Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one ofthe youngest basalt units on the Moon. The CE-5 lunar samples provide oppor...Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one ofthe youngest basalt units on the Moon. The CE-5 lunar samples provide opportunities to address some key scientific questions related to theMoon, including the discovery of high-pressure silica polymorphs (seifertite and stishovite) and a new lunar mineral, changesite-(Y). Seifertitewas found to be coexist with stishovite in a silica fragment from CE-5 lunar regolith. This is the first confirmed seifertite in returned lunarsamples. Seifertite has two space group symmetries (Pnc2 and Pbcn) and formed from an α-cristobalite-like phase during “cold” compressionduring a shock event. The aftershock heating process changes some seifertite to stishovite. Thus, this silica fragment records different stagesof an impact process, and the peak shock pressure is estimated to be ∼11 to 40 GPa, which is much lower than the pressure condition forcoexistence of seifertite and stishovite on the phase diagram. Changesite-(Y), with ideal formula (Ca_(8)Y)◻Fe^(2+)(PO_(4))_(7) (where ◻ denotes avacancy) is the first new lunar mineral to be discovered in CE-5 regolith samples. This newly identified phosphate mineral is in the form ofcolumnar crystals and was found in CE-5 basalt fragments. It contains high concentrations of Y and rare earth elements (REE), reaching upto ∼14 wt. % (Y,REE)2O3. The occurrence of changesite-(Y) marks the late-stage fractional crystallization processes of CE-5 basalts combinedwith silicate liquid immiscibility. These new findings demonstrate the significance of studies on high-pressure minerals in lunar materials andthe special nature of lunar magmatic evolution.展开更多
Natural minerals,such as kaolinite,halloysite,montmorillonite,attapulgite,bentonite,sepiolite,forsterite,and wollastonite,have considerable potential for use in CO_(2) capture and mineralization due to their abundant ...Natural minerals,such as kaolinite,halloysite,montmorillonite,attapulgite,bentonite,sepiolite,forsterite,and wollastonite,have considerable potential for use in CO_(2) capture and mineralization due to their abundant reserves,low cost,excellent mechanical prop-erties,and chemical stability.Over the past decades,various methods,such as those involving heat,acid,alkali,organic amine,amino sil-ane,and ionic liquid,have been employed to enhance the CO_(2) capture performance of natural minerals to attain high specific surface area,a large number of pore structures,and rich active sites.Future research on CO_(2) capture by natural minerals will focus on the full utiliza-tion of the properties of natural minerals,adoption of suitable modification methods,and preparation of composite materials with high specific surface area and rich active sites.In addition,we provide a summary of the principle and technical route of direct and indirect mineralization of CO_(2) by natural minerals.This process uses minerals with high calcium and magnesium contents,such as forsterite(Mg_(2)SiO_(4)),serpentine[Mg_(3)Si_(2)O(OH)_(4)],and wollastonite(CaSiO_(3)).The research status of indirect mineralization of CO_(2) using hydro-chloric acid,acetic acid,molten salt,and ammonium salt as media is also introduced in detail.The recovery of additives and high-value-added products during the mineralization process to increase economic benefits is another focus of future research on CO_(2) mineralization by natural minerals.展开更多
The fruit of Morinda citrifolia L., commonly known as noni, has an extensive history of use as a food and traditional medicine around the world. Adding value to Morinda citrifolia L. products, particularly the fruit, ...The fruit of Morinda citrifolia L., commonly known as noni, has an extensive history of use as a food and traditional medicine around the world. Adding value to Morinda citrifolia L. products, particularly the fruit, could be one way of building resilience in vulnerable farming households. The aim of this study was to determine the secondary metabolite and mineral composition of noni juice obtained by fermenting the fruit of Morinda citrifolia L. Fruits were collected in August 2022 from the local field in Thiès region, West of Senegal. Extraction yields were determined and the secondary metabolites were determined using conventional analytical methods. Calcium, magnesium, iron, sodium and potassium were determined by atomic absorption spectrophotometer coupled with a CCD detector. The results show that an average fruit mass (503.2 ± 110.96 g) consists of 171.44 ± 50.01 g pulp and 34.06 ± 10.35 g seeds. The traditional extraction yield of noni juice is 16.46% after three weeks of fermentation. The contents of total polyphenols, flavonoids and tannins obtained in noni are 608.97 ± 4.53 mg EAG/100mL, 7.78 ± 0.01 mg EQ/100mL and 0.191 ± 0.01 mg EC/100mL respectively. The ethanol content of noni varies from 3.57 to 5.23 mL/100mL during extraction. Noni has a high calcium content with a concentration of 383.79 ± 33.23 mg/L. This is followed by a good concentration of magnesium, potassium and sodium, at 278.47 ± 26.30, 187.43 ± 10.7 and 155.95 ± 28.66 mg/L respectively. Noni also has an iron content of 202.15 ± 0.05 mg/L.展开更多
The Baidi Au-Sb deposit, which contains 8 t of Au and 10,979 Mt of Sb, is a typical and rare paragenetic deposit located in southwestern Guizhou Province, China.Previous studies have focused on individual ores, but ha...The Baidi Au-Sb deposit, which contains 8 t of Au and 10,979 Mt of Sb, is a typical and rare paragenetic deposit located in southwestern Guizhou Province, China.Previous studies have focused on individual ores, but have not combined them to identify their paragenetic mechanism or metallogenic regularity. Therefore, we used field investigations, microscopic observations, and in situ analyses to identify the spatial distribution, mineral paragenesis, compositional evolution, and metallogenic material sources of the ore bodies. We also determined the Au and Sb paragenetic characteristics and the metallogenesis of the deposit. The main Au-bearing minerals in the deposit were early(Apy1–2) and late(Apy3) stage arsenopyrites, as well as pre-mineralization(Py1), mineralization(Py2–5), and late mineralization(Py6–7) stage pyrites. The main Sb-bearing minerals were stibnite(Snt), skinnerite, bournonite,and valentinite. The minerals formed in the order of Py1,Py2–3 + Apy1, Py4–5 + Apy2, Snt, and Py6–7 + Apy3.The δ34S values of the arsenopyrites and pyrites ranged from-5 to 5‰, while those of stibnite were mostly less than-5‰ in the later mineralization stages. Sulfur was provided by deep magmatic hydrothermal fluids, but sedimentary sulfur was added in the later stages. Moreover,the trace elemental contents fluctuated and eventually became similar to those of the sedimentary strata. By comprehensively considering the ores along with the geological characteristics of the deposit, we determined that deep magma provided the Au during ore formation. Later tectonic changes provided Sb from the sedimentary strata,which precipitated along fault expansion areas and produced Au and Sb paragenesis.展开更多
In response to the rapid increase in world population and subsequent demands for food,edible insects represent an alternative food source for humans that is rich in proteins,amino acids and minerals.Entomophagy is a t...In response to the rapid increase in world population and subsequent demands for food,edible insects represent an alternative food source for humans that is rich in proteins,amino acids and minerals.Entomophagy is a tradition in many countries including China and Thailand,and edible insects have attracted a lot of attention in Western World due to their suitable nutrient composition,high mineral content(e.g.,Fe,Zn,Ca,Mg)and potential use as a supplement in human diet.In this study,we surveyed mineral content in seven insect orders and 67 species of mass produced and wild-harvested edible insects.The total content of essential elements in edible insects was very high in Tenebrio molitor,Bombyx mori,and Zonocerus variegatus.The heavy metal content(summarized for eight species)was below the maximum limit allowed for safe consumption.Sustainable supply of minerals derived from insect biomass is complicated due to the high variations of mineral content in insects and the potential of its change due to processing.展开更多
