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By K Nesbitt

Draw control at Premier Mine is considered important to avoid conditions of isolated draw, which results in early waste ingress, compaction of the kimberlite ore and loss of ore reserves. The Premier Mine kimberlite pipe is unique in that the pipe is cut at a depth of 400 metres below surface by a 75 metre thick gabbro sill. All cave mining at Premier is below the sill and failure to exercise good draw control could cause early ingress of gabbro waste. Gabbro causes problems in the diamond recovery plant and the amount of gabbro sent to the plant needs to be closely monitored. Fortunately coarse gabbro fragments are easy to recognise in drawpoints. It was anticipated that only 85 per cent of available ore would be drawn from the blocks immediately overlain by the gabbro sill before excessive gabbro waste forced the closure of drawpoints. Data on tons drawn per drawpoint and loaded per LHD as well as the tons tipped per pass is gathered by the vehicle monitoring and control (VMAC) system and information recorded by the load-haul-dump (LHD) drivers. Draw control staff monitor drawpoints on a shift basis and record the occurrence, type and height of hang-ups. Information pertaining to the status of the drawpoint in terms of support, waste and availability is also recorded. A database has been compiled that has been used to analyse the overall pattern of draw control, the frequency of occurrence of different types of hang-ups, secondary blasting efficiencies and drawpoint and LHD productivity. The gabbro sill has provided a unique marker horizon that has allowed the arrival of rock from a level 100 metres above the production level to be recognised. Data shows that ore migrates extensively towards groups of drawpoints that are heavily drawn with many drawpoints more than 100 per cent drawn before gabbro waste was recognised. This indicates that an accurate mixing algorithm is essential for good draw control. Data on tons drawn, drawpoint availability, productivity and the occurrence of various types of hang-ups has allowed better control of the mining operation and provided data for planning future caves. In the BA5 mining block a drawpoint spacing of 22 metres, horizontally across the major apex, has still allowed drawpoints to be pulled to waste with no loss of ore. In the BB1E mining block the drawpoint spacing has been increased to 23 metres and no problems have been experienced to-date. Future initiatives centre on improving the data gathering integrity of the vehicle monitoring and control system and a linear programme that will optimise draw control and productivity.

Jan 1, 2000

By J M TORLACH

Learning is an iterative process, and we might reasonably expect that after more than a century of mining during an era of sustained technological development, (following a millenium or two of unrelieved hard physical graft), that the more obvious physical hazards could by now be competently managed. It is perhaps a reflection on the perversity of human nature that we have not fully learned our lessons in this exacting environment, and that worse, we have still too often failed to profit by the experience of those lessons. The more obvious underlying factors which impact on this situation are examined briefly, as a prelude to consideration of some outstanding examples of recurrent problems experienced in recent years. Reasons for the continued existence of sub-standard practices are outlined, with a focus on the human element, and finally proposals for appropriate remedial strategies are summarised. This paper therefore seeks to examine and discuss some of our deficiences and to suggest some directions for the way ahead.

Jan 1, 1992

Information obtained from a reconciliation system provides fundamental indicators to an operations performance and is often neglected as a key performance indicator when developing a business plan or mining schedule. The cycle of exploration, ore definition, mining and processing within a company is constantly scrutinised both internally and externally as to the safety, environmental and financial performance of these activities with the operators judged on their performance on a periodic basis. However, it is not unusual for the reconciliation process to be given scant attention until a serious issue (usually a shortfall) occurs, at which point short-term solutions may be implemented which only serve to compound the original problem. A robust reconciliation system takes time to develop and implement initially and must continue to evolve with time. The best systems are those where all the stakeholders in the ultimate outcome are involved in the design and accept responsibility for the validity of their component inputs. Output from the reconciliation process can be utilised to fine-tune all aspects of an operation once the underlying issues leading to a particular result are understood.

