Search Documents

In 1556, Agricola noted that "a prudent owner, before he buys shares, ought to go to the mine and carefully examine the nature of the vein, for it is very important that he should be on his guard lest fraudulent sellers of shares should deceive him"(1). In today's world, the owner rarely has the opportunity to visit the mine and, instead of reading about the `nature of the vein' in annual reports, prospectuses, government publications, et cetera he sees the words `reserves' and `resources'. Unfortunately, the subject of reserves and resources has become increasingly complex and Canadians, along with their counterparts in Australia and elsewhere, are still struggling with definitions which will attempt to cover all conceivable circumstances from national or regional resource endowment to the material to be extracted next week from a given stope or open pit bench. The providers and recipients of reserve and resource data are: - Government agencies who are concerned with questions of national endowment, strategic use of raw materials and other questions of public policy. - Stockholders who have a vested interest in the basic assets of their companies. - Financiers who are concerned about the security of their loans. - Regulatory bodies whose function is to protect a frequently naive investor from unscrupulous practices. - Management, at head office and on-site, who need basic information for decision-making, whether it be to open up a new mine, expand or close an existing operation, acquire or merge with other entities, or, more mundanely, for routine mine planning. To satisfy their demands with unanimously accepted definitions is a formidable task but, it is my impression that, little by little, a concensus appears to be growing within the industry.

Jan 1, 1987

By M Darvall And R Fare, D Dormer

The Argo Archaean lode gold deposit is hosted within a structurally complex shear zone system, 70 km south of Kalgoorlie, and 3 km west of the crustal-scale Boulder û Lefroy Fault. Argo is an active underground mine currently producing at a rate of 120 koz pa with a Probable and Proven Reserve as at December 2005 of 2.19 Mt at 5.94 g/t Au (419 koz), a reduction on the December 2004 Probable and Proven Reserve of 4.58 Mt at 5.74 g/t Au (845 koz). This Reserve is hosted in six separate gold bearing lodes within the Argo shear system. Presently, a further six subeconomic shears are recognised. The 2005 Reserve figure represents a reduction of 426 koz compared to the 2004 Reserve as a result of a thorough review of the geological interpretation/resource model, and engineering factors applied to the Resource/Reserve, and depletion due to mining. Year on year Resource/Reserve figures at Argo had gradually increased as additional information on the system became available and mining methods were increasingly resolved with early production. The portal for Argo underground mine was cut in June 2002 within the highly profitable Argo open pit. The proposed æAvocaÆ bottom-up mining method required extensive lead time between development and the commencement of stoping in April 2004. During development considerable additional complexity in the Resource was encountered. Additional structures were identified, and complex splay interactions affecting the geology impacted on development. Intensive concurrent exploration in the footwall to the main lode during this period was the main cause of the increase in the Resource/Reserve figures during early development. As development progressed, lower grade continuity was observed than was previously interpreted. At the same time, drilling of deeper portions of the deposit and subsequent reinterpretation of the geological model significantly reduced strike lengths of economic mineralisation. Radical changes to the mining methods were required to improve productivities and to satisfy geotechnical considerations. The changes altered the engineering factors applied, which resulted in a reduction in the Reserve figures.

Jan 1, 2006

By Sivell W

We discuss the origin of the Patuki ophiolite complex and the Dun Mountain ultramafics of Middle Permian age in Nelson, New Zealand. It is shown that the Patuki volcanics have strong affinities with tholeiites of mid ocean spreading ridges transitional to alkaline basalts similar to those from fracture zones and ocean islands. At D'Urville Island, typically pillowed alkaline basalts enriched in rare light rare earth elements (LREE) - ophitic spilites - are associated with LREE-depleted (N-MORB-like) tholeiitic spilites with intergranular textures. The metabasalts are associated with a wide variety of sediments, and with sediments are intruded by conformable sheets of serpentinite. Coarsely crystalline mafic and plagiogranitic rocks signify vents and magma chambers, and we propose that the group developed as ocean crust from a slowly spreading mid-ocean ridge, transform association, overwhelmed at intervals by volcaniclastic sediment. Detailed mapping at a scale of 1:5000, and stratigraphic and geochemical development and structural coherence, show that the group is not melange in the Franciscan sense. The Dun Mountain Group, of serpentinites, peridotites, dunites, gabbros and other rocks, intruded the upper Patuki Group as a linear series of aligned pods and sheets. They carried up with them tectonic inclusions of older rock, which were metasomatised, and altered wall-rock, and one low angle dike passed several hundred metres into overl~ing sediment, at moderate temperatures (500 C). The rocks did not act as a floor (and alleged source) for the Patuki, but partly post-dated and were emplaced into Patuki.

