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By V Morand, W R. H Ramsay

Structural, mineralogical, and textural data from the Tarnagulla Goldfield demonstrate that the area has undergone three significant phases of deformation. The first phase of deformation (D1) predates the intrusion of the Tarnagulla pluton, which has been dated using K/Ar as 391 ¦ 5MY. We regard this pre-granite deformational event as the major regional deformation. Gold-bearing quartz veins have been deposited in dilational sites on west-dipping reverse faults. These sites demonstrate a geometry related both to faulting associated with D1 and the plunge of the F1 fold axes. This evidence, together with chronology of unmineralised ? D2 and D3 faults, the absence of quartz veining associated with D3 events, and the deformation of carbonate-quartz-biotite-sulphide aggregates within Sl by later S2, lead us to conclude that the bulk of the mineralisation was essentially syn- or late D1 . d18O values for fluids in equilibrium with vein quartz from Central Victoria have indicated equivocal support for either a magmatic or metamorphic origin. Our evidence supports a pre-magmatic origin for mineralisation at Tarnagulla and hence tends to favour a metamorphic fluid source.

Jan 1, 1995

Estimating Particle Size Fraction Proportions - A Multiscale Approach Using Multiple Kernel Learning

Sep 13, 2010

By K S. Smith

Mineral-deposit geology, geochemical processes, and biogeochemical processes are fundamental controls on the environmental conditions that exist naturally in mineralised areas prior to mining, and that result from mining and mineral processing. Input from economic geologists and geochemists is therefore crucial to effectively predict, assess, mitigate, and remediate the environmental effects of mineral-resource development. Recent open pit gold mining at Summitville, Colorado , has received intense public scrutiny for a variety of environmental problems, most important of which has been extreme acid drainage. Now a Superfund environmental cleanup site, Summitville exemplifies how economic geology and geochemistry principles: 1. could have been better utilized to first predict and minimise the environmental problems, and 2. can now be used to optimize the environmental cleanup.

Jan 1, 1995

By D Craw, G Eis

Late Cretaceous Blue Spur Conglomerate preserved as isolated remnants at Gabriels Gully, Weatherstones, Forsyth, Waitahuna Gully and Adams Flat was deposited during the intiation and early stages of extensional movement on the Tuapeka Fault zone at each locality. The deposits represent successive courses of a single fluvial system flowing across the Tuapeka Fault zone from the up-thrown (northeast) block. Each course, beginning with the channel at Gabriels Gully, was abandoned as a result of uplift-induced defeated antecedence in favour of a new course farther to the southeast around the southeast-propagating tip of the Tuapeka Fault zone. Schist and quartz in the conglomerate was derived ultimately from schistose rocks northeast of the Tuapeka Fault zone. Caples Terrane greywacke detritus in the middle and upper beds of the conglomerate was probably recycled from pre-existing sedimentary cover on the up-thrown block, following initiation of uplift on the Tuapeka Fault zone at each locality. Most of the gold is derived from vein sources in Otago Schist rocks to the north, and/or associated placers. Hydrothermal veins at Waipori, Hindon, Barewood, and Macraes are the most likely primary sources. There is no evidence to support previous interpretations of deposition by river systems flowing from the southwest, or axially along the Tuapeka Fault zone from northwest to southeast. High gold grades within Blue Spur Conglomerate should have a linear trend more or less similar to the orientation of the host channels, but are likely to drop off rapidly to the southwest. Extensions of the conglomerate-filled channels are unlikely to be preserved, but there is a strong probability that younger placers recycled from the former channels exist.

