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This paper presents the water management plan of the Mae Moh Project in the North of Thailand, which includes a large lignite opencast mine and thermal power plants. Lignite production will increase from the present 5.5 million tons per annum to approximately 20 million tons per annum by 1995 when the pit area will be about 20 sq.km. and the depth at over 300 meters. Seven power plants are proposed of which two are under construction. The total capacity to be installed is 2,925 MW. The principles considered for water management are firstly flood protection, including drainage of the mining pit and diversion of the Mae Moh stream away from proposed future mining areas; and secondly, a plan to meet the water requirement of the thermal power plants, while maintaining downstream supplies for irrigation and other purposes. The limited annual run-off of Mae Moh and Mae Chang watershed basins are inadequate for the proposed power plants. A study has been prepared to compare two approaches, namely conveying water from remote watersheds to meet the water requirement of the power plants up to total installed capacity; or by limiting future total generation, at the existing site, to only 2025 MV.

Jan 1, 1988

By Golding D

The Charters Towers goldfield is located in the centre of a Lower to Mid-Palaeozoic igneous complex where schistose, amphibolite-grade metamorphic rocks were intruded by multiple phases of medium grained granodioritic rocks. Several generations of mafic and felsic dykes also occur. Two distinct mylonites cut all but the youngest granitoids. Gold mineralisation occurs in quartz veins located in brittley reactivated mylonite and in sympathetic fissures in the undeformed granitoids. The gold-quartz veins occur in complex, gouge-filled, 2.5m thick zones, with minor sulfides, surrounded by zoned phyllic and propylitic alteration assemblages. Four main vein systems are each restricted to separate granitoids or contain oreshoots near granitoid contacts. No genetic relationship between the granitoids and the vein systems can be documented. The early mylonitic fabrics and the granitoid contacts played an important role in ground preparation and in the localization of oreshoots. Non mylonitized granitoids also served as favourable hosts for many of the lodes. Whole rock values of 180 of the granitoids range between 6.5 and 7.9 per mil. Hydrothermal vein quartzes have 180 values between 12.2 and 15.7 per mil. Mylonite quartzes have values of 8.4 per mil. Variation in 180 values of quartzes is in part related to granitoid host rock type.

Jan 1, 1987

The grade (or value) to volume relationship which constitutes a target orebody is used to show that the concentration of diamonds in an economic deposit may be as low as O.Olg/t. Diamond valuations from an Indonesian deposit demonstrate that the largest 5% of the diamonds in the deposit contributed 25% of the mass of diamonds recovered and 70% of the value from the ore. The need to consider the large stone content and the probability of recovery is used to estimate that the sampling density is required to be as high as 4-10,000ppm for a VLC deposit. This is compared with an acceptable sampling density for a bauxite deposit of 700ppb. A case history of the discovery of a diamond bearing paleo-channel in the Ellendale field in Western Australia illustrates that the sampling task becomes impractical. It requires an excavation in excess of 300,000 bcm of material to prove a 5M hem ore reserve. The conclusion is reached that setting up a small scale mining operation is an appropriate method of proving such an ore reserve and that the Code of Reporting should allow a category of "Mineable Resource" to cover such a situation.

Jan 1, 1990

Flue gases from electrical power station boilers, roasting, metallurgical and chemical plants could be treated by flotation using conventional flotation machines. The flue gases are introduced into the pulp instead of the air. The flotation media is a suspension of Ca(OH)2 or CaCO3 or a solution of NH4OH etc containing Na oleate as collector and frother. The SO2 and dust content of the initial flue gases were experimentally reduced by 100 to 1000 times in one flotation operation. The velocity of the flue gases through flotation machines could reach approximatively 0.4 to 0.5 m/s and more against 1.5 m/s reached in scrubber absorbers used for this purpose, but the quality of purification is expected to be better for flotation, which is essential for the cases of heavy polluted metallurgical and chemical flue gases. For some chemical plants the flue gases flotation media may be different and more suitable as compared to the above mentioned media. The proposed flotation method could be used for separation of dry grinded ores in the form of aerosols, with a realisation of flotation from a closed space (gas bubble in the pulp) onto the interface liquid-air where the particles are attached inside the bubbles.

