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By H F. Galbiatti, G J. I dos Santos, A de C Zapparoli

The Grao Para and Rio Maria greenstone banded iron formations (BIFs), within the Carajas mineral province, exhibit distinct lithological and petrographic fabrics, together with pronounced differences in their surface expression, real thickness, iron grade and tonnage. These geological differences support a new model for the regional distribution of iron formations in the Carajas Mineral Province.

Jan 1, 2009

To secure a sustainable competitive advantage some smelters may need strategies based on flexibility in feed and product ranges depending on immediate future projections of profitability. This paper explores the technical requirements for strategic diversity in smelting, leaving procurement, marketing and contractual considerations aside. The days when a smelting operation is tied specifically to say only processing zinc concentrates are perhaps drawing to a close. While internationally traded mineral concentrates are available, attractive business opportunities must exist for fully diversified custom smelters. Certain new and emerging technologies have inherent characteristics that are evaluated in this context. The paper identifies the basic building blocks that will permit such a scenario and assesses the technical feasibility. The ability to respond flexibly to environmental pressures is highlighted as being of paramount importance.

Jan 1, 1996

McLeod: Without getting into the argument as to how well we can know our resource levels specifically in the immediate short term, I would like to make one or two points about the future, and perhaps try and persuade people that they are not really facing a doomsday. It is fair to say that over the last few years the rate at which we have increased our resources has far exceeded the rate at which we have used them, and this is likely to continue for quite a few years yet. As people are now looking for a substitute for petroleum, later on we will be looking for a substitute for coal, should the position get serious. After all man is pretty versatile, has plenty of initiative-and makes allowances for experience. It has been demonstrated here by the way people are looking at use of low quality coals and better use of the coals that are available. It would be fair to say that what now we regard as economically submarginal deposits will, by the time we need them, become economic. I think that there is quite a lot in front of us in exploration and finding new reserves. I would like to have comment from yourself sir, because I recall reading a report of a meeting, here in Wollongong I think it was, in which you addressed the local branch on the future of coal in Australia, and you said that the coal basins of Australia had been well explored and there was not much chance of new discoveries. Since that time we have seen some thousands of millions of tonnes turned up in the Galilee Basin of Queensland, we have seen five hundred million tonnes turned up in Lake Phillipson in South Australia. Do your previous comments still apply? I would like to hear from some of the exploration people, who are operating on an Australia-wide basis, as to how they regard our chances of discovering significant new deposits and significant extensions of known deposits. H,artnell: Mr. McLeod has asked me to comment on what he has just said. I think that the important thing is that our knowledge of the main coal basins in Eastern Australia is increasing in detail but for the most part the extent of coal basins is not being increased in respect of their superficial areas. There are additions but they are not substantially changing our expectation of what the main coal basins will be. I believe that our task is essentially to intensify our knowledge of the main coal basins that we know about. This is important for example for the various reasons that Mr. Roach was talking about, that is the problem of surface alienation, jeopardising the chance of recovery when you go to underground operations. My approach to this whole problem is predicated on the belief that coal has a special destiny to perform in the next fifty years. I believe that it is going to take up to fifty years and maybe a little longer before the enormously demanding technology for nuclear power recovery is in fact achieved. When it is achieved the supply of energy to the world will be enormous, much beyond what we have ever even dreamed about. The mind boggles at what the people of the middle of next century, of two thousand and fifty, will command in the way of physical resources. It is going to be, I believe, tremendous, but the technology involved is very demanding. I mentioned to Mr. McLeod the other day that according to the information that I got in November last, 60% of the nuclear power stations in the United States were out of action, by automatic cut offs because of safety requirements. The technology of breeder reactors seems each year to be a bit further off. In the meantime coal I am sure is going to be called on to supply power directly to fluidised bed and other technologies for power generation. It is going to be called upon in the near future, I believe, to supply liquid fuel on a vast scale and the only thing in my view that we should be thinking about is whether the coal producing countries of the world will succeed in producing as much coal as is going to be demanded. I believe the real challenge to the coal mining industries of the world is that they may fail to do what is going to be demanded of them. This is a challenge I believe to mining technology. I think that we should be working deliberately and energetically finding ways and means where underground recoveries, instead of averaging 50%, can average 50% plus, plus, plus, and this is the first requirement. We should be spending many millions every year, here and overseas, on increasing our means of winning coal because every tonne of coal that is alienated and left irrecoverable in the earth is going to weaken the capacity of the coal mining industry to fulfil, what I believe to be its destiny in the next 50 years.

