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By Vidalinc, Raffoux

Longwall faces producing in the order of 20,000 tons per day of raw coal are presently running in the Houilleres du Bassin de Lorraine of Charbonnages de France. Production levels of twice that level pose some technical and economic problems of coal cutting, ventilation, coal and equipment transportation in the.face and from the face to the sur- face. The peak productions of the equipment in use today, the results of trials with new equipment, the utili- sation of forecasting models (some in the form of software), allow us to fo- resee feasable technical solutions to these problems. They will first be considered in the best possible context (thick- ness, dip, non gassy, soft coal, good strata, no faults). This will give. the necessary conditions to reach daily output'of that level. A sensitivity analysis of these- figures to the effective natural con- ditions will then be undertaken and the implication of such a project on health and safety (dust, climate ...) will be carefully considered. A concise technical and econo- mical approach will permit us to fore- cast the economical interferences of such production units and specially the consequences of sudden variations of the output (downtimes, failures, etc). From this investigation, goals for technological development and re- search areas will be outlined to be able to reach this production target in the XXIst century.

Jan 1, 1988

By Lawson F

The leaching behaviour of BHAS copper matte in oxygenated acidic sulphate chloride solutions at 85¦C has been studied using samples containing 34% copper, 41% lead and 12% sulphur. Copper sulphide in the matte, essentially Cu2S was found to leach in two distinct stages. Similar to the behaviour of pure chalcocite, copper dissolution in the first stage was affected by the availability of oxygen in solution. The presence of chloride ions in the leachant was essential if there was to be any leaching in the second stage (which usually commenced after about 40% of the copper had been taken into solution). Lead sulphide in the matte was oxidised to lead sulphate and formed a shell around the partially leached matte particles. Electrochemical studies showed that this lead sulphate and/or sulphur produced during leaching can form a passivating layer around the copper sulphide. However, this layer was disrupted when chloride ions were present. A Plackett-Burman analysis was used to determine the species in the recycled leach solution that affect the leaching of copper. Under the experimental conditions used, in the first stage the rate of copper dissolution was influenced by the concentrations of sulphuric acid, Zn(II), Cu(II), Fe(III) and Cd(II). In the second stage, the rate was futher modified by the concentrations of Cl(I) and As(V) ions. In solutions of low acidity and high As(V) concentration, insoluble copper arsenate formed which coated the partially leached matte particles and acted as a barrier to futher reaction.

Jan 1, 1989

By Hanna P

Coal geologists are under pressure to minimise exploration expenditure, maximise interpretation confidence and produce the results often too soon. This pressure continues to increase as companies are forced to evaluate borderline economic deposits which are usually deeper and more hazardous, such as the Togara North and Togara South projects in Central Queensland.

Jan 1, 1998

By Turner T. M, Jorgensen F. R A

The tendency of the concentrate to ignite was studied using four techniques, namely, laminar flow furnace, fluid bed, thermal analysis and boat-in-furnace. Exothermic activity occurred at two temperatures: minor activity in the vicinity of 200¦C, major activity at 330-350¦C. The low temperature reaction was due to the ignition of a small amount of free sulphur while the major activity was associated with the ignition of the sulphide minerals, notably pyrite. To avoid ignition of the sulphide minerals, the gas temperature should not exceed 300¦C and the oxygen content of the gas phase should be as low as possible. It was shown that little of the arsenic in the concentrate entered the gas phase during drying.

Jan 1, 1987

The development of the SECV brown coal open cut at Loy Yang will require depressurisation of aquifers both within and below the coal seam sequence in order to maintain open cut stability. Prediction of future open cut dewatering requirements at Loy Yang Open Cut and evaluation of the regional consequences of dewatering has required development of a detailed hydrogeological model of the Loy Yang area. The complex stratigraphy of the coal seam and aquifer/aquitard sequences at Loy Yang have been analysed and integrated with the hydrogeological concepts developed from regional groundwater studies to formulate a realistic hydrogeological model as a basis for finite-element flow modelling.

Jan 1, 1988

By Viney K. G, Molinia A. B

The Hellyer Pb-Zn-Ag orebody in western Tasmania was discovered in 1983, and mine production at a rate of 250 000 tonnes/yr commenced in 1987. Expansion to 1 million/yr will be completed by early 1989. Exploratory development to gain access to the orebody, to provide a 20 000 tonne bulk sample for pilot plant work and to confirm mining conditions and orebody continuity was undertaken using conventional drill and blast techniques and large diesel trackless equipment. A ventilation shaft was raisebored. Development in this phase totalled 2 815 m and provided a sound basis for rapid expansion of the mine.

