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Lithocaps are potentially voluminous zones of advanced argillic and associated argillic alteration located above the subvolcanic intrusive environment. They constitute exploration objectives for epithermal and porphyry-type deposits. High-sulphidation epithermal deposits may be sought within lithocaps, whereas low-sulphidation deposits may exist on their edges. Porphyry Cu-Au/Au deposits may be accessible beneath lithocaps if systems are telescoped sufficiently. Oxidation of the basal, pyritic parts of lithocaps may promote supergene sulphide enrichment under appropriate tectonic and climatic conditions.

Jan 1, 1995

By Kandemir H, Stafford G

The Croydon Gold Mine is located in northwest Queensland and is a joint venture between Central Coast Exploration N.L. and Pancontinental Mining Ltd. The mining operation commenced in 1987 and consists of satellite open pit mines feeding a central Carbon-In-Pulp gold Treatment Plant. The gold mineralisation is hosted by quartz veins within the Croydon Volcanic Group and the Esmeralda Granite, a cogenetic igneous suite of Middle Proterozoic age. The mineralisation comprises gold and silver with associated basemetals. The gold and silver electrum occurs as extremely fine free grains. The gold distribution is heterogenous occuring across the full vein width, or restricted to the footwall or hangingwall. The average mineral resource grade is 3.5 g/t. The deposits are all hard rock and mining is carried out by drill and blast technique. All mining activity is carried out by a mining contractor. Mining is by a selective mining method which entails the drilling, blasting and extraction of the hangingwall waste prior to orebody extraction.

Jan 1, 1989

Coal washing practice can be improved not only by critical examination of the plant being operated but also by studying plants operated in other areas. The developments at the Australian Iron & Steel Pty. Ltd. plants are discussed in relation to experiences there as well as developments which have taken place in Queensland in recent years. Early A.I.S. problems involved small coal cleaning in heavy medium cyclones and flotation. A proposed future plant flowsheet for A.I.S. is considered in the light of these experiences. Reference is made to plants operated by the Thiess, Peabody, Mitsui Coal Company Pty. Ltd. at Moura and the Utah Development Company's plants at Blackwater and Goonyella in the development of coal washing prac- tice in Australia.

Jan 1, 1975

Commercial or potentially commercial deposits of coal occur in Australia in strata ranging in age from Permian to Tertiary. The coals of each period tend to show a community of petrographic character and significant differences as compared with coals of other ages. In particular- many of the Permian coals are unusually rich in inertinite whereas the Jurassic and Tertiary coals are typically very rich in vitrinite. The majority of the coals show evidence of deposition in environments subject to relatively minor marine influence. Except for some Tertiary and Permian coals the content of mineral matter tends to be high. Outcrops of coals of bituminous rank appear to be largely restricted to the eastern margin of the Australian continent. In this region vertical rank gradients are generally higher than in the other sedimentary basins and uplift and the removal of cover has occurred to a greater extent. To the west of the Tasman geosyncline, coal of bituminous rank generally occurs at considerable depths (usually in excess of 1 km and in some areas only at depths of over 2 kms), and in most areas coals at shallow depth are of sub-bituminous or brown coal rank. The controls of the distribution of coal type and rank have considerable economic significance and the unusual characteristics of Australian coals, especially with respect to coal type, make the direct application of overseas technology to Australian coals inappropriate.

Jan 1, 1975

By D MacKenzie

The Rise & Shine Shear Zone is a shallow-dipping Cretaceous late metamorphic shear zone formed in a compressional environment. The Shotover mineralised system is dominated by normal faults with well-defined vein systems that cut across Miocene schist folds and faults related to the inception of the Alpine Fault. Despite the geological differences between these mineralisation systems, they share many common features of hydrothermal alteration that have resulted in disseminated gold in altered sheared schist. The most distinctive feature of both systems is the abundant ankeritic carbonate that has formed from decomposition of metamorphic chlorite. Excess iron from this alteration reaction combined with hydrothermal sulphur to form sulphides that host the disseminated gold. The chlorite decomposition reaction was reversed in the latter stages of both mineralisation systems, and this was accompanied by further gold emplacement in the Rise & Shine system.   Both alteration systems involved initial decomposition of metamorphic albite, followed by deposition of albite as a vein mineral in the latter stages. The fluid flow that yielded the disseminated gold was controlled by microshears that pervade host schists, in strong contrast to many Otago Schist vein systems where host rock alteration is absent. The ankeritic alteration in the Shotover and Rise & Shine mineralised systems has increased the volume of mineralised rock, and may have made suitable targets for large-tonnage, low grade gold deposits.

