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By W J. Bruckard, M J. Vaisey

Ashton Mining Ltd (Ashton) and Lynas Corporation Ltd (Lynas) have established a joint venture partnership to develop and process rare earth oxides (REOÆs) from the Mt Weld deposit in Western Australia. The deposit is located in a deeply weathered volcanic carbonatite structure that contains approximately two million tonnes of rare earth oxides at an average grade of 20 per cent REO. As part of the 1999/2000 feasibility study currently being undertaken by Ashton and Lynas, an extensive laboratory beneficiation test program was undertaken by CSIRO Minerals on diamond drill core samples from the Mt Weld orebody. The aim was to develop a flowsheet, based primarily on flotation that could be confirmed at pilot plant scale. The target concentrate grade was 52 per cent REO with a REO recovery of at least 35 per cent. Two main ore types, nominated as CZ (limonitic siltstone) and LI (nodular limonitic ironstone) were identified for separate laboratory evaluation. The lower grade LI-type ore overlies the higher grade and more extensive CZ-type ore. The majority of the work was conducted on the CZ ore; only limited testing of the LI ore was undertaken. The latter contains a clay component that will present difficulties in processing due to its poor filtering and settling characteristics. Two processing options for treatment of CZ ore were presented for pilot plant consideration. One (Option 1) includes gravity concentration prior to flotation while the other (Option 2) includes finer grinding and four stages of open circuit cleaning. The benefits of each scheme are discussed in detail. Neither has been fully optimised and the definitive flowsheet is most likely to be a hybrid of the two schemes, incorporating the best features of each. Typical metallurgical results from each scheme were final concentrate grades of 49 per cent REO, 10-16 per cent Fe2O3 and 3.2-4.8 per cent CaO. REO recoveries were above 35 per cent in both cases. Features of the processes developed by CSIRO were the inclusion of a gravity concentration stage prior to flotation, a modified flotation reagent scheme, a change in the method of feed preparation, and incorporation of magnetic separation to upgrade final flotation concentrates. Metallurgical results obtained from flotation tests on LI ore were much poorer than those obtained for CZ ore. The best rougher/scavenger result, with the limited amount of testing so far completed, was an REO grade of 32 per cent with a recovery of 28 per cent. Further work is needed to develop a viable processing route for this ore type.

Jan 1, 2000

By Longworth C. R

This paper descrioes a case history of a coal mine which developed un'tahle roof conditions due to mass sliding of the overburden strata on a claystone band within the coal seam. The sliding is believed to have been initiated by stress relief associated with the removal of overburden alongside the entry portal of the underground workings. Once in motion, the roof block was kept moving by bulking due to roof collapse in the normal underground goafing operations. Control measures in the form of an earth and rockfill buttress against the entry portal and a sequential mining plan to create goaf areas alongside the entry portal have been initiated to attempt to limit movement. The operation has been continually monitored and a gradually decreasing pattern of movement is being re, orded.

Jan 1, 1981

By G Byrne, A Bowden

There is often a difference in opinion about the allocation of risk in the establishment of mine closure bonds or financial assurances. From the State’s perspective, protection is needed to ensure that the broader community is not left with the liability of properly closing a mine in the event of a default by the mine operator. Such a default might occur where an operator decides to abandon a site, perform incomplete rehabilitation, becomes insolvent or claims limited liability. On the other hand, mine operators who can demonstrate a strong financial position plus a record of social and environmental commitment and performance, argue that there should be some recognition of this in setting a bond that is less than the full cost of early closure. They argue that a mine rehabilitation bond based on the full cost of early closure is overly conservative and ignores the actual risk of the operator being in default. This paper examines an approach that incorporates the risk of default into the establishment of mine closure and rehabilitation bonds. CITATION:Bowden, A and Byrne, G, 2018. Mine closure bonds (financial assurances) – the ‘how much?’ conundrum, in Proceedings Life-of-Mine 2018, pp 32–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By A Kite

Frontline leaders play a critical role in the safe and productive operations of Australia’s mining, resources and heavy industries. These leaders set the workplace culture, especially during night shifts and weekends, by providing team direction and encouragement, providing access to resources, fulfilling statutory requirements, enacting and reinforcing risk management systems, setting the standards on shift and acting as the primary conduit of communications between senior leaders and team members.