Jan 1, 1975

By S Bright, M J. Masamvu, E K. Chiwandika, S Dandi, S M. Masuka

The depletion of high-grade hard and lumpy chrome ores has forced Zimbabwean ferrochrome producers to resort to low-grade friable ores that have an average of 28 per cent fines against a set limit of 12 per cent. Submerged open arc furnaces currently in use are associated with eruptions within the furnace because of the high amounts of fines, high energy consumption, as well as high SO2 and CO2 emissions. Traditionally employed agglomeration methods such as pelletising and the use of coke in the furnace have been discarded because of the pressure to lower operational costs and to achieve higher profit margins. This research aims to develop a method to incorporate lowgrade friable ore fines and unprocessed coal into production while lowering CO2 and SO2 emissions through a closed direct current (DC) arc furnace. The closed DC arc furnace could incorporate the friable ores and coal while maintaining above 90 per cent reduction rates. Preliminary findings also show that energy consumption could be reduced by up to 35 per cent by incorporating a pre-heating and pre-reduction system using the flue gases from the furnace. In the proposed circuit, the cost of production per ton of ferrochrome might be potentially lowered by an average of 30 per cent.

Jun 19, 2024

By M Hawkins

The Clem Jones Tunnel (formally known as the North-South Bypass Tunnel), a A$2.88 billion road tunnel project in Brisbane, Queensland, was successfully completed almost seven months ahead of schedule. The project included two parallel 4.7 km long road tunnels, 740 m of intermediate roadway access ramps and two auxiliary ventilation tunnels. The tunnels incorporate intelligent tunnel systems, best practice fire and life safety standards and typical civil tunnel elements.Over the duration of the project the Parsons Brinckerhoff (PB) and AECOM (formally Maunsell) design joint venture (MPB) were Lead Designers to the Leighton Contractors and Baulderstone Bilfinger Berger Joint Venture (LBBJV). Construction of the toll road commenced in September 2006 and was completed in March 2010, with the tunnel opening then. Contributing to the success of this project was the continued support the lead designers gave throughout the construction period.This paper will focus on some of the structural elements that contributed to the success of the project – in particular the cable tunnel structure, a small precast, culvert shaped element under the pavement of the mainline tunnel, and the fit-out of the Gibbon Street shaft which were designed to be constructed in a combination of precast and in situ concrete.The cable tunnel was incorporated early in the design phase and runs the length of much of the tunnel. This paper will outline the challenges faced by the designers with implementing this system which provided significant construction advantages, among which were being able to install a separate ventilation duct during construction and to start fitting out the mechanical and electrical conduits and drainage system while tunnelling was still underway.The Gibbon Street shaft had a length and width of 20 m by 40 m and an overall depth of 38 m. A 20 m high structure of precast and in situ concrete was constructed in the base to accommodate mechanical and electrical equipment and provide a take-off access for the southern ventilation tunnel. The construction purpose for this structure was to provide a junction between the tunnel boring machine (TBM) and the roadheader-style tunnels, a staging platform for commencing the roadheader tunnelling, and a platform where the TBMs could be dismantled and removed.The design was assessed and reviewed many times throughout the construction process to address the needs of each of these stages. Innovative use of precast concrete was used to minimise construction time.Additionally, the designers provided support to the construction team from the time of design completion through to the tunnel opening. This meant that the changes to the design and adjustment of construction loadings could also be assessed. The fi nal outcome resulted in an efficient construction sequence and a project that has provided an excellent outcome for the client, stakeholders and community.

Mar 8, 2011

In conjunction with a study on wear of drag bits the effect of clearance angle on penetration rate was studied.Increases in clearance angle from 24 1/2 up to 30° gave an increase in penetration rate. Thereafter the rate was apparently affected by partial clogging with cuttings.Analysis of results was by a linear regression model and the t-test was applied to assess the significance of parameters in the penetration equation.

Jan 1, 1969

Mining is still a significant economic activity within the Hauraki District. The Martha project is particularly significant. Estimates are that in the order of 850 direct and indirect jobs are derived as a consequence of the Martha project within the Waikato Region. The Resource Management Act 1991 (RMA) is New Zealand's primary piece of environmental legislation. It sets out to provide the framework for the control of the use, development and protection of almost all physical and natural resources. Minerals are excluded from the sustainability requirements of the legislation but as mining invariably involves the use of land, all the other elements of RMA apply. The Council's role in dealing with mining changed with the introduction of RMA. It became responsible for administration of those matters that fell within the functions set out in section 31 of the RMA in respect to existing authorisations. Mineral development needed to be considered in the development of the District Plan that the Council is required to prepare. Implementation of the Act has been a challenge for not only local government but for many industries and resource users since it came into force in 1991. There have been, and are, differing views on both the way it is administered and its intent. The Hauraki District Council has been at the forefront of some of the challenges that are a consequence of the Act. Its reactions to these challenges have been consistent. It treats mining in the same why it treats any other industry. At times this approach has not been understood and without challenge from sections of the community.