Jan 1, 2002

By R K. Dayal

Many transport tunnels show distress after few decades of construction. Owing to exorbitant cost of replacement, rehabilitation of tunnels has become inevitable and rapidly gaining attention/significance worldwide. This paper discusses the detailed planning and design of remedial measures for repairs and rehabilitation of the twin tube highway tunnel in India, at an elevation of 2200 m constructed approximately 38 years ago. The tunnel length is 2547 m having 30 m2 cross-sectional area of each tube. The tunnel is lined in stretches, totalling 60 per cent lined and the remaining portions are unlined. The tunnel has developed acute problems of rock falls, water leakage, distressed pavement and icicle formation resulting in slow movement of vehicular traffic which has also increased. Suffocation inside the tunnel caused deaths due to inadequate natural ventilation, hence artificial ventilation was deemed necessary and was provided in the restricted 28.5 m2 cross-sectional area of tunnel. The paper would be useful for planners, designers and construction engineers for setting future trends.

Jan 1, 1999

The New England Fold Belt forms the easternmost and youngest section of the Tasman Fold Belt System of eastern Australia. From middle Palaeozoic to Early Cretaceous time it was the site of extensive episodic calc-alkaline magmatism related to W-dipping subduction. The oldest rocks may have formed at least partly in a volcanic island arc, but from the Late Devonian, the fold belt developed as a convergent Pacific-type continental margin. For Late Devonian-Carboniferous time, parallel belts representing continental margin volcanic arc, forearc basin and subduction complex assemblages can be recognised. Major dextral transform faulting may have offset parts of the fold belt in the Late Carboniferous. In addition, some structural blocks which appear to be out of place in the overall palaeogeographic setting are possible exotic or suspect terranes. A great variety of lode deposits ranging in age from middle Palaeozoic to Early Cretaceous is present in the New England Fold Belt. The vast majority of these are related to emplacement of extensive granite plutons and eruption of continental silicic volcanics in Late Permian-Late Triassic time. However, volcanogenic massive sulphides and volcanic hosted epithermal gold-silver deposits in older rock sequences include one major orebody (Mount Morgan) and several important ones (Mount Chalmers, Cracow, Silver Spur, Cangai and Halls Peak). Some problematical deposits are best classified as metamorphic-hydrothermal. These include gold-bearing quartz reefs and stockworks in sedimentary host rocks, the most important of which are at Gympie, and antimony-gold- tungsten mineralisation in the New England area, mainly at Hillgrove.

Jan 1, 1987

The treatment of nickel ores and concentrates and the subsequent processing to recover separate products of nickel and cobalt is one of the major interests at present in the mining industry. The increasing demand for nickel, and more recently also cobalt, has led to increased exploration for ore sources. Major discoveries have resulted in Canada and Australia. These deposits, as well as others already known, are presently being developed and the process technology tested and evaluated for applicability to the different mineralogical types - mainly sulphide, arsenide and oxide laterites. Concentrates may be treated by either hydro- or pyrometallurgical processes, while the nickel laterites are best suited to hydrometallurgical processing. However, if hydrometallurgy is used, once the ore or concentrate is leached the resultant solutions are then amenable to similar separation technologies for purification and recovery of high purity nickel and cobalt products. Solvent extraction, together with other separation processes such as precipitation, can produce high purity solutions of nickel and cobalt. The final products of these solutions may be nickel and cobalt cathodes, metal powders precipitates or salts, depending on the final process of electrowinning, hydrogen reduction, precipitation, or crystallisation Respectively.

Jan 1, 1996

By Carlini G, Ibba R

The KSS Lead Plant (Kivcet - SNAMPROGETTI - SAMIM) of Por tovesme, owned by Nuova Samim (the sector-head Company for non ferrous metals and derivatives owned by ENI), has been operating since february 1987. This plant is based on the Soviet Kivcet licence and testwork carried out on the pilot plant of VNIITSVETMET in Ust Kameno gorsk fed by the Nuova Samim's concentrates. The plant is com pletely automatized using the most advanced technologies and it is operated by nineteen people on shift work, including all ancillary units and lead decopperizing-casting. The expected performance of the plant has been confirmed and improves day by day in relation of the operating experience, thanks to the new conceptual design of the furnace. Due to the remarkable flexi bility of the process, the integration of the lead plant with the other plants of the metallurgical complex of Portovesme rro-#4 (Electrolytic Zinc Plant, Sulphuric Acid Plant, Imperial Smel ting) has shown all the economic advantages. The lead content in the ambient air, detected by the monitors, either in the working area and on the ground outside the complex, is widely Pb W" below the stricter new limits recommanded by the E.E.C. (Economic European Community) rules and by the Italian law. The whole process is carried out in equipment completely closed and under suction and it does not require manual operations with exposure to the lead. The production cost is much lower than that performed by the traditional technology. This advantage permits wide margin to consider investment to replace the traditional technology.