A seed-directed approach to synthesizing Fe ZSM-22 zeolite without organic structure directing agent(OSDA)was developed by using Fe-rich diatomite as all aluminum and iron sources.The Fe ZSM-22zeolite with optimal cry...A seed-directed approach to synthesizing Fe ZSM-22 zeolite without organic structure directing agent(OSDA)was developed by using Fe-rich diatomite as all aluminum and iron sources.The Fe ZSM-22zeolite with optimal crystallinity and purity can be obtained by systematically adjusting feed composition and synthesis conditions.Characterizations show that Fe ZSM-22 zeolite synthesized with OSDA-free owns high crystallinity,obvious thin needle-shaped morphology and high Bronsted/Lewis acid ratio.Significantly,when used for n-octane hydroisomerization reaction,its derived catalyst exhibits the best catalytic performance reflected by the highest selectivity to C_(8)isomers compared to the two reference catalysts prepared based on a Fe-containing and a Fe-free ZSM-22 synthesized through an OSDA-directed route from natural diatomite and conventional chemicals,respectively.This work provides an alternative route to sustainably synthesizing heteroatomic zeolites with high performance.展开更多
The flotation separation of Cu–Fe sulfide minerals at low alkalinity can be achieved using selective depressants.In the flotation system of Cu–Fe sulfide minerals,depressants usually preferentially interact with the...The flotation separation of Cu–Fe sulfide minerals at low alkalinity can be achieved using selective depressants.In the flotation system of Cu–Fe sulfide minerals,depressants usually preferentially interact with the pyrite surface to render the mineral surface hydrophilic and hinder the adsorption of the collector.This review summarizes the advances in depressants for the flotation separation of Cu–Fe sulfide minerals at low alkalinity.These advances include use of inorganic depressants (oxidants and sulfur–oxygen compounds),natural polysaccharides (starch,dextrin,konjac glucomannan,and galactomannan),modified polymers (carboxymethyl cellulose,polyacrylamide,lignosulfonate,and tricarboxylate sodium starch),organic acids (polyglutamic acid,sodium humate,tannic acid,pyrogallic acid,salicylic acid,and lactic acid),sodium dimethyl dithiocarbamate,and diethylenetriamine.The potential application of specific inorganic and organic depressants in the flotation separation of Cu–Fe sulfide minerals at low alkalinity is reviewed.The advances in the use of organic depressants with respect to the flotation separation of Cu–Fe sulfide minerals are comprehensively detailed.Additionally,the depression performances and mechanisms of different types of organic depressants on mineral surfaces are summarized.Finally,several perspectives on depressants vis-à-vis flotation separation of Cu–Fe sulfide minerals at low alkalinity are proposed.展开更多
There are abundant igneous gas reservoirs in the South China Sea with significant value of research,and lithology classification,mineral analysis and porosity inversion are important links in reservoir evaluation.Howe...There are abundant igneous gas reservoirs in the South China Sea with significant value of research,and lithology classification,mineral analysis and porosity inversion are important links in reservoir evaluation.However,affected by the diverse lithology,complicated mineral and widespread alteration,conventional logging lithology classification and mineral inversion become considerably difficult.At the same time,owing to the limitation of the wireline log response equation,the quantity and accuracy of minerals can hardly meet the exploration requirements of igneous formations.To overcome those issues,this study takes the South China Sea as an example,and combines multi-scale data such as micro rock slices,petrophysical experiments,wireline log and element cutting log to establish a set of joint inversion methods for minerals and porosity of altered igneous rocks.Specifically,we define the lithology and mineral characteristics through core slices and mineral data,and establish an igneous multi-mineral volumetric model.Then we determine element cutting log correction method based on core element data,and combine wireline log and corrected element cutting log to perform the lithology classification and joint inversion of minerals and porosity.However,it is always difficult to determine the elemental eigenvalues of different minerals in inversion.This paper uses multiple linear regression methods to solve this problem.Finally,an integrated inversion technique for altered igneous formations was developed.The results show that the corrected element cutting log are in good agreement with the core element data,and the mineral and porosity results obtained from the joint inversion based on the wireline log and corrected element cutting log are also in good agreement with the core data from X-ray diffraction.The results demonstrate that the inversion technique is applicable and this study provides a new direction for the mineral inversion research of altered igneous formations.展开更多
In recent years,natural hydrogen has been discovered in various geological environments both domestically and internationally,which has sparked a global interest among geologists and led to a surge in the exploration ...In recent years,natural hydrogen has been discovered in various geological environments both domestically and internationally,which has sparked a global interest among geologists and led to a surge in the exploration of hydrogen gas(Klein et al.,2019;Prinzhofer et al.,2019;Moretti and Webber,2021;Scott,2021;Bezruchko,2022).However,there is a lack of research on the occurrence state of natural hydrogen gas,which hinders a deeper understanding of its behavior in underground storage and migration.展开更多
The types,occurrence and composition of authigenic clay minerals in argillaceous limestone of sepiolite-bearing strata of the first member of the Middle Permian Maokou Formation(Mao-1 Member)in eastern Sichuan Basin w...The types,occurrence and composition of authigenic clay minerals in argillaceous limestone of sepiolite-bearing strata of the first member of the Middle Permian Maokou Formation(Mao-1 Member)in eastern Sichuan Basin were investigated through outcrop section measurement,core observation,thin section identification,argon ion polishing,X-ray diffraction,scanning electron microscope,energy spectrum analysis and laser ablation-inductively coupled plasma-mass spectrometry.The diagenetic evolution sequence of clay minerals was clarified,and the sedimentary-diagenetic evolution model of clay minerals was established.The results show that authigenic sepiolite minerals were precipitated in the Si4+and Mg2+-rich cool aragonite sea and sepiolite-bearing strata were formed in the Mao-1 Member.During burial diagenesis,authigenic clay minerals undergo two possible evolution sequences.First,from the early diagenetic stage A to the middle diagenetic stage A1,the sepiolite kept stable in the shallow-buried environment lack of Al3+.It began to transform into stevensite in the middle diagenetic stage A2,and then evolved into disordered talc in the middle diagenetic stage B1and finally into talc in the period from the middle diagenetic stage B2to the late diagenetic stage.Thus,the primary diagenetic evolution sequence of authigenic clay minerals,i.e.sepiolite-stevensite-disordered talc-talc,was formed in the Mao-1 Member.Second,in the early diagenetic stage A,as Al3+carried by the storm and upwelling currents was involved in the diagenetic process,trace of sepiolite started to evolve into smectite,and a part of smectite turned into chlorite.From the early diagenetic stage B to the middle diagenesis stage A1,a part of smectite evolved to illite/smectite mixed layer(I/S).The I/S evolved initially into illite from the middle diagenesis stage A2to the middle diagenesis stage B2,and then totally into illite in the late diagenesis stage.Thus,the secondary diagenetic evolution sequence of authigenic clay minerals,i.e.sepiolite-smectite-chlorite/illite,was formed in the Mao-1 Member.The types and evolution of authigenic clay minerals in argillaceous limestone of sepiolite-bearing strata are significant for petroleum geology in two aspects.First,sepiolite can adsorb and accumulate a large amount of organic matters,thereby effectively improving the quality and hydrocarbon generation potential of the source rocks of the Mao-1 Member.Second,the evolution from sepiolite to talc is accompanied by the formation of numerous organic matter pores and clay shrinkage pores/fractures,as well as the releasing of the Mg2+-rich diagenetic fluid,which allows for the dolomitization of limestone within or around the sag.As a result,the new assemblages of self-generation and self-accumulation,and lower/side source and upper/lateral reservoir,are created in the Middle Permian,enhancing the hydrocarbon accumulation efficiency.展开更多
