Search Documents

Significance of the body of iron oxide, which in part overlies as its hanging-wall the rich chalcocite ore-body at Mount Oxide, Queensland, has been variously interpreted by engineers and geologists who have inspected the deposit.Among the interpretations offered is the one that the body represents the residual of an original medium to low grade...

Jan 1, 1939

By Carlos G. C

Geological mapping in various parts of Australia is revealing a number of regional associations of mineralizations with particular persistent stratigraphic horizons. Such associations have been found in the Broken Hill district of New South Wales, in the Nairne district of South Australia, in the Mount Isa district of Queensland, and in the Cloncurry district of Queensland. The question has arisen as to whether such mineralizations are of sedimentary origin, syngenetic with the enclosing formation, or whether they are of epigenetic origin, and reflect the selective hydrothermal mineralization of favourable beds on a regional scale.The purpose of this investigation is to test the use of sulphur-selenium ratios as an objective method of distinguishing between suphide deposits or sedimentary or supergene origin, and sulphide deposits of hydrothermal origin, with particular application to the districts mentioned. At the same time much data has been accumulated as to the selenium content of Australian sulphide ores. The possible use of sulphur-selenium ratios for this purpose was first demonstrated by Goldschmidt and his coworkers (1933; 1935), and later by Carstens (1941). Goldschmidt and Strock (1935) found that pyrite of sedimentary origin had a sulphur : selenium ratio of the order of 200,000 or more, whereas pyrite of hydrothermal origin had a sulphur: selenium ratio of 10,000 to 20,000. Carstensfound that sedimentary pyrite deposits in Norway contained less than 1 g. Se per ton, whereas hydrothermal pyrite deposits contained 20 to 30 g. per ton.

Jan 1, 1954

By D Craw

Formation of gold-bearing veins in Otago Schist was intimately linked to the structural evolution of the schist belt. The currently-exploited Macraes gold deposit formed in a regional scale shear zone during latemetamorphic uplift of the schist belt. Further exploration for this type of deposit will be facilitated by an increased understanding of the late-metamorphic structural evolution of the schist belt. To this end, a three-dimensional cross section through the Otago Schist has been drawn using structural data gathered at outcrops in a 20 - 40 km wide transect across central Otago. This is the first continuous detailed structural section to be drawn through the belt. The section spans an area from Textural Zone 1 metagreywacke of the Torlesse terrane in the northeast through TZ 4 schist in the central region and across the Caples-Torlesse boundary to Textural Zone 3 schist of the Caples terrane in the southwest. Two different late-metamorphic structural generations are identified in this section: the long-recognised Manorburn Generation, and a new æPoolburn GenerationÆ. The location of the Caples-Torlesse boundary has been refined on this transect by field mapping combined with whole rock geochemistry.

Jan 1, 2001

Two outstanding features of the world's young orogenic belts are their very consistently developed suites of volcanic rocks and, it is now recognized, the rather distinctive types of mineralization they contain. Further,it is now known that these volcanic suites exhibit evolutionary patterns, and it is beginning to appear that this evolution in style of igneous activity is accompanied by a parallel evolution in style of mineralization. Specifically,podiform chromite and stratiform pyritic copper ores of Alpine ultramafic/submarine tholeiite association progressively give way to more zincian stratiform ores associated with andesites and dacites, "porphyry copper"deposits developed in quartz dioritic to dacitic plugs, and lead-zinc stratiform ores related to increasingly pyroclastic, rbyodacitic volcanism.This "coupling" is exhibited well in the volcanic arcs - the young orogenic zones-of the SW Pacific which, with tbeir abundance of youthful and commonly unmetamorphosed materials provide an opportunity for investigating, through a petrochemical approach, the possible significance of ores in the elucidation of mechanisms of lava formation. It is suggested as a working hypothesis that in the orogenic (voleanic arc) regime ores are associated with the cale-alkaline rocks because these cale-alkaline rocks are in part generated by exhalative loss, and the ores are among the manifestations of tbat loss.

