Minerals

2845 KiB

Open AccessArticle

Three Compositional Varieties of Rare-Earth Element Ore: Eudialyte-Group Minerals from the Norra Kärr Alkaline Complex, Southern Sweden

by Axel S.L. Sjöqvist, David H. Cornell, Tom Andersen, Muriel Erambert, Mattias Ek and Magnus Leijd

Minerals 2013, 3(1), 94-120; https://doi.org/10.3390/min3010094 - 20 Mar 2013

Cited by 45 | Viewed by 12580

Abstract

Agpaitic nepheline syenites at the Norra Kärr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra Kärr hosts three compositionally distinct groups of EGM, which are complex zirconosilicates. Analyses of EGM [...] Read more.

Agpaitic nepheline syenites at the Norra Kärr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra Kärr hosts three compositionally distinct groups of EGM, which are complex zirconosilicates. Analyses of EGM by electron beam energy-dispersive (SEM-EDS) and wavelength-dispersive (WDS-EMP) X-ray microanalysis are presented and compared, complemented by whole-rock analyses. The SEM-EDS and WDS-EMP methods produce comparable results for most elements. Considering that most SEM instruments have a user-friendly EDS system, it is a useful tool for reconnaissance work in research and especially in exploration-related studies. The EGM evolved markedly from an initial Fe-rich and REE-poor, but HREE-dominated variety, to an intermediate Fe-Mn and HREE-rich one, and to a final Mn- and LREE-rich variety, which occur in rocks classified as lakarpite and grennaite. Based on the Mn/(Fe+Mn) ratios of the EGM, this trend is interpreted as a result of magmatic evolution. The threefold diversity of EGM presented in this work is much broader than has previously been documented. Full article

(This article belongs to the Special Issue Advances in Economic Minerals)

► Show Figures

Figure 1

2804 KiB

Open AccessArticle

High and Low Temperature Gold Mineralizations in the Fe–Cu–Zn Sulfide Deposits of Corchia Ophiolite, Northern Italian Apennine

by Zaccarini Federica and Giorgio Garuti

Minerals 2013, 3(1), 82-93; https://doi.org/10.3390/min3010082 - 5 Mar 2013

Viewed by 7936

Abstract

Gold has been found in the Cyprus-type volcanogenic massive sulfide ore (VMS) deposits of Corchia ophiolite (Parma province, Italy) in the Cantiere Donnini, Speranza and Pozzo mining sites. At Cantiere Donnini and Speranza, the mineralization occurs at the contact between pillow lava and [...] Read more.

Gold has been found in the Cyprus-type volcanogenic massive sulfide ore (VMS) deposits of Corchia ophiolite (Parma province, Italy) in the Cantiere Donnini, Speranza and Pozzo mining sites. At Cantiere Donnini and Speranza, the mineralization occurs at the contact between pillow lava and sedimentary rocks. The Pozzo mineralization is hosted by a serpentinite. Concentrations of gold up to 3070 ppb have been reported for the Cantiere Donnini and up to 6295 ppb in the Pozzo mine. According to the field relationships, gold composition, mineralogical assemblage and sulfur isotope data, we can conclude that two different types of gold mineralization have been recognized in the Corchia ophiolite: (1) formed at low temperature in submarine environment (Cantiere Donnini and Speranza) and (2) formed at high temperature in the oceanic mantle (Pozzo) by segregation of an immiscible sulfide liquid. Full article

(This article belongs to the Special Issue Advances in Economic Minerals)

► Show Figures

Figure 1

687 KiB

Open AccessArticle

Initial Parallel Arrangement of Extracellular Fibrils Holds a Key for Sheath Frame Construction by Leptothrix sp. Strain OUMS1

by Hiromichi Ishihara, Tomoko Suzuki, Hideki Hashimoto, Hitoshi Kunoh and Jun Takada

Minerals 2013, 3(1), 73-81; https://doi.org/10.3390/min3010073 - 22 Feb 2013

Cited by 10 | Viewed by 6047

Abstract

Early stages of sheath formation by Leptothrix sp. strain OUMS1 and its derivative sheathless mutant grown in media with or without Fe were examined by light and electron microscopy. Results showed that the initial parallel arrangement of fibrils excreted from the cells holds [...] Read more.

