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The Ngakuru zeolites are located about 20 km south of Rotorua and comprise a number of deposits dispersed along several fault lines. Relatively recent volcanic activity (250,000 years ago) resulted in ash depositions that vary in depth and mineralogy. Subsequent variable thermal alteration intensities generated predominantly clinoptilolite and mordenite zeolites with a range of physical characteristics. Typically the zeolites have low density (650 kg/m3), have high liquid (60% of dry weight) and odour absorption characteristics, and a high affinity for soluble cations (CEC =: 100 meq/100 g). Traditional kitty litter and oil absorbency markets are being expanded. New opportunities in waste and potable water treatment, organic and synthetic slow release fertilisers, use as a light weight aggregate for speciality concretes, and pozzalome activity are currently being researched.

Jan 1, 2000

By D M. Weedon

This paper introduces a novel roll crusher design, which incorporates non-cylindrical crushing rolls. The use of non-cylindrical rolls enables the crusher to achieve a greater reduction ratio than is possible with conventional roll crushers. Referred to as the NCRC (non-cylindrical roll crusher), the new crusher incorporates two rolls comprised of an alternating arrangement of plane and convex or concave surfaces. The two rolls are complementary and arranged so that when they rotate the convex and concave surfaces of each roll are substantially opposed. With the rolls rotating in opposite directions at the same speed, this arrangement produces a gap between the rolls that remains approximately constant. Discontinuities on the roll surfaces provide improved angles of nip, which increase the probability of larger particles being drawn into the crusher. Initial tests on a scale prototype of the NCRC have indicated that reduction ratios exceeding 10:1 are achievable.

Jan 1, 2000

By P Bartlett, K Naidoo

Premier Diamond Mine is planning a new, mechanised, block cave, with a production level approximately 1000 m below surface. A high degree of tunnel damage is expected, due to stress and the relatively low in situ strength of kimberlite. An evaluation of the timing of tunnel excavation, tunnel size and spacing has been carried out to define critical parameters for planning layouts and development schedules. Extensive use has been made of three-dimensional FLAC3D numerical models, calibrated against known rock mass behaviour at 650 m depth, to examine the influence of undercut advance on production level excavations. These were able to represent the effect of stress rotation on tunnels during undercut advance and the effect of an inclined undercut. The analysis has provided guidelines that are possibly applicable to any deep block cave layout. The choice of drawpoint layout is of considerably less significance than the proportion of ground extracted on the production level elevation prior to advancing the undercut. The analysis shows that damage to production development will be potentially severe if it is all excavated prior to advancing the undercut, or is mined directly beneath the undercut face. The development of the main production tunnels alone ahead of the undercut may be feasible, but no breakaways should be put in as they appear to trigger a rapid increase in the severity of damage. The optimal sequence is when all production tunnels are developed at least 10 m in plan behind the undercut, where the induced peak field stress is less than 20 MPa and a maximum support pressure of 100 to 500 kN/m2 is require to contain movement. The assessment showed that the conditions are not significantly improved by increasing drawpoint spacing from 15 m to 18 m. The vertical spacing between the undercut and production level beneath is investigated. Provided production level development is carried out beneath the undercut, there would appear to be little benefit in increasing the vertical spacing between the undercut and production level beyond the current 15 m to 18 m.

Jan 1, 2000

By M Mee, R L. Gwyther

Accurate measurement of rock mass response during the mining of massive underground orebodies is essential, as mines become larger and deeper. These measurements enable: provision of quantitative data for optimal pit slope design and engineering; monitoring of the stability of deep pit slopes, the long-term integrity of shafts and large-scale underground infrastructure, and long-term measurements of deformation or rock mass creep following the mining process for environmental management. Strainmeters traditionally used for deformation measurement have neither the long-term stability nor the high sensitivity to perform measurements in these applications. This paper describes a new precision borehole strain monitoring system (GTS) currently deployed by CSIRO Exploration and Mining, which has the potential to solve these new issues in rock mass deformation monitoring. This technology was originally developed for use in hard rock mines (Gladwin, 1977) and refined considerably for earthquake research (Gladwin et al, 1994; Gwyther et al, 1992). A case study of the use of the GTS in monitoring longwall coal mining over the period 1993 - 1998 is presented.