Jan 1, 1978

W. Johnson (Consultant, Adelaide) : Is there any mineralogical evidence of temperature of formation of the amphiboles and other minerals present in the crocidolite veins and country rocks7.N. A. Trueman: I am not aware of any definite evidence of the temperature of formation of these minerals, but am of the opinion that high temperatures would not be present during crystallization.No evidence from the qUl'trtz, magnetite and hematite of formation temperatures is indicated and, as the carbonate is later than the other minerals it does not supply any data either.According to Miyashiro and other workers who have studied the composition and stability of the glaucophaneriebeckite series, minerals of riebeckite composition are stable over a wide range of P, T conditions. Recent work by W. G. Ernst, of the University of California, indicate that, in the presence of an Fe203/Fe304 buffer, riebeckite and crocidolite are more likely to form at low temperatures. The occurrence of riebeckite-crocidolite as authigenic minerals has been reported from several localities.Dr. MacLeod (Geol. Surv. of W. A.): Recent regional mapping by the Geological Survey of Western Australia has revealed a total thickness of at least 30,000 ft for the Proterozoic sediments in the Hamersley Basin. In this succession the asbestos-bearing beds of the Brockman Iron Formation at Wittenoom are overlain by some 20,000 ft of younger sediments and volcanics. With such a thickness of superincumbent material, it seems perfectly valid to involve

Jan 1, 1963

By G W. Wilson, M Aubertin

A desulfurised tailings cover was installed at the Detour Lake Mine in Ontario, Canada, to reduce oxygen penetration into the underlying sulfidic tailings. The cover ranges from one to 1.5 m in thickness and was intended to maintain high water saturation to reduce oxygen diffusion and consume oxygen by oxidation of the residual sulfide minerals. The tailings impoundment was instrumented to measure climatic parameters, water levels and water content profiles within the tailings and single-layer cover. One year of monitoring data was collected. Additional tailings samples were obtained for geotechnical and geochemical characterisation. The average grain size of the cover material was found to be coarser than the underlying tailings. Monitoring also indicated that air entry values of the cover material were lower than the tailings. Numerical modelling was conducted on the cover to predict water content profiles under varying climate conditions together with the depth of oxygen penetration and diffusive oxygen fluxes. Estimates of the diffusion coefficient and kinetic oxidation rates from field data compared well with values obtained by laboratory measurements. Numerical simulations indicate water saturations of less than 85 per cent can be expected under varying climate conditions. Predicted oxygen flux rates through the desulfurised cover over tailings with high acid potential indicate low flux rates reaching these tailings due to either consumption of oxygen by residual sulfur within the cover or saturation of the underlying tailings.

Jan 1, 2003

IN 1906, soon after his arrival in New Zealand, a brief article was prepared by the writer on "The Salient Features of the Economic Geology of New Zealand," for the Journal of Economic Geology. In November, 1907, a somewhat similar paper, entitled "The Mineral Wealth of New Zealand," was read at the Royal Colonial Institute in London. The present contribution to the Transactions...

Jan 1, 1909

Northern Iron Ltd (NIL) is an Australian listed company that recently brought the historic Sydvaranger open pit Magnetite Mine (the Project) in Northern Norway successfully back into production. NIL made the decision to operate the Project on an owner mining basis, due to limited large scale mining expertise amongst Norwegian mining contractors, a long mine life, a limited range in planned mining rate and to minimise costs. As a new mine operator in a country where labour practices are strictly regulated, there was the desire to reduce the risk associated employing and managing skilled personnel. This was achieved by coupling the purchase of the required mining equipment from the original equipment manufacturer's (OEM) regional dealers with OEM supported Maintenance and Repair Contracts (MARC). This paper examines the process that was followed to implement an owner mining operation in a short time frame; approximately 12 months from the initial requests for quotation to actual delivery of mining equipment to site, and some of the challenges faced. By following a formal and well-tested process, not only was the implementation achieved in the set time frame, but significant value was added through the cost savings achieved in the equipment purchase price and MARC rates that were negotiated through this process.