Early stages of sheath formation by Leptothrix sp. strain OUMS1 and its derivative sheathless mutant grown in media with or without Fe were examined by light and electron microscopy. Results showed that the initial parallel arrangement of fibrils excreted from the cells holds a key for subsequent construction of the sheath frame and that aqueous-phase Fe interacts with excreted fibrils whether fibrils are parallel-arranged or simply-intermingled. Full article

► Show Figures

Figure 1

1016 KiB

Open AccessArticle

The Safety Journey: Using a Safety Maturity Model for Safety Planning and Assurance in the UK Coal Mining Industry

by Patrick Foster and Stuart Hoult

Minerals 2013, 3(1), 59-72; https://doi.org/10.3390/min3010059 - 18 Feb 2013

Cited by 57 | Viewed by 46227

Abstract

A Safety Maturity Model was developed for use in UK coal mining operations in order to assess the level of compliance and effectiveness with a recently introduced standards based safety management system. The developed model allowed for a “self-assessment” of the maturity to [...] Read more.

A Safety Maturity Model was developed for use in UK coal mining operations in order to assess the level of compliance and effectiveness with a recently introduced standards based safety management system. The developed model allowed for a “self-assessment” of the maturity to be undertaken by teams from the individual sites. Assessments were undertaken at all sites (surface and underground) and in some cases within each site (e.g., underground operations, surface coal preparation plant). Once the level of maturity was established, improvement plans were developed to improve the maturity of individual standards that were weaker than the average and/or improve the maturity as a whole. The model was likened to a journey as there was a strong focus on continual improvement and effectiveness of the standards, rather than pure compliance. The model has been found to be a practical and useful tool by sites as a means of identifying strengths and weaknesses within their systems, and as a means of assurance with the safety management system standards. Full article

(This article belongs to the Special Issue Taking Health and Safety in the Mining Industry into the 21st Century - Innovative solutions to difficult problems)

► Show Figures

Figure 1

414 KiB

Open AccessArticle

A New Direction for Biomining: Extraction of Metals by Reductive Dissolution of Oxidized Ores

by D. Barrie Johnson, Barry M. Grail and Kevin B. Hallberg

Minerals 2013, 3(1), 49-58; https://doi.org/10.3390/min3010049 - 30 Jan 2013

Cited by 68 | Viewed by 14028

Abstract

Biomining, the biotechnology that uses microorganisms to extract metals from ores and concentrates, is currently used exclusively for processing reduced ores and mine wastes. Metals of economic value also occur extensively in oxidized ores, such as nickel laterites. While these are not amenable [...] Read more.

Biomining, the biotechnology that uses microorganisms to extract metals from ores and concentrates, is currently used exclusively for processing reduced ores and mine wastes. Metals of economic value also occur extensively in oxidized ores, such as nickel laterites. While these are not amenable to oxidative dissolution, the ferric iron minerals they contain can, in theory, be disrupted by iron reduction, causing associated metals to be released. We have harnessed the ability of the facultatively anaerobic, acidophilic bacterium Acidithiobacillus ferroooxidans to couple the oxidation of elemental sulphur to the reduction of ferric iron in the goethite fraction of a limonitic nickel ore at 30 °C. Nickel and other metals (Co, Cr and Mn) were effectively solubilised and maintained in solution due to the low pH (1.8) of the leach liquor. The results highlight the potential for the bioprocessing of oxidized, iron-rich ores using an approach that is energy-saving and environmentally-benign compared with metallurgical processes currently applied to the extraction of Ni from lateritic ores. Full article

(This article belongs to the Special Issue Advances in Mineral Processing)

► Show Figures

Figure 1

1690 KiB

Open AccessReview

Towards a Model for Albitite-Type Uranium

by Andy Wilde

Minerals 2013, 3(1), 36-48; https://doi.org/10.3390/min3010036 - 17 Jan 2013

Cited by 35 | Viewed by 9068

Abstract

Albitite-type uranium deposits are widely distributed, usually of low grade (<1% U₃O₈), but are often large and collectively contain over 1 million tonnes of U₃O₈. Uranium is hosted in a wide range of metamorphic lithologies, [...] Read more.