May 5, 2022

Recent work has shown that, in at least some instances of regional metamorphism, metamorphic diffusion has been restricted to such relatively minute distances (of the order of 1.0 mm and much less), that there is no clear, direct evidence of prograde metamorphic mineral reactions, and that metamorphic equilibrium does not appear to have been attained through even very small domains.A number of stratiform orebodies and their immediate metapelitic environments exhibit very large, seemingly "disequilibrium", assemblages of regional metamorphic index materials. One such, in north-eastern Australia, includes laumontite, prehnite, chamosite, stilpnomelane and related hydrous iron silicates, primary chlorite, sericite-muscovite, epidote, actinolite, biotite, almandine, andradite, metamorphic hornblende and clinopyroxene, scapolite, staurolite and sillimanite, all within a 20 metres length of a single diamond drill core. In this and several related occurrences it appears that metamorphism has involved very small scale in situ transformation of pre-existing materials rather than large-scale diffusion and reaction, and hence that the observed metamorphic minerals have probably been derived directly from precursor materials of sedimentary/diagenetic origin.It is concluded that the fluctuating seafloor interplay between warm, acid, concentrated hydrothermal waters with cold, alkaline, dilute seawater during stratiform ore formation, together with diagenetic processes, leads to the formation of a wide range of clay, chlorite, mixed-layer clay and clay/chlorite, and zeolite precursor materials and hence, later, to the complex assemblages of metamorphic minerals closely associated with some stratiform ores. Commonly included in highly localized assemblages of this kind are various minerals which, in conventional regional metamorphic studies, are generally regarded as indicating widely different grades of metamorphism.

Jan 1, 1982

Anglo American Metallurgical Coal (AAMC) manages five open cut coal mines in Queensland and New South Wales, producing approximately 30 million tonnes per annum. The size and complexity of these mines require efforts by a large and diverse number of personnel to minimise adverse geotechnical events from occurring. To achieve this, the AAMC coal mines in Australia are developing a concept of managing the geotechnical risks associated with open cut coal mines. The overall system utilises a combination of internal training, a management system (operational management systems) and standards, numerical modelling, monitoring, inspections and audits. The development of the standards as well as training and mentoring of exploration personnel, geotechnical engineers, engineering geologists and mining engineers with an interest in the geotechnical aspects of mining, training of the production workforce, mentoring and training of the technical staff create the basis for achieving a pro-active rather than a reactive system. Audits are used to assure that personnel are maintaining the standards and to facilitate cross-mine leanings so that best practices are developed across all sites.

Nov 25, 2010

By Rolfe PR, Ellis BA, Clements RJ

Associated Minerals Consolidated Limited (AMC) is constructing a 112,500 tonne/yr synthetic rutile plant at Narngulu, near Geraldton in Western Australia. Design of the plant is based on the technology developed by AMC and utilised in its two existing plants at Capel in Western Australia. Ilmenite Feedstock for the plant will be sourced from AMC's mine at Eneabba and coal obtained from the Collie deposits. The plant is scheduled to come on stream in the second quarter of calendar 1987. The rationale of the decision to construct the Narngulu plant is examined against the background of the world market for high-Ti02 content feedstocks. Also provided is a detailed description of the plant and an examination of the technology used in process Design.