Jan 1, 1987

By C Standing, R Lacourt Rodrigues, C Q

The value of iron ore depends on the grade of the contaminants. Scheduled iron, and the associated contaminants, provides mine planners with a measure of stockpile feed and blending requirements. Blending at the stockpiles is one approach to optimising iron grade, while minimising the variability of contaminant grades. These schedules are typically based on resource models incorporating geology and iron and contaminant grades. Resource models reflect best estimates of trends for each of the elements rather than the potential variability, which is critical for accurate short-term blending. Conditional simulation provides a tool to describe the likely variability of each element. Only recently has conditional simulation technology allowed the inherent correlation between elements to be incorporated into the process. This paper presents the stepwise co-simulation process used to simulate and describe multi-element variability for effective mine planning. A case study using the multi-element conditional simulation and the subsequent uncertainty in the schedule and stockpile planning is presented. This process supports proactive mine planning to minimise unexpected fluctuations in the final product.

Jan 1, 2005

By Muller M, Ashley PM

Massive sulphide ZnPbCuAg deposits in the Halls Peak district of northeastern NSW are of the submarine volcanogenic type. They occur as a number of small lenses enclosed in shale and epiclastic rocks, in association with felsic volcanics of early Permian age. The deposits crop out in steep terrain near the eastern edge of the New England plateau. Local relief of 700 m and slopes up to 50¦, coupled with an average annual rainfall of about 1000 mm has led to local severe landsliding in previously mined areas. Mining from the 1890's to the 1960's has also resulted in unconstrained drainage of heavy metal-bearing acid waters and physical dispersion of finer grained metalliferous sediments into the Chandler River. Waters emanating from the main landslide area, from underground workings and draining scattered unconfined stockpiles of massive sulphide ore have pH values of 3 to 4 and contain elevated contents of Zn, Cu, Pb, Cd and Fe. Chemical mobility of heavy metals into streams occurs under low pH conditions with Zn exhibiting the greatest dispersion. Increasing pH conditions downstream cause precipitation of Fe phases and coprecipitation of heavy metals. Physical dispersion of secondary metal-bearing minerals into the surrounding creeks results in wt% levels of Cu, Pb and Zn in the stream sediments thereby exceeding the regional background values by one to three orders of magnitude. Areas disturbed by mining are characterised by lack of vegetation, biomagnification of heavy metals into algae and lower plants, and partial recolonisation by metal-tolerant grass species (Snow Grass, Poa sieberana; Blady Grass, Lomandra longifolia). Rehabilitation measures will have to include landslide stabilisation, impervious sealing or removal of sulphidic materials, import of topsoil and revegetation by metal-tolerant, slow-growing native grass and shrub species.

Jan 1, 1995

The Banda arc, a U-shaped orogenic belt which separates oceanic crust of the Banda Sea from continental crust underlying the Australian- New Guinea shelf, has been interpreted to mark the convergent boundary between the northward-moving Indian Ocean- Australian plate and the Southeast Asian plate (Hamilton, 1979; von der Borch, 1979; Bowin et al., 1980). East of the island of Sumba (Fig. 1), the oceanic crust of the Indian Ocean has been completely subducted and Australian crust is now thrust under the Banda arc. Controversy has centered over the interpretation of the Timor trough as the surface location of subduction and the significance of the Savu Sea between Timor and Flores as either a forearc basin or the continuation of the Java trench (Karig et al., 1987). Two concentric island ridges, called the inner and outer Banda arcs (Hamilton, 1979), separate Australian continental crust from the oceanic crust of the Banda Sea (von der Borch, 1979) (Fig. 1). The inner arc is a typical volcanic island arc composed of calc-alkalic volcanic rocks of Neogene age, while older (Permian and younger) complexly deformed sedimentary and metamorphic rocks make up the outer arc. Timor is the largest and most extensively studied island of the outer arc and is separated from the inner arc by the Savu Sea. The triangular-shaped Savu Sea appears to be a complex forearc basin divided by a series of buried basement ridges (Karig et al., 1987). The outer, convex side of the Banda arc is followed by a major negative bathymetric feature known ne rho Timor trnnnh