Jan 1, 1989

By M Wortley, O Gu, D La Rosa, J McMaster

Metso Minerals Cisa have developed VisiofrothÖ û a system which calculates parameters of the froth surface using vision from remote cameras mounted about individual flotation cells. The parameters calculated from this system can be utilised within process control strategies to achieve stabilisation or optimisation of the flotation process. As part of a JKMRC AMIRA P9 field campaign, froth vision was collected from various cells operated at different air rates and froth depths within Rio TintoÆs Northparkes copper roughing and scavenging circuit. At the same time, samples were collected to determine the cell metallurgical performance at each operating condition. These froth images have been processed using the VisiofrothÖ system with froth velocity, bubble size, froth collapse rate and various froth colour parameters calculated. These parameters have been compared to the measured concentrate flow and concentrate grade produced at each condition. This analysis shows that the concentrate tonnage flow is strongly correlated with froth velocity whereas the concentrate grade is best correlated using froth velocity in combination with a bubble stability parameter which affects the bubble size distribution on the top surface of the froth. This paper summarises the results from this analysis as well as an overview of the VisiofrothÖ system and the parameters that are measured by the software.

Jan 1, 2007

Risk Management has been applied relatively slowly in the mining industry. Except for the risk concept application in financial considerations, the application of Risk Management in safety management has been far from satisfactory. When applied it was treated in a global occupational safety and health sense. Regardless of how much the mining industry has progressed over the years it is still, in many respects, `state-of-the-art' business. The safety aspects of mining are well known and yet little understood by the public. Regardless of what has been achieved so far and how much effort has been put into it, mining is regarded as an unsafe and somehow rude business. Safety records of the mining industry vary from State-to-State. Latest mining related disasters in PNG and Queensland and some other fatal accidents support this public perception. They purport a need for change in managing safety in the mining industry. The latest mining fatalities have raised the issue: What must be done to improve safety standards? Duty of care, risk management and system engineering concepts can provide some answers. Risk Management principles which have been advocated for some time provide many answers and explanations and can make safety management more constructive and workable. What has been missing so far is that this concept has neither been applied nor has been modified for its practical application and purpose on a larger scale. A risk management approach to the management of safety and health in the mining industry is addressed, herein. This approach does not attempt to provide the solution. It does, however, provide a basic understanding of what Risk and Risk Management are all about. Rational management of risk is addressed in the life cycle and system contexts. A system of continuous improvement is applied. There is always a chain of events, outcome, exposure, consequence(s), and consequence(s) value(s). It means that development of an event takes place in time and space. Dynamic circumstances have been created in or within the system. It is a decision-making process designed to provide a methodology which is directed not toward a mathematical model but toward easy use and application in dynamic working environment, by decision-makers who can be anybody from either a risk taker or a risk creator. The emphasis is placed not only on arriving at the best practical, possible and fair decision but also on structured and systematic acquisition of knowledge about the system, its hazards and associated risks, hence increasing the decision maker's ability to manage the decision-making process related to the management of risk.

