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Minerals, Volume 9, Issue 2 (February 2019)

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Open AccessArticle Selective Separation of Hematite by a Synthesized Depressant in Various Scales of Anionic Reverse Flotation
Minerals 2019, 9(2), 124; https://doi.org/10.3390/min9020124
Received: 24 January 2019 / Revised: 16 February 2019 / Accepted: 18 February 2019 / Published: 20 February 2019
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Abstract
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. [...] Read more.
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. Full article
(This article belongs to the Special Issue Flotation Reagents)
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Open AccessArticle Uraninite, Coffinite and Ningyoite from Vein-Type Uranium Deposits of the Bohemian Massif (Central European Variscan Belt)
Minerals 2019, 9(2), 123; https://doi.org/10.3390/min9020123
Received: 26 November 2018 / Revised: 12 February 2019 / Accepted: 15 February 2019 / Published: 19 February 2019
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Abstract
Uraninite-coffinite vein-type mineralisation with significant predominance of uraninite over coffinite occurs in the Příbram, Jáchymov and Horní Slavkov ore districts and the Potůčky, Zálesí and Předbořice uranium deposits. These uranium deposits are hosted by faults that are mostly developed in low- to high-grade [...] Read more.
Uraninite-coffinite vein-type mineralisation with significant predominance of uraninite over coffinite occurs in the Příbram, Jáchymov and Horní Slavkov ore districts and the Potůčky, Zálesí and Předbořice uranium deposits. These uranium deposits are hosted by faults that are mostly developed in low- to high-grade metamorphic rocks of the basement of the Bohemian Massif. Textural features and the chemical composition of uraninite, coffinite and ningyoite were studied using an electron microprobe. Collomorphic uraninite was the only primary uranium mineral in all deposits studied. The uraninites contained variable and elevated concentrations of PbO (1.5 wt %–5.4 wt %), CaO (0.7 wt %–8.3 wt %), and SiO2 (up to 10.0 wt %), whereas the contents of Th, Zr, REE and Y were usually below the detection limits of the electron microprobe. Coffinite usually forms by gradual coffinitization of uraninite in ore deposits and the concentration of CaO was lower than that in uraninites, varying from 0.6 wt % to 6.5 wt %. Coffinite from the Jáchymov ore district was partly enriched in Zr (up to 3.3 wt % ZrO2) and Y (up to 5.5 wt % Y2O3), and from the Potůčky uranium deposit, was distinctly enriched in P (up to 8.8 wt % P2O5), occurring in association with ningyoite. The chemical composition of ningyoite was similar to that from type locality; however, ningyoite from Potůčky was distinctly enriched in REE, containing up to 22.3 wt % REE2O3. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Uranium Deposits)
Open AccessArticle Mineral Mapping and Vein Detection in Hyperspectral Drill-Core Scans: Application to Porphyry-Type Mineralization
Minerals 2019, 9(2), 122; https://doi.org/10.3390/min9020122
Received: 23 January 2019 / Revised: 12 February 2019 / Accepted: 16 February 2019 / Published: 19 February 2019
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Abstract
The rapid mapping and characterization of specific porphyry vein types in geological samples represent a challenge for the mineral exploration and mining industry. In this paper, a methodology to integrate mineralogical and structural data extracted from hyperspectral drill-core scans is proposed. The workflow [...] Read more.
The rapid mapping and characterization of specific porphyry vein types in geological samples represent a challenge for the mineral exploration and mining industry. In this paper, a methodology to integrate mineralogical and structural data extracted from hyperspectral drill-core scans is proposed. The workflow allows for the identification of vein types based on minerals having significant absorption features in the short-wave infrared. The method not only targets alteration halos of known compositions but also allows for the identification of any vein-like structure. The results consist of vein distribution maps, quantified vein abundances, and their azimuths. Three drill-cores from the Bolcana porphyry system hosting veins of variable density, composition, orientation, and thickness are analysed for this purpose. The results are validated using high-resolution scanning electron microscopy-based mineral mapping techniques. We demonstrate that the use of hyperspectral scanning allows for faster, non-invasive and more efficient drill-core mapping, providing a useful tool for complementing core-logging performed by on-site geologists. Full article
(This article belongs to the Special Issue Hyperspectral Imaging for Mineral Mapping)
Open AccessArticle FTIR-Based Crystallinity Assessment of Aragonite–Calcite Mixtures in Archaeological Lime Binders Altered by Diagenesis
Minerals 2019, 9(2), 121; https://doi.org/10.3390/min9020121
Received: 10 January 2019 / Revised: 13 February 2019 / Accepted: 15 February 2019 / Published: 18 February 2019
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Abstract
Lime plaster and mortar are pyrotechnological materials that have been employed in constructions since prehistoric times. They may nucleate as calcite and/or aragonite under different environmental settings. In nature, aragonite and calcite form through biogenic and geogenic processes that lead to different degrees [...] Read more.
Lime plaster and mortar are pyrotechnological materials that have been employed in constructions since prehistoric times. They may nucleate as calcite and/or aragonite under different environmental settings. In nature, aragonite and calcite form through biogenic and geogenic processes that lead to different degrees of atomic order. The latter is a result of defects in the crystal lattice, which affect the properties of crystals, including their interaction with infrared light. Using Fourier transform infrared spectrometry (FTIR) with the KBr pellet method, it is possible to exploit these differences and assess the degree of atomic order of aragonite and calcite crystals and thus their mechanisms of formation. Here we use FTIR to characterize the degree of short-range atomic order of a pyrogenic form of aragonite recently observed in experimental and archaeological lime binders. We show that pyrogenic aragonite has a unique signature that allows its identification in archaeological sediments and lime binders of unknown origin. Based on these results, we developed a new FTIR-based method to assess the integrity and degree of preservation of aragonite and calcite when they occur together in the same material. This method allowed a better assessment of the diagenetic history of an archaeological plaster and finds application in the characterization of present-day conservation materials, such as lime plaster and mortar, where different polymorphs may nucleate and undergo recrystallization processes that can alter the mechanical properties of binders. Full article
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Open AccessArticle Mineralogical Evidence for Partial Melting and Melt-Rock Interaction Processes in the Mantle Peridotites of Edessa Ophiolite (North Greece)
Minerals 2019, 9(2), 120; https://doi.org/10.3390/min9020120
Received: 10 December 2018 / Revised: 13 February 2019 / Accepted: 14 February 2019 / Published: 17 February 2019
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Abstract
The Edessa ophiolite complex of northern Greece consists of remnants of oceanic lithosphere emplaced during the Upper Jurassic-Lower Cretaceous onto the Palaeozoic-Mesozoic continental margin of Eurasia. This study presents new data on mineral compositions of mantle peridotites from this ophiolite, especially serpentinised harzburgite [...] Read more.
