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By T Kang, V Sahajwalla, L Lu

During devolatilisation, physical behaviour of coals was investigated in horizontal electrically heated furnace with an inert gas atmosphere, and gasification rates of four coal chars and coke were measured thermogravimetrically in a carbon dioxide atmosphere at temperatures in the range 1100oC - 1500oC. The volume change of chars was also measured in horizontal electrically heated furnace at various temperatures. Both reactivity and the activation energy for the gasification of coal chars were found to be strongly influenced by pore structure and the carbonisation conditions employed during preparation. CO2 reactivity of chars increases with increasing reaction temperature, and particularly increases more rapidly over 1300¦C. CO2 reactivity of coke is lower than that of non-coking coal chars in the range of 1100¦C to 1500¦C. CO2 reactivity of chars with smaller pore area and bigger pore diameter is less than that of chars with bigger pore area and smaller pore diameter. During gasification, the volume of chars did not change significantly at the lower temperatures of 1100¦C and 1200¦C, but at the high temperatures, 1300¦C to 1500¦C, the volume of chars quickly decreased due to ash softening and melting. The CO2 reactivities of the chars are controlled by the mixed control of chemical reaction and pore diffusion in the temperature range 1100¦C to 1300¦C, and by bulk diffusion in the temperature range 1400¦C to 1500¦C.

Jan 1, 2000

During underground mining, rock mass changes can occur as a function of the mining sequence and excavation processes. Mining-induced rock mass damage can occur due to redistribution of static stresses and the application of dynamic stresses from blasting and seismic activity. These rock mass changes can result in a degradation of strength of the bulk rock mass and the remaining rock surrounding existing excavations. Rock mass damage near existing excavations which lead to excavation-scale instabilities such as rock fall, excavation closure, or visible rock mass fracturing can detrimentally affect the safety and profitability of mining operations.The focus of the current work was the prediction and assessment of damage to mine infrastructure occurring in relation to the blasting of a sublevel open stope. The study case involved a 60kt stope located in a highly-competent rock mass at a large Australian sublevel open stoping mine. The mine infrastructure of interest for investigation included local stope access development, critical access and haulage development crossing a regional-scale fault, an explosives storage magazine and a ventilation return air raise. The methods used to predict or assess the blast-induced damage to each infrastructure element in response to stope extraction were:- intact rock strength testing,- discontinuity mapping,- linear-elastic static stress modelling,- blast-damage mapping,- near-field blast vibration monitoring and analysis,- geophysical assessment using inferred stiffness and wave velocity methods, and- post-extraction void assessment.The results of the detailed blast damage prediction and assessment program at the mine site have been discussed by the primary author elsewhere (Fleetwood, 2010). The current work will address blast-induced damage to mine infrastructure as a result of extraneous blasting vibrations from stope production blasting. A method for predicting the amplification of excavation surface motions from reflecting body waves will be discussed as well as the results of damage mapping around the study stope. The results of the damage mapping program identified blast-induced damage that occurred to the surface of the explosives storage magazine and local stope access development. No damage was observed at the main fault crossing or return air raise where higher vibration amplitudes were measured or predicted.

Dec 6, 2010

By R Mackay, J Brereton

On 30 June 2020, the Mine Land Rehabilitation Authority (the Authority) superseded the Latrobe Valley Mine Rehabilitation Commissioner as the independent overseer of Victoria’s declared mine rehabilitation. Currently, only the Latrobe Valley’s three brown coalmines are declared, with each mine at a different stage of rehabilitation and closure planning: Hazelwood ceased mining in 2017, Yallourn is scheduled to end mining in 2028 and Loy Yang in 2035. The three declared mines are very large, close together (Figure 1) and present significant environmental risks that must be mitigated during rehabilitation and post closure. In addition to fire risks, the brown coalmines are inherently unstable and require continuous monitoring and management of ground movements and groundwater pressures. Since 2007 several damaging events have occurred, highlighting the difficulties of achieving long-term stability, even with good landform design and rigorous ground control management plans

