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By Tilley H. L

The 90 m deep Yallourn Open Cut brown coal mine in the Latrobe Valley, Victoria is developing into an area close to a reverse fault. A major batter stabilisation program, matched to ongoing operations, has com- menced to maximise coal recovery where the fault is within 100 m of the Open Cut. The various mine development options considered during the planning stages are outlined. These options were formulated in a back- ground of geotechnical constraints and the need to maintain continuous and reliable coal supply at a time when a new coal field would be developed. The geotechnical investigations and analysis procedures under- taken to determine stability of the batters during their excavation are presented. The geotechnical constraints on the mine design and opera- tions required to ensure safe working conditions are detailed. Current operational and batter stability conditions are considered satisfactory.

Jan 1, 1989

By Smith DM Jr

Silver deposits, in which silver forms at least fifty percent of the value of the ore, are abundant and large on the east side of the Pacific and are absent in the western Pacific. To determine if this uneven distribution is related to features of consuming plate tectonic boundaries which dominate the metallogeny of the Pacific Rim, the variation of Ag/Au in porphyry copper deposits was used to estimate the relative silver content of magma generated in subduction zones. Porphyry copper provinces with high Ag/Au occur in regions of the eastern Pacific where silver deposits are abundant, suggesting that the distribution of silver deposits is controlled by the relative abun- dance of silver in subducted ocean crust. Ocean crust being subducted in the eastern Pacific is mostly less than 50 million years old in contrast to most ocean crust in the western Pacific which is much older. Enrich- ment of silver in young ocean crust at spread- ing centers may reflect metallogenetic evolution over geologic time. Silver may be transported to the surface in volcanic rocks, and deposits are common where felsic varieties are abundant. The high ,solubility of silver in natural waters provides a natural storage mechanism for silver weath- ered from these rocks and ultimately circulated in near-surface hydrothermal systems where many silver deposits form. The regional distribution of silver deposits is not influenced by discoverability, vertical metal zoning, or regional tectonic style. The effect of igneous differentiation is unclear.

Jan 1, 1987

By C McIntosh, M Carder, P M. J Durance

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Disseminated, gold-bearing sulfide minerals hosted in sheared, wall rock metasediments and clay alteration zones comprise one of the dominant styles of Palaeozoic orogenic gold mineralisation within the Reefton Goldfield, and is exemplified by OceanaGold’s Globe Mine. This study begins the exploration and characterisation of the gold-arsenic-antimony mineralisation hosted within the dominant lithologies of the Globe-Progress shear zone. The main gold-bearing sulfides are pyrite, arsenopyrite and stibnite. Pyrite and arsenopyrite are not compositionally uniform across the Globe-Progress shear zone. Pyrite from the mineralised greywacke and argillite has higher As contents than pyrite in the host rock and pug breccia. Furthermore, the mineralised greywacke and argillite pyrite are enriched in As from core to rim. The 3D models based on bulk assays reveal a significant correlation in the distribution of Au, As and Sb. The interpolant for Sb envelops those for Au and As, which in turn are very similar to each other in their vertical and lateral extents across the shear zone. This result is consistent with earlier findings that the occurrence of stibnite represents a separate and likely later phase of mineralisation relative to that represented by the formation of disseminated pyrite and arsenopyrite both of which exert a stronger control on the distribution of As.CITATION:Durance, P M J, Christie, A B, McIntosh, C and Carder, M, 2015. The composition of disseminated, gold-bearing sulfides within the three-dimensional framework of bulk Au, As and Sb in the Globe-Progress orogenic gold deposit, Reefton Goldfield, New Zealand, in Proceedings PACRIM 2015 Congress, pp 327–334 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

