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By Lewis PC, Carr GR, Dean JA, Glen RA

The Lachlan Fold Belt (LFB) is a complex orogenic belt which developed in Early to Mid Palaeozoic time. A number of orogenies and more localised deformational events affected the region. A simplified classification scheme for the diverse gold deposit types is proposed, subdividing primary mineralizing processes into four categories: volcanism (epithermal and volcanogenic deposits), igneous intrusion (subvolcanic/porphyry style, skarn and magmatic deposits), metahydrothermal processes (deposits generated during metamorphism and regional deformation) and hydrothermal-distal processes (deposits generated by poorly understood, generally remote large scale hydrothermal processes). Major gold deposit associations include epithermal and porphyry style deposits in Ordovician-Early Silurian shoshonitic andesite sequences; volcanogenic base metal-gold deposits in Silurian rift or basin felsic sequences; vein deposits in Late Silurian and Early Devonian S and I-type granitoids; deposits in Early Devonian sedimentary rocks of the Cobar Basin probably generated by metahydrothermal processes during basin closure and cleavage formation; deposits associated with serpentinite; and metahydrothermal quartz vein deposits in folded sedimentary rocks.Studies of host rock geochemistry suggest a relationship between magma types, gold enrichment and mineralization particularly in shoshonitic sequences and Early Devonian granitoids of the Boggy Plain Supersuite. Structural studies indicate the importance of thrust type structures and detachment faults in generation and location of gold mineralization. Lead isotope initial ratios help define metallogenic associations and a number of distinctive isotope "signatures" have been established.

Jan 1, 1990

By Leigh J. H

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

Jan 1, 1976

Any engineering firm hoping to do business in the modern world must understand-and take into account-the social and economic realities of client, country, culture, and community. If these considerations are ignored, any large-scale international development project is doomed to failure even before it begins. In this changing world, the distinctions between `developed', `developing', and `less developed' nations are more and more blurred. The so-called `less-developed' and `developing' nations are rapidly acquiring technology, an educated man- agerial and technical class, manufacturing capa- bilities, a growing spectrum of developed financial and raw materials resources, and a broad range of labour skills. These nations are establishing themselves as an integral part of the modern world, on an equal footing with other nations and with justifiable expectations for an ever higher standard of living and an ever better quality of Life.

Jan 1, 1978

By R A. Pax

Operational grinding mills emit significant acoustic emissions which are a consequence of the dynamic environment prevailing inside them. From a technical perspective, the noise presents an opportunity to determine some details of the processes occurring inside the mills. The noise generated is not random and can be attributed to a range of events that occur inside these mills, consequently non-contact acoustic determinations of in-mill behaviour provide powerful insights into the operation of primary comminution tumbling mills. To enable a logically coherent picture to be formed of the processes inside a mill, arrays of microphones have been used. This approach allows a clearer picture of the in-mill behaviour of the charge to be accessed. In contrast to single microphone approaches, usually located near the expected charge toe position, an array of microphones allows much more useful information to be obtained from grinding mill noise.This paper will discuss and present data obtained from microphone arrays positioned at the toe and shoulder locations of a mill, and how this information can then be used for the optimisation of grinding mills in real-time.CITATION:Pax, R A, 2012. Determining mill operational efficiencies using non-contact acoustic emissions from microphone arrays, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 119-126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Porphyry type mineralization of Lower Cretaceous age in eastern Queensland has been recognized only from the easternmost part of the northern New England Orogen (Day, Murray and Whitaker, 1978), within the northern Yarrol Province (Horton,1982). Recent work about the Mt. Suthers (Pb, Zn, Ag, Cu, Au), Lug-e-nor (Cu, Pb, Zn, Ag, Au, Mo), and German Tully (Cu, Au, Bi) prospects suggest that there has been a phase of porphyry type mineralization within the Gympie Province, of Lower Cretaceous age, overprinting earlier Permo-Triassic phases. About the Mt. Suthers Prospect surface samples of shallow, medium to heavy textured soils derived from marine sedimentary rocks of Permian age, and extrusive and intrusive igneous rocks of intermediate composition and Triassic age, were analysed for Cu, Zn, Pb, Co, Cr, Ni, Fe, V, Mn and Ag. Whereas strong iithological control determined the distribu- tion of Cu (diorite) and of Cr, Ni, Fe and V ,sedimentary rocks), the distribution of Pb, Zn, Ag and of Cu, were determined by mineralization of faults by a cavity fill hydrothermal process. Gold is associated with the Pb, Zn, Ag mineralization. Co and Mn showed distributions independent of lithology and structure. The fault controlled style of mineraliz- ation at Mt. Suthers is repeated at other localities to the south; Calgoa, Marodian, and German Gully. Relative dating of structural features and isotopic dating of nornblende porphyrites (134-135 m.y.) near and related to those mineralized at German c;ully suggest a previously unrecognized phase of porphyry copper style mineralization in south-east Queensland of Lower Cretaceous age (Fig. 1).

