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.     

微生物浸矿技术在我国的研究现状及发展前景

As the world’s second largest economy experiencing rapid economic growth, China has a huge demand for metals and energy. In recent years, China ranks first, among all the countries in the world, in the production and consumption of several metals such as copper, gold, and rare earth elements. Bioleaching, which is an approach for mining low grade and refractory ores, has been applied in industrial production, and bioleaching has made great contributions to the development of the Chinese mining industry. The exploration and application of bioleaching in China are reviewed in this study. Production and consumption trends of several metals in China over the past decade are reviewed. Technological processes at key bioleaching operations in China, such as at the Zijinshan Copper Mine and Mianhuakeng Uranium Mine, are presented. Also, the current challenges faced by bioleaching operations in China are introduced. Moreover, prospects such as efficiency improvement and environmental protection are proposed based on the current situation in the Chinese bioleaching industry.     

不同结构和形态的天然镁硅酸盐:与K反应制备生物柴油的K2MgSiO4催化剂

In this work, different magnesium silicate mineral samples based on antigorite, lizardite, chrysotile (which have the same general formula Mg₃Si₂O₅(OH)₄), and talc (Mg₃Si₄O₁₀(OH)₂) were reacted with KOH to prepare catalysts for biodiesel production. Simple impregnation with 20wt% K and treatment at 700–900°C led to a solid-state reaction to mainly form the K₂MgSiO₄ phase in all samples. These results indicate that the K ion can diffuse into the different Mg silicate structures and textures, likely through intercalation in the interlayer space of the different mineral samples followed by dehydroxylation and K₂MgSiO₄ formation. All the materials showed catalytic activity for the transesterification of soybean oil (1:6 of oil : methanol molar ratio, 5wt% of catalyst, 60°C). However, the best results were obtained for the antigorite and chrysotile precursors, which are discussed in terms of mineral structure and the more efficient formation of the active phase K₂MgSiO₄.     

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.     

胰岛素预处理抗心律失常作用的实验研究

研究胰岛素对心肌缺血再灌注大鼠心律失常的影响，选择SD雄性大鼠，随机分成对照组(CTRL组)，预适应组(IPC组)，缺血／再灌注组(I／R组)卡托普利组(CPT)及胰岛素高剂量组(INSH)、胰岛素低剂量组(INSL)，采用改良推管法建立大鼠在体心肌缺血再灌注模型，以心律失常发生率为指标，观察胰岛素的心肌预适应保护性作用．结果表明，胰岛素可以显著降低缺血及再灌时室性早搏的发生；降低缺血时室颤、室速的发生率．胰岛素对缺血再灌注心肌具有预适应样抗心律失常作用。     

用于ECT图像重建的预处理Landweber迭代算法

针对Landweber迭代方法收敛速度慢的问题,采用预处理方法来加快其收敛速度,即减少为计算有效解所需的迭代步数,由求解方程ATAf=ATg变为求解DATAf=DATg,其中D是预处理矩阵.讨论了构建预处理矩阵的一般方法.采用两级预处理策略构建预处理矩阵,将大的奇异值聚合并与小的奇异值分隔开来,而不是将所有的奇异值聚合在一点上,避免信号与噪声混合.使用仿真数据对预处理Landweber方法的收敛速度以及重建图像质量进行了评价.实验表明,预处理投影Landweber迭代方法同未经预处理的Landweber相比只需很少的迭代步数就可以获得比较满意的重建结果,为电容层析成像技术在线进行定量的图像重建...     

一种用于计算矢量有限元方程组的不完全分解预处理方法

提出一种不完全分解预处理方法,并结合迭代法计算矢量有限元方程组。预处理方法采用基于拓展乔里斯基分解的多波前法对有限元方程组的系数矩阵进行分解和更新,并采用基本线性代数系统库函数计算稠密矩阵乘来保证算法内层循环的高效率。该预处理算法在对系数矩阵进行数值分解前引入缩放矩阵以改善矩阵条件数。针对有限元方程组系数矩阵稀疏或部分稀疏的特性,提出一种新的舍弃策略以保证不完全分解的精度和提高预条件子的构造时间。通过与直接法对比,从时间花费与内存占用两方面,分析了该算法的计算性能。理论和数值实验表明,提出的预处理方法能大大减少计算时间与分解过程所占用的内存,同时保证了计算的准确性和有效性。     

用Chebvshev多项式加速的预处理子空间迭代法

研究了计算大型稀疏对称矩阵的若干个最大或最小特征值的问题的子空间迭代法.首先引入了加速子空间迭代法的Chebyshev迭代法和预处理技术.为了更好地加速子空间迭代法的收敛速度,作者把Chebyshev多项式和预处理技术同时应用到子空间迭代法中,对预处理过的残余矩阵用Chebyshev多项式加速.即讨论了Chebyshev迭代法对预处理子空间迭代法的应用.这样既缩小了矩阵特征值的分布范围,又改善了每次循环的初始矩阵.从而给出了用Chebyshev多项式加速的预处理子空间迭代法.最后给出了数值例子,结果表明加速后的预处理子空间迭代法比原来的预处理子空间迭代法更优越,进一步加速了迭代法的收敛速度,减少了计算量和计算时间.     

