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A tectonic interpretation of the Coromandel Peninsula which suggests that the basement underwent tensional collapse at its northern and southern ends would permit more ready penetration of late stage magmatic fluids. This hypothesis is consistent with regional trends of the chloride content of low grade geothermal waters and of the yield of gold and silver per unit weight of quartz worked. The consequences of such a model are that mercury should not only be a good pathfinder for Coromandel gold, but that it should be correlative with ratios of base metals high in the zoning or paragenetic sequences to those lower in the sequences. This is demonstrated successfully in an area of mineralisation in the southern Coromandel.

Jan 1, 1987

Geostatistical methods have become well established in the last two decades for the evaluation of ore reserves in base metal, industrial minerals, coal and gold deposits of the Witwatersrand type. However, there has been considerable debate about the applicability of geostatistical techniques when applied to vein-type gold deposits with hydro or epithermal mineralisation. The main problems stem from a lack of spatial continuity and the highly erratic sample values that characterise these deposits. This paper reviews some of the current geostatistical techniques that are applied to the evaluation of gold prospects.

Jan 1, 1992

By R G. Moreby, S Bluhm, FávonáGlehn, C Pascoe

Resolution Copper Mine in Arizona, USA, is planned to be a 2000 m deep panel cave mine with virgin rock temperatures exceeding 80¦C in rock with high crystalline silica content, resulting in a very challenging ventilation and cooling system design. This is one of the largest copper orebodies ever found and, with a planned rock production rate of 120 kton/day. The project is currently in its prefeasibility phase and the paper discusses features of the ventilation and cooling system design which includes multiple ventilation shafts with total primary ventilation flow of about 3000 m3/s and both surface and underground refrigeration plants producing more than 140 MW refrigeration capacity. The cooling system features large surface bulk air coolers chilling all downcast air supplemented by an underground secondary air cooler system and a chilled service water system. This will be a very challenging mine to ventilate and cool but this work has demonstrated that it will be technically achievable with the application of existing technology.CITATION:Bluhm, S, Moreby, R G, von Glehn, F and Pascoe, C, 2013. Life-of-mine ventilation and refrigeration planning for Resolution Copper Mine, in Proceedings The Australian Mine Ventilation Conference , pp 125-138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By M Hawkins

The Clem Jones Tunnel (formally known as the North-South Bypass Tunnel), a A$2.88 billion road tunnel project in Brisbane, Queensland, was successfully completed almost seven months ahead of schedule. The project included two parallel 4.7 km long road tunnels, 740 m of intermediate roadway access ramps and two auxiliary ventilation tunnels. The tunnels incorporate intelligent tunnel systems, best practice fire and life safety standards and typical civil tunnel elements.Over the duration of the project the Parsons Brinckerhoff (PB) and AECOM (formally Maunsell) design joint venture (MPB) were Lead Designers to the Leighton Contractors and Baulderstone Bilfinger Berger Joint Venture (LBBJV). Construction of the toll road commenced in September 2006 and was completed in March 2010, with the tunnel opening then. Contributing to the success of this project was the continued support the lead designers gave throughout the construction period.This paper will focus on some of the structural elements that contributed to the success of the project – in particular the cable tunnel structure, a small precast, culvert shaped element under the pavement of the mainline tunnel, and the fit-out of the Gibbon Street shaft which were designed to be constructed in a combination of precast and in situ concrete.The cable tunnel was incorporated early in the design phase and runs the length of much of the tunnel. This paper will outline the challenges faced by the designers with implementing this system which provided significant construction advantages, among which were being able to install a separate ventilation duct during construction and to start fitting out the mechanical and electrical conduits and drainage system while tunnelling was still underway.The Gibbon Street shaft had a length and width of 20 m by 40 m and an overall depth of 38 m. A 20 m high structure of precast and in situ concrete was constructed in the base to accommodate mechanical and electrical equipment and provide a take-off access for the southern ventilation tunnel. The construction purpose for this structure was to provide a junction between the tunnel boring machine (TBM) and the roadheader-style tunnels, a staging platform for commencing the roadheader tunnelling, and a platform where the TBMs could be dismantled and removed.The design was assessed and reviewed many times throughout the construction process to address the needs of each of these stages. Innovative use of precast concrete was used to minimise construction time.Additionally, the designers provided support to the construction team from the time of design completion through to the tunnel opening. This meant that the changes to the design and adjustment of construction loadings could also be assessed. The fi nal outcome resulted in an efficient construction sequence and a project that has provided an excellent outcome for the client, stakeholders and community.

