Hydrogen-based mineral phase transformation(HMPT)technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores.However,further research is needed to clarify ...Hydrogen-based mineral phase transformation(HMPT)technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores.However,further research is needed to clarify the phase composition and floatability of rare earths obtained after HMPT owing to the associated phase transformations.This study explored the mineralogical characteristics and separation behavior of rare earths in HMPT-treated iron tailings.Process mineralogy studies conducted via BGRIMM process mineralogy analysis and X-ray diffraction revealed that the main valuable minerals in the tailings included rare-earth oxides(9.15wt%),monazite(5.31wt%),and fluorite(23.52wt%).The study also examined the impact of mineral liberation and gangue mineral intergrowth on flotation performance.Flotation tests achieved a rare-earth oxide(REO)grade of 74.12wt% with a recovery of 34.17% in open-circuit flotation,whereas closed-circuit flotation resulted in a REO grade of 60.27wt% with a recovery of 73%.Transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy revealed that monazite remained stable during the HMPT process,while bastnaesite was transformed into Ce_(7)O_(12)and CeF_(3),leading to increased collector consumption.Nonetheless,the HMPT process did not significantly affect the flotation performance of rare earths.The enrichment of fluorite in the tailings highlighted its further recovery potential.The integration of HMPT with magnetic separation and flotation presents an efficient strategy for recovering rare earths,iron,and fluorite from Bayan Obo ores.展开更多
The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study cruci...The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study crucial for understanding environmental changes in the region.Despite its importance,research on the Shichuanhe River basin has thus far been primarily focused on riverbank construction,with limited exploration of its sediment characteristics.Although river sediments hold potential for guiding agricultural practices in the area,comprehensive studies on their composition and provenance remain scarce.To address this gap,a systematic sediment sampling campaign was conducted in the lower reaches of the Shichuanhe River,and detailed mineralogical analyses were performed.The results show that the sediment is predominantly composed of detrital quartz and feldspar(albite and orthoclase),with heavy minerals constituting approximately 10%–12%of the total sediment volume.The analysis of the heavy mineral assemblage reveals an absence of signifi cant contributions from igneous rocks in the sedimentary profi le.Furthermore,the distribution patterns of major,trace,and rare-earth elements in the Shichuanhe River’s argillaceous sediments exhibit similarities to those found in the Weihe River’s sediments.Elemental fractionation patterns suggest that the Shichuanhe River sediments are primarily derived from Loess Plateau sediments,aligning with fi ndings from both the Weihe River and the middle reaches of the Yellow River.展开更多
This paper focused on the investigation of the mineralogical characteristics of rare earth minerals from Bayan Obo tailings during the roasting process in the presence of coal,Ca（OH）_2 and NaOH.Roasting experiments ...This paper focused on the investigation of the mineralogical characteristics of rare earth minerals from Bayan Obo tailings during the roasting process in the presence of coal,Ca（OH）_2 and NaOH.Roasting experiments and leaching experiments were carried out to study the decomposition of rare earth minerals.The results indicated that bastnaesite and monazite could be completely decomposed at 650 ℃ and the leaching ratio of rare earths could reach 89.78%.The reaction mechanisms of bastnaesite and monazite at 650 ℃were analyzed.For bastnaesite,both the outer layer decomposition and inner core decomposition occurred simultaneously during the roasting.However,monazite was decomposed in a spatial sequence starting from the outer layer and proceeding to the inner core.展开更多
Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes.To develop value in the exploitation of sphalerite,samples were collecte...Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes.To develop value in the exploitation of sphalerite,samples were collected from 19 ore deposits in China and characterized for their mineralogical and photocatalytic properties.X-ray diffraction(XRD) and electron probe micro analysis(EPMA) measurements indicated that all the natural sphalerites from various localities crystallized in cubic phases with various chemical compositions.The substitution of Fe for Zn ranged from 0.235% to 14.826% by weight,Mn from 0.004% to4.868%,Cu from 0.009% to 5.529% and Cd from 0.133% to 1.576%.As Fe became more abundant,the color of natural sphalerite darkened,becoming almost black;and higher Fe content was associated with stronger visible light absorption.Photoluminescence spectra showed emission mainly related to S-vacancies and progressively decreasing fluorescence intensity with increasing Fe content.Tests of the photocatalytic degradation of methyl orange indicated that the sample with the highest Cd content but moderate Fe content had the highest photocatalytic activity.Specifically,the degradation of Methyl Orange(30 mg/L)attained 82.11% efficiency under visible light irradiation for 4 hr of natural sphalerite with4.262% Fe and 1.576% Cd.Overall,the Fe content in sphalerite was found to contribute to the visible light absorption ability and the recombination rate of photo-generated electrons and holes,while substitution by Cd was observed to have a greater effect on the photocatalytic properties.These findings provide a scientific basis for the profitable utilization of base metal resources like sphalerite.展开更多
Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization...Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment （ACE-Asia）. The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317μg m^-3 and 307μg m^-3, respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095μg m^-3, while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196μg m^-3 on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite （K/C） ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back-trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.展开更多
Talc is a hydroxyled, magnesium-rich, layered silicate that has the ideal chemical formula Mg3Si4O10(OH)2. Due to its unique properties, such as softness, chemical inertness, high thermal stability, low electrical con...Talc is a hydroxyled, magnesium-rich, layered silicate that has the ideal chemical formula Mg3Si4O10(OH)2. Due to its unique properties, such as softness, chemical inertness, high thermal stability, low electrical conductivity, lamellar habit, adsorption properties, and occurrence of a wide range of particle sizes that can be easily reduced by milling and high specific surface area, talc is widely used in many industries. A stratified deposit of unusual black talc, an occurrence of talc estimated to be more than half a billion tons, was found exposed in the late Neoproterozoic Dengying Formation, located in Guangfeng County, Jiangxi Province, southeastern China. The ores occur primarily as oolitic structures (Fig. 1). The mineralogical and geochemical characteristics of the ores were investigated by using multiple techniques. The ores were found to mainly consist of talc (30%–70%), dolomite, quartz, and magnesite. Most of talc crystals are ultrafine (with an average crystallite size of smaller than 5 μm) and appear as irregular broken or distorted lamellar flakes. The total organic carbon (TOC) content of the black talc ore samples is generally lower than 1.0%. Electron-microprobe analysis (EPMA) revealed low contents of Na, K, Ca and Mn, Fe, Ni, Al in the talc oolitic particles. The talc ores have low contents of toxic elements and relatively high contents of Li and Zn. The infrared spectrum of the black talc is similar to that of white talc from Trimouns (Pyrenees, France), and their Brunauer–Emmett-Teller (BET) specific surface areas, ranging from 15.7 to 23.2 m2/g, is much higher than those of white talc (normally lower than 5.0 m2/g), which may be due to the small size of the talc crystals.展开更多
