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By de Brodtkorb MK

Late Cenozoic ore deposits "Precious and base metal-rich" and " Sn-Ag-polymetallic"of Northern Puna are associated either with Middle Miocene dacitic volcanic-dome complexes or with Upper Miocene dacitic-andesitic volcanic centers. Ore mineralogies and their related volcanism are discussed. A strong link is observed between the Cenozoic Metallogenetic Province of Northern Puna and the Southern Bolivia Tin and Polymetallic provinces.

Jan 1, 1995

By S Pollak, A Amon

This paper describes the current and finished design work which has been performed for shallow rock station caverns for New York CityÆs first new subway construction in 60 years. A new robust, sophisticated, design procedure has been developed for two up to 30 m wide caverns, with overburden of less then 12 m, and rock cover to span ratios (C/S) in the order of 0.25. The design is based on empirical input parameters like the Q-value, rock mass rating (RMR) values, rock mass class after Cording (1984), cover to span ratios, which have been validated by the use of structural computer models as well as two- and three-dimensional numerical discontinuum models. The design approach is a staged approach using first principles, empirical models and non-linear FEM and DEM models. In addition, the paper describes the factors and circumstances why shallow caverns have been selected instead of cut-and-cover structures and why all the underground station structures have been developed as drained structures.

Jan 1, 2008

By A V. Ozsever

The selectivity in flotation columns involving the separation of particles of varying degrees of floatability is based on differential flotation rates in the collection zone, reflux action between the froth and collection zones, and differential detachment rates in the froth zone. Using well known theoretical models describing the separation process and experimental data, froth zone and overall flotation recovery values were quantified for particles in an anthracite coal that have a wide range of floatability potential. For highly floatable particles, froth recovery had a very minimal impact on overall recovery while the recovery of weakly floatable material was decreased substantially by reductions in froth recovery values. In addition, under carrying-capacity limiting conditions, selectivity was enhanced by the preferential detachment of the weakly floatable material. Based on this concept, highly floatable material was added directly into the froth zone when treating the anthracite coal. The enriched froth phase reduced the product ash content of the anthracite product by five absolute percentage points while maintaining a constant recovery value.

Jan 1, 2005

By Benson R. P

Building a new tunnel to accommodate CN North America's needs or double stacked container traffic for the next 100 years represents new and unprecedented challenges. Innovative approaches to contracting, especially the Negotiated Compressed Process (NCP), TBM design, project management, and the regulatory and approval process, were all required to deliver a new tunnel to meet the needs of CN North America within the approved completion schedule of 33 months compared to a traditional approach of 45 to 48 months. The NCP resulted in trimming a full 12 months from the project schedule with an anticipated saving of direct and indirect costs.

Jan 1, 1993

By A Gray

Physical separation features in almost every mineral processing circuit. The category encompasses a broad range of techniques and technologies including hydrocyclones, gravity concentration methods (including jigs, spirals, centrifugal concentrators, tables, heavy media separators) and thickeners, all of which make use of the inherent density differences between two mediums. It is also possible to include flotation, magnetic separation, and ore sorting in the physical separation category.However, opportunities for enhanced physical separation performance can now go beyond the common practice of optimising unit operations. Improved options exist for feed preparation ahead of the physical separation stage, enabling higher performance and lower cost outcomes for physical separation flow sheets and technologies.The use of new applications in breakage technologies combined with mineral liberation analysis to optimise liberation prior to the physical separation stage provides options for preconcentration and gangue rejection as well as better separation efficiency. The use of low cost gangue rejection and preconcentration can be an intermediate step between mining and processing that allows processing of lower cut-off grades from the mine whilst delivering higher grades to the mill.Optimising flow sheets and technology performance requires detailed understanding of particle size and shape distributions as well as liberation characteristics to suit the particular separation unit, combined with knowledge of the available technologies, their capabilities and the economic impact across the whole mine cycle.CITATION:Gray, A, 2017. The role of liberation in physical separation techniques, in Proceedings MetPlant 2017, pp 147–156 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

