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A number of mineral deposits occur in close proximity to the Pacific plate fronts. Among these deposits are gold-silver and the base metal sulphide deposits of copper, zinc and lead. Gold deposits that commonly occur in these areas are of hydrothermal origin. Of these the epithermal deposits have attracted the attention of the exploration geologists as well as the metallurgists. One vital aspect of the activity of the geologists is the development of models for epithermal gold mineralisation in the Pacific Rim. These models can also be used by metallurgists for predicting gold extraction processes. This paper reviews the mineralogy, fineness and the host minerals of gold and examines the data in the light of gold mineralisation in the southwest Pacific Rim. The gold mineralisation models proposed for the Pacific Rim have been used to predict gold extraction processes suitable for the various mineralisation types. Discussed also are the mineralisation and treatment processes of some selected epithermal gold deposits and gold-rich porphyry copper deposits in Indonesia, Papua New Guinea, Solomon Islands, Fiji and New Zealand.

Jan 1, 1999

The Khanong supergene-enriched copper resource, (~23 Mt at 3.0 per cent Cu), is one of several resources recently discovered in the intrusive-centred, sediment-hosted Au-Cu Sepon mineral field located in southern Lao PDR. The unusual style of hypogene mineralisation and unique set of conditions have resulted in the development and preservation of a supergene-enriched profile in this subtropical climate. Hypogene sulphide-rich mineralisation replaced calcareous cataclastite (fault rock) developed in the flat-lying, extensional, Khanong Fault. Spatially, the hypogene mineralisation was immediately out board of the skarn û hornfels Cu-Bi front and in board of sediment hosted Au-(As-Sb) mineralisation in a zoned intrusive-centred hydrothermal system. In situ supergene enrichment of the sulphide protore has resulted in a high-grade chalcocite-clay zone (~10.3 Mt at 4.6 per cent Cu) overlain by leached limonite-clay. A very high-grade in situ to exotic limonite-clay Cu-oxide-mineral zone is locally developed above impermeable dolomite at the base of chalcocite-clay zone. Exotic Cu-Mn-wad mineralisation developed for up to 1 km down the hydraulic gradient from the chalcocite-clay zone. Unique supergene enrichment conditions have resulted in the high-grade Khanong Cu resource in a subtropical weathering environment. The base of the currently active supergene profile coincides with the base of a flat-lying, pyrite-rich fault rock, dipping parallel to the hill slope, maximising Cu enrichment. Meteoric water has been channelled along subvertical faults and narrow horizontal subsurface zones. Low permeability of the fault host rock and footwall rocks has controlled the low volume and slow movement of groundwater required for supergene enrichment. Erosion has been slowed by the resistive ironstone and limonite-clay layer at surface, which assists in preserving the gentle slope over the chalcocite-clay zone.

Jan 1, 1999

Commercialisation of Ni Heap Leaching at Murrin Murrin Operations

Sep 13, 2010

Inpit tailings disposal has been undertaken at a number of mining sites within Australia. This paper presents a brief history of the experience of inpit tailings disposal at the Marymia Gold Operation in Western Australia, including geotechnical aspects of the design. Regular monitoring of the inpit tailings disposal into the K1SE Pit at Marymia has allowed the operators of the mine to assess the performance of the tailings storage against its predicted performance during the design phase. Results of this monitoring indicated that the predicted performance was exceeded and the results have been incorporated into the design of another large inpit tailings disposal, the K1 Pit. Monitoring of tailings disposal to both the K1SE Pit and K1 Pit has allowed the mine operator to make substantial savings from inpit tailings storage when compared with above ground tailings storage facilities. The inpit method of tailings disposal at Marymia has proven to be acceptable from an environmental perspective by reducing the water resource requirements of the project, backfilling pits, which would otherwise collapse with time and eliminating the need for disturbing additional areas of mining leases, which usually accompanies construction of above ground tailings storage facilities.

Jan 1, 1999

The New Technology of Enrichment of a Fine Low-Grade Tungsten from Complex Multi-Metallic Ore

Sep 13, 2010

By V L. Los, G J. Abramson

The paper examines three types of polar zoning of ore-forming and associated elements that can be detected from geochemical data. Polar zoning is mapped in the form of geochemical ore systems of various ranks. Various types of polar zoning can be found in some systems, which present a general geochemical model of the ore object. The genetic basis of zoning is examined from the perspective of the conception of geoelectrochemical redistribution of matter, including ore-forming elements. The volume of the geochemical ore system may be used in the prognosis of resources for every rank.

