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By P M. Downes

Porphyry-related skarns are common around thePacific Rim. Examples include Cadia and Goonumbla (Australia) Ok Tedi (PNG) and Ertsberg and Grasberg (Indonesia). Although usually treated as separate to the adjacent porphyry copper-gold (Cu-Au) deposit, skarns near porphyry deposits are commonly inextricably part of the larger Cu-Au system(s). Using Cadia as the primary example, we demonstrate that large, zoned, calc-silicate skarns necessitate very large porphyry systems. The Big Cadia and Little Cadia Fe-Cu-Au skarns are associated with the Late Ordovician to Early Silurian high-K calc-alkaline to shoshonitic Cadia Intrusive Complex (CIC). Together, these skarns total ~40 Mt of Cu-Au ore but are much smaller than the adjacent Cadia EastûFar East, Cadia Hill, and Ridgeway porphyry-related Cu-Au deposits. Historically these skarns were large, economically significant and highly controversial deposits. Porphyry-related skarns typically have well-developed calc-silicate and ore zonation. At Cadia, classic skarn zonation has been mapped between Cadia Quarry (proximal) and Big Cadia (distal). Over this 800 minterval, mineralogy trends from: proximal garnet > pyroxene, grading to; fe-oxide-rich skarn; and distal haematite-epidote-rich skarn. At Little Cadia, analogous but symmetrical alteration zonation is present. Big Cadia formed from fluids that migrated laterally within calcareous units and were sourced from strongly altered quartz monzonite phases of the CIC at Cadia Quarry. Isotope studies and mass-balance calculations suggest that prograde and retrograde skarn alteration was caused by magmatic dominated fluids. They also indicate that the mapped alteration system at Cadia Quarry is insufficient to account for the total volume of Fe present at Big Cadia. Despite the typically oxidised nature of many porphyry systems, not all skarns in the porphyry environment are oxidised. Assimilation of carbonaceous sediment by hydrous, alkaline intrusions could lead to reduced Au skarns rather than porphyry deposits. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Veal FL

Technological changes in Portland cement manufacturing during past years have reflected changes in the economics and availability of various types of fuel such as coal, fuel oil and natural gas. The industry consumes a sig- nificant quantity of both thermal and electric- al energy. The nature of the process and its chemical constraints does however permit the use of comparatively low grade fuels such as high ash coal and high sulphur oil. In striving for increased daily kiln outputs and conservation of energy, there is a worldwide trend towards the use of dry process plants. Wet process kilns of about 2 500 tonnes per day assume massive component sizes which present difficulties in manufacture, and transport to plant sites. Large capacity dry process units in excess of 8 000 tonnes per day are now in operation using precalcination techniques in which part of the fuel is introduced in the static preheater section ahead of the kiln while the balance is added to the kiln in a conventional manner. This technique has virtually doubled the potential output of any given single kiln.

Jan 1, 1976

By H P÷llmann

Calcium aluminates, calcium aluminate ferrate and calcium aluminate sulfate were synthesised by solid-state reaction, sol-gel method, a self-combustion method and by a polymeric precursor process. For chemical sintering methods the base chemicals CaO, CaSO4, Al2O3 and Fe2O3 were used. As precursors for sol-gel synthesis metal nitrate hydrates and Al2O3-Sol were used. In order to synthesise pure phases by a self-combustion reaction glycine was used as fuel and nitrates as metal components. In the polymeric precursor process metal nitrates and diluted H2SO4 were used as metal components and the resin was made using citric acid (C6H8O7) and ethylene glycol (C2H6O2). Precursor phases synthesised by these different methods were sintered step-by-step in order to investigate the crystallisation. Further on single phases were hydrated and their hydration behaviour was studied by heat flow calorimetry, X-ray diffraction and cryo-transfer scanning electron microscopy. Due to the different synthesis procedures different hydration reactions and microstructures of the phases will be shown.

Jan 1, 2008

A Study of Extracting Vanadium from Stone Coal Using Cyclic Oxidation

Sep 13, 2010

Tholeiitic metabasalts comprise at least five geochemically distinct mafic volcanic associations of Late Palaeozoic age within the Gympie Province, southeast Queensland. Geochemical features indicate that parental magmas of the various metavolcanic suites were generated in contrasting tectonic regimes, although each of the suites shows some affinities with eruptives from convergent plate margin settings.Basalts from the Highbury Volcanics of the Gympie Group are island arc tholeiites (IAT) formed during an immature stage of eruptive activity in an intra-oceanic arc. They are unique among the analysed metabasites in possessing high Zr/Nb (Zr/Nb - 30) and very high Ba/Nb, and as well as low Ti/V, Ti/Zr and Ti/Y. These features are explicable solely in terms of contributions from a depleted, convecting upper mantle source, and large ion lithophile element (LILE) enriched fluids ascending from subducted oceanic crust.

