Change search
Refine search result
1 - 35 of 35
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Ahmed, Hesham
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute (CMRDI), Cairo, Egypt.
    New Trends in The Application of Carbon-Bearing Materials in Blast Furnace Iron-Making2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, no 12, article id 561Article in journal (Refereed)
    Abstract [en]

    The iron and steel industry is still dependent on fossil coking coal. About 70% of the total steel production relies directly on fossil coal and coke inputs. Therefore, steel production contributes by ~7% of the global CO2 emission. The reduction of CO2 emission has been given highest priority by the iron- and steel-making sector due to the commitment of governments to mitigate CO2 emission according to Kyoto protocol. Utilization of auxiliary carbonaceous materials in the blast furnace and other iron-making technologies is one of the most efficient options to reduce the coke consumption and, consequently, the CO2 emission. The present review gives an insight of the trends in the applications of auxiliary carbon-bearing material in iron-making processes. Partial substitution of top charged coke by nut coke, lump charcoal, or carbon composite agglomerates were found to not only decrease the dependency on virgin fossil carbon, but also improve the blast furnace performance and increase the productivity. Partial or complete substitution of pulverized coal by waste plastics or renewable carbon-bearing materials like waste plastics or biomass help in mitigating the CO2 emission due to its high H2 content compared to fossil carbon. Injecting such reactive materials results in improved combustion and reduced coke consumption. Moreover, utilization of integrated steel plant fines and gases becomes necessary to achieve profitability to steel mill operation from both economic and environmental aspects. Recycling of such results in recovering the valuable components and thereby decrease the energy consumption and the need of landfills at the steel plants as well as reduce the consumption of virgin materials and reduce CO2 emission. On the other hand, developed technologies for iron-making rather than blast furnace opens a window and provide a good opportunity to utilize auxiliary carbon-bearing materials that are difficult to utilize in conventional blast furnace iron-making.

  • 2.
    Aiglsperger, Thomas
    et al.
    Department of Crystallography, Mineralogy, and Ore Deposits, University of Barcelona.
    Proenza, Joaquín A.
    Departament de Cristal·lografia, Mineralogia i Dipòsits Minerals, Universitat de Barcelona.
    Longo, Francisco
    Falcondo Glencore, Santo Domingo .
    Font-Bardia, Mercé
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Galí, Salvador
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Roqué, Josep
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona.
    Baurier-Aymat, Sandra
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Universitat de Barcelona .
    Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic2016In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 6, no 4, article id 126Article in journal (Refereed)
    Abstract [en]

    This contribution reports on the observation of enigmatic fibrous platinum-group minerals (PGM) found within a chromitite body included in limonite (“floating chromitite”) from Ni-laterites in the Dominican Republic. Fibrous PGM have a Ru-Os-Ir-Fe dominated composition and are characterized by fibrous textures explained by grain-forming fibers which are significantly longer (1–5 _m) than they are wide (~100 nm). Back-scattered electron (BSE) images suggest that these nanofibers are platinum-group elements (PGE)-bearing and form <5 _m thick layers of bundles which are oriented orthogonal to grains’ surfaces. Trace amounts of Si are most likely associated with PGE-bearing nanofibers. One characteristic fibrous PGM was studied in detail: XRD analyses point to ruthenian hexaferrum. However, the unpolished fibrous PGM shows numerous complex textures on its surface which are suggestive for neoformation processes: (i) features suggesting growth of PGE-bearing nanofibers; (ii) occurrence of PGM nanoparticles within film material (biofilm?) associated with PGE-bearing nanofibers; (iii) a Si-rich and crater-like texture hosting PGM nanoparticles and an Ir-rich accumulation of irregular shape; (iv) complex PGM nanoparticles with ragged morphologies, resembling sponge spicules and (v) oval forms (<1 _m in diameter) with included PGM nanoparticles, similar to those observed in experiments with PGE-reducing bacteria. Fibrous PGM found in the limonite may have formed due to supergene (bio-)weathering of fibrous Mg-silicates which were incorporated into desulphurized laurite during stages of serpentinization.

  • 3.
    Bacsik, Zoltan
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhang, Peng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Ammonium-Carbamate-Rich Organogels for the Preparation of Amorphous Calcium Carbonates2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 7, article id 110Article in journal (Refereed)
    Abstract [en]

    Amine-CO2 chemistry is important for a range of different chemical processes, including carbon dioxide capture. Here, we studied how aspects of this chemistry could be used to prepare calcium carbonates. Chemically crosslinked organogels were first prepared by reacting hyperbranched polyethylene imine (PEI) dissolved in DMSO with carbon dioxide. The crosslinks of the organogel consisted of ammonium-carbamate ion pairs as was shown by IR spectroscopy. These carbamate-rich organogels were subsequently subjected to aqueous solutions of calcium acetate, and amorphous calcium carbonate (ACC) precipitated. The ACC did not crystalize during the mixing for up to 20 h, as was shown by a combination of IR spectroscopy, X-ray diffraction, scanning electron microscopy, and thermal analysis. Some PEI had been included or adsorbed on the ACC particles. Traces of calcite were observed in one sample that had been subjected to water in a work-up procedure.

  • 4.
    Barker, Abigail
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics. Ctr Nat Hazards & Disaster Sci CNDS, Villavagen 16, SE-75236 Uppsala, Sweden.
    Hansteen, Thor H.
    GEOMAR Helmholtz Ctr Ocean Res Kiel, Wischhofstr 1-3, D-24148 Kiel, Germany.
    Nilsson, David
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Unravelling the Crustal Architecture of Cape Verde from the Seamount Xenolith Record2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 2, article id 90Article in journal (Refereed)
    Abstract [en]

    The Cape Verde oceanic plateau hosts 10 islands and 11 seamounts and provides an extensive suite of alkaline lavas and pyroclastic rocks. The volcanic rocks host a range of crustal and mantle xenoliths. These xenoliths provide a spectrum of lithologies available to interact with magma during transport through the lithospheric mantle and crust. We explore the origin and depth of formation of crustal xenoliths to develop a framework of magma-crust interaction and a model for the crustal architecture beneath the Cape Verde oceanic plateau. The host lavas are phononephelinites to phonolites and the crustal xenoliths are mostly mafic plutonic assemblages with one sedimentary xenolith. REE profiles of clinopyroxene in the host lavas are light rare-earth element (LREE) enriched whereas clinopyoxene from the plutonic xenoliths are LREE depleted. Modelling of REE melt compositions indicates the plutonic xenoliths are derived from mid-ocean ridge basalt (MORB)-type ocean crust. Thermobarometry indicates that clinopyroxene in the host lavas formed at depths of 17 to 46 km, whereas those in the xenoliths formed at 5 to 20 km. This places the depth of origin of the plutonic xenoliths in the oceanic crust. Therefore, the xenoliths trace magma-crust interaction to the MORB oceanic crust and overlying sediments located beneath the Cape Verde oceanic plateau.

