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By Tzung-mow Yao, S Ki, J Word, J Vinson

Properly designed evapotranspirative (ET) cover systems can greatly reduce the amount of infiltration and groundwater recharge (deep percolation) into potential acid generating mine waste. In arid and semi-arid environments, infrequent precipitation, low measurable subsurface fluxes, spatial variability within mine waste and cover material, and evapotranspiration from below the cover system create challenges to monitoring moisture flux in these systems. Sloped ET single-layer (monolayer) cover depths and a variety of reclamation treatments are being studied at a copper tailing impoundment in Arizona, USA. To monitor the performance of different ET cover systems in response to precipitation patterns, four different test plots consisting of two different cover depths and two different vegetation densities were instrumented with heat dissipation sensor nests. The sensors measure the soil water pressure potential and allow hydraulic gradients to be determined within and below the cover systems to depths of 180 cm. Three replicate sensor nests were installed in each test plot to account for variability in materials and test plot treatments. Data collection occurs twice daily and is ongoing. Weather during the 26-month monitoring period was characterised by two months of greater than normal precipitation followed by nine months of normal precipitation and 15 months of abnormally dry conditions. Monitoring data indicate that deep percolation occurs in response to periods of extended precipitation, however, drying was observed to depths of six feet below the surface in all test plots. Using conservative assumptions regarding tailing hydraulic properties, one-dimensional downward flux predictions based on the monitoring data indicate very low (Additional long-term monitoring and installation of deeper and replicate monitoring sensors into tailings without cover systems are recommended to evaluate the long-term ET cover system performance and develop a better understanding of deep percolation rates at the sites.

Jan 1, 2003

Virtual reality (VR) simulators represent a powerful tool for training humans to perform tasks which are otherwise expensive or dangerous to duplicate in the real world. The idea is not new. Flight simulators have been used for decades to train pilots for both commercial and military aviation. These systems have advanced to a point that they are integral to both the design and the operation of modern aircraft (Adams, Klowden and Hannaford, 2001; Mastaglio and Callahan, 1995). This technology has been successfully extended and utilised in the mining industry in a range of successful applications (Bise, 1997; Denby and Schofield, 1999a; Schofield, 2005; Henning et al, 2002; Kaiser, Vasak and Suorineni, 2005). There are a number of lessons that can be learned from other industries that have successfully utilised virtual technology for a number of years. Specific rules of thumb regarding the specification, development, application and operation of these simulators can be garnered from other industrial training systems and examined in a minerals industry context (Tromp and Schofield, 2004; Schofield, 2006). This paper intends to discuss some of these generic rules in the context of a number of recently developed virtual reality mining applications.

Jan 1, 2008

The discovery of magmatic nickel sulfide mineralisation within the Musgrave Block of Central Australia, in a region which has received virtually no exploration since the early 1970s, promoted a pegging rush throughout the region and provided a significant boost to the investor interest in resources sector companies. The discovery proved a significant success for the application of generic models for major magmatic nickel-copper sulfide deposits. The entry of junior explorers to the region is the principal mechanism by which the region will be explored, although significant social and physical challenges will impact on the ability of explorers to maintain investor confidence in the region.

Jan 1, 2002

Information from bores in the LatTobe Valley has been accumulating for over fifty years, and the manual extraction of details has become a limiting factor in their use.Punched card equipment, installed by the State Electricity Commission for accounting purposes, was known to be available for reasonable periods, and it was suggested that this could help in the extraction of data from the voluminous records.Investigation showed that they could be substantially duplicated on cards, with consequent gains on many operations; the cards being regarded as an auxiliary to the existing records.BRIEF DESCRIPTION OF RECORDSAs a bore is drilled a continuous record of the strata is kept, together with notes on the presence of water or any unusual features which the driller may observe.When coal is struck, samples of each ten feet are usually sent for analysis.The location and surface level of each bore is fixed by surveyors, and details of dates and methods of drilling are also kept.Bores are allocated numbers, prefixed by the name of the parish within which they are drilled. Numbers are allocated in conjunction with the Department of Mines, to avoid duplication.Records of strata and analyses are kept in folders, with 100 bore numbers per folder.Standard plans are drawn, showing the locations, bore numbers and surface levels. For each bore they also show the depth and thickness of coal struck, and the total depth drilled.Cross sections are then drawn, connecting the various coal seams, which have been identified by the geologist.

