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By G K. Robinson, M D. Sinnott

Three-dimensional granular flow models have been run to simulate three types of sample cutters: a cross-stream cutter, a vezin, and a cross-belt cutter. This type of modelling involves solving the equations of motion for large numbers of individual particles as they travel along a conveyor belt and interact with a sample cutter. It allows flows of bulk materials to be visualised and understood. Here we have used spherical particles. These results illustrate some advantages that modelling has compared to physical bias testing: By taking reference samples which are very close to the actual samples, the estimation of bias can be achieve quite precisely with very few runs. (Many Standards about bias testing recommend a minimum of 20 runs, but we have found that five runs generally provide adequate precision.) Potential bias can be divided into two components: the particles which are missed but should have been sampled and the particles which are extra but which should not have been sampled. This more detailed information can provide useful insight. Exactly the same material can be sampled using different sample cutters, thereby avoiding a source of variation that complicates physical testing. Much more detailed visualisation is possible, allowing better understanding of the bulk material flow in various circumstances.

Jan 1, 2005

By Bourke J. H, Ashcroft T. B

Many changes have occurred in the world market for manganese over the last five years. Among these, the emergence of divided steel processes for the hot metal refining of pig iron is affecting the use of both ferruginous manganese ore and ferro manganese, at this stage particularly in the Japanese steel industry. Subsequent demand for higher quality manganese materials is promoting the use of thermally beneficiated products such as sinter. In addition, many processes are being developed for the direct smelting of fine manganese ores, of which plasma technology is the most advanced. Cost pressures and product quality requirements are encouraging pre- viously self sufficient countries such as The People's Republic of China and the USSR to import high grade manganese ores to supplement indigenous lower quality supplies. At the same time, Brazil has been provided with the impetus to convert its substantial reserves of ore to value added products.

Jan 1, 1988

In open cut gold mining at Mt Magnet and Reedy, grade control sampling is done with inclined RC drilling using one metre samples. In the small open cuts at Rothsay blasthole sampling was successfully used. Underground sampling for gold and copper grades at Rothsay is done using chip sampling. At the Youanmi open pits both Ditchwitch Earthsawing and RC drilling are used.All assay data are interpreted on sections and plans using a customised SURPAC system. Reconciliations of the grade control predictions of tonnes and grade against initial ore reserves, mining production and milling results are carried out monthly.

Jan 1, 1990

By Hunter TC

Metals Refining Operations Pty. Ltd. (NMO), PNG's only gold and silver refinery is operated by Golden West Refining Corporation Ltd (GWR), a member of the Rothschilds group and has a strong PNG ownership link through statutory shareholders. Located in Waigani, MRO has been successful in substantially increasing production through toll refining for Porgera, Misima, Tolukuma, Wapolu and, more recently, at Lihir as well as treatment of alluvial gold from smaller operations. This increased throughput has resulted in the need to constantly upgrade equipment, techniques and practices, particularly to continue quality improvements and meet market demands. The evolution of these changes are documented and discussed and the probable future development plans are detailed.

Jan 1, 1997

Mt. Whaleback is in the Pilbara region of Western Australia approximately 1200 kilometers north of Perth, the State capital. In this deposit the Mt. Newman Joint Venturers are mining ore reserves totalling 1500 million tonnes of high grade hematite averaging 64.0% Fe. In addition to Mt. Whaleback, 38 ore bodies have so far been identified outside Mt. Whaleback on the Company's remaining 75,000 hectares of lease area. These ore bodies contain major tonnages of iron ore. Extraction at present is planned at a rate of 37 million tonnes per annum at an ore-to-waste ratio of approximately 1 to 1.4. The ore is railed north to Port Hedland on the Indian Ocean where the different products are screened, crushed and blended prior to shipping. The purpose of this paper is to acquaint the reader with the facilities installed in the Mt. Newman operation to form a background to the sampling techniques employed, describe the precisions which were achieved in experiments conducted February through June, 1976 and also to assess the degree of blending which takes place during the various processes and to put a quantitative measure to the degree of blending. There have been many excellent papers written on the more theoretical aspects