Jan 1, 1993

Cyanidation tests by bottle agitation were conducted on an oxidized lead-silver ore containing approximately 12% Pb and 500 g/t Ag. Over 60% of the silver was leached when the ore was ground to 100% passing 0.15mm, whereas 50-60% of the silver was leached when the ore was only ground to 100% passing 0.5mm. Slurry handling and dewatering at the fine grind size were very difficult due to the high clay content of the ore, however this problem was greatly reduced at the coar- ser grind size. The silver recovery at the fine grind size was very dependent on cyanide solution strength with stronger cyanide sol- utions (containing more than 0.1% NaCN) re- sulting in lower solution silver contents. This was thought to be due to the precipi- tation of leached silver by zinc, which was also leached from the ore by the higher cyanide levels. There was a critical zinc level in solution of approximately 1000ppm, above which the silver recovery fell markedly. Cyanide and lime consumptions for this ore were high (typically 5 kg/t and 40 kg/t respectively), hence the processing of this particular ore by cyanide leaching is un- economic at current silver prices.

Jan 1, 1987

By B J. Monaghan, R J. Longbottom, D J. Pinson, S J. Chew

Recycling steel plant by-products is a critical issue for achieving both environmental and economic sustainability of integrated steel plants. A key steel plant by-product stream is dust from basic oxygen steelmaking (BOS), which can be recycled back to the BOS vessel as iron units and to aid slag formation. The major limitations for its recycling are zinc and the uncertainty in zinc speciation of the dust. This uncertainty affects the amount of dust recycled and how it interacts with the slag during processing. BOS dust in stockpiles can undergo self-sintering reactions that oxidise the iron-bearing components. As this occurs, zinc (or oxide) may combine with iron oxides to form a zinc-iron spinel solid solution phase. Knowing which zinc-bearing species are present in the BOS dust is a key aspect in understanding and developing an efficient recycling process for the dust. To overcome difficulties associated with phase identification in the BOS dust (both fresh and selfsintered), particularly the magnetite-zinc ferrite spinel solid solution using X-ray diffraction (XRD) / scanning electron microscopy (SEM) / energy dispersive spectroscopy (EDS), high end characterisation tools, transmission electron microscopy (TEM) and Mössbauer spectroscopy, were also used. Such an approach allowed improved phase identification of key zinc- and iron-bearing phases that were not previously resolvable. The zinc in fresh BOS dust was mostly present as extremely fine separate particles of zinc oxide, attached to the iron particles. These extremely fine particles were <10 nm in size. Additionally, a small amount of zinc ferrite was also identified within the sample (most likely contained within a magnetite-zinc ferrite spinel solid solution). However, the zinc in the self-sintered BOS dust, was found to be present entirely in a magnetite-zinc ferrite spinel solid solution. While this spinel phase had been previously identified by XRD, it was not clear that it contained zinc. The Mössbauer results provided definitive evidence of zinc within the spinel phase.

Jun 19, 2024

By S Brunt

A new elution process has been developed for the recovery of gold thiosulfate from ion exchange resins. This is a synergistic system which utilises a base eluent, such as nitrate or trithionate, along with an additive that improves the elution of gold. The use of the additive enables lower eluent concentrations to be adopted, as well as weaker eluents such as chloride. With the chloride + additive system, complete gold elution can be achieved within 12 BV when utilising an eluent flow of 5 BV/h. When the eluent flow is reduced to 2 BV/h, complete elution is achieved within 8 BV. Similar results are obtained when using nitrate or trithionate as the base eluent. A copper pre-elution process has also been developed, whereby the majority of copper can be stripped within 5 BV prior to gold elution. This method is a significant improvement on the ammonia + oxygen pre-elution previously suggested. The development of a new analytical procedure based on ion chromatography with UV detection is also described for the quantification of polythionates in leach solutions and loaded on resins. This enables analysis to be carried out for resin-in- leach type processes where the polythionates are being formed in solution and simultaneously adsorbed onto the resin.

