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By Hargraves A. J

At 4 MPa gas pres ure and 30°C the sorptive capacity of 10 selected Australian dried coal ranges from 17 to 23 m3/tonne of CH4 and 27 to 36 m3/tonne of CO2. Values for moist coals are about 25 per cent less. At 20°C, sorptive capacities are about 18 per cent greater. No clear relationship between coal rank and sorptive capacity was established.The permeability of coal to gas is dramatically reduced by progressive hydrostatic confinement. No single 'permeability' for a coal can be established because of relative affinities of coals and the gases (Ar, CH4 and CO2) used in experiments. Bedding plane permeability is significantly greater than permeability normal to bedding. Dependent on gas/coal combinations, permeabilities without confinement ranged from 150 to 0.05 millidarcies, and with 8 MPa hydrostatic confinement from 1.0 to 0.001 md. Generally, permeability is increased by reduction in temperature, and reduced by increase in moisture as one changes from Ar through CH4 to CO2. In retrospect, it is preferable to ubject permeability sample to 8 MPa hydrostatic stress only once, because changes occur in the samples and it is difficult to use other gases successively.The initial rate of desorption, DP, does not appear to be a reliable index of proneness to instantaneou outbursts for Australian coals.The methods used for determining quantitative gas-coal properties appear suitable and reliable for testing other coals.

Jan 1, 1985

This report chronicles the historical development of longwall mining in the United States and speculates on future developments to the turn of the century. Five eras of technological development during the modern period are described and analyzed. These eras discuss the development of (1) mechanized extraction, (2) self advancing roof supports, (3) high capacity roof supports, (4) shield supports, and (5) system automation. Current trends are analyzed in terms of: longwall utilization, production capability, support capacity, face widths, and new technological developments. From these analyses, the future of longwall mining to the year 2000 is speculated. It is concluded that longwall mining will continue to grow in importance during the next decade and that the next major technological milestone will be the realization of a fully automated longwall mining system.

Jan 1, 1992

By Mallett CW, Hobbs BE

This study examined the structures of the Bowen Basin in central Queensland, Australia, by a series of lineament analyses. These studies were carried out using published geological maps, NOAA-AVHRR imagery, and LANDSAT MSS. Comparisons between these various data sources allowed the discrimination of the nature of the observed lineament sets and the time of their development. These data, which have been verified by field work, allowed the development of an integrated structural model of the Basin as an area of compression. This is considered in the light of a plate tectonics framework for northeastern Australia. The study showed that geological structures of great significance to mining operations, such as strike slip faults and large thrusts, could be identified and mapped using a combination of satellite imagery and field investigation. The small scale view of the satellite imagery also facilitated the development of a structural model for the Bowen Basin.

Jan 1, 1986

In early-1989, subsidence due to voids at the top of previously filled stopes and stopes awaiting filling,began to threaten the 15 level fill conveyor horizon. This together with the need to maintain production targets meant that a method was required to significantly increase fill placement.Alternative methods of placing dry fill underground were investigated. One option was to drill 200 mm boreholes from surface directly into stopes 600 - 800 metres underground. A drilling program was successfully undertaken, and resulted in the placement of more than 800 000 tonnes of dry aggregate fill via four boreholes.This paper details the drilling program undertaken and discusses the difficulties encountered, the fill placement system and the project costs.

Jan 1, 1992

By Billington WG

A structural study of northwest Fergusson Island, part of the D'Entrecasteaux Group, was undertaken using colour and monochrome aerial photography and Landsat imagery. The resulting interpretation shows an upstanding, in part, dome-like metamorphic core complex, which is bound on three sides by an en echelon series of low-angle, thrust faults. Faceted gneissic layers occur throughout the complex. These facets are triangular in plan view and range in size from a few tens of metres, to massive composite zones which traverse the entire uplifted zone, The lower surface of each of the facets are, in fact, low-angle decollements which, during uplift, slid one upon the other to accommodate the vertical and extensional movements. As a consequence, deep structural valleys developed which widen towards the zone of maximum uplift. In many places, recognisable topographic features are replicated on both sides of these valleys, and under the stereoscope can be visually reconstructed to their original pre break-up positions. The southern margin of the core complex is less dome-like and falls away, via a series of deeply-entrenched structural valleys, towards a volcano-studded lowland. The lowland appears to belong to a rift or arm, stemming from the more southerly located Goodenough Bay Infrabasin.

