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By C P. de Jager, J J. Taljaard

Over the past 75 years, the mining of platinum has predominantly focused on the Merensky Reef horizon in the western Bushveld region of the Bushveld Igneous Complex (BIC) of South Africa (Figure 1). The orebody is relatively flat dipping at 10¦ to 25¦, narrow tabular in shape and has been mined to a maximum depth of some 1600 m within Anglo Platinum. This has resulted in the installation of up to four generations of shaft systems as mining progressed into reserves at greater depth. In recent years, with the improvement in processing technology and improved economics, in particular with the improved price of palladium, the mining of the UG2 Chromitite Reef is proving economically viable. The UG2 Chromitite Reef occurs below the Merensky Reef in the succession and the normal separation varies from 15 m to 400 m, with the largest separation between the reefs occurring in the eastern region of the BIC. The UG2 Chromitite Reef horizon is now being accessed from existing Merensky mining infrastructure by cross-cutting back through the stratigraphy where appropriate, or by establishing new decline cluster systems from surface, along the extensive strike length of the various mining properties. These declines are generally established utilising mechanised mining techniques. This paper gives an overview of the techno-economic approaches considered and evaluated for the selection of the optimum mining and shaft systems. More specifically, the paper reviews the design parameters used, techno-economics, conveyor versus haul alternatives, logistics simulations, capital costs, system performance, time to market or ramp-up success, important system differences and lessons learnt.

Jan 1, 2005

By A E. Petts

Record iron ore prices and a renaissance of infrastructure in the Pilbara have Flinders Mines poised to move from explorer/developer to an iron ore producer. The potential of the company’s Pilbara Iron Ore Project was first highlighted by the announcement of Rio Tinto’s Caliwingina North deposit to the north and the Fortescue Metals group’s Serenity deposit in the southeast. The success of Flinders Mines’ exploration has been based on incorporating landscape studies into an existing geological framework, and using this to understand the iron-rich materials that were emplaced during the Tertiary. The development of the Delta and Eagle deposit resource models highlights this process. There are three main mineralisation styles at the project; detrital iron, channel iron and bedded iron deposits. They have textural and mineralogical similarities with comparative deposits in the region. Gaining an insight into the geological processes unique to detrital iron deposits and more distal channel iron deposits has been important to understanding the geometallurgy of the mineralisation. The model sits comfortably with other regional oregenesis models and allows a contextual framework to be developed around the timing of deposition of the Fe-rich detritus and pisolitic nodules that dominate the deposits. The exploration model also allows Flinders to explore more effectively for bedded iron mineralisation developed prior to, and since the development of the Tertiary weathering landscape.

Jul 11, 2011

By Horowitz F. G, Lamb P

As mining operations become larger and more complex, larger volumes of geological, geophysical, and production data must be manipulated and interpreted on a day-to-day basis. Because of the large volume of data, more sophisticated data storage strategies, interpretation tools, and visualisation tools must be used by exploration and mining operations in order to remain competitive. Critical to better practice is an understanding of the basic syntax and character of geological and mining data, expressed in the form of a data model. In the short-term, a data model can be used to implement or evaluate schemes for data storage or exchange. It can be used to evaluate software. In the longer term, a data model is essential to the design of the next generation of software for 3D geological modelling. In this and the related paper (Lin et al, 1995) the data model in use by CSIRO is presented, together with: 1. examples of the use of data transfer in the linkage of existing mining software; and 2. examples of the use of the data model in software design.