Jan 1, 1999

Continuous pH and Pulp Potential Measurements During Complex Sulfide Ore Flotation

Sep 13, 2010

By G J. Wilkie, P A. Revell

The R&D landscape for ore pre-concentration technologies within mining is characterised by the development of individual technologies and point solutions. This presents METS and mining companies with the combined challenge of understanding how to apply pre-concentration technologies to create maximum value, and how to sustainably integrate the technologies into their businesses to maintain the value. The paper will consider the requirements of an integrated pre-concentration system and presents a portfolio of R&D projects that have co-developed and integrated a suite of new precencentration technologies and methodologies across the mining value chain. Focus areas include in-situ orebody characterisation, blast design, real time cross belt mineral sensing, and consideration of how much data needs to be acquired in order to make value based decisions between ore pre-concentration options. An ore pre-concentration workflow is presented to demonstrate how additional optimisation opportunities are enabled both by moving decision points further upstream in the value chain, and by integrating the concepts of pre-concentration into the design of mineral processing equipment. Additionally, several research projects examine the non-technical factors that present barriers to uptake of new technologies within mining companies. Organisational culture, risk management and socio-political factors are discussed and a set of management tools are presented that allow organisations to self-assess their readiness for new technology uptake, along with process models to assist management with identifying and navigating the ecosystem of stakeholders that are decision makers in the use of pre-concentration technologies.

Nov 10, 2020

By A B. Richards

A brick veneer house located on a open-pit coal mine lease has been subject to ground vibration levels of up to 222 mm/s, and air vibration levels of up to 145 dBL. The dynamic response of the structure was measured with accelerometers, geophones, and strain gauges as part of a project investigating the response of brick veneer houses to blasting. This paper outlines the project, and provides information on brickwork strength, foundation investigations, and observations on damage due to blasting. Correlations have been made between crack behaviour and factors such as blast vibration levels and rainfall.

Jan 1, 2001

Avoca Resources LimitedÆs Higginsville Gold Project has a resource base of over 1 300 000 oz of gold. The Trident underground mine, which forms the basis of the project development, has a resource base of 927 000 oz of gold. Avoca is building the Higginsville Gold Project based on a minimum ten year vision, producing over 150 000 oz per annum. The project development has taken less than three years from the Trident discovery hole in October 2004 to the first ore production in June 2007. This paper discusses the background work associated with the development of the Trident underground mine in a difficult period for new project development in Western Australia. The resources boom, led by the iron ore industry in the Western Australian Pilbara region, is creating cost pressures and, combined with a lack of people and equipment, is placing cost and timing stress on a small developing project. Avoca Resources has developed a project execution management strategy aimed at mitigating cost blow outs and schedule delays.

Jan 1, 2008

Research on the Design and Processing Characteristics of 320 m3 Air-Forced Mechanical Flotation Cell

Sep 13, 2010

By M Roche, W J. Huxley

Finding a balance between practical and acceptable groundwater management, and providing for the needs and impacts of mining developments remains a challenge. The changes that accompanied the recent implementation of water reforms have provided greater flexibility for the water manager and greater certainty for the resource user. However uncertainty associated with understanding of complex aquifer systems, balanced against providing for the needs of mining developments, the rights of existing water resource users and expectations of the broader community have not diminished the conflicting issues faced by water resource managers and resource developers. Licensing under the Water Act 2000 provides the regulatory link with the taking of water for water supply purposes or as a consequence of the mining activity. This paper outlines key elements of sustainable water resource management involving certainty of access to water and adaptive environmental management that are delivered through conditioning the water licences issued for the particular mining development. Implementation of this approach is illustrated through a case study involving the BHP Billiton Cannington Mine in North West Queensland.

