Search

Herein, Factsage software and sintering experiment were conducted to predict and correlate thermodynamic calculations of Fe in a synthetic solid waste and the expansion behavior of ceramsite. With the increase of Fe 2 O 3 content, the liquid phase content and viscosity in the multi-component system gradually decreased and the melting temperature range became wider. This can match with the generation of the liquid phase with proper viscosity in the ceramsite and the full expansion properties. At 400–1000 °C, iron as a network former was tetrahedrally coordinated with oxygen to form Hercynite (Al 2 FeO 4) phase; at 1180–1200 °C, iron as a network modifier dissolved into the silicate mineral structure to form the eutectic composition of Diopside (Ca 4 Mg 3.62 Fe 0.78 Si 7.6 O 24) and Ferrosolite (Si 16 Mg 5.09 Fe 10.66 Ca 0.26 O 48). The formation of iron-bearing silicate facilitated the generation of the viscous layer, so that the outer layer of the ceramsite exhibited sealing performance. Finally, a preferable porous ceramsite with compressive strength of 10.7 MPa and an apparent density of 708 kg/m3 was obtained. This study analyzes the effect of Fe 2 O 3 on the expansion behavior of porous ceramsite and provides new insight into how to analyze different solid wastes to produce ceramsite in a predictable way. [ABSTRACT FROM AUTHOR]

Background: It is unknown whether the Dietary Approaches to Stop Hypertension (DASH) dietary pattern is associated with other blood pressure (BP) variables, beyond mean systolic blood pressure (SBP) and diastolic blood pressure (DBP).Objectives: The study aimed to study the associations between the DASH dietary pattern and daytime and nighttime mean BPs and BP variance independent of the mean (VIM).Methods: A sample of 324 Chinese adults aged ≥ 60 y who were not on BP-lowering medications were included in the analysis. The DASH score was calculated using data collected by a validated FFQ. The 24-h ambulatory BP was measured and the mean and VIM SBP and DBP were calculated for both the daytime (06:00-21:59) and nighttime periods (22:00-05:59). Multivariable linear models were constructed to assess associations between the DASH dietary pattern and daytime and nighttime BP outcomes, adjusting for sociodemographic factors, lifestyle, BMI, and hypertension (clinic SBP ≥ 140 mm Hg or DBP ≥ 90 mm Hg), and sleep parameters (only for nighttime BP outcomes). An interaction term between DASH score and hypertension status was added to explore the potential differential association in normotensive and hypertensive individuals.Results: Every 1-unit increase in the DASH score was associated with a 0.18-unit (95% CI: -0.34, -0.01 unit) and a 0.22-unit (95% CI: -0.36, -0.09 unit) decrease in nighttime VIM SBP and nighttime VIM DBP, respectively. DASH score was not associated with any daytime BP outcomes, nighttime mean SBP, or nighttime mean DBP. A significant interaction (DASH score × hypertension status) was detected for VIM SBP (P-interaction = 0.04), indicating a differential association between DASH score and nighttime VIM SBP by hypertension status.Conclusions: Independently of sleep parameters and other factors, the DASH dietary pattern is associated with lower nighttime BP variability in elderly adults. [ABSTRACT FROM AUTHOR]

Coal slime is a solid waste generated during the coal washing process, and the high value-added clay minerals it contains are critical to reducing resource extraction and proactively adapting to changing policy requirements. In this work, sodium hexametaphosphate (SHMP) was selected to form thermodynamically stable complexes (i.e., Fe 7 P 6 O 24 , Fe 10 P 6 O 26 , Mg 3 P 2 O 8 , NaMgPO 4 , Na 12 Mg 4 P 10 O 35 , and Ca 5 HO 13 P 3) with exposed Fe3+, Mg2+ and Ca2+ ion sites on the surface of coal slime. The adsorption of SHMP effectively enhanced the zeta potential of the coal slime, and the energy potential increased from 5 × 10−18 J to 17 × 10−18 J, which overcame the van der Waals force at a short distance of 1–2 nm. It promoted the formation of the solvent hydration layer and achieved stable dispersion of the slurry. Meanwhile, through the magnetic difference between minerals, the kaolin in the system was purified by combined overflow filtration superconducting magnetic separation technology. Finally, under 3T/5T tandem magnetic separation conditions, the removal rates for Fe and Ti were approximately 94.96 % and 85.86 % respectively. The purified kaolin complies with Chinese kaolin categorization requirements and shares a similar composition to commercial kaolin. [ABSTRACT FROM AUTHOR]