Jan 1, 1995

DIVERSITY There are plenty of examples to show that diversity has been the fundamental downfall of many organisations, particularly when you consider the international position. What about core business, the return of companies to key competence directions and market focus. The stockmarket for instance defines groups and companies in key groups of core business. The expectation is that companies toe the line and do not diversify across their areas of defined expertise. In essence, the market has given notice that the requirements are to focus and stick to our core business. So what right does the conference have to suggest that diversity is the key to prosperity. Hasn't the organiser read the book, studied the history, listened to the market - obviously not. Have they got it wrong, My feeling and belief is no - the organisers have got it right. However, the matter is not as simple as first perceived. What is Diversity, or Diversification as I would prefer? Is it a product position? Is it a geographic position? Is it an expansion or change in services offered? Does a gold mining company diversify into copper or diamonds or aluminium or nickel? Does a gold miner in Australia diversify into China or Kazakhstan or West Africa? How do the two relate? They don't. A successful company will always possess a 'core competence' not so much a 'core business'. The best example of this is the service company extraordinaire - McDonalds. They don't sell hamburgers or french fries, they sell a service, a convenience, a lifestyle. The core business is hamburgers and if McDonalds were to diversify further into new styles of hamburgers, I suggest to you they would fail. But if McDonalds were to diversify into other products based on their 'core competence', provision of service, then I would suggest to you they would be very successful. The service procedure, service machine, service system, the formula, stava the rnnetant the nrnrlnrte -

Jan 1, 1996

By Watson DF

Calculation of the amount of metal in an ore deposit or mining block should be approached by multiplication and integration of appropriate numerical manifolds describing the spatial distribution of the relevant variables, viz. grade, specific gravity and also thickness for bivariate data. Construction of a numerical manifold necessarily involves some form of interpolation but detailed characteristics of this are often not specified in various automatic methods, some of which even provide manifolds with discontinuities. A manifold used in calculations should describe in a geologically plausible way the spatial distribution of the variable of interest. Different approaches to the problem are discussed and compared. Particular computational inconsistencies emerge when "accumulation" is used as a variable in calculations of average grade. If an ore deposit is variable in relation to its sampling and especially if selection of mining blocks according to grade cut-off is a necessary operational decision, the biases introduced by accumulation methods can bring about serious problems of over-evaluation. Modern computational techniques make unnecessary the use of accumulations; because of potential inconsistencies it would seem unwise to use them in any ore reserve computation.

Jan 1, 1987

By S R. Green, G D. Corder

The legacy issues from mining can, and have often, extended well beyond the closure of operations. However, conventional cost-benefit analysis provides little incentive to implement initiatives at the project development stages of a new mining project as the costs that will be incurred towards the end of the mine life, 20 years or longer, appear minor in net present value (NPV) terms. This analysis can be misleading as the true costs of managing post-mining land can continue for many years, or decades, after mining ceases and any resulting unfavourable legacy issues can delay or prevent government permits or licences to develop new resources. Proper upfront planning is critical for implementing successful rehabilitation and closure strategies. The investment in this planning needs to be done in a structured and rigorous manner taking into consideration the long-term and broad benefits of sustainable land uses after mine closure. The advantages of such an approach could include the streamlining of regulatory approvals by early advice to the regulator of identified issues and responses to those issues, and clear evidence that a strong social licence to operate ethic with local, regional and national benefits is included in the decision-making process. This paper investigates the potential closure options for two case studies at the early stages of project development - concept and prefeasibility. By using a sustainability framework that can identify opportunities and risks, prospective initiatives that deliver enhanced environmental, community and social benefits will be compared with compliance-orientated approaches. This comparison is made across the Five Capitals Sustainability Model - natural, human, social, manufactured and financial. The results of this analysis demonstrate that upfront planning during project development and due care and effort during the life of the working mine will reduce the risks of long-term detrimental legacy issues. This will ultimately benefit the mine operator, the local community and the state.CITATION:Corder, G D and Green, S R, 2012. Using a sustainability assessment framework to achieve enhanced legacy outcomes, in Proceedings Life-of-Mine 2012 , pp 311-318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

Various factors influence the exploration geologist or geochemist in his choice of.an analytical method for gold and other elements which may help him find the elusive gold deposit. One of the first decisions the geologist must make is the nature of sample media to collect for his survey. Needless to say there are many media available depending on the situation. These include rocks, soils, heavy mineral concentrates (from overburden drilling and panned concentrates), humus, vegetation, water, lake bottom sediments, stream sediments, etc. The choice of the sample media will depend to a large degree on the state of development of the particular project from grassroots to mine feasibility. The nature of the geological information required will affect which media and which analytical technique should be chosen for the analysis. Valid sampling from the initial sample collection, preparation and subsampling aspects may also help to determine which analytical procedure is best. Cost and turnaround time are of prime. importance to the explorationist, as it should be, however, these aspects should not be detached from receiving accurate and reliable results.