Jan 1, 2003

High-sulphidation (HS) gold, silver and/or copper deposits are generated in both the epithermal and the upper parts of the underlying porphyry environments over vertical intervals of up to 2 km. The HS deposits are generated in advanced argillic lithocaps, which are products of the absorption of acidic magmatic volatiles by voluminous groundwater systems. Mineralisation styles in HS systems reflect depth of formation as well as the interplay between structural, lithological and hydrothermal parameters. The deep parts of HS systems, at depths of >1000 m, are typified by disseminated copper¦gold mineralisation comprising digenite, chalcocite and covellite in pervasive advanced argillic as well as underlying sericitic alteration. In highly telescoped systems, such mineralisation may overprint porphyry stocks and associated quartz-veinlet stockworks. Intermediate levels of HS systems commonly contain fault-controlled copper-gold mineralisation, typically as enargite in bodies of vuggy residual quartz, silicification and/or massive pyritic sulphide. The shallow parts of HS systems, at depths of The exploration focus is on four principal HS mineralisation styles:copper (eg Chuquicamata, Monywa) or copper-gold (Wafi) in the deep porphyry-hosted parts of systems preferably, in the case of the latter, where supergene oxidation is limited and, hence, flotation may be used for metal recovery; copper¦gold-bearing replacement mantos and pipes hosted by carbonate wallrocks in the deep parts of systems (eg Bisbee); high-grade gold in late-stage veins or hydrothermal breccias that overprint the intermediate to shallow levels of systems (eg El Indio, Goldfield); and large, bulk-mineable gold deposits in the shallow parts of systems that were subjected to supergene oxidation, thereby permitting heap-leach treatment (eg Yanacocha, Pierina). To these preferred HS styles may be added the low-sulphidation vein or disseminated gold¦silver mineralisation that is commonplace alongside many HS systems (eg Victoria at Lepanto).

Jan 1, 1999

By P To, A Sharp-Paul, S Jones, C Monahan

A key environmental management issue associated with mining projects is tailing disposal. In high rainfall environments this is particularly challenging and generally requires the discharge of excess water from a tailing dam to adjacent streams or coastal waters. Such discharges can potentially have adverse impacts on downstream water quality and the environmental values associated with these waters, such as providing a drinking water supply for local villagers, maintaining a fisheries resource or protecting a fish species of high conservation significance. An alternative to the construction and operation of a conventional tailing dam is Deep Sea Tailing Placement (DSTP). The key features of such a system are:Discharge of the tailing slurry at considerable depth (approximately 120 - 150 m) below the oceanÆs surface. This requires a pipeline to be laid from the process plant to a mix tank, where the tailing is mixed with seawater and entrained air released. The pipeline then continues down the ocean floor to the required discharge depth, which is below the surface mixed layer and the euphotic zone. After discharge, formation of a density current which continues to descend along the ocean floor as long as the slope is sufficiently steep. Final deposition of the tailing in an area where the slope of the ocean floor is insufficient to maintain the density current. This typically occurs at depths of more than 800 m. Water quality issues associated with DSTP include: Impacts on the oceanic water column due to the formation of subsurface plumes which break away from the descending density current. The occurrence of elevated concentrations of contaminants in the interstitial waters of the deposited tailing solids. Fluxes of contaminants from the tailing deposits into the overlying oceanic water column. This paper discusses the water quality aspects of DSTP with particular reference to a case study in Papua New Guinea. The evaluations undertaken as part of the DSTP impact assessment included consideration of both the short- and long-term chemical behaviour of contaminants and bioassays, within the appropriate water quality assessment framework.

Jan 1, 1999

By D J. Corp

The Halmahera Contract of Work is a sixth generation contract held 82.5 per cent by Newcrest Mining Limited and 17.5 per cent by PT Aneka Tambang and takes in the Gosowong Project area. In 1991 Newcrest Mining Limited established a small exploration office in Jakarta and proceeded to seek exploration opportunities. The Halmahera area was identified as a substantial prospective ground position in a relatively unexplored area. In late-1991 Newcrest Mining Limited and PT Aneka Tambang agreed to explore in Halmahera. Initial field work commenced in July 1992. A vigorous ground reconnaissance programme led to the discovery of the Gosowong deposit a little over 12 months later in September 1993. In April 1997 the Contract of Work was approved covering much of the island of Halmahera. Between September 1997 and November 1998 activities were directed principally towards obtaining the necessary permits required to commence construction activities. Some particularly ambitious targets were set for achieving this outcome. An aggressive construction programme commenced in late-1998. Construction took place during a period of unseasonally high rainfall, which in itself presented additional challenges to the construction team. A key milestone for the project was achieved on 1 July 1999 when wet commissioning of the process plant commenced. Construction of the Gosowong Mine was achieved on time and within budget. A period of some six years elapsed from the initial discovery of the Gosowong deposit to the time of the first gold pour. Much of the permitting, construction and commissioning activity took place between September 1997 and July 1999. This coincided with a period of significant social, economic and political upheaval in Indonesia. During the construction period a high level of importance was placed on the structured recruitment and training of local people, as well as fostering appropriate community and local business development programmes in the communities nearby the project. Emphasis was also placed on environmental management with detailed long-term planning and progressive rehabilitation commencing during the construction phase. The permitting and subsequent development of the Gosowong Project has demonstrated that even during the difficult times, with commitment, it is possible for mining and exploration companies to conduct business in Indonesia.

