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Many of the large refrigeration plants used in, the cooling systems on deep South African gold mines are situated on surface where they are exposed to seasonally and diurnally varying climatic conditions, and to a diurnally varying demand for cooling made by the mine. It has been traditional to accommodate the seasonal variation in climate by manual control applied to the plants at appropriate times of the year, and the plants have normally been specified to conform passively to the diurnal variations. This paper introduces new strategies for the active automatic control of the plants on a diurnal cycle, and shows that attractive benefits in energy and chilled water resource management can be accrued through the use of these strategies. The results have been derived through the modelling and simulation of a representative refrigeration plant.

Jan 1, 1985

By Pyrih R, House A, Shangraw J, Silva AJ

Sunbeam Mining -Corporation has the inten mine with heap leach gold recovery, near spent ore indicated a relatively high ar topographical configuration, the spent across a small drainage and a lake. Du permit for spent ore disposal from th agencies, concerns about the potential contamination by the arsenic were expres conducted extensive studies to addre contamination. These studies consiste( geochemical and geotechnical parameters underlying the proposed disposal si geotechnical investigations were also hydrologic characteristics were include with the use of an IBM PC computer. :ion of opening an open pit gold Stanley, Idaho. Testing of the ?enic content. Due to the local ore was planned to be disposed :ing the process of obtaining a federal and state regulatory for surface and ground water .ed. Sunbeam Mining Corporation is the potential for arsenic of laboratory testing of both of the spent ore, and the soils te. Field hydrogeologic and -onducted. Local climatic and 1 in the analysis of these data Conclusions of studies indicated that although the seepage through the spent ore disposal would contain an elevated dissolved arsenic content, the hydrologic and geochemical characteristics of the site would prevent arsenic migration into the local ground water system. The attenuation of arsenic on soils with high clay content, and dilution after reaching the ground water table would lower the arsenic content to acceptable Concentrations.

Jan 1, 1988

By Zervoudis J

Limitations of current touch-up solders for galvanised steel include coating thickness control problems and poor corrosion and abrasion resistance as well as health and environmental concerns due to toxic constituents such as lead. This paper reports on progress in ILZRO-sponsored research to develop an improved touch-up solder. Encouraging results were achieved in torch soldering trials with experimental zinc-tin-based alloys. Mouldability and coating thickness control were achieved over a practical working temperature range in which the solders consisted of a viscous mixture of solid primary zinc phase particles in a liquid zinc-tin eutectic matrix. The mouldability was dependent on the microstructure of the solder sticks, and optimum structures could be obtained through control of casting solidification rates and by the addition of small amounts of copper. Hardness, abrasion resistance, adhesion and corrosion tests on experimental Zn- (40 - 50 per cent) Sn-I per cent Cu also showed improved performance over lead-tin-zinc solders and compared the effects of tin content within this range. Atmospheric corrosion testing and optimisation of alloy composition and methods of solder stick production are continuing.

Jan 1, 1993

By Katsuyama K, Nag DK

Three aspects of rock mechanics, namely, in-situ stress estimation by acoustic emission (AE) method, strength of rock mass and role of chemicals to reduce the strength are covered. It is possible to detect the previously applied maximum stress by stressing a rock specimen to the point where there is a substantial increase in AE activity. This is known as Kaiser effect. From the AE signatures in the second and subsequent loadings, AE take-off point was identified more easily than in the first loading. In determining the compressive strength of rock mass, two factors have to be considered, namely, the size effect on the compressive strength of intact rock and the effect of discontinuities on the compressive strength of rock mass. Although a modified Bieniawski criterion gives best agreement with the triaxial test data, modifications have been suggested to Hoek-Brown criterion due to its popularity. It is possible to reduce the tensile strength of sandstone by saturating it with weak chemical solutions made with dodecyltrimethyl ammonium bromide, polyethylene oxide and aluminium chloride by up to 30%. In the case of compressive strength, there is no appreciable effect. The possible explanation is that the chemical solutions produce an effect on the strength of sandstone only when the failure mechanism is dominated by tensile mode.

Jan 1, 1998

By Mould G. R

The paper presents a general background to the subsidence research programme being undertaken by the Department of Mineral Resources and Development in New South Wales. The results of the studies undertaken over the last ten years are summarised. The differences between these results and those obtained by the National Coal Board are discussed. The results of a study carried out on the effect of total extraction beneath a freeway in the southern coalfields are discussed in some detail. The procedures developed for the const- ruction of a 500 mm diameter natural gas pipe- line crossing a number of collieries in the northern coalfields are also outlined. The future direction of the Department's subsidence research programme is discussed.

