具有良好可再生性的新型二氧化硅磁性氧化石墨烯纳米复合材料

Graphene oxide (GO) wrapped Fe₃O₄ nanoparticles (NPs) were prepared by coating the Fe₃O₄ NPs with a SiO₂ layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO₂ coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. The effect of the amount of SiO₂ on the morphology, structure, adsorption, and regenerability of the composites was studied in detail. An appropriate SiO₂ layer can effectively induce the GO nanosheets to completely wrap the Fe₃O₄ NPs, forming a core-shell Fe₃O₄@SiO₂@GO composite where Fe₃O₄@SiO₂ NPs are firmly encapsulated by GO nanosheets. The optimized Fe₃O₄@SiO₂@GO sample exhibits a high saturated adsorption capacity of 253 mg·g?1 Pb(II) cations from wastewater, and the adsorption process is well fitted by Langmuir adsorption model. Notably, the composite displays excellent regeneration, maintaining a ~90% adsorption capacity for five cycles, while other samples decrease their adsorption capacity rapidly. This work provides a theoretical guidance to improve the regeneration of the GO-based adsorbents.     

微波预处理对复杂铜矿磨矿及浮选动力学的影响

The effect of CaCO₃, Na₂CO₃, and CaF₂ on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe₃PO₇ and apatite was investigated. The results revealed that Na₂CO₃ had the most significant effect on iron recovery and dephosphorization, followed by CaCO₃, the effect of CaF₂ was negligible. The mechanisms of CaCO₃, Na₂CO₃, and CaF₂ were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe₃PO₇ was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO₃ reacted with Fe₃PO₇ to generate an enormous amount of Ca₃(PO₄)₂ and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na₂CO₃, the phosphorus in Fe₃PO₇ migrated to nepheline and Na₂CO₃ improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF₂ reacted with Fe₃PO₇ to form fine Ca₃(PO₄)₂ particles scattered around the iron particles, making the separation of iron and phosphorus difficult.     

不同硅饱和系数水榴石的碳酸化分解动力学

Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method, which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method. In this study, the effect of the silica saturation coefficient (x) on the carbonation of hydrogarnet was investigated from the kinetic perspective. The results indicated that the carbonation of hydrogarnets with different x values (x = 0.27, 0.36, 0.70, and 0.73) underwent two stages with significantly different rates, and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3. The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol, respectively. Moreover, the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.     

一种超重力燃烧合成制备高性能高熵合金的新方法

A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr_0.9FeNi_2.5V_0.2Al_0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.     

利用皮秒激光烧蚀制备非球形铝纳米颗粒

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl₃) with ~2 ps laser pulses at an input energy of ~350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ~340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ~280 nm. Additionally, coarse structures with a period of ~700 nm were observed.     

窄板坯结晶器内连铸工艺参数对钢液流场的影响

Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting (CC) molds with narrow widths for the production of automobile exposed panels. Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process. The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold. Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone. The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min?1 and casting speed of 1.7 m·min?1. Under the present experimental conditions, the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.     

电渣重熔脱硫技术研究进展

Electroslag remelting (ESR) gives a combination of liquid metal refining and solidification structure control. One of the typical aspects of liquid metal refining during ESR for the advanced steel and alloy production is desulfurization. It involves two patterns, i.e., slag–metal reaction and gas–slag reaction (gasifying desulfurization). In this paper, the advances in desulfurization practices of ESR are reviewed. The effects of processing parameters, including the initial sulfur level of consumable electrode, remelting atmosphere, deoxidation schemes of ESR, slag composition, melting rate, and electrical parameters on the desulfurization in ESR are assessed. The interrelation between desulfurization and sulfide inclusion evolution during ESR is discussed, and advancements in the production of sulfur-bearing steel at a high-sulfur level during ESR are described. The remaining challenges for future work are also proposed.     

Mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al2O3?Na2O system during high-temperature sintering

The mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al₂O₃?Na₂O system during the high-temperature sintering process were systematically investigated using DSC?TG, XRD, SEM?EDS, FTIR, and Raman spectra, and the crystal structure of Na₄Ca₃(AlO₂)₁₀ was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na₄Ca₃(AlO₂)₁₀, CaO·Al₂O₃, and 12CaO·7Al₂O₃, and the content of Na₄Ca₃(AlO₂)₁₀ could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na₄Ca₃(AlO₂)₁₀ occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na₄Ca₃(AlO₂)₁₀ was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na₄Ca₃(AlO₂)₁₀ was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.     

含细夹层的分矿充填层中流动特性的可视化

Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography (CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers (24.21%) was significantly lower than that of the heap packed by coarse ores (37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity (1.8 × 10?5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10?5 m/s appeared in flow paths with a large diameter.     

