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The transgressive sedimentary sequence of the Noumea Basin contains rhyolitic lavas and less voluminous mafic and intermediate volcanics of shoshonitic affinities which erupted simultaneously during the late Cretaceous. The shoshonitic volcanism shows a trend froIn early mafic to younger evolved intermediate lithologies. The rhyolites are consistently calcalkaline. There is no evidence of mixing of the two magma types. The shoshonitic volcanism is the result of a short-lived subduction event related to spreading in the New Caledonia Basin and involved reactivation of an earlier esozoic subduction zone.

Jan 1, 1995

By C McGuire, W Harris, S Arsenault, D Witow, B Rogers

Mining deep orebodies is increasingly becoming the norm as the ‘easy’ orebodies are depleted. Deep ore mining requires significant ventilation and cooling infrastructure to not only meet regulatory requirements for air quality but also to achieve acceptable workplace temperatures with the higher strata rock temperatures and increased auto-compression. At the same time, advances in battery equipment technology are turning the possibility of a battery powered fleet into reality. The switch from a diesel fleet to a battery powered fleet offers several positive opportunities for the design and operation of a deep mine.The potential to reduce ventilation and cooling requirements due to battery powered equipment results in significant cost savings for mine development and infrastructure. Battery powered fleets are not subject to the same dilution requirements associated with diesel fleets thus allowing lower ventilation rates. At the low ventilation volumes possible with a battery powered fleet, surface refrigeration plants are limited with respect to the amount of cooling that can be delivered to the workface. Considerations for calculating the optimum air flow and cooling requirements are presented. Considerations for locating the refrigeration plant are also discussed. This paper presents these opportunities and considerations; including a case study comparing the ventilation and cooling system design with a diesel fleet versus battery fleet for a planned mine in Northern Ontario, Canada.CITATION:Harris, W, Arsenault, S, McGuire, C, Rogers, B and Witow, D, 2017. Diesel to electric – creating a positive paradigm in underground ventilation and cooling, in Proceedings Australian Mine Vent Conference 2017, pp 169–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By G J. Corbett, T M. Leach

Although hosted within an Ordovician magmatic arc, the Peak Hill high sulphidation system displays features typical of youngerPacific Rim high sulphidation epithermal gold deposits. Regional NW trending transfer structures are inferred to localise the magmatic source at their intersection of the NS trending arc. Fluids have migrated from the magmatic source along NW structures and thence exploited permeable horizons, which have become silicified. Alteration displays typical zonation from silicification through assemblages characterised by alunite, pyrophyllite and kaolinite and is followed by breccia/fracture controlled sulphide and gold deposition. Sinistral rotation on the NS arc has dilated NW trending fractures to produce the WNW to EW dilational fractures which host the higher grade ore. Mineral assemblages are typical of formation distal to the magmatic source in an epithermal environment. The combination of alteration and mineralisation zonation with structure provide fluid vectors which target a magmatic source to the SE of Peak Hill.

Jan 1, 1995

By C Bailey, T Kojovic, M M. Hilden, M S. Powell

The Julius Kruttschnitt semi-autogenous grinding (SAG) mill model was developed by Leung in the 1980s and extensively updated to the variable rates model by Morrell and Morrison in 1996. Since then only minor upgrades have been incorporated in the version distributed in the JKSimMet simulator. A number of improvements, developed over the course of the AMIRA P9 project and in recent independent work, have now been incorporated. These improvements are based on a power-based model that directly relates the degree of breakage with energy consumption. The new size-dependent breakage function has been incorporated. The upgrades include more accurate predictions for a wide range of mill fillings (ten - 40 per cent), slurry hold-up in the mill, pebble discharge rate and the influence of changes in feed size and ball load.The paper presents the status of progress in the model development. The upgraded model will greatly enhance its application to challenging design and optimisation studies required to optimise the performance of SAG milling circuits.CITATION:Kojovic, T, Hilden, M M, Powell, M S and Bailey, C, 2012. Updated Julius Kruttschnitt semi-autogenous grinding mill model, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 71-80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Kinetic Dependence of Refractory Gold Sulfide Biooxidation Using Different Microorganism Association In this investigation, refractory sulfide concentrate from a deposit located in northern Russia was treated using biohydrometallurgical technology. The objective of this work was to compare the accelerated refractory sulfide concentrate biooxidation abilities of the pure and mixed mesophilic and moderately termophilic acidophiles cultures. Pure culture of Acidithiobacillus ferrooxidans and two associations of the: Acidithiobacillus ferrooxidans + Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans + Acidithiobacillus thiooxidans + Leptospirillum + Sulfobacillus were used in this investigation. Results of sulfide concentrate bioleaching were analysed using the enzyme catalysis theory. Different effective kinetics parameters were calculated for Michaelis-Menten equation, such as Michaelis' constant and maximum rate of the enzymatic reaction. It was shown that the increase of microorganisms' species decreased Michaelis' constant. Lower Michaelis' constant characterises increasing bacteria ferment affinity to substrate (treated concentrate). As a result, the rates of sulfide minerals biooxidation have increased. This investigation has demonstrated that cultures of the different microorganism species, including moderately termophilic, allow to enhance different parameters of the biohydrometallurgical technology for the refractory gold sulfide concentrate treatment. We can see that bacterial leaching stage duration decreased and sulfide minerals oxidation increased. When the bioresidues were subjected to the hydrometallurgical stage, which includes aeration and sorption cyanidation, the operation factors were also enhanced. The decrease of aeration duration and the growth of the precious metal extraction by sorption cyanidation was achieved. Cyanide consumption was also reduced. The results of this investigation were used in design of an industrial plant.

