烧结铁矿中FeO含量对其在富氢高炉中还原行为的影响

Japan started the national project “COURSE 50” for CO₂ reduction in the 2000s. This project aimed to establish novel technologies to reduce CO₂ emissions with partially utilization of hydrogen in blast furnace-based ironmaking by 30% by around 2030 and use it for practical applications by 2050. The idea is that instead of coke, hydrogen is used as the reducing agent, leading to lower fossil fuel consumption in the process. It has been reported that the reduction behavior of hematite, magnetite, calcium ferrite, and slag in the sinter is different, and it is also considerably influenced by the sinter morphology. This study aimed to investigate the reduction behavior of sinters in hydrogen enriched blast furnace with different mineral morphologies in CO–CO₂–H₂ mixed gas. As an experimental sample, two sinter samples with significantly different hematite and magnetite ratios were prepared to compare their reduction behaviors. The reduction of wustite to iron was carried out at 1000, 900, and 800°C in a CO–CO₂–H₂ atmosphere for the mineral morphology-controlled sinter, and the following findings were obtained. The reduction rate of smaller amount of FeO led to faster increase of the reduction rate curve at the initial stage of reduction. Macro-observations of reduced samples showed that the reaction proceeded from the outer periphery of the sample toward the inside, and a reaction interface was observed where reduced iron and wustite coexisted. Micro-observations revealed three layers, namely, wustite single phase in the center zone of the sample, iron single phase in the outer periphery zone of the sample, and iron oxide-derived wustite FeO and iron, or calcium ferrite-derived wustite 'FeO' and iron in the reaction interface zone. A two-interface unreacted core model was successfully applied for the kinetic analysis of the reduction reaction, and obtained temperature dependent expressions of the chemical reaction coefficients from each mineral phases.     

Mg和La对Ca–Ti 处理钢中夹杂物演变和组织的影响

The evolution of inclusions and the formation of acicular ferrite (AF) in Ca–Ti treated steel was systematically investigated after Mg and La addition. The inclusions in the molten steel were Ca–Al–O, Ca–Al–Mg–O, and La–Mg–Ca–Al–O after Ca, Mg, and La addition, respectively. The type of oxide inclusion in the final quenched samples was the same as that in the molten steel. However, unlike those in molten steel, the inclusions were Ca–Al–Ti–O + MnS, Ca–Mg–Al–Ti–O + MnS, and La–Ca–Mg–Al–Ti–O + MnS in Mg-free, Mg-containing, and La-containing samples, respectively. The inclusions distributed dispersedly in the La-containing sample. In addition, the average size of the inclusions in the La-containing sample was the smallest, while the number density of inclusions was the highest. The size of effective inclusions (nucleus of AF formation) was mainly in the range of 1–3 μm. In addition, the content of ferrite side plates (FSP) decreased, while the percentage of AF increased by 16.2% due to the increase in the number of effective inclusions in the La-containing sample in this study.     

氧化锌矿物浸出渣中铅、锶的提取及动力学分析

NH₄HCO₃ conversion followed by HCl leaching was performed and proven to be effective in extracting Pb and Sr from zinc extracted residual. The mechanism and operating conditions of NH₄HCO₃ conversion, including molar ratio of NH₄HCO₃ to zinc extracted residual, NH₄HCO₃ concentration, conversion temperature, conversion time, and stirring velocity, were discussed, and operating conditions were optimized by the orthogonal test. Experimental results indicate that NH₄HCO₃ conversion at temperatures ranging from 25 to 85°C follows the shrinking unreacted core model and is controlled by inner diffusion through the product layer. The extraction ratios of Pb and Sr under optimized conditions reached 85.15% and 87.08%, respectively. Moreover, the apparent activation energies of Pb and Sr were 13.85 and 13.67 kJ·mol?1, respectively.     

