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Yttrium oxide with a large specific surface area (SSA) (hereafter called LSSA Y2O3) has high-porosity structure, relatively large interface, and relatively abundant active surface sites, and its optical, chemical and thermal stability properties are greatly improved compared with ordinary yttrium oxide. As a result, LSSA Y2O3 has been applied in various fields as a luminescent, catalytic, and adsorbent material, showing enormous market potential. This study creatively presents a process designed to prepare LSSA Y2O3 powders through moderate carbonation in the presence of CO2. Experimentally, CO2 was used to carbonate a yttrium hydroxide [Y(OH)3] slurry. During the initial stage of carbonation, crystalline yttrium carbonate encapsulated Y(OH)3 through heterogeneous nucleation on its surface. This encapsulation considerably improved the filterability of the carbonation product while allowing it to retain the phase structure and high-porosity morphology of Y(OH)3. Further calcination of the carbonation product produced LSSA Y2O3 with an SSA of approximately 84 m2/g. This Y2O3 powder exhibited a relatively high adsorption capacity for methyl orange and was easy to recycle and reuse, thus showing potential for use as an adsorbent. The process developed in this study for preparing LSSA Y2O3 powders through carbonation in the presence of CO2 is advantageous because it requires only moderate conditions, causes no pollution, produces products with a uniform granularity and morphology, and is easy to scale up to meet industrial demands. Therefore, this process can effectively increase the added value and market competitiveness of Y2O3 powders and provide an experimental basis and theoretical guidance for the synthesis of other rare earth (RE) compounds with large SSAs through carbonation.

The digital transformation in developing countries is crucial in determining whether environmental regulations can better facilitate green technological innovation. This paper constructs a theoretical model to deduce the relationships among digital transformation, environmental regulations, and green technological innovation. Empirical research is conducted using a two-way fixed-effects model and a threshold regression approach, based on provincial panel data from China spanning the years 2013 to 2020. The results indicate that environmental regulation inhibits green technological innovation. However, digital transformation, by reducing cost pathways, can promote the efficiency of green technological innovation under environmental regulation. This moderating effect exhibits a nonlinear threshold characteristic. Regarding dimensions of digital transformation, the level of digital investment shows no threshold, while both the level of digital application and the scale of digital integration exhibit threshold effects. Presently, in China, digital transformation effectively incentivizes green technological innovation under environmental regulation. Therefore, increasing digital investment, advancing digital applications, and fostering digital integration are inevitable choices to drive green technological innovation under the pressure of environmental regulation.

In this study, a CO2 carbonization method is introduced for the preparation of 1D yttrium oxide powders. Using YCl3 as the raw material, sodium hydroxide was initially used to completely precipitate Y3+ into yttrium hydroxide, and then CO2 was introduced into the yttrium hydroxide slurry for homogenization-like carbonization to obtain yttrium carbonate precipitation. Then, by studying the effects of carbonization conditions, such as the temperature, CO2 flow rate, and stirring speed, on the morphology and phases of yttrium carbonate, the temperature was observed to exert a greater effect than the other experimental parameters on the morphology and structure of the carbonized products. Finally, Y2(CO3)3·2H2O nanoneedles were obtained at optimal conditions. The carbonized crystals of the acicular yttrium carbonate precipitate because of the solution supersaturation and then quickly complete their crystal growth process through the oriented attachment (OA) and Ostwald ripening (OR) mechanisms. After heat treatment, yttrium carbonate retained a good crystal morphology and produced Y2O3 nanoneedles with a length of 1–2 μm and a width of 20–30 nm.