Jan 1, 1960

Water resources legislation in Brazil is evolving in a number ways. The nature of water resource ownership has changed in the last constitution (1988) so that now all water remains the property of the state and not the individual. There is also an increasing amount of legislation to control water access from the environment and regulation over water quality for water discharged. Finally, in some regions charging for water has been introduced and this is expected to become more wide-spread over the next few years. Increasing government attention to water legislation creates an increased need for mine sites to improve water management. As a fundamental basis for this, it is necessary to make robust estimates of mine site water balances, which also requires knowledge of the regional water balance to provide context for the mine water use. A conceptual model for mine site and environmental water balance is presented. Issues associated with conventional water monitoring are discussed. It is proposed that introduction of automated monitoring to provide comprehensive and consistent data is attractive. However, there remain a number of cultural and practical impediments to purchase, implementation and maintenance of effective monitoring, which are summarised.

Jan 1, 2009

The continuously growing coal mining industry of India presently includes shovel dumper combinations in open cast mines, sometimes with dragline mining of overburden, together with the whole range of longwall and bord and pillar underground mining, continuously undergoing fuller mechanisation. This transition from "low tech" to "high tech" systems is now monitored for reliability and provides bases for comparisons of downtime relative to age and make of equipment, whether imported or indigenous, including spare parts, as well as frequencies of particular failures to allow analysis and progressive improvement. Varying geologies complicate technology and equipment requirements, especially in underground mine,s with minimal technological standardisation, but now, reliability in South Eastern Coalfields Limited has been given more importance and superior technological back-up is being developed.

Jan 1, 1991

By G J. Keyter, P J. Terbrugge, Yu Xianb

There has been disappointingly little development in the understanding of the behaviour of rock slopes in open pit mines over the past 30 years. The lack of development in general, and of robust, standardised approaches in particular, are surprising in view of the æultraÆ deep open pit mines that are being developed to depths in excess of 1000 m. Research has recently been carried out into the occurrence of zones of extension strain in open pit slopes. This showed that very large zones of extension strain can occur, and this finding represents a significant new aspect in slope stability that has not been considered before. The greatest magnitudes of extension strain occur near the toe of the slope, either in the slope itself, or in the floor of the pit. Results of the research will be presented for different slope heights, slope angles and horizontal to vertical in situ stress ratios. The magnitudes of the strains are considered to be large enough to result in fracturing of intact rock, and the fracture orientations predicted are adverse for slope stability. Fracturing that is extension in nature is common in competent, brittle rocks and often develops with some violence and little or no warning, producing easily measurable seismicity. In the slope situation, the expected physical manifestation of this behaviour would be popping off of rock slabs and plates of rock from slope surfaces and popping up of the pit floor, as well as the formation of new fractures within the rock mass. Such behaviour may cause overall slope failure, or may initiate failure, which may then be driven to overall slope failure by other influencing factors or combinations of factors. In addition to instability resulting from the fracture surfaces themselves, all induced fracture surfaces could interact with natural geological structures to facilitate formation of a significant failure surface. Case studies of slope failure in two open pits will be described. In both cases failure occurred æsuddenlyÆ after very limited amounts of deformation. In the first, the slope crest moved suddenly upwards and backwards over a length of more than 200 m, with associated instability. In the second, the horizontal displacement of the slope face was almost an order of magnitude greater than the vertical displacement and occurred æsuddenlyÆ. A recently installed seismic system is detecting events in a significant zone behind the slope face. Both pits were in the 200 m to 300 m depth range at the time of the occurrences.

