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By Blair J. R

In the Bayer process, bauxite is leached with caustic soda, forming a solution of sodium aluminate, from which hydrated alumina is precipitated. The efficient operation of the continuous form of this process requires that the concentration of caustic soda be controlled. A computer simulation of the concentration of caustic soda has been conducted to provide information, regarding the dynamic behaviour of caustic concentration, which is not available from normal plant data. The basis of the simulation is a state- space model of an alumina refinery, linearized about the normal operating condition. The formulation of the model, with the relevant approximations and assumptions, is outlined. The simulation of the mudwash section of the. plant is described in detail. A continuous model of the mudwash, having time-varying coefficients, was driven using operating data from an alumina refinery. The modelled response showed reasonable agreement with the recorded plant response.

Jan 1, 1977

By P W Haines

The McArthur, Balma (new name) and Habgood Groups are thick (up to 4.5 km) correlative sequences of shallow water evaporitic carbonates, mudstones and sandstones that are exposed largely within the Batten, and southern and northern Walker Fault Zones (Batten and Walker Troughs) of the McArthur Basin respectively. Recent re-mapping of the Walker Fault Zone has provided data for refined stratigraphic correlations between these groups. Two significant hiatuses are now recognised within the Balma Group (base of Vaughton Siltstone and base of Yarrawirrie Formation) and these may represent tectonically-generated sequence boundaries which may correlate with similar local hiatuses within the McArthur Group such as at the base of the Teena Dolomite and Lynott Formation respectively.

Jan 1, 1994

This paper describes an ongoing study into the management systems developed by mining operations in Papua New Guinea to address particular public health issues in the workforce (primarily communicable and lifestyle diseases). The first stage of the study involves the analysis of the site health and safety management system documentation of three major mining operations in Papua New Guinea, producing a descriptive summary of each system. In the second stage of the study these summary descriptions are evaluated using a maturity model constructed through a detailed review of literature. Experience with the evaluation process is then used to refine the maturity model. The analysis performed in the study is used to develop a process for creating a maturity model for mine site health risk management based on a theoretical risk management framework, and refining it through empirical evaluations of the actual systems in place on site. Companies can use maturity models as a guide to organisational improvement, which in the context of the study will assist the operations in developing their systems for the management of health both in their workforce and in local communities.

Jan 1, 2007

By D R. Swinbourne, Y H. Yang

Calcium ferrite slag has gained prominence in the copper smelting industry over the last decade due to the emergence of continuous converting as an established technology. As smelters move towards processing which is higher in intensity, more efficient and more environmentally acceptable, its use is likely to increase because it has technical advantages over conventional iron silicate slag, which include a higher magnetite-holding capacity, lower copper losses to slag and a lower viscosity. Calcium ferrite is currently the converting slag of choice in the Mitsubishi process at operations in Japan, South Korea, Indonesia, Canada and Australia, and in the Kennecott/Outokumpu flash converting process in USA. However, users of this slag have experienced problems in containment due to its highly corrosive nature and low viscosity. As use of this slag becomes more widespread the containment problem will assume greater importance. Consequently, work has recently been carried out to establish the mechanism of refractory attack and devise means to retard it. This work will be critically reviewed in this paper.

Jan 1, 2000

The impact on metallurgical operations of the hydrocarbon energy price hike can be greatly alleviated by recourse to alternative fuels. Information is provided on fuels such as coal, coke, coal-oil mixtures, manufactured gas, wood and charcoal; techniques such as direct and indirect combustion, pulverised fuel injection, slurry burning, fluid bed combustion and various gasification processes. Actual examples of metallurgical operations are used.

Jan 1, 1981

By Maslov LA

We have considered the following characteristics of the crust and upper mantle of the Pacific Belt: seismic wave velocit> anomalies, mechanical stress and shear deformation rate fields, heat flow and the pattern of metallogenic provinces of the Belt. It has been noted that there exist certain regularities in distribution of the above mentioned geophysical characteristics and metallogenic zones within the Belt, displayed by prevalence of the lithophile elements in the Asia-Australian part of the Belt, and of the chalcophile ones within the American part.

Jan 1, 1995

By Y Yang

Despite the importance and usefulness of basicity in metallurgical slags, the optimum quantitative expression of it has remained elusive, partly due to the fact that the precise concept of basicity has not been properly clarified. The two basic approaches to the concept of basicity are the Lux-Flood, which perceives basicity in terms of the activity of the free oxide ion, aO2-, and the Lewis, which perceives basicity in terms of the ability to donate negative charge. The former has been almost universally adopted in the area of metallurgical slags, while the latter has been increasingly accepted in the field of glass chemistry. In this paper, some difficulties of the Lux-Flood approach are pointed out, including the need for indirect measures of aO2-, which have proliferated in recent years. Accordingly, it is suggested that the Lewis approach has a good deal to commend it, and that the quantification of it in terms of optical basicity is the best measure of basicity available, which should therefore be more widely applied in metallurgical slags than it currently is. The fact that there are intrinsic problems in evaluating the optical basicities for the transition metal oxides is acknowledged, and a new scale is recommended. The patterns of iso-optical basicity lines in ternary systems are shown to agree well with the pattern of iso-activity and iso-capacity lines under appropriate conditions.