Jan 1, 2000

By T Blyth, D Holden, N Archibald, S Huffadi

The Morning Star mine is owned by Hill 50 Gold NL. Gold is hosted in quartz-carbonate ¦stibnite ¦molybdenite veins that occur in a series of deformed, altered and metamorphosed mafic volcanics with subordinate sediments and felsic intrusive rocks. The irregular gold distribution and its relationship to structure and alteration intensity makes the definition of stoping limits difficult. Understanding the structural evolution of the orebodies and the contemporaneous and later structures that affect the orebodies has been very useful in this context. This paper reports on a detailed mapping exercise (as part of a more extensive and on-going investigation) and the integration of this mapping with other geological and grade control data in a 3D modelling environment to provide an expanded basis for stope design. Three types of mineralised zones can be discriminated based on the morphology of the veins within. They are:those associated with strongly folded, thick veins (approximately 1 m thick eg 05 orebody); those comprising planar, boudinaged and some folded veins which consolidate to form tabular, steeply dipping bodies (eg 010 orebody); and zones containing the above vein types and thin, highly deformed veins within zones of intensely foliated country rock that result in localised, irregularly distributed high-grade gold zones (eg 02 orebody). The mineralised zones associated with thick folded veins are typically predictable over many tens of vertical metres. The second and third types of ore zone is generally less predictable. Detailed mapping and structural kinematic studies indicate all ore zone types are affected by progressive deformation involving strong strain partitioning. It is interpreted that high strain zones, recognisable by intense foliation development and highly deformed veins, are the latest stage of a progressive deformation which approximates bulk flattening. Structural controls on mineralisation can be defined at two different scales.Regional scale folding has deformed a sequence of mafic volcanics with interlayered sediments and felsic intrusives. Initial geometry of felsic bodies relative to orientation of the primary lithological layering and the bulk shortening direction is interpreted to be critical for initiation and development of strongly dilatant zones within this package of rocks, and Local scale dilation is evidenced by development of several vein sets whose range in orientations and opposed vergence relationships suggest a pre-folding origin comprising both extensional and hybrid shear-extensional types. Continued deformation resulted in folding of these veins with strong strain partitioning. Major vein packages are closely spatially associated with the felsic/mafic contact and an interpreted early structure which appears to have partitioned early dilation. This structure is now obscured by strong deformation but is currently represented by a zone of planar veins.

Jan 1, 2000

Determining the controls of high-grade mineralisation at Vera Nancy requires careful data collection and assessment on a global and specific deposit basis. The techniques developed over 60 years ago to analyse structure, grade and width data are just as applicable today and can be enhanced using modern geological modelling software. High ore grades at Vera Nancy are controlled by both the primary geometry of the mineralised structure and the intersections of the main mineralised veins with subordinate splay veins. The main mineralised structure dilated as a consequence of extensional tectonics while the splays acted as conduits bringing oxidising surficial fluids into mixing zones precipitating high gold grades. Near-mine exploration is focussed on identifying zones of vein flexure and splay interaction to locate the relatively small high-grade shoots. Data modelling in a 3D environment is an essential process for understanding the geometry of the system being explored.

Jan 1, 2000

By L Crew, S Jackson

A trial of an Adept Online Ore Sizer (OOS) was undertaken at the WMC Leinster Nickel Operation (LNO) in the first half of 2000. During this time the On Line Ore Sizer has been shown to be a robust and accurate instrument for measuring mill feed ore size. Data collected during the trial indicates significant variation in the F80 of the SAG mill feed. The effects of feed size on milling parameters such as mill weight, mill power draw and mill efficiency appears to be dependent on the ore blend treated. With some ore blends a weak positive correlation was found between ore size and mill weight and milling efficiency but with others no correlation is evident. It is believed that the OOS will become a vital piece of equipment in the future as LNO continues to optimises its milling circuit.

