The green energy transition relies heavily on critical metals,such as rare earth elements(REEs).However,their reserves are primarily focused in a few countries,such as China,which accounts for approximately 70%of glob...The green energy transition relies heavily on critical metals,such as rare earth elements(REEs).However,their reserves are primarily focused in a few countries,such as China,which accounts for approximately 70%of global production.Hence,several countries are currently looking for alternative resources for REEs.Alternative REE resources in the supply chain include recycling of e-waste,industrial waste like red mud and phosphogypsum,coal ash,mine tailings,ocean floor sediments,and even certain types of sedimentary deposits like phosphorites where REEs are present in lower concentrations but at larger volumes compared to primary ore deposits which are becoming targets by REEs industry.Currently,several studies are going on the development of eco-friendly REEs extraction technologies from phosphorite deposits.Consequently,advanced data analysis tools,such as Machine Learning(ML),are becoming increasingly important in mineral prospectivity and are rapidly gaining traction in the earth sciences.Phosphorite deposits are mainly used to manufacture fertilizers as these rocks are known for their significant phosphorus content.Moreover,these formations are considered a prospective resource of REEs.The different types of phosphorite deposits such as continental,seamount,and ore deposits worldwide reported concentrations of∑REE upto 18,000µg/g.Due to the augmented claim of REEs for various ultra-modern,and green technology applications that are required to switch over to a carbon-neutral environment,these phosphorite deposits have become an important target mostly because of their relatively higher content of REEs especially heavy rare earth elements(HREE).For example,Mississippian phosphorites reported ∑ HREE 7,000µg/g.To have a comprehensive understanding of the REEs potential of these phosphorite deposits which also include several Chinese phosphorite deposits,this study is undertaken to review the phosphorite deposits in the world and their REEs potential,in addition to some of the associated aspects such as applications and formation mechanisms for different types of phosphorite deposits such as igneous phosphate deposits,sedimentary phosphorite deposits,marine phosphorite deposits,cave phosphate deposits,and insular guano deposits.Other important aspects include their occurrences,types,geochemical characteristics,the REEs enrichment mechanisms,and various recovery methods adopted to recover REEs from different phosphorite deposits.The present review paper concludes that the recent studies highlight the global potential of phosphorite deposits to satisfy the increasing demand for REEs.Extracting REEs from phosphorite presents no significant technological or environmental difficulties,as long as radioactive elements are eliminated.In India,more comprehensive geological surveys,along with the advancement of new methods and evaluations,are required to locate phosphorite deposits with high concentrations of REEs.展开更多
Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and m...Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.展开更多
It is generally considered that a significant change in oceanic redox conditions occurred during the Ediacaran-Cambrian transition. However, there are currently two major conflicting views on the degree of oxygenation...It is generally considered that a significant change in oceanic redox conditions occurred during the Ediacaran-Cambrian transition. However, there are currently two major conflicting views on the degree of oxygenation of deep water（oxic vs. ferruginous） during this interval. To date, the oxygenation conditions of the Early Cambrian ocean have not been well constrained. The oxygenation magnitude and mechanism of the Early Cambrian ocean could be critical to the significant biological evolution of the ＂Cambrian Explosion＂. To constrain the Early Cambrian oceanic redox environment, we conducted an integrated study on iron and sulfur isotopes and redox-sensitive elements（Mo, U, and V） of Lower Cambrian phosphorite deposits from two shallow sections（Meishucun and Gezhongwu） and a deeper water section（Zunyi） from the Yangtze Platform, South China. The near zero δ^（56）Fe values from the two shallow sections studied here reflect oxic conditions in the lower phosphorite deposition. An obvious positive shift in δ^（56）Fe and redox-sensitive element content was observed in the middle parts of the two shallow water sections, which might reflect loss of light iron by dissimilatory iron reduction during early diagenesis under suboxic shallow water in the platform. However, the highly positive δ^（56）Fe values in the deep section could reflect a lower oxidation degree of dissolved Fe（II） under anoxic deep water. The data suggest redox-stratified oceanic conditions during the Early Cambrian, in which completely oxygenated shallow water（platform） coexisted with anoxic deep water（slope）. We propose that prolonged upwelling of dissolved organic carbon（DOC）-, Fe（II）- and phosphorus-rich anoxic deep water in a redox-stratified ocean could have increased exchange with the open ocean, resulting in major phosphorite deposition in oxic-suboxic conditions. The progressive oxygenation of the ocean may have facilitated the Early Cambrian biotic diversification.展开更多
Analysis on P205 and REE （rare earth elements） in basal Cambrian phosphorites from the Yangtze Region, showed that the phosphorites from Bailongtan in Yunnan Province, Zhijin, Jinsha, Xishui, Zunyi, Tianzhu and Tong...Analysis on P205 and REE （rare earth elements） in basal Cambrian phosphorites from the Yangtze Region, showed that the phosphorites from Bailongtan in Yunnan Province, Zhijin, Jinsha, Xishui, Zunyi, Tianzhu and Tongren in Guizhou Province, Shan- grao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province contained high REE contents in phos- phorites, especially those from Tianzhu and Tongren in Guizhou Province, Shangrao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province. Among them, the highest REE contents reached up to 1361.59×10^-6 and P205 contents up to 29.45%. In contrast, phosphorites from Kaiyang, Qingzhen and Zhenyuan in Guizhou Province had relatively low total REE con- tents and low P205 contents, with the lowest total REE content of 53.19× 10^-6, and the lowest P205 content of 0.07%. REE contents exhibited a positive correlation with phosphorous contents, indicating a close genetic relationship between REE and phosphorous ele- ment. The main reason was the difference of the sedimentary environments and the contents of phosphorous and REE in deep water mass formed in upwelling currents, at an upper slope facies （Slu） in reducing condition due to relatively closed sedimentary environ- ment. It was very difficult for the upswelling phosphorous and REE to deposit, massive phosphorous deposits were hard to be formed. At a deep water ramp facies （DRa） in the ascending process of currents, phosphorus and REE underwent differentiation rather than sedimentation. Consequently, the contents of P205 sediments and REE were low. At a shallow water ramp facies （including shoals and tidal flats） （SRa）, with active seawater circulation and phosphatic supplement, sunny weather, high nutrition and rapid growth of algae, were benefitial for the physical enrichment of carbonate sediments. Therefore, massive phosphorite deposits were easy to be tbrmed with abundant REE minerals, and finally turned into high REE beating phosphorous deposits.展开更多