Jan 1, 2003

Most of the copper deposits in the Lachlan Geosyncline fall within areas having either a common host rock, mineral assemblage, form of ore body or time and method of emplace- ment. On this basis a Cobar-type ore has been recognised in the deposits of the Cobar -- Mt. Hope - Melrose region. The copper ores in the Tottenham-Girilambone area to the east have a different mineral assemblage. In the more rugged Central Highlands nearer the coast copper deposits are generally concentrated either in one of several Ordovician andesite belts, particularly between Wellington and Woodstock, or within Silurian acid volcanics developed in irregular fashion over a considerable portion of this region. In only a few instances is copper known in the granite batholiths which adjoin these volcanic belts. Native copper and magnetite are characteristic of the deposits of the andesite province and it is possible that future mineragraphic studies will indicate significant differences in the base metal sulphides of both the andesitic and the more acid volcanic belts. Ores having similar mineralogy and form to the Captain's Flat deposit are known at various localities in the eastern segment of the latter belt. In the Gundagai area several small copper deposits with associated nickel minerals have been developed in the Coolac Serpentinite belt.

Jan 1, 1969

The latent conditions clause in various general conditions of contract have traditionally proved to be a source of significant disputes in tunnelling contracts, even when extensive geotechnical investigations have been carried out at the tunnel site and a report of these investigations provided with the tender documents, informing the contractor of the nature and extent of subsurface conditions likely to be met with during execution of the works. This paper discusses the contractual aspects of the new latent conditions clause in the recent Australian Standard AS 2124-1986, General Conditions of Contract, in relation to tunnelling contracts. A comparison of this new clause is made with other latent conditions clauses in general conditions of contract in use in Australia and other commonwealth countries. It is seen that the new latent conditions clause in the recent Australian Standard 2124-1986 has, by providing for a reasonable apportionment of risks, attempted to minimize contractual disputes relating to latent conditions in tunnelling contracts and to provide a satisfactory basis for quick and efficient settlement of such disputes should they arise during execution of these contracts.

Jan 1, 1987

By E Werner, B R. Leavitt

The chemistry of acidic mine drainage discharging from flooded coal mines is commonly reported to improve with time after flooding. This investigation describes a 18-year dataset of post-flooding water chemistry for a below-drainage underground coal mine within the northern Pittsburgh coal basin (Pennsylvania, USA). The Montour mine is a 5650-hectare below-drainage coal mine of maximum 260 metres depth. Montour was closed in 1980 and flooded to within 38 metres of land surface within 4.8 years. Pumping averaging 210 L/s was then employed to maintain water levels at this elevation. The flooded proportion of the mine (by volume) at full flooding was 56 per cent. The shaft where water was pumped from Montour for water control is located about 70 per cent of the distance between the mine water table and the back of the mine ù that is, it is close to the back of the mine. The residence time (total water volume at flooding divided by pumping rate for control) is estimated at 5.6 years. Time series of chemical analyses show three phases of chemical behavior in post-flooding discharge. In Phase I (zero to two years after flooding), iron concentrations were high and reached their maximum (1100 mg/L). In Phase II (two to four years after flooding), a transition was begun to alkaline conditions, with decline in iron and other solutes. In Phase III (>4 years), net alkaline conditions began, with iron concentrations declining exponentially to 50 per cent of mined volume. This attainment of net alkalinity in this case may have also depended on abundant calcite in overburden extended up to 30 m above the mine floor.

Jan 1, 2003

On the 18th November, 19'58, the first coal was delivered to the Morwell Power Station from the adjacent Open Cut using conveyors for the transport of the coal from the working face to the boiler bunkers. As the cut develops the coal seam will be worked for its full depth of about 360 feet from four benches, each feeding a conveyor line along th.e face and up out of the cut to the power station and briquette factory. By 1970 the estimated maximum daily demand reaches 60,000 tons and the total annual output 18 million tons. The complete conveyor installation will then total some 9 miles with a capital cost of over £3~ million.The choice of conveyors in place of the more usual rail system was made possible by the development of movable belt conveyors which use mechanical conveyor shifting, high belt speeds and flexible high strength belts and the paper deals with these and some other aspects of the scheme.INTRODUCTIONThe development of brown coal deposits is usually based on open cut workings equipped with a few large dredgers giving an almost continuous output of coal or overburden which has to be hauled a comparatively short distance. These are ideal conditions for conveyor operation, and it is surprising that, until recently, rail transport has been used almost exclusively in brown coal open cuts. In some cases inclined conveyors have been introduced to take the coal from the coal levels up out of the cut to bunkers at groundlevel, but trains have been left to operate between the ditch bunker feeding the conveyor system and the dredger.