Jan 1, 2000

By D Trembath

"One of the key risks to the success of a mining operation is the accuracy of the estimates of both the economic mineral and any accompanying contaminants contained within the ore reserve. Misrepresenting the mineralogical characteristics of the ore reserve can result in considerable financial investment in an operation that is in fact uneconomic and/or carries a significant environmental risk. This in turn can result in an unplanned closure of the operation with associated financial, environmental and social legacy. One way to minimise this risk is to undertake high density resource sampling to gain a better understanding of the resource characteristics. However, such an approach is expensive, time-consuming and often impractical. The risk of not having an accurate model is typically assessed during a feasibility study utilising a Monte Carlo simulation method or some form of sensitivity analysis. Importantly, the error margins used in these types of analyses are often based on subjective or very general criteria such as ‘professional judgement’ or an ‘industry standard’. This presentation introduces a conditional simulation method for developing a range of mineralogical distribution models. Based broadly on the method outlined in Journel and Kyriakidis (2004) the proposed approach develops this work further. It combines a geostatistical analysis of the available data with automated mine design software to provide a rigorous method for assessing the confidence in the mineralogical characterisation of the ore reserve. The process is based on simulating possible mine plans based on the statistical characteristics of the available resource sample data. These plans are then assessed against high resolution resource models generated using a Sequential Gaussian Simulation method. The outcome is confidence intervals for important characteristics of the ore reserve estimate relative to the actual resource. These confidence intervals are an objective and transparent measure important for assessing closure risks and represent an improvement over common practice.CITATION:Trembath, D, 2016. A simulation approach for improving the assessment of closure risks, in Proceedings Life-of-Mine 2016 Conference , pp 36–38 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 28, 2016

By J King, T Hunter, R Coleman

"The industry that supports operations and new projects is suffering a rapid decline in the currently severely curtailed capital investment environment. This is evidenced by a decline in the number of skilled teams, who are now centred in fewer locations. Other features are an aging and retiring ‘Baby Boomer’ generation, coupled with a low uptake of new graduates and the uncertainty in predicting future capital expenditure programs and requirements. Combine this with a reluctance of cash-poor operations to modernise and adapt in an environment of low metal prices, and there is a real uncertainty in how service providers will meet industry needs as they evolve.The industry that supports operations and new projects is suffering a rapid decline in the currently severely curtailed capital investment environment. This is evidenced by a decline in the number of skilled teams, who are now centred in fewer locations. Other features are an aging and retiring ‘Baby Boomer’ generation, coupled with a low uptake of new graduates and the uncertainty in predicting future capital expenditure programs and requirements. Combine this with a reluctance of cash-poor operations to modernise and adapt in an environment of low metal prices, and there is a real uncertainty in how service providers will meet industry needs as they evolve.Trends amongst service providers will be put forward as well as developing options and alternatives. These embrace a whole gamut of agile alternatives in the areas of partnering, alliances, commercial and shared risk models and mutual innovations. These will be discussed with some case studies and suggested approaches.Particular emphasis will be upon brownfield expansions and upgrades which have emerged recently as a preferred lower capital and focused way to achieve best practical outcome at lowest cost. There are a number of specific features of such brownfields projects including the requirement for very close cooperation between the execution team, operators, maintenance and suppliers and a maximum usage of site resources and ingenuity. Often, required investment hurdle rates are high, downtime allowed is minimal and site resources usage is maximised. This requires mutual trust, good planning and high health, safety, environment and community (HSEC) standards and practice. In many ways the practices and skills needed are the exact opposite of the historical ‘big greenfields’ project with which the industry has been geared for more recently.Another developing area has been with innovative commercial models and practices. These have been as a direct result of the more challenging investment criteria being adopted and the relative hunger of service providers. It has become more common to look at these commercial/costing alternatives very early in the project cycle as an essential project tool and not just as a possible option. These commercial solutions cover such alternatives as leasing and rental, deferred payments, build–own–operate–transfer (BOOT) and build–own–operate (BOO), whole-of-mine preferred spares and maintenance terms, and aggressive performance targets with real assurance penalties. Once again this requires very close mutual dealings and trust, and sufficient time allocation compared to a conventional approach.Citation:Coleman, R, King, J and Hunter, T, 2016. Upgrades, Modernisations and Expansions... Where Will the Expertise, Capability and Skills Come from in the Future?, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 69–76 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Dickin FJ

