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Lower greenschist quartzo-feldspathic schists within the N-S trending Earnslaw Synform of the Upper Wakatipu area are pervaded by late-stage quartz filled extensional and extensional shear fractures, with quartz-scheelite lodes infilling normal faults. Exposed veins/lodes mapped over at least 1000 km2 define a paleoflow system developed during late metamorphic exhumation of the schist. Both veins and lodes have consistent angular relationships to the schist foliation independent of their location on the Earnslaw synform. Unfolding the synform leads to a regional subhorizontal foliation and a systematic set of subvertical quartz veins striking NNW extending over a depth interval >5 km, striking parallel to a set of normal faults hosting the quartz-scheelite lodes. The structures define an extensional regime with s1 sub-vertical, s3 oriented WSW-ENE, a low differential stress, and suprahydrostatic fluid pressures.   The quartz-scheelite lodes (<2 m thick) occupy faults which cross-cut the quartz veins, and are traceable for a few hundred metres, at most. The lodes consist of laminated and/or massive quartz, slivers of crushed and folded schist, random and discontinuous lenses of scheelite with clay selvages separating the lode from relatively undisturbed wallrock schist. Textural evidence suggests that slip developed incrementally with total displacement on faults during lode formation on the order of a few ten's of metres.   The distribution of Glenorchy veins demonstrates broad scale hydrothermal flow through low-permeability schist, channelled within dilatant mesh style structures comprising interconnected shear and extension fractures. Flow through the lodes was likely derived from the greater surrounding area via the interlinked network of fractures and focused into the low displacement shears. Available evidence suggests the system developed together in a uniform extensional stress regime toward the bottom half of the seismogenic regime.

Jan 1, 2001

By S Lal, S Rost, Q Williams, K Collerson

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Shoshonite suite (absarokite-shoshonite-banakite) and adakite-hosted epithermal Au deposits are a feature of circum-Pacific magmatism. Fijian examples include Tavua (Emperor) and Tuvatu on Viti Levu. New discoveries of shoshonite suite and adakite-hosted epithermal Au mineralisation have been made in the southern Yasawa Islands and in central-northern and central-western Viti Levu. The Fijian shoshonites define four NE–SW trending suites. The oldest is the northern 7.9–5.0 Ma Yasawa suite, followed by the 4.7–3.5 Ma Sabeto–Tavua–Rakiraki suite in northern Viti Levu, the 4.7–4.2 Ma Yanuca–Vatulele suite approximately 20 km south of Viti Levu and the 3.4 Ma Astrolabe suite approximately 75 km further south. Shoshonite suite lithologies with 3.8–3.0 Ma ages also occur in the Lomaiviti islands between Vatu-Cake and Moala, to the east of Viti Levu, defining a trend oblique to the NE–SW shoshonite belts. Seatura, a 3.3–2.8 Ma ocean island basalt (OIB) volcano, sits at the northern end of the Lomaiviti trend shoshonites. Trace element/isotopic chemistries indicate that shoshonite arc magma genesis involved the melting of a hydrated supra-subduction zone mantle wedge and also a lower mantle-derived plume (OIB) component. The upwelling plume provided heat for melting and possibly Au enrichment. Accessing the melt generation zone associated with the plume required a slab conduit or window. Such slab windows form by tearing during subduction or occur at slab edges. Adakites form by plume-induced slab melting. The four NE–SW Fijian shoshonite suites are interpreted to occur in back-arc extensional zones above a slab window (tear) that migrated southward during rollback of the New Hebrides–Vanuatu subduction zone. The plume (Seatura OIB) that is interpreted to have caused mantle wedge melting and formation of the Lomaviti trend shoshonites was focused along the interface between the north-dipping Vanuatu–New Hebrides subduction zone and the west-dipping Tonga subduction zone, which we have seismically imaged at approximately 400 km depth. Our model ‘cracks the metallogenetic code’ for shoshonites and adakites and has regional and global implications for Au exploration.CITATION:Collerson, K, Lal, S, Williams, Q and Rost, S, 2015. Cracking the metallogenetic code for Fijian epithermal gold mineralisation , in Proceedings PACRIM 2015 Congress, pp 219–226 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

