High-resolution landslide images are required for detailed geomorphological analysis in complex topographic environment with steep and vertical landslide distribution.This study proposed a vertical route planning meth...High-resolution landslide images are required for detailed geomorphological analysis in complex topographic environment with steep and vertical landslide distribution.This study proposed a vertical route planning method for unmanned aerial vehicles(UAVs),which could achieve rapid image collection based on strictly calculated route parameters.The effectiveness of this method was verified using a DJI Mavic 2 Pro,obtaining high-resolution landslide images within the Dongchuan debris flow gully,in the Xiaojiang River Basin,Dongchuan District,Yunnan,China.A three-dimensional(3D)model was constructed by the structure-from-motion and multi-view stereo(SfM-MVS).Micro-geomorphic features were analyzed through visual interpretation,geographic information system(GIS),spatial analysis,and mathematical statistics methods.The results demonstrated that the proposed method could obtain comprehensive vertical information on landslides while improving measurement accuracy.The 3D model was constructed using the vertically oriented flight route to achieve centimeter-level accuracy(horizontal accuracy better than 6 cm,elevation accuracy better than 3 cm,and relative accuracy better than 3.5 cm).The UAV technology could further help understand the micro internal spatial and structural characteristics of landslides,facilitating intuitive acquisition of surface details.The slope of landslide clusters ranged from 36°to 72°,with the majority of the slope facing east and southeast.Upper elevation levels were relatively consistent while middle to lower elevation levels gradually decreased from left to right with significant variations in lower elevation levels.During the rainy season,surface runoff was abundant,and steep topography exacerbated changes in surface features.This route method is suitable for unmanned aerial vehicle(UAV)landslide surveys in complex mountainous environments.The geomorphological analysis methods used will provide references for identifying and describing topographic features.展开更多
In China,numerous cities are expanding into sloping land,yet the quantitative distribution patterns of urban built-up land density along the slope gradient remain unclear,limiting the understanding of sloping land urb...In China,numerous cities are expanding into sloping land,yet the quantitative distribution patterns of urban built-up land density along the slope gradient remain unclear,limiting the understanding of sloping land urbanization.In this paper,a simple negative exponential function was presented to verify its applicability in 19 typical sloping urban areas in China.The function fits well for all case urban areas(R^(2)≥0.951,p<0.001).The parameters of this function clearly describe two fundamental attributes:initial value a and decline rate b.Between 2000 and 2020,a tends to increase,while b tends to decrease in all urban areas,confirming the hypothesis of mutual promotion between flatland densification and sloping land expansion.Multiple regression analysis indicates that the built-up land density and the ruggedness of background land can explain 70.7%of a,while the average slope ratio of built-up land to background land,the built-up land density and the built-up land area can explain 82.1%of b.This work provides a quantitative investigative tool for distribution of urban built-up land density along slope gradient,aiding in the study of the globally increasing phenomenon of sloping land urbanization from a new perspective.展开更多
Mineral fulvic acid(MFA)was used as an eco-friendly pyrite depressant to recover chalcopyrite by flotation with the use of the butyl xanthate as a collector.Flotation experiments showed that MFA produced a stronger in...Mineral fulvic acid(MFA)was used as an eco-friendly pyrite depressant to recover chalcopyrite by flotation with the use of the butyl xanthate as a collector.Flotation experiments showed that MFA produced a stronger inhibition effect on pyrite than on chalcopyrite.The separation of chalcopyrite from pyrite was realized by introducing 150 mg/L MFA at a pulp pH of approximately 8.0.The copper grade,copper recovery,and separation efficiency were 28.03%,84.79%,and 71.66%,respectively.Surface adsorption tests,zeta potential determinations,and localized electrochemical impedance spectroscopy tests showed that more MFA adsorbed on pyrite than on chalcopyrite,which weakened the subsequent interactions between pyrite and the collector.Atomic force microscope imaging further confirmed the adsorption of MFA on pyrite,and X-ray photoelectron spectroscopy results indicated that hydrophilic Fe-based species on the pyrite surfaces increased after exposure of pyrite to MFA,thereby decreasing the floatability of pyrite.展开更多
Tin is a critical metal for various industries,making its recovery from low-grade cassiterite ores crucial.This study aimed to optimize the flotation recovery of cassiterite using multi-component collector systems.Sev...Tin is a critical metal for various industries,making its recovery from low-grade cassiterite ores crucial.This study aimed to optimize the flotation recovery of cassiterite using multi-component collector systems.Several collectors were initially selected through micro-flotation tests,leading to the identification of optimal proportions for a four-component collector system(SHA-OHA-SPA-DBIA in a 4:3:2:1 ratio).Molecular dynamics simulations and surface tension tests were used to investigate the micellar behavior of these collectors in aqueous solution.The adsorption characteristics were quantified using microcalorimetry,enabling the determination of collection entropy and changes in Gibbs free energy.The four-component collector system showed the highest entropy change and the most favorable Gibbs free energy,leading to a cassiterite recovery of above 90%at a concentration of 8.0×10^(5)mol/L.Various analytical techniques were employed to systematically characterize the adsorption mechanism.The findings revealed a positive correlation between the adsorption products formed by the multicomponent collectors on the cassiterite surface and the entropy changes.Industrial-scale testing of the high-entropy collector system produced a tin concentrate with an Sn grade of 6.17%and an Sn recovery of 82.43%,demonstrating its substantial potential for practical applications in cassiterite flotation.展开更多
Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly as...Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly ash paste.We conducted mechanical tests and numerical simulations to understand the evolution of microstructure,and used environmental scanning electron microscopy(ESEM)and energy dispersive spectroscopy(EDS)techniques to analyze the microenvironments of the samples.The mechanical properties of fly ash paste under different activation conditions and the changes in the microstructure and composition were investigated.The results revealed that under conditions of low NaOH content(1%-3%),the strength of the sample increased significantly.When the content exceeded 4%,the rate of increase in strength decreased.Based on the results,the optimal NaOH content was identified,which was about 4%.A good activation effect,especially for short-term activation(3-7 d),was achieved using TEA under high doping conditions.The activation effect was poor for long-term strength after 28 days.The CaO content did not significantly affect the degree of activation achieved.The maximum effect was exerted when the content of CaO was 2%.The virtual cement and concrete testing laboratory(VCCTL)was used to simulate the hydration process,and the results revealed that the use of the three types of activators accelerated the formation of Ca(OH)_(2) in the system.The activators also corroded the surface of the fly ash particles,resulting in a pozzolanic reaction.The active substances in fly ash were released efficiently,and hydration was realized.The pores were filled with hydration products,and the microstructure changed to form a new frame of paste filling that helped improve the strength of fly ash paste.展开更多
1.Objective.The Yidun arc within the Tethys-Himalaya metallogenic belt formed during the westward subduction of the Ganzi-Litang Ocean(237-206 Ma)during the Indosinian period,and then underwent the evolution stages of...1.Objective.The Yidun arc within the Tethys-Himalaya metallogenic belt formed during the westward subduction of the Ganzi-Litang Ocean(237-206 Ma)during the Indosinian period,and then underwent the evolution stages of the collisional orogeny(206-138 Ma)and the post-collisional orogeny(135-75 Ma).In recent years,a series of large and medium-sized Late Yanshanian intracontinental porphyry-skarn Mo-Cu-W deposits have been discovered in the southern part of the Yidun arc,including Xiuwacu,Relin,Hongshan,Tongchanggou,and Donglufang(Fig.1a).展开更多
Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosph...Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosphogypsum.However,pipe plugging,which is caused by the poor workability of HPG-based filling materials,has become a major safety hazard in the filling process.Determining an economical and practicable method is urgently needed to improve the workability of HPG slurry work.First,this work found that grind-ing treatment was much more effective than increasing concentration(59wt%-65wt%)and adding tailings(20wt%-100wt%)in enhan-cing the workability of HPG slurry based on a comprehensive analysis of water retention,fluidity,and flow stability.Then,the combined effects of particle size,particle morphology,water film,and interparticle interactions on the workability of HPG slurry were quantitat-ively described through a microanalysis.Moreover,the first direct evidence for the transformation from robust embedded structures to soft stacking structures was presented.In practice,the filling materials should be prepared by grinding HPG for 20 min and mixing with 0-200wt%phosphorus tailings to achieve satisfactory workability and mechanical performance.The results of this study provide practic-al and feasible methods for addressing the stable transportation problem of HPG slurry.展开更多
This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably d...This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably decreased,while the impact on scheelite was negligible,resulting in a recovery difference of 82.53%.Fourier transform infrared(FTIR)spectroscopy and atomic force micro-scopy(AFM)analyses indicated the selective adsorption of KGM on the calcite surface.Test results of the zeta potential and UV-visible absorption spectroscopy revealed that KGM prevented the adsorption of sodium oleate on the calcite surface.X-ray photoelectron spec-troscopy(XPS)analysis further confirmed the chemical adsorption of KGM on the calcite surface and the formation of Ca(OH)_(2).The density functional theory(DFT)simulation results were consistent with the flotation tests,demonstrating the strong adsorption perform-ance of KGM on the calcite surface.This study offers a pathway for highly sustainable and cost-effective mineral processing by utilizing the unique properties of biopolymers such as KGM to separate valuable minerals from gangue minerals.展开更多
The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified i...The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified in the region via exploration.However,metallogenic sources and evolution of W remain unclear,and the existing metallogenic model has to be updated to guide further ore prospecting.Elemental and Sr-Nd isotopic data for scheelites assist in the determination of sources and evolution of the W-mineralizing fluids and metals in the district.Based on field geological survey,the scheelites in the Gejiu district can be categorized into three types:altered granite(Type Ⅰ),quartz vein(Type Ⅱ)from the Laochang deposit,and skarn(Type Ⅲ)from the Kafang deposit.Types Ⅰ and Ⅱ scheelites have low molybdenum(Mo)and strontium(Sr)contents,and Type Ⅱ scheelite has lower Sr contents than Type Ⅰ as well as higher Mo and Sr contents than Type Ⅲ scheelites.Varying Mo contents across the scheelite types suggests that the oxygen fugacity varied during ore accumulation.Type Ⅰ and Type Ⅱ scheelites exhibit similar rare earth elements(REE)patterns;Type Ⅲ scheelite contains lower REE content,particularly HREE,compared with the other scheelites.All scheelites exhibit negative Eu anomalies in the chondrite-normalized REE patterns.As the W-mineralization and two-mica granite share close spatial and temporal relationships,the negative Eu anomalies were likely inherited from the two-mica granite.Type Ⅰ and Type Ⅱ scheelites display varied(^(87)Sr/^(86)Sr)_(82 Ma)(0.7090-0.7141)andε_(Nd)(82 Ma)(from−9.9 to−5.4)values,similar to those of granite.However,Type Ⅲ scheelite exhibits lower(^(87)Sr/^(86)Sr)_(82 Ma)(0.7083-0.7087)and lowerε_(Nd)(82 Ma)(from−10.5 to−6.9)values than the two-mica granite.This indicates that the two-mica granite alone did not provide the ore-forming fluids and metals and that the Type Ⅲ scheelite ore-forming fluids likely involved external fluids that were probably derived from carbonate rocks.The implication is that highly differentiated two-mica granites were the source of primary W-bearing metals and fluids,which is consistent with earlier research on the origin of Sn ore-forming materials.展开更多
Hemimorphite exhibits poor floatability during sulfidization flotation.Cu^(2+)and Pb^(2+)addition enhances the reactivity of the hemimorphite surface and subsequently improves its flotation behavior.In this study,the ...Hemimorphite exhibits poor floatability during sulfidization flotation.Cu^(2+)and Pb^(2+)addition enhances the reactivity of the hemimorphite surface and subsequently improves its flotation behavior.In this study,the mechanisms of Cu^(2+)Pb^(2+)adsorption onto a hemimorphite surface were investigated.We examined the interaction mechanism of xanthate with the hemimorphite surface and observed the changes in the mineral surface hydrophobicity after the synergistic activation with Cu^(2+)Pb^(2+).Microflotation tests indicated that individual activation with Cu or Pb^(2+)increased the flotation recovery of hemimorphite,with Pb^(2+)showing greater effectiveness than Cu^(2+).Meanwhile,synergistic activation with Cu^(2+)Pb^(2+)considerably boosted the flotation recovery of hemimorphite.Cu^(2+)and Pb^(2+)were both adsorbed onto the hemimorphite surface,forming an adsorption layer containing Cu or Pb.Following the synergistic activation with Cu^(2+)+Pb^(2+),the activated layer on the hemimorphite surface consisted of Cu and Pb and a larger amount of the active product compared with the surface activated by Cu^(2+)or Pb^(2+)alone.In addition,xanthate adsorption on the hemimorphite surface increased noticeably after synergistic activation with Cu^(2+)Pb^(2+),suggesting a vigorous reaction between xanthate and the activated minerals.Therefore,synergistic activation with Cu^(2+)Pb^(2+)effectively increased the content of active products on the hemimorphite surface,thereby enhancing mineral surface reactivity,promoting collector adsorption,and improving surface hydrophobicity.展开更多
To investigate the influence of different joint conditions on the rockburst of a circular tunnel,a true-triaxial test of rockburst with a single set of joint conditions was conducted.The rockburst incubation and evolu...To investigate the influence of different joint conditions on the rockburst of a circular tunnel,a true-triaxial test of rockburst with a single set of joint conditions was conducted.The rockburst incubation and evolution characteristics and acoustic emission evolution characteristics under different joint directions and joint dip angles were studied.The Weibull function was used to fit rockburst debris with different particle sizes and a single set of joints to obtain statistical results.The experimental results revealed that shear fracture rockburst occurred in samples with joints aligned with the tunnel strike as well as joints with inclination angles of 45°,60°,and 90°.Slab buckling–shear fracture rockburst was more likely to occur in samples with inclination angles of 0°and 30°.Slab buckling–shear fracture rockburst occurred in samples with joints crossing the tunnel strike as well as in samples with joints with inclination angles of 0°,30°,45°,60°,and 90°.The location of the rockburst pit was influenced by the joint inclination angle when the joints aligned with the tunnel strike.In contrast,when the joints crossed the tunnel strike,the location of the rockburst pit was independent of the joint inclination angle.The cumulative absolute energy of acoustic emission(AE)exhibited an overall upward trend with the increase in joint dip angle.The cumulative absolute energy of the AE of the jointed samples was greater than that of intact samples(without joints).Loading reached the rockburst stage in the samples with joints aligned with the tunnel strike and dip angles of 45°,60°,and 90°.Moreover,the peak value of AE cumulative absolute energy was the highest.These results can elucidate the evolution mechanism of rockburst in the surrounding rock of circular tunnels with a single set of joints in deep underground engineering.展开更多
