclones (508 mm cyclone battery with an apex of 65 mm) for desliming at 45 µm and to recover ultrafi nes (-150 + 45 µm). The cyclone overfl ow slimes (-45 µm) along with water is treated in lamella thickeners to recover process water. The thickener underflow material is transported to tailing pond (discharge rate is 300 m3/h at a specific gravity of 1.4) by pumping through HDPE (high density poly ethylene) pipeline and the over flow water is being recirculated. The water requirement for beneficiation is approx 1.5 m3 per ton of ore.This paper aims at identifying and quantifying the factors that affect the overall plant performance (grade and recovery) during the different seasonal variations especially in the rainy season (mid-June to end October). The effect of seasonal variations on unit operations such as milling, classification, thickening and filtration are discussed. Specific cases are presented as examples and recommendations are formulated.

Jul 11, 2011

By Y Tsukurimichi, D Asahina, T Endo, T Takemura

Scientific knowledge of Mars’ surface morphology and internal geological structure has been accumulated through satellite imagery and numerical topographic data using remote sensing technology, as well as seismic surveys by the on-site lander. Recent studies show that Marsquakes could be caused by the release of strain energy generated by the contraction of Mars. In particular, Marsquakes occur around the graben where many faults are existed and formed regularly spaced patterns. This implies that Marsquakes occur when the stress field of the Martian crust is an extension condition, and normal faults appear on the surface. We focus on the linear relationship between the fault spacing and the thickness of the mechanical layer as an approach to studying the internal structure from satellite images. Mechanical layer is a layer that composes of the same mechanical properties and is mainly bounded by lithology (Narr, 1991; Gross, 1993). The linear relationship between the thickness of the mechanical layer and the joint spacing has been studied and its slope is called the Fracture-Spacing Index (FSI) (Narr and Suppe, 1991). Soliva, Benedicto and Maerten (2006) showed that the stress drop zone (stress shadow) due to the fault activities affects the fault spacing. Figure 1 shows the approach used to estimate the thickness of the mechanical layer from the fault spacing on Mars. This paper aims to better understand the internal mechanical structure of Mars estimated by the geometrical pattern of faults on the Martian surface. We report the initial studies of this work. The lab-scale physical experiments and numerical experiments were presented to demonstrate the relationship between the thickness of the mechanical layer and the geometric pattern of fractures

Nov 29, 2022

By C M. Ramotsabi, F Bornman, W Erasmus

Spiral concentrators are gravity based separation devices used for the preparation of coal, iron and heavy mineral ores (Wills, 1992). Gravity concentration remains the main separation method for fine iron ore and is used extensively for treating many minerals. Gravity concentration methods separate minerals of different specific gravity by their relative movement in response to gravity and one or more other forces, the latter often being the resistance to motion offered by a viscous fluid such as water or air (Wills, 2006).The main operating variables for a spiral concentrator are the feed rate, the slurry concentration, the wash water addition and the position of the splitters used to separate the tailings, middlings and concentrate streams (Sadeghi, Bazin and Renaud, 2014). Wash water is an important control variable used to wash away entrapped light minerals from the concentrate stream (Burt, 1984; Bouchard, 2001). Sadeghi et al concluded the spiral operation to be sensitive to the wash water flow addition and resultant economic trade-off. Increasing the wash water flow rate increases the concentrate grade at the expense of the iron recovery.The paper addresses the effects of dripping wash water onto the concentrate stream of a spiral processing fine iron ore. The dripping wash water system offers a low flow alternative and could possibly provide a good balance between grade and recovery of valuable minerals without using excessive water. The Multotec SC20HC/7 WW spiral was used for the experimental test work. The spiral was tested at varying solids concentrations; the wash water rate and the splitter positions were kept constant.The use of wash water at 30 per cent, 35 per cent and 40 per cent solid concentration improved the Fe grade in the concentrate by about 1.5 per cent, six per cent and eight per cent respectively. The additional SiO2 rejected by the wash water is approximately three per cent, nine per cent, and 11 per cent at 30 per cent, 35 per cent and 40 per cent solid concentration respectively. Addition of wash water is shown to have minimum effect on grade at 30 per cent solid concentration, and Fe upgrades obtained with and without wash water were found to be similar. Notable upgrades were observed at 35 and 40 per cent solid concentration with wash water. The results obtained suggest that the additional SiO2 rejection by wash water increases with an increase in solid concentration. This suggests that the benefit of using the drip system is notable at higher solid concentration. It is believed that at lower solid concentration SiO2 particles are reasonably free to move around and are possibly less entrapped than at high solid concentration.The Fe grade/recovery and solid concentration relationship with wash water showed a non-linear correlation. The Fe grade increases with an increase in solid concentration up to a somewhat optimum point and then drops as solid concentration increases further. The recovery of Fe on the other hand follows a converse relationship with solid concentration, the recovery decreases from 30 per cent to 35 per cent solid concentration and then increases again at 40 per cent solid concentration. The increase in recovery at higher solid concentration could possibly be explained by the fact that the mass yield to concentrate also increases with solid concentration. Since recovery is a function of both grade and mass yield, the higher recovery at 40 per cent solid concentration is likely due to the high mass yield obtainable at 40 per cent solid concentration.The drip system could therefore possibly offer a safe guarding against grade and solid concentration variations without using excessive water, and possibly ensure that a product within specification is maintained.CITATION:Ramotsabi, C M, Erasmus, W and Bornman, F, 2015. Optimisation of wash water on an iron ore spiral to improve grade, in Proceedings Iron Ore 2015, pp 175–184 (The Australasian Institute of Mining and Metallurgy: Me