The mineralogical characterization of antimony-bearing refractory gold concentrates and the antimony extraction by ozonein HCl solution were investigated.The mineralogical study shows that there exist stibnite(Sb2S3),...The mineralogical characterization of antimony-bearing refractory gold concentrates and the antimony extraction by ozonein HCl solution were investigated.The mineralogical study shows that there exist stibnite(Sb2S3),arsenopyrite(FeAsS),pyrite(FeS2)and quartz in the concentrates,and the gold is mainly(67.42%)encapsulated in sulfides.The antimony extraction by ozone inhydrochloric acid was employed and the influences of temperature,liquid/solid ratio,HCl concentration and stirring speed on theextraction of antimony were investigated.High antimony extraction(93.75%)is achieved under the optimized conditions.After thepretreatment by ozone,the antimony is recovered efficiently and the gold is enriched in the leaching residue.展开更多
The sodium roasted-acid leaching tailing(SRALT)of vanadium slag with a certain amount of vanadium exhibits potential environmental risk.To investigate the leaching behavior of vanadium from the SRALT,neutral batch lea...The sodium roasted-acid leaching tailing(SRALT)of vanadium slag with a certain amount of vanadium exhibits potential environmental risk.To investigate the leaching behavior of vanadium from the SRALT,neutral batch leaching tests were performed.The evolution of vanadium concentration,pH,redox potential(Eh),dissolved oxygen,and conductivity as a function of time was measured.Pourbaix diagrams of V–H2O system with different vanadium concentrations were obtained to identify the ionic speciation of vanadium in leachate.X-ray diffraction,X-ray photoelectron spectroscopy,field emission-scanning electron microscopy,and thermogravimetry–differential scanning calorimetry analysis were conducted to investigate the mineralogical evolution of the SRALT during the leaching process.It was found that the major minerals of the original SRALT are titanomagnetite,spinel,olivine,and augite.The valence states of V existing in the original SRALT are V^(3+)and V^(5+).The pH and Eh values of the obtained leachates are 10.00–10.58 and(−43)–(+67)mV,respectively.In this pH and Eh region,the released vanadium is mainly present as HVO_(4)^(2−).The FeOOH and CaCO_(3)would form during the leaching process.The HVO_(4)^(2−)would be mainly adsorbed by the FeOOH and slightly incorporated into the CaCO_(3),resulting in the decline in the vanadium concentration.The vanadium concentration above 27 mg L^(−1)and the dissolved oxygen value below 5.0 mg L^(−1)can be obtained after a short leaching period.As a V(V)-releasing and oxygen-depleting substance,the leaching toxicity of the SRALT should not be ignored.展开更多
The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a so...The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a source of eolian silty. The northeastern margin of the Tibetan Plateau is one of the most actively-growing mountain belt on earth, and has large amounts of debris, with masses of fine grained material, which were continuously mobilized and deposited in the Alagxa Plateau by rivers, forming broad alluvial fans. It is possible that the role of fluvial sediments as a source of silty dust in the Alagxa Plateau has been underestimated. In this study, we test this hypothesis by investigating the iron mineralogical and geochemical characteristics of the fluvial sediments and the surface material of the sandy desert in the Alagxa Plateau, and comparing them with paleo-eolian dust deposits(loess) in the adjacent Chinese Loess Plateau(CLP) to investigate the possible linkages among the fluvial sediments, sandy desert and the last glacial loess of the CLP. The results show that sandy desert typically have high contents of goethite, and high ratios of goethite to hematite, similar to the fluvial sediments in the Alagxa Plateau. Based on the major element characteristics, field investigations and the results of previous studies, we found a genetic link between the silt component of the fluvial sediments and the sandy desert in the Alagxa Plateau with high value of Gt(goethite) and similarity of the Gt/(Hm(hematite)+Gt) ratio. But the silt component of the sandy desert main come from the adjacent fluvial sediments. The iron mineralogical characteristics(χ(magnetic susceptibility), χARM(anhysteretic susceptibility), SIRM(saturation isothermal remanent magnetization) and SIRM_(AF100 mT)(SIRM demagnetized at 100 mT)) of the CLP samples overlap with those of the fluvial sediments in the Alagxa Plateau, but there is a mismatch with the sandy desert samples. This suggests that the fluvial sediments are the source of a large amount of silty material which could be transported to the CLP. Therefore, we conclude that the fluvial sediment in the Alagxa Plateau is an important source of eolian silt, which is deposited in downwind region, and that this source has been previously underestimated.展开更多
Batch experiments tively evaluate the inhibition were conducted to compara- effects and mechanisms of a low-concentration （1%） proline solution cover on the release of pollutants from high-sulfur coal gangue. High- ...Batch experiments tively evaluate the inhibition were conducted to compara- effects and mechanisms of a low-concentration （1%） proline solution cover on the release of pollutants from high-sulfur coal gangue. High- sulfur coal gangue was continuously immersed in a proline solution and in deionized water （as a control treatment） for 540 days. The results showed that the coal gangue in the control treatment was oxidized and generated leachate with poor water qualities, i.e., the leachate exhibited lower pH values, higher redox potential values, higher pollutant concentrations （804^2-, Fe, Mn, Cu, and Zn）, and high levels of acidophilic sulfur-oxidizing bacteria. However, compared to the control treatment, the addition of the proline solution （1%） significantly improved the water quality of the leachate by significantly reducing the Eh values, the pollutant concentrations （804^2-, Fe^2＋, Fe, Mn, Cu, and Zn）, and the activity of acidophilic sulfur-oxidiz- ing bacteria and by significantly increasing the pH value to neutral. The proline treatment significantly inhibited the oxidation of coal gangue and the release of pollutants, mainly by inhibiting the activity of acidophilic sulfur-ox- idizing bacteria and by altering the heavy metal fractions and the mineralogical characteristics. Therefore, in engi- neering practice, workers should consider using an envi- ronmental friendly aqueous proline solution cover to achieve the in-situ control of pollutant releases from coal gangue dumps.展开更多