At the Waikato North Head Ironsand operation, NZ Steel Mining Ltd is using a Bucket Wheel Excavator û shiftable conveyor mining system to excavate Titanomagnetite bearing sand and clay. The system utilises two Bucket Wheel Excavators with a two level shiftable bench conveyor and common trunk conveyor to deliver the material to a processing plant. The system was commissioned in November 1984 and has proved itself to be a high capacity, low cost method of excavating. Techniques of handling high sand faces have been developed and the conveyor layouts are going through a process of change to cope with the variable geo technical conditions and remain within: the characteristics of the excavators. The safety requirements for operating the system have been of a high standard and the experience has increased the confidence of the Company and the Mines Department Inspector's, for the first Bucket Wheel Excavator Mining system in New Zealand.

Jan 1, 1986

The Purification of Low-Grade Quartz Ore by Flotation and its Mechanism

Sep 13, 2010

By A Proudman, J Isles, R Lawolo, G Forster

PT Nusa Halmahera Minerals (PT NHM) is an Indonesian joint venture company owned by Newcrest Mining Limited (75 per cent) and PT Aneka Tambang (Persero) (25 per cent). PT NHM operates two underground gold mines, Kencana and Toguraci at the Gosowong mine site in North Halmahera District, North Maluku Province, Indonesia.Due to several major stope overbreak events at Toguraci, the mining method and sequence was reviewed. The method was changed from a bottom up Avoca stoping approach using waste rock as fill material and leaving sill pillars, to a top down open stope method using paste fill without sill pillars.The revised mine plan originally had stoping progressing from the current level to the base of reserves followed by extraction of the sill pillars in the upper levels at the end of mine life. Geotechnical modelling was conducted on the revised mine plan and it was recommended that the sill pillars be taken early due to the risk of them overstressing and being difficult to recover if left until the end of mine life. The backfill material above the sill pillars is unconsolidated run-of-mine development waste rock or unconsolidated rock fill (URF).Due to earlier attempts to extract sill pillars under URF not being successful in the upper areas of the mine, it was stipulated that the URF above the five remaining pillars must be consolidated prior to stoping. Cost benefit analysis showed this to be justifiable due to the high-grade nature of the ore locked up in the pillars.Grout was initially planned to be injected in one pass through self-drilling anchors (SDA) in a 2.5 m pattern. Initial attempts to do this failed due to the SDA aperture and grout consistency. A modified method was employed using poly pipe installed into open holes that were drilled through the sill pillar and into the URF from below. Repeated application at each location ensured full grout consolidation. Drill holes were used to confirm grout thickness as well as add more grout. Design thickness was based on stress analysis.Despite different URF types being present due to varying quantities of fines, the process was similar for each area. The presence of paste in the URF of one target affected the quantity of grout it received.With a design thickness of 4–5 m of consolidation in the URF, depending on stope width and dip, each consolidated pillar (to date) maintained integrity during the stope operation. Some fall of material was anticipated; however, quality assurance / quality control (QA/QC) during grouting, staged stope extraction and careful blast design minimised fall of material.CITATION:Proudman, A, Isles, J, Lawolo, R and Forster, G, 2017. Rock fill consolidation for the extraction of sill pillar stopes at Toguraci gold mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 199–210 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