  • 5.
    Biagioni, Cristian
    et al.
    Università di Pisa, Italy.
    Bindi, Luca
    Università di Firenze, Italy.
    Mauro, Daniela
    Università di Pisa.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Geology.
    Crystal chemistry of sulfates from the Apuan Alps (Tuscany, Italy). V. Scordariite, K8(Fe3+0.67ο0.33)[Fe3+3O(SO4)6(H2O)3)]2(H2O)11 , a new metavoltine-related mineral2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 11, p. 1-14, article id 0702Article in journal (Refereed)
  • 6.
    Dold, Bernhard
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pooler, Robert
    SGS Minerals Chile, Geometallurgy Area, Puerto Madero 130, Pudahuel, Santiago.
    Optimization and quality control of automated quantitative mineralogy analysis for acid rock drainage prediction2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 1, article id 12Article in journal (Refereed)
    Abstract [en]

    Low ore-grade waste samples from the Codelco Andina mine that were analyzed in an environmental and mineralogical test program for acid rock drainage prediction, revealed inconsistencies between the quantitative mineralogical data (QEMSCAN®) and the results of geochemical characterizations by atomic absorption spectroscopy (AAS), LECO® furnace, and sequential extractions). For the QEMSCAN® results, biases were observed in the proportions of pyrite and calcium sulfate minerals detected. An analysis of the results indicated that the problems observed were likely associated with polished section preparation. Therefore, six different sample preparation protocols were tested and evaluated using three samples from the previous study. One of the methods, which involved particle size reduction and transverse section preparation, was identified as having the greatest potential for correcting the errors observed in the mineralogical analyses. Further, the biases in the quantities of calcium sulfate minerals detected were reduced through the use of ethylene glycol as a polishing lubricant. It is recommended that the sample preparation methodology described in this study be used in order to accurately quantify percentages of pyrite and calcium sulfate minerals in environmental mineralogical studies which use automated mineralogical analysis

  • 7.
    Ekman Nilsson, Anna
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Macias Aragones, Marta
    Fundación Corporación Tecnológica de Andalucía, Spain; University of Seville, Spain.
    Arroyo Torralvo, Fatima
    University of Seville, Spain.
    Dunon, Vincent
    ARCHE Consulting, Belgium.
    Angel, Hanna
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    Komnitsas, Konstantinos
    Technical University of Crete, Greece.
    Willquist, Karin
    RISE - Research Institutes of Sweden, Built Environment, Energy and Circular Economy.
    A review of carbon footprint of Cu and Zn production from primary and secondary sources2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 9, p. 168-Article in journal (Refereed)
    Abstract [en]

    Copper (Cu) and zinc (Zn) with their unique propertiesare central for economic growth, quality of life and creation of new jobs. The base-metalproducing sector is, however, under growing public pressure in respect toenergy and water requirements and needs to meet several challenges, includingincreased demand and lower ore grades generally associated with larger resourceuse. The development of technologies for metal production from secondarysources is often motivated by increased sustainability and this paper aims to providefurther insights about one specific aspect of sustainability, namely climatechange. The paper presents a review of carbon footprints (CF) for Cu and Znproduced from primary and secondary raw materials, by analyzing data taken fromscientific literature and the Ecoinvent database. Comparisons are carried outbased on the source of data selected as reference case. In the case of Cu,reduced CF of secondary production is indicated, although there is large datavariation. As for Zn, production of this metal from secondary sources seems to bebeneficial but the number of data and cases to be compared is much smallercompared to Cu. The general variation of data suggests that standardization ofcomparison is needed when assessing the environmental benefits of production inline with the principles of waste valorization, zero waste approach andcircular economy.

  • 8. Gebauer, Denis
    et al.
    Jansson, Kjell
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Oliveberg, Mikael
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Indications that Amorphous Calcium Carbonates Occur in Pathological Mineralisation-A Urinary Stone from a Guinea Pig2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, no 3, article id 84Article in journal (Refereed)
    Abstract [en]

    Calcium carbonate is an abundant biomineral that is of great importance in industrial or geological contexts. In recent years, many studies of the precipitation of CaCO3 have shown that amorphous precursors and intermediates are widespread in the biomineralization processes and can also be exploited in bio-inspired materials chemistry. In this work, the thorough investigation of a urinary stone of a guinea pig suggests that amorphous calcium carbonate (ACC) can play a role in pathological mineralization. Importantly, certain analytical techniques that are often applied in the corresponding analyses are sensitive only to crystalline CaCO3 and can misleadingly exclude the relevance of calcium carbonate during the formation of urinary stones. Our analyses suggest that ACC is the major constituent of the particular stone studied, which possibly precipitated on struvite nuclei. Minor amounts of urea, other stable inorganics, and minor organic inclusions are observed as well.

  • 9.
    Ghosh, Rajib
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Schunnesson, Håkan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gustafson, Anna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Monitoring of Drill System Behavior for Water-Powered in-the-hole (ITH) drilling2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 7, article id 121Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the drilling system and the drilling control is required to correctly interpret rock mass conditions based on monitored drilling data. This paper analyses data from hydraulic in-the-hole (ITH) drills used in LKAB’s Malmberget mine in Sweden. Drill parameters, including penetration rate, percussive pressure, feed pressure, and rotation pressure, are monitored in underground production holes. Calculated parameters, penetration rate variability, rotation pressure variability, and fracturing are included in the analysis to improve the opportunity to predict rock mass conditions. Principal component analysis (PCA) is used to address non-linearity and variable interactions. The results show that the data contain pronounced hole length-dependent trends, both linear and step-wise linear, for most parameters. It is also suggested that monitoring can be an efficient way to optimize target values for drill parameters, as demonstrated for feed force. Finally, principal component analysis can be used to transfer a number of drill parameters into single components with a more straightforward geomechanical meaning

  • 10.
    Greberg, Jenny
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Salama, Abubakary
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gustafson, Anna
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Skawina, Bartlomiej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Alternative Process Flow for Underground Mining Operations: Analysis of Conceptual Transport Methods Using Discrete Event Simulation2016In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 6, no 3, article id 65Article in journal (Refereed)
    Abstract [en]

    As the near surface deposits are being mined out, underground mines will increasingly operate at greater depths. This will increase the challenges related to transporting materials from deeper levels to the surface. For many years, the ore and waste transportation from most deep underground mines has depended on some or all of the following: truck haulage, conveyor belts, shafts, rails, and ore pass systems. In sub-level caving, and where ore passes are used, trains operating on the main lower level transport the ore from ore passes to a crusher, for subsequent hoisting to the surface through the shaft system. In many mines, the use of the ore pass system has led to several problems related to the ore pass availability, causing production disturbances and incurred cost and time for ore pass rehabilitation. These production disturbances have an impact on the mining activities since they increase the operational costs, and lower the mine throughput. A continued dependency on rock mass transportation using ore passes will generate high capital costs for various supporting structures such as rail tracks, shaft extensions, and crushers for every new main level. This study was conducted at an existing underground mine and analyzed the transport of ore from loading areas at the lower levels up to the existing shaft points using trucks without employing ore passes. The results show that, when the costs of extending ore passes to lower levels become too great or ore passes cannot be used for production, haul trucks can be a feasible alternative method for transport of ore and waste up the ramp to the existing crusher located at the previous main level. The use of trucks will avoid installing infrastructure at the next main level and extending the ore passes to lower levels, hence reducing costs.

