The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models...The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic elements.Therefore,a large storage size of memory and long solution time are often needed in solving higher-frequency problems.In this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic BEM.The first one uses a plane wave expansion,which can be used to model scattering problems.The second one uses a special plane wave expansion,which can be used tomodel radiation problems.Five examples are investigated to showthe advantages of the enriched elements.Compared with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational time.This improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.展开更多
The zircon ore deposit in metasediments and peralkaline granite of the Kyemyeongsan Formation is located in southwest of Chungju city, Korea. The deposit, closely associated with REE and Nb,is composed of metasomatic ...The zircon ore deposit in metasediments and peralkaline granite of the Kyemyeongsan Formation is located in southwest of Chungju city, Korea. The deposit, closely associated with REE and Nb,is composed of metasomatic alkaline rocks and rare metal alkali granite, and was formed in late Carboniferous (340～343Ma). Zircon occurs in different paragenetic sequence: (1) earlier rare metal alkali granite, (2) later metasomatic zircon ore. The metasomatic zone contains abundant microcline, albite and quartz with minor biotite, magnetite, hornblende, allanite and zircon. The alkali granites have high silica (72.13～74.52wt.% as SiO 2), and total iron content (5.95～6.89%), and are characterized by low Al 2O 3 content (7.12～9.74%). They also show variable K 2O content (3.60～6.98%), and high ratios of K 2O/Na 2O. The REE patterns of rare metal alkali granite are similar to those of felsic volcanics from rifts, or back arc basins in, or near continental crust. Zircon ores are characterized by high iron content and low Al 2O 3, SiO 2, and K 2O content and have unusually high total REE content (0.18～2.33%). REE patterns show relatively flat to somewhat heavy REE (HREE) depleted characteristics (Ce/Yb=0.39～5.17) with large Eu negative anomaly (Eu/Eu *=0.16～0.29). Laser ablation microprobe inductively coupled plasma mass spectrometer (LAM ICP MS) analyses has been carried on zircon. The REE patterns of mineral zircons are almost the same to those of zircon ores and rare metal alkali granites, which may reflect the inability of zircons to effectively fractionated REE at formation of origin. The Sm Nd isochron age of the zircon ore and rare metal alkali granite are 330Ma, and 331Ma, respectively with ε Nd(t) being range from -2.00 to -1.84. This data suggest that the ore forming material came from the mantle. Alkali granite has suffered extensive post magmatic metasomatism of a high temperature to produce zircon ores. Geochemical characteristics show that metasomatism of alkaline fluid was probably the dominant ore forming process in Chungju district.展开更多
To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa,the present study focused on the size distribution and chemical characteristics of particulate matter(PM)emission resu...To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa,the present study focused on the size distribution and chemical characteristics of particulate matter(PM)emission resulting from 7 types of non-fossil pollution sources.We investigated the concentration and size distribution of trace elements from 7 pollution sources collected in Lhasa.Combining Lhasa’s atmospheric particulate matter data,enrichment factors(EFs)have been calculated to examine the potential impact of those pollution sources on the atmosphere quality of Lhasa.The highest mass concentration of total elements of biomass combustion appeared at PM_(0.4),and the second highest concentration existed in the size fraction 0.4-1μm;the higher proportion(12%)of toxicmetals was produced by biomass combustion.The elemental composition of suspended dust and atmospheric particulate matter was close(except for As and Cd);the highest concentration of elements was all noted in PM_(2.5-10)(PM_(3-10)).Potassium was found to be one of the main biomass markers.The proportion of Cu in suspended dust is significantly lower than that of atmospheric particulate matter(0.53%and 3.75%),which indicates that there are other anthropogenic sources.The EFs analysis showed that the Cr,Cu,Zn,and Pb produced by biomass combustion were highly enriched(EFs>100)in all particle sizes.The EFs of most trace elements increased with decreasing particle size,indicating the greater influence of humanfactors on smaller particles.展开更多
A new quadrilateral finite element IQ4 is developed for the free vibration of carbon nanotube-reinforced composite(CNTRC)perforated plates with a central cutout.By enriching the membrane part and incorporating a proje...A new quadrilateral finite element IQ4 is developed for the free vibration of carbon nanotube-reinforced composite(CNTRC)perforated plates with a central cutout.By enriching the membrane part and incorporating a projected shear technique,the IQ4 element is proposed to address the known limitations of the standard Q4 element,such as shear locking and limited consistency in the coupling ofmembrane-bending components.The proposed element is formulated within the FSDT-based framework and assessed through benchmark tests to verify its convergence and accuracy.The governing equations are obtained via theweak formofHamilton’s principle.Particular attention is given to the influence of carbon nanotube volume fraction,distribution patterns,and boundary conditions on the fundamental frequency response of CNTRC plates with cutouts.In addition,a parametric study is conducted to assess the influence of cutout geometric configuration,shape,and size ratios on the vibrational response of the CNTRC plate.The numerical results demonstrate that the formulated IQ4 element provides stable and accurate estimations of natural frequencies,even in the presence of a cutout and the coupled effects of the non-uniform distribution of reinforcement through the plate thickness.The developed formulation is expected to contribute to the structural design and optimization of advanced lightweight systems,particularly in aerospace and mechanical engineering applications.展开更多