The Olympic Dam copper/uranium deposit was discovered in 1975 and subsequently commenced production in 1988 at a rate of 1.5 Mtpa using the sublevel open stoping mining method. In the following five years the operation underwent two optimisation programs that have increased mine output to the current rate of 3.4 Mtpa of ore. The pre-expansion requirements were annual development of approximately 10 000 m and the placement of around 500 000 m 3 /yr of cemented backfill. Previous to 1995 all hoisting was carried out by the Whenan shaft. The Robinson shaft was commissioned during that year to hoist increasing development mullock tonnages and to allow for increased ore hoist via the Whenan system. In 1996 WMC committed to expanding the output of the operation from 85 000 tpa (1996/97 budget) copper metal to 200 000tpa. The corresponding increase in mine ore production requires expansion to a nominal rate of 9.0 Mtpa. To achieve these increased tonnages, major hardware installations will include sinking of a third shaft capable of hoisting in excess of 9.5 Mtpa, a rail haulage horizon utilising automatic trains, expansion of the existing backfill plant to a production capacity of over 1.8 million m 3 /yr, increasing long term development rates to 15 000 m/yr and increasing the production drilling and blasting rates in line with the higher stope production output. This paper provides detail into the intended hardware (shafts, equipment, etc) of the mining system, and outlines the intended long-term operation and management of the operation. Of particular note is the background requirement of ensuring existing production targets are met to provide critical cashflows into the project during the period of expansion.

Jan 1, 1998

By G Boyd

The Nokomai Gold Mining Project commenced production in January 1992. The Project continues a history of mining in theNokomai Valley which extended from 1863 to 1942. L & M Mining Limited have held interests in the valley since 1980. In 1990 the Nokomai Joint Venture was formed with the Hore family, the owners of Nokomai Station, to mine a large alluvial gold resource in the valley. The mine is located adjacent to the Mataura Brown Trout fishery and required extensive environmental studies prior to granting of permits. The mine is budgeted to work for 20 months, processing 460 000 m3 of wash material. During this period, contract miners, Downer Mining Limited, will move in excess of seven million cubic metres of overburden from the deposit.

Jan 1, 1992

Drilling in the south of the Rapahoe Sector at Greymouth Coalfield has demonstrated the existence of thick coal seams in the upper Rewanui Member. Seam correlation is handicapped by complex lithostratigraphy and laterally variable geophysical log profiles. An integrated investigation of coal measure stratigraphy, coal petrology, and proximate analyses, suggests a feasible model whereby most of the major seam intersections belong to a single horizon. Coal properties vary laterally in response to original swamp conditions, which are believed to have ranged from well-drained to ponded. A new model of peat accumulation is proposed for the northern Rapahoe Sector, whereby Upper Rewanui peat accumulation occurred on a flood plain between the levees of a major south southwest-flowing fluvial system in the east and the toe of a western alluvial fan.

Jan 1, 1985

By P K. Smith, N G. Corner, R J. Ryan, D C. Arne, F P. Bierlein

The Reefton Goldfield has produced 67 t of gold from mesothermal vein gold deposits in metasedimentary rocks of the Greenland Group (Cambrian-Ordovician). The Globe-Progress deposit contributed 13.2 t (418,000 oz) of this total, predominantly from quartz veins. Recently a resource of 14 Mt at 1.96 g/t Au (27.5 t or 882,300 oz of contained gold) has been delineated at Globe-Progress in quartz vein remnants and disseminated within adjacent sedimentary rock, much of which has been locally brecciated. The breccias consist of quartz vein and sedimentary wall rock fragments set in a matrix of clay ærock flourÆ and sulphide (arsenopyrite plus minor pyrite and stibnite). Gold, closely associated with sulphide, is disseminated within the breccia. Disseminated gold also occurs in massive siltstone and sandstone adjacent to the quartz veins and breccias. Exploration drilling at Globe-Pogress, and several other Reefton prospects (e.g. Capleston, Merrijigs, Big River and Alexander River), has intersected zones of disseminated arsenopyrite carrying up to 20 g/t more gold. These mineralised sediments commonly have little or no megascopic quartz and or carbonate veining. There is little visible indication of former primary or secondary permeability for the passage of hydrothermal fluid and deposition of gold. However, porosity and permeability were formerly present in inter-granular pore spaces and microveinlets now filled with quartz, carbonate and K-mica. The Fosterville gold deposit in Victoria bears many similarities to the Globe-Progress deposit at Reefton, in terms of age, host rocks, hydrothermal alteration and mineralisation style. Many ofthe disseminated deposits in Nova Scotia, including deposits at North Brookfield and Moose River (Touquoy Zone), have similar characteristics to the Reefton disseminated mineralisation, but commonly have abundant pyrrhotite and some deposits have disseminated metal alloy grains of complex metallurgy.