Jan 1, 1990

All companies and individuals who embark on a business venture incur costs. For the most part these costs can be conveniently categorised, firstly into capital and operating costs and then into the various elements of these major cost centres. Although the nature of expenditure naturally differs as between industries certain broad cost types are characteristic of all heavy industries. The capital costs of gaining access to an orebody, equipping a new mine, building a treatment plant and perhaps refining and smelting facilities are likened to capital expenditure by a manufacturer on new plant and equipment required for an expansion or new product innovation. Similarly the day to day costs of labour and materials employed in the running of a mining operation can be likened to similar costs in other heavy industry. There is another group of costs that are not so easily categorised. Most industries incur unavoidable costs that do not form part of the direct or capital costs of physical production. These costs include taxes and other payments to government and research expenditure. The mining industry has a particularly heavy burden of non-production costs and it is the objective here to highlight and analyse a few of them. These costs are exploration expenditure, infrastructure expenditure, royalties and income tax. This is not to suggest that these are the only major non-production costs that the mining industry needs to bear. The industry may incur significant costs for environment protection, land tenure maintenance and on liaising with Government on a wide variety of matters. It is for reasons of subject manageability that the list is confined to the four costs mentioned. For the mining industry, exploration and infrastructure expenditure, royalties and income tax have several distinguishing features. Firstly, they are generally proportionately large costs. Exploration and infrastructure expenditure for example, could well exceed mine development costs. Depending on how royalties are levied, they may be very high in relation to profits earned and many in fact exceed profits. Secondly, except for income tax, they are costs that are generally not payable by other industries. Exploration expenditure is in some respects comparable with industrial research and development. However, because mines are wasting assets exploration is necessary for survival, and it is likely to form a larger part of costs per dollar of profits or sales than R&D. It can therefore be said that exploration is of far more significance to the miner than R&D is to the typical industrial company. Furthermore, unlike exploration expenditure, R&D results are transportable and patents permitting, transferable. The infrastructure burden that miners must carry is unique to the industry. Whereas urbanised industry is not usually liable for the capital cost of power, water, transport, townships and community facilities, the miner must finance these projects himself. Neither the payment of royalties, nor of course, income tax are unique to the mining industry. Royalties are more properly described as a unique charge on some primary industries but however described, they are a charge that manufacturing and service industries do not have to pay. Whilst we all pay income tax, the mining industry's uniqueness derives from the special problem that the industry has in arriving at annual net income in view of the capital intensity of the industry, partly due to expenditure on infrastructure, the indefinite life of capital equipment and its unpredictable residual value, funds expended on exploration and long lead times associated with a mine development. The third distinguishing feature of these costs is that, with the possible exception of exploration expenditure, they are heavily influenced by the policies and actions of Government. As such the industry has a responsibility to promote the industry by emphasising its potential to improve national product including exports and by requesting that the Government provide for the industry in its long term planning and seek its co-operation to prevent the industry incurring inequitable penalties relative to other industries.Finally, exploration and infrastructure expenditure are significant because they are front-end charges on a project. When due allowance is given the time value of money and the deferment of income from a mining development to which they relate, exploration and infrastructure expenditure assume greater importance than the raw money expenditure suggests. For all these reasons, exploration and infrastructure expenditure, mining royalties and mining income tax are worthy of detailed study. This is the purpose of this paper. The objective is to examine the determinants that give rise to them and provide some thoughts on their impact on on-going and potential mining developments and, where relevant, to make some suggestions as to how they may be minimised.

Jan 1, 1977

A continuous casting machine, of the Concast curved mould design casting billets in four strands, was commissioned at the Newcastle Works of The Broken Hill Proprietary Co. Ltd., in November, 1967. Quality assessment of early casts from this plant indicated that steel cleanliness was sometimes inferior to that of equival- ent ingot cast steel. Extensive trials to develop a modified deoxidation technique were not successful in improving clean- liness to the desired level. A "contra-flow" gas shroud, to cover the steel stream between the tundish and the mould, was developed, and proved successful in achieving the required levels of product cleanliness. The inclusion content of six grades of steel ranging in carbon content from 0.10 to 0.70 per cent is examined, and an attempt is made to explain theoretically some of the results obtained.

