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![(A) Paleogeographic Map of Rodinia (From Li et al. 2008 [35]); (B) Schematic tectonic Map of China (From Zhao et al. 2012 [36]).](publication/346877766/figure/fig1/AS:1021958556762113@1620665315236/A-Paleogeographic-Map-of-Rodinia-From-Li-et-al-2008-35-B-Schematic-tectonic-Map.jpg)
(A) Paleogeographic Map of Rodinia (From Li et al. 2008 [35]); (B) Schematic tectonic Map of China (From Zhao et al. 2012 [36]).
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Phosphorite-type rare earth deposits, which are one of the important types of rare earth elements (REE) ore deposits, have attracted increasing attention because of the extreme enrichments in heavy rare earth elements (HREE), including Yttrium (Y). In this study, in situ geochemical analyses of apatite grains from Zhijin phosphorites were conducted...
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... South China Craton lies in the center of Rodinia, between Australia and Laurentian ( Figure 1A,B). Rodinia assembled through global orogenic events between 1300 Ma and 900 Ma, while the breakup of the supercontinent began at ca. 750 Ma and was not completed until ca. ...
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... previous studies imply the mineral/seawater REY partition coefficients and the logarithm of ionic radius display a simple parabolic relation if REY is a single source [57][58][59]. According to our result, most data fall on the parabola (Figure 10) (as the Ce value deviates from other elements in Figure 9, it was removed from the scatter diagram). Thus, it also suggests that the REY in apatite is from seawater rather than other contributors. ...
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Apatite may be a common accessory mineral in coal seams, but interpretation of its origins can vary from syndepositional mineral detritus, early precipitation during diagenesis, and post coalification precipitation and replacement from hydrothermal or other fluids. It is hypothesised that paragenesis is reflected in the modes of occurrence in diffe...
Citations
... As the global demand for rare-earth resources continues to rise, it is crucial to explore new sources of REEs [1,2]. It is noteworthy that current research suggests that REEs found in phosphate deposits offer a potential solution to the global rare-earth crisis [3][4][5][6]. ...
Rare-earth elements (REEs) are often highly concentrated in sedimentary phosphate deposits, and the microdistribution characteristics and occurrence state of rare earth in these deposits play a crucial role in the overall development and utilization of mineral resources. This study aims to analyze the microdistribution of REEs in REE-bearing phosphate deposits in the Zhijin region of Guizhou at the microstructural level and investigate their occurrence modes. Specifically, rock and mineral identification, X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDS), and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) were utilized to analyze the samples. The correlation between the distribution of REEs and phosphorus was examined. In addition, the microdistribution of REEs in specific mineral phases and the locations of their occurrence were investigated. The analysis revealed that no REEs existed independently in the deposit. Instead, the distribution of REEs was highly consistent and significantly positively correlated with that of phosphorus. In the microarea structure, REEs were predominantly found both in particles, such as bioclasts, sand debris, and agglomerates, and in phosphate cement, where the main mineral components were collophane and apatite. Conversely, the content of REEs in dolomitized sand debris edges, sparry dolomitic cement, and siliceous cement was considerably lower. Based on these findings, it is speculated that REEs primarily occur within the lattice defects of apatite or on the surface of collophanite. There is a notable contrast in the REE content between the unaltered sand debris at the periphery and the dolomitized sand debris, indicating that the dolomitization in the diagenetic stage resulted in a depletion of REE abundance in the ore. Obviously, the dominant gangue mineral, dolomite, does not serve as the primary host for REEs. Furthermore, the highest concentration of REEs was inside organisms. This finding suggests that the high content of REEs in biological soft tissue may remain under the influence of waves and tides, and REE-bearing apatite may be preferentially separated and fill the cavities of deceased organisms. The second highest content of REEs was found in the shells of organisms, indicating that small shelly organisms absorb phosphorus materials through their life activities to construct their shells, resulting in REE enrichment. Quantitative analysis through sequential extraction procedures displayed that most REEs were present in the residual state, with a smaller portion combined with organic matter. These results confirm that REEs in the Zhijin phosphate deposits primarily exist as isomorphic substitutions in the lattice defects of apatite, with a secondary occurrence as organic matter-bound REEs.
... They have also become a strategic mineral resource of China [1][2][3]. At their peak, China's REE reserves accounted for 71.1% of the global total; however, this share has dropped sharply to <34% [4,5]. Therefore, the identification of new REE sources has become a priority. ...