The separation and enrichment of mercury and the recovery of elemental sulfur from flotation sulfur concentrate in zinc pressure leaching process were carried out by sodium sulfide leaching and carbon dioxide precipit...The separation and enrichment of mercury and the recovery of elemental sulfur from flotation sulfur concentrate in zinc pressure leaching process were carried out by sodium sulfide leaching and carbon dioxide precipitating. The results show that the leaching rate of elemental sulfur is more than 98%, and 98.13% of mercury is enriched in the residue, under the optimized conditions of sodium sulfide concentration 1.5 mol/L, liquid/solid ratio 6：1 and leaching time 30 min at room temperature. In addition, the content of mercury is enriched 5.23 times that in the leaching residue. The elemental sulfur is precipitated from leaching solution under conditions of carbon dioxide flow rate 200 mL/min and blowing time 150 min, while solution is stirred adequately. The recovery efficiency of elemental sulfur reaches 97.67%, and the purity of elemental sulfur is 99.75%, meeting the requirements of industrial first-rate product standard according to the national standard of GB/T 2449-2006 （PRC）.展开更多
In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical me...In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H_2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas,and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of variouselements and compounds, potentially up to extreme levels,and may explain various features both of mineralization and the magmas that produced them.展开更多
Rare earth element （REE） concentrations of two different types of groundwaters （high SO42–water-SW and high alkaline waterCW） from coal bearing aquifer （–400~–280 m） in Renlou coal mine,northern Anhui Provinc...Rare earth element （REE） concentrations of two different types of groundwaters （high SO42–water-SW and high alkaline waterCW） from coal bearing aquifer （–400~–280 m） in Renlou coal mine,northern Anhui Province,China were measured.The results indicated that they had different REE characteristics： the total concentrations of REEs （ΣREE） of SW were lower than those of CW in general although they all had heavy REEs enriched relative to light REEs.The dissolved REE inorganic species of SW included Ln3＋,LnCO3＋,LnSO4＋,Ln（CO3）2– and Ln（SO4）2–,whereas the CW are Ln（CO3）2– and LnCO3＋ dominant,and the proportions of Ln（CO3）2– increased while other species decreased with pH increasing.Combined with correlation analysis,the enrichment and fractionation of SW （low alkaline water） were considered to be affected by alkaline concentrations via affecting the types and proportions of REE inorganic species.However,the effect of alkaline concentrations to the enrichment and fractionation of REEs of CW （high alkaline water） was less important than total dissolved solids and pH,which reflected the contribution from different rocks they flowed over,different degrees of water-rock interactions and/or REE solid-liquid partition coefficients.展开更多
In the east coast Peninsular Malaysia region,sediments are transported by several rivers from the east Malaysia into the South China Sea estuary.In the vicinity of the five river estuaries core sediments were collecte...In the east coast Peninsular Malaysia region,sediments are transported by several rivers from the east Malaysia into the South China Sea estuary.In the vicinity of the five river estuaries core sediments were collected in order to investigate rare earth elements(REEs) profile.Core sediments were divided into strata of between 2 to 4 cm intervals and prepared for analyzing by ICP-AES.REE concentrations of 54.3 μg/gr at 24–26 cm in EC4 increased to 114.1 μg/gr at 20–22 cm in EC5.The measured concentration of ...展开更多
Concentrations of sixteen rare earth elements（REEs） in PM2.5 and potential-source samples, collected in Nanchang city in mid-September 2013, were determined by inductively coupled plasma mass spectrometry（ICP-MS）....Concentrations of sixteen rare earth elements（REEs） in PM2.5 and potential-source samples, collected in Nanchang city in mid-September 2013, were determined by inductively coupled plasma mass spectrometry（ICP-MS）. The results showed that the concentrations of total REEs（ΣREE） ranged from 78.76 to 1351 ng/mg. The order of REEs in PM2.5 samples showed the anthropogenic effects, Ce and Eu were affected more than the other REEs according to the enrichment factors. The results of chondrite-normalized REEs patterns and characteristic parameters showed evident light REEs fractionation, and positive anomalies of Ce and Eu in PM2.5. The other non-local pollution sources affected the PM2.5 samples, according to the triangular diagram of La, Ce and Sm compositions and plot of ΣREE vs δEu. Moreover, plot of（La/Sm）N vs（Gd/Yb）N revealed the effects of local sources. In conclusion, the REEs in potential-source samples were close to the background of local soil, while the REEs in PM2.5 samples in Nanchang city were jointly affected by the investigated local sources and other non-local sources.展开更多