Jan 1, 1986

By J R. Taylor, J A. Muchan, S M. Pape, B S. Davis

Acid and metalliferous drainage (AMD) is routinely derived from waste rock, tailings, pit wall rock, underground mine voids, heap leach pads, ore stockpiles, concentrate stockpiles and even slag piles. In many jurisdictions, there is an assumption that tailings materials represent the highest AMD risk. This is likely due to their highly sulfidic and ultra-fine grained nature, and the fact that they occur in large tonnage, partially unsaturated deposits. These characteristics are not unreasonably associated with reactive and therefore highly polluting mine waste materials. Interestingly, however, the high sulfide content and highly reactive nature of tailings achieves the rapid consumption of oxygen in tailings pore spaces. This oxygen depletion can limit or halt sulfide oxidation throughout much of the tailings pile. Oxygen can only be resupplied to the tailings via atmospheric exchange at the air-tailings interface. The grain size of most tailings materials limits this resupply to a diffusion related process that only affects the uppermost 100–2000 mm. Hence sulfide oxidation in tailings can be inherently self-limiting. Unfortunately, the same cannot be concluded for waste rock materials.Using a unique site assessment strategy that focuses on quantifying acidity fluxes from various domains at a mine site, it has become increasingly evident that sulfidic waste rock produces the majority (typically 60–80 per cent) of the soluble acid and metalliferous pollution at most active and decommissioned sulfide-bearing mine sites. Whether sulfidic waste rock is disposed in engineered above ground facilities, backfilled into pits or even underground voids, it remains the primary source of pollutants for decades to centuries.Conventional end-dumping waste rock practices result in angle-of-repose pathways for air and water, and these internal fabrics exacerbate sulfide oxidation (ie pollution generation) and discharge from waste rock materials. The primary aim of many cover systems is to retard the access of air and water to these conduits. Recent thinking is that more emphasis needs to be directed at strategic waste rock pile construction practices, and less reliance placed on thin soil cover systems to prevent AMD.Waste rock pile construction approaches that minimise porosity and permeability but raise the retained moisture content and enhance water residence times have the potential to lower sulfide oxidation rates and thereby improve water quality outcomes. For example, innovative base-up, layered and compacted (BULC) waste rock piles have the potential to avoid or minimise the generation of AMD, supersede the need for treatment and facilitate successful closure and relinquishment across the mining sector (Figure 1).CITATION:Taylor, J R, Pape, S M, Davis, B S and Muchan, J A, 2016. Waste rock pile construction to lower closure and relinquishment costs, in Proceedings Life-of-Mine 2016 Conference, pp 97–99 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By P J. Terbrugge

Many ore deposits have considerable vertical extent which is not always known at the time of commencement of mining. In many of these cases, initial mining is by opencast methods, and as ore reserves are proved to greater depths, the pits are often planned to go deeper than had been originally envisaged. In such cases, surface plants and critical underground facilities such as conveyer tunnels, access ramps, ore passes, hoisting shafts and ventilation shafts are often located much closer to the pit rim and the orebody than is desirable for the deeper mining situation. This usually raises the question of the stability of such underground excavations, which may be critical for the viable longer-term mass underground operation of the mine. In this paper the key considerations in the evaluation of the stability of the overall mining environment for ædeepened minesÆ are defined. Aspects which are dealt with are: open pit stability, shaft stability, dilution, mudrushes and airblasts, and selection of mining method. The necessary stability evaluations are put into the appropriate context by considering two case histories. Critical parameters and considerations which need to be addressed during the evaluation of excavation interaction are also discussed.

Jan 1, 2000

Most new engineers in the mining industry do not realise the importance of legal obligations. During investigations the first question you are asked is: Do you have any proof or evidence? The smallest detail in an underground notebook or a diary entry is able to be used as your proof and/or evidence. The importance of a paper trail is often undervalued and overlooked when you first enter the industry. As a new engineer, all too often your legal obligations, including your duty of care are not given enough consideration. Whose job is it to inform you of what your legal obligations are and when do they end? Everyone has legal obligations at every level of the industry, from graduate to mine manager. The level of these responsibilities varies depending on the position that you hold. When you first start in the industry you need to understand what your responsibilities are and how you are expected to discharge them, whether they are memos, databases or senior sign-offs, etc. In order to fulfil your obligations you must first discharge your own obligation, which in turn discharges those of your department and ultimately those of the mine. As a graduate engineer in the mining industry what I have learnt about my own legal obligations has come directly from my own experience, which will form the basis of this paper.