Sep 13, 2010

Recovery of Pentlandite and Chalcopyrite from Tailings by Bi-Cyclone Powerful Flotation Column

Sep 13, 2010

By M Simpson

Greywackes of the greater Auckland Region (Brynderwyn Hills to Hamilton), when considered on a regional scale, have characteristic ranges of physical, mineralogical and other properties. Some properties (eg density, porosity, crushing resistance, clay index) generally cluster and correlate with the basement greywacke facies, regions and terranes recognised by geologists, and their diagenetic/metamorphic level. Other local factors, particularly variations in mineralogical composition, nature of matrix cement, grain size, and degree of weathering may produce aberrant properties. Some of these local variations, when extreme, have the potential to affect the aggregateÆs performance in roading or the concrete industries.   Smectite and the zeolite laumontite are the major deleterious minerals occurring in fresh greywacke rocks of the Auckland region, although weathered rocks may contain halloysite, an expanding member of the kaolin clay mineral group. These minerals, when found in abnormally high levels in greywackes cause expansion effects in the aggregate. Currently there are inconsistencies in the detailed correlation of shrinkage, clay index, clay mineral content and intrinsic expansion data that need further research to resolve them.  

Jan 1, 2007

Optical sensors have emerged during the telecom boom in the late 1900s, due to the availability to low-cost telecom-grade optical components. It's only after the telecom industry's fall in 2004 that optical sensors became sufficiently developed to be a viable technology for real-world applications. Geotechnical applications have long relied on electrical sensors such as thermocouples, strain, and the venerable vibrating wire to measure physical phenomena. Although these are well suited for a large variety of applications, electrical sensors cannot be used for all applications: these are vulnerable to noise, hazardous voltages and corrosion, limiting the environments in which they can be used. In addition, electrical wires can also become an issue when sensors require external excitation or are distant from the measurement system. Finally, changes in physical properties of electrical sensors and systems over time makes regular calibration a necessity - not easy to do when these are permanently mounted on structures. Optical sensing systems are non-conducting and use light to perform various measurements. There are several optical sensor technologies available, each with different strengths and weaknesses. In addition, there are different methods of interrogating optical sensors, each of which also present different strengths and weaknesses. To make matters worse, configuring the interrogation and scaling to physical units can also be challenging to the unprepared engineer. This paper will present a holistic view of optical sensing, presenting the different optical sensor technologies and interrogation techniques. Sample optical sensing systems will be revealed and top considerations for optical sensing will be presented.

Nov 25, 2010

By W Valery, S Morrell

In the mining industry blasts are usually designed to fracture the in situ rock mass and prepare it for excavation and subsequent transport. The run of mine (ROM) fragmentation is considered good when it is fine enough and loose enough to ensure efficient digging and loading operations. Mining optimisation strategy is hence usually focussed on minimising total mining costs and maintaining these ROM fragmentation characteristics. Although this approach ensures an efficient mining operation it ignores the potential impact on crushing and grinding. Investigations by several researchers have shown that designing blasts to produce ROM fragmentation to optimise crushing and grinding performance enhances the overall efficiency and profitability (Eloranta, 1995; Kojovic et al, 1995; Bulow et al, 1998; Kanchibotla et al, 1998; Scott et al, 1998; Simkus and Dance, 1998). Field experimentation in this area is often found to be difficult because of high implementation costs and insufficient understanding about the effect of fragmentation at different stages in a comminution circuit. Modelling and simulation of blasting and comminution processes provide a more economic alternative to explore the impact of blast design changes on the down stream operations (Kanchibotla et al, 1998; Kojovic et al, 1998; Adam and Siddall, 1998; Bulow et al, 1998). However, the reliability of such simulations depends on:the ability of the models to reproduce the physical processes that take place; characterisation of rock mass in terms of its blastability and comminution characteristics; and in the case of blast modelling the ability to predict fines (-10 mm) has been found to be particularly important as this fraction has a significant effect on mill throughput.