The Edessa ophiolite complex of northern Greece consists of remnants of oceanic lithosphere emplaced during the Upper Jurassic-Lower Cretaceous onto the Palaeozoic-Mesozoic continental margin of Eurasia. This study presents new data on mineral compositions of mantle peridotites from this ophiolite, especially serpentinised harzburgite and minor lherzolite. Lherzolite formed by low to moderate degrees of partial melting and subsequent melt-rock reaction in an oceanic spreading setting. On the other hand, refractory harzburgite formed by high degrees of partial melting in a supra-subduction zone (SSZ) setting. These SSZ mantle peridotites contain Cr-rich spinel residual after partial melting of more fertile (abyssal) lherzolite with Al-rich spinel. Chromite with Cr# > 60 in harzburgite resulted from chemical modification of residual Cr-spinel and, along with the presence of euhedral chromite, is indicative of late melt-peridotite interaction in the mantle wedge. Mineral compositions suggest that the Edessa oceanic mantle evolved from a typical mid-ocean ridge (MOR) oceanic basin to the mantle wedge of a SSZ. This scenario explains the higher degrees of partial melting recorded in harzburgite, as well as the overprint of primary mineralogical characteristics in the Edessa peridotites. Full article
(This article belongs to the Special Issue Mineralogy, Petrology and Geochemistry of Ophiolitic Complexes)
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Open AccessArticle Cleaner Extraction of Lead from Complex Lead-Containing Wastes by Reductive Sulfur-Fixing Smelting with Low SO2 Emission
Minerals 2019, 9(2), 119; https://doi.org/10.3390/min9020119
Received: 31 December 2018 / Revised: 4 February 2019 / Accepted: 7 February 2019 / Published: 17 February 2019
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Abstract
A novel and cleaner process for lead and silver recycling from multiple lead-containing wastes, e.g., lead ash, lead sludge, lead slag, and ferric sludge, by reductive sulfur-fixing smelting was proposed. In this process, coke and iron-containing wastes were employed as reductive agent and [...] Read more.
A novel and cleaner process for lead and silver recycling from multiple lead-containing wastes, e.g., lead ash, lead sludge, lead slag, and ferric sludge, by reductive sulfur-fixing smelting was proposed. In this process, coke and iron-containing wastes were employed as reductive agent and sulfur-fixing agent, respectively. A Na2CO3-Na2SO4 mixture was added as flux. The feasibility of this process was detected from thermodynamic and experimental perspectives. The influence of Fe/SiO2 and CaO/SiO2, composition of the molten salt, coke addition, smelting temperature, and smelting time on direct Pb recovery and sulfur-fixation efficiency were investigated. The optimal process conditions were determined as follows: WCoke = 15% WPb wastes, W Na 2 CO 3 / W Na 2 SO 4 = 0.7/0.3, Fe/SiO2 = 1.10, CaO/SiO2 = 0.30, smelting temperature 1200 °C, and smelting time 2 h, where W represents weight. Under these optimum conditions, 92.4% Pb and 98.8% Ag were directly recovered in crude lead bullion in one step treatment, and total 98.6% sulfur was fixed. The generation and emissions of SO2 can be avoided. The main phases in ferrous matte obtained were FeS, NaFeS2, Fe2Zn3S5, and a little entrained Pb. The slag was a FeO-SiO2-CaO-Na2O quaternary melt. Full article
(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)
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Open AccessArticle Investigation of Copper Recovery from a New Copper Deposit (Nussir) in Northern-Norway: Thionocarbamates and Xanthate-Thionocarbamate Blend as Collectors
Minerals 2019, 9(2), 118; https://doi.org/10.3390/min9020118
Received: 18 January 2019 / Revised: 13 February 2019 / Accepted: 14 February 2019 / Published: 16 February 2019
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Abstract
Norway has newly seen an upsurge of interest in exploiting its mineral deposits influenced by fresh Government focus and survey support for previously under-prospected areas. One of the major areas of interest is a huge copper deposit, operated by Nussir ASA, located in [...] Read more.
Norway has newly seen an upsurge of interest in exploiting its mineral deposits influenced by fresh Government focus and survey support for previously under-prospected areas. One of the major areas of interest is a huge copper deposit, operated by Nussir ASA, located in the Repparfjord tectonic window in the Caledonides of west Finnmark. The latest mineral resource estimation is from July 2014, which states that Nussir consists of 5.8 million tonnes of indicated resources and 60.2 million tonnes of inferred resources, giving 66 million tonnes of copper ore. This paper represents the first study on processing characteristics of this ore to date. Our parallel studies using xanthates and dithiophosphates as collectors for Nussir ore flotation examined the grade and recovery of copper, silver, gold, and platinum group (PGM) minerals. Therefore, in this subsequent study, a chelating agent n-Butoxycarbonyl-O-n-butyl thionocarbamate (BBT) is used as a collector and it was found that the recovery and grades of the economically interesting minerals are improved at as low as 2 × 10−5 M collector concentration. Zeta potential, Hallimond flotation and adsorption studies were initially performed in order to assess the selective interaction of BBT and its blend with SIBX (Sodium Isobutyl xanthate) on the three copper minerals of the ore. The bench scale flotation experiments were performed using mixtures of xanthate and thionocarbamate collectors of the Nussir ore and both the resulting copper recovery and grade employing these collector mixtures is observed to be 2–8% superior to the use of a single collector system. Additionally, the current study revealed that the metallurgical results are strongly influenced by the ratio of the collectors in the mixture and particularly the sequence of the collector addition. Full article
(This article belongs to the Section Mineral Processing and Metallurgy)
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Open AccessArticle From Early Contraction to Post-Folding Fluid Evolution in the Frontal Part of the Bóixols Thrust Sheet (Southern Pyrenees) as Revealed by the Texture and Geochemistry of Calcite Cements
Minerals 2019, 9(2), 117; https://doi.org/10.3390/min9020117
Received: 28 December 2018 / Revised: 7 February 2019 / Accepted: 14 February 2019 / Published: 16 February 2019
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Abstract
Structural, petrological and geochemical (δ13C, δ18O, clumped isotopes, 87Sr/86Sr and ICP-MS) analyses of fracture-related calcite cements and host rocks are used to establish a fluid-flow evolution model for the frontal part of the Bóixols thrust sheet [...] Read more.
Structural, petrological and geochemical (δ13C, δ18O, clumped isotopes, 87Sr/86Sr and ICP-MS) analyses of fracture-related calcite cements and host rocks are used to establish a fluid-flow evolution model for the frontal part of the Bóixols thrust sheet (Southern Pyrenees). Five fracture events associated with the growth of the thrust-related Bóixols anticline and Coll de Nargó syncline during the Alpine orogeny are distinguished. These fractures were cemented with four generations of calcite cements, revealing that such structures allowed the migration of different marine and meteoric fluids through time. During the early contraction stage, Lower Cretaceous seawater circulated and precipitated calcite cement Cc1, whereas during the main folding stage, the system opened to meteoric waters, which mixed with the connate seawater and precipitated calcite cement Cc2. Afterwards, during the post-folding stages, connate evaporated marine fluids circulated through newly formed NW-SE and NE-SW conjugate fractures and later through strike-slip faults and precipitated calcite cements Cc3 and Cc4. The overall paragenetic sequence reveals the progressive dewatering of Cretaceous marine host sediments during progressive burial, deformation and fold tightening and the input of meteoric waters only during the main folding stage. This study illustrates the changes of fracture systems and the associated fluid-flow regimes during the evolution of fault-associated folds during orogenic growth. Full article
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Open AccessArticle Influential Factors in Transportation and Mechanical Properties of Aeolian Sand-Based Cemented Filling Material
Minerals 2019, 9(2), 116; https://doi.org/10.3390/min9020116
Received: 24 January 2019 / Revised: 12 February 2019 / Accepted: 13 February 2019 / Published: 16 February 2019
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Abstract
Given that normal filling technology generally cannot be used for mining in the western part of China, as it has only a few sources for filling gangue, the feasibility of instead using cemented filling materials with aeolian sand as the aggregate is discussed [...] Read more.
