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At the Highway gold deposit, 37 kilometres south of Charters Towers, gold mineralisation occurs in several stratiform layers and is enriched near the surface by lateritic weathering. The host rocks of the mineralisation are ferruginous and baritic, intensely sericitised, kaolinised and silicified rhyolitic tuffs and pyroclastics of the Cambrian-Ordovician Mount Windsor Volcanics. The geology of the deposit is illustrated in Figures 1 and 2.Forty-six reverse circulation percussion drill holes were completed by North-Queensland Resources N.L. for a total of 2,093 metres of drilling to further outline and test the open pit resource. The drilling indicated a resource of 171,000 tonnes averaging 4.4 grams per tonne gold and 5.0 grams per tonne silver.A shallow initial pit, approximately 30 metres deep, has been designed to mine the high grade upper portion of the western stratiform layer and part of the eastern layer. This initial pit is designed to mine 45,400 tonnes of western mineralisation at an average grade of 7.84 grams per tonne gold and 22,200 tonnes of eastern mineralisation at an average grade of 1.42 grams per tonne gold. Waste is estimated at 110,900 tonnes.

Jan 1, 1986

By Jefferson CW

Middle-to-Late Proterozoic stratigraphy and metallogeny in the eastern part of the Canadian Cordillera and in South Australia are strikingly similar. In both areas, thick, predominantly shallow-water strata and their contained mineral deposits can be divided into three sequences (A, B, C) that record episodic and prolonged continental rifting. It is proposed that Adelaidean strata of Australia were deposited adjacent to Belt-Purcell, Mackenzie Mountains and Windermere strata of the Canadian Cordillera within an epicontinental trough of a "Hudsonia" regacontinent. With the final rifting of this trough, the paleo-Pacific ocean was born. By Early Cambrian time, Australia- Antarctica was on the trailing "east" side of the nascent megacontinent, Gondwana, and was being modified on the "west" by accretion in the Pan-African event. North America, more or less surrounded by trailing edges at this time, was analogous to the Cenozoic African plate. This hypothesis accommodates the available paleomagnetic and radiometric data. It has implications for pre-Pangean plate tectonics, paleogeography, and the predictive metallogeny of both areas.

Jan 1, 1987

By Etheride MA

The evolution of economic precious metal and copper-gold deposits in high-level igneous terranes is dependent on very efficient fluid focussing. This is most readily achieved by contemporaneous deformation, igneous intrusion and hydrothermal activity. Mineralisation in these environments generally occurs in fault and fault-vein arrays developed in the cover sedimentary and volcanics sequences above older regional scale fault systems. Such reactivated fault systems an particularly prone to developing the complex fracture arrays, extreme local dilation and dramatic increases in permcahilit} that are necessary to efficiently focus hydrothermal fluid and produce large mineral deposits.

Jan 1, 1995

By Thompson AG, Cadby GW

The New Austrian Tunnelling Method (NATM) is a proven concept for the safe and economic construction of underground facilities. This is especially true for tunnelling activity where changing ground conditions are often encountered. However, the principles central to the NATM have gained only limited use within Australia, presumably due to the measurement process inter- fering with tunnel driving and the cost associated with instrumentation and interpre- tation expertise. The design and operating principles of two basic instruments are explained together with laboratory simulated test results and suggest- ions for use in an integrated NATM style approach to underground excavation and construc- tion. The two instruments monitor load in rock reinforcement and deformation in rock or primary and secondary linings. The instruments may be fitted with a miniature display module which outputs the measured parameter in engineering units directly. The design of the sensing components allows the instruments to be installed in various configurations suitable for routine performance monitoring, quality control, support element testing or detailed investigations. The display module which reduces the need for instrumenta- tion expertise should suit contractors and allow performance data to be obtained which quickly may be used to modify support procedures to suit ground conditions. When complemented by convergence measurements the devices enable most facets of the NATM to be implemented.