Jan 1, 1987

By N Boughen, P Ashworth, S Johns, C J. Yeats, A Littleboy

The ocean floor, often called the last frontier, is increasingly discussed in terms of its resource potential û from near shore building aggregate and placer deposits to massive sulfide orebodies in the deeper ocean. Consequently there is an increasing incentive to mine the seafloor. But, do we have the social license to explore and mine the seafloor? Does this nascent industry have support amongst the wider community? If not, why not? And what should be done? To answer some of these questions, the Wealth from Oceans National Research Flagship has explored the social viability of an expanded seafloor exploration and mining (SEM) industry inAustralia. The results show that there are significant geological and environmental data gaps and that, in the absence of sufficient information, stakeholder reaction to the prospect of an SEM industry expansion may be reactionary and negative. This uncertainty means that the perception of risk from the industry is variable and often dependent on individual values. The acceptability of an expansion to the SEM industry is currently precarious, in particular due to the high levels of uncertainty regarding the environmental impacts of seafloor activity. While there are existing federal regulatory frameworks and government processes for the licensing of seafloor mineral exploration and extraction, there is little precedent in the application and implementation of these regulations. The future viability of the industry will be highly dependant on AustraliaÆs ability to improve the knowledge-base underpinning its regulatory regime and also to generate open and transparent communication channels between stakeholders. It will also be dependent on the SEM industryÆs ability to communicate an acceptable value proposition to society. This proposition will need to include the relative impacts of terrestrial and marine mining, the alternative potential uses of the ocean and the multi-use conflict that SEM might engender. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Milner SC

Four quartz latite rheoignimbrite units (units I to IV) mapped in the Goboboseb Mountains have been traced to their eruptive source, the Messum intrusive complex; this is a complex multistage ring structure (18 km diameter) with well defined gabbroic, monzonitic, and syenitic intrusive phases, and a central ring zone containing mixed rhyolitic to latitic agglomerates. Three of the four quartz latite units are correlated with the upper and lower (2 units) Springbok quartz latites outcropping some 90-130 km north of McIsum. This implies minimum volumes of 300-500 km for wits I and III (Lower Springbok) and 2200-2600 km for unit IV (Upper Springbok). This latter unit is still ti 300 m thick at its outcrop limit, some 130 km from Messum. Each of the four units represents single cooling units. Lithologically, each can be divided into three zones: A basal, dark grey to black flinty or glassy zone, often with highly attenuated fiamme (ressembling flow banding); a central massive and strongly recrystallised zone; and an upper variable zone which exhibit breccias, contorted flow banding, and amygdaloidal to pumiceous clasts. Their overall characteristics tend to be intermediate between ash flows and lava flows. The rheoignimbrites are interpreted as the oproducts of dense, high temperature (950¦-1100 C) ash flows which underwent rheomorphism and lava-like flow prior to their final cooling.These large scale eruptions are related to the initial rifting of Africa and S. America, possiby in response to a major hot spot.

Jan 1, 1990

This paper summarises the results of a study carried out for the Sustainable Minerals Institute, University of Queensland, aimed at identifying the major water-related issues facing the minerals industry internationally and the research required to support the development of practicable solutions. An overview is given of the sources and uses of the worldÆs water resources and of the regional and global sustainability of water supply and management. Agriculture is the worldÆs major user of water; it wastes more water than the minerals industry uses. Water reform and its potential impact on the minerals industry are discussed with particular reference to Australia and South Africa. The sources, uses and management of water on mine and processing sites are outlined. Particular attention is paid to the importance of groundwater as a source of often saline water that can be used in mineral processing and for other purposes. Aquifer storage and recovery has the potential to help conserve water resources. Generally, the major uses of water on mining and processing sites are for mineral processing and refining and for the associated tailings disposal. Water consumption for these purposes may be reduced by recycling process water, using saline water, paying close attention to water management, thickening tailings and using techniques such as dry stacking and paste. A change in the minerals processing paradigm in respect of water use could come through research into new, improved and less costly dry processing techniques. The treatment of mine and processing water will be required increasingly before water is reused, stored, discharged or sold, and before sites are decommissioned. Research and development are required to reduce costs and develop new treatment methods. Mine closure and decommissioning raise a number of long-term water issues requiring continuing generic and site-specific research and development.