Large phosphorite deposits in Central Guizhou,China,were formed around the Precambrian/Cambrian boundary(PC/C),including the Ediacaran(Doushantuo stage)and early Cambrian(Gezhongwu stage).Among them,Gezhongwu phosphor...Large phosphorite deposits in Central Guizhou,China,were formed around the Precambrian/Cambrian boundary(PC/C),including the Ediacaran(Doushantuo stage)and early Cambrian(Gezhongwu stage).Among them,Gezhongwu phosphorite from Zhijin are enriched in rare earth elements(REE)plus yttrium(REY),reaching 3.503 million tons.Although phosphorites have attracted great attention,the specific sources P and REY remained unclear.To determine the P and REY sources and establish a phosphogenic model of PC/C phosphorite,we present an integrated dataset of Mo and phosphate O isotopes for the first time,along with carbonate C and O isotopes,geology,petrology,and geochemistry.In all samples,d18Op,Y/Ho,and Zr/Hf decreased from the Ediacaran to the early Cambrian,indicating increased terrigenous weathering fluxes while decreased upwelling water input.Furthermore,terrigenous weathering delivery significantly elevated marine REY concentrations in the Cambrian in Zhijin.The Ceanom and d98/95Mo suggest that seawater was oxidized in the later Ediacaran and became entirely oxic in the early Cambrian.The positive feedback between oxygen levels in atmosphere and primary productivity caused progressive oxygenation in ocean-atmosphere system and enable phosphorites to be formed by different mechanisms.Results show that the Lower Doushantuo consist of abiotic intraclasts and exhibited“seawaterlike”REY types,indicating abiological and mechanical reworking phosphogenesis.The Upper Doushantuo and Gezhongwu Formation contained mainly microbial debris and abiogenic intraclasts,and exhibit “hat-shaped”REY plots,suggesting microbially mediated phosphogenesis.Based on this data set,we developed a phosphogenic model illustrating formation of these two phosphorite deposits,wherein the Lower Doushantuo phosphorite formed through the reworking of pre-existing phosphatic sediments in anoxic and abiotic ocean,whereas the Upper Doushantuo and Gezhongwu phosphorite formed via microbial metabolisms in oxic and biotic conditions.Our study has implications on the PC/C phosphorite generative processes,as well as paleoenvironmental conditions.展开更多
Zhijin County in Western Guizhou is one of the most important production areas of phosphorites in China. In order to investigate genesis of the phosphorites, their REE compositions were analyzed by using inductively c...Zhijin County in Western Guizhou is one of the most important production areas of phosphorites in China. In order to investigate genesis of the phosphorites, their REE compositions were analyzed by using inductively coupled plasma emission mass spectrometry (ICP-MS) method. For comparison, phosphorites from the Lower Cambrian black rock series in Southern China, such as Zunyi in Guizhou and Zhangjiajie in Hunan Province, were also analyzed. The analytical data show that: (1) Xinhua phosphorites possess a quite high and greatly varied total rare earth elements (ΣREE), which varying between 164.23×10-6 and 1395.01×10-6 with average of 642.54×10-6, remarkable differentiation between light (LREE) and heavy rare earth elements (HREE), and the ΣLREE/ΣHREE ratios varying between 5.04 and 6.52. The ΣREE and ΣLREE/ΣHREE ratios of the Zunyi and Zhangjiajie phosphorites are 156.69×10-6～637.41×10-6 with average of 431 75×10-6 and 3.17～6.95 with average of 4.37 respectively; (2) All the phosphorites from Xinhua, Zunyi and Zhangjiajie show remarkable negative Ce anomalies. Besides, the Xinhua phosphorites possess lower δCe, which varying between 0.26 and 0.53 with average of 0.35, while δCe of the Zunyi and Zhangjiajie phosphorites are 0.30～0.66 with average of 0.47, suggesting that all of the phosphorites are typical marine sediments deposited mainly in ancient peri-continental seas, and the depositional position of the Xinhua phosphorite might be deeper; (3) Most phosphorites from Xinhua, Zunyi and Zhangjiajie possess unremarkable positive Eu anomaly, and only a few of samples show obvious ones. The δEu varies between 0.98 and 2.4, suggesting that hot (>200 ℃) and strong reductive hydrothermal fluids might have been involved in genesis of the phosphorites; (4) The Xinhua phosphorite is relatively depleted in HREE, and LaN/NdN and δY of most samples are >1 and >1.5 respectively. Besides, there exists no correlation between δY and δCe, suggesting that the phosphorite was subjected to quite strong weathering and leaching processes, and catagenesis do not greatly modify its REE compositions.展开更多
The separation and extraction of associated rare earths from the Zhijin phosphorite mine is of great interest. Based on previous studies, the hydrolysis of phosphate ore using hydrochloric acid was systematically stud...The separation and extraction of associated rare earths from the Zhijin phosphorite mine is of great interest. Based on previous studies, the hydrolysis of phosphate ore using hydrochloric acid was systematically studied through extensive testing. Experiments were conducted to separate and recover the rare earths from the hydrolysis solution. Kinetic studies on the acidolysis of phosphorite using hydrochloric acid show that the use of hydrochloric acid in the acidolysis of phosphorite is mainly controlled by a chemical reaction and is also a diffusion-controlled reaction. When 210 L of HCL per 100 kg of phosphorite was used at 30 ℃ for 360 min, 96.1% of the P_2 O_5 and 95.0% of the rare earths are leached from the phosphorite. After defluorination and purification, the pH of the phosphate-acid solution is adjusted to 2.1 using sodium hydroxide, and a rare earth concentrate with rare earth content of 1.76 wt%is obtained; i.e., 90.1% of the rare earths are recovered. The rare earth content is increased to more than5 wt% through multiple enrichment processes, with a total yield of 59.5%.展开更多
The phosphorite ores-deposits rich in rare earth elements(REE) in Zhijin, Xinhua, Guizhuo occurs in the early Cambrian Meishucun and at the bottom part of Qiongzhusi stage (the upper layer of phosphorites), belonging ...The phosphorite ores-deposits rich in rare earth elements(REE) in Zhijin, Xinhua, Guizhuo occurs in the early Cambrian Meishucun and at the bottom part of Qiongzhusi stage (the upper layer of phosphorites), belonging to Yangzi stratum section. The living creature scraps was proved existent in dolomitic-phosphorites by experiments, The REE could be extracted to provide the worthy data for the further using. Adopting the HNO3 to extract REE, through the ion exchange method, the REE recovery rate could be reached 85.44% , having certain reference value.展开更多
Zhijin phosphorite is one of super large-scale medium-low grade and REE-bearing phosphorite deposit in Southwest of China. Previous investigations had revealed that this deposit contained appreciable amounts of rare e...Zhijin phosphorite is one of super large-scale medium-low grade and REE-bearing phosphorite deposit in Southwest of China. Previous investigations had revealed that this deposit contained appreciable amounts of rare earth elements (REE) reaching up to 1300 μg·g-1. In this paper, REE contents and existing state in single collophanite and dolomite mineral were further analyzed by ICP-MS and EPMA-1600 Electric Probe methods. The results indicated that REE content of collophanite was far more than that of dolomite, and increased with an increase of phosphor. There existed independent minerals of REE in single collophanite mineral, such as cerianite and monazite, but the amount of them was extremely little. No independent mineral of yttrium was found in this investigation. Presumedly, REE and yttrium were present in the form of ions in the lattices of collophanite. Based on above investigation, the two-stage reverse flotation technology was carried out to see the distribution of REE in flotation process. It was found that REE was mainly enriched in phosphate concentrate and recovered in the rough stage flotation. REE recovery of concentrate increased with an increase of P2O5 content and P2O5 recovery of concentrate. Under the optimum flotation condition, REE recovery was 79.25% in the rough stage flotation and 9.94% in scavenging flotation.展开更多