The objective of this study was to investigate the vertical distribution of rare earth elements （REEs） in a natural wetland soil core to understand the influence of natural and anthropogenic activities on geochemica...The objective of this study was to investigate the vertical distribution of rare earth elements （REEs） in a natural wetland soil core to understand the influence of natural and anthropogenic activities on geochemical behavior of REEs. A natural wetland soil core of 95 cm was collected from the Sanjiang Plain in China and sliced into 5 cm slices for analyses of REEs, Fe, Al, Mn, Sc, Y, and soil organic matter （SOM）. Results indicated that SOM was accumulated in the upper part of the soil core （0 to 20 cm depth）, while Fe and Mn was reductively leached from the upper part of the soil core and accumulated in the low part. The content of total REEs ranged from 137.9 to 225.9 mg/kg in the soil core. Content profiles obtained for all REEs were almost identical except for Ce. The highest contents of REEs generally occurred at about 20 cm depth, but enrichment factor （EF） of REEs except Ce was usually the highest in the surface horizon. Average EF ranged from 1.1 for La to 2.1 for Gd. The pronounced shift in EF occurred at about 40 cm depth and it gradually increased from 40 cm depth to surface （except for Ce）, probably suggesting anthropogenic atmospheric deposition of REEs. In comparison with chondrite, Eu was depleted in all horizons, while Ce was negatively anomalous in the top horizons and positively anomalous in the bottom horizons. This positive anomaly of Ce in the bottom horizons was due to its preferential adsorption on Fe and Mn oxides, relative to other REEs. Although both natural and anthropogenic activi-ties influence the geochemical behaviors of REEs in soils, enrichment or mobility of REEs is low in the natural wetland soil core of the San-jiang Plain.展开更多
The phosphorite ores-deposits rich in rare earth elements(REE) in Zhijin, Xinhua, Guizhuo occurs in the early Cambrian Meishucun and at the bottom part of Qiongzhusi stage (the upper layer of phosphorites), belonging ...The phosphorite ores-deposits rich in rare earth elements(REE) in Zhijin, Xinhua, Guizhuo occurs in the early Cambrian Meishucun and at the bottom part of Qiongzhusi stage (the upper layer of phosphorites), belonging to Yangzi stratum section. The living creature scraps was proved existent in dolomitic-phosphorites by experiments, The REE could be extracted to provide the worthy data for the further using. Adopting the HNO3 to extract REE, through the ion exchange method, the REE recovery rate could be reached 85.44% , having certain reference value.展开更多
Ferromanganese crusts and nodules are important submarine mineral resources that contain various metal elements with significant economic value. In this study, polymetallic crusts and nodules obtained from the South C...Ferromanganese crusts and nodules are important submarine mineral resources that contain various metal elements with significant economic value. In this study, polymetallic crusts and nodules obtained from the South China Sea （SCS） were determined by using X-ray power diffraction （XRD）, Raman spectroscopy （RS）, Fourier transform infrared spectroscopy （FTIR）, and X-ray photoelectron spectroscopy （XPS） to systematically investigate and analyze the mineralogical and spectral characteristics of the Fe-Mn minerals. XRD measurements revealed that the SCS polymetallic crusts and nodules were composed of vernadite, quartz, and plagioclase. The nodules also contained todorokite. The Fe-phase minerals of the SCS crusts and nodules were composed of amorphous Fe oxide/hydroxide, and the Mn- and Fe-phases minerals exhibited relatively poor degrees of crystallization. FTIR results showed that the Fe-Mn minerals in the crusts and nodules included a large number of surface hydroxyl groups. These surface hydroxyl groups contained protons that could provide reactive sites for complexation of ore-forming elements in seawater. XPS results indicated that the surfaces of the Fe-Mn minerals mainly contained Fe, Mn, and O. Fe was present in the trivalent oxidation state, while Mn, which may contain several bivalent oxidation state, was present in the tetravalent and trivalent oxidation states. The SCS polymetallic crusts and nodules were compared with Pacific seamount crusts, and results showed that the surface hydroxyl （-OH） groups of the SCS crusts and nodules numbered more than the lattice oxygen （O^2-）. But the lattice oxygen of Pacific seamount crusts numbered more than the surface hydroxyl groups. This characteristic indicated that the degree of crystallization of Fe-Mn minerals from the Pacific Ocean was higher than that of minerals from the South China Sea. Comprehensive studies showed that ore-forming elements in the interface between seawater and the Fe-Mn minerals in the submarine ferromanganese crusts and nodules employed the following enrichment mechanisms： （1） the metal ion complexed with the surface hydroxyl of Fe-Mn minerals to form hydroxyl complexes, which were connected by coordination bonds or stable inner-sphere complexes that exchanged protons on the mineral surfaces; （2） the charged surfaces of the minerals and metal cations formed outer-sphere complexes, which made up the electrostatic double layer, through electrostatic adsorption; and （3） the metal cations isomorphously exchanged the Mn and Fe ions of the mineral lattice structure.展开更多