Jan 1, 2000

By D Nobes, D Trumm, D Manhire, A OÆSullivan, M W. Milke

Coal seam gas (CSG) exploration and development requires the abstraction of significant amounts of water. This is so because gas desorbtion in coal seams takes place only after aquifer pressure has been reduced by prolonged pumping of aquifer water. CSG waters have a specific geochemical signature which is a product of their formation process. These waters have high bicarbonate, high sodium, low calcium, low magnesium, and very low sulphate concentrations. Additionally, chloride concentrations may be high depending on the coal depositional environment. This particular signature is not only useful for exploration purposes, but it also highlights potential environmental issues that can arise as a consequence of CSG water disposal. Since 2002 L&M Coal Seam Gas Ltd and CRL Energy Ltd, have been involved in exploration and development of CSG in New Zealand. Anticipating disposal of CSG waters as a key issue in CSG development, they have been assessing CSG water quality along with exploration work. Coal seam gas water samples from an exploration well in Maramarua closely follow the geochemical signature associated with CSG waters. This has helped to identify CSG potential, while at the same time assessing the chemical characteristics and water generation processes in the aquifer. Neutral pH and high alkalinity suggest that these waters could be easily managed once the sodium and chloride concentrations are reduced to acceptable levels.

Jan 1, 2005

The New South Wales coal industry is a highly mechanised well organised industry which has developed from an annual production of slightly less than 13 million tons in 1950 to over 33 million tons in 1969. Although continuous miners were not introduced into the mines until 1950, by Jillle 1969 the percentage of coal won by these units was 87.3. The paper describes mining conditions in the various coalfields of the State, their complexities and problems and how these have been dealt with. The introduction of fully mechanised long wall faces has presented a challenge which has been accepted and descriptions of systems in use are discussed. Major expansion of the industry is anticipated to meet the requirements of the growing Australian steel industry, for local power generation and to meet the increasing demands of overseas markets.

Jan 1, 1971

While the new Minister of Economic Development sends his apologies at being unable to speak at this Conference, I am delighted to present on his behalf. The Ministry of Economic Development is not only responsible for managing the Crown mineral estate, but also for developing initiatives and policies to promote regional economic development and for managing the GovernmentÆs broader economic development strategy. IÆd like to talk to you today about the critical links that need to exist between these three areas.   I am going to start with a question for all of you. What do these towns have in common? +        Waiuku, +        Thames, +        New Plymouth, +        Nelson, +        Greymouth, +        Arrowtown, +        Reefton, +        Palmerston, and +        Dunedin.   The answer is minerals. These towns were nearly all founded on the back of minerals and mining. In the case of Greymouth it was gold that brought the people to the mouth of the Grey River and it is coal that sustains the town.   In 1870 the town of Shortland had 20 000 people, 90 hotels and was twice the size of Auckland. We now know Shortland as Thames, and of course Auckland is considerably larger. One wonders whether the good folk of Shortland suffered from ætraffic jamsÆ with 90 pubs to navigate between. Gold mining in the Aorere River near Collingwood led early entrepreneurs to develop the land surrounding Nelson as a food basket to sustain the mining population. Nelson is still thriving on this legacy today. The town of Palmerston was founded in 1862 as a stopping point for gold miners heading into central Otago. The gold rush made Dunedin New ZealandÆs first highly industrialised city. Reefton on the West Coast was the first town in New Zealand to have electric lights and in the recent past we were wondering whoÆd be left to turn them off. New Plymouth, and Waiuku are still known as energy and mining centres.   By contrast once thriving towns like Capleston, Canvastown and Blackball are just names on a map now, and at the extreme you have places like Waiuta which has been reclaimed by the West Coast forest. Queenstown was built off the back of the gold rush, but by 1900 with the gold gone, only 190 people lived there yet Queenstown has managed to rebuild itself thanks to some other stunning natural assets. These examples help illustrate three key points that I am sure will each be extensively linked with our minerals and mining industries. First, NZÆs development and that of its regions has been, and continues to be, inextricably linked with our minerals and mining industries.   Second, things change. Sectors, regions and countries must continually adapt and improve if the are to avoid the fate of the Waiutas of this world. And third, the development challenges faced by NZ and its mining industry in the 21st century are vastly more complex than in the past. Governments and industry alike must balance and respond to a range of domestic and international environmental, cultural, economic and other interests and considerations. If you thought of your industry as æjust digging holes in the groundÆ then you may as well simply stick your head in one!