Background and Aims: Efficient analysis strategies for complex network with cardiovascular disease (CVD) risk stratification remain lacking. We sought to identify an optimized model to study CVD prognosis using survival conditional inference tree (SCTREE), a machine-learning method.Methods and Results: We identified 5379 new onset CVD from 2006 (baseline) to May, 2017 in the Kailuan I study including 101,510 participants (the training dataset). The second cohort composing 1,287 CVD survivors was used to validate the algorithm (the Kailuan II study, n = 57,511). All variables (e.g., age, sex, family history of CVD, metabolic risk factors, renal function indexes, heart rate, atrial fibrillation, and high sensitivity C-reactive protein) were measured at baseline and biennially during the follow-up period. Up to December 2017, we documented 1,104 deaths after CVD in the Kailuan I study and 170 deaths in the Kailuan II study. Older age, hyperglycemia and proteinuria were identified by the SCTREE as main predictors of post-CVD mortality. CVD survivors in the high risk group (presence of 2-3 of these top risk factors), had higher mortality risk in the training dataset (hazard ratio (HR): 5.41; 95% confidence Interval (CI): 4.49-6.52) and in the validation dataset (HR: 6.04; 95%CI: 3.59-10.2), than those in the lowest risk group (presence of 0-1 of these factors).Conclusion: Older age, hyperglycemia and proteinuria were the main predictors of post-CVD mortality.Trial Registration: ChiCTR-TNRC-11001489. [ABSTRACT FROM AUTHOR]

• A novel C-C process was used to deep extract alumina from low-grade bauxite. • A near-neutral C-C residue with high Ca and low Al was obtained to prepare cement clinker. • The mineral transformation in alumina extraction and clinker preparation was studied. • The combined method realizes the efficient production of alumina and zero discharge. During the Bayer process for alumina production, the molecular formula of the bauxite residue is approximately equivalent to Na 2 O·Al 2 O 3 ·1.7SiO 2 · n H 2 O. This means that 1 kg of SiO 2 in bauxite will produce 1 kg of Al 2 O 3 and 0.608 kg of Na 2 O in bauxite residue. Thus, the extraction efficiency of alumina is low when processing low-grade bauxite. In addition, it is difficult to utilize bauxite tailings with solid alkali in the structure. In this study, low-grade bauxite was treated using a calcification–carbonization process. A new type of residue (C-C residue) with a different structure from that of traditional bauxite residue was obtained. A cement clinker was prepared with C-C residue as the main ingredient at a dosage of 50%. The experimental results show the alumina extraction efficiency reached 75.82% when processing low-grade bauxite of A/S 3.06 using the calcification–carbonization process. This is higher than the 61.44% of the Bayer process. The main phases of C-C residue [CaCO 3 , amorphous Ca (4−2x) Si x O 4 , and undecomposed Ca 3 Al 2 (SiO 4)(OH) 4 ] convert into Ca 2 SiO 4 , Ca 3 SiO 5 , and Ca 2 Fe x Al (2−x) O 5 after calcination. The calcification–carbonization process combined with cement production helped low-grade bauxite achieve highly efficient and clean alumina production, which is conducive to the sustainable development of alumina industry. [ABSTRACT FROM AUTHOR]

Bauxite residue is an alkaline solid waste produced during the extraction of alumina from bauxite, which causes serious environmental problems and safety risks. In this study, alkali and alumina were recovered from Bayer bauxite residue using a novel calcification-carbonisation process. This produced a non-hazardous and near-neutral residue (C-C residue), the properties of which facilitated its subsequent reuse. After the calcification-carbonisation treatment, 46.5% of the alumina was extracted and the Na 2 O content in the final residue (C-C residue) dropped to less than 0.3%. In addition, the feasibility of using C-C residue in the production of cement and the preparation of soil was analysed. The results showed that the chemical composition of C-C residue is very close to that of Portland cement clinker, which allows the dosage of bauxite residue in cement production to be increased. A comparison of the C-C residue with a general soil showed that the former performed well for many soil parameters, such as alkalinity and salinity, and has great potential for application in soil preparation. Thus, the calcification-carbonisation method, combined with cement production or soil preparation, is a sustainable process for completely reusing Bayer bauxite residue and facilitating bauxite waste minimisation. [ABSTRACT FROM AUTHOR]