During the leaching process of ionic rare earth ore (ICREO), ion-exchangeable phase calcium (IEP-Ca) and ion-exchangeable phase aluminum (IEP-Al) are leached along with rare earth, which causes many problems in the enrichment process, such as increasing the precipitant agent consumption and rare earth loss, etc. The agitation leaching kinetics and the column leaching mass transfer process of IEP-Ca and IEP-Al were studied to understand the leaching behavior of impurity in ICREO, which provides guides for the adjustment of the leaching process and to limit the co-leaching of impurities. IEP-Ca and IEP-Al were leached by ion exchange, with the leaching agent cations and the leaching kinetics described by an internal diffusion-controlled shrinking core model with an apparent activation energy of 8.97 kJ/mol and 10.48 kJ/mol, respectively. In addition, a significant reduction in the leaching efficiency of aluminum was caused by the hydrolysis reaction reinforced by the increase in MgSO4 concentration and temperature. The leaching kinetic data of IEP-Ca and IEP-Al was verified by the column leaching mass transfer process. There was a synchronous increase in the peak concentration of the outflow curve and leaching efficiency of calcium with the concentration of MgSO4 since IEP-Ca was easily leached. Therefore, as the leaching efficiency of calcium was already very high in the 0.20 mol/L MgSO4 leaching process, the leaching rate of calcium was limited by the leaching temperature and injection rate of MgSO4. For aluminum, the hydrolysis of Al3+ was promoted by increasing the MgSO4 concentration and the leaching temperature, thereby effectively reducing the content of aluminum in the leachate.

When conducting company performance evaluations, the traditional method cannot reflect the distribution characteristics of the company’s operating conditions in the entire securities market. Gephi is an efficient tool for data analysis and visualization in the era of big data. It can convert the evaluation results of all listed companies into nodes and edges, and directly display them in the form of graphs, thus making up for the defects of traditional methods. This paper will take all the listed companies in the Shanghai and Shenzhen Stock Exchange as the analysis object. First uses tushare and web crawlers to collect the financial statement data of these companies. And then, uses the Economic Value Added model to calculate the EVA of each listed company and build graph data. Next, import the graph data into gephi to generate the distribution graph of all listed companies’ performance, and summarize the distribution characteristics of business performance. Finally, select a listed company that you want to analyze in detail, using the traditional DuPont analysis method to conduct micro level visualization analysis of the business performance to find the main factors affecting the company’s operating performance. Incorporating gephi into traditional performance analysis methods will make the results of traditional analytical methods more effective and complete. [ABSTRACT FROM AUTHOR]

The practice of in-situ leaching of the ion-adsorption type rare earth ore using (NH 4 ) 2 SO 4 had revealed serious ammonia-nitrogen pollution. Therefore, a discussion on the leaching process of the ion-adsorption type rare earth ore with the electrical double layer model was presented in this paper, so as to screen out the green and efficient leaching agent and the appropriate leaching measures to improve the rare earth leaching efficiency and reduce or even eliminate ammonia-nitrogen emissions. It was determined that the leaching process could be described as the formation of a new stable electric double layer (EDL). The potential φ ( x ) with the distance x from clay surface to bulk solution in the diffusion layer was obtained, it showed that the potential φ ( x ) would decrease with the increase of the cationic charge of leaching agent, the leaching temperature and the concentration of leaching agent, leading to a higher rare earth leaching efficiency. The theoretical analysis was verified by soak leaching experiments. The results showed that the law of rare earth leaching efficiency was in agreement with the theoretical analysis. And the rare earths partition in the leaching liquor under different conditions was substantially constant except cerium element. Therefore, the cation and anion of leaching agent should have a large electric density and be environmental friendly, of which magnesium sulfate could be preferred. Moreover, chemical substances, which could form a more stable coordination with rare earth ions, could be used as an assistant to promote the leaching equilibrium to move toward a favorable direction. This paper had provided a theoretical foundation and application basis for the leaching of rare earth from the ion-adsorption type rare earth ore, and show the direction on reducing or even eliminate ammonia-nitrogen emissions. [ABSTRACT FROM AUTHOR]