Compared to North American shale composition (NASC), REE contents of sediments from the CC area in the Pacific Ocean are obviously high except that cerium has equal content to that of NASC. Three-valence rare earth el...Compared to North American shale composition (NASC), REE contents of sediments from the CC area in the Pacific Ocean are obviously high except that cerium has equal content to that of NASC. Three-valence rare earth elements were completely enriched in phosphate-phase and cerium in iron-phase. Rare earth elements in the sediments were originally derived from seawater. During lithi- genic and minerogenic processes of metalliferous nodules, three-valence rare earth elements in sediments mobilized and incorporated into sediments as authigenous biogenic-apatite, while cerium had change from Ce3+ to Ce4+ and directly precipitated from seawater and entered metalliferous nodules and caused Ce anomalies in REE pattern in sediments.展开更多
The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investi...The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen content and trace elements' characters. One coefficient of Meij was also improved to more directly show element enrichment in combustion products. These elements may be classified into three groups according to their distribution: Group 1: Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2 Cr has properties of both group 1 and 3 In addition, the smaller diameter of fly ash, the more relative enrichment of trace elements(except Mn). The fly ash showed different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not always improve the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Trace elements should be classified in accordance with factors.展开更多
Three-dimensional(3D)graphene oxide-tris(4-aminophenyl)amine(GO-TAPAx:y)composites with different GO-to-TAPA mass ratios(x:y)were prepared by a facile one-step ultrasonic treatment.GOTAPAx:y composites were characteri...Three-dimensional(3D)graphene oxide-tris(4-aminophenyl)amine(GO-TAPAx:y)composites with different GO-to-TAPA mass ratios(x:y)were prepared by a facile one-step ultrasonic treatment.GOTAPAx:y composites were characterized by scanning electron microscopy(SEM),nitrogen(N2)adsorption-desorption isotherms,Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermogravimetric analysis(TGA).Behavior and mechanism of GO-TAPAx:yco mposites for the adsorption of rare earth elements(REEs)were investigated.The adso rption capacities of GO-TAPA1;2 composite for Yb^3+,Er^3+,Nd^3+,La^3+and Y^3+are 30.88,26.52,20.60,11.24 and 10.52 mg/g,respectively.Effects of some important parameters including GO-to-TAPA mass ratios,contact time,reaction temperature and initial Yb^3+concentration on the adsorption were evaluated in detail.FTIR spectral and XPS analyses show that the metal complexations and ion exchanges between nitrogen/oxygen-containing species of the adsorbents and REEs are involved in the adsorption procedure besides the conventional adsorption based on specific surface area,indicating the introduction of specific molecules onto GO is beneficial to its adsorption ability.The convenient reusability and applicability of GO-TAPAx:y composites toward real samples also demonstrate their feasibility in the enrichment of REE ions.展开更多
Soil heavy metal pollution is one of the main environmental problems in Pearl River Delta Economic?Zone of China. Based on multi-purpose regional geochemical survey, regional eco-geochemical assessment, local eco-geoc...Soil heavy metal pollution is one of the main environmental problems in Pearl River Delta Economic?Zone of China. Based on multi-purpose regional geochemical survey, regional eco-geochemical assessment, local eco-geochemical assessment and comprehensive appraisal, the eco-geochemical survey and assessment in Pearl River Delta Economic Zone of 41,698 km2?were completed. Samples from soils were collected in accordance with the two-layer grid method. Totally 54 elements and indicators for soils were determined. Compared to deep soils, the sampled surface soils are enriched in OrgC, N, P, Cd, S,Hg, Ag, B, Au, S and poor with As, Ni, I, Co, Cr, V, MgO, Sc, Al2O3, Fe2O3?etc. The characteristics of geochemical reference value of element in soil that inherited soil parent material and regional elements combined features reflected that the elements enriched in the soil was interrelated with acid rock, sandstone and shale. The spatial distribution characteristics of element regional geochemistry were conditional by regional environmental geological conditions,and effected by human activities. The Pearl River Delta plain is a typical geochemical landscape area with regional anomaly of multiple-elements. The north, western and eastern parts of the Pearl River Delta Economic Zone are quite different in geochemical features due to regional geological background, soil parent materials, geomorphic characteristics and human activities. Environment quality evaluation results show that the grade I and grade II soil accounted for 19.9% and 57.3% of the total area. Many samples that widely distributed in the economic developed of Pearl River Delta Plain area reached the third-grade of national soil environment standard. The soil enriched in Cd, Hg, As, and the area ratio accounting for 22.8% of the total area. It is mainly controlled by the geochemical background, the Pearl River Delta formation evolution process, especially the marine transgression process lead to Cd, Cu, Zn and Pb enrichment in Pearl River Delta plain. At the same time, under the influence of higher pressure of human activities, all kinds of exogenous input material carrying heavy metal pollutants on soil environmental quality also could not to ignore.展开更多
基金the National Natural Science Foundation of China(https://www.nsfc.gov.cn/,Project No.11972179)the Natural Science Foundation of Guangdong Province(http://gdstc.gd.gov.cn/,No.2020A1515010685)the Department of Education of Guangdong Province(http://edu.gd.gov.cn/,No.2020ZDZX2008).
