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.     

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.     

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.     

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).     

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.     

铁酸锌焙烧后的还原行为及氨浸特性

A novel method for recovering zinc from zinc ferrite by reduction roasting–ammonia leaching was studied in this paper. The reduction thermodynamic of zinc ferrite by CO was analyzed. The effects of roasting parameters on the phase transformation and conversion rate of zinc ferrite, and the leaching behavior of zinc from the reductive roasted samples by ammonia leaching, were experimentally investigated. The mineralogical phase compositions and chemical compositions of the samples were characterized by X-ray diffraction and chemical titration methods, respectively. The results showed that most of the zinc ferrite was transformed to zinc oxide and magnetite after weak reduction roasting. 86.43% of the zinc ferrite was transformed to zinc oxide under the optimum conditions: CO partial pressure of 25%, roasting temperature of 750°C, and roasting duration of 45 min. Finally, under the optimal leaching conditions, 78.12% of zinc was leached into the solution from the roasted zinc ferrite while all iron-bearing materials were kept in the leaching residue. The leaching conditions are listed as follows: leaching duration of 90 min, ammonia solution with 6 mol/L concentration, leaching temperature of 50°C, solid-to-liquid ratio of 40 g/L, and stirring speed of 200 r/min.     

放电等离子烧结制备石墨烯纳米片增强7075铝合金复合材料的力学性能

A 0.3wt% graphene nanoplatelets (GNPs) reinforced 7075 aluminum alloy matrix (7075 Al) composite was fabricated by spark plasma sintering and its strength and wear resistance were investigated. The microstructures of the internal structure, the friction surface, and the wear debris were characterized by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Compared with the original 7075 aluminum alloy, the hardness and elastic modulus of the 7075 Al/GNPs composite were found to have increased by 29% and 36%, respectively. The results of tribological experiments indicated that the composite also exhibited a lower wear rate than the original 7075 aluminum alloy.     

利用立辊磨的低品位菱镁矿选矿新工艺研究

We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill. We conducted experiments involving the reverse flotation and positive flotation of low-grade magnesite to determine the optimum process parameters, and then performed closed-circuit beneficiation experiments using the vertical roller mill and ball mill. The results show that the optimum process parameters for the vertical roller mill are as follows: a grinding fineness of 81.6wt% of particles less than 0.074 mm, a dodecyl amine (DDA) dosage in magnesite reverse flotation of 100 g·t?1, and dosages of Na₂CO₃, (NaPO₃)₆, and NaOL in the positive flotation section of 1000, 100, and 1000 g·t?1, respectively. Compared with the ball mill, the use of the vertical roller mill in the beneficiation of low-grade magnesite resulted in a 1.28% increase in the concentrate grade of MgO and a 5.88% increase in the recovery of MgO. The results of our causation mechanism analysis show that a higher specific surface area and greater surface roughness are the main reasons for the better flotation performance of particles ground by the vertical roller mill in the beneficiation of low-grade magnesite.     

Investigation of structural,morphological and electrochemical properties of mesoporous La2CuCoO6 rods fabricated by facile hydrothermal route

This work introduces the facile hydrothermal synthesis of double perovskite La₂CuCoO₆. X-ray diffraction pattern confirmed the formation of a monoclinic phase with P12₁/c1 symmetry. Transmission electron microscopy results revealed that the self-assembled porous rods were composed of nanocrystallite aggregates. The estimated specific surface area of these mesoporous rods with an average pore diameter of 6 nm was ~41 m2·g–1. The presence of ions with oxidation states of La3+, Cu2+, and Co2+/Co3+ on the surface of the mesoporous La₂CuCoO₆ rods was confirmed by X-ray photoelectron spectroscopic analysis. Via cyclicvoltammetry and chronopotentiometry, the electrode fabricated from the mesoporous La₂CuCoO₆ rods were found to exhibit pseudocapacitive behavior with a specific capacitance of 259.4 F·g–1 at a current density of 0.5 A·g–1. An ~89% retention in specific capacitance was achieved after 1000 charge/discharge cycles at a constant current density of 4 A·g–1.     

动力学控制合成原子精确的银纳米团簇及催化还原4-硝基苯酚

Synthesizing atomically precise Ag nanoclusters (NCs), which is essential for the general development of NCs, is quite challenging. In this study, we report the synthesis of high-purity atomically precise Ag NCs via a kinetically controlled strategy. The Ag NCs were prepared using a mild reducing agent via a one-pot method. The as-prepared Ag NCs were confirmed to be Ag₄₉(D-pen)₂₄ (D-pen: D-penicillamine) on the basis of their matrix-assisted laser desorption ionization time-of-flight mass spectrometric and thermogravimetric characteristics. The interfacial structures of the Ag NCs were illustrated by proton nuclear magnetic resonance and Fourier-transform infrared spectroscopy. The Ag NCs were supported on activated carbon (AC) to form Ag NCs/AC, which displayed excellent activity for the catalytic reduction of 4-nitrophenol with a kinetic reaction rate constant k of 0.21 min?1. Such a high k value indicates that the composite could outperform several previously reported catalysts. Moreover, the catalytic activity of Ag NCs/AC remained nearly constant after six times of recycle, which suggests its excellent stability.     