Jul 13, 2015

By S La Brooy, C Fountain

Throughout its history the mining industry has focused on the highest-grade deposits sited in the most convenient locations. The burgeoning global population and higher standards of living not only increase the demand for mineral products but also make it harder to mine and process them. The future will include the development of lower-grade, more complex orebodies, and orebodies in difficult locations. The industry will be expected to provide for humanityÆs needs while reducing its environmental footprint and maintaining profitability. This paper reviews some of the likely adaptations in mineral processing that will occur over the next 20 years. The challenges inherent in adapting to lower grade and more complex materials might be exacerbated by such factors as the availability of water and low-cost energy. In underground mining, higher energy costs are likely to foster further developments in underground preconcentration, especially for ores that can be upgraded at relatively coarse sizes. The adoption of underground crushing could also render material amenable to semi-dry preconcentration options such as might be achieved by the rotary classifier developed by CSIRO and being commercialised by RCR Tomlinson, or more modern versions of the hand-sorting of ore that use sensors based on colour or other suitable rock properties. The cement industry and some gold roasters have used the alternative of dry grinding and classification, which might also have a part to play in dry processing. There is also likely to be increased interest in options such as in situ leaching that further minimise the surface disturbance. Underground operations will have to balance the energy savings from reducing the amount of material brought to the surface and reduced surface disturbance against the practical limitations of installing and maintaining processing equipment underground. On the other hand, surface disturbance and energy issues in open cut operations will be balanced by potentially lower mining costs and higher overall recovery from the deposit.

Jan 1, 2008

The papers in this section of the conference and indeed the conference as a whole will rightly focus on the recent û the state of play around the Pacific Rim. However, to set the scene I propose to take a longer-term perspective. In so doing I wish to illustrate and emphasise that change is normal and natural û to paraphrase Bob DylanÆs 1963 classic, æThe times they are (always) a-changinÆ Æ. The challenge is how to cope with such change, in an industry, a corporate and a personal sense. A further challenge for geologists, both exploration and mine-based, and indeed for anyone, is to understand where they fit in the broader picture. For several reasons it is appropriate first to look briefly at the minerals industry in the Pacific Rim around a century ago. It was here in Adelaide in April 1893 that the first general meeting of the Australasian Institute of Mining Engineers (or The Australasian Institute of Mining and Metallurgy as it later became) took place and where the Centenary Meeting was held in 1993. The late 1800s and early 1900s was a period of extraordinary change in the minerals industry regionally and worldwide. The industry benefited from the economies of scale provided by improved mechanisation. It further benefited from the introduction of technically qualified professionals, such as chemists, metallurgists and mining engineers, although the usefulness of geologists had yet to be recognised commercially. With the rise of such professionals, technical societies formed and flourished. At the same time international financial markets and trade were expanding, a gold standard was widely supported and the financing of mining ventures was well established. Mining was an international business and its people travelled widely. As a consequence of the better-educated mining professional, the ready exchange of knowledge and the availability of finance, new processing techniques such as pyritic smelting, the cyanide process and flotation were developed. These, together with much improved materials handling in the mining and processing phases, dramatically changed the economics of the minerals industry.