文摘The boundary element method(BEM)is a popular method for solving acoustic wave propagation problems,especially those in exterior domains,owing to its ease in handling radiation conditions at infinity.However,BEM models must meet the requirement of 6–10 elements per wavelength,using the conventional constant,linear,or quadratic elements.Therefore,a large storage size of memory and long solution time are often needed in solving higher-frequency problems.In this work,we propose two new types of enriched elements based on conventional constant boundary elements to improve the computational efficiency of the 2D acoustic BEM.The first one uses a plane wave expansion,which can be used to model scattering problems.The second one uses a special plane wave expansion,which can be used tomodel radiation problems.Five examples are investigated to showthe advantages of the enriched elements.Compared with the conventional constant elements,the new enriched elements can deliver results with the same accuracy and in less computational time.This improvement in the computational efficiency is more evident at higher frequencies(with the nondimensional wave numbers exceeding 100).The paper concludes with the potential of our proposed enriched elements and plans for their further improvement.
文摘The zircon ore deposit in metasediments and peralkaline granite of the Kyemyeongsan Formation is located in southwest of Chungju city, Korea. The deposit, closely associated with REE and Nb,is composed of metasomatic alkaline rocks and rare metal alkali granite, and was formed in late Carboniferous (340～343Ma). Zircon occurs in different paragenetic sequence: (1) earlier rare metal alkali granite, (2) later metasomatic zircon ore. The metasomatic zone contains abundant microcline, albite and quartz with minor biotite, magnetite, hornblende, allanite and zircon. The alkali granites have high silica (72.13～74.52wt.% as SiO 2), and total iron content (5.95～6.89%), and are characterized by low Al 2O 3 content (7.12～9.74%). They also show variable K 2O content (3.60～6.98%), and high ratios of K 2O/Na 2O. The REE patterns of rare metal alkali granite are similar to those of felsic volcanics from rifts, or back arc basins in, or near continental crust. Zircon ores are characterized by high iron content and low Al 2O 3, SiO 2, and K 2O content and have unusually high total REE content (0.18～2.33%). REE patterns show relatively flat to somewhat heavy REE (HREE) depleted characteristics (Ce/Yb=0.39～5.17) with large Eu negative anomaly (Eu/Eu *=0.16～0.29). Laser ablation microprobe inductively coupled plasma mass spectrometer (LAM ICP MS) analyses has been carried on zircon. The REE patterns of mineral zircons are almost the same to those of zircon ores and rare metal alkali granites, which may reflect the inability of zircons to effectively fractionated REE at formation of origin. The Sm Nd isochron age of the zircon ore and rare metal alkali granite are 330Ma, and 331Ma, respectively with ε Nd(t) being range from -2.00 to -1.84. This data suggest that the ore forming material came from the mantle. Alkali granite has suffered extensive post magmatic metasomatism of a high temperature to produce zircon ores. Geochemical characteristics show that metasomatism of alkaline fluid was probably the dominant ore forming process in Chungju district.
基金supported by the Natural Science Foundation of China (No.11775180).
文摘To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa,the present study focused on the size distribution and chemical characteristics of particulate matter(PM)emission resulting from 7 types of non-fossil pollution sources.We investigated the concentration and size distribution of trace elements from 7 pollution sources collected in Lhasa.Combining Lhasa’s atmospheric particulate matter data,enrichment factors(EFs)have been calculated to examine the potential impact of those pollution sources on the atmosphere quality of Lhasa.The highest mass concentration of total elements of biomass combustion appeared at PM_(0.4),and the second highest concentration existed in the size fraction 0.4-1μm;the higher proportion(12%)of toxicmetals was produced by biomass combustion.The elemental composition of suspended dust and atmospheric particulate matter was close(except for As and Cd);the highest concentration of elements was all noted in PM_(2.5-10)(PM_(3-10)).Potassium was found to be one of the main biomass markers.The proportion of Cu in suspended dust is significantly lower than that of atmospheric particulate matter(0.53%and 3.75%),which indicates that there are other anthropogenic sources.The EFs analysis showed that the Cr,Cu,Zn,and Pb produced by biomass combustion were highly enriched(EFs>100)in all particle sizes.The EFs of most trace elements increased with decreasing particle size,indicating the greater influence of humanfactors on smaller particles.