Jan 1, 2000

The decision to contract or owner mine should be independent of, and should be made before, definitive estimated cost comparisons could be available. There is substantial potential risk of estimated cost comparisons being flawed due to difficulties in compiling comparable estimates for differing business objectives, errors and omissions or because of significant bias. In the current economic environment, escalating cost pressures potentially lead to increased incidence of disputes in mining contracts. The apparent cost of contractorÆs profit and overheads has tended to become more significant to owners. Economy-driven trends towards higher levels of performance and commercial risk for contractors, and the potential for more adversarial, difficult management; with attendant disputation between contractors and owners, have encouraged development of so-called ærelationship contractsÆ û partnering or project alliance contracts. The paper discusses the issues, circumstances when owner mining or contract mining is favoured and perceived advantages and disadvantages of contract mining. The implications of owner-perceived core business and core skills and outsourcing are also discussed. Techniques of introducing objectivity into the decision to owner or contract mine using matrix analysis or benefit comparisons are described. A disciplined procurement process should deliver a decision to owner or contract mine independent of, and prior to, any definitive comparison of estimated costs. A generic procurement process model is provided as a basis for discussion. Risk is discussed generally and as a significant factor in comparison of estimated operating costs. Consideration of risk and any prudent cost treatment are promoted as necessary pre-requisites to any comparison of estimated costs. The paper develops the concept that the decision to owner or contract mine should be based on real benefits that become obvious in the early stages of the development, particularly the procurement process; and before definitive estimated cost comparison can be available. In the context of this concept estimated cost comparisons tend to be confirmatory. Problems with comparing estimated ownerÆs operating costs with tendered contract prices are also discussed, particularly recovery of capital cost of equipment; and the owner minerÆs trade-off of operating risks for the residual contractorÆs margin attributed to overheads and profit. The paper concludes that sole reliance on a comparison of estimated ownerÆs operating costs with tendered contract prices in deciding to owner or contract mine is questionable and likely driven by a need to satisfy specific in-house customers.

Jan 1, 2003

Around 35 Mt of industrial clays were produced in 1994 under the broad classifications kaolin (25 Mt), bentonite (8 Mt) and attapulgite/sepiolite (2 Mt). A brief review of world sources and markets is given as background to Australia's small production (0.5 Mt) but developing interest in industrial clays. Clay markets have changed significantly over the past 30 years resulting initially in consolidation and expanded production from traditional high-grade clay sources but also creating opportunities for development of new discoveries. Decline in the use of clay-based refractories has come at a time of strong growth in demand for refined kaolin for the paper industry. Traditional markets for bentonite as oil drilling muds, iron ore pelletising and foundry bond sands are mature and in overall decline. Today, bentonite has a significant share of the growth market in pet litter which a few years ago was dominated by attapulgite/sepiolite clays. Both bentonite and attapulgite/sepiolite have good prospects for increased demand in environmental markets both in containment of hazardous wastes and sorption of toxic substances. In common with all industrial minerals, markets for clay minerals will demand continuous improvement in product quality and consistency. Development of new and improved products will be increasingly the responsibility of the raw material supplier. In order to remain competitive, this will require a substantial commitment to quality assurance and research and development. Increase in market share will come for those producers able to translate developments in their products to cost savings or increased competitiveness for the industries that they Supply.

Jan 1, 1997

Experience in evaluating grade control at operating mines has shown that a number of similar errors re-occur in diverse settings. These can be broadly classed as technical errors, and procedural or grade contra management errors. Examples of typical errors are presented a; generalised case studies. A brief explanation of why the recommender solution worked is also presented for each case.

Jan 1, 1993

At Renison Limited, on the West Coast of Tasmania, modern trackless decline mining is practised to exploit the various tin bearing sulphide deposits. With footwall accesses, one of three adaptations of horizontal mechanised cut and fill, 1. unsupported, 2. pillar supported,and 3. unsupported - resuing is used to stope each defined ore block. The stoping method is basically determined by the dip and true thickness of the ore with emphasis on high ore recovery. Extreme flexibility is possible by the selective mining of stope lifts, the consumption of development waste as fill and the utilisation of the same mobile equipment in all phases of production. This has resulted in high productivity and low cost per tonne of ore.

Jan 1, 1977

By Mousset-Jones P, McPherson M. J

This paper explains and discusses a computer program developed to deter- mine the optimum combination of fan pressures that will give a required distribution of airflows in a mine ven- tilation system. The program is based on an existing simulator, VNETPC and two experimentally developed relationships: (1) linearity between fan pressures and added regulator resistances and (2) a non- linear convex function relating the system air power and the fan operating Pressures.