Jan 1, 2000

By D Pilone

The Tyrrhenian micro-nodules, findable at low depths (200/600 m under s l) are a reasonable reserve of manganese. They can be easily and cheaply recovered but do not contain valuable metals as in the case of oceanic nodules. In this work a hydrometallurgical process for manganese recovery from Tyrrhenian nodules is presented. The studied treatment includes the following operations: magnetic enrichment, reducing leaching, leach liquor purification and electrowinning . The study shows that the most important step in the process is the preliminary manganese enrichment. It can be done directly on the platform reducing not only the transport cost, but also the residue mud in the metallurgical plant. The leaching parameters such as status and size of nodules, temperature, composition of leaching solution and S/L ratio have been investigated. After purifying the leach liquor by iron precipitation as ammonium jarosite , the conditions to electrowin manganese have been investigated. The yields of both manganese leaching and iron precipitation together with current efficiency and specific energy consumption in the electrowinning step are given.

Jan 1, 2000

Laboratory tests were conducted to study the effects of thrust or pull-down force and rotary speed on the vibration signatures of a particular drill in a known rock type, and to determine how the vibration signatures could be used to assess bit wear. The vibration signatures were analysed using a Wavelet Transform analysis technique, which decomposes the signals in multi-bands of frequency and presents the results simultaneously in time and frequency domain. Results show that as the bit wears, large fluctuations in amplitudes in the high frequency ranges occur, and prominent peaks in the low frequency ranges were observed for a worn bit. The Wavelet Transform technique provides an appropriate and effective metrics for monitoring and evaluating the state of wear as drilling progresses through the post-processing of wavelet coefficients. This study provides a basis for the development of an on-line detection technique of bit wear in rock drilling through Wavelet Transform technique or time-frequency analysis that can be used in real time.

Jan 1, 2000

Just as geophysics, in the form of 3D seismic and wireline logging, plays a key role in petroleum reservoir management, so too will geophysics play an important role in mining of coal, metals, and minerals in the 21 st century. The commercial and social imperatives driving greater use of geophysics are reduced costs, increased revenues, and enhanced safety. In short, superior utilisation of capital and management of risks. In relatively undeformed sedimentary environments it is possible to adapt petroleum-style 3D reflection seismic to image mines. This has been demonstrated most impressively in the Witwatersrand. Anglo-American, for example, completed a $1 million 3D seismic survey at Western Deeps in order to site a new $300 million shaft with confidence. Likewise, 3D seismic has gained rapid acceptance at Australian coal mines in recent years. Encouraged by these successes, metalliferous mining companies are supporting research in Canada and Australia, as well as South Africa, to adapt 3D seismic for more highly structured, metamorphic terranes. Because the mining industry is far more diverse than the petroleum industry in terms of commodities and geological environments, 3D seismic is not always cost-effective. A plethora of other geophysical techniques can be applied, many of which are employed in mineral exploration. Mine applications of geophysics differ from traditional exploration applications in two main ways: time scales and length scales are shorter, and boreholes are more plentiful. Borehole geophysical techniques therefore play a more significant role, both for logging and imaging. Logging systems detail the variations of in situ physical properties down the borehole at scales measured in centimetres, while geophysical imaging techniques can map features located tens or even hundreds of metres from the sensors. While geologists tend to think of boreholes in terms of chips and core, geophysicists perceive them first and foremost as access paths for instruments. Borehole logging has been employed at iron and coal mines for decades, mainly to accurately define ore boundaries in delineation holes. In base metal mines, Outokumpu implemented logging widely for orebody delineation in percussion holes in the 1980s. The benefit was a direct cost-saving, arising from substitution of core drilling with percussion drilling plus borehole logging. The practice has since spread to other companies. INCO, for example, defines nickel boundaries in blast holes at Sudbury using conductivity logs. The benefits are in the form of reduced dilution and enhanced ore recovery, flowing from a more accurate mine model. Density, natural gamma radiation, magnetic susceptibility, and conductivity are the principal metalliferous mine logging parameters because they can be recorded in both dry and water-filled holes. Sonic velocity is the premier geotechnical logging parameter, given its sensitivity to rock strength, stress, porosity, and degree of fracturing. Sonic is recorded routinely in exploration and geotechnical holes at coal mines. With the advent of slimline dipmeter, full waveform sonic, and optical and acoustic scanner tools, the role of borehole logging in geotechnical evaluations is expanding. Monitoring of strain and micro-seismic activity enhances safety during mine production. While qualitative interpretation of logs is adequate for stratigraphic identification or definition of boundaries, a wealth of quantitative information, eg density, can be derived from properly calibrated, repeatable geophysical logs. Moreover, geophysical logs can sometimes serve as surrogates for geochemical assays, and not only for magnetite and uranium. At OutokumpuÆs Kemi chromite mine, for example, gamma-gamma logging provides the basis for grade control. By reducing reliance on assaying, three benefits can be realised: reduced reliance on core drilling; lower core handling and assaying costs; and shorter turn-around times. Conventional downhole EM and borehole magnetics are used for near-mine exploration, and for ground sterilisation. Inco has enjoyed considerable success with borehole UTEM in the Sudbury Basin, for example, and Geopeko has applied three-component borehole magnetics successfully in the Tennant Creek area. Electrical techniques such as applied potential and magnetometric resistivity (MMR) are also finding application at mines. For higher resolution, borehole seismic, radio imaging, and radar have been invoked, with varying degrees of success, to delineate orebodies and map structures, or to geotechnically characterise the rock mass and identify hazards. Success mapping nickel sulphide shoots with borehole radar has been reported by WMC at Kambalda. There are no universal geophysical panaceas, and each mine imposes different geological, logistical, and economic constraints. Geophysics will not always be cost-effective. However, the greatest single impediment to expanded use of geophysics at mines has been the low level of awareness of geophysics on the part of most mine geologists, engineers, and managers and, equally, the limited understanding of mine geology and engineering exhibited by the majority of geophysicists. This myopia will be remembered as a 20th century affliction! Blue Sky areas for mine geophysics in the next ten years include integration of geophysical data acquisition with drilling, enhanced grade estimation and rock mass characterisation, and the incorporation of geophysical information into mine models using geostatistical techniques. All these advances will be predicated on an expansion of petrophysical knowledge.

