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A non-contacting under-belt capacitance and gamma-ray backscatter technique has been developed for the on-line measurement of moisture in coal. In this technique, moisture was correlated with radio frequency susceptance and conductance determined using an under-belt capacitance sensor in which a fringing electric field Interrogates a layer of coal on the conveyor belt directly above the sensor. To compensate for variations in the density and thickness of the coal layer, an under-belt gamma-ray backscatter gauge was used to measure an equivalent volume of coal.A plant trial of the technique was conducted at Stockton Borehole Colliery, SW Australia, where the gauges were installed on the coking coal product conveyor. Product moistures, in the range 7 - 14%, were determined with r.m.s errors of 0.50 and 0.25 wt% using on-belt and static off-belt gauges, respectively. The difference in the on-belt and off-belt gauge measurement accuracy was attributed to sampling errors in the calibration of the onbelt gauge.

Jan 1, 1989

By Liu Q, Siefken T. C, Misra V. N

The bubble size was measured in a laboratory flotation column. The effect of variables such as air flowrate, frother dosage and type, pulp density, particle size and water column height on the bubble size was investigated. The results show that an increase in either air flowrate or pulp density cause the bubble size to increase, while increases in water column height, frother dosage, surface tension or solid particle size cause the bubble size to reduce. Among the frother types tested, MIBC was found to be the most effective in reducing the bubble size.

Jan 1, 1992

By Maconochie A. P

The copper-gold orebodies of the Ok Tedi project and located in an area of climatic and topographic extremes, where both the landforms and the rocks from which they have developed are so young that it may be said that geological and engineering processes are coincident.

Jan 1, 1990

By Tsuchiya N, Takada Y, Okabe K

Alkalis in the blast furnace are removed mainly by the slag, Alkali removal by the slag was studied as a rate process of alkali vapor- ization from the slag flowing through the dropping zone in the blast furnace. The vapor-, ization rate of I:20 from CaO-Si02-A1203 IZ20 slag was- measured under various experimental conditions. An empirical formula for the vaporization rate was obtained as a function of slag basicity, temperature and surface area per unit mass of slag. A simulation model of IC20 vaporization in the dropping zone was evaluated using the rate equation when the true velocity and surface area of the slag was de- termined from a flow dynamic model of counter- current gas-liquid flow through packed beds. The influence of the dynamic conditions of flow, as well as the slag basicity and temperature, on alkali removal by the slag was estimated.

Jan 1, 1980

By Grey D, Turner R, Capsanis J

Coal fines are recognised to have a major impact on the cost and efficiency of the recovery of saleable coal. Fines affect the productivity of the whole mining cycle because of the low yields obtained in washing this material as well as affecting the moisture content and handling characteristics of the final product.In 1990, Coal and Allied Hunter Valley Mine initiated an internal study into coal fines based on the assumption that a reduction in fine coal in ROM material will lead to increase yields in the preparation plant. The initial results of this study indicated that the level of fines in the ROM coal can be reduced by more than 40 per cent by simple changes in blast design and implementation.

Jan 1, 1992

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

Based on twenty years of experiences of applying computers in mine water engineering in Hungary, a program package was developed for home utilization and for other users abroad as well. This program package has been adapted to the CAD System of Coal Mining of COMECON countries. The main features of the "mine water subsystem" in the CAD System of Coal Mining and short descriptions of the key programs of the package are presented in this paper. Foreword The serious water problems of Hungarian mining pressed and/or stimulated its professionals to apply computers for supporting their problem-solutions. The first trials of these computer applications in mine water engineering were dated from the sixties. Owing to its twenty years of experiences in computer appli- cations in mine water engineering the Central Institute for the Development of Mining in Hungary was requested to work out the "Subsystem of Mine Water" for the Computer Aided Design System ('CAD) of Coal Mines in COMECON countries. This paper gives a brief presentation on the main features of this "subsystem"with reference to significant components.

Jan 1, 1988

By Lacy JC

Human habitation of the Pacific Rim began when mankind began migrations out of its place of origin in the Rift Valley of Central Africa c. 4million years ago. This migration was erratic and largely controlled by advances and retreat of the various Ice Ages which, while limiting advances in areas of intense cold, at the same time aided migration thro-ugh the creation of land bridges as ocean levels declined during periods of glacial advance (Fig.l).Mankind began its trek to the Pacific from Africa across India then north into southern China and south into Indonesia (Fig.2). In part, these migrations stimulated early technological develop-ments to fulfill needs and adapt to environmental conditions; thus, these nomads developed stone and bone tools, animal skin clothing and the use of caves and other simple shelters. The earliest evid-ence of mankind's use of fire can be found at Zhou-koudaian near Beijing, c.400,000 BP.From China, the completion of the Pacific Rim's population can be attributed to the last Ice Age that dropped the ocean level by more than 300 feet and created land bridges about 40,000 BP allowing migration across the Bering Strait into Alaska and to Australia from Indonesia. The American migration reached Mexico about 30,000 BP, and by 6000 BP the occupancy of the Pacific Rim was complete when the first human settlers reached the southern tip of Chile.

