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By M Pizey, C Ross

Rehabilitation approaches, methods and outcomes have changed markedly over the last 100 years, and especially over the last 20 years. Alluvial gold dredges have moved from creating a legacy of boulder fields and ponds to radiata pine plantations and highly productive dairy pastures. The rehabilitated farmland has reduced flood risk, improved drainage and efficient paddock design. The next challenge is to include areas of environmental diversity in these projects, for example, shelter belts, patches of native trees, and wetlands that were part of the original landscape.   West Coast coal mines have also come from a legacy of leaving it to nature to rehabilitate damage by mining to establishing native ecosystems or plantation forests. Developments in techniques at Stockton Mine are used to illustrate the changes in approach to rehabilitation of native forest and tussock heathland ecosystems. The proposed Cypress Mine will adopt a full range of avoidance, remediation through rehabilitation, and off-site mitigation techniques in a æthree-prongedÆ approach.   We propose a coordinated extractive industry approach to mitigate for the impacts of mining on native ecosystems and achieve nationally important conservation benefits that individual projects cannot afford. This approach is particularly beneficial in New Zealand, as our native ecosystems must be actively managed to conserve native plants and animals. Currently, some important species and ecosystems are not being actively managed for conservation.

Jan 1, 2004

By J Addai-Mensah, W Skinner, K Quast

The efficiency of any iron ore value-adding operation is closely associated with detailed knowledge of the mineralogy, especially in the processing of lower grade and complex ores. There are a number of physico-chemical properties of iron oxide mineral phases (eg goethite, hematite and magnetite) that can be prudently exploited to enhance their processing efficiency. Recent iron ore studies on the upgrading of high-goethite iron ores have highlighted that the knowledge of the various phases of both iron oxide and gangue minerals is critical to the economic processing of these ores. Appropriate knowledge of this kind can lead to better-designed flow sheets for economically viable production of saleable products. With the increasing use of goethitic materials as blend components of iron ore concentrates for steelmaking, this review paper focuses on relevant beneficiation processes and the pivotal role of mineralogy and petrology in producing saleable iron oxide concentrates from ore blends. For goethites, mineral impurities including silica, phosphorus and alumina are very important. Physical separations, as well as those incorporating higher temperatures, have also been included in this review as potential processes to upgrade high-goethite ores.CITATION:Quast, K, Addai-Mensah, J and W, Skinner, 2017. The importance of mineralogy and petrology on the beneficiation of iron oxide ores, primarily those containing goethite, in Proceedings Iron Ore 2017, pp 233–240 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By K L. Brown

In the Waiotapu geothermal area only Champagne Pool, 109 ng/L, and Waiotapu Geyser, 7.6 ng/L, have dissolved Au concentrations greater than 5 ng/L and most springs have concentrations less than 2 ng/L. When Au concentration data are combined with other physico-chemical data from each spring including; pH, reduced sulphur concentration and temperature, the degree of Au saturation can be calculated. All samples sites except Champagne Pool, Waiotapu Geyser and the Artists Palette are under-saturated with respect to Au(s) by 1 to 3 orders of magnitude. This indicates that adsorption or co-precipitation or both are important processes depositing Au beneath hot springs. Deposition of Au by adsorption or co-precipitation beneath hot springs implies that dissolved Au may not have to reach saturation concentrations for ore to deposit. This interpretation is supported by the presence of substantial Au as sub-microscopic components within sulphide minerals in ore deposits and indicates depositional efficiency beyond that possible through precipitation of Au(s).

Jan 1, 2004

By D H. Lee, J F, J H. Rubinstein

This paper examines the problem of optimising the life-of-mine costs of an underground mine, focussing particularly on the costs associated with the underground development needed to provide access to and haulage from the ore zones. This mine optimisation problem is modelled as a network and a solution technique is outlined. The effectiveness of this solution technique is then demonstrated by applying it to a prototype test example and some actual case studies. Finally, extensions of this technique to other underground mining problems are discussed.