Jan 1, 1995

By A Li, H Jinto, M Laxman

The behaviour of tailings under cyclic loading has an impact on the stability and deformation of tailings dams and a good understanding of the cyclic behaviour of the tailings under earthquakes is important for tailings engineers and tailings operators for the design and safe operation of tailings dams. This paper presents an investigation into the cyclic behaviour of tailings using both laboratory cyclic direct simple shear (DSS) testing and numerical modelling. The laboratory testing involved cyclic DSS tests on gold tailings and zinc-copper tailings under different loadings and loading frequencies. The gold tailings specimen tested at a higher loading frequency and a higher cyclic stress ratio experienced spontaneous liquefaction during cyclic shearing and the zinc-copper tailings specimen tested at a lower loading frequency and a similar cyclic stress ratio exhibited ductile behaviour and liquefied due to cyclic mobility. The liquefaction behaviour of the tailings was modelled using an advanced constitutive model (UBCSAND), which was developed specifically to model soil liquefaction and strain softening under cyclic loading. The constitutive soil model presents the nonlinear soil behaviour under dynamic loading using a hyperbolic stress-strain relation. Dynamic analyses were carried out using a finite difference program FLAC. The cyclic stress-induced excess pore water pressures measured in the laboratory were modelled using numerical simulations of the laboratory tests under different loading conditions. The results of the non-linear dynamic analyses demonstrated the capability of numerical modelling of cyclic shearing induced excess pore water pressure and the onset of the spontaneous liquefaction. The laboratory investigation and numerical modelling technique provided the key properties and parameters for the dynamic analyses to assess the stability and deformation of tailings dams under design earthquake events. More importantly, the laboratory tests and numerical modelling provided some insights into liquefaction behaviour of the tailings during earthquakes. CITATION:Li, A, Laxman, M and Jinto, H, 2018. Liquefaction behaviour of tailings under cyclic simple shear testing, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 250–262 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

The Northland Peninsula of northern North Island, New Zealand contains a complex and diverse record of volcanism which reflects rapid tectonic changes during the late Cenozoic. The main volcanic associations observed on the peninsula are late Cretaceous- early oceanic crust obducted onto Northland at the end of the Oligocene, Miocene arc-type rocks and Pliocene-Quaternary intraplate basalts. This sucession of volcanic successions can be related to tectonic convergence developing into subduction and followed by a an environment of tectonic tension. While the volcanic activity is ultimately linked to specific tectonic regimes, because of rapid change magmatism was decoupled from the specific tectonic event. This decoupling of magmatism and tectonism appears to be a feature of the zones of plate interaction in the southwest Pacific region.

Jan 1, 1990

Since the earliest recorded prospecting of the 1860's mineral exploration and mining in Fiordland has been discouraged by the formidable physical difficulties presented by its isolation, extremely rugged relief, treacherous coastal waters and generally unfavourable weather conditions. Government assistance was often sought by the miners and prospectors but little, if any, support or encouragement was received after the initial period. During the 1840's decorative marble was quarried at Caswell and Dusky Sounds. A prospector discovered and attempted to mine copper sulphides to the north of Dusky Sound (Parks Mineral Beds) and near Mt Solitary. A small Pb, Zn, Cu, Ag, Au bearing quartz reef was discovered and driven on in the granite coast line of Preservation Inlet (Bradshaws Reef) and the ore roasted on site. Alluvial and quartz lode gold was discovered at Preservation Inlet in the 1890's and led to the recorded recovery of 11 000 oz of mainly lode gold. Falloff in grades with depth, thinning and splitting of the reefs and the high mining costs at this location led to a virtual abandonment of the field by 1906. In the late 1950's and early 1960's the geology of Fiordland was mapped by the Geological Survey at 1:250 000 scale, but field work was largely confined to the shore lines of the coast and fiords. In view of the physical difficulties it is not surprising that mineral exploration and mining up to 1970 was limited to the scant attention outlined above.

Jan 1, 1977

By Glastras M. V

The presence of arsenic in solutions which result from the processing of many sulphide minerals leads to a need to understand its speciation in aqueous systems and the reactions of those various species. This paper deals in particular with the precipitation of arsenic from aqueous solution in the form of insoluble inorganic compounds in order to remove arsenic from various hydrometallurgical process streams. The solubility and stability of the precipitates is examined. It has been found that many of the arsenic compounds presently used are more soluble than previously accepted and unstable in disposal sites such as tailings ponds.