The development of artificial intelligence (AI), particularly deep learning, has made it possible to accelerate and improve the processing of data collected in different fields (commerce, medicine, surveillance or sec...The development of artificial intelligence (AI), particularly deep learning, has made it possible to accelerate and improve the processing of data collected in different fields (commerce, medicine, surveillance or security, agriculture, etc.). Most related works use open source consistent image databases. This is the case for ImageNet reference data such as coco data, IP102, CIFAR-10, STL-10 and many others with variability representatives. The consistency of its images contributes to the spectacular results observed in its fields with deep learning. The application of deep learning which is making its debut in geology does not, to our knowledge, include a database of microscopic images of thin sections of open source rock minerals. In this paper, we evaluate three optimizers under the AlexNet architecture to check whether our acquired mineral images have object features or patterns that are clear and distinct to be extracted by a neural network. These are thin sections of magmatic rocks (biotite and 2-mica granite, granodiorite, simple granite, dolerite, charnokite and gabbros, etc.) which served as support. We use two hyper-parameters: the number of epochs to perform complete rounds on the entire data set and the “learning rate” to indicate how quickly the weights in the network will be modified during optimization. Using Transfer Learning, the three (3) optimizers all based on the gradient descent methods of Stochastic Momentum Gradient Descent (sgdm), Root Mean Square Propagation (RMSprop) algorithm and Adaptive Estimation of moment (Adam) achieved better performance. The recorded results indicate that the Momentum optimizer achieved the best scores respectively of 96.2% with a learning step set to 10−3 for a fixed choice of 350 epochs during this variation and 96, 7% over 300 epochs for the same value of the learning step. This performance is expected to provide excellent insight into image quality for future studies. Then they participate in the development of an intelligent system for the identification and classification of minerals, seven (7) in total (quartz, biotite, amphibole, plagioclase, feldspar, muscovite, pyroxene) and rocks.展开更多
Owing to the depletion of wolframite, the focus of tungsten extraction has gradually shifted to scheelite. However, separating the associated minerals(e.g., apatite, fluorite, and calcite) and scheelite is challenging...Owing to the depletion of wolframite, the focus of tungsten extraction has gradually shifted to scheelite. However, separating the associated minerals(e.g., apatite, fluorite, and calcite) and scheelite is challenging because their surface physicochemical properties are similar to those of scheelite. Fortunately, researchers have made substantial progress in separating the minerals of scheelite by using depressants. This study reviews the application and inhibition mechanism of inorganic depressants in obtaining tungsten from its calcium-bearing minerals. The application of new organic depressants in obtaining tungsten from its calcium-bearing minerals and the associated mechanisms are also summarized. After an objective assessment of inorganic and organic depressants’ advantages and disadvantages, possible future research directions for inorganic and organic depressants are proposed. Herein, we provide a theoretical basis for developing scheelite flotation depressants.展开更多
In the past few decades,microbubble flotation has been widely studied in the separation and beneficiation of fine minerals.Compared with conventional flotation,microbubble flotation has obvious advantages,such as high...In the past few decades,microbubble flotation has been widely studied in the separation and beneficiation of fine minerals.Compared with conventional flotation,microbubble flotation has obvious advantages,such as high grade and recovery and low consumption of flotation reagents.This work systematically reviews the latest advances and research progress in the flotation of fine mineral particles by microbubbles.In general,microbubbles have small bubble size,large specific surface area,high surface energy,and good selectivity and can also easily be attached to the surface of hydrophobic particles or large bubbles,greatly reducing the detaching probability of particles from bubbles.Microbubbles can be prepared by pressurized aeration and dissolved air,electrolysis,ultrasonic cavitation,photocatalysis,solvent exchange,temperature difference method(TDM),and Venturi tube and membrane method.Correspondingly,equipment for fine-particle flotation is categorized as microbubble release flotation machine,centrifugal flotation column,packed flotation column,and magnetic flotation machine.In practice,microbubble flotation has been widely studied in the beneficiation of ultrafine coals,metallic minerals,and nonmetallic minerals and exhibited superiority over conventional flotation machines.Mechanisms underpinning the promotion of fine-particle flotation by nanobubbles include the agglomeration of fine particles,high stability of nanobubbles in aqueous solutions,and enhancement of particle hydrophobicity and flotation dynamics.展开更多
The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater ...The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater Himalayan Crystalline Complex(GHC),the Gyirong pegmatite in southern Tibet was chosen for geochronological and geochemical studies.The dating analyses indicate that the U-Th-Pb ages of zircon,monazite,and xenotime exhibit large variations(38.6‒16.1 Ma),with the weighted average value of the four youngest points is 16.5±0.3 Ma,which indicates that the final stage of crystallization of the melt occurred in the Miocene.The age of the muscovite Ar-Ar inverse isochron is 15.2±0.4 Ma,which is slightly later than the intrusion age,showing that a cooling process associated with rapid denudation occurred at 16‒15 Ma.TheεHf(t)values of the Cenozoic anatectic zircons cluster between−12 and−9 with an average of−11.4.The Gyirong pegmatite shows high contents of Si,Al,and K,a high Al saturation index,and low contents of Na,Ca,Fe,Mn,P,Mg,and Ti.Overall,the Gyirong pegmatite is enriched in Rb,Cs,U,K,Th and Pb and depleted in Nb,Ta,Zr,Ti,Eu,Sr,and Ba.The samples show a high 87Sr/86Sr(16 Ma)ratio of ca.0.762 and a lowεNd(16 Ma)value of−16.0.The calculated average initial values of 208Pb/204Pb(16 Ma),207Pb/204Pb(16 Ma)and 206Pb/204Pb(16 Ma)of the whole rock are 39.72,15.79 and 19.56,respectively.The Sr-Nd-Pb-Hf isotopic characteristics of the Gyirong pegmatite are consistent with those of the GHC.This study concludes that the Gyirong pegmatite represents a typical crustal‒derived anatectic pegmatite with low metallogenic potential for rare metals.The Gyirong pegmatite records the long‒term metamorphism and partial melting process of the GHC,and reflects the crustal thickening caused by thrust compression at 39‒29 Ma and the crustal thinning induced by extensional decompression during 28‒15 Ma.展开更多
Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM(ultra-high pressure metamorphic)belt were studied for petrography,titanite U-Pb dating and mineral geochemistry.Three origins of garnets...Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM(ultra-high pressure metamorphic)belt were studied for petrography,titanite U-Pb dating and mineral geochemistry.Three origins of garnets are distinguished:metamorphic garnet,peritectic garnet and anatectic garnet,which are formed in the stages of peak metamorphism,retrograde anatexis and melt crystallization,respectively.The euhedral titanite has a high content of REE and high Th/U ratios,which is interpreted as indicating that it was newly-formed from an anatectic melt.The LA-ICP-MS titanite U-Pb dating yields 214-217 Ma ages for the titanite(melt)crystallization.The distribution of trace elements varies in response to the different host minerals at different stages.At the peak metamorphic stage,Y and HREE are mainly hosted by garnet,Ba and Rb by phengite,Sr,Nb,Ta,Pb,Th,U and LREE by allanite and Y,U and HREE by zircon.During partial melting,Y,Pb,Th,U and REE are released into the melt,which causes a dramatic decline of these element contents in the retrograde minerals.Finally,titanite absorbs most of the Nb,U,LREE and HREE from the melt.Therefore,the different stages of metamorphism have different mineral assemblages,which host different trace elements.展开更多