Jan 1, 1990

By Ryan CG, Both RA, Mernagh TP, Large RR, Hunns SR, Gemmell JB

The Hellyer and Mt. Chalmers deposits are mound-style volcanic-hosted massive sulphide (VHMS) deposits in Australia. Textural, petrographic and microthermometric investigations of fluid inclusions in the Hellyer stringer system indicate that Type I, primary, liquid-vapour inclusions are 10-15 pm in size, and yield homogenisation temperatures of 170-220¦C in early 2A veins, 165-322¦C in main-stage 2B veins and 190-256¦C in late-stage 2C veins. These data suggest a waxing and waning thermal history. However, the average salinity remained between 8-11 NaCl equiv. wt % in all Stage 2 veins. At Mt. Chalmers, Type I inclusions up to 20 ¦m are found in quartz from the mineralised zone, and these inclusions yielded homogenisation temperatures of 160-268¦C and salinities of 5-8 NaCl equiv. wt %. Laser Raman spectroscopic (LRS) analysis indicates the presence of CO2 (

Jan 1, 1995

By Mutmansky J. M, Hartman H. L

Multiple operating points for mine fans are a problem that fan and mining engineers must constantly be aware of in mine/fan systems. In a single-fan system, unstable conditions can be avoided by restricting fan operation to the "normal operating range." When mine fans are operated in parallel, the situation becomes a little more complicated. Multiple operating points are more often encountered and the fan user must be aware of these multiple points to have a suitable set of operating conditions. However, for fans in parallel, the engineer can plot the combined characteristic in a relatively straightforward manner and thus can avoid conditions that would cause instability in the mine/fan system.

Jan 1, 1988

By Eggins SM, Crawford AJ, Maillet P

The Fiji Islands are remnants of a once continuous Solomon-Vanuatu-Fiji-Tonga volcanic arc (the Vitiaz arc), located at the boundary between the Indian-Australian and Pacific plates. They record a history of (i) arc volcanism the late Eocene to late Miocene, (ii) an extensive magmatic response to arc rifting (5.5-3.OMa) during which volcanism was dominated by shoshonitic to tholeiitic basalts, and as rifting continued, (iii) a transition from arc to intraplate volcanism. The Hunter Ridge-Hunter Fracture Zone separates the inactive South Fiji Basin from the actively spreading North Fiji Basin, and has been considered to be a transform zone, almost parallel to the motion vector of the Australian plate. However rocks dredged during the 1993 `Alize' cruise, from along the northern part of the Hunter Ridge are typical arc tholeiites, and therefore demand that subduction has occurred beneath the Hunter Ridge sometime during the last û 5Ma.

Jan 1, 1995

The introduction of rubber tyred diesel equipment underground in the early 1960's and subsequent design improvements to diesel haulage systems over the past 2 decades has meant that diesel truck haulage has often been the first choice when selecting a haulage system for a new underground mine. Even today only 9% of all vehicles underground are electric powered.However, with the development of more efficient electric haulage systems, the suc-cessful installation of low cost shaft hoisting systems and improvements in conveyor design, alternative haulage systems are appearing as viable alternatives to diesel truck hauling. In particular, the aspects of ergonomic and environmental operating conditions, maintenance and operating costs as well as productivity rates are becoming more and more important in the selection of underground haulage systems. Future develop-ment of existing diesel haulage systems will require that diesel haulage units become more productive, have considerably reduced exhaust emissions compared to existing units and remain the cheapest haulage method for under-ground one way haul distances up to a distance of 3 kilometres. Development of electric truck and associated fuel cell haulage systems

Jan 1, 1985

By McNay L. M

Two field studies to monitor fill pres sures and vein-wall deformation were conducted in mines of the Coeur d'Alene mining district in Idaho. Both operations employed cut-and-fill mining techniques in nearly vertical veins aver- aging 10 feet in width, and backfilled with classified mill tailings. Hydraulic pressure cells were used to measure transverse, longitudinal, and vertical pressures within the backfilled stopes. Rock bolts extending into the manways and mechanical closure devices were used to monitor vein-wall convergence. Continuous recorders were used with selected pressure cells to prolong the life of the installation. Transverse pressures in excess of 600 psi and stope wall closure up to 22 inches were re- corded. Closure rates were higher at midheight of the stope than they were near either sill, indicating that the vein walls react similarly to a beam supported on each end.