Gold was discovered at Waihi in 1878. In 1987 the modern Martha Mine opened in the middle of the town of Waihi. Newmont Waihi Gold as the current licence holder has been operating the mine since 2000. The current open pit was scheduled to stop production in mid 2006. An underground mine is currently being developed to the east of the town.   In 2001 serious subsidence issues from historical underground mine workings outside the mining licence and the forecast closure of the open pit acted as a catalyst for the development of new communication initiatives.   In this context Newmont Waihi Gold and the Hauraki District Council initiated a community consultation process with the people of Waihi. The Waihi Community Consultation Committee (WCCC) was established in May 2003. After an initial brief to act as a forum for community participation in closure and rehabilitation of the Martha Mine, the group quickly took on a much more proactive role working towards the long-term social, environmental, cultural, economic and spiritual sustainability of Waihi.   In the course of over three years of meetings all groups represented on the committee have presented their views, developed ideas and established an organisational structure to bring those ideas to fruition. The challenge now is to work together to consolidate likely options, seek sources of funding, produce business proposals and implement the plan for the future of Waihi.   This paper backgrounds the experience to date and describes the outcomes of the process. For more detail on process considerations this paper should be read in conjunction with Part C by process facilitators, T Clark and S Stewart. For more detail on progress towards the groupÆs goals and future possibilities, this paper should be read in conjunction with Part B by Vision Waihi Trust CEO, E Morrow.

Jan 1, 2006

By R B. Wanty

Historically, most investigations of biogeochemical cycling in acid rock drainage systems involved synoptic sampling over longer time periods (one sample per week or month) or intensive time series studies over a few hours or days. However, many important episodic loading events, such as seasonal meltwater and storm events occur on timescales that are rarely observed by these traditional sampling approaches. Monitoring these transient processes, which may contribute the bulk of the annual metal loading, is essential for accurate assessment in acid rock drainage areas. Recent work also has demonstrated dramatic diel (24 hour cycle) variations in trace metal concentrations in response to diel changes in temperature, pH, oxygen, and photochemical cycling (Brick and Moore, 1996; Nimick et al, in prep). To characterise a system that may respond to diel, seasonal, and episodic events, a monitoring program must sample at a frequency that captures the details of these major forcing events. We developed two novel instruments, the Zn-DigiScan and the DigiSampler to examine low and high frequency temporal changes in acid rock drainage areas. The Zn-DigiScan is a battery powered real time in situ chemical analyser designed for long-term deployments with hourly analyses of Zn. Stream physical parameters (temperature, conductivity, dissolved oxygen, pH, turbidity, etc) were measured every 15 minutes with a water quality sonde. The DigiSampler was developed for the long-term daily sampling of biogeochemically active elements and can take either discrete samples or samples integrated over 24 hours. The DigiSampler collects 2 ml samples in a Teflon coil which are separated by 0.2 ml nitrogen bubbles. The sample coil is returned to lab and the 2 ml samples are diluted 1:10 and analysed for trace metals by ICP-MS. Initial results from a three-day deployment at Fisher Creek, MT, USA have successfully demonstrated the ability of the Zn-DigiScan to record Zn concentrations at levels below 100 ¦g/L. Zinc concentrations measured at 30 minute intervals in Fisher Creek showed a diel cycle with low values of ~25 ¦g/L in the late afternoon and increasing to ~60 ¦g/L by early morning. Zn concentrations were inversely related to temperature and pH, suggesting that temperature and pH dependent adsorption was the main factor controlling diel Zn fluctuations. Initial deployment of the DigiSampler also was successful, revealing diel cycles in Zn, Cu, and Mn. Comparison of trace metal samples collected by the DigiSampler showed good agreement with samples collected by an Isco automated water sampler, demonstrating that the DigiSampler can collect clean samples for trace metal analysis at the low ¦g/L range.

Jan 1, 2003

Iron from the blast furnace constitutes the starting point in steel production and any increase that can be made in iron production will bring about important repercussions in a long line of processes. Coke constitutes a major item in furnace operation and consumption at the Port Kembla Works of Australian Iron & Steel Ltd. has been approximately 1,850 lb. per ton of iron produced on ore practice, or 3,000 tons per day.For many years coke quality has been subject to much criticism by furnace operators throughout the world, sometimes with little real grounds. Whatever the merits of previous arguments, and they were no doubt two-sided, the development of bigger furnaces has focused attention on coke strength. At the same time a decrease in the quantity of good quality coking coals available to many plants has stimulated research in this field.Extensive coke research has been carried out overseas, and in Australia the.B.H.P. Organization is now actively doing likewise in its Central Research Laboratories at Shortland near Newcastle, N.S.W., and works research groups at Newcastle and Port Kembla Steelworks. Similar work has been initiated in the beehive coking industry. Such work is in its infancy and this paper will outline the direction of the activities at Port Kembla rather than propound specific solutions.At Port Kembla good quality coking coals are readily available from the IIIawarra coalfield. The seams generally mined for coking are Bulli and Wongawilli and to a much smaller extent Tongarra. Characteristics of these coals appear in Table 1.