Jan 1, 1987

In the search for significant new economic base-metal resources within Australia during the early 1970s BHP's Exploration Department had observed that the majority of lead and zinc con- centrate production in Europe and the USA came from carbonate- hosted Mississippi-Valley-type (MVT) zinc-lead deposits, but Aus- tralia had no history of production from this class of deposit despite several very favourable geological environments, par- ticularly in the large Palaeozoic sedimentary basins. An exploration-research team was established in 1975 and the Lennard Shelf region, near Fitzroy Crossing, was selected as a most promising geological environment. Previous exploration for this class of deposit by other companies in Australia had largely used conventional exploration philosophies (geological mapping, geophysics and geochemistry to identify specific drill targets) but BHP sought specialist advice from a North American expert and adopted a grid-drilling philosophy, which involved wide spaced relatively deep diamond drill holes on a regular grid pattern, and statistical evaluation of the results. This technique resulted in the discovery of the Blendevale Deposit in 1978 in an area which had previously been explored by other companies using conventional methodologies. The deposit was delineated and a pre-feasibility study carried out in 1985 indicated that the resource of 20 Mt @ 8.3% Zn, 2.5% Pb was a marginal proposition.

Jan 1, 1988

MERLIN, the Queensland Department of Minerals and Energy's corporate geographic information system, provides ready access to all georeferenced data held by the department. Its aim is to provide a consistent, current, statewide coverage of timely information to assist in tenures management, exploration targeting and competing land use decision-making. Initially developed in 1988 and under continual enhancement since then, its functionality is the result of on-going close consultation with a wide range of departmental clients and potential users. A true geographic information system, MERLIN maintains both graphical data with linked textual information on a wide range of features of interest. The proprietary software products Arclnfo and Oracle are used to hold the graphics and attribute information respectively. Access to information is provided by a specially designed graphical user interface programed in-house. Hardcopy output of graphics displays including related attribute data as well as detailed reports of textual information can be retrieved at any departmental office. MERLIN is a network of computer systems which link each of the Department's regional offices and head office in Brisbane. The current state of exploration and mining is maintained by departmental officers processing tenure applications, transactions and dealings directly into the system. Data entered at regional offices are transferred overnight to head office to up-date central records and maintain a currency of data statewide as at the close of business the previous day. Through MERLIN the Department of Minerals and Energy now offers a much streamlined tenures management service as well as access to information about past exploration and mining, Queensland's mineral and energy occurrences and resources, and up-to-date information on the state's geology including maps, boreholes, geophysical surveys and field observations. In the future, this Geographic Information system will be invaluable to the mining industry in the development of mining projects.

Jan 1, 1995

By Fulton B, Stewart R, Leach T

Gold mineralisation at Porgera is inferred to have been derived from a deep differentiated magmatic source which is capped by a series of (now tilted) inward dipping sills and stocks, which comprise the Porgera Intrusive Complex. An arc normal transfer structure provides a conduit, at the intersection with an arc parallel structure, into which basic magma derived from the deep melting of mantle material has been emplaced. Two phases of mineralisation display an association with late stage feldspar porphyry intrusives. Stage I carbonate-base metal-style gold mineralisation occurs as early quartz-sericite, then massive sulphide and late zoned Mn-Fe-Mg-Ca carbonate vein/breccias. Magmatic fluids derived from the deep magma source, are interpreted to have migrated along the margin of a feeder stock to the sills, and south to Waruwari. Stage II epithermal Au-Ag quartz-style gold mineralisation occurs as early fluidised breccias and carbonate veining, followed by zoned quartz-roscoelite-carbonate-gold vein/breccias, and late carbonate and/or sulphate open space infill. Magmatic fluids are interpreted to have utilised the same plumbing system as the late stage feldspar porphyry intrusive, and then migrated into the Roamane Fault which was dilated by; dextral rotation on elements of the transfer structure, normal faulting, and refraction around the competent footwall hornblende diorite. Bonanza gold is localised in a jog in the Roamane Fault, hangingwall splits and at intersections with cross structures. Bulk low grade Stage I gold has been deposited by the mixing of magmatic fluids with cool gas condensate waters, whereas high grade Stage II gold mineralisation resulted from the rapid quenching of mineralised magmatic fluids by oxygenated groundwaters.