Jan 1, 1976

By Ennis P. C

The Mt Keith ultramafic intrusive extends for about 200 kilometres from Agnew in the south to Wiluna in the north. It forms the host for a number of nickel sulphide orebodies including Mt Keith and Honeymoon Well. Long fibre minerals are associated with the orebodies. The presence of these minerals impacts on the issue of tailings disposal from several standpoints, particularly the slurry beaching properties and dust generation from dry beaches. Central thickened discharge (CTD) is an innovative method of tailings disposal that involves stacking tailings in a low conical hill instead of storing them in cells. In appropriate circumstances this leads to savings in capital costs and operating expenditure. The method was introduced to Australia in 1981, and is currently employed at four operating mines, Elura and Peak Gold, both at Cobar in NSW, McArthur River in the Northern Territory, and Union Reefs near Pine Creek, also in the Northern Territory. It is the proposed method for Century Zinc and Ernest Henry, both in Queensland. The paper describes laboratory test work and design parameters for the application of the method to tailings disposal at Honeymoon Well and compares them with comparable data for other CTD systems. Of particular relevance for design purposes are beach slope, density, and water recovery. Wind tunnel tests were conducted on the Honeymoon Well tailings samples to investigate dust generation from the dry beach surface and it was concluded that dust generation from an undisturbed beach would not occur because of crusting.

Jan 1, 1996

By Woodcock JT

This paper deals with some innovations and current proposals for the treatment of gold ores and considers the possibilities of incorporating new developments in new or revised ore treatment flowsheets. The main topics considered are I. typical practice in relation to the size of gold particles, 2. concentration of coarse gold, 3. leaching reagents, 4. in situ leaching, 5. heap leaching, 6. carbon-in-pulp adsorption, and 7. treatment of complex ores (gold in pyrite, gold tellurides, and carbon-containing ores).

Jan 1, 1982

Establishing the link between the solid, cold rock of dikes, sills, plutons, and lavas and hot, active magma chambers is the quest of igneous petrology. Differentiation of Earth, the diversity of the igneous rocks, and the spectacle of volcanism are ample evidence that magmatic processes are fundamental to our understanding of planet formation and evolution. Single gabbroic plutons, on the other hand, often show intricate and abundant evidence of the effects of crystal growth and sorting. It has not proven simple, however, to establish the basic principles of magmatic behavior leading to this crucial evidence. Because of their abundance, exposure, simple geometry, large range in size, and often straight-forward petrology, sills are excellent examples of the magma chambers. Physical and chemical processes operating in sills can be recognized that also routinely operate in many other bodies. Understanding the dynamics of sill solidification is essential to understanding the genetic links between lavas and plutons.

Jan 1, 1990

The results of the washing of coal are often presented by using Partition Curves. By analogy, it is possible to express the results of screening by using similar partition curves. As in the coal washing processes, this method determines the accuracy of screening and is also suitable for different separations depending on the difference in size distribu- tion. This method compares the effectiveness of two screening operations and forecasts the performances.

Jan 1, 1984

By Grouhel P

Blasting performance is directly related to the characteristics and efficiency of the explosives used. The selection of the correct explosive for particular blast conditions and objectives depends on the ability to characterise the performance of individual explosive products. Techniques have been developed by the JKMRC to measure explosive performance and assess the impact of explosive performance on blast results. Studies conducted at a number of mine sites have shown that different types of explosives perform quite differently and that the performance of any particular explosive can vary significantly. The principal causes of these variations have been identified and detailed blast monitoring techniques, including the analysis of muckpile fragmentation and shape, have been used to quantify the effects of explosive performance on blast Results.