Jan 1, 2007

The Australian Mineral Industry's growth in the last two decades is directly related to the skill and experience of its consultants in mining, metallurgy, geology, finance, management, marketing, and engineering. The role of mining consultants needs to be re-examined, so that the quality of the service they deliver will continue to be adequate for the 1990's. One means of this evaluation is by examining Case Studies in the strategies and difficulties of developing contract and entrepreneurial research.

Jan 1, 1986

Early theories of coal formation are outlined, with special emphasis on the arguments for allochthony and autochthony. Various aspects of the nature, growth, and decay of the characteristic vegetation of the brown coal peat moors, their conversion into coal, the origin of banding, and the influence of tectonics are discussed.A description of the banding in Victorian brown coals is followed by a discussion of their vitrain, fusain, and natural carbonized coal; and concludes with the nature of the coal resin and the possibilities of its extraction.The nature and derivation of inorganic matter in brown coal, based on Lessing's classification, is described. Assimilation of mineral substances in specific plants with variations due to environmental factorsare illustrated by analyses of present day trees. Consideration is then given to possible sources of salt, marcasite, and quartz in brown coal.It is shown that part of the inherent and extraneous ash may have been removed during and after coal formation. The nature and abundance of the organically combined substances in brown coal emphasizes the anomalies that may arise from estimating the total inorganic matter from ash contents.After classifying deposits on external heating surfaces of boilers, theoretical and practical aspects of slag formation, alkali matrix deposits, and the effect of sulphur and chlorine are considered.Analyses of deposits in boilers burning Victorian brown coal are tabulated.Slagging at the Yallourn power station from sand in the Yallourn open cut, and difficulties with Yallourn North Extension coal at the Maryvale paper mills are described.Tests carried out on Morwell and Yallourn coals showed that with the former, impacted deposits formed on boiler heating surfaces, and left a high percentage of chlorides on probes. Morwell briquettescompared with Yallourn briquettes also reduced the running time of a semi-industrial boiler through deposits with sodium sulphate as...

Jan 1, 1962

By I Gipps

The mining industry has come through a period of major change in community expectations regarding safety and environmental impact and these changes can be expected to continue in the future. These changes are ultimately reflected in Government regulations and industry safety standards and form the basis of the ælicense to operateÆ. Equally, advances in technology have made possible new equipment and processes either available now, or close to completion, that will allow mines to meet these more stringent expectations if properly introduced. Changes in technology provide opportunities for mine management to introduce new systems that will remove people from hazardous areas and lead to improvements in the ætriple bottom lineÆ. In a longer time frame of five to ten years, novel and advanced technologies that are currently being developed will deliver new mining methods and conversion of presently uneconomic resources to ore. This is consistent with the time frame required to develop a new mine from discovery. Strategic decisions can be taken now by mine designers to enable the introduction of these major technology changes. Examples of both practical and strategic opportunities are drawn from the integration of rock cutting/blasting, automation, electronic communications and new mining methods. This paper discusses emerging industry trends, changes to legislative framework and some practical choices for existing and imminent technology.