The Guanfang large-scale W deposit is located in the W polymetallic ore concentration area of Bozhushan in southeastern Yunnan,China.Despite extensive research,the fluid evolution process of the deposit remains ambigu...The Guanfang large-scale W deposit is located in the W polymetallic ore concentration area of Bozhushan in southeastern Yunnan,China.Despite extensive research,the fluid evolution process of the deposit remains ambiguous,leading to controversy regarding its genesis.This study conducted a detailed field geological survey,with systematic sampling of the KT6 orebody,to delineate mineralization stages.Fine mineralogy work,including the use of CL images of scheelite,in-situ LA-ICP-MS trace elements,and Sr isotopes,was carried out on diff erent generations of scheelite formed in various stages.The findings identified the evolution of fluids in the mineralization process,shedding light on the genesis of the deposit.The study revealed four mineralization stages at the Guanfang W deposit:prograde skarn stage,retrograde skarn stage,quartz-sulfide stage,and carbonate-fluorite stage.Diff erent generations of scheelite(Sch I,Sch II,Sch III)were observed in the first three stages,displaying distinct chondrite-normalized REE patterns.The REE of Sch I mainly substituted into the Ca site by REE^(3+)+□_(Ca),and there may be a similar substitution of Nb for REE,whereas it is not the main substitution method.The REE of Sch II mainly enter the scheelite lattice in the form of REE 3++Na+,and there may be a substitution of Nb for REE isomorphism.In the early stage,The REE of Sch III was mainly replaced by Nb for REE isomorphism,while in the later stage,the replacement mode of REE^(3+)+□_(Ca)coexisted with it.The Mo content in scheelite,along with the corresponding Eu anomalies in both scheelite and garnet,collectively imply that the ore-forming fluids during various mineralization stages were predominantly oxidizing,with only slight reducibility observed in Sch II.The in-situ Sr isotope ratios of scheelite concentrates ranged from 0.7093 to 0.7153,resembling those of the Bozhushan granite,indicating a relationship between W mineralization and granite.In addition,the Y/Ho ratios of scheelite from various mineralization stages exhibit a narrow range(19-31),with a pronounced correlation between the contents of Y and Ho and a similar trend in their variation.This consistency suggests that the Guanfang deposit has undergone a uniform or comparable evolutionary process,implying a stable ore-forming fluid across diff erent mineralization stages.展开更多
Flotation behavior of stibiconite after sulfidation roasting with sulfur at a high temperature and the sulfidation mechanisms were investigated by ultraviolet spectrophotometry,X-ray diffraction(XRD)combining with the...Flotation behavior of stibiconite after sulfidation roasting with sulfur at a high temperature and the sulfidation mechanisms were investigated by ultraviolet spectrophotometry,X-ray diffraction(XRD)combining with thermodynamic calculation,X-ray photoelectron spectroscopy(XPS)and electron probe microanalysis(EPMA).The XRD and thermodynamic analyses revealed that the Sb_(3)O_(6)(OH)was reduced into Sb_(2)O_(4)and Sb_(2)O_(3),and was transformed into Sb_(2)S_(3)after introducing sulfur at high temperatures.Flotation test results show that flotation recovery of the stibiconite after sulfidation reaches 90.3%.Ultraviolet spectrophotometry tests confirm that adsorption capacity of sodium butyl xanthate(SBX)on surface of the roasted products has a positive relationship with S/Sb mole ratio.XPS analyses indicate that Sb-bearing species including mainly Sb_(2)S_(3),Sb_(2)O_(3)and Sb_(2)(SO_(4))_(3) are formed at the surface of particle after sulfidation.The EPMA analyses verify that the Sb_(2)S_(3)is generated at the outer layer of sample after sulfidation roasting,but the particle interior is mainly composed of antimony oxides.The sulfur atmosphere induces the outward migration of oxygen to form Sb_(2)O_(4).Then,the Sb_(2)O_(4)is transformed into Sb_(2)O_(3)in two pathways,and the Sb_(2)S_(3)is formed.These findings will provide theoretical support for recovering antimony from antimony oxide ores by xanthate flotation methods.展开更多
The strength of backfill body is a crucial parameter in backfilling mining,and the failure process of cemented backfill body is essentially an energy dissipation process.To investigate the effects of curing age and ce...The strength of backfill body is a crucial parameter in backfilling mining,and the failure process of cemented backfill body is essentially an energy dissipation process.To investigate the effects of curing age and cement-sand ratio on the strength and energy consumption of backfill,whole tailings were used as aggregate to prepare slurry with mass concentration of 74%,and the slurry with cement-sand ratio of 1:4,1:6,1:8 and 1:12 was poured into backfill.Uniaxial compression tests were conducted on backfill body specimens that had been cured for 7 days,14 days,28 days,and 45 days.It aims at studying the compressive strength,damage,energy storage limit,energy dissipation,and crack propagation of the fill.The results show that when the cement-sand ratio is held constant,the strength of the backfill increases with curing age.Simultaneously,when the curing age is fixed,the strength is positively correlated with the cement-sand ratio.During uniaxial compression tests,it is observed that the pre-peak energy consumption,post-peak energy consumption,total energy consumption,and unit volume strain energy of the cemented backfill body exhibit exponential relationships with both curing age and cement-sand ratio.The energy storage limit of the backfill reflects its capacity to absorb energy prior to failure,while the relationship between damage and energy consumption provides an accurate depiction of its internal failure mechanisms at different stages.In the failure process of the cemented backfill body,primary cracks accompany secondary cracks,many microcracks initiate and propagate from the stress direction,and crack propagation consumes a significant amount of energy.This study on the strength,energy storage limit,and failure of the cemented backfill body can provide valuable insights for mine safety production.展开更多
The western margin of the Yangtze Block hosts diverse Neoproterozoic igneous rocks,with exposed S-type granites serving as key indicators for deciphering regional geological evolution.This study focuses on the Jiudaow...The western margin of the Yangtze Block hosts diverse Neoproterozoic igneous rocks,with exposed S-type granites serving as key indicators for deciphering regional geological evolution.This study focuses on the Jiudaowan granite pluton,located on the western margin of the Yangtze Block,through systematic petrographic,whole-rock geochemical,zircon and monazite U-Pb geochronology,and whole-rock Nd isotopic analyses aiming to elucidate its petrogenesis and tectonic significance.The Jiudaowan granite pluton is a composite body,consisting of the Luotaijiu,Jiudaowan,and Daheishan units,characterized by biotite monzogranites,muscovite-plagioclase granites,and two-mica monzogranites,respectively.LA-ICP-MS zircon and monazite U-Pb dating reveals crystallization ages between 832 and 798 Ma.The three units are peraluminous,containing minerals such as muscovite,garnet,and tourma-line,and exhibiting high SiO_(2)(72.99-77.83 wt%),Al_(2)O_(3)(12.36-15.02 wt%),and A/CNK values(1.06-1.43),con-firming their classification as peraluminous S-type granites.Compositional variations within the Jiudaowan granite pluton are primarily controlled by protolith composition and melting mechanisms.The pluton is distinguished by low CaO/Na_(2)O ratios(0.02-0.18),high Rb/Sr(0.83-113)and Rb/Ba(0.33-15.2)ratios,and negativeεNd(t)values(−13.6 to−9.1),indicating derivation from partial melting of het-erogeneous metasedimentary sources.MgO,TiO_(2),Rb/Sr,and whole-rock Zr saturation temperatures suggest that the Luotaijiu and Daheishan units formed via biotite dehydration melting,whereas the Jiudaowan unit resulted from muscovite dehydration melting.Additionally,the Jiudaowan granite pluton displays a clear negative correlation between Al_(2)O_(3),CaO,Fe_(2)O_(3)T,MgO,TiO_(2),and SiO_(2),along with pronounced Eu negative anomalies and depletions in Sr and Ti,suggesting fractional crystallization of feldspar,mica,and Fe-Ti oxides during magma emplacement.Similarly,variable incompatible element ratios of Nb/U(1.07-18.97)and Nb/La(0.24-26.88)further indicate minor crustal assimilation and contamination during magma evolution.Integrating regional geological data,we propose that the Jiudaowan pluton formed during crustal thickening associated with post-collisional extension,likely related to the breakup of the Rodinia supercontinent.展开更多
