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Although the diesel engine is normally considered a tried and proven power source, many new and exciting diesel design concepts are being evaluated in engine development laboratories around the world. Three such programs currently underway at Cummins Engine Company are discussed. The turbocompound engine converts into power exhaust heat energy which is normally wasted. It does this by incorporating after the turbocharger a low pressure gas turbine which is gear driven to the crankshaft. The adiabatic engine has no conventional cooling system. It converts into useful power most of the heat energy normally rejected to the coolant. The series boost turbocharged engine uses seperate low and high pressure turbochargers to increase engine output and improve transient performance. These design concepts make possible increases in diesel engine thermal efficiency from the current 33 to 38 per cent range to the 50 percent range.

Jan 1, 1982

The central thickened discharge system of tailings disposal takes advantage of the natural beach slope formed by sub-aerially discharged tailings, and the non-segregating properties of thickened tailings, to create a homogeneous conical stack. The need for containing embankments can be largely avoided leading to capital and operating cost savings. Methods for estimating beach slopes and tailings density, essential parameters for the design of such a system, are described. Case histories from three mining operations are used to illustrate the application of the technique, There are also seen to be potential advantages in the areas of water management, seepage, and rehabilitation. Laboratory and in-situ testing enable parameters to be determined.

Jan 1, 1991

Any project carries a number of challenges and risks. Inappropriate design, poor project management, time, industrial disputation and capital over runs are all areas which can impact on a project cash flows and return on investment. In the resource Industry you have the added complexity and risk of geology which is difficult to predict and sometimes unforgiving. The Dartbrook Mine was designed and constructed as a high output longwall mine and has overcome a number of hurdles to produce over 2.3 million tonnes for the first year of operation. A number of problems were encountered during construction which resulted in the inseam development being delayed for six months. Dartbrook people have demonstrated they can manage adversity and produce world class results. The mine has been through a very steep learning curve during 1997 and with this experience behind the mine is now producing at an annualised rate of 3.4 MTPA.

Jan 1, 1998

Utah's Blackwater mine began operations in 1967. The four CQCA mines controlled by Utah followed over the period 1971 to 1979. Project feasibility studies for all these were based on open cut mining to overburden depths of 60 metres, with typical project lives of 12 to 16 years, depending on reserves Further studies, initiated after the mines had started, showed that continuation of open cut mining beyond the 60 metre highwall was viable. In 1973, the Deep Stripping Project (DSP) was launched to define the scope for stripping deeper, to determine what the additional equipment needs might be, and to pu forward proposals for a full scale trial system. The project commenced at grass roots with a literature survey, proceeded through a sequence of equipment evaluation, specification, design and manufacture to the commissioning of the Goonyella BWE system. Studies are continuing to assess the future deep stripping requirements for all Utah's Bowen Basin mines.

Jan 1, 1983

By P Krauss, S Harpalani

Methane emitted from underground coal mines, along with ventilation air and known as ventilation air methane (VAM), constitutes the largest component of coal mine methane (CMM) emissions. Atmospheric methane, on the other hand, is a potent greenhouse gas with a significant adverse impact on the atmosphere. This has led to the development of various technological alternatives for its use as an energy fuel. Techniques involving oxidation of VAM, usually consisting of very low concentrations of methane, have been validated in the past. Prominent among these technologies are the thermal and catalytic flow reversal reactors, ancillary fuel technologies, lean fuel gas turbines, and concentrators and gasifiers. However, the efficiency of any VAM utilisation technique depends on the amount and concentration of methane in the ventilation exhaust air. Therefore, quantification of VAM emission from a coal mine is the first step towards identifying the most suitable technology for its utilisation for energy production. This paper presents an evaluation of the efficacy of VAM as an energy source. It provides details of a case study aimed at developing a technique to accurately quantify VAM emission from a coal mine. It further discusses the various VAM utilisation techniques available, and presents an economic evaluation of the alternatives. Based on the findings of the study, the most feasible method for VAM utilisation is identified for the mine. The paper summarises the procedure for quantifying VAM emissions and selecting the most suitable utilisation technique.