  • 11.
    Guntoro, Pratama Istiadi
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Ghorbani, Yousef
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Koch, Pierre-Henri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    X-ray Microcomputed Tomography (µCT) for Mineral Characterization: A Review of Data Analysis Methods2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 3, article id 183Article in journal (Refereed)
    Abstract [en]

    The main advantage of X-ray microcomputed tomography (µCT) as a non-destructive imaging tool lies in its ability to analyze the three-dimensional (3D) interior of a sample, therefore eliminating the stereological error exhibited in conventional two-dimensional (2D) image analysis. Coupled with the correct data analysis methods, µCT allows extraction of textural and mineralogical information from ore samples. This study provides a comprehensive overview on the available and potentially useful data analysis methods for processing 3D datasets acquired with laboratory µCT systems. Our study indicates that there is a rapid development of new techniques and algorithms capable of processing µCT datasets, but application of such techniques is often sample-specific. Several methods that have been successfully implemented for other similar materials (soils, aggregates, rocks) were also found to have the potential to be applied in mineral characterization. The main challenge in establishing a µCT system as a mineral characterization tool lies in the computational expenses of processing the large 3D dataset. Additionally, since most of the µCT dataset is based on the attenuation of the minerals, the presence of minerals with similar attenuations limits the capability of µCT in mineral segmentation. Further development on the data processing workflow is needed to accelerate the breakthrough of µCT as an analytical tool in mineral characterization.

  • 12.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Broman, Curt
    Neubeck, Anna
    Drake, Henrik
    Chi Fru, Ernest
    Bengtson, Stefan
    Naden, Jonathan
    Detsi, K
    Whitehouse, Martin
    Exceptional preservation of fungi as H2-bearingfluid inclusions in an early Quaternary paleo-hydrothermal system at Cape Vani,Milos, Greece.2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163XArticle in journal (Refereed)
  • 13.
    Ivarsson, Magnus
    et al.
    Univ Southern Denmark, Denmark;Swedish Museum of Natural History, Sweden.
    Kilias, Stephanos P.
    Univ Athens, Greece.
    Broman, Curt
    Stockholm University, Sweden.
    Neubeck, Anna
    Uppsala University, Sweden.
    Drake, Henrik
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Fru, Ernest Chi
    Cardiff Univ, UK.
    Bengtson, Stefan
    Swedish Museum of Natural History, Sweden.
    Naden, Jonathan
    British Geol Survey, UK.
    Detsi, Kleopatra
    Univ Athens, Greece.
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Sweden.
    Exceptional Preservation of Fungi as H2-Bearing Fluid Inclusions in an Early Quaternary Paleo-Hydrothermal System at Cape Vani, Milos, Greece2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 12, p. 1-33, article id 749Article in journal (Refereed)
    Abstract [en]

    The production of H-2 in hydrothermal systems and subsurface settings is almost exclusively assumed a result of abiotic processes, particularly serpentinization of ultramafic rocks. The origin of H-2 in environments not hosted in ultramafic rocks is, as a rule, unjustifiably linked to abiotic processes. Additionally, multiple microbiological processes among both prokaryotes and eukaryotes are known to involve H-2-production, of which anaerobic fungi have been put forward as a potential source of H-2 in subsurface environments, which is still unconfirmed. Here, we report fungal remains exceptionally preserved as fluid inclusions in hydrothermal quartz from feeder quartz-barite veins from the Cape Vani Fe-Ba-Mn ore on the Greek island of Milos. The inclusions possess filamentous or near-spheroidal morphologies interpreted as remains of fungal hyphae and spores, respectively. They were characterized by microthermometry, Raman spectroscopy, and staining of exposed inclusions with WGA-FITC under fluorescence microscopy. The spheroidal aqueous inclusions interpreted as fungal spores are unique by their coating of Mn-oxide birnessite, and gas phase H-2. A biological origin of the H-2 resulting from anaerobic fungal respiration is suggested. We propose that biologically produced H-2 by micro-eukaryotes is an unrecognized source of H-2 in hydrothermal systems that may support communities of H-2-dependent prokaryotes.

  • 14. Ivarsson, Magnus
    et al.
    Kilias, Stephanos P.
    Broman, Curt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Neubeck, Anna
    Drake, Henrik
    Fru, Ernest Chi
    Bengtson, Stefan
    Naden, Jonathan
    Detsi, Kleopatra
    Whitehouse, Martin J.
    Exceptional Preservation of Fungi as H-2-Bearing Fluid Inclusions in an Early Quaternary Paleo-Hydrothermal System at Cape Vani, Milos, Greece2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 12, article id 749Article in journal (Refereed)
    Abstract [en]

    The production of H-2 in hydrothermal systems and subsurface settings is almost exclusively assumed a result of abiotic processes, particularly serpentinization of ultramafic rocks. The origin of H-2 in environments not hosted in ultramafic rocks is, as a rule, unjustifiably linked to abiotic processes. Additionally, multiple microbiological processes among both prokaryotes and eukaryotes are known to involve H-2-production, of which anaerobic fungi have been put forward as a potential source of H-2 in subsurface environments, which is still unconfirmed. Here, we report fungal remains exceptionally preserved as fluid inclusions in hydrothermal quartz from feeder quartz-barite veins from the Cape Vani Fe-Ba-Mn ore on the Greek island of Milos. The inclusions possess filamentous or near-spheroidal morphologies interpreted as remains of fungal hyphae and spores, respectively. They were characterized by microthermometry, Raman spectroscopy, and staining of exposed inclusions with WGA-FITC under fluorescence microscopy. The spheroidal aqueous inclusions interpreted as fungal spores are unique by their coating of Mn-oxide birnessite, and gas phase H-2. A biological origin of the H-2 resulting from anaerobic fungal respiration is suggested. We propose that biologically produced H-2 by micro-eukaryotes is an unrecognized source of H-2 in hydrothermal systems that may support communities of H-2-dependent prokaryotes.