Jan 1, 2007

By S Pontual

The use of spectral data has traditionally been for obtaining mineral information and for mapping out alteration systems. The output from these data is typically in the form of mineral assemblages and data on relative proportions of minerals. However there is much more than just mineral information in the spectral data. Most importantly, the data allow the user to obtain vital information on mineral chemistry for some key alteration minerals. The mineral chemistry data allow the users to evaluate multiple phases of alteration of the same key mineral species, and to assess which phase is related to mineralisation. Mineral indices can be extracted from the spectral data and plotted to represent variations in the chemistry and relative proportions of key mineral phases as downhole, section and three-dimensional (3D) plots. These data can also be compared with the spatial distribution of the mineralisation by integration with geochemical and logging data. Through spatial and statistical evaluation the mineral information obtained using spectral analysis can provide vital information to assist in building alteration models and therefore improve targeting for further drilling and exploration.

Aug 22, 2011

By S Juras

The terms measured resources and proven reserves denote the highest level of estimation confidence in all of the major classification schemes. But what do they really bring to today’s project or mine with respect to production planning and expectations? Initial reserve declaration does not need measured resources, just indicated resources. Economic viability of a project is assessed on total reserves with nary a bonus for the amount of proven reserves. Production plans are based on grade and tonnage goals that may only coincidently correspond to proven reserves. So are the measured and proven categories still relevant? Historically, and almost exclusively in underground mines, companies only allowed mining in areas of proven reserves. Some companies still follow that philosophy. But many others will mine a mixture of probable and proven reserves without hesitation. Also what of the undeveloped project in a new district – what is to be made of their declared measured resources and proven reserves? Measured resources are commonly set either by some type of proximity to data scheme or a matter of ‘feel’ based on the qualified person’s experience. The parameters for reserve conversion focus on the project as a whole and then a portion becomes classified as proven reserves almost solely based on whether the resource category is measured. So should the mining industry continue to use these categories of resource and reserve classification? This paper will present arguments about making these categories once again more relevant. A more disciplined usage of these categories may re-introduce their relevancy in public disclosures of resources and reserves. As well a more consistent usage in operations may lead to increased confidence in managing production targets and costs.

Aug 22, 2011

By Draper J. J, Lang S. C

Regional geological mapping and facies analysis of the Late Devonian to Early Carboniferous Keelbottom Group of the Burdekin Basin have resulted in a depositional model representing six siliciclastic-carbonate facies. The six facies represent alluvial fan, braidplain delta, siliciclastic shoreline, siliciclastic shallow marine, restricted siliciclastic/carbonate shelf, and carbonate shoal depositional environments. These facies are identified in the Star beds which are equated with and included in the Keelbottom Group in this paper. Facies are repeated throughout the Group, as a result of two transgressive-regressive cycles.The first transgression recognised in the Keelbottom Group began in the mid-Famennian, and followed deposition of the Late Devonian Dotswood Group. It was marked by the deposition of Siliciclastic Shoreline facies in the basal Myrtlevale Formation, which was succeeded by Siliciclastic Shallow Marine facies at the peak of the transgression. The return of Siliciclastic Shoreline facies in the upper part of the Myrtlevale Formation marked the onset of the first regression, which resulted in the progradation of Braidplain Delta facies from the northwest of the basin. During the peak of this regression, deposition in the western part of the basin was dominated by Alluvial Fan facies.

Jan 1, 1990

The Mineral Research Centre is located at Perth in the suburb of Waterford, adjacent to Curtin University of Technology and within a Technology Precinct which includes Technology Park. The Centre, constructed by the WA Government at a cost of $16 million and occupied in late-1994, comprises three separate buildings housing the CSIRO Division of Minerals, Curtin University's School of Chemical Engineering and the Mineral Processing Laboratory of the Department of Minerals and Energy. The emphasis on R&D at the Centre is primarily in hydrometallurgy as a result of staff expertise, extensive bench and pilot-scale facilities, track record with the industry and, very importantly, two of the occupiers being partners in the AJ Parker Cooperative Research Centre for Hydrometallurgy. Staff in the Centre have a long involvement with R&D agencies such as AMIRA and MERIWA. The hydrometallurgical focus of the Centre complements that of pyrometallurgy at the GK Williams CRC in Melbourne and the Centre for Mining Technology and Equipment in Brisbane, to ensure that the mineral processing industry in Australia has access to a complete range of expertise and facilities to serve its needs.