Jan 1, 2000

By P Taskinen, D Lindberg

The increase in metals demand in the electrifying globe means significant growth in the smelting of copper, nickel, zinc, and lead, produced from primary sulfide sources or using sulfide mattes as the intermediates of the process chains. This means that leaner and complex mineral deposits will be evaluated as ores and are in the future traded in the commodity market for smelting and refining to pure metals. An important issue in the trend is the technology metals, like antimony, tellurium, and gallium, which exist as trace elements in sulfide ores and form no ores of their own. Their recovery becomes important in the coming decades as will be the case with growing slag amounts without use in other industries. The key is to produce environmentally acceptable slags in the smelting operations. It sets new boundary conditions to the treatment of flue dusts. This means that all material streams of smelting and refining must be re-evaluated for the deportments of the main and minority metals. In copper smelting, the recoveries of precious metals are today important for the feasibility of the custom smelters but due to low prices of many minority metals they are discarded in slag landfills. It is one of the emerging issues also in the secondary copper smelting today and once the demand grows, the same question will be faced also in the mining-beneficiation-smelting-refining chain of the primary production of nickel, zinc, and lead. The distributions of many technology metals in the copper and nickel smelting have been recently studied using methods where the chemically bound trace elements in the slag and its phases at the smelting conditions have been studied. Thus, the key data about options for process modifications and additional processing steps are piling up. Short processing routes in the metals smelting and refining are attractive due to their simplicity. At the same time, complexity of many raw materials challenges the fluxing at high oxygen partial pressures in low silica slags with high metal concentrations. The compromise between high primary recovery and safe operation is a demanding task in conditions where slag foaming outside the processing window is evident. The increase in the demand of pure nickel is challenging the raw material basis where low-grade sulfide ores are soon smelted along with nickel laterites to matte. It is a demanding task at high MgO concentrations. The low solubility of MgO in iron silicate slags requires new fluxing strategies and new smelting end points for the operation at reasonable temperatures; the direct nickel matte smelting in one-matte mode may be an option.

Aug 21, 2024

Maghemite - A Source of Heavy Medium for Coal Washeries Use of magnetite as heavy medium in coal preparation plants has been increasing steadily in recent years. It might be in short supply in some areas or excessively costly in certain times. In Turkey, the cost of heavy medium magnetite has almost tripled since 2003. As a result, alternative sources of heavy medium material have been evaluated. A maghemite ore from Elbistan-Kahramanmaras was found to be an interesting source. Tests showed that the maghemite ore can be enriched via magnetic separation at 1556 gauss to obtain a heavy medium material with 4.93 g/cm3 density and 97.22 per cent magnetic recovery. Further tests were conducted to determine the optimum field strength for magnetic separation, friability and regeneration recovery.

Sep 13, 2010

The words ""Uncertainty"" and ""Risk"" pervade every discussion about mining exploration and investment. Perhaps these terms are subjectively understood by industry professionals, but objective portrayal of these concepts outside the industry is a woefully undeveloped science. This paper addresses current industry understanding and practice regarding quantitative risk assessment techniques, and provides examples of the application of three of these techniques. Probabilistic techniques for financial risk assessment are valuable adjuncts to conventional financial analysis, and address a range of issues not assessable by any other means. The value of whole-of-project probabilistic risk assessment is currently debatable for decision-making purposes, but is seen as important as a mechanism to focus attention to the critical issues that ultimately impact on project success. The dissection of project capital into risk and non-risk components provides valuable insights into risk characteristics not readily quantifiable in any other way. This technique also provides a framework for more objective ""what if?"" scenario evaluation and for the capital structure of resource projects. Finally, mechanisms for the valuation of undeveloped reserves are examined, and guidelines suggested. The importance of reliability in production cost estimates is highlighted and the impact of early development on reserve valuations is discussed. The importance of economics throughout all stages of the evaluation process is fundamental.

