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Wetherstones gold deposit is located just east of the township of Lawrence, in the Otago District of the South Island, New Zealand. The paper will describe aspects of the mining and exploration history of the Wetherstones gold field, current knowledge of the geology of the deposit, and speculate on possible outcomes of exploration in the modern era.   As at the famed Gabriels Gully situated nearby, most of the Wetherstones gold is/was contained in, or recycled into modern drainages from, the Blue Spur Conglomerate (æBSCÆ). The BSC is the basal member of a wedge of auriferous non-marine sediments of latest Cretaceous age which are tilted against the Tuapeka Fault Zone, a structure of regional dimensions. In particular mineralisation of elevated grade (which cannot yet be reliably estimated) appears to be concentrated in an elongate basement depression (ægutterÆ) of width around 100 m, variable thickness to a few metres, and axial length in excess of 500 m. The gutter plunges from the base of alluvial mining (where it has been partly exploited by underground methods) to depths of more than 100 m, beyond which it remains open and untested.   The prospects for a revival of mining at Wetherstones depend upon confirmation of what is here inferred to exist, and the discovery of additional gold. The economic prospects of the project however are enhanced by what is known or indicated of the geographic location, and anticipated geologic, mining and metallurgical characteristics of the mineralisation, and consequent anticipated environmental management issues.   The recognition of gold contained in pyrite in the BSC represents an upside to project economics which has never previously been evaluated. The Wetherstones Basin covers more than five square kilometres in areal extent. There is no modern exploration record of the majority of this area, leaving open the prospect of the discovery of additional gutters, and primary mineralisation in the underlying schist.   Australasia Gold Ltd has embarked on a program to reassess the potential resources of the Wetherstones gold mineralisation, and to evaluate the feasibility of mining.

Jan 1, 2004

By Massy-Greene RB

Limited recourse financing techniques reduce the financial exposure of equity holders to major mining projects by transfering some of the risks to the banks which provide loan funds for project development. This can only be achieved by a clear understanding of the principles involved. Engineering and management decisions on how the resource is to be developed and extracted must be made in the light of lender's requirements. The structure of sales contracts, joint venture agreements and many other documents can be important in limited recourse financing. If projections show that the debt can be repaid from project cash flow, loan agreements and other arrangements can restrict lenders ability to look to the equity holders for repayment of project loans.

Jan 1, 1981

By J Galvin

This paper addresses the actions of the Australian mining industry, its regulators and educational providers towards ensuring that a pool of competent mine managers is maintained in Australia and that mine management remains a desirable career path for future mining professionals. The Australian and global mining industries are experiencing an acute skills shortage. Mine managers, traditionally drawn from the ranks of mining engineers, are at the sharp end of this shortage. Exacerbating the shortage is a perception that a professional mine manager is not an attractive career option. This perception is influenced by the following forces which combine to make the role of a modern mine manager very demanding:legislative requirements for owners and managers to ensure (guarantee) the safety and health of employees; an increasing trend towards prosecution over exposure to risks to health and safety a need to be more aware and responsive to community and environment; financial, technical and æpeopleÆ pressures traditionally associated with the job of managing a mine; and mine management roles being filled by younger and less experienced professionals. Universities and other educational providers have the challenge of both ensuring that undergraduates are exposed to these issues during their study and continuing to promote mine management as a desirable career option. Anecdotal and statistical evidence indicates that young graduates are choosing and remaining in technical roles rather than taking on the challenge of mine management. Furthermore, it is suspected that the issues referred to above are contributing to the low retention rate of young professionals at mine sites. The challenges are not insurmountable, however. This paper reviews the initiatives of industry, the regulators and educational institutions in addressing these challenges. It includes a focus on:prosecution policies and their impacts, tertiary education program content and delivery modes, CPD initiatives of the Mine Managers Association of Australia, and alternative pathways for obtaining mine management qualifications.