The colloidal sediment phase rare earth was little leached even if the pH of leaching agent reached 1.00, but part of it could be reduction leaching by the ferrous ion. To solve the problems appeared in the FeSO 4 leaching process, a magnesium-ferrous compound leaching was put forward in this paper. It was demonstrated that lower proportion of Mg/Fe and higher acidity of leaching agent, could result in a higher rare earth leaching efficiency and relative a bigger cerium partition in the leaching liquor. But the leaching performance of the magnesium-ferrous compound leaching system was unsatisfactory because of some problems. Therefore, another compound leaching method using MgSO 4 and ascorbic acid was proposed, taking advantage of the reducibility and the ability to strengthening the leaching process of ascorbic acid. It was shown that about 50% rare earths colloid sediment phase was dissolved into the leaching liquor when with 0.20 mol/L MgSO 4 and 0.5 g/L ascorbic acid. 85.85% rare earth leaching efficiency and a low content of Fe and Al were achieved as well. Therefore, compound leaching with MgSO 4 and ascorbic acid was proposed to an excellent alternative leaching agent for further studies, which may realize efficiency extraction, low consumption and be environmentally friendly. [ABSTRACT FROM AUTHOR]

In order to coordinate the content and ratio of ion-exchangeable calcium and ion-exchangeable magnesium in the soil and reduce ammonia nitrogen pollution, recovery of rare earth from the ion-adsorption type rare earths ore with magnesium–ammonium, magnesium–calcium and magnesium–ammonium–calcium compound leaching agent was studied in this paper. Results showed that the leaching ability was in the order of (NH 4 ) 2 SO 4 > NH 4 Cl > MgSO 4 > MgCl 2 ≈ CaCl 2 under the same total cationic charge. The content of ion-exchangeable magnesium and ion-exchangeable calcium in water washing tailings could be adjusted to be suitable for the plant growth by changing the composition of leaching agent. In the magnesium–ammonium–calcium compound leaching system, when the mole ratio of magnesium–ammonium–calcium was 15:25:60, 628.57 mg·kg − 1 ion-exchangeable magnesium and 77.77 mg·kg − 1 ion-exchangeable calcium in water washing tailings were achieved, while the ratio of ion-exchangeable calcium and magnesium was 8.08. Moreover, the aluminum leaching efficiency was only 49.2% and the rare earth leaching efficiency could be above 94%. Furthermore, the soybeans could grow normally with water washing tailings in magnesium–ammonium–calcium compound leaching system with an average plant height of 25.5 cm. The application of magnesium–ammonium–calcium compound leaching agent could significantly reduce the ammonia nitrogen pollution, maintain the soil nutrient so as to reduce the dosage of calcium–magnesium fertilizer, and may realize the ecological friendly leaching of the ion-adsorption type rare earths ore. [ABSTRACT FROM AUTHOR]

The practice of in-situ leaching of weathered crust elution-deposited rare earth ore using (NH 4 ) 2 SO 4 solution has revealed serious environmental problems such as ammonia-nitrogen pollution in water body and plant growth difficulties. The present study investigated the use of magnesium sulfate instead of (NH 4 ) 2 SO 4 as the leaching agent in the recovery of rare earth elements to solve the problem of ammonia-nitrogen pollution. It was determined that the optimum leaching condition in 298 K, a flow rate of 0.60 mL·min − 1 , and 0.20 mol·L − 1 magnesium sulfate solution, lead to 93% of total rare earth leaching efficiency and around 50% aluminum leaching efficiency. The results suggested that the magnesium sulfate was capable of producing identical recovery efficiency as (NH 4 ) 2 SO 4 and reducing aluminum leaching efficiency at the same time. In addition, the leaching mechanism was analyzed with different kinetic models, it was determined that the leaching kinetics of the weathered crust elution-deposited rare earth ore could be appropriately described by Pseudo-first-order model, which indicated that the film diffusion was rate-limiting for the leaching process. The apparent activation energy was calculated to be 8.90 kJ·mol − 1 . However, the content of ion-exchangeable magnesium in rare earth washing tailings was 560 mg per kilogram soil. This would lead to an imbalance of ion-exchangeable calcium and ion-exchangeable magnesium, which would have a bad effect on the plant growth. Based on these findings, the synergic leaching with magnesium salt and calcium salt was identified as an excellent alternative leaching agent for further studies. [ABSTRACT FROM AUTHOR]