Jan 1, 1987

By Turner T. M, Jorgensen F. R A

The tendency of the concentrate to ignite was studied using four techniques, namely, laminar flow furnace, fluid bed, thermal analysis and boat-in-furnace. Exothermic activity occurred at two temperatures: minor activity in the vicinity of 200¦C, major activity at 330-350¦C. The low temperature reaction was due to the ignition of a small amount of free sulphur while the major activity was associated with the ignition of the sulphide minerals, notably pyrite. To avoid ignition of the sulphide minerals, the gas temperature should not exceed 300¦C and the oxygen content of the gas phase should be as low as possible. It was shown that little of the arsenic in the concentrate entered the gas phase during drying.

Jan 1, 1987

A combination of highly structured, fissile stope hangingwalls and high ground stresses have caused difficult mining conditions in the Main Lode Deeps at Lancefield Gold Mine. Cyclic reviews of ground support and stoping techniques, coupled with geotechnical investigations, and the application of numerical modelling has led to the successful management of stoping operations.

Jan 1, 1995

By Lockyer PC, Reed MR Bartlett PM

Difficult ground conditions have plagued the underground operations at Mount Windarra since mining started in 1974.The ore at Mount Windarra consists of seven vertically dipping, sub vertically plunging ore shoots. The ore zone in which the shoots lie is characterised by moderate to heavy cleavage and the presence of serpentanite. The ore is known to extend to 1100 metres below surface.Long hole open stoping under cover of backfill has been used as the primary mining method at the mine, but its poor performance brought the mine near to closure in 1984. The mine had been closed from 1979 to 1980.

Jan 1, 1985

By Campbell Brown G F

THE Mount Morgan mine has, from the time of its historical discovery, been the subject of investigation and speculation by geologists and mining engineers. The first examination was made by Dr. R. L. Jack, in 1884. He came to the conclusion, from theevidence then available, that nothing but a thermal spring in the open air-otherwise a geyser-could account for the formation of the ore body. This report attracted world-wide attention at the time. Since then the mine has been examined by most of the leading geologists of Australia, and by many from elsewhere. In all cases the examination has only extended over a period' of a few days or weeks, and in the light of present knowledge of the deposit we know that sufficient data could not be obtained in such a short time to warrant the statement of definite conclusions. It is not to be wondered at, therefore, that a considerable difference of opinion exists as to the genesis of the deposit. That the company considered more detailed investigation necessary is shown by the fact that some thirteen years ago it employed Mr. Charles Walker as geological surveyor on the .mine. At that time also the data available was insufficient to give satisfactory results. It is, however, a matter for comment that none of the geological reports on the property took notice of the increase of copper values in the ore with depth, though the present workings and diamond-drilling...

Jan 1, 1911

By Scherbatsky VB, zon BM, Babushkin NM, Kitaev BI, Shabel&apos

The structure and hydrodynamics of the raceway zone of a blast furnace was studied on a cold model representing a sector containing two tuyeres. The model differed from the usual in that it was prov- ided with continuous flow of the coke layer at pre- determined rates, had provision for changing the tuyere parameters (diameter, protrusion, inclinat- ion) and irrigation of the layer with liquid. A combination probe was developed which per- mitted simultaneous measurement of the pressure field both across the area and through the height of the layer as well as determining the topography of the raceway. The velocity fields in the layer were measured with a specially made impulse thermo- anemometer. The determining criteria of the model were taken as the relationships between the energy of the blast and the particles, the dimensions of the raceway and the cross-section of the tuyere. The model established the effects of the tuy- ere structural parameters, blast parameters and amount of liquid products of smelting on the con- figuration of the raceway, the structure of the layer, pressure and velocity fields in the vicinity of the tuyeres and in the vertical direction through the layer. The properties of the raceway formation and the structure of the layer in motion have been clarified.

Jan 1, 1981

The discovery of economic uranium miner alisation in unique geological conditions at Yeelirrie, 700 km NNE of Perth, presented Western Mining Corporation Limited with a num- ber of sampling and evaluation problems. Carn- otite mineralisation occurred in a porous cal- crete-clay lithology in close proximity to the water table; background information on such a deposit was non-existent and sampling in these conditions could be difficult. The deposit was sampled initially by aug- er drilling with X-ray fluorescence analysis of drill cuttings, followed by reverse circulation and diamond drilling with analyses by X-ray fluorescence and gamma logging of the holes. Two costeans provided lithological and grade distribution data and mining experience in the deposit. Spoil from the costeans was stockpiled according to location in the first costean and according to location and grade in the second costean. Samples from the various stockpiles were analysed by X-ray fluorescence. No. 1 costean was extensively sampled by channel sampling of the walls and by pit sampling of the floor of the benches of the costean by back hoe. No. 2 costean was sampled by Geiger counters mounted in T-probes and by the gamma logging of auger holes to establish the valid- ity of the T-probe results. Samples were taken