Jan 1, 1994

L&M have been involved on the Shotover since 1980 when we joined Jack and Barney Ryan, who had started in 1972 with gold at $45 per ounce after a successful career as roading and demolition contractors in Christchurch. The first 85 tonne plant was a typical NZ trammel-riffle table plant with an armour plated hull for surviving Shotover floods, and was fed by a 53 tonne UH20 excavator. All this gear had to be carted in over the Skippers road on a small truck or sledge for the heavy loads. This operation was successful and generated the cash flow to sample the lower section of river and plan a second plant. To reduce fine gold losses this was planned to be a jig recovery plant and also included a vibrating screen which saved space and weight over a trammel. There are five flowlines of primary jigs and one secondary, followed by two Knudsen bowls for cleanup.

Jan 1, 1985

Flotation testing has been done at laboratory scale on hematite mineral and ore samples using stage additions of various hydroxamates. Chemisorption of hydroxamate species onto the hematite surface was inferred from the results, possibly involving both the undissociated hydroxamic acid and hydroxamate ion as maximum recovery occurred close to the pKa of the hydroxamic acid. Flotation testing on a specular hematite ore containing 40 per cent Fe and 42.5 per cent silica gave highest iron grades in concentrate at pH 6, in contrast to published data which suggested pH 9 as the optimum value for ore processing. Using octyl hydroxamate, a rougher concentrate assaying 67 per cent Fe at 51 per cent recovery was obtained using four stage additions of 50 g/t at pH 6. For lower grade concentrates still meeting the chemical analysis for pigment grade micaceous hematite (minimum Fe assay 60 per cent) iron recoveries of 80 per cent were possible for stage additions of 50 g/t octyl hydroxamate in the pH range 6-8.

Jan 1, 1999

By N M. Player, R P. Varden, E Jones

"An effective geotechnical design provides an accurate and appropriate assessment, balanced with a mining company’s risk profile. Justifying the cost of slope assessment requires an understanding of the input sensitivities, and resultant risk, to achieve a slope of a required functionality. As a project progresses from Scoping to Feasibility, the geotechnical risk becomes better resolved through increased expenditure on drilling, testing, analysis and modelling as long as the input data is appropriately spatially distributed. Providing accurate and appropriate geotechnical assessments in the early stages provides confidence in all following stages, especially where initial analysis indicates difficult geotechnical conditions. It is also in the early stages of project definition that there is most opportunity to maximise the value of the deposit through investigations into optimal mining methods.This paper examines the advantages of geotechnical engineering input through a project study period. Early geotechnical involvement allows the Scoping and Pre-Feasibility Studies to be more effective. Operational risks can then be better understood and dealt within the Feasibility Study phase, also ensuring that the correct risks and management controls are put in place.With commodity price pressure and cost of resource recovery in a downturned industry, reducing the risk to cash flow, resource recovery and safety should be a primary goal for all mining companies. Reduced risk can be effectively achieved through geotechnical design of slopes to achieve a required performance as part of an integrated study to the Reserve definition and mine design.Citation:Varden, R P, Player, J R, Player, N M and Jones, E, 2016. Justifying Slope Design Risks and Costs, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 185–201 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By Dean J. A, Taube A, White A. H, Messenger P. R, Jones I. W O, Huston D. L

