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By P Tzeferis

An exploratory laboratory work was carried out on microbial leaching of poor non-sulphide nickel ores, not amenable to conventional mineral processing operations. The results have shown that domestic low-grade lateritic ores of limonitic or haematitic type are amenable to bioleaching by fungal strains of Aspergillus sp and Penicillium sp. Maximum nickel and cobalt recoveries achieved were 60 per cent and 50 per cent respectively. Losses of soluble nickel in the fungal biomass were found in the range 3 - 11 per cent. Chemical analysis of the leach liquors showed the presence of significant amounts of citric, oxalic and other organic acids, indicating the role which certain metabolic products of fungal activity may play in the process. Possibilities for future investigations are discussed.

Jan 1, 1997

By T Leach, B Fulton, R Stewart

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 tile intersection with an arc parallel structure, into which basic magma derived from tile 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 me 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

It is now becoming mandatory in Australia to rehabilitate ponded fine grained coal mine tailings, which may well have been deposited initially with no consideration as to how or whether this could be done nor to the costsinvolved. Of prime importance to the rehabilitation of tailings ponds are the bearing capacity and deformation characteristics of the tailings. Since the tailings are fine grained, time effects will govern the self-weightdeformation of the tailings initially deposited as a slurry and the subsequent deformation of the deposit under the weight imposed by rehabilitation fill. The engineering properties of a particular deposit of ponded tailings havebeen investigated and its response to the placement of fill monitored and analysed.

Jan 1, 1987

By D Craw, L Cox, R J. Norris

The Rise and Shine Shear Zone is a mineralised low-angle deformation zone traceable for at least 7 km through biotite zone schist of the Dunstan Range, central Otago. The zone is commonly believed to be similar to the actively mined Macraes deposit. The Rise and Shine Shear Zone occurs in the immediate footwall of the Thomsons Gorge Fault, a regional scale Cretaceous normal fault that juxtaposes chlorite zone schist against biotite zone schist. Most mineralised rocks are deformed and record a progression from early stages of semiductile deformation to more brittle cataclasis. Folds in mineralised rocks trend northwards. The mineralised schist is hydrothermally altered with variable silicification, sericitisation, chloritisation, replacement of titanite by rutile and carbonate alteration. Gold is associated with pyrite and arsenopyrite and occurs in both ductile and brittle microstructures. Sheared and mineralised schist is cut by north-striking fault zones which host mineralised quartz veins. Veins in the shear zone contain hydrothermal albite. Trace element analyses show enrichment in As, U, Th and rare earth elements. Many of the above features are similar to Macraes deposit, but there are important differences. In particular, the Macraes deposit is hosted in lower grade rocks and truncated beneath by a normal fault, Macraes has no U or Th enrichment, Macraes veins have no albite and folds at Macraes trend NW-W. Rise and Shine mineralised rocks have no Cr enrichment and no hydrothermal graphite.

Jan 1, 2005

By A Asadov, D Nair

This paper discusses the determination of the percentage of crystalline material in a natural silica deposit which would be considered harmful to health (<10 ¦m). A sample of the natural silica material was recovered and split into a number of subsamples. Samples were sieved using a conventional dry sieve to remove material >300 ¦m before testing. Particle size analyses of the fine fraction showed 75 per cent of the material was below 10 ¦m. Initially XRD and XPS were run on the samples to determine the minerals and composition of the sample. The XRD revealed strong quartz peaks and smaller tridymite peaks with a high amorphous background. The XPS indicated traces of iron, titanium and carbon with dominant silicon and oxygen peaks. The structure of the sample was investigated using the SEM. It was apparent that there were a number of larger quartz crystals (>30 ¦m) with a mix of amorphous and crystalline in the finer fraction. It was also observed that amorphous material was attached to the surface of the crystals. In order to determine the percentage of crystalline quartz a known amount of quartz was added to the sample incrementally. On each addition an XRD scan was performed and the area under the peaks recorded. Back analysis of these peaks with an assumed percentage of crystalline material in the original sample gave a crystalline content of 30 per cent. The quantity at the respirable fraction was estimated to be 18.7 per cent.