Jan 1, 1990

I am honoured and very pleased to have been given the opportunity this evening to say a few words of thanks not only on behalf of all the guests but especially for the delegates and accompanying persons attending the 13th Congress of the Council of Mining and Metallurgical Institutions. Firstly, I would like to congratulate Sir Hamilton Whyte,KCMG for his most interesting address. In his far ranging talk, when he showed knowledge of widely diverse subjects, I had a brief fear that he was going to be talking about the details of support methods in deep level mines, or how to avoid flotation problems in multi-metal mines. Although he did not go that far, he touched on subjects which have arisen this week - long term planning and secure supply of minerals at acceptable prices. The dire predictions of the Club of Rome have been debunked with a far more elastic supply of minerals having been proved. Combined with the importance of a falling birthrate in some parts of the world, this will lead to many changes in the future, when hopefully governments will take the long term view rather than look at the next budget or the next election. Maybe some of them are not too lazy to do this for all of us. However as a fellow Ukranian, I feel that he might have been called something different if he had been in Australia. Sir Hamilton, thank you for your talk. Once upon a time - and this is not a fairy story - there was a cobbler who had two sons; one very bright who became a professor of mathematics; the other, dim, who became a millionaire shoemaker. Asked for the secret of his success, the millionaire attributed it to a vital piece of economics which his father had imparted, "Be content with small margins on a large turnover." "So", said the millionaire, "I make my shoes for $2 a pair and sell them for $5. I am very happy with the three per cent profit."

Jan 1, 1986

Jan 1, 2004

By Jaczkowski B. M, Cox T. J, Domfeh I. A, Stalker I

Mining and treatment of gold ore in the Ashanti region at Obuasi, Ghana has been continuous for more than 100 years. Earlier production from this world class deposit can be traced far into the history of West Africa's gold trade. As part of a general development and expansion program, Ashanti Goldfields Corporation (Ghana) recently undertook a program to heap leach oxidized near surface ore. Kappes, Cassiday & Associates was given a major role in the design, equipment supply, installation and start-up management of the 3000 tonne/day heap leach. Unusual conditions included a high annual rainfall and an ore which could be characterized as a soft, decomposed, water saturated schist. Production began in March 1990. Startup problems and their solutions are discussed.

Jan 1, 1991

By A G. Tomkins

"Approximately 32 per cent of the worldÆs total gold production has come from greenstone belts (Frimmel, 2008). In these regions numerous small to large, quartz vein-associated gold deposits are hosted in metamorphic rocks ranging from lower greenschist to granulite facies. Historical exploration has focused its efforts on rocks of greenschist to lower amphibolite facies because these seem to contain the most deposits. Consequently, these regions are now reaching mature brownfield status, particularly in developed nations, and finding new deposits is becoming progressively more difficult. In comparison, regions of similar tectonic setting, but instead containing high-grade metamorphic rocks of mid-amphibolite to granulite facies, have received little attention because the first explorers found fewer deposits there.However, these regions certainly do contain some very significant gold deposits such as Hemlo in Canada (~684 t Au), Renco in Zimbabwe (~31 t Au mined since 1980), the very profitable Challenger deposit in South Australia (~36 t Au; recovered + reserve + resource), and the most recently discovered Tropicana deposit in Western Australia (~182 t Au; reserve + resource). High-grade metamorphic terrains therefore offer explorationists an excellent opportunity to move onto relatively green fields within developed nations, which carry less risk associated with development. However, explorationists have comparatively little knowledge of the geological controls on gold distribution in high-grade terranes because: industry experience lies in traditional lode-style gold deposits these gold deposits are geologically more complex there has simply been minimal research conducted on these deposits as a holistic group.Furthermore, research conducted in the last five years has shown us that the previous widely accepted model for gold genesis in these terranes, the crustal continuum model, is incorrect. Here, I discuss features from several gold deposits hosted in high-grade metamorphic rocks and use these to define two categories for explorationists to consider: deposits that formed prior to peak metamorphism (metamorphosed gold deposits) deposits that formed well after peak metamorphism (post-metamorphic gold deposits). There are none that have been convincingly shown to have formed during peak metamorphism.CITATION:Tomkins, A G, 2013. Gold deposits in highly metamorphosed terranes, in Proceedings World Gold 2013, pp 23-26 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 26, 2013

By K P. Tully

In August 1996 a Microseismic Monitoring System developed by ISS International Limited was installed at the Pasminco Broken Hill Mine -Southern Cross area. The project aims were to:Assist in daily safety management in a mine environment which exhibits one of the highest occurrences of microseismic activity recorded in the Australian mining industry. Be used as a proactive tool in design of future development and stoping. The project to-date has been an unqualified success in achieving both goals. Consequently the system is being expanded from 6 to 14 monitoring sites.