The coal and coal-bearing measures in the Jungar Coalfield in Inner Mongolia are characterized by rare earth element (REE) enrichment. Combustion in coal-fired power plants can lead to further enrichment of REEs in coal ash, which serves as a new potential source for REE extraction and smelting. Further, investigating the content, modes of occurrence, and transformation behavior of REEs during coal combustion may help in better understanding REE differentiation during coal combustion and facilitate the development of economically feasible REE recovery technologies. Therefore, in this study, we analyzed coal ash from the Jungar Energy Gangue Power Plant in Inner Mongolia via inductively coupled plasma mass spectrometry, X-ray diffraction, and scanning electron microscopy combined with energy-dispersive spectroscopy. Our results showed that the REE content of the feed coal was 220 μg/g, slightly higher than the average for global coal. Additionally, fly ash had a higher REE content (898 μg/g) than bottom ash, and its rare earth oxide content was approximately 1152 μg/g, which meets the industrial requirements. Bottom and fly ashes contained similar minerals; however, their relative abundances were different. Specifically, mullite, quartz, calcite, and gypsum were slightly more abundant in fly ash than in bottom ash, whereas amorphous solids were slightly more abundant in bottom ash than in fly ash. Furthermore, fly ash, dominated by Si- and Al-rich minerals, was composed of irregular particles of different shapes and sizes. It also contained monazite and REE fluoro-oxides, which possibly originated from the feed coal and had mineral structures that remained unchanged during coal combustion. Thus, the REE fluoro-oxides possibly resulted from the conversion of bastnaesite in the feed coal during combustion and thereafter became attached to the edge of the Si–Al minerals in the fly ash.
... On top of that, these samples did not show a marked negative Ce anomaly with the exception of samples M3 and M4 where a negative spike can be observed for Ce/Ce* for both samples. Furthermore, the Y/Ho ratios can be used as a vector to assess whether the studied rocks reflect primary marine signatures (Y/H = 44-74; values for rocks free of contamination by some terrigenous material) or if they have been affected by siliciclastic components (Y/Ho = 23-27) (Nozaki et al., 1997;Ö zyurt et al., 2020;Xiqiang et al., 2020). In this study, the obtained Y/Ho values vary from 31.43 to 50.44, indicating that the contamination by the terrigenous materials is apparently negligible, especially in the phosphorite samples, where the Y/Ho ratio is 45.22 on average. ...
... Previous studies (Chen et al., 2003;Fazio et al., 2013;Xin et al., 2016;Garnit et al., 2017) have revealed that the REEs + Y signatures of seawater can be well preserved by CFA minerals in phosphorites, and these signatures cannot be easily altered even during the later burial or diagenesis (Shields and Stille, 2001;Xiqiang et al., 2020). Numerous geochemical parameters have been proposed to identify the diagenetic or burial influence on the REY signatures of phosphorites (Shields and Stille, 2001;Chen et al., 2003;Fazio et al., 2013;Xiqiang et al., 2020). ...
... Previous studies (Chen et al., 2003;Fazio et al., 2013;Xin et al., 2016;Garnit et al., 2017) have revealed that the REEs + Y signatures of seawater can be well preserved by CFA minerals in phosphorites, and these signatures cannot be easily altered even during the later burial or diagenesis (Shields and Stille, 2001;Xiqiang et al., 2020). Numerous geochemical parameters have been proposed to identify the diagenetic or burial influence on the REY signatures of phosphorites (Shields and Stille, 2001;Chen et al., 2003;Fazio et al., 2013;Xiqiang et al., 2020). The presence of this influence can be identified by: (i) a negative correlation between Ce/Ce* and (Dy/Sm) N ratios (Shields and Stille, 2001;Xiqiang et al., 2020); also these effects can be investigated using a plot of (La/Sm) N vs. (La/Yb) N ratios, proposed by Reynard et al. (1999) and modified by Garnit et al. (2012); (ii) a positive correlation between Ce/Ce* ratio and ΣREE, which can be generated by a progressive REE scavenging during post-depositional alteration (Shields and Stille, 2001;Alexander et al., 2008;Ö zyurt et al., 2020); (iii) a negative correlation between Ce/Ce* and (La/Sm) N , which indicates an influence of the digenesis on the Ce anomaly, or the absence of correlation between Ce/Ce* and Eu/Eu* ratios, suggesting a negligible or lack of influence of post-depositional modification on Ce anomaly (Özyurt et al., 2020). ...