Spinel exsolution is widespread in titanomagnetite from the Fe-Ti oxide gabbro of the Panzhihua intrusion, Emeishan Large Igneous Province, SW China. However, little research has been conducted into the implications o...Spinel exsolution is widespread in titanomagnetite from the Fe-Ti oxide gabbro of the Panzhihua intrusion, Emeishan Large Igneous Province, SW China. However, little research has been conducted into the implications of patterns in the mineralogical characteristics of the spinel for spatial variation in the controls on the exsolution mechanism and, hence, the formation process of the ore deposit. This study selected the Lanjiahuoshan Ore Block in the Panzhihua V-Ti magnetite deposit to explore this issue, systematically studying exsolution textures in the titanomagnetite through petrographic observation and the integrated use of in-situ microanalysis. The results show that the exsolved spinel gradually becomes finer-grained and less abundant from the center to edge and the bottom to top of the ore bodies. Compositionally, there is an inverse correlation between the size of exsolved spinel grains and their Mg# value. In addition, there is compositional zonation in the spinel interiors, with a gradual increase in the Mg content and decrease in Fe content from the core to the rim. The analysis suggests that fractional crystallization of ferrotitanium magma with a high oxygen fugacity in a shallow magma chamber caused compositional differences in the primary magnetite solid solution in different parts of the Panzhihua intrusion. Additionally, the thermal evolution of the magnetite solid solution differed in different parts of orebody, bringing about variations in spinel development. Together, these effects resulted in spatial variation in the abundance, grain size, and morphology of spinel in different parts of the orebody and intrusion that follows an identifiable distribution law. Furthermore, the compositional zonation of exsolved spinels reflects the rapid growth of exsolution features in a high-temperature environment. Thus, the size, morphology, abundance, and composition of spinel exsolution features in titanomagnetite provide a valuable petrogenetic tool for estimating the maturity and formational environment of the deposit.展开更多
1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of...1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of salt layers and interbedded facies.The latter consists mainly of mudstones,and mudstone-rich conglomerate.The mineralogy and geochemistry of salt-bearing beds and展开更多
A seafloor hydrothermal field, named Deyin-1 later, near 15°S southern Mid-Atlantic Ridge（SMAR） was newly found during the 22 nd cruise carried out by the China Ocean Mineral Resources Research ＆ Development A...A seafloor hydrothermal field, named Deyin-1 later, near 15°S southern Mid-Atlantic Ridge（SMAR） was newly found during the 22 nd cruise carried out by the China Ocean Mineral Resources Research ＆ Development Association（COMRA）. Sulfide samples were collected at three stations from the hydrothermal field during the26 th cruise in 2012. In this paper, mineralogical characteristics of the sulfides were analyzed with optical microscope, X-ray diffractometer, scanning electron microscope and electron microprobe to study the crystallization sequence of minerals and the process of hydrothermal mineralization. According to the difference of the ore-forming metal elements, the sulfide samples can be divided into three types：（1） the Ferich sulfide, which contains mainly pyrite and chalcopyrite;（2） the Fe-Cu-rich sulfide consisting predominantly of pyrite, chalcopyrite and isocubanite, with lesser amount of sphalerite, marmatite and pyrrhotine; and（3） the Fe-Zn-rich sulfide dominated by pyrite, sphalerite and marmatite, with variable amounts of chalcopyrite, isocubanite, pyrrhotine, marcasite, galena and gratonite. Mineral precipitations in these sulfides are in the sequence of chalcopyrite（isocubanite and possible coarse pyrite）, fine pyrite,sphalerite（marmatite）, galena, gratonite and then the minerals out of the dissolution. Two morphologically distinct generations（Py-I and Py-II） of pyrite are identified in each of the samples; inclusions of marmatite tend to exist in the coarse pyrite crystals（Py-I）. Sphalerite in the Fe-Zn-rich sulfide is characterized by a＂chalcopyrite disease＂ phenomenon. Mineral paragenetic relationships and a wide range of chemical compositions suggest that the environment of hydrothermal mineralization was largely changing. By comparison, the Fe-rich sulfide was formed in a relatively stable environment with a high temperature, but the conditions for the formation of the Fe-Cu-rich sulfide were variable. The Fe-Zn-rich sulfide was precipitated during the hydrothermal venting at relatively low temperature.展开更多
Phosphogypsum (PG) derived from the dissolution of phosphate ore in H2SO4 has been characterized by using chemical and thermogravimetric analyses, X-ray difFraction and infrared spectrum to give an idea about the futu...Phosphogypsum (PG) derived from the dissolution of phosphate ore in H2SO4 has been characterized by using chemical and thermogravimetric analyses, X-ray difFraction and infrared spectrum to give an idea about the future utifization of this waste material. The PG under the investigation was free from the radioactive elements and Cd and contained about 141 × 10-6 rare earth elements in total, which favours the utilization of this material. PG was formed mainIy of gypsum, little anhydrite and quartz and rare kaolinite. It exhibited two large endothermic peaks corresponding to the dehydration of the sample and a small one which may be attributed to the Iiberation of the residual water that may be found in the soluble anhydrite. Also, an exothermic peak was observed which may be related to the transformation of soluble (γ-anhydrite) to insoluble β-anhydrite. PG exhibited the same absorption bands as that observed for chemical CaSO4.2H2O and natural gypsum samples besides the appearance of a weak band at 840 cm-1 which characterizes the vibration of H2PO4- group展开更多
We explored the potential use of combining wavelength-dispersive X-ray spectroscopy(WDX) and micromorphology of thin sections to identify minerals in peat soils. Peat soil minerals from three peats and swamps across G...We explored the potential use of combining wavelength-dispersive X-ray spectroscopy(WDX) and micromorphology of thin sections to identify minerals in peat soils. Peat soil minerals from three peats and swamps across Golestan Province in northern Iran were first characterized by micromorphological studies. Soils were composed mainly of quartz, muscovite, biotite, pyroxene,sericitized Fe-nodules, and iron-rich garnet. In addition,micromorphological results indicated that Galougah Coastal Swamp sections contained some inorganic residue with biological origin including oyster and limpet, which may be related to the swamp's location near Gorgan Gulf.In order to determine mineralogical properties of samples,twelve unknown grains were chosen for elemental concentration map studies. Quartz, garnet, ilmenite, calcite,and pyroxene in Suteh samples; epidote and Fe-nodule in Ghaleh-Ghafeh Peat Swamp; and barite, phyllosilicates,and calcite in Galougah were identified by WDX mapping of Si, Al, Fe, Ca, Mg, C, Ba, S, and Ti. Composition of the oysters' body was also analyzed by WDX for Si, Ca, Fe,and C. The results indicated that most of the minerals in all sections likely formed through weathering, inheriting their composition from the parent rock. This research suggests that merging micromorphology and SEM/WDX image techniques can be useful in confirming the presence of mineral particles in soil science.展开更多