Jan 1, 1999

By X Yang, B Wang, L Liu

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Huoqiu iron ore field in north-west Anhui province is located in the south-east margin of the North China Craton and hosts large iron resources. Orebodies are hosted in Neoarchean amphibolite facies metamorphic rocks, forming silicon-iron bands from north to south. The area is dominated by an Early Precambrian basement consisting of Neoarchean grey gneisses, amphibolites and metasediments. The gneisses are similar with assemblages of Trondhjemite-Tonalite-Granodiorite in compositions and intercalated with amphibolites. Igneous zircons from gneisses and amphibolites have U-Pb ages of 2.86 and 2.75 Ga respectively, which are interpreted as the crystallisation ages of their protolith. Zircons from amphibolite and gneiss have eHf(t) values of 2.4–15.5 and -3.0–1.5 respectively. The tDM2(Hf) model ages of the gneiss range from 2.87 to 3.14 Ga, which is consistent with tDM1(Hf) ages of amphibolite (2.84–3.16 Ga). The U-Pb-Hf isotopes thus confirm that the gneisses were generated by partial melting of amphibolite. Two granites produce two group Hf isotopic compositions. The older one (1916 ± 42 Ma) has eHf(t) values and tDM1(Hf) ages of -9.4–3.4 and 2.24–2.71 Ga respectively, whereas the younger one (1823 ± 41 Ma) shows a large variation in eHf(t) values of -18.1–12.5 and tDM1(Hf) model ages of 1.73–2.92 Ga. Geological and geochemical characteristics indicate that the Huoqiu banded iron formations are a Superior-type iron formation rather than an Algoma-type as previously considered.CITATION:Yang, X, Liu, L and Wang, B, 2015. Study on the Huoqiu banded iron formation, West Anhui Province, East China , in Proceedings PACRIM 2015 Congress, pp 649–656 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Economically significant gold-silver mineralization occurs in Miocene andesitic flows and tuffs at Golden Cross, eight kilometres northwest of Waihi, New Zealand. The highest grade mineralization occurs in a steeply dipping elongate zone of strong quartz veining and brecciation underlying, but contiguous with, a gently dipping tabular quartz vein stockwork containing potentially open-pittable lower grade gold-silver mineralisation. The stockwork zone is enveloped by argillic alteration and overlain by unaltered Pliocene andesites and recent tephra. Evaluation of the prospect involved underground and surface geologic mapping, rock and soil geochemistry, IP-resistivity, magnetic and gravity surveys as well as 1844 metres of reverse circulation drilling and over 30 000 metres of core drilling. The paper outlines the exploration history of the area and describes the results of the various exploration techniques used at Golden Cross.

Jan 1, 1986

A summary of a proposal to develop a 20 000 tpa underground gold operation in a Forest Park. The environmental constraints are severe and affected the mine development planning and choice of mining method. The mine will use trackless methods to access the narrow 1.5 m ore shoots, and to mine ore by cut and fill methods. The use of Microscoop and CT 1700 HE electric LHDs for mucking, together with special drilling attachments for drilling, is central to efficiency and small Kubota diesel haulers will be used for carrying ore to surface.

Jan 1, 1986

By R R. Large

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The formation of orogenic gold deposits is commonly a two-stage process. The first stage involves preconcentration of gold in a suitable source rock, such as carbonaceous black shales, felsic volcaniclastics or komatiitic volcanics. The second stage involves the release of gold (commonly with arsenic and/or tellurium) from the source rocks during metamorphism or magmatic intrusive events, accompanied by the replacement of source rock pyrite by pyrrhotite. Recent research suggests that synsedimentary gold trapped in the structure of diagenetic arsenian pyrite in reduced carbonaceous facies of continental margin sedimentary basins is an ideal source of gold for many orogenic and Carlin-style gold deposits. The conversion of diagenetic arsenian pyrite to pyrrhotite during basin closure and greenschist facies metamorphism is the key process releasing gold and arsenic to the metamorphic fluid, with metal deposition in structural trap sites to form the deposits.CITATION:Large, R R, 2015. Orogenic gold deposits – a two-stage process of gold enrichment, in Proceedings PACRIM 2015 Congress, pp 335–340 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