May 1, 2010

Upgrading of Superfine Low-Grade Haematite Ores by Reverse Floatation Direct Reduction Low Intensity Magnetic Separation Process

Sep 13, 2010

This method determines tellurium at concentrations down to 0·01 p.p.m., with geochemical accuracy. Tellurium is volatilized from the rock at 800°C in the presence of sulphur from decomposing pyrite, condensed, dissolved, and finally determined by atomic absorption in a long tube burner. The distribution of Te is shown near some gold lodes at Kalgoorlie. Lastly, a method of synthesizing Te-free pyrite from sulphur and ferrous sulphate is described.

Jan 1, 1969

By I Thin, L Morizzi, C Seymour, G Mungur

Olympic Dam has been investigating mine design options for the South Mine Area (SMA), which will continue using the existing sublevel open stoping (SLOS) method. The SMA is an undeveloped mining area, located south of the existing underground mining areas currently in production at Olympic Dam. The SMA study reached the stage where geotechnical inputs were required for stope design, infrastructure location and ground support forecasts. A large database of geotechnical data was collected to inform open pit designs for the ODX (Olympic Dam expansion) project (resulting from 659 drill holes). This geotechnical data has since been reprocessed to align with design inputs required for the SLOS mining method. The result has been the construction of a preliminary three-dimensional mining rock mass model (MRMM) that has been incorporated into preliminary stope mine design and infrastructure layout assessments, which have taken into account the predicted prevailing ground conditions.As with any model, it is necessary to improve the confidence in its predictability; therefore the model must be calibrated. The preliminary SMA MRMM was no exception. First pass calibration was possible with results from underground geotechnical window mapping from exposed rock mass conditions in the lateral development and surface geotechnical holes for ventilation shafts.The SMA project continues to advance and has started a program of resource drilling. Selected holes have been identified that target data limited areas. This will ensure that the data gaps are infilled in order to maintain the required data density required to improve the model confidence. In addition, further underground window mapping in the SMA will provide ‘mine scale drill hole’ data that can be used to either update the MRMM or as part of planned future calibration. Stope performance data from stopes will provide further valuable data for calibration purposes.The proposed paper will present the process and findings that have been followed in order to establish a well calibrated geotechnical model that can be used with an acceptable level of confidence in the ongoing refinements of the mine design and planning process for the SMA.CITATION:Thin, I, Morizzi, L, Mungur, G and Seymour, C, 2016. Building and calibration of a geotechnical model for sublevel open stope design at Olympic Dam, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 523–532 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

The effect of conditioning energy input on the metallurgical results of an emulsion flotation process has beenattributed by previous authors to a detergency process.This paper shows that such a process does not explain the data and that an attrition mechanism is more appropriate.

Jan 1, 1970

By T D. H McGrath, G Wardell-Johnson, E A. Oraby, W Staunton, A R. Bax, J J. Eksteen

"Gold ores often show significant inter-domain variation with respect to the gravity recoverable gold (GRG) content and the leach behaviour of the non-GRG component. Liberation assessment is extremely difficult for gold due to its malleability and the high sampling errors and poor test reproducibility resulting from gold’s high specific gravity and the low metal concentrations that occur in most gold ores. The use of microscopic techniques for the liberation assessment of gold is also impractical due to the high number of sampling errors and high cost of analysis.Curtin University’s Gold Technology Group has developed an online carbon-in-pulp/carbon-in-leach (CIP/CIL) simulation model called SIMCIL, which has been used since 1999 to model and simulate industrial leach-adsorption circuits. Recently the model has been upgraded to include an integrated liberation-leach modelling (ILLM) approach, which can be used to evaluate the impact of various process parameters (such as grind size, bleed to gravity etc) and circuit configurations on leach-adsorption circuit behaviour and overall plant gold recovery. A new time-efficient ore characterisation methodology has been researched and developed to provide the required liberation-leach data used in the ILLM approach, which is implemented online for the modelling of gold operations. The ILLM characterisation methodology, test work data analysis, interpretation and application of the ILLM test work data are discussed.CITATION:Bax, A R, McGrath, T D H, Eksteen, J J, Staunton, W, Oraby, E A, and Wardell-Johnson, G, 2016. An Integrated Liberation-leach Model and Ore Characterisation Procedure for Gold Ores, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 315–320 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