Jan 1, 2003

By S C. Dominy

This contribution examines the effect of feedstock sampling before the sorting stage of polyethylene terephtalate (PET) bottle recycling. Batches of waste PET bottles may contain non-PET bottles which need to be removed by sorting. Any residual presence of PVC is detrimental for the quality of products manufactured from recycled PET. The maximum tolerated concentration of PVC in cleaned PET is extremely low, which places high demands on the recovery of PVC achieved by sorting. To be confident of attaining the desired PET quality after sorting, acceptance sampling of truckloads of PET bottles may take place prior to sorting. It is shown that accounting for sampling uncertainty requires that the sorting process achieves a consistently high recovery of PVC bottles.CITATION:Glass, H J and Dominy, S C, 2017. Plastics recycling and sampling, in Proceedings Eighth World Conference on Sampling and Blending , pp 129–134 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By D Craw, R Norris

The Golden Bar pit is part of the Macraes mine, the largest gold mine in New Zealand. The Macraes mine is mainly developed in the late metamorphic Hyde-Macraes Shear Zone. However, the Golden Bar pit was developed in a mineralised zone about 200 m structurally above the Hyde-Macraes Shear Zone. The host rocks are dominated by massive quartzofeldspathic schist (5 - 10 m layers) with minor intercalations (1 - 5 m scale) of micaceous schist. All the host schist has disseminated pyrite (micron to mm scale) from pervasive late metamorphic hydrothermal alteration.   In addition, there has been more localised (metre scale) relatively intense hydrothermal alteration controlled by shears subparallel to foliation. Gold occurs in three types of mineralised rock: silicified schist, which dominates, fissile black sheared rock, and cross-cutting quartz veins. There are three principal structural zones in the deposit: 1.   a strongly sheared micaceous and graphitic zone at the base of the structural sequence; 2.   a weakly deformed schist zone cut by relatively flat-lying (= 20¦ dipping) quartz veins; and 3.   a stack of imbricated schist pods and deformed silicified schist confined between two sub-parallel low-angle (ca. 30¦) shears.   These structural zones were juxtaposed during thrust deformation. The lower black shear zone has m-scale folding and over-thrusting packages, kink folding and foliation stacking with associated striations that imply west-directed thrusting. Striations and imbrication geometry between the upper two shears imply oblique thrusting that was directed towards the west. Post-mineralisation normal faults locally disrupt the mineralised zone. The Golden Bar pit mineralised zone has some of the structural and mineralogical characteristics of the main Hyde-Macraes Shear Zone, and may be genetically related.

Jan 1, 2006

Lower Miocene Maryville Coal Measures at Waitewhena Coalfield, in the Taranaki coal region, include seams of sub-bituminous coal up to 4 m thick. During coalfield exploration Fletcher Challenge Ltd drilled ten cored holes, all of which encountered at least one seam. Coal quality is variable. Ash ranges from six to 12 per cent and sulphur from 0.5 to three per cent. A basal seam, overlying the Lower Mokau Sandstone, appears to extend throughout the area under investigation. A rider seam, of variable thickness, closely overlies the main seam in most drillholes. The rider converges with the main seam to the north and vertical trends in coal properties suggest that the seams are united in some locations. A less extensive seam sometimes occurs at the top of the coal measures beneath the Upper Mokau Sandstone. The lithostratigraphy of the intervening coal measures is complex, and coexistence of fluviodeltaic, lagoonal/lacustrine, and marine depositional environments is provisionally inferred. Lateral variations in coal properties (clastic derived ash, volatile matter, inertinite, hydrogen), thickness of the sedimentary parting between the basal seam and rider, texture of the coal measure sediments, and distribution of the upper seam all indicate persistence of a relatively low lying northeast-trending zone which may have been structurally controlled. Available data indicate that coal measure accumulation was terminated by marine transgression from north to south.

Jan 1, 1987

By M A. Knackstedt

Coupling between deformation processes and rock permeability is a major factor influencing the architecture of fluid migration and the localisation of ore deposition in several types of hydrothermal ore systems in middle to upper crustal regimes. Permeability in many hydrothermal systems is controlled by a dynamic competition between deformation-induced porosity-creation processes and porosity-destruction processes. Localisation of deformation within faults, fractures and shear zones leads to flow localisation, with large-scale flow systems forming when active faults and shear zones link to create percolation networks. Numerical modelling techniques are used to explore the growth of fracture networks and evolution of network connectivity during progressive deformation. Initial results indicate that networks reach a percolation threshold at very low strains. Near the percolation threshold, flow is localised along a small proportion of the total fracture population and favours localised ore deposition. At higher strains, flow is distributed more widely throughout the fracture population and may provide reduced potential for production of high-grade deposits. The distribution of mesothermal gold deposits along a small subset of the total population of co-active faults and shear zones in the Archaean Yilgarn Craton in Western Australia indicates that some hydrothermal systems maintain themselves near the percolation threshold for a substantial part of the lifetime of the system. Fluid-driven growth of fault/fracture/shear networks may lead them to self-organise near the percolation threshold.