Aug 2, 2023

Simulation and animation models have developed rapidly over the past decade. Even so, the current state-of-the-art can be viewed only as being in a state of continual development with improvements in both hardware and software constantly being

Jan 1, 1998

By Kister H

Hoesch HUttenwerke AG, Dortmund, West Germany, is an integrated steel work of the Estel-group. The nominal annual production capacity-is about 7 Mio tons of steel. Hoesch has along experience in operation of diffe-rent types of slag granulation plants and of utilization of the granulated product. This experience is used to granulate a large amount of blast furnace slag and to process it in own cement plants and produce blast fur-nace cement.

Jan 1, 1979

By Bucknell WR, Clarke DE

The paper provides a company's view of the relative merits of various valuation methods and outlines the basic approach it takes to the valuation of an exploration property. The negotiating process and methods of acquiring an interest in an exploration property is discussed The valuation methods discussed are: 1. Exploration Expenditure. 2. Real Estate. 3. Joint Venture Terms. 4. Rule of Thumb. 5. Net Present Value - Discounted Cash Flow. 6. Geoengineering.

Jan 1, 1994

By Floyd JM, Richardson P

The extension of theoretical and laboratory studies of the roasting of tantalite and cassiterite concentrates from Greenbushes Tin Limited to pilot and semi- commercial plant developments is detailed. A rotary pilot furnace was used to prove the feasibility of the process and a semi- commercial plant was constructed at Greenbushes to produce large quantities of roasted calcine. The additions and conditions of the laboratory study were employed to achieve marketable grades of calcine from the two materials. As well as producing calcines with less than 0.1% Sb, most of the tin in tantalite was recoverable to a separate fume product. Tin fumed during cassiterite roasting on a semi-commerical scale amounted to less than 1% of the tin in feed.

Jan 1, 1986

This paper discusses the concepts of core risk associated with mining projects and operations and illustrates the types of core geotechnical risks and consequences that may relate to a range of different mining methods, with recommendations on risk management procedures to ensure that the core risks are under constant and ongoing scrutiny and priority management focus. These core geotechnical risks can and should be identified at the initial mining method selection stage, during a feasibility study. They should form part of the auditing of the project and the decision-making regarding the project viability. They should then be built into the ongoing management structure of the project, right through into ongoing operations, with regular audit and review.

Jan 1, 2003

By L Strezov, J Herbertson

Conversion of industrial waste materials to valuable resources would essentially take part in an ecologically sustainable future. There are still large amounts of undervalued biomass wastes generated from a diverse range of industries that are disposed in landfields. They have potential to produce valuable materials and fuels, such as charcoal, bio-oils and bio-gas through thermal upgrading. In order to enhance the efficiency of the thermal upgrading process, comprehensive characterisation of the raw biomass materials is essential. We have developed a novel thermal characterisation method that utilises computer aided thermal analysis incorporated with a gas analyser. The method was applied on two biomass materials, wood sawdust and bagasse. The paper discusses the results obtained with the novel thermal characterisation technique.

Jan 1, 2006

The Court rejected the suggestion that CRAE had actively misled DMR concerning the worth of its tenements. The Court agreed that CRAE remained silent about certain significant information concerning CRAE's own tenement area. It was a significant question as to what duties CRAE'was under, given that it was in joint venture with DMR in respect of one of the tenement areas. Did that joint venture create an obligation on CRAE to disclose everything it knew? The Court said no. The Court said that the fiduciary duties were defined by the terms of the farm-in agreement between DMR and CRAE. When the Court examined the disclosure obligations within the confines of the contract, it held that CRAE had not breached those terms.

Jan 1, 1990

The State of Western Australia has a land area of 2 525 000 km2, and is well endowed with minerals and petroleum products. In 1989 - 90 these products were valued at nearly A$10 500 million.