基于Gini修正G1组合赋权的低碳经济评价模型与实证

主要目的是通过构建低碳经济评价模型实现对低碳经济发展水平的评价,并找出低碳经济发展的影响因素,低碳经济评价结果可以对低碳经济发展的政策制定提供理论依据和参考.首先,根据低碳经济的涵义构建低碳经济评价指标体系;然后,利用G1赋权法和Gini赋权法构造了基于客观修正主观的组合赋权方法,确定评价指标的组合权重;最后,对秦皇岛市2005~2015年的低碳经济发展水平进行了实证研究,判断秦皇岛市的低碳经济发展水平,找出影响秦皇岛市低碳经济发展的因素,为秦皇岛市低碳经济发展政策制定提供理论依据和参考.     

民族地区低碳金融支持低碳经济发展措施分析

在世界经济向低碳经济转型以及后危机背景下,提出民族地区发展低碳经济产业的理论依据,论证了民族地区低碳金融支持低碳经济发展的必要性,及民族地区低碳金融支持低碳经济发展的主要内容。通过分析民族地区金融机构支持低碳经济发展的主要措施,引导理论界和实务部门重视民族地区低碳金融对低碳经济产业的转型支持,并提出金融机构在民族地区发展低碳金融业务的对策建议。     

农村发展主体的低碳经济意识教育研究

就农村经济发展而言,农民是根本主体。发挥农民发展低碳经济的主体力量,必须提升其低碳经济意识。低碳经济教育是提升农民低碳经济意识的基本方式。对农民进行低碳经济教育的内容多样,核心是对农民进行生态道德教育;由于乡村精英是低碳经济教育的重点,要增强其发展低碳经济的使命感,使其真正成为发展低碳经济的领头羊;妇女的性别特征使其能在农村低碳经济发展中发挥特殊的作用,同时也意味对其低碳经济教育应因＂性＂而别;应该将幼儿、中小学学生培育为农村低碳经济发展的后备军,农村幼儿低碳经济教育应坚持生本教育理念,农村中小学的低碳经济教育应以课堂教育为主展开。     

发挥低碳金融作用促进广西低碳经济发展

诠释了如何发挥金融市场的导向和调节作用支持广西低碳经济产业发展;如何培育和完善碳金融交易体系,加快开发碳金融衍生工具,促进广西低碳经济发展.广西的金融业应树立低碳金融理念,将金融服务拓展到低碳经济各个层面,让金融业成为低碳理念推广的"践行者",最终推动广西经济发展方式的转型和产业结构的调整和优化,促进广西经济又好又快发...     

国外发展低碳经济的启示

阐述了低碳经济的发展历程,通过美国、欧洲联盟等国应对气候变化、发展低碳经济的案例,介绍了国外低碳经济的发展手段,提出了我国发展低碳经济的建议。     

基于DEA法的内蒙古发展低碳经济的效率评价

低碳经济被认为是有效减少二氧化碳排放的可行的经济运行模式,但是由于区域的差异,低碳经济的发展程度不同,因此对于低碳经济的有效评价成为必须。目前我国对于区域低碳经济的评价研究较少,对中国内蒙古地区近10年数据的利用数据包络法(DEA法),根据投入及产出的结果分析内蒙古发展低碳经济的效率,并以此为依据提出内蒙古低碳经济的发展对策。     

低碳经济下的工程经济风险与防范管理研究

在世界进入新的世纪之后,人们普遍对低碳经济转型的过程开始关注起来,而在这个重要的时期,我国以低碳、环保、节能为主题在各个领域开展了低碳型经济的发展。在国内,项目的多种类的特性让低碳转型期内的经济风险加大,并且在考虑风险的范围内存在一定的差异。由于低碳经济的存在,本文研究了在低碳型经济下工程经济的风险及防范措施,研究低碳时代的发展和变革,给未来的发展奠定良好的基础。     

基于三螺旋理论的我国低碳经济发展构想

介绍了三螺旋理论,应用三螺旋理论对中国低碳经济的发展进行了战略性的分析,从充分发挥政府在低碳经济中的主导作用、强化企业社会责任、发挥大学在低碳经济中的作用等方面提出了我国低碳经济的发展构想。     

东莞发展低碳经济的现状、挑战与路径选择——从发达国家的低碳路径探索看

世界经济历经工业化、信息化之后,正在走向低碳化,低碳经济时代已经来临,这种大背景,对有“世界工厂”之称的东莞,既是挑战,也是机遇。通过对西方发达国家走过的低碳经济发展路径的简要综述,分析了东莞传统经济的高碳特性,东莞发展低碳经济的现状及问题与挑战,并针对东莞未来推动低碳经济发展的进程提出了相关建议。     

“节能减排”背景下中小型城市低碳经济发展模式调查研究——以山东德州为例

为了解德州市低碳经济发展现状,分析其成功经验,探究我国中小型城市低碳经济发展的普适模式,从德州市城乡居民的低碳意识、低碳科技推广应用和新能源工程、宏观政策等方面对德州低碳经济成功范例展开调查分析.在此基础上建立了德州市发展低碳经济的"四驱循环动力模型",最后对德州模式进行了总结说明,并对中小型城市如何实现低碳发展提出了针对性建议.