Advances in the development and application of in situ imaging of mineral processing operations using electrical tomography techniques are reviewed and illustrated with case studies relating to pneumatic conveying, mixing and centrifugal separation processes. The potential for applying these methods to full three-dimensional visualisation of the dynamic behaviour of flow in pipelines and separators, and the resulting consequences for process-modelling strategies, are discussed.

Jan 1, 1993

By M Kizil

Mining Engineering Degree programs have traditionally had a practical emphasis and have been highly vocational in nature. However, over the years, there has been an increasing attention to the more scientific aspects of the discipline. More recently, the professional institutions, the industry and the community at large have placed increasing emphasis on the broader aspects of the professions: management, finance, humanity, environment and social issues. Notwithstanding this, there has been a continuing emphasis on the practicalities, and most Mining Engineering programs are still strongly vocational in nature. But employers of new graduates complain about the graduatesÆ lack of practicality and readiness for employment æat the sharp endÆ on the mine site.This paper briefly describes some of the more recent developments in the Mining Engineering Degree program at the University of Queensland that attempt to address the problem. Particular attention is paid to alternative learning programs, including applications of virtual reality, practical experience at the University Experimental Mine (UQEM), and the Undergraduate Site Learning Program (USLP).

Jan 1, 2002

By N B. McCaffrey, V Glenn, C Johns, P D. Erskine, A T. Fletcher

"Underground coal mining is the dominant method of extracting thermal and coking coal in the southern and western coalfields of New South Wales. Monitoring mining-related subsidence forms an important component of environmental impact assessments and subsidence management plans, particularly when there are conflicts between the interests and requirements of mining and environment and community groups. However, there are few specific guidelines for monitoring the impacts of subsidence on terrestrial and aquatic ecosystems, leading to inconsistent policy approaches and highly variable abilities of monitoring programs to accurately detect biological change.This paper highlights the use of a conceptual framework to guide the development of a long-term ecological monitoring program at an underground coalmine in the Western Blue Mountains, New South Wales. Two pilot studies are described: determining the level of observer agreement to assess the condition of a vulnerable tree species (Capertee Stringybark) comparing field sampling methods for detecting a rare heath shrub, Epacris muelleri, using a power analysis to determine sampling intensity requirements.These examples demonstrate that investment in initial pilot studies to test different monitoring approaches can have long-term benefits for stakeholders by more confidently being able to detect potential impacts.CITATION:McCaffrey, N?B,?Glenn, V, Erskine, P?D, Johns,?C?and Fletcher, A?T, 2014. Detecting long-term ecological impacts of subsidence from underground coal mining – a tale of two pilot tests, in Proceedings Life-of-Mine 2014, pp 139–152 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 16, 2014

By Ritter K-C, Sturgul J. R, Filess T

The proposed Lihir open pit gold mine is located on Lihir Island in New Ireland Province, Papua New Guinea. The mine will be located within a volcanic caldera, part of which forms the adjacent Luise Harbour. Kennecott Corporation started engineering design work in 1988 and ended in 1993 when a Feasibility Report was submitted to the Papua New Guinea government by RTZ/Kennecott. The project will be managed by the Lihir Management Company. The mining operation will produce approximately 350 Mt of waste and 62 Mt of low-grade ore over the life of open pit mining. Landforms and traditional land use by Lihirians preclude storing mine waste and some of the low-grade ore on land close to the mine site. The mine waste will be composed of hard rock and soft soild like material which cannot be safely used to construct large land waste repositories by truck dumping. Submarine disposal by bottom discharging barges is the only safe disposal method. The barges will also be required to construct a waste platform along the shore for stockpiling low-grade ore. A simulation model of the waste handling system was written in GPSS/H¦ to assist engineers in selecting the optimum size and quantity of barges and loading docks by analysing the interaction between excavators, trucks and barges. The simulation model was written in enough details to model the various functions that will be encountered during mining. Input parameters allowed for variations in the size and number of trucks, shovels, barges and loading docks. Variations in loading, hauling, and dumping times were from user specified distributions. In order to visualise the interaction between the components of the waste mining operation, the simulation was animated using Proof AnimationT""'. It is believed that this is the first application of an animated simulation study for a mine still in the planning stages.