Jan 1, 1987

The major slime forming minerals in coal seams are generally montmorillonite, illite and kaolinite, and due to the consistant trend to full seam mechanisation in New South Wales and Queensland these minerals remain in the feed to a coal preparation plant. After coming into contact with water their size degradation is very rapid, and therefore they mostly report to the fine coal cleaning section of the plant. Froth flotation, being the most effective method of beneficiating fine coal, is widely practised in these two major coal producing states of Australia. Plant experience and laboratory tests suggest that the presence of these slimes in the flotation circuit depresses the flotation of fine coal. Although the deleterious effects of slimes on the flotation behaviour of minerals is well known, the mode of their adsorption at the mineral surface has been a subject of controversy for some time. In this paper, on the basis of the surface properties of slime forming minerals and coal, a model has been put forward to explain the adsorption of slimes at the coal surface. The degree of slime coating has been examined by scanning electron microscopy. Laboratory tests have revealed that with the appropriate use of polyvalent phosphate electrolytes these slimes can be liberated from the coal surface. Just attrition and desliming are not enough to ensure complete liberation of slimes. Coal, after treatment with these electrolytes and then deslimed, floats readily with a common frother, such as MIBC. Modifications in the conventional flotation circuits have been suggested to ensure an efficient flotation of fine coal.

Jan 1, 1978

In todayÆs demanding business landscape continual change and technological advancement is a given. With these changes there is now, more than ever, a need to ensure sustainable growth in respect of value protection and value adding whilst meeting the pressures and expectations of the societies in which we operate. Traditionally the management of safety has been a very reactive activity in the business, in some cases seen as an irritation and a disruptive process that demands a focus on preventing reoccurrences. This in turn has focused the measurement of safety performance on a range of lagging indicators û æafter the effect managementÆ. Gaining and maintaining a licence to operate is crucial to a sustainable business but as a prerequisite, organisations need to have a demonstrable ability to manage the safety of their people, as well as mitigating the people risk associated with the business activity. A major focus in the last decade has been on the implementation of enterprise risk management programs, where risk becomes embedded in all business systems and processes and the organisationsÆ genetic make up is programmed to analyse and integrate risk management into all facets of the business activity. The management of safety should be no different. One school of thought argues that there are no new accidents, but rather our inability to learn from the past. Others believe that as long as we have an appetite to achieve the unachievable, we will have to continue to push the boundaries, our safety comfort zones and inevitably take risks. Single reliance on highly evolved technical systems, elaborate processes, highly skilled people, safe equipment and safe work environments have shown one thing û they are not sustainable in providing adequate coverage in the business. In analysing a range of factors associated with some of the worst catastrophes of the 20th century, it can be suggested that they were in fact predictable and inevitable and that an integrated approach underpinned by sound risk management systems could have determined a different result. The key to a sustainable approach in the management of safety requires us to look at a multitude of aspects that collectively allow the performance of an organisation to be predictable. To have certainty in the business activities it is necessary to have controls in place that will mitigate the risks normally associated with unwanted events. It is ensuring that human factors effectively contribute to monitoring the planned approach and being able to safely adjust to any variability. In essence this is having the ability to proactively plan for the longer term. The sentiments articulated by organisational leaders echo that safety management is good business. Surely then a good business is a sustainable business, and a sustainable business is one that provides lasting benefits to its stakeholders.