Jan 1, 1972

Solution transport of gold and silver has occurred as a result of the chemical weathering of many Western Australian epigenetic gold deposits. Evidence for the remobilization of gold exists in the form of small crystalline octahedra, mustard gold, flake gold, and coatings on iron-oxide. This "secondary" gold is of high purity (low silver content). It is believed that the high chloride content of laterite profiles combined with the acid produced by the oxidation and hydrolysis (ferrolysis) of iron has caused dissolution of Au/Ag and Au/Te alloys. Gold, and less frequently silver, is subsequently reprecipitated in the profile nearby.Pyrite, which is a ubiquitous accessory of gold in vein or lode systems, is probably an important source of iron for the development of acidity. Where carbonate is abundant in the primary assemblage, neutralization directs the oxidation of sulphide to a path which produces thiosulphate, and an alternative type of Au/Ag oxidation process. Sulphide/carbonate ratios in the vein system, and adjacent wallrock are seen as important in determining the course and extent of remobilization in the oxidized zone of gold deposits.

Jan 1, 1984

This technical note describes a problem with WANG82, a ventilation network analysis programme. The problem was highlighted by Renison Ltd when using the programme on large, complex networks. Under certain circumstances the programme produced incorrect results or failed to converge to a solution.

Jan 1, 1986

By Brien R. J, O&apos

Faster and more efficient methods of producing and refining iron and steel are imposing severe conditions on the refractory materials used to contain these metals in the molten state. In order to provide refractory linings which will give the desired service life and maintain unit availability at an economical level, it is necessary to appreciate the aggressive environment in which the refractories operate and determine the reaction mechanisms by which the refractories are destroyed. Only by such studies can the most suitable refractory or refractory combination for a particular unit be selected. Examples of refractories selection and reaction mechanisms are discussed for blast furnaces, BOS vessels, AOD vessels, steel ladles, vacuum degassing units and continuous casting.

Jan 1, 1976

Comminution of solids is surely one of the oldest technologies which even in this day and age of DNAs, chips and space exploration continues to challenge our scientific acumen and engineering ingenuity. In essence, this challenge is two-fold. One, as much as three to four per cent of all electric power generated world-wide is consumed in crushing and grinding primarily because the utilisation of energy is woefully poor. Studies have shown that the efficiency of mechanical size reduction processes is of the order of 1.5 to 12 per cent only (Schoenert 1986). Two, with the grinding technologies available to us, we have, at best, inadequate and, at worst, almost negligible control over the shape of the comminuted particles, size dispersion of the ground mass, and the sharpness of mineral liberation. Low energy efficiency and lack of control in the sense mentioned above have far-reaching implications for resource conservation, performance of down stream unit operations, and damage to the environment. Our problem is in fact central to the mineral-energy resources triangle shown in Figure 1 which depicts the close interrelationships among mineral resources which are becoming poorer in content and more complex in mineralogy each day, energy resources which are depleting rapidly without any viable alternate on the horizon, and environmental concerns which can no longer be ignored. It is evident that any improvement in the efficiency of the comminution process impacts directly on the control of environmental damage, conservation of energy and the economics of the operation. These concerns have special relevance for the processing of non-ferrous ores.

Jan 1, 1992

Proposals designed to use stockpiles and buffer stocks to achieve price stabilization and better resource use have a long history. They are super- ficially simple to understand. The benefits seem clear. And yet I am well aware that this is not a simple subject: the more one studies it, the more complex it becomes. Worldwide interest in re- source management, while receiving fresh impetus from the OPEC actions, also has a long and chequered history. Those venturing into such ter- ritories must be forewarned of the traps and pit- falls which abound. Interest in these schemes has waxed and waned over the years with the fluctuating fortunes of the producers or consumers. As I write this paper towards the end of 1977, I am acutely aware of the low ruling prices for zinc, copper, and nickel. These sacrifice prices remind me that it is difficult, for example, for a surveyor, to be calm and rational if he is up to his neck in a swamp full of crocodiles. He might be forgiven for forgetting that the aim was to drain the swamp! I am also aware that when swamps are drained, painful and dangerous stumps sometimes stick out. Hence, in looking at the subject of stockpiles and resource management we must not set our sights too high, perhaps not initially hope for perfec- tion, if we want to secure worthwhile changes. My approach is to acknowledge a bias for the market system. We have, however, had experience (remember the 1930s) of some weaknesses in the untrammelled operation of free markets. Thus our international economic relationships over the past 20 or 30 years have been based on a desire to retain as much as possible of a liberal world trading system backed by such organizations as the GATT, IMF, and the U.N. to ensure the necessary cooperation. Some nations have seen this system work only partially in their best in- terests. GATT, for example, has been reasonably effective in liberalizing trade in many manufac- tured goods but far less so in regard to agricultural or semi-processed goods.