Jan 1, 1980

By Gunther L. M, Rich N

Remapping of the Burdekin Basin has resulted in the subdivision of the three formations (megafacies) previously recognised in the Late Devonian Dotswood Group. Nine dominantly volcaniclastic facies are now identified within the three megafacies, representing coastal plain, floodplain lake, alluvial plain, ephemeral lake and alluvial fan depositional environments. The Dotswood Group was deposited during a major regressive phase that began at the end of the Givetian, continued throughout the Frasnian and ended in the early Famennian.The proposed depositional model completes a southeasterly progradation of coastal plain facies over shoreline and nearshore marine facies established in the underlying Fanning River Group. Uplift and associated acid-intermediate volcanism to the south of the Burdekin Basin, resulted in the deposition of a volcanogenic alluvial fan facies locally preserved along the southwestern margin of the basin. Tuffs and ?ignimbrite were deposited in widespread floodplain lakes which lay behind the coastal plain. An alluvial plain traversed by southward flowing rivers, formed the northern margin of the basin.

Jan 1, 1990

The story of the Penjom gold mine located near Kuala Lipis on the Malay Peninsular demonstrates the valuable role successful exploration companies can play in the development of the gold mining industry. Avocet Mining PLC ('Avocet') began exploration in the area on a limited budget in 1989, securing land tenure around the Penjom alluvial workings in July 1990. The lease granted, known as Block 7, formed part of a land package offered at the time by the Pahang State Government to develop the resources of the area. Until the late-1980s, the Kuala Lipis region, situated approximately 180 km north west of Kuala Lumpur, had restricted accessibility for security reasons precluding serious exploration or mining activity. The situation has changed dramatically in the 1990s, with several foreign explorers active in the Peninsular, targeting old alluvial and underground workings adjacent to the north-south trending Raub-Bentong Suture. Deeper drilling of these prospects has shown there is potential for both small- to medium-scale open pit mining and possibly underground operations, providing companies such as Avocet with an ideal mining investment opportunity.

Jan 1, 1997

By Cutafani M, Lama R

An approach to combatting abnormal roof control conditions in underground coal mines is outlined. Support techniques available are discussed along with the methods available to be adopted in different situations. Properties of materials available presently are tabulated together with the conditions of their Application.

Jan 1, 1988

The problems arising in the excavation of hard rocks with the use of mechanical tools consist chiefly in a slow advance rate accompanied by an intensive wear due to the toughness and abrasiveness of the rock. In order to allow the further extension of mechanical excavation beyond the limits of the presently available technology, the assistance of waterjet aiming at improving the performance of the equipment while reducing the wear rate of the tools, has been recognised as one of the most interesting technical solutions. The paper illustrates the improvement of the performance of both disk cutters and picks obtained with the waterjet assistance at the Waterjet Laboratory of the University of Cagliari on a medium-hard rock.

Dec 6, 2010

Deposition of uranium in the South Alligator river area has been influenced structurally by reverse faulting; and lithologically by carbonaceous shales and sandstones. Mineral assemblages suggest a mesothermal-epithermal epigenetic mode of origin. The ultimate source of the uranium and associated metals is probably in deep seated magmatism which is expressed at surface in the widespread penecontemporaneous vulcanity.

Jan 1, 1968

By Mercer JK

This paper gives a description of the research undertaken by an explosives manufacturer to give better technical advice to the Mineral Industry. Blasting Physics is defined as giving a systematic and coherent account of the initiation and subsequent effects of high explosives upon the surrounding medium. As a result of this work a mathematical model based on the gener- ally accepted mechanism of blasting has been developed. The mechanism and the resulting model are briefly outlined. IFrom'this model the effects of burden, spacing, blasthole diameter, rock and explosive properties upon fragmentation and heave can be calculated. Using these calculations it is then possible to see how variations in frag Imentation and heave can affect the overall production costs of a mine whether it is surface or underground. The overall costs are made up of a number of individual costs - drilling, blasting, loading, hauling and crushing. ach of these operations influences or is influenced by fragmentation and heave s these costs are inter-related, the