Jan 1, 2004

By D Monaghan

Pumping water for dewatering and water supply is a major component of electricity consumption at mining operations and hence is a significant contributor of greenhouse gas emissions. Pump systems at a typical mine site can be broadly split between above ground centrifugal pumps (generally used for water transfer) and submersible borehole pumps (generally for dewatering and/or water supply). In contrast to above ground pumps, submersible borehole pumps can be subjected to varying duty points (total pumping head and flow requirements) as a result of changing bore water levels and yields, particularly in mine dewatering bores. Typically, much higher pumping rates are required at the commencement of dewatering to remove groundwater storage and to intercept sufficient groundwater throughflow to achieve target drawdowns. Once target drawdown levels are reached it often only requires much lower pumping rates to maintain target drawdowns. Pumps sized to remove the large initial volumes of stored groundwater often end up too large for the lower flow rate required for æmaintenance pumpingÆ. This often results in pumps operating inefficiently, a problem which can be made worse when pumps are throttled to reduce the pump output to better match the reduced bore yield. Current standard operating practice places little emphasis on the electricity consumed by pumps, with the focus often being on minimising capital expenditure (æIf it ainÆt broke donÆt fix itÆ). Submersible pumps can have extended service lives of ten to 20+ years. However as the capital cost of a pump typically represents only five per cent of the life cycle cost, the vast majority of the life cycle cost is energy usage.Through the implementation of a regular review of the operation of borehole pumps, significant reductions in electricity use and associated greenhouse gas emissions can be achieved without impacting the dewatering schedule. In most cases, the capital cost of replacing pumps is more than offset by savings in operating costs. These potential savings become even more significant when considering proposed future carbon tax levees.This paper presents examples of the opportunities for significant reductions in energy, greenhouse gas emissions and overall costs that can be achieved for a range of dewatering scenarios.

Jan 1, 2009

By N C. Steenkamp

The Northern Cape Province of South Africa is host to the Kalahari Manganese Field (KMF). The northern portion of the KMF hosts high-grade manganese referred to as Wessels’ type ore and is mined mostly from underground operations. WorleyParsons TWP is currently involved with the development of a ventilation shaft for one of these mines. The main challenge is to develop through the unconsolidated Kalahari material and weathered portion of the Karoo formation. These formations are preserved very erratically over short distances. A lack of understanding of the unique challenges presented for developing shafts in this area has resulted in the failed development of a shaft on an adjacent property and over-expended budgets on others.The renowned red sand of the Kalahari forms the top several tens of metres and overlies a horizon of gravels and calcrete that pose seasonally variable water ingress problems. A very stiff red clay horizon is then intersected. The Red Clay is prone to swellling during excavation and has been the main stumbling block on previous constructions. The standard approach has been to develop non-stop through this layer. The red clay is underlain by another horizon of calcrete, gravel and conglomerate that marks the bottom of the formation. The top of the Dwyka Tillite (Karoo Formation) is usually highly weathered and has a distinctive yellow colour. The weathered tillite is highly susceptible to drying and becomes friable. At reef-intersection, the combination of subhorizontal bedding and joints with the dominant subvertical faulting results in potential wedge failures in the manganese and ironstone units.This paper describes the geotechnical issues identified during the planning of the ventilation shaft and the risks associated with development through the Kalahari and weathered Karoo Formations. A new approach to developing ventilation shafts in overcoming these challenges is recommended.CITATION:Steenkamp, N C, 2014. Challenges of developing a ventilation shaft in Kalahari and Karoo formations, Northern Cape, South Africa, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 81–88 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