A partly clumped-particles combined with joint planes model was developed to simulate the microstructure of quartz mica schist.It considers grain-scale heterogeneity including microgeometry heterogeneity and grain-sca...A partly clumped-particles combined with joint planes model was developed to simulate the microstructure of quartz mica schist.It considers grain-scale heterogeneity including microgeometry heterogeneity and grain-scale elastic heterogeneity.Clumped-particles with larger volume and larger stiffness were used to represent stiff minerals such as quartz,the rest of unclumped particles with smaller stiffness were used to represent soft minerals such as mica.The joint planes,which have smaller stiffness and strength than mica,were used to describe schist.The extensive sensitivity studies have shown that the clump’s radius,clump’s content and joint plane’s strength affect the microscopic and macroscopic behaviors of sample.For DanBa quartz mica schist,the model calibrated uniaxial tests and well matched with the stress-strain curves,crack initiation stress and crack damage stress of laboratory test.展开更多
The Bainiuchang Ag-polymetallic ore deposit,located in southeastern Yunnan,China,is one of the region's largest deposits.However,the hyp abyssal granite porphyry within this mining area has yet to be comprehensive...The Bainiuchang Ag-polymetallic ore deposit,located in southeastern Yunnan,China,is one of the region's largest deposits.However,the hyp abyssal granite porphyry within this mining area has yet to be comprehensively investigated.In this study,we conducted geochemical,geochronological,whole-rock Sr-Nd isotope,and zircon Hf isotope analyses on granite porphyry samples collected from the Bainiuchang deposit.The results indicate that the granite porphyry formed between 87.5 and 87.4 Ma in the Late Yanshanian period.Geochemically,the granite is strongly peraluminous,with high silica and alkali contents consistent with S-type granite characteristics.The granite porphyry is enriched in large-ion lithophile elements(Rb,Th,U,and K)and is relatively depleted in Ba and Sr.The initial ^(87)Sr/^(86)Sr ratios are high(0.71392-0.71585),accompanied by low ε_(Nd)(t)values(-8.9 to-8.2).The zircons exhibited similarly low ε_(Hf)(t)values(-9.31 to-3.6).These data suggest that the porphyry-forming magma originated from a continental crustal source.The two-stage Hf and Nd model ages are estimated at 1534-1216 Ma and 1615-1561 Ma,respectively.Thus,the granite porphyry likely formed under a strike-slip extensional setting in the Late Yanshanian period and resulted from the re-melting of Proterozoic basement metagreywackes.This porphyry shares a similar magmatic origin with concealed granite bodies within the deposit and is associated with structural reactivation during the Yanshanian.The findings of this study provide valuable insights into the tectonomagmatic mineralization processes in the B ainiuchang area.展开更多
Three-dimensional(3D)object detection is crucial for applications such as robotic control and autonomous driving.While high-precision sensors like LiDAR are expensive,RGB-D sensors(e.g.,Kinect)offer a cost-effective a...Three-dimensional(3D)object detection is crucial for applications such as robotic control and autonomous driving.While high-precision sensors like LiDAR are expensive,RGB-D sensors(e.g.,Kinect)offer a cost-effective alternative,especially for indoor environments.However,RGB-D sensors still face limitations in accuracy and depth perception.This paper proposes an enhanced method that integrates attention-driven YOLOv9 with xLSTM into the F-ConvNet framework.By improving the precision of 2D bounding boxes generated for 3D object detection,this method addresses issues in indoor environments with complex structures and occlusions.The proposed approach enhances detection accuracy and robustness by combining RGB images and depth data,offering improved indoor 3D object detection performance.展开更多
China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot ...China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot regions, the Guangdong-Hong KongMacao Greater Bay Area(GBA) has undergone a dramatic urban expansion. To better understand forest dynamics and protect forest ecosystem, revealing the processes, patterns and underlying drivers of forest loss is essential. This study focused on the spatiotemporal evolution and potential driving factors of forest loss in the GBA at regional and city level. The Landsat time-series images from 1987 to2017 were used to derive forest, and landscape metrics and geographic information system(GIS) were applied to implement further spatial analysis. The results showed that: 1) 14.86% of the total urban growth area of the GBA was obtained from the forest loss in1987–2017;meanwhile, the forest loss area of the GBA reached 4040.6 km2, of which 25.60%(1034.42 km2) was converted to urban land;2) the percentages of forest loss to urban land in Dongguan(19.14%), Guangzhou(18.35%) and Shenzhen(15.81%) were higher than those in other cities;3) the forest became increasingly fragmented from 1987–2007, and then the fragmentation decreased from2007 to 2017);4) the landscape responses to forest changes varied with the scale;and 5) some forest loss to urban regions moved from low-elevation and gentle-slope terrains to higher-elevation and steep-slope terrains over time, especially in Shenzhen and Hong Kong.Urbanization and industrialization greatly drove forest loss and fragmentation, and, notably, hillside urban land expansion may have contributed to hillside forest loss. The findings will help policy makers in maintaining the stability of forest ecosystems, and provide some new insights into forest management and conservation.展开更多
The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with G...The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with GPS field collected data in the area of Xiaowan-Dachaoshan Reservoirs of Lancangjiang River cascaded Hydropower Area. Consequently, the land-cover is divided into five subclasses, namely water, paddy field and wetland, bare dryland and sparse shrub, secondary forest and density forest. The result showed that the areas of bare land, upland and secondary forest decreased in 1988-1996, whereas from 1996 to 2000, water body and density forest keep invariability while the areas of paddy field and wetland, bare dryland and sparse scrub increasing and the area of secondary forest decrease; Features of reciprocal transformation between density forest and other type of land-cover had two points, i.e. secondary forest, bare dryland and sparse shrub converted to density forest; and density forest converted to secondary forest and paddy field and wetland. It reflects the dynamic variation of density forest; the area which slope less than 8° and greater than 15° shows bigger variation, however, less change in 8°-15°.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 62266026)
文摘High-resolution landslide images are required for detailed geomorphological analysis in complex topographic environment with steep and vertical landslide distribution.This study proposed a vertical route planning method for unmanned aerial vehicles(UAVs),which could achieve rapid image collection based on strictly calculated route parameters.The effectiveness of this method was verified using a DJI Mavic 2 Pro,obtaining high-resolution landslide images within the Dongchuan debris flow gully,in the Xiaojiang River Basin,Dongchuan District,Yunnan,China.A three-dimensional(3D)model was constructed by the structure-from-motion and multi-view stereo(SfM-MVS).Micro-geomorphic features were analyzed through visual interpretation,geographic information system(GIS),spatial analysis,and mathematical statistics methods.The results demonstrated that the proposed method could obtain comprehensive vertical information on landslides while improving measurement accuracy.The 3D model was constructed using the vertically oriented flight route to achieve centimeter-level accuracy(horizontal accuracy better than 6 cm,elevation accuracy better than 3 cm,and relative accuracy better than 3.5 cm).The UAV technology could further help understand the micro internal spatial and structural characteristics of landslides,facilitating intuitive acquisition of surface details.The slope of landslide clusters ranged from 36°to 72°,with the majority of the slope facing east and southeast.Upper elevation levels were relatively consistent while middle to lower elevation levels gradually decreased from left to right with significant variations in lower elevation levels.During the rainy season,surface runoff was abundant,and steep topography exacerbated changes in surface features.This route method is suitable for unmanned aerial vehicle(UAV)landslide surveys in complex mountainous environments.The geomorphological analysis methods used will provide references for identifying and describing topographic features.