To reduce the consumption of MgSO 4 and to leach the colloidal sediment phase rare earth, a MgSO 4 -ascorbic acid compound leaching agent was introduced to deal with the ion-adsorption type rare earth ore. The ascorbic acid was used as an assistant to enhance the leaching of the ion-exchangeable phase rare earth and to reductively leach the colloidal sediment phase rare earth, making use of its ability to coordinate with rare earth ions and its reductive properties. It was determined that the total rare earth leaching efficiency was 86.2% and the Ce partition was 5.62% at a flow rate of 0.60 mL/min, an initial pH of 2.50, a liquid to ore ratio of 1.30 mL/g, and 0.15 mol/L magnesium sulfate and 1.0 g/L ascorbic acid in the leaching agent. The concentrations of Al and Fe in the leaching liquor were 21.36 mg/L and 30.22 mg/L, respectively. Moreover, the contents of the ion-exchangeable phase and the colloidal sediment phase rare earth in the leaching tailings were 0.03‰ and 0.06‰, respectively. The leaching efficiency of the colloidal sediment phase rare earth was approximately 57.1%. Hence, an alternative process would be provided for the leaching of rare earth from ion-adsorption type rare earth ore. The process could reduce the consumption of MgSO 4 and would have great significance for environmentally-friendly extraction of ion-adsorption type rare earth ore and the improvement of resource utilization. [ABSTRACT FROM AUTHOR]

The ion-adsorption type rare earths ore contains natural U, 232 Th and 226 Ra. The production of this kind of rare earth concentrate will produce a lot of waste residue and wastewater. It may cause the radioactive pollution and the wastage of radioactive resources. In this paper, a quantitative analysis on the migration and enrichment of natural radionuclides in the extraction process of the ion-adsorption type rare earths ore was developed. The column leaching, impurity removal, precipitation and roasting process were carried out according to the actual extraction process conditions. The related results about RE and Al did accord with the actual production index. For natural radionuclides, most of the radionuclides in the raw ore were retained in the tailings, and only 3.31% natural U, 0.08% 232 Th and 0.62% 226 Ra migrated into leaching liquor because the partial release of the exchangeable phase and carbonates phase. The radionuclides in the leaching liquor were finally distributed in the impurity slay (about 0.30% natural U, 0.057% 232 Th and 0.016% 226 Ra), the precipitated liquor (about 1.89% natural U, 0.012% 232 Th and 0.59% 226 Ra) and the rare earth concertrate (about 1.03% natural U, 0.009% 232 Th and 0.019% 226 Ra). Moreover, the radionuclides contents in impurities slag and rare earth concentrate were greatly improved than it in the raw ore, being 79.18 mg·kg − 1 natural U, 122.59 mg·kg − 1 232 Th, 1.83 × 10 − 6 mg·kg − 1 226 Ra in impurities slag and 284.07 mg·kg − 1 natural U, 19.95 mg·kg − 1 232 Th, 2.31 × 10 − 6 mg·kg − 1 226 Ra in rare earth concentrate. These part of the radionuclides might could be further enriched by optimum solubilizing, and then recycled by extraction in an economic way. What's more, the radioactive specific activities in the different types of samples were much lower than the specific activities threshold of radioactive waste, and would have little harm to the human body. The research of the migration and enrichment of natural radionuclides in the extraction process had provided accurate and reliable data support for the radioactive pollution prevention and the recovery of radionuclides. [ABSTRACT FROM AUTHOR]

Aim: In order to supply a scientific basis for uniting the normal reference value standard of hemoglobin of Chinese middlescent women., Methods: A research is made about the relationship between the normal reference value of 25,917 examples of hemoglobin of middlescent women and altitude in 268 areas in China, the normal reference values of hemoglobin of middlescent women are determined by the hemoglobincyanide method., Results: The correlation between the normal reference value of hemoglobin of middlescent women and altitude is quite significant (r = 0.827). By using the method of univariate linear regression analysis, one regression equation is inferred., Conclusion: If the altitude values are obtained in some areas, the normal reference value of hemoglobin of middlescent women of this area can be reckoned by using the regression equation. Furthermore, depending on the altitude, China can be divided into three districts: Qingzang District, Central District, and Eastern District.