Given that normal filling technology generally cannot be used for mining in the western part of China, as it has only a few sources for filling gangue, the feasibility of instead using cemented filling materials with aeolian sand as the aggregate is discussed in this study. We used laboratory tests to study how the fly ash (FA) content, cement content, lime–slag (LS) content, and concentration influence the transportation and mechanical properties of aeolian-sand-based cemented filling material. The internal microstructures and distributions of the elements in filled objects for curing times of 3 and 7 days are analyzed using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The experimental results show that: (i) the bleeding rate and slump of the filling-material slurry decrease gradually as the fly ash content, cement content, lime–slag content, and concentration increase, (ii) while the mechanical properties of the filled object increase. The optimal proportions for the aeolian sand-based cemented filling material include a concentration of 76%, a fly ash content of 47.5%, a cement content of 12.5%, a lime–slag content of 5%, and an aeolian sand content of 35%. The SEM observations show that the needle/rod-like ettringite (AFt) and amorphous and flocculent tobermorite (C-S-H) gel are the main early hydration products of a filled object with the above specific proportions. After increasing the curing time from 3 to 7 days, the AFt content decreases gradually, while the C-S-H content and the compactness increase. Full article
(This article belongs to the Special Issue Backfilling Materials for Underground Mining)
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Open AccessArticle Geostatistical Estimation of Multi-Domain Deposits with Transitional Boundaries: A Sensitivity Study for the Sechahun Iron Mine
Minerals 2019, 9(2), 115; https://doi.org/10.3390/min9020115
Received: 14 January 2019 / Revised: 8 February 2019 / Accepted: 12 February 2019 / Published: 16 February 2019
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Abstract
In mineral resource estimation, identification of the geological domains to be used for modeling, and the type of boundaries dividing them, is a major concern. Generally, the variables within a domain are estimated with an assumption of the hard boundaries (sharp contact). However, [...] Read more.
In mineral resource estimation, identification of the geological domains to be used for modeling, and the type of boundaries dividing them, is a major concern. Generally, the variables within a domain are estimated with an assumption of the hard boundaries (sharp contact). However, in many cases, the geologic structures that generate a deposit are transitional (overlapping of several geologic domains). Consequently, boundary identification of the geological domains is essential for an accurate estimate of resources. This paper considers a real application to examine whether the addition of geologic information benefits grade estimation in the presence of transitional boundaries. Results proved that the accuracy of the grade estimation can be improved by adding geological information and there is a significant sensitivity in grade estimation results in the existence of transitional boundaries. Full article
(This article belongs to the Section Mineral Deposits)
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Open AccessArticle A pXRF In Situ Study of 16th–17th Century Fresco Paints from Sviyazhsk (Tatarstan Republic, Russian Federation)
Minerals 2019, 9(2), 114; https://doi.org/10.3390/min9020114
Received: 13 December 2018 / Revised: 10 February 2019 / Accepted: 13 February 2019 / Published: 15 February 2019
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Abstract
Twenty frescoes from “The Assumption” Cathedral located in the island town of Sviyazhsk (Tatarstan Republic, Russian Federation)—dated back to the times of Tsar Ivan IV “the Terrible”—were chemically analyzed in situ with a portable X-ray fluorescence (pXRF) spectrometer. The investigation focused on identifying [...] Read more.
Twenty frescoes from “The Assumption” Cathedral located in the island town of Sviyazhsk (Tatarstan Republic, Russian Federation)—dated back to the times of Tsar Ivan IV “the Terrible”—were chemically analyzed in situ with a portable X-ray fluorescence (pXRF) spectrometer. The investigation focused on identifying the pigments and their combinations in the paint recipes. One hundred ninety-three micropoints randomly chosen from the white, yellow, orange, pink, brown, red, grey, black, green, and blue areas were measured for major and minor elements. The compositional types separated within each color indicate different recipes. The statistical processing of the data unveiled the most important oxides (CaO, MgO, Fe2O3, PbO, SO3, Sb2O3, Al2O3, SiO2, and P2O5) and their relationships. The results allowed to infer the mineral composition of the paints, and, hence, the recipes used by the Russian artisans. Slaked lime and slaked dolomitic lime mixed with variable amounts of “antimony white” and “bone white” were used for white, pink, yellow, and orange paints and for preparing a basic batch for all other colors. Mostly yellow ochre, red ochre, and lead minerals, and occasionally blue ochre, green earth, realgar, orpiment, bone black, galena, stibnite, and magnetite were the pigments involved in various amounts in preparing the paints. Full article
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Open AccessCommentary Breaking Preconceptions: Thin Section Petrography For Ceramic Glaze Microstructures
Minerals 2019, 9(2), 113; https://doi.org/10.3390/min9020113
Received: 16 December 2018 / Revised: 1 February 2019 / Accepted: 12 February 2019 / Published: 15 February 2019
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Abstract
During the last thirty years, microstructural and technological studies on ceramic glazes have been essentially carried out through the use of Scanning Electron Microscopy (SEM) combined with energy dispersive X-ray analysis (EDX). On the contrary, optical microscopy (OM) has been considered of limited [...] Read more.
During the last thirty years, microstructural and technological studies on ceramic glazes have been essentially carried out through the use of Scanning Electron Microscopy (SEM) combined with energy dispersive X-ray analysis (EDX). On the contrary, optical microscopy (OM) has been considered of limited use in solving the very complex and fine-scale microstructures associated with ceramic glazes. As the crystallites formed inside glazes are sub- and micrometric, a common misconception is that it is not possible to study them by OM. This is probably one of the reasons why there are no available articles and textbooks and even no visual resources for describing and characterizing the micro-crystallites formed in glaze matrices. A thin section petrography (TSP) for ceramic glaze microstructures does not exist yet, neither as a field of study nor conceptually. In the present contribution, we intend to show new developments in the field of ceramic glaze petrography, highlighting the potential of OM in the microstructural studies of ceramic glazes using petrographic thin sections. The outcomes not only stress the pivotal role of thin section petrography for the study of glaze microstructures but also show that this step should not be bypassed to achieve reliable readings of the glaze microstructures and sound interpretations of the technological procedures. We suggest the adoption by the scientific community of an alternative vision on glaze microstructures to turn thin section petrography for glaze microstructures into a new specialized petrographic discipline. Such an approach, if intensively developed, has the potential to reduce the time and costs of scientific investigations in this specific domain. In fact, it can provide key reference data for the identification of the crystallites in ceramic glazes, avoiding the repetition of exhaustive protocols of expensive integrated analyses. Full article
(This article belongs to the Special Issue Minerals and Crystals in Glass)
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Open AccessArticle Surface Organic Modification of CaCO3-TiO2 Composite Pigment
Minerals 2019, 9(2), 112; https://doi.org/10.3390/min9020112
Received: 2 December 2018 / Revised: 30 January 2019 / Accepted: 11 February 2019 / Published: 15 February 2019
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Abstract
To improve the properties and dispersibility of CaCO3-TiO2 composite pigments (CaCO3-TiO2) in organic matrices, the surface modification of CaCO3-TiO2 was performed with sodium stearate (SS) as an organic modifier by wet ultra-fine grinding [...] Read more.