The 50 million tonne Mount Morgan gold-copper deposit (4.99 g/t Au, 0.72 per cent Cu) was an irregular pipe-like body of quartz and pyrite, with subordinate chalcopyrite, magnetite and gold. Mineralisation was hosted by the Middle Devonian Mine Corridor Volcanics which occur as a roof pendant within the Late Devonian Mount Morgan Tonalite. On three sides, the deposit was enclosed by a series of normal, concave, listric faults and surrounded by outward-dipping Mine Corridor Volcanics. The tonalite which bounded the western side of the deposit transgresses the domal structure with no apparent interference. A pipe of intense, texturally-destructive, quartz-sericite-chlorite ¦ pyrite underlay and partly surrounded the deposit.The volcanic setting of the deposit, its shape, metal content and associated footwall alteration are consistent with a subsea-floor replacement origin for the gold-copper mineralisation. Mineralogical studies have confirmed the deposit has been recrystallised and annealed by a thermal metamorphic event, most likely the intrusion of the Mount Morgan Tonalite. Pyrrhotite Pipe mineralisation replaces annealed massive pyrite, suggesting that it formed during retrogressive metasomatism associated with tonalite emplacement. Telluride minerals have a close association with chalcopyrite, and no evidence for a late telluride paragenetic stage was observed. Telluride mineralisation is inferred to be genetically related to the massive sulphide mineralisation, and a separate magmatogenic origin for this mineralisation is discounted.

Jan 1, 1993

By P S. Heithersay, M McGeough

The discovery of Olympic Dam in 1975 and, more recently, Prominent Hill in 2001 and Carrapateena in 2005 demonstrates the potential for world-class IOCG deposits in South Australia. Potential for further discovery of large IOCG mineral deposits in the Gawler Craton and the Curnamona Province is high because of continental-scale pervasive iron-rich alteration, crustal-scale structural preparation and unique magmatic-hydrothermal conditions. Recent exploration successes point to the effectiveness of new exploration tools and technologies to locate this style of mineralisation under cover. The gold endowment of these orebodies located in South Australia exceeds 75 Moz, with further discoveries to come. The lead time between discovery and development of the multi-million ounce Prominent Hill copper-gold mine in less than seven years demonstrates how quickly this style of deposit can be brought into production in South Australia. Clearly these long-life, multi- commodity IOCG deposits mines are an immediate exploration and future growth opportunity for the gold mining industry to replace ever depleting gold inventories.

Jan 1, 2007

The role of government and the community has changed significantly over the last two decades in relation to environment protection, particularly in the mining sector. Increased community expectations have moved well ahead of regulatory requirements, and there is now a much greater appreciation generally of the concepts of ecologically sustainable development and intergenerational equity, and the gap between current practice and practices which would be in harmony with these concepts. Besides providing a `safety net' through regulations to ensure that basic environmental performance standards are met, government is now working proactively with the mining industry to encourage higher levels of environmental performance. This paper describes some initiatives between the Commonwealth government and the industry designed to achieve these higher levels of environmental performance, through programs aimed at the paradigms of best practice environmental management and continual improvement.

Jan 1, 1997

By J R. Leeming

Mines require ventilation to ensure an adequate atmosphere for the sustenance of life, and to dilute, render harmless and remove contaminants.This paper describes the developments in the United Kingdom (UK) from natural ventilation, through the introduction of fire and simple fans, to modern fully independent and remotely monitored and controlled installations.CITATION:Leeming, J R, 2017. The history of mine ventilation in the United Kingdom, in Proceedings Australian Mine Vent Conference 2017, pp 271–276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