基金supported by the project of the National Natural Science Foundation of China entitled“Distribution and change characteristics of construction land on slope gradient in mountainous cities of southern China”(No.41961039).
文摘In China,numerous cities are expanding into sloping land,yet the quantitative distribution patterns of urban built-up land density along the slope gradient remain unclear,limiting the understanding of sloping land urbanization.In this paper,a simple negative exponential function was presented to verify its applicability in 19 typical sloping urban areas in China.The function fits well for all case urban areas(R^(2)≥0.951,p<0.001).The parameters of this function clearly describe two fundamental attributes:initial value a and decline rate b.Between 2000 and 2020,a tends to increase,while b tends to decrease in all urban areas,confirming the hypothesis of mutual promotion between flatland densification and sloping land expansion.Multiple regression analysis indicates that the built-up land density and the ruggedness of background land can explain 70.7%of a,while the average slope ratio of built-up land to background land,the built-up land density and the built-up land area can explain 82.1%of b.This work provides a quantitative investigative tool for distribution of urban built-up land density along slope gradient,aiding in the study of the globally increasing phenomenon of sloping land urbanization from a new perspective.
基金supported by Fundamental Research Projects of Yunnan Province,China(Nos.202101BE070001-009,202301AU070189).
文摘Mineral fulvic acid(MFA)was used as an eco-friendly pyrite depressant to recover chalcopyrite by flotation with the use of the butyl xanthate as a collector.Flotation experiments showed that MFA produced a stronger inhibition effect on pyrite than on chalcopyrite.The separation of chalcopyrite from pyrite was realized by introducing 150 mg/L MFA at a pulp pH of approximately 8.0.The copper grade,copper recovery,and separation efficiency were 28.03%,84.79%,and 71.66%,respectively.Surface adsorption tests,zeta potential determinations,and localized electrochemical impedance spectroscopy tests showed that more MFA adsorbed on pyrite than on chalcopyrite,which weakened the subsequent interactions between pyrite and the collector.Atomic force microscope imaging further confirmed the adsorption of MFA on pyrite,and X-ray photoelectron spectroscopy results indicated that hydrophilic Fe-based species on the pyrite surfaces increased after exposure of pyrite to MFA,thereby decreasing the floatability of pyrite.
基金supported by Yunnan Science and Technology Leading Talent Project(No.202305AB350005)。
文摘Tin is a critical metal for various industries,making its recovery from low-grade cassiterite ores crucial.This study aimed to optimize the flotation recovery of cassiterite using multi-component collector systems.Several collectors were initially selected through micro-flotation tests,leading to the identification of optimal proportions for a four-component collector system(SHA-OHA-SPA-DBIA in a 4:3:2:1 ratio).Molecular dynamics simulations and surface tension tests were used to investigate the micellar behavior of these collectors in aqueous solution.The adsorption characteristics were quantified using microcalorimetry,enabling the determination of collection entropy and changes in Gibbs free energy.The four-component collector system showed the highest entropy change and the most favorable Gibbs free energy,leading to a cassiterite recovery of above 90%at a concentration of 8.0×10^(5)mol/L.Various analytical techniques were employed to systematically characterize the adsorption mechanism.The findings revealed a positive correlation between the adsorption products formed by the multicomponent collectors on the cassiterite surface and the entropy changes.Industrial-scale testing of the high-entropy collector system produced a tin concentrate with an Sn grade of 6.17%and an Sn recovery of 82.43%,demonstrating its substantial potential for practical applications in cassiterite flotation.
基金Supported by Yunnan Major Scientific and Technological Projects(No.202403AA080001)National Natural Science Foundation of China(No.52074137)Yunnan Fundamental Research Projects(No.202201AT070151)。
文摘Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly ash paste.We conducted mechanical tests and numerical simulations to understand the evolution of microstructure,and used environmental scanning electron microscopy(ESEM)and energy dispersive spectroscopy(EDS)techniques to analyze the microenvironments of the samples.The mechanical properties of fly ash paste under different activation conditions and the changes in the microstructure and composition were investigated.The results revealed that under conditions of low NaOH content(1%-3%),the strength of the sample increased significantly.When the content exceeded 4%,the rate of increase in strength decreased.Based on the results,the optimal NaOH content was identified,which was about 4%.A good activation effect,especially for short-term activation(3-7 d),was achieved using TEA under high doping conditions.The activation effect was poor for long-term strength after 28 days.The CaO content did not significantly affect the degree of activation achieved.The maximum effect was exerted when the content of CaO was 2%.The virtual cement and concrete testing laboratory(VCCTL)was used to simulate the hydration process,and the results revealed that the use of the three types of activators accelerated the formation of Ca(OH)_(2) in the system.The activators also corroded the surface of the fly ash particles,resulting in a pozzolanic reaction.The active substances in fly ash were released efficiently,and hydration was realized.The pores were filled with hydration products,and the microstructure changed to form a new frame of paste filling that helped improve the strength of fly ash paste.
基金jointly supported by the Selection Project of High-level Scientific and Technological Talents and Innovative Teams Project in Yunnan Province(202305AT350004-4)the National Natural Science Foundation of China(42362010 and 42464005)+3 种基金the Field Scientific Observation and Research Station of Mountain Agroecosystem in the Lower Reaches of Nujiang River,Yunnan Province(202305AM340031)the Yunnan Provincial Department of Education Science Research Fund Project(2025J0983)the Wen Bang-chun Academician Workstation in Yunnan Province(202205AF150032)the Undergraduate Innovative Training Program(2310603235).
文摘1.Objective.The Yidun arc within the Tethys-Himalaya metallogenic belt formed during the westward subduction of the Ganzi-Litang Ocean(237-206 Ma)during the Indosinian period,and then underwent the evolution stages of the collisional orogeny(206-138 Ma)and the post-collisional orogeny(135-75 Ma).In recent years,a series of large and medium-sized Late Yanshanian intracontinental porphyry-skarn Mo-Cu-W deposits have been discovered in the southern part of the Yidun arc,including Xiuwacu,Relin,Hongshan,Tongchanggou,and Donglufang(Fig.1a).
基金financial support from the National Natural Science Foundation of China(No.52074137)the Yunnan Fundamental Research Projects,China(Nos.202301BE070001-054 and 202401CF070124)the Yunnan Major Scientific and Technological Projects,China(No.202403AA080001).