Jan 1, 2007

By Finch JA, Uribe-Salas A

The relationship between the process variables and hydrodynamics of a downflow concurrent column (Jameson cell) was investigated in both two and three-phase systems. Gas holdups from 10 to -60 per cent were obtained at gas rates up to 15 cm/s (STP), liquid (slurry) rates up to 25 cm/s, frother concentrations of 5 and 25 ppm, and slurry density (silica) up to 1.23 g/cm3 ina 3.8 cm diameter, 190 cm high column with a 0.5 cm diameter nozzle. Gas holdup decreases with feed rate and increases with gas rate, reaching a maximum (-60 per cent) at a gas rate to feed rate ratio of about one. Gas holdups were higher with slurry compared to water as feed. Stable operation was difficult to maintain at high gas rates especially with low frother dosage; operation was not possible without some frother. Instability was characterised by loss of pool level or formation of slugs. The slugs could move up or down or remain oscillatory. A quantitative relationship between the variables and gas holdup or onset of instability was not identified. Conductivity and pressure-based techniques were successfully tested on-line for estimation of gas holdup and to judge the state of operation (eg formation of slugs).

Jan 1, 1993

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 A Hocking, S Henderson

Commonwealth of Australia (2016) defines rehabilitation as comprising “the design and construction of landforms as well as the establishment of sustainable ecosystems or alternative vegetation, depending upon the desired post-operational land use”. For open cut coal mines in Queensland and New South Wales, the question of how to apply this intent to pits at mine closure is repeated for hundreds of individual pits. In EISs, closure plans and public discussion, assorted treatments are proposed to rehabilitate pits. While some aspects of final voids have been intensively studied, there is little guidance on how to choose a final void treatment option that delivers the optimal outcome against rehabilitation goals. For example, in the Bowen Basin and Hunter Valley commonly proposed rehabilitation actions include reducing the angles of pit walls; however, with few voids successfully rehabilitated to date there is limited understanding of what different wall slopes will achieve.CITATION:Henderson, S and Hocking, A, 2018. A decision framework for comparison of coal void rehabilitation options, in Proceedings Life-of-Mine 2018, pp 127–130 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By P J. Bangerter, G D. Corder

With the societal desire and drive towards low carbon energy sources, there is a growing awareness of the important role that minerals and metals will play with renewable energy technologies. Copper is an essential metal for technologies that generate energy from renewable sources, in particular for wind and solar photovoltaic energy systems. A recent report (Arrobas et al., 2017) estimated that the median increase in copper demand through to 2050 for wind technologies and for solar photovoltaics would need to be 250% and 300% respectively to meet the goal of a 2&#176;C global temperature increase scenario compared with a 6&#176;C global increase, which is largely an extension of current trends (IEA, 2018). The aim of this extended abstract is to demonstrate with the necessary increase in copper production for renewable energy technologies that sound sustainability performance across the global copper value chain is to the benefit of government, society and industry.CITATION:Corder, G D and Bangerter, P J, 2018. Balancing the benefits and impacts of future copper demand – climate change and arsenic, in Proceedings Life-of-Mine 2018, pp 17–19 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By A Tawadrous, D S. Preece

Cave mining is of interest to the mining community as it offers a chance to extract large, deep orebodies with low operating costs and high production rates. It allows for extracting large low-grade orebodies, which may not have previously been considered for mining. Cave mining is done either top down (ie sublevel caving) or bottom up (ie block/panel caving). Both approaches rely on gravity, stresses and weakness of the rock to fracture and achieve a controlled collapse.Block caving starts at the base of the orebody. It progresses upward and across through continuous collapse of the roof. To achieve this, a critical hydraulic radius must be exceeded. This is accomplished by blasting drawbells, through which the caved ore passes to the production level. An entire level above the drawbells (undercut level) is excavated to help initiate the cave. The undercut level ensures the connection between drawbells and achievement of the required hydraulic radius.Conventionally, drawbells are generated by drilling and blasting several times from the production level as well as the undercut level. Mucking between each shot is required to generate enough void space for the rock to swell. The need for several blasts necessitates some downtime between each blast. Also, the cost of developing and maintaining the undercut level can constitute up to 35 per cent of the cost of mining the panel.A new blasting technique was developed to create the drawbells in a single blast from the production level. The technique ensures the connection of the drawbell to the neighbouring ones, thus, the critical hydraulic radius is reached and propagation of the cave achieved without the need for the undercut level. The technique has the potential to reduce the capital cost of a block caving operation, increase its feasibility and reduce time to reach the ore and consequently the payback period. This paper presents the modelling of a traditional drawbell excavation process, the philosophy of the developed technique, the modelling of that new design and its implementation.CITATION:Tawadrous, A and Preece, D S, 2015. A novel blasting technique to create drawbells and eliminate the undercut level in block cave mining, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 617–624 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By S Szylkarski, D N. Graham