For years traditional optical microscopic techniques have been used successfully to carry out mineralogical studies on processing products. Essential information could be obtained by supplementing microscopic data with X-ray powder diffraction data, chemical analyses, etc. However, most of the time the mineralogists working on plant related issues, would supply qualitative information to the metallurgists, due to quantification not being possible in the available time. Since the late-80s, the use of semi-automated to automated techniques for mineral quantification has impacted positively on the use of mineralogy for optimising processing plants. Rustenburg Platinum Mines (now Anglo Platinum) were the first mining company to purchase a Qem*Sem in 1987. With the success achieved in quantifying the minerals in the concentrator streams of the Rustenburg Platinum operations, a second instrument was purchased soon after. These instruments have proven invaluable tools in understanding the flotation behaviour of the sulfide and gangue minerals in the various reefs of the Bushveld. Restrictions in the resolution of these earlier instruments, as well as the time involved in searching for and correctly identifying the fine-grained platinum-group minerals (PGM), meant that these investigations focused on the deportment of the more abundant base metal sulfides, rather than on the actual PGM. The Mineral Liberation Analyser (MLA), which became available in the late 1990s, was well suited to detect and analyse minerals occurring in trace amounts such as the PGM. Anglo Platinum was the first mining company to purchase such an instrument and now has fourteen systems operating at the AR Crown Mines site. One of the applications of these systems involves the study of feeds, concentrates and tailings from the various concentrators on a monthly basis. These routine investigations provide information on a variety of mineralogical parameters, including liberation, association, and grain size. Results are used to emphasise areas for improvement, and specifically underline those areas where improvements will have the most impact on recovery. After new or different technologies have been implemented, mineralogical characterisation of the different process streams is an essential component in the assessment of the impact of these changes on flotation performance. In addition, the knowledge is databased for future reference to draw trends across the various concentrators around the Bushveld complex, and is also used for comparative studies when plants experience high losses to tailings. Due to the success of these investigations the question was posed whether it was possible to obtain data on a daily basis, as compositing samples could hide the impact of daily events. Although the instruments currently used are suitable for a research environment, these are not ideal for mine-site implementation. For that reason Anglo Platinum, together with FEI embarked on a development program to develop a system that can be implemented on-site to measure the important mineralogical characteristics on a daily basis. Important requirements for such a system include time-to-data, ease of use and regular quality control. Highlighting some results from concentrator studies, the presentation will review the progress on the development of automated mineralogical techniques for fast, automated mineral measurements. This is an abstract only. No full paper was prepared for this abstract.

Sep 13, 2010

By Minchinton A

CPeX is a non-ideal explosive performance prediction model. The model takes into account the rate of energy release, the extent of chemical reac- tion and the effect of confinement on energy release. The model resolves the explosive energy into `shock' and `heave' com- ponents as a function of explosive type, hole diameter and rock type. The predictions of the model are compared for a bulk emulsion, and a prill-doped bulk emulsion in soft rock. The predictions, based on calibra- tion of the model with simple unconfined detonation velocity measure- ments, show the significant effect of non-ideality on explosive Performance.

Jan 1, 1988

By R Riquelme

The El Salvador porphyry Cu deposit (26¦ 15Æ Lat S, ~2700 masl) and associated exotic mineralisation is situated at the back-scarp of the late middle Miocene Atacama pediplain in the western Precordillera. New, together with published 40Ar-39Ar data from El Salvador combined with morphologic analysis reveal that the palaeospring plumbing system related to exotic mineralisation at the Damiana exotic Cu deposit and the local geomorphology has not changed fundamentally between the late Eocene and late Miocene. Stable H/D isotope data on supergene alunite from El Salvador indicate an overall increase in dD values (VSMOW) from -74ë at 35.82 ¦ 0.95 Ma to -23ë at ~11 Ma. The transition from strongly to moderately negative deuterium values occurred between ~16 and ~13.5 Ma. Supergene alunite from the El Hueso (3950 masl) sedimentary rock-hosted epithermal deposit ca 35 km SE from El Salvador was dated at 8.19 ¦ 0.01 Ma and yielded a dD value of -25ë. We interpret the increasing deuterium excess as the result of strong evaporation and recycling of meteoric water after ~15 Ma and as indicative for a change in precipitation patterns and climate desiccation. In contrast, the strongly negative dD value for late Eocene supergene alunite points to a more humid climate and an elevation similar to the present. The late Miocene supergene activity at El Hueso is probably related to an uplift of the Precordillera to elevations sufficient for capture of orographically controlled precipitation. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Mine planning includes equipment selection as a subprocess because aging equipment must be replaced to maintain or improve productivity levels. The criteria used for decision-making in mine planning and equipment selection are often inextricably linked and inherently contradictory. For example, financial wisdom demands that development, which is an expense and locks up capital, be deferred as far into the future as possible yet on the contrary technical knowledge suggests that developing well ahead of stoping is practically desirable because it generates additional geological information required to improve planning of the unmined portion of the orebody and create better operating flexibility. Consequently, mine planning professionals have to delicately balance all decision criteria when executing mine planning in order to achieve optimal mineral extraction or when selecting equipment, so that capital is optimally deployed. These two processes can therefore be characterised as belonging to the multi-criteria decision analysis (MCDA) type of problems. MCDA problems are alternatively referred to as multiple attribute decision-making (MADM) problems and belong to a broader group of problems called multi-criteria decision-making (MCDM). There is now a gradual recognition and application of MCDA techniques in the minerals industry. This paper explores the theory, current and potential application of these techniques in decision-making in the minerals industry.