... For 96 h of exposure, a maximum ∑REEs of 3222 μg/g (excluding Y) was obtained, using the optimized conditions (initial concentration of 190 μg/L, salinity 16, and seaweed dosage of 1.0 g/L). The total concentration of REE in Ulva sp. is circa of 3000-fold higher than that initially in water and also exceeds that found in common apatite ores (∑REEs 1098 -1688 μg/g) (Xiqiang et al. 2020), supporting the use of REEs-enriched seaweed biomass as an alternative to mineral ores. It is possible to further increase these concentrations by processing the biomass, namely its pyrolysis which reduces its weight by about 87 %. ...
In this study, response surface methodology (RSM) was applied with a Box–Behnken design to optimize the biosorption (removal and bioconcentration) of rare earth elements (REEs) (Y, La, Ce Eu, Gd, Tb) by living Ulva sp. from diluted industrial wastewaters (also containing Pt and the classic contaminants Hg, Pb, Zn, Cu, Co, and Cd). Element concentration (A: 10–190 μg/L), wastewater salinity (B: 15–35), and Ulva sp. dosage (C: 1.0–5.0 g/L) were the operating parameters chosen for optimization. Analysis of the Box–Behnken central point confirmed the reproducibility of the methodology and p- values below 0.0001 validated the developed mathematical models. The largest inter-element differences were observed at 24 h, with most REEs, Cu, Pb and Hg showing removals ≥ 50 %. The factor with the greatest impact (positive) on element removal was the initial seaweed dosage (ANOVA, p < 0.05). The optimal conditions for REEs removal were an initial REEs concentration of 10 μg/L, at a wastewater salinity of 15, and an Ulva sp. dosage of 5.0 g/L, attaining removals up to 88 % in 24 h. Extending the time to 96 h allowed seaweed dosage to be reduced to 4.2 g/L while achieving removals ≥ 90 %. The high concentrations in REE-enriched biomass (∑REEs of 3222 μg/g), which are up to 3000 times higher than those originally found in water and exceed those in common ores, support their use as an alternative source of these critical raw materials.
... It was urgent to find a RE reserve resource to meet the needs of industrial production Ji and Zhang, 2021). Phosphate contained all Lanthanides except Pm, in which the content of ΣRE (the total RE) was 1098~1688 ppm (Xiqiang et al., 2020). From this perspective, phosphate was a reserved RE resource and had great development value. ...
Rare earths (REs) containing phosphate rock is a potential REs resource. The unclear occurrence mechanism of REs in phosphorite limits its further development and utilization. Fluorapatite (FAP) is the main REs-bearing target mineral in phosphorite, the microscopic mechanism of REs entering FAP still needs to be further studied from the electronic scale. In this paper, the doping mechanism of REs in FAP was studied by experiment combined with GGA+U calculation. The XRD, SEM, and FT-IR characterization results of hydrothermal synthesis products showed that REs (La, Ce, Nd, and Y) entered FAP crystal, and one of every 20 Ca atoms was replaced by a REs atom. The GGA+U calculation indicated that La-O/F, Ce-O/F, Nd-O/F, and Y-O/F were ionic bonds in general, and the bonding strength of La-O/F, Ce-O/F, Nd-O/F, and Y-O/F increased gradually with atomic number. The substitution difference of La, Ce, Nd, and Y was mainly caused by the gain and loss of electrons in f and d orbitals. The substitution mechanism of REs at the characteristic sites of Fap was studied, which provided a theoretical reference for the selective recovery of REs from phosphorus blocks.
... The lacustrine shale of the Upper Fourth Member of Shahejie Formation in the Dongying Depression, Bohai Bay Basin, which has experienced a breakthrough in shale oil exploration in the last few years (Wang et al., 2016;Song et al., 2020;Zhang et al., 2022), contains widely developed CFA nodules according to observations of a dozen coring wells. However, detailed research on the formation processes of CFA nodules in lacustrine settings, which may be free from phosphatization affected by upwelling compared to marine sediments, is lacking (Jiang et al., 2007;Gao et al., 2018;Liu et al., 2020). The major objectives of the present research are (1) specifying the mineralogical and chemical characteristics, and (2) exploring the formation processes of CFA nodules. ...