Jan 1, 1978

Exceptionally weak ground, usually associated with faulting, unanticipated groundwater pressures or flows and exceptionally high stress concentrations are some of the hazards which confront the underground excavation engineer. One or more of these hazards can seriously delay or even halt a tunnel or mining project, and methods for predicting these hazards are urgently required, particularly for projects involving high speed drill and blast or tunnelling machine excavations.This paper explores the current availability and the potential for the development of tools and techniques for the prediction of these hazards. It is concluded that systematic and automated geological data collection and interpretation represent the most promising avenue for development. It is suggested that there is room for the use of expert systems in which the computer is used to assemble and organize practical underground excavation experience into an interactive decision making system.

Jan 1, 1985

The undeniable fact of life in the next 25 years will be the increasing difficulty of the physical conditions of Australian orebodies facing future miners. We are all familiar with names such as the 3000 orebody at Mt Isa, Hilton, Century, Macarthur River, Cannington, and Ernest Henry. These projects represent a significant. proportion of the planned underground mine development in Australia. Moreover, many of these new orebodies are an order of magnitude more difficult to mine and process than their predecessors. Extraction will be from deeper and potentially more hazardous working environments. Occupational health and safety considerations will place unprecedented demands upon mine operators and technology providers of the future.

Jan 1, 1994

By T Iwadachi, T Fujisawa an, G R. Alvear

A large amount of Be2C and BeO is formed during the Cu-Be alloy production process, because beryllium is a highly reactive element. Carbide and oxide formation impairs the production yield and the quality of the Cu-Be alloy products, and therefore should be minimised. As a first step for solving these problems in the process, the following thermodynamic properties of the Cu-Be-C-O system were investigated. Based on the results, the equilibrium relations of the Cu-Be-C-O system were clarified and the operational conditions of the current Cu-Be alloy production process were also examined and discussed.

Jan 1, 2000

By R Kahnt, S Jahn, D Baacke, M Eckart

Relocation into the Lichtenberg open pit mine of about 110 million m3 of sulfide-bearing and ARD-generating waste rock piled up on the surface is the most important and cost-intensive single surface restoration project conducted by WISMUT GmbH at the former Ronneburg uranium mining site. The waste rock comprises for the most part Palaeozoic shales, limestones and diabases with pyrite contents of up to seven per cent. Waste pile relocation began in 1992 and is scheduled to be completed by 2007. The approach used for relocation has been extensively described elsewhere (Jakubick et al, 1997; Hockley et al, 1997; Chapman et al, 1998; Paul, 2003). Following completion of the backfill that will be up to 60 m above the initial ground level, a dry cover will be placed on top of the backfilled mine wastes. The area to be covered amounts to about 220 ha. Design planning for the final cover placement of which is to begin in 2004 had to be based on a comprehensive cost-benefit analysis over and above compliance with legal requirements. The crucial question to be answered in this respect was to determine û in addition to the expenditure required to ensure reuse, radiation protection and soil protection û the extent to which additional time, effort and money were justified in order to minimise contaminant release from the unsaturated portion of the backfilled pit contributing to total releases into the ground water and possibly achieve savings in long-term operating costs for the on-site water treatment plant. Optimisation was based on contaminant balance modelling for the entire site reproducing dominant physical and geochemical processes. Among the specifics underlying the cover design is that contaminant release from the backfilled open pit must not be considered independently of that from the adjacent flooded underground mine and that a major part of the backfilled open pit will also be submerged. Following weighing of cover-related short- and long-term costs it was found that higher construction costs for the various cover options will not be offset by cost savings in the long-term water treatment. As a consequence of pit flooding, even a costly multiple cover including an impermeable layer will only insignificantly impact on concentrations and loads at ground water spill over points. As a result of comprehensive studies and investigations, a combined cover of cohesive soil material from on-site excavation overlain by a 0.4 m thick storage layer to restore natural soil functions for revegetation was derived and submitted for approval. Together with hydraulic measures, this approach is to meet any requirement in terms of radiology, water protection, stability, erosion protection, and reuse.