Jan 1, 2003

By R Knight

"In project evaluation there are two matters of keen interest to non-executive directors: the process by which an investment recommendation is reached, as well as the investment itself, as presented. It is sometimes mistakenly believed that Boards of directors are interested only in the result. That is not so. The process by which project evaluations are derived and socialised with the Board is as important as the result, sometimes more so.Setting aside the gloomy predictions of the doomsayers and looking through short-term volatility in supply and demand, the overall availability of mineral resources more often than not exceeds demand. There are in reality more development projects in prospect at any one time than are needed to meet the market. Only the fittest will prosper, although some others may survive.Optimism springs eternal in the mining industry and every project promoter, executive or entrepreneur has a convincing project development case. Some will create value for shareholders, but the historical evidence suggests that many will fail to meet the expectations set in their evaluation.Boards of directors make the final decision to invest, or not, in a new mine. Knowledge is power, and on that basis the balance of power favours management. Management has the facts (or in some cases, what passes for fact) and the passion to invest. The non-executives have the power of approval – yes or no – but before making a decision directors must demonstrate due diligence, the essential precursor to project approval.Management has a vital part to play in facilitating that due diligence process and in encouraging the independent thought processes of the Board. A closed approach by management fosters a negative, risk-averse attitude on the part of the Board. One that encourages an understanding of the rigour of the project evaluation process and the robustness of the result will allow directors to understand better the implications of their decision.CITATION:Knight, R, 2016. Project evaluation – a non-executive director’s perspective, in Proceedings Project Evaluation 2016, pp 11–19 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By C Hamilton

Stawell Gold Mines (SGM) is an underground mining operation located in Victoria, Australia. The mining method employed is long hole retreat stoping, utilising up and downholes and artificial concrete pillars. Stawell is currently mining the Golden Gift and Magdala orebodies.Access to the Magdala and Golden Gift deposits is via 6.0 m wide by 5.5 m high declines developed at a gradient of one in eight to one in seven from the surface to a depth of 1500 m, with a planned depth of 1650 m. From the declines, cross cutting drives are developed to intersect the orebodies. Orebodies in the Gift system are discrete lodes which are generally mined from a bottom up centre retreat to minimise geotechnical stresses.Ore development fronts are currently located between 1000 m and 1500 m below surface, with all ore being hauled to the surface using a fleet of 60 tonne underground trucks. With the use of conventional pyrotechnic long period (LP) delays, broken rock of combined ore and waste is thrown 10 m from the face and the materials hauled to the surface. The majority of the mullock from development is consumed in the underground as backfill.With the use of Orica Mining Services eDev™ Electronic Blasting System for Tunnelling, the waste is thrown up to 40 m from the face, while majority of the ore is left 5 - 10 m from the face, effectively segregating ore and waste. This enables significant recovery of gold values with minimal loss and significantly reduced dilution. By using this technique in ore drives with a 30:70 waste to ore ratio, SGM is able to haul 24 000 tonnes less mullock to the surface annually. Resue mining is applied to narrow vein headings and gives a 40 per cent grade increase at the faces as well as increasing the economic footprint of development. This will also contribute to an improved grade profile for the year from 3.98 - 4.16 g/t Au and allow extra capacity for ore haulage from stoping and for milling.This paper describes the application and the successful blast outcomes achieved using the eDev™ Electronic Blasting Systems for resue mining at SGM. Results to date, since commencement in March 2010, have been achieving significant benefits in terms of ore grade as confirmed by geologists grab sample grades. Face advance have also shown improvement with better breakage of perimeter holes giving improved face profile. These benefits are delivering increased productivity and safety performance when compared to other resue firing techniques.

Mar 21, 2011

By L Klemettinen, A Jokilaakso, D Attah-Kyei, P Taskinen, M Tiljander, D Sukhomlinov, D Lindberg