Jan 1, 1976

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

By Whincup P

Hilton deposit comprises en-echelon silver-lead-zinc orebodies with reserves in excess of 50 million tonnes. The host rock to the ore is a dolomitic and pyritic shale/siltstone which dips steeply west. The shale/siltstone is deeply leached and porous, particularly over the Ore Zone where the depth of leaching continues down to 440 m below surface, and constitutes an extensive permeable aquifer system containing a large volume of saline acidic groundwater. Initial production commenced at Hilton in 1987 well below the aquifer. A dedicated dewatering and monitoring programme is in place to ensure security of stoping operations and allow extraction of ore close to the leached zone in future years. Dewatering is undertaken from controlled bores from underground sites. Mine groundwater discharge is presently at the rate of 4000 kl/day with plans to increase to 8000 kl/day. An additional 2000 kl/day of fill and service water and water from secondary aquifers is also pumped from the mine daily. Although recharge rate to the aquifer is minimal, studies indicate that due to the size of the aquifer and future extensions to mine development, dewatering will be a life of mine activity. The investigations which have been undertaken to determine optimum dewatering techniques and schedules are described. These include production bore tests, mine planning constraints and computer aquifer modelling. Gravity geophysical techniques have been successful in delineating the lateral and vertical disposition of the aquifer. The mine dewatering schedule, whose principal component is underground mine drainage, is also outlined.

Jan 1, 1988

By Sorentino C

Mineral valuation may appear to be a special field of financial valuation when in fact it is a subset of general investment decision theory. The only significant difference in mineral valuation is that in the case of valuing an on-going mineral asset, ie a mine, often there is no initial capital outlay involved. One is required to determine what the mineral asset as it stands is worth. But this is the same problem as determining the maximum one could pay today and not incur a loss over the life of the asset. In other words one needs to determine the Net Present Value (NPV) of the asset. The two most widely used discounted cash flow methods, NPV and Internal Rate of Return (IRR) came of age with the rapid adoption of the personal computer and spreadsheet programs. The two methods are directly related as the IRR is a special case of NPV. NPV measures the absolute increase in real wealth that can be expected from a certain investment, which makes it particularly suitable for mineral asset valuation, but ignores the efficiency of the investment. In contrast, IRR gives the expected efficiency of the investment but ignores the increase in wealth aspect. IRR has two serious theoretical weaknesses; multiple IRR's and a very rigid assumption about the rate of return of reinvested proceeds, plus if no initial equity expenditure is involved there is no IRR. The choice of the ""hurdle"" rate can also be a problem and in certain circumstances one can obtain different rankings of mutually exclusive projects using IRR and NPV. Although NPV and IRR supposedly measure financial risk, in fact they only address a very narrow area of risk, namely the time value of money given the real discount rate. They side step the issue of what the real discount rate should be and varying degrees of risk. The classical way to establish the real discount rate is to use the weighted average cost of capital.

Jan 1, 1994

By Mistra M, Hu JS, Wadsworth ME

The fluorite/oleate system has been studied extensively since the begin- nings of flotation research. The well-defined relatively simple crystal structure of fluorite and its ionic bonding make it a model system for study. Our understanding of fluorite/ oleate flotation chemistry continues to grow but as yet remains incomplete. Besides a review of our understanding of this system, recent findings are presented in this paper, and new research horizons are identified.

Jan 1, 1984

By O Aydan, R Ulusay

Blasting is the most commonly used excavation technique in mining and civil engineering applications. Blasting induces strong ground motions and fracturing of rock mass in rock excavations. Particularly, high ground motions may also induce some instability problems of rock mass and structures nearby. Furthermore, it may cause some environmental problems due to noise as well as vibrations of structures near the populated areas. Furthermore, flyrocks is another major issue for the safety of people and damage to machinery and equipments when blasting is employed. In this study, the authors explore the ways how to estimate the ground motions as a function of distance, amount of explosive, number of holes. The ground motions were measured by stand-alone accelerometers developed by the first author and some empirical relations are developed. The effect of ground motions on the instability issues of benches such as sliding, toppling and rockfalls were investigated. Furthermore, the flyrock issue is investigated and some empirical relations to estimate the maximum distance of flyrocks from the blasting relations are compared and discussed. CITATION:Aydan, O and Ulusay, R, 2018. The ground motions induced by blasting in open pit lignite mines and its environmental effects, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 142–151 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

