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.     

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.     

PLGA/硬石复合涂层镁基纳米复合材料在植入应用时的体外生物活性和腐蚀行为

A type of polymer/ceramic coating was introduced on a magnesium-based nanocomposite, and the nanocomposite was evaluated for implant applications. The microstructure, corrosion, and bioactivity of the coated and uncoated samples were assessed. Mechanical alloying followed by sintering was applied to fabricate the Mg–3Zn–0.5Ag–15NiTi nanocomposite substrate. Moreover, different contents of poly(lactic-co-glycolic acid) (PLGA) coatings were studied, and 10wt% of PLGA content was selected. The scanning electron microscopy (SEM) images of the bulk nanocomposite showed an acceptable homogenous dispersion of the NiTi nanoparticles (NPs) in the Mg-based matrix. In the in vitro bioactivity evaluation, following the immersion of the uncoated and coated samples in a simulated body fluid (SBF) solution, the Ca/P atomic ratio demonstrated that the apatite formation amount on the coated sample was greater than that on the uncoated nanocomposite. Furthermore, assessing the corrosion resistance indicated that the coatings on the Mg-based substrate led to a corrosion current density (i_corr) that was considerably lower than that of the substrate. Such a condition revealed that the coating would provide an obstacle for the corrosion. Based on this study, the PLGA/hardystonite (HT) composite-coated Mg–3Zn–0.5Ag–15NiTi nanocomposite may be suitably applied as an orthopedic implant biomaterial.     

矿山尾矿作为碱活化原料的研究进展

The mining industry produces billions of tons of mine tailings annually. However, because of their lack of economic value, most of the tailings are discarded near the mining sites, typically under water. The primary environmental concerns of mine tailings are related to their heavy metal and sulfidic mineral content. Oxidation of sulfidic minerals can produce acid mine drainage that leaches heavy metals into the surrounding water. The management of tailing dams requires expensive construction and careful control, and there is the need for stable, sustainable, and economically viable management technologies. Alkali activation as a solidification/stabilization technology offers an attractive way to deal with mine tailings. Alkali activated materials are hardened, concrete-like structures that can be formed from raw materials that are rich in aluminum and silicon, which fortunately, are the main elements in mining residues. Furthermore, alkali activation can immobilize harmful heavy metals within the structure. This review describes the research on alkali activated mine tailings. The reactivity and chemistry of different minerals are discussed. Since many mine tailings are poorly reactive under alkaline conditions, different pretreatment methods and their effects on the mineralogy are reviewed. Possible applications for these materials are also discussed.     

动态应变时效的应力状态依赖性:热硬化和蓝脆

This study aims to discover the stress-state dependence of the dynamic strain aging (DSA) effect on the deformation and fracture behavior of high-strength dual-phase (DP) steel at different deformation temperatures (25–400°C) and reveal the damage mechanisms under these various configurations. To achieve different stress states, predesigned specimens with different geometric features were used. Scanning electron microscopy was applied to analyze the fracture modes (e.g., dimple or shear mode) and underlying damage mechanism of the investigated material. DSA is present in this DP steel, showing the Portevin–Le Chatelier (PLC) effect with serrated flow behavior, thermal hardening, and blue brittleness phenomena. Results show that the stress state contributes distinctly to the DSA effect in terms of the magnitude of thermal hardening and the pattern of blue brittleness. Either low stress triaxiality or Lode angle parameter promotes DSA-induced blue brittleness. Accordingly, the damage mechanisms also show dependence on the stress states in conjunction with the DSA effect.     

关于钢水质量窄窗口稳定控制的思考

In order to promote the intelligent transformation and upgrading of the steel industry, intelligent technology features based on the current situation and challenges of the steel industry are discussed in this paper. Based on both domestic and global research, functional analysis, reasonable positioning, and process optimization of each aspect of steel making are expounded. The current state of molten steel quality and implementation under narrow window control is analyzed. A method for maintaining stability in the narrow window control technology of steel quality is proposed, controlled by factors including composition, temperature, time, cleanliness, and consumption (raw material). Important guidance is provided for the future development of a green and intelligent steel manufacturing process.     

不同应变速率下Mg?B4C纳米复合材料的力学性能表征

Magnesium has wide application in industry. The main purpose of this investigation was to improve the properties of magnesium by reinforcing it using B₄C nanoparticles. The reinforced nanocomposites were fabricated using a powder compaction technique for 0, 1.5vol%, 3vol%, 5vol%, and 10vol% of B₄C. Powder compaction was conducted using a split Hopkinson bar (SHB), drop hammer (DH), and Instron to reach different compaction loading rates. The compressive stress–strain curves of the samples were captured from quasi-static and dynamic tests carried out using an Instron and split Hopkinson pressure bar, respectively. Results revealed that, to achieve the highest improvement in ultimate strength, the contents of B₄C were 1.5vol%, 3vol%, and 3vol% for Instron, DH, and SHB, respectively. These results also indicated that the effect of compaction type on the quasi-static strength of the samples was not as significant, although its effect on the dynamic strength of the samples was remarkable. The improvement in ultimate strength obtained from the quasi-static stress–strain curves of the samples (compared to pure Mg) varied from 9.9% for DH to 24% for SHB. The dynamic strength of the samples was improved (with respect to pure Mg) by 73%, 116%, and 141% for the specimens compacted by Instron, DH, and SHB, respectively. The improvement in strength was believed to be due to strengthening mechanisms, friction, adiabatic heating, and shock waves.     

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.