A varying abundance of carbonate-bearing fluorapatite (CFA) nodules in Eocene lacustrine shale in the Bohai Bay Basin was observed; however, mineralogical and geochemical awareness is lacking, which limits the specific understanding of CFA formation mechanisms and paleoenvironmental proxies. We specified the petrology, trace elements (TE), rare earth elements and yttrium (REY) of the CFA nodules by using an integrated approach of cathodoluminescence, micro-Fourier transform infrared spectroscopy, electron microprobe analysis and laser ablation–inductively coupled plasma–mass spectrometry. The results suggest that CaO (25.85 to 39.95 wt%), P2O5 (17.19 to 29.35 wt%) and F (0.71 to 2.99 wt%) are the dominant components of the CFA nodules, with low Mn/Fe ratios and few incorporations of CO3²⁻. They show selective concentrations of Sr (avg. 14,963.3 ppm), Ba (avg. 1831.6 ppm), U (avg. 314.2 ppm), Zr (avg. 263.5 ppm), and Th (avg. 185.4 ppm) and apparent negative Y anomalies with low Y/Ho ratios (18.40 to 28.90). These CFA nodules were classified into three types according to REY patterns normalized to the Post-Archean Australian Shale (PAAS). Type A nodules enclosed by micritic calcite laminae are middle rare earth elements (MREE) enriched which yield a typical “bell-shaped” REY pattern, nonanomalies of Ce and a good correlation of ΣREY with Ce/Ce* (R² = 0.90) and Ba (R² = 0.95). Type B nodules in the clay and organic-rich laminae were better phosphatized and display more heavy rare earth elements (HREE) depletion, minimal Ce anomalies and a good correlation between CaO and P2O5 (R² = 0.84) than type A nodules. Type C nodules are rare but show light rare earth elements (LREE) enrichment relative to type A and B nodules. The adsorption of P, TE and REY by Fe-(oxyhydr)oxide and organic matter is significant for CFA formation through the “dissolution-recapture-reprecipitation” process in the ambient pore water of the Fe reduction zone during early diagenesis. The retention of HREE as HREE(CO3)²⁻ in more reducing bottom water is critical to the HREE depletion for type B and C nodules, while the release of LREE from bacterial-mediated degradation of organic matter into ambient pore water enhances the concentration of LREE on type C nodules. Deviation of the REY patterns is probably related to the differential suboxic redoxclines for the deposition of calcite-rich and clay- and organic-rich laminae of shale, which are considered the depositional environment proxies of lacustrine shale.
... This sets Ulva sp. as a captivating alternative source for the recovery of Y, as natural deposits seldom display REEs content superior to 5% in weight . For example, Y concentrations obtained in the algae tissue greatly surpasses that which is found in ores such as apatite (≈ 0.5 mg g − 1 ) (Xiqiang et al., 2020). The integration of pyrolysis in an idealized recycling process can also bring other benefits besides higher REEs yield, as some authors argue that pyrolysis of algae biomass can be a viable source of renewable energy and bio-fuel (Li et al., 2010). ...
Secondary sourcing of Rare-Earth elements (REE) from electronic waste can compensate for supply bottlenecks as well as environmental and health issues associated with ore mining. In this study, recovery of yttrium (Y) from real fluorescent lamp waste (FLW) through biosorption onto the macroalga Ulva sp. is proposed. The initial waste was composed mainly of yttrium oxides (49%) and calcium hydroxides/phosphates (23%). Response surfaces revealed that lower salinity (10) and higher sorbent mass (9 g L⁻¹) improved sorption efficiency (maximum removal of 52% and 32% for initial concentrations of 20 and 120 mg L⁻¹, respectively). Higher concentrations of Y accelerated the sorption kinetics, achieving equilibrium after 3 h. The amount of Y accumulated on the algal tissue (maximum of 22 mg g⁻¹) was not affected by algae dosage. Results show that algal-based sorbents are efficient when applied to real wastes under optimal conditions. While leachate purity still requires optimization, fast kinetics and high concentrations in the biomass indicate that Ulva sp. may constitute a viable material for the biosorption of Y obtained from FLW. Incorporating Ulva sp. biosorption into an Y recovery process will thus contribute to a green and circular economy, compensating the negative effects associating with primary ore mining.
... In this study, we studied the profiles with large ore resources, including the Gezhongwu (Figure 3a Major ore types at Zhijin are dark-/light-gray bioclasticbearing dolomitic phosphorite (dominant) and brecciated phosphorite [14,15], with the former displaying (inter) layered and banded structure (Figure 4a and b). Bioclasts in the biophosphorites are mainly dominated by small shells (Figure 5a-e), including Zhijinites and hyolithes spicules ( Figure 5a) and algal biocide (Figure 5e). ...