Jan 1, 1988

By Daxian Z, Youdi Z, Shucai Y

The Huolinhe surface mine is a very large-scale surface coal mine, located in the north-east area of China with a production rate of 1.2 Mtpa. Its coal haulage system has a large capacity, long transportation line and high degree of automation. The system comprises two crushing plants, many belt conveyors, four surge bunkers, one loading bunker, one coal storage and five end product bunkers. In this paper, the network patterns of semi-continuous systems in surface mines are studied, the reliability calculation methods and a simulation model are established and the software for computing the reliability of a semi-continuous system is worked out. By considering the whole coal haulage system in the Huolinhe surface mine, the authors developed the system reliability-numerical simulation method. The steps and the computing results of this method are described in detail. Through the calculation, we can master the present situation of system reliability and the main factors impairing system reliability, expose the system weak links, put forward the ways of enhancing system reliability and furnish the basis for improving the system and equipment. The way of increasing capacity and methods of enhancing system reliability are further raised.

Jan 1, 1995

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

By Denisov GA

Conventional processes for disintegration of ores are characterised by low selectivity and cause damage to the components of their structure. It affects their liberation and recovery which are connected also with the inevitable formation of extreme fines. In the world practice recently came into view 4 trend to grinding of materials within a thick layer (in a bed layer), which provides a substantial selectivity of liberation, for example, of kimberlite. The degree of diamond preservation in the final product is highly increased. However, this method causes a considerable overgrinding of material. A new method of intralayer vibro-impulse breaking of materials providing an easily adjusted force acting at the layer and timely removal of product size grains from the grinding chamber has been developed in Russia.

Jan 1, 1993

By Millen M. J, Rainey S, Sowerby B. D

The control of size reduction in grinding machines and circuits may be enhanced by a continuous and accurate measurement of the particle size of solids in appropriate process streams. This paper presents a brief review of commercial particle s

Jan 1, 1997

In preparation of this Paper, the emphasis has been laid on the commercial rather than on the technical and scientific aspects of coal evaluation. It is intended to describe and comment on the principal factors which currently determine the selection and procurement of coking coal for the steel industry, and is not based on the results of any original research by the author. Evaluation of different coals for strictly thermal uses, for gas production or other chemical applications has not been attempted, and comparisons of coal with other fuels have been excluded: the paper is concerned only with coals for the production of blast furnace coke. The discussion is strongly related to, and illustrated by, British, and to some extent, other Western European practice, but it is hoped that the general conclusions may have a wider application.

Jan 1, 1975

Quite apart from economic considerations, the following performance parameters must be considered when selecting an explosive for a particular blasting operation. 1. total energy yield/kg, and more particularly, strain energy/kg and bubble energy/kg of charge 2. charge weight/m of blasthole 3. sensitivity of the charge 4. water resistance of the charge The effective division of an explosive's total energy into strain energy (SE) and bubble energy (BE) is explained as is the influence of each energy component on blast results. Because some rocks require a high strain energy for effective breakage, while others are most satisfactorily fragmented by bubble energy, values of SE and BE are more meaningful than those of total energy. Unfortunately, our extensive knowledge of the effects of certain variables on total energy has not yet been completely supplanted by the influence of these variables on SE and BE values. Relative SE/kg and BE/kg values are presented for a range of explosives. The 'charge density of ammonium nitrate/ fuel oil (ANFO)-type explosives is essentially constant throughout the length of the charge; because of their compressibility, slurry

Jan 1, 1974

By Ash M

The world-class iron ore mines at Mt Whaleback, Torn Price and Paraburdoo located in the Hamersley Province of Western Australia must mine the Mt McRae Shale to obtain high grade ore from the Dales Gorge Member of the Brockman Iron Formation. The Mt McRae Shale contains a black pyritic shale lithology that reacts with ammonium nitrate-based explosives. This paper provides an overview of the problems associated with mining this reactive rock type as well as the development of a comprehensive procedure to safely and efficiently blast, excavate and dispose of this material. The strategy used to develop the procedure involved raising the awareness of relevant site personnel to the risks associated in mining the Black Pyritic Mt McRae Shale, obtaining the commitment of these personnel that a detailed procedure was required and that any procedure developed must be followed, otherwise the potential risks such as premature detonation were high. It was also necessary that an on-going training program be implemented so that all relevant new employees would be educated as to the reasons for adhering to the Black Pyritic Shale Procedure.

Jan 1, 1995

By Coates J. R, Firth I. C

The Imperial Smelting Furnace at Cockle Creek, NSW, was constructed in 1961 and is the oldest facility using the Imperial Smelting process in operation. In recent years there have been significant improvements in many areas of the operation, including production, safety, hygiene and environmental performance. Steps taken to achieve these improvements are described. Plans to secure a profitable future while meeting environmental requirements are outlined.

Jan 1, 1993