Jan 1, 1958

By U Berg, T Neumann, Y Song

Eutrophication of water bodies is one of the most severe environmental problems worldwide. It is well known that the availability of phosphate, as the limiting nutrient, is crucial for increased primary production and eutrophication. Calcite exhibits positive surface charge in most natural waters and can therefore be used for phosphate immobilisation. In this study, sorption experiments were performed in order to test different calcite materials regarding their suitability for use in restoration of eutrophic lakes. These short-term experiments were performed under different hydrochemical conditions (pH, SICC, initial dissolved P concentration) and with varying calcite properties (specific surface area and amount) in order to predict the long-term stability of the Ca-P-bonds. Peculiar shapes of isotherms that could not be explained only by adsorption processes were detected in the individual experiments. Depending on the residual P-concentration in solution, the isotherms can be divided into three sections indicating different processes responsible for the P-fixation on calcite surfaces. Adsorption prevails in equilibrium with lowest residual P-concentrations. The inflection of the isotherm at moderate residual P-concentrations suggests that precipitation and transformation of a Ca-P compound becomes dominant. This is supported by characteristic Ca/P-ratios for different Ca-P-compounds (b-tri- calcium-phosphate, octa-calcium-phosphate). On the new surface, phosphate ions again are fixed by adsorption. The observed transformation of P-bonding is crucial for sustainable phosphate immobilisation on calcite surfaces. While pure adsorption processes are reversible, the development of a thermodynamically stable Ca-P-phase, like hydroxylapatite, will lead to a lasting immobilisation of phosphate.

Jan 1, 2008

By Denisov GA

Conventional processes for disintegration of ores are characterised by low selectivity and cause damage to the components of their structure. It affects their liberation and recovery which are connected also with the inevitable formation of extreme fines. In the world practice recently came into view 4 trend to grinding of materials within a thick layer (in a bed layer), which provides a substantial selectivity of liberation, for example, of kimberlite. The degree of diamond preservation in the final product is highly increased. However, this method causes a considerable overgrinding of material. A new method of intralayer vibro-impulse breaking of materials providing an easily adjusted force acting at the layer and timely removal of product size grains from the grinding chamber has been developed in Russia.

Jan 1, 1993

A process was developed based on the thermal hydrolysis and precipitation of iron from solutions resulting from the leaching of zinc plant residue. A study was made of the hydrolysis of iron, at temperatures in the range 140-220°C, in both pure solutions of ferrie sulphate and in leach solutions derived from plant spent electrolyte.At 200°C hydrolysis of pure ferric sulphate solutions results in the precipitation of ferric oxide, Fe2O3, at low acid. concentrations, and a basic salt, Fe2O3.2S03.H20, at hIgher acid concentrations. At 180°C ferric oxide is precipitated at low acid concentrations, but at higher acidities. carphosiderite, 3Fe203.4SO.3.9H20, is the stable phase. Frequently a mIxture of ferric oxide and carphosldente IS produced at 180°C, the ratio of phases being dependent on the non-equilibrium experimental conditions.With solutions derived from plant spent electrolyte hydrolysIS at elevated temperatures results in the precipitation of jarosite compounds of the type NaFe3(S04)2(OH)6 The precipitation of natrojarosite jarosite, and ammonio-jarosite was studied in detail. Temperature, free acidity, and the concentration of sodium potassium, and ammonium ions are critical factors which affect the extent of precipitation.A process based on ammonio-jarosite precipitation was tested in a pilot plant.An alternative method of iron removal based on the addition of zinc oxide calcine, to neutralize excess acidity, and the precipitation of ferric oxide was also tested in the pilot plant. Both processes appear economically favourable...

Jan 1, 1967

By J A. Brown

Osborne Mine commenced hydraulic filling of three stopes in April 1999. Two of these stopes experienced barricade failures in July 1999 and January 2000. As a result, a review of hydraulic filling was commissioned in April 2000. The design of a trial of revised specifications and practices is in the final stages, prior to the trial commencing in mid-2002.

