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By Giuli M, Barnaba P, Sacerdote R, Tammaro F

Following a theoretical consideration of the effect of flooding, fluidisation and softening on blast furnace blowing limits, results are presented which show the effect of these parameters on operation. Industrial trials on Oscar Sinigaglia No. 4 BF are reported and results compared with those obtained theoretically and in the laboratory. It is shown that in these trials the furnace operated at levels of fluidisation very much (80-90%) below those theoretically calculated whereas in some cases (high proportion of sinter) actual hot metal output was near the calculated flooding limit. However, it was observed that as the sinter percentage decreases also actual productivity becomes lower than the one caused by flooding. This gap, which increases as other ferrous components (essentially acidic) replace the basic sinter was explained by the softening of the burden under bosh conditions. Softening indices measured on the individual materials yield support to this explanation. Coke rates data show that for approximately every one percent increase in the basic sinter in place of blended sized ore, a coke rate decrease of 1.1 kg/thm results. For acidic pellets this value is 0.6 kg/thm. Results of breakdown and reduction characteristics are also given and their indices compared with actual pt oduction. Measures to improve operations are proposed.

Jan 1, 1975

Alcoa of Australia's Western Australian bauxite mining operations in the Darling Ranges, southeast of Perth, present major challenges in the control of air blast. The close proximity of rural communities and the face profile make the traditional methods of air blast control difficult.An extensive blast noise monitoring programme has been established. The development of a computerised blast noise prediction model and the establishment of a radiosonde weather balloon facility have reduced blast induced complaints by a factor of ten.The meteorological factors affecting blast noise transmission are discussed and examples are given of adverse weather conditions for the southwest region of Western Australia.

Jan 1, 1983

By Quinlan M. J, Ratcliffe J. S

Chemical kinetics is a dependent process which usually correlates the rate at which a reaction proceeds with the mechanism descriptive of the manner by which reactive particles interact. Given the latter, the object gen- erally is to find the reaction rate dependency in terms of an intensive property of the system - number of reactive particles present, and of the energetics of the system - usually temperature. Chemical kinetics depend on a dem- onstration that reaction considerations alone control the phenomenological process under study. For these rea- sons, chemical kinetics are usually involved in homogeneous gaseous systems. Even in liquid homogeneous sys- tems earliness or lateness of reactant mixing rather than chemical kinetics may be controlling. Considerations of transport phenomena are involved in heterogeneous systems and often control the observable rate:an additional problem in such systems is to apportion the rate due to mass transfer - usually a linear process - and that due to reaction which may be linear or non-linear. Experimentally, conditions are often chosen so that only one consideration controls but this becomes more difficult where solid phases are involved. Kinetic modelling involves considerations of chemical kinetics, transport phenomena, and factors attributable to the physical environment in which the process takes place. The latter two considerations may be quite different as between experiment and plant. The kinetic model may be a mathematical representation of a conceptual mech- anistic model of the reaction. Alternatively, it may be an empirical relationship resulting from, for example, some curve fitting procedure applied to experimental data. The latter approach may be necessary where the system is particularly complicated.

Jan 1, 1975

By Will D

This presentation is to outline the current practice of mechanised stoping a one-metre wide, gold bearing ore body to optimise fragmentation, minimise dilution and reduce stoping costs.Coolgardie underground operations have historically been mined using traditional shrink stope methods, but in this recent economic environment (with falling gold prices and high costs of traditional methods) it was necessary to look for alternative methods in order to reduce costs and increase productivity.Although still in a learning and refinement phase, CGNL is satisfied that it is feasible, practical and more economic to use mechanised long up-hole stope and long-hole rising methods to significantly reduce the mining cost, reduce dilution, increase safety and increase productivity three-fold compared to traditional airleg methods used throughout the Fasten Goldfields.

Jan 1, 1993

The capacity of chlorine based solutions to rapidly and effectively dissolve coarse gold in oxide ores is well established. The inherent advantages of chlorine are high dissolution rates (10 - 100 times those of cyanide), and low cost. The high dissolution rates mean that coarse or poorly liberated gold may be dissolved over relatively short periods and hence ore particle size may cease to be such a critical factor. The cost of size reduction to allow adequate gold liberation in order to achieve an adequate gold recovery is less of a consideration when using chlorine than in traditional plant or heap leaching cyanide-based treatment systems.Because chlorine based solutions capable of dissolving gold evolve an unpleasant vapour phase with the potential for significant chlorine losses into the atmosphere, traditional heap leaching with active solutions being sprayed onto prepared heaps is not possible. The ore must be covered and the solution may be introduced beneath that cover through prepared injection `wells' and recovered through production 'wells'. The pit is flooded with active solution beneath an overburden or cover with the solution migrating from the injection 'wells' to the production 'wells' over a period of around five - ten days.

