Search Documents

By R Long

The founder of social psychology is sometimes identified as Kurt Lewin. In a 1947 article, Kurt Lewin coined the term ‘group dynamics’. He described this notion as the way that groups and individuals act and react to changing circumstances. Lewin theorised that when a group is established it becomes a unified system with unique dynamics that cannot be understood by evaluating members individually. The discipline of social psychology really emerged out of World War II and tackled questions associated with human judgement and decision-making by the Nazis. For a comprehensive look at the development of social psychology look at Abelson, Frey and Gregg (2004).Social psychology is concerned with the way social arrangements affect human judgement and decision-making. What the author has done is apply the knowledge of this new discipline to an understanding of risk, safety and leadership. This paper will explain some of the developments in social psychology, such as the discovery of the bystander effect, Groupthink, bounded rationality, heuristics, risk homeostasis and the Milgram effect.The social psychology of risk tackles the way decisions are made about risk in their social context. Unless organisations understand that decision-making is socially conditioned, they are unlikely to be able to tackle the complexities of culture change or the development of risk maturity.The paper will offer a new understanding of why people do what they do, how risk makes sense and why a ‘dumb down’ approach to safety is dangerous. A model will also be presented that shows the pathway to risk maturity.CITATION:Long, R, 2016. The social psychology of risk, safety and leadership maturity, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 31–42 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By R Barritt, P Scott

Across the globe, it is a common scenario that tailings storage facilities (TSFs) are being decommissioned; however, their subsequent impact on the local environment and landscape can often be overlooked during the mine planning process. In addition, the requirement of a cover system for a facilities closure may not be a priority until the latter stages of the mine/mill operation when potential cover materials may have been utilised elsewhere or, worse, buried. Developing a conceptual design and closure plan for a TSF early in a mining venture is fundamental to its success once operations have ceased. If a cover system is a planned component for rehabilitation of a TSF, it is vital that its design is appropriate to the facility and any local site constraints, such as climate and cover system material availability. It is also strongly recommended that various cover system options are physically trialled at the site by using performance-monitoring instrumentation. Through this process, an informed decision can be made regarding the most appropriate cover system design to meet any regulatory and stakeholder closure objectives and criteria specific to the site in question; however, in order for the cover system’s performance to be determined through on-site trials, it is essential that an appropriate instrumentation design is utilised. Often, little attention is paid to the data that is being obtained, and its importance may only become apparent after several years of monitoring at an expense to the venture. This should not be the case. Many sites have used an appropriate initial planning stage to understand what is required for the successful closure of a TSF, how it can be achieved and how monitoring data can be utilised to prove, or otherwise, that a cover system design will be a success.CITATION:Barritt, R and Scott, P, 2015. Cover system performance monitoring for tailings – are we doing it correctly?, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 283–288 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

Interest in mining narrow, vein-type ones has increased world-wide during the last few years despite the fact that prices of metals have not risen in proportion as production costs of mining, such as labour and energy. In many mines, where narrow ones are mined, the mining technique and equipment used have been poorly mechanised. The mining methods have been cut-and-fill or shrinkage stoping. Pneumatic jack-legs have been used for drilling and slushers have been used for loading. The methods that have been used can be called the 'first-generation' methods. Work has been very hard for miners. It has been dangerous and exhausting. Production volumes of mines, and a s a result of that, also profits have been low.

Jan 1, 1990

By G R. F Alvear Flores

Mineral resources are becoming more complex in composition and structure making it more difficult to produce clean concentrates for primary metal smelting. In parallel, providing technological solutions to the recycling and recovery of end-of-life materials is becoming more important in moving towards the goal of increasing circularity. The availability of fundamental thermodynamic data and advanced thermodynamic tools greatly assists in evaluating these complexities and their impact on existing and new processes. In addition, it is fundamental to support the economic performance of smelters. This paper describes several examples on how fundamental work can be applied to industrial processing..

