This study synthesised a zincic salt (ZS) as a depressant for marmatite—galena separation. The effect of ZS on the flotation of marmatite and galena was investigated through micro-flotation tests. 88.89% of the galena was recovered and 83.39% of the marmatite was depressed with ZS dosage of 750 mg·L−1 at pH = 4. The depression mechanism of ZS on marmatite was investigated by a variety of techniques, including adsorption measurements, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopic (XPS) analysis, and time of flight secondary ion mass spectrometry (ToF-SIMS). Results of adsorption tests and FTIR reveal that ZS adsorbed on marmatite surface and impeded the subsequent adsorption of butyl xanthate (BX). The results of XPS and ToF-SIMS indicate that the ZnO 2−2 released by ZS could be chemisorbed on the marmatite surface and depress marmatite flotation.

We analyzed a novel cationic collector using chemical plant byproducts, such as cetyltrimethylammonium bromide (CTAB) and dibutyl phthalate (DBP). Our aim is to establish a highly effective and economical process for the removal of quartz from collophane. A micro-flotation test with a 25 mg·L−1 collector at pH value of 6–10 demonstrates a considerable difference in the floatability of pure quartz and fluorapatite. Flotation tests for a collophane sample subjected to the first reverse flotation for magnesium removal demonstrates that a rough flotation process (using a 0.4 kg·t−1 new collector at pH = 6) results in a collophane concentrate with 29.33wt% P2O5 grade and 12.66wt% SiO2 at a 79.69wt% P2O5 recovery, providing desirable results. Mechanism studies using Fourier transform infrared spectroscopy, zeta potential, and contact angle measurements show that the adsorption capacity of the new collector for quartz is higher than that for fluorapatite. The synergistic effect of DBP increases the difference in hydrophobicity between quartz and fluorapatite. The maximum defoaming rate of the novel cationic collector reaches 142.8 mL·min−1. This is considerably higher than that of a conventional cationic collector.

The Li2ZnTi3O8@LiAlO2 was synthesized by a facile high-temperature solid-state route. The LiAlO2 modification does not alter the morphology and particle size of Li2ZnTi3O8 (LZTO). The LiAlO2 modification improves the structure stability, intercalation/deintercalation reversibility of lithium-ions, and electrochemical reaction activity of Li2ZnTi3O8, and promotes the transfer of lithium ions. Benefited from the unique component, Li2ZnTi3O8@LiAlO2 (8wt%) shows a good rate performance with charge capacities of 203.9, 194.8, 187.4, 180.6, and 177.1 mAh·g−1 at 0.5, 1, 2, 3, and 5 C, respectively. Nevertheless, pure LZTO only delivers charge capacities of 134.5, 109.7, 89.4, 79.9, and 72.9 mAh·g−1 at the corresponding rates. Even at large charge—discharge rate, the Li2ZnTi3O8@LiAlO2 (8wt%) composite indicates a good cycle performance with a high reversible charge/discharge capacity of 263.5/265.8 mAh·g−1 at 5 C after 150 cycles. The introduction of LiAlO2 on the surface of Li2ZnTi3O8 enhances electronic conductivity of the composite, resulting in the good electrochemical performance of Li2ZnTi3O8@LiAlO2 composite. Li2ZnTi3O8@LiAlO2 (8wt%) composite shows a good potential as an anode material for the next generation of high-performance Li-ion batteries.