  • 15.
    Ivarsson, Magnus
    et al.
    Univ Southern Denmark, Dept Biol, Campusvej 55, DK-5230 Odense, Denmark;Swedish Museum Nat Hist, Dept Paleobiol, Box 50007, S-10405 Stockholm, Sweden.
    Kilias, Stephanos P.
    Univ Athens, Fac Geol & Geoenvironm, Dept Econ Geol & Geochem, Athens 15784, Greece.
    Broman, Curt
    Stockholm Univ, Dept Geol Sci, SE-10691 Stockholm, Sweden.
    Neubeck, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Drake, Henrik
    Linnaeus Univ, Dept Biol & Environm Sci, S-39231 Kalmar, Sweden.
    Fru, Ernest Chi
    Cardiff Univ, Sch Earth & Ocean Sci, Inst Geobiol & Geochem, Pk Pl, Cardiff CF10 3AT, Wales.
    Bengtson, Stefan
    Swedish Museum Nat Hist, Dept Paleobiol, Box 50007, S-10405 Stockholm, Sweden.
    Naden, Jonathan
    British Geol Survey, Nottingham NG12 5GG, England.
    Detsi, Kleopatra
    Univ Athens, Fac Geol & Geoenvironm, Dept Econ Geol & Geochem, Athens 15784, Greece.
    Whitehouse, Martin J.
    Swedish Museum Nat Hist, Dept Geosci, Box 50007, SE-10405 Stockholm, Sweden.
    Exceptional Preservation of Fungi as H-2-Bearing Fluid Inclusions in an Early Quaternary Paleo-Hydrothermal System at Cape Vani, Milos, Greece2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 12, article id 749Article in journal (Refereed)
    Abstract [en]

    The production of H-2 in hydrothermal systems and subsurface settings is almost exclusively assumed a result of abiotic processes, particularly serpentinization of ultramafic rocks. The origin of H-2 in environments not hosted in ultramafic rocks is, as a rule, unjustifiably linked to abiotic processes. Additionally, multiple microbiological processes among both prokaryotes and eukaryotes are known to involve H-2-production, of which anaerobic fungi have been put forward as a potential source of H-2 in subsurface environments, which is still unconfirmed. Here, we report fungal remains exceptionally preserved as fluid inclusions in hydrothermal quartz from feeder quartz-barite veins from the Cape Vani Fe-Ba-Mn ore on the Greek island of Milos. The inclusions possess filamentous or near-spheroidal morphologies interpreted as remains of fungal hyphae and spores, respectively. They were characterized by microthermometry, Raman spectroscopy, and staining of exposed inclusions with WGA-FITC under fluorescence microscopy. The spheroidal aqueous inclusions interpreted as fungal spores are unique by their coating of Mn-oxide birnessite, and gas phase H-2. A biological origin of the H-2 resulting from anaerobic fungal respiration is suggested. We propose that biologically produced H-2 by micro-eukaryotes is an unrecognized source of H-2 in hydrothermal systems that may support communities of H-2-dependent prokaryotes.

  • 16.
    Jafari, Mohammad
    et al.
    School of Mining Engineering, University of Tehran, Tehran, Iran.
    Shafaei, Said Zia Aldin
    School of Mining Engineering, University of Tehran, Tehran, Iran.
    Abdollahi, Hadi
    School of Mining Engineering, University of Tehran, Tehran, Iran.
    Gharabaghi, Mahdi
    School of Mining Engineering, University of Tehran, Tehran, Iran.
    Chelgani, Saeed Chehreh
    Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, USA.
    A comparative study on the effect of flotation reagents on growth and iron oxidation activities of Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 1, article id 2Article in journal (Refereed)
    Abstract [en]

    Recently, extraction of metals from different resources using a simple, efficient, and low-cost technique-known as bioleaching-has been widely considered, and has turned out to be an important global technology. Leptospirillum ferrooxidans and Acidithiobacillus (Thiobacillus) ferrooxidans are ubiquitous bacteria in the biomining industry. To date, the effects of commercial flotation reagents on the biooxidation activities of these bacteria have not been thoroughly studied. This investigation, by using various systematic measurement methods, studied the effects of various collectors and frothers (collectors: potassium amylxanthate, potassium isobutyl-xanthate, sodium ethylxanthate, potassium isopropylxanthate, and dithiophosphate; and frothers: pine oil and methyl isobutyl carbinol) on L. ferrooxidans and A. ferrooxidans activities. In general, results indicate that in the presence of these collectors and frothers, L. ferrooxidans is less sensitive than T. ferrooxidans. In addition, the inhibition effect of collectors on both bacteria is recommended in the following order: for the collectors, potassium isobutyl-xanthate > dithiophosphate > sodium ethylxanthate > potassium isobutyl-xanthate > potassium amylxanthate; and for the frothers, methyl isobutyl carbinol > pine oil. These results can be used for the optimization of biometallurgical processes or in the early stage of a process design for selection of flotation reagents.

  • 17.
    Junno, Niina
    et al.
    Univ Helsinki, Dept Geosci & Geog, POB 68, FIN-00014 Helsinki, Finland.
    Koivisto, Emilia
    Univ Helsinki, Dept Geosci & Geog, POB 68, FIN-00014 Helsinki, Finland.
    Kukkonen, Ilmo
    Univ Helsinki, Dept Geosci & Geog, POB 68, FIN-00014 Helsinki, Finland.
    Malehmir, Alireza
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    Montonen, Markku
    Boliden FinnEx Oy, Kevitsantie 730, Petkula 99670, Finland.
    Predicting Missing Seismic Velocity Values Using Self-Organizing Maps to Aid the Interpretation of Seismic Reflection Data from the Kevitsa Ni-Cu-PGE Deposit in Northern Finland2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 9, article id 529Article in journal (Refereed)
    Abstract [en]

    We use self-organizing map (SOM) analysis to predict missing seismic velocity values from other available borehole data. The site of this study is the Kevitsa Ni-Cu-PGE deposit within the mafic-ultramafic Kevitsa intrusion in northern Finland. The site has been the target of extensive seismic reflection surveys, which have revealed a series of reflections beneath the Kevitsa resource area. The interpretation of these reflections has been complicated by disparate borehole data, particularly because of the scarce amount of available sonic borehole logs and the varying practices in logging of borehole lithologies. SOM is an unsupervised data mining method based on vector quantization. In this study, SOM is used to predict missing seismic velocities from other geophysical, geochemical, geological, and geotechnical data. For test boreholes, for which measured seismic velocity logs are also available, the correlation between actual measured and predicted velocities is strong to moderate, depending on the parameters included in the SOM analysis. Predicted reflectivity logs, based on measured densities and predicted velocities, show that some contacts between olivine pyroxenite/olivine websterite-dominant host rocks of the Kevitsa disseminated sulfide mineralization-and metaperidotite-earlier extensively used "lithology" label that essentially describes various degrees of alteration of different olivine pyroxenite variants-are reflective, and thus, alteration can potentially cause reflectivity within the Kevitsa intrusion.