May I first of all say that I am fully conscious of the great compliment paid to me when I was invited to accept the Presidential Chair for this current year. I realise that it is an onerous task by reason of the fact that the Chair has been occupied in the past by so many able and distinguished men, and I realise also that I have been set a standard which is hard to emulate. "It is my desire however, in accepting the post that I may be able to contribute in some small measure to the further advancement Of the aims and objectives of the Institute and I thank you all for the confidence you have shown in me.Secondly, on behalf of the Company and in my Presidential capacity, I want to extend to each and everyone of you a hearty welcome to Whyalla and I hope that you will all return to your respective fields of endeavour feeling that you have had a most interesting, enjoyabIe and instructive time with us here in Whyalla.In this year of 1951 marking as it does the culmination of the first 50 years of Federation in Australia and yet another half century of human endeavour and progress, we are brought to a point where it is perhaps natural that we should pause, to review what has been achieved, in that span of time, and to look at the tasks ahead.It is no exaggeration to say that the story of Australian development since the inauguration of the Commonwealth 50 years ago has no more remarkable chapter than that of the-growth of its manufacturing industries.Each decade has borne witness to steady and substantial growth of our secondary industries and whilst it is true that our financial well-being still rests heavily on our primary production, we have, as a nation, moved surely in the direction of a more balanced economy. More and...

Jan 1, 1951

By R Dunne, S Hart, G Levay

While water represents a major proportion of the mineral pulp processed in flotation circuits, relatively little research effort has been committed to understanding and controlling the influence of water quality on this process. Historically, this probably stems from the perception of water as an inert transport medium. However, the changing attitude towards water as a valuable resource, has given impetus to increasing requirements to use relatively impure make-up water supplies such as treated effluents and a high proportion of internally recycled water. In turn, this has resulted in the need for a more detailed focus on process water quality and its control to minimise adverse effects on sulfide flotation. Along these lines, prior to commissioning of a new concentrator at their Cadia Hill Gold Mine, Newcrest Mining was proactive in examining potential water sources and the influence of water quality on flotation of their copper/gold bearing ore. An extensive water quality survey of all major potential water supplies to the concentrator was undertaken. The flotation performance of the Cadia ore in each of these waters was investigated on a laboratory scale. The results of these studies identified that water quality could indeed have a significant influence on the flotation process. Since operations at the Cadia Hill concentrator began, water quality surveys of both make-up water sources and recycled flotation circuit waters have been carried out on a regular basis. By doing this, a database of water quality has been established which can be compared with plant performance. In parallel with the water quality surveys, a series of laboratory flotation tests have been conducted using a standard ore and waters from various streams to monitor changes in flotation performance as a function of water quality. These tests have indicated that certain water types may have a significant influence on plant performance. More research is required to better understand the impact of water quality on sulfide flotation. This understanding will help operators to minimise adverse effects, while maintaining the best utilisation of available water resources.

Jan 1, 2003

This paper concerns a pragmatic approach to a problem that is common to many operations in the mining industry: how, over the short-term, to grasp the extent and distribution of long-term financial risk from environmental causes and reduce these risks strategically, in order to maintain stability and flexibility in the operations. Surprisingly, many companies operate without an environmental master plan or tools that can help managers measure and reduce financial risks. Such companies may be subject to unknown unacceptable financial risks from environmental causes. While many companies have some kind of internal system of environmental standards, it is often the case that such systems have uneven or limited effect, and offer no opportunities for visualising, measuring or managing aggregate financial risks from environmental causes. `Aggregate risks' are defined here as the calculated total expected financial costs to a company, or a subdivision of a company, from environmental causes at nominated operations over a defined time period. Aggregate risks take into account the type and magnitude of an environmental problem set, the likelihood of occurrence, and the time frame during which the problems will develop or solutions are required. For the large corporation, the 'amount of' aggregate environmental risk is a statistic that can be managed, along with other financial parameters, at the corporate level to improve the stability and predictability of operations, and protect the interests of shareholders. This paper concerns development of a management framework and a tool for the large corporation that responds to the need for managing aggregate environmental financial risks. The logical framework proposed to overcome the need for strategic vision is the Environmental Master Plan, and this is described in the next section. The analytical tool proposed to measure aggregate risks and provide relevant data and insights to managers, is called an Environmental Risk Management Information System, and its mechanics are described in a subsequent section.