Yttrium(Y)is a critical metallic element that is used widely in modern scientific,technological,and industrial applications.Phosphorites in the Zhijin area of Guizhou Province,China,are famous for Y enrichment,but the...Yttrium(Y)is a critical metallic element that is used widely in modern scientific,technological,and industrial applications.Phosphorites in the Zhijin area of Guizhou Province,China,are famous for Y enrichment,but the enrichment characteristics and sources remain unclear.Previous studies suggested that the sources of rare earth elements(REEs,La-Lu)and Y(REYs,La-Lu+Y)were related to hydrothermal deposition.However,this study presents evidence refuting that hypothesis,with major and trace elemental data collected with quadrupoleinductively coupled plasma-mass spectrometry(Q-ICPMS)analysis.These data show that Y in Zhijin REYscontaining phosphorites has a normal distribution and is particularly enriched relative to other REYs.The Y enrichment degree is different at different∑REY intervals.Specifically,the Y enrichment degree is higher at lower∑REY values and lower at higher∑REY values.The REYs-containing phosphorites show features of primary phosphorites.Both REEs and Y have good correlations with P2 O5 in the phosphorites with low REYs contents(total REYs<535 ppm),whereas at high REYs contents(total REYs>535 ppm),REEs have a good correlation with P2 O5 but Y does not.Inconsistent enrichment processes of REYs are suggestive of complex sources of Y.Thus,seafloor hydrothermal fluids were not the direct source of Y.Normal seawater mixed with terrestrial sources might have contributed to the origin of Y here.This study could lead to improvements in Y mineral resource explorations and the situation involving the global REYs supply crisis.展开更多
Phosphorite nodule beds are discovered in the black shale of basal Niutitang Formation throughout the Yangtze Platform in South China, recording an important phosphorite-generation event. Platform-wide phosphorite pre...Phosphorite nodule beds are discovered in the black shale of basal Niutitang Formation throughout the Yangtze Platform in South China, recording an important phosphorite-generation event. Platform-wide phosphorite precipitation requires special oceanographic and geochemical conditions, thus the origin of the Niutitang phosphorite nodules may provide valuable information about the ocean chemistry in the Early Cambrian. In this study, we measured sulfur and oxygen isotopic compositions of sulfate extracted from phosphorite nodules collected from the basal Niutitang Formation. Phosphorite associated sulfate（PAS） is a trace amount of sulfate that incorporates into crystal lattice during phosphorite precipitation, accordingly PAS records the geochemical signals during phosphorite nodule formation. Sulfur isotopic composition of PAS（δ^（34）S_（PAS）） ranges from-1.16‰ to ＋24.48‰（mean=＋8.19‰, n=11）, and oxygen isotopic value（δ^（18）O_（PAS）） varies between-5.3‰ and ＋26.3‰（mean=＋7.0‰, n=8）. Most phosphorite nodules have low δ^（34）SPAS and low δ^（18）O_（PAS） values, suggesting PAS mainly derived from anaerobic oxidation of H_2S within suboxic sediment porewater. We propose that phosphate was delivered to the Yangtze Platform by a series of upwelling events, and was scavenged from seawater with the precipitation of FeOOH. The absorbed phosphate was released into suboxic porewater by the reduction of FeOOH at the oxic-suboxic redox boundary in sediments, and phosphorite nodule precipitated by the reaction of phosphate with Ca^（2＋） diffused from the overlying seawater. The platform-wide deposition of phosphorite nodules in the basal Niutitang Formation implies the bottom water might be suboxic or even oxic, at least sporadically, in Early Cambrian. We speculate that the intensified ocean circulation as evident with frequent occurrences of upwelling events might be the primary reason for the episodic oxidation of the Yangtze Platform in Early Cambrian.展开更多
Most of the phosphorite deposits in the world contain isomorphism rare earths （RE） which are considerably difficult to be leached into solution in the wet phos- phoric acid process. In this work, a systematic study ...Most of the phosphorite deposits in the world contain isomorphism rare earths （RE） which are considerably difficult to be leached into solution in the wet phos- phoric acid process. In this work, a systematic study of leaching RE using sulfuric acid, phosphoric acid, mixed acid and two-step leaching of phosphoric acid and sulfuric acid was performed. The aims are to illuminate the main factors that inhibit RE leaching and to provide insights into the further enrichment of RE in the wet phosphoric acid solution. The results indicate that H2SO4 is not an effective acid for leaching isomorphism RE from phosphorite ore. The low RE leaching efficiency attributes to the RE cocrystallized and encapsulated by phosphogypsum （PG） as well as the precipitation of RE by RE sulfates or phosphates. High concentration of H3PO4 can enhance the dissolution and diffusion of RE ions. Hence, the optimized leaching mode of improving RE leaching efficiency is to adequately dissolve phosphorite ores in high concentration of H3PO4 solution and then add H2SO4 to crystallize PG. The effect of corystallization or encapsulation of PG on RE can be decreased due to the crystallizing mode of PG in the bulk solution instead of on the interface of solid reactants. RE leaching efficiency can be high up to 65% by the optimized leaching mode.展开更多
Phosphorite has become increasingly important as the raw material for phosphatic fertilizer. Phosphorite nodules are widespread in the Kursk complex deposit (Russian platform). Genesis of these nodules has long been a...Phosphorite has become increasingly important as the raw material for phosphatic fertilizer. Phosphorite nodules are widespread in the Kursk complex deposit (Russian platform). Genesis of these nodules has long been a matter of debate, and this has hampered understanding of the mechanism and controls in the formation of the nodules. In this paper, we report the petrographical, mineralogical, and geochemical data of the Lebedinsky phosphorite nodules. Petrographic study reveals complex phosphatic cement resulting in the replacement of apatite minerals around quartz grains. The main mineral composition consists of quartz, phosphate minerals (apatite, francolite mainly), feldspar, iron hydroxides and carbonate minerals. These results, when combined with available data, are used to address the origin of the phosphorite nodules. The nodules are characterized by the universal presence of biogenic and chemical signatures which is phosphorus crown around crystal grains. The structure of the nodules is massive. Their texture is depicted by basaltic cement and concretion, which consists mainly of apatite and its varieties, with general formula: Ca_10 (PO_4, CO_3) 6(F,OH,Cl). Variation of mineralogy appears dependent on geological setting. Microscopic observations of biogenic fossils in Lebedinsky phosphorite favor a chemical and biogenic origin of phosphorites. Weathering has been suggested to be capable of liberating as much as 20 %-35 % P_2O_5 from sedimentary rocks. Previous investigations demonstrate that weathering of the Proterozoic substratum was the main cause in the formation of Fe, Mo, Mn, Pb, Zn, and P in the Russian platform. We therefore suggest that both weathering and biochemical processes have been positive in the formation of the Lebedinsky phosporite nodules. However, whether continental weathering or oceanic bio-chemical processes are more relevant in the phosphorite accumulation remains undetermined.展开更多
The rare earth element（REE） data from the Paleoproterozoic Bijawar basin,Sonrai phosphorites were used to interpret the depositional conditions of the phosphorites.The post archean Australian shales（PAAS） normaliz...The rare earth element（REE） data from the Paleoproterozoic Bijawar basin,Sonrai phosphorites were used to interpret the depositional conditions of the phosphorites.The post archean Australian shales（PAAS） normalized REE patterns of the Sonrai phosphorites were characterized by negative Ce and positive Eu anomalies.Middle rare earth elements（MREE）-enrichment was a characteristic feature.Phosphorites showing the diagenetic effects on the REE patterns were limited.The observed Eu anomaly was indicative of an anoxic（or sulphate reducing） diagenetic environment of phosphate formation.Mixing of sea water and upwelling during the Paleoproterozoic was responsible for the recording of positive Eu and negative Ce anomalies in the Sonrai phosphorites.展开更多