  • 18.
    Kudryavtsev, Daniil
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kutcherov, Vladimir G.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Dubrovinsky, Leonid
    University of Bayreuth (Bayreth's geological institute) .
    Serovaiskii, Aleksandr
    Gubkin University of oil and gas (Moscow).
    High-pressure chemistry of propane2020In: Minerals, ISSN 2075-163X, E-ISSN 2075-163XArticle in journal (Refereed)
    Abstract [en]

    This study is a comprehensive research of the propane's high-pressure and high-pressure high temperature behaviour using diamond-anvill cell technique combined with vibrational spectroscopy. As we have found, propane while being exposed to the high pressures (5-40 GPa) could exhibit three solid-solid phase transitions. With the applyimg of laser heating technique, propane could react with the formation of various hydrocarbon compounds and carbon. At temperatures less than 900 K and in the range of pressures from 3 to 22 GPa propane remains stable.

    The full text will be freely available from 2020-07-22 19:32
  • 19.
    Leiva, Claudio A.
    et al.
    Department of Chemical Engineering, Universidad Católica del Norte, Chile.
    Arcos, Katheryn V.
    Department of Chemical Engineering, Universidad Católica del Norte, Chile.
    Poblete, Diego A.
    Department of Chemical Engineering, Universidad Católica del Norte, Chile.
    Serey, Eduardo A.
    Department of Chemical Engineering, Universidad Católica del Norte, Chile.
    Torres, Cynthia M.
    Department of Metallurgical and Mining Engineering, Universidad Católica del Norte, Chile.
    Ghorbani, Yousef
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Design and Evaluation of an Expert System in a Crushing Plant2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, no 10, article id 469Article in journal (Refereed)
    Abstract [en]

    This document presents a proposal for designing an expert system in the Gabriela Mistral Division’s crushing plant belonging to Codelco (Chile) with the objective of maximizing stacked tonnage, allowing the improvement of operational variables that directly interact with the crushing process. In addition, this study considers the impact that occurs in both the process and operational continuity regarding the standardization of the system. In the first stage, a survey and analysis of historic operation data was carried out, which allowed the definition of benchmarking indicators. Subsequently, both modalities of operation were compared, monitoring processed tonnage and detentions related to operational failures. As a result, significant differences were observed in the performance of the critical line operating with expert control, with a 55% reduction in the detentions referred to operational failures. Added to this is the benefit of low cost and improved quality as the control provides an analysis of the variables in reduced time intervals, which is superior to human control.

  • 20.
    Lenaz, Davide
    et al.
    University of Trieste.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Rigonat, Nicola
    University of Trieste.
    Berger, Julien
    University of Toulouse.
    Following the Amphibolite to Greenschist Metamorphic Path through the Structural Parameters of Spinels from Amsaga (Mauritania)2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, no 1, article id 27Article in journal (Refereed)
  • 21.
    Lishchuk, Viktor
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lund, Cecilia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lamberg, Pertti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Miroshnikova, Elena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Simulation of a Mining Value Chain with a Synthetic Ore Body Model: Iron Ore Example2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, no 11, article id 536Article in journal (Refereed)
    Abstract [en]

    Reconciliation of geological, mining and mineral processing information is a costly and time demanding procedure with high uncertainty due to incomplete information, especially during the early stages of a project, i.e., pre-feasibility, feasibility studies. Lack of information at those project stages can be overcome by applying synthetic data for investigating different scenarios. Generation of the synthetic data requires some minimum sparse knowledge already available from other parts of the mining value chain, i.e., geology, mining, mineral processing. This paper describes how to establish and construct a synthetic testing environment, or “synthetic ore body model” by integrating a synthetic deposit, mine production, constrained by a mine plan, and a simulated beneficiation process. The approach uses quantitative mineralogical data and liberation information for process simulation. The results of geological and process data integration are compared with the real case data of an apatite iron ore. The discussed approach allows for studying the implications in downstream processes caused by changes in upstream parts of the mining value chain. It also opens the possibility of optimising sampling campaigns by investigating different synthetic drilling scenarios including changes to the spacing between synthetic drill holes, composite length, drill hole orientation and assayed parameters.

  • 22.
    Mwanga, Abdul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lamberg, Pertti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Testing of Ore Comminution Behavior in the Geometallurgical Context: A Review2015In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 5, no 2, p. 276-297Article in journal (Refereed)
    Abstract [en]

    Comminution tests are an important element in the proper design of orebeneficiation plants. In the past, test work has been conducted for particular representative reference samples. Within geometallurgy the entire ore body is explored in order to further identify the variation within the resource and to establish spatial geometallurgical domains that show the differential response to mineral processing. Setting up a geometallurgical program for an ore deposit requires extensive test work. Methods for testing the comminution behavior must therefore be more efficient in terms of time and cost but also with respect to sample requirements. The integration of the test method into the geometallurgical modeling framework is also important. This paper provides an overview of standard comminution test methods used for the investigation of ore comminution behavior and evaluates their applicability and potential in the geometallurgical context.

  • 23.
    Mäkitalo, Maria
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Jia, Yu
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Characterization of Green Liquor Dregs, Potentially Useful for Prevention of the Formation of Acid Rock Drainage2014In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 4, no 2, p. 330-344Article in journal (Refereed)
    Abstract [en]

    Using alternative materials such as residual products from other industries to mitigate the negative effects of acid rock drainage would simultaneously solve two environmental problems. The main residual product still landfilled by sulphate paper mills is the alkaline material green liquor dregs (GLD). A physical, mineralogical and chemical characterization of four batches of GLD was carried out to evaluate the potential to use it as a sealing layer in the construction of dry covers on sulphide-bearing mine waste. GLD has relatively low hydraulic conductivity (10−8 to 10−9 m/s), a high water retention capacity (WRC) and small particle size. Whilst the chemical and mineralogical composition varied between the different batches, these variations were not reflected in properties such as hydraulic conductivity and WRC. Due to relatively low trace element concentrations, leaching of contaminants from the GLD is not a concern for the environment. However, GLD is a sticky material, difficult to apply on mine waste deposits and the shear strength is insufficient for engineering applications. Therefore, improving the mechanical properties is necessary. In addition, GLD has a high buffering capacity indicating that it could act as an alkaline barrier. Once engineering technicalities have been overcome, the long-term effectiveness of GLD should be studied, especially the effect of aging and how the sealing layer would be engineered in respect to topography and climatic conditions.