Jan 1, 1987

By Thomas W

Due to record low tin prices and an uncompetitive position in world markets, the Renison tin mine has undergone three major phases of restructuring in the last three years. This has involved substantial job losses, almost all of which have been through voluntary retrenchments. Retrenchments took place in 1988, 1990 and 1991.The last phase of restructuring was the most dramatic, as many aspects of the operation of the mine were changed. New pay structures were introduced, and the miners' contract system was scrapped. Drastic pay cuts occurred in many areas, although the opportunity was also taken to increase pay at some of the lower levels where inequities existed. Work practices were changed, as was the management structure.

Jan 1, 1992

The methods used by the Anglo American Corporation for analysis of long-term metal markets and prices are described. The principal factors affecting the relationships between production costs and metal prices are analysed. These are firstly the type of market, - speculative or consumer commodity, free market or subject to price control; and secondly the rate of growth of demand for the metal. It is shown that virtually all metals will have relatively low rates of demand growth for the foreseeable future, due to market saturation, increased economisation, substitution and product obsolescence. Metal prices have a clear dependance on production costs, however forecasting future costs is by no means simple; amongst other things, account must be taken of changing exchange rates, inflation rates, and the potential for operating more efficiently. The paper concludes by giving brief assessments of the long-term future for aluminium, copper, zinc, nickel and tin.

Jan 1, 1986

By A Purchase, C Stacey

The procedure for operation of deluge systems installed in road tunnels is still a subject of debate. The work undertaken in this paper assists in the understanding of the effects of deluge in road tunnels, and thus aims to help inform the development of operational policy. Analysis was undertaken using computational fluid dynamics (CFD) simulations to help explore the deluge interaction with the tunnel ventilation (including smoke exhaust) and combustion products. It was found, for the scenarios considered, that: Deluge activation can decrease the required critical velocity for smoke backlayering, and this in turn can improve the effectiveness of a smoke exhaust system.The dominant parameter for deluge effectiveness is the vehicle configuration, with shielded scenarios (such as a fire in the passenger compartment) showing almost no water reaching the fire. The water delivery rate (5 mm/min versus 10 mm/min) has only a minor effect on the smoke duct damper inlet temperatures and downstream smoke temperatures for small fires (5 MW). For large fires (50 MW) the higher water delivery rate gives slightly improved performance (lower damper inlet temperatures and lower downstream smoke temperatures). A one-dimensional transient tunnel model incorporating different operational and deluge response policies (ie deluge activation times) was developed. It was used to examine the influence of different operational parameters on life safety risk and tunnel damage risk. It was found, for the scenarios considered, that: The life safety risk for different scenarios has a sensitivity to deluge activation policy with the case of delaying the deluge activation for a long time giving the worst outcomes. However, the most critical parameters for life safety risk are operator response time (for all response activities, not just deluge) and the type of fire (configuration, size and growth rate).There is a reduction in risk of tunnel damage when the deluge is activated earlier, although the fire configuration (ie whether or not the seat of the fire can be reached) has the greatest influence on the outcome. It is concluded that the deluge activation policy should be case-dependent. It will depend on the tunnel, the safety systems provided, and most particularly the vehicles involved. The current policy in Australian tunnels is for manual activation of the deluge by the tunnel operator as soon as practical after the fire is confirmed (see also PIARC, 2007). This is a good policy. However, future work may be helpful to improve the skills of operators to make the best judgement as to when deluge should be activated, balancing all risks. This work could include research to further the understanding of deluge and fire in road tunnels, training programs and consideration of historical fire events.