Jan 1, 2006

By N F. Glenn, S Thiruchittampalam, B P. Banerjee, S Raval

The determination of shear strength parameters for the spoil material plays a crucial role in the assessment of a dump’s stability; nevertheless, their evaluation necessitates laborious laboratory experiments. In order to address this issue, Simmons and McManus (2004) formulated a framework that serves as a foundation for categorising spoils according to their distinctive shear strength parameters based on observable and tactile characteristics. This framework, previously identified as the ‘BHP Mitsubishi Alliance Coal (BMAC) Spoil Shear Strength Framework’, is now recognised as the ‘CoalSpoil’ framework. The spoil characterisation provided by the CoalSpoil framework offers benefits but is not without limitations. The examination of these attributes in the field is a time-consuming task that demands expertise. Subjectivity arises in the spoil characterisation when attributes straddle the line between two categories, such as delineating matrix-supported and framework-supported fabric structures. To enhance consistency in the spoil characterisation process, minimising human intervention is crucial to mitigate bias, classification errors, and safety risks. This study seeks to achieve this aim by introducing image-assisted and automated methods for spoil characterisation.

Sep 1, 2024

By K Koskinen, S Ronkainen

The flow field induced in an Outokumpu TankCell and by an OK rotor-stator mixing device in a laboratory and a process size flotation cell was modelled numerically using computational fluid dynamics (CFD). The primary target was to discover and reproduce the various interactions between the flow field and the flotation cell by numerical means. As power consumption depends sensitively on flow field, it can be regarded as a top-level derived quantity (or measure/metric) indicating the validity of the numerically obtained flow field. Having properly validated numerical means to produce the flow field the influence of various design parameters can be captured with certain accuracy. In addition, separate gas and solid phase models for bubbles and solids, respectively, were implemented. The comparisons between velocities and turbulence quantities measured using the laser doppler velocimetry (LDV) technique and CFD modelling were performed. The grid generation was performed with the commercial Gambit 1.3 and the subsequent integration and solving of the resulting algebraic equations with the commercial CFD-code Fluent 6.22. The computationally economic multiple reference frame method was included to model the moving rotor blades. Gas and solid phase models were modified mixture models.

Jan 1, 2005

By S Bandopadhyay

The seasonal fluctuations of the dust content in Arctic mine environments and the environmental variables affecting the intensity of dust production are qualitatively well known, but quantitative models that allow simulation and prediction of dust generation and the effects of engineering control of thermal regime on the mine environment are still non-existent. In Arctic mines, the migration of moisture in the surrounding rock mass releases fine dust by freeing it from the ice matrix allowing it to escape into mine airway. The migration of moisture is the direct cause for the production of mine dust and heat is the primary driving force. This paper examins the heat and moisture exchange between the ventilation air and the surrounding rock mass in frozen ground, placer mines in the Arctic. Based on the simulated results of a coupled heat and mass transfer problem with phase change, methods of dust control have been identified for mines in the Arctic.

Jan 1, 2005

By Lawrence L. J

The Australian Broken Hill Consols Mine, situated some 600 yd east of the main Broken Hill line of lode, is noted for its rich ores of silver. In contrast to the vast conformable orebodies of the Broken Hill field, the Consols lode occupies a narrow fissure dipping to the south west at angles increasing from 240 through to vertical and transgressing the strike of the metamorphosed country rock at an oblique angle. This feature, together with the abundance of calcite and siderite and the virtual absence of silicate minerals in the gangue, has led to its classification as an orebody of the Thackeringa type (King, 1953). Recorded production during the period 1890 to 1903 is given as 845,000 oz of silver and 20 tons of lead.The unusually rich silver values of the Consols lode were concentrated at the intersection of the fissure with beds of amphibolite, whereas in the adjacent schists and gneisses the lode became markedly impoverished. From the surface to a depth of some 120 ft extensive surface oxidation had occurred, resulting in the breakdown of siderite and its replacement by limonite and associated manganese oxides.Silver halides, dyscrasite, acanthite and partly oxidised tetrahedrite were the main silver minerals in this zone. With increasing depth the lode material gradually reverted to minerals representative of the hypogene zone.The only previous work specifically on the mineralogy of the Consols lode is that by Smith (1922), one time manager of the mine. His zeal as a mineral collector resulted in much valuable information being available on the distribution of the minerals. More recently, Garretty (1943) noted the...