Jan 1, 1960

By I Haine, J Penm, T Waring

During 1999 there was a considerable turnaround in world prices for most minerals and energy commodities, except for the bulk commodities (coal and iron ore). The main reasons for this turnaround were: improved prospects in demand for most minerals and energy commodities in the Asian region following a return to both economic and industrial production growth in key economies in that region; continued moderate growth in demand in Europe and North America; substantial production cutbacks in a range of minerals and energy industries; effective reductions in the supply of oil by OPEC nations; and an announcement by European central banks that they would cap the amount of gold they sell and loan in the next five years. Most of these influences are expected to be sustained into the first years of the new millennium. In 2000, with exception of coal, average world prices of minerals and metals are forecast to rise significantly. Gross domestic product and industrial production is expected to grow in some European countries and most Asian countries in 2000 and, with moderate growth expected to be sustained in the United States, demand for minerals and energy is expected to increase. AustraliaÆs main bulk commodities, iron ore and coal, saw prices set for 1999 - 2000 at substantially lower levels in negotiations in early-1999. Double digit price cuts were locked in. However, similar falls appear to have been avoided for coal in Japanese Fiscal Year 2001, while increases of between four and six per cent were achieved for iron ore. Forecast modest recovery in economic growth in Japan and increasing demand elsewhere in Asia are expected to lead to tighter market conditions in 2000. Beyond 2000, world minerals and energy markets will be influenced by the expected robust global supply responses of minerals and energy companies, against a background of sustained economic growth and industrial production growth in major consuming countries. Over the medium-term, a return to declining real prices which have been evident for most commodities in the recent past, is expected as exploration, mining and processing technological change and associated productivity growth continues to reduce industry costs. While lower rates of exploration and mining investment in Australia between 1998 and 2000 will modestly constrain the rate of future industry expansion, Australia remains an important contributor to expected growth in global minerals supply over the medium-term. Australian mine production is forecast to grow between 1999 - 2000 and 2004 - 05, boosted by production from recently commissioned mines and minerals processing facilities and comissioning of other projects at advanced stages of planning.

Jan 1, 2000

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

Jan 1, 1976

Gold mine production in South America was 247.3 tonnes in 1995 up from 156.4 tonnes ten years earlier in 1986. This represents a 58 per cent increase and amounted to 11 per cent of total world gold mine production. The major countries involved in order of production, were: Brazil (67.4 tonnes), Peru (51.5 tonnes),. Chile (48.5 tonnes), Colombia (24.1 tonnes), Venezuela (17.1 tonnes), Bolivia (16.0 tonnes), Ecuador (9.6 tonnes), Guyana (8.8 tonnes), French Guiana (3.3 tonnes) and Argentina (one tonne). The most dramatic increase was reported in Peru where production increased from 10.9 tonnes in 1986 to 51.5 tonnes in 1995, heavily influenced by the production from Minera Yanacocha which began operations in 1993 and produced 17.2 tonnes in 1995.With the reformation of the mining laws and the introduction of investment incentives in all the South American countries in recent years, dozens of major and junior mining companies began flocking into the area in the early-1990s to conduct exploration. A recent study undertaken in Brazil shows that an average of $240 million per year will be expended in this country during the period 1993 - 2010. Twenty-five per cent of this expenditure is expected to be made on gold exploration. Similar figures for Peru are $220 million total per year with 50 per cent for gold; $170 million per year in Argentina with 25 per cent for gold and $120 million ner year in Chile also with 25 Der cent for gold.