To improve the properties and dispersibility of CaCO3-TiO2 composite pigments (CaCO3-TiO2) in organic matrices, the surface modification of CaCO3-TiO2 was performed with sodium stearate (SS) as an organic modifier by wet ultra-fine grinding in a stirred mill. The pigment properties of modified CaCO3-TiO2 and its dispersibility in organic media were tested and characterized. The binding mechanism between CaCO3-TiO2 and SS was explored by infrared spectrometry (IR) and X-ray photoelectron energy spectroscopy (XPS). The results showed that the mechanical grinding strength and SS dosage had a significant effect on the activation index and sedimentation rate of CaCO3-TiO2. After surface modification, the surface of CaCO3-TiO2 turned from a hydrophilic surface to a hydrophobic surface and the surface free energy was reduced. In addition, the hiding property and dispersibility of CaCO3-TiO2 in the organic medium were significantly improved. IR and XPS results indicated that the modifier SS was adsorbed on the surface of CaCO3-TiO2 by chemical combination. Full article
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Open AccessArticle Distribution and Risk Assessment of Heavy Metals in Sediment from Bohai Bay, China
Minerals 2019, 9(2), 111; https://doi.org/10.3390/min9020111
Received: 24 December 2018 / Revised: 9 February 2019 / Accepted: 10 February 2019 / Published: 14 February 2019
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Abstract
Sediment core and porewater samples from the Western coastal tidal flat in Bohai Bay, China, were collected for meals and physical-chemical properties analysis. The vertical distribution characteristics of eight metals along the core was investigated based on 137Cs and 210Pb radionuclide [...] Read more.
Sediment core and porewater samples from the Western coastal tidal flat in Bohai Bay, China, were collected for meals and physical-chemical properties analysis. The vertical distribution characteristics of eight metals along the core was investigated based on 137Cs and 210Pb radionuclide dating. The chemical fractions of six metals (Cu, Pb, Zn, Ni, Mn and Cd) were also measured based on the modified European Community Bureau of Reference (BCR) sequential extraction procedures to better understand the mobility and bioavailability of these metals in the sediment. In addition, geoaccumulation index (Igeo) and risk assessment code (RAC) are used to assess risk status of these metals in the environment. 210Pb measurement indicates a sedimentation rate of about −1.87 cm∙year−1. The metals Cu, Zn, Pb and Ni show similar vertical distributions throughout the core, while Mn and Cd show different distribution patterns. Ni, Cu, Pb and Zn are strongly associated with the residual fraction while Mn and Cd are dominant in the acid-soluble fraction. According to the estimated diffusive fluxes, the Zn ions were the most mobilized, followed by Cu, Ni, Pb, and to a lesser extent Cd. The result of Igeo shows that Ni in sediments does not reflect any pollution, and Cu, Pb and Zn are in a level from unpolluted to modest polluted throughout the core. Mn and Cd have obvious anthropogenic sources. Based on the RAC, Cd and Mn pose a high to very high risk to the local environment, respectively, due to the significant percentage of exchangeable fraction. Clay content is significantly positively correlated with Ni, Cu, Al and Fe, and Cu, Pb, Zn and Ni might originate from the same sources or be influenced by similar geochemical processes. River runoff and atmospheric deposition are important sources for heavy metals, and since 1998, domestic sewage discharge might have had an important influence on the source of heavy metals (except for Cd and Mn). Full article
(This article belongs to the Special Issue Metallic Elements in Sediments)
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Open AccessArticle Natural Graphite Cuboids
Minerals 2019, 9(2), 110; https://doi.org/10.3390/min9020110
Received: 12 December 2018 / Revised: 27 January 2019 / Accepted: 5 February 2019 / Published: 14 February 2019
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Abstract
Graphite cuboids are abundant in ultrahigh-pressure metamorphic rocks and are generally interpreted as products of partial or complete graphitization of pre-existing diamonds. The understanding of the graphite cuboid structure and its formation mechanisms is still very limited compared to nanotubes, cones, and other [...] Read more.
Graphite cuboids are abundant in ultrahigh-pressure metamorphic rocks and are generally interpreted as products of partial or complete graphitization of pre-existing diamonds. The understanding of the graphite cuboid structure and its formation mechanisms is still very limited compared to nanotubes, cones, and other carbon morphologies. This paper is devoted to the natural occurrences of graphite cuboids in several metamorphic and magmatic rocks, including diamondiferous metamorphic assemblages. The studied cuboids are polycrystalline aggregates composed either of numerous smaller graphite cuboids with smooth surfaces or graphite flakes radiating from a common center. Silicates, oxides, and sulphides are abundant in all the samples studied, testifying that the presence of oxygen, sulfur, or sulphides in natural systems does not prevent the spherulitic growth of graphite. The surface topography and internal morphology of graphite cuboids combined with petrological data suggest that graphite cuboids originated from a magmatic or metamorphic fluid/melt and do not represent products of diamond-graphite transformation processes, even in diamond-bearing rocks. Full article
(This article belongs to the Special Issue Mineralogy of Natural Graphite)
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Open AccessArticle The Correlation of Roasting Conditions in Selective Potassium Extraction from K-Feldspar Ore
Minerals 2019, 9(2), 109; https://doi.org/10.3390/min9020109
Received: 17 January 2019 / Revised: 5 February 2019 / Accepted: 11 February 2019 / Published: 13 February 2019
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Abstract
Feldspar minerals are essential ingredients for the glass and ceramic-glass industries. The potassium element found in certain proportions in the composition of K-feldspar minerals has a fundamental function in the growth of plants. The production of potassium fertilizers is mostly made from the [...] Read more.
Feldspar minerals are essential ingredients for the glass and ceramic-glass industries. The potassium element found in certain proportions in the composition of K-feldspar minerals has a fundamental function in the growth of plants. The production of potassium fertilizers is mostly made from the soluble minerals, which are located in lakes. Despite having a huge area of use in the agriculture industry, the reserves of these salts are limited and not evenly distributed in the earth’s crust. Due to the high availability of feldspar reserves in the earth’s crust, the production of potential potassium salts can provide a wide range of social and economic benefits. In this study, potassium extraction from a feldspar ore, which contained microcline, albite, muscovite, and quartz, was studied using chloridizing (CaCl2) roasting followed by leaching. Direct leaching experiments were also performed on the sample by adapting various solvents. To emphasize the importance of roasting before the dissolution process, different parameters such as particle size, roasting temperature, and duration, as well as the feldspar/CaCl2 ratio, were tested. Under the optimum conditions (i.e., −106 microns, 850 Co, 60 minutes, 1:1.5 feldspar:CaCl2), 99% of the potassium was successfully extracted from the ore feed. Full article
(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)
Open AccessArticle Incorporation of Geometallurgical Attributes and Geological Uncertainty into Long-Term Open-Pit Mine Planning
Minerals 2019, 9(2), 108; https://doi.org/10.3390/min9020108
Received: 10 December 2018 / Revised: 5 February 2019 / Accepted: 6 February 2019 / Published: 13 February 2019
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Abstract
Long-term open-pit mine planning is a critical stage of a mining project that seeks to establish the best strategy for extracting mineral resources, based on the assumption of several economic, geological and operational parameters. Conventionally, during this process it is common to use [...] Read more.