In this study, the use of carbon neutral biochars as reducing agents in the pyrometallurgical treatment of nickel slag was investigated at 1400°C in order to recover valuable elements such as copper and nickel from the slag. A large amount of slag is generated during the nickel matte smelting. Nickel slag contains valuable elements such as copper, nickel and cobalt, which can be recovered. Disposal of this slag results in loss of resources and may cause pollution of the environment. It is important to retrieve these metals for environmental and economic reasons. In this study, the slag was reacted with non-fossil reducing agents (biochar) which were produced from hydrolysis lignin and black pellet biomass pyrolyzed at 600 and 1200°C and with metallurgical coke for comparison. The reduction experiments were done at 1400°C for 15, 30 and 60 mins under inert gas atmosphere. The samples were quickly quenched and analysed with Electron Probe X-ray Microanalysis (EPMA). The results showed that the use of biochar resulted in faster reaction kinetics in the reduction process compared to coke. The fast reaction kinetics is attributed to the relatively high content of volatiles in this biochar, leading to gas formation and thus mixing of the sample material. Moreover, thermodynamic modelling was also performed using FactSage™ to simulate equilibria with different amounts of biochar. The metal to slag distribution coefficient calculated from the results of thermodynamic modelling were consistent with experimental results. In addition, thermodynamic calculations confirmed that nickel is reduced rapidly and it deports to the metal alloy phase. As the reduction progresses or extra reductant is available for reactions, more iron is deported to the metal phase. The calculations also revealed that Zn vaporises into the gas phase.

Jun 19, 2024

By M E. Watson

Minimising dilution and ore loss is an important part of ensuring profitability of a gold mining operation. White Foil open pit gold deposit is a low-grade deposit and therefore managing ore quality is a high priority. Ground movement through blasting can displace ore and waste boundaries up to 10 m from their in situ location and therefore requires stringent ore movement monitoring and adjustment. There are currently only two options for monitoring blast movement – utilising visual targets (commonly lengths of polypipe) but this has widely been replaced by electronic blast movement monitors (or BMM). Regardless of the technology used, the basic principle is to compare the pre- and post-blast locations of the targets to determine the movement of the rock mass during blasting, which is then used to determine the final location of ore and waste boundaries.The Blast Movement Technologies (BMT) BMM system has been used at White Foil since June 2014. The system has been effective and reliable during that time; however, the annual cost of using the BMM system is greater than other monitoring alternatives. As such, the open pit geology team conducted a study comparing the BMM system against the conventional polypipe technique. The objective was to quantify the profit and loss that would occur based on the ore block transformations from both methods. Eight blasts were selected where polypipes were installed in additional holes adjacent to the BMM monitoring holes. The resulting movement vectors from the respective methods were used to create post-blast ore blocks by transforming the in situ ore blocks. While polypipe is a cheaper alternative, the BMM system tracks ore and waste boundaries more effectively resulting in better quality control, enhanced ability to minimise dilution and ore loss thus maximising profit. For these eight blasts, it is calculated that the BMM system resulted in A$664 978 extra profit through a reduction of ore loss. The total cost of a yearly BMM package was recovered in the first two blasts of this study. The primary reason for the difference is that polypipe had a poor recovery rate of 32 per cent compared with 92 per cent for BMM at White Foil. Therefore, the data used to transform the ore blocks was less representative, resulting in inaccurate post-blast ore block boundaries when using polypipe.CITATION:Watson, M E, 2017. Blast movement monitors or polypipe? A study into cost-effective blast movement monitoring at White Foil gold mine, Western Australia, in Proceedings Tenth International Mining Geology Conference 2017, pp 433–440 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By S Freij, P W, R Gunawan, D Zhang, B Feng

The Mt Whaleback iron ore mine is located adjacent to Newman, approximately 1200 km north of Perth, in the Pilbara District of Western Australia. Approximately 15 per cent of the waste materials are in the zones with high concentrations of sulfide and carbonaceous minerals and are referred to as æreactive shaleÆ. The reactive shale has the potential to undergo self-heating and can react with the ammonium nitrate (AN) based explosives used in mining operations, resulting in spontaneous combustion and spontaneous explosion. The sulfide-rich shales also have the potential to produce acid rock drainage (ARD). In the present study, over 200 shale samples have been collected from different locations in the Mt Whaleback iron ore mine, including blasthole drill cuttings, fresh mine faces and waste dumps. These samples have been systematically characterised for their geochemical properties. Based on the characterisation results, a pH test was developed as a cost-effective, fast and efficient tool for the assessment of reactive ground in the mining industry. This paper summarises the results of the sample characterisations and discusses the key findings arising from the interpretation of results. These results have significant implications in the safe storage of the reactive shales and the prevention of spontaneous explosion, spontaneous combustion and ARD.