Jan 1, 1992

By Bowling K. McG, Hamilton J. D G

The influence of three important para- meters which affect the induration of iron-ore pellets, viz temperature, time, and lime content, have been assessed in terms of internal pellet structure and commonly-used pellet quality criteria. The pellets studied were produced from a typical hematite ore from the Pilbara area of Western Australia, using a 25 cm dia. pot-grate test rig. Isothermal laboratory induration tests were conducted in accordance with a statistically-planned programme. The internal structures were studied by optical microscopic examination of polished sections of the test pellets. The effects of SFCA (silico- ferrite of calcium and aluminium) and slag formation, matrix consolidation and grain modi- fications were studied, and have been related to pellet properties and to the time/temperature histories produced by the firing conditions chosen. The implications of the data for commercial pellet plant operations are discussed.

Jan 1, 1974

By Costello MC

An alternative process for desorbing and recovering metals from activated carbon has been developed, and is the subject of several patent applications by Micron Research (W.A.) The system uses the principle of conditioning the carbon in a strong alkaline cyanide solution followed by distillation desorption in a fractionating column, using the carbon as the column packing and methanol as the desorbing agent. The system offers the following advantages : (a) The processes of desorption, methanol recovery and reactivation are all carried out in a single column with the carbon itself acting as the column packing. No other desorption plant items or fractional distillation equipment are required. (b) The metal values are concentrated into the water content of the carbon and no other water is used except as condenser coolant. This produces very high grade gold silver solutions which give high current efficiencies in the electrowinning step. These high gold concentrations allow almost complete separation of gold and silver from copper in the electrolytic cell. (c) The process is completed to a tailing assay of less than 200g Au/tonne carbon in 15 - 20 hours allowing turn around of carbon batches on a daily Basis.

Jan 1, 1982

By Rosmus P

Improper use of auxiliary ven- tilation units during heading operations may often result in the appearance of hazardous methane accumulations. This is the case especially when roadways are ventilated by a combined system with a short sucking pipe at face end performing as the dedusting installation. Uniform air inflow to the face end facilitates sucking off the dust clouds and creates conditions favourable for formation of local methane accumulations. The highest methane concentration occurs in the cutting zone between the rock cut and the pipe inlet, under the roof and by, the sidewalls. Permanent monitoring of methane concentration at face end employs methane sensors. The most important are: one on the road- header's boom behind the cutting head, and one at the air outlet from the dedusting installation.

Jan 1, 1988

By Wilkinson LR

The object of this paper is to present a brief overview of applications of radioisotopes in mineral processing. The emphasis is towards on-line applications, and is to present the broad picture rather than become involved in the details of particular applications. For a more detailed and comprehensive coverage, the reader is referred to the International Atomic Energy Agency International Symposium on Nuclear Techniques in Exploration, Extraction and Pro- cessing of Mineral Resources, held in Vienna 7-11 March, 1977. Because of space limitations here, we have inmost cases restricted coverage to those applications of radioisotopes within the direct experience of Amdel and Australian research bodies. Radioisotopes spontaneously emit energy in tiie Form of a and S particles, and electromag- netic radiation. The electromagnetic radiation is generally referred to as y-radiation when it originates from the nucleus, and X-radiation when originating from the electrons orbiting the nucleus. X-ray and y-ray energies overlap, with X-rays extending from a few electron volts (%') up to about 100 keV. Gamma rays in the useful energy range extend from a few keV up to .feV.

Jan 1, 1978

By Seymour C. A

Peak Downs Mine, a five million tonnes a year coking coal operation, strip mines a, series of Permian coal seams. Seam thickness ranges from 0.5m to 5.0m, and seams consist of multiple coal plies with intermediate shale and mudstone partings. Four 47m3 draglines strip overburden to a cover depth of up to 60m. Coal loading is by 12m3 shovels and 14m3 to 18m3 front-end loaders. Parting removal takes place where the layer of shale and mudstone between seams exceeds 0.3m in thickness. Parting has been removed by a wide variety of earthmoving equipment in order to evaluate the problem and to select the optimum method from an operational and economic standpoint. Multi-seam stripping of the thicker seams is accomplished by working draglines from spoil- pile benches. Coal seams thinner than lm are recovered by dragline and stacked in the pit for later loading.