Jan 1, 2006

The correct design and effective operating strategies of metallurgical plants require a constant analysis of data gathered for process control, or for due accountability. Conventional, oldfashion statistical tools often fall short of helping management, either because they are too complicated and ambiguous, or because they fail to address structural problems leading to causes of setbacks. This paper focuses on three statistical tools known for their practicality and the in-depth perspective they offer in attempts to retrieve important information from existing data. These tools also provide a better appreciation of the importance of carefully selected data quality objectives. Chronological data are meticulously gathered and stored at considerable expense: They have value, and it is the duty of management to take full advantage of them. These three selected tools are the variogram and its auxiliary functions, the moving average and its auxiliary functions, and the relative difference plot. This paper offers solutions, and a reference for managers to optimise metallurgical plants.

Jan 1, 2002

By M Eichorn

Running a successful reagent plant trial is not an easy task, especially when trying to achieve an incremental improvement in a highly variable process, such as flotation. Cytec aims to achieve one per cent recovery improvement with 90 per cent statistical confidence. Most concentrators experience large fluctuations in recovery and so the æmagicalÆ one per cent is difficult to detect. With the aid of statistical software, including REFDISTR (proprietary) and ECHIPR, Cytec have developed a unique approach to differentiate between daily operational variation and actual process improvement. This paper describes how Cytec runs a plant trial based on extensive laboratory investigation and detailed analysis of historical plant data using statistical techniques.

Jan 1, 2000

By M J. Cole, J Zhou, D J. Borrow, S M. Iveson, K P. Galvin, J L. Sutherland

New technologies can easily take around ten years to commercialise. Strong research support is needed in parallel with the process of innovation and commercialisation, in building a deeper understanding of the underpinning physicochemical and hydrodynamic forces that deliver the separations, in achieving improvements, in the deployment of a new technology, and in expanding the innovation platform to create new IP. External investment beyond the research, derived from the genuine value proposition of transformational change, funds the pathway for traversing the so-called Valley of Death.

Aug 24, 2022

Mineral policy is now generally regarded as a function reserved to government. Government is reponsible for the economic health and progress of nations, and must therefore interest itself in minerals as a basic national resource. Government should therefore identify objectives which it sees as suitable and necessary for the mineral industry so that the industry can play its part in achieving national goals. It should provide the legislative framework and policy guidelines to enable these objectives to be achieved. The essential objective of a national mineral policy should be rational development of the nation's minerals resources. To achieve this, it need not be too formal; broad guidelines are enough. But it must be dynamic, to keep pace with the changing circumstances of the mineral industry in the world scene and the changing requirements of government. It should be flexible, recognising that there is no such thing as a "typical" mineral deposit; above all it should represent the outcome of a continuing dialogue between government and industry. Both government policy and corporate planning need to be formulated on the practical understanding of the potential economic value of the mineral sector and what it can contribute to the nation's prosperity. There needs to be a common understanding of the wide range of the costs of risks that may arise through the exploration and development stages and of the uncertainties affecting ventures at the production stage. There needs to be a common understanding that the size and importance of the mineral sector is determined in the long run by the level of investment in exploration. The development of a continuing understanding between government and industry should lead to the formulation of ground rules which ensure the continuance of a strong industry able to adapt to the changing world scene and make its contribution to national growth and wellbeing.

Jan 1, 1986

By D Landriault, G W. Wilson, L Langetine and

Engineered soil covers are used for final closure options for both waste rock and tailings disposal facilities. Currently, cover construction requires excavation of appropriate cover material from a nearby site. If no suitable materials are available, the mine operation may have to ship appropriate materials long distances to the site before the construction of the cover can even begin. This has led to the proposal to engineer cover materials using existing waste materials from the mining operation. The paper presented here describes the results of a laboratory scale testing program to evaluate the potential for blending waste rock, smelter slag and tailings for the creation of a suitable cover material at a site in Canada. Tailings from the local mill, waste rock and slag were collected in the field and blended to create a material with an air entry value similar to the tailings and with physical strength similar to the waste rock. Testing indicated this mixed material could be blended at a consistency of a paste and was suitable for pumping. It can also be compacted to a high-density material. The preliminary results show that it may be possible to blend waste rock, slag and tailings into a material that can be utilised in the construction of a water retaining cover.