Jan 1, 2000

Analysis of rock discontinuities, collected using a scanline method, has been undertaken at the Iron Duke open cut mine, on the southern margin of the Middleback Range in the Gawler Craton, South Australia. The iron mineralisation, which is a product of supergene enrichment of carbonate sediments, is located on the W (western) limb of a gently N plunging D2 macrosyncline. Mesofolds plunge shallowly to the NE or steeply to SE, suggesting two shortening events, of which the second produced significant macrofolds. Discontinuities include:faults and shears which display variable orientations, mainly striking WNW dipping steeply N; mesofractures or joints maintaining a well constrained orientation, dipping steeply S, subvertical striking E-W; and bedding surfaces which are folded about a gently N plunging axis. Through this example of the regional control exerted on local discontinuities, it is clear that discontinuities are not randomly distributed as often assumed in purely statistical approaches. Commonly for rocks of any age there is a distinct discontinuity pattern, reflecting the geological deformation history. If the controls exerted on local rock discontinuities can be determined and assigned a number related to their significance, the way forward is available to develop a site specifc knowledge base that can make realistic predictions for any position in a given rock mass. Such a procedure would involve assessment of the regional geology, linked to scanned discontinuities either via manual or automatic means. Recent advances in automatic scanning rock faces (eg by the I-SiTE Laser Radar) to determine discontinuities distributions, enable the rapid calculation of rock characteristics. This is a significant advance in rock engineering, providing a method of safe and quick collection of data. However it creates problems in the presence of an increase in the geotechnical data available, which should be assessed in the context of the regional geology. Although techniques are underway to analyse post-blast discontinuities, the next signifant potential advance in this area could be the integration of a knowledge based system to assess discontinuities ahead of mining, incorporating regional assessment and human intuition.