A broad zone of intra-plate volcanism occurs for some 3000 km along the E. Australian coastal regions, extending from far northern Queensland southwards to Tasmania, westwards to western Victoria, and into southeastern South Australia. The age range, taken over the whole region, extends from Eocene to Holocene. Wellman & McDougall (1974) recognised the occurrence of three distinct types of volcanic occurrences: (a) Lava field provinces, dominantly basaltic and commonly strongly undersaturated, but of variable size. Large lava fields are especially exemplified by the younger provinces in northern Queensland (e.g. Nulla, McBride), and western Victoria. (b) Central volcano provinces, in which a reasonably well defined volcanic edifice is discernable. Such provinces are built of mildly undersaturated to saturated mafic lavas, but are also characterised by felsic volcanism (and often substantial mafic and felsic intrusive phases). Examples are the Springsure-Minerva Hills province, the Tweed and Focal Peak Shields (southeastern Queensland to northeastern N.S.W.), and the Nandewars, Warrumbungles, and Canobolas volcanic centres (N.S.W.). (c) A single leucitite province in N.S.W. Wellman and McDougall (1974) were able to show that the central volcano provinces exhibit a remarkably regular southward age migration pattern, the calculated migration rate being 66 + 5 mm yr , and these authors interpreted this in terms of the northward passage of the Australian plate across a fixed 'hotspot' within the upper mantle. The leucitite province also fits this migration pattern. The lava field provinces apparently exhibit more erratic regional age distribution patterns, but Sutherland (1981) has interpreted the data in terms of a multiple 'hotspot' model. It is noted, however, that the youngest areas of volcanism (Pleistocene 1. Department of Geology and Mineralogy, University of Queensland, St. Lucia, Brisbane, Queensland

Jan 1, 1987

By Armoo K, Tran T

Cementation has been widely used in several hydrometallurgical processes for recovering gold and silver from process liquors. The process is electrochemical in nature, in which gold and silver are precipitated from the solution using less noble metals such as zinc, iron and copper. This paper summarises the current practice of gold cementation from cyanide liquors using zinc powder. Various developmental studies on the cementation of gold and silver from various systems (chloride and bromide) are also reported.

Jan 1, 1991

By Vynne J. F

Drill monitors for blasthole and exploration drills have been available to the mining industry since the 1970s. The early monitors were pen strip chart recorders which were developed for the oil drilling industry and adapted to mining. They recorded drilling parameters such as depth, pull-down pressure, torque, RPM, and bailing air pressure. While these recorders could generate a large volume of paper, the amount of useful data was minimal. The data was not summarised and required an engineer to interrupt the chart traces. Being a mechanical recorder, the devices were also susceptible to frequent failures.

Jan 1, 1993

By Eren H

For a hydrocyclone of fIXed geometry, DC, Di, DO and ? are constants, the variable parameters affecting the performance are Qi, Fi, Du and H. (See Appendix 2 for definition of symbols).The relationship between d50c, Qi, Fi, Du and H gives models which can effectively be used for performance predictions. Such models have already been established by Lynch et al and by Plitt.These models have been tried in a limited manner under continuous operating conditions for on-line cowol. For on-line control effective and accurate instrumentation is required for which a new set up is proposed. Using this set up, a new model was established. A feature in this model is that deviations from the norm of operational parameters affecting d50c were considered. It is shown that these deviations generated by the disturbance of one or more of variations in the parameters, can be monitored by a computer and suitable signals generated to control servo mechanisms for restoring the required d50c value.The logic followed in developing the computer software is described and the application of the model is indicated.

Jan 1, 1990

Slide presentation at conference

Jan 1, 1996

The techniques originally developed to process digital images of Mars, later gained widespread acceptance when applied to Landsat data: they are now making a significant impact in fields of geology outside remote sensing. The three ingredients of success are seen to be firstly, the perceptual attributes of image displays and the use of colour; secondly, the absolute ability to register data from a variety of sources; and thirdly, the speed of specialist "interactive" digital image display systems. The future lies in further exploiting these attributes through a Geographic Information Systems (GIS) approach to data handling, integration and display.

Jan 1, 1986

By Gonzalez JM

The Pao gold prospect in N. Luzon, is an example of a high sulphidation epithermal gold system hosted in Mid-Tertiary alkaline volcanics, in the Philippine Arc. Styles of mineralization include: quartz-enargite veins, vuggy silica alteration bodies, and pervasive low grade (0.5ppm) gold mineralization, associated with kaolinite-pyrite-quartz alteration, and geochemically characterized by high As and Hg. Early magnetite-epidote-chlorite alteration linked to an unexposed granitoid is overprinted by an extensive zone of advanced argillic alteration (kaolinite-pyrite-quartz). No alunite is recorded. Important controls of mineralization include; a broad anticline intersected by axial faults, permeable pyroclastic units, and upward confinement of the alteration system by a highly impermeable, clay-rich volcanic unit. At this stratigraphic position the most important mineralization waz developed. The Pao high sulphidation system is not closely related to a stratovolcanic centre, and has formed subsequent to deformation of the volcanic field. It may, however, be related to an unexposed comagmatic intrusion.