In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical prope...In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.展开更多
Ultramafic hypoxenoliths found in the alkali-rich porphyry in the Liuhe Village, Heqing, Yunnan, China, are of great significance in understanding the origin and evolution of the porphyry. This paper discusses the min...Ultramafic hypoxenoliths found in the alkali-rich porphyry in the Liuhe Village, Heqing, Yunnan, China, are of great significance in understanding the origin and evolution of the porphyry. This paper discusses the mineralogical features of the hypoxenoliths. It shows that the xenoliths are characterized by the upper mantle rocks modified to certain extent by the enriched mantle fluid metasomatism in the mantle environment, with the enriched mantle property of low-degree partial melting. This constitutes the important mineralogical evidence for the petrogenesis and mineralization of alkali-rich porphyry.展开更多
This paper presents a study research in the laboratory of three clayey soils from the depression of the Lama, a tropical climate area where disorders appear on construction and roads. Samples were tested to establish ...This paper presents a study research in the laboratory of three clayey soils from the depression of the Lama, a tropical climate area where disorders appear on construction and roads. Samples were tested to establish the relationship between their mineralogy and their geotechnical properties. On the three clayey soils, analyses were performed to characterize the macroscopic behavior (physical tests, free swelling test and compressibility tests) and the microstructural, chemical and mineralogical characterizations by thermal analysis, chemical analysis, X-Ray diffraction, Scanning Electron Microscopy observations complementary X-ray EDS analyses. At first glance, the results of physical and compressibility tests appear not to be consistent with the free swelling test results. Indeed, these results highlighted differences in the behaviors of the samples because the swelling potential revealed by the results of physical and compressibility test does not follow the same trend as the one given by the free swelling test result. The main clay minerals in the studied clayey soils varied from fibrous clays (palygorskite) to best-known clays such as smectite and kaolinite. Microstructural, chemical and mineralogical analyses allowed to understand and explain the different trends obtained by the different types of geotechnical characterization tests of studied clayey soils.展开更多
To contribute to the valorization of local materials, the physico-chemical and mineralogical characterization of two clay materials MJ and MN collected in the Mayo Tsanaga river which crosses the Makabaye district of ...To contribute to the valorization of local materials, the physico-chemical and mineralogical characterization of two clay materials MJ and MN collected in the Mayo Tsanaga river which crosses the Makabaye district of Maroua (Cameroon) was carried out. For this purpose, various methods of characterization have been used, namely granulometric analysis, Atterberg limits, X-ray fluorescence spectrometry and X-ray diffraction. It is apparent from the granulometry that the clay materials studied titrate 33.77% of clays for MJ against 44.13% for MN. The plasticity indices Ip with values IpMJ = 19.27% and IpMN = 23.4% place the materials in the plastic domain and offer them the possibility to being shaped into objects. The chemical composition of the MJ and MN materials reveals that the silicon oxide SiO2, the aluminumoxide Al2O3 and iron oxide Fe2O3 are their main constituents. The X-ray diffraction of the MJ and MN materials shows that they consist mainly of quartz with associated kaolinite, illite, montmorillonite, perlialite, dickite, nacrite, amesite, albite, brookite and anorthite. In addition to these, 2/1 minerals such as muscovite, nontronite, glauconite, and phlogopite are also identified in the MJ material. The peaks of sanidine, microcline and gismondine are also found in the MN material. The materials being rich in clay minerals 2/1 can be valorized in the adsorption and the absorption of the oils and greases and in the waterproofing of the grounds. The presence of quartz, kaolinite and illite is undoubtedly favorable for the manufacture of ceramic products in terracotta. These products will be obtained at a relatively lower temperature due to illite, feldspars and iron minerals that provide vitrification during firing by forming eutectics. The aluminosilicate amorphous phases contained in the studied materials can be exploited to produce geopolymer cements and concretes.展开更多
Geotechnical tests conducted on clayey materials of Missole II, Douala sub-basin of Cameroon showed that these materials present: fines particles (55 to 78 wt.%), sand (22 to 44 wt.%), and plasticity index of 13.8 to ...Geotechnical tests conducted on clayey materials of Missole II, Douala sub-basin of Cameroon showed that these materials present: fines particles (55 to 78 wt.%), sand (22 to 44 wt.%), and plasticity index of 13.8 to 21.6%. The X-ray diffraction (XRD) and the chemical analysis revealed a kaolinite amount of 46 to 56 wt.%, 19 to 27 wt.% of illite, 12 to 19 wt.% of quartz, 3 to 5 wt.% of goethite, 2 to 5 wt.% of hematite, 1.5 to 5 wt.% of anatase, 2 to 3 wt.% of feldspar-K with 52.87 to 63.11 wt.% of SiO2, 18.08 to 24.31 wt.% of Al2O3, 3.28 to 11.45 wt.% of Fe2O3 and a small content of bases (<2 wt.%). The results of geotechnical tests combined to those of the XRD and the chemical analysis showed that the Missole II clayey materials are suitable for the manufacture of bricks, tiles and sandstones.展开更多
基金the financial support received from the Key Program of National Natural Science Foundation of China(No.52130406)the National Key R&D Program of China(Nos.2021YFC2901000 and 2022YFC2905800)+1 种基金the General Program of National Natural Science Foundation of China(No.52274253)Natural Science Foundation Innovation Group Project of Hubei Province,China(No.2023AFA044)。
文摘Hydrogen-based mineral phase transformation(HMPT)technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores.However,further research is needed to clarify the phase composition and floatability of rare earths obtained after HMPT owing to the associated phase transformations.This study explored the mineralogical characteristics and separation behavior of rare earths in HMPT-treated iron tailings.Process mineralogy studies conducted via BGRIMM process mineralogy analysis and X-ray diffraction revealed that the main valuable minerals in the tailings included rare-earth oxides(9.15wt%),monazite(5.31wt%),and fluorite(23.52wt%).The study also examined the impact of mineral liberation and gangue mineral intergrowth on flotation performance.Flotation tests achieved a rare-earth oxide(REO)grade of 74.12wt% with a recovery of 34.17% in open-circuit flotation,whereas closed-circuit flotation resulted in a REO grade of 60.27wt% with a recovery of 73%.Transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy revealed that monazite remained stable during the HMPT process,while bastnaesite was transformed into Ce_(7)O_(12)and CeF_(3),leading to increased collector consumption.Nonetheless,the HMPT process did not significantly affect the flotation performance of rare earths.The enrichment of fluorite in the tailings highlighted its further recovery potential.The integration of HMPT with magnetic separation and flotation presents an efficient strategy for recovering rare earths,iron,and fluorite from Bayan Obo ores.