Jan 1, 2000

By M P. Simpson, J L. Mauk

The Golden Cross, low-sulfidation, epithermal deposit shows a number of features that are directly or indirectly related to boiling hydrothermal fluids. Occurrences of lattice calcite and their quartz pseudomorph equivalents in veins, and occurrences of adularia in veins and in the surrounding altered rocks in the vicinity of ore, are both direct evidence of deposition in the presence of boiling hydrothermal fluids. Loss of carbon dioxide causes calcite deposition (platy variety) near the level of first boiling, while adularia deposits due to the attendant pH increase along the cooling flow path. Indirect evidence of boiling include crustiform-colloform quartz banding, late massive calcite veins, clay-carbonate alteration in the shallow and peripheral parts of the ore zone, and the restricted vertical interval of precious metal mineralisation. The colloform quartz banding strongly resembles the banding in amorphous silica deposits found in geothermal surface pipes. This implies that fluids ascending the Empire Vein structure were saturated in amorphous silica. If so, then they must have undergone phase separation, which initiated at considerable depth (e.g. =1000 m) and very hot temperatures (e.g. =300¦C). On the basis of stable isotope data, late massive calcite veins appear to have deposited from CO2-rich steam-heated waters. Calcite deposited along heating paths as these waters descended into the upflow zone during late stage collapse of the hydrothermal plume. In active systems, such steam heated waters form by deep boiling. The high CO2 contents of these waters promote hydrolytic alteration and the formation of clay-carbonate alteration. Reaction path modelling using CHILLER and a deep, Broadlands-Ohaaki water as an analogue, shows that minerals deposit along boiling flow paths over discrete spatial intervals. Calcite and adularia deposit near the site of first boiling, followed by gold and then by amorphous silica. For deep boiling starting at 300¦C, these minerals deposit over a path length that exceeds 1000 m. The distribution of banded quartz and gold at Golden Cross are consistent with such a boiling model. However, the elevation of first boiling must have fluctuated over 500 m to account for the coincidence of lattice quartz (pseudomorphs of platy calcite) and adularia, crustiform-colloform silica and gold over distances of a few centimeters in veins. We deduce that a downward propagating boiling front and expansion of two-phase flashing in a flowing water column occurred during episodes of high vertical permeability and fluid flux in the Empire vein structure.

Jan 1, 2000

By P SSrkkS

Mining is commonly seen as a typical basic industry with rough and even dangerous working conditions, heavy environmental load, and a low level of high-technology and automation with much manual work and operations. A mining operation (open pit or underground) is a very complex one consisting of many manual, physical, mechanical and logistical operations with different human interfaces and decisions. For this reason it is a demanding and potential area for all applications of automation and information technology: controlling difficult non-linear, time varying multivariable processes and machines; solving of ergonomic safety and environmental problems; automation of logistical systems; applying robotics, mechatronics, and information handling, etc. In addition to that, big economic sums are involved with these operations. On the other hand, automation technology has developed towards intelligent and adaptive systems including some from the above mentioned fields of automation. Connecting them with modern information and communication technologies makes the idea of an intelligent and unmanned mine more and more feasible in the near future. This requires intensive co-operation and co-ordination between the mining industry and manufacturers of mining machinery. This has been successfully accomplished in the five-year Intelligent Mine research and development program as well as the three years of subsequent implementation of its results in Finland. The basic elements of an Intelligent MineTM concept are:mine-wide information and data acquisition system; high-speed two-directional mine-wide communication network for real-time monitoring and control; computerised information management, mine planning, control and maintenance systems; automated and tele-operated machinery and equipment which are connected to the information system; and links to the public information networks. The degree of automation of an intelligent mine depends on many technical and economical factors. The basic precondition for such an approach is that it will improve the total economy of the mine. This paper will describe the Intelligent Mine Technology Program with the results. Also the implementation which took place during starting of a new underground mine (Outokumpu Chrome Oy Kemi Mine) will be described.

Jan 1, 2000

By P Heppner, J Schell, R Newell

The effect of various methods of conditioning on subsequent flotation performance was reviewed, where complex interactions involving attrition, aggregation, dispersion and surface cleaning were discussed. The present study focussed on the influences of standard laboratory cell conditioning, ultrasonic dispersion and high intensity conditioning on copper mineral flotation characteristics. The effect of substituting demineralised water for the WMC plant water was also examined. It was found that higher copper concentrate grades were often obtained using demineralised water, however the use of high intensity conditioning in mill water gave the highest copper recovery and highest flotation rate constant. This process should be considered if copper grade and recovery in this section of the plant drops, especially if the drop is due to surface oxidation of the copper minerals. Other methods of conditioning (cell and ultrasonic techniques) improved the rate of copper flotation above that obtained in the virtual absence of conditioning, showing the importance of conditioning on subsequent flotation operations.