Jan 1, 1987

By Rieniets S, Somerville J. L

In Morwell Open Cut brown coal mine, the overburden 'firehole' materials which have resulted from ancient coal fires vary-from hard baked clays to firm laminated lacustrine clays. The need to pre-strip designated areas to reduce the slope height and attain safe digging conditions for the bucket wheel excavator operation is now accepted practice at the open cut mine. In this study, the inherent spatial variability of undrained shear strength of the clay materials has been incorporated in a visco plastic, finite element based, probabilistic slope stability analysis. Data on the costs of initial pre-stripping, excavation and slope failure are collected to provide an economic basis for the optimisation of the design of the overburden batters in Morwell Open Cut. This improved stability modelling is enabling costly pre-stripping to be minimised while ensuring acceptable slope stability conditions and minimising the risk to personnel and plant.

Jan 1, 1994

Australia's gold mining industry has seen a resurgence in the past seven years - a resurgence the likes of which has been seen in very few, if any of this nation's other mineral industries. Industry experts are predicting that Australia could become one of the world's largest gold producers as the future of the South African gold industry looks increasingly tenuous under the present political crisis in that country. Therefore, it is utterly ludicrous for the Federal Government to introduce a tax which will see the Australian gold industry "wither on the vine."The Queensland State Government is utterly opposed to a tax on gold. Anyone in their right mind, who has seen the statistics could only agree with our stance. In 1984/85, activity in the gold mining industry is estimated to have accounted for over $750 million in national income, over$1,200 million in national output, and tax revenue of at least $115 million as well as providing more than 16,000 jobs. Chartered accountants Coopers and Lybrand's survey on the gold industry last year showed an increase in exploration expenditure by gold producers and explorers by up to 36% in 1986 from 1985 levels. That level is expected to be maintained in real terms for most of the remainder of the decade under the present tax arrangements. This is in contrast with the mining sector as a whole, where a recent Australian Mining Industry Council survey forecasted a 14% FALL in production.

Jan 1, 1986

By A Specht, A Müller, V Montenegro, S Winkler, E Klaffenbach, A Schmidt

In the process of primary copper smelting in flash smelting furnace (FSF), the ratio of iron to silica (Fe/SiO2 mass ratio) primarily determines the slag viscosity and magnetite formation. Viscous slag does not only cause difficulties in daily operation, such as in tapping, it also increases the copper losses to slag. Thus, keeping the Fe/SiO2 mass ratio at the desired level is an important aspect of FSF and slag cleaning furnace (SCF) operation. In this study, the improvement of the Fe/SiO2 mass ratio was conducted in two steps: First, the optimal Fe/SiO2 mass ratio was derived based on thermodynamic data. Based on this analysis, appropriate control limits were determined. Second, this range of favourable Fe/SiO2 mass ratios was implemented into operation by an advice-based control system, which suggests the addition of silica based on the analysis of SCF slag. As this approach was successful, the same advice-based control system principle was adapted for the coke addition to the SCF. After testing the new advice-based control for several months, the production data confirm the predictions by thermodynamics: since the prediction was implemented as an advisor, the copper and magnetite content in SCF slag is significantly reduced and viscous slag is reported less often by operations.