Jan 1, 2003

By M P. Sandy, J B. Simpson

The empirical stope design techniques developed by Mathews et al (1981) and refined by Potvin (1988) and others, have gained rapid acceptance in Australia in the 1990s as a simple, æfirst-passÆ means of designing primary stopes. However, it is recognised that these æstability graphÆ methods can only provide broad design guidelines. Recently published stability graphs (Hutchinson and Diederichs, 1996) encompass a wide range of geological environments, which are not discussed, and the influence of time and blasting practices cannot be easily reviewed. The æscatterÆ in the graphs must reflect, to some degree, different operating practices as well as subtle but important differences in the pre-mining conditions that are not adequately accounted for in the æmodified stability numberÆ. Development of a ælocalÆ, site-specific stability graph may overcome some of these problems. At NormandyÆs Golden Grove Operations, Western Australia, detailed reviews of stope stability performance, including Cavity Monitoring System (CMS) surveys, are undertaken for every stope, with the objective of developing a series of local stability graphs, customised to site conditions and calibrated in terms of æAverage Falloff ThicknessÆ (AFT). Cablebolting of stope hangingwalls is used to develop reinforced æbeamsÆ on each sublevel, effectively dividing the full span into smaller, more stable æsubspansÆ. By analysing stope stability performance in terms of fall-off, cost-benefit studies can be undertaken of the effect of cablebolting and other options for modifying stope spans. The approach used to develop the local stability graphs, and their integration into routine stope design procedures at Golden Grove, is described. The experience gained during stope extraction in the Scuddles orebodies has been successfully applied to the Gossan Hill æC-PanelÆ orebody. This methodology should be applicable to other underground mining operations.

Jan 1, 2000

By Parfitt RL

A quarter of the North Island, New Zealand is covered by weathered volcanic tephras of mainly andesitic and rhyolitic compositions. Rapid weathering of basic volcanic glass and slower weathering of acidic glass have produced short-range order alumino-silicate clays such as allophane. Although amorphous to x-rays they have a high degree of local structure. Allophane comprises hollo spheres of approximately 40 diameter and 7 X wall thickness. This small particle size and morphology gives a very high surface area (up to 800 m2/g). Ferrihydrite is another short-range order clay of similar small size and high surface area; it has ò formed from the rapid oxidation of water containing ferrous iron derived from volcanic rocks. The quantity of allophane present in tephra depends upon the climate, the nature of the volcanic glass and the time it has weathered. In New Zealand highest amounts (-50%) occur in beds of andesitic ash deposited on old ignimbrite surfaces with mean annual rainfalls >1600 mm. Both allophane and ferrihydrite will react with oxyanions, such as phosphate, arsenate or borate, and remove them from solution. Other anions such as fluoride also react with aluminium sites on the mineral surface. At NZ Soil Bureau, Department of Scientific and Industrial Research (DSIR), New Zealand, techniques have been developed for granulating allophane to enable it to be used to remove pollutants from solution without dispersion into the liquid phase. This granulated allophane can be used to remove phosphate from sewage effluent or fluoride from tap water without having a sedimentation stage to remove the clay.

Jan 1, 1987

By S Servant

In the mine of this study, cemented hydraulic backfill is placed under the form of a slurry at a percentage of solid by weight varying from 50 to 65 per cent. This slurry settles and cures in the stope. During this process an important amount of water must be drained from the stope. Field observations in the case studied here show that the geometry of the drains system has a significant impact on the drainage of the stopes. The mode of filling produces a backfill showing an evident stratification typical of a sedimentation process. In situ observations on this material show that this stratification translates into a very strong heterogeneity in the physical properties of the cemented backfill. This heterogeneity should affect the hydraulic conductivity of the backfill in the stope. In order to study this aspect, finite element simulations were performed. This paper presents the results of these simulations, where the impact of this stratification on hydraulic conductivity is related to the performance of the backfill drainage system for various geometry. This preliminary study is aimed at providing a better understanding of the role of the drains in the dewatering process of the backfilled stope in the case of this mine.