基金supported by the Key Project of Natural Science Basic Research Program of Shaanxi Province(2023-JC-ZD-16).
文摘The Shichuanhe River,a major tributary of the lower Weihe River,is situated in Xi’an,Shaanxi Province,China.It holds signifi cant information regarding the evolution of the Northern Weihe River,making its study crucial for understanding environmental changes in the region.Despite its importance,research on the Shichuanhe River basin has thus far been primarily focused on riverbank construction,with limited exploration of its sediment characteristics.Although river sediments hold potential for guiding agricultural practices in the area,comprehensive studies on their composition and provenance remain scarce.To address this gap,a systematic sediment sampling campaign was conducted in the lower reaches of the Shichuanhe River,and detailed mineralogical analyses were performed.The results show that the sediment is predominantly composed of detrital quartz and feldspar(albite and orthoclase),with heavy minerals constituting approximately 10%–12%of the total sediment volume.The analysis of the heavy mineral assemblage reveals an absence of signifi cant contributions from igneous rocks in the sedimentary profi le.Furthermore,the distribution patterns of major,trace,and rare-earth elements in the Shichuanhe River’s argillaceous sediments exhibit similarities to those found in the Weihe River’s sediments.Elemental fractionation patterns suggest that the Shichuanhe River sediments are primarily derived from Loess Plateau sediments,aligning with fi ndings from both the Weihe River and the middle reaches of the Yellow River.
基金supported by National Basic Research Program of China(973 Program)(2012CBA01205)
文摘This paper focused on the investigation of the mineralogical characteristics of rare earth minerals from Bayan Obo tailings during the roasting process in the presence of coal,Ca（OH）_2 and NaOH.Roasting experiments and leaching experiments were carried out to study the decomposition of rare earth minerals.The results indicated that bastnaesite and monazite could be completely decomposed at 650 ℃ and the leaching ratio of rare earths could reach 89.78%.The reaction mechanisms of bastnaesite and monazite at 650 ℃were analyzed.For bastnaesite,both the outer layer decomposition and inner core decomposition occurred simultaneously during the roasting.However,monazite was decomposed in a spatial sequence starting from the outer layer and proceeding to the inner core.
基金supported by the National Key Basic Research Program of China (973 Program,No.410020010).
文摘Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes.To develop value in the exploitation of sphalerite,samples were collected from 19 ore deposits in China and characterized for their mineralogical and photocatalytic properties.X-ray diffraction(XRD) and electron probe micro analysis(EPMA) measurements indicated that all the natural sphalerites from various localities crystallized in cubic phases with various chemical compositions.The substitution of Fe for Zn ranged from 0.235% to 14.826% by weight,Mn from 0.004% to4.868%,Cu from 0.009% to 5.529% and Cd from 0.133% to 1.576%.As Fe became more abundant,the color of natural sphalerite darkened,becoming almost black;and higher Fe content was associated with stronger visible light absorption.Photoluminescence spectra showed emission mainly related to S-vacancies and progressively decreasing fluorescence intensity with increasing Fe content.Tests of the photocatalytic degradation of methyl orange indicated that the sample with the highest Cd content but moderate Fe content had the highest photocatalytic activity.Specifically,the degradation of Methyl Orange(30 mg/L)attained 82.11% efficiency under visible light irradiation for 4 hr of natural sphalerite with4.262% Fe and 1.576% Cd.Overall,the Fe content in sphalerite was found to contribute to the visible light absorption ability and the recombination rate of photo-generated electrons and holes,while substitution by Cd was observed to have a greater effect on the photocatalytic properties.These findings provide a scientific basis for the profitable utilization of base metal resources like sphalerite.
基金The authors are very grateful to the anonymous reviewers for their constructive suggestions and comments.This research was supported by the National Natural Science Foundation of China(Grant No.40405023)the Chinese National Key Project of Basic Research(Grant G2004CB720200)+1 种基金the Science Foundation of Xi'an Jiaotong University(Grant No.XJJ2004006)a grant from the State Key Laboratory of Loess and Quaternary Geology(SKLLQG),Chinese Academy of Sciences.
文摘Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment （ACE-Asia）. The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317μg m^-3 and 307μg m^-3, respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095μg m^-3, while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196μg m^-3 on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite （K/C） ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back-trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.
文摘Talc is a hydroxyled, magnesium-rich, layered silicate that has the ideal chemical formula Mg3Si4O10(OH)2. Due to its unique properties, such as softness, chemical inertness, high thermal stability, low electrical conductivity, lamellar habit, adsorption properties, and occurrence of a wide range of particle sizes that can be easily reduced by milling and high specific surface area, talc is widely used in many industries. A stratified deposit of unusual black talc, an occurrence of talc estimated to be more than half a billion tons, was found exposed in the late Neoproterozoic Dengying Formation, located in Guangfeng County, Jiangxi Province, southeastern China. The ores occur primarily as oolitic structures (Fig. 1). The mineralogical and geochemical characteristics of the ores were investigated by using multiple techniques. The ores were found to mainly consist of talc (30%–70%), dolomite, quartz, and magnesite. Most of talc crystals are ultrafine (with an average crystallite size of smaller than 5 μm) and appear as irregular broken or distorted lamellar flakes. The total organic carbon (TOC) content of the black talc ore samples is generally lower than 1.0%. Electron-microprobe analysis (EPMA) revealed low contents of Na, K, Ca and Mn, Fe, Ni, Al in the talc oolitic particles. The talc ores have low contents of toxic elements and relatively high contents of Li and Zn. The infrared spectrum of the black talc is similar to that of white talc from Trimouns (Pyrenees, France), and their Brunauer–Emmett-Teller (BET) specific surface areas, ranging from 15.7 to 23.2 m2/g, is much higher than those of white talc (normally lower than 5.0 m2/g), which may be due to the small size of the talc crystals.