Jan 1, 1999

A New Online Detection Method for Arsenic Minerals in Process Streams

Sep 13, 2010

The lignite resource in the southern part of the South Island is New ZealandÆs largest source of indigenous primary energy. The ten deposits evaluated by the Liquid Fuels Trust Board (LFTB) have a total recoverable reserve of 6.2 billion tones equivalent to 74 000 PJ of energy or 20 times the original energy content of the Maui gas field. Updating the economics of the original LFTB studies indicates that lignite could be mined for between NZ$1.0 and 3.0/GJ. Its conversion to synthesis gas for production of petroleum products, chemical methanol, ammonia/urea fertiliser or electricity would be in the national benefit and likely to be commercially economic at todayÆs product prices.

Jan 1, 2005

By V Cullinan, D Buchanan

The Brunswick plant is located in Costerfield, approximately 40km east of Bendigo in central Victoria. Crushing, grinding, gravity gold concentration and flotation methods are used to produce a saleable gold concentrate and an antimony-gold flotation concentrate. This paper discusses the improvements made within the processing plant which have resulted in a 99% increase in throughput over nameplate capacity of 6 250 average tonnes per month to 12 445 average tonnes per month and increases of 12% gold (from 2007 average of 78% to 2014 average of 90%) and 16% antimony recovery (from 2007 average of 79% to 2015 average of 95%). This combined effort has resulted in an increase of equivalent gold ounces (AuEq oz) produced from 2010-2014 of 15 872 to 82 574 – a 66 702 increase.AuEq oz= Au oz +Sb t × Sb (US$/t)Au (US$/oz)CITATION:Buchanan, D and Cullinan, V, 2015. Improvements in bi-metal production at the Brunswick Plant, Costerfield, in Proceedings MetPlant 2015, pp 267–272 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

Three computerised sets of minerals information are being developed by New Zealand Geological Survey in co-operation with the Resource Management and Mining group of the Ministry of Energy: 1. Geological Resource Map: a file of information on the location, geology, geochemistry, production, and potential use of individual occurrences of aggregate, mineral, geothermal, coal, oil, and gas resources. The computer program can be used for search and retrieval of information and the production of maps and tables. The data is being published as a series of 1:250 000 maps with accompanying text and tables. 2. Minerals Bibliography: an index and retrieval system for mineral exploration related; open-file company reports, N.Z. Geological Survey files, scientific research publications and university theses. 3. Minerals WhoÆs Who: an annotated directory of geologists involved in mineral exploration, mining and research.

Jan 1, 1986

Research and Tests on Improving the Technology of Enrichment of the Copper-Molybdenum Ore

Sep 13, 2010

Permitting, engineering and evaluation, detailed design and construction aspects of the Golden Cross goldmining project in New Zealand are briefly reviewed. The extremely lengthy and complicated governmental approval process together with the delaying tactics of opponents of the project are outlined and comment is made on aspects of the draft legislation proposed as part of the overhaul of New Zealand's resource management laws.

Jan 1, 1990

As the theme of the conference is ære-discover Otago' from the minerals point of view, it is also timely. Of the eight million ounces of gold recorded produced from Otago, perhaps a quarter of this came from the goldfields of St Bathans, Vinegar Hill and Cambrians. The most notable among them was the Kildare Hill Mine, which is the so-called Blue Lake at St Bathans today. The bottom wash encountered in this mine contained the famous Kildare lead, which averaged 7 1/2 dwt to the dish, and is still one of the richest leads of alluvial gold known in the world. The richness of this lead, the best encountered in these gold fields, is otherwise stated to have yielded more than 42 ounces of gold to the cubic yard. It should be borne in mind that this equates to about $22 000 per cubic metre, in todayÆs values. I have been told by older residents of this district that in fact about 1 million ounces came out of the Kildare mine and associated workings. In todayÆs values, this would be about 530 million dollars worth of gold. The largest mines in the district were at Surface Hill, Kildare Hill, Nicholsons, Vinegar Hill, the Never Fail claim at Shepherds Flat nearby, and at Cambrians. It would appear that in almost every case, work stopped when the bottom wash progressed too deep down dip of the anticline hills on which it was initially found. The mining methods were sluicing and hydraulic elevating, and although the gold bearing ground did not stop, eventually it exceeded the ability of the mining methods then available years ago, to work it further. When it is realised that the previous mining has removed what is likely to be only a low percentage of the gold resources in these fields, a tantalising situation presents itself today in that mining technology now available will enable another cut to be taken off these fields. As in the past, I believe this will be million ounce plus and multi-million dollar scenarios, where the economic and social benefits will become widespread prizes.