Jan 1, 2000

By T Cutts

Since 1989 Kalgoorlie Consolidated Gold Mines has managed the Kalgoorlie gold operations of joint venture partners Normandy Mining Ltd and Homestake Gold of Australia Ltd. Current production from the Fimiston Open Pit is approximately 650 000 ounces per annum. The mine incorporates a multitude of narrow shear hosted, subvertical lodes, predominantly within Golden Mile Dolerite. Traditionally KCGM has used blasthole based grade control in the Fimiston pits. A single sample is taken from vertical production blastholes, drilled on ten metre benches. This process was improved with the addition of infill drilling along blasthole rows to provide additional samples across strike. However the limitations of adequately defining subvertical mineralised structures with vertical blastholes remain. In 1997 the first of two trial areas were drilled with close spaced, inclined Reverse Circulation (RC) drilling. These tests indicated that RC based grade control had the potential to provide significant advantages. These include:improved delineation of mineralised structures, particularly across strike; reliable short-term mine schedules based on the advance data available from drilling over three benches; and the angled RC drilling is capable of providing samples of near stope and stope fill material which often remains unsampled by blasthole drills due to the safety constraints around unstable underground openings. Based on the success of this initial work RC based grade control was gradually implemented across production areas commencing September 1998. Some of the many challenges faced include:development of effective procedures and systems for the planning, logging, interpretation and modelling of the RC data; obtaining adequate drill coverage due to mine scheduling constraints and restricted access around underground openings; requirement for integrated systems to handle either blast hole or RC data; and development of effective methods to evaluate the performance of RC grade control. RC based grade control is delivering significantly improved lode definition, grade estimation and subsequent ore classification.

Jan 1, 2000

The operations management system at Olympic Dam has evolved over a two-year period to the state described in this paper. This evolution has been driven largely by the requirements of the recent expansion of the Olympic Dam operation from three to nine million tonnes of ore per year. Such a change process demands an holistic approach to mine management and several techniques have been employed including XPAC, Mine Works Planner as well as a basic philosophy of æjust-in-timeÆ completion. The philosophies, software and tracking mechanisms for managing a large tonnage operation are described, outlining a fully integrated scheduling system from shift to shift detailed activity planning to a 20 year production plan. Moreover, the vision of production exceeding the current limit of nine million tonnes means that there are to be further developments to this state-of-the-art system in use at the Olympic Dam mine.

Jan 1, 2000

Modelling and simulation are important aspects of flotation research, which may assist in the design of new circuits and the optimisation of existing ones. Flotation research in the AMIRA P9 project has developed a methodology for flotation plant modelling based on determination of cell (pulp) characteristics. froth characteristics, and ore floatability (using floatability components). The implementation of this methodology requires the determination of ore floatability, to which end a small flotation pilot plant known as the Floatability Characterisation Test Rig (FCTR) has been designed and then built and kindly made available to the AMIRA P9 project by Baker Process. The FCTR has a 2 tph capacity and consists of six 130 litre rougher/scavenger cells and six 50 litre cleaner/recleaner cells. The Mintek FloatStar pulp level control system is used to control the pulp level in all cells. A number of experimental procedures have been developed for using the FCTR to obtain the data required for the P9 flotation models. These procedures include how to determine the floatability parameters, Pi and mi, the bubble surface area flux, Sb, the mean residence of the pulp in the cell, t, water recovery. Rw, froth zone recovery, Rf, and the degree of entrainment, ENT. The flexibility of the FCTR allows it to be used in numerous flotation studies such as stream characterisation, reagent testing, grinding experiments, power studies, oxidation studies, and scale-up and simulation studies. This paper will describe the design and operation of the FCTR and the procedures that will be used to obtain data from the rig for modelling purposes.