Mar 8, 2011

Increasing demands on quality of metallurgical grade alumina and for lower production costs led to the development of a new fluid bed calcining process. The process, jointly developed in Germany by Vereinigte Aluminium Werke A. G. and Lurgi Gesellschaften m.b.H., takes advantage of modern chemical engineering methods such as counter-current flow of combustion air and solids, direct heat-exchange between combustion air and fine solids, and near stoichiometric combustion of oil in a fluid bed. Using a two-stage Venturi-type suspension preheater for heat-recovery from combustion flue-gases, the circulating fluid bed technique with internal oil combustion at 220°F for the calcining step and a five-stage fluidized bed cooler for heat-recovery from calcines, the process gives an outstanding heat-efficiency. In a first industrial plant for 560 sh. tons/day of alumina heat consumption figures of less than 1·400 B.T.U./lb Al203 g were achieved.

Jan 1, 1972

By M Jacobs

This abstract discusses a heap leach copper mine that was failing to perform and as a result was not meeting targeted production. The mine had numerous technical challenges including: high water inflows, low levels of geotechnical monitoring, performance issues with mining, resource model and grade control reconciliation issues, and unexplained low levels of performance from the heap leaching operations. A team from various organisations with specialist skill sets including: a forensic accountant, the owner’s representative and a mining engineer, was arranged to visit the site. The task was to investigate the situation and determine what could be done to turn the performance of the mine around. After an initial assessment in late 2018, efforts were directed to better understanding the operations and improving the performance of the site through preventative management. A key part included the creation of production forecasts that could be achieved that would help restore confidence in the operations. Uncertainty in the mine achieving production forecasts and the performance of the heap leaching operations were contributing to the decline of the operations. Investigations uncovered the fact that while the resource model could reliably predict total copper, a lack of sequential leach data meant the accurate prediction of soluble and insoluble copper species, both important for heap leaching, was difficult to do with any degree of certainty. The crushing and mining contractors also appeared to have suffered somewhat from a lack of management by the owner’s team and performance had affected the production of copper. Collaboration and management were used by the team to understand and stabilise the operations. Ongoing collaborative efforts by the management team, site personnel and contractors resulted in a positive outcome for the owners and their mine – and could at yours.