The Ordovician-Silurian Wufeng and Longmaxi Shale in the Sichuan Basin were studied to understand the genesis and diagenetic evolution of carbonate minerals and their effects on reservoir quality. The results of geoch...The Ordovician-Silurian Wufeng and Longmaxi Shale in the Sichuan Basin were studied to understand the genesis and diagenetic evolution of carbonate minerals and their effects on reservoir quality. The results of geochemical and petrological analyses show that calcite grains have a negative Ce anomaly indicating they formed in the oxidizing environment of seawater. The high carbonate mineral contents in the margin of basin indicate that calcite grains and cores of dolomite grains appear largely to be of detrital origin. The rhombic rims of dolomite grains and dolomite concretions with the δ^(13)C of –15.46‰ and the enrichment of middle rare earth elements were formed during the sulfate-driven anaerobic oxidation of methane. The calcite in radiolarian were related to the microbial sulfate reduction for the abundant anhedral pyrites and δ^(13)C value of –11.34‰. Calcite veins precipitated in the deep burial stage with homogenization temperature of the inclusions ranging from 146.70 ℃ to 182.90 ℃. The pores in shale are mainly organic matter pores with pore size mainly in the range of 1–20 nm in diameter. Carbonate minerals influence the development of pores through offering storage space for organic matter. When calcite contents ranging from 10% to 20%, calcite grains and cement as rigid framework can preserve primary pores. Subsequently, the thermal cracking of liquid petroleum in primary pores will form organic matter pores. The radiolarian were mostly partially filled with calcite, which combining with microcrystalline quartz preserved a high storage capacity.展开更多
The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The g...The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed geochemical prospecting.展开更多
Hydrothermal alteration with bleaching of host rocks is the most important prospecting indicator for gold deposits in the Jiangnan Orogen Belt.The alteration has been identified as pre-ore carbonate(siderite)-sericiti...Hydrothermal alteration with bleaching of host rocks is the most important prospecting indicator for gold deposits in the Jiangnan Orogen Belt.The alteration has been identified as pre-ore carbonate(siderite)-sericitization and the Fe of siderite in the alteration zone is derived from the host rocks rather than fluids.In addition,such alteration decreases in intensity and width with depth and gold mineralization also occur in the non-bleached rocks,casting doubt on the reliability of the prospecting indicator.Detailed petrographic work and SEM analysis on the Wangu deposit indicate that there are two types of siderites,i.e.,Sd1 and Sd2.Among them,Sd1 grains are relatively small and distributed along the planes of unaltered host rocks,while Sd2 grains,only occurring in the altered slates,are commonly larger.Both types of siderites were altered by auriferous fluids,producing porous cores and minerals such as pyrite,quartz,and ankerite.Compared with unaltered parts,the altered parts have lower Fe,but higher U,Pb,and REE.In addition,Sd1 and Sd2 are similar in Mn,Na,V,and Sr concentrations but different in Fe and Mg.The occurrence and geochemical compositions of both siderites indicate that Sd1 could be transformed into Sd2 by pre-mineralization alteration through dissolution-reprecipitation.Chlorite is another important Fe-bearing mineral in the host rocks,and EPMA analysis suggests that it is ripidolite with relatively high Fe contents.Consequently,chlorite can also provide Fe to form the pre-ore carbonate(siderite)-sericitization.Geochemical modeling demonstrates that both ripidolite and siderite can result in sulfidation and therefore gold precipitation.As a result,this study demonstrates that pre-ore alteration with characterized bleaching is not a prerequisite for gold mineralization despite of its prominent features.Due to the presence of Fe-bearing Sd1 and chlorite,gold mineralization could still occur through sulfidation in the unaltered rocks.展开更多
The composition,provenance,and genetic mechanism of sediment on different sedimentary units of the East China Sea(ECS)shelf are essential for understanding the depositional dynamics environment in the ECS.The sediment...The composition,provenance,and genetic mechanism of sediment on different sedimentary units of the East China Sea(ECS)shelf are essential for understanding the depositional dynamics environment in the ECS.The sediments in the northern ECS shelf are distributed in a ring-shaped distribution centered on the southwestern Cheju Island Mud.From the inside to the outside,the grain size goes from fine to coarse.Aside from the“grain size effect”,hydrodynamic sorting and mineral composition are important restrictions on the content of rare earth elements(REEs).Based on the grain size,REEs,and clay mineral composition of 300 surface sediments,as well as the sedimentary genesis,the northern ECS shelf is divided into three geochemical zones:southwestern Cheju Island Mud Area(ZoneⅠ),Changjiang Shoal Sand Ridges(ZoneⅡ-1),Sand Ridges of the East China Sea shelf(ZoneⅡ-2).The northern ECS shelf is mostly impacted by Chinese mainland rivers(the Changjiang River and Huanghe River),and the provenance and transport mechanism of sediments of different grain sizes is diverse.The bulk sediments come primarily from the Changjiang River,with some material from the Huanghe River carried by the Yellow Sea Coastal Current and the North Jiangsu Coastal Current,and less from Korean rivers.Among them,surface sediments in the southwestern Cheju Island Mud Area(ZoneⅠ)come mostly from the Changjiang River and partly from the Huanghe River.It was formed by the counterclockwise rotating cold eddies in the northern ECS shelf,which caused the sedimentation and accumulation of the fine-grained sediments of the Changjiang River and the Huanghe River.The Changjiang Shoal Sand Ridges(ZoneⅡ-1)were developed during the early-middle Holocene sea-level highstand.It is the modern tidal sand ridge sediment formed by intense hydrodynamic action under the influence of the Yellow Sea Coastal Current,North Jiangsu Coastal Current,and Changjiang Diluted Water.The surface sediments mainly originate from the Changjiang River and Huanghe River,with the Changjiang River dominating,and the Korean River(Hanjiang River)influencing just a few stations.Sand Ridges of the East China Sea shelf(ZoneⅡ-2)are the relict sediments of the paleo-Changjiang River created by sea invasion at the end of the Last Deglaciation in the Epipleistocene.The clay mineral composition of the surface sediments in the study area is just dominated by the Changjiang River,with the North Jiangsu Coastal Current and the Changjiang Diluted Water as the main transporting currents.展开更多
基金supported by the B-Type Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB 41000000)the National Natural Science Foundation of China(Grant Nos.41773052,41973058,and 42003054)+2 种基金the Key Research Program of the Chinese Academy of Sciences(Grant No.ZDBS-SSWJSC007-10)the Pre-Research Project on Civil Aerospace Technologies funded by the CNSA(Grant No.D020201)the China Postdoctoral Science Foundation(Grant No.2020M680155).
文摘Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one ofthe youngest basalt units on the Moon. The CE-5 lunar samples provide opportunities to address some key scientific questions related to theMoon, including the discovery of high-pressure silica polymorphs (seifertite and stishovite) and a new lunar mineral, changesite-(Y). Seifertitewas found to be coexist with stishovite in a silica fragment from CE-5 lunar regolith. This is the first confirmed seifertite in returned lunarsamples. Seifertite has two space group symmetries (Pnc2 and Pbcn) and formed from an α-cristobalite-like phase during “cold” compressionduring a shock event. The aftershock heating process changes some seifertite to stishovite. Thus, this silica fragment records different stagesof an impact process, and the peak shock pressure is estimated to be ∼11 to 40 GPa, which is much lower than the pressure condition forcoexistence of seifertite and stishovite on the phase diagram. Changesite-(Y), with ideal formula (Ca_(8)Y)◻Fe^(2+)(PO_(4))_(7) (where ◻ denotes avacancy) is the first new lunar mineral to be discovered in CE-5 regolith samples. This newly identified phosphate mineral is in the form ofcolumnar crystals and was found in CE-5 basalt fragments. It contains high concentrations of Y and rare earth elements (REE), reaching upto ∼14 wt. % (Y,REE)2O3. The occurrence of changesite-(Y) marks the late-stage fractional crystallization processes of CE-5 basalts combinedwith silicate liquid immiscibility. These new findings demonstrate the significance of studies on high-pressure minerals in lunar materials andthe special nature of lunar magmatic evolution.