Jan 1, 1998

By Johnson N. W, Manlapig E. V, Alexander D. J, Franzidis J. P

The importance of the froth region on flotation performance is often emphasised in the literature. It is well-known that decreasing froth depth or increasing air flowrate results in increasing cell recovery at the cost of lower concentrate gra

Jan 1, 1997

By B Hooper

Deep cuts in CO2 emissions will be required to stabilise and, in the long term, decrease CO2 concentrations in the atmosphere. Technologies for capturing CO2 from major stationary sources (power stations, industrial plants, etc) and storing that CO2 for long periods of time is one of few near term options for decreasing CO2 emissions. This transition to low carbon intensity energy and possibly the hydrogen economy through renewables and in the long-term technological developments such as artificial photosynthesis.Capture of CO2 from post combustion emissions can be done using a range of technologies though costs are currently high and dependent on the concentration of CO2 in the emissions. Techniques include solvents, pressure swing adsorption and the use of membranes. Options for decreasing capture costs by increasing the concentration of CO2 in the emission stream include the use of oxyfuels (in pulverized fuel types boilers) and by moving to integrated gasification combined cycle (IGCC) operations either simply for power generation or for poly-generation opportunities. Once the CO2 has been captured it can be stored using a variety of methods. Storage in the ocean has been suggested but is considered an unlikely option because of environmental uncertainties and political opposition. Mineral storage is a niche opportunity. The greatest potential lies in geological storage of CO2 and this option is commanding increased attention from the Australian and international community.In Australia, the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) is an important new initiative that will support energy companies and energy intensive industries in meeting challenges posed by greenhouse gas issues and assist them in their efforts to reduce their emissions profile.The progress of geo-sequestration and the challenges in the capture and separation of CO2 in the process industries are discussed.

Jan 1, 2004

In the future to excavate sufficient coal for power generation, two dredgers would be required to dig overburden or interseam 70010 of the time and three dredgers 40010 of the time. One overburden system was not adequate for this requirement, making coal production reliability vulnerable. TS5 spreader is the new machine element of this system. The selection of the best type of machine configuration to suit the application was then subject to an internal SECV VE Study, a registration of interest and a tender for two machine alternatives. This paper outlines the reasons why SECV planned the Secondary Overburden System and how the Krupp machine met these requirements. It also identifies the main design features of the machine and its constructability which will allow the machine to be operational by the end of May, 1990.

Jan 1, 1989

HISTORY OF PROCESS DEVELOPMENT The manufacture of coke from coal commenced at the beginning of the 17th century by heaping coal into circular mounds in the open, covering with earth, clay or ash and slowly burning the coal in the mounds to produce a heap of coke. Naturally the process was slow in production rate with low coke recovery due to the loss of that part of the coal which was completely burnt to ash. As a natural consequence of this initial carbonisation method, a coke oven design was developed so that the coking chamber, which was constructed of brick, was circular in plan, cylindrical in section with a dome shaped roof - similar in shape to the original coal mounds. As the shape of the chamber was similar to the old dome shaped beehive, the ovens were called beehive ovens. The ovens were built in long single or double rows with retaining walls between each oven and as such were known as a battery of beehive coke ovens. In these early beehive ovens, coal was charged from hand wheeled tubs into a hole into the top of each oven, hand- levelled with a rake and the oven side opening sealed with bricks and clay except for some small holes in the opening to admit limited quantity of air for combustion. Coking commenced by the heat retained in the brickwork from the previous charge. The gases evolved from the coal, together with the admitted air, were partially burnt inside the oven to supply the heat for carbonisation and the surplus gases were burnt to waste at the top charging hole. The heat from this gaseous combustion inside the oven together with the reflected heat from the brickwork of the arched roof of the oven allowed carbonisation of the coal charge to proceed from its surface slowly downwards to the floor of the oven. At the end of the coking cycle (usually 4 or 5 days) when there was no more evolution of gases, as indicated by diminishing gas flame and a drop in oven temperature, the brickwork of the oven opening was removed. The coke was then quenched by inserting a pipe with spray holes to spray water over the coke charge in the oven after which the coke was raked from the oven. The work of charging and levelling the coal, bricking and removal of oven opening, quenching and raking out the coke all required manual labour. As these ovens only carbonised a 5 to 7 ton charge of coal per cycle of 4 to 5 days, to produce 3 to 41/2 ton of marketable coke, the labour required per ton of coke was high.