Jun 17, 2024

This paper considers three aspects of cemented fill practice and research in Mount Isa. Firstly, an account is given of the use of Portland cemented hydraulic fill both in MICAF sills and in recovery of major horizontal pillars in the 650 copper orebody, where, during mining, cemented fill has regularly been exposed on unsupported vertical faces up to 90 ft high. In the paper the main considerations are the role and specifications of the fill used but also included is a brief description of fill preparation and placement.Data resulting from a Portland cemented hydraulic fill sampling, curing and testing campaign covering about 18 months of operating practice are presented, analysed, and discussed. These yield information indicating the mode of operation of a fully-automated fill preparation station, as well as a means of comparing field and laboratory strength results. A technique with potential for use as a fill quality control without actual strength testing is also described. The data collected showed that the fill station can operate within tolerances set on product quality, that laboratory and field strength results are comparable, and that rapidly obtained fillsample properties such as moisture content and void ratio can be related to cement content and strength, and hence used for quality control.Results of a fill research programme conducted by the author in Mount Isa since early 1968 are presented involving Portland cemented hydraulic fill and alternative, cheaper additives for cementing hydraulic fill. The most significant alternative to Portland cement is quenched and ground copper reverberatory furnace slag, whIch behaves as a pozzolan, reacting strongly with any available lime to produce cementitious hydrated calcium silicates and allowing Portland cement reductions of at least 50 per cent without strength loss.

Jan 1, 1971

A flow sheet has been developed to treat a high tonnage highly preg-robbing gold ore. The ore is low grade and fine grained with a high proportion of very fi ne free gold. The key components of the flow sheet include gravity, flotation, intensive cyanidation with direct electrowinning, and carbon-in-leach of the flotation concentrate. The circuit produces a low overall mass pull to concentrate allowing economic intensive treatment of large tonnage low-grade material. Efficient recovery of fine gravity gold using a Falcon concentrator in both the milling and flotation circuits, and subsequent intensive cyanidation in a Gekko InLine Leach Reactor (ILR) is critical to the process with over 70 per cent gold recovery expected in this circuit. Grind size control was also found to be important in controlling the activity of the preg-robbers in the carbon in leach circuit and also in the solid liquid separation performance. Tests at the large-scale demonstration plant have been conducted to demonstrate the effectiveness of this flow sheet. A large low-grade deposit is currently under development with the aim of developing a 10 Mt/a treatment plant with the subsequent addition of equivalent sized process lines in multiples of 10 Mt/a. The economic development of this orebody is critically dependant on understanding and exploiting the properties of the ore. In particular it is critical to minimise the effect of preg-robbers by recovering free gold with Falcon concentrators and InLine Leach Reactors. Recovery of the remaining gold by flotation into a small mass yield allows this fraction of gold to be treated by CIL leaching utilising high carbon levels. It is critical is to ensure operation at the optimal grind size to maximise liberation of the free gold and minimise pregrobber activity. The ore has been identified as preg-robbing with low recoveries obtained if treated using conventional cyanidation and carbon absorption. The mineralogy consists of predominantly fi ne grained free gold with minor sulfides including pyrite and arsenopyrite. With conventional cyanide leaching in the absence of carbon, gold recovery is less than 50 per cent. Direct cyanide leaching of the ore in the presence of activated carbon results in an improved but still uneconomic gold recovery. The gravity recoverable gold (GRG - as defined by Andre La Plante) content of the ore has been measured to be 70 per cent to 85 per cent in various tests with liberation grind size of approximately 106 ¦m. This indicates gold is predominantly free and suitable for recovery by batch centrifugal concentrators into a low mass yield. This property of the ore presents the opportunity to maximise the recovery of gold by separating it from the majority of the preg-robbers prior to leaching. Due to the very fine gold particle sizes and the necessity to maximise recovery of this fine fraction Falcon concentrators were selected for the duty, with their proven high recoveries at very fine gold sizes. The gravity recovery in the milling circuit is designed to be in the range 55 to 65 per cent. This has been achieved in the existing pilot plant using a Falcon operating on ball mill discharge within the mill recirculating load. Intensive leaching in an InLine Leach Reactor is essential to recover the gold from the gravity concentrates. Tabling is not a preferred option since recovery is lower than intensive cyanidation and any gold losses to table tails will report to CIL where recovery is reduced by the presence of preg-robbers. Furthermore, tabling recovery from the gravity concentrates is particularly poor due to the fine particle size of the free gold. ILR recoveries of 98 per cent were demonstrated in the pilot plant using an ILR100BA and leach conditions were investigated in the lab using pilot plant generated Falcon concentrate. Recovery of gold from the pregnant solution was achieved with direct electrowinning at pilot and efficiency and sizing parameters were determined at lab scale. To further increase free gold recovery Falcon concentrators will be installed in the flotation circuit. Location of the Falcons in the circuit is not finalised but installation on the rougher concentrate stream is favoured since it will allow multiple pass recovery. This is expected to recovery a further ten to 20 per cent of the gold, as indicated by lab tests on pilot plant generated material. The gravity concentrate from the flotation circuit will also be leached using InLine Leach Reactors. Initial intensive cyanidation tests carried out on lab generated flotation concentrates indicated higher recoveries than CIL can be obtained even though the concentrates contain significant levels of preg-robbing material. This can be explained by the high cyanide, high pH leaching conditions used in the ILR which alters the absorption equilibrium of the preg-robbers. Further optimisation of the leach conditions will be undertaken once more concentrate becomes available. Recovery of the remaining gold content is achieved by flotation into a small mass yield, however the preg-robbers are also recovered into this concentrate. Due to the presence of the preg-robbers gold leaching must be carried out in the presence of high levels of activated carbon in a CIL system. The recovery has been shown to be strongly dependant on the carbon loading and the concentrate particle size. The carbon competes against the preg-robbers for dissolved gold while excessive grinding increases the surface area and activity of the preg-robbers. This has been demonstrated in test work however the economic optimum leaching conditions and carbon loading have yet to be determined. The grind size is critical to the economics of the project, not only due to its effect on gold recovery but also due to its effect on the major operating and capital costs at both the front and back end of the process. It is critical to grind enough to obtain both gravity free gold and flotation liberation at low mass yields however over-grinding results in large increases in mill size and power at the front end and filtration or thickening costs at the tails. Because these unit operations treat essentially all the plant feed even small changes can result in major impacts on project economics. The viability of this project is greatly enhanced by the high recovery of gold into a small mass yield. In particular the production and intensive leaching of the free gold gravity concentrates will allow over 70 per cent of the gold to be recovered efficiently with minimal impact from preg-robbers. By using flotation the mass of the remaining fine preg-robber contaminated material, to be leached in CIL, is greatly reduced allowing this difficult material to be economically treated. This is an ABSTRACT ONLY. No paper was prepared for this presentation. 