This paper concerns deals with?biogeologic?accumulation and their peculiarities, lithological unites of the phosphorite-bearing formations of these basins and an evolution of the old biota. Old bedded phosphorites are...This paper concerns deals with?biogeologic?accumulation and their peculiarities, lithological unites of the phosphorite-bearing formations of these basins and an evolution of the old biota. Old bedded phosphorites are believed to be connected with specific biogeological events happening in the Neoproterozoic glaciation, which was followed by rapid deglaciation,?Ediacaran bioradiation and the “great” postglacial transgression bearing phosphorites at its initial phase. The Mongolian phosphate basins give evidence of this phenomenon. Khubsugul basin is located in the northern Mongolia. The Neoproterozoic-Cambrian phosphorite-bearing khubsugul group is subdivided into 3 formations as ongolik, kheseen and erkhelnuur which are rich in organic fossils (a group of cyanobacterial mats, archaeocyaths, trilobites) in the ascending order. The Zavkhan basin lies in the western Mongolia. The Ediacaran-lower Cambrian sediments are divided into five formations: Maikhanuul (diamictites), Tsagaanolom (phosphorite-bearing carbonate), Bayangol, Salaanygol and Khairkhan. All the formations contain the paleontological fossils (algae, sponges, cyanobacterial mats, ichnocoenosis, soft-bodied fauna, archaeocyaths, etc.). Bedded phosphorites are the object for comprehensive research of bacterial paleontology. It is shown at example of the Mongolian Khubsugul and Zavkhan sea shelf phosphate basins. The expounded actual material clearly shows that the heterogeneous biologic activity, suitable geologic (transgressive systems tracts) and paleogeographic (glaciations, warm climate, etc.) conditions played an important role in the formation and accumulation of the biogenic bedded phosphorites.展开更多
The authors investigated the effect of Bacillus mucilaginosus on weathering of phosphorite. Analysis of different proteins was of significance in exploring the molecular biological mechanism in the bacterial weatherin...The authors investigated the effect of Bacillus mucilaginosus on weathering of phosphorite. Analysis of different proteins was of significance in exploring the molecular biological mechanism in the bacterial weathering process. The concrete methods are described as follows: Mineral powder was put into liquid culture medium and B. mucilaginosus was incubated in the medium. The control (group) had no mineral powder in the medium. The treatments and controls were cultured simultaneously under the same condition. In a few days, the supernatant was filtrated, the main cations (Ca2+, Mg2+, Na+, Mn2+, Al3+, Fe3+, K+) were measured by ICP-OES, and the contents of water soluble phosphorus (Pws) and silicon (Siws) were determined by colorimetry. The residual solid was weighed on the filter paper, followed by digestion with concentrated HNO3. The concentrations of the main cations and Pws, Siws in the digest liquid were measured by using the method mentioned above. After the supernatant was centrifuged, the precipitation was used to analyze the protein differences between the treatment groups and the control groups by 2-dimentional gel electrophoresis (2-DE). The experimental results showed that apatite and quartz were partially weathered, but kaolinite was dissolved completely. The population of bacteria increased when mineral powder was added in the liquid medium. Software analysis and comparison of the 2-DE pictures of bacterial proteins revealed 1134 visible protein spots in the treatment group, and 729 visible protein spots in the control group. To compare the bacterial protein expression contents of the treatment group with those of the control group, there were 496 different protein spots, including 214 protein spots which indicated that the protein contents increased, 75 protein spots were indicative of a decrease, and 207 proteins were newly synthesized. It is proposed that the increased bacterial contents may be related to some protein expression and activation after the input of mineral powder. Newly synthesized proteins, the increase of expression contents and the reduction of proteins may be connected with bacterial metabolic regulations, cell activation and signal transmission.展开更多
The Cambrian Gezhongwu Formation in Southwest China is the lowest Cambrian phosphorite unit. The Formation belongs to the Meishucun stage with small shelly fossils. Rare-earth element (REE) data from the Gezhongwu pho...The Cambrian Gezhongwu Formation in Southwest China is the lowest Cambrian phosphorite unit. The Formation belongs to the Meishucun stage with small shelly fossils. Rare-earth element (REE) data from the Gezhongwu phosphorites of Zhijin documented the depositional conditions. The total REE concentrations are high in the Gezhongwu phosphorites, which are especially rich in yttrium. The PAAS-normalized REE patterns of the Gezhongwu phosphorites are characterized by negative Ce anomalies and slight enrichment of MREE, as being hat-shaped. The hat-shaped patterns suggest that the REE originated from depositional environments rather than from subsequent diagenesis. The negative Ce anomalies indicate that the depositional environments are oxic. The positive Eu anomaly, the high total REE and the hat-shaped REE pattern revealed contributions from the normal marine environment mixed with hydrothermal water to the REE budget of the Gezhongwu phosphorites.展开更多
Egyptian phosphorites from Abu Tartur (Western Desert), El Mahamide mine (Nile Valley) and Rabah mine (Eastern Desert) show variable degrees of relative REE enrichment. Black plateau phosphorites of Abu Tartur are sub...Egyptian phosphorites from Abu Tartur (Western Desert), El Mahamide mine (Nile Valley) and Rabah mine (Eastern Desert) show variable degrees of relative REE enrichment. Black plateau phosphorites of Abu Tartur are substantially enriched in REE as compared to the Red Sea and Nile Valley phosphorites. P-rich organic matter from the Abu Tartur and Rabah mines recorded negative Ce and positive Eu anomalies. Positive Eu anomaly reveals an anoxic event prior to the phase of Late Cretaceous phosphate formation. Ce is a redox indicator. Mixing of sea water and upwelling during the Late Cretaceous was responsible for the recording of positive Eu and negative Ce anomalies in the Egyptian phosphorites.展开更多
The RE and composition of trace elements analysis show that phosphorite-ores are rich in ∑ RE concentration generally in Xinhua, Zhijin.The phosphorites were measured to gather LRE and HRE element.It is higher than o...The RE and composition of trace elements analysis show that phosphorite-ores are rich in ∑ RE concentration generally in Xinhua, Zhijin.The phosphorites were measured to gather LRE and HRE element.It is higher than other rocks.The phosphorite has enriched Y, La and Nd chemical element.There are leading characteristics of concentrated La, LRE and Y, HRE.The chondrite-normalized RE element patterns of the Xinhua dolomitic phosphorite distribute mode for rightwards type to one side of the curve.LRE/HRE ＞ 1, (La/Sm)N ＞ (Gd/Yb)N, and all indicate that LRE content is higher than HRE.The test mode of chemical analysis of single mineral, chemistry phase analysis, scan electric analysis and micro-electronics probe analysis were adopted.The chart of EDAX showed that there was representative element-Y(RE) in exsiting.There was no independent mineral of the RE.It is show that part of the few rare earth chemical element is adsorbed by the clay mineral, much for the type of quality isomorphic form exist in the apatite crystal structure of phosphorite inside.展开更多
Geochemical characteristics of scandium are described with respect to its source, evolution and correlation with REE as observed in Late Sinian and Early Cambrian phosphorites and tuffs in Guizhou. Comparison of chond...Geochemical characteristics of scandium are described with respect to its source, evolution and correlation with REE as observed in Late Sinian and Early Cambrian phosphorites and tuffs in Guizhou. Comparison of chondrite\|normalized REE patterns and some other parameters between the phosphorite and tuff shows that scandium and REE are most likely to have been derived from earlier or contemporaneous marine volcanics or tuffs, with no indication of genetic link to the purple shales, siltstones and dolomites in the area. The conditions under which the Sc bearing phosphorites were formed are discussed in the light of sulfur isotopes and Eh Ph constrains.展开更多
基金the Anusandhan National Research Foundation(ANRF),Science and Engineering Research Board(SERB),Department of Science&Technology,Government of India for a start-up research grant(M-14/0599,Sanction order no.SRG/2022/001478)Seed Grant under Institutions of Eminence(IoE),Banaras Hindu University(BHU)(Dev.Scheme No.6031)for financial assistance.