  • 24. Ordóñez, J. I.
    et al.
    Condori, A.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Cisternas, L. A.
    Heap leaching of caliche ore. Modeling of a multicomponent system with particle size distribution2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 10, article id 180Article in journal (Refereed)
    Abstract [en]

    Caliche is a mineral exploited in northern Chile, from which iodine and Nitrate salts (saltpeter) are obtained. This ore is the most important source of iodine in the world and is processed mainly by heap leaching using water as a leaching agent. Heap leaching of caliche ore is carried out by the stacking of ROM (Run-Of-Mine) material, where the particle size distribution covers a wide range, from a few millimeters up to several decimeters, even diameters about 1 m. During the leaching, the multiple soluble species of caliche, which can reach total fractions larger than 40%, are dissolved at different rates, mainly controlled by their solubilities. When it occurs and unlike most other leachable ores, the particle size diminishes. The leaching modeling of several soluble species of caliche has been recently addressed; however, one of the main assumptions is the idealization that the heap is composed of particles of the same size. The present work aims to complement the previously formulated phenomenological models for caliche ore leaching, through a model that considers the simultaneous dissolution of two species from caliche with three different particle sizes. These two water-soluble species have different solubilities and dissolution rates and the conceptual model considers that both species are dissolved at the particle surface. When the most soluble species is being depleted, the particle collapses, leaving a remaining fraction of the less soluble species together with insoluble material. The less soluble species is now being dissolved from the collapsed material. This article also includes the experimental verification of the conceptual model using data obtained from column leaching tests conducted for this purpose, focusing on the dissolution of two soluble species: Nitrate and Magnesium.

  • 25.
    Reinhardt, Nils
    et al.
    Institute of Mineralogy, Technische Universität Bergakademie Freiberg, Germany;Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Spain; Institute of Applied Mineralogy and Economic Geology (IML), RWTH Aachen University, Germany.
    Proenza, Joaquín A.
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Spain.
    Villanova-de-Benavent, Cristina
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Spain;School of Environment and Technology (SET), University of Brighton, UK.
    Aiglsperger, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Spain.
    Bover-Arnal, Telm
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Spain.
    Torró, Lisard
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Spain;Especialidad Ingeniería Geológica, Sección Ingeniería de Minas, Pontificia Universidad Católica del Perú, Peru.
    Salas, Ramon
    Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona (UB), Spain.
    Dziggel, Annika
    Institute of Applied Mineralogy and Economic Geology (IML), RWTH Aachen University, Germany.
    Geochemistry and Mineralogy of Rare Earth Elements (REE) in Bauxitic Ores of the Catalan Coastal Range, NE Spain2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, no 12, article id 562Article in journal (Refereed)
    Abstract [en]

    Karst bauxite deposits are currently investigated as a new resource for rare earth elements (REE) in order to avoid present and future supply shortfalls of these critical metals. The present work focuses on the geochemistry and mineralogy of the REE in karst bauxite deposits of the Catalan Coastal Range (CCR), NE-Spain. It is revealed that the studied bauxitic ores have a dominant breccia and local ooido-pisoidic and pelitomorphic texture. The bauxitic ores are mostly composed of kaolinite and hematite, as well as of lesser amounts of boehmite, diaspore, rutile and calcite. The mineralogy and major element composition indicate incomplete bauxitization of an argillaceous precursor material possibly derived from the erosion of the Mesozoic Ebro massif paleo-high. The studied bauxites are characterized by ∑REE (including Sc, Y) between 286 and 820 ppm (av. 483 ppm) and light REE to heavy REE (LREE/HREE) ratios up to 10.6. REE are mainly concentrated in phosphate minerals, identified as monazite-(Ce) and xenotime-(Y) of detrital origin and unidentified REE-phosphates of a possible authigenic origin. REE remobilization presumably took place under acidic conditions, whereas REE entrapment in the form of precipitation of authigenic rare earth minerals from percolating solutions was related to neutral to slightly alkaline conditions. During the bauxitization process no significant REE fractionation took place and the REE distribution pattern of the bauxitic ores was governed by the REE budget of the precursor material. Finally, adsorption as a main REE scavenging mechanism in the studied CCR bauxite deposits should not be considered, since the presented data did not reveal significant REE contents in Fe-and Mn-oxyhydroxides and clay minerals.

  • 26.
    Serovaiskii, Aleksandr
    et al.
    Gubkin Russian State Univ Oil & Gas, Natl Res Univ, Dept Phys, Leniskiy Ave 65-1, Moscow 119991, Russia..
    Mukhina, Elena
    Skolkovo Inst Sci & Technol, Bolshoy Blvd 30,Bld 1, Moscow 121205, Russia..
    Dubrovinsky, Leonid
    Univ Bayreuth, Bayer Geoinst, Univ Str 30, D-95440 Bayreuth, Germany..
    Chernoutsan, Aleksey
    Gubkin Russian State Univ Oil & Gas, Natl Res Univ, Dept Phys, Leniskiy Ave 65-1, Moscow 119991, Russia..
    Kudriavtcev, Danil
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    McCammon, Catherine
    Univ Bayreuth, Bayer Geoinst, Univ Str 30, D-95440 Bayreuth, Germany..
    Aprilis, Georgios
    Univ Bayreuth, Lab Crystallog, Mat Phys & Technol Extreme Condit, D-95440 Bayreuth, Germany..
    Kupenko, Ilya
    Univ Munster, Inst Mineral Westfalische Wilhelms, Corrensstr 24, D-48149 Munster, Germany..
    Chumakov, Aleksandr
    ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France..
    Hanfland, Michael
    ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France..
    Kutcherov, Vladimir G.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.). Department of Physics, Gubkin Russian State University of Oil and Gas (National Research University), Leniskiy avenue 65/1, Moscow, 119991, Russian Federation.
    Fate of Hydrocarbons in Iron-Bearing Mineral Environments during Subduction2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 11, article id 651Article in journal (Refereed)
    Abstract [en]

    Subducted sediments play a key role in the evolution of the continental crust and upper mantle. As part of the deep carbon cycle, hydrocarbons are accumulated in sediments of subduction zones and could eventually be transported with the slab below the crust, thus affecting processes in the deep Earth's interior. However, the behavior of hydrocarbons during subduction is poorly understood. We experimentally investigated the chemical interaction of model hydrocarbon mixtures or natural oil with ferrous iron-bearing silicates and oxides (representing possible rock-forming materials) at pressure-temperature conditions of the Earth's lower crust and upper mantle (up to 2000(+/- 100) K and 10(+/- 0.2) GPa), and characterized the run products using Raman and Mossbauer spectroscopies and X-ray diffraction. Our results demonstrate that complex hydrocarbons are stable on their own at thermobaric conditions corresponding to depths exceeding 50 km. We also found that chemical reactions between hydrocarbons and ferrous iron-bearing rocks during slab subduction lead to the formation of iron hydride and iron carbide. Iron hydride with relatively low melting temperature may form a liquid with negative buoyancy that could transport reduced iron and hydrogen to greater depths.