Aug 1, 2010

By Yesil MM, Bozdag T

This paper describes the conver- gence and load measurements carried out in inclined seams at five longwall faces, two of which were supported by hydraulic props and the other three by conventional timber supports in Karadon-Gelik mine. The minimum support capacities determined in this study are compared with the results obtained from two empirical approaches suggested by Wilson (1975) and Jacobi (1981). The characteristics of hydraulic props to be used and support patterns in the longwalls are found, conclu- sions are drawn and suggestions are made. Design nomograms are prepared for field engineers, in order to be able to approach the problem more confidently and realistically.

Jan 1, 1992

By L Hussey

Mt Keith concentrator treats low grade disseminated nickel sulfide ore supplied from the adjoining open pit mine. It is a traditional crushing, two-staged closed circuit grinding circuit (SAG & Ball Mills), followed by a complex split-size rougher, scavenger and cleaner flotation circuit. In 2016, 10.5 Mt was milled, at an average head grade of 0.54% Ni, yielding 35 000 nickel metal tonnes in concentrate.Historical analysis of the plant data indicated that of all the nickel lost in the fines rougher circuit tails stream, 25.6% was recoverable in an eight minute laboratory scale flotation test. These results implied that this fine nickel was readily available for recovery in the plant, either through operational improvements or additional flotation capacity. With operation optimisation ongoing, and capital within the business focused elsewhere, plant personnel were challenged to think differently about improving recovery.In 2012, a separate project to improve plant recovery when treating high talc ore was completed. Amongst other vessels, this project saw the installation of two 150 m3 Outotec Cells to the scavenger section of the fines rougher, middlings and scavengers (RMS 1) circuit. Since installation, the operation of these cells resulted in difficulties immediately upstream with instability in the scavenger cells. It was therefore decided that these cells would be better suited to treating the fines rougher circuit tails.The alterations required to divert these flows were minimal, with the capital project totalling $220 000.In the two years since installation, the fines rougher tailings nickel grade has dropped by 9.9%. The scavenger circuit has also seen a 2.8% reduction in tailings nickel grade, and instability issues were immediately resolved. This project serves as a lesson in how existing plant infrastructure may be better utilised to maximise recovery. Although this is especially applicable when capital constrained, such re-appropriation can be considered at any point to maximise return on existing assets. CITATION:Hussey, L, 2017. Repurposing flotation capacity at Mt Keith nickel concentrator, in Proceedings MetPlant 2017, pp 254–258 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