Jan 1, 1994

By Beattie T

For many years explosive sensitized explosives were assessed using the ballistic mortar. The standard test used lOg of explo- sive initiated with a detonator. Over the past 30 years many non- explosive sensitized explosives and blasting agents have been developed. Most of these new explosives and blasting agents cannot be tested in the ballistic mortar as they are not initiated by a detonator. It is also known that all explosives have a criti- cal diameter. When the cartridge diameter is less than the criti- cal diameter a stable detonation cannot be produced and the explosive fails to propagate. For many blasting agents the criti- cal diameters are greater than 50mm and such large diameters cannot be tested in the ballistic mortar. The underwater test allows explosives to be tested in diameters greater than the critical diameter and to be adequately initiated with suitable boosters. The effects of the explosive on the water are easy to measure and the test provides a safe, convenient and reproducible means of assessing explosive performance. The reaction products are allowed to expand to a low final pressure. The underwater test can therefore be used to give a measure of the total expansion work of explosives. The detonation of an explosive induces a shock wave in the surrounding water. The profile of the shock wave can be meas- ured 3-6m from the charge and the energy in the shock wave cal- culated. Measurements over a range of distances show that the shock wave is attenuated as it travels through the water and the attenuation is different for each explosive. This makes it difficult to estimate the energy dissipated in the water between the charge and a single gauge. The reaction products continue to expand and displace water. The bubble continues to expand until the kinetic energy of the water is zero. The gas pressure in the bubble is now lower than the hydrostatic pressure and the bubble radius is a maximum. The higher external hyrdostatic pressure causes the bubble to implode. The bubble energy is the work done displacing the maxi- mum bubble volume against the hydrostatic pressure and can befound from the bubble period. It is not always easy to find a large enough pond for the bubble to expand undisturbed by the water surface and the containing boundaries. This makes it difficult to determine the bubble energy accurately in shallow Ponds.

Jan 1, 1988

By D B. Donato

Gold mining cyanide-bearing solutions can pose a risk, cause significant wildlife deaths and adverse public relations and result in non-compliance with regulatory conditions. The International Cyanide Management Code for the Manufacture, Transport and Use of Cyanide in the Production of Gold (the Code) was developed as a voluntary code to encourage industry-wide improvements in managing cyanide responsibly. The Code requires design and implementation of robust monitoring programs for compliance under the following standards of practice: 4.1, 4.4 and 4.9. A robust monitoring regime can be complicated as each processing and tailing system is different. The following systems are commonly used in Australia: carbon-in-leach (CIL); carbon-in-pulp (CIP); heap leach process ponds; tailing waste disposal systems; peripheral discharge, central discharge and in-pit disposal. Some terrestrial wildlife can be denied access by fencing tailing storage facilities (TSFs) or other physical barriers, therefore limiting wildlife interaction with cyanide-bearing tailing and solutions to mainly birds and bats. While wildlife monitoring programs for processing and TSFs contain similar core attributes, it is necessary to adapt monitoring to take into account the site-specific features of each system. These core attributes are discussed in this paper, with reference made to cyanide concentration and associated methodologies. The issue is considerably complicated if tailing solutions are deemed or discovered to be toxic to wildlife. Essentially cyanides are required to be measured to gain an understanding of the concentrations to which wildlife may be exposed. This usually equates to measuring the cyanide concentration of solutions entering and leaving a tailing system. To assess the risk to wildlife presented by tailing and heap leach systems it is necessary to monitor both the hazard (cyanide concentrations) and the exposure (live wildlife species, presence and interaction). These tasks need not be arduous and a system of simple frequent monitoring has been developed and implemented for Code compliance. The wildlife monitoring developed by Donato Environmental Services (DES) and used at mining operations departs from the industry norm. It documents observer effort, live wildlife presence, habitat and behaviour in a tailing system, as well as deaths and carcasses. A greater understanding of wildlife cyanide toxicosis associated with this monitoring approach will enable mining companies to adopt a proactive approach to significantly reduce, or preferably eliminate, the impact on wildlife and assist in gaining Code compliance.