摩擦焊接碳钢（EN24）和镍基高温合金（IN718）的显微组织和力学性能

Continuous-drive rotary friction welding was performed to join cylindrical specimens of carbon steel (EN24) and nickel-based superalloy (IN718), and the microstructures of three distinct weld zones—the weld interface (WI)/thermo-mechanically affected zone (TMAZ), the heat-affected zone (HAZ), and the base metal—were examined. The joint was observed to be free of defects but featured uneven flash formation. Electron backscatter diffraction (EBSD) analysis showed substantial changes in high-angle grain boundaries, low-angle grain boundaries, and twin boundaries in the TMAZ and HAZ. Moreover, significant refinement in grain size (2–5 μm) was observed at the WI/TMAZ with reference to the base metal. The possible causes of these are discussed. The microhardness profile across the welded joint shows variation in hardness. The changes in hardness are ascribed to grain refinement, phase transformation, and the dissolution of strengthening precipitates. The tensile test results reveal that a joint efficiency of 100% can be achieved using this method.     

汽车暴露面板带有表面条状缺陷的夹杂物分布特征分析:一种定量电解方法

The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface. A quantitative electrolysis method was used to compare and evaluate the three-dimensional morphology, size, composition, quantity, and distribution of inclusions in the defect and non-defect zone of automobile exposed panel. The Al₂O₃ inclusions were observed to be aggregated or chain-like shape along with the sliver defect of about 3–10 μm. The aggregation sections of the Al₂O₃ inclusions are distributed discretely along the rolling direction, with a spacing of 3–7 mm, a length of 6–7 mm, and a width of about 3 mm. The inclusion area part is 0.04%–0.16% with an average value of 0.08%, the inclusion number density is 40 mm?2 and the inclusion average spacing is 25.13 μm. The inclusion spacing is approximately 40–160 μm, with an average value of 68.76 μm in chain-like inclusion parts. The average area fraction and number density of inclusions in the non-defect region were reduced to about 0.002% and 1–2 mm?2, respectively, with the inclusion spacing of 400 μm and the size of Al₂O₃ being 1–3 μm.     

在酸性溶液中加压氧化三价砷离子和二价铁离子

The co-oxidation of As(III) and Fe(II) in acidic solutions by pressured oxygen was studied under an oxygen pressure between 0.5 and 2.0 MPa at a temperature of 150°C. It was confirmed that without Fe(II) ions, As(III) ions in the solutions are virtually non-oxidizable by pressured oxygen even at a temperature as high as 200°C and an oxygen pressure up to 2.0 MPa. Fe(II) ions in the solutions did have a catalysis effect on the oxidation of As(III), possibly attributable to the production of such strong oxidants as hydroxyl free radicals (OH·) and Fe(IV) in the oxidation process of Fe(II). The effects of such factors as the initial molar ratio of Fe(II)/As(III), initial pH value of the solution, oxygen pressure, and the addition of radical scavengers on the oxidation efficiencies of As(III) and Fe(II) were studied. It was found that the oxidation of As(III) was limited in the co-oxidation process due to the accumulation of the As(III) oxidation product, As(V), in the solutions.     

采用超声组装与滚压工艺制备铝–碳纳米管复合材料

This study introduced a novel fabrication of aluminum–carbon nanotube (CNT) composites by employing bulk acoustic waves and accumulative roll bonding (ARB). In this method, CNT particles were aligned using ultrasonic standing wave in an aqueous media, and the arrayed particles were precipitated on the aluminum plate substrate. Then, the plates rolled on each other through the ARB process with four passes. Optical and scanning electron micrographs demonstrated the effective aligning of CNTs on the aluminum substrate with a negligible deviation of arrayed CNTs through the ARB process. The X-ray diffraction pattern of the developed composites showed no peaks for carbon and aluminum carbide. In addition, tensile tests showed that the longitudinal strength of the specimens processed with aligned CNTs was significantly greater than that of the specimens with common randomly dispersed particles. The proposed technique is beneficial for the fabrication of Al–CNT composites with directional mechanical strength.     

活化天然矿石选择性还原二氧化碳为无定形碳

Natural magnetite formed by the isomorphism substitutions of transition metals, including Fe, Ti, Co, etc., was activated by mechanical grinding followed by H₂ reduction. The temperature-programmed reduction of hydrogen (H₂-TPR) and temperature-programmed surface reaction of carbon dioxide (CO₂-TPSR) were carried out to investigate the processes of oxygen loss and CO₂ reduction. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS). The results showed that the stability of spinel phases and oxygen-deficient degree significantly increased after natural magnetite was mechanically milled and reduced in H₂ atmosphere. Meanwhile, the activity and selectivity of CO₂ reduction into carbon were enhanced. The deposited carbon on the activated natural magnetite was confirmed as amorphous. The amount of carbon after CO₂ reduction at 300°C for 90 min over the activated natural magnetite was 2.87wt% higher than that over the natural magnetite.     