基金supported by the Beijing Natural Science Foundation,China(No.2242055).
文摘Natural minerals,such as kaolinite,halloysite,montmorillonite,attapulgite,bentonite,sepiolite,forsterite,and wollastonite,have considerable potential for use in CO_(2) capture and mineralization due to their abundant reserves,low cost,excellent mechanical prop-erties,and chemical stability.Over the past decades,various methods,such as those involving heat,acid,alkali,organic amine,amino sil-ane,and ionic liquid,have been employed to enhance the CO_(2) capture performance of natural minerals to attain high specific surface area,a large number of pore structures,and rich active sites.Future research on CO_(2) capture by natural minerals will focus on the full utiliza-tion of the properties of natural minerals,adoption of suitable modification methods,and preparation of composite materials with high specific surface area and rich active sites.In addition,we provide a summary of the principle and technical route of direct and indirect mineralization of CO_(2) by natural minerals.This process uses minerals with high calcium and magnesium contents,such as forsterite(Mg_(2)SiO_(4)),serpentine[Mg_(3)Si_(2)O(OH)_(4)],and wollastonite(CaSiO_(3)).The research status of indirect mineralization of CO_(2) using hydro-chloric acid,acetic acid,molten salt,and ammonium salt as media is also introduced in detail.The recovery of additives and high-value-added products during the mineralization process to increase economic benefits is another focus of future research on CO_(2) mineralization by natural minerals.
文摘The fruit of Morinda citrifolia L., commonly known as noni, has an extensive history of use as a food and traditional medicine around the world. Adding value to Morinda citrifolia L. products, particularly the fruit, could be one way of building resilience in vulnerable farming households. The aim of this study was to determine the secondary metabolite and mineral composition of noni juice obtained by fermenting the fruit of Morinda citrifolia L. Fruits were collected in August 2022 from the local field in Thiès region, West of Senegal. Extraction yields were determined and the secondary metabolites were determined using conventional analytical methods. Calcium, magnesium, iron, sodium and potassium were determined by atomic absorption spectrophotometer coupled with a CCD detector. The results show that an average fruit mass (503.2 ± 110.96 g) consists of 171.44 ± 50.01 g pulp and 34.06 ± 10.35 g seeds. The traditional extraction yield of noni juice is 16.46% after three weeks of fermentation. The contents of total polyphenols, flavonoids and tannins obtained in noni are 608.97 ± 4.53 mg EAG/100mL, 7.78 ± 0.01 mg EQ/100mL and 0.191 ± 0.01 mg EC/100mL respectively. The ethanol content of noni varies from 3.57 to 5.23 mL/100mL during extraction. Noni has a high calcium content with a concentration of 383.79 ± 33.23 mg/L. This is followed by a good concentration of magnesium, potassium and sodium, at 278.47 ± 26.30, 187.43 ± 10.7 and 155.95 ± 28.66 mg/L respectively. Noni also has an iron content of 202.15 ± 0.05 mg/L.
基金funded by the Science and Technology Foundation of Guizhou Province([2019]1138,Qiankehezhicheng[2021]Yi Ban 403 and Qiankehepingtairencai-CXTD[2021]007)the Project for the Growth of Young Scientific and Technological Talents in Colleges and Universities of Guizhou Province([2022]356)。
文摘The Baidi Au-Sb deposit, which contains 8 t of Au and 10,979 Mt of Sb, is a typical and rare paragenetic deposit located in southwestern Guizhou Province, China.Previous studies have focused on individual ores, but have not combined them to identify their paragenetic mechanism or metallogenic regularity. Therefore, we used field investigations, microscopic observations, and in situ analyses to identify the spatial distribution, mineral paragenesis, compositional evolution, and metallogenic material sources of the ore bodies. We also determined the Au and Sb paragenetic characteristics and the metallogenesis of the deposit. The main Au-bearing minerals in the deposit were early(Apy1–2) and late(Apy3) stage arsenopyrites, as well as pre-mineralization(Py1), mineralization(Py2–5), and late mineralization(Py6–7) stage pyrites. The main Sb-bearing minerals were stibnite(Snt), skinnerite, bournonite,and valentinite. The minerals formed in the order of Py1,Py2–3 + Apy1, Py4–5 + Apy2, Snt, and Py6–7 + Apy3.The δ34S values of the arsenopyrites and pyrites ranged from-5 to 5‰, while those of stibnite were mostly less than-5‰ in the later mineralization stages. Sulfur was provided by deep magmatic hydrothermal fluids, but sedimentary sulfur was added in the later stages. Moreover,the trace elemental contents fluctuated and eventually became similar to those of the sedimentary strata. By comprehensively considering the ores along with the geological characteristics of the deposit, we determined that deep magma provided the Au during ore formation. Later tectonic changes provided Sb from the sedimentary strata,which precipitated along fault expansion areas and produced Au and Sb paragenesis.
基金founded by Jiangsu Agricultural Science and Technology Innovation Fund(CX(20)3179)Dongminghuanghetan Ecological Agriculture Co.,Ltd(204032897)+1 种基金partially funded funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no.861976,project SUSINCHAINthe German Federal Ministry of Education and Research(BMBF),in the frame of FACCE-SURPLUS/FACCE-JPI project UpWaste,grant number 031B0934A。
文摘In response to the rapid increase in world population and subsequent demands for food,edible insects represent an alternative food source for humans that is rich in proteins,amino acids and minerals.Entomophagy is a tradition in many countries including China and Thailand,and edible insects have attracted a lot of attention in Western World due to their suitable nutrient composition,high mineral content(e.g.,Fe,Zn,Ca,Mg)and potential use as a supplement in human diet.In this study,we surveyed mineral content in seven insect orders and 67 species of mass produced and wild-harvested edible insects.The total content of essential elements in edible insects was very high in Tenebrio molitor,Bombyx mori,and Zonocerus variegatus.The heavy metal content(summarized for eight species)was below the maximum limit allowed for safe consumption.Sustainable supply of minerals derived from insect biomass is complicated due to the high variations of mineral content in insects and the potential of its change due to processing.
基金the financial supports from the National Natural Science Foundation of China(22322803,22178059,22208054,22221005,22072019)Key Technologies Innovation and Industrialization Projects of Fujian Province(2022G031)Qingyuan Innovation Laboratory(00121002,00523005)。
文摘A seed-directed approach to synthesizing Fe ZSM-22 zeolite without organic structure directing agent(OSDA)was developed by using Fe-rich diatomite as all aluminum and iron sources.The Fe ZSM-22zeolite with optimal crystallinity and purity can be obtained by systematically adjusting feed composition and synthesis conditions.Characterizations show that Fe ZSM-22 zeolite synthesized with OSDA-free owns high crystallinity,obvious thin needle-shaped morphology and high Bronsted/Lewis acid ratio.Significantly,when used for n-octane hydroisomerization reaction,its derived catalyst exhibits the best catalytic performance reflected by the highest selectivity to C_(8)isomers compared to the two reference catalysts prepared based on a Fe-containing and a Fe-free ZSM-22 synthesized through an OSDA-directed route from natural diatomite and conventional chemicals,respectively.This work provides an alternative route to sustainably synthesizing heteroatomic zeolites with high performance.
