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The Physical Basis of Non-Random Breakage in an Iron-Oxide Ore Hosted Copper Gold Ore

Sep 13, 2010

By J Robinson, D Herbert

Bench stoping operations at the Isa Lead mine have been underway for over 11 years. They were implemented to address safety, productivity and mining cost concerns noted with cut and fill mining operations which were then being used to extract ore from the Racecourse orebodies. This paper describes the main features of benching operations at the Isa Lead mine and identifies the key elements for the success of the method. Four case histories are presented which highlight several of these factors.

Jan 1, 1998

Advances in technology have led to larger and deeper open pit mines and, consequently, also increased the potential economic impact associated with slope failures. If the ultimate aim of mining operations is to maximise project profit, it is surprising to see related research activities have mostly been focusing on technical areas such as slope stability modelling, but with limited studies conducted to date to assess the relationship between geotechnical uncertainties and economic risk. Given most major decisions in the mining industry nowadays are made by management staff with financial background, any design approach that would help to link slope stability analysis results with monetary values would no doubt enhance communication between geotechnical practitioners and decision makers. This paper presents a study which assesses economic impact of slope failures to assist in mine planning. The study also estimates the impact of slope failures on project value, which would enable economic risks associated with pit slope designs to be closely examined. The proposed risk assessment techniques, used by financial institutions for many years to assess portfolio risks, can assist geotechnical practitioners in quantifying risks of slope failures. Risk-adjusted concepts are also suggested to assist management in selecting a slope design with optimal risk and return ratio.

May 1, 2010

Access to the Rosebery Orebody, which dips into the western slopes of Mount Black at 45¦, has been achieved in sequence by the following means: - A series of adits down to 8 level - An inclined shaft (No. 1 Shaft) sunk internally from 8 level to 14 level - A vertical circular concrete lined shaft (No. 2 Shaft) sunk internally from 4 level to 19 level. Although the orebody has been fairly well defined to 19 level, deeper ore occurrences have been outlined by a series of drill holes decreasing in frequency with depth to 26 level. No. 2 Shaft (sink) was stopped some 10 m below 19 level in order to make an early start on doubled production at West Coast Mines, with the intention of subsequently extending the shaft or of driving a decline from the lowest operating horizon for deeper access. The decline approach was adopted some six years after production commenced from No. 2 Shaft. The reasons for that decision are outlined, together with an account of the constraints and design requirements imposed by commencing by a vertical shaft in the hanging wall of the orebody.

Jan 1, 1982

By Tuck M. A

The increasing depth, mechanisation and distance of working areas from surface connections places an ever greater contaminant burden on ventilation airflows. Some British Coal mines are already experiencing significant problems in providing adequate climatic conditions in the working areas and have had to introduce air conditioning. Previous work has shown that in mines of low to moderate virgin strata temperature the application of controlled district recirculation could serve to improve climatic conditions at the working area.

Jan 1, 1988

Application of Kriging in Approximations of Grained Materials Characteristics Distribution Functions

Sep 13, 2010

By N Merry, T Cocks

The mineral exploration industry is increasingly aware of the importance of the relationship between mineralogical data and geochemical assay results. However, until recently, the cost and time constraints of most techniques for analysing alteration mineralogy have precluded detailed alteration studies. These impediments have been reduced by the development of the Portable Infrared Mineral Analyser (PIMA), a field portable infrared spectrometer that allows rapid (in field) and cost effective analysis of alteration minerals including subtle variations in mineral crystallinity and composition.   A major application of this technology is in mapping mineralogical variations within hydrothermal alteration systems. Using actual case study examples this paper introduces two approaches to using the PIMA data: 1. for directly mapping alteration systems and using the PIMA data to provide vectors to mineralisation, and 2. for establishing empirical relationships between geochemical data and PIMA spectral data. These applications demonstrate that this technology can be an invaluable tool for targeting and mapping alteration and mineralisation.