Jan 1, 1997

Broken Hill South Limited's discovery of phosphate deposits in the northwest of Queensland in 1966 prompted intensive exploration which has proved phosphate rock in excess of 2,000 million tons at ten separate deposits. Systematic exploration for phosphate in Australia was initiated by the Company in 1964. Early in 1966, an investigation of oil wells in the Georgina Basin in the Northern Territory and Queensland revealed widespread anomalous phosphate in early Middle Cambrian Beetle Creek Formation and Thorntonia Lime- stone. Phosphorites recognised in oil wells in the southeastern part of the Basin, Queensland, led to the discovery of the Duchess deposits, Exploration of the Beetle Creek Formation since 1966 has disclosed nine other sizeable deposits north of Duchess around the eastern margin of the Basin. The Lady Annie and the adjoining Lady Jane deposits, by reason of their location, 160 miles south of the Gulf of Carpentaria, are expected to be the first to be brought into production. Beneficiation testing and engineering investigations commenced in 1967. Transport between the deposits and various port sites in the Gulf of Carpentaria has been extensively studied and a slurry pipeline as a means of transport to a deep water island port, is now being investigated.

Jan 1, 1971

Broken Hill South Limited's discovery of phosphate deposits in the northwest of Queensland in 1966 prompted intensive exploration which has proved phosphate rock in excess of 2,000 million tons at ten separate deposits.Systematic exploration for phosphate in Australia was initiated by the company in 1964. Early in 1966, an investigation of oil wells in the Georgina Basin in the Northern Territory and Queensland revealed widespread anomalous phosphate in early Middle Cambrian Beetle Creek Formation and Thorntonia Limestone. Phosphorites recognized in oil wells in the southeastern part of the Basin, Queensland, led to the discovery of the Duchess deposits. Exploration of the Beetle Creek Formation since 1966 has disclosed nine other sizeable deposits north of Duchess around the eastern margin of the Basin. The Lady Annie and the adjoining Lady Jane deposits, by reason of their location, 160 miles south of the Gulf of Carpentaria, are expected to be the first to be brought into production.Beneficiation testing and engineering investigations commenced in 1967. Transport between the deposits and various port sites in the Gulf of Carpentaria has been extensively studied and a slurry pipeline as a means of transport to a deep water island port, is now being investigated.

Jan 1, 1971

By Sparrow G. J

In a recently completed AMIRA project, 20 samples were searched for gold mineralisation using the automated location facility (ALF) for rare phases on a scanning electron microscope in the CSIRO Division of Mineral Products, Melbourne. The samples were submitted by mining companies in Australia, and Papua New Guinea, and included crushed ore samples, cyclone overflow and underflow products, a flotation concentrate, and 12 tailing samples. Their gold contents ranged from 600 to 0.2 g/t An. Native gold and gold minerals including a gold telluride, gold-silver tellurides, and a gold bismuth mineral, were located in the samples as free grains and associated with other minerals such as pyrite, magnetite, hematite, ankerite, copper sulphides, silicate minerals, and quartz. In the highest grade samples, both micron sized and 200 ¦m grains of gold were found with ALF. It would be difficult to locate such d wide size range of gold in a manual search. Gold mineralisation was located in the tailing samples assaying 0.4 g/t An and higher. In several tailing samples coarse grains of native gold over 40 p.m in size were located. One grain was estimated to have contributed 40 per cent of the gold in the sample. As well as locating gold mineralisation, the ALF examination resulted in the identification of uranium, mercury, and bismuth minerals in the samples. Knowledge of the distribution of these minerals in processing streams could be important in the operation of a concentrator.