In mining, water management is an operational necessity, requiring planning and detailed engineering, as well as risk assessment. Yet, the hydrology of streams and aquifers typically extends well beyond the boundaries of mine operations and intersect with environmental and social values. Mine managers often plan, design and assess the impact of water management activities (such as dewatering, excess water disposal and flood management) with a mine site or process specific focus. The challenge is that the impacts are spatial, long-term and complex – and may be cumulative across multiple mine sites. Further, there is usually little consideration of the feedbacks and interactions between surface water, groundwater and catchment hydrology. Failure to understand these processes can lead to poor decisions and increased costs. This presentation outlines an approach to simulating integrated hydrology in mining catchments that addresses the shortcomings of traditional modelling techniques.CITATION:Graham, D N and Szylkarski, S, 2016. Simulating integrated hydrology in mining catchments from planning to closure, in Proceedings Life-of-Mine 2016 Conference, pp 101–105 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By Selby J

South Australia&apos;s economic development has relied heavily on the mineral industry. In the late 1840s the rich copper deposits at Kapunda and Burra saved the Colony&apos;s economy when South Australia became a world copper producer. Copper lodes developed at Moonta-Wallaroo during the 1860s brought further prosperity when mining activities at Kapunda and Burra were in decline. In addition to those large mines there were many smaller workings scattered through the Flinders and Mount Lofty Ranges producing copper, gold, silver, lead and zinc. Most of the mines of this period were worked by Cornish immigrants who brought their own technology and mining methods with them. These people have left a cultural legacy unique in Aus- tralia. In this Jubilee 150 year (1986) the Department of Mines and Energy, working in conjunction with the Department of Environment and Planning, is helping to preserve and interpret selected historic mining sites, most of which have been neglected since their closure. This work is designed to draw people&apos;s interest to mining history by providing interpreted sites for them to visit and to demon- strate the importance of the mining industry in South Australia&apos;s cultural and economic develop- Ment.

Jan 1, 1987

By J Heyes, R Getty, M Sanapala

Closure is an inevitable part of the life cycle of every mine. Successful closure outcomes critically depend upon early and ongoing integration of closure planning and mine planning. Early and holistic integration minimises residual risk and maximises opportunity to leave a cost-effective, positive legacy for the company, investors and future land users. Both disciplines are inherently interconnected and aim to maximise ‘value’ via trade-offs. Historically, integration of closure into mine plans has been poorly implemented across the industry. There is still a perception that closure planning only starts as the end of a mine life approaches. This inevitably leads to tension when making business decisions, with progressive closure often being deferred due to short-term drivers and incentives. To create a positive legacy after production has ceased, this tension can be managed by transparently and fully informing business decision-makers, such that the impacts of short-term decisions on long-term closure objectives are understood. BHP recently updated a business-wide standard ‘Our Requirements for Closure and Legacy Management’ designed to strengthen collaboration, education and integration of closure across the entire life cycle of the asset. Concurrently, the ‘Life of Asset’ definition was refined to include the postproduction phase, until closure objectives have been met. This paper discusses the criticality of mine planning integration with closure and how updates to Our Requirements sharpen the focus from transactional to transformational planning. These concepts are applicable to any mining operation aiming to achieve successful closure across the full asset life cycle, from exploration to post-production.