Jan 1, 1988

By Will D. P

A 328 m, 2.4 m diameter raise-bored shaft has been equipped with a modular ladderway system to provide a second means of egress from Aberfoyle's Hellyer Mine in Tasmania. The modular ladderway consists of platforms, ladders and service pipes assembled at the surface and progressively lowered down the shaft. This system provides a rapid, safe and economical non-entry approach to equipping a shaft. The modular construction and single suspension allows for future extension or for reuse in another shaft.

Jan 1, 1988

By Richardson F. A

Techniques for flotation optimisation were investigated at Cobar [lines Pty:Ltd., in anticipation of the proposed installation of a computer and on-stream analysis. Successful laboratory and pilot plant tests for flotation performance optimisation using the Simplex Evolutionary Operation Technique (Simplex) lead to a full scale plant test using this method. The index developed for" Simplex response evaluation of flotation performance was based on metallurgical and economic criteria. This index was further modified to minimise the effect of head grade fluctuations. The test program was carried out on one of two parallel copper flotation circuits to allow comparison with normal "manual" operating control, and was conducted for thirty eight shifts. Results from the test section operating under Simplex direction were superior to those obtained using normal "manual" operating techniques and demonstrated the use of the Simplex Evolutionary Operation Technique as a method of reducing reagent consumption in flotation but, at the same time, maintaining satisfactory metallurgical performance. Experience in the use of the technique indicated the need for modifications to the rules of Simplex operations. Modifications were proposed, tested and appeared satisfactory.

Jan 1, 1973

The preferred alternatives in heap design and their motivation are identified as- -normal heap leaching, to be generally applied wherever possible, - flooded vat leaching, to be appliedwhere wetted ore lacks adequate cohesion or if limited space necessitates it,- thin layer leaching, to be applied where deleterious vat chemistry necessitates it.A number of the following features would probably be incorporated in the optimization of normal local heap leach operations- pre-cyanidation - pre-agglomeration - retaining walls- staged (counter-current) heap treatment- control of calcium levels- reduced pH and trickler irrigation

Jan 1, 1984

By A J. Moore

Predictive assessment of surface blast vibration requires the identification and quantification of significant factors, and the summation of their combined effect. Methods available for the prediction of significant factors are described, and examples are given of the combined use of these methods to evaluate alternative proposals.

Jan 1, 1999

By Bruce See J

Oxidation of artificial Imperial Smelting Furnace lead bullion was performed during cooling between 1180 and 820°C in order to attempt to produce a tin-rich dross.The addition of sodium carbonate together with stirring increased the tin content of the dross when oxidation was carried out with air or PbO on zinc-free bullion.Zinc in the bullion during oxidation resulted in a decrease in tin concentration of the dross due to zinc oxidation and copper entering the dross.

Jan 1, 1987

This paper describes the effects of physical variables in dewatering of mineral slurries with air as the filtrate displacing medium. Using a mathematical model with material related constants measured in laboratory dewatering curves are simulated for vacuum and pressure filtration. Four different mineral slurries are studied. Basic dewatering curves with variation in air-pressure are shown with iso-energy lines. Variables such as air pressure, feed concentration, cake thickness and cake formation pressure are discussed.

Jan 1, 1989

By Henderson J

Iron ore samples selected from the Deepdale, Iron Prince and Mt. Newman ore bodies have been pelletised on a pilot scale plant and subsequently reduced under laboratory conditions by hydrogen or carbon monoxide. Pellets approximately 1 cm in diameter have been reduced by hydrogen over the temperature range 5000- 900¦C and the results examined by thermogravimetric, microscopic, electron probe and x-ray techniques. After an initial time delay it was found that up to 95% reduction the rate of reduction could be described by a transport con- trolled porous model, in which the effective diffusivities of hydrogen in theòpr¦duct layer and the reaction zone are filar. Independent measurements of effective diffusivity supported the values obtained from the reduction data. ve 95% reduction the rate decreased markedly due to the formation_of retained wustite or fayalite. Comparison with reduction by carbon monoxide over the temperature range 7500 - 900¦C showed that the rate eduction by carbon monoxide was approximately five times slower than the rate by hydrogen. The rate of reduction was found to be a function of the properties of the pellets, which may account for the ely conflicting results that have been obtained in previous investigation on porous pellets.

Jan 1, 1970

The kinetics of desorption of nitrogen from molten iron were investigated using the electromagnetic levitation technique. The respective influences of gas flow rate and surface active element (S) were examined. A second order behaviour with respect to the nitrogen concentration in the melt prevailed at all experimental conditions. Sulphur had a marked inhibiting effect on the desorption rate. The experimental results on the rates of nitrogen desorption have been interpreted with the aid of a reaction mechanism consisting of a sequence of elementary steps.