Morphology control of aluminum nitride (AlN) for a novel high-temperature hydrogen sensor

Hydrogen is a promising renewable energy source for fossil-free transportation and electrical energy generation. However, leaking hydrogen in high-temperature production processes can cause an explosion, which endangers production workers and surrounding areas. To detect leaks early, we used a sensor material based on a wide bandgap aluminum nitride (AlN) that can withstand a high-temperature environment. Three unique AlN morphologies (rod-like, nest-like, and hexagonal plate-like) were synthesized by a direct nitridation method at 1400°C using γ-AlOOH as a precursor. The gas-sensing performance shows that a hexagonal plate-like morphology exhibited p-type sensing behavior and showed good repeatability as well as the highest response (S = 58.7) toward a 750 ppm leak of H₂ gas at high temperature (500°C) compared with the rod-like and nest-like morphologies. Furthermore, the hexagonal plate-like morphology showed fast response and recovery times of 40 and 82 s, respectively. The surface facet of the hexagonal morphology of AlN might be energetically favorable for gas adsorption–desorption for enhanced hydrogen detection.     

铝基复合材料界面Al?Ce?Cu?W非晶层的热驱动固相非晶化研究

Interfacial Al?Ce?Cu?W amorphous layers formed through thermally driven solid-state amorphization within the (W+CeO₂)/2024Al composite were investigated. The elemental distributions and interfacial microstructures were examined with an electron probe microanalyzer and a high-resolution transmission electron microscope, respectively. The consolidation of composites consisted of two thermal processes: vacuum degassing (VD) and hot isostatic pressing (HIP). During consolidation, not only the three major elements (Al, W, and Ce) but also the alloying elements (Mg and Cu) in the Al matrix contributed to amorphization. At VD and HIP temperatures of 723 K and 763 K, interfacial amorphous layers were formed within the composite. Three diffusion processes were necessary for interfacial amorphization: (a) long-range diffusion of Mg from the Al matrix to the interfaces during VD; (b) long-range diffusion of Cu from the Al matrix to the interfaces during HIP; (c) short-range diffusion of W toward the Al matrix during HIP. The newly formed interfacial Al?Ce?Cu?W amorphous layers can be categorized under the Al?Ce?TM (TM: transition metals) amorphous system.     

Na2CO3–K2CO3熔盐电化学法除锈

The formation of a rust layer on iron and steels surfaces accelerates their degradation and eventually causes material failure. In addition to fabricating a protective layer or using a sacrificial anode, repairing or removing the rust layer is another way to reduce the corrosion rate and extend the lifespans of iron and steels. Herein, an electrochemical healing approach was employed to repair the rust layer in molten Na₂CO₃?K₂CO₃. The rusty layers on iron rods and screws were electrochemically converted to iron in only several minutes and a metallic luster appeared. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses showed that the structures of the rust layer after healing were slightly porous and the oxygen content reached a very low level. Thus, high-temperature molten-salt electrolysis may be an effective way to metalize iron rust of various shapes and structures in a short time, and could be used in the repair of cultural relics and even preparing a three-dimensional porous structures for other applications.     

自然对流下废料熔化行为和碳扩散的模拟

A 3D model applying temperature- and carbon concentration- dependent material properties was developed to describe the scrap melting behavior and carbon diffusion under natural convection. Simulated results agreed reasonably well with experimental ones. Scrap melting was subdivided into four stages: formation of a solidified layer, rapid melting of the solidified layer, carburization, and carburization + normal melting. The carburization stage could not be ignored at low temperature because the carburization time for the sample investigated was 214 s at 1573 K compared to 12 s at 1723 K. The thickness of the boundary layer with significant concentration difference at 1573 K increased from 130 μm at 5 s to 140 μm at 60 s. The maximum velocity caused by natural convection decreased from 0.029 m·s?1 at 5 s to 0.009 m·s?1 at 634 s because the differences in temperature and density between the molten metal and scrap decreased with time.     

TiB2和Al3Ti对近共晶Al?12.6Si合金组织、力学性能和断裂行为的影响

A near eutectic Al?12.6Si alloy was developed with 0.0wt%, 2.0wt%, 4.0wt%, and 6.0wt% Al?5Ti?1B master alloy. The microstructural morphology, hardness, tensile strength, elongation, and fracture behaviour of the alloys were studied. The unmodified Al?12.6Si alloy has an irregular needle and plate-like eutectic silicon (E_Si) and coarse polygonal primary silicon (P_Si) particles in the matrix-like α-Al phase. The P_Si, E_Si, and α-Al morphology and volume fraction were changed due to the addition of the Al?5Ti?1B master alloy. The hardness, UTS, and elongation improved due to the microstructural modification. Nano-sized in-situ Al₃Ti particles and ex-situ TiB₂ particles caused the microstructural modification. The fracture images of the developed alloys exhibit a ductile and brittle mode of fracture at the same time. The Al?5Ti?1B modified alloys have a more ductile mode of fracture and more dimples compared to the unmodified alloy.     

限域于三维多孔碳的超细纳米尺度Cu2Sb合金用于钠离子和钾离子电池负极

Ultrafine nano-scale Cu₂Sb alloy confined in a three-dimensional porous carbon was synthesized using NaCl template-assisted vacuum freeze-drying followed by high-temperature sintering and was evaluated as an anode for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). The alloy exerts excellent cycling durability (the capacity can be maintained at 328.3 mA·h·g?1 after 100 cycles for SIBs and 260 mA·h·g?1 for PIBs) and rate capability (199 mA·h·g?1 at 5 A·g?1 for SIBs and 148 mA·h·g?1 at 5 A·g?1 for PIBs) because of the smooth electron transport path, fast Na/K ion diffusion rate, and restricted volume changes from the synergistic effect of three-dimensional porous carbon networks and the ultrafine bimetallic nanoalloy. This study provides an ingenious design route and a simple preparation method toward exploring a high-property electrode for K-ion and Na-ion batteries, and it also introduces broad application prospects for other electrochemical applications.