Jan 1, 1974

By S S. Kanchibotla, D La Rosa, R W. Pesch

The Porgera Joint Venture and Dyno Nobel have commissioned a joint project to optimise the drill and blast operations to increase the overall profitability of the mine. One of the aims of this project is to increase the throughput of semi autogenous (SAG) mills by optimising the blast fragmentation. A number of test blasts were conducted during the period May 2000 to January 2002 and the ore from these blasts was campaigned through the mill. The data from these trials suggested up to 15 per cent increase in the SAG mill throughput with high energy blast designs. However, changes in ore geology (shape, structure and hardness) and potential ore dilution/loss and wall damage have raised concerns about the economic benefits of these designs over the entire orebody. The lack of a system to track the economic benefits of these modified designs has also compounded these concerns. PJV and DynoConsult, the consulting arm of Dyno Nobel have initiated steps to minimise the potential for ore dilution and wall damage resulting from these modified designs. DynoConsult worked with Julius Kruttschnitt Mineral Research Centre (JKMRC) to develop and implement a blast management system to track the quality of blast implementation and down stream process benefits. This paper discusses the implementation of the system and the results achieved to date.

Jan 1, 2003

The Fosterville goldfield, situated 25 km east of Bendigo, Victoria was at its peak between 1894-1910 with some 47 600 ounces produced (Figure 1). Since that time intermittent mining and tailings retreatment was undertaken until Bendigo Gold Associates delineated a viable resource and commenced an open cut heap leaching operation in early 1991. Unfortunately they encountered financial difficulties and Perseverance Exploration purchased the mine in April 1992. Perseverance operated a successful heap leach operation nearby Nagambie, 100 km east of Fosterville. Based on its acquired heap leaching experience, Perseverance Exploration was able to instigate operational changes to create a successful small gold heap leach operation. The major change was the using of the original multi-use leach pad as a single-use leach pad. The available data allows for a comparison of the two operating systems.

Jan 1, 1994

Design of cemented fill in mining is often carried out without any consideration of the structure of the fill. The composition of cemented fills varies in the stopes due to the placement method, and the strength of the fill in the laboratory depends on the density, orient- ation, moisture content and drainage conditions. Within each stope there are definite zones and the structure of both cemented rockfill and cemented hydraulic fill has to be defined for each zone and the field conditions simulated in the laboratory. Structure also affects fill permeability and compressibility. From a study of the cemented fill in place, the effect of changes in the placement methods can be seen and then controlled to improve fill performance and economy. These features of cemented hydraulic fill and cemented rockfill behaviour are discus- sed and illustrated through reference to field and laboratory work undertaken at Mount Isa.

Jan 1, 1973

This paper discusses the use of tapered roller bearings in conveyor idlers. It shows that in medium and high capacity systems, tapered roller bearings can offer significant cost and performance advantages. In the next ten years, conventional conveyors will face increased competition from unconventional belt conveyors, pneumatic systems, pipeline "slurry" systems, unit trains and so on. The conveyor industry must meet these challenges by innova- tive use of technology. Conventional belt conveyors must continue to show the lowest cost per tonne-km or lose their position in the market. Tapered roller bearings can contribute to the achievement of this goal. The concurrent resources boom and liquid fuel crises may well see a decline in the use of heavy trucks for bulk material handling over moderate distances 10 to 50 km. There appears to be a trend in the conveyor industry to go to higher speeds with improved belting in conven- tional widths. The transmission of more material over a given period of time will place more demands on conveyor idler bearings. Australia has in general followed the European practice of using deep groove ball bearings in conveyor idlers.

Jan 1, 1978

By Yates M. G, Rowlands A. T

Most geostatistical techniques applied to the estimation of ore reserves assume relatively unifonn grade and thickness within an ore deposit environment. In shear-hosted mineralisation this rarely occurs. The distribution of mineralisation is controlled by the kinematic and geometric variation within the shear zone. Although the kinematic variation is dependent primarily on the temperature (and consequently the depth) of formation of the deposit, the geometric variation appears to be relatively insensitive to this parameter. Shoot mineralisation is controlled either by the intersection of secoodary shear planes (brittle deformation) or the stretching lineation of the mylonitic fabric (ductile defonnation).Once the shear geometry is clearly identified, it is critical to review the distribution of grade and thickness of mineralisation. The practice of cutting high-grade intersections without reference to the shear model leads to underestimation of the amount of gold in the deposit. High-grade shoots may occur as pipe-shaped bodies within the system; their identification is essential for both resource estimation and mine planning purposes.