Jan 1, 2003

By G R. Ballantyne, M S. Powell, M Tiang

This paper reviews the proportion of energy attributable to comminution within the Australian gold and copper mining sector. The need for this is motivated by inconsistencies in the quoted energy usage data and the lack of a common basis for reporting the fraction of energy in mining that is attributable to comminution. This study should form a reliable basis from which to assess both demand and opportunities to reduce energy consumption.The proportion of milling energy was calculated for the major producers in the Australian gold and copper sector. A sampling methodology created by Powell et al (2003 - 2010) was initially used to provide an accurate and meaningful measure of the energy used in the comminution process. However, no useful method for grouping similar mines was found. Fortunately, a surprisingly large amount of high quality data was found from a number of different sources, allowing the development of robust relationships to be used to estimate a high proportion of the unknown values. The fraction of energy attributable to comminution was found to be dependent on how the total energy consumption was defined. For instance, comminution accounted for 52 per cent of the electrical energy, but only 21 per cent of the total energy publicly reported by the mines because a substantial proportion of energy used on a mine is in the form of transportation fuel (mostly diesel). Critically, the measured electrical energy consumption does not account for transmission and generation losses, while diesel energy usage is typically quoted according to its calorific value. This review proposes that diesel should instead be converted via the mechanical efficiency factor for diesel engines. Using this conversion, comminution was found to account for 36 per cent of the available energy on average. This approach allows a useful basis of comparison for mines regardless of whether milling energy is obtained from electrical or diesel generation. A summary of the results are shown in Figure 7 with other values obtained from literature. The total comminution energy assessed in this study accounts for 1.3 per cent of AustraliaÆs electricity consumption, this figure will increase as the other mineral commodities are added to the study.CITATION:Ballantyne, G R, Powell, M S and Tiang, M, 2012. Proportion of energy attributable to comminution, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 25-30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Equity finance provides the most suitable and frequently the only access to capital during the exploration and evaluation stages of resource projects when project risk is at its highest. Investors are prepared to provide equity funds in the knowledge that they are compensated for the higher risk they take on with higher potential returns or sufficient upside potential to justify the higher risk. The context of resource projects which determines the role of equity finance has changed considerably. Prior to the resurgence of the gold price and the development of new mining technology many resource projects were selectively mining orebodies by underground methods frequently with limited reserves proved up in advance of mining. The limited proved ore reserves base and the volatility of the gold price all contributed to a higher risk and higher return investment environment in which the use of equity finance was more appropriate and frequently the only option for capital raising. The financial risk of a resources project can be transferred to an underwriter who makes the commitment to distribute the financial risk between a number of investors. There is also the opportunity for financiers to use a mix of equity and debt finance to allow a company to proceed with the development stage where without such a mix the resource project would not proceed. By using a level of equity finance the project becomes robust enough in its ability to service the debt finance facility and the project proceeds with the equity participants receiving a suitable risk reward return. The liquidity from the establishment of a market for the company's securities enhances further capital raising and generally enables the company to satisfy its financial requirements on more favourable terms particularly during bull markets. The role of equity finance in the management of the financial risk during the exploration, evaluation, development and mining stages of resource projects is summarised in Table 1. In more detail the principal roles of equity finance and the ways in which equity finance impact on the risk management of resource projects will be considered in turn.

Jan 1, 1994

Mary Kathleen Uranium Ltd. recommenced operations in early 1976 following a twelve year period of care and maintenance. Several sections of the plant were modified or completely changed for the second operation. The most important change was the replacement of ion exchange with solvent extraction as the means of purifying and upgrading uranium rich Isolutions Most of the problems experienced in the solvent extraction system originate from the leach liquor which has a strong tendency to form stable emulsions. This has been countered by some careful control of leaching conditions and by closer observation of operations in the solvent extraction area. Most problems have now been resolved and plant recoveries are quite Satisfactory.