Jan 1, 2005

By R Turner, P Hatherly, T Medhurst

Borehole geophysical logging data are routinely acquired during exploration of coal deposits in Australia. These data are commonly used qualitatively to identify and correlate coal seams and geotechnically significant interburden rock units. Some quantitative analysis, such as using sonic logs for rock strength estimation is becoming increasingly widespread. This paper discusses results from a project aimed at expanding the quantitative approach to more detailed mineralogical and lithological analysis, which leads to improved geotechnical characterisation for mine planning and mining hazard reduction. A standard suite of wireline logs measuring density, natural gamma, sonic and neutron were analysed from three coal mines in the Bowen Basin. Thirty-nine samples from cored sections of the boreholes were analysed by X-ray diffraction, spectral gamma counts and hyperspectral scanning. Using a standard petrophysical approach to calculating porosity, shale and matrix components from a combination of density, natural gamma and neutron logs, a good correlation with observed mineralogy was demonstrated. However, unusual mineralogies such as heavy minerals or low-potassium clays may distort this analysis. Simultaneous evaluation of all available geophysical logs by modern data mining methods was able to show how these ambiguities may be solved.

Jan 1, 2006

By Mirabediny H, Whitchurch K

A computerised simulation model has been developed to select the most suitable digging method of a dragline operation for a given geological condition. The developed procedure uses a geological ore body model as the basis for the geologic database. The simulation selects the most cost effective dragline digging method from a database of various dragline digging methods The database consists of common and innovative dragline methods currently used in Australian open cut mines. A generalised computer package, DSLX, was extensively used to simulate various dragline digging methods. The DSLX software uses predefined functions to build strip geometry, working benches, blast profiles and spoil piles. The outputs from DSLX in form of volumetric, swing angles and hoist distances data are then aggregated with dragline specifications and site time study data to compare productivity of selected digging methods. The result of a case study showed that this procedure lends itself to the 'optimum' selection a dragline digging method for a given coal deposit.

Jan 1, 1995

By C Aldrich

In this paper, the use of topology preserving projections (Sammon maps) and neural networks are considered as a basis for the construction of multivariate statistical process control charts for a semi-autogenous grinding circuit on a gold plant. Comminution circuits are often operated in a quasi-steady state mode, where the mills tend to move rapidly from one state to another. This makes them difficult to monitor by conventional means designed for continuous steady state processes. As a first step, process data reflecting normal operating conditions are mapped with SammonÆs algorithm. Only one feature is extracted at a time and each mapping is captured by a neural network model to allow online application. Reverse neural network models are used to reconstruct the data prior to the extraction of subsequent features from the data residuals. The ensemble of neural network models can then be used for both fault detection and identification. The approach compared favourable with both linear and non-linear principal component models. It was able to detect two simulated fault conditions both with a reliability of 100 per cent, as opposed to 57.8 per cent and 95.2 per cent detected by an approach based on the use of linear principal component analysis and 84.1 per cent and 98.0 per cent detected by an approach based on non-linear principal components extracted with auto-associative neural networks.

Jan 1, 2007

Among the various methods of thick-seam mining already well-tried in practice longwall caving with extraction of a single slice, as thick as possible, abandoning the top and/or the bottom coal, seems to be the most suitable one for the Australian coal mining industry. The production units of the future should be equipped with heavy double-drum shearer-loaders, wide armoured conveyors, (with one or two central chains) and shield support. Material of this type has been developed for seams up to 6 m thick. Output figures of more than 6,000 tROM/d from a single face can be looked upon as a quite realistic expectation. The problems of co-ordinating such large production units with the whole layout of the mine are discussed. The factors to be taken into account in the planning work and for preven- tion of mine fires caused by spon- taneous combustion are dealt with. For economic reasons the highest possible utilization factor of the very expensive equipment must be aimed at. Furthermore, the seams or parts of seams to be extracted should be carefully selected.

