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.     

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.     

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.     

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.     

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.     

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.     

浅谈果蔬贮藏保鲜新技术

概括分析了减压贮藏保鲜、电离辐射贮藏保鲜、保鲜剂处理、细胞间水结构化气调保鲜、临界低温高湿保鲜、高压静电场保鲜、生物技术保鲜等国内外果蔬贮藏保鲜新技术。     

高职教育督导的八大误区与突破创新

高职教育督导应走出误区,保持正确的方向,始终坚持教学督导与教育督导相结合、常规督导与专项督导相结合、事后督导与事前督导相结合、"督"与"导"相结合、校内督导与社会评价相结合、课堂督导与实践教学督导相结合、督教与督学和督管相结合、教学活动督导与设备利用督导相结合,以全面提高教育教学质量与人才培养质量。     

在直径为d的树中具有极小GA2的树

Tabar等人定义了图的第二类几何-算术指标GA2,同时给出了任意连通图G的可达上下界,并分别刻画了：在有n个顶点的树中Pn具有极大GA2,K1,n-1具有极小GA2.刘颖在有n个顶点的树中确定了具有GA2前五小的图及在具有完美匹配的所有树中具有GA2前四小的图.在此基础上,本文给出直径固定且有n个顶点的树中具有极小GA2的图.     

不同电化学条件下氧化后碳纤维表面基团的XPS分析

在不同的电流密度,电解质浓度和处理时间上对粘胶基碳纤维进行电化学氧化,然后用Ｘ－射线光电子能谱分析了氧化后碳纤维的表面基团,讨论了表面基团随着这些电化学条件的变化规律。     

重型颅脑交通伤的临床特点及救治要点

目的 :分析重型颅脑交通伤的临床特点及救治要点。方法 :回顾性分析我科2000年1月—2003年12月的64例重型颅脑交通伤病例的临床特点、CT资料及救治后的结果。分析原发昏迷时间、入院时GCS评分、救治措施与预后的关系。结果 :64例伤员中 ,单纯颅脑损伤24例 ,多发伤40例。原发性昏迷51例 ,继发性昏迷8例。GCS评分3～5分20例 ,5～8分44例。开颅手术23例 ,其它手术15例 ,气管切开35例。死亡22例 ,植物生存4例 ,重残2例 ,中残6例 ,恢复良好30例。结论 :重型颅脑交通伤伤情重、复合伤多、伤情复杂。及时有效的院前急救及入院后处理对患者的预后有重要意义     

鲨软骨粘多糖的酶法提取及组分分析

通过正交实验法分别研究单酶法提取次数和双酶法不同提取方式对鲨软骨粘多糖提取率的影响,从而获得胰蛋白酶和／或木瓜蛋白酶水解鲨软骨提取粘多糖的最佳工艺：并采用乙酸纤维素薄膜电泳和琼脂糖凝胶电泳分析不同提取方法获得的粘多糖的组分．实验结果表明：双酶水解方式比单酶水解方式的软骨降解率和多糖提取率要高;在双酶水解方式中,木-胰方式比胰-木方式能更有效地降解软骨,并且能获得更高的粘多糖提取率;而木瓜蛋白酶法提取的粘多糖纯度比胰蛋白酶法高．     

土工袋挡土墙小型振动台试验

通过小型振动台试验,研究了以天然河沙为填料的土工袋挡土墙在水平向不同振动加速度下的位移、动土压力以及水平加速度的分布规律,并与水平加筋土挡土墙和传统的刚性挡土墙进行了对比分析。结果表明,输入加速度不超过0.3g时,土工袋挡土墙位移变形比刚性挡土墙略大,但是随着输入加速度继续增大,刚性挡土墙发生整体滑移,以致倾覆破坏,而土工袋挡土墙依然稳定,显示出良好的抗震性能。水平加筋土挡土墙的位移一直大于土工袋挡土墙与刚性挡土墙,峰值出现在1/2倍墙高处,且随着输入加速度的增大,挡土墙中上部外凸变形越来越显著;土工袋挡土墙的动土压力系数与墙体位移相对应,沿墙高呈非线性分布,中上部较大、下部较小;土工袋挡土墙的加速度放大倍数随着输入加速度和墙高的增大而增大,均小于水平加筋土挡土墙与刚性挡土墙。同时,针对土工袋挡土墙的破坏失稳模式,对顶部进行加筋处理,可以进一步提高土工袋挡土墙的抗震性能。     

五种预氧化工艺处理污染原水的消毒性能比较

观察了水中腐殖酸和乳糖蛋白胨培养液的含量变化对高锰酸钾、氯、氯胺单独处理工艺及高锰酸钾与氯或氯胺联用工艺消毒效果的影响．结果表明，有机物浓度越高，高锰酸钾与氯或氯胺联用工艺与单独氯或氯胺工艺消毒效能相比所占优势越明显，尤其是当水中含有大量有机氮化合物时，采取高锰酸钾与氯或氯胺联用能更有效提高预处理时消毒效能．对有机污染严重的水源水进行预处理时，高锰酸钾与氯或氯胺联用预氧化能够减少有机物对消毒效果的影响，发挥预处理工艺对致病微生物的多级屏障作用，保障供水安全。     

毛泽东与中国特色社会主义

中国特色社会主义“始于毛,成于邓”。毛泽东对中国特色社会主义建设道路的探索可分为三个阶段,即基本正确的探索期、正误交织的曲折期和严重错误的失败期,思想框架几乎涉及了社会主义建设的全部内容。其探索有成绩也有失误,但作为起点和正反经验都对中国特色社会主义的建设有重大启示意义。     

随物赋形气韵自然--论自然之美与艺术形象的塑造

随物赋形,气韵自然,是自然之美在塑造艺术形象方面的重要特征。自然之美的文学艺术品,在艺术形象上表现为随物赋形并突出地体现为强调“神似”、“传神”。艺术形象的自然之美,追求的是传神之美,追求的是传神自然,亦即气韵自然。