文摘The green energy transition relies heavily on critical metals,such as rare earth elements(REEs).However,their reserves are primarily focused in a few countries,such as China,which accounts for approximately 70%of global production.Hence,several countries are currently looking for alternative resources for REEs.Alternative REE resources in the supply chain include recycling of e-waste,industrial waste like red mud and phosphogypsum,coal ash,mine tailings,ocean floor sediments,and even certain types of sedimentary deposits like phosphorites where REEs are present in lower concentrations but at larger volumes compared to primary ore deposits which are becoming targets by REEs industry.Currently,several studies are going on the development of eco-friendly REEs extraction technologies from phosphorite deposits.Consequently,advanced data analysis tools,such as Machine Learning(ML),are becoming increasingly important in mineral prospectivity and are rapidly gaining traction in the earth sciences.Phosphorite deposits are mainly used to manufacture fertilizers as these rocks are known for their significant phosphorus content.Moreover,these formations are considered a prospective resource of REEs.The different types of phosphorite deposits such as continental,seamount,and ore deposits worldwide reported concentrations of∑REE upto 18,000µg/g.Due to the augmented claim of REEs for various ultra-modern,and green technology applications that are required to switch over to a carbon-neutral environment,these phosphorite deposits have become an important target mostly because of their relatively higher content of REEs especially heavy rare earth elements(HREE).For example,Mississippian phosphorites reported ∑ HREE 7,000µg/g.To have a comprehensive understanding of the REEs potential of these phosphorite deposits which also include several Chinese phosphorite deposits,this study is undertaken to review the phosphorite deposits in the world and their REEs potential,in addition to some of the associated aspects such as applications and formation mechanisms for different types of phosphorite deposits such as igneous phosphate deposits,sedimentary phosphorite deposits,marine phosphorite deposits,cave phosphate deposits,and insular guano deposits.Other important aspects include their occurrences,types,geochemical characteristics,the REEs enrichment mechanisms,and various recovery methods adopted to recover REEs from different phosphorite deposits.The present review paper concludes that the recent studies highlight the global potential of phosphorite deposits to satisfy the increasing demand for REEs.Extracting REEs from phosphorite presents no significant technological or environmental difficulties,as long as radioactive elements are eliminated.In India,more comprehensive geological surveys,along with the advancement of new methods and evaluations,are required to locate phosphorite deposits with high concentrations of REEs.
基金Project supported by Guizhou Provincial Basic Research Program (Natural Science)(Qian Ke He Basic-ZK 2024 General 626)National Natural Science Foundation of China (52164018)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology (13210025)。
文摘Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.
基金the National Basic Research Program of China (No. 2014CB440906)the National Natural Science Foundation of China (Nos. 41273024, 41573011)+2 种基金Youth Innovation Promotion Association CAS, "West Light" of CAS, the 12th Five-Year Plan project of the State Key Laboratory of Ore Deposit Geochemistry, CAS (No. SKLODG-ZY125-07)MLR Public Benefit Research Foundation (No. 201411044)China Geological Survey Foundation (No. 1212011120354)
文摘It is generally considered that a significant change in oceanic redox conditions occurred during the Ediacaran-Cambrian transition. However, there are currently two major conflicting views on the degree of oxygenation of deep water（oxic vs. ferruginous） during this interval. To date, the oxygenation conditions of the Early Cambrian ocean have not been well constrained. The oxygenation magnitude and mechanism of the Early Cambrian ocean could be critical to the significant biological evolution of the ＂Cambrian Explosion＂. To constrain the Early Cambrian oceanic redox environment, we conducted an integrated study on iron and sulfur isotopes and redox-sensitive elements（Mo, U, and V） of Lower Cambrian phosphorite deposits from two shallow sections（Meishucun and Gezhongwu） and a deeper water section（Zunyi） from the Yangtze Platform, South China. The near zero δ^（56）Fe values from the two shallow sections studied here reflect oxic conditions in the lower phosphorite deposition. An obvious positive shift in δ^（56）Fe and redox-sensitive element content was observed in the middle parts of the two shallow water sections, which might reflect loss of light iron by dissimilatory iron reduction during early diagenesis under suboxic shallow water in the platform. However, the highly positive δ^（56）Fe values in the deep section could reflect a lower oxidation degree of dissolved Fe（II） under anoxic deep water. The data suggest redox-stratified oceanic conditions during the Early Cambrian, in which completely oxygenated shallow water（platform） coexisted with anoxic deep water（slope）. We propose that prolonged upwelling of dissolved organic carbon（DOC）-, Fe（II）- and phosphorus-rich anoxic deep water in a redox-stratified ocean could have increased exchange with the open ocean, resulting in major phosphorite deposition in oxic-suboxic conditions. The progressive oxygenation of the ocean may have facilitated the Early Cambrian biotic diversification.
基金Project supported by National Natural Science Foundation of China(50164001)the State Programs of Science and Technology Development funded by The Ministry of Science and Technology of China(2007BAB08B03)+3 种基金the Outstanding Scientific and Technological Talents Fund of Guizhou Province(2009008)the Graduates Innovation Fund of Guizhou University(2010009)the Youth Fund of Guizhou University(2009070)the Youth Fund of College of Resources and Environmental Engineering,Guizhou University(ZHY0901)
文摘Analysis on P205 and REE （rare earth elements） in basal Cambrian phosphorites from the Yangtze Region, showed that the phosphorites from Bailongtan in Yunnan Province, Zhijin, Jinsha, Xishui, Zunyi, Tianzhu and Tongren in Guizhou Province, Shan- grao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province contained high REE contents in phos- phorites, especially those from Tianzhu and Tongren in Guizhou Province, Shangrao in Jiangxi Province, Jiangshan in Zhejiang Province and Nanjing in Jiangsu Province. Among them, the highest REE contents reached up to 1361.59×10^-6 and P205 contents up to 29.45%. In contrast, phosphorites from Kaiyang, Qingzhen and Zhenyuan in Guizhou Province had relatively low total REE con- tents and low P205 contents, with the lowest total REE content of 53.19× 10^-6, and the lowest P205 content of 0.07%. REE contents exhibited a positive correlation with phosphorous contents, indicating a close genetic relationship between REE and phosphorous ele- ment. The main reason was the difference of the sedimentary environments and the contents of phosphorous and REE in deep water mass formed in upwelling currents, at an upper slope facies （Slu） in reducing condition due to relatively closed sedimentary environ- ment. It was very difficult for the upswelling phosphorous and REE to deposit, massive phosphorous deposits were hard to be formed. At a deep water ramp facies （DRa） in the ascending process of currents, phosphorus and REE underwent differentiation rather than sedimentation. Consequently, the contents of P205 sediments and REE were low. At a shallow water ramp facies （including shoals and tidal flats） （SRa）, with active seawater circulation and phosphatic supplement, sunny weather, high nutrition and rapid growth of algae, were benefitial for the physical enrichment of carbonate sediments. Therefore, massive phosphorite deposits were easy to be tbrmed with abundant REE minerals, and finally turned into high REE beating phosphorous deposits.