Jan 1, 1995

By La Brooy S R, Fenton K

A low grade copper flotation tailing from Telfer containing 1.2% Cu as chalcocite and cuprite and 5 gt-t Au was leached with ammonia, cyanide and ammonia-cyanide mixtures to extract copper and/or gold. Direct cyanidation extracted both copper and gold but consumed about 30 kgt 1 NaCN. Pre-leaching the tailing with an aerated ammonia solution containing 28 kgt 1NH3 and 17 kgtl(NHa)2S0a at pH 10 readily extracted up to 95% Cu in about 6 hours under optimum conditions. However pH and total ammonia concentration were critical factors. Subsequent cyanidation ex- tracted 80% Au using 6 kgt NNaCN. Ammonia-cyanide mixtures werefound to selectively leach gold over copper depending on the concentration and relative proportion of NH3 and CN. The best composition for leaching up to 80% Au from Teller tailing was 1.6 kgt t NaCN and 1.1 kgf 1 NH3 in the presence of 0.3 kgt t Cue+. Such a mixture left only 50 mgL-1Cu in the final solution after precipitation of some of the initially dissolved copper.

Jan 1, 1991

In order to satisfy environmental and mine operational requirements it is becoming increasingly important to minimise ground blast vibrations at certain locations. These locations are often in soil or on large resonant structures such as grain silos, highway bridges or even the walls of an open pit. A soil monitoring exercise was carried out to evaluate the common practice of coupling vibration detectors to the ground using spikes. At a series of locations in an operating quarry the spiked array response to single blastholes was compared with that of an accelerometer array attached to a calibrated embedded mount. The results clearly showed that the spiked arrays over-estimated the true ground vibration by 46.5 per cent on average, with a maximum observed error of 99.2 per cent. These errors are considered too large for compliance monitoring where accurate vibration levels are required for comparison with prescribed limits. Although spike coupling is convenient, its use for compliance monitoring should be viewed with caution. Unfortunately, however, many manufacturers supply their detectors as spiked arrays. A structural monitoring exercise was also carried out to evaluate the vibration response of a grain silo, highway bridge and a pit wall to the initiation of single blastholes. In this case accelerometers and standard geophones were firmly attached to the bridge which resonated at low frequencies. The results clearly show that, due to their limited low-frequency response, the geophones typically measured only half the true vibration level as measured by the accelerometers.

Jan 1, 1995

By Johnson N. W, Quast K. B

Over the years there have been occasional references in the literature to the activating effect of cyanide in galena flotation with xanthates. These have usually been associated with the processing of lead-zinc or copper-lead-zinc ores. Bubble contact curves for the pure galena-xanthate system show a flotation edge at pH 10.4 independent of sodium cyanide concentration which was thought due to hydroxyl ion, not cyanide ion.Flotation tests were conducted on samples of Mount Isa lead-zinc ore using varying concentrations of sodium ethyl xanthate and sodium cyanide. At low collector concentrations, galena recovery kinetics improved with sodium cyanide addition, and the higher the cyanide concentration, the higher the galena recovery rate. At higher collector concentrations, galena recovery rate was independent of sodium cyanide addition.For a given collector addition, the lead grade-recovery curve shifted to an improved position with increasing sodium cyanide level. For the same recovery there was an increase in the lead grade with increased sodium cyanide addition, and this increase was most dramatic at high sodium cyanide concentrations.The presence of sodium cyanide during the grinding of Mount Isa ore caused surface passivation of the iron sulphides and possibly the sphalerite.These sulphides, therefore, reacted with less of the oxygen present in the pulp, hence more oxygen was directed to the surface of the galena. This resulted in an enhancement in the total amount of xanthate adsorbed on the galena that is reflected in the improved flotation response of that mineral.

Jan 1, 1990

In 1972, metallurgical testwork on Renison ore indicated a significant proportion of low specific gravity, tin-barren material ideally suited to heavy medium separation (HMS). Further technical and financial studies provided adequate economic justification and in December 1974 the Renison HMS plant was cannissioned. Initial operations were interrupted by the imposition of tin production quotas for three months in 1976; they were also beset with difficulties particularly with regard to mechanical wear. During the first two operating years much develognent work was carried out including installation of a pyrrhotite flotation bank in the medium recovery circuit, investigations into various wear-resistant materials and the use of atanised rather than milled ferro-silicon. By 1977/78 financial year satisfactory performance had been achieved and since then the average floats rejection has been 18.8% of the total ore treated with an associated tin loss of 2.96%. Developnent has nevertheless continued during the last three years, principal modifications being the installation of larger aperture desliming screens and improvements to the overdense cyclone circuit.