Jan 1, 1998

By R Cunningham, P Duniam

Late in 2005 it became apparent that cave propagation at the Northparkes Mine was not progressing as planned. By mid-2006 sufficient Reserves were identified to warrant an extensive drill and blast program to assist in cave propagation. This program began late in 2006 and concluded early 2007. A significant challenge faced was the drilling and blasting of holes between 75 - 240 m in length in the South Wedge in Lift 2 at Northparkes Mines E26 orebody. The project set new benchmarks in production drilling and charging in underground metalliferous mining. This paper discusses the drill and blast designs, the challenges and the operational issues encountered with this project. Also highlighted are ways in which these were overcome.

Jan 1, 2007

By Ho SE, Neil Phillips G, Houstoun SM

There are numerous individual gold deposits in the Archaean greenstone belts of Western Australia, but only 26 have productions and/or quoted reserves in excess of 10 tonnes Au. Most gold production has come from mineralization in shear zones, quartz veins or stockworks in volcanic or intrusive host rocks, particularly tholeiitic basalts or dolerites metamorphosed at sub-amphibolite facies (e.g. Kalgoorlie). Significant prod- uction has also come from BIF-hosted deposits (e.g. Hill 50), and large reserves are quoted for mafic hosts at high metamorphic grade (e.g. Big Bell). Most deposits have marked structural control, great depth extension, and are characterized by zoned alteration haloes of pyritization (with Au), K-metasomatism and carbonation. On the regional scale, most larger volcanic- or intrusive-hosted deposits occur in younger (ca 2.8 b.y.) rift-phase green- stones (Norseman-Wiluna Belt). These belts also have a high prospectivity (36 kg Au/km2 of greenstone belt). Younger (ca 3.0 b.y.) and older (ca 3.5 b.y.) platform-phase green stones of the Murchison and Sodthern Cross Provinces and the east Pilbara, respectively, are progressively less prospective (14 kg Au/km2 and 0.8 kg Au/km2, respectively) and also have progressively smaller deposits. The important regional- and local-scale characteristics of most gold deposits can be explained in terms of a metamorphic- replacement model. In this model, metamorphic H2O-CO2 fluids, focussed by faults and shear zones, infiltrated host rocks and deposit gold at 350 + 50¦C and 1-2 kb, largely in response to fluid-wallrock interaction. In many large deposits, gold precipitation was synchronous with sulphidation of Fe-rich host rocks, but the diversity and abundance of smaller deposits reflects the variety of reactions precipitating gold from ubiquitous, auriferous metamorphic fluids. Regional variations in abundance and size of deposits relate to factors such as tectonic setting, alteration styles and possibly source rocks.