基金Project(51474257)supported by the National Natural Science Foundation of ChinaProject(2015zzts037)supported by the Postgraduate Research and Innovation Projects of Hunan province,ChinaProject(2015JC3005)supported by the Key Technology Research and Development Program of Hunan Province,China
文摘The mineralogical characterization of antimony-bearing refractory gold concentrates and the antimony extraction by ozonein HCl solution were investigated.The mineralogical study shows that there exist stibnite(Sb2S3),arsenopyrite(FeAsS),pyrite(FeS2)and quartz in the concentrates,and the gold is mainly(67.42%)encapsulated in sulfides.The antimony extraction by ozone inhydrochloric acid was employed and the influences of temperature,liquid/solid ratio,HCl concentration and stirring speed on theextraction of antimony were investigated.High antimony extraction(93.75%)is achieved under the optimized conditions.After thepretreatment by ozone,the antimony is recovered efficiently and the gold is enriched in the leaching residue.
基金supported by the Natural Science Foundation of Hebei Province(Nos.E2020209195,E2021209043,E2020209043),National Natural Science Foundation of China(No.51574108),Tangshan Municipal Project of Science and Technology(No.19150201E)Science and Technology Project of Hebei Education Department(Nos.BJ2020022,BJ2021034).
文摘The sodium roasted-acid leaching tailing(SRALT)of vanadium slag with a certain amount of vanadium exhibits potential environmental risk.To investigate the leaching behavior of vanadium from the SRALT,neutral batch leaching tests were performed.The evolution of vanadium concentration,pH,redox potential(Eh),dissolved oxygen,and conductivity as a function of time was measured.Pourbaix diagrams of V–H2O system with different vanadium concentrations were obtained to identify the ionic speciation of vanadium in leachate.X-ray diffraction,X-ray photoelectron spectroscopy,field emission-scanning electron microscopy,and thermogravimetry–differential scanning calorimetry analysis were conducted to investigate the mineralogical evolution of the SRALT during the leaching process.It was found that the major minerals of the original SRALT are titanomagnetite,spinel,olivine,and augite.The valence states of V existing in the original SRALT are V^(3+)and V^(5+).The pH and Eh values of the obtained leachates are 10.00–10.58 and(−43)–(+67)mV,respectively.In this pH and Eh region,the released vanadium is mainly present as HVO_(4)^(2−).The FeOOH and CaCO_(3)would form during the leaching process.The HVO_(4)^(2−)would be mainly adsorbed by the FeOOH and slightly incorporated into the CaCO_(3),resulting in the decline in the vanadium concentration.The vanadium concentration above 27 mg L^(−1)and the dissolved oxygen value below 5.0 mg L^(−1)can be obtained after a short leaching period.As a V(V)-releasing and oxygen-depleting substance,the leaching toxicity of the SRALT should not be ignored.
基金supported by the National Natural Science Foundation of China (41401046)the Fundamental Research Funds for the Central Universities (lzujbky-2016-264, lzujbky-2016-bt01)
文摘The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a source of eolian silty. The northeastern margin of the Tibetan Plateau is one of the most actively-growing mountain belt on earth, and has large amounts of debris, with masses of fine grained material, which were continuously mobilized and deposited in the Alagxa Plateau by rivers, forming broad alluvial fans. It is possible that the role of fluvial sediments as a source of silty dust in the Alagxa Plateau has been underestimated. In this study, we test this hypothesis by investigating the iron mineralogical and geochemical characteristics of the fluvial sediments and the surface material of the sandy desert in the Alagxa Plateau, and comparing them with paleo-eolian dust deposits(loess) in the adjacent Chinese Loess Plateau(CLP) to investigate the possible linkages among the fluvial sediments, sandy desert and the last glacial loess of the CLP. The results show that sandy desert typically have high contents of goethite, and high ratios of goethite to hematite, similar to the fluvial sediments in the Alagxa Plateau. Based on the major element characteristics, field investigations and the results of previous studies, we found a genetic link between the silt component of the fluvial sediments and the sandy desert in the Alagxa Plateau with high value of Gt(goethite) and similarity of the Gt/(Hm(hematite)+Gt) ratio. But the silt component of the sandy desert main come from the adjacent fluvial sediments. The iron mineralogical characteristics(χ(magnetic susceptibility), χARM(anhysteretic susceptibility), SIRM(saturation isothermal remanent magnetization) and SIRM_(AF100 mT)(SIRM demagnetized at 100 mT)) of the CLP samples overlap with those of the fluvial sediments in the Alagxa Plateau, but there is a mismatch with the sandy desert samples. This suggests that the fluvial sediments are the source of a large amount of silty material which could be transported to the CLP. Therefore, we conclude that the fluvial sediment in the Alagxa Plateau is an important source of eolian silt, which is deposited in downwind region, and that this source has been previously underestimated.
基金funded by a grant from the United Fund of Guizhou Province GovernmentNational Natural Science Foundation of China(No.U1612442-3)the Project of the Education Department of Guizhou Province(Nos.KY 2016011,GZZ201607,and ZDXK201611)
文摘Batch experiments tively evaluate the inhibition were conducted to compara- effects and mechanisms of a low-concentration （1%） proline solution cover on the release of pollutants from high-sulfur coal gangue. High- sulfur coal gangue was continuously immersed in a proline solution and in deionized water （as a control treatment） for 540 days. The results showed that the coal gangue in the control treatment was oxidized and generated leachate with poor water qualities, i.e., the leachate exhibited lower pH values, higher redox potential values, higher pollutant concentrations （804^2-, Fe, Mn, Cu, and Zn）, and high levels of acidophilic sulfur-oxidizing bacteria. However, compared to the control treatment, the addition of the proline solution （1%） significantly improved the water quality of the leachate by significantly reducing the Eh values, the pollutant concentrations （804^2-, Fe^2＋, Fe, Mn, Cu, and Zn）, and the activity of acidophilic sulfur-oxidiz- ing bacteria and by significantly increasing the pH value to neutral. The proline treatment significantly inhibited the oxidation of coal gangue and the release of pollutants, mainly by inhibiting the activity of acidophilic sulfur-ox- idizing bacteria and by altering the heavy metal fractions and the mineralogical characteristics. Therefore, in engi- neering practice, workers should consider using an envi- ronmental friendly aqueous proline solution cover to achieve the in-situ control of pollutant releases from coal gangue dumps.
