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.     

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.     

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.     

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.     

含钛高炉炉渣微波合成碳化钛及其介电性能测定

The preparation of functional material titanium carbide by the carbothermal reduction of Ti-bearing blast furnace slag with microwave heating is an effective method for valuable metals recovery; it can alleviate the environmental pressure caused by slag stocking. The dynamic dielectric parameters of Ti-bearing blast furnace slag/pulverized coal mixture under high-temperature heating are measured by the cylindrical resonant cavity perturbation method. Combining the transient dipole and large π bond delocalization polarization phenomena, the interaction mechanism of the microwave macroscopic non-thermal effect on the titanium carbide synthesis reaction was revealed. The material thickness range during microwave heating was optimized by the joint analysis of penetration depth and reflection loss, which is of great significance to the design of the microwave reactor for the carbothermal reduction of Ti-bearing blast furnace slag.     

陕西省普通高校田径教学现状调查与分析

采用问卷调查、专家访谈、文献资料等方法，对陕西省普通高校田径教学的现状进行调查分析。研究发现：当前陕西省普通高校田径教学正面临巨大困境。同样情况在其他省市也不同程度地存在，造成这种困境的主要原因是人们对田径运动的价值认识不足；田径教学的内容与方法缺乏趣味性，使学生产生厌学情绪。研究结合健康体育教育、终身体育教育对田径教学在普通高校体育课中的地位与作用进行论述，并对改革普通高校田径教学的现状提出积极建议。     

山东高校科技状况及与部分省市对比分析

高校科技统计工作是了解高校科研发展现状和制定高校发展规划的重要参考依据.在高等学校科技统计年报的基础上,对山东高校科技状况进行了分析,并与部分省市高校科技状况进行了对比.     

重庆市体育俱乐部规范发展的政策选择

对重庆市体育俱乐部以及有组织的群众体育活动的发展现状,运行机制和存在问题等进行了初步调研.提出了促进体育俱乐部规范发展的若干政策建议.     

新时期高校学风建设的问题及策略探讨

学风是一所学校的灵魂,学风建设是高等院校建设的一项重要内容,文章针对新时期、新环境、新条件下学风建设中出现的新问题进行了分析,提出了加强学风建设的一些对策。     

计算机科学与技术专业课程体系的优化与整合

通过论述计算机科学与技术学科的内涵、培养目标和评价标准,提出了一个反映内涵发展模式要求的教学计划与课程体系原则.     

论高校思想政治课教学科学性与政治性的统一

在目前的高校思想政治理论课教学中,存在着重科学性轻政治性或重政治性轻科学性的现象,影响了教学效果。要实现思想政治理论课的教育目标,必须正确把握科学性与政治性这两者的辩证关系,实现二者在教学中的统一。它要求思想政治理论课教学必须重视学生的主体性地位,改革教学模式;要树立学术意识,加强课程建设;要不断提高教师素质,增强教学感染力。     

清华大学物理系在原子分子结构、光谱及动力学研究方面的新进展

该文简短的描述了清华大学物理系的部分老师最近几年在原子分子结构、光谱及动力学领域的研究进展.     

古田会议精神与高校思想政治教育内容创新

挖掘传统教育内容中的可贵因素,赋予传统教育内容时代性、时效性,这是创新高校思想政治教育的重要方面.古田会议精神是高校思想政治教育的宝贵财富,对高校思想政治教育传统内容的创新,具有十分重要的启示意义.     

重组腺相关病毒的小量制备与体内体外感染研究

 重组腺相关病毒(rAAV)是近年来发展的较为成熟的一种病毒基因载体, 常用于过表达或者敲低等动物模型的建立与基因治疗等。本研究使用三质粒共转染的方法, 在HEK293细胞中包装出含绿色荧光蛋白(EGFP)基因的rAAV, 通过一系列实验, 确定纯化方法为脱氧胆酸钠裂解, 高浓度NaCl去除杂蛋白, 最后通过肝素层析柱纯化, 经超滤管浓缩后其滴度可达10¹³ gene copys/mL以上。将纯化后的rAAV 感染HEK293 细胞, 通过实验确定使用感染复数为10⁶、感染3 d 的细胞能够表达出高水平的EGFP。将rAAV注射入大鼠中脑黑质致密部, 经过3周的感染发现, rAAV可以特异性地感染多巴胺能神经元, 表达出EGFP。通过以上实验, 建立了一个在实验室小量制备rAAV的方法, 且此方法制备的rAAV完全满足体内与体外实验的要求。     

厦门龙舟三池水体氮磷的污染状况及来源分析

对厦门龙舟三池水体、底泥和周围排污口进行了监测,监测指标主要为pH、溶解氧、氨态氮、亚硝态氮、硝态氮、总氮、总磷和叶绿素8个理化指标,并对龙舟三池氮磷污染状况和来源进行了分析.结果表明:龙舟三池水体呈弱碱性;水体和底泥中氮磷营养元素浓度较高,其主要污染物来源为外海来水;外海来水和内池水体处于富营养状态,龙舟池和中池具有...