高职英语教学中复式教学法应用的探索

针对高职生英语水平差距过大的现状，科学分析存在问题，反思传统教学弊端，更新教育观念，尝试运用复式教学法，优化知识结构，力求对高职高专英语教师在调整教学方法上得到一定的借鉴作用，以取得更好的教学效果。     

高职汽车专业模块化教学实践探索

汽车专业课的职业技能教学是各大工科高等职业院校困惑的问题，结合多年的教育教学经验，论述了模块化理论在汽车专业职业技能教学中的运用，举例介绍了我校汽车运用技术专业模块化教学方法的实践探索。     

高等职业教育中教学改革的思考

培养社会适应能力强、有一定专业理论水平和较强专业技能的高级技术人才是高等职业技术教育职责所在。在高等职业技术教育快速发展的新形势下,以市场为导向,注重一个＂需＂字;以技能为核心,注重一个＂强＂字;以质量为保证,确保一个＂高＂字;以改革为手段,保持一个＂活＂字;以特色为前提,力求一个＂新＂字,加强教学改革,提高教学质量,意义尤为重大。     

关于高职院校教学资源库建设的探讨

教学资源库在现代教育中发挥着越来越重要的作用,优质、高效的教学资源库对现代教学意义十分重大。高职院校在教学资源库建设中,图书馆有着不可替代的作用,是校园教学资源库的枢纽。其信息化、数字化程度已成为教学资源库建设强有力的支撑,为教学资源库的维护、管理奠定了技术、人员基础。     

传统教学方法与行动导向教学方法的对比研究

随着社会的不断发展与进步,企业对从业者的能力要求越来越高,与此同时,人生发展与社会发展的互动态势更加明显,迫使劳动者要求具备跨职业、跨行业、跨产业的不断适应劳动市场变化的本领。针对这样的现状,改革职业教育教学方法,使得学生获得社会认可的职业能力就显得尤为重要。结合在德国学习和国内教学实施心得,我们对比传统教学方法与行动导向教学方法,阐述了当前职业教育教学改革的方向,对广大教育工作者具有一定的参考价值。     

浅析民办高职院校教学中存在的问题及对策

民办高职院校作为一种特殊的高等教育办学类型,在我国高等教育大众化的进程中扮演着十分重要的角色。而当前民办高职院校的教学现状并不乐观,其中在学生基础、师资素养、实践环节、教材建设和学业考核机制等几个方面存在的问题正影响着其人才培养的质量。以生为本、加强师资、强化训练、特色教材、多元评价是其改善教学质量的重要途径。     

影响高职思政课教学实效的教学要素研究

高职思政课教学面临的问题诸多,其中教学实效不高是最大的问题。提高思政课教学实效是高职思政课教学所追求的目标,而高职思政课有无教学效果及实现程度的高低受到诸多因素的影响,其中教学要素的影响最为关键,因此,深入探讨各种教学要素对高职思政课教学实效的影响,进而提出提高高职思政课教学实效的相关对策,对提高高职思政课教学实效具有理论意义和实践价值。     

教育教学质量是高职发展的生命线

阐明了高职教育教学质量的内涵,分析了高职教育教学质量的重要性,并在此基础上提出了提高高职教育教学质量的措施。     

《环境化学》课程的教学改革与实践

本文分析了现阶段高职高专的环境化学课程教学过程中的一些问题,根据自身的教学实践,结合国内高职教育教学改革的经验,提出明确教学目的、改进教学方式的建议,并探讨了"教学做一体化"的教学模式.     

高职院校足球教学中学生职业能力的培养

随着职业教育事业的发展,由常规教育到职业教育、传授型教学向职业型教学转型,是新时期教学改革的要求。本文根据足球教学和职业教学的特点,就高职高专足球教学中学生职业能力的培养问题进行论述,以拓展继续创新的思路,培养学生的职业能力。