文摘A new quadrilateral finite element IQ4 is developed for the free vibration of carbon nanotube-reinforced composite(CNTRC)perforated plates with a central cutout.By enriching the membrane part and incorporating a projected shear technique,the IQ4 element is proposed to address the known limitations of the standard Q4 element,such as shear locking and limited consistency in the coupling ofmembrane-bending components.The proposed element is formulated within the FSDT-based framework and assessed through benchmark tests to verify its convergence and accuracy.The governing equations are obtained via theweak formofHamilton’s principle.Particular attention is given to the influence of carbon nanotube volume fraction,distribution patterns,and boundary conditions on the fundamental frequency response of CNTRC plates with cutouts.In addition,a parametric study is conducted to assess the influence of cutout geometric configuration,shape,and size ratios on the vibrational response of the CNTRC plate.The numerical results demonstrate that the formulated IQ4 element provides stable and accurate estimations of natural frequencies,even in the presence of a cutout and the coupled effects of the non-uniform distribution of reinforcement through the plate thickness.The developed formulation is expected to contribute to the structural design and optimization of advanced lightweight systems,particularly in aerospace and mechanical engineering applications.
文摘The separation and enrichment of mercury and the recovery of elemental sulfur from flotation sulfur concentrate in zinc pressure leaching process were carried out by sodium sulfide leaching and carbon dioxide precipitating. The results show that the leaching rate of elemental sulfur is more than 98%, and 98.13% of mercury is enriched in the residue, under the optimized conditions of sodium sulfide concentration 1.5 mol/L, liquid/solid ratio 6：1 and leaching time 30 min at room temperature. In addition, the content of mercury is enriched 5.23 times that in the leaching residue. The elemental sulfur is precipitated from leaching solution under conditions of carbon dioxide flow rate 200 mL/min and blowing time 150 min, while solution is stirred adequately. The recovery efficiency of elemental sulfur reaches 97.67%, and the purity of elemental sulfur is 99.75%, meeting the requirements of industrial first-rate product standard according to the national standard of GB/T 2449-2006 （PRC）.
文摘In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites,and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H_2O are completely miscible in all proportions at magmatic temperatures and pressures. This phase evolves from felsic melts and changes into hydrothermal fluids, and its unique properties are particularly important in sequestering and concentrating low abundance elements, such as metals. In our past research, we have focused on processes observed at upper crustal levels, however extensive work by us and other researchers have demonstrated that supercritical melt/fluids should be abundant in melting zones at deep-crustal levels too. We propose that these fluids may provide a connecting link between lower and upper crustal magmas,and a highly efficient transport mechanism for usually melt incompatible elements. In this paper, we explore the unique features of this fluid which allow the partitioning of variouselements and compounds, potentially up to extreme levels,and may explain various features both of mineralization and the magmas that produced them.
基金Project supported by the National Natural Science Foundation of China (40873015)the Eleventh Five-Year Scientific and Technological Project of Anhui Province,China (08010302062)
文摘Rare earth element （REE） concentrations of two different types of groundwaters （high SO42–water-SW and high alkaline waterCW） from coal bearing aquifer （–400~–280 m） in Renlou coal mine,northern Anhui Province,China were measured.The results indicated that they had different REE characteristics： the total concentrations of REEs （ΣREE） of SW were lower than those of CW in general although they all had heavy REEs enriched relative to light REEs.The dissolved REE inorganic species of SW included Ln3＋,LnCO3＋,LnSO4＋,Ln（CO3）2– and Ln（SO4）2–,whereas the CW are Ln（CO3）2– and LnCO3＋ dominant,and the proportions of Ln（CO3）2– increased while other species decreased with pH increasing.Combined with correlation analysis,the enrichment and fractionation of SW （low alkaline water） were considered to be affected by alkaline concentrations via affecting the types and proportions of REE inorganic species.However,the effect of alkaline concentrations to the enrichment and fractionation of REEs of CW （high alkaline water） was less important than total dissolved solids and pH,which reflected the contribution from different rocks they flowed over,different degrees of water-rock interactions and/or REE solid-liquid partition coefficients.
文摘In the east coast Peninsular Malaysia region,sediments are transported by several rivers from the east Malaysia into the South China Sea estuary.In the vicinity of the five river estuaries core sediments were collected in order to investigate rare earth elements(REEs) profile.Core sediments were divided into strata of between 2 to 4 cm intervals and prepared for analyzing by ICP-AES.REE concentrations of 54.3 μg/gr at 24–26 cm in EC4 increased to 114.1 μg/gr at 20–22 cm in EC5.The measured concentration of ...
基金Project supported by the National Natural Science Foundation of China(21477042,21377042)the Natural Science Foundation of Fujian Province(2016J01065)
文摘Concentrations of sixteen rare earth elements（REEs） in PM2.5 and potential-source samples, collected in Nanchang city in mid-September 2013, were determined by inductively coupled plasma mass spectrometry（ICP-MS）. The results showed that the concentrations of total REEs（ΣREE） ranged from 78.76 to 1351 ng/mg. The order of REEs in PM2.5 samples showed the anthropogenic effects, Ce and Eu were affected more than the other REEs according to the enrichment factors. The results of chondrite-normalized REEs patterns and characteristic parameters showed evident light REEs fractionation, and positive anomalies of Ce and Eu in PM2.5. The other non-local pollution sources affected the PM2.5 samples, according to the triangular diagram of La, Ce and Sm compositions and plot of ΣREE vs δEu. Moreover, plot of（La/Sm）N vs（Gd/Yb）N revealed the effects of local sources. In conclusion, the REEs in potential-source samples were close to the background of local soil, while the REEs in PM2.5 samples in Nanchang city were jointly affected by the investigated local sources and other non-local sources.