Jan 1, 1995

By M Doran

The Olympic Dam mine utilises 1.1 m to 1.4 m diameter raise bores for generating the initial slot void for most production stopes. Slot raise bores generally span two development levels ranging from 30 m to 50 m in height. Raise bores are reamed upward and typically leave a cap of rock equivalent to two times the raise bore diameter on the drill level (minimum 3 m). This provides safe access over the cap for subsequent production activities. It is therefore critical to ensure robust falling object protection for personnel accessing underneath, and in the vicinity of the raise bore void on the lower level. Recently, a number of mesh failures have occurred at Olympic Dam as a result of falling rock from the underside of the cap and raise walls. In addition, as Olympic Dam transitions to deeper and more challenging ground conditions, rockfall-off onto the raise bore protection mesh is anticipated to increase in frequency. This paper discusses the evolution of raise bore protection mesh used at Olympic Dam and presents results from recent site-based drop testing. This impact testing was carried out using a built for purpose object to replicate point loading and shear failure of mesh wires. Testing was also carried out on an improved mesh design which utilises two layers of Geobrugg high-tensile MINAX mesh. Results from the drop testing suggest an improvement in performance of the raise bore protection mesh is realised with the updated design.

Mar 29, 2023

By D Cliff, K Bailey

Traditionally occupational health and safety (OH&S) has been managed for the direct benefits of reducing injury and illness to workers on mine sites. In the current skill shortage climate it is important to recognise the value that OH&S management can have in assisting mines in minimising their exposure to this issue. In times of skills shortage turnover is high as mines poach personnel from each other. This leads to loss of corporate knowledge and loss in productivity through the need to train new personnel in mine-specific operating procedures. In addition absenteeism can significantly disrupt production as there may be no ready replacements available for key jobs. Pressure will be placed upon workers to remain at work even though they are not completely fit for work, leading to presenteeism and consequently loss in productivity. In addition to the threats to routine operation, the loss of management and professional staff can significantly increase catastrophic risk through loss of experience and corporate knowledge. There is increased pressure to focus on events that occur regularly in the here and the now and underestimate the rare, or unlikely, events.The theme of this paper is that by properly addressing OH&S management at mine sites, companies can minimise their exposure to these problems. Put simplistically, a safe and healthy mine is a sustainable and productive mine. Case studies and relevant literature will be used to support this premise.CITATION:Cliff, D and Bailey, K, 2012. Health, safety and sustainability, in Proceedings International Mine Management 2012, pp 53-58 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By J L. Merritt

The mining industry seeks to engage with and respond to stakeholders through open consultation processes during the various phases of a mining project (Department of Industry, Tourism and Resources, 2006). Two Australian Coal Association Research Program (ACARP) funded projects conducted in the Bowen Basin coalfields in Central Queensland investigated the use of a stakeholder panel for the evaluation of mine site rehabilitation. The panel members were drawn from the local and regional area, and represented neighbouring landholders, traditional owners, AgForce, local government, conservation groups and non-governmental organisations (NGOs) such as Greening Australia and the Fitzroy Basin Association. The approach of utilising stakeholders to establish rehabilitation criteria was proposed as an alternative to the established practice of assessing rehabilitated areas against a suite of quantitative completion criteria; eg >70 per cent vegetative ground cover or <5 t/ha/a soil loss. The basis of this approach recognises the reality that the definition of completion criteria has proved problematic over the last 40 years with no broad consensus reached on the suite, let alone the metrics; eg the exact cover level that will benchmark acceptance of the mine site rehabilitation.CITATION:Merritt, J L, 2016. Zooming out – learning to see rehabilitation through stakeholders’ eyes, in Proceedings Life-of-Mine 2016 Conference, pp 163–165 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

Optimisation and sensitivity analysis of final pit limits is now an accepted procedure for open pit planning studies. Tools to assist the design engineer in an underground metalliferous mine to make optimal choices for the selection of major development, stope geometry and cut-off grade analysis have not been available. The engineer has had to rely on experience and a limited analysis of design alternatives. A new tool called the `floating stope' has been developed to define the optimal (boundary) limit for material that can be economically extracted by underground stoping methods. The method is analogous to the `floating cone' method of open pit optimisation. The geology and mineralisation are modelled as a regular or subcell block model. Included in the model are structural and geotechnical features, and any previously mined out areas. Inputs to the procedure include the minimum stope dimensions, cut-off grade, stope head grade, and the way in which dilution is to be calculated. The optimisation procedure can be directed to maximise ore tonnes, grade, contained metal or the economic (dollar) value of material mined. The procedure can be applied at each stage of mine evaluation and design to assist with preliminary resource appraisal, selection of stoping methods, and detailed mine design. As with open pit optimisation procedures, manual intervention by an experienced engineer is required to produce practical and detailed designs. This practical design should follow the optimised design as closely as possible. The paper outlines the algorithms used in the definition of the stope envelope, and describes the analysis and results of several case studies where the optimisation procedure has been applied.