文摘Hemihydrate phosphogypsum(HPG)-based filling materials have become a new low-cost green alternative for early strength filling materials.They also provide a promising solution for the large-scale utilization of phosphogypsum.However,pipe plugging,which is caused by the poor workability of HPG-based filling materials,has become a major safety hazard in the filling process.Determining an economical and practicable method is urgently needed to improve the workability of HPG slurry work.First,this work found that grind-ing treatment was much more effective than increasing concentration(59wt%-65wt%)and adding tailings(20wt%-100wt%)in enhan-cing the workability of HPG slurry based on a comprehensive analysis of water retention,fluidity,and flow stability.Then,the combined effects of particle size,particle morphology,water film,and interparticle interactions on the workability of HPG slurry were quantitat-ively described through a microanalysis.Moreover,the first direct evidence for the transformation from robust embedded structures to soft stacking structures was presented.In practice,the filling materials should be prepared by grinding HPG for 20 min and mixing with 0-200wt%phosphorus tailings to achieve satisfactory workability and mechanical performance.The results of this study provide practic-al and feasible methods for addressing the stable transportation problem of HPG slurry.
基金supported by the National Natural Science Foundation of China(No.52164022).
文摘This study investigated the effect of konjac glucomannan(KGM)on the flotation separation of calcite and scheelite.Micro-flotation tests showed that under the action of 50 mg/L KGM,the floatability of calcite notably decreased,while the impact on scheelite was negligible,resulting in a recovery difference of 82.53%.Fourier transform infrared(FTIR)spectroscopy and atomic force micro-scopy(AFM)analyses indicated the selective adsorption of KGM on the calcite surface.Test results of the zeta potential and UV-visible absorption spectroscopy revealed that KGM prevented the adsorption of sodium oleate on the calcite surface.X-ray photoelectron spec-troscopy(XPS)analysis further confirmed the chemical adsorption of KGM on the calcite surface and the formation of Ca(OH)_(2).The density functional theory(DFT)simulation results were consistent with the flotation tests,demonstrating the strong adsorption perform-ance of KGM on the calcite surface.This study offers a pathway for highly sustainable and cost-effective mineral processing by utilizing the unique properties of biopolymers such as KGM to separate valuable minerals from gangue minerals.
基金financed by Yunnan Major Scientific and Technological Projects(Grant No.202202AG050006)the National Natural Science Foundation of China(Grant No.42462011)Projects of Yunnan Province Technology Hall(Grant No.202305AT350004).
文摘The Gejiu tin-copper-(tungsten)(Sn-Cu-(W))polymetallic district is located in the southwest of the W-Sn metallogenic belt in the western Youjiang Basin,Yunnan,Southwest China.Abundant W minerals have been identified in the region via exploration.However,metallogenic sources and evolution of W remain unclear,and the existing metallogenic model has to be updated to guide further ore prospecting.Elemental and Sr-Nd isotopic data for scheelites assist in the determination of sources and evolution of the W-mineralizing fluids and metals in the district.Based on field geological survey,the scheelites in the Gejiu district can be categorized into three types:altered granite(Type Ⅰ),quartz vein(Type Ⅱ)from the Laochang deposit,and skarn(Type Ⅲ)from the Kafang deposit.Types Ⅰ and Ⅱ scheelites have low molybdenum(Mo)and strontium(Sr)contents,and Type Ⅱ scheelite has lower Sr contents than Type Ⅰ as well as higher Mo and Sr contents than Type Ⅲ scheelites.Varying Mo contents across the scheelite types suggests that the oxygen fugacity varied during ore accumulation.Type Ⅰ and Type Ⅱ scheelites exhibit similar rare earth elements(REE)patterns;Type Ⅲ scheelite contains lower REE content,particularly HREE,compared with the other scheelites.All scheelites exhibit negative Eu anomalies in the chondrite-normalized REE patterns.As the W-mineralization and two-mica granite share close spatial and temporal relationships,the negative Eu anomalies were likely inherited from the two-mica granite.Type Ⅰ and Type Ⅱ scheelites display varied(^(87)Sr/^(86)Sr)_(82 Ma)(0.7090-0.7141)andε_(Nd)(82 Ma)(from−9.9 to−5.4)values,similar to those of granite.However,Type Ⅲ scheelite exhibits lower(^(87)Sr/^(86)Sr)_(82 Ma)(0.7083-0.7087)and lowerε_(Nd)(82 Ma)(from−10.5 to−6.9)values than the two-mica granite.This indicates that the two-mica granite alone did not provide the ore-forming fluids and metals and that the Type Ⅲ scheelite ore-forming fluids likely involved external fluids that were probably derived from carbonate rocks.The implication is that highly differentiated two-mica granites were the source of primary W-bearing metals and fluids,which is consistent with earlier research on the origin of Sn ore-forming materials.
基金supported by the National Natural Science Foundation of China(Nos.52304291 and 52264026)Yunnan Fundamental Research Projects,China(No.202301AW070018)。
文摘Hemimorphite exhibits poor floatability during sulfidization flotation.Cu^(2+)and Pb^(2+)addition enhances the reactivity of the hemimorphite surface and subsequently improves its flotation behavior.In this study,the mechanisms of Cu^(2+)Pb^(2+)adsorption onto a hemimorphite surface were investigated.We examined the interaction mechanism of xanthate with the hemimorphite surface and observed the changes in the mineral surface hydrophobicity after the synergistic activation with Cu^(2+)Pb^(2+).Microflotation tests indicated that individual activation with Cu or Pb^(2+)increased the flotation recovery of hemimorphite,with Pb^(2+)showing greater effectiveness than Cu^(2+).Meanwhile,synergistic activation with Cu^(2+)Pb^(2+)considerably boosted the flotation recovery of hemimorphite.Cu^(2+)and Pb^(2+)were both adsorbed onto the hemimorphite surface,forming an adsorption layer containing Cu or Pb.Following the synergistic activation with Cu^(2+)+Pb^(2+),the activated layer on the hemimorphite surface consisted of Cu and Pb and a larger amount of the active product compared with the surface activated by Cu^(2+)or Pb^(2+)alone.In addition,xanthate adsorption on the hemimorphite surface increased noticeably after synergistic activation with Cu^(2+)Pb^(2+),suggesting a vigorous reaction between xanthate and the activated minerals.Therefore,synergistic activation with Cu^(2+)Pb^(2+)effectively increased the content of active products on the hemimorphite surface,thereby enhancing mineral surface reactivity,promoting collector adsorption,and improving surface hydrophobicity.
基金funded by the National Natural Science Foundation of China(Grant Nos.52364005,51934003)Yunnan major scientific and technological special project(202202AG050014).This support is gratefully acknowledged.
文摘To investigate the influence of different joint conditions on the rockburst of a circular tunnel,a true-triaxial test of rockburst with a single set of joint conditions was conducted.The rockburst incubation and evolution characteristics and acoustic emission evolution characteristics under different joint directions and joint dip angles were studied.The Weibull function was used to fit rockburst debris with different particle sizes and a single set of joints to obtain statistical results.The experimental results revealed that shear fracture rockburst occurred in samples with joints aligned with the tunnel strike as well as joints with inclination angles of 45°,60°,and 90°.Slab buckling–shear fracture rockburst was more likely to occur in samples with inclination angles of 0°and 30°.Slab buckling–shear fracture rockburst occurred in samples with joints crossing the tunnel strike as well as in samples with joints with inclination angles of 0°,30°,45°,60°,and 90°.The location of the rockburst pit was influenced by the joint inclination angle when the joints aligned with the tunnel strike.In contrast,when the joints crossed the tunnel strike,the location of the rockburst pit was independent of the joint inclination angle.The cumulative absolute energy of acoustic emission(AE)exhibited an overall upward trend with the increase in joint dip angle.The cumulative absolute energy of the AE of the jointed samples was greater than that of intact samples(without joints).Loading reached the rockburst stage in the samples with joints aligned with the tunnel strike and dip angles of 45°,60°,and 90°.Moreover,the peak value of AE cumulative absolute energy was the highest.These results can elucidate the evolution mechanism of rockburst in the surrounding rock of circular tunnels with a single set of joints in deep underground engineering.