Jan 1, 1991

By D Mukendi-Ngalula, G Hearn

Beach sand minerals from the volcanic rock structures of the Drakensberg, Kwazulu-Natal, (South Africa) have been processed. Screening, flotation, spiral concentration and magnetic separation methods were used either separately or successively in an attempt to concentrate monazite minerals. Products thereof and those from a long time (up to 72 hours) microwaves treatment of the finally produced ilmenite-bearing minerals have been studied using the M÷ssbauer effect spectroscopy. The 57Fe M÷ssbauer effect spectroscopy has demonstrated its versatility and power in monitoring the ilmenite internal reduction mechanism and products and, in characterising the iron-bearing phases contained in different products from the beach sand minerals processing. Microwaves heating of ilmenite for up to 38 hours reduced internally the Fe3+ from the ilmeniteÆs structure. A more prolonged microwaves heating (up to 72 hours) re-oxidised the mineral. 61 per cent natural ilmenite recovery was obtained in the floating products of a spiral concentrated -212+106 ¦m screened and beach sand minerals fraction. A preferential concentration of hematite with a 62 per cent recovery was found in the sinking products while the combination of screening-spiral separation-magnetic separation and flotation yielded a floating product with the highest ilmenite and the highest hematite abundanceÆs (71 per cent, 19 per cent respectively). A natural ilmenite containing 87 per cent ilmenite and 13 per cent hematite could be produced and extracted from the sinking products of the flotation process collected subsequently to the spiral concentration and the initial screening.

Jan 1, 2000

Basic Oxygen Steelmaking (B.O.S.) commenced in Australia in December, 1962. Two 200-ton furnaces were installed initially at Newcastle with a 50-ton furnace coupled to a continuous casting machine added in 1967. In 1965, two 100-ton furnaces were installed at Whyalla plant and two 225-ton furnaces are nearing com- pletion at Port Kembla to commence oper- ations in 1972. Plant layouts in each centre differ due to changing circumstance and increasing knowledge of the B.O.S. process since 1962. Raw materials are a most important factor for good operation of the process. Most materials come from within Australia but some are imported. General operating practices are similar in each plant, although treatment of fume at Port Kembla will be by the OG (Oxygen Converter Gas Recovery) Process as against electrostatic precipitators in Newcastle and Whyalla. Special alloy steels as well as plain carbon steels can be made by the B.O.S. process. Production potential of the process in Australia has yet to be fully utilised with 45 per cent of steel production coming from B.O.S. In 1971.

Jan 1, 1972

Problems associated with gas management become more significant as exploitation of coal reserves in the Bowen Basin in Australia becomes deeper. At Oaky North mine, relocation of production from one area of the mine to another with a higher gas content required the use of pre-drainage, post drainage and inertisation techniques to enable production activities to continue largely uninterrupted. Innovative surface to inseam drilling techniques were developed for pre-drainage of reserves close to mine workings and have proven to be largely successful. The gas management techniques adopted and specific experience gained are discussed in this paper.

Jan 1, 2005

By A E. Annels, M D. Raine, I M. Platten

Lode-gold systems are often characterised by a high to extreme nugget effect (>50 per cent), and the presence of coarse gold particles (>100 ¦m in size). They rank amongst the most difficult of ore deposits types, in terms of producing an accurate and precise resource estimate. Their effective sampling is generally difficult because of the relatively low concentrations involved and erratic nature of the gold particles. Grade continuity is usually less consistent than gross geological continuity, and is typified by the localisation of grades within discrete oreshoots. In most cases drilling, particularly diamond drilling is an effective measure of global geological continuity, whereas grade can only be reliably resolved from underground development. Depending upon drill density and geology, it is unlikely that anything above an Inferred Mineral Resource can be estimated from surface drilling alone. Underground development, in-fill drilling and, potentially, bulk sampling or trial mining will be required to delineate Indicated and Measured Mineral Resources and subsequent Ore Reserves. Grade estimation will have to account for highly skewed and often multi-modal populations, extreme values, a high nugget effect and low geostatistical ranges. A clear geological model that honours both geological and grade continuity must drive the resource estimation process.

Jan 1, 2003

By Stewart WJ

Australia's first offshsore well was spudded in on 27th December 1964 and resulted in the discovery of the Barracouta gas field. Further exploratory drilling led to the discovery of the Marlin gas field in December 1965, the Kingfish oil field in April 1967 and the Hblibut oil field in June. 1967. In September 1968, a small oil reservoir was found in a sand below the main Barracouta'gas reservoir. The Snapper gas field was discovered in May, 1968 Information on exploration activities associated with the discovery of oil and gas in the Bass Strait area may be found in the paper, "Exploration in the Gippsland, Bass and Otway Basins, Australia" by B. M. Hopkins. _ Development of the commercial fields is being undertaken on an equal participation basis by Hematite Petroleum Pty. Ltd. and Esso Exploration and Production Australia Inc. Esso Standard Oil (Australia) Ltd. is responsible for the design, construction and operation of the production facilities.

Jan 1, 1970