Jan 1, 2003

In New York City, on the walls of the library of the United Engineering Societies are these words:"Engineering-the art of organising and directing men and of controlling the forces and materials of nature for the benefit of the human race," but who, reading the schedules of even our best engineering schools, would infer that engineering is an art or that it should always havejn mind the benefit of the human race? While it must be remembered that our engineering schools exemplify the British cult of the amateur, that cult which lets men who have never attended a lecture on "Education" or perhaps nevereven read a book on it, become enginering teachers by profession (and so educators by inference), the root of the matter is to be found in the fact that our educational aims, and consequently our educational practice, seem suited much better to the position engineering held in the community in 1900 than to the position it holds to-day. This civilization of ours has developed, !;loth for good and for ill, into one based largely on engineering achievement; technical progress is so continuous and so rapid that thevalue of descriptive knowledge of current practice is ever lessening; enough must be imparted to make the young graduate immediately employable, and this amount is sufficient for illustrating the principles on which practice is based and on which its advance depends, but the young graduate's technical progress depends much less on his having acquired additional knowledge than on his ability to acquire knowledge, so, paradoxically, the more useful knowledge there is availabJe the less of it the student should be taught.Less conspicuous but fully as important is the enlargement of the field of work of engineering graduates, especially its extension to the initiating of policies and to the broader problems of administration. At present the road to such positions lies normally through a considerable period of professional work, but it is by no means unlikely that the field will soon include much that requires little professional expel'ience. At all events it is safe to say that the changed. and changing position of engineering in the communitydemands the attention of the engineering schools and that profitable discussion of engineering education demands some understanding of the real nature of education and of the part which engineering plays in the life of the community.THE NATURE OF EDUCATIONUnfortunately "to educate" supplies an example of how words degenerate in meaning; most people regard it as the equivalent of "to instruct"; a small number feel they have gone to. the root of the matter when they say...

Jan 1, 1941

Australia contains a variety of iron ores, differing in grade, chemistry, size distribution and genesis. While a proportion of this ore is used world-wide as blast furnace lump, much of the material mined is high grade fines, requiring agglomeration (usually sintering) before blast furnace reduction. Sintering studies initially concentrated on the production of ferrous material of high iron content, coarse size and sufficient cold strength. In recent years research involving pilot plant sintering, precise test procedures and mineralogical analyses has focussed on the additional sinter properties of hot strength and reducibility. Aspects of mineralogical studies applied to iron ore sintering are described.

Jan 1, 1989

By Schoning W. L

Ore deposit models form the basis for numerous other economic decisions in the mining process. The success of these economic decisions therefore depend directly on the accuracy of the ore evaluation process. The Geology Department at the Sishen Iron Ore Mine is responsible for the generation of a reliable geological computer model of the rock material with predicted grades. This information is then utilised for further ore reserve calculations, mine planning, production scheduling and grade control. Owing to a very complex geological orebody, grades and beneficiation characteristics differ significantly from sample to sample. This means that ore evaluation is a difficult process and great reliance is placed on computer techniques. In 1993, preparation for the ISO 9002 quality certification of the mine motivated the Geology Department to hold formal `problem solving' sessions in order to identify and revise problem areas in operating

Jan 1, 1995

Digital Simulation of Particulate Processes The inherent complexity of mineral particulates (shape, size and mineralogical texture) has challenged conventional simulation model approaches for decades. Much effort was expedited in using mathematical assumptions to accommodate stereological effect. With the advance of instrumental methods such as x-ray microtomography 3D structure can, in many cases, be measured directly. The information derived from such measurements provides direct input to building the structural digital model. In addition digital simulation methods that enable creation of process realistic particulate properties in an efficient digital computer space have demonstrated their effectiveness to model a variety of realistic packing, sorting and multi-phase processes. The paper reviews recent advances in the use of information derived from 3D micro-tomographic imaging and laser scanning technology can be coupled with digital methods to enable simulation of tablet compaction and dissolution, filtration and permeability, column packing and leaching kinetics, packing and cementation of nuclear waste. By assigning 'properties' to a digital zone (voxel) in the computational space it is possible to mimic the realistic characteristics of quite complex particulate mineral processing systems. The system self-adapts to correct the coherent particle characteristics (shape, size, compound, porosity) with time. Such simulations are useful to elucidate the sensitivity of system performance to variations in process parameters. Dimensional scaling of the approach is also possible, as the case studies will illustrate, in deploying the method to both small (micron) and large (m) features. The use of process realistic simulations presents experimental challenges in code validation. It is in this context that other tomographic methods play a role in direct 3D measurement of system behaviour such as electrical and optical sensors.

Sep 13, 2010