Jan 1, 2008

Acclaimed as one of the most remarkable orebodies anywhere on account of its length and richness, the Oroya Shoot occurs on the eastern side of the Kalgoorlie gold mining district close to the contact of a fine-grained with a coarse-grained greenstone, and in association with sediments. In the same stratigraphic position on the synclinal flanks of a large drag fold there are a number of other flat ore pipes, smaller, but almost as rich in tenor. Although differing in control structure they are believed to be related genetically as all show a characteristic development of a bright-green ore known locally as "green leader". Folding and bedding structures have played an important part in formation of the ore shoots.INTRODUCTIONThe Oroya Shoot is the biggest individual bonanza of Kalgoorlie's Golden Mile. It has been stoped almost continuously over a length of 4,300 ft., and about 2,000,000 oz. of gold have been won from it. Naturally pillars are not left in the best sections of such an orebody and the detailed geology of stoped out portions can only be inferred from examination of adjacent workings.No mention is made in the literature of the actual makeup of the orebody although a few structures are shown on some of the old cross sections. A diagrammatic cross section, Fig. 1, adapted from Stillwell (1929) illustrates the form of the Oroya Shoot.Gustafson (1937) drew attention to the role of folding, previously unrecognized, in Kalgoorlie geology, and indicated that the Oroya Shoot is associated with a minor drag fold on the east limb of the Brownhill Syncline, itself part of a larger left hand drag on the Central Anticline. The latter in turn appears to be part of a regional right hand fold system as shown by Campbell (1953).

Jan 1, 1959

By Breen AM, Phelan JM, Doherty RJ

Early in 1990, Pancontinental Resources (Base Metals) Pty Ltd commenced flotation treatment of ore from the complex copper-lead-zinc sulphide orebody at Thalanga, 65 km west of Charters Towers in North Queensland. The orebody consists mainly of primary sulphide ore but also contains a substantial proportion of supergene ores which are being processed during the first year of operations. The supergene ores are of three main types, designated as A, B, and C. Supergene A ores are essentially copper ores, containing little lead and zinc, while B and C ores are copper-lead-zinc ores with different degrees of alteration of the original chalcopyrite and different ratios of copper to zinc content. Copper is present in the supergene ores mainly as chalcocite, digenite and covellite. Lead and zinc occur mainly as galena and sphalerite respectively. This paper describes the development of flotation plant practice, aided by laboratory testing, to process the supergene ores. The major challenge in treating these ores is that a varying proportion of the sphalerite is naturally activated and is not easily depressed in flotation by the conventional zinc depressants.

Jan 1, 1991

Host minerals for gold have been of great interest to exploration geologists and metallurgists for a variety of reasons. The depletion of high grade ores in many parts of the world requires that greater attention be given to the study of host min-erals for gold. Some host minerals have been employed in exploration as traces for gold. They are also essential in the design of extraction processes for treating gold ores.This paper reviews the mineralogy of important gold deposits of Papua New Guinea (PNG), Indonesia and New Zealand and focuses attention on the ore minerals and rock-forming minerals that host gold.

Jan 1, 1994

By Johnston R. F

The factors which influence the reduction of chromite are investigated with special reference to Coobina chromite. This was compared with a South African chromite ore. The reduction characteristics are outlined and the reduction kinetics studied Temperature has the most significant effect, followed by particle size, silica addition and type of coal.Electron microprobe analysis of the products indicates that iron in the chromite is first reduced at temperatures above 1100°C, followed by chromium at around 1200°C. At temperatures greater than 1200°C metallic iron and chromium are formed simultaneously and subsequently give an iron-chromium-carbon alloy. It was observed that the metallic carbide contains a small amount of silicon. The decomposition of the chromite spinel was observed to pass through the FeO.Cr2O3, MgO.Cr2O3 and MgO.AI2O3 forms before slag formation. It is concluded that Coobina chromite is suitable for the production of ferrochrome if direct prereduction followed by intensive bath smelting is used.

Jan 1, 1994