Jun 22, 2022

Exploring the Breakage Environment in Mills with Discrete Element Methods

Sep 13, 2010

By D Craw, P Upton

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Southern Alps of New Zealand and the mountains of Taiwan are both young transpressive orogens characterised by rapid uplift and exhumation, high heat flow and vigorous surface processes. Comparing and contrasting the two provides an ideal framework through which to explore the structural and lithological controls on fluid and gold mobility during collisional deformation. Both have two fluid flow systems centred about their drainage divide with shallow topographically-driven meteoric water above a deeper flow system dominated by mineralising rock-exchanged fluids. Despite similar tectonic settings, the distribution of heat flow, hot springs and veins in the two orogens are different. Taiwan has higher heat flow, distributed hot springs and localised veining whereas the Southern Alps have a narrow heat flow anomaly, localised warm springs and widespread veining. We use three-dimensional numerical models to evaluate key parameters that affect fluid flow and gold mineralisation. Models show that differences in crustal strength and thickness affect the locus, scale and rate of crustal fluid flow and hence influence gold deposition at a variety of scales. We explore how surface topography can lead to localised changes in the stress state, facilitating the switching of principal stresses and hence vein orientations.CITATION:Upton, P and Craw, D, 2015. Modelling structural and lithological controls on the mobility of fluids and gold in orogenic belts – examples from New Zealand and Taiwan, in Proceedings PACRIM 2015 Congress, pp 189–192 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The West Coast region of the South Island is situated astride the Pacific û Australian plate boundary zone. The most significant component of this zone is the Alpine Fault. A variety of reconstructions of the pre-Alpine Fault plate tectonic configuration of the New Zealand continental area have been attempted over the past 25 years or so. Most of these have not been closely constrained by a regional compilation of field data related to the age and horizontal displacement history of the Alpine Fault. A model in which the Alpine Fault was initiated no earlier than the interval 18 - 16.5 Ma (B.P.) is proposed, a significantly younger age of inception than has been widely accepted as the onset of dextral displacement along the plate boundary through the South Island. A subsequent history of displacement is presented consistent with the West Coast basin stratigraphy. The alluvial gold content of some parts of the Miocene to Pleistocene conglomerate sequences is also discussed.

Jan 1, 1996

Study on Treatment of Wastewater Containing Heavy Metal Ions Using Modified Oceanic Cobalt-Rich Crusts

Sep 13, 2010

By J C. Waters

Pseudoclastic hydrothermal alteration textures occur within quenched coherent dykes forming part of a subaqueous dome complex (~4 Ma) onPonza Island, Italy. These textures are similar to those observed in considerably older (~500 Ma) subaqueous volcanic rocks at a number of localities throughout the Mount Read Volcanics in Tasmania and elsewhere in ancient volcanic sequences of this type in Australia. This is significant because the processes of formation, hydrothermal alteration and secondary mineralisation of ancient volcanic sequences may be better understood if we can make comparisons with modern analogues. Observations at Ponza imply that these pseudoclastic alteration features form synvolcanically or immediately after dyke emplacement and lava extrusion. This is compatible with scenarios presented for their formation in ancient sequences in the Mount Read Volcanics, Tasmania.

Jan 1, 1995

Perception has the unfortunate habit of becoming reality. Urban inhabitants unfortunately do not regard mining as a legitimate or desirable business, despite its contribution to Australia's export income (+A $8,000 million, being nearly a third of all exports); share of GDP (it is 4.5%); and the fact that its presence fills up all the empty spaces northwest of the Adelaide-Melbourne-Sydney-Brisbane crescent of inhabitation. The huge economic contribution of Australia's minerals industry, resulting from providing more than half of merchandise exports (Figure 1), is achieved by employing only some 2% of the national work force (Gaulton, 1997). Unfortunately, the minerals industry's critics generally oppose exploration on the basis that what you don't know will not hurt you. It is the 'do-not-confuse-me-with-facts' philosophy or 'ostrich syndrome', which somehow crudely assumes that mining practices have stayed in the style popular circa late 1800s. Somehow ignorance really is bliss for these idealistic believers, who are reminiscent of the members of the Flat Earth Society!

Jan 1, 1997

Bubble Load Measurements in Flotation - A Critical Review of Current Practice

Sep 13, 2010

By C A. Fleming

Gold extraction is largely driven by mineralogical factors, which often cause gold losses to various tailings. Mineralogical factors affecting gold recovery include grain size and shape, surface coating or rimming on gold particles, the presence of cyanide or oxygen-consuming minerals or preg-robbers, the presence of slow-dissolving gold minerals and the refractory nature of submicroscopic gold. Among these factors, locking of fine gold particles in sulfide, silicate and other minerals, either as visible, fine-grained gold inclusions and/or as invisible submicroscopic gold, is by far the most common factor leading to poor gold recovery in gold ore processing. This paper discusses the mineralogical characterisation of gold lost in tailings and its metallurgical implications. The techniques used in characterising the un-recovered gold are also briefly introduced.