As in other countries, gold mining inNew Zealand has been cyclic in character. Looking at these cycles may provide insights as to what may occur in the future and that is the basis for this study.   New Zealand has experienced four gold mining cycles. The first began in 1857, peaked in 1866 and terminated in 1890. This cycle was characterised by alluvial gold mining by individuals and small groups. This is referred to as the Labour Led cycle. The second cycle began in 1890 and reached its peak in 1906 and terminated in 1929. This cycle was characterised by the use of dredges in alluvial gold mining and was also the peak of hard rock mining. This cycle is referred to as the Technology Led Cycle. The third cycle peaked in 1940. This cycle was far less significant than the previous cycles, arising out of the depression when the unemployed embarked on small scale alluvial mining. This overprinted the continuing decline that occurred after 1906. This cycle is here referred to as the Depression Overprint Cycle.   The fourth cycle began in 1984 when production began to climb rapidly from a very low base. The growth in production was spurred by rising gold prices in the early 1980s resulting in relatively low grade gold-bearing alluvial ground becoming economic. But in the 1990s, production from the new hardrock mines in Coromandel and Otago has overshadowed alluvial production. This cycle is here referred to as the Price Led cycle.   What are the future prospects for gold in New Zealand? Although there are many factors involved, this will be largely determined by two factors; firstly, continued access to prospective gold-bearing properties, and secondly, the price of gold. Based on these factors, three future industry scenarios have been developed. The first of these is industry collapse, in which access to prospective property is constrained and prices mayor may not weaken. The second is industry consolidation, in which the available ground is accumulated by a small number of large companies who can use economies of scale to weather price fluctuations. The third scenario is industry growth, in which access to prospective ground is constrained in environmentally sensitive areas but is otherwise relatively unconstrained. Efficient companies are allowed to work in a policy and economic framework that allows them to make a major contribution to the economy.   While the industry cannot control these critical factors, a good knowledge of the positive role gold mining could play in the future economy may provide a framework by which the access issue, in particular, may be addressed from a balanced perspective.

Jan 1, 1994

By J Dwyer, M Hill

Downer’s mining division has made an operational and financial commitment to developing engineered solutions that mitigate the risks associated with operator proximity to uncontrolled development drill boom movements, and unguarded rotating drill steels.With the potential for serious injury or fatality, these identified risks are categorised as critical. Previous attempts by the industry to engineer them out have produced limited success, with numerous incidents still occurring year on year. Ultimately, the industry (as a whole) remains reliant on procedural prevention for operator safety.Downer understood the success of such an initiative would largely depend on the effective collaboration between operational experience, technology experts and automation. With so many variables requiring consideration; such as physical operator movement, machine boom movements, variable machine positions, and underground environmental impacts – challenging traditional technologies was necessary to deliver an optimal solution.For that reason, discrete detection (similar to laser curtains or beams) was considered not fit for purpose. The use of situational mapping, using rotating lasers, however, provided the optimal solution. The lasers collect data that is then processed using a custom software application.The software application is specifically programmed for tracking and classifying objects within detection zones, using advanced algorithms and filtering. Recognition and removal of non-positive disturbances are possible without losing personnel detection capability. The detection of relevant classified objects (humans) is determined by analysis of object size, age, movement, and speed etc. When the relevant object is detected, an alarm and inhibit function is applied preventing drilling functions.Any breach of the safety zone (forward of the front jacks) will automatically disable the hydraulic boom function. This can only be reset in the cabin once the person or persons have returned past the front jacks of the development drill into the safety zone.Downer, in collaboration with partner YUMARR Automation, has successfully developed this reliable boom isolation system, and is called JumboGuard. The system has now been commissioned and installed across all Downer Mining development drill fleets, operating in Australia.CITATION:Hill, M and Dwyer, J, 2017. JumboGuard – automatic boom isolation system, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 287–294 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