To understand the adverse effects of TiO 2 on alumina leaching, the reaction behavior of TiO 2 in a series of pure substance systems relating to Bayer digestion was systematically investigated based on thermodynamics, experiments, and comprehensive analyses. The results show that TiO 2 is almost unreactive without alkali in the Bayer system. When free alkali does exist, TiO 2 preferentially forms amorphous, metastable sodium titanate as a reactive intermediate and induces more side reactions. The physicochemical characteristics and the transformation of the amorphous metastable phase were described in detail. The findings from this study provide strong evidence explaining titanate species' reduction of the dissolution efficiency of alumina through amorphization and the elimination of adverse titanate effects via promoting the crystallization of amorphous metastable phase. Knowledge of these mechanisms deepens the understanding of the effects of titanate species in the Bayer process and assists in the prevention and control of titanate industrial hazards. [ABSTRACT FROM AUTHOR]

The calcification-carbonation process is a novel cleaner production method to recover alkali and alumina from bauxite residue and obtain harmless residue with low aluminum content and no alkali. At present, this method is only limited to laboratory research and has not been put into industrial application. The reason is that the existing research only focuses on the mineral transformation of the solid phase, but lacks consideration of the concentration and availability of the extract in the liquid phase. The calcification-carbonation process is a complex hydrometallurgical series process. Without a complete continuous production line, it is difficult to evaluate the reliable concentration distribution in the system. In order to obtain the concentration distribution of Na 2 O and Al 2 O 3 in the whole calcification-carbonation process, this paper adopts a combined research method of metallurgical process simulation and experimental research based on the existing solid phase transformation theory. This method turns out to be effective and inexpensive to develop new technology at present. On the basis of the previous experimental results of solid structure transformation and parameter optimization, this study employs the material balance analysis module of METSIM software to analyze the distribution and concentration of Na 2 O and Al 2 O 3 in the calcification-carbonation process. Combined with the concentration characteristics of input and output and the experimental verification of the key steps, a multi-material circulation optimization scheme of the calcification-carbonation process through the integration of liquid material flow resources is proposed to realize the effective recovery of low-concentration Al 2 O 3 and the circulation of alkali liquor in the system. It promotes the recycling of resources and cleaner production of alumina. Image 1 • A specific scheme is designed to recover alkali and alumina from bauxite residue. • The recovered resources are enriched based on multi-material balance and circulation. • Improve the availability of recovered low-concentration components. • Promote zero discharge of pollutants and cleaner production of alumina. [ABSTRACT FROM AUTHOR]

The calcification‑carbonation method is a novel technology recovering Na 2 O and Al 2 O 3 from bauxite residue through mineral transformation, which realizes the harmless treatment of bauxite residue simultaneously. It is mainly realized by two key transformation steps such as calcification transformation and carbonation transformation of the slag phase, and multiple wet process series steps. In this paper, the research progress achieved by calcification‑carbonation method in recent years was summarized, the researches on mineral transformation law of calcification and carbonation key steps conducted by many researchers aiming at multiple sources of bauxite residue were analyzed, and finally, the optimal conditions and treatment effects of calcification‑carbonation method for red mud treatment were summarized. Based on the transformation law of the solid phase, METSIM software was used to calculate the specific distribution trend of concentration in each material flow through the material balance. Then according to the concentration characteristics of Na 2 O and Al 2 O 3 , as well as the liquid concentration requirements for calcification‑carbonation treatment, the material flow was further integrated and the resources were reasonably allocated by optimizing the existing process. This study not only provided a reference for future relevant researches but also offered analysis methods and data sources, so as to further reduce costs and promote the application of this new technology. • Review the research progress of calcification-carbonation method in recent years. • Summarize and analyze the parameter control laws of calcification and carbonation. • Combine the research methods of metallurgical process simulation and experiments. • Put forward the material flow integration and resource allocation optimization. [ABSTRACT FROM AUTHOR]