Aug 21, 2024

By S H. Algie, D P. Taplin, S G. Doig

"Suboptimal performance of clusters of hydrocyclones (cyclones), relative to the performance of the individual cyclones that comprise the cluster, is a common phenomenon. The primary cause is well known: uneven distribution of the slurry feed into the individual cyclones. The direct result of uneven distribution is that each cyclone in a cluster performs somewhat differently. Hence, some, if not all, of them do not work at their intended operating points, and the classification is not as sharp as intended. The impact on grade, recovery and milling efficiency will vary depending on the duty of the processing circuit, but the most immediately apparent consequence of uneven distribution is a difference in wear rates in the individual cyclones; this exacerbates the problems of unequal performance of the individual cyclones. In severe cases, and as differential wear proceeds, flows from the individual cyclones may become visibly different. Uneven distribution, once the phenomenon was identified, was seen to be a significant issue in the high-solids hydrocyclone cluster in the ball mill recycle section of Evolution Mining’s Edna May Operation (EMO, Westonia, Western Australia) gold processing plant. In 2012, a FloCEP® hydrocyclone feed distributor system was installed to alleviate the problem. Over the next four years of operation, this innovation has proven its value in the metallurgical and maintenance areas. Individual cyclones now wear at the same rate, greatly reducing the need for operator intervention, as well as increasing overall plant availability through minimising unplanned maintenance. The costs of the installation can be justified by savings in maintenance alone, though the greatest value, as is described in this paper, is in allowing the plant to produce consistently closer to its operational design limits. The FloCEP® system is a low maintenance, readily installed retrofit, based on two patented devices that are combined with complementary proprietary design methodology allowing customisation for specific flow rates and slurry particle properties. Together, these devices produce and distribute a pseudo-homogenous slurry flow without moving parts.Citation:Taplin, D P, Doig, S G and Algie, S H, 2016. Experience with FloCEP® Slurry Flow Conditioning at Evolution Mining's Edna May Operation, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 251–260 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By R McCarthy, P Hawke

FerrAus Ltd's Robertson Range and Davidson Creek Projects are located in the Hamersley Province about 100 km east of Newman, Western Australia. Significant iron mineralisation defined by an aggressive exploration program within the Marra Mamba Iron Formation is shallowly north dipping at Davidson Creek, and mainly shallowly east dipping at Robertson Range, forming part of a regional scale anticline with the granitic and greenstone basement of the Sylvania Inlier as its core. With minor exceptions, the stratigraphy is comparable with that seen in the main Hamersley Basin. Granite and greenstone basement rocks of the Sylvania Inlier are unconformably overlain by shales and volcanic rocks of the Fortescue Group. The overlying Hamersley Group is locally represented by interbedded chert, banded iron-formation (BIF) and shales of the Marra Mamba Iron Formation (Nammuldi, MacLeod and Mount Newman Members), and dolomites, cherts, BIF and shales of the Wittenoom Formation. Iron enrichment occurs predominantly in the Mount Newman Member, and to a lesser extent in the West Angela Member of the Wittenoom Formation. Enrichment varies from 20 - 30 m in thickness in elongate bodies up to 3 km in strike length, and generally thins down dip. At Davidson Creek iron mineralisation is a haematite-goethite-ochreous goethite assemblage, while at Robertson Range this assemblage is consistently overprinted by a later, goethitic alteration related to 'hardcap' weathering. Near surface hardcap alteration in both project areas comprises more siliceous, aluminous and vitreous goethite. Initial exploration completed by Rio Tinto Exploration between 1999 and 2001 indicated the potential for about 20 Mt of iron mineralisation at Robertson Range. Since 2005 a detailed exploration program undertaken by Australian Manganese Pty Ltd (a wholly owned subsidiary of FerrAus Ltd) has defined a global indicated and inferred resource totaling 164.4 Mt at 58.6 per cent Fe (ASX: FRS 17 April 2009).

Jan 1, 2009

By Feebrey CA, Duncan RA

The Ebor Volcano in northeastern New South Wales is an eroded example of a central-type intraplate volcanic-intrusive complex. It is of Miocene age (19-20 Ma) and has similarities to other central-type volcanoes in eastern Australia which may represent manifestations of sub-lithospheric hotspot activity. Thick lava flows are exposed around the Great Escarpment and are dominated by a tholeiitic basaltic suite, ranging from ol-tholeiite to qz-tholeiite to icelandite with ages of 19.2-19.6 Ma. On its western edge, the tholeiitic lava suite probably overlies remnants of basanite flows belonging to the Eocene (-48 Ma) Doughboy province, but elsewhere, minor alkaline basaltic lavas may be coeval with the tholeiitic suite. Several felsic bodies were emplaced into the volcano at -19.0-19.2 Ma and include subalkaline and peralkaline types. The Crescent Complex is a Miocene-age, strongly differentiated mafic to felsic intrusion in basement rocks and centrally located in pre-erosion reconstructions of the Ebor Volcano. It is interpreted to be a major feeder for the tholeiitic lavas based on age and composition. Evolution of the dominant tholeiitic suite proceeded from a parental ol-tholeiite magma, through qz-tholeiite, icelandite and small volumes of felsic rocks by fractionation of plagioclase, olivine, clinopyroxene and titanomagnetite, accompanied by enrichment of SiO2, F,FeO/MgO, alkalies and HFSE.