Jan 1, 2007

Polyacrylamide flocculating agent has been used in the Leaching Division 'of the Risdon Works of the Electrolytic Zinc Company of Australasia Limited since October, 1960. The number of thickeners in the continuous thickening stage was thereby reduced from eight to three. There has been an increase of 25 per cent in throughput and a reduction of solids in thickener over-flow from 3-4 g/l. solids to 0·5 g Ir. solids. Reagent addition has been at the rate of 0·25 lb Separan NP10 per ton solids.Additionally there has been a gain of 3 per cent in current efficiency as the direct result of the addition of Separan NP10 to purified cadmium sulphate solution priOl; to electrolysis for cadmium metal. A smoother deposit has resulted and it has been possible to increase deposition time between strippings from 47 to 71 hr. However, there has been a slight increase in the lead content of the cadmium metal produced.The use of Separan NP10 to settle copper bearing residue in a batch process stage has resulted in a five-fold increase in settlement rate and a reduction in purification cycle time.INTRODUCTIONThe Electrolytic Zinc Company of Australasia Limited, Risdon, Tasmania, produces zinc by electrolysis of purified zinc sulphate solution, the raw material being zinc sulphide concentrate. In the Risdon process (Van Arsdale, 1953; J ohnstone, 1953; Ross, 1949) the compound zinc ferrite (ZnO.Fe203) is formed during the concentrate roasting stage. When the roasted material is leached in dilute sulphuric acid the zinc ferrite is not attacked, and it remains as part of the insoluble leach residue, of which it may form as much as two-thirds of the whole. The remainder is mainly unroasted zinc sulphide, unleached zinc oxide, lead sulphate, gypsum, silver compounds etc. The zinc in the residue may be 10 per cent of that in the original concentrate.Continuous thickeners are used to recover the valuable residue from the impure zinc sulphate solution and the...

Jan 1, 1963

By M Laxman, A Kundu

After multiple tailings dam failures in recent times, the owner organisations have made increased efforts to step up the governance systems to industry best practise in the design, construction and operational management areas. The measures include but are not limited to, site investigation, rigorous peer review (both internal and external), certification through appropriately qualified personnel and improvement in operational management practises. While a lot of focus is on design and operational practices, the construction stage requires adaptation (both in terms of materials and approved design) and immediate decision making on site. Work undertaken in these areas is mostly irreversible and sometimes poses serious threat to the future TSF raise/ expansion planning and may lead to reduced life of the TSF and additional risk to the Owner.This technical paper will discuss some challenges and highlight the importance of appropriate processes to achieve a successful construction regime. The process will include a robust quality control/ quality assurance process, a team of designer-constructor-owner with suitable skills and technical understandings and robust documentation of the entire construction process from day 1 to the completion of construction.CITATION:Kundu, A and Laxman, M, 2018. Robust construction and quality assurance culture for tailings storage facilities – equally important as robust design and review practice, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 111–116 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By M I. Pownceby, M A. Rhamdhani, W J. Rankin, G Brooks, I R. Ignacio

Steelmaking has a significant contribution in producing greenhouse gases and there is a worldwide push towards decarbonising the process. One of the approaches to reduce CO2 emissions is to use hydrogen in the blast furnace (BF) as the reductant gas. However, hydrogen reduction is an endothermic reaction, bringing changes to the temperature distribution in the BF. Understanding iron ore sinter mineralogy and reducibility under a hydrogen atmosphere is essential to optimise the process. In this study, sinter analogues in the Fe3O4-CaO-SiO2 (FCS) ternary system together with industrial sinters were reduced in H2-rich and CO atmospheres and the resulting reducibility and associated mineralogical changes were observed. Results show that magnetite-lime-silica (MLS) sinter analogues had similar reduction rates under H2 and CO, and also higher reducibility than most of the industrial sinters, suggesting that magnetite sinters could be used efficiently in a conventional or hydrogen blast furnace.