Jan 1, 1991

By A J. Moore

The Australian Coal Association Research Program (ACARP) funded project, No C14057, entitled æEffect of Blasting on InfrastructureÆ, has been carried out with the objectives of providing methodologies for the assessment of the strength of infrastructure types and the establishment of responsible and realistic limits. Personnel from Melbourne, Newcastle and Swinburne Universities and Terrock Consulting Engineers conducted the project. Infrastructure types including: conveyors; power transmission towers; wooden power poles; electrical substations; pipelines, bridges; public access roads and underground workings have been investigated by both field studies and structural analysis. Railways, underground telecom cables, dams and industrial buildings have been reviewed using general structural analysis. This paper has been prepared for the mining industry to provide a progress report on the project.

Jan 1, 2007

By Fourney W. L, Dick R. D

Tests were conducted in plexiglass and Rockite models to determine if crater blasting could be improved by changes in charge geometry or by alterations to the borehole. Circumferential grooves were placed at various locations in the borehole in an attempt to control the initiation site of the crater. Grooves located at or above the top of the cylindrical charge had no effect on the resulting crater. Grooves placed too low in the borehole were successful in controlling the initiation site but the growth of the fracture system was not sufficient to reach the upper surface. Grooves located at a height of two thirds of the charge length were quite successful in that resulting craters were bigger by at least a factor of six than the normal crater. Testing was conducted in Rockite models to investigate charge geometry. Spherical charges in ungrooved boreholes resulted in crater sizes that were three times larger than those caused by cylindrical charges.

Jan 1, 1990

By Juniper LA

ERM Consultants Pty Ltd was established in 1980 for the purpose of introducing a disciplined coal technology and power station planning service, to support Australia's efforts in establishing a major export steaming coal industry. At that time, major coal exploration programs were mounted on more than 50 potential export coal deposits with proven open-cut reserves to export 200 Mt/a of coal. The fact that Australia achieved an export trade of only 30 Mt/a, equivalent to the energy requirements for a population of around 5 million people, illustrates the very small achievement to date. The main reasons for this small export steaming coal growth have been: 1. Failure to convince potential overseas coal buyers of the benefits of coal-fired power generation, and the ability of proper power station design to overcome environmental problems, and achieve reliable operation and long life when burning Australian coals. 2. Failure to promote Australian power engineers to advise on the use of Australian coals, resulting in Northern Hemisphere power station experience dominating in market countries. 3. Failure of governments to draw on privately practising Australian power engineers and coal technologists in technical workshops, presentations and assistance to overseas countries, to ensure that personnel whose business it was to serve the follow-on needs of countries were readily available. The result of these failures has been that: 1. Only a fraction of prospective overseas coal-fired power projects have proceeded. 2. Australia has had no influence in the design of overseas power stations to ensure that potential customers would be confident that Australian coals could be reliably burnt in their boilers.

Jan 1, 1987

At 11 p.m. on Tuesday, 24th July 1979, an explosion of methane gas in a three heading development panel at Appin Colliery resulted in the deaths of fourteen men. The explosion followed after or was asso- ciated with a changeover of the ventilation to achieve a central intake between two returns. Investigation by Inspectors was followed by separate Judicial and Coronial Inquiries. Investigational information aimed at understanding the circumstances of the ex- plosion was prepared for the Inquiries. Recommendations following the Judicial Inquiry have been adopted by the Department of Mineral Resources.

Jan 1, 1981

By C R. Sundberg

Despite nearly a half-century of continuous production, the low-grade iron ore (taconite) deposits of North America remain economically competitive sources of raw materials for the domestic steel industry. The continued viability of these mature integrated mining-concentrationagglomeration complexes requires highly efficient utilisation of assets, especially the mineral resource. At Cleveland-CliffsÆ five North American managed operations, enhanced ore characterisation techniques are playing a critical role in their continued success. Due to the low-grade nature and complex mineralogical composition of these deposits, ore characterisation cannot solely rely on assay grades. Historically, taconite ore characterisation has augmented assay grades with bench-scale concentration tests to quantify recoverable mineral. The economic necessity for improvements in mill efficiencies and final product quality has mandated significantly greater knowledge of ore-related impacts. Cliffs Technology Center has met this challenge by developing a variety of novel iron ore characterisation techniques. The applications developed include both in situ and laboratory procedures, plus unconventional data integration methods uniquely suited for these deposits. This paper details the evolution of these novel ore characterisation techniques and their application to each phase of the operation: mining-concentrating-and pelletising. The improved ore characterisation techniques have contributed to successes at individual Cleveland-Cliffs managed operations including mineral recoveries exceeding 95 per cent and productivity increases exceeding ten per cent while consistently achieving customer product quality objectives.

Jan 1, 2002

In the 100 years since the formation of The Australasian Institute of Mining and Metallurgy there have been significant changes in all aspects of the mining industry.A number of the changes have been driven by technical evolution or necessity, others have been driven by developments in the application of the products produced from the mining of minerals. Other changes have been driven by shifts in community values.

Jan 1, 1993