Jan 1, 1962

East Nelson and Marlborough, in the northeast of the South Island, contain a wide variety of metallic minerals, including gold, silver, copper, chromite, antimony and scheelite, but no sustained metallic mining industry has evolved. Gold was the most sought-after mineral during the first century of European settlement and numerous discoveries were made but these failed to live up to expectations. While traces of gold are widespread in east Nelson, including in quartz veins in Nelson City, no payable deposits were found. In Marlborough the probability of a gold discovery had initially seemed remote but all this changed with the finding of rich deposits in the bed of the Wakamarina River in 1864, which provided a much-needed boost to the provincial economy. However, the decline of gold mining in Marlborough began virtually as soon as it had commenced. Extensive floods in 1865 hastened the exodus of miners to the profitable new fields of the West Coast.

Jan 1, 1993

By J Bartlett, P Quigley

Historical research has played a significant role in the rebirth of the Bendigo Goldfield. The historical research undertaken by the company has been directed to specific areas such as verifying the total gold production of the field, the gold production from defined blocks on each of the major anticlines, the extent of workings of each mine which exceeded 200 m depth, the size and style of reefs mined in each shaft and also within specific domains of the field. Application of this data has assisted in the determination of possible dimensions of different reef styles and the location of mineralisation within each reef system. Description of grade variation, percentage of quartz and the amount and species of accessory sulphide minerals, as well as early geotechnical observations accompanying stoping methodologies, provides valuable analogues for reef structure being defined in the current program. Historical information on shafts on the two anticlines the company is exploring has allowed the postulation and recognition of repetition of reef development within the same stratigraphy in the hinge zones of the adjacent folds. The similarities of mineralisation styles across the field within both specific lithological units and structural setting has had important implications in respect to exploration drill targeting and the estimation of grade and tonnes.

Jan 1, 2003

It was Harold McMillan, Prime Minister of England 30 years ago, who used the phrase "The Wind of Change" to describe political events in Africa in his day. So well did this phrase capture the spirit of the time that it echoed around the world, and the echo has never stopped. Change is the constant factor in the society in which we live and everyone of us has had experience of the effect which it has had on our professional and personal lives.Change will not stop, it will continue at an increasing rate and the questions we must answer are how do we prepare ourselves to meet the challenge of future change and how do we take advantage of the opportunities which it will bring?It is these questions which I wish to discuss in this address.There is nothing new about change in the mineral industry, it has been happening for thousands of years and it will continue as long as civilisation exists on earth. One type of change is economic and we are all aware of the rises and falls which occur in the prices of metals and minerals (Figure 1). When these have happened in an orderly manner, and could be predicted and planned for, it has been possible to take advantage of the benefits and minimise ill-effects, but when they were sudden and precipitate, and could not be predicted, the consequences were serious. The extreme example, of course, was the oil price shock of the 1970s which had such disastrous effects on industry and society.Other types of change are social, cultural and political. They have all been important in recent years and will continue to be so in the future.But it is technological change which may well be the most important because its effects are profound and irreversible, and alter irrevocably the way in which we live. So in discussing the mineral industry in a changing world I will talk specifically about technological change.

Jan 1, 1989

Low-grade, porphyry copper type mineralization at the Moonmera prospect is related to the intrusion of a granodiorite porphyry mass into the Upper Permian "Gracemere granodiorite". Significant copper mineraliza- tion appears to be associated with the alteration assemblage quartz-sericite- kaolinite. The ore shell is surrounded by a zone where montmorillonite and kaolinite are in greater abundance and this assemblage is over- lapped, mainly at depth, by potassium feldspar alteration. Secondary biotite is abundant throughout the mineralized zone. Preliminary sulphur isotope results on the sulphide mineralization are compatible with a magmatic origin for the sulphur.