Long-term open-pit mine planning is a critical stage of a mining project that seeks to establish the best strategy for extracting mineral resources, based on the assumption of several economic, geological and operational parameters. Conventionally, during this process it is common to use deterministic resource models to estimate in situ ore grades and to assume average values for geometallurgical variables. These assumptions cause risks that may negatively impact on the planned production and finally on the project value. This paper addresses the long-term planning of an open-pit mine considering (i) the incorporation of geometallurgical models given by equiprobable scenarios that allow for the assessing of the spatial variability and the uncertainty of the mineral deposit, and (ii) the use of stochastic integer programming model for risk analysis in direct block scheduling, considering the scenarios simultaneously. The methodology comprises two stages: pit optimization to generate initial ultimate pit limit per scenario and then to define a single ultimate pit based on reliability, and stochastic life-of-mine production scheduling to define block extraction sequences within the reliability ultimate pit to maximize the expected discounted value and minimize the total cost of production objective deviations. To evaluate the effect of the geometallurgical information, both stages consider different optimization strategies that depend on the economic model to be used and the type of processing constraints established in the scheduling. The results show that geometallurgical data with their associated uncertainties can change the decisions regarding pit limits and production schedule and, consequently, to impact the financial outcomes. Full article
(This article belongs to the Special Issue Geometallurgy)
Open AccessArticle An Innovative Method for Placement of Gangue Backfilling Material in Steep Underground Coal Mines
Minerals 2019, 9(2), 107; https://doi.org/10.3390/min9020107
Received: 17 January 2019 / Revised: 7 February 2019 / Accepted: 11 February 2019 / Published: 13 February 2019
Viewed by 193 | PDF Full-text (1073 KB)
Abstract
Using gangue backfilling in underground coal mining not only controls the roof deformation in the gob area but also reduces the amount of mining waste rock. However, due to the limitations of the complicated engineering conditions, backfilling mining in the steep coal seam [...] Read more.
Using gangue backfilling in underground coal mining not only controls the roof deformation in the gob area but also reduces the amount of mining waste rock. However, due to the limitations of the complicated engineering conditions, backfilling mining in the steep coal seam is not widely applied. In this study, a long-distance backfilling technology with a scraper winch for a steep coal seam was proposed and applied in a flexible shield supporting working face in Datai Mine, Beijing. Aiming at the problem of the decreasing backfilling ratio in field practice, numerical simulation was carried out to research the moving law of gangue in the goaf. The gangue mainly experienced four stages: gangue landslide stage, small-scale subsidence stage, funnel-shaped subsidence stage, and large-scale subsidence stage. The moving area of the gangue could be divided into five areas including a motionless area, a landslide area, a subsidence area, a funnel-shaped subsidence area, and a to-be-backfilled area. With the increase of the inclined length of the working face, the moving time of the gangue increased gradually. Based on the simulation results, the scheme of backfilling and mining in Datai Mine was optimized, for which the inclined length of the working face was shortened, and a higher backfilling ratio was obtained. Full article
(This article belongs to the Special Issue Backfilling Materials for Underground Mining)
Open AccessEditorial Editorial for Special Issue “New Mineral Species and Their Crystal Structures”
Minerals 2019, 9(2), 106; https://doi.org/10.3390/min9020106
Received: 17 January 2019 / Revised: 30 January 2019 / Accepted: 1 February 2019 / Published: 13 February 2019
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Abstract
Mineralogy is the oldest and one of the most important sciences of the geological cycle [...] Full article
(This article belongs to the Special Issue New Mineral Species and Their Crystal Structures)
Open AccessReview Emerald Deposits: A Review and Enhanced Classification
Minerals 2019, 9(2), 105; https://doi.org/10.3390/min9020105
Received: 12 January 2019 / Revised: 7 February 2019 / Accepted: 9 February 2019 / Published: 13 February 2019
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Abstract
Although emerald deposits are relatively rare, they can be formed in several different, but
specific geologic settings and the classification systems and models currently used to describe
emerald precipitation and predict its occurrence are too restrictive, leading to confusion as to the
exact [...] Read more.
Although emerald deposits are relatively rare, they can be formed in several different, but
specific geologic settings and the classification systems and models currently used to describe
emerald precipitation and predict its occurrence are too restrictive, leading to confusion as to the
exact mode of formation for some emerald deposits. Generally speaking, emerald is beryl with
sufficient concentrations of the chromophores, chromium and vanadium, to result in green and
sometimes bluish green or yellowish green crystals. The limiting factor in the formation of emerald
is geological conditions resulting in an environment rich in both beryllium and chromium or
vanadium. Historically, emerald deposits have been classified into three broad types. The first and
most abundant deposit type, in terms of production, is the desilicated pegmatite related type that
formed via the interaction of metasomatic fluids with beryllium-rich pegmatites, or similar granitic
bodies, that intruded into chromium- or vanadium-rich rocks, such as ultramafic and volcanic rocks,
or shales derived from those rocks. A second deposit type, accounting for most of the emerald of
gem quality, is the sedimentary type, which generally involves the interaction, along faults and
fractures, of upper level crustal brines rich in Be from evaporite interaction with shales and other
Cr- and/or V-bearing sedimentary rocks. The third, and comparatively most rare, deposit type is the
metamorphic-metasomatic deposit. In this deposit model, deeper crustal fluids circulate along faults
or shear zones and interact with metamorphosed shales, carbonates, and ultramafic rocks, and Be
and Cr (±V) may either be transported to the deposition site via the fluids or already be present in
the host metamorphic rocks intersected by the faults or shear zones. All three emerald deposit
models require some level of tectonic activity and often continued tectonic activity can result in the
metamorphism of an existing sedimentary or magmatic type deposit. In the extreme, at deeper
crustal levels, high-grade metamorphism can result in the partial melting of metamorphic rocks,
blurring the distinction between metamorphic and magmatic deposit types. In the present paper,
we propose an enhanced classification for emerald deposits based on the geological environment,
i.e., magmatic or metamorphic; host-rocks type, i.e., mafic-ultramafic rocks, sedimentary rocks, and
granitoids; degree of metamorphism; styles of minerlization, i.e., veins, pods, metasomatites, shear
zone; type of fluids and their temperature, pressure, composition. The new classification accounts
for multi-stage formation of the deposits and ages of formation, as well as probable remobilization
of previous beryllium mineralization, such as pegmatite intrusions in mafic-ultramafic rocks. Such
new considerations use the concept of genetic models based on studies employing chemical,
geochemical, radiogenic, and stable isotope, and fluid and solid inclusion fingerprints. The emerald occurrences and deposits are classified into two main types: (Type I) Tectonic magmatic-related
with sub-types hosted in: (IA) Mafic-ultramafic rocks (Brazil, Zambia, Russia, and others); (IB)
Sedimentary rocks (China, Canada, Norway, Kazakhstan, Australia); (IC) Granitic rocks (Nigeria).
