Effects of slag composition on H2 generation and magnetic precipitation from molten steelmaking slag-steel reaction

In this paper, the effects of slag composition (slag basicity CaO/SiO2 and FeO concentration) on the amounts of H2 gas generated and the magnetic spinel phase precipitated as a result of the reaction between synthetic steelmaking slag and steam at 1873 K (1600 °C) were studied by thermodynamic simulation (using Thermodynamic Package FactSage 7.0) and laboratory experiments. The thermodynamic calculation showed that, upon increasing slag basicity (CaO/SiO2) from 1.0 to 2.5, for the reaction of 100 g of slags with 100 g of H2O gas, the accumulated amount of the produced H2 gas increased from 0.17 to 0.27 g, while the amount of magnetic spinel phase first increased and then decreased, with the maximum precipitation of 16.71 g at the basicity of 1.5. When the FeO concentration increased from 15 to 30 pct for the slag with basicity of 2.0, the accumulated amount of the produced H2 gas increased from 0.17 to 0.28 g, and the amount of magnetic spinel phase increased from 5.88 to 10.59 g. The laboratory experiments were conducted in confocal laser scanning microscope to verify the reaction between 0.2 g of slag and 3.75 L of H2O-Ar gas (PH2O=0.2atm). The results indicated that, for 100 g of slags, upon increasing slag basicity (CaO/SiO2) from 1.0 to 2.5, both the produced H2 gas and magnetic spinel phase first increased and then decreased, with the maximum amounts being 0.09 g of gas and 37.00 g of magnetic spinel phase at the slag basicity of 1.50. For the FeO concentration increasing from 15 to 30 pct, the amounts of both the produced H2 gas and magnetic spinel phase increased from 0.04 to 0.10 g and from 18.00 to 27.00 g, respectively. The reaction rate between the molten CaO-SiO2-FeO-MnO-Al2O3-MgO slag and the moisture (PH2O=0.2atm) increased with the increasing FeO activity in the slag. The dependence of the reaction rate (mol/cm2/s) on FeO content can be expressed as r=(7.67(aFeO)−2.99)×10−7

Development of a novel process for energy and materials recovery in steelmaking slags

This work aims at gathering fundamental knowledge for the development of a novel process for energy (H2 gas) and materials (magnetite Fe3O4) recovery in hotsteelmaking slags by reacting molten steelmaking slag with steam. Thermodynamic simulation was carried out to calculate the accumulated amount of produced H2 gas as a function of the volume of H2O-Ar gas introduced and the precipitated phases of the molten slags during controlled cooling. Laboratory experiments of crystallisation behaviours of molten slags during cooling were visualized in situ through a confocal laser scanning microscope (CSLM), and the cooled slags obtained were characterised by using SEM-EDS and XRD. CCT diagrams for different slags were created showing the slag crystallisation/phase transformation at different cooling rates. The recovery ratio of H2 gas and the maximum potential recovery ratio of iron oxide in the oxidised slags were calculated, which concludes that with increasing the slag basicity from 1.0 to 1.5 and 2.0, the recovery ratio of H2 was found to increase from 12.6% to 23.7% and 22.6%, and the maximum potential recovery ratio of iron oxide was found to increase from 18.3% to 34.4% and 32.8% under the investigated conditions

Food preference strategy of four sympatric rodents in a temperate forest in northeast China

Rodents are well known as both seed predators and dispersers of various plant species in forest ecosystems, and they play an important role in the regeneration of vegetation. Thus, the research on seed selection and vegetation regeneration by sympatric rodents is an interesting topic. To understand the characteristics of preferences of rodents for different seeds, a semi-natural enclosure experiment was performed with four rodent species (Apodemus peninsulae, Apodemus agrarius, Tscherskia triton, and Clethrionomys rufocanus) and the seeds of seven plant species (Pinus koraiensis, Corylus mandshurica, Quercus mongolica, Juglans mandshurica, Armeniaca sibirica, Prunus salicina, and Cerasus tomentosa) to investigate the differentiation in niches and patterns of resource utilization of sympatric rodents. The results showed that all the rodents had consumed many seeds of Pi. koraiensis, Co. mandshurica, and Q. mongolica but differed significantly in how they selected the different seeds. The rate of utilization (Ri) of Pi. koraiensis, Co. mandshurica, and Q. mongolica exhibited the highest values. The Ei values indicated that the rodents tested exhibited differences in their priorities used to select the seeds from different plant species. All four species of rodents exhibited obvious preferences for certain seeds. Korean field mice preferentially consumed the seeds of Q. mongolica, Co. mandshurica, and Pi. koraiensis. Striped field mice favor the seeds of Co. mandshurica, Q. mongolica, P. koraiensis, and Nanking cherry. Greater long-tailed hamsters prefer to consume the seeds of Pi. koraiensis, Co. mandshurica, Q. mongolica, Pr. salicina, and Ce. tomentosa. Clethrionomys rufocanus likes to eat the seeds of Pi. koraiensis, Q. mongolica, Co. mandshurica, and Ce. tomentosa. The results supported our hypothesis that sympatric rodents overlap in food selection. However, each rodent species has a marked preference for food selection, and different rodent species differ in their food preferences. This reflects the role of distinct food niche differentiation in their coexistence