Constraints on the mineral industry are best treated as issues that have to be understood and managed in partnership rather than in conflict with communities. TheZapopan development at Mt Todd in Australia and the Martha Hill development at Waihi in New Zealand are but two of many recent successful examples at the local level.   However, at the national level, the issues are more complex and more difficult to resolve because the most influential stakeholders are now the urban electorates and governments defer to their perceptions when making decisions and policy. In the developed countries, government policies for the development of mineral resources have been progressively eroded since the early 1970s. At the same time policies for the environment and for native land rights have generally been carried out in a way that has reduced access to minerals and increased the cost and risks for prospectors and developers (Hancock, 1995). Since the end of the Cold War, the lesser developed countries (LDCs) have introduced policies to attract investment in their mineral resources that remained undeveloped under previous unstable or hostile regimes. The increased attraction of these LDCs and the decreased attraction of the developed countries has caused many Australian and North American companies to outlay increasing proportions of their budgets and capital investment in the LDCs.   Significantly, LDC policies for environment protection do not discourage exploration and mine development, Surveys of the relative appeal of the LDCs and the traditional mining countries of the developed world, rate Chile, Argentina and Indonesia ahead of Australia and Canada in terms of risk, delays and ease of doing business (Australian Mining Monthly, February 1994).

Jan 1, 1995

By R J. Merchant

The Hauraki goldfield is located east of Auckland in the North Island of New Zealand. It includes Great Barrier Island, the Coromandel Peninsula and the Coromandel and Kaimai Ranges as far south as the town of Te Aroha and south east to Te Puke. It has a total north-south extent of about 180 km and an area of 3000 km2. The goldfield is the most productive in New Zealand, and while production at present is negligible, the area has undergone continuous exploration over the last seven years.

Jan 1, 1984

By H A. Challenor

Eyewash safety showers located in remote hot environments may be unsafe to use due to excess water temperature and high risk levels of water borne bacteria such as Legionella. Australian Standard AS 4775 specifies that dispensed water shall be bacteria free and have a maximum temperature of 37.8°C. Legionnaires disease is contracted when water aerosols containing Legionella bacteria are inhaled.Laboratory tests show 30 to 70 times more aerosols are generated by showers operating at 38°C than with showers operating at 25°C. Furthermore, excess temperature in flushing water can cause burn injuries leading to hospitalisation, skin grafts and/or permanent scarring. Excess temperature also increases the rate of reaction to corrosive substances, opens pores in the skin to allow greater dermal penetration and can cause dizziness and fainting by dilating blood vessels and reducing blood pressure.CITATION:Challenor, H A, 2017. Managing excess temperature and high risk levels of Legionella bacteria in eyewash safety showers, in Proceedings Iron Ore 2017, pp 337–346 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

The treatment plant at Martha Mine was upgraded from a nominal throughput of 110tph (O.93mtpa) to 150tph (1.25mtpa) late 1999. Post-upgrade performance did not meet expectations when treating either the competent primary ore or the clay-rich oxide ore.   ò Plant throughput is constrained by milling capacity when treating the competent primary ore. This is not an issue at present as current plant feed is oxide ore from the top of the open-pit, but will become so in future years as the pit deepens. To counter this future threat, ball mill power has been restored to 1100kW through modifications to the drive train. The addition of a crushing circuit may also be necessary.   ò Plant throughput was originally constrained by thickener and leach/adsorption tank issues when treating the oxide are. Changes to plant equipment and operations has seen the removal of these constraints and throughput on this material is no longer a problem.   The most significant issue facing plant staff at present is the high silver grade and its impact on gold recovery. These high grades impact upon recovery through losses caused by insufficient leach and adsorption capacity. To counter this, the geology, mining, and milling teams are working together to blend the high grade silver zones with lower grade ores - this is seen to be the quickest and most cost effective way to deal with the issue. The plant design has also been evaluated with a view to modifying it to cope with the higher silver grades. The viability of these modifications will depend on cost and time (that is, the length of time to implement any modifications versus the length of time to mine out the high silver zones).