  • 27.
    Svartsjaern, Mikael
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Saiang, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Discrete Element Modelling of Footwall Rock Mass Damage Induced by Sub-Level Caving at the Kiirunavaara Mine2017In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 7, no 7, article id 109Article in journal (Refereed)
    Abstract [en]

    The Kiirunavaara mine is one of the largest sub-level-caving (SLC) mines in the worldand has been in underground operation for more than 50 years. The mine has been the focus ofseveral case studies over the years. The previous works have either focused on the caving of thehanging wall, using the footwall as a passive support, or focused on the footwall using the hangingwall to apply a passive load. In this updated study the findings of the previous case studies arecombined to study the interaction between the caving hanging wall, the developing cave rock zoneand the footwall. The geological data for the rock types in the mine area are used to derive upperand lower limits for the geomechanical parameters calibrated for numerical models in the previousstudies. The calibrated parameters are used as inputs to a numerical model constructed usingItasca’s Particle-flow-code (PFC) encompassing a mine-scale 2D section at the mid portion of themine. The model captures the failure locations well in the footwall underground and indicatesdamage development without a coherent large-scale failure. The trend in subsidence data on thehanging wall is adequately simulated but the magnitude of deformation is underestimated. Theinput strength for the hanging wall was lowered to study the impact of hanging wall strength onfootwall damage development. It is shown that when the footwall strength is kept constant, whilelowering the hanging wall strength, the extent of damage and magnitude of displacements in thefootwall increases. From these observations it is argued that the hanging wall and footwall cannotbe studied independently for the Kiirunavaara mine since the cave rock zone significantly affectsthe damage development in both walls.

  • 28.
    Tohry, Arash
    et al.
    Yazd University, Yazd, Iran.
    Dehghan, R.
    Yazd University, Yazd, Iran.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rosenkranz, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rahmani, O.
    Chadormalu Mining and Industrial Company, Yazd, Iran.
    Selective Separation of Hematite by a Synthesized Depressant in Various Scales of Anionic Reverse Flotation2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 2, article id 124Article in journal (Refereed)
    Abstract [en]

    Demand for high-quality iron concentrate is significantly increasing around the world. Thus, the development of the techniques for a selective separation and rejection of typical associated minerals in the iron oxide ores, such as phosphorous minerals (mainly apatite group), is a high priority. Reverse anionic flotation by using sodium silicate (SS) as an iron oxide depressant is one of the techniques for iron ore processing. This investigation is going to present a synthesized reagent “sodium co-silicate (SCS)” for hematite depression through a reverse anionic flotation. The main hypothesis is the selective depression of hematite and, simultaneously, modification of the pulp pH by SCS. Various flotation experiments, including micro-flotation, and batch flotation of laboratory and industrial scales, were conducted in order to compare the depression selectivity of SS versus SCS. Outcomes of flotation tests at the different flotation scales demonstrated that hematite depression by SCS is around 3.3% higher than by SS. Based on flotation experiment outcomes, it was concluded that SCS can modify the pH of the process at ~9.5, and the plant reagents (including NaOH, Na2CO3, and SS gel) can be replaced by just SCS, which can also lead to a higher efficiency in the plant. 

  • 29.
    Torres, Cynthia M.
    et al.
    Departamento de Ingeniería Metalúrgica y Minas, Universidad Católica del Norte, Antofagasta, Chile. Centro Integrado de Pilotaje de Tecnologías Mineras, CIPTEMIN, Antofagasta 124000, Chile..
    Ghorbani, Yousef
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Hernández, Pía C.
    Departamento de Ingeniería Química y Procesos de Minerales, Universidad de Antofagasta,Antofagasta, Chile.
    Justel, Francisca J.
    Departamento de Ingeniería Metalúrgica y Minas, Universidad Católica del Norte, Antofagasta, Chile. Departamento de Ingeniería Química y Procesos de Minerales, Universidad de Antofagasta,Antofagasta, Chile..
    Aravena, Matías I.
    Departamento de Ingeniería Metalúrgica y Minas, Universidad Católica del Norte, Antofagasta, Chile.
    Herreros, Osvaldo O.
    Departamento de Ingeniería en Minas, Universidad de Antofagasta, Antofagasta, Chile.
    Cupric and Chloride Ions: Leaching of Chalcopyrite Concentrate with Low Chloride Concentration Media2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 10, article id 639Article in journal (Refereed)
    Abstract [en]

    In this paper, the effect of the cupric and chloride ions concentrations on copper dissolution from chalcopyrite concentrate was studied in acidified media. Variables included three different concentrations of Cu2+ (0.5, 1.5, and 2.5 g L−1), four different concentrations of Cl (0, 5, 7, and 10 g L−1), two different pH values of 1 and 2, and a constant temperature of 60 °C. Results indicated that addition of Cl to the system improves copper extractions, especially at higher concentrations of Cu2+. Initial copper concentrations in the leaching solution did not significantly affect the copper extraction when Cl was not present. Better copper extractions were obtained at pH 1 as compared with pH 2. As the Cu2+ and Cl concentrations were increased, higher values of redox potential were obtained. According to the formation constants of the chloro-complexes, the predominant species in the Cu2+/Cl system in the studied interval were CuCl+ and Cu2+. Using a model of copper speciation in the experimental range predicted for a single copper concentration with increasing Cl concentration, the Cu2+ concentration decreased significantly while the concentration of the chloro-complex species CuCl+ increased. In the leached residue, evidence of sulfur formation was found using SEM and corroborated by XRD analysis. When chloride is present in the medium, the amounts of copper and iron in the residue decrease, confirming a positive effect of chloride on the extraction of copper from concentrate for the studied conditions.

  • 30.
    Wang, Weixing
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Chen, Liangqin
    Flotation Bubble Delineation Based on Harris Corner Detection and Local Gray Value Minima2015In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 5, no 2, p. 142-163Article in journal (Refereed)
    Abstract [en]

    Froth image segmentation is an important and basic part in an online froth monitoring system in mineral processing. The fast and accurate bubble delineation in a froth image is significant for the subsequent froth surface characterization. This paper proposes a froth image segmentation method combining image classification and image segmentation. In the method, an improved Harris corner detection algorithm is applied to classify froth images first. Then, for each class, the images are segmented by automatically choosing the corresponding parameters for identifying bubble edge points through extracting the local gray value minima. Finally, on the basis of the edge points, the bubbles are delineated by using a number of post-processing functions. Compared with the widely used Watershed algorithm and others for a number of lead zinc froth images in a flotation plant, the new method (algorithm) can alleviate the over-segmentation problem effectively. The experimental results show that the new method can produce good bubble delineation results automatically. In addition, its processing speed can also meet the online measurement requirements.