Jan 1, 2007

By S Kodate, Ö Aydan, Y Suda, J Tomiyama

Fracture zones are commonly found in the Earth’s crust. These zones may cause very severe engineering problems. Therefore, the formation and the assessment of the mechanical characteristics of these zones is of great concern for rock engineers. A new double shearing jig was used to study the formation of shear zones in rock under static and impact loading conditions using the device developed by the authors. A series of experiments were undertaken to investigate formation on the formation and characteristics of fracture zones in laboratory. Although actual fracture zones are more complicated, various tests give some insight view of the formation of fracture zones as well as some information on their mechanical behaviour under both dynamic conditions and static conditions. The authors report the outcomes of these experiments and discuss their implications in practice.

Nov 29, 2022

By K Faure

At Sams Creek a gold-bearing, peralkaline granite pophyry dyke intrudes Ordovician-Silurian metapelite and quartzite. The granite porphyry dyke has a thickness of up to 40 m, extends discontinuously for about 8 km, and intrudes thin lamprophyre dykes along its contacts. The granite dyke and gold-bearing sulphide and quartz-siderite veins within it have been deformed and recrystallised during several phases of folding, the youngest of which is Early Cretaceous.   The unaltered granite porphyry is composed of phenocrysts of perthite, arfvedsonite, aegerine and quartz in a groundmass of the same minerals, with accessory ilmenite, rutile and fluorite. K-Ar dates of amphibole from the granite gave ages of 226 and 246 Ma, but these ages may be a minimum due to resetting during the thermal and deformation events that have affected the area. Unpublished Ar-Ar data on amphibole from the granite show disturbed spectra with high temperature steps around 300-315 Ma, which is consistent with the age of A-type granites in the Buller region. Further age dating of primary and hydrothermal minerals in the granite is continuing. At least three stages of hydrothermal alteration have been identified in the granite. Stage I alteration is characterised by high fO2 magnetite-siderite ¦ biotite, which is cut by thin quartz-pyrite veinlets (Stage II). These are cut by Stage III sulphide, quartz and siderite veins, and pervasive silicification represented by quartz-perthite-albite-rutile ¦ pyrite-siderite-sericite assemblages overprints the earlier alteration stages. Lamprophyre is altered to a siderite-chlorite-sericite assemblage. Stage III sulphide veins are composed of arsenopyrite + pyrite ¦ gold ¦ galena ¦ sphalerite ¦ chalcopyrite ¦ pyrrhotite ¦ graphite, deposited by low fO2 H2S fluids. The gold contains 18-30 wt% Ag and up to 1 wt% Bi. Temperature of vein formation was estimated from vein quartz fluid inclusion homogenisation temperatures (Th 260-355oC, average 330oC), arsenopyrite-sphalerite thermometry (310-365oC) and quartz-albite stable isotope thermometry (340oC). The altered granite and the veins have been deformed, and recrystallised and competent sulphide minerals are fractured and brecciated. Alteration and mineralisation are confined to the granite porphyry and adjacent lamprophyre.