Carbon Quantum Dots from Pomelo Peel as Fluorescence Probes for “Turn-Off–On” High-Sensitivity Detection of Fe3+ and L-Cysteine

This study designed a “turn-off–on” fluorescence analysis method based on carbon quantum dots (CQDs) to detect metal ions and amino acids in real sample systems. CQDs were derived from green pomelo peel via a one-step hydrothermal process. The co-doped CQDs with N and S atoms imparted excellent optical properties (quantum yield = 17.31%). The prepared CQDs could be used as fluorescent “turn-off” probes to detect Fe3+ with a limit of detection of 0.086 µM, a linear detection range of 0.1–160 µM, and recovery of 83.47–106.53% in water samples. The quenched CQD fluorescence could be turned on after adding L-cysteine (L-Cys), which allowed detection of L-Cys with a detection limit of 0.34 µM and linear range of 0.4–85 µM. Recovery of L-Cys in amino acid beverage was 87.08–122.74%. Visual paper-based testing strips and cellulose/CQDs composite hydrogels could be also used to detect Fe3+ and L-Cys

Luminescent Molecularly Imprinted Polymers Based on Covalent Organic Frameworks and Quantum Dots with Strong Optical Response to Quinoxaline-2-Carboxylicacid

Three-dimensional molecularly imprinted polymers (MIPs) based on quantum dots-grafted covalent organic frameworks (QDs-grafted COFs) are reported in this study. The compound 1,3,5-triformylphloroglucinol-P-phenylenediamine was used as COF material to react with the amino-modified CdSe/ZnS QDs by Schiff-base reactions. The amino-derived QDs reacted with quinoxaline-2-carboxylicacid (QCA) via a non-covalent interaction. The system combines the advantages of MIPs, COFs, and QDs for highly sensitive and selective QCA detection. The MIPs based on QDs-grafted COFs showed good chemical selectivity and thermal stability, as well as consistency in QCA optosensing. Under optimal conditions, the detection limit for QCA in meat and feed samples was 0.85 μmol L−1, over a linear concentration range of 1–50 μmol L−1. The current findings suggest a potential application of MIPs based on QDs-grafted COFs for the detection of trace levels of hazardous chemicals for food safety and environmental control

In-plane crashworthiness of chiral honeycombs

In-plane dynamic crushing and energy-absorption capabilities of chiral honeycombs are studied numerically invoking Finite Element (FE) code ABAQUS®/Explicit. Chiral honeycombs are characterized by a non-intuitive negative in-plane Poisson’s ratio ρ (auxeticity), for hexagonal chiral honeycombs, which exhibits a theoretic value of −1 (Prall and Lakes, 1997). The effects of topology parameters, stiffness ratio of ligament to node, impact velocity and impact mass on structural crashworthiness are studied based on a fixed-size model and a convergence study is also carried out to minimize the meshing induced result error. The numerical results show that increasing values of topology parameters give rise to better crashworthiness of chiral honeycombs which is dependent on boundary conditions. Specific energy absorption of chiral honeycomb is independent of relative stiffness after reaching a critical value. High velocity impact loading has dramatic effect on energy absorption of chiral honeycomb which is relatively independent of low velocity impact loading and impact mass

Sensitivity analysis of structural behaviors on key design parameters of tripod for offshore wind farm

The tripod foundation has been used as a popular support structure for offshore wind turbine (OWT). Typically, only deterministic computational model is considered by applying relevant standards and codes during the preliminary design of the foundations of OWT. However, uncertain parameters should also be considered in preliminary design due to complex configuration of tripod structure. In order to balance conflicting design parameters against design requirements, uncertainties from both design loads and geometric dimensions of structural components were considered to identify the dominant loads and key structural design parameters for tripod foundation. Nonlinear finite element methods were utilized to investigate the mechanical behaviors of tripod foundation and Monte Carlo simulations (MCS) were conducted to obtain sensitive design parameters of tripod foundation of OWTs. Based on the results, it is highlighted that which design parameters should be considered carefully and which design parameters can be selected relying on engineering judgment during the preliminary structural design stage of tripod foundation