Jan 1, 2005

By H P÷llmann

Calcium aluminates, calcium aluminate ferrate and calcium aluminate sulfate were synthesised by solid-state reaction, sol-gel method, a self-combustion method and by a polymeric precursor process. For chemical sintering methods the base chemicals CaO, CaSO4, Al2O3 and Fe2O3 were used. As precursors for sol-gel synthesis metal nitrate hydrates and Al2O3-Sol were used. In order to synthesise pure phases by a self-combustion reaction glycine was used as fuel and nitrates as metal components. In the polymeric precursor process metal nitrates and diluted H2SO4 were used as metal components and the resin was made using citric acid (C6H8O7) and ethylene glycol (C2H6O2). Precursor phases synthesised by these different methods were sintered step-by-step in order to investigate the crystallisation. Further on single phases were hydrated and their hydration behaviour was studied by heat flow calorimetry, X-ray diffraction and cryo-transfer scanning electron microscopy. Due to the different synthesis procedures different hydration reactions and microstructures of the phases will be shown.

Jan 1, 2008

By M F. Gazley

The amphibolite-facies metabasaltic rocks of the Mine Mafic Package at Plutonic Gold Mine, Marymia Inlier, Western Australia, contain an estimated total endowment of 12.2 Moz of Au, which includes 4.71 Moz of past production and 2.77 Moz of reserves and resources; the remainder comprises lower-grade inventory. Over 65?000 multi-element analyses of whole-rock core and face channel samples from the underground workings of the deposit have been collected by portable X-ray fluorescence (pXRF) using a handheld Innov-X Omega pXRF unit. The analyses were performed on pulverised samples through paper bags, and were corrected using a pulverised, matrix-matched, reference standard. This method of data correction compares favourably with conventional XRF analyses performed on the same samples.A preliminary study based on pXRF analyses from a small number of drill holes found that a geochemical stratigraphy was evident in the pXRF data, and that this stratigraphy strongly controlled the location of Au mineralisation. The present study incorporates a much larger pXRF data set that samples a greater volume of diamond drill core and face channel samples and presents the data in a three-dimensional (3D) framework.This data set allows an investigation of the mineralogy of Au mineralisation with varying geochemical associations across the deposit. Historically, there has been a strong relationship identified between As and Au, which has caused issues with metallurgical performance, rendering some areas of the deposit only marginally economic. Utilising seamless data integration of the pXRF data set allows for recognition of the different styles of Au mineralisation using elemental concentrations and ratios from the multi-element analyses (Au:As, Au:As:Cu, As:Cu vs. K:V), and to visualise the distribution of these different mineralogical associations in 3D. The results of the 3D modelling and geochemical characterisation of the different styles of Au mineralisation are currently the focus of an extensive metallurgical testing program, the preliminary results of which are presented here.