Jan 1, 1995

By Leigh J. H

A history is given of the dust control techniques developed and applied by the mining companies at Broken Hill. A history of the regeneration works undertaken since 1936 is out- lined. Particular emphasis is placed on the stabilization of mine residue dumps which are located throughout a belt of mining leases in the middle of the city and which began in 1937. The establishment of vegetation for dust control techniques is discussed in detail and a case study is given of the successful revegetation of the sides of a 650 metre long, 350 metre wide and 35 metre high residue dump.

Jan 1, 1976

By H von Blottnitz, J L. Broadhurst

Eco-efficiency has been proposed by the World Business Council on Sustainable Development as an environmental performance indicator framework that contributes to sustainability by assisting corporate decision makers improve the environmental performance of their operations and processes, while also extracting additional economic value. Given that the recent engagement of the minerals industry with sustainability has highlighted the need for requisite tools and methodologies, it is therefore of interest to assess whether eco-efficiency indicators can drive sustainability performance improvement during process design within the minerals industry. Previous work indicates that the choice of sustainability performance indicators to be used for decision making needs to be governed by the decision context; ie the performance indicators need to be fit-for-purpose. Here, the strengths and weaknesses of eco-efficiency indicators are analysed using case studies. First, a more rigorous definition of eco-efficiency indicators for the minerals industry is proposed based on indicators currently offered in the literature. Two case studies are then selected to reflect typical decision situations encountered within minerals process design. For each case study, eco-efficiency indicators are computed and are compared to more traditional graphical representations of the economic and environmental performance of process design alternatives considered. The sensitivity of these indicators to various process design parameters is also investigated. Results confirm that the meaningful application of eco-efficiency indicators is strongly dependent on the decision context in which the process data is generated. Results also show that eco-efficiency indicators can be related to technical process design parameters to allow for richer communication of performance information for various decision trade-offs; however, in some cases, graphical approaches that provide more insights into the environmental-financial trade-offs should be preferred. The research thus contributes to guiding the selection of the appropriate tools for more environmentally sustainable design of minerals beneficiation processes.

Jan 1, 2009

The revival of the mining industry at Captain's Flat after a long period of years of inactivity has attracted attention to the importance of the ore-deposits of that field as potential sources of supply of lead and zinc. Mindful of the necessity for taking stock of the State's mineral resources, the Department of Mines of New South Wales as part of its programme of geological investigation, carried out a survey of the oredeposits and associated country rocks during 1938 and 1940.Surface geology was mapped in detail and all available exposures were examined and logged. Unfortunately, and this condition militates against the formulation of conclusions because of insufficiem.t data, some of the older workings, notably in Keating's Section, were inaccessible and the logging of levels and stopes is by no means as complete as could be desired. However, with the progress of development and exploration, further information of geological value will come to hand for incorporation in supplementary reports. It may be expected that, under such circumstances, modification of certain statements herein expressed may be necessary but it is not anticipated that any vital alteration will be occasioned.Within the State of, New South Wales, Captain's Flat ranks second to Broken Hill as a pqtem.tial producer of lead and zinc. In addition, large quantities of iron pyrites are available for the manufacture of sulphuric acid which finds application in the superphosphate industry.The mines are now controlled by an operating company known as Lake George Mines, Ltd., incorporated in New South Wales, the parent organisation being the Lake George Mining Gorporation Ltd., registered in London.Over £600,000 has been spent by the Company in exploration, mine development, surface plant, housing and water 'conservation, while the State' Government constructed a branch railway from Bungendore at a cost of £200,000. The various activities consequent upon these development and construction programmes and the prospect of employment in the industry has led to a rapid increase in the population of the township.The State, generally, has benefited to the extent of a substantial contribution to the relief of the unemployment problem, and it is hoped that reasonable permanency will be assured to some hundreds of workers for many years.

Jan 1, 1941