Jan 1, 1992

Geochemical data on Australian granites and pegmatites9 and the.,mineral.components of these rocks, is presented and compared with that obtained in similar studies in.the U.S.òS.R and:.elsewhere.The petrochemical character of tin granites and the trace.-chemistry of their component minerals, particularly biotites, have some significance as ore guides in prospectingfor tin.The primary geochemical dispersion of tin can be readily tested both in the laboratory and field by colourimetric methods, after volatilization with ammonium iodide, using modifications of.the method described by Wood (1958).Secondary dispersions of tin in residual soils or.alluvia can likewise be readily tested by rapid colourimetric methods in the field, but simple hydraulic methods,.handling larger-. sample volumes, give reliable outlines of dispersion patterns.

Jan 1, 1963

Although geophysical methods of prospecting have proved indispensable in the search or oil deposits elsewhere; it is only 'in recent years that they have been used to any significant extent in Australia. The increase in their use has been quite remarkable over the past two or three years, due in Sao small measure to the encouragement given by means of Commonwealth subsidy. There is no doubt that the use of' geophysical methods will coxi-tinue to increase and this increase could be greatly accelerated as and when oil is discovered in commercial quantities,This review of their use A in Australia and the remarks and statistics are confined to work on the mainland. There has been, a substantial amount of geophysical work in Papua, but as operating conditions are so very different to the mainland Papua has been regarded as a separate province.

Jan 1, 1962

By Seeley D, Buckley N, Goodall J

Improving the performance and reducing the costs associated with export logistics chains is critical to the competitiveness of export coal mines. The fundamental practices associated with the use of export logistics chains made up of mine, trucking, rail and port operations are being challenged by the advent of third party operators on rail systems and the use of the Internet.Whilst individual mines can improve their processes to drive down their mining costs, they face major challenges in their endeavour to improve the performance of export logistics chains and reduce the significant logistics costs of moving coal from the mine to export ships, via the shared infrastructure of rail systems and ports. There is an increasing realisation that global competition is not only between mines but between coal export regions that are defined by their rail system and ports infrastructure.

Jan 1, 1998

By Alvarez A. R, Garcia H. l

A fuzzy expert system, DIME, has been developed, under Matlab v 5.1. to assess the coal and gas outburst risk in underground mining. Expert systems and fuzzy logic are powerful tools to manage information represented by linguistic statements,

Jan 1, 1998

Severe development difficulties were experienced soon after in-seam mining commenced at Appin Colliery in'1962. Thirteen years later no significant pro- gress had been made in overcoming some aspects of this development problem. Some success had been achieved in destressing roadways both in development and pillar extraction. Longwall retreat mining had shown promise of being highly productive but at an extremely high cost in terms of development requirements both in number of roadways and intensity of support in those roadways. No real advance was made in the problem of driving the first heading of a group of headings under conditions of apparently high stress in directions other than the preferred mining directions, although failure of the roof in this heading did seem to give easier work in the subsequent headings driven particularly if they were driven on narrow centres.