Sep 18, 2023

By C Tapia, B Hay

There is a close relationship between the mining industry, economic growth, and technological and social development. Mining activities benefit all economic agents, but only during a timespan determined by available reserves, primarily driven by internal factors such as production rate, technology and costs, and external factors such as prices determined by the market and taxes and royalties controlled by governments (Gordon and Tilton, 2008; Henckens, 2021; Tapia Cortez et al, 2018). The intense use of Mineral Commodities (MC) needed to maintain the current lifestyle has placed ore depletion as one of the main threats to sustainable economic, social and technological development. However, ore depletion does not only arise due to the finite nature of MC, price fluctuations or technological challenges. It is also triggered by the ‘economic limits of extraction’, determined by the optimisation of financial factors and technical restrictions within the regulatory framework (Henckens, 2021). Most reporting standards – if not all – define ore reserves as ‘the economically mineable part of a Measured and/or Indicated Mineral Resources’ determined by the technical and economic viability of extracting, processing and commercialising MC having the NPV as the fundamental decision – making tool (JORC, 2012; Krzemień et al, 2016). However, is the NVP an ‘economically’ basis index able to capture the complexity of economic phenomena? No, it is not, and it is crucial to define what is economic and financial. Although related, they are different disciplines. Economics studies the behaviour of the different market agents, including human behaviour and policies and explains the factors involved in the scarcity (or surplus) of goods and services. Finance focuses on financial systems and managing funds considering the time, cash available, and risk. It involves banks, loans, investments, and savings and can be considered a small subset of economics (Simon, 1959; Tapia Cortez et al, 2018). Given the economic nature of ore Reserves, endorsed by governments (Figure 1), NPV is an incomplete tool to determine ore Reserves as it limits the problem to simply maximising cash flows instead of optimising the economic benefits for all economic agents. In addition, using the rigid scheme of controlling taxation – unable to adapt to new market or economic conditions and systematically increasing – within the NPV framework only increases the sub-optimisation of ore reserves, mainly due to the systematic taxation rise. Short-term benefits of higher taxes and royalties are unlikely to offset the impacts of reducing exploration and project development in the long-term, which not only boosts ore depletion concerns but also reduces competitiveness, threatening economic and social welfare (Fisher, Cootner and Baily, 1972; Gordon, Bertram and Graedel, 2007; Lilford, 2017; Mardones, Silva and Martínez, 1985; Radetzki, 2009; Rodrik, 1982; Tan, 1987; World Bank, 2000). Holistic methods and collaborative tools, able to dynamically simulate and assess how changes in the technical settings, regulatory framework (taxes and royalties), and financial factors affect the availability of ore reserves and the impact for all economic agents, should be incorporated into the evaluation process to fill the gap.

Aug 2, 2023

By P Hatherly, A Melkumyan, D Wyman

Chemical species distributions in rock sequences can be modelled using Gaussian processes (GPs) to predict the weight percentage between known data points. This method can be improved by dividing the modelled area into regions of different mineralogy. In the context of many iron ore deposits, marker shales give the initial guidance of where these regions may lie. These shales give rise to distinctive peaks in the natural gamma downhole logs, which are conventionally identified by hand. A GP method has been developed to automate this task.Once the appropriate boundary has been located on the basis of shale occurrences, chemical assays from exploration drill holes are used to find the exact boundaries of interest. These boundaries divide the drill hole stratigraphy into regions of different mineralogy, each of which display their own distinct correlations between the main elements and oxides (Fe, SiO2 and Al2O3). Iron ore shows a negative correlation between Fe and Al2O3, but in banded iron formation (BIF) there is a positive correlation between these species. Similarly, SiO2 and Al2O3 have a positive correlation in the shales and ore but a negative correlation in the BIF. Correlations obtained within ore-, BIF- and shale-dominated regions are therefore better than those obtained using the entire log and can be used to improve the results obtained when modelling.