基金supported by the United Foundation of National Natural Science Foundation of China(Grant Numbers:41972095,U181240004,9206220039)the Public Beneficial,Basic Geological Project of Department of Land and Resources of Guizhou Province(Grant Number:2016-09-1).
文摘Large phosphorite deposits in Central Guizhou,China,were formed around the Precambrian/Cambrian boundary(PC/C),including the Ediacaran(Doushantuo stage)and early Cambrian(Gezhongwu stage).Among them,Gezhongwu phosphorite from Zhijin are enriched in rare earth elements(REE)plus yttrium(REY),reaching 3.503 million tons.Although phosphorites have attracted great attention,the specific sources P and REY remained unclear.To determine the P and REY sources and establish a phosphogenic model of PC/C phosphorite,we present an integrated dataset of Mo and phosphate O isotopes for the first time,along with carbonate C and O isotopes,geology,petrology,and geochemistry.In all samples,d18Op,Y/Ho,and Zr/Hf decreased from the Ediacaran to the early Cambrian,indicating increased terrigenous weathering fluxes while decreased upwelling water input.Furthermore,terrigenous weathering delivery significantly elevated marine REY concentrations in the Cambrian in Zhijin.The Ceanom and d98/95Mo suggest that seawater was oxidized in the later Ediacaran and became entirely oxic in the early Cambrian.The positive feedback between oxygen levels in atmosphere and primary productivity caused progressive oxygenation in ocean-atmosphere system and enable phosphorites to be formed by different mechanisms.Results show that the Lower Doushantuo consist of abiotic intraclasts and exhibited“seawaterlike”REY types,indicating abiological and mechanical reworking phosphogenesis.The Upper Doushantuo and Gezhongwu Formation contained mainly microbial debris and abiogenic intraclasts,and exhibit “hat-shaped”REY plots,suggesting microbially mediated phosphogenesis.Based on this data set,we developed a phosphogenic model illustrating formation of these two phosphorite deposits,wherein the Lower Doushantuo phosphorite formed through the reworking of pre-existing phosphatic sediments in anoxic and abiotic ocean,whereas the Upper Doushantuo and Gezhongwu phosphorite formed via microbial metabolisms in oxic and biotic conditions.Our study has implications on the PC/C phosphorite generative processes,as well as paleoenvironmental conditions.
文摘Zhijin County in Western Guizhou is one of the most important production areas of phosphorites in China. In order to investigate genesis of the phosphorites, their REE compositions were analyzed by using inductively coupled plasma emission mass spectrometry (ICP-MS) method. For comparison, phosphorites from the Lower Cambrian black rock series in Southern China, such as Zunyi in Guizhou and Zhangjiajie in Hunan Province, were also analyzed. The analytical data show that: (1) Xinhua phosphorites possess a quite high and greatly varied total rare earth elements (ΣREE), which varying between 164.23×10-6 and 1395.01×10-6 with average of 642.54×10-6, remarkable differentiation between light (LREE) and heavy rare earth elements (HREE), and the ΣLREE/ΣHREE ratios varying between 5.04 and 6.52. The ΣREE and ΣLREE/ΣHREE ratios of the Zunyi and Zhangjiajie phosphorites are 156.69×10-6～637.41×10-6 with average of 431 75×10-6 and 3.17～6.95 with average of 4.37 respectively; (2) All the phosphorites from Xinhua, Zunyi and Zhangjiajie show remarkable negative Ce anomalies. Besides, the Xinhua phosphorites possess lower δCe, which varying between 0.26 and 0.53 with average of 0.35, while δCe of the Zunyi and Zhangjiajie phosphorites are 0.30～0.66 with average of 0.47, suggesting that all of the phosphorites are typical marine sediments deposited mainly in ancient peri-continental seas, and the depositional position of the Xinhua phosphorite might be deeper; (3) Most phosphorites from Xinhua, Zunyi and Zhangjiajie possess unremarkable positive Eu anomaly, and only a few of samples show obvious ones. The δEu varies between 0.98 and 2.4, suggesting that hot (>200 ℃) and strong reductive hydrothermal fluids might have been involved in genesis of the phosphorites; (4) The Xinhua phosphorite is relatively depleted in HREE, and LaN/NdN and δY of most samples are >1 and >1.5 respectively. Besides, there exists no correlation between δY and δCe, suggesting that the phosphorite was subjected to quite strong weathering and leaching processes, and catagenesis do not greatly modify its REE compositions.
基金supported by Key Industrial Engineering Project of Guizhou Province([2013]3041)High-level Talent Project of Guizhou Province(TZJF-2011-54)Guizhou Science and Technology Support Plan Project([2017]2892)
文摘The separation and extraction of associated rare earths from the Zhijin phosphorite mine is of great interest. Based on previous studies, the hydrolysis of phosphate ore using hydrochloric acid was systematically studied through extensive testing. Experiments were conducted to separate and recover the rare earths from the hydrolysis solution. Kinetic studies on the acidolysis of phosphorite using hydrochloric acid show that the use of hydrochloric acid in the acidolysis of phosphorite is mainly controlled by a chemical reaction and is also a diffusion-controlled reaction. When 210 L of HCL per 100 kg of phosphorite was used at 30 ℃ for 360 min, 96.1% of the P_2 O_5 and 95.0% of the rare earths are leached from the phosphorite. After defluorination and purification, the pH of the phosphate-acid solution is adjusted to 2.1 using sodium hydroxide, and a rare earth concentrate with rare earth content of 1.76 wt%is obtained; i.e., 90.1% of the rare earths are recovered. The rare earth content is increased to more than5 wt% through multiple enrichment processes, with a total yield of 59.5%.
基金Project supported by the National Natural Science Foundation of China (40372047, 50164001)
文摘The phosphorite ores-deposits rich in rare earth elements(REE) in Zhijin, Xinhua, Guizhuo occurs in the early Cambrian Meishucun and at the bottom part of Qiongzhusi stage (the upper layer of phosphorites), belonging to Yangzi stratum section. The living creature scraps was proved existent in dolomitic-phosphorites by experiments, The REE could be extracted to provide the worthy data for the further using. Adopting the HNO3 to extract REE, through the ion exchange method, the REE recovery rate could be reached 85.44% , having certain reference value.