Jan 1, 2000

By R Chinamatira

Several technical and economic factors have to be taken into consideration in developing an optimal mining method. This paper describes some of the important factors learnt during the evolution of the sublevel cave mining method at Trojan Nickel Mine, part of the Bindura Nickel Corporation (BNC) in Zimbabwe. Sublevel caving (SLC) has been successfully implemented at Trojan mine since its introduction in 1994. The method has evolved over the past six years into a system that has brought about improvements in efficiencies and productivity. Although the original design parameters used were sound and provided a solid foundation for the system, they needed to be optimised to get the best out of the mining method. Improvements and changes have been made in areas such as the drilling process, charging and blasting techniques, ring pattern design, development size and shape, and the draw control system. This has enabled the mine to develop an SLC operation that is efficient and innovative. Experience gained, together with the theory available has given us a much better understanding of the system. This knowledge will be used in the future to enhance the system further. Given the low grades of the BNC Mines, management recognises that only through technical excellence and efficient mining can the mines reduce mining costs and maintain profitability and competitiveness on the world market. In the Zimbabwe mining industry reaction to technological change, mechanisation and advancement have been relatively slow, due to isolation and economic constraints, compared to the rest of the world. Economic difficulties prevail, with high inflation levels, a poor exchange rate, lack of foreign currency and other associated problems. Despite these constraints, the bold steps taken have transformed Trojan mine into a more efficient and competitive operation, presenting itself as the leading mine in the BNC group. Appendices give data to illustrate the benefits obtained.

Jan 1, 2000

By S Hancock, B H. Brady, H Muhlhaus

The aims of this paper are to present the governing science, verify the performance and demonstrate the potential engineering applications of a computational simulator for in situ leach mining of non-ferrous minerals. Assuming that the target mineral is deposited either uniformly within rock matrixes (matrix-hosted) or on fracture walls (fracture-hosted), in situ leaching can be treated as reactive flow and transport in geological media (porous media for matrix-hosted ore deposits and fractured media for fracture-hosted ore deposits). Under this treatment, the processes of in situ leach mining for non-ferrous minerals can be quantified through several sets of equations and these coupled equations have been numerically solved. The computational simulator has been applied to the simulations of one-, two-, and three-dimensional in situ leaching cases. The computational simulator, together with laboratory and in situ leaching tests, can be used to:optimise the leaching chemistry; optimise the in situ scale mining operations; scale up the in situ scale test operation to a full-scale mining operation; and evaluate the post-mining environmental restoration plan.

Jan 1, 2000

In the 1890s, The Goldfields Water Supply Department in Western Australia commissioned the diamond drilling of two deep artesian exploratory water bores near Coolgardie (Blatchford, 1899). At the time, in spite of strongly-worded advice to the contrary from the Government geologists, there was a wide popular belief that you could obtain artesian groundwater virtually anywhere providing you drilled deep enough. The first Coolgardie hole was drilled to over 900 m, despite the fact that the bore penetrated granite from a depth of 5 m below the surface. Drilling proceeded for more than 16 months, between July 1896 and November 1897. A small quantity of salt water was struck at a depth of 36 m. The second bore was mercifully terminated at a depth of 50 m, also in granite, with again only a small inflow of salt water. Such were the desperate lengths that were pursued to obtain a reliable water supply for the influx of people in the Eastern Goldfields gold rush. The WA Goldfields continued to rely on huge condensers for water supply until that great engineering feat, the construction of a water pipeline from Mundaring Weir to Coolgardie, was completed in 1903. An enormous network of rail tracks penetrated outwards from Kalgoorlie and Coolgardie for the collection of timber, principally to feed the condensers. Remnants of the rail network are still visible today. The acute shortage of fresh water led to great deprivation, disease and death among the early miners. Today, the water problems faced by the mining industry are thankfully not as severe, but they are nevertheless no less challenging. The southern part of the WA Goldfields is a notoriously difficult area for finding potable quality groundwater. Even as recently as the 1990s, there were occasional serious efforts to find potable groundwater in that area, some very imaginative and innovative. One mining company, working south of Southern Cross, spent many months experimenting with recovery of potable quality water from a shallow freshwater lens overlying hypersaline water in a low permeability weathered granite aquifer. They used very low capacity pumps manufactured from car windscreen washer pumps powered by solar panels.

Jan 1, 2000