Sep 26, 2011

By Baker G

Chromite was recorded among the rare minerals in the natural beach sand concentrates on the coast of Northern New South Wales by Whitworth(l) in 1931, and the commercial production of zircon and rutile from these beach sands has yielded concentrates of ilmenite with small amounts of chromium. The chromite is a detrimental impurity in the utilisation of the ilmenite, and the difficulties that attend the separation of the small amount of chromite from the ilmunite have raised suggestions from time to time that chromite occurs with ilmenite in composite grains. The absence of such composite grains and the nature of the chromite grains has been indicated by the following mineragraphic examination of magnetic concentrates containing chromite which were prepared by the C.S.I.R. Ore Dressing Laboratory, Melbourne University, from ilmenite concentrates from beach sands at Norrie&apos;s Head, County Rous, New South Wales and Stradbroke Island, Queensland.The magnetic concentrates from each locality are divided into five fractions, and the No. 1 concentrate is the most highly magnetic and the tailing the least magnetic. Chromium assays as determined by the Ore Dressing Laboratory are as follows:-

Jan 1, 1948

By D Reid

Many of the relevant engineering behaviours of tailings are controlled to a large degree by the density of the material. For example, loose tailings are prone to brittle strength loss, while dense tailings are dilative (i.e. gain strength) at large shear strains. The critical state framework has been successfully developed over the past few decades to assess whether in situ conditions are contractive or dilative, and estimate relevant engineering parameters on that basis. Tailings comprising primarily silt-sized particles, when subaqueously deposited, often form a particularly loose state compared to subaerially deposited material of similar index properties. Such subaqueous deposition occurs in the decant pond area, where the tailings typically pluviate in quiescent conditions within a pond of standing water. Silt tailings deposited in such a manner have been observed to be extremely loose in a number of TSF investigations. Of particular concern, the deposited material in such cases appear to be significantly looser than can be reproduced in the laboratory - even using moist tamping, the sample preparation method which can usually produce the loosest samples possible in laboratory conditions. While the loose density of subaqueously deposited silt tailings is clear, in a well-managed upstream-raised TSF the decant pond is usually small and far from the perimeter embankments, however there are a number of examples where the engineering performance of such materials becomes relevant – for example, when historical deposition practices were poor, resulting in subaqueous deposition near the perimeter embankment. This paper outlines the geotechnical characterisation of a number of such subaqueously-deposited zones, compares the in situ state to that achievable in the laboratory, and discusses options for assessing the expected engineering performance of such materials when comparable laboratory tests are unavailable.

Jul 1, 2021

By A Larsson, K Niiranen

The Palaeoproterozoic Leveäniemi iron oxide apatite (IOA) deposit of the so-called Kiruna type is currently mined by Luossavaara-Kiirunavaara AB (publ.), commonly known as LKAB. The mineralogy of iron oxides, ie magnetite, hematite, maghemite, and goethite is more complicated compared to the neighbouring and more famous IOA deposits of Kiirunavaara and Malmberget. Furthermore, the mineral chemistry of the iron oxides in the Leveäniemi deposit is also slightly different. Especially, the information about the deportment of titanium and vanadium in iron oxides and distribution in the deposit is essential since they can have an impact in the steelmaking process. For this study 50 samples were selected from exploration drill cores and investigated by optical microscopy, FE-SEM-EDS and EPMA at LKAB and the Geological Survey of Finland. Investigations revealed that magnetite is the predominant iron oxide mineral with secondary hematite being the second most abundant mineral. Primary hematite, maghemite, and goethite seem to be less abundant. It should be noted, however, that this investigation focused on magnetite which currently is the only mineral with economic value. Vanadium occurs as a substitution element in the crystal lattice of iron oxide minerals in the Leveäniemi deposit and not as discrete stochiometric vanadium minerals. In the investigated samples vanadium concentration in magnetite ranges from 0.12 to 0.32 wt per cent V2O3 with higher concentration in the southern part of the deposit. Contrary, titanium does not substitute for iron in the crystal lattice of magnetite or secondary hematite (less than 0.018 wt per cent TiO2). It either occurs as tiny inclusions of titanium oxide minerals or as exsolution lamellae of ilmenite in magnetite. The spatial distribution for titanium in the deposit, however, remains unknown. Furthermore, results of this study indicate that alteration of primary magnetite to secondary hematite has had no significant effect on the trace element chemistry of these minerals in the Leveäniemi deposit.

Nov 8, 2021