Jan 1, 1978

By Turner W. G, Trundle R. S, Medland D. G

Contracting has evolved from basically a tradesman providing a service for an `employer' to a multi disciplined organisation providing an all compassing service for a client.Having commenced its activities as Thiess Bros Pty Ltd, providing simple earthmoving services in rural Queensland, Thiess Contractors Pty Ltd which provides a wide range of services for Governments and Industry is used as an example of an experienced multi-disciplined Contractor.

Jan 1, 1992

By F Mwijage

"The benefits of measuring blast movement to reduce ore loss and dilution have been recognised by many people for many years and various methods have been used with limited success. Geita Gold Mine is running the pilot study on the blast movement monitoring (BMM) system which is a revolutionary method developed and patented by the University of Queensland and Blast Movement Technology (BMT). The system consists of directional transmitters placed within the shot prior to blasting, which are then located after the blast with a special detector and then the data is processed with purpose-designed software.As part of continuous improvement on grade control, Geita Gold Mine is running a research project in all operating pits with the objective of: quantifying the three-dimensional blast muck pile movement and finally utilise the movement data to define post-blast ore polygons and incorporate the movement dynamics during block modelling,quantify the potential savings for ore loss and dilution,improve mine geologists knowledge of blast dynamics, andstimulate greater co-operation between drill and blast engineers and geologists to achieve optimum blast designs.To any operation with selective mining, it is critical to the economics of an operation to control ore loss and dilution; getting it wrong will result in significant lost revenue. Implementation of ongoing pilot study on electronic balls as determinant on blast movement dynamics on ore would be of longer term solution and big investment pay back.CITATION:Mwijage, F, 2012. Pilot study on blast movement monitoring at Geita gold mine, in Proceedings Narrow Vein Mining 2012 , pp 49-58 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 26, 2012

By D Gericke, R Cooke

This paper presents an assessment of the status in design and operation of deep level backfill distribution systems by referring to case studies and practical experience. The improvements in design and operation of the systems can largely be attributed to an improved understanding of slurry flow behaviour and a corresponding integrated design approach that includes slurry flow modelling, system design and application of the latest technology. The conclusions summarise the lessons learnt from such case studies and stresses the importance of design reviews and audits of existing systems as a means to ensure that the mistakes of the past are not repeated in the future.

Jan 1, 1998

In those days no one worried - there were plenty of other things to do. But in'these days it is different. Everyone worries- and. because there is so much worry, emotion has entered the picture. And, worse than that, capital is being made in political circles. People who were quite unaware, five years ago, that any problem existed, have now become experts on the subject, and shout to high heaven that something should be done - and yet they go on using the leaded high octane petrol they deplore so much. And even scientists, who should know better, adduce only such evidence as fits the argument in hand. And the Press is not without blame - some of its reportings is open to serious question, whatever may be the excellence of its motives. The point is made that one should know what one is talking about. And make sure that the evidence quoted is fact - and make sure too, that all the evidence is used, not only that which suita the argument.

Jan 1, 1971

Severe development difficulties were experienced soon after in-seam mining commenced at Appin Colliery in'1962. Thirteen years later no significant pro- gress had been made in overcoming some aspects of this development problem. Some success had been achieved in destressing roadways both in development and pillar extraction. Longwall retreat mining had shown promise of being highly productive but at an extremely high cost in terms of development requirements both in number of roadways and intensity of support in those roadways. No real advance was made in the problem of driving the first heading of a group of headings under conditions of apparently high stress in directions other than the preferred mining directions, although failure of the roof in this heading did seem to give easier work in the subsequent headings driven particularly if they were driven on narrow centres.