Education for the Mineral Industry in Australia developed in an uncoordinated but effective fashion till the mid 1960's, with recognised quality in graduates, with output matching demand, and with industry needs being fulfilled. Then in the space of a further 20 years, as company structures expanded, as the number, complexity, and costs of mineral projects escalated, as educational facilities, costs and politics increased, as community perceptions and aspirations changed, as government control of minerals and education increased, and as mineral sales cycles and markets fluctuated widely, the very fabric of Australian Mineral Education fell in tatters. Extractive Metallurgy Education suffered most in this collapse, and no compre- hensive remedies have been initiated. We are all the losers. In the 1990's, the extraction of Australian minerals and metals will increase in international significance, and the education of Extractive Metallurgists must meet this need. After examining the current situation, a series of management strategies are proposed to enable Extractive Metallurgical Education to survive and prosper in the next two decades and beyond. These strategic proposals involve industry, the government, the educational bodies, and individuals, in a range of short and long term objectives, policies, and actions.

Jan 1, 1984

In the last two decades, equipment used in the coal mining operations has become much more sophisticated. The way that work is organised and performed in the industry has also changed significantly. Changes in equipment specification or procedures inevitably means that the risk associated with that equipment or procedure also changes. In an attempt to address this the Joint Coal Board Occupational Health and Safety Trust (JCB) commissioned the University of New South Wales Mining Research Centre and Mine Site Technologies to perform a feasibility study into the development and deployment of Virtual Reality (VR) based training simulators in the New South Wales coal industry. The main aims of the study were to identify, the key providers of VR Technology, the VR options available to the JCB and the information that would need to be included in any simulator. It was anticipated that a critical assessment of these components would produce a format for a cost effective, state of the art simulator that could be readily accessed by all mines. The expectations of the feasibility study were that VR should offer three-dimensional (3D) simulations that are interactive, high-resolution models of real environments based on best practice Safety Management Plans. It was anticipated that the simulations would allow trainees to experience the consequences of poor decision-making and allow them to learn from their mistakes in a safe and forgiving environment. It was envisaged that such simulators would become an addition to the existing training methods used in the industry.

Jan 1, 2003

By ZáWang, F Hungerford, T Ren

Operations in an underground drill site have to co-exist within the mineÆs ventilation and operational system. The space requirements of a drilling operation have to be adapted to the limitations provided in available site space, which is usually defined by standard mining operations and geotechnical influences. These limitations affect borehole design, equipment positioning in the site layout and possible interactions with mining equipment and services such as water and power supply.The ventilation requirements for drill sites and the means employed vary with depth of the site, space and likely presence of gas. All drilling operations provide a particular service for the mine and in each case, drilling must operate in a manner which controls all gas, water and cuttings returning from the borehole. The various standpiping systems employed have evolved under differing influences and must cater for conditions during and after the drilling operations.The influences that gas content, pressure and flow, rib stability, cleat direction, borehole length, potential water pressure and flow have on a mineÆs operation and ventilation systems have to be considered in the design of standpipe length, diameter and fittings. Past history has a strong influence on common practice while worst case effects of a possible in-hole event should be catered for.This paper describes the early drilling systems and their limitations in ventilation and gas management. The drill site dimensions and set-up are discussed in the context of roadway conditions, equipment layout, ventilation and logistics. The use of standpiping to control all returns from the borehole is illustrated by referring to likely scenarios in a drilling site to achieve the most effective sealed depth to accommodate the worst case possibility of intersecting high pressure gas or water during the drilling operation. Practices to allow gas drainage in the return airway of a panel are described.CITATION:Hungerford, F, Ren, T and Wang, Z, 2013. operational management of underground in-seam drilling sites, in Proceedings The Australian Mine Ventilation Conference , pp 43-48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By D Henderson, M Germain

The beneficiation of iron ore deposits to yield haematite and magnetite concentrates for steel making processes typically require the use of one or a combination of wet processing techniques based on gravity, magnetic or froth flotation processes. With the need for more cost-effective technologies with a lower water demand, a re-examination of dry processing techniques has been initiated. For example, a dry processing capability may offer an advantage where suitable quality and quantity of process water hinders the development of a particular resource. This paper describes recent laboratory test work for the production of high grade concentrates using dry electrostatic techniques for -300 ¦m haematite and magnetite ores and compares them with magnetic separation techniques.