Jan 1, 1999

By A M. Mueller

St Helena tunnel is the centrepiece of the Pacific Highway upgrade from Tintenbar to Ewingsdale, abbreviated and commonly known as T2E. At the deepest point the twin tunnels run 45 m below the ridge line of St Helena Hill, located about 5 km west of Byron Bay. The tunnel breakthrough was achieved early in 2014 and the works for permanent lining will be completed in early 2015.Once the project will be handed over to the public in 2015, T2E will deliver a safer highway and uninterrupted traffic flow between New South Wales and Queensland. The design speed in the project area has been set to 110 km/h by the client Roads and Maritime Services (RMS), which will reduce the travel times between Brisbane and Ballina to just over two hours.The two tubes of the tunnel have been designed to accommodate three lanes in each direction with shoulders and walkways on either side of the carriageway. These requirements result in a huge cross-section of about 20 m width and an excavated area of about 210 m2.With the tunnel alignment being situated in basaltic rock, St Helena tunnel is conventionally driven. The selected excavation method was predominantly drill-and-blast with temporary support being installed immediately after the excavation. Despite the wide span of the tunnel, the geology allowed the tunnel perimeter to be supported by only rock bolts and a layer of shotcrete over the majority of its length.Due to environmental reasons one of the approval criteria of the project was that the tunnel must not have a detrimental long-term impact on the groundwater system within St Helena Hill. Consequently the tunnel has been designed as a fully tanked structure with a waterproofing sheet membrane installed on the temporary shotcrete.The permanent structure of the tunnel has to meet a 100-year design life and it is designed as a cast in situ concrete lining. Considering the water pressure on the lining the concrete is reinforced with a significant amount of bar reinforcement.The presented paper provides a more detailed explanation of the geology and the consequential temporary and permanent support measures together with the waterproofing system.CITATION:Mueller, A M, 2014. Pacific Highway upgrade from Tintenbar to Ewingsdale (T2E), St Helena Tunnel, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 419–424 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By J Ramezani, K Faure, N Mortimer

Western New Zealand can be regarded as a rifted continuation of eastern Australia. Detailed studies of units previously considered to have trans-Tasman correlations are being undertaken within the FRST Programme Mineral Wealth of NZ and its EEZ to test specific connections, and thus add to the exploration framework of NZ. Correlation of two major episodes of granitic magmatism are currently being investigated. These represent the oldest (mid Paleozoic) and youngest (Early Cretaceous) magmatic events that conjoined Australia and New Zealand are believed to have in common.

Jan 1, 2007

Geological information is essential for a diversity of public and other purposes, including land use planning, hazard mitigation, and the exploration and sustainable use of natural resources. This is especially important in New Zealand, where the complexity of the geology is due to its position on an active plate boundary - the ultimate cause of earthquakes, mountain building, subsidence and volcanic activity. The geological setting also controls the origin and distribution of New Zealand's varied mineral and energy resources. Providing information about the origin, quality and quantity of mineral resources has long been seen as a key function of national geological organisations such as the Institute of Geological and Nuclear Sciences. Such information is essential for wise land-use decisions under the Resource Management Act. One of the major goals of the Institute is to quickly and effectively disseminate research results to interested users. The most effective and internationally accepted method of presenting geological data is by means of geological maps, which show the distribution of rock types and structural features at the surface. Most countries have ongoing gelogical mapping programmes, and in recent years the need for up-to-date, reliable information has led to a trend to accelerate basic geological mapping (eg US National Geological Mapping Act 1992; Australian National Mapping Accord 1990; Plan 2000 in the UK). Over the last 25 years, the Institute of Geological and Nuclear Sciences and its predecessors (NZ Geological Survey and DSIR Geology and Geophysics) have concentrated on detailed mapping of priority areas selected on the basis of economic and scientific interest. This has included remapping of Nelson-West Coast and Coromandel, regions with high mineral potential, for which 1:63 360 or 1:50 000 maps have been prepared.

Jan 1, 1994

The Johnny Mercer lyrics 'You've got to accentuate the positive, Eliminate the negative, Latch on to the affirmative à' would best sum up the traditional approach to community relations in the mining industry. This '90s 'Public Relations spin' approach, usually backed up by scientific data, technical reports and graphs outlining risk probability and the impact potential on people and communities, is being challenged. Challenged by communities who have greater access to information, demand greater levels of transparency and corporate responsibility of large corporate operations and possess greater awareness of the communities they live in.   The growth of the environmental movement, of anti-globalisation, anti corporatism, apprehension of a large corporate's ability to deal with community issues, and a lack of faith in the abilities of regulators to regulate corporate activities, means our industry faces challenges on multiple fronts. It must now be able to address these from a personal/community perspective if it is to remain relevant within communities.   One of the keys to this is linking the internal activities and responsibilities to the externals concerns and demands for higher levels of operation and care.   This presentation draws on Corporate Public Affairs trends, functions and approaches and the application to External Affairs activities within Newmont Waihi Gold's operations in Waihi and regional exploration activities throughout the Hauraki Goldfields.   The approach presented works on the philosophy that communities don't necessarily have to like what we do, but should be able to identify and recognise the way in which we involve them in decision making, communicate our intentions and respond to issues.