Jan 1, 1995

Major discrepancies between mine estimates and estimates from plant metallurgical balances are a common problem in many gold and base metals mines around the world. Many existing practices are based on practical protocols that often fall short

Jan 1, 1998

By J Player, G Sweby

The material properties and hence performance of saturated alluvial sediments slope can be incorrectly forecast if the water content is not preserved, and materials properties not correctly determined. The occurrence of saturated sediments in the Western Australia (WA) Goldfields, while not common, should be a significant investigation focus. Geotechnical engineers new to the area may be unaware of this and hence the importance of correct testing and determination of the material strength. Application of appropriate analysis to determine stable pit slopes to an acceptable level of risk, is not possible unless the appropriate strength and hydrogeological parameters have been established at the outset. A back analysis is presented of a pit that had extensive slope failures in alluvial clay-rich sediments with discussion on the approach adopted by the original design engineers to assess pit wall stability and consequent poor slope performance. Learnings from a full pit 3D back analysis are presented, with an approach to geotechnical and hydrogeological investigations and analysis for slopes in similar materials.

Jun 22, 2022

Resource developers in Papua New Guinea (PNG) are now, more than ever before, confronted with land-owner related issues that can hinder their corporate objectives.Development of PNG's custom-arily owned land since independence has brought sudden changes with mixed success. Exploitation of mineral resources has had its share of problems, and Highlands Gold Limit-ed's (HGL) endeavours in the central Highlands of PNG are no exception.

Jan 1, 1994

By H R. Phillips

The ventilation and refrigeration design of underground mines is an important aspect, when new or existing mines are considered and places a great responsibility on engineers tasked to do so. The current trend for both local and international underground mines is to extend their search for valuable ore reserves deeper below surface. In South Africa, the predictions are that about 40 kt of actual gold still lies in situ, ready for extraction. As mines extend their search for minerals of economic value deeper and deeper into the earthÆs crust, ventilation and refrigeration aspects of such mines become more prominent than before. The planning and design of the required ventilation and refrigeration within these mines, over their expected lifetime is important including the practical implications of such designs. Technology changes and improvements need to be incorporated into ventilation and refrigeration designs, where possible and advances in this specialised field explored. This paper explores ventilation and refrigeration design aspects within the underground mine sphere. Aspects such as mining depth, virgin rock temperature (VRT), mining methods, and different cooling applications available including ventilation supply are reviewed in design applications. Heat generally becomes a significant aspect to counter in these mines and they are not always necessarily deep mines.

Jan 1, 2005

Plant growth is likely to prove the most suitable and satisfactory material to stabilise and cover quarry faces and worked-out surface mining sites. The careful selection of plant species is of paramount importance to the success of any attempts to re- vegetate these sites. Various tech- niques are recommended and attention is drawn to different factors,which will adversely affect plant growth.

Jan 1, 1976

By Lye GN

Rock mechanics investigations have shown that some major slopes in the Panguna pit would be stable at angles in excess of 500 providing near-surface instability could be controlled. Excavation of final batters at angles between 55¦ and 60¦ is now being carried out using D10 dozers with berms at 45 to 60 m centres. A trial slope with berms at 90 m centres is planned. Shotcreting of weak zones combined with crest reinforcement, with rock anchors and dowels, is used to provide protection against erosion and toppling of the crests. Overall slopes excavated in this way are of the order of 10¦ steeper than slopes obtained by blast and shovel excavation.

Jan 1, 1986

A Modelling Approach Using a Back-Calculated Induction Time to Predict Recoveries in Flotation

Sep 13, 2010