基金financially supported by the Yunnan Major Scientific and Technological Projects,China (No.202202AG050015)the National Natural Science Foundation of China (No.51464029)。
文摘The flotation separation of Cu–Fe sulfide minerals at low alkalinity can be achieved using selective depressants.In the flotation system of Cu–Fe sulfide minerals,depressants usually preferentially interact with the pyrite surface to render the mineral surface hydrophilic and hinder the adsorption of the collector.This review summarizes the advances in depressants for the flotation separation of Cu–Fe sulfide minerals at low alkalinity.These advances include use of inorganic depressants (oxidants and sulfur–oxygen compounds),natural polysaccharides (starch,dextrin,konjac glucomannan,and galactomannan),modified polymers (carboxymethyl cellulose,polyacrylamide,lignosulfonate,and tricarboxylate sodium starch),organic acids (polyglutamic acid,sodium humate,tannic acid,pyrogallic acid,salicylic acid,and lactic acid),sodium dimethyl dithiocarbamate,and diethylenetriamine.The potential application of specific inorganic and organic depressants in the flotation separation of Cu–Fe sulfide minerals at low alkalinity is reviewed.The advances in the use of organic depressants with respect to the flotation separation of Cu–Fe sulfide minerals are comprehensively detailed.Additionally,the depression performances and mechanisms of different types of organic depressants on mineral surfaces are summarized.Finally,several perspectives on depressants vis-à-vis flotation separation of Cu–Fe sulfide minerals at low alkalinity are proposed.
基金The project was supported by the National Natural Science Foundation of China(Grant No.42204122).
文摘There are abundant igneous gas reservoirs in the South China Sea with significant value of research,and lithology classification,mineral analysis and porosity inversion are important links in reservoir evaluation.However,affected by the diverse lithology,complicated mineral and widespread alteration,conventional logging lithology classification and mineral inversion become considerably difficult.At the same time,owing to the limitation of the wireline log response equation,the quantity and accuracy of minerals can hardly meet the exploration requirements of igneous formations.To overcome those issues,this study takes the South China Sea as an example,and combines multi-scale data such as micro rock slices,petrophysical experiments,wireline log and element cutting log to establish a set of joint inversion methods for minerals and porosity of altered igneous rocks.Specifically,we define the lithology and mineral characteristics through core slices and mineral data,and establish an igneous multi-mineral volumetric model.Then we determine element cutting log correction method based on core element data,and combine wireline log and corrected element cutting log to perform the lithology classification and joint inversion of minerals and porosity.However,it is always difficult to determine the elemental eigenvalues of different minerals in inversion.This paper uses multiple linear regression methods to solve this problem.Finally,an integrated inversion technique for altered igneous formations was developed.The results show that the corrected element cutting log are in good agreement with the core element data,and the mineral and porosity results obtained from the joint inversion based on the wireline log and corrected element cutting log are also in good agreement with the core data from X-ray diffraction.The results demonstrate that the inversion technique is applicable and this study provides a new direction for the mineral inversion research of altered igneous formations.
基金funded by the National Key Research and Development Program of China (2019YFA0708504)the National Science Foundation of China (42090025)+1 种基金the National Postdoctoral Researcher Funding Program (GZB20240009)the American Association of Petroleum Geologists Foundation for the year 2023
文摘In recent years,natural hydrogen has been discovered in various geological environments both domestically and internationally,which has sparked a global interest among geologists and led to a surge in the exploration of hydrogen gas(Klein et al.,2019;Prinzhofer et al.,2019;Moretti and Webber,2021;Scott,2021;Bezruchko,2022).However,there is a lack of research on the occurrence state of natural hydrogen gas,which hinders a deeper understanding of its behavior in underground storage and migration.
基金Supported by the Enterprise Innovation and Development Joint Fund of National Natural Science Foundation of China(U19B6003)National Natural Science Foundation of China(41872150)。
文摘The types,occurrence and composition of authigenic clay minerals in argillaceous limestone of sepiolite-bearing strata of the first member of the Middle Permian Maokou Formation(Mao-1 Member)in eastern Sichuan Basin were investigated through outcrop section measurement,core observation,thin section identification,argon ion polishing,X-ray diffraction,scanning electron microscope,energy spectrum analysis and laser ablation-inductively coupled plasma-mass spectrometry.The diagenetic evolution sequence of clay minerals was clarified,and the sedimentary-diagenetic evolution model of clay minerals was established.The results show that authigenic sepiolite minerals were precipitated in the Si4+and Mg2+-rich cool aragonite sea and sepiolite-bearing strata were formed in the Mao-1 Member.During burial diagenesis,authigenic clay minerals undergo two possible evolution sequences.First,from the early diagenetic stage A to the middle diagenetic stage A1,the sepiolite kept stable in the shallow-buried environment lack of Al3+.It began to transform into stevensite in the middle diagenetic stage A2,and then evolved into disordered talc in the middle diagenetic stage B1and finally into talc in the period from the middle diagenetic stage B2to the late diagenetic stage.Thus,the primary diagenetic evolution sequence of authigenic clay minerals,i.e.sepiolite-stevensite-disordered talc-talc,was formed in the Mao-1 Member.Second,in the early diagenetic stage A,as Al3+carried by the storm and upwelling currents was involved in the diagenetic process,trace of sepiolite started to evolve into smectite,and a part of smectite turned into chlorite.From the early diagenetic stage B to the middle diagenesis stage A1,a part of smectite evolved to illite/smectite mixed layer(I/S).The I/S evolved initially into illite from the middle diagenesis stage A2to the middle diagenesis stage B2,and then totally into illite in the late diagenesis stage.Thus,the secondary diagenetic evolution sequence of authigenic clay minerals,i.e.sepiolite-smectite-chlorite/illite,was formed in the Mao-1 Member.The types and evolution of authigenic clay minerals in argillaceous limestone of sepiolite-bearing strata are significant for petroleum geology in two aspects.First,sepiolite can adsorb and accumulate a large amount of organic matters,thereby effectively improving the quality and hydrocarbon generation potential of the source rocks of the Mao-1 Member.Second,the evolution from sepiolite to talc is accompanied by the formation of numerous organic matter pores and clay shrinkage pores/fractures,as well as the releasing of the Mg2+-rich diagenetic fluid,which allows for the dolomitization of limestone within or around the sag.As a result,the new assemblages of self-generation and self-accumulation,and lower/side source and upper/lateral reservoir,are created in the Middle Permian,enhancing the hydrocarbon accumulation efficiency.
文摘The development of artificial intelligence (AI), particularly deep learning, has made it possible to accelerate and improve the processing of data collected in different fields (commerce, medicine, surveillance or security, agriculture, etc.). Most related works use open source consistent image databases. This is the case for ImageNet reference data such as coco data, IP102, CIFAR-10, STL-10 and many others with variability representatives. The consistency of its images contributes to the spectacular results observed in its fields with deep learning. The application of deep learning which is making its debut in geology does not, to our knowledge, include a database of microscopic images of thin sections of open source rock minerals. In this paper, we evaluate three optimizers under the AlexNet architecture to check whether our acquired mineral images have object features or patterns that are clear and distinct to be extracted by a neural network. These are thin sections of magmatic rocks (biotite and 2-mica granite, granodiorite, simple granite, dolerite, charnokite and gabbros, etc.) which served as support. We use two hyper-parameters: the number of epochs to perform complete rounds on the entire data set and the “learning rate” to indicate how quickly the weights in the network will be modified during optimization. Using Transfer Learning, the three (3) optimizers all based on the gradient descent methods of Stochastic Momentum Gradient Descent (sgdm), Root Mean Square Propagation (RMSprop) algorithm and Adaptive Estimation of moment (Adam) achieved better performance. The recorded results indicate that the Momentum optimizer achieved the best scores respectively of 96.2% with a learning step set to 10−3 for a fixed choice of 350 epochs during this variation and 96, 7% over 300 epochs for the same value of the learning step. This performance is expected to provide excellent insight into image quality for future studies. Then they participate in the development of an intelligent system for the identification and classification of minerals, seven (7) in total (quartz, biotite, amphibole, plagioclase, feldspar, muscovite, pyroxene) and rocks.