Jan 1, 2001

Assessment of the Consistency Between Different Laboratory Froth Stability Measurements

Sep 13, 2010

A recent Evening Post Headline read 'Officialdoms Inertia Risking Millions in Growth Strategy'. The article beneath that headline outlined the difficulties encountered by the Government's growth strategy projects and included the paragraph 'public efforts by Government to brush up communication of the widespread nature of its growth strategy is believed to have been matched by efforts in private by some ministers to overcome their frustration at the constant delay while reports and paper work are moved between departments and through the system'. The article went on to point out that these delays could cost New Zealand millions of dollars in lost overseas exchange savings. We as responsible citizens should be appalled or at least concerned that such costly delays should or even could occur. But those on the outside of the system who spend much of their working life prodding, reminding, pleading, cajoling, even begging, the bureaucracy should be excused a smirk or a smile or even a good belly laugh. The Minister is usually a part of the bureaucracy passing judgment on someone else's proposals. This time the Government has plans of its own. Plans which it wishes to see implemented as rapidly as possible and even with the assistance of the precautionary National Development Act with its 'fast track' provisions those plans have got bogged down in the bureaucratic machine which this Government has done as much as any other to create. In the circumstances, the thought of Her Majesty's Ministers frustrated at the constant delay while reports and paper work are moved between departments and through the system is not unpleasing.

Jan 1, 1982

By C Placzek, E Beattie, K Blake

Channel iron deposits (CID) consist of ferruginous chemical sediments, and are an unusual subset of Phanerozoic ooidal ironstone deposits almost unique to the Pilbara, where they constitute around 19 per cent of the Pilbara’s iron ore exports. These deposits occupy many of the ancestral river channels of the Pilbara region, especially the Robe River palaeochannels, incising and meandering through the Precambrian banded iron formations (BIF) of the Hamersley Group and the underlying Fortescue Volcanics.This paper explores the factors underlying geochemical variation in CID, particularly the chemical properties of goethite. The selected deposits in the western Robe palaeochannel and its tributaries show little or no secondary reworking by later water tables. There is a total absence of aluminosilicate clays with all the deleterious elements such as aluminium and silica. Instead, these are associated with the goethite mineral lattice, either within or adsorbed to the cortices of pelletoids.A thickly vegetated environment, and the presence of the Maddina Volcanics as potential source rocks for these western Robe CID is offered as an explanation for relatively high aluminium in the deposits studied, and, in turn, as the reason most parts of the palaeochannel are preserved as inverted topography.CITATION:Beattie, E, Placzek, C and Blake, K, 2017. Dirty goethite – a geochemical characterisation of some western Robe River channel iron deposits, in Proceedings Iron Ore 2017, pp 489–502 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By I Hustwick

New Zealand Steel Mining Limited operates two independent sand mining operations on the West Coast of the North Island of New Zealand. Waikato North Head 30 km south of Auckland supplies ironsand concentrate as the raw feed for New Zealand Steel's works at Glenbrook and Taharoa 70 km further south, exports ironsand concentrate to Japan.   Taharoa uses two sets of six low pressure Warman centrifugal pumps in series to load bulk ore carriers 3 km off shore through two underwater pipelines. Waikato North Head delivers the ironsand to Glenbrook 18 km through a 200 mm ID buried pipeline using two stages of high pressure positive displacement (HPPD) pumping.   A high level of operating and maintenance expertise has been developed since commissioning the two systems which are proving to be reliable, efficient and of minimal impact environmentally.