Jan 1, 1992

At the beginning of the seventies pre- drainage of methane was introduced in West German coal mining in order to reduce the gas emission from the worked seam. After three pilot tests on the "Rheinland" Colliery (86 boreholes in seam "Prasident"), "Bergmannsgluck/ Westerholt" Colliery (23 boreholes in seam "Gustav") and "General Blumenthal" Colliery (27 boreholes in seam "Hugo" and 170 boreholes in seam "Karl") systematic large scale tests with extended investigations were carried out un the "Rheinland" Colliery (127 boreholes in the seams "Anna", "Blucher", Prasident"). During this time an analogous test was carried out on the "Consolidation" Colliery (21 bore- holes in seam "B"). In these studies and tests the technical feasibility, efficiency and economy could be proved, so that pre-drainage of methane starts spreading. On the "Rheinland" Colliery pre-drainage has become common practice in gassy seams. Mainly two points impede a faster spreading of method: 1. in many cases the necessary requirement, that one or both of the gate roads should ire driven 6 to 12 months before the face is worked, is missing. This is mainly due to the difficulty of retreat mining in passe seams.

Jan 1, 1982

The phosphorus content of the banded iron formation (BIF) and of the associated iron ore deposits in the north west of Western Australia is known to vary widely, a fact which has considerable econ~mic significance. Trendall and Blockley (1970) have described the variety of textural appearances of apatite in the Hamersley Group BlF, and suggest that apatite may account for the entire phosphorus content of the unaltered BIF.A preliminary investigation using an M.A.C. electron microprobe analyser has shown that, at least in some iron ores and in partially enriched BIF and associated shales, the phosphorus occurrence is more complicated than this. A suite of samples was examined from one location which covered the entire Dales Gorge Member and some adjoining macrobands in the Mt. McRae shale, together with samples selected for their high phosphorus content, degree of ore enrichment, and position relative to the enrichment zone. Calcium apatite was not observed in any sample of ore from this sequence, despite its ubiquitous occurrence in the BIF. Silicate mineralogy in the enriched regions also differs from that in the BIF, but this change has not yet been studied in detail.The phosphorus content of goethite in one orebody is often high and appears to be in solid solution in the goethite structure. It shows little or no variability on a micro-scale within a grain, except where theremay be a zoned enrichment near boundaries and solution channels. There is also a limited solubility of phosphorus in hematite (the maximum observed by the author is 0·1 per cent P); but where the hematite is martitic (after magnetite) its phosphorus content is always low or zero. In some bands, martitic hematite has been hydrated to goethite, and this also has a very low phosphorus content. Phosphorus was not found in the silica or silicates in the ore, and even when iron enrichment is just beginning, a limited suite of samples from the BIF suggests that the phosphorus content of the chert microbands is almost entirely in the microscopic goethite nuclei (after riebeckite) scattered throughout the chert. The ability of goethite and hematite to accept phosphorus...

Jan 1, 1973

Magmatism is of first order significance in the extension process. Continental extension is terminated when sea-floor spreading commences, but sea-floor spreading will not commence if magmas do not begin to arrive in sufficient volumes. In the oceanic lithosphere, the rate of magma supply may determine whether sea-floor spreading takes place, or lithospheric extension as the result of normal fault arrays. In continental crust thickened as the result of previous compressional orogeny, the availability of magma may determine a completely different process. The author has examined metamorphic core complexes in a number of tectonic environments, in the North American Cordillera, in the Aegean Sea, Greece, and in the Solomon Sea, Papua and New Guinea. What these terrains have in common is a major collisional orogeny predating a major extensional event. The "roll back" of the lithospheric flexure associated with subduction can be seen as the "driving force" for extension in two of these cases. Metamorphic core complexes in these environments are characterized by domal exposures of crustal scale ductile shear zones, underneath which massive plutonic complexes have been formed. Emplacement of these plutons is associated with anatexis of the surrounding rocks. Migmatite complexes are well developed in the Aegean and Solomon Sea core complexes, and in some core complexes in the Basin and Range. Chains of core complexes can be explained as the result of basaltic and andesitic magmas derived from a linear belt of relatively hot rising asthenosphere, in a zone of attempted continental "break up". It is argued that core complexes are the results of magmas derived from relatively short lived mantle "hot spots" impingeing on extending continental crust which has been overthickened during previous compressional orogeny.

Jan 1, 1990