The Greymouth Coal field is situated on the West Coast of New Zealand's South Island and has been mined for coal for more than 120 years. The area covered in this paper is within the Rapahoe Sector of this field and contains >200 million tonnes of low ash, low sulphur, bituminous rank coal. Paper No 6, presented to the 19th Annual Conference of the New Zealand Branch of The Australasian Institute of Mining and Metallurgy in Christchurch in August 1985 by R G Bowman, explained 'A Geologist's View' of the 'Economic Potential of the Greymouth Coalfield', and describes previous geological assessments of the Rapahoe Sector.

Jan 1, 1989

Sluiceboxes can provide a much higher concentration ratio than most other gravity concentrators (up to 50 000:1) at very high overall placer gold recoveries (greater than 99 per cent). They are also very reliable, inexpensive and simple to operate. This combination is very difficult to beat and explains why the sluicebox is still the most important placer gold concentrator in northwestern Canada, Alaska and the rest of the world. A sluicebox is a rectangular fl ume containing riffles on matting, through which a dilute (<12 per cent) slurry of water and alluvial gravel flows. Sluiceboxes are actually centrifugal concentrators with settling velocity playing a minor role in gold recovery. Due to their higher density, gold particles tend to segregate to the bottom of the slurry flow where they form a streamline that is diverted by a low pressure zone into a riffle. Under ideal conditions, this ribbon of slurry will be overturned as it flows down the rear of the following riffle and will continue fl owing in a circular path to form a vortex. At the bottom of this vortex, centrifugal and gravitational forces combine to drive gold particles into or beside the matting. To remove the gold concentrates, sluiceboxes are shut down and the riffles and matting are taken apart and cleaned. The slurry velocity provides the energy that powers the vortex. If the velocity of the slurry is reduced through overloading with solids, insufficient water flows or shallow gradients it may not sustain a full size vortex. If the riffles are too close, too far apart, too tall, or if there is not enough energy available to the vortex, the vortex will not be formed properly and gold recovery will be reduced. If the slurry velocity is too high, extreme turbulence and the resulting scouring will also cause gold losses. Testing sluiceboxes with conventional sampling and evaluation techniques is very costly, time consuming and problematic. Most placer gold ores contain a very small number of gold particles in a large volume of pay gravels. Sluiceboxes can lose coarse gold particles. The presence or absence of one of these particles in a tailings sample can lead to high unpredictable errors (nugget effect) even when large sample volumes are processed with care. Every time conventional samples are upgraded, additional errors are introduced due to the inefficiency of recovery equipment. Nuclear tracer tests are more accurate, faster, cheaper and safer than conventional sampling. In 1989 through 2002, the recovery efficiency of dozens of sluicing systems was determined by mixing radioactive gold particles (tracers) into the feed streams of dozens of placer mines in the Yukon Territory, British Columbia, Alaska and Guyana. Four distinct sizes of nuclear tracers were used and their recovery was related to the design and operational characteristics of the individual sluiceboxes and their pay gravels. At clean up, scintillometers were used to detect the very low level X-ray and gamma ray radiation emitted by these tracers and locate them in the sluice runs. The effectiveness of any given section of riffles was easily diagnosed by the presence or absence of tracers. At every mine the gravel feed rates, water flows, equipment dimensions and riffle performance were measured. After the gold tracers were removed from the fi nal concentrate and counted, the concentrate was sieved and weighed. These gold recovery, weight and sieve data were used to calculate the quantities and size distributions of the gold particles in the original pay gravels and those lost in the tailings. The expired tracers were stored in a lead lined container until their radioactivity was near background levels (about two months). The standard errors from these radiotracer tests were estimated from binomial probability theory with the equation: SE = {(n + p + q) ^ 0.5}/n. Where n was the total number of radiotracers added, p is the proportion recovered and q was the proportion lost. Each overall recovery estimate would be within one standard error of the true recovery value (14 times out of 20) and almost always within two standard errors of the true recovery (19 times out of 20). The maximum standard error with 100 tracers was five per cent and occurred when the recovery approached 50 per cent. With higher recoveries, standard errors usually ranged from one to two per cent.