基金financially supported by the National Natural Science Foundation of China (Nos.52174248 and 52264022)the Natural Science Foundation of Jiangxi Province,China (No.20202ACBL214010)+1 种基金the “Thousand Talents Plan” of Jiangxi Province,China (No.jxsq2019201115)the Youth Jinggang Scholars program in Jiangxi Province,China。
文摘Owing to the depletion of wolframite, the focus of tungsten extraction has gradually shifted to scheelite. However, separating the associated minerals(e.g., apatite, fluorite, and calcite) and scheelite is challenging because their surface physicochemical properties are similar to those of scheelite. Fortunately, researchers have made substantial progress in separating the minerals of scheelite by using depressants. This study reviews the application and inhibition mechanism of inorganic depressants in obtaining tungsten from its calcium-bearing minerals. The application of new organic depressants in obtaining tungsten from its calcium-bearing minerals and the associated mechanisms are also summarized. After an objective assessment of inorganic and organic depressants’ advantages and disadvantages, possible future research directions for inorganic and organic depressants are proposed. Herein, we provide a theoretical basis for developing scheelite flotation depressants.
基金funded by the National Natural Science Foundation of China (No.52004020)Fundamental Research Funds for the Central Universities (No.00007733)+2 种基金Open Foundation of State Key Laboratory of Mineral Processing (No.BGRIMM-KJSKL-2021-13)High-end Foreign Expert Introduction Program (No.G2022105001L)State Key Laboratory of Comprehensive Utilization of LowGrade Refractory Gold Ores,Zijin Mining Group Co.,Ltd.
文摘In the past few decades,microbubble flotation has been widely studied in the separation and beneficiation of fine minerals.Compared with conventional flotation,microbubble flotation has obvious advantages,such as high grade and recovery and low consumption of flotation reagents.This work systematically reviews the latest advances and research progress in the flotation of fine mineral particles by microbubbles.In general,microbubbles have small bubble size,large specific surface area,high surface energy,and good selectivity and can also easily be attached to the surface of hydrophobic particles or large bubbles,greatly reducing the detaching probability of particles from bubbles.Microbubbles can be prepared by pressurized aeration and dissolved air,electrolysis,ultrasonic cavitation,photocatalysis,solvent exchange,temperature difference method(TDM),and Venturi tube and membrane method.Correspondingly,equipment for fine-particle flotation is categorized as microbubble release flotation machine,centrifugal flotation column,packed flotation column,and magnetic flotation machine.In practice,microbubble flotation has been widely studied in the beneficiation of ultrafine coals,metallic minerals,and nonmetallic minerals and exhibited superiority over conventional flotation machines.Mechanisms underpinning the promotion of fine-particle flotation by nanobubbles include the agglomeration of fine particles,high stability of nanobubbles in aqueous solutions,and enhancement of particle hydrophobicity and flotation dynamics.
基金sponsored by the National Key R&D Programme of China(2021YFC2901803)National Natural Science Foundation of China(92055314 and 41802095)+2 种基金the China Geological Survey(DD20230049 and DD20220983)is a contribution to the International Geoscience Programme(IGCP-741)Academician Bao-jun Liu Foundation of Southwest Geological Science and Technology Innovation Center.
文摘The Cenozoic Himalayan leucogranite-pegmatite belt has been a hotspot for rare metal exploration in recent years.To determine the genesis of the pegmatite in the Himalayan region and its relationship with the Greater Himalayan Crystalline Complex(GHC),the Gyirong pegmatite in southern Tibet was chosen for geochronological and geochemical studies.The dating analyses indicate that the U-Th-Pb ages of zircon,monazite,and xenotime exhibit large variations(38.6‒16.1 Ma),with the weighted average value of the four youngest points is 16.5±0.3 Ma,which indicates that the final stage of crystallization of the melt occurred in the Miocene.The age of the muscovite Ar-Ar inverse isochron is 15.2±0.4 Ma,which is slightly later than the intrusion age,showing that a cooling process associated with rapid denudation occurred at 16‒15 Ma.TheεHf(t)values of the Cenozoic anatectic zircons cluster between−12 and−9 with an average of−11.4.The Gyirong pegmatite shows high contents of Si,Al,and K,a high Al saturation index,and low contents of Na,Ca,Fe,Mn,P,Mg,and Ti.Overall,the Gyirong pegmatite is enriched in Rb,Cs,U,K,Th and Pb and depleted in Nb,Ta,Zr,Ti,Eu,Sr,and Ba.The samples show a high 87Sr/86Sr(16 Ma)ratio of ca.0.762 and a lowεNd(16 Ma)value of−16.0.The calculated average initial values of 208Pb/204Pb(16 Ma),207Pb/204Pb(16 Ma)and 206Pb/204Pb(16 Ma)of the whole rock are 39.72,15.79 and 19.56,respectively.The Sr-Nd-Pb-Hf isotopic characteristics of the Gyirong pegmatite are consistent with those of the GHC.This study concludes that the Gyirong pegmatite represents a typical crustal‒derived anatectic pegmatite with low metallogenic potential for rare metals.The Gyirong pegmatite records the long‒term metamorphism and partial melting process of the GHC,and reflects the crustal thickening caused by thrust compression at 39‒29 Ma and the crustal thinning induced by extensional decompression during 28‒15 Ma.
基金supported by funds from the National Natural Science Foundation of China(Grant Nos.42172067,41972064,U1906207)the SDUST Research Fund。
文摘Gneisses with anatectic characteristics from the Liansan island in the Sulu UHPM(ultra-high pressure metamorphic)belt were studied for petrography,titanite U-Pb dating and mineral geochemistry.Three origins of garnets are distinguished:metamorphic garnet,peritectic garnet and anatectic garnet,which are formed in the stages of peak metamorphism,retrograde anatexis and melt crystallization,respectively.The euhedral titanite has a high content of REE and high Th/U ratios,which is interpreted as indicating that it was newly-formed from an anatectic melt.The LA-ICP-MS titanite U-Pb dating yields 214-217 Ma ages for the titanite(melt)crystallization.The distribution of trace elements varies in response to the different host minerals at different stages.At the peak metamorphic stage,Y and HREE are mainly hosted by garnet,Ba and Rb by phengite,Sr,Nb,Ta,Pb,Th,U and LREE by allanite and Y,U and HREE by zircon.During partial melting,Y,Pb,Th,U and REE are released into the melt,which causes a dramatic decline of these element contents in the retrograde minerals.Finally,titanite absorbs most of the Nb,U,LREE and HREE from the melt.Therefore,the different stages of metamorphism have different mineral assemblages,which host different trace elements.
基金supported by the National Natural Science Foundation of China(Nos.42172148,41830431,and 41902127).