基金the Natural Science Foundation of Guizhou Province (QianKeHe J[2005]2098)
文摘Zhijin phosphorite is one of super large-scale medium-low grade and REE-bearing phosphorite deposit in Southwest of China. Previous investigations had revealed that this deposit contained appreciable amounts of rare earth elements (REE) reaching up to 1300 μg·g-1. In this paper, REE contents and existing state in single collophanite and dolomite mineral were further analyzed by ICP-MS and EPMA-1600 Electric Probe methods. The results indicated that REE content of collophanite was far more than that of dolomite, and increased with an increase of phosphor. There existed independent minerals of REE in single collophanite mineral, such as cerianite and monazite, but the amount of them was extremely little. No independent mineral of yttrium was found in this investigation. Presumedly, REE and yttrium were present in the form of ions in the lattices of collophanite. Based on above investigation, the two-stage reverse flotation technology was carried out to see the distribution of REE in flotation process. It was found that REE was mainly enriched in phosphate concentrate and recovered in the rough stage flotation. REE recovery of concentrate increased with an increase of P2O5 content and P2O5 recovery of concentrate. Under the optimum flotation condition, REE recovery was 79.25% in the rough stage flotation and 9.94% in scavenging flotation.
基金supported by the National Natural Science Foundation of China (No. U1812402)the Public Beneficial and Basic Geological Project from the Department of Land and Resources of Guizhou Province (No. 2016-09-1)。
文摘Yttrium(Y)is a critical metallic element that is used widely in modern scientific,technological,and industrial applications.Phosphorites in the Zhijin area of Guizhou Province,China,are famous for Y enrichment,but the enrichment characteristics and sources remain unclear.Previous studies suggested that the sources of rare earth elements(REEs,La-Lu)and Y(REYs,La-Lu+Y)were related to hydrothermal deposition.However,this study presents evidence refuting that hypothesis,with major and trace elemental data collected with quadrupoleinductively coupled plasma-mass spectrometry(Q-ICPMS)analysis.These data show that Y in Zhijin REYscontaining phosphorites has a normal distribution and is particularly enriched relative to other REYs.The Y enrichment degree is different at different∑REY intervals.Specifically,the Y enrichment degree is higher at lower∑REY values and lower at higher∑REY values.The REYs-containing phosphorites show features of primary phosphorites.Both REEs and Y have good correlations with P2 O5 in the phosphorites with low REYs contents(total REYs<535 ppm),whereas at high REYs contents(total REYs>535 ppm),REEs have a good correlation with P2 O5 but Y does not.Inconsistent enrichment processes of REYs are suggestive of complex sources of Y.Thus,seafloor hydrothermal fluids were not the direct source of Y.Normal seawater mixed with terrestrial sources might have contributed to the origin of Y here.This study could lead to improvements in Y mineral resource explorations and the situation involving the global REYs supply crisis.
基金supported by the Natural Science Foundation of China (Nos. 41272017, 41322021)Chinese Geological Survey Program (No. 1212011120622)
文摘Phosphorite nodule beds are discovered in the black shale of basal Niutitang Formation throughout the Yangtze Platform in South China, recording an important phosphorite-generation event. Platform-wide phosphorite precipitation requires special oceanographic and geochemical conditions, thus the origin of the Niutitang phosphorite nodules may provide valuable information about the ocean chemistry in the Early Cambrian. In this study, we measured sulfur and oxygen isotopic compositions of sulfate extracted from phosphorite nodules collected from the basal Niutitang Formation. Phosphorite associated sulfate（PAS） is a trace amount of sulfate that incorporates into crystal lattice during phosphorite precipitation, accordingly PAS records the geochemical signals during phosphorite nodule formation. Sulfur isotopic composition of PAS（δ^（34）S_（PAS）） ranges from-1.16‰ to ＋24.48‰（mean=＋8.19‰, n=11）, and oxygen isotopic value（δ^（18）O_（PAS）） varies between-5.3‰ and ＋26.3‰（mean=＋7.0‰, n=8）. Most phosphorite nodules have low δ^（34）SPAS and low δ^（18）O_（PAS） values, suggesting PAS mainly derived from anaerobic oxidation of H_2S within suboxic sediment porewater. We propose that phosphate was delivered to the Yangtze Platform by a series of upwelling events, and was scavenged from seawater with the precipitation of FeOOH. The absorbed phosphate was released into suboxic porewater by the reduction of FeOOH at the oxic-suboxic redox boundary in sediments, and phosphorite nodule precipitated by the reaction of phosphate with Ca^（2＋） diffused from the overlying seawater. The platform-wide deposition of phosphorite nodules in the basal Niutitang Formation implies the bottom water might be suboxic or even oxic, at least sporadically, in Early Cambrian. We speculate that the intensified ocean circulation as evident with frequent occurrences of upwelling events might be the primary reason for the episodic oxidation of the Yangtze Platform in Early Cambrian.
基金financially supported by the National Natural Science Foundation of China (Nos. 51364005, 51564003 and 51574094)
文摘Most of the phosphorite deposits in the world contain isomorphism rare earths （RE） which are considerably difficult to be leached into solution in the wet phos- phoric acid process. In this work, a systematic study of leaching RE using sulfuric acid, phosphoric acid, mixed acid and two-step leaching of phosphoric acid and sulfuric acid was performed. The aims are to illuminate the main factors that inhibit RE leaching and to provide insights into the further enrichment of RE in the wet phosphoric acid solution. The results indicate that H2SO4 is not an effective acid for leaching isomorphism RE from phosphorite ore. The low RE leaching efficiency attributes to the RE cocrystallized and encapsulated by phosphogypsum （PG） as well as the precipitation of RE by RE sulfates or phosphates. High concentration of H3PO4 can enhance the dissolution and diffusion of RE ions. Hence, the optimized leaching mode of improving RE leaching efficiency is to adequately dissolve phosphorite ores in high concentration of H3PO4 solution and then add H2SO4 to crystallize PG. The effect of corystallization or encapsulation of PG on RE can be decreased due to the crystallizing mode of PG in the bulk solution instead of on the interface of solid reactants. RE leaching efficiency can be high up to 65% by the optimized leaching mode.
文摘Phosphorite has become increasingly important as the raw material for phosphatic fertilizer. Phosphorite nodules are widespread in the Kursk complex deposit (Russian platform). Genesis of these nodules has long been a matter of debate, and this has hampered understanding of the mechanism and controls in the formation of the nodules. In this paper, we report the petrographical, mineralogical, and geochemical data of the Lebedinsky phosphorite nodules. Petrographic study reveals complex phosphatic cement resulting in the replacement of apatite minerals around quartz grains. The main mineral composition consists of quartz, phosphate minerals (apatite, francolite mainly), feldspar, iron hydroxides and carbonate minerals. These results, when combined with available data, are used to address the origin of the phosphorite nodules. The nodules are characterized by the universal presence of biogenic and chemical signatures which is phosphorus crown around crystal grains. The structure of the nodules is massive. Their texture is depicted by basaltic cement and concretion, which consists mainly of apatite and its varieties, with general formula: Ca_10 (PO_4, CO_3) 6(F,OH,Cl). Variation of mineralogy appears dependent on geological setting. Microscopic observations of biogenic fossils in Lebedinsky phosphorite favor a chemical and biogenic origin of phosphorites. Weathering has been suggested to be capable of liberating as much as 20 %-35 % P_2O_5 from sedimentary rocks. Previous investigations demonstrate that weathering of the Proterozoic substratum was the main cause in the formation of Fe, Mo, Mn, Pb, Zn, and P in the Russian platform. We therefore suggest that both weathering and biochemical processes have been positive in the formation of the Lebedinsky phosporite nodules. However, whether continental weathering or oceanic bio-chemical processes are more relevant in the phosphorite accumulation remains undetermined.