Two low cytotoxic fluorescence probes Rb1 and Rb2 detecting Fe 3+ were synthesized and evaluated. Rb1 and Rb2 exhibited an excellent selectivity to Fe 3+ , which was not disturbed by Ag + , Li + , K + , Na + , NH 4 + , Fe 2+ , Pb 2+ , Ba 2+ , Cd 2+ , Ni 2+ , Co 2+ , Mn 2+ , Zn 2+ , Mg 2+ , Hg 2+ , Ca 2+ , Cu 2+ , Ce 3+ , AcO − , Br − , Cl − , HPO 4 2− , HSO 3 − , I − , NO 3 − , S 2 O 3 2− , SO 3 2− and SO 4 2− ions. The detection limits were 1.87 × 10 −7 M for Rb1 and 5.60 × 10 −7 M for Rb2 , respectively. 1:1 stoichiometry and 1:2 stoichiometry were the most likely recognition mode of Rb1 or Rb2 towards Fe 3+ , and the corresponding OFF–ON fluorescence mechanisms of Rb1 and Rb2 were proposed. [ABSTRACT FROM AUTHOR]

Saline-alkali stress is a major abiotic stress limiting plant growth. The selection of saline-alkali-tolerant rootstock is an effective strategy to reduce salinization-alkalization influence in apple production. M. halliana is a highly saline-alkali-resistant apple rootstock in northwestern China. However, few metabolic response studies have been conducted on this species. In plants under saline-alkali stress, the uptake of K, Mg and Zn in M. halliana leaves were inhibited, whereas the absorption of Fe2+, Cu2+ or Mn2+ were increased. Metabolic analysis revealed 140 differentially expressed metabolites, which were mainly involved in alkaloid biosynthesis, phenylalanine biosynthesis, ATP-binding cassette (ABC) transporters, and mineral absorption. Especially, the expression of sucrose, amino acids, alkaloids, flavonoids and carotenoids were significantly upregulated under saline-alkali stress. qRT-PCR analysis demonstrated that NHX8 and ZTP1 involved in Na+ and Fe2+ transport were upregulated, while AKT1 , MRS2-4 and ZTP29 involved in K+, Mg2+ and Zn2+ transport were downregulated, respectively. ANT , ATP2A, CALM and SOS2 are involved in Ca2+ signal transduction, and ABCB1 , ABCC10 and NatA are key transporters that maintain ionic homeostasis. M. halliana regulates Na+/K+ homeostasis by mediating Ca2+ signalling and ABC transporters. The accumulation of metabolites contributes to improving the saline-alkali resistance of M. halliana because of the scavenging of ROS. An increase in pheophorbide a content in porphyrin and chlorophyll metabolism leads to leaf senescence in M. halliana leaves, which contributes to a reduction in stress-induced injury. These findings provide important insights into the saline-alkali tolerance mechanism in apple, which also provides an important starting point for future research. • M. halliana is a highly saline-alkali-resistant apple rootstock in northwestern China. • M. halliana regulates Na+/K+ homeostasis by mediating Ca2+ signalling and ABC transporters. • Sucrose, amino acids, alkaloids, flavonoids and carotenoids significantly accumulated under saline-alkali stress. • The accumulation of metabolites contributes to improving the saline-alkali resistance of M. halliana because of the scavenging of ROS. [ABSTRACT FROM AUTHOR]