Jan 1, 1976

While specific definitions of the main categories of mineral reserves and mineral resources are becoming well established through the efforts of the Australasian Joint Ore Reserves Committee (JORC) and the Combined Reserves International Reporting Standards Committee (CRIRSCO), there has been perhaps less attention paid to the standardisation of language used in the definition and reporting of Mineral Exploration Results and a clear understanding of the transition to Inferred Mineral Resources. This is an area of significant importance to small and medium sized enterprises in the mineral exploration sector as it represents in many cases the only tangible information by which the reader or potential investor can evaluate the future potential of such enterprises. By its very nature information in the Mineral Exploration Results category is incomplete, and frequently complex, and it is open to a broad range of interpretation by readers of various competency levels and disciplines. Many will have a short-term speculative view rather than a long-term perspective, with others out deliberately to misrepresent the information, and as such it can have an enormous impact on investment decisions if the risks associated with this information being reported are not fully understood. Authors of reports on Mineral Exploration Results, who may be Competent Persons or company directors, have to put themselves in the shoes of the reader of the report, second-guessing if you like what the reader will understand by a report, which in many cases will be of a highly technical nature. This raises reporting dilemmas and questions that require to be understood and addressed. Looking at reports on Mineral Exploration Results from the other side, readers have a degree of responsibility as well, particularly if they engage in an advisory or communications role. The tendency of commentators, journalists, analysts, and bulletin board posters to over-exaggerate the significance of a particular exploration result is all too familiar. Questions arise here as well about whether there should be more regulatory supervision and control exercised over those who use this information, all of whom greatly influence investment decisions, and many of whom have no idea there is a Reporting Code, far less an understanding of it. Examples are given and questions raised to illustrate the dilemmas surrounding the reporting of Mineral Exploration Results. In order to retain credibility with markets it is incumbent on companies to be transparent, not to be selective and to report all material information. On the other hand, information has to be taken and read in its proper context in order to avoid fuelling dramatic and unjustified company share price escalation. Timing of course is another factor that can affect the market price of shares, which may be beyond the control of those making the reports. Emotive and imprecise language, however, when reporting Mineral Exploration Results, coupled by speculation, can trigger damaging short runs on shares and destroy credibility where formerly there was long-term promise. The paper will review how Mineral Exploration Results are dealt with in various jurisdictions, and conclude that there has to be a balance between prescription and the tempering of undue optimism on the one hand, and the entrepreneurial spirit, which the industry needs, on the other.

Jan 1, 2002

By Miller J. D

The mechanism of adsorption of gold from alkaline cyanide solutions by carbon has been the subject of much research over the past decade. In this paper, the nature of the gold cyanide adsorption phenomenon is investigated, particularly with respect to carbon substrates and associated surface adsorp- tion sites.

Jan 1, 1991

Marketing of mineral products has not yet succumbed to the degree of pre- dictability and exactitude that is fam- iliar to the engineer or metallurgist in pursuing their profession. Whilst the Great Market of the world economy dic- tates circumstances for the sale of min- eral products, there are more than just buyers and sellers in the determination of the revenue received by the producer. For the engineer or metallurgist he will be required to gain an understanding of these participants and of the peculiar languages of the market place. This will be only one of his tasks in learn- ing to communicate with society, as his responsibilities increase as he climbs the ladder of success. There is un- doubtedly a need for better statistical information so that producers and sell- ers can make an appropriate and earlier response to market conditions. There is in addition, a need for more aggressive concern by raw material producers for the development and promotion of better end use of their products. Undoubtedly the marketing of mineral products will be more influenced by the direct involv- ment of government agencies than has been the case in the past. Whilst that 1. Director - Marketing & Finance, North Broken Hill Limited.

Jan 1, 1975

By Toussaint LF

A brief history of the mineral sands industry is given from a radiation protection standpoint, with gamma radiation and inhalation of radioactive dust being identified as the main sources of radiation exposure of persons working in the plants. The principal sources of gamma radiation exposure are identified and the history of early bagging methods is discussed. The concept of ALARA is introduced and the impact of the "bulka bags" (and more effective monazite storage facilities) are detailed as illustrative examples of dose minimization, together with the requirements for the transport of monazite. The dose from radiation received from inhaled dust is dependent on a number of parameters of the dust, some of which are not well known. ICRP 30 (1978) makes recommendations relating to the intake of radionuclides by workers. These recommendations are discussed with respect to the inhalation of dust containing thorium. The possible pathways of radioactive material throughout the body are also described. The effect of having parameters that differ from ICRP 30 is discussed and suggestions are made relating to measurements that can be carried out to more accurately determine these parameters. Since in some instances the exposures to dust yield personal doses which may exceed the annual ICRP 30 based limits, it is necessary to define more accurately parameters of the dust so as to determine more accurately personal Doses.

Jan 1, 1986