基金funded by the National Natural Science Foundation of China(Grant No.41172047)the Open Fund of the Key Laboratory of Ore Deposit Geochemistry(Institute of Geochemistry,Chinese Academy of Sciences,Guiyang),(Grant No.201308)the Open Fund of the Key Laboratory Metallogeny and Mineral Resource Assessment,Ministry of Land and Resources(Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing)(Grant No.ZS1407)
文摘Spinel exsolution is widespread in titanomagnetite from the Fe-Ti oxide gabbro of the Panzhihua intrusion, Emeishan Large Igneous Province, SW China. However, little research has been conducted into the implications of patterns in the mineralogical characteristics of the spinel for spatial variation in the controls on the exsolution mechanism and, hence, the formation process of the ore deposit. This study selected the Lanjiahuoshan Ore Block in the Panzhihua V-Ti magnetite deposit to explore this issue, systematically studying exsolution textures in the titanomagnetite through petrographic observation and the integrated use of in-situ microanalysis. The results show that the exsolved spinel gradually becomes finer-grained and less abundant from the center to edge and the bottom to top of the ore bodies. Compositionally, there is an inverse correlation between the size of exsolved spinel grains and their Mg# value. In addition, there is compositional zonation in the spinel interiors, with a gradual increase in the Mg content and decrease in Fe content from the core to the rim. The analysis suggests that fractional crystallization of ferrotitanium magma with a high oxygen fugacity in a shallow magma chamber caused compositional differences in the primary magnetite solid solution in different parts of the Panzhihua intrusion. Additionally, the thermal evolution of the magnetite solid solution differed in different parts of orebody, bringing about variations in spinel development. Together, these effects resulted in spatial variation in the abundance, grain size, and morphology of spinel in different parts of the orebody and intrusion that follows an identifiable distribution law. Furthermore, the compositional zonation of exsolved spinels reflects the rapid growth of exsolution features in a high-temperature environment. Thus, the size, morphology, abundance, and composition of spinel exsolution features in titanomagnetite provide a valuable petrogenetic tool for estimating the maturity and formational environment of the deposit.
基金supported by the National Basic Research Program of China (2011CB403004)the National Natural Science Foundation of China (41303029)
文摘1 Introduction Geological studies established on several sections in Lanping-Simao basin have shown that the salt-bearing strata of Mengyejing formation(Yunlong Fm.in Lanping basin)are constituted by an alternation of salt layers and interbedded facies.The latter consists mainly of mudstones,and mudstone-rich conglomerate.The mineralogy and geochemistry of salt-bearing beds and
基金The National Basic Research Program(973 Program)of China under contract No.2013CB429702the National Oceanic Major Project of 12th Five Year under contract No.DY125-11-R-05
文摘A seafloor hydrothermal field, named Deyin-1 later, near 15°S southern Mid-Atlantic Ridge（SMAR） was newly found during the 22 nd cruise carried out by the China Ocean Mineral Resources Research ＆ Development Association（COMRA）. Sulfide samples were collected at three stations from the hydrothermal field during the26 th cruise in 2012. In this paper, mineralogical characteristics of the sulfides were analyzed with optical microscope, X-ray diffractometer, scanning electron microscope and electron microprobe to study the crystallization sequence of minerals and the process of hydrothermal mineralization. According to the difference of the ore-forming metal elements, the sulfide samples can be divided into three types：（1） the Ferich sulfide, which contains mainly pyrite and chalcopyrite;（2） the Fe-Cu-rich sulfide consisting predominantly of pyrite, chalcopyrite and isocubanite, with lesser amount of sphalerite, marmatite and pyrrhotine; and（3） the Fe-Zn-rich sulfide dominated by pyrite, sphalerite and marmatite, with variable amounts of chalcopyrite, isocubanite, pyrrhotine, marcasite, galena and gratonite. Mineral precipitations in these sulfides are in the sequence of chalcopyrite（isocubanite and possible coarse pyrite）, fine pyrite,sphalerite（marmatite）, galena, gratonite and then the minerals out of the dissolution. Two morphologically distinct generations（Py-I and Py-II） of pyrite are identified in each of the samples; inclusions of marmatite tend to exist in the coarse pyrite crystals（Py-I）. Sphalerite in the Fe-Zn-rich sulfide is characterized by a＂chalcopyrite disease＂ phenomenon. Mineral paragenetic relationships and a wide range of chemical compositions suggest that the environment of hydrothermal mineralization was largely changing. By comparison, the Fe-rich sulfide was formed in a relatively stable environment with a high temperature, but the conditions for the formation of the Fe-Cu-rich sulfide were variable. The Fe-Zn-rich sulfide was precipitated during the hydrothermal venting at relatively low temperature.
文摘Phosphogypsum (PG) derived from the dissolution of phosphate ore in H2SO4 has been characterized by using chemical and thermogravimetric analyses, X-ray difFraction and infrared spectrum to give an idea about the future utifization of this waste material. The PG under the investigation was free from the radioactive elements and Cd and contained about 141 × 10-6 rare earth elements in total, which favours the utilization of this material. PG was formed mainIy of gypsum, little anhydrite and quartz and rare kaolinite. It exhibited two large endothermic peaks corresponding to the dehydration of the sample and a small one which may be attributed to the Iiberation of the residual water that may be found in the soluble anhydrite. Also, an exothermic peak was observed which may be related to the transformation of soluble (γ-anhydrite) to insoluble β-anhydrite. PG exhibited the same absorption bands as that observed for chemical CaSO4.2H2O and natural gypsum samples besides the appearance of a weak band at 840 cm-1 which characterizes the vibration of H2PO4- group
文摘We explored the potential use of combining wavelength-dispersive X-ray spectroscopy(WDX) and micromorphology of thin sections to identify minerals in peat soils. Peat soil minerals from three peats and swamps across Golestan Province in northern Iran were first characterized by micromorphological studies. Soils were composed mainly of quartz, muscovite, biotite, pyroxene,sericitized Fe-nodules, and iron-rich garnet. In addition,micromorphological results indicated that Galougah Coastal Swamp sections contained some inorganic residue with biological origin including oyster and limpet, which may be related to the swamp's location near Gorgan Gulf.In order to determine mineralogical properties of samples,twelve unknown grains were chosen for elemental concentration map studies. Quartz, garnet, ilmenite, calcite,and pyroxene in Suteh samples; epidote and Fe-nodule in Ghaleh-Ghafeh Peat Swamp; and barite, phyllosilicates,and calcite in Galougah were identified by WDX mapping of Si, Al, Fe, Ca, Mg, C, Ba, S, and Ti. Composition of the oysters' body was also analyzed by WDX for Si, Ca, Fe,and C. The results indicated that most of the minerals in all sections likely formed through weathering, inheriting their composition from the parent rock. This research suggests that merging micromorphology and SEM/WDX image techniques can be useful in confirming the presence of mineral particles in soil science.