Jan 1, 1999

The spatial and temporal evolution from the porphyry to high-sulphidation epithermal environment can be assessed by integrating new results on such deposits (Arribas et al, 1995; Hedenquist et al, 1998) with past studies of plutonic and porphyry systems (Dilles and Proffett, 1995; Cline, 1995; Shinohara and Hedenquist, 1997; Hedenquist and Richards, 1998). Some time ago, Sillitoe (1973) argued for the nature of the tops and bottoms of porphyry deposits. He concluded that epithermal deposits may form over the tops of some porphyry systems. We can now conclude more confidently what the tops and bottoms of many high-sulphidation ore deposits appeared like while active (Arribas, 1995; Hedenquist, 1995). In addition, we better understand the nature of the zonation of high-sulphidation epithermal systems from the intrusive to surficial environment (Sillitoe, 1999), and how these two styles of ore deposit are related. Geological and geochemical evidence clearly indicates a continuum between these two ore environments. This improved understanding of genesis allows more efficient exploration for these deposits. There are many examples of spatially associated porphyry and epithermal ore deposits. A genetic connection has been suggested by some, and argued against by others. Nowhere is this spatial association better seen than in northern Luzon, Philippines, where the Lepanto high-sulphidation epithermal Cu-Au deposit overlies the Far Southeast (FSE) porphyry Cu-Au resource (Figure 1). Together these mineralised bodies contain a resource of >3.8 M tonnes Cu and >550 tonnes Au. Lepanto was largely mined out in early-1997. Post-war production until 1995 was 0.73 Mt Cu, 115 t Au and 393 t Ag at an average grade of 2.2 per cent Cu, 3.5 g/t Au and 11 g/t Ag. The recent discovery of the adjacent Victoria low-sulphidation quartz-Au-base metal vein deposit, with a resource of >68 tonnes Au (Cuison et al, 1998), illustrates the variety and abundance of mineralisation in the Mankayan district. This district also hosts the Guinaoang porphyry Cu-Au deposit (Sillitoe and Angeles, 1985) and other epithermal vein occurrences (Figure 1). This brief summary reviews the results recently published on the Lepanto-FSE deposits (Arribas et al, 1995; Mancano and Campbell, 1995; Claveria, 1998; Hedenquist et al, 1998), and stresses the evidence for coupling of mineralisation between the porphyry and high-sulphidation epithermal environments.

Jan 1, 1999

The global mining industry is perceived to be a world leader in sustainability reporting û with a 2008 Ernst & Young survey placing four mining companies in their top five performers in sustainability reporting in South Africa. There is certainly good evidence to support this finding, but there remain many ongoing issues with respect to sustainability reporting and some important areas for improvement by mining companies globally. This paper begins with a broad (but brief) review of sustainability and the technical basis for reporting against a wide range of typical indicators or measures on the environmental aspects of mining. The various protocols, frameworks or systems are then reviewed, with a particular focus on the Global Reporting Initiative (GRI) and its associated mining sector supplement (including the evolution from environmental to sustainability reporting). A wide-ranging survey of reporting by mining companies is presented, including detailed analysis of 2007 and some commodity sectors over time. Examples of reported data are synthesised and analysed, focusing on their accuracy, consistency and utility for accurate assessment of the life cycle impacts for minerals and metals. A number of areas are identified for improved reporting by all mining companies, including water resources and consumption, energy consumption, process inputs (eg acids, solvents, etc), pollutant emissions, including greenhouse emissions, mine site data (not aggregate company totals) and finally rehabilitation and land status. Given the nature of mining, and considering parallels between æpeak oilÆ and the mining sector, it is critical that the state of sustainability reporting continue to evolve and improve û both in the number of companies using the GRI but also in the level and consistency of data being reported. Overall, the paper presents an important review of the present state of the art in sustainability reporting for mining, and provides a range of insights into ways to help improve reporting in the future for all mining companies.