Jan 1, 2005

By F Wu, H Wang, W Chen

A pressurisation method with multiparallel fans has been adopted at HongLiuLin Coalmine to control the significant external air leakage through the goaf area of coalface 15207. Potential damaging effects of large external air leakage on a coalmine’s ventilation system are analysed according to the current air leakage status caused by the exploitation of shallow-covered coal seams. The use of pressure balanced ventilation to prevent external air leakage through goaf areas is introduced. The calculation of ventilation network of HongLiuLin Coalmine shows that the air resistance of an external air leakage branch through a goaf area and the air pressure drops from the intake slope to the working face can be adopted to determine the values of pressure to be increased by regulating fans and airflow controlling parameters of regulators. By investigating airflow requirements of the pressure-balanced area as well as the performances of the auxiliary fans currently used in the coalmine, the number of pressurisation fans needed is fixed. The expected result is achieved after the pressurisation method has been carried out, which can be helpful for other coalmines to handle similar problems.CITATION:Wu, F, Chen, W and Wang, H, 2015. Multiparallel fan method to prevent significant external air leakages through a goaf area of a shallow covered coalmine, in Proceedings The Australian Mine Ventilation Conference, pp 267–270 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

While sampling techniques used by the mineral industry continue to improve, sampling is still an area which is often neglected. It is often left to personnel who do not fully appreciate the significance and importance of sampling. Yet sampling and sample processing are of vital importance. There is little point in making major capital investments in the latest analytical equipment and spending considerable time obtaining the best analytical precision, if the sample provided for analysis is seriously biased in the first place.

Jan 1, 1976

By M Zoorabadi, B Hebblewhite, S Saydam, W Timms

Based on the cubic law, the hydraulic aperture of rock discontinuities has the most significant effect on the hydraulic conductivity of jointed rocks. The hydraulic aperture of rock discontinuities is a stress-dependant parameter and reduces with increasing applied stress. Furthermore, the rock stress increases with increasing depth. Therefore, hydraulic aperture is a depth-dependant parameter. In this paper, new empirical equations are introduced to calculate the hydraulic aperture of rock discontinuities at different depths. These equations were developed on the basis of back analysis of compiled packer tests from different actual cases. They provide the capability to calculate range of variation and average hydraulic aperture when the orientation of discontinuity and field stress tensor are given. Furthermore, it is possible to calculate the hydraulic aperture of rock discontinuities when its value is given for another depth. A hydraulic aperture of 7.7?µm was calculated by this method, comparing well with a reported site value of 8.3?µm for rock discontinuities at the Stripa mine project at a depth of 385?m. These new equations can be used by analytical or numerical methods to estimate the hydraulic conductivity of jointed rocks.CITATION:Zoorabadi, M, Saydam, S, Timms, W and Hebblewhite, B, 2014. New empirical equations to estimate the hydraulic aperture of rock discontinuities at different depths, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 375–380 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Davies H, Pigram C, Sunata W, Falvey D, Loxton C, Giddings J, Rogerson R

PALAEOMAGNETIC CONSTRAINTS ON TERRANE TECTONICS IN NEW GUINEA Chris Klootwijkl), John Giddingsl), Wahyu Sunata2), Chris Pigraml), Charles Loxton3), Hugh Daviesl), Rick Rogerson3) and David Falveyl) 1) Bureau of Mineral Resources, Canberra, Australia 2) Geological Research and Development Centre, Bandung, Indonesia 3) Geological Survey of Papua New Guinea, Port Moresby, Papua New Guinea