Jan 1, 1975

Since 1958 there have been 16 major coal mine explosions in the U.S. claiming 323 lives. Whilst the exact cause of a number of these incidents has not been determined, the majority has involved gas ignitions in one way or another. In addition there have been fatal gas explosions in salt mines and vapor explosions in oil mines. Furthermore, many of the oil shale mines in the U.S. have proven to be gassy giving cause for concern. Compounding these problems is the fact that frictional ignition of methane in coal mines has dramatically increased over the past several years; over 100 such ignitions were reported in 1979. While, no fatalities have been attributed to frictional ignition in the U.S. since early 1978, a recent mine explosion in Nova Scotia which resulted in 11 fatalities was attributed to a frictional face ignition. Research being conducted at the Bureau of Mines is aimed at the prevention and suppression of gas explosions. Emphasis is placed on new coal cutter bits for reducing ignition frequency, machine-mounted water sprays for preventing frictional face ignitions and automatic devices for quenching incipient ignitions and fully developed gas explosions.

Jan 1, 1981

This paper describes the application of the Total Productive Management (TPM) technique as a performance improvement initiative for a coal mining operation. It discusses the objectives of TPM, with the driver for improved production performance being the Overall Equipment Effectiveness (OEE) of the equipment or process, and with the development of "ownership" as the behavioral approach to equipment management and continuous improvement through cross-functional and area-based teams. It illustrates the concept of equipment management as defects management.The scope for application of TPM to the coal mining industry is immense. The harshness of the operating environment can be a major generator of equipment defects, and a current paradigm in the industry accepts these defects as an unavoidable outcome defining maintenance costs in this environment. However recent benchmarking studies have highlighted that maintenance costs per operating hour in some mining operations are more than double the vendor's estimate of "best practice". The paper refers to these studies which also compare maintenance costs of fixed and mobile plant and equipment to "best practice" outcomes in comparable process industries.

Jan 1, 1998

A BRIEF account of the water-power potentialities of Tasmania is given, together with possible applications of the power commercially. A short history of the Waddamana development is then given, and the main works are described.WATER POWER POTENTIALITIESTasmania is an island of approximately 24,500 sq. miles area (exclusive of small islands). An area of 12,000 sq. miles is at an elevation of over 1000 ft. above sea-level, and of 2300 sq. miles at over 3000 ft. above sea-level. Average annual rainfall varies from' over 140 in. on West Coast to 20 in. on East Coast, and for the whole island averages 48.5 in. The total water-power available, based on conservative figures for run off and efficiency, is 6,000,000 b.h.p. Only a small percentage of this total will, under present conditions, and under likely conditions in the immediate future, be capable of being developed commercially.An extensive hydro-metric and water-power survey is at present being carried out in order to collect information concerning the most promising water-power schemes. Already 400,000 b.h.p. has been located in different proposals, and there is still a large area of very likely country along the West Coast which has not been investigated yet. Tasmania thus has very vast power potentialities, which, combined with good ports and communications and wonderful mineral and timber resources, should augur well for the establishment of the great key industries, particularly chemical and metallurgical.

Jan 1, 1923

By Vidalinc, Raffoux

Longwall faces producing in the order of 20,000 tons per day of raw coal are presently running in the Houilleres du Bassin de Lorraine of Charbonnages de France. Production levels of twice that level pose some technical and economic problems of coal cutting, ventilation, coal and equipment transportation in the.face and from the face to the sur- face. The peak productions of the equipment in use today, the results of trials with new equipment, the utili- sation of forecasting models (some in the form of software), allow us to fo- resee feasable technical solutions to these problems. They will first be considered in the best possible context (thick- ness, dip, non gassy, soft coal, good strata, no faults). This will give. the necessary conditions to reach daily output'of that level. A sensitivity analysis of these- figures to the effective natural con- ditions will then be undertaken and the implication of such a project on health and safety (dust, climate ...) will be carefully considered. A concise technical and econo- mical approach will permit us to fore- cast the economical interferences of such production units and specially the consequences of sudden variations of the output (downtimes, failures, etc). From this investigation, goals for technological development and re- search areas will be outlined to be able to reach this production target in the XXIst century.