Jan 1, 2009

By K Shannon, A Shaw

The Hilton and George Fisher deposits occur 22 and 24 km north of Mount Isa, NW Qld, Australia respectively. Both deposits occur as deformed Proterozoic, sediment hosted, stratiform orebodies hosting Pb-Zn-Ag (Hilton) and Zn-Pb-Ag (George Fisher) mineralisation. The two deposits are separated by approximately 2 km of strongly faulted barren shales, mudstones and siltstones along strike. Despite this, correlations between the Hilton and George Fisher deposits have previously been assumed on the basis of textural, lithological and geochemical similarities, but previously lacked specific details to prove exact stratigraphic matches.Feasibility drilling allowed broad correlations based on the position of siltstone pillars separating individual orebodies. However the position of continuous potassium-rich, siliceous and cross-fractured tuffaceous marker beds (TMBs) often used as stratigraphic markers within the Hilton Mine were initially unrecognised within the George Fisher stratigraphy where they are erratically silicified and often not cross-fractured resulting in correlations being difficult to prove. As a more detailed knowledge of TMB locations at George Fisher was gained it was possible to look for corresponding TMBs within the Hilton orebodies. Recent underground stope definition drilling at the two locations enabled specific TMBs, stratigraphic units and even individual sedimentary beds to be matched between the two locations, despite the large separation between mines.The correlation between the two deposits has implications for future exploration drilling north of George Fisher. If a specific stratigraphic horizon can be determined within one hole, positioning of further drillholes can be more accurately planned. The significance of having stratigraphic matches between Hilton and George Fisher also has implications for correlations with other Isa Valley deposits. Convincing preliminary TM and stratigraphic correlations have already been made between George Fisher and the Isa Lead Mine 24 km to the south.

Jan 1, 2002

The history of mining is rightly proud of its achievements in improving productivity and cost improvements over the years. No matter what measure is used, tonnes per manhour, cost per tonne, etc vast improvements have been made over the last hundred years. In fact over the last ten years in Australian coal mines raw coal output per employee has increased by 60 per cent. When one examines why these improvements have taken place the principal reasons have been technological advancement in mining equipment, excavator and dump truck capacity increases, longwall and continuous miners continually improving in reliability and size. Of course all these improvements are correlated to an increase in capital cost. Even with the above-mentioned advances the pressure for increased performance is as strong as ever. The international mining and mineral-processing sector is currently operating in a recessive market with some traditional commodities, eg gold trading at 20 year lows. During recessive times senior management will demand greater returns on capital employed: the obvious choices being reducing costs or increasing throughput. In addition, head office environments will often place a capital freeze on operational management so the opportunity to take advantage of technological change is not available. The challenge is, therefore, to increase throughput and cut costs without the need for capital. The answer is to optimise the existing labour and plant. If done systematically a result in productivity improvement, in our experience, as high as 45 per cent can be achieved with the average across South East Asia and Australasia being 21 - 23 per cent. The intention of this paper is to present a systematic approach to labour and machine utilisation thereby gaining the greatest possible return on the existing capital base.

Jan 1, 1999

By Griffiths L, Marshall P

fhis paper describes investigations into drainage of gas from the solid to control outbursts. Initial studies conducted on drainage of shear zones showed that, given enough time, these can be successfully drained. Once drained, they can be intersected and driven through without any activity of outbursts. The results of programme of investigations to determine parameters for drainage from the solid show that gas flow rates from the Bulli Seam on the average are about 2 litres/min/metre length of borehole. But when shear zones are intersected, the flow rates could be as high as 8 litres/min/ metre length of hole. Shear zones can be picked up from pressure measurements 50 - 60 m away and this could give sufficient time to drill through these zones and drain them in advance. Systematic drainage of Bulli Seam at West Cliff Colliery could eliminate or reduce frequency of outbursts considerably. At present drainage holes are being drilled systematically in the seam, with drainage installations on the surface. Gas purity of 80% methane is being delivered at the surface plant.

Jan 1, 1980