Jan 1, 1976

Two examples of risk assessment and risk management in action are discussed. The first is in a management context in relation to Kingsgate Consolidated LtdÆs Chatree operation in Thailand. Kingsgate has conducted an over-riding risk management program to assess and manage risk across its complete business from the Sydney and Bangkok offices through to the Chatree Mine and the companyÆs exploration group. This example addresses how Kingsgate has applied risk management, particularly to the process operation, and the benefits that have been gained. The second is in an operational context in relation to Minara Resources LtdÆs Murrin Murrin operation in Western Australia. The subject is the methodology and outcomes of a risk assessment across the Murrin Murrin operation specifically to identify and assess risks with potential impacts from $1 M to $7 M. This section of the paper then shows how the outcomes of the risk assessment were integrated into MinaraÆs strategic plan to debottleneck the plant and increase nickel production.

Jan 1, 2004

Separation in magnetic fluids is one of the modern techniques that offer a unique approach to material manipulation in a broad spectrum of industries. Its wide-scale application has been restricted so far for a variety of reasons, including limited throughput, inefficient recovery of magnetic fluids and the cost of commercially available magnetic fluids. This situation has changed recently. Very selective separators, with automated density control, capable of treating a variety of materials in a wide spectrum of densities and particle sizes have been built by DebTech and applied in the diamond industry. Technology for the recovery of magnetic fluids has been developed and low-cost magnetic fluids, with high magnetisation and low viscosity are being produced on a production scale. Scale-up of the technology has been addressed and units capable of treating large tonnages of material have been designed. Such a development thus offers the minerals industry a technology that surpasses the existing technologies in selectivity, efficiency and versatility

Jan 1, 2000

By D R. Rankin, J J. Fuykschot

Forrestania Nickel Mines is owned and operated by Outokumpu Mining Australia Pty Ltd and is situated 400 km east of Perth, WA in the Forrestania Greenstone Belt. Production started in late-1992 at a rate of 600 ktpa and reserves were exhausted in August 1999. Cosmic Boy is the largest of three mines worked and operates in a high stress environment with both very high and very low rock mass strength domains. Stoping commenced in 1995 using conventional benching with long hole slot rises but because of drilling and blasting problems the mine switched to airleg rising. In 1997 the mining method was changed to smaller scale up hole retreat benching with each stope requiring a slot rise of up to 16 m length. This method does not allow top access to the rise location and so airleg rising was used until mid-1998. At this stage mining was approaching areas of higher stress for which it was clear that an alternative to this entry method of rising was required. Small diameter raise boring and Cubex rigs were considered but because of the set up costs were not considered to be viable. Since the ore is relatively soft, burn cuts were developed to make use of specially designed 152, 203 and 254 mm diameter reamer bits (depending on the rise length) and drilled with conventional long hole drilling equipment. These rises are fired in one blast together with the slot rings. In the northern lower section of the mine (below 400 m) the principle stress has been estimated at 60 MPa and this causes minor strain bursting in BIF development headings and loose material to form on walls and backs. Trials of destress blasting modelled on Canadian experience has greatly reduced strain bursting at the face. However only around 300 m of development was affected and so this method had not been optimised when mine development was completed.

Jan 1, 1999

By K Lee, K Fernando, S Rayner

Copper-gold ores have been technically difficult and uneconomical to process due to high consumptions of cyanide. Many copper oxide and sulphide minerals react with cyanide to form copper cyanide complexes, partly contributing to the high level of weak-acid dissociable cyanide in the tailings which is normally experienced during the processing of copper-gold ores. The cost for detoxification, if required for treating these tailings, would further inhibit the development of these copper-gold resources unless the cyanide used for leaching was recovered. Several technologies have been proposed to process copper-gold ores, aiming to recover copper as a co-product and cyanide for recycling in conjunction with the leaching process. A critical review of these processes reveals that a pre-concentration stage (solvent extraction or resin ion exchange) is required. Cyanide is recovered by the conventional Acidification-Volatilisation-Regeneration technique in most cases. A critical evaluation is also provided on technical aspects related to the use of Vitrokele Technology and a newly developed Elutech process in processing copper-gold ores, in particular with its application at May Day Mine.

Jan 1, 2000