Jan 1, 1992

New Developments in Spirals and Spiral Plant Operations Records indicate that spiral separators have been utilised in mineral separation for over 100 years. The Spiral's predecessor, the sluice, has been in use for centuries in different forms and a spiral can be thought of as a sluice wound around a column. The spiral separator is distinguished from the straight sluice, and other flowing film separators, in uniquely introducing centrifugal motion. The elegance of the spiral concept was embraced due to significantly improved separation efficiencies, ease of operation and tolerance of variation in feed conditions. Advances in spiral technology have improved the metallurgical performance, modernised the materials of construction, increased unit capacities and simplified operation. These advances have ensured that spirals continue to play a major industry role amidst other advancing and competing technologies. Recent developments in spiral and spiral plant technology include: the launch of the VHG spiral model, specifically aimed at feeds with very high levels of high-density mineral particles; the introduction of a high capacity wash water spiral model; and innovations in feed stabilisation and control. Details of these developments are presented together with the resultant operational benefits including feed stabilisation, product control and improved metallurgical performances.

Sep 13, 2010

By D Kotzen

Online cyanide analysers have been successfully used to control free cyanide in the gold/silver leach process for over 15 years. Use of such analysers leads to cyanide savings and improvement in recoveries. Plants with leach cyanide analysers show both lower and more consistent cyanide levels in tailings. Cyanide code compliance requires meeting residual cyanide targets in tailings. Monitoring and logging of the residual cyanide in plant tailings and effluent is required. Meeting targets may require cyanide recovery/destruction processes to be implemented. The operating cost of destroying cyanide is often the same order of magnitude as the cyanidation cost. Various cyanide destruction and/or recovery processes are reviewed. Choice of a process consistent with the environmental and operational requirements is illustrated. Online weak acid dissociable cyanide (CNWAD) analysers have recently been developed and introduced on gold plants. The application of a WAD 1000 online CNWAD analyser at a large gold plant is presented. The analyser ensures code compliance, reduces cyanide destruction process operating costs and forms a historical record of CNWAD values in tailings.

Jan 1, 2007

By Harrison AT, Smart RM

Backfill systems using unconventional cementitious hinders have been successfully used in relatively deep and hard rock tabular mines for longwall, scattered stoping and shaft pillar removals. Two unconventional cementitious systems are discussed: 1. A ground granulated blast furnace slag (GGBS) with an activator containing lime. This has been used with a total tailings 'stable' slurry at a relatively low dosage of less than seven per cent, by mass, based on dry solids. The room and pillar stopes supported with this fill were up to 20 in high and the tailings were relatively high in pyrite. .\ GGBS binder plus a silicate based activator and gelling agent that virtually eliminated all water drainage (and hence post filling shnnkage). The system used a slurry, but the addition of the ;iutivator created a final placed product that had the behaviour of a paste. The system has been successfully used for almost ten years in the following applications: ò sloping widths (mining heights) above 1.6 in; and ò shaft pillar removals in seismically active areas at the end of the life of the shafts. \This paper discusses the technical merits and costs of the systems and compares them to other fill systems (including true paste systems).

Jan 1, 1998

The design of a mine should aim to optimise the market value by maximising revenues whilst minimising costs. In open pit mining, the nature of the extraction technique translates this objective into the maximum recovery of reserves while minimising waste extraction subject to technical, economical and safety constraints. Since the introduction by Lerchs and Grossman, in 1965, of a model that is now considered a classic in the area, open pit design has reached a level of maturity and acceptance by industry. These models are being used on a regular basis by designers and planners.This paper proposes a new alternative model for open pit design. It is based on genetic algorithms (GA) and exploits a reduction of the number of decision variables of the more traditional techniques. The novel approach provides more flexibility than traditional models; it can also be extended to consider planning problems that traditional open pit design models are not capable of handling. The algorithm has been designed for two dimensional problems and tested in a simple instance. The results obtained in this simple test are encouraging and are a good supporting argument for the development of a GA model capable of handling three-dimensional (3D) instances. The model presented in this paper is just a first step towards a full GA to solve the pit design problem and it is believed that novel tools like the one presented herein could become great allies in tackling challenging problems in open pit design, an illustration of such a challenging problem is presented and discussed.

Dec 6, 2010