Jan 1, 1990

The grinding of ore to a size that is conducive to the extraction of minerals by leaching or flotation is an essential and expensive component of most mineral-processing operations. Overgrinding results in reduced flotability of the minerals, as well as problems in the filtration and thickening processes, while undergrinding leads to a product in which the minerals have not been exposed, and cannot be leached or floated effectively. Furthermore, coarse material causes settling in thickeners and agitator tanks. It is therefore essential, from the perspective of both operational and extraction efficiency, to grind the ore to an optimum size fraction. A well-run milling circuit will yield a product within a narrow size band and at a high throughput. Although the effective operation and control of milling circuits with their many operating parameters is widely acknowledged as a complex as well as a critically important operation, the benefits of such control are difficult to quantify. This is due to the difficulties in relating more stable operation to increased recovery of the valuable components in downstream processes.

Jan 1, 1993

The invitation to speak today was in the form of a single sentence instruction: How does your company run and how do you communicate from top to bottom? It looks like I'll have to let you into our little secret. The team at Croesus know what works for us but we've never talked about it with others - least of all presented it at a conference such as this. In fact we tend to avoid the jargon normally associated with Best Practice or TQM, however in our own way, each of our staff are 100 per cent loyal to our company's aim to maintain and strengthen our commercial success. Just how we achieve this at Croesus is the subject of this presentation today, but first a little history. My dear old grandfather arrived in Kalgoorlie, as a mining engineer 100 years ago. Do you think he would have chuckled if someone suggested to him that a hundred years later we would just be starting to understand Kalgoorlie's geological mysteries? Well, here we are 100 years later and Croesus Mining is fortunate to be part of a generation now realising the true potential of Kalgoorlie's Goldfields. This provides us with a very fertile field in which to sow the seeds we can obtain from the World's Best Practice in Mining and Processing. With each new mineral deposit being discovered, old theories are being exploded. Each new deposit has a personality of its own, leading to some belated pioneering theories of where to drill next, and how to reduce internal costs so that we can win the war against constantly increasing external costs. What we have now and what the old timers didn't have is a huge database of geological input spanning several gold booms and a couple of nickel booms. My only interest in history is to pick up the points that may help us for our future. This is what we are doing in our company which is something of a David, in the David to Goliath range of mining companies in Australia. As a humbling thought; of the 115 164 tonnes of gold that the world's mines have produced throughout history, four tonnes have been produced by Croesus Mining. That's equivalent to 0.003 per cent of the total world's gold production. In the past financial year we achieved a dividend yield of five per cent. To put this into perspective, that's over twice the dividend yield of BHP, Australia's largest company. As we are somewhat less known than BHP, let me spend a few moments giving some particulars of our company's background.

Jan 1, 1995

The effects of process variables such as solution chemistry, flocculent type and dosage, intensity and duration of mixing, and solids type and concentration, on the performance of flocculation/clarification/thickening processes are described. System response is evaluated in terms of the specific effects on floc settling, supernatant clarity and sediment compressibility. The implications of these results with respect to industrial practice are discussed and general guidelines for direct application to plant design and operation are suggested.