(Type II) Tectonic metamorphic-related with sub-types hosted in: (IIA) Mafic-ultramafic rocks
(Brazil, Austria); (IIB) Sedimentary rocks-black shale (Colombia, Canada, USA); (IIC) Metamorphic
rocks (China, Afghanistan, USA); (IID) Metamorphosed and remobilized either type I deposits or
hidden granitic intrusion-related (Austria, Egypt, Australia, Pakistan), and some unclassified
deposits. Full article
(This article belongs to the Special Issue Mineralogy and Geochemistry of Gems)
Open AccessArticle Geology, Geochronology and Geochemistry of Weilasituo Sn-Polymetallic Deposit in Inner Mongolia, China
Minerals 2019, 9(2), 104; https://doi.org/10.3390/min9020104
Received: 2 December 2018 / Revised: 3 February 2019 / Accepted: 10 February 2019 / Published: 12 February 2019
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Abstract
The recently discovered Weilasituo Sn-polymetallic deposit in the Great Xing’an Range is an ultralarge porphyry-type deposit. The mineralization is closely associated with an Early Cretaceous quartz porphyry. Analysis of quartz porphyry samples, including zircon U-Pb dating and Hf isotopies, geochemical and molybdenite Re-Os [...] Read more.
The recently discovered Weilasituo Sn-polymetallic deposit in the Great Xing’an Range is an ultralarge porphyry-type deposit. The mineralization is closely associated with an Early Cretaceous quartz porphyry. Analysis of quartz porphyry samples, including zircon U-Pb dating and Hf isotopies, geochemical and molybdenite Re-Os isotopic testing, reveals a zircon U-Pb age of 138.6 ± 1.1 Ma and a molybdenite Re-Os isotopic age of 135 ± 7 Ma, suggesting the concurrence of the petrogenetic and metallogenic processes. The quartz porphyry has high concentrations of SiO2 (71.57 wt %–78.60 wt %), Al2O3 (12.69 wt %–16.32 wt %), and K2O + Na2O (8.85 wt %–10.44 wt %) and A/CNK ratios from 0.94–1.21, is mainly peraluminous, high-K calc-alkaline I-type granite and is relatively rich in LILEs (large ion lithophile elements, e.g., Th, Rb, U and K) and HFSEs (high field strength elements, e.g., Hf and Zr) and relatively poor in Sr, Ba, P, Ti and Nb. The zircon εHf(t) values range from 1.90 to 6.90, indicating that the magma source materials were mainly derived from the juvenile lower crust and experienced mixing with mantle materials. Given the regional structural evolution history, we conclude that the ore-forming magma originated from lower crust that had thickened and delaminated is the result of the subduction of the Paleo–Pacific Ocean. Following delamination, the lower crustal material entered the underlying mantle, where it was partially melted and reacted with mantle during ascent. The deposit formed at a time of transition from post-orogenic compression to extension following the subduction of the Paleo–Pacific Ocean. Full article
(This article belongs to the Special Issue Polymetallic Metallogenic System)
Open AccessArticle Micro-Laser-Induced Breakdown Spectroscopy: A Novel Approach Used in the Detection of Six Rare Earths and One Transition Metal
Minerals 2019, 9(2), 103; https://doi.org/10.3390/min9020103
Received: 3 January 2019 / Revised: 25 January 2019 / Accepted: 1 February 2019 / Published: 12 February 2019
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Abstract
Laser-induced breakdown spectroscopy (LIBS) was undertaken using an instrument which used a high-powered microscope to deliver the light and tightly focused the low energy laser beam onto the surface of a solid sample. A micro-plasma was generated on the surface of the sample [...] Read more.
Laser-induced breakdown spectroscopy (LIBS) was undertaken using an instrument which used a high-powered microscope to deliver the light and tightly focused the low energy laser beam onto the surface of a solid sample. A micro-plasma was generated on the surface of the sample under test even though the amount of energy/pulse from a beam of 532 nm was <1 mJ. Rare earth elements such as europium, gadolinium, lanthanum, neodymium, praseodymium, samarium, and a transition metal, yttrium, were tested. These elements are important in nuclear fission reactions especially for estimation of actinide masses for non-proliferation “safeguards”. Each element was mixed in the graphite matrix in different percentages from 1% to 50% by weight and the LIBS spectra were obtained for each composition as well as after mixing each element in the same amount using oxides of the elements. The data for the 5% mixture of the rare earth elements with graphite powder along with the transition metal has been presented in this article. A micro-LIBS approach was used to demonstrate that these rare earth elements can be identified individually and in a complex mixture in glove boxes in which the microscope LIBS instrument is housed in a nuclear research environment. Full article
(This article belongs to the Section Mineral Deposits)
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Open AccessArticle Experimental Research on Deformation Characteristics of Waste-Rock Material in Underground Backfill Mining
Minerals 2019, 9(2), 102; https://doi.org/10.3390/min9020102
Received: 2 January 2019 / Revised: 5 February 2019 / Accepted: 7 February 2019 / Published: 11 February 2019
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Abstract
Waste-rock material used in underground backfill mining has a granular texture and acquires non-linear deformation characteristics when compressed. The deformation modulus of waste-rock measured by a laboratory compression test is significantly different from the true deformation modulus in the field, due to the [...] Read more.
Waste-rock material used in underground backfill mining has a granular texture and acquires non-linear deformation characteristics when compressed. The deformation modulus of waste-rock measured by a laboratory compression test is significantly different from the true deformation modulus in the field, due to the complete confining effect of the loading steel cylinder. In this study, we performed a series of laboratory-based compression tests on waste-rock samples. The results showed that lab-acquired deformation modulus variations of waste rock could be divided into three stages: slow increase, accelerated increase, and rapid increase. We also measured the true deformation modulus of backfill waste rock by conducting a field test in gob areas of the Tangshan coal mine, China. The hardening process of backfill waste rock during the field test was analyzed, and could be divided into four stages: roof contact, rapid compression, slow compression, and long-term stable. With the increase of axial strain, the lab- and field-measured deformation moduli of waste rock both increased exponentially. A correction parameter was proposed to investigate the relationship between the field-generated true deformation modulus and the lab-tested deformation modulus. The correction parameter k positively correlated with the axial strain, in the form of an exponential function. The magnitude of k was between 0.5616 and 0.6531. Full article
(This article belongs to the Special Issue Backfilling Materials for Underground Mining)
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Open AccessFeature PaperArticle Ore Genesis at the Jinchang Gold–Copper Deposit in Heilongjiang Province, Northeastern China: Evidence from Geology, Fluid Inclusions, and H–O–S Isotopes
Minerals 2019, 9(2), 99; https://doi.org/10.3390/min9020099
Received: 18 December 2018 / Revised: 5 February 2019 / Accepted: 8 February 2019 / Published: 10 February 2019
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Abstract
The Jinchang gold–copper deposit is located in Eastern Heilongjiang Province, Northeastern China. The orebody comprises primarily hydrothermal breccias, quartz veins, and disseminated ores within granite, diorite, and granodiorite. Three paragenetic stages are identified: early quartz–pyrite–arsenopyrite (Stage 1), quartz–pyrite–chalcopyrite (Stage 2), and late quartz–pyrite–galena–sphalerite [...] Read more.
The Jinchang gold–copper deposit is located in Eastern Heilongjiang Province, Northeastern China. The orebody comprises primarily hydrothermal breccias, quartz veins, and disseminated ores within granite, diorite, and granodiorite. Three paragenetic stages are identified: early quartz–pyrite–arsenopyrite (Stage 1), quartz–pyrite–chalcopyrite (Stage 2), and late quartz–pyrite–galena–sphalerite (Stage 3). Gold was deposited during all three stages and Stage 1 was the major gold-producing stage. Copper is associated with the mineralization but has low economic value. Fluid inclusions (FIs) within the deposit are liquid-rich aqueous, vapor-rich aqueous, and daughter-mineral-bearing types. Microthermometric data for the FIs reveal decreasing homogenization temperatures (Th) and salinities of the ore-forming fluids over time. The Th for Stages 1–3 of the mineralization are 421–479, 363–408, and 296–347 °C, respectively. Stage 1 fluids in vapor-rich and daughter-mineral-bearing inclusions have salinities of 5.7–8.7 and 49.8–54.4 wt% NaCl equivalent, respectively. Stage 2 fluids in vapor-rich, liquid-rich, and daughter-mineral-bearing inclusions have salinities of 1.2–5.4, 9.5–16.0, and 43.3–48.3 wt% NaCl, respectively. Stage 3 fluids in liquid-rich and daughter-mineral-bearing inclusions have salinities of 7.9–12.6 and 38.3–42.0 wt% NaCl equivalent, respectively. The estimated trapping pressures are 160–220 bar, corresponding to an entrapment depth of 1.6–1.2 km in the paleo-water table. Oxygen and hydrogen isotope data (δ18OV-SMOW = 8.6‰ to 11.4‰; δDV-SMOW = −92.2‰ to −72.1‰) suggest that the ore-forming fluids were derived from magmatic fluids during the early stages of mineralization and subsequently incorporated meteoric water during the late stages. The sulfide minerals have δ34SVCDT values of 0.2‰–3.5‰, suggesting that the sulfur has a magmatic origin. The Jinchang deposit is a typical gold-rich gold–copper porphyry deposit. Full article
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Open AccessArticle Numerical Simulation on Authigenic Barite Formation in Marine Sediments
Minerals 2019, 9(2), 98; https://doi.org/10.3390/min9020098
Received: 29 December 2018 / Revised: 2 February 2019 / Accepted: 5 February 2019 / Published: 10 February 2019
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Abstract
Submarine cold seep and its associated authigenic minerals in sediment are meaningful to indicate the existence of underlying natural gas hydrate. The anaerobic oxidation of methane (AOM) is coupled with sulfate reduction (SR) and influences the dissolution and precipitation of barite. However, the [...] Read more.
Submarine cold seep and its associated authigenic minerals in sediment are meaningful to indicate the existence of underlying natural gas hydrate. The anaerobic oxidation of methane (AOM) is coupled with sulfate reduction (SR) and influences the dissolution and precipitation of barite. However, the forming mechanism of barite is not yet clearly understood. In order to investigate the forming process of authigenic barite and its relationship with methane leakage flux, based on the measured data of the Qiongdongnan Basin in the Northern slope of the South China Sea, we constructed a 1D model of a sedimentary column to reproduce the formation of barite using the numerical simulation method. The results show that the original equilibrium of barite was broken by the cold seep fluids and Ba2+ was carried upward to the sulfate-rich zone leading to the formation of barite front. When there is no flux of methane from the bottom of sediment, the barite front disappears. The relationship between methane leakage flux and authigenic minerals was also discussed. It can be concluded that high methane flux corresponds to a shallow barite front in the sediment, furthermore, the barite content first increases and then decreases as the methane flux increases. At the same time, an inverse relationship between the ratio of authigenic barite to calcite and methane flux was obtained. Full article
(This article belongs to the Special Issue Deep-Sea Minerals and Gas Hydrates)
Open AccessArticle The Effects of Al2O3 and SiO2 on the Formation Process of Silico-Ferrite of Calcium and Aluminum (SFCA) by Solid-State Reactions
Minerals 2019, 9(2), 101; https://doi.org/10.3390/min9020101
Received: 2 January 2019 / Revised: 30 January 2019 / Accepted: 31 January 2019 / Published: 10 February 2019
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Abstract
The silico-ferrite of calcium and aluminum (SFCA) is a significant crystalline phase that bonds in high basicity sinter. Al2O3 and SiO2 play an important role in the formation of SFCA in the Fe2O3–CaO–SiO2–Al [...] Read more.
The silico-ferrite of calcium and aluminum (SFCA) is a significant crystalline phase that bonds in high basicity sinter. Al2O3 and SiO2 play an important role in the formation of SFCA in the Fe2O3–CaO–SiO2–Al2O3 system, but the effect mechanism of Al2O3 and SiO2 on the formation of SFCA is unclear. To investigate this effect, sintering experiments were carried out with different temperatures and different times. It was found that the reaction of Al2O3 with CaFe2O4 (CF) as an initial product was easier to form during the calcium iron aluminum oxide (CFA) than that of SiO2 with CF to form SFC. This was due to the former directly forming to CFA while the latter initially formed Ca2SiO4 (C2S) and Ca2.5Fe15.5O25, and then SFC. It was also observed that when Al2O3 and SiO2 existed simultaneously, the Al2O3 initially reacted with CF to form CFA at 1100 °C, while the SiO2 participated in the formation of SFCA at 1150 °C without the formation of SFC. Moreover, it was understood that these were different effects in that the Al2O3 promoted the transformation from the orthorhombic crystal system to the triclinic crystal system, while the SiO2 dissolved into CFA to form the SFCA phase when Al2O3 existed. Full article
(This article belongs to the Special Issue Mineralogy of Iron Ore Sinters)
Open AccessArticle Origin of Smectite in Salinized Soil of Junggar Basin in Xinjiang of China
Minerals 2019, 9(2), 100; https://doi.org/10.3390/min9020100
Received: 13 December 2018 / Revised: 3 February 2019 / Accepted: 5 February 2019 / Published: 10 February 2019
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Abstract
In this paper, salinized soils with different degrees of salinity are sampled in Junggar Basin of Xinjiang of China. The X-ray diffraction, transmission electron microscopy, and inductively coupled plasma mass spectrometry are employed to investigate the morphology and distribution characteristics of smectite in [...] Read more.