文摘The rare earth element（REE） data from the Paleoproterozoic Bijawar basin,Sonrai phosphorites were used to interpret the depositional conditions of the phosphorites.The post archean Australian shales（PAAS） normalized REE patterns of the Sonrai phosphorites were characterized by negative Ce and positive Eu anomalies.Middle rare earth elements（MREE）-enrichment was a characteristic feature.Phosphorites showing the diagenetic effects on the REE patterns were limited.The observed Eu anomaly was indicative of an anoxic（or sulphate reducing） diagenetic environment of phosphate formation.Mixing of sea water and upwelling during the Paleoproterozoic was responsible for the recording of positive Eu and negative Ce anomalies in the Sonrai phosphorites.
文摘This paper concerns deals with?biogeologic?accumulation and their peculiarities, lithological unites of the phosphorite-bearing formations of these basins and an evolution of the old biota. Old bedded phosphorites are believed to be connected with specific biogeological events happening in the Neoproterozoic glaciation, which was followed by rapid deglaciation,?Ediacaran bioradiation and the “great” postglacial transgression bearing phosphorites at its initial phase. The Mongolian phosphate basins give evidence of this phenomenon. Khubsugul basin is located in the northern Mongolia. The Neoproterozoic-Cambrian phosphorite-bearing khubsugul group is subdivided into 3 formations as ongolik, kheseen and erkhelnuur which are rich in organic fossils (a group of cyanobacterial mats, archaeocyaths, trilobites) in the ascending order. The Zavkhan basin lies in the western Mongolia. The Ediacaran-lower Cambrian sediments are divided into five formations: Maikhanuul (diamictites), Tsagaanolom (phosphorite-bearing carbonate), Bayangol, Salaanygol and Khairkhan. All the formations contain the paleontological fossils (algae, sponges, cyanobacterial mats, ichnocoenosis, soft-bodied fauna, archaeocyaths, etc.). Bedded phosphorites are the object for comprehensive research of bacterial paleontology. It is shown at example of the Mongolian Khubsugul and Zavkhan sea shelf phosphate basins. The expounded actual material clearly shows that the heterogeneous biologic activity, suitable geologic (transgressive systems tracts) and paleogeographic (glaciations, warm climate, etc.) conditions played an important role in the formation and accumulation of the biogenic bedded phosphorites.
基金the financial support from the Ministry of Science and Technology of China(Grant No.2006CB403200)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KZCX3-SW-140)the National Natural Science Foundation of China(Grant No.40773069).
文摘The authors investigated the effect of Bacillus mucilaginosus on weathering of phosphorite. Analysis of different proteins was of significance in exploring the molecular biological mechanism in the bacterial weathering process. The concrete methods are described as follows: Mineral powder was put into liquid culture medium and B. mucilaginosus was incubated in the medium. The control (group) had no mineral powder in the medium. The treatments and controls were cultured simultaneously under the same condition. In a few days, the supernatant was filtrated, the main cations (Ca2+, Mg2+, Na+, Mn2+, Al3+, Fe3+, K+) were measured by ICP-OES, and the contents of water soluble phosphorus (Pws) and silicon (Siws) were determined by colorimetry. The residual solid was weighed on the filter paper, followed by digestion with concentrated HNO3. The concentrations of the main cations and Pws, Siws in the digest liquid were measured by using the method mentioned above. After the supernatant was centrifuged, the precipitation was used to analyze the protein differences between the treatment groups and the control groups by 2-dimentional gel electrophoresis (2-DE). The experimental results showed that apatite and quartz were partially weathered, but kaolinite was dissolved completely. The population of bacteria increased when mineral powder was added in the liquid medium. Software analysis and comparison of the 2-DE pictures of bacterial proteins revealed 1134 visible protein spots in the treatment group, and 729 visible protein spots in the control group. To compare the bacterial protein expression contents of the treatment group with those of the control group, there were 496 different protein spots, including 214 protein spots which indicated that the protein contents increased, 75 protein spots were indicative of a decrease, and 207 proteins were newly synthesized. It is proposed that the increased bacterial contents may be related to some protein expression and activation after the input of mineral powder. Newly synthesized proteins, the increase of expression contents and the reduction of proteins may be connected with bacterial metabolic regulations, cell activation and signal transmission.
文摘The Cambrian Gezhongwu Formation in Southwest China is the lowest Cambrian phosphorite unit. The Formation belongs to the Meishucun stage with small shelly fossils. Rare-earth element (REE) data from the Gezhongwu phosphorites of Zhijin documented the depositional conditions. The total REE concentrations are high in the Gezhongwu phosphorites, which are especially rich in yttrium. The PAAS-normalized REE patterns of the Gezhongwu phosphorites are characterized by negative Ce anomalies and slight enrichment of MREE, as being hat-shaped. The hat-shaped patterns suggest that the REE originated from depositional environments rather than from subsequent diagenesis. The negative Ce anomalies indicate that the depositional environments are oxic. The positive Eu anomaly, the high total REE and the hat-shaped REE pattern revealed contributions from the normal marine environment mixed with hydrothermal water to the REE budget of the Gezhongwu phosphorites.
文摘Egyptian phosphorites from Abu Tartur (Western Desert), El Mahamide mine (Nile Valley) and Rabah mine (Eastern Desert) show variable degrees of relative REE enrichment. Black plateau phosphorites of Abu Tartur are substantially enriched in REE as compared to the Red Sea and Nile Valley phosphorites. P-rich organic matter from the Abu Tartur and Rabah mines recorded negative Ce and positive Eu anomalies. Positive Eu anomaly reveals an anoxic event prior to the phase of Late Cretaceous phosphate formation. Ce is a redox indicator. Mixing of sea water and upwelling during the Late Cretaceous was responsible for the recording of positive Eu and negative Ce anomalies in the Egyptian phosphorites.
基金Projbect supported by the National Natural Science Foundation of China(50164001 )
文摘The RE and composition of trace elements analysis show that phosphorite-ores are rich in ∑ RE concentration generally in Xinhua, Zhijin.The phosphorites were measured to gather LRE and HRE element.It is higher than other rocks.The phosphorite has enriched Y, La and Nd chemical element.There are leading characteristics of concentrated La, LRE and Y, HRE.The chondrite-normalized RE element patterns of the Xinhua dolomitic phosphorite distribute mode for rightwards type to one side of the curve.LRE/HRE ＞ 1, (La/Sm)N ＞ (Gd/Yb)N, and all indicate that LRE content is higher than HRE.The test mode of chemical analysis of single mineral, chemistry phase analysis, scan electric analysis and micro-electronics probe analysis were adopted.The chart of EDAX showed that there was representative element-Y(RE) in exsiting.There was no independent mineral of the RE.It is show that part of the few rare earth chemical element is adsorbed by the clay mineral, much for the type of quality isomorphic form exist in the apatite crystal structure of phosphorite inside.
文摘Geochemical characteristics of scandium are described with respect to its source, evolution and correlation with REE as observed in Late Sinian and Early Cambrian phosphorites and tuffs in Guizhou. Comparison of chondrite\|normalized REE patterns and some other parameters between the phosphorite and tuff shows that scandium and REE are most likely to have been derived from earlier or contemporaneous marine volcanics or tuffs, with no indication of genetic link to the purple shales, siltstones and dolomites in the area. The conditions under which the Sc bearing phosphorites were formed are discussed in the light of sulfur isotopes and Eh Ph constrains.