Jan 1, 1993

By J Zhou, D M. Hunter, S M. Iveson, K P. Galvin

The recovery and concentration of ultra-fine iron ore can provide significant economic benefits. Presently, there are limited options available given the low settling rates achieved by conventional gravity separation and the relatively poor performance of reverse flotation. The Reflux Classifier is a new water-based gravity separation technology that consists of a set of parallel inclined channels positioned above a vertical fluidised section. This arrangement promotes a powerful throughput advantage compared to conventional fluidisation and a highly selective hydrodynamic basis for achieving sharp separations. A high shear rate develops within the inclined channels, which generates sufficient hydrodynamic lift to convey the lower-density particles (even if they are relatively coarse) to overflow while retaining the high-density particles (even those that are ultra-fine) for discharge to the underflow. The technology has previously been used around the world on particle sizes in excess of 0.1 mm. The present work, however, is concerned with density-based separations down to much finer particle sizes approaching 0.01 mm.A major advantage of the Reflux Classifier technology is the achievement of simultaneous gravity separation and desliming via a single-stage separation. A series of continuous experiments was conducted using an iron ore feed with head grade of 35 wt per cent FeT and nominal top size of 0.106 mm, with 59 wt per cent being below 0.038 mm in size. At a low throughput of 1.5 t/(m2 h), the Reflux Classifier produced high-grade products at a high recovery. For the entire feed, grades of 66.1 wt per cent FeT with Fe recoveries of 80 per cent were achieved in a single-stage separation. Within the 0.020–0.038 mm size fraction, grades of 68.8 per cent were achieved with iron recoveries of 94.7 per cent. Excellent recoveries of up to 57.0 per cent were achieved for the -0.020 mm size fraction. The ability of the inclined channels to retain the fine dense material further enhances the effectiveness of the Reflux Classifier by creating an autogenous dense medium effect within the vertical section. This helps to elevate large gangue particles up into the overflow.CITATION:Hunter, D M, Zhou, J, Iveson, S M and Galvin, K P, 2015. Gravity separation of ultra-fine iron ore in the reflux classifier, in Proceedings Iron Ore 2015, pp 143–148 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

The winning and upgrading of mineral raw materials necessarily includes size reduction, which serves the liberation and production of marketable products from highly valuable and bulk materials. For crushing, the following factors can be duly accounted for depending on material type and the selection of the suitable machine: ò producing a particular size distribution, ò producing a particular grain shape, ò selective comminution, ò gentle comminution, and ò producing a size range required by a specific process and/or for a specific product.

Jan 1, 1993

The movements of the major continental cratons and the distribution of the principal tectonostratigraphic terranes are reviewed in the Circum-Pacific region during Phanerozoic time. It is concluded that major periods of orogeny and consolidation of accreted terranes in the Circum-Pacific region is best correlated with periods of advance of cratonic blocks over the Pacific Ocean basin combined with relative convergent to transpressive motions between the cratons and the Pacific Ocean plates. Continental collisions and collision of terranes with continental margins has not been a significant geodynamic process in Circum-Pacific tectonic evolution. The permanency of the Pacific Ocean basin throughout 500 MA is remarkable. It appears no continental block or large continental fragment has ever entered or crossed the Pacific Ocean basin since early Paleozoic time. This area where no continent has entered for 500 MA is almost coincident with the present Pacific Ocean basin and seems associated with the 25 to 100 meter geoid high which dominates the present-day figure of the Earth.

Jan 1, 1990

By D Morrison

Backfill is usually considered a necessary evil that contributes little to the principal objective of the operation, ore production. Consequently, it is relegated to an auxiliary role in the operation with minimal equipment and resource allocation in planning and is only superficially considered during feasibility studies. In many mines, the inadequacy of the design and operation of the backfill system ultimately leads to frequent delays, excessive costs and, in the worst cases, major instabilities which result in reduced ore production and lost or unrecoverable ore reserves. The primary objective of backfill is to prevent the progressive deterioration of mined out excavations. With the exception of narrow vein operations, it is too weak to alter the mining induced stress regime and control stress concentrations caused by stope extractions. However, the direct benefits of backfill include the possibility to consider a wider range of mining methods, recovery of 100 per cent of the planned resource and the selection of a stoping sequence that minimises the regional stability problems that cause production shortfalls in the later years of mine production. Indirectly, backfill is a practical means of solving other issues, such as waste disposal, that impact the viability of mining. In Australia, the geotechnical conditions of many mines are becoming more difficult and increased attention to the importance of backfill is warranted. This paper describes realistic aspects of backfilling and the positive impacts a well co-ordinated fill system can have on mining activities as a whole. Examples are presented where an integrated approach to backfill systems have offered significant benefits to the operation.