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

The long continuing controversy over the Origin of fusain, whether it is a product of primeval forest fires, or of special conditions of weathering (including bacterial decay) of the vegetal debris concerned prior to, burial, has now been extended, to include the possibility that fusain is a product of the coalifaction process subsequent to deposition, so that doubt may reach even to its time of formation.The conflicting views on this point are summarised in the following quotations from two recent publications (my italics in each quotation):1. "Recent observations made in peat and brown coal deposits in Australia, England and Germany strongly suggest that practically all fusain is formed by coalifaction after deposition and 'preliminary compression. In deposits of advanced brown coal rank, it normally takes the shape of pieces of wood compressed parallel to the bedding plane; and some fragments consisting partly of fusain and partly of vitrain exhibit the same amount of compression throughout. This would seem to indicate fusinisation after burial, as hard brittle charcoal would be crushed, or else retain its original irregular shape if strong enough to withstand pressure.In some immature deposits, however, where cover is of a hydrostatic nature rather than a vertical compressionar force, occasional pieces of fusinised wood showing very little flattening are present, but such immature deposits seldom contain the proportion of fusain found in higher rank coals. In view of this, and the possibility of introduction of charcoal into peat deposits, it is felt that a small amount of the fusain in coal may represent wood charred before burial, but most of it almost certaInly originated as a product of fusinisation after burial" (Dulhunty, 1948, p.14).

Jan 1, 1953

By Mosusu N

Geothermal anomalies of different types occur within distinct geological/structural settings in Papua New Guinea. According to R.F. Herring, geothermal occurrences in Papua New Guinea can be classified into two types, those related to vulcanism (Lihir, Rabaul and other series of islands along the volcanic arc) and those resulting from a regional heat flow probably caused by radiogenic sources, for instance those in the Wau/Bulolo area. The manifestation of this potential source of energy generally coincides with either converging or diverging tectonic plate boundaries. Previous inventories on thermal waters were carried out by vulcanologists from the Rabaul Observatory in the early 1960s. However, these studies rarely included chemical analyses of water and gas emissions and the investigations were carried out in an ad hoc manner, generally as a secondary activity. The most recent investigation on thermal waters was conducted on Lihir Island in connection with the development of the open pit gold mine. These studies included detailed exploratory drilling to a maximum depth of 730 m, and a water chemistry isotopic sampling and analysis programme. The hydrothermal waters were not considered as an energy source but as a hazard during the development stage of the mine. Nevertheless, the geothermal anomaly observed at Lihir includes hot springs emerging along the coastal zones with temperatures that approach 100¦C, steam, and thermal borehole waters with temperatures that exceed 200¦C. Chemical analysis results of thermal fluids from Rabaul, Talasea and other areas in Papua New Guinea generally show high total dissolved solids and low pH. In contrast, recent results from the deepest and hottest thermal source at Lihir shows a neutral pH, a Na-CI-SO4 composition and temperatures above 200¦C. Despite the concentration of chloride being similar to that of sea water, other chemical results and stable hydrogen and oxygen isotopic compositions of thermal fluids imply the source to be mixture of local meteoric water and deep thermal water rather than sea water. Results of geothermal modelling suggests that the total geothermal uptlow is equivalent to 54 MW.

Jan 1, 1997

By D Craw

Interactions between structure and lithology in the Hyde-Macraes Shear Zone controlled the style of gold mineralisation at the Macraes mine. Large volumes of rock in some mine pits have most gold disseminated in hydrothermally altered schist, rather than in quartz veins. Mineralisation was initiated in the latter stages of metamorphism. Pods of massive schist rich in quartz and feldspar are surrounded by more fissile schist consisting of interlayered micaceous and quartzofeldspathic schist. Later shears have been partly controlled by the micaceous schist, and anastomose around pods of more massive schist. Micaceous schist was replaced by pyrite and arsenopyrite, accompanied by recrystallisation of phengitic muscovite under lower greenschist facies conditions. Gold occurs in sulfides and with microcrystalline quartz formed during minor silicification. Massive schist is locally mineralised along sulfidic microshears which have phengitic muscovite largely illitised under sub-greenschist facies conditions. Mineralised massive and micaceous schists were overprinted by cataclastic shears, with addition of graphite and more sulfides. Mineralisation occurred during a transition from ductile to brittle deformation regimes as the schist was uplifted in the late Jurassic.

Jan 1, 2004