The Zhijin phosphorite (P)-bearing rare earth element (REE) deposit in Guizhou Province (China) hosts vast ore resources (P: 1.348 billion tonnes; REE: 1.44 Mt). Up to date, the Zhijin phosphorite resource has not been exploited because of the uncertain occurrence of the associated REEs, which hampers mineral processing and extraction. In this study, the structure, the valence state, and the coordination position of Y in the REE-yttrium-rich bioclastic samples from Zhijin were revealed by means of synchrotron radiation X-ray absorption fine structure analysis. The results show that the Y occurs as Y( iii ) in the samples, and that the form of Y is different from the Y 2 O 3 form in standard xenotime samples. Yttrium in the samples was in a complex coordination position without Y–O–Y bonding, and the Y–O bond lengths range widely without clear patterns. We suggest that Y in the samples is surrounded by organic or macro-molecular compounds, rather than in inorganic ones. Thus, Y in collophanite is unlikely to be in the form of isomorphism.
... As shown in the slope in Figure 9, the distribution of the REE content of the sedimentary apatite is more uniform. [31,34,42]. Normalization values for chondrite are from Herman (1971) [33]. ...
... Chondrite-normalized REE distribution patterns of the apatite from Madagascar analyzed in this work compared to apatite from literature. Data from[31,34,42]. Normalization values for chondrite are from Herman (1971)[33]. ...
... Chemical composition and structural formula of apatite from other origins, determined by EMPA (in wt%). Data derived from[31,[34][35][36]42].Table A4. Cont. ...
Madagascar is known as the ‘Island of Gemstones’ because it is full of gemstone resources. Apatite from Madagascar is widely popular because of its greenish blue Paraiba-like color. This study analyzes apatite from Madagascar through standard gemological characteristic methods, spectroscopic tests and chemical analyses (i.e., electron probe and laser ablation inductively coupled plasma mass spectrometry). This work explores the gemological and the diagenesis information recorded on Madagascar apatite by comparing them with apatite from other sources and establishes the origin information of Madagascar apatite. The origin characteristics are as follows: Apatite from Madagascar is fluorapatite, with excellent diaphaneity, greenish–blue color caused by Ce and Nd and crystal structure distortion indicated by spectroscopic tests. The F/Cl ratio (16.47 to 21.89) suggests its magmatic origin Cl loss during the weathering processes forming the source rocks, and lg fO2 (−10.30 to −10.35) reflects the high oxidation degree of magma.
... The normalized data obtained from the standard rare-earth value of chondrite meteorites. Taking the rare-earth elements as the abscissa, comparing the apatite samples from Morocco (Moro-1, Moro-2, Moro-3) [22], Zhijin (M1, M2, M3) [23] and Madagascar (AP1, AP2) [24], and normalizing the rare-earth elements of apatite and plotting Figure 8, the rareearth distribution of apatite in this experiment is highly consistent with other origins; it is characterized by the enrichment of light rare earths and the loss of heavy rare earths. ...
... The normalized data obtained from the standard rare-earth value of chondrite meteorites. Taking the rare-earth elements as the abscissa, comparing the apatite samples from Morocco (Moro-1, Moro-2, Moro-3) [22], Zhijin (M1, M2, M3) [23] and Madagascar (AP1, AP2) [24], and normalizing the rare-earth elements of apatite and plotting Figure 8, the rare-earth distribution of apatite in this experiment is highly consistent with other origins; it is characterized by the enrichment of light rare earths and the loss of heavy rare earths. ...
The fluorescence phenomenon of apatite is an important feature. In this paper, three apatites with uniform transition from green to blue were selected, and the fluorescence color characteristics of the samples were observed under UV fluorescent lamp and DiamondView. With 3D fluorescence technology, combined with LA-ICP-MS, this paper aims to comprehensively test the fluorescence phenomenon of apatite to explore the relationship between apatite fluorescence and elements and analyze the fluorescence color characteristics. With the experiments mentioned above, this paper explores the fluorescent color characteristics of gemstones and their influencing factors to improve the color system of apatite. UV and DiamondView experiments show that with the change from green to blue, apatites show weak purple–red to strong pink–purple fluorescence. The 3D fluorescence test shows that the samples have two notable fluorescence emission peaks: (1) The fluorescence peak group composed of the double fluorescence peaks around 600 nm is generated by the excitation light source at 450 and 470 nm and a weaker fluorescence peak generated by the excitation at 400 nm; (2) The fluorescence emission peak of the sample gradually becomes prominent and the intensity increases significantly near the areas where the excitation wavelength is 280–330 nm and where the emission wavelength is 380 nm. According to the LA-ICP-MS test combined with the element properties, the fluorescence peak group (1) is mainly affected by Mn2+, Sm3+, and Pr3+, which emit orange fluorescence. The fluorescence emission peak (2) is caused by Ce3+, Eu3+, Dy3+, and Tb3+, which emit purple fluorescence. The mixing of the two fluorescent colors results in violet–pink fluorescence.