  • 31.
    Wang, Weixing
    et al.
    KTH. College of Information Engineering, Chang’an University, Xi’an 710064, China.
    Liu, W.
    Lang, F.
    Zhang, G.
    Gao, T.
    Cao, T.
    Wang, F.
    Liu, S.
    Froth image acquisition and enhancement on optical correction and retinex compensation2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, no 3, article id 103Article in journal (Refereed)
    Abstract [en]

    To well monitor and optimize the flotation production, a computer vision and image analysis system is used. In such a system, the first important step is to acquire the froth surface images in high quality. Froth imaging quality is hard to control, and the industrial field noise, froth 3D properties, complex textures, and mixed colors can also cause the flotation image to be difficult to segment and process. To acquire high quality images, a new system for image acquisition of the lead flotation is studied. The system constructs the free-form surface lens based on the non-imaging optics theory, which can improve the optical efficiency of the lens and the uniformity of light sources, and can reduce flare effects. For the compensation, an improved MSR (Multi-Scale Retinex) adaptive image algorithm is proposed to increase the brightness and intensity contrast for small bubbles, and to enhance texture details and froth weak edges by analyzing the Retinex output characteristics of the shaded area and improving the gain function. Under the condition of the optimal parameters, the image acquisition system can obtain uniform illumination and reduce different noises. Experiments show that the new froth image acquisition system increases Signal/Noise by 14%, contrast by 21%, and image segmentation accuracy by 26% in an image. 

  • 32.
    Wanhainen, Christina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nigatu, Wondowossen
    Gunnarn Explorat AB.
    Selby, David
    University of Durham, Department of Earth Science.
    McLeod, Claire L
    University of Houston, Department of Earth & Atmospheric Science.
    Nordin, Roger
    Boliden Mineral AB, Boliden AB.
    Bohlin, Nils-Johan
    Boliden, Division of Process Technology.
    The Distribution, Character, and Rhenium Content of Molybdenite in the Aitik Cu-Au-Ag-(Mo) Deposit and Its Southern Extension in the Northern Norrbotten Ore District, Northern Sweden2014In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 4, no 4, p. 788-814Article in journal (Refereed)
    Abstract [en]

    Molybdenite in the Aitik deposit and its southern extension was studied through mineralogical/chemical analysis and laboratory flotation tests. It is demonstrated that molybdenite varies considerably in grain size, ranging from coarse (>20 m) to very fine (<2 m) and occurs predominantly as single grains in the groundmass of the rocks, as grain aggregates, and intergrown with chalcopyrite and pyrite. The dominating molybdenite-bearing rocks are the mica schists, the quartz-monzodiorite, and the Salmijarvi biotite-amphibole gneiss, the latter containing mostly medium-coarsegrained molybdenite. Later geological features, such as garnet-magnetite-anhydrite-K feldspar alteration and pegmatite dikes appear to be responsible for a significant part of the distribution pattern of molybdenite. Molybdenite grains contain up to 1587 ppm Re, with an average of 211 +/- 10 ppm in Aitik molybdenite and 452 +/- 33 ppm in Salmijarvi molybdenite. The higher Re concentrations are found in molybdenite associated with sericite- and quartz-amphibole-magnetite altered rocks, whereas low Re values occur in rocks in which potassic alteration is prominent. Molybdenite recovery is influenced by the mineralogy of the host rock and the alteration grade; hence both of these factors will have an impact on potential recoveries. The recovery of molybdenite was lower from flotation feeds with significant amounts of Mg-bearing clay-micas.

  • 33.
    Warlo, Mathis
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Wanhainen, Christina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bark, Glenn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Butcher, Alan
    Geological Survey of Finland/Geologian tutkimuskeskus, Espoo, Finland.
    McElroy, Iris
    Boliden AB.
    Brising, Dominique
    Boliden AB.
    Rollinson, Gavyn
    Camborne School of Mines, University of Exeter.
    Automated quantitative mineralogy optimized for simultaneous detection of (precious/critical) rare metals and base metals in a production-focused environment2019In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 9, no 7, article id 440Article in journal (Refereed)
    Abstract [en]

    Automated Scanning Electron Microscopy (ASEM) systems are applied in the mining industry to quantify the mineralogy of the ore feed and products. With society pushing towards sustainable mining, this quantification should be comprehensive and include trace minerals since they are often either deleterious or potential by-products. Systems like QEMSCAN® offer a mode for trace mineral analysis (TMS mode); However, it is unsuitable when all phases require analysis. Here, we investigate the potential of detecting micron-sized trace minerals in fieldscan mode using the QEMSCAN® system with analytical settings in line with the mining industry. For quality comparison, analysis was performed at a mining company and a research institution. This novel approach was done in full collaboration with both parties. Results show that the resolution of trace minerals at or below the scan resolution is difficult and not always reliable due to mixed X-ray signals. However, by modification of the species identification protocol (SIP), quantification is achievable, although verification by SEM-EDS is recommended. As an add-on to routine quantitative analysis focused on major ore minerals, this method can produce quantitative data and information on mineral association for trace minerals of precious and critical metals which may be potential by-products in a mining operation

  • 34.
    Wonyen, Darius G.
    et al.
    University of Liberia, Monrovia, Liberia.
    Kromah, Varney
    University of Liberia, Monrovia, Liberia.
    Gibson, Borbor
    University of Liberia, Monrovia, Liberia.
    Nah, Solomon
    University of Liberia, Monrovia, Liberia.
    Chelgani, Saeed Chehreh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    A Review of Flotation Separation of Mg Carbonates (Dolomite and Magnesite)2018In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 8, article id 354Article in journal (Refereed)
    Abstract [en]

    It is well documented that flotation has high economic viability for the beneficiation of valuable minerals when their main ore bodies contain magnesium (Mg) carbonates such as dolomite and magnesite. Flotation separation of Mg carbonates from their associated valuable minerals (AVMs) presents several challenges, and Mg carbonates have high levels of adverse effects on separation efficiency. These complexities can be attributed to various reasons: Mg carbonates are naturally hydrophilic, soluble, and exhibit similar surface characteristics as their AVMs. This study presents a compilation of various parameters, including zeta potential, pH, particle size, reagents (collectors, depressant, and modifiers), and bio-flotation, which were examined in several investigations into separating Mg carbonates from their AVMs by froth flotation.

  • 35.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Chatwin, Terrence
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Management of sulfide-bearing waste: a challenge for the mining industry2012In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 2, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Oxidation of iron sulfides in waste rock dumps and tailings deposits may result in formation of acid rock drainage (ARD), which often is a challenging problem at mine sites. Therefore, integrating an ARD management plan into the actual mine operations in the early phases of exploration, continuing through the mine life until final closure might be successful and decrease the environmental impact. A thorough characterization of ore and waste should be performed at an early stage. A detailed knowledge of mineralogical composition, chemical composition and physical properties such as grain size, porosity and hydraulic conductivity of the different waste types is necessary for reliable predictions of ARD formation and efficiency of mitigation measures. Different approaches to prevent and mitigate ARD are discussed. Another key element of successfully planning to prevent ARD and to close a mining operation sustainably is to engage the mine stakeholders (regulators, community and government leaders, non-governmental organization (NGOs) and lenders) in helping develop and implement the ARD management plan.

1 - 35 of 35
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf