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.     

爆破振动信号时频特征的微差时间效应

基于平滑伪Wigner-Ville分布信号重排(RSPWVD),用matlab5.6编写的振动信号处理软件,并在海钢北一采场就微差间隔时间对爆破振动的影响进行试验的基础上,研究了振动信号时频特征的微差时间效应.基于平滑伪Wigner-Ville分布信号重排能全面反映爆破振动信号的时频特征,具有良好的聚集性.采用BC-6型微差起爆器起爆瞬发雷管消除了微差雷管时间漂移带来的误差.将测试获得的不同微差时间条件下的爆破振动波形进行重排,获得了相应条件下的爆破振动时频特征.研究表明,微差时间对爆破振动信号的时频特征影响很大,延迟时间的长短直接影响到整个爆破振动信号主频率及其持续时间.图2,表1,参11.     

事件的模糊离散时间区间的表示

由于现实世界中事件的持续时间难以精确测量,以及起始时刻及结束时刻的模糊性,使得Allen的区间代数不能很好地刻画事件的模糊时间区间,首先将时间区间离散化,然后用事件的持续分布的概念米表示事件的持续时间,并用时间区间来近似持续分布,使得可以应用Allen的区间代数来进行相应的时态推理,最终给出了求主时间区间的算法。     

一种计算设备空闲时间及工件等待时间的简便方法──表格计算法

本文以合理安排生产任务、提高设备利用率、缩短生产周期为目的，提出一种新的计算设备空闲时间及工件等待时间的简便方法，即表格计算法．该方法可以很容易地计算出各设备等待工件的空闲时间以及各工件等待设备的等待时间和工艺周期，为进一步编制更详细的生产调度计划提供可靠的依据．     

硬脆性页岩超声波透射实验研究

为了获取硬脆性页岩地层声波传播特征,以鄂尔多斯盆地井下石盒子组页岩为研究对象,采用超声波透射实验系统的分析了钻井液作用前后页岩声波时差、衰减系数、时域信号以及频域信号的特征。研究结果表明,钻井液作用后页岩声波时差增大,衰减系数增大,频域信号与时域信号均发生改变。钻井液作用后,页岩发生水化反应,声波时差与衰减系数可定量描述页岩水化动态变化,时域信号与频域信号能够定性分析页岩水化结构变化特征。超声波透射实验为硬脆性页岩水化特征的研究提供了一个新的思路。     

区间型金融时间序列的长记忆性研究

研究金融时序的长记忆性能够帮助人们更加准确地刻画金融市场的特征,而在现有研究中,有关区间型金融时序长记忆性的研究很少。因此,考虑了区间型金融时序蕴含的长记忆性特征及其基于现有实值金融时序长记忆性建模的区间值时序预测模型,首先,将区间数表示成区间中心和区间半径的形式;然后分别对中心和半径序列进行长记忆性检验,并对具有长记忆性的序列进行组合预测;最后,以上证综指和深证综指的区间股指为实证对象进行验证。实证结果表明:上证综指的区间股指具有明显的长记忆性,且组合预测能够显著提高区间型金融时序的预测精度。     

基于再生制动能利用的发车间隔优化模型

本文基于单车节能操纵,以降低全线总能耗为目标,建立了发车间隔节能优化模型。该模型在现有区间运行时分的基础上,考虑单列车节能及其在不同站间的运行速度曲线,得到列车区间牵引能耗,通过重叠时间确定有效利用的再生制动能,并且将多车总能耗最低转化为求解全线能耗最低问题。以全线能耗最低为目标,采用遗传算法,寻求最优发车间隔。仿真案例验证了优化发车间隔的节能效果。     

时滞系统终端时间参数优化控制

针对时滞系统终端时间优化控制问题,提出一种基于参数化的数值求解方法.首先将优化控制向量用分段常数函数来近似;然后引入时间转换方法将未知切换时间点和未知终端时间映射到新时间域的固定时间点上,从而将原未知时域的时间最优控制问题近似为固定时域的非线性规划问题;最后采用全联通粒子群算法求解.资源再生系统优化控制问题的仿真结果表明所提方法是有效的.     

指数分布无替换定时截尾寿命试验失效率的估计

介绍了指数分布无替换定时截尾寿命试验失效率的点估计和区间估计 ,特别在大样本情况下 ,失效率的近似置信区间。     

一类两机器 no-wait 流水作业总完工时间问题

在两机器 no-wait 流水作业问题中,每个工件在加工前有一调整时间,加工完之后有一移走时间,同一工件的调整和移走是可以重叠的,但加工时间不能重叠,同时任一工件在第二台机器上的加工必须紧接在它在第一台机器上的加工之后进行,本文以总完工时间为目标函数,讨论问题最优解中工件排列应满足的条件;其次讨论当工件的三种时间满足一定条件时最优时间表的求法;最后为问题设计了一个近似算法.     

一种高精度时间间隔测量方法的研究

为了提高测量精度,利用高精度时间间隔测量芯片TDC-GP2的测量范围2进行测量,通过延时的方法避免了测量范围量程不足的问题;同时结合模拟法的优点进行不足一个时钟周期的测量。为了在测量过程中解决时间间隔测量的非线性问题,利用模数转换的方法进行了精确测量。实验结果表明,该方法能够有效的提高测量精度。