基金financially supported by the National Natural Science Foundation of China(No.52174291)。
文摘In order to study the sintering characteristics of Ca-rich iron ore,chemical analysis,laser diffraction,scanning electron microscopy,XRD-Rietveld method,and micro-sintering were used to analyze the mineralogical properties and sintering pot tests were used to study the sintering behavior.In addition,a grey correlation mathematical model was used to calculate and compare the comprehensive sintering performance under different calcium-rich iron ore contents.The results demonstrate that the Ca-rich iron ore has coarse grain size and strong self-fusing characteristics with Ca element in the form of calcite(CaCO_(3)) and the liquid phase produced by the self-fusing of the calcium-rich iron ore is well crystallized.Its application with a 20wt%content in sintering improves sinter productivity,reduces fuel consumption,enhances reduction index,and improves gas permeability in blast furnace by 0.45 t/(m^(2)·h),6.11 kg/t,6.17%,and 65.39 kPa·℃,respectively.The Ca-rich iron ore sintering can improve the calorific value of sintering flue gas compared with magnetite sintering,which is conducive to recovering heat for secondary use.As the content of the Ca-rich iron ore increases,sinter agglomeration shifts from localized liquid-phase bonding to a combination of localized liquid-phase bonding and iron oxide crystal connection.Based on an examination of the greater weight value of productivity with grey correlation analysis,the Ca-rich iron ore is beneficial for the comprehensive index of sintering in the range of 0-20wt%content.Therefore,it may be used in sintering with magnetite concentrates as the major ore species.
文摘Ultramafic hypoxenoliths found in the alkali-rich porphyry in the Liuhe Village, Heqing, Yunnan, China, are of great significance in understanding the origin and evolution of the porphyry. This paper discusses the mineralogical features of the hypoxenoliths. It shows that the xenoliths are characterized by the upper mantle rocks modified to certain extent by the enriched mantle fluid metasomatism in the mantle environment, with the enriched mantle property of low-degree partial melting. This constitutes the important mineralogical evidence for the petrogenesis and mineralization of alkali-rich porphyry.
文摘This paper presents a study research in the laboratory of three clayey soils from the depression of the Lama, a tropical climate area where disorders appear on construction and roads. Samples were tested to establish the relationship between their mineralogy and their geotechnical properties. On the three clayey soils, analyses were performed to characterize the macroscopic behavior (physical tests, free swelling test and compressibility tests) and the microstructural, chemical and mineralogical characterizations by thermal analysis, chemical analysis, X-Ray diffraction, Scanning Electron Microscopy observations complementary X-ray EDS analyses. At first glance, the results of physical and compressibility tests appear not to be consistent with the free swelling test results. Indeed, these results highlighted differences in the behaviors of the samples because the swelling potential revealed by the results of physical and compressibility test does not follow the same trend as the one given by the free swelling test result. The main clay minerals in the studied clayey soils varied from fibrous clays (palygorskite) to best-known clays such as smectite and kaolinite. Microstructural, chemical and mineralogical analyses allowed to understand and explain the different trends obtained by the different types of geotechnical characterization tests of studied clayey soils.
文摘To contribute to the valorization of local materials, the physico-chemical and mineralogical characterization of two clay materials MJ and MN collected in the Mayo Tsanaga river which crosses the Makabaye district of Maroua (Cameroon) was carried out. For this purpose, various methods of characterization have been used, namely granulometric analysis, Atterberg limits, X-ray fluorescence spectrometry and X-ray diffraction. It is apparent from the granulometry that the clay materials studied titrate 33.77% of clays for MJ against 44.13% for MN. The plasticity indices Ip with values IpMJ = 19.27% and IpMN = 23.4% place the materials in the plastic domain and offer them the possibility to being shaped into objects. The chemical composition of the MJ and MN materials reveals that the silicon oxide SiO2, the aluminumoxide Al2O3 and iron oxide Fe2O3 are their main constituents. The X-ray diffraction of the MJ and MN materials shows that they consist mainly of quartz with associated kaolinite, illite, montmorillonite, perlialite, dickite, nacrite, amesite, albite, brookite and anorthite. In addition to these, 2/1 minerals such as muscovite, nontronite, glauconite, and phlogopite are also identified in the MJ material. The peaks of sanidine, microcline and gismondine are also found in the MN material. The materials being rich in clay minerals 2/1 can be valorized in the adsorption and the absorption of the oils and greases and in the waterproofing of the grounds. The presence of quartz, kaolinite and illite is undoubtedly favorable for the manufacture of ceramic products in terracotta. These products will be obtained at a relatively lower temperature due to illite, feldspars and iron minerals that provide vitrification during firing by forming eutectics. The aluminosilicate amorphous phases contained in the studied materials can be exploited to produce geopolymer cements and concretes.
文摘Geotechnical tests conducted on clayey materials of Missole II, Douala sub-basin of Cameroon showed that these materials present: fines particles (55 to 78 wt.%), sand (22 to 44 wt.%), and plasticity index of 13.8 to 21.6%. The X-ray diffraction (XRD) and the chemical analysis revealed a kaolinite amount of 46 to 56 wt.%, 19 to 27 wt.% of illite, 12 to 19 wt.% of quartz, 3 to 5 wt.% of goethite, 2 to 5 wt.% of hematite, 1.5 to 5 wt.% of anatase, 2 to 3 wt.% of feldspar-K with 52.87 to 63.11 wt.% of SiO2, 18.08 to 24.31 wt.% of Al2O3, 3.28 to 11.45 wt.% of Fe2O3 and a small content of bases (<2 wt.%). The results of geotechnical tests combined to those of the XRD and the chemical analysis showed that the Missole II clayey materials are suitable for the manufacture of bricks, tiles and sandstones.