Jan 1, 1986

By F Carrick, W A. Ellis, D R. Mulligan, S I. FitzGibbon

"One of the major environmental impacts of mining is the destruction of habitat. The koala (Phascolarctos cinereus) is an iconic Australian marsupial that has been severely affected by land clearing and its decline is continuing. This has placed pressure upon mining companies and government agencies to ensure koalas are managed throughout the life-of-mines - from land clearing through to rehabilitation of post-mining landscapes. This paper reports on the æKoala VentureÆ research partnership between The University of Queensland and Rio Tinto. As part of the Koala Venture program we examined koala use of two types of restored environments: rehabilitated mined land (20 sites) natural regrowth forests (six sites), at Blair Athol Coal Mine in Central Queensland, Australia. Searches for koala scats revealed evidence of koalas in ten per cent of rehabilitated sites (2/20) and 33 per cent of natural regrowth sites (2/6). Two factors were identified as being of greatest importance in facilitating koala recolonisation of restored habitats. Firstly, all recolonised sites were located close to native forest occupied by koalas (mean 135 m ¦ 52). Proximity to source animals is considered crucial to recolonisation of suitably restored habitats. Secondly, three of the four recolonised sites were dominated by koala food trees, most of which were large enough to be utilised by koalas. Availability of suitably abundant food resources is, therefore, also considered crucial. The requirement for these two factors, in combination, is highlighted by the absence of koalas at several sites that contained abundant food trees, but that were distal to areas with source animals, and vice-versa.Our research demonstrates the enormous potential for restoration of wildlife habitat on post-mining lands, even for species with specific requirements such as the koala. Consideration of the ecological requirements of wildlife during rehabilitation planning is critical to enhancing the likelihood of recolonisation.CITATION:FitzGibbon, S I, Ellis, W A, Mulligan, D R and Carrick, F, 2012. Rehabilitating post-mining landscapes for wildlife - A case study from the Koala Venture research program in Central Queensland, in Proceedings Life-of-Mine 2012, pp 319-324 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 10, 2012

CSA mine, which is a deep level copper operation, located 12 km north of Cobar, NSW, currently uses a top down stoping method, utilising cemented hydraulic backfill (CHF) to fill and stabilise the stoping void thus assisting the extraction sequence. The stope sequence then requires development back through the CHF stope so that the necessary infrastructure for the subsequent stoping, such as raise bore pads can be sited. The primary and secondary support installed in the CHF consisted of 100 mm thick fibrecrete from floor to floor with 7 + 2.4 m long resin support tendons installed at 1.5 m ring spacing. This support system relied on the resin achieving a quality bond with the CHF, and also the fibrecrete developing early structural strength due to the use of an accelerator. In addition to the delays in the excavation turn around time, it was felt that a superior support system could be designed. Such a system was designed; risk assessed, tested underground, and trialled in selective CHF digouts, and eventually signed off as the chosen support method in CHF digouts. This paper discusses the change from a passive support system used in CHF digouts to an active support system using Swellex bolts and weld mesh, which has provided an active support system, that is superior, faster to install, reduced the excavation turn around time and is overall a cheaper support system.

Nov 25, 2010

By N Haque

Base metal ores contain low levels of toxic/hazardous elements such as arsenic, antimony, bismuth, cadmium, lead and mercury. Given the large tonnage of base metal ores mined and processed each year globally, the accumulated mass of minor elements introduced into the biosphere is large and could be expected to have a significant environmental impact. Life cycle analysis (LCA) is a methodology that has been developed to assess the environmental impacts of material supply chains over their entire life cycle. Assessing the toxicity impacts of metallic wastes and incorporating these impacts into LCA methodology is not a simple task given the complexity of the issue. However, research and methodology development is in progress internationally to address this. Despite limitations concerning the lack of a coherent framework for characterising the toxicity impacts of metals, including issues such as bioavailability, a study was carried out to give first estimates of the relative toxicity impacts of various waste streams from metal production processes. The wastes considered were: red mud; sulfide tailings (copper, nickel, lead/zinc); lead/zinc slags; synthetic rutile residue; iron oxide residue; and copper slags and anode slimes. These toxicity estimates can be considered the æworst caseÆ scenario for these wastes, where all the metals present are bioavailable. Combining estimates of the amounts of the various waste streams produced in Australia each year with the toxicity results showed that despite their relatively low human toxicity impact per unit mass compared to some other waste streams, red mud and the various sulphide tailings had the highest annual human toxicity load on the environment, along with copper smelting slag and dust. Data from the pH dependent leaching test reported in the literature were assumed to represent first approximations of metal bioavailability and used to compare the two approaches to estimating the toxicity impacts of red mud.

Jan 1, 2009