基金suppor ted by Yunnan Major Scientific and Technological Projects(Grant No.202202AG050006)the Personnel Training Project of Kunming University of Science and Technology(Grant No.KKZ3202221022)。
文摘The Guanfang large-scale W deposit is located in the W polymetallic ore concentration area of Bozhushan in southeastern Yunnan,China.Despite extensive research,the fluid evolution process of the deposit remains ambiguous,leading to controversy regarding its genesis.This study conducted a detailed field geological survey,with systematic sampling of the KT6 orebody,to delineate mineralization stages.Fine mineralogy work,including the use of CL images of scheelite,in-situ LA-ICP-MS trace elements,and Sr isotopes,was carried out on diff erent generations of scheelite formed in various stages.The findings identified the evolution of fluids in the mineralization process,shedding light on the genesis of the deposit.The study revealed four mineralization stages at the Guanfang W deposit:prograde skarn stage,retrograde skarn stage,quartz-sulfide stage,and carbonate-fluorite stage.Diff erent generations of scheelite(Sch I,Sch II,Sch III)were observed in the first three stages,displaying distinct chondrite-normalized REE patterns.The REE of Sch I mainly substituted into the Ca site by REE^(3+)+□_(Ca),and there may be a similar substitution of Nb for REE,whereas it is not the main substitution method.The REE of Sch II mainly enter the scheelite lattice in the form of REE 3++Na+,and there may be a substitution of Nb for REE isomorphism.In the early stage,The REE of Sch III was mainly replaced by Nb for REE isomorphism,while in the later stage,the replacement mode of REE^(3+)+□_(Ca)coexisted with it.The Mo content in scheelite,along with the corresponding Eu anomalies in both scheelite and garnet,collectively imply that the ore-forming fluids during various mineralization stages were predominantly oxidizing,with only slight reducibility observed in Sch II.The in-situ Sr isotope ratios of scheelite concentrates ranged from 0.7093 to 0.7153,resembling those of the Bozhushan granite,indicating a relationship between W mineralization and granite.In addition,the Y/Ho ratios of scheelite from various mineralization stages exhibit a narrow range(19-31),with a pronounced correlation between the contents of Y and Ho and a similar trend in their variation.This consistency suggests that the Guanfang deposit has undergone a uniform or comparable evolutionary process,implying a stable ore-forming fluid across diff erent mineralization stages.
基金Projects(52074139,51964027)supported by the National Natural Science Foundation of ChinaProject(KKS 2202152011)supported by the High-level Talents of Yunnan Province,China。
文摘Flotation behavior of stibiconite after sulfidation roasting with sulfur at a high temperature and the sulfidation mechanisms were investigated by ultraviolet spectrophotometry,X-ray diffraction(XRD)combining with thermodynamic calculation,X-ray photoelectron spectroscopy(XPS)and electron probe microanalysis(EPMA).The XRD and thermodynamic analyses revealed that the Sb_(3)O_(6)(OH)was reduced into Sb_(2)O_(4)and Sb_(2)O_(3),and was transformed into Sb_(2)S_(3)after introducing sulfur at high temperatures.Flotation test results show that flotation recovery of the stibiconite after sulfidation reaches 90.3%.Ultraviolet spectrophotometry tests confirm that adsorption capacity of sodium butyl xanthate(SBX)on surface of the roasted products has a positive relationship with S/Sb mole ratio.XPS analyses indicate that Sb-bearing species including mainly Sb_(2)S_(3),Sb_(2)O_(3)and Sb_(2)(SO_(4))_(3) are formed at the surface of particle after sulfidation.The EPMA analyses verify that the Sb_(2)S_(3)is generated at the outer layer of sample after sulfidation roasting,but the particle interior is mainly composed of antimony oxides.The sulfur atmosphere induces the outward migration of oxygen to form Sb_(2)O_(4).Then,the Sb_(2)O_(4)is transformed into Sb_(2)O_(3)in two pathways,and the Sb_(2)S_(3)is formed.These findings will provide theoretical support for recovering antimony from antimony oxide ores by xanthate flotation methods.
基金funded by the National Natural Science Foundation of China(52474131)the National Natural Science Foundation of China(42467022)+1 种基金the Yunnan Major Scientific and Technological Projects(Grant No.202202AG050014)the Yunnan Fundamental Research Projects(NO.202101BE070001-038,202201AT070146).
文摘The strength of backfill body is a crucial parameter in backfilling mining,and the failure process of cemented backfill body is essentially an energy dissipation process.To investigate the effects of curing age and cement-sand ratio on the strength and energy consumption of backfill,whole tailings were used as aggregate to prepare slurry with mass concentration of 74%,and the slurry with cement-sand ratio of 1:4,1:6,1:8 and 1:12 was poured into backfill.Uniaxial compression tests were conducted on backfill body specimens that had been cured for 7 days,14 days,28 days,and 45 days.It aims at studying the compressive strength,damage,energy storage limit,energy dissipation,and crack propagation of the fill.The results show that when the cement-sand ratio is held constant,the strength of the backfill increases with curing age.Simultaneously,when the curing age is fixed,the strength is positively correlated with the cement-sand ratio.During uniaxial compression tests,it is observed that the pre-peak energy consumption,post-peak energy consumption,total energy consumption,and unit volume strain energy of the cemented backfill body exhibit exponential relationships with both curing age and cement-sand ratio.The energy storage limit of the backfill reflects its capacity to absorb energy prior to failure,while the relationship between damage and energy consumption provides an accurate depiction of its internal failure mechanisms at different stages.In the failure process of the cemented backfill body,primary cracks accompany secondary cracks,many microcracks initiate and propagate from the stress direction,and crack propagation consumes a significant amount of energy.This study on the strength,energy storage limit,and failure of the cemented backfill body can provide valuable insights for mine safety production.
基金supported by the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(Grant No.2024ZD1001600)National Natural Science Foundation of China(Grants Nos.42302223,42162012 and 42402069)Yunnan Fundamental Research Projects(Grants No.202401CF070093).