Dec 6, 2010

By K Faure

At Sams Creek a gold-bearing, peralkaline granite pophyry dyke intrudes Ordovician-Silurian metapelite and quartzite. The granite porphyry dyke has a thickness of up to 40 m, extends discontinuously for about 8 km, and intrudes thin lamprophyre dykes along its contacts. The granite dyke and gold-bearing sulphide and quartz-siderite veins within it have been deformed and recrystallised during several phases of folding, the youngest of which is Early Cretaceous.   The unaltered granite porphyry is composed of phenocrysts of perthite, arfvedsonite, aegerine and quartz in a groundmass of the same minerals, with accessory ilmenite, rutile and fluorite. K-Ar dates of amphibole from the granite gave ages of 226 and 246 Ma, but these ages may be a minimum due to resetting during the thermal and deformation events that have affected the area. Unpublished Ar-Ar data on amphibole from the granite show disturbed spectra with high temperature steps around 300-315 Ma, which is consistent with the age of A-type granites in the Buller region. Further age dating of primary and hydrothermal minerals in the granite is continuing. At least three stages of hydrothermal alteration have been identified in the granite. Stage I alteration is characterised by high fO2 magnetite-siderite ¦ biotite, which is cut by thin quartz-pyrite veinlets (Stage II). These are cut by Stage III sulphide, quartz and siderite veins, and pervasive silicification represented by quartz-perthite-albite-rutile ¦ pyrite-siderite-sericite assemblages overprints the earlier alteration stages. Lamprophyre is altered to a siderite-chlorite-sericite assemblage. Stage III sulphide veins are composed of arsenopyrite + pyrite ¦ gold ¦ galena ¦ sphalerite ¦ chalcopyrite ¦ pyrrhotite ¦ graphite, deposited by low fO2 H2S fluids. The gold contains 18-30 wt% Ag and up to 1 wt% Bi. Temperature of vein formation was estimated from vein quartz fluid inclusion homogenisation temperatures (Th 260-355oC, average 330oC), arsenopyrite-sphalerite thermometry (310-365oC) and quartz-albite stable isotope thermometry (340oC). The altered granite and the veins have been deformed, and recrystallised and competent sulphide minerals are fractured and brecciated. Alteration and mineralisation are confined to the granite porphyry and adjacent lamprophyre.

Jan 1, 2004

By D J. Brake

The correct specification and then selection of primary or major fans for an underground mine is a critical decision not only in terms of fan capital and operating costs, but also safety and reliability which usually has a major impact on mine production. In addition, fan manufacturers may spend tens of thousands of dollars preparing proposals for a purchase enquiry for primary fans especially where they have complete responsibility for the installation (turnkey projects). There are many good reasons to thoroughly and fairly adjudicate fan tenders. This paper describes the process to achieve this starting with the initial fan specification through to the final award.CITATION:Brake, D J, 2017. Fan specification and tender adjudication for mine ventilation engineers with particular reference to turnkey projects, in Proceedings Australian Mine Vent Conference 2017, pp 245–252 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017