Jan 1, 2004

By A Kuras

Segmental tunnel linings are becoming more common in Australia. One current project employing a segmental lining is the City West Cable Tunnel (CWCT) in Sydney. The project has been commissioned by Energy Australia and is currently being constructed by Thiess Pty Ltd. The project includes 1.6 km of tunnel boring machine (TBM) driven, segmentally lined tunnel. The majority of the CWCT will be excavated through Hawkesbury Sandstone. The tunnel is required to carry a 132 kV electrical circuit under SydneyÆs central business district (CBD), between Haymarket and Energy AustraliaÆs City North Substation on Sussex Street. The segmental lining has been designed as a 3.2 m internal diameter, 200 mm thick universal ring with six trapezoidal segments. The design and detailing of this segmental lining presents some noteworthy challenges, including exposure to saline groundwater, and the exclusive use of steel fibres for flexural and tensile concrete reinforcement. This paper describes some of the key elements of the segmental lining design. These include:the case for choosing segmental linings over other forms of tunnel construction;the major design checks required of a segmental lining including ground loading, hydrostatic loading, joint bearing, joint rotation, ram loading and the early strength lifting case;the benefits of using steel fibres over conventional steel reinforcement;the design approach used for steel fibre reinforced concrete;the application of 3D computer modelling in the design;the provision for components including connector dowels and gaskets;the design for passive fire resistance; andthe design for durability of steel fibre reinforced concrete in a saline environment. Segmental lining design requires the application of specialist design approaches. Input is required by the construction team, as the methods of demoulding, handling, transportation and installation impact on the lining design. As the segmental lining is functioning as immediate ground support and also a permanent lining, high standards of manufacture and construction quality control are required to ensure that the 100-year design life is met. The requirement for a watertight tunnel means that detailing and installation of the EPDM gaskets is of importance.

Jan 1, 2008

The Australian Constitution specifies certain powers of the Commonwealth Government to be used in its capacity as the national government. Certain of these broad powers result in the Com- monwealth having a facility to play an important part in the development of the mining industry. The State Governments, however, by virtue of their wide powers to regulate matters within the boundaries of a particular State, are more directly involved in the day to day administration and standards of activities of mining operations. In this respect the Common- wealth has something of a dual role because of its "State-like" responsibilities for the mainland Terri- tories. The components of the role that the Common- wealth Government discharges in relation to the mining industry are qualified to varying extents at particular times by the political persuasion of the Government. In absolute terms the components are as follows. 1. Economic management. The Commonwealth's fiscal and monetary policies have an important effect on industry as well as on State finances. In particular, the taxation regime employed by the Commonwealth Government is of direct importance to economic decision-makers in the mining industry. 2. International matters. International trade and commodity matters are, more and more, becoming an everyday part of the conduct of a nation's foreign affairs. 3. Exports. The Commonwealth Government, via the constitutional powers over overseas trade, have exercised varying degrees of control over mineral exports to achieve particular objectives. 4. Foreign capital and investment. Australia in general, and the mining industry in particular, is and will continue to be a net importer of capital. There appears to be bipartisan political agreement in Australia that foreign investment policy must be enunciated to ensure that investors. are in no doubt that Australia welcomes beneficial investment and technology from overseas. 5. Environment and Aborigines. Governments, both Commonwealth and State, have in recent years become more involved in these areas in response to their interpretations of community aspirations. 6. Energy. Access to assured supplies of energy is now viewed, by Governments worldwide, as a desirable asset to ensure the well-being of a nation's people and industries.

Jan 1, 1978

This paper is directed at the problems flowing from Australia's capital gains tax (CGT) on the disposal of exploration and mining tenements both in Australia and overseas. It will seek to identify the issues and give some idea of the dollar consequences of decisions lacking forethought. The paper should not only be seen in the context of Australian tenements. CGT applies to the disposal of any assets by an Australian resident anywhere in the world. Offshore incorporated companies are not necessarily free from CGT risk where it can be shown that control management and control of the relevant company is in Australia. Also the disposal by non residents of Australian tenements are potentially caught by CGT. Some will ask what has taxation got to do with a valuer who merely determines the value of assets. These days no determination can be blind to the consequences. Whether the consequences can encourage a movement in value is another thing dependent upon the circumstances; but? A role of an experienced taxation consultant is to point out parameters within which associated professionals can work. The parameters will vary from case to case, but these when clearly indicated may be of help to persons such as valuers. When one comes down to it real estate salesmen are never wrong. They have a feel for the market and almost through self fulfilling prophesies achieve sales at their guestimates. Whether they could have achieved higher considerations become virtually academic in the process. Of course I am not suggesting that tenement valuers can be compared to real estate salesmen, or am I? What is the value of a tenement? Is it the DCF/NPV type of generated value based on a large number of variable factors (ie what one may call the fundamental value)? Or is it what another may pay to purchase that tenement if it were on the market at an instant point in time? How big is the market, the quality of the bidders, the size of their purses, the needs of the buyer for comfortable fit, the premiums for foreigners, the standard of the marketing, the industry intelligence level of the bidders, the obligation to farm/sell down? The list goes on endlessly. One question must be.asked-"Is a range of values acceptable for tax purposes". ie Would any tax consultant ever provide a valuation to the Australian Taxation Office that indicates three or more possible values ie