In this paper, salinized soils with different degrees of salinity are sampled in Junggar Basin of Xinjiang of China. The X-ray diffraction, transmission electron microscopy, and inductively coupled plasma mass spectrometry are employed to investigate the morphology and distribution characteristics of smectite in salinized soil profiles. In the salinized soil profiles of this region, crystals of smectite are poor where lattice fringes are not parallel. In all soil layers, the content of smectite in the soil increases with the decrease in content of illite, which has demonstrated significant negative correlation (r = 0.79, n = 50, p < 0.01) between illite and smectite. This phenomenon has demonstrated that illite may be transformed into smectite in salinized soils of studied regions. In general, the transformation process of illite to smectite is affected by climate condition. The δ18O values of secondary carbonate in the 0–10 cm soil layers is higher than that in deep soil layers, which indicates that δ18O concentrates in surface soil and reflects temperature rise during soil layer formation. The δ13C values of secondary carbonate and soil organic matter in 0–10 cm soil layers are higher than that in deep soil layers. It indicates that C4 plants were the main plants, which reflects that the climate was relatively dry during the formation of the surface soil. Thus, the climate during the surface soil formation is arid, which is not conducive for leaching K+ from illite of the 0–10 cm soil to form smectite. As a result, the content of the smectite becomes lowest in the soil surface. In the relative humid condition of deep soil layers, the K+ of the illite of the soil would be relative easily leached and more smectite may be formed. Furthermore, the presence of salt in the salinized soil would promote the formation of smectite in Junggar Basin of Xinjiang. A lot of Ca2+, Na+ and Mg2+ in the soil solution of salinized soils would enter into the illite and occupy K+ positions. The studied result shows that the amount of smectite would increase with the increase of salt below 10 cm of the soil layer, where the amount of smectite would be significantly correlated with soil electrical conductivity (r = 0.64, n = 39, p < 0.01). In the Junggar Basin in Xinjiang, therefore, the salinized soil below 10 cm would have the necessary water conditions and chemical components for illite transformation to smectite. Full article
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Open AccessArticle A Workflow to Define, Map and Name a Carbonatite- or Alkaline Igneous-Associated REE-HFSE Mineral System: A Case Study from SW Germany
Minerals 2019, 9(2), 97; https://doi.org/10.3390/min9020097
Received: 4 December 2018 / Revised: 20 January 2019 / Accepted: 24 January 2019 / Published: 9 February 2019
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Abstract
Security of supply of “hi-tech” raw materials (including the rare earth elements (REE) and some high-field-strength elements (HFSEs)) is a concern for the European Union. Exploration and research projects mostly focus on deposit- to outcrop-scale description of carbonatite- and alkaline igneous-associated REE-HFSE mineralization. [...] Read more.
Security of supply of “hi-tech” raw materials (including the rare earth elements (REE) and some high-field-strength elements (HFSEs)) is a concern for the European Union. Exploration and research projects mostly focus on deposit- to outcrop-scale description of carbonatite- and alkaline igneous-associated REE-HFSE mineralization. The REE-HFSE mineral system concept and approach are at a nascent stage, so developed further here. However, before applying the mineral system approach to a chosen REE-HFSE metallogenic province its mineral system extent first needs defining and mapping. This shifts a mineral system project’s foundation from the mineral system concept to a province’s mineral system extent. The mapped extent is required to investigate systematically the pathways and potential trap locations along which the REE-HFSE mass may be distributed. A workflow is presented to standardize the 4-D definition of a REE-HFSE mineral system at province-scale: (a) Identify and hierarchically organize a mineral system’s genetically related sub-divisions and deposits, (b) map its known and possible maximum extents, (c) name it, (d) discern its size (known mineral endowment), and (e) assess the favorability of the critical components to prioritize further investigations. The workflow is designed to generate process-based perspective and improve predictive targeting effectiveness along under-evaluated plays of any mineral system, for the future risking, comparing and ranking of REE-HFSE provinces and plays. Full article
(This article belongs to the Special Issue Toward Mineral Systems for HFSE Rare Metals)
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Open AccessArticle Study of the Cu-Ni Productive Suite of the Pechenga Structure on the Russian-Norway Border Zone with the Use of MHD Installation “Khibiny”
Minerals 2019, 9(2), 96; https://doi.org/10.3390/min9020096
Received: 28 December 2018 / Revised: 1 February 2019 / Accepted: 3 February 2019 / Published: 8 February 2019
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Abstract
The tracing of current-conducting channels of the Pechenga structure from Russian to Norwegian territory was the main task of this research. The study was carried out in the framework of the Soviet-Norwegian cooperation “Northern Region” to estimate the prospects for discovery of Cu-Ni [...] Read more.
The tracing of current-conducting channels of the Pechenga structure from Russian to Norwegian territory was the main task of this research. The study was carried out in the framework of the Soviet-Norwegian cooperation “Northern Region” to estimate the prospects for discovery of Cu-Ni deposits in northern Norway. In addition to previous publications of technical character, the emphasis here is on geological description. Experimental measurements have been performed in the field of the “Khibiny” dipole and with the use of DC electrical profiling. The “Khibiny” dipole consists of 160-ton aluminum cable flooded in the Barents Sea bays on opposite sides of the Sredny and Rybachy peninsulas. Measurements were implemented as in the mode of single pulses generated by 80 MW magneto-hydrodynamic (MHD) generator “Khibiny” (“hot” launches) and in the accumulation mode of rectangular current pulses of 0.125 Hz frequency generated by a 29 kW car generator (“cold” launches). From results of measurements, it was concluded that the most promising potential for CU-Ni deposits Pil’gujarvi formation of the Northern wing of the Pechenga structure is rather quickly wedged out in Norway, while the conductive horizons of the Southern part of Pechenga, which have a weak prospect for CU-NI ores, follow into Norway nearly without a loss of power and integral electrical conductivity. Full article
(This article belongs to the Special Issue Arctic Mineral Resources: Science and Technology)
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Open AccessArticle Evaluating Metal Criticality for Low-Carbon Power Generation Technologies in Japan
Minerals 2019, 9(2), 95; https://doi.org/10.3390/min9020095
Received: 9 November 2018 / Revised: 31 January 2019 / Accepted: 5 February 2019 / Published: 8 February 2019
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Abstract
Given a potential increase in low-carbon power generation, assessing the criticality of metals used for its technologies is of significant importance. While several studies analyzed the metal criticality of an individual technology, the national metal criticality for a wide range of low-carbon power [...] Read more.
Given a potential increase in low-carbon power generation, assessing the criticality of metals used for its technologies is of significant importance. While several studies analyzed the metal criticality of an individual technology, the national metal criticality for a wide range of low-carbon power generation technologies and the comparison of overall criticality of each technology have yet to be fully evaluated. Therefore, this study firstly evaluates the criticality of 29 metals used in facilities for renewable energy and highly efficient thermal power generation in Japan and then compares the overall criticality for each technology to identify metals that might impose limitations on these technologies and to discuss measures for removal of factors hindering the spread of low-carbon power generation technologies. It was discovered that solar power generation technology is the most critical technology from the perspective of supply risk due to the use of indium, cadmium and selenium, while wind power generation is the most critical technology from the perspective of vulnerability to supply restriction because of the use of neodymium and dysprosium. A developed approach would have a significant potential to contributing to energy-mineral nexus, which may assist in providing policy implications from the perspectives of both specific metals and technologies. Full article
(This article belongs to the Special Issue Critical Minerals: Methodologies and Case Studies)
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