Jan 1, 1974

This paper summarises the current status of the mining sector in Poland in terms of vertical transport system safety. Selected results of research programs conducted at the AGH-UST relating to mine hoist system safety are reviewed. The conclusions support the notion that the costs of vertical transport systems can be reduced, while at the same time maintaining the required safety and reliability levels. Novel solutions: movable fender beams HWR, linings modar« and the integrated shock absorbers PHH for conveyance guiding systems fully confirm this hypothesis.

Jan 1, 2005

By T Davis

Cameco Corporation operates the high-grade 140 tpd fly-in/fly-out underground McArthur River Uranium Mine in Northern Saskatchewan in a joint venture with Cogema Resources Inc. Reserve grade is in excess of 20 per cent U3O8 with current mining grade averaging 16 per cent U3O8. Due to the high radiation potential of the ore, the non-entry mining method of raiseboring was chosen to minimise worker radiation exposure potential. The raisebore and extraction horizons are located in waste rock with the orebody located between horizons. Ore produced by raiseboring is delivered by LHD to an underground SAG mill and is then hydraulically hoisted to surface receiving facilities after underground thickening to 50 per cent solids by weight. Concrete backfilling is utilised. The orebodies at McArthur River are adjacent to water bearing sandstone. Ground freezing is therefore employed to isolate the ore from this water bearing ground. Calcium chloride brine at -35¦C is circulated through a series of cased boreholes to establish freeze walls up to 25 metres in thickness. At 18 000 000 lb of low cost U3O8 production per annum, McArthur River ranks as the worldsÆ largest uranium mine. Over 50 per cent of the workforce resides in this sparsely populated area of Canada with approximately 40 per cent being of aboriginal ancestry. Site operations must cater for winter temperatures as low as -50¦C.

Jan 1, 2002

By I R. F MacCulloch, K Jones

Pintail Systems, Inc, a Colorado USA based company has developed and commercially applied bioremediation processes for biological detoxification of cyanide compounds in mine waste. Site-specific microorganisms are isolated from spent ore, tailings or process solutions and augmented in the laboratory for cyanide oxidation, denitrification and metal biomineralisation. Biological processes typically treat complex contaminants (cyanide compounds, soluble metals and nitrates) in a fraction of the time of conventional remediation processes. Cyanide is used in microbial metabolic processes as a carbon or a nitrogen source. Biological detoxification processes applied at the end of mine life can end long-term liability and perpetual monitoring and containment. Case studies from commercial application and demonstration programs for the US Environmental Protection Agency will be presented in this paper.

Jan 1, 2004

By J Hadjigeorgiou, T R. Stacey

A ground support system is a combination of individual reinforcement and surface support elements that work together to retain and contain the rock mass. The various elements are subjected to external loads and to interactive loading between individual ground support system components. This paper focuses on the challenges in determining the capacity and behaviour of mesh, recognizing that installed mesh can be subjected to several loading mechanisms. Field observations from underground hard rock mines demonstrate that there are multiple types of damage and modes of failure of mesh. However, these are difficult to reproduce in a laboratory environment. A critical review has shown that existing mesh laboratory testing rigs reproduce very limited loading conditions that may not be representative of underground conditions. This has significant implications in quantifying and extrapolating the performance of mesh to ground conditions. CITATION:Hadjigeorgiou, J and Stacey, T R, 2018. Challenges in determining the capacity of mesh, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 280–290 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By R Terracciano, J Schneider

Willemite (Zn2SiO4) is one of the main zinc carriers in several Neoproterozoic carbonate-hosted non-sulfide deposits ofNamibia and Zambia. Willemite commonly replaces sphalerite, but it may also replace the carbonate host rocks. Fluid inclusions, cathodoluminescence petrography and trace element geochemistry are crucial to distinguish between hypogene, high temperature and low temperature (possibly) supergene willemites. A global period of willemite mineralisation, extending from Cambrian to Lower Ordovician has been proposed for the southern hemisphere. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008