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.     

水环境评价概述

水环境包括水力环境和水质环境两部分,且水力环境决定水质环境的变化方向。因而水环境评价应该同时进行水力环境和水质环境的评价。水质环境评价应该包括现状评价、动态评价和污染程度评价三项内容。现状评价是对比现状水质与标准之间的关系,而动态评价可反映水质变化的趋势。由此可实现评价现状、找出原因、制定防治规划措施的水环境评价的目的。     

胶州湾北岸不同水体水化学及氢氧同位素特征研究

研究不同水体的形成和运移过程,有助于合理开发利用水资源,对地表水与地下水污染协同防治和生态环境保护具有重要意义。以胶州湾北岸地区浅层地下水、河水及海水为研究对象,通过采集水化学和氢氧稳定同位素样品进行测试分析,综合运用统计学和Piper三线图,分析不同水体的水化学特征和影响因素,并结合氢氧稳定同位素特征研究其补给来源和转化关系。结果表明：研究区基岩裂隙水整体以淡水为主,部分点位受海水入侵影响,呈微咸水特征;第四系孔隙水整体为咸水且化学组分较稳定;河水水化学组分变化程度较大,呈微咸水-咸水特征。研究区地表水体间存在相互转化关系,祥茂河河水的主要来源为大气降水;洪江河、墨水河河水为大气降水与海水的混合水,且墨水河受海水混合影响程度大于洪江河;胶州湾海水为河水和标准海水的混合水。研究区地下水和地表水之间存在相互转化,基岩裂隙水来源除大气降水外,还与第四系孔隙水存在密切的水力联系,受海水入侵的影响;第四系孔隙水来源为大气降水与海水的混合水,径流过程中接受地表水体或基岩裂隙水的补给并经历不同程度的蒸发作用。     

镇江市饮用水中挥发性卤代烃污染状况研究

对镇江市区的饮用水中挥发性卤代烃的污染状况进行研究,对比分析自来水和地下水,以及自来水中的直供水、水箱水、水塔水中挥发性卤代烃的污染状况.     

拉萨城市饮用水安全：管网末梢水化学稳定性评价

饮用水安全问题关系人体健康和国计民生。自上世纪80年代以来,我国供水管网和二次供水导致的饮用水污染问题呈上升趋势。管网老化、水化学稳定性差引起管道腐蚀和结垢是影响供水末梢水质下降的主要原因之一。文章以拉萨城区用户末梢水为研究对象,展开管网对末梢水质的潜在影响调查,并采用饱和指数（IL）和稳定指数（IR）来评价管网水化学稳定性。结果显示,2008到2011年期间拉萨城区集中式供水管网水化学稳定性较差,管网被腐蚀和结垢倾向明显,并有逐年加剧趋势。     

空调循环水的化学处理

随着中央空调的发展,中央空调水处理已成为工业水处理中的重要领域。文章针对三大循环水系统(循环冷却水系统、循环冷冻水系统、循环热水系统)的特点,分别论述这三种水系统的水处理方法。     

中国水资源战略研究中几个问题的认识

要全面、辩证、历史地认识我国水资源情况,看到我国水资源情况的两面性,指了我国水土资源已得到相当开发,存在的根本问题是水利发展模式属于粗放型,部分地区水土资源过度开发,制约了可持续发展,我国水资源总体战略应当是：以水资源的可持续发展支持我国社会经济的可持续发展,为此,应从防洪减灾、农业用水、城市用水与工业用水及防污减灾、生态环境与防污减灾、生态环境与水资源、水供需平衡、南水北调、西北地区水资源等八个方面实行战略性的转变,最后指出：改革水资源管理体制、投资机制和水价政策,是解决我国水资源问题的根本出路。     

济宁市水环境功能区划分

从分析山东省济宁市的水环境现状入手，根据大量的监测资料，运用定性与定量相结合的方法，确定了济宁市地表各水域的主导功能及功能顺序，科学合理地划分了水功能区，并在此基础上阐述了对济宁市水功能区管理措施。     

多维尺度模型算法实现及其配水模型应用

介绍了多维尺度(MDS)配水模型算法的实现,并针对传统配水模型只能考虑一个变量的缺点,用多维尺度模型构造了实时动态配水模型。MDS配水模型适用于包含配水水量、用水区位置和用水区需水概率等多变量的实时动态配水,它对传统一维配水模型是一个重要的补充和发展。基于MDS的配水模型,可以实现大型流域实时动态配水,为流域的规划和管理提供参考。     

东莞市水环境对地下水资源持续利用的影响与对策

将地表水和地下水作为一个水环境的整体，分析地表水和地下水的关系；根据有机和无机污染的检测结果，按地表水环境质量标准和地下水质量标准对东莞市的水环境现状作出了评价。结果表明，东莞市大部分地表水污染严重，其结果使浅层地下水也受到了一定污染，深层地下水质尚好。为确保地下水资源的可持续利用，提出了地下水资源的保护和开发利用的策略。     

水驱油地层电阻率变化规律数值模拟及拐点影响因素分析

为确定水驱过程中地层电阻率与含水饱和度之间的关系,提出变倍数多倍注入水物质平衡理论模拟方法,模拟分析淡水水淹时各种地质因素对地层电阻率变化规律和拐点含水饱和度的影响,并与岩心水驱试验数据进行对比.结果表明:数值模拟方法精度较高;地层物性越好、注入水与原始地层水电阻率比值越大,拐点含水饱和度越小,水淹进程就越快越强;束缚...