基金Project supported by National Natural Science Foundation of China (40930740)
文摘The objective of this study was to investigate the vertical distribution of rare earth elements （REEs） in a natural wetland soil core to understand the influence of natural and anthropogenic activities on geochemical behavior of REEs. A natural wetland soil core of 95 cm was collected from the Sanjiang Plain in China and sliced into 5 cm slices for analyses of REEs, Fe, Al, Mn, Sc, Y, and soil organic matter （SOM）. Results indicated that SOM was accumulated in the upper part of the soil core （0 to 20 cm depth）, while Fe and Mn was reductively leached from the upper part of the soil core and accumulated in the low part. The content of total REEs ranged from 137.9 to 225.9 mg/kg in the soil core. Content profiles obtained for all REEs were almost identical except for Ce. The highest contents of REEs generally occurred at about 20 cm depth, but enrichment factor （EF） of REEs except Ce was usually the highest in the surface horizon. Average EF ranged from 1.1 for La to 2.1 for Gd. The pronounced shift in EF occurred at about 40 cm depth and it gradually increased from 40 cm depth to surface （except for Ce）, probably suggesting anthropogenic atmospheric deposition of REEs. In comparison with chondrite, Eu was depleted in all horizons, while Ce was negatively anomalous in the top horizons and positively anomalous in the bottom horizons. This positive anomaly of Ce in the bottom horizons was due to its preferential adsorption on Fe and Mn oxides, relative to other REEs. Although both natural and anthropogenic activi-ties influence the geochemical behaviors of REEs in soils, enrichment or mobility of REEs is low in the natural wetland soil core of the San-jiang Plain.
基金Project supported by the National Natural Science Foundation of China (40372047, 50164001)
文摘The phosphorite ores-deposits rich in rare earth elements(REE) in Zhijin, Xinhua, Guizhuo occurs in the early Cambrian Meishucun and at the bottom part of Qiongzhusi stage (the upper layer of phosphorites), belonging to Yangzi stratum section. The living creature scraps was proved existent in dolomitic-phosphorites by experiments, The REE could be extracted to provide the worthy data for the further using. Adopting the HNO3 to extract REE, through the ion exchange method, the REE recovery rate could be reached 85.44% , having certain reference value.
基金The National Natural Science Foundation of China under contract Nos 40473024 and 40343019the research fund from State Key Laboratory for Mineral Deposits Research in Nanjing University under contract No.20-15-07+3 种基金the Investigation and Development of Marine Resources during the 12th Five Year Plan Project under contract No.DY125-13-R-05the Doctoral Program of Higher Education Research Fund under contract Nos 20040558049 and 20120171130005the Project of High Level Talents in Colleges of Guangdong Province(2011)the Fundamental Research Funds for Central Universities under contract Nos 16lgjc11,12lgjc05 and 09lgpy09
文摘Ferromanganese crusts and nodules are important submarine mineral resources that contain various metal elements with significant economic value. In this study, polymetallic crusts and nodules obtained from the South China Sea （SCS） were determined by using X-ray power diffraction （XRD）, Raman spectroscopy （RS）, Fourier transform infrared spectroscopy （FTIR）, and X-ray photoelectron spectroscopy （XPS） to systematically investigate and analyze the mineralogical and spectral characteristics of the Fe-Mn minerals. XRD measurements revealed that the SCS polymetallic crusts and nodules were composed of vernadite, quartz, and plagioclase. The nodules also contained todorokite. The Fe-phase minerals of the SCS crusts and nodules were composed of amorphous Fe oxide/hydroxide, and the Mn- and Fe-phases minerals exhibited relatively poor degrees of crystallization. FTIR results showed that the Fe-Mn minerals in the crusts and nodules included a large number of surface hydroxyl groups. These surface hydroxyl groups contained protons that could provide reactive sites for complexation of ore-forming elements in seawater. XPS results indicated that the surfaces of the Fe-Mn minerals mainly contained Fe, Mn, and O. Fe was present in the trivalent oxidation state, while Mn, which may contain several bivalent oxidation state, was present in the tetravalent and trivalent oxidation states. The SCS polymetallic crusts and nodules were compared with Pacific seamount crusts, and results showed that the surface hydroxyl （-OH） groups of the SCS crusts and nodules numbered more than the lattice oxygen （O^2-）. But the lattice oxygen of Pacific seamount crusts numbered more than the surface hydroxyl groups. This characteristic indicated that the degree of crystallization of Fe-Mn minerals from the Pacific Ocean was higher than that of minerals from the South China Sea. Comprehensive studies showed that ore-forming elements in the interface between seawater and the Fe-Mn minerals in the submarine ferromanganese crusts and nodules employed the following enrichment mechanisms： （1） the metal ion complexed with the surface hydroxyl of Fe-Mn minerals to form hydroxyl complexes, which were connected by coordination bonds or stable inner-sphere complexes that exchanged protons on the mineral surfaces; （2） the charged surfaces of the minerals and metal cations formed outer-sphere complexes, which made up the electrostatic double layer, through electrostatic adsorption; and （3） the metal cations isomorphously exchanged the Mn and Fe ions of the mineral lattice structure.