Jan 1, 1975

By G R. Ballantyne, M S. Powell, M Tiang

This paper reviews the proportion of energy attributable to comminution within the Australian gold and copper mining sector. The need for this is motivated by inconsistencies in the quoted energy usage data and the lack of a common basis for reporting the fraction of energy in mining that is attributable to comminution. This study should form a reliable basis from which to assess both demand and opportunities to reduce energy consumption.The proportion of milling energy was calculated for the major producers in the Australian gold and copper sector. A sampling methodology created by Powell et al (2003 - 2010) was initially used to provide an accurate and meaningful measure of the energy used in the comminution process. However, no useful method for grouping similar mines was found. Fortunately, a surprisingly large amount of high quality data was found from a number of different sources, allowing the development of robust relationships to be used to estimate a high proportion of the unknown values. The fraction of energy attributable to comminution was found to be dependent on how the total energy consumption was defined. For instance, comminution accounted for 52 per cent of the electrical energy, but only 21 per cent of the total energy publicly reported by the mines because a substantial proportion of energy used on a mine is in the form of transportation fuel (mostly diesel). Critically, the measured electrical energy consumption does not account for transmission and generation losses, while diesel energy usage is typically quoted according to its calorific value. This review proposes that diesel should instead be converted via the mechanical efficiency factor for diesel engines. Using this conversion, comminution was found to account for 36 per cent of the available energy on average. This approach allows a useful basis of comparison for mines regardless of whether milling energy is obtained from electrical or diesel generation. A summary of the results are shown in Figure 7 with other values obtained from literature. The total comminution energy assessed in this study accounts for 1.3 per cent of AustraliaÆs electricity consumption, this figure will increase as the other mineral commodities are added to the study.CITATION:Ballantyne, G R, Powell, M S and Tiang, M, 2012. Proportion of energy attributable to comminution, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 25-30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Exploration risk increases with time, due to a general decrease in prospectivity as the more accessible deposits are found, and be- cause of rising costs and demands due to an improving standard of living. Risk is separated into financial risk, which increases sharply at the development stage, and the risk of failure which is at its peak at the outset of exploration. Risk is also divided into internal and external factors; some of the latter cannot be offset, viz. the systematic overall risk for any enterprise. The recently emergent risk embodied in withdrawal of large areas from exploration access is discussed. An appeal is made for objective multiple land-use policies to be applied so that land remains available at reasonable cost and with appropriate environ- mental safeguard conditions. Risks specific to gold exploration are discussed. As gold now accounts for over 50% of all mineral exploration, and most other metals are depressed, any sharp decline in gold will have grave effects on the ex- ploration industry. Gold exploration will become more difficult and expensive in about five years, after most of the readily accessible deposits in Australia are found. Government's role is important in pro- viding stability and basic data at reasonable cost. Exploration for specific minerals or of particular areas could be stimulated by extending the 150%.tax deductibility of R & D to aspects of exploration of strategic im- portance, particularly in the event of a downturn. Exploration is classic scientific research, at least through to the proving Stages.

Jan 1, 1987

By Doig ID, Phillips HR

As a prelude to studying the sorption desorption and permeability behaviour of coal cores in a triaxial stressing rig using sorb- able gases, the air permeability of typical cores was measured. Lump coal samples were obtained from three gas-troubled collieries in Queensland and New South Wales. These were cored in the laboratory and a simple laboratory permeameter employed which accepted 38 x 40 mm cores in a thick rubber sheath. Air pressure of 500 kPa was applied outside the sheath to provide suitable sealing between the rubber and the coal. Differential driving pressures up to 100 kPa were employed and the air flow measured by displacement of water columns in inverted graduated cylinders. Flow measurements accurate to + 2% could thereby be achieved. Coal lumps were cored both parallel and perpen- dicular to the bedding plane, and were observed prior to measurement for any notable features, in particular for the presence of fissures. Between samples an overall variation of from 100 milliDarcy was found in Appin, Westcliff and Leichhardt coals. Significant variation was observed both from section to section of a core and between regions of a

Jan 1, 1982

This paper examines the latest advances in mine drive and motor systems. In the last decade, the drive technology employed for large mine winders has migrated from the traditional dc technology to ac motors with cyclo convertor drives. Recent advances in pulse width modulation (PWM) drives have resulted in these being applied to large winder drives. While having many advantages for the winder system, the PWM drive must be carefully designed to ensure long-term reliable operation. When combined with induction motor technology, the PWM drive presents the ideal solution for winder drives. This paper examines the factors in choosing a suitable PWM drive for a winder installation. Factors under consideration include: winder duty cycle, drive rating restrictions, choice of power semiconductor device, cooling, and low speed operation.The cage induction motor is the motor of choice for large winder drives and has a number of advantages over the synchronous motor. The induction motor is ideally suited to integrated winder applications where the motor is built inside the friction drum, as installed at WMCÆs Olympic Dam site. The challenges of integrating the induction motor into the friction drum will be detailed, including: assembly, ventilation, air gap adjustment, and position sensors.

Jan 1, 2005