Albitite-type uranium deposits are widely distributed, usually of low grade (<1% U₃O₈), but are often large and collectively contain over 1 million tonnes of U₃O₈. Uranium is hosted in a wide range of metamorphic lithologies, whose only common characteristic is that they have been extensively mylonitised. Ore minerals are disseminated and rarely in megascopic veins, within and adjacent to albitised mylonites. Grain size is uniformly fine, generally less than 50 microns. Scanning electron microscopy reveals that spatial association between uranium and various Ti-bearing phases is common. Gangue minerals include albite, carbonates (calcite and dolomite), and sodic pyroxene and amphibole. The ore rarely contains economic metals apart from uranium, phosphorous at Itataia being an exception. There is widespread evidence of hydrothermal zirconium mobility and hydrothermal zircon and other Zr phases are frequent and in some cases abundant gangue minerals. Positive correlations are noted between uranium and various high field strength elements. The group remains poorly described and understood, but a link to iron-oxide copper-gold (IOCG) deposits and/or carbonatite and/or alkaline magmatism is plausible. Full article

(This article belongs to the Special Issue Advances in Economic Minerals)

► Show Figures

Figure 1

454 KiB

Open AccessArticle

Comparing Health Risks to Load-Haul-Dump Vehicle Operators Exposed to Whole-Body Vibration Using EU Directive 2002/44EC, ISO 2631-1 and ISO 2631-5

by Tammy R. Eger, Aaron M. Kociolek and James P. Dickey

Minerals 2013, 3(1), 16-35; https://doi.org/10.3390/min3010016 - 14 Jan 2013

Cited by 13 | Viewed by 9354

Abstract

The purpose of this study was to evaluate health risks to operators of large and small load-haul-dump (LHD) vehicles exposed to whole-body vibration (WBV), based on criteria established in ISO 2631-1, ISO 2631-5, and EU Directive 2002/44 EC. Studies simultaneously evaluating health risks [...] Read more.

The purpose of this study was to evaluate health risks to operators of large and small load-haul-dump (LHD) vehicles exposed to whole-body vibration (WBV), based on criteria established in ISO 2631-1, ISO 2631-5, and EU Directive 2002/44 EC. Studies simultaneously evaluating health risks based on all three standards are limited. Operator WBV exposure was measured in accordance with ISO 2631-1 using a tri-axial seat pad accelerometer. According to ISO 2631-1, four of the seven large LHD vehicle operators and three of six small LHD vehicle operators were exposed to WBV above the 8-hour vibration dose value (VDV) health guidance caution zone (HGCZ). According to the EU Directive 2002/44/EC criteria one of the seven large LHD vehicle operators and one of the six small LHD vehicle operators were exposed to WBV above the VDV daily exposure limit. However, health risks predicted by ISO 2631-5 criteria only placed one of seven large LHD vehicle operators and one of the six small LHD vehicle operators in the high probability of an adverse health effect category. Thus, the probability of adverse health effects, associated with WBV exposure during LHD vehicle operation, is suggested to be greatest based on the ISO 2631-1 8-hour VDV HGCZ and lowest based on ISO 2631-5 S_ed criterion values. Full article

(This article belongs to the Special Issue Taking Health and Safety in the Mining Industry into the 21st Century - Innovative solutions to difficult problems)

► Show Figures

Figure 1

720 KiB

Open AccessReview

Integrated Approaches for the Study of Real Mineral Flotation Systems

by Andrea Gerson and Tim Napier-Munn

Minerals 2013, 3(1), 1-15; https://doi.org/10.3390/min3010001 - 8 Jan 2013

Cited by 6 | Viewed by 7474

Abstract

It is more common than not, for mineral processing studies to proceed via the examination of model flotation systems with the resulting data often lacking statistical verification. The resultant concentrates and tails may then be subjected to a restricted range of analyses, for [...] Read more.

It is more common than not, for mineral processing studies to proceed via the examination of model flotation systems with the resulting data often lacking statistical verification. The resultant concentrates and tails may then be subjected to a restricted range of analyses, for diagnosis of the flotation behavior variations observed, that themselves bias the outcomes. For instance surface analysis may be undertaken without reference to solution speciation, or liberation may be studied but surface speciation may not be taken into account. We propose an integrated approach whereby firstly the flotation data are vigorously scrutinized and the mineralogy, liberation, surface and solution speciation are examined in parallel to establish a chemical over view of the system. It is proposed that to make progress in the understanding of flotation systems, in terms of the minerals chemistry, that a multi-dimensional analytical approach is utilized and that the focus shifts towards the analysis of real ores and industrial flotation systems. Full article

(This article belongs to the Special Issue Advances in Mineral Processing)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Minerals, Volume 3, Issue 1 (March 2013) – 8 articles , Pages 1-120

Further Information

Guidelines

MDPI Initiatives

Follow MDPI