基金the R&D Project on the Oceanic Metalliferous Nodue during the "Ninth- Five- YearPlan"(No. DY95 ~ 02 ~ 10).
文摘Compared to North American shale composition (NASC), REE contents of sediments from the CC area in the Pacific Ocean are obviously high except that cerium has equal content to that of NASC. Three-valence rare earth elements were completely enriched in phosphate-phase and cerium in iron-phase. Rare earth elements in the sediments were originally derived from seawater. During lithi- genic and minerogenic processes of metalliferous nodules, three-valence rare earth elements in sediments mobilized and incorporated into sediments as authigenous biogenic-apatite, while cerium had change from Ce3+ to Ce4+ and directly precipitated from seawater and entered metalliferous nodules and caused Ce anomalies in REE pattern in sediments.
文摘The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen content and trace elements' characters. One coefficient of Meij was also improved to more directly show element enrichment in combustion products. These elements may be classified into three groups according to their distribution: Group 1: Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2 Cr has properties of both group 1 and 3 In addition, the smaller diameter of fly ash, the more relative enrichment of trace elements(except Mn). The fly ash showed different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not always improve the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Trace elements should be classified in accordance with factors.
基金Project supported by National Natural Science Foundation of China(51674292)Fundamental Research Funds for the Central Universities of Central South University(2019zzts434)。
文摘Three-dimensional(3D)graphene oxide-tris(4-aminophenyl)amine(GO-TAPAx:y)composites with different GO-to-TAPA mass ratios(x:y)were prepared by a facile one-step ultrasonic treatment.GOTAPAx:y composites were characterized by scanning electron microscopy(SEM),nitrogen(N2)adsorption-desorption isotherms,Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermogravimetric analysis(TGA).Behavior and mechanism of GO-TAPAx:yco mposites for the adsorption of rare earth elements(REEs)were investigated.The adso rption capacities of GO-TAPA1;2 composite for Yb^3+,Er^3+,Nd^3+,La^3+and Y^3+are 30.88,26.52,20.60,11.24 and 10.52 mg/g,respectively.Effects of some important parameters including GO-to-TAPA mass ratios,contact time,reaction temperature and initial Yb^3+concentration on the adsorption were evaluated in detail.FTIR spectral and XPS analyses show that the metal complexations and ion exchanges between nitrogen/oxygen-containing species of the adsorbents and REEs are involved in the adsorption procedure besides the conventional adsorption based on specific surface area,indicating the introduction of specific molecules onto GO is beneficial to its adsorption ability.The convenient reusability and applicability of GO-TAPAx:y composites toward real samples also demonstrate their feasibility in the enrichment of REE ions.
文摘Soil heavy metal pollution is one of the main environmental problems in Pearl River Delta Economic?Zone of China. Based on multi-purpose regional geochemical survey, regional eco-geochemical assessment, local eco-geochemical assessment and comprehensive appraisal, the eco-geochemical survey and assessment in Pearl River Delta Economic Zone of 41,698 km2?were completed. Samples from soils were collected in accordance with the two-layer grid method. Totally 54 elements and indicators for soils were determined. Compared to deep soils, the sampled surface soils are enriched in OrgC, N, P, Cd, S,Hg, Ag, B, Au, S and poor with As, Ni, I, Co, Cr, V, MgO, Sc, Al2O3, Fe2O3?etc. The characteristics of geochemical reference value of element in soil that inherited soil parent material and regional elements combined features reflected that the elements enriched in the soil was interrelated with acid rock, sandstone and shale. The spatial distribution characteristics of element regional geochemistry were conditional by regional environmental geological conditions,and effected by human activities. The Pearl River Delta plain is a typical geochemical landscape area with regional anomaly of multiple-elements. The north, western and eastern parts of the Pearl River Delta Economic Zone are quite different in geochemical features due to regional geological background, soil parent materials, geomorphic characteristics and human activities. Environment quality evaluation results show that the grade I and grade II soil accounted for 19.9% and 57.3% of the total area. Many samples that widely distributed in the economic developed of Pearl River Delta Plain area reached the third-grade of national soil environment standard. The soil enriched in Cd, Hg, As, and the area ratio accounting for 22.8% of the total area. It is mainly controlled by the geochemical background, the Pearl River Delta formation evolution process, especially the marine transgression process lead to Cd, Cu, Zn and Pb enrichment in Pearl River Delta plain. At the same time, under the influence of higher pressure of human activities, all kinds of exogenous input material carrying heavy metal pollutants on soil environmental quality also could not to ignore.