Jun 1, 2010

OneSteel and BlueScope Steel have been working with the CSIRO to develop sustainable carbon fuels and reductants which are suitable for use in the iron and steel industry. One of the initial focuses of this work has been a process called steel recarburisation which is the addition of carbon to liquid steel to produce particular steel grades. This paper reports on the preliminary work and the recent full scale recarburisation plant trials conducted at the OneSteel Sydney Steel Mill.   Preliminary experimental work involved kilogram scale recarburisation of liquid steel with a range of commercial and prepared charcoal products. This work showed that charcoal dissolves into liquid steel very quickly and that carbon recovery to steel was inversely related to the charcoal volatile content. Initial larger scale work focused on the collection of wood, and preparation of low volatile charcoal which is required for steel recarburisation. Approximately three tonnes of charcoal was prepared at the Corrimal coke ovens of the Illawarra Coke Company. This charcoal was dried, crushed, sized and packaged in a form suitable for addition to 80 tonne liquid steel ladles.   The recarburisation trial was conducted over 30 ladle heats during June 2009. The charcoal was manually added to the liquid steel in 5 kg bags using normal plant practice. Conventional commercial recarburiser was also added to the liquid steel in alternate ladle heats. The performance of the charcoal was compared with the conventional recarburiser based on the carbon recovery to steel, hydrogen pick-up by steel and the rate of carbon dissolution into steel.   An analysis of the trial results showed that the charcoal performed at least as well as commercial recarburiser in carbon recovery and rate of dissolution but may have resulted in a slightly higher hydrogen content of steel. This is probably due to the higher moisture content of charcoal. The main challenges in the future include: increasing the charcoal density to improve transport and handling economics, securing a sustainable supply of biomass for the steel industry and developing a charcoal production industry so materials of suitable quality for both production and trials on other applications can be conducted.

Jun 1, 2010

By P S. Datta, V N. Misra

Higher bed height up to 680 mm, including 30 mm hearth layer of sized return sinter and high suction below the grate bars up to 1400 mm WG have resulted in increasing the productivity to a level of 33 t/m2/day and reduced coke rate to a level of 46 kg/tonne sinter. The ferro-wastes like blue dust, flue dust, mill scale, collection from dust catcher and gas cleaning plant, etc have been successfully added in charge mix to produce quality sinters. In this paper, brief description of the work done at Regional Research Laboratory (CSIR) in last few years and two case studies are discussed including the successful development of pan sintering units.

Jan 1, 2002

By C Rizzardi, M Callahan, J Mahon

Henderson Operation’s underground molybdenum mine has been in production since 1976. Since that historic date, more than one billion pounds of moly has been produced, and over 120 Mt of ore extracted from three different levels and many different panels. The safe and successful operation of Henderson has been, and will continue to be, dependent on utilising an increasingly sophisticated fleet of equipment, advanced designs, innovative mining techniques, best practices in maintenance processes, improvements in crushing and conveying systems, and most importantly, the training and mentoring of the underground staff. These ‘professional mining technicians’ have been essential in the safe and efficient operation and maintenance of the underground mine and convey systems, and will drive the continuous improvements needed to keep Henderson competitive in the growing global market.CITATION:Callahan, M, Mahon, J and Rizzardi, C, 2016. Development of the professional mining technician – Henderson’s underground mine continuous improvement program, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 161–166 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

Planning for the Macraes Extension project highlighted the need for additional tailings storage availability. The possible solution of developing new tailings impoundments in Northern Gully, in tum, led to concerns being expressed by the regUlatory authority over the assimilative capacity of Deepdell Creek. Philosophical differences over the appropriateness of applying a seepage model used to set standards in consents for the original project resulted in the company re-evaluating the whole monitoring system associated with tailings disposal and seepage control. Re-evaluation indicated problems arising from the existing in-stream water quality monitoring in respect of protection of the aquatic ecological system and verifiability of results. A new monitoring system was designed relocating the compliance monitoring point out of the stream and into the gully containing the tailings impoundments giving greater certainty of monitoring results to all parties and providing improved protection for the aquatic ecology of Deepdell Creek.