Jan 1, 1990

By T Preston

Solid Energy is the largest coal producing company in New Zealand, employing 500 people and more than 250 mining contract personnel. The coal produced by Solid Energy plays a significant part in the energy mix for New Zealand being supplied to the coal-fired power station at Huntly. It is also supplied to a wide range of industrial users, NZ Steel, and primary processing. It is fair to say however that the positive economic and social benefits of coal have to some extent been overshadowed by the negative environmental consequences of coal mining.   Over the past two years Solid Energy have been actively researching and addressing the impacts that they currently have on the environment and making a significant investment in environmental improvements, rehabilitation projects and environmental research to address historical and ongoing environmental issues. These investments have been driven by the companyÆs commitment to its environmental policy, which states:   æSolid EnergyÆs overall environmental objective is for the cumulative result of all the activities we undertake to have a positive net effect on the New Zealand environmentÆ.   With such significant investment it is essential that the company is able to target expenditure wisely, ie invest where there is greatest environmental gain to be had, and are also able to actively demonstrate to stakeholders the improvements that are achieved. In order to be able to demonstrate the commitment and the steps that the company is making towards this goal a number of systems have been developed. Firstly an environmental management system along the lines of ISO14001 formalising the environmental processes, responsibilities, auditing and management review. Secondly as part of the planning element of the EMS an environmental management matrix, which allows the scoring of sites against environmental management goals, has been developed. Thirdly the monitoring and measuring tools have been upgraded with GIS driven relational databases installed for management of consent related information and monitoring results.   The development of the environmental management matrix has drawn on a number of existing systems such as the Australian Institute of Mining and Minerals Code 2000. In addition to adapting the scoring regimes from these methods the Solid Energy Environmental Matrix has been further developed to ensure that it reflects the actual environmental impacts on site, as well as the management and audit systems that are in place to control them at a strategic level. The development of this matrix has included a number of steps: +        reviewing the information that stakeholders would be interested in, +        reviewing what was already available, +        development of systems to collect data and benchmark the current         operations, and +        setting up support systems to ensure that the correct information would be provided for scoring.

Jan 1, 2004

By JOHN G. RAYNER

An examination was made of the filtration characteristics of a haematite slurry using a range of polyacrylamide based flocculants in solutions containing up to 3 per cent sodium chloride. The polymers used were "high" and "Iow" molecular weight and had from 0 to 40 per cent charged groups.Increasing charge density tends to reduce the dose required to achieve optimum performance measured by filtration rate and by cake moisture. In general increased salt addition tends to increase the dosage required to achieve these optima. Both these observations result from the change in polymer extension and accord well with the bridging theory of flocculation.The dose required for optimal cake moisture is up to three times greater than that required for optimal filtration rate. This effect is reasonably consistent for all polymers studied and appears to be non-linearly dependent on salt concentration, with the difference being small at 0 and 3 per cent but quite significant at 1 per cent.

Jan 1, 1987

Atlas Copco Construction and Mining Australia identified a number of issues in regard to the skill levels, labour turnover and productivity of our service technicians. In 1994 we were experiencing a labour turnover rate of 42 per cent per annum amongst our technicians. Exit interviews were held with each individual and one of the major areas of dissatisfaction was the degree of product training provided on our equipment, compared to what is required to be competent across the range of our products. These tradespersons were prepared to accept the reduced remuneration that an OEM offers, for the benefit of comprehensive, professional training that, in theory, could be provided. The truth is that we were achieving approximately 40 per cent of our target for training hours because of the demands of field service, pre-deliveries, etc. So, the summary was the same as the industry was experiencing at that time because of skilled labour shortages, production demands, etc people were employed and thrown in at the deep end. A recipe for failure that will be successful every time.

Jan 1, 1998

By F Hancock

A rainfall simulator was developed to assist with hydrogeomorphic research into the stability of engineered landforms associated with rehabilitated uranium mines in the Top End of Australia. It can be used in rough terrain with slope gradients up to 30o. The rainfall simulator is modular, utilises upward jetting nozzles, has a multiple head arrangement and is capable of delivering rainfall intensities between 60 and 300 mmh-1 over areas up to 1000 m2 and could be easily modified for larger areas. Rainfall uniformity is commonly in excess of 80 per cent and the kinetic energy approaches that of natural rainfall (The modular design utilises an equilateral triangular array of rainfall stands, constructed from galvanised steel water pipes and flexible plastic hoses. Total construction costs are low. The water supply reservoir is mobile and easily constructed. An example of its use at Ranger Uranium Mine, investigating the effect of cover on rainsplash and rainwash dominated processes shows that vegetation cover is likely to reduce the erosion rate by these processes by at least four times below that experienced on bare areas.

Jan 1, 1997