Jan 1, 1973

By Jay W. H, Brown L. J

Several case studies are examined in which analysis of treated ores and extracted metal species by Mossbauer spectroscopy provides information not available by other competing techniques. The cases include poorly crystalline, surface iron oxides in titanium minerals and chalcopyrite, gold in ores and bacterially oxidised ores and the adsorbed species from gold extracted from cyanide and chloride solutions onto activated carbon and polyurethane foams. Some limitations on the use of the technique in terms of sample size, sensitivity and counting time are also discussed.

Jan 1, 1997

By Fourney W. L, Dick R. D

A small-charge rapid excavation system employing a novel penetrating cone fracture initiation and propagation technique has been demonstrated to be capable of excavating the hardest of rocks at efficiencies (energy per unit volume of rock removed) four to ten times greater than attainable with conventional drill and blast. Significant enhancements to the concept developed during the research efforts include the use of propellant rather than explosive charges and a device for containing the charges and effectively sealing the shot-holes. The experimental results, including the excavation of several tons of hard rock in a research mine, have confirmed the novel breakage process and provided a data base for the design of a continuous hard rock mining machine based upon the concept. The small-charge excavation system would be attractive for civil construc-tion operations where sensitive structures, equipment and personnel would be in close proximity to the excavation face. The system would be attractive for selective mining operations where the ore rock could be fragment-ed and processed separately from the barren country rock. The barren rock could then be backfilled underground and eliminated from the traditional hauling and milling operations.

Jan 1, 1990

By Mackinnon I. D R, Glikson M

Samples from the Callide Coal Measures, Queensland, Australia, containing the minor maceral, micrinite, have been studied using optical and electron-optical techniques to determine the precise compositional and structural nature of micrinite when in association with vitrinite macerals. Emphasis has been placed on direct spatial correlation of optical and electron-optical data due to the fine grain size (90 per cent of the component) and, as such, should not be considered a maceral.

Jan 1, 1991

By Casale G

This paper discusses a long range mine plan development at the Santa Fe Pacific Gold Twin Creeks Mine based on the reserves of Mega pit. The key constraints of the schedule development included two types of mill ore targets (sulphide and oxide mill ore), consideration of blending of six chemical constituents (sulphide sulphur, carbonate, organic carbon, the ratio of iron/[arsenic, antimony]), and mining of acid generating and acid neutralizing waste at pre-defined proportions. Solution approaches, selected results, and project experiences are discussed.

Jan 1, 1995

By Benson R. P

Building a new tunnel to accommodate CN North America's needs or double stacked container traffic for the next 100 years represents new and unprecedented challenges. Innovative approaches to contracting, especially the Negotiated Compressed Process (NCP), TBM design, project management, and the regulatory and approval process, were all required to deliver a new tunnel to meet the needs of CN North America within the approved completion schedule of 33 months compared to a traditional approach of 45 to 48 months. The NCP resulted in trimming a full 12 months from the project schedule with an anticipated saving of direct and indirect costs.

Jan 1, 1993

By Allchurch P. D

At Perseverance a reserve of 45 million tonnes at 2% Ni was indicated by drilling. Holes were drilled in trellis pattern on section lines 61m apart to assess shallow mineralization. To explore at depth holes were spaced 122m apart, collared vertically, then allowed to deflect under controlled drilling conditions. The mineralization may be divided into the three homogeneous classes of soarsely disseminated, heavily dissem- inated and massive sulphides. In the standardised sampling and assaying procedures used to assess the deposit, attention was always paid to these fundamental ore types. All sampling and assaying processes were continuously monitored by checks. Sampling and sample preparation errors were small, to judge from the differences between results of original and check samples. Assaying errors, determined from analyses made by independent laboratories using different methods, slightly exceeded sampling errors. Comparison of underground core, c'iannel, and grab sampling, suggests that core sampling tends to undervalue.

Jan 1, 1976

By Eddy B. W, Washusen J. A, Wulff R. T

The State Electricity Commission of Victoria (SECV) has been con- tinuously involved in the extraction of brown coal from open cut mines in Victoria's Latrobe Valley for over 60 years, but have not completed a major mine. Detailed consideration for rehabilitation at this stage has only been able to be given to overburden disposal areas. Increasing interest in rehabilitation in the 1980's led the SECV to review its existing policies and practices and to embark in 1985 on a public consultation process to establish an agreed and accepted policy. This was extended in 1986 to the consultation process for the rehabilitation planning for the Mor- well Open Cut External Overburden Dump. This paper covers the con- sultative process developed and the lessons learned by the participants.

Jan 1, 1989