Jan 1, 1987

By A Cooper

The current financial climate has given rise to fears that falling mineral prices and tight credit will force mining companies to cut back on production and new project development in a bid to cut costs and conserve cash. However, a prolonged squeeze on global supply can have only one result: a massive and potentially explosive demand for metals in the not-too-distant future. A resurgent global economy will also generate dramatic new demand for oil and energy, with a return to higher oil prices likely. How then should the mining industry plan for the future? In-pit crushing and conveying (IPCC) could lead the way as a partial or complete substitute for trucks. In 13 of 15 studies undertaken by Sandvik and Snowden, comparing IPCC with truck-optimised pit designs, IPCC generated operating savings ranging from US$0.18 to US$0.82 per tonne moved, compared to trucks. Trucks have higher operating, maintenance and energy costs than conveyors. New emission standards on diesel engines may make them more emission friendly but less efficient in terms of energy usage. With far more efficient energy use and cheaper operating costs per tonne moved than trucks, conveying offers an attractive alternative for the bad times ahead and into the apparent energy depleted future. When evaluating alternatives, a reasonable first step would be to conduct a scoping level study which analyses the differences in capital and operating costs between a truck and shovel operation and an IPCC solution. The study can also determine what type of IPCC is best suited to the particular mining application. The results can then be used to decide whether a more detailed study is justifiable. IPCC is a proven process that, with a fresh mindset, can make a significant improvement to mining operations. Sandvik (as an OEM with a full suite of IPCC equipment) can undertake these studies in ten working days in conjunction with Snowden or any other independent mine planner who knows how to schedule for IPCC. Because most mining industry personnel have been æborn and bredÆ on trucks and shovels û this paper focuses on some of the practical considerations necessary to make IPCC systems work that the Sandvik Technical Services Group has encountered during these studies.

Jan 1, 2009

The underground coal mining industry in Australia has, in the last 30 years, undergone a revolution in production methods, techniques and results probably unparalleled elsewhere in the world. It can lay claim not only to leading the fight against pneumoconiosis and setting high safety standards generally, but has at the same time recorded comparatively high rates of increase in output per man shift. The latter has been achieved as a result of progressively matching the latest in production and underground transportation equipment with significant changes in seam development and extraction techniques and the introduction of stress-relieving extraction methods unique to the world scene. However, the seam recovery factor is still too low. Apart from the overall objectives of maximising production and commercial returns with the greatest safety, there must be a concentration towards maximising seam recovery, particularly in high seams. The search will continue for systems which are more completely continuous mining operations than the present stop-go operations, with longwall having long term potential in this regard, but as yet not sufficiently developed to engender confidence for its more general use. Techniques developed in the last 10 years make the development and extraction of deeper seams, perhaps to 2500 feet or more, feasible with continuous miners as well as longwall. The future will see a greater use of continuous shifts at mines, larger mines with more sophisticated management organisation, extensible belts at the face, better systems of immediate roof support at the face, remote operation of face equipment, greater use of roof bolts and the longer roof cables. With commercial confidence in coal mining now virtually assured to at least the turn of the century, the stage is set for heavy capital development in the industry which will undoubtedly include major research into the whole area of mining methods and equipment. We must ensure that our contribution to such research equitably matches other coal producing countries.

Jan 1, 1975