文摘The western margin of the Yangtze Block hosts diverse Neoproterozoic igneous rocks,with exposed S-type granites serving as key indicators for deciphering regional geological evolution.This study focuses on the Jiudaowan granite pluton,located on the western margin of the Yangtze Block,through systematic petrographic,whole-rock geochemical,zircon and monazite U-Pb geochronology,and whole-rock Nd isotopic analyses aiming to elucidate its petrogenesis and tectonic significance.The Jiudaowan granite pluton is a composite body,consisting of the Luotaijiu,Jiudaowan,and Daheishan units,characterized by biotite monzogranites,muscovite-plagioclase granites,and two-mica monzogranites,respectively.LA-ICP-MS zircon and monazite U-Pb dating reveals crystallization ages between 832 and 798 Ma.The three units are peraluminous,containing minerals such as muscovite,garnet,and tourma-line,and exhibiting high SiO_(2)(72.99-77.83 wt%),Al_(2)O_(3)(12.36-15.02 wt%),and A/CNK values(1.06-1.43),con-firming their classification as peraluminous S-type granites.Compositional variations within the Jiudaowan granite pluton are primarily controlled by protolith composition and melting mechanisms.The pluton is distinguished by low CaO/Na_(2)O ratios(0.02-0.18),high Rb/Sr(0.83-113)and Rb/Ba(0.33-15.2)ratios,and negativeεNd(t)values(−13.6 to−9.1),indicating derivation from partial melting of het-erogeneous metasedimentary sources.MgO,TiO_(2),Rb/Sr,and whole-rock Zr saturation temperatures suggest that the Luotaijiu and Daheishan units formed via biotite dehydration melting,whereas the Jiudaowan unit resulted from muscovite dehydration melting.Additionally,the Jiudaowan granite pluton displays a clear negative correlation between Al_(2)O_(3),CaO,Fe_(2)O_(3)T,MgO,TiO_(2),and SiO_(2),along with pronounced Eu negative anomalies and depletions in Sr and Ti,suggesting fractional crystallization of feldspar,mica,and Fe-Ti oxides during magma emplacement.Similarly,variable incompatible element ratios of Nb/U(1.07-18.97)and Nb/La(0.24-26.88)further indicate minor crustal assimilation and contamination during magma evolution.Integrating regional geological data,we propose that the Jiudaowan pluton formed during crustal thickening associated with post-collisional extension,likely related to the breakup of the Rodinia supercontinent.
基金supported by the Natural Science Foundation of Hubei Province(2021CFA081)the Fundamental Research Funds for the Central Universities(2042023kf0210)the National Natural Science Foundation of China(42277160).
文摘A partly clumped-particles combined with joint planes model was developed to simulate the microstructure of quartz mica schist.It considers grain-scale heterogeneity including microgeometry heterogeneity and grain-scale elastic heterogeneity.Clumped-particles with larger volume and larger stiffness were used to represent stiff minerals such as quartz,the rest of unclumped particles with smaller stiffness were used to represent soft minerals such as mica.The joint planes,which have smaller stiffness and strength than mica,were used to describe schist.The extensive sensitivity studies have shown that the clump’s radius,clump’s content and joint plane’s strength affect the microscopic and macroscopic behaviors of sample.For DanBa quartz mica schist,the model calibrated uniaxial tests and well matched with the stress-strain curves,crack initiation stress and crack damage stress of laboratory test.
基金supported by Yunnan Major Scientific and Technological Project(202202AG050006)National Natural Science Foundation of China(42362010)The Open Fund of Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,Ministry of Nature Resources(ZRZYBSJSYS2022002)。
文摘The Bainiuchang Ag-polymetallic ore deposit,located in southeastern Yunnan,China,is one of the region's largest deposits.However,the hyp abyssal granite porphyry within this mining area has yet to be comprehensively investigated.In this study,we conducted geochemical,geochronological,whole-rock Sr-Nd isotope,and zircon Hf isotope analyses on granite porphyry samples collected from the Bainiuchang deposit.The results indicate that the granite porphyry formed between 87.5 and 87.4 Ma in the Late Yanshanian period.Geochemically,the granite is strongly peraluminous,with high silica and alkali contents consistent with S-type granite characteristics.The granite porphyry is enriched in large-ion lithophile elements(Rb,Th,U,and K)and is relatively depleted in Ba and Sr.The initial ^(87)Sr/^(86)Sr ratios are high(0.71392-0.71585),accompanied by low ε_(Nd)(t)values(-8.9 to-8.2).The zircons exhibited similarly low ε_(Hf)(t)values(-9.31 to-3.6).These data suggest that the porphyry-forming magma originated from a continental crustal source.The two-stage Hf and Nd model ages are estimated at 1534-1216 Ma and 1615-1561 Ma,respectively.Thus,the granite porphyry likely formed under a strike-slip extensional setting in the Late Yanshanian period and resulted from the re-melting of Proterozoic basement metagreywackes.This porphyry shares a similar magmatic origin with concealed granite bodies within the deposit and is associated with structural reactivation during the Yanshanian.The findings of this study provide valuable insights into the tectonomagmatic mineralization processes in the B ainiuchang area.
文摘Three-dimensional(3D)object detection is crucial for applications such as robotic control and autonomous driving.While high-precision sensors like LiDAR are expensive,RGB-D sensors(e.g.,Kinect)offer a cost-effective alternative,especially for indoor environments.However,RGB-D sensors still face limitations in accuracy and depth perception.This paper proposes an enhanced method that integrates attention-driven YOLOv9 with xLSTM into the F-ConvNet framework.By improving the precision of 2D bounding boxes generated for 3D object detection,this method addresses issues in indoor environments with complex structures and occlusions.The proposed approach enhances detection accuracy and robustness by combining RGB images and depth data,offering improved indoor 3D object detection performance.
基金Under the auspices of National Natural Science Foundation of China(No.41890854)Basic Research Program of Shenzhen Science and Technology Innovation Committee(No.JCYJ20180507182022554)+3 种基金National Key R&D Program of China(No.2017YFC0506200)National Natural Science Foundation of China(No.7181101150)National Natural Science Foundation of China(No.41901248)Shenzhen Future Industry Development Funding Program(No.201507211219247860)。
文摘China has experienced rapid urbanizations with dramatic land cover changes since 1978. Forest loss is one of land cover changes, and it induces various eco-environmental degradation issues. As one of China’s hotspot regions, the Guangdong-Hong KongMacao Greater Bay Area(GBA) has undergone a dramatic urban expansion. To better understand forest dynamics and protect forest ecosystem, revealing the processes, patterns and underlying drivers of forest loss is essential. This study focused on the spatiotemporal evolution and potential driving factors of forest loss in the GBA at regional and city level. The Landsat time-series images from 1987 to2017 were used to derive forest, and landscape metrics and geographic information system(GIS) were applied to implement further spatial analysis. The results showed that: 1) 14.86% of the total urban growth area of the GBA was obtained from the forest loss in1987–2017;meanwhile, the forest loss area of the GBA reached 4040.6 km2, of which 25.60%(1034.42 km2) was converted to urban land;2) the percentages of forest loss to urban land in Dongguan(19.14%), Guangzhou(18.35%) and Shenzhen(15.81%) were higher than those in other cities;3) the forest became increasingly fragmented from 1987–2007, and then the fragmentation decreased from2007 to 2017);4) the landscape responses to forest changes varied with the scale;and 5) some forest loss to urban regions moved from low-elevation and gentle-slope terrains to higher-elevation and steep-slope terrains over time, especially in Shenzhen and Hong Kong.Urbanization and industrialization greatly drove forest loss and fragmentation, and, notably, hillside urban land expansion may have contributed to hillside forest loss. The findings will help policy makers in maintaining the stability of forest ecosystems, and provide some new insights into forest management and conservation.
文摘The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with GPS field collected data in the area of Xiaowan-Dachaoshan Reservoirs of Lancangjiang River cascaded Hydropower Area. Consequently, the land-cover is divided into five subclasses, namely water, paddy field and wetland, bare dryland and sparse shrub, secondary forest and density forest. The result showed that the areas of bare land, upland and secondary forest decreased in 1988-1996, whereas from 1996 to 2000, water body and density forest keep invariability while the areas of paddy field and wetland, bare dryland and sparse scrub increasing and the area of secondary forest decrease; Features of reciprocal transformation between density forest and other type of land-cover had two points, i.e. secondary forest, bare dryland and sparse shrub converted to density forest; and density forest converted to secondary forest and paddy field and wetland. It reflects the dynamic variation of density forest; the area which slope less than 8° and greater than 15° shows bigger variation, however, less change in 8°-15°.