Aug 22, 2011

By M P. Simpson

Forty one whole rock samples from the Gold Cross low-sulfidation epithermal Au-Ag deposit have d18O values that range from 4.4 to 9.3 per mil, with an average value of 7.0 per mil. Unaltered and weakly altered rocks have d18O values greater than eight per mil, and the orebody is surrounded by samples that are depleted in 18O. A strongly silicified sample adjacent to the Empire Vein System has a d18O value of 9.0 per mil, similar to previously reported analyses of vein quartz (7.0 to 11.7ë, average 9.4ë). This suggests that, in detail, Golden Cross may have a zone of 18O-enriched wall rocks in the core of the deposit, adjacent to the main underground veins. Although some workers have suggested that stable isotope geochemistry may provide useful information for epithermal mineral deposit exploration, at Golden Cross this is not the case. Alteration minerals, major elements and trace elements all define larger, less ambiguous halos than the zone of 18O-depleted wall rocks.

Jan 1, 2001

By R P. Langford, T A. Moore

Indonesia over the last 15 years has experienced a surge in coal exploration, which has led to the development of a major export industry. This coal exploration has improved the understanding of the geology of the Indonesian coal deposits. The main economic coal deposits are of Eocene and Miocene to Pliocene age, which mainly occur in Kalimantan and Sumatra and were formed from peat deposits in an equatorial paleoclimate similar to that prevailing today. Some of these peats were domed peats, which grew above the normal water tables, under a climate of year-round rainfall; these peats grew above the level at which waterborne mineral matter can enter the system, resulting in low ash and sulphur, and locally very thick coal. It is believed that such peats have formed the unusually thick, low ash, and low sulphur Miocene coals of Indonesia. Coal deposits of Eocene age are typically characterised by thinner seams, with relatively higher contents of ash and sulphur. The Miocene coals and Eocene coals both appear to have formed in lacustrine, coastal plain or deltaic depositional environments, similar to the modern peat-forming environments of eastern Sumatra and parts of Kalimantan. The Eocene coals formed mainly in extensional tectonic settings. Miocene - Pliocene coal deposits formed in a range of tectonic settings; the most significant, for large economic coal deposits, are the foreland basin setting of the large Neogene coal deposits of South Sumatra.

Jan 1, 1999

A review is presented of developments in mill liners to improve performance in terms of wear, impact, as well as mill grind and throughput. These developments are in response to the growth in size of SAG mills and the use of larger ball loadings and ball sizes in modern SAG milling practice. Shell liner developments include specific mechanical design features such as special bolting, directed metal flow to prolong liner life and a focus on the process aspects of the mills to provide more effective grinding motion with reduced wasteful ball-on-liner impacts. Grate design developments aim to provide high throughput of material, especially in the larger size fractions, while providing good impact and wear life. Curved pulp lifters are designed to ensure, at high mill speeds, complete discharge of coarse solids from the mill.

Jan 1, 1999

Thickener Modelling - Incorporating Shear Effects

Sep 13, 2010

The Greymouth Coal field is situated on the West Coast of New Zealand's South Island and has been mined for coal for more than 120 years. The area covered in this paper is within the Rapahoe Sector of this field and contains >200 million tonnes of low ash, low sulphur, bituminous rank coal. Paper No 6, presented to the 19th Annual Conference of the New Zealand Branch of The Australasian Institute of Mining and Metallurgy in Christchurch in August 1985 by R G Bowman, explained 'A Geologist's View' of the 'Economic Potential of the Greymouth Coalfield', and describes previous geological assessments of the Rapahoe Sector.

Jan 1, 1989

By Jagger ND

Pressure filters were found to be necessary to produce Elura silver/lead and zinc concentrates at sufficiently low moisture contents for bulk cargo shipment by sea to smelters.The difficulty in obtaining low moistures was due to the fine primary grind, 80% passing 45 microns, and resultant fine concentrates, 97% passing 45 microns.The filtration system was designed to filter up to 90,000 tonnes/year silver/lead concentrates and up to 130,000 tonnes/year zinc concentrates.This paper details the preliminary test work to select Larox automatic pressure filters, and the commissioning and operation of these filters to achieve design criteria for both concentrates. The design criteria for both concentrates have been bettered due to the concentrates being coarser than the design sizing.

Jan 1, 1985