文摘The Ordovician-Silurian Wufeng and Longmaxi Shale in the Sichuan Basin were studied to understand the genesis and diagenetic evolution of carbonate minerals and their effects on reservoir quality. The results of geochemical and petrological analyses show that calcite grains have a negative Ce anomaly indicating they formed in the oxidizing environment of seawater. The high carbonate mineral contents in the margin of basin indicate that calcite grains and cores of dolomite grains appear largely to be of detrital origin. The rhombic rims of dolomite grains and dolomite concretions with the δ^(13)C of –15.46‰ and the enrichment of middle rare earth elements were formed during the sulfate-driven anaerobic oxidation of methane. The calcite in radiolarian were related to the microbial sulfate reduction for the abundant anhedral pyrites and δ^(13)C value of –11.34‰. Calcite veins precipitated in the deep burial stage with homogenization temperature of the inclusions ranging from 146.70 ℃ to 182.90 ℃. The pores in shale are mainly organic matter pores with pore size mainly in the range of 1–20 nm in diameter. Carbonate minerals influence the development of pores through offering storage space for organic matter. When calcite contents ranging from 10% to 20%, calcite grains and cement as rigid framework can preserve primary pores. Subsequently, the thermal cracking of liquid petroleum in primary pores will form organic matter pores. The radiolarian were mostly partially filled with calcite, which combining with microcrystalline quartz preserved a high storage capacity.
文摘The Elogo region has been subjected to craft industry and semi-industrial mining for gold-bearing placers, since the colonial times. It is actually undergoing an intensive exploration for a primary gold deposit. The goal of this study is to contribute to the exploration of the primary gold deposit in the Elogo Region (North-West of Congo Republic). The methodology consisted of characterization of placers deposits by their lithology, mineralogy and the gold grains shape, in order to constrain the source of gold with the respect to the local geology. The results obtained show that alluviums are polygenic and yields seventeen mineral species composed of zircon, olivine, magnetite, ilmenite, gold, garnet, rutile, coltan, cassiterite, monazite, apatite, amphibole, tourmaline, pyrite, limonite, chromite, and amphibole. The morphoscopy of gold grain shows single grains and grains with quartz inclusions that suggest their relationship with quartz veins. The gold grains are flattened, sub-flattened, and rounded. The northern region of Elogo characterized by a dominance of coarser quartz-included gold grains indicates a proximal proparte origin (less than 50 m), while the southern region, showing less coarse and more evolved grains with choc marks, appears to be associated with a distal pro-parte origin (more than 300 m). The multivariate statistical analysis shows seven classes of samples corresponding to the mineralogical paragenesis suggesting various sources, consisting of high-grade metamorphic, granitoids, pegmatites, basic and ultrabasic rocks, and BIFs that provided minerals to the placers. Gold mainly comes from hydrothermal quartz veins and probably from the peptization of gold from the weathering of sulfides occurring in the BIF. In the Elogo region, gold exploration for primary deposits should look for and follow the hydrothermal system developed in this region. Chemical analysis for the gold grains and associated minerals is necessary to better guide the proposed geochemical prospecting.
基金co-founded by the National Natural Science Foundation of China(42002090,41930428)National Key Research and Development Program of China(No.2018YFC0604200)+3 种基金Open Research Fund Program of State Key Laboratory of Nuclear Resources and Environment,East China University of Technology(No.NRE1915)Open Research Fund Program of Jiangxi Engineering Laboratory on Radioactive Geoscience and Big Data Technology(JELRGBDT202006)International Geoscience Programme(IGCP675)Jiangxi province graduate student innovation special fund project(YC2019-S271,DHYC-202001)。
文摘Hydrothermal alteration with bleaching of host rocks is the most important prospecting indicator for gold deposits in the Jiangnan Orogen Belt.The alteration has been identified as pre-ore carbonate(siderite)-sericitization and the Fe of siderite in the alteration zone is derived from the host rocks rather than fluids.In addition,such alteration decreases in intensity and width with depth and gold mineralization also occur in the non-bleached rocks,casting doubt on the reliability of the prospecting indicator.Detailed petrographic work and SEM analysis on the Wangu deposit indicate that there are two types of siderites,i.e.,Sd1 and Sd2.Among them,Sd1 grains are relatively small and distributed along the planes of unaltered host rocks,while Sd2 grains,only occurring in the altered slates,are commonly larger.Both types of siderites were altered by auriferous fluids,producing porous cores and minerals such as pyrite,quartz,and ankerite.Compared with unaltered parts,the altered parts have lower Fe,but higher U,Pb,and REE.In addition,Sd1 and Sd2 are similar in Mn,Na,V,and Sr concentrations but different in Fe and Mg.The occurrence and geochemical compositions of both siderites indicate that Sd1 could be transformed into Sd2 by pre-mineralization alteration through dissolution-reprecipitation.Chlorite is another important Fe-bearing mineral in the host rocks,and EPMA analysis suggests that it is ripidolite with relatively high Fe contents.Consequently,chlorite can also provide Fe to form the pre-ore carbonate(siderite)-sericitization.Geochemical modeling demonstrates that both ripidolite and siderite can result in sulfidation and therefore gold precipitation.As a result,this study demonstrates that pre-ore alteration with characterized bleaching is not a prerequisite for gold mineralization despite of its prominent features.Due to the presence of Fe-bearing Sd1 and chlorite,gold mineralization could still occur through sulfidation in the unaltered rocks.
基金The National Natural Science Foundation of China under contract Nos 42276084 and 42176078the Special survey items of the China Geological Survey under contract Nos DD20190205 and DD20221710。
文摘The composition,provenance,and genetic mechanism of sediment on different sedimentary units of the East China Sea(ECS)shelf are essential for understanding the depositional dynamics environment in the ECS.The sediments in the northern ECS shelf are distributed in a ring-shaped distribution centered on the southwestern Cheju Island Mud.From the inside to the outside,the grain size goes from fine to coarse.Aside from the“grain size effect”,hydrodynamic sorting and mineral composition are important restrictions on the content of rare earth elements(REEs).Based on the grain size,REEs,and clay mineral composition of 300 surface sediments,as well as the sedimentary genesis,the northern ECS shelf is divided into three geochemical zones:southwestern Cheju Island Mud Area(ZoneⅠ),Changjiang Shoal Sand Ridges(ZoneⅡ-1),Sand Ridges of the East China Sea shelf(ZoneⅡ-2).The northern ECS shelf is mostly impacted by Chinese mainland rivers(the Changjiang River and Huanghe River),and the provenance and transport mechanism of sediments of different grain sizes is diverse.The bulk sediments come primarily from the Changjiang River,with some material from the Huanghe River carried by the Yellow Sea Coastal Current and the North Jiangsu Coastal Current,and less from Korean rivers.Among them,surface sediments in the southwestern Cheju Island Mud Area(ZoneⅠ)come mostly from the Changjiang River and partly from the Huanghe River.It was formed by the counterclockwise rotating cold eddies in the northern ECS shelf,which caused the sedimentation and accumulation of the fine-grained sediments of the Changjiang River and the Huanghe River.The Changjiang Shoal Sand Ridges(ZoneⅡ-1)were developed during the early-middle Holocene sea-level highstand.It is the modern tidal sand ridge sediment formed by intense hydrodynamic action under the influence of the Yellow Sea Coastal Current,North Jiangsu Coastal Current,and Changjiang Diluted Water.The surface sediments mainly originate from the Changjiang River and Huanghe River,with the Changjiang River dominating,and the Korean River(Hanjiang River)influencing just a few stations.Sand Ridges of the East China Sea shelf(ZoneⅡ-2)are the relict sediments of the paleo-Changjiang River created by sea invasion at the end of the Last Deglaciation in the Epipleistocene.The clay mineral composition of the surface sediments in the study area is just dominated by the Changjiang River,with the North Jiangsu Coastal Current and the Changjiang Diluted Water as the main transporting currents.