Jan 1, 1988

By J Vann

The key functions of project evaluation are to assess potential profitability and to develop an effective operational design. For mining projects, design aspects include mining methodology, ore treatment methodology and production rates. All of these characteristics impact on project economics and overall value. Resource models, which form the ultimate basis of project evaluation, typically consist of tonnes above cut-off, grade above cut-off and the spatial distribution (connectivity) of tonnes/grade above cut-off, for one or more variables. Dilution, ore loss and metallurgical recovery are all modifying factors applied to the resource model during evaluation and determination of profitability. A key issue is: how is the value determined? In addition to traditional combination of in situ tonnes/grade, the following merit serious consideration: the concentration of deleterious elements, throughput rates, mining/processing costs and û importantly û metallurgical recovery. Geometallurgy is an emerging field targeted at integrating these issues by identifying either direct measures or proxies for throughput (hardness, grindability), recovery (liberation, mineral shape/texture, etc) and concentrate quality from easily collected macro-, meso- and microscopic data. These ægeometallurgical variablesÆ drive project costs and revenues in a fundamental way. For geometallurgical characterisation to have a real impact on business design, it must enable improved mine planning. When creating spatial estimates for such variables, it is preferable to find proxies that can be measured as close to the intact rock mass as possible. However, spatial estimation of proxies for geometallurgical properties and responses is complex and requires special consideration. Unlike grades, both proxies and absolute measures of geometallurgical variables are not necessarily linear or additive and therefore require very careful geostatistical consideration. In some cases, models must predict extreme values of geometallurgical attributes rather than averages. Incorrect characterisation of metallurgical recovery/throughput can (and has) led to misspecification of the scale of projects, and thus can be seriously value destructive. Aspects of geometallurgy have long been important in iron, bauxite, manganese and coal deposits and are increasingly on the radar for base and precious metal miners. However, as more metallurgically complex deposits are developed and mining of large-scale, low-grade deposits becomes more commonplace, the importance of characterising the metallurgical response in order to generate properly optimised projects will rapidly increase. It is possible that in many ætraditionalÆ (ie grades and tonnes) reserve models, the variables that drive the project are missing!

Jan 1, 2007

Over the last five years Du Pont (Australia) Ltd has developed a commercial range of new generation emulsion based explosives concurrently with the development of new explosives-placement systems. The paper outlines Du Pont's emulsion technology and history of product development from the initial emulsions (Tovex E & EL) to emulsion/ANFO blends (Tovex BE) through to the most recent development of Du Pont's SOL emulsion component. The paper also outlines the development of materials handling systems on site to load waterproof bulk explosives from the original pumper trucks through to the multipurpose agitator bowl blending and pumping units at the heart of Du Pont's SOL emulsion system currently available within Australia. The last section deals with some of the more important features of enhanced agitator bowl truck designs and outlines examples of the complete SOL emulsion system and methods of operations currently practiced at specific mines within the Bowen Basin coalfields.

Jan 1, 1986

The traditional concept of optimum drill and blast is that it is achieved when ore is produced at the lowest unit cost and, because of the complexities of most mining operations, represents a band which extends either side of an overall cost m

Jan 1, 1998

By Brent A. D, Olsen a. H, Mayfield P. L J, Grazier P. E

Concentrates produced from MnO2 and Fe203 ore fines have been targeted as potential feedstocks for direct metallurgical processing. Prereduction of pyrolusite-rich Mn02 sands to MnO has been investigated in batch and continuous experimental bubbling fluidised beds using CO-H2 reducing gas mixtures. This process has been found to produce a high grade feedstock suitable for smelting to ferroalloys or acid digestion for chemicals production. Similarly, production of highly metallised direct reduced iron (DRI) from hematite ore fines has also been investigated in batch bubbling bed reactors. Programs to characterise the reduction kinetics, fluidisation behaviour and defluidisation phenomena for both feedstocks are currently in progress to enable optimum process conditions to be determined.

Jan 1, 1995

By Perring CS, Vearncombe J. R, Ho SE, Groves DI

Large Late Archaean greenstone belts in Western Australia, Canada and Zimbabwe, contain abundant mesothermal gold, volcanogenic massive base-metal sulphide, and komatiite-associated Ni-Cu mineralization. These greenstone belts are similar in many respects to convergent and accretionary plate margins found in the Pacific rim; modem environments which are cor-respondingly rich in gold and base-metal mineralization. The giant gold placer deposits of the Late Archaean Witwatersrand Basin (the world's largest gold producer) formed in a foreland or retro-arc basin; in a similar tectonic setting to much modem placer mineralization around the Pacific. Gold and volcanogenic base-metal sulphide mineralization are abundant in Late Archaean terranes and the Pacific rim because1. gold mineralization is a product of convergent margin tectonics, and 2. accretion in convergent margin orogens provides the best chance of preserving base-metal mineralization related to submarine volcanism.It is therefore likely that the abundance of gold and base-metal sulphide mineralization in the Late Archaean reflects the widespread growth and sta-bilization of continental crust via tectonic processes broadly similar to those operating in the present Pacific basin.

Jan 1, 1990