Jan 1, 1978

This paper briefly discusses the negotia- tion of the more important provisions in agree- ments for exploration and mining rights with Pacific countries. LAND RIGHTS Land rights are complicated and sometimes controversial in many of the Pacific countries. In some countries, a company will have to deal with land owners directly; in others, the government will act as intermediary. Inevit- ably, a company will have to deal with both. Mining companies need to be sensitive to the culture and particular interests of the land owners and of their history in defending their rights. The issues are too complicated to be dealt with here. Some mining companies have spent, and will continue to spend, considerable time trying to understand them. It will " require patience, perseverance, sensitivity and unflagging optimism. The better advised companies will ensure that their local repre- sentatives get to know the land owners, under- stand their concerns, and will pursue a policy of keeping them informed on a regular basis of all of the company's activities and proposed activities. Good community relations are the keystone for good mining operations in the Pacific. Most countries will require the submission of an environmental impact statement so that they will know in advance what effects a pro- posted mining operation are expected to have on the environment and how it is intended to deal with them. They will also want to approve the company's environmental reclamation and rehabilitation plan. Let's face facts right away - mining, by its very nature, is not going to improve the environment. There will be waste discharges, emissions and deposits. They will affect the land, air and water and hence human, marine and animal life and vegetation. There will be sounds and odours and the esthetics of mining operations, though perhaps pleasing to geolo- gists and mining engineers, will not please Others.

Jan 1, 1987

By Dyne GD

From experience in the design and operation of power station combustion facilities in most mainland Australian States, involving a wide range of black coals and lignites, and in the specification and procurement of coal supplies for power station use, techniques for the optimisation of coal resource development and power generation utilisation have been developed to ensure compatibility between characteristics of the selected coals and power station design. These techniques include computer data bases for resource data handling and computer simulation of coal-fired boilers for determining coal property cost effects. Data Base Systems allow results of coal analyses to be efficiently handled, to assist in the review of the relevance of resource data to the coal sections proposed to be mined and the coal fractions proposed to be marketed. Data Base Systems also facilitate the marshalling of coal quality data into basic utilisation format to enable a proper utilisation review and analysis of the certainty and scatter of coal properties. Computer simulation of the effects of different coal properties on the capital and operating cost of power stations is achieved by establishing conceptual design parameters of the major items of plant to relate the variations in coal specification to equipment size and type. Variations in power station budget costs can then be determined using the computer model for variations in coal specification.

Jan 1, 1983

By Hulton SJ, MacKenzie DH

The Broken Hill orebody within the leases of ZC Mines is still a major lead-silver-zinc resource after over 80 years of mining. It illustrates particular problems encountered in resource and reserve estimation in old mines. The six mined ore lenses are characterised by three features: ò complex external geometry, ò high internal grade variability, ò bimodal grade distribution. The high grade 3, 2 and 1 lenses and B lode have sharp external contacts but contain some low grade internal zones. By contrast A lode is of lower average grade and comprises an extensive but geometrically variable mineralised zone within which are numerous irregular bodies of high and medium grade ore. Geological factors are the main source of variability in reserve estimation, which historically has been conservative. For many years the geological resource tonnage has been maintained at a level sufficient to make up for extraction but at a gradually declining grade. Using a geological block cut off grade of 10% Pb + Zn the present in situ resource is 53.8 Mt grading 8% lead and 13% zinc. Using empirical cut factors a "recoverable reserve" is derived from this large geological tonnage. There is some doubt that the "recoverable reserve" is conservative enough to reflect mining reality. The most sensitive indicator of forthcoming change in total resource or insufficient drilling and development is given by changes in the tonnage and grade of possible ore from which the proved and probable categories are derived. Examples are given to show that where reserves are drill indicated, the delineation required for proved ore reserves must be enhanced to achieve final stope design. The move in recent years to greater emphasis on non entry mining and lower recovery of in situ material poses a dilemma for a mine which has practised 100% recovery for much of its past. The need for a realistic reserve assessment in current terms needs to be balanced against the fullest possible geological knowledge of the resource to cater for future technological developments.

Jan 1, 1987

In this year marking the centennial of the Geological survey of Western Australia, it is appropriate that we should review the value of the contribution of the Survey, and Australian Geological Surveys in general, to the exploration industry. Most geological surveys in Europe and North America had their origins in the first half of the 19th Century when the burgeoning Industrial Revolution was demanding the identification of new sources of coal and iron ore. Australia, as a young nation, essentially dependent on an agricultural and pastoral industry, and with already discovered vast coal resources in Eastern Australia, had, no great need to explore for new mineral resources. However, with the discovery of gold in 1851, the mineral potential of the country became apparent to the whole world and the first Geological Survey in Australia was set up in 1852 in Victoria under A.R.C. Selwyn. After a number of false starts all Australian States had an established Geological Survey by 1900. It is hard to assess the contemporary value of the early work of the Geological Surveys with respect to exploration, almost all major mineral discoveries were made by prospectors and most mining companies had little time for geologists - although the Chamber of Mines in Western Australia in 1910, did recommend that the Geological survey be granted an additional ten thousand pounds over two years to map all existing goldfields and the country between them, and produce a reconnaissance map of the area east of a line between Wiluna and Edjudina as far as the South Australian border!

Jan 1, 1988

The products of Lower Miocene calc- alkaline activity on the east coast of Northland, New Zealand are described and contrasted with coeval rocks of the northern North Island. These rocks, the Eastern Volcanic Belt (EVB), occur in four main centres aligned north-west to south east as either plutonic/hyabyssal bodies or as agglomeratic piles and dyke intrusions. Significantly the plutonic members always occur to the north-west of the volcanic members, probably indicative of differential uplift along faults (upthrown to the north) aligned perpendicular to the EVB. A full basalt-rhyolite (diorite-granodiorite/ adamellite) spectrum is represented, with a temporal progression towards the silica-rich endmembers indicated by cross-cutting field relationships. Modal mineralogy parallels this trend, consisting of two-pyroxene, hornblende, biotite, quartz/alkali feldspar modal assemblages, and with rare occurrences of olivine and garnet-bearing volcanic phases. Chemically the EVB is medium-K, calc-alkaline (with respect to AFM and total-Fe/MgO vs. Si02 indices) and quartz and hypersthene normative. The thirty two available K-Prisotope dates indicate that activity was largely confined to the Lower Miocene (24Ma-16Ma), with an apparent younging towards the south east. Initial B7Sr/e Sr ratios (0.70335- 0.70679) are indicative of a continental- arc-type setting, however it is unlikely that a straightforward tectonic reconstruction for this part, of the Pacific Margin is possible. Evidence from xenoliths, both petrologic and isotope, within EVB magmas and from regional geologic studies suggests that hypotheses pertaining to a volcanic arc sited over a subduction zone may hold little relevance in this case. The review concludes that the EVB developed from the partial melting of a geochemically evolved lower crust as indicated by xenolith evidence. This occurred in response to thickening initiated by a short-lived obductive event in the uppermost Oligocene, and controlled spatially by pre-existing basement structure. Intra-suite chemical and mineralogic variation reflects not only crustal variability, but localized differences in physico-chemical conditions best illustrated by the rare occurrences of olivine and garnet.

Jan 1, 1987

By L Abrahamsson

The aim with this paper is to discuss experiences from the ongoing research project ‘Attract: A roadmap to attractive, inclusive, and safe mining workplaces’. The project’s aim is to analyse possibilities, effects, and consequences of the green and digital transformation in the Swedish mining industry from workplace, socio-technical and gender equality perspectives. The research project (2022–2025) at Human Work Science at Luleå University of Technology is financed by the strategic innovation program Swedish Mining Innovation (a joint venture by the national research funds Vinnova, Formas and the Swedish Energy Agency). The project includes a multidisciplinary research group of five senior researchers and five PhDstudents and a broad repertoire of methods, eg literature reviews, qualitative interviews with both managers and workers, workplace observations, workshops, surveys, and project seminars where the researchers and the company representatives together analyse the results. One important part of the project is the applied approach where the researchers work together with two mining companies and one subcontractor company. The project has two parallel main subprojects.

Sep 1, 2024

By Case JE

Complete Bouguer and isostatic anomaly maps compiled for Costa Rica provide new insights into the crustal structure and mineralization. Terrain corrections were approximated from the station to a radial distance of 167 km by computer using a 3- minute digital elevation model of Costa Rica and surrounding areas. Isostatic corrections, based on Airy-Heiskanen compensation, were also calculated from 0 to 167 km using the 3- minute elevation model and from 167 km to 180 degrees using combined topographic and isostatic reduction maps. Costa Rica can be divided into four main terranes based on gravity data: a Pacific coastal region, a Pacific inland area, a central region, and a Caribbean coastal region. Negative gravity anomalies along the Pacific coastal margin correlate with an offshore sedimentary basin, and large positive anomalies correlate with mafic and ultramafic igneous rocks on the Santa Elena, Nicoya, and Osa Peninsulas, and at Puerto Quepos. Pacific inland anomalies are separated from the Pacific coastal region by a steep gravity gradient, and over the Coast Ranges a major gravity low overlies a thick section of low- density sedimentary rocks. In the central region, a major gravity low occurs over a thick low-density Quaternary volcanic complex in the Cordillera Central, north of San Jose. A prominent feature of the Caribbean coastal region is an interrupted gravity low over the Limon Basin that reflects a thickening of low-density sedimentary rocks. A conspicuous gravity lineament, trending northeast separates northern and southern Costa Rica. The lineament is defined by the termination of several major gravity anomalies including those over the Coast Ranges, Cordillera Central, Puerto Quepos, and Limon Basin. In addition, the lineament correlates with other geological and geophysical data including: northeast-trending faults, the southern limit of large Quaternary volcanoes, the segmentation of the middle America volcanic belt, and a seismicity gap. This lineament may be the expression of a previously unrecognized major northeast- trending fracture zone in central Costa Rica. An important economic implication of the gravity lineament is a correlation with the termination of gold and porphyry copper deposits in Costa Rica.

Jan 1, 1987

By Sowerby BD

The CSIRU Division of Mineral Engineering is developing various techniques for the on-line determination of moisture in coal and coke, and some instruments are now commercially available. These techniques permit accurate and rapid determination of moisture in materials directly on conveyor belts or in bins. The most promising techniques for direct on-belt measurement of moisture in coal are capacitance and microwave transmission. A non-contacting under-belt capacitance and gamma-ray backscatter technique has determined moisture in coal to better than 0.5 wt'/. in field tests at BHP Stockton Borehole Colliery, NSW. Mineral Control Instrumentation Pty Ltd have been licensed to manufacture the capacitance gauges and have installed five commercial units in the coal industry and other industries. Microwave transmission techniques have an advantage over the under-belt capacitance technique in that they are not sensitive to vertical segregation of moisture in coal on the conveyor belt. A laboratory prototype of a microwave transmission gauge has been constructed and tested. Microwave techniques, based on a measurement of attenuation and phase shift, are under development and are expected to be field tested in 1987. These new techniques will enable a wide range of thickness changes to be accommodated. Capacitance and microwave transmission methods are unsuitable for materials of high electrical conductivity, such as coke. CSIRO is therefore developing a fast neutron and gamma-ray transmission technique, which is proving very accurate in laboratory tests. This technique overcomes many of the limitations of thermal neutron moisture gauges and it is expected to be field tested in 1987.

Jan 1, 1987

By T Amiconi

Ernest Henry Mining commenced operations on its copper-gold project in August 1997, some two months ahead of schedule and ten per cent ($35 million) under budget. The mine is located in the highly prospective Mount Isa/Cloncurry mineral district in north-west Queensland, approximately 38 km north-east of Cloncurry. The developer and operator of the project is Ernest Henry Mining Pty Ltd (EHM), an incorporated joint venture between MIM Holdings Limited (51 per cent) and Savage Resources Limited (49 per cent). The deposit is located approximately 40 km north of Cloncurry in North West Queensland and lies beneath a featureless black soil plain with no significant creeks or gullies cutting across the site. Vegetation is sparse and consists essentially of Mitchell grass with occasional low shrubs and trees. Up to nine million tonnes of ore and over 43 million tonnes of waste will be extracted each year from an open pit operation to produce approximately 350 000 tonnes of concentrate when in full production.

Jan 1, 1998