Aug 1, 2010

The efficiency of water sprays in suppressing airborne colliery dust depends on many variable factors. A survey of previous work in this field shows that swirl spray nozzles are the best dust suppressors.Investigations carried out in an experimental dust chamber show that, in spite of limitations to the application of water sprays in underground use, promising dust suppression efficiencies in mechanised mining can be obtained with swirl spray nozzles.INTRODUCTIONA dust hazard has always been associated with coal mining, and the recent growth of mechanisation has resulted in a greater production of fine coal and dust, thus increasing the hazard. A better knowledge and appreciation of the medical aspects and dust explosion factors has led to practices reducing the seriousness of the problem. However, the dust hazard still exists and its control is basically an engineering problem.Dust, as with any atmospheric pollution, may be removed from the, mine by ventilation, which is an indirect method of control. Direct methods, in which the dust is prevented from being produced and from becoming airborne, should be employed where possible. Of these direct methods the most significant is the use of water sprays.THE DUST HAZARDAn appreciation of the physical nature of the more important dust hazards is necessary before considering the removal of the hazard. The main hazards associated with colliery dusts are the health hazard and the explosion hazard. "Dust" comprises solid particles of size minus 20 mesh Tyler (833 microns).

Jan 1, 1964

In spite of the many contributions that have been made to our knowledge of the creep properties of polycrystalline lead, the precise influence of various factors on these properties is not yet fully understood. Indeed, the position is such that several important points in connection with the creep of lead are a matter of controversy. This has been brought about largely by the fact that, in the case of lead, the changes that are produced in the creep behaviour by slight variations of such factors as the purity, grain sizeand previous treatment are out of all proportion to the magnitude of these variations.In order to study the fundamental properties of lead as related to creep, and so gain a more enlightened perspective with which to consider the creep of lead in general, the work that is described in a series of papers, of which the present paper is the third part, has been carried out. It deals with lead in the form of single crystals.It has been shown (1) - (3) that the grain boundaries as well as the actual grains play a part in the creep of polycrystalline lead. The present work, by eliminating grain boundaries, enables the. contribution of the grains themselves to the process of creep, in other words, crystalline creep, to be studied effectively.This object was, possibly, the major one in this work.

Jan 1, 1940

When the mining and milling of 1100 copper orebody commenced at Mount Isa a satisfactory grade of copper concentrate was difficult to produce. The major concentrate contaminants were fine pyrite and silica, particularly in the minus 10 microns fraction. Studies of the 1100 orebody showed that much of the fine grained pyrite and a proportion of the silica present in the ore contained carbonaceous matter in the form of complete or partial rims and as internal carbon films disseminated throughout grains. The hydrophobic surface property of the carbonaceous material resulted in inherently flotable fine pyrite and siliceous particles.The addition of a 60:40 mixture of nigrosine and dextrine, initially to a prefloat concentrate of the inherently flotable carbonaceous material and finally to the total copper flotation feed, successfully controlled the flotation rates of the carbonaceous pyrite and silica. The objective of a 25 per cent Cu concentrate grade was then achieved without decreasing copper recovery.

Jan 1, 1971