Sep 18, 2023

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

By S Christensen

In August 2001 the Minister for Conservation declined an application by GRD Macraes for an access arrangement to enable work at the Globe Progress Mine near Reefton. In her decision, Ms Lee said:æI have considered whether potential compensation and the proposed safeguards against some of the adverse effects are sufficient to outweigh my concerns as to the loss of conservation values, consistency with the objectives of the Conservation Act, the purposes for which the land is held by the Crown and, to a lesser extent, the North Westland Regional Management Plan. I do not think they are sufficient. To my mind, my concerns as to the consistency with the objectives of the Conservation Act, the purposes for which the land is held and the loss of some conservation values in particular, outweigh any potential compensation and possible mitigation of adverse effects.Æ Commenting on the MinisterÆs decision Guy Salmon of the Ecological Foundation stated that the Minister should have invited the applicant to provide a 10 000 hectare pest-free wildlife sanctuary as part of the æpriceÆ for obtaining that access. However,æfor many people of green persuasion, it has become fashionable to say no every timeàthose who really have the well-being of the environment at heart, will want to look carefully at the bigger picture of environmental restoration needsàThe deciding criterion: the mining company should show that its involvement on conservation land would produce a net conservation gain. That is a criterion that creates the right incentives for win-win-win solutions on conservation land.ÆThis paper considers whether the concept of off site mitigation is one which fits within the current legal regime. Two questions arise:Can such mitigation/compensation be legally considered in access arrangements or required as a condition of resource consents? Is this a realistic option for industry to be pursuing?

Jan 1, 2002

By E J. Cowan

Efficiency demands that mine geologists devote the most time to tasks where they can have the biggest effect on production. One of the most time-consuming tasks is geological interpretation of the orebody and turning this into a block model for the planning engineers.The current best practice for mines that require a geologically constrained resource model involves capturing the interpretation of geologists as three-dimensional (3D) wireframes. However, there is significant overhead in the production of valid wireframes from sectional and plan interpretations. This overhead consists of the mundane tasks of digitising polylines, then building 3D wireframes and validating them. While software can simplify this task, the current process is not the best use of a geologist’s time. Under time pressure exerted by planning engineers and the time required for modelling from polylines, geologists are forced to roll-up the presence of other elements or impurities into the interpretation and encode them in the polylines, even though it is often desirable to consider these other factors separately.While it might seem unlikely that mine geologists can produce constrained geological models without the intermediary of wireframes, the technology to accomplish this is getting closer.In this paper, the results of a trial at the Savage River magnetite mine, which is owned and operated by Grange Resources Ltd, are reported. The trial was for a ‘direct-to-block’ implicit geological modelling method. The focus was on creating a geological attributed block model from drill hole geological log data; resource estimates were not determined. The categories modelled were air, waste, low-grade ore, medium-grade ore, and high-grade ore. The block model outputs either resulted in a proportional block model (categories expressed as percentages within equivolumetric blocks) or a sub-blocked model (parent block and one sub-block), which is the preferred block model output at the Savage River mine. When compared to the traditional best practice modelling method, which takes 43 work days, the wireframe-free modelling method took only 26 hours from initial modelling, using both exploration and grade control data. An update using appended drill hole data is achievable within one day. These results represent time savings of more than one order of magnitude compared to the traditional workflow, and, as such, these figures merit serious consideration for the use of the direct-to-block modelling approach at other operations.With these time savings, geological and estimation models can be kept updated constantly; geologists will not need to set aside two months for quarterly or half-yearly modelling of the drill hole data for resource review. Such dramatic time savings will allow for the better use of highly skilled geologists, who are in short supply in the current market, and will also impact directly on downstream mining engineering workflows.

Aug 22, 2011