Jan 1, 1995

By R M. Briggs

Kapowai Caldera Complex (KCC), located 10 km west of Tairua (eastern Coromandel Peninsula), is a late Miocene composite collapse caldera, formed during eruption of several small and large volume andesitic rhyolitic ignimbrites. Numerous epithermal Au-Ag mineral deposits and associated alteration zones at the KCC are related to caldera (rhyolite lava domes, intracaldera faults) or regional structures (faults). The main epithermal deposit exposed in the central KCC is associated with an E-W striking structural boundary fault that cuts the Welcome Jack rhyolite dome. Propylitic (calcite - chlorite) and sericitic (quartz - sericite) alteration haloes surround this deposit. Sporadic zones of sericitic alteration are also exposed within and on the margins of the Bulls Run rhyolite dome complex. Epithermal systems post-dated emplacement of these rhyolite domes, but were controlled by them. Propylitic alteration of ignimbrite in the floor of the Kapowai and Kauaeranga valleys is related to the major NE-trending Kapowai Fault which extends SW to south of Thames. Alteration along this fault pre-dates alteration associated with the rhyolite lava domes. Numerous sericitic and propylitic altered welded ignimbrite, rhyolite and andesite lava lithic fragments have been sampled from intracaldera ignimbrites, and although no direct source is known, they infer the presence of buried epithermal systems. Repeated epithermal activity at the KCC is inferred by the exposed epithermal deposits/alteration zones and the older buried geothermal systems. Silicic caldera volcanoes are considered to be critical volcanic environments for epithermal Au-Ag mineralisation in Coromandel, but are highly variable and need detailed stratigraphic, structural, petrologic, and geophysical studies to characterise them.

Jan 1, 1999

A number of terrane reconstructions conflict with global plate histories or with data from adjacent regional studies. Paleogeographic maps have ignored terranes thus are over-simplified. This paper represents an attempt to "marry" Mesozoic global plate reconstructions and terrane analysis to produce examples of a "third generation" of global plate tectonic maps. The best approach to global terrane analysis involves intercomparison of all regional data and the evolving global model. Data conflicts within and between terranes and regions must be resolved by a system of relative data reliability "weighting." The most reliable and useful data are those which constrain "departure" (rift) and "arrival" (collision) times. Certain ad hoc decisions aid in the analysis (e.g. only one net vector allowed per plate). The maps that follow summarize Early Mesozoic global tectonic history at three critical junctures: 240 MA (Triassic); 180 MA (Jurassic); and 120 MA (Cretaceous). Due to space limitations, maps drawn at 20 m.y. intervals appear elsewhere. A preliminary Middle Triassic reconstruction is presented in Figure 1. Major plates and continental blocks are labeled; smaller blocks are marked with abbreviations. Examination of Figure 1 indicates the necessity of modeling Triassic tectonics with at least 68 blocks. Spalling- off of microcontinental slivers from Gondwanaland is active some 70 m.y. before the actual breakup of the supercontinent. In the SW sector of the Pacific, the Australian margins were embroidered with several terranes (e.g. Sumba) which eventually rifted away and crossed Tethys. The NW sector at this time included 10 microcontinental chips forming a huge archipelago along the Asian margin. All blocks inboard of Indochina collided by latest Triassic. Terranes of the NE sector include several (e.g. Arctic Alaska) along the North American margin, and at least six large blocks (e.g. Stikinia) drifting SE with the Farallon Plate. The SE sector

Jan 1, 1987

By K Palmer, G J. Artmont

Alluvial gold is an ideal exploration tracer to bedrock source and indicator of bedrock mineralisation style because: (i) gold occurs in a wide range of deposit types, (ii) primary composition is sensitive to style of mineralisation, and (iii) it is a heavy resistate mineral that is readily preserved and easily sampled. In regional exploration of the Central Ranges of Irian Jaya, alluvial gold mineralogy has been applied to maximise the information return from panned concentrate sampling and to focus exploration effort. Primary gold is a solid solution of Au+Ag¦Cu¦Hg, ¦ trace Pd, Te, and Sb. In general Ag¦Hg increase and Cu decreases with inferred decreasing temperature of formation, and gold from particular mineralisation styles has signature compositions that can be used as indicators of bedrock mineralisation type. Furthermore, the abundance of alluvial gold is an indicator of the economic potential of a catchment. The convergent continental-oceanic plate geology of the Central Ranges is conducive to a wide range of mineralisation styles. Mineralogy of gold in ophiolite, skarn, porphyry, mesothermal vein and possible VHMS environments is characterised from alluvial and bedrock samples, and the use of gold mineralogy in prospecting at regional scale through prospect definition to drilling is demonstrated.