Jan 1, 2009

By S Juras

To our geologists at Eldorado Gold Corporation, the release of the gold assays on a new ore zone causes a flurry of excitement. But to our metallurgists, that news is often greeted with the question ‘What’s the sulfur grade’? In our company, we operate and manage projects whose end-product will either be auriferous sulfide flotation concentrate or gold doré. Almost all of the steps in the ore processing are related to sulfur (in this paper specifically sulfide sulfur). So why do we geologists wait until late in a project or into production before collecting sulfur data for mine planning and ore control purposes?Gold deposits associated with sulfides commonly use a metallurgical process that begins with a flotation step to recover gold into a smaller mass known as flotation concentrate. Often, this step solely targets the sulfide minerals with gold only coming along for the ‘ride’. As a result, the gold grade in the concentrate is primarily influenced by the ratio of gold to sulfur in the feed. Should this concentrate require a refractory process downstream (eg pressure oxidation), knowing sulfur grade is critical as sulfur controls heat balance in the process. Regardless, we need sulfur models to be as robust as gold models, and created much earlier in the project evaluation process.Sulfur models require quality data collected at the same density as gold samples. Analytical methods must match expected grade ranges and quality assurance quality control (QA/QC) protocols and must be of the same integrity as in use for gold. Sulfur models will then be created by their own data analyses, interpolation protocols and validation. Furthermore, ore control systems should be designed for regular sulfur monitoring to ensure and enhance downstream value. Given time it should become habitual for geologists to likewise ask, ‘And what’s the sulfur grade’, or more specifically, ‘What’s the gold to sulfur ratio’?CITATION:Juras, S, 2017. Sulfur – the new geometallurgical grade in gold-sulfide deposits, in Proceedings Tenth International Mining Geology Conference 2017, pp 199–202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By Armstrong A

Queensland is Australia's second largest mining state with world-class deposits of coal, base metals, bauxite and magnesite. The total value of Queensland's mining production is about $5 billion per annum, and coal accounts for around 55 per cent of that total. The environmental issues which arise as part of management and regulation of the industry are resolved within the EMOS process. The Environmental Management Overview Strategy is the cornerstone of the policy 'Environmental Management for Mining in Queensland' developed jointly by the Queensland Department of Minerals and Energy and the mining industry. The Gordonstone Coal Mine is the largest underground mine to gain approval under the new policy. Accordingly, Gordonstone has a well planned environmental management program which takes into account site-specific factors and provides for continuous compliance with the provisions of the Mineral Resources Act in a self-regulatory context.

Jan 1, 1994

By S Cyphers, J Missen, B Jansen

The AGL Loy Yang Mine is one of the largest and most significant coalmines in Australia. Commencing in 1982, this mine produces 30–35 Mt/a to supply more than 50 per cent of Victoria’s electrical power requirements. At this mine there are unique geotechnical challenges to overcome to ensure its safe operation including: significant mine depth, low density of coal in the operating and permanent mine batters, the influence of groundwater and deep sediment aquifer pressures. One of the challenges is the behaviour of brown coal, which is neither a soil nor a rock and displays long-term creep stress relief. Other geotechnical challenges include ensuring stability in high unconsolidated dumps, potential large-scale block movement in mine batters driven by crack water pressure and heave from high-pressure aquifers.The paper will outline the geological and hydrogeological setting and potential failure mechanisms, and detail an integrated geographic information system and reporting regime that in part addresses ground control management at the mine. The paper will also outline the management processes for a dynamic geotechnical environment and the benefits of the alliance arrangements to meet the geotechnical requirements at the mine and the effective personnel integration in the mine technical services team.CITATION:Jansen, B, Missen, J and Cyphers, S, 2014. Geotechnical management at the AGL Loy Yang Mine, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 239–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By T Baumgartl, A Costine, B Boshrouyeh, M Edraki