Jan 1, 1993

By G H. Clark

Batu Hijau is a porphyry copper-gold deposit located onSumbawa Island in the western Banda Arc of Indonesia. The deposit has been evaluated from 54 000 m of drilling in 105 diamond drill holes over a surface area of 1.2 km2 and to a depth of 1000 m below surface (412 m below sea level). A provisional plan is being evaluated to mine 642 million tonnes at an average grade of 0.61% Cu and 0.55 g/t Au (variable cut-off) from an open pit in the higher grade portion of the resource.   The deposit is associated with a calc-alkaline intrusive complex that was emplaced in a thick sequence of andesitic pyroclastic rocks. The oldest and most widespread intrusion is porphyritic to medium-grained, equigranular, quartz hornblende diorite. At Batu Hijau the western diorite contact zone was intruded by two phases of tonalite. The older tonalite is a stock increasing from 200 m diameter at surface to 500 m at sea level. It consists of quartz, plagioclase and hornblende phenocrysts set in a groundmass of similar composition. A younger tonalite intrudes the tonalite stock, quartz and plagioclase phenocrysts are more abundant and it has a finer groundmass than the older tonalite. Brecciation occurs near the older tonalite contacts but there are no breccia pipes or late-stage features such as pebbledykes or postmineralisation intrusive rocks.   Hydrothermal alteration of Old Tonalite and adjacent rocks is centred on the Old Tonalite and is zoned from a core of pervasive potassic alteration grading to an outer propylitic halo. At depth a propylitic assemblage is developed in the low grade core in the Old Tonalite. Phyllic alteration, late stage and mainly fracture controlled, overprints both potassic and inner propylytic zones. Intermediate argillic alteration overprinting is widespread, particularly on the eastern side of the hydrothermal system, where advanced argillic alteration overlies argillic alteration.   Ore grade mineralisation is cylindrical in shape, up to 800 m in diameter, and is centred on the Old Tonalite. A high grade shell (>0.75% Cu) forms an upward tapering cone in and around the Old Tonalite and reaches the surface in the centre of the deposit. Lower in the shell >l g/t Au and >2 g/t Ag accompany >1% Cu. Below 75 m above sea level mineralisation in the Old Tonalite rapidly decreases as a weakly mineralised core develops, but the limb continues to contain mineralisation to at least 412 m below sea level. Fracture and vein-controlled chalcopyrite and bornite are the dominant hypogene copper minerals and are the hosts for most of the gold mineralisation. Gold occurs free and in the lattice of the copper sulphides, and has been observed in quartz.   Weathering, especially where argillic alteration is developed, has produced a strongly leached cap, up to 147 m thick, below which is an irregular copper enriched supergene zone. Where leaching is not developed, such as over the centre of the deposit, an irregular oxide zone and a weakly developed supergene zone may be present.

Jan 1, 1995

A new test coke oven of seven cubic foot capacity is described. The oven was designed to simulate conditions in a central section of a battery oven and a special feature is the achievement of unidirectional heating from the flues on either side of the charge. The method of charging permits close control of charge conditions'such as bulk density and moisture content. These conditions, as well as coking conditions (e.g. flue temper- atures., coking time) must be varied to simulate conditions in different batteries, The effects of several variables on coke quality are discussed. Using test oven conditions corresponding to those of Newcastle steelworks batteries, good agreement was obtained between strength indices of test oven and battery cokes; for 17 tests, the average A.S.T.M. stability and hardness indices for the test oven coke were 38,5% and 69.7%, while those for the battery coke were 37.1.% and 67.6%.

Jan 1, 1969

By M J. Begbie, K B. Sporle

The Golden Cross low sulfidation epithermal deposit produced approximately 750,000 ounces of Au from two ore zones: the underground Empire Vein System and the open pit stockwork. The Empire Vein System has at least eight stages of vein formation: (1) sulfide veins, (2) black veins, (3) massive veins, (4) banded veins, (5) thin white veins, (6) crumbly veins, (7) massive/platy calcite veins, and (8) flattened rhomb calcite veins. Gold mineralisation occurred relatively early in the lifetime of the system, dominantly during 2 through 4. The late calcite veins (7 and 8) and early sulfide veins (1) are barren. The vein system formed in a dominantly extensional environment, though some compressional faulting may have also existed during vein formation. There is no evidence for significant strike-slip faulting during vein formation, highlighting the fact that explorationists should pursue on-site structural patterns rather than fashionable models.

Jan 1, 1998