Jan 1, 2002

By D J. Williams, S Islam

Fine-grained coal tailings slurry undergoes only limited settling and self-weight consolidation, and tends to remain slurry-like and unsuitable for conventional laboratory consolidation testing. In addition, constant rate of loading consolidation testing is more representative of the continuous disposal of tailings slurry into a tailings storage facility (TSF) than conventional step loading. The laboratory consolidation testing of coal tailings slurry under a constant rate of loading has been carried out in a purpose-built, large-scale, slurry consolidometer, instrumented with load cells and pore water pressure (PWP) transducers. In the slurry consolidometer, the rate of loading may be varied to represent the actual rate of rise of the tailings in the TSF. A slow rate of loading increases the test duration, while too fast a rate of loading may build up very high excess PWP, without achieving significant consolidation. For the particular fine-grained coal tailings slurry tested, the rate of loading in the slurry consolidometer is varied to access its effect on the development and dissipation of excess PWP. The resulting consolidation parameters are evaluated and explained using the recorded settlement and PWP data.CITATION:Islam, S and Williams, D J, 2018. Optimisation of constant rate of loading slurry consolidometer testing of fine-grained coal tailings, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 72–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By G Diprose

Diamond exploration in Queensland is influenced by the South African approach modified by the discovery of diamonds in Lamproite in Western Australia. The current approach is to explore for Kimberlite and Lamproite bodies using indicator minerals dispersed by fluvial and colluvial processes. In the north-west, diamonds are derived from kimberlitic and lamproitic sources, whereas those in the coastal and subcoastal areas of eastern Queensland are associated with xenoliths included in rocks formed during Cainozoic volcanism. In these areas, sapphire is commonly associated with diamonds. In New South Wales diamonds in economic quantities occur in alkali basaltic intrusions and a subduction model has been proposed for these occurrences (Barrows et al, 1996). Exploration for diamonds in Australia increased following the discovery and exploitation of the Argyle mine. State geological surveys have produced digital information on the local occurrences of diamonds. As part of the Smart Mining Initiative (2006 - 2010), the Geological Survey of Queensland compiled a database and report on microdiamonds and diamond indicator minerals from open file company exploration data from 1968 to 2008 from the Department of Mines and EnergyÆs QDEX system. Most exploration in Queensland was conducted with exploration for other commodities. There is no commercial exploitation of diamonds in Queensland and, to date, only rare occurrences of microdiamonds. There is a regional difference in diamond occurrences with the kimberlitic and lamproitic models favoured for the north-western regions of the State and the subduction (S-type model) favoured for the eastern coastal zone linked to Cainozoic alkalic basaltic volcanism. Further diamond exploration is warranted in Cainozoic basalt provinces along the eastern coastal and near coastal regions and in the north-west of the state in conjunction with airborne geophysics flown as part of current Departmental Smart initiatives. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By R Lau

In recently completed road tunnel projects in Queensland, such as the Airport Link and the Clem7 tunnels, there is a smoke duct running along the roof of the carriageways to extract smoke in case of fire. In New South Wales, no road tunnels have a smoke duct. In the Melbourne City Link tunnels, there is a small smoke duct running along the roof. All of the tunnels are safe as claimed by the designers and authorities. However, there is significant cost associated with providing a full size smoke duct compared with no smoke duct. This paper is going to present a comparison of the road tunnel safety with a smoke duct and those without one from a risk perspective. It further discusses the cost-effectiveness of such provisions and whether similar levels of safety could be achieved without a smoke duct.CITATION:Lau, R, 2014. Smoke duct or no smoke duct for road tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 83–86 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

Risk management for resources and reserves includes examining the fundamental processes of data collection, interpretation, modelling and estimation. Newmont Australia has developed a procedures manual to assist mine sites to build Resource block models, estimate Ore Reserves, validate the outcome and report the results. An audit scheme has been developed to compliment the procedures manual by assessing the degree of site compliance with recommended practice. A score of between one and five stars is awarded to each site depending on its performance in the audit. Audits are undertaken by a team of three Newmont personnel over a three to five day period at each site. Scores are ultimately compared between sites and reviewed annually. The objective of the program is to encourage continuous improvement in the modelling, estimation, validation and reporting practices used at sites and in advanced projects. The scheme provides a method of risk management for the companyÆs biggest asset û its Ore Reserves. Newmont Mining Corporation is preparing to use the audit scheme internationally in part to conform with recent legislation requiring US companies to demonstrate that management systems and procedures are in place to monitor and verify the companyÆs assets.

