JOM最新文献

Metals extraction and processing generate a substantial amount of industrial waste, posing significant environmental hazards. To reduce the accumulation of such waste, this paper incorporates steel slag (SS) into a lime (CH)–sodium sulfate (SN) composite-activated cementitious system. The mechanical properties, hydration products, and microstructure of the cementitious system with varying SS contents were characterized. The results indicate that the addition of SS not only enhances the mechanical properties of the cementitious system but also significantly reduces its cost and energy consumption. When the content of SS is lower than 30%, it does not reduce the generation of C-(A)-S-H and ettringite in the cementitious system, and can be used as a micro-filling to make the matrix dense, thus improving the mechanical properties of the cementitious system. However, as the SS content continues to increase, the formation of C-(A)-S-H and ettringite in the cementitious system decreases, leading to an increase in the number of harmful pores in the matrix and a subsequent reduction in the mechanical properties of the system. This study provides important insights into the sustainable development of metal extraction and processing.

Nanocellulose extracted from agro-waste rice straw has been utilized to fabricate carbon nanofiber films. The nanocellulose-based films were drop-casted and underwent a two-step thermal treatment: stabilization at 180°C in air and carbonization at 700°C in a nitrogen atmosphere. Phosphoric acid (PA) was incorporated into the nanocellulose solution, resulting in a 17% reduction in stabilization activation energy and a 20% increase in carbonization yield. Additionally, PA facilitated phosphorus doping, leading to a phosphorus concentration of up to 5%, and enhanced the Brunauer–Emmett–Teller (BET) surface area from 223 m² g⁻¹ to 334 m² g⁻¹. Structural analysis via XRD, Raman spectroscopy, and TEM confirmed the formation of a turbostratic graphitic structure in the PA-doped carbon nanofiber films. This increased surface area and graphitic structure make the films highly promising for diverse applications, including flame-retardant coatings, sensors, energy storage devices, and biomedical uses.

Chlorite is a typical aluminum-bearing mineral found in sedimentary bauxite deposits. To achieve the efficient extraction of alumina from chlorite, this study proposes an oxidative Bayer digestion and compares the reaction behavior of chlorite under the conventional Bayer digestion conditions. During the conventional high-temperature Bayer digestion process, chlorite hardly reacts with sodium aluminate solution, resulting in a low digestion rate of alumina. Through comparative experiments with the addition of sodium nitrate as an oxidant, it was found that ferrous ions in the chlorite were easily oxidized to trivalent iron, leading to the phase transformation of chlorite, and enhancing the digestion of alumina. The relative digestion rate increased from 88.39% under conventional digestion to 95.48% under oxidative Bayer digestion. In this process, nitrate ions are transformed into nitrite ions and ammonia gas. These research findings provide important theoretical insights for the large-scale extraction and utilization of sedimentary bauxite deposits with a high chlorite content.

Material test reactors (MTRs) are used to irradiate nuclear fuels and materials to develop data for how they endure neutron bombardment in or near reactor cores. Most historic MTRs, and all that remain operational in the US today, are water-cooled types and produce a thermalized neutron flux. New irradiation facilities are needed which can produce neutron energy spectra relevant to fast and fusion reactor environments. Construction of these facilities will take several years of steadfast funding to complete, which poses a formidable schedule challenge for current fast and fusion reactor developers. Irradiation designs which modify the neutron energy spectra delivered to test specimens in thermal spectrum MTRs, an approach referred to as “spectral tailoring”, can be used to approximate several relevant phenomena in the materials needed to enable fast and fusion reactor technologies. This approach is imperfect, but still valuable in the present situation. The two highest flux MTRs operational in the United States, the Advanced Test Reactor (ATR) and High Flux Isotope Reactor (HFIR), have rich histories, ongoing developments, and new potentials for spectral tailoring that will be reviewed and discussed in this paper.

Laser powder bed fusion (LPBF)-based additive manufacturing (AM) provides high print resolution which enables design freedom and the fabrication of complex geometries. However, anisotropy is a major challenge that impacts the properties of LPBF materials. In this study, we investigate the mechanical anisotropy of an LPBF-produced BCC Ti-45Nb alloy that exhibits a weakly elongated (near equiaxed) microstructure with no preferred grain orientation. Based on uniaxial tensile tests, profilometry-based indentation plastometry, and microhardness tests along the laser scan and build directions, we find a strong mechanical anisotropy in the randomly oriented LPBF Ti-45Nb alloy. By employing these distinct multi-scale mechanical testing techniques, we delineate the influence of LPBF microstructural features such as grain morphology, cellular structures, melt pool boundaries, and crystallographic texture on the anisotropic behavior. Our work specifically highlights the role of melt interface length on the mechanical (yield) anisotropy.