Jan 1, 1987

By S T. L Harrison, J-P Franzidis, M Becker, N Dyantyi, J L. Broadhurst

Gold mining is a major contributor to the South African economy, but is associated with several environmental issues such as acid rock drainage (ARD). ARD is due to the oxidation of sulfides in gold tailings and is characterised by low pH, high sulfate content and elevated concentrations of heavy metals that contaminates scarce water resources and subsequently limits the use of such waters without treatment. Treatment strategies can only be implemented if the acid-generating potential of mine wastes is effectively predicted using common static and kinetic acid prediction tests. The choice of test performed is usually a trade-off between the number of samples, speed of the test, cost of the analysis and level of information obtained. Often the results of these various tests are not consistent with one another. This study uses mineralogy to analyse biokinetic test results of a Witwatersrand gold sample in order to improve the understanding of behaviour of mine wastes under different ARD prediction test conditions.All ARD prediction testing methods investigated in this study showed that the gold sample is considered to be potentially acid forming with net acid generation (NAG) pH of 2.5 and net acid producing potential (NAPP) of 36 kg H2SO4/t. Results of biokinetic test showed that ANC was consumed within four days confirming acid producing potential of the sample with low neutralising potential as observed from acid base accounting (ABA) (4.7 kg H2SO4/t) and mineralogy (4.9 kg H2SO4/t). Results generated in this study demonstrated importance of mineralogy in both understanding the controlling reaction mechanisms playing key role in ARD formation and its capability as a prediction technique. Future work will focus on the application of mineralogy in interpreting the behaviour of mine waste under different static test conditions with a view to assessing their applicability and reliability in estimating potential acid generating characteristics of gold tailings.CITATION:Dyantyi, N, Becker, M, Broadhurst, J L, Harrison, S T L and Franzidis, J-P, 2013. Use of mineralogy to interpret laboratory-scale acid rock drainage prediction tests - a gold case study, in Proceedings World Gold 2013, pp 519-526 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By A G. Dempster, N Barnett, J Oh, S Saydam

NASA’s Artemis III mission is expected to return astronauts to the surface to explore and sample the lunar volatiles by 2026. These volatiles are anticipated to provide scientific insights as to how the Moon was created and economic value to off-Earth operations. These same volatiles can pose health implications to astronauts and Earth based personnel handling lunar regolith samples. Using Australian, USA and NASA airborne contaminant exposure limits and the Lunar CRater Observation and Sensing Satellite (LCROSS) measurements of lunar volatiles in the Cabeus crater ejecta, the minimum mass of lunar regolith that can be safely handled by humans on Earth and in spacecraft can be calculated. This analysis determined a 0.15 grams pure sample of Cabeus crater regolith within a cubic metre of air has enough volatiles to exceed safe working conditions, and 14.9 grams of pure Cabeus crater regolith per cubic metre of air can impact human life. The intent of this analysis is to assist safe handling and exposure calculations for the safe handling procedures of lunar regolith containing volatiles.

Sep 1, 2024

By K Guilfoyle

AngloGold Ashanti Australia Ltd operates an underground mine below a large open pit at the Sunrise Dam Gold Mine near Laverton in Western Australia. Operations are based on an extensive mineralised zone which has very complex geometry, has a high ‘nugget effect’, and is difficult to interpret and model. Initial underground ore was produced from relatively narrow orebodies dipping from 15º - 70º. Open stopes aimed to selectively extract high-grade ore, using methods including jumbo stripping and longhole drilling and blasting. The complex geology makes it difficult to accurately locate development and stopes in the positions required for profitable production. In narrow stopes, rock mass damage and overbreak dilute ore grades and increase the cost per ounce of gold poured. In flat orebodies, several different techniques have been used to recover blasted ore but overall productivity is low. Thus selective mining can also be slow, costly and recovers only a portion of the available mineral resources. Large longhole open stopes with cemented paste backfill are used to extract multiple zones of mineralisation from the Cosmo and GQ orebodies. Bulk emulsion explosives and electronic detonators are used in all large stope blasts to reduce the risk of misfires and to accurately control blasthole initiation sequences and delay timing. Larger stopes improve productivity and significantly reduce direct mining costs, enabling the use of lower economic cut-off grades which increase the overall recovery of mineral resources. This paper reviews the evolution of open stoping at Sunrise Dam, the various mining methods and drilling and blasting practices used, the results achieved, and the lessons learned.

Nov 8, 2011