二维翼型绕流计算中预处理和多重网格方法的应用

结合Turkel矩阵预处理方法和多重网格方法,发展一种适合低速粘性流动计算的高效数值方法,通过对Navier-Stokes方程的时间导数项实施Turkel矩阵预处理,使得可压缩Navier-Stokes方程在低速情况下的系统刚性得到改善,为进一步加速收敛,提高计算效率,采用多重网格的3层V循环方式,对RAE2822超临...     

JAK-STAT/survivin通路对过氧化氢预处理诱导的适应性细胞保护作用的影响

为了探讨H_2O_2预处理对存活素(survivin)表达的影响及JAK-STAT/survivin通路在H_2O_2预处理的适应性细胞保护中的作用,用PC12细胞建立H_2O_2预处理对抗H_2O_2诱导细胞凋亡的实验模型,应用甲氮甲哇蓝(MTT)法检测细胞存活率,碘化丙啶(PI)染色流式细胞术检测细胞凋亡率,Hoechst染色检测细胞凋亡的形态学改变,免疫印迹法(Western blot)测定survivin表达水平.结果显示:用100μmol/L H_2O_2预处理PC12细胞90min可明显地抑制300μmol/L H_2O_2作用12 h后引起的细胞毒性和细胞凋亡,并可以显著地促进PC12细胞survivin的表达;JAK_2抑制剂AG-490不仅可以抑制survivin的表达.而且能拮抗H_2O_2预处理的适应性细胞保护作用.研究表明,survivin是JAK-STAT通路的靶基因,JAK-STAT/survivin通路在H_2O_2预处理诱导的适应性细胞保护机制中起着重要的作用.     

预处理子空间迭代法

研究了计算大型稀疏对称矩阵的若干个最大或最小特征值的问题．首先引入求解大型对称特征值问题的预处理技术，给出了改善后的算法及相应的算法收敛分析．而求解特征值问题的子空间迭代法，当矩阵的特征值的分布范围较大时，其收敛速度会受到限制．为了加速子空间迭代法的收敛速度，对每次迭代所得的残余矩阵直接进行预处理以改善矩阵特征值的分布而加速收敛．讨论了预处理技术对子空间迭代法的应用，从而给出了预处理子空间迭代法．最后给出了数值例子，结果表明预处理子空间迭代法比子空间迭代法优越，不仅收敛速度快，并且减少了计算量和计算时间．     

预处理子空间迭代法的收敛性分析

基于子空间迭代法的局限性，结合预处理技术的收敛特性，研究了预处理技术对子空间迭代法的应用以加速子空间迭代法的收敛，即预处理子空间迭代法，给出了相应的收敛分析．理论的分析和数值例子的结果表明预处理技术对子空间迭代法的加速是有效的．     

rhEPO对预处理低氧损伤胶质细胞MMP-9表达的影响

 探讨人促红细胞生成素（rhEPO）对低氧损伤胶质细胞的影响及对金属蛋白酶-9（MMP-9）表达的影响。通过体外纯化培养第3代星形胶质细胞,将其分为正常组、低氧组、rhEPO预处理组;以四唑蓝（MTT）比色法测定低氧培养12、24、36h细胞的存活率,倒置显微镜和透射电镜观察低氧对胶质细胞形态的影响;免疫荧光和逆转录-聚合酶链反应（RT-PCR）方法研究低氧对星形胶质细胞MMP-9表达的影响。结果显示:低氧组星形胶质细胞在低氧培养下出现细胞肿胀,且随时间的延长而加重,rhEPO预处理组在各时间点细胞肿胀明显轻于低氧组。rhEPO能减轻细胞超微结构的改变及降低MTT比值。RT-PCR及免疫荧光检测表明：低氧组MMP-9 mRNA及蛋白的表达在低氧各时间点均高于正常组,在24h达到最高,在36h开始降低（P<0.05）;rhEPO预处理组MMP-9mRNA及蛋白的表达变化在12、24、36h较低氧组低（P<0.05）。由此得出结论：rhEPO通过抑制MMP-9的表达促进低氧条件下星形胶质细胞的存活。     

一种运用多层不完全LU分解预处理的 时域有限元方法

为了提高时域有限元方法的计算效率,将一种基于逆的多层不完全LU分解(MIB-ILU)预处理方法运用于隐式时域有限元矩阵求解中,给出了三维散射问题的模型以及时域有限元公式系统,对系数矩阵进行了分析,并给出了预处理求解方法.理论和数值表明,此预处理方法有效地减少了每个时间步求解矩阵的时间,采用几个散射问题的算例证明了此种预处理技术的效果.