Jan 1, 1996

By McOnie A. W, Rutherford PG

A volcanic sequence is described from the Golden Cross Mine, Waihi, New Zealand. The sequence includes seven lithostratigraphic units comprising flow and pyroclastic units of Coromandel Group andesite and dacite and overlying Whitianga Group dacite and rhyolite which is intruded by the Golden Cross dacite porphyry and rhyolite dykes. The sequence is mineralized and is unconformably overlain bv_ two post-mineral units, the lacustnne Waitekauri beds and Omahine Subgroup andesite. Detailed structural analysis of mine data has identified four deformational events (D 1-D4) and related these to the gold-silver mineralizing events. Faulting was coeval with the mineralization and directly controlled the development, localization, style and geometry of the ore shoots. Mineralization developed in competent lithologies where dilation occurred during faulting. The Empire Fault is the master shear which controlled fluid flow. Mineralized veining developed in response to tectonic pulses occurring at slightly different stages as represented by the underground Empire vein complex and the open pit vein array. The mineralizing events culminated with the deposition of barren calcite veins. Post-mineral movement along the Western Boundary fault appears to have offset the ore body.

Jan 1, 1995

Conditional simulation is a branch of geo- statistics which allows the simulation of a mineral deposit so that predictions can be made about the variability of some particular parameter of the deposit. A summary of the general principles, advantages and limitations of conditional simulation is presented together with an example based on coal seam thickness.

Jan 1, 1981

The Antarctic Peninsula consists of accretion complex sedimentary and volcanic rocks, talc-alkaline magmatic are rocks, marginal basin sediments and extension-related alkali basalts, dominantly of Mesozoic to Cenozoic age. Metallic minerals have been recorded at "250 localities but two thirds of these are innocuous occurrences of Fe+Cu accessory minerals. The remaining -70 localities are related to hydrothermal mineralization processes. Metallogenetic associations identified are: vein and breccia-hosted Fe+Cu+Zn+Pb+Mo or Fe+Cu+Mo+Mn, shear-hosted Fe+Cu, volcanogenic Fe+Cu and pegmatite-hosted Fe+Cu+Mo+Mn. Anomalous Au, Ag, As, W and Sb also occur but are not of economic interest. Metallogenic zoning is unproven and genetic models are uncertain, possibly involving volcanogenic, epithermal to hypothermal vein and porphyry-type systems. Substantial field and laboratory studies are required to understand distribution and Genesis.

Jan 1, 1987

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

Nickel-iron sulphide mineralization at Nepean, Western Australia occurs within a small Archaean greenstone outlier in granite south of the main Coolgardie greenstone belt. Individual sulphide ore bodies are situated near the foot- wall contact of simply-differentiated en echelon ultramafic sills that have intruded a sequence of sulphide-bearing metasediments and amphibo- lites. The paper describes a detailed section through the No. 2 ultramafic sill and its associated sulphide ore zone, which gave Metals Exploration N.L. the first significant nickel discovery in the Nepean area in 1968. The sill is variable in thickness up to 30 m along a strike length of 600 m, and is truncated to the north by pegmatite intrusion and pinches out to the south. The body has border zones of pyroxenetic composition, now represented by felted aggregates of chlorite and amphibole, and a central peridotitic core in which olivine and orthopyroxene are concentrated towards the base. Textures within the peridotite are dominated by large lath-shaped olivine grains and their serpentine pseudomorphs, which delineate triangular areas composed of talc, chlorite, and amphibole. Orthopyroxene occurs in large ovoid patches and is often replaced by Talc.

Jan 1, 1973

For too long we, as an industry, have borne the brunt of irrational claims, poor science and even worse, journalism with regards to our affect on the environment. To some of us, the overwhelming media attention on greenhouse warming, the polluting outputs of mineral processing or unthinkable depletion of natural resources has left us embarrassed and more unfortunately has turned bright young people away from a career in the minerals industry.This paper shows the hypocrisy associated with an element of the green movement and dispels some general myths on mining disseminated by radical environmentalists.The fallacy of the greenhouse warming effect will be scrutinised by common sense and the mining industryÆs use of land will be discussed and put in proper perspective.Problems associated with safety and emissions and the means to overcome such are discussed briefly.

Jan 1, 2004