Jan 1, 1995

Solid Energy New Zealand Limited owns and operates the Ohai coal field (Wairaki Coal Mining Licence, CML) in western Southland. The Morley Stream passes directly through the middle of the CML and has required diversion in the past to enable open cast mining to proceed. Solid Energy is evaluating two new open cast pits at Ohai. Commissioning these new pits would necessitate further diversion of the Morley Stream. One of these potential new mines is adjacent to an abandoned State Coal Mines (State Coal) pit and there is an opportunity to substantially rehabilitate this old pit as a corollary to the new mine and the stream diversion project.   Past Morley Stream diversions were undertaken by State Coal and so they predated the Resource Management Act 1991 and the degree of community environmental awareness and involvement that has become the norm these days. Not surprisingly the design and construction of the historic stream diversions was based purely upon mining (operational) and engineering considerations. This led to the stream being diverted in a manner that achieved the clinical conveyance of design volumes of water from points A and B.   Solid Energy realised that the proposed new diversions need to adopt more holistic and environmentally sustainable design principles while also including appropriate mining and engineering constraints. This project involved the design of a 1.7 km diversion of the Morley Stream (median flow of about 1000 litres/second) that would enable progressive prestripping and development of the new mines and would also address final rehabilitation (of the stream), geotechnical risks, hydrological and ecological issues. To address all of these factors the project required a multidisciplinary approach. Moreover, it required a clear understanding of how the mining operational constraints could be integrated with the environmental considerations. A significant aspect of the project was how to take account of fishery instream habitat needs, the resource consent requirements and most of all, the involvement of key stakeholders such as the Fish & Game Council, Department of Conservation, the Iwi and local community in the design process. This was achieved through coordinated consultation and stakeholder involvement in a technical design workshop.

Jan 1, 2005

Efficacy of Enhanced Gravity Separator in Processing Indian Iron Ore Slime The slime sample was subjected to concentration using Falcon concentrator for their enrichment. The effects of three important variables, eg bowl rotation frequency, back water flow rate and per cent solid were studied on the process performance. Increasing the rotation of the Falcon bowl, enable more material to the underflow by increasing the yield, whereas, the iron content decreases steadily with increasing the rotation of the bowl. The increase in the back water flow effectively removes the clay materials from the underflow at the expense of the yield. Similarly, increasing the per cent solid concentration in the feed produces a better product both in terms of yield and Fe content. Results show that EGS/Falcon can be used for processing Indian iron ore slime and producing pellet grade concentrate.

Sep 13, 2010

Innovative and Resource-Preserving Washing Processes for Primary and Secondary Raw Materials

Sep 13, 2010

By A Horne, Z Graszkiewicz, D Dettrick, R Evan, B Neal

"Most of VictoriaÆs rivers and aquifers are already fully allocated or reaching full allocation. In regions without a well-established water market, access to water entitlements to facilitate new development is limited. In areas with established water markets, mine developers face an undue cost burden in circumstances where they are only planning to consume a fraction of the water entitlements that they purchase. The challenge for water managers is to ensure protection of water resources and other water users without creating an unnecessary disincentive for those types of developments that return most of the water that they take from water sources. The opportunity for development of a mine is explicitly linked to a particular location and must be developed where a resource is located or it cannot be exploited at all. Regulatory arrangements that facilitate development may have a positive impact on economic development, particularly where water availability is a potentially limiting factor. Net volume licensing has the potential to allow increased economic outcomes through improved licensing of access to water. Net volume licensing differs from traditional water licensing in that it authorises access to water on the basis of ænet useÆ rather than æthe gross volume takenÆ. This paper asks under what conditions net volume licensing is likely to be feasible and effective. In particular, the paper examines the information and accuracy requirements to allow net volume licensing decisions to be made. This work is based around five case studies in Victoria that were used to examine the potential for net volume licensing for mines and quarries. Assessing a potential net volume licensing arrangement requires the regulating authority to have an understanding of the inputs and outputs of water to a site. In contrast, assessment of take and use licences consider only a single input. It was concluded that the conditions that lend themselves to net volume licensing include: well understood water inputs and outputs, including appropriate accuracy of information where the location of site water inputs and outputs are the same where the timing of extraction and discharge can be managed to minimise impact on the water resource.A key remaining challenge is establishing an accounting framework that allows net volume licensing under current water resource limits. CITATION:Graszkiewicz, Z, Horne, A, Neal, B, Evan, R and Dettrick, D, 2013. The practicalities of implementing net volume licensing of water use in mines and quarries - a discussion based on Victorian case studies, in Proceedings Water in Mining 2013, pp 241-250 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 26, 2013

There is a significant amount of historical mining and exploration information available. This information is often distributed throughout a number of reports or plans, available from a variety of sources, and in many differing formats. The ability to capture paper-based historical information in a modem digital format provides mining and exploration companies with valuable information that can be used in a number of ways; for example, reassessments of exploration or mining work previously undertaken, or used in conjunction with current exploration information.   The purpose of this paper is threefold. Firstly, to present the paper-based historical information; highlighting some of the problems encountered, solutions to those problems, and any assumptions used. Secondly, to present the historical data in digital format, and demonstrate the tools available to analyse geological and associated information, and finally, to illustrate some of the potential future applications of the information, including mining optimisation, mine design and scheduling.   The Glenorchy scheelite/gold prospect has been used as an example. Within the overall prospect two smaller areas were selected. The Mount McIntosh and surrounding areas, focuses on exploration and surface excavation information. The Mount Judah area (State and Kelly-Taylor workings) focuses on underground mining and exploration information.  