Jan 1, 1976

By Thatcher R

In areas where land suitable for development is a scarce resource, an upgraded post-mining land use can result in economic benefits to both the mining company and to the community.A study undertaken at Aberdare Colliery near Ipswich during 198611987 assessed the costs and benefits of developing the site following mining for grazing, forestry and residential uses. The proposed fmal land use plan comprised a combination of these uses that can be upgraded to higher valued uses once subsidence monitoring of backfilled open-cut areas and dumps indicates that total settlement has reached acceptable levels for development to proceed.The study involved the documentation of existing site environmental parameters and the delineation of site opportunities and constraints. The unpredictable nature of settlement over backfilled open-cuts and overburden dumps represents the major constraint to urban development on mined areas.

Jan 1, 1990

By Yusuf R

Many heap and dump leaching processes involve competitive, complementary and sequential reactions between multiple minerals and reagents. A comprehensive model has been developed to deal with these complex chemical interactions which is based on diffusion control of the reaction rates. All of the mineralogical and chemical data are obtained from representative samples of the ore or the chemical literature. These properties have been incorporated in a general way, making the model applicable to a range of ore-process systems. The simulation is used to predict the absolute reaction rates and can be used before any leach tests are carried out on the ore itself. The applicability of the model and some tests of its validity are presented.

Jan 1, 1984

A model of dense medium cyclones is developed based on balancing the terminal velocities of the discrete particles due to the centrifugal force against a random turbulent eddy velocity. An expression of the form P - or Q _ 1 100 e."A where P is the partition number., is a function of cyclone efficiency, particle size and density differential between the particle and medium, and is the slurry spilt, is developed and may be used for regressing plant partition data. The above model provides an understanding of peculiarities of the partition curve such as asymmetrical tails, elevation of the cutpoint and elevation of the d50 with increasingly fine feed. The effect of feed variables such as particle size, medium viscosity and changes in spigot or vortex finder diameter is shown. A means of convoluting the partition curve with various feed washabilities is discussed together with how the above may be used to evaluate plant performance for a variety of feeds.

Jan 1, 1987

By A G. L Pratt, G F. Dunstan, A Leonforte

The selection of the material sizing and mine dewatering systems are important elements in the development of a large-scale, high tonnage (greater than 4 Mt/a) underground hard rock mine. The sizing system will influence the size and type of the ore haulage system and therefore how the underground project is developed. With more underground developments considering or implementing caving methods of mining, the selection of the material sizing systems is also influenced by the caving fragmentation. Traditionally, crusher systems are used for material sizing in large hard rock mines, with the crusher installation and its ancillary equipment representing a substantial capital investment. Underground cave mining type operations generally express themselves with large surface subsidence areas, which can lead to large inflows of water from major rain events or purging underground aquifer systems. To minimise disruption to mine production, the dewatering system needs to be sized, with consideration to both storage and pumping capacities. The balance between storage and pumping capacity is assessed to provide the optimal economic solution with the appropriate risk measures. This paper outlines a process for the selection of material sizing and dewatering systems for large-scale caving operations. This process is illustrated with information drawn from NewcrestÆs Ridgeway Deeps Block Cave project. The Ridgeway Deeps Block Cave is located directly beneath the existing Ridgeway Sublevel Cave Mine.

Jan 1, 2008

Poor ground conditions associated with historical workings have presented significant challenges to the drilling of production downholes at the Sons of Gwalia Mine. The combination of foam and polymer drilling, the use of Aquacrete to drill through voids and the practice of lining completed holes has allowed downholes to be effectively drilled and blasted in delaminated ground.

Jan 1, 2002

FaulIing west of the Mount Isa mine is described and is shown to be related to three groups of folds that have been recognized in the area. The first period of faulting postdates the first generation folding; these faulIs are regional faults (tectonic discontinuities) which are folded by second generation folds. The faulting accompanying the second generation folding divides the area west of the Mount Isa mine into four structurally and metamorphically identifiable blocks. The most prominent of these second generation faults is the Mount Isa Fault, which is characterized by a number of distinct zones of intense second generation folding and the presence of localized layers of mylonite. Only limited evidence for brittle deformation has been observed and the major movement appears to be associated with the plastic deformation of the rocks. Confined to the areas of second generation folding in the Mount Isa Fault are numerous third generation kink folds. A detailed description of the Mount Isa and other faulIs is presented together with evidence for their existence. The displacement accompanying this faulting cannot be established because of the complexity of the structure.Postdating these faults and all the folding of the area are minor cross faults.