Jan 1, 1998

The Division of Minerals and Geochemistry in collaboration with three mineral exploration companies, Mawson Pacific Ltd, Ramsgate Resources Ltd and Tectonic Systems Pty Ltd commenced a two year research project to investigate the application of remote sensing techniques to exploration for mineral deposits in access of the Yilgarn Block in Western Australia. The project utilizes satellite data such as day and night imagery from the NOAA-AVHRR (National Oceanic and Atmospheric Administration - Advanced Very High Resolution Radiometer) satellite. The recent research with the imagery in the Kalgoorlie, Southern Cross and Mt Magnet regions has highlighted the advantages of the mid infra-red and the two thermal response channels of NOAA-AVHRR for geological investigations. These three channels have the spectral resolution to distinguish stratigraphic units and younger intrusive bodies, and to delineate fracture zones and shear zones associated with Proterozoic dykes. But most important is the capacity to distinguish thermal signatures from geological structure, near-surface outcrop and palaeochannels which have been covered by unconsolidated sediments. The research project applies remote sensing methods including enhanced satellite imagery optimised to the Western Australian environment. It encompasses data from both space and airborne monitoring platforms that have obsreved a significant spectral response for the classification of alteration zone lithologies. It includes the collection of multiseasonal data from areas of interest which is essential both for the understanding of thermal characteristics of important lithologies and for the extrapolation from field work investigation to potential exploration areas. No comprehensive investigation of this type has been carried out within the Yilgarn goldfields.

Jan 1, 1987

By Bush P. R, Hale M, Dixon C. J, Wheatley M. R

Barium anomalies in drainage sediments can act as indicators of barite mineralization and path- finders for lead-zinc mineralization. Their detection in an arid climate has been investigated in two areas of Saudi Arabia. At Rabigh, 150 km north of Jeddah, barium anomalies found in wadi sediments reflect barite veins which occupy Tertiary faults in Precambrian metavolcanics and granodiorite. In the Wadi ad Dawasir area, 650 km east of Jeddah, the sediments of wadis draining the Jabal Tuwayq escarpment have been found to contain anomalous concentrations of barium derived from diagenetic barite in the Sudair formation siltstones and shales. Barium dispersion in these wadis is predominantly clastic. Near to the source rocks, barium occurs in relatively coarse grains of barite. Owing to the three well-developed cleavages of barite, its crystals readily break into cleavage flakes during fluvial transport in flash floods; as a result, the longest anomalous dispersion trains are found in the 250 to 600 um fraction. Wadi sediments finer than 250 um have relatively constant and low barium contents, being dominantly composed of windblown sand.

Jan 1, 1988

By S H. Sie, R Seetharam, K Naito, T Takagi

Tin-polymetallic vein type deposits are one of the major source of metal producers in the Circum Pacific Belt. This type of deposit is of great importance for the modem electronics and medical industries because of their high content of rare metals (especially indium and bismuth). We have studied two representatives, Tosham of India (Cu-In-Bi-Sn-W-Ag-Au), and Mount Pleasant of Canada (Zn-Cu-In-Bi-Sn-W), using proton and electron microprobes in order to delineate the distribution of medicallhigh-tech rare metals. The electron microprobe study showed that major indium carrier in such type of deposit are roquesite (CulnS2), sphalerite, stannite and a Cu-Zn-Fe-In-Sn-S mineral; and that indium is incorporated in sulfides by coupled substitution like Cu + In = 2(Zn + Fe). The proton microprobe showed that indium at trace levels is also present in chalcopyrite and pyrite. In addition, zinc, copper, arsenic, antimony, selenium, tin, and bismuth are common in chalcopyrite and pyrite. Arsenopyrite contains nickel, copper, zinc, silver, tin, antimony and bismuth. In chalcopyrite and pyrite, zinc, arsenic, indium, bismuth and lead are higher in Mount Pleasant ore, but silver is higher at Tosham. Also thallium and gold were found only in Tosham pyrite. The Tosham deposit is genetically related to S-type magma, while the Mount Pleasant deposit is related to A-type granite. Tosham ore contains zinc-bearing biotites that coexist with chalcopyrite in ore bodies but Mount Pleasant ore lacks such biotite. We propose that the difference in elemental abundance between the two deposits are caused by the different character of source magma and different mineral associations of the ore body.

Jan 1, 1995