Jan 1, 2001

Project Sustainability Assessment - Matching Method to Enterprise Size Sustainable development requires managing natural resources, including minerals, in a way that is conducive to long-term wealth creation and the maintenance of capital (natural, social, human, economic and physical). One aspect of the minerals sustainability discussion focuses on replacing depleted mineral capital with other forms of capital so as to ensure that the contribution of a mineral project is net positive over its life. Another, equally important, aspect focuses on selection of projects and technologies that contribute to the achievement of a variety of sustainability objectives, such as environmental protection, efficient use of resources, water and energy, worker health and safety, and the equitable distribution of risks and benefits within and across generations. Technical feasibility and relative economic performance remain necessary decision criteria for mineral investment decisions, but they are no longer sufficient. Enterprises, regardless of size, are now confronted with the challenge of comparing investment alternatives based on a new, broader set of criteria. The field of integrated sustainability assessment (ISA) emerged in response to this changed social and business environment. ISA is a structured process for examining the economic, social and environmental impacts of a project or technology. The purpose of an assessment can be broad, a strategic review of corporate behavior for example, or quite narrow, input to a specific decision process such as the selection of a piece of equipment. There are numerous methods and analytical tools available to conduct ISAs and selection of the most appropriate for a given situation will depend upon temporal focus (retrospective to prospective), decision context (strategic, tactical or operational), and phase of the assessment process (problem structuring, analysis, resolution, ex post review), among others. Selection also depends upon enterprise size and the attendant availability of financial and human resources. Large multi-national firms often undertake complex, data intensive sustainability assessments, in part because the projects they are involved in are multi-faceted, long term, and require significant financial investments. Small and medium sized enterprises are seldom able to commit the same level of resources to an ISA, and if the projects they undertake are less complicated, a time consuming and detailed assessment may be unnecessary. Regardless of enterprise size, the tangible and reputational benefits of conducting as ISA must exceed the actual monetary cost of doing so. This presentation will provide an overview of available ISA tools, categorising them in terms of their data requirements, methodology, outputs and applicability in various decisions contexts. Distinction will be drawn between situations where reasonable approximations of project impacts can be expected to provide an adequate amount of information and those for which more detailed analysis is essential. Finally, ISA strategies that have been successful and cost effective at different scales of business enterprise will be identified. This is an abstract only. No full paper was prepared for this presentation.

Sep 13, 2010

This article presents a proposal for the rehabilitation of the mined area of the Mogiana quarry. The Mogiana quarry produces material used in civil construction and is situated in the Brazilian State of Spo Paulo in the kilometre six of the Mogf Mirim - Itapira highway. The mineral exploitation in the Mogiana quarry provokes modifications in the environment such as alterations in the relief, vegetation, quality of the air, water and landscape. Through previous study of the area it was verified that after the closure of the exploitation the mine should be occupied mainly by pasturage. At the closing of the mine the exploitation benches, berms and slopes in general as well as the surrounding areas should be covered with a layer of soil and vegetated with native species in order to mitigate the negative impacts caused by the mine. The rehabilitation project of the area is based on the probable future use of the area, located between agricultural cultivations and cattle creation. The great alteration of the relief and soil would make future use of the area for agriculture difficult. It is more suitable t0 animal creation, mainly cattle. The high and thick rock slopes originated by the mining should be covered by vegetation, where possible, to reduce the negative visual impact. Obviously several measures will be necessary to reduce the impacts on the environment during mining. The final and definitive reclamation will only be possible after abandonment of the area. The main aspects of this reclamation process will be discussed in this paper.