Jan 1, 2003

By J Mukhopadhyay, J Gutzmer

Most world-class high-grade (60 - 67 wt per cent Fe) hematite iron ore deposits are the product of enrichment of Precambrian iron-formations but processes responsible for enrichment are still unclear. Different models, ranging from syngenetic and diagenetic (King, 1989), deep-seated hydrothermal (Powell et al, 1999; Barley et al, 1999; Taylor et al, 2001; Gutzmer et al, 2002) and ancient supergene (Morris, 1980; 1985; Van Schalkwyk and Beukes, 1986) to modern supergene (MacLeod, 1966) have been suggested. The high-grade hematite deposits stand in contrast to martiteûgoethite ores which are generally accepted to be the result of supergene enrichment of iron-formation because they are found along Cretaceous to Tertiary lateritic weathering profiles (Morris, 1980; Harmsworth et al, 1990). Uncertainties about the origin of the high-grade hematite ores appear largely due to the monomineralic composition of the ores. They are almost exclusively composed of hematite (as microcrystalline hematite and martite), a mineral with wide stability field and very simple chemical composition that reveals little about its origin. Second, many of the deposits have been overprinted by later deformation and chemical weathering obscuring primary ore characteristics and zonation (Taylor et al, 2001). Third, surprisingly few detailed geological studies have been undertaken on the deposits with the aim of unraveling ore genesis. Most studies focus on the present-day structure of orebodies and their general physical-chemical composition for mining and beneficiation purposes. A more thorough understanding of the origin of high-grade hematite iron ore deposits may be gained by combining available mining-orientated data with systematic petrographic-geochemical analyses of different ore generations and hematite phases. This paper presents a first summary of results of an ongoing study, started some two years ago, of high-grade iron ore deposits in South Africa, India and Brazil, including a comparison with the rather well studied deposits of the Hamersley Province in Australia.

Jan 1, 2002

In July 1994 the Premier, John Fahey MP, announced that the New South Wales Government would make available a total of $40 million over six years in new funding for the Department of Mineral Resources. These funds are to be applied directly to the generation of regional geological and geophysical information. The Government's initiative known as `Discovery 2000', is aimed at providing a major boost to the exploration industry. The Government expects new discoveries to be made and new mines to be developed because of the initiative and, perhaps, the first ever commercial oil or gas production in New South Wales. The Government's return will come from increased economic activity, and from the increased royalty return from higher levels of production. Quality information is the key to successful exploration. In the highly competitive business of mineral and petroleum exploration high quality regional geological and geophysical information improve both the efficiency and effectiveness of the area selection or project generation process. Using the `needle in the hay stack' analogy, Discovery 2000 will vastly improve industry's chances of finding the haystacks. It is up to the mineral and petroleum industries to find their respective `needles'. Careful target area selection is probably the most critical factor in mineral exploration. The ability to select the most prospective areas, or to identify prospectivity that others have failed to recognise, can make all the difference between success and failure. Government geological surveys clearly have a crucial role to play in providing the geoscientific information infrastructure that companies must have if they are to make the discoveries this country needs to pay its way in the world. It is the regional information generated by Governments that sets the scene for efficient exploration. This regional information includes regional aeromagnetics and radiometrics and gravity, regional geological mapping and tectonic analysis, and geoscientific databases. The New South Wales Department of Mineral Resources (by various names) has been providing such information for over 100 years and has led the way in many aspects of the generation and dissemination of geological, geophysical and metallogenic Information.

Jan 1, 1995

Mining projects have long since presented challenges for the protection of the water environment. Lessons learnt from historical pollution incidents and increasingly stringent environmental controls have significantly improved the environmental performance of mines in developed countries. In contrast, water protection legislation and guidance in the Former Soviet Union (FSU) countries, based on the æpolluter paysÆ principle, has not promoted the prevention of water pollution, and examples of poor environmental performance in mining still exist. However, there is now evidence of emerging legislation encouraging the protection of the water environment. This paper provides an overview of water protection legislation in the Russian Federation and Armenia and highlights some of the challenges facing international mining companies developing projects. A mining case study is described, which highlights how communities in Armenia increasingly value their water environment. Here, greater public participation in development projects is playing a vital role in influencing water protection legislation. It is considered that public opinion and emerging legislation will increasingly present challenges for the development of mining projects.

Jan 1, 2006

By Mules GJ

Geotechnical investigations have played a key role in influencing decisions for development of the Porgera Gold Project in the highlands of Papua New Guinea. Porgera is located 130 km west-northwest of Mt. Hagen in steep mountainous terrain with high rainfall. Much of the site is underlain by weak mudstone of the Chim Formation and creeping colluvial soils. Landsliding is common on the steeper slopes and in the valley floors. Structures have had to be sited to avoid areas susceptible to these movements. Early stage feasibility investigations included studies of tailings dam and waste rock dump sites, processing plant sites and hydroelectriic schemes. Further studies, leading into the design stage included the Enga Highway upgrading, water supply and power supply schemes. As construction for the project proceeds geotechnical input remains at a high level, with emphasis now on maintaining viable stable sites and refining data on which designs were based.

Jan 1, 1990