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.     

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.     

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.     

基于响应曲面法的铁焦冶金性能多目标协同优化

Iron carbon agglomerates (ICA) are used to realize low-carbon blast furnace ironmaking. In this study, the central composite design based on response surface methodology was used to synergistically optimize the compressive strength, reactivity, and post-reaction strength of ICA. Results show that the iron ore addition ratio significantly influences the compressive strength, reactivity, and post-reaction strength of ICA. The iron ore addition ratio and carbonization temperature or the iron ore addition ratio and carbonization time exert significant interaction effects on the compressive strength and reactivity of ICA, but it has no interaction effects on the post-reaction strength of ICA. In addition, the optimal process parameters are as follows: iron ore addition ratio of 15.30wt%, carbonization temperature of 1000°C, and carbonization time of 4.27 h. The model prediction results of compressive strength, reactivity, and post-reaction strength are 4026 N, 55.03%, and 38.24%, respectively, which are close to the experimental results and further verify the accuracy and reliability of the models.     

皮秒Nd:YAG激光对生物金属纯Ti和Ti–13Nb–13Zr合金的表面改性

The effects of picosecond Nd:YAG laser irradiation on chemical and morphological surface characteristics of the commercially pure titanium and Ti–13Nb–13Zr alloy in air and argon atmospheres were studied under different laser output energy values. During the interaction of laser irradiation with the investigated materials, a part of the energy was absorbed on the target surface, influencing surface modifications. Laser beam interaction with the target surface resulted in various morphological alterations, resulting in crater formation and the presence of microcracks and hydrodynamic structures. Moreover, different chemical changes were induced on the target materials’ surfaces, resulting in the titanium oxide formation in the irradiation-affected area and consequently increasing the irradiation energy absorption. Given the high energy absorption at the site of interaction, the dimensions of the surface damaged area increased. Consequently, surface roughness increased. The appearance of surface oxides also led to the increased material hardness in the surface-modified area. Observed chemical and morphological changes were pronounced after laser irradiation of the Ti–13Nb–13Zr alloy surface.     

汽车用废弃锂离子电池的减量化、再生及回收研究进展

The demand for Li-ion batteries (LIBs) for vehicles is increasing. However, LIBs use valuable rare metals, such as Co and Li, as well as environmentally toxic reagents. LIBs are also necessary to utilize for a long period and to recycle useful materials. The reduction, reuse, and recycle (3R) of spent LIBs is an important consideration in constructing a circular economy. In this paper, a flowsheet of the 3R of LIBs is proposed and methods to reduce the utilization of valuable rare metals and the amount of spent LIBs by remanufacturing used parts and designing new batteries considering the concept of 3R are described. Next, several technological processes for the reuse and recycling of LIBs are introduced. These technologies include discharge, sorting, crushing, binder removal, physical separation, and pyrometallurgical and hydrometallurgical processing. Each process, as well as the related physical, chemical, and biological treatments, are discussed. Finally, the problem of developed technologies and future subjects for 3R of LIBs are described.     

传统加热和微波加热下氧化锰矿的碳热还原行为研究

For the purpose of exploring a potential process to produce FeMn, the effects of microwave heating on the carbothermal reduction characteristics of oxidized Mn ore was investigated. The microwave heating curve of the mixture of oxidized Mn ore and coke was analyzed in association with the characterization of dielectric properties. The comparative experiments were conducted on the carbothermal reductions through conventional and microwave heatings at temperatures ranging from 973 to 1373 K. The thermogravimetric analysis showed that carbothermal reactions under microwave heating proceeded to a greater extent and at a faster pace compared with those under conventional heating. The metal phases were observed in the microstructures only under microwave heating. The carbothermal reduction process under microwave heating was discussed. The electric and magnetic susceptibility differences were introduced into the thermodynamics analysis for the formation of metal Mn. The developed thermodynamics considered that microwave heating could make the reduction of MnO to Mn more accessible and increase the reduction extent.     

机械合金化法制备的Cu/SiC纳米复合材料的组织、热性能和力学性能评估

Nano-sized silicon carbide (SiC: 0wt%, 1wt%, 2wt%, 4wt%, and 8wt%) reinforced copper (Cu) matrix nanocomposites were manufactured, pressed, and sintered at 775 and 875°C in an argon atmosphere. X-ray diffraction (XRD) and scanning electron microscopy were performed to characterize the microstructural evolution. The density, thermal expansion, mechanical, and electrical properties were studied. XRD analyses showed that with increasing SiC content, the microstrain and dislocation density increased, while the crystal size decreased. The coefficient of thermal expansion (CTE) of the nanocomposites was less than that of the Cu matrix. The improvement in the CTE with increasing sintering temperature may be because of densification of the microstructure. Moreover, the mechanical properties of these nanocomposites showed noticeable enhancements with the addition of SiC and sintering temperatures, where the microhardness and apparent strengthening efficiency of nanocomposites containing 8wt% SiC and sintered at 875°C were 958.7 MPa and 1.07 vol%?1, respectively. The electrical conductivity of the sample slightly decreased with additional SiC and increased with sintering temperature. The prepared Cu/SiC nanocomposites possessed good electrical conductivity, high thermal stability, and excellent mechanical properties.     

空冷条件下钛渣颗粒的氧化路径及氧化动力学

The oxidation pathway and kinetics of titania slag powders in air were analyzed using differential scanning calorimetry (DSC) andthermogravimetry (TG). The oxidation pathway of titania slag powder in air was divided into three stages according to their three exothermic peaks and three corresponding mass gain stages indicated by the respective non-isothermal DSC and TG curves. The isothermal oxidation kin-etics of high titania slag powders of different sizes were analyzed using the ln-ln analysis method. The results revealed that the entire isotherm-al oxidation process comprises two stages. The kinetic mechanism of the first stage can be described as f (α)=1.77 (1?α) [?ln (1?α)](1.77?1)/1.77 , f (α)=1.97 (1?α) [?ln (1?α)](1.97?1)/1.97 , and f (α)=1.18 (1?α) [?ln (1?α)](1.18?1)/1.18 . The kinetic mechanism of the second stage for all samples can be described as f (α)=1.5(1?α)2/3[1?(1?α)1/3]?1 . The activation energies of titania slag powders with different sizes (d1 < 0.075 mm, 0.125 mm < d2 < 0.150 mm, and 0.425 mm < d3 < 0.600 mm) for different reaction degrees were calculated. For the given experimental conditions, the rate-controlling step in the first oxidation stage of all the samples is a chemical reaction. The rate-controlling steps of the second oxidation stage are a chemical reaction and internal diffusion (for powders d1 < 0.075 mm) and internal diffusion (for powders 0.125 mm < d2 <0.150 mm and 0.425 mm < d3 < 0.600 mm).     

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.