Dec 6, 2010

One of the major changes in the resource industry in the nineties has been the re- internationalisation of the industry. The history of the resource business has been one of companies from the developed world utilising the cash flows from their operations to explore and develop mines in less developed regions of the world. This resource development has progressively generated wealth and economic development, which in tum, has led to a new generation of exploration and mining projects.   InSouth America, Chile had led the way in a mining resurgence, now closely followed by Argentina, Brazil, Venezuela and Peru. Although Chile has long had a significant copper mining industry, the pre-nationalisation phase was driven by American capital; the current phase has been spearheaded by RTZ - BHP at Escondida with Canadian junior companies, in particular, providing major speculative impetus. The Australian junior companies have not been significant in South America.   Although Canadian and USA exploration appears to be in decline, the mining industry, particularly in gold, is buoyant in North America. Interestingly, a number of listed and unlisted Australian companies are active, particularly in United States exploration.   Australian-based companies have dominated the South-East Asian exploration scene, especially in the Vietnam region. To date, the combination of political and legislative uncertainties have failed to lead to significant resource developments in this region. The area remains one of great potential, as exemplified by the exciting developments in Indonesia.   The Philippines has a history of mining, and this has been dominated by both local and North American operators. Both large and small Australian resource companies have a presence in the Philippines, and the development of the copper-gold potential could be impressive over the next decade.   The tales of the undeveloped mineral potential of China are probably rivalled only by the supposed strings of virgin Russian orebodies! Many Australian companies appear to have looked but few have chosen to proceed with Chinese developments. There seems little likelihood that China will, in the foreseeable future, rival South America as a target for Australian and North American resource capital.   Papua New Guinea has had an active, albeit chequered history in mining, with Australia long being the predominant source of exploration and development funds. The developing nation status of PNG has generated extreme uncertainty, with the current exploration scene all but dead. Most recently, the international flotation of Lihir Gold has tested the international and Australian investment community's commitment to PNG resource development.   The Australian exploration scene continues buoyant, although dominated by gold. The base metals scene is generating, on average, one significant base metal mine developed every couple of years. This is probably the fastest rate of significant base metal development in Australia's history.   The gold scene has been one of incredible dynamics, and there is no evidence that this momentum is waning. The development of new exploration techniques, together with a number of the companies reaching a critical size, has added to the momentum in the industry.

Jan 1, 1995

Kinetic Study on the Leaching of Vanadium from LD Converter Slag Using Sulfuric Acid In order to reduce the environmental impact due to land disposal of LD (Linz-Donawitz) converter slag from steelmaking plant and to valorise this waste material, an acid leaching study was carried out to assess the effect of several parameters on the kinetics of vanadium dissolution. The characterisation and morphology of the feed investigated using XRD, XRF. The factors influencing leaching vanadium such as particle size, temperature, slurry density and the concentration of sulfuric acid were investigated and optimised. The maximum vanadium recovery about 95 per cent achieved at 70¦C, S/L: 1/15, acid concentration: 3M and for 150 minutes of leaching time. The dissolution of vanadium in sulfuric acid shows that there are two stages in the kinetics of leaching. At the first 15 minutes, there is a sharp increase in the amount of vanadium extracted and at longer leaching time, the extraction increase slightly. In the present work, the shrinking core model (SCM) was used to describe the acid leaching of vanadium compounds. A summary of the controlling regimes in the SCM are examined below for short time (less than 12 min.) and long time (more than 30 min.) stages. So, it was found that the kinetics of leaching in both stages is controlled by solid product diffusion regime.

Sep 13, 2010

By L Torckler, R L. Brathwaite

At Neavesville gold-silver (electrum) mineralisation occurs in steeply-dipping zones of intense fracturing, brecciation and quartz veining within rhyolitic pyroclastics, carbohaceous shales and andesites. Hydrothermal alteration extends over an area of greater than 3 by 1.5 km. In rhyolitic tuffs, highly silicified zones containing quartz-adularia-illite assemblages are flanked by less silicified assemblages composed of albite, illite-montmorillonite and chlorite. The mineralogy and sequence of alteration are comparable with the alteration zones which envelop the steam-producing fissures of the active Wairakei and Broadlands geothermal fields. Primary fluid inclusions in quartz from five fissure veins in the Neavesville field show maximum homogenisation temperatures ranging from 220 - 260¦C and salinities of 0.0 - 1.1 wt per cent NaCl equivalent, which cover a similar range to actual measured temperatures and salinities in geothermal fluids at Wairakei and Broadlands. The age of the rhyolitic pyroclastics and related alteration and mineralisation is probably Pliocene and Neavesville therefore represents a fossil geothermal system. The intensely fractured zones containing the gold-silver mineralisation were probably produced by hydraulic fracturing generated by accumulation under pressure of hydrothermal fluid in blind fault zones. Study of fluid inclusions indicates that hydrothermal quartz associated with electrum was deposited under boiling conditions. High grade electrum mineralisation at Graces workings appears to be localised by reaction of hydrothermal fluid with sedimentary marcasite in black shale.

Jan 1, 1980