With the rapid development of China's aluminum industry and the depletion of high-quality bauxite resources, technology for the clean and efficient utilization of non-traditional bauxite resources has become the focus in related fields. The alumina-to-silica mass ratio of low-grade high-iron sedimentary bauxite from Yunnan, China is 2.65; diaspore and goethite coexist in this bauxite. To enhance the utilization efficiency of bauxite, the hydrometallurgy process of the "calcification-carbonation method" (CCM) had been proposed, and the research results indicated that the addition of lime promoted the transformation of the goethite phase significantly, and the replacement ratio of Al in goethite decreased from 16.02% to 12.15% for a calcification temperature of 200 °C. The Gibbs free energy for the generation of Ca 3 (Fe 0.87 Al 0.13) 2 (SiO 4) 1.65 (OH) 5.4 decreases gradually with an increase in the reaction temperature, and an excessive decomposition temperature in the carbonization process is not conducive to the decomposition of the garnet phase. The calcification reaction is controlled by diffusion and chemical reaction, and the activation energy in the temperature range from 220 to 260 °C (determined using a high-pressure DSC) is 38.4 kJ/mol; it is 19.6 kJ/mol in the temperature range from 260,276.8 °C. Fe completely dissociates from hydrogarnet upon carbonization, and the main silica-containing phases in the digested slag are unreacted hydrogrossular and calcium silicate. The CCM enhanced the recovery ratios of Al 2 O 3 and Fe from high-iron diasporic bauxite by ~20% and 10%, respectively, compared with those in the Bayer process, and the Na content decreased to lower than 0.1% in the CCM slag; this can be used as cement raw material directly. Thus, the clean and efficient utilization of low-grade high-iron sedimentary bauxite was achieved using the CCM. • Diaspore and goethite coexist in the low-grade high-iron bauxite. • Promotion scale of lime on isomorphic transformation of Al in goethite was analyzed. • Fe is completely dissociated from hydrogarnet through carbonization. • Recovery ratios of Al 2 O 3 and Fe are about 20% and 10% higher than the Bayer process. • Na content in the CCM slag meets the requirement of cement raw material. [ABSTRACT FROM AUTHOR]

A hydrometallurgical calcification‑carbonation method is proposed to change the structure of the red mud of Bayer alumina production for clean utilization of low-grade bauxite resources. The utilization process consists of the flowing steps: i) silicon containing phases in bauxite are transformed into hydrogarnet; ii) hydrogarnet subsequently changed into Al(OH) 3 , CaO·SiO 2 and CaCO 3 through the carbonation process by CO 2 ; and iii) Al(OH) 3 is digested by alkali when the digestion temperature is below 100 °C. The thermodynamics of the calcification and carbonation processes were elucidated, and the effects of the saturation coefficient of SiO 2 in hydrogarnet on the new process were investigated. The results show that the silicon saturation coefficient rapidly increases with temperature. The digestion ratio of alumina from hydrogarnet exceeds 50% when the saturation coefficient is either higher than 0.79 or < 0.3. After a low-grade bauxite treatment, the alkali content in the new red mud decreases to 0.49 wt% and the A/S (ratio of alumina and silicon) decreases to below 0.5%. Furthermore, the recovery ratio of alumina increases by 15% compared to the traditional Bayer process. The new modified red mud can be used directly in the cement industry, and efficient and clean use of low-grade bauxite can be realized by this method. [ABSTRACT FROM AUTHOR]

[Display omitted] • The specific organic ligands with the NH 4 + group and nitrosamine polar group could activate the malachite surface and modify its interface structure. • The surface morphology after treatment of NaOH-immersed and organic ligands-immersed. • The adsorption mechanism have been confirmed by performing macroscopic flotation experiment. • Adsorption mechanism model of NBH on malachite surface. The adsorption mechanism between malachite and a specific organic ligand of the ammonium salt of N-Nitroso-N-phenylhydroxyamine (NBH) with the NH 4 + group and nitrosamine polar group has been studied. The tapping mode atomic force microscopy (AFM) imaging illustrated that irregular protrusions were covered on malachite surface at the nanoscale when malachite was treated in NBH solutions under alkaline conditions at pH 9.5. It indicated that the NBH displayed an excellent affinity to malachite, and the adsorption density was correlated with the concentration of NBH. Based on copper ammine theory and the results of Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the intermediate transition process of the interaction between malachite and NBH can be summarized as activation, diffusion and reduction, combination, and redeposition. The copper ions removed from the ammonia-activated malachite surface combined with the NBH resonating structures to form the bidentate and monodentate complexes. Eventually, those microscopic analyses are confirmed by the macroscopic flotation test. The flotation recovery illustrated the formation of ligand–Cu complex strengthened the hydrophobicity of malachite in a three-phase system. Therefore, it is feasible using NBH as collector to selectively separate malachite from gangue minerals in flotation experiments. [ABSTRACT FROM AUTHOR]