Jan 1, 1973

Silver-lead mineralization at Indooroopilly, Queensland, extends upwards from Upper Triassic rhyolite which intrudes phyllite-containing Palaeozoic mineralization.Sulphides and magma were emplaced in a special structural site which underwent dilational fracturing while surrounding rocks were block-faulted and compressed. This site lies at tbe intersection of dykes, faults, and a lineament adjacent to a Middle Triassic granitic stock.Structural controls at Indooroopilly are attributed to the effects of piston faulting. Exploration for similarly controlled deposits should be directed towards structural intersections near stocks or batholiths which have intruded mineralized belts. Priority should be given to structural intersections which were sites of block-faulting and igneous activity under compressional tectonic conditions.Favourable sites lacking surface mineralization may contain ore at depth as piston faulting produces 'blind' ore deposits.

Jan 1, 1976

Powercoal Pty Ltd operates eight underground coal mines in New South Wales and produces coal for both domestic power stations and the export market. Approximately 40% of total production is from continuous miners. Over the past five years, place change mining methods have been introduced to improve productivity from continuous miners. This has involved utilising the existing coal clearance system from the continuous miner to the ratio feeder using trailing cable shuttle cars.By late 1996 average productivity at Cooranbong Colliery using this system had plateaued at 800 tonnes per eight hour shift. A number of factors were identified to increase average productivity to 1500 tonnes per eight hour shift. An improved coal clearance system was one of the factors identified.

Jan 1, 1998

By Olofsson O, Durance M-V, Villeneuve J

Modelling of the Sala Agitated Mill (SAM) using a simplified solution to the population balance approach has been carried out. The rate of breakage is modified by the mill power, providing predictions of the resulting product size distribution for different grinding conditions and mill sizes. The power of the mill is estimated by a physically derived function, using an assumption that the mill power consumption mainly arises from the ball to ball friction within the mill. The grinding efficiency, depending on the media ball size and pulp density is approximated in the model. Experimental work on grinding a complex sulphide ore using a pilot scale SAM 7.5 has been carried out. Good agreement has been found between the data from the test campaign and the simulated values. The model has also been validated with experimental data from a pilot grinding of calcium carbonate and from an industrial mill. The model is included in the USIM PAC simulation software.

Jan 1, 1995

Gold occurs at Mt. Charlotte associated with a stockwork of pyritised quartz veins in Unit 8 of the Golden Mile Dolerite. The ore- body is massive, 200m long and 40m wide and has been proved to over 600m below surface. Mining is by sublevel ring drill stoping with the ore recovered by diesel powered equipment. Ore reserves are based on traverses of diamond drill holes oriented to produce an equal intersection width on the two principal sets of quartz veins. Assay and geological boundaries are marked on each drill section and this boundary is transferred to mine plans and cross sections. Ring-drilling patterns are based on the cross sections and the resulting mining outline is transferred back to the drilling sections. The mine ore reserve is calculated from the mining outline.

Jan 1, 1979

By P D. Franzmann, D J. Readett, J Peterse

A better connection between laboratory- and pilot-scale test results, and heap bioleaching performance can be achieved by generating reliable information on the fundamental microbial, chemical and physical processes that occur in heaps and incorporating this information into a comprehensive and robust model. More efficient heap bioleaching, particularly of chalcopyrite, has the potential to add value to the mining industry as well as deliver attractive environmental and social benefits to the communities within which those companies operate.The results of fundamental chemical and microbiological studies of the leaching mechanism, the temperature dependence of chalcopyrite bioleaching, and the optimisation of leaching conditions are described with examples from full-scale heaps. The development and application of a number of novel techniques and tools has assisted our understanding of heap subprocesses mineralogy, hydrology, chemistry and microbiology. The heap bioleaching model HeapSim, which embodies a large number of effects not previously accounted for in other models, continues to be refined and has been applied successfully to the study of several heap bioleach systems.

Jan 1, 2004