This study uses sulfuric acid activation-water leaching method to decompose and leach iron from roasted cyanide tailings, thereby creating favorable conditions for the further leaching of gold from the tailings. The leachate obtained from the decomposition of iron is purified and then prepared into liquid polyferric sulfate. The gold in the leaching residue after iron decomposition is leached using cyanidation. The results show that at 100°C, by activating cyanide tailings with concentrated sulfuric acid for 1 h at a volume-to-mass ratio of 0.7:1, the leaching rate of iron can reach 82.64%. With 4000 g/ton of sodium cyanide used on the leached residue, the gold leaching rate can reach 83.4%. After reduction with iron powder, the strongly acidic, high-iron-content solution uses Na₂S as a precipitating agent to remove arsenic and zinc through a two-stage precipitation process. The arsenic content in the solution can be reduced from 253 mg/L to 5.01 mg/L, and the zinc content can be reduced from 207 mg/L to 65.8 mg/L. This study not only realizes the high-value utilization of waste but also reduces the accumulation of waste through the treatment of roasting cyanide tailings, which has a good application prospect.

301 stainless steel is austenitic stainless steel with excellent service characteristics. To fully reveal the influence of the spraying process on its surface characteristics, a 3D HVOF thermal spraying model was established in this study. The transient evolution for flame flow was simulated during the spraying WC-12Co powder on the surface of 301 stainless-steel substrate, and the particle distribution at different locations in the calculation domain was captured. The effects of substrate shape, spraying angle and spraying distance on the substrate temperature, strain rate and shear stress were analyzed. The results show that the temperature distribution affects the strain rate and shear stress on the substrate surface. The more uniform the temperature distribution, the lower the strain rate and shear stress. For the cylinder substrate, the strain rate and shear stress of 60° spraying angle are lower and concentrated on one side (upper part) of the substrate. The spraying direction should be selected from top to bottom, which can uniformly reduce the substrate surface stress and facilitate the high-quality coating formation.

New energy vehicles are gradually becoming widespread in China, and the quantity of installed and retired power LiFePO₄ batteries has increased. The traditional wet recovery process of LiFePO₄ cathode materials produces a lot of waste acid and waste alkali, which is inconsistent with the modern industrial concept of zero emissions and zero waste. This paper proposes a novel environmental protection process for direct remediation of spent LiFePO₄. Li₂CO₃ is the lithium source, and expired food-grade sucrose is used to reduce the spent LiFePO₄ cathode materials, which are then regenerated under the premise of achieving zero emissions and zero waste. When the addition of Li₂CO₃ is 4 wt% and the sucrose content is 15 wt%, the regenerated LiFePO₄/C material exhibits uniform particle size and favorable morphology. At 0.1 C, the initial discharge specific capacity is 156.15 mAh g^-1. At 5 C, its discharge performance is 106.01 mAh g^-1, and the electrochemical performance of the regenerated LiFePO₄/C material is similar to that of the commercial LiFePO₄. Moreover, the regulation mechanism of lithium replenishment repair in LiFePO₄ cathode materials is explored from the perspectives of material structure and physical phase composition.

The oxygen evolution reaction (OER) is known as a kinetics barrier in electrochemical water splitting. Developing stabilized non-precious metal-based catalysts is crucial for the wide application of electrolytic water splitting in oxygen production. Porous Co-based intermetallics function as promising non-noble metal catalysts for OER. Porous nanogrid-like Cu-doped Co-based materials (D-CAC) were prepared via the combination of rapid self-exothermic reactions and subsequent chemical dealloying. The Co-Al intermetallics possess high porosity and large specific surface area, which can promote mass transfer. On the other hand, proper metal doping is beneficial to adjust the absorption and desorption of oxygen-containing intermediate species. Accordingly, the D-CAC sample exhibited excellent OER activity with an overpotential of 370 mV@10 mA cm^-1 and a low Tafel slope of 52.7 mV dec^-1 in 1 M KOH. These findings offer a novel perspective on the efficient development of cobalt-based electrocatalysts for oxygen evolution.