In mineral processing, the management of tailings may become increasingly more challenging with a change of ore type and the quality of water used in the plant. This, in turn, may affect the overall costs of the operation and water usage and, in the long-term, pose challenges for mine closure and rehabilitation. Depending on the applied treatment technique, the short and long-term properties of tailings are largely determined by the fine particles. Most clay materials and ultrafine particles exist in tailings from oil sands, coalmines and base metals, bringing about challenges in dewatering performance. Moreover, given the growing concern for water scarcity, the minerals industry is increasingly turning towards the use of saline water, which poses yet another challenge for tailings management. The high salt content alters the behaviour of clay particles, making dewatering a more complex process than in freshwater systems (Boshrouyeh Ghandashtani et al, 2022; Costine et al, 2018). High-density techniques for tailings management have been used for several years in the mineral industry. In this regard, one of the novel and promising dewatering methods is in-pipe or inline flocculation, where the polymer is added at high dosages to thickener underflows, giving additional (likely denser) aggregation, releasing more water on deposition compared to low solids thickening. Previous research in the field of flocculation has primarily focused on the process of flocculation itself, specifically the settling rate and size of aggregates, rather than the long-term impacts of the produced tailings materials (Liu et al, 2020; Jeldres et al, 2017). This is particularly true for the novel method of this technology, where polymer is added to the thickener underflow. Furthermore, these studies have used small-scale set-ups using buckets/beakers, plungers and mechanical stirrers for the flocculation process. Unfortunately, these methods lack the necessary control over the properties of the treated tailings, which can lead to irreproducible mixing and dispersion of viscous polymer solutions (Fawell, Costine and Grabsch, 2015). Consequently, a system that can work with a wide range of operational conditions for high-solid tailings material is essential for reliable and reproducible results. The objectives of this study were to determine the effect of different type of polymers in the presence of monovalent and divalent salts on the inline flocculation of artificial tailings. The next step was to evaluate the impact of high-dosage polymer addition on geotechnical properties such as settling rate, consolidated density, rate of consolidation and the hydraulic conductivity of tailings. In addition, this research aimed to fill a knowledge gap and investigate the feasibility of using polymer-treated tailing in removing the copper ions and then quantify the performance of produced aggregates under time-dependent processes.

Aug 2, 2023

By M Aros, L Reilly

Iron ore is normally sold in bulk at certain specifications. These include iron grade and specific contaminant grades, typically silica, alumina, phosphorous and sulfur. These target grades are normally agreed between the mining company (producer) and the steelmaking company (customer).This study presents an alternative to traditional cut-off grade calculation, using linear programming that maximises the total ore inventories within a predefined mining envelope while meeting the specified targets. Providing a feasible mining sequence that maintains the target grade is not covered in this study.The method was applied to Fortescue’s operations. The complexity arising from differing ore quality within each mining horizon, variable yields and upgrades and the need to control iron and contaminant grades provided a good opportunity to test an alternative method of ore selection. The new method significantly reduced the time spent in cut-off selection and sensitivity analysis, and provided an optimised solution.CITATION:Aros, M and Reilly, L, 2014. Ore selection optimisation for an iron ore deposit using linear programming, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 345–350 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

The sequences in alteration and mineralisation from five copper-gold porphyry systems (Taysan and Didipio, Philippines; Horse-Ivaal and Wafi River, PNG; and Goonumbla, Australia) and one gold-copper skarn system (Browns Creek, Australia) are documented in this paper. Alteration and mineralisation in all these systems reflect a common evolution from crystallisation of melts emplaced at shallow crustal levels (zoned potassic -> propylitic alteration), followed by exsolution of volatile-rich fluids from these melts (porphyry quartz ¦K-feldspar/biotite veins and local high temperature advanced argillic alteration), to a progressive cooling of the intrusion which results in associated retrograde alteration. Copper-gold mineralisation in all cases is almost exclusively restricted to the cooler retrograde events. The recognition of the temporal and spatial zonations in alteration and mineralisation in gold-copper porphyry systems has significant relevance in the interpretation of geophysical signatures, overprinting alteration, vein sequences and structural controls, and can lead to more focused and potentially more cost-effective exploration.

Jan 1, 1999

By G MORRIS

The mining industry has been rightly proud of its environmental achievements and it would be fair to say that in some areas the Australian mining industry is at the forefront of world practice in environmental management and mine rehabilitation. The `environment' has certainly been a growth area over the past three decades with growing awareness in the 1960s, some large battles and the of significant legislation in the 1970s. The most important period however has been the 1980s and so far the 1990s where, in addition to the of some more rigorous legislation, we have seen the practical application of environmental management/rehabilitation Techniques.

Jan 1, 1992

By E Baafi, G Brassington

Coal mining operations can impact on various types of surface infrastructure or natural features, including cliff-lines, steep slopes and natural watercourses. Longwall mining leads to a subsidence depression due to the changing geometry of the mined out area. The current regulatory process for managing subsidence in New South Wales (NSW) involves the preparation of a Subsidence Management Plan (SMP). This paper demonstrates the use of a Weights of Evidence (WofE) technique applied within a Geographical Information Systems (GIS) environment to predict potential areas for rockfalls along cliff-lines in the NSW Southern Coalfield. The WofE is a ædata-drivenÆ method that can be used to predict subsidence impacts prior to mining. The WofE method was applied to ten known rockfalls along the Cataract River to evaluate the reduced impact of not mining within 50 m of cliff-lines along the Nepean River. There is significant reduction of probabilities of rockfall occurrence when mining is avoided within 50 m of cliffs.

Jan 1, 2006