The formation mechanism of calcium vanadate and manganese vanadate and the difference between calcium and manganese in the reaction with vanadium are basic issues in the calcification roasting and manganese roasting process with vanadium slag. In this work, CaO-V2O5 and MnO2-V2O5 diffusion couples were prepared and roasted for different time periods to illustrate and compare the diffusion reaction mechanisms. Then, the changes in the diffusion product and diffusion coefficient were investigated and calculated based on scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) analysis. Results show that with the extension of the roasting time, the diffusion reaction gradually proceeds among the CaO-V2O5 and MnO2-V2O5 diffusion couples. The regional boundaries of calcium and vanadium are easily identifiable for the CaO-V2O5 diffusion couple. Meanwhile, for the MnO2-V2O5 diffusion couple, MnO2 gradually decomposes to form Mn2O3, and vanadium diffuses into the interior of Mn2O3. Only a part of vanadium combines with manganese to form the diffusion production layer. CaV2O6 and MnV2O6 are the interfacial reaction products of the CaO-V2O5 and MnO2-V2O5 diffusion couples, respectively, whose thicknesses are 39.85 and 32.13 µm when roasted for 16 h. After 16 h, both diffusion couples reach the reaction equilibrium due to the limitation of diffusion. The diffusion coefficient of the CaO-V2O5 diffusion couple is higher than that of the MnO2-V2O5 diffusion couple for the same roasting time, and the diffusion reaction between vanadium and calcium is easier than that between vanadium and manganese.

The macroscopic characteristics of molten salts are governed by their microstructures. Research on the structures of molten salts provides the foundation for a full understanding of the physicochemical properties of molten salts as well as a deeper analysis of the microscopic electrolysis process in molten salts. Information about the microstructure of matter can be obtained with the help of several speculative and experimental procedures. In this review, the advantages and disadvantages of the various test procedures used to determine the microstructures of molten salts are compared. The typical coordination configurations of metal ions in molten salt systems are also summarized. Furthermore, the impact of temperature, anions, cations, and metal oxides (O2−) on the structures of molten salts is discussed in detail. The accuracy and completeness of the information on molten salt structures need to be investigated by the integration of multiple methods and interdisciplinary fields. Information on the microstructure and coordination of molten salts deepens the understanding of the elementary elements of the microstructure of matter. This paper, which is based on the review of the coordination states of metal ions in molten salts, is hoped to inspire researchers to explore the inter-relationship between the microstructure and macroscopic properties of materials.

Currently, the process of extracting rubidium from ores has attracted a great deal of attention due to the increasing application of rubidium in high-technology field. A novel process for the comprehensive utilization of rubidium ore resources is proposed in this paper. The process consists mainly of mineral dissociation, selective leaching, and desilication. The results showed that the stable silicon—oxygen tetrahedral structure of the rubidium ore was completely disrupted by thermal activation and the mineral was completely dissociated, which was conducive to subsequent selective leaching. Under the optimal conditions, extractions of 98.67% Rb and 96.23% K were obtained by leaching the rubidium ore. Moreover, the addition of a certain amount of activated Al(OH)3 during leaching can effectively inhibit the leaching of silicon. In the meantime, the leach residue was sodalite, which was successfully synthesized to zeolite A by hydrothermal conversion. The proposed process provided a feasible strategy for the green extraction of rubidium and the sustainable utilization of various resources.

Pure Ni and its composites with different percentages of Ni–Cr nano-oxides were coated over carbon steel to assess the coating features and mechanical and corrosion behavior. A nano-oxide composite of Ni–Cr was first synthesized through chemical coprecipitation with uniform distribution constituents. Electrodeposition was employed to coat pure Ni and Ni–Ni–Cr) oxides (10, 20, 30, 40, and 50 g/L) on the steel sheets. Transmission electron microscope and field emission scanning electron microscope were adopted to examine the microstructure of powders and coatings, and X-ray diffraction analysis was employed to study the chemical composition. The microhardness, thickness, and wear resistance of the coatings were assessed, polarization and electrochemical impedance spectroscopy (EIS) tests were conducted to analyze the corrosion behavior, and the corresponding equivalent circuit was developed. Results showed flawless and crack-free coatings for all samples and uniform distribution of nano-oxides in the Ni matrix for the samples of 10–30 g/L. Agglomerated oxides were detected at high concentrations. Maximum microhardness (HV 661), thickness (116 µm), and wear resistance of coatings were found at 30 g/L. A three-loop equivalent circuit corresponded satisfactorily to all EIS data. The corrosion resistance increased with the nano-oxide concentration of up to 30 g/L but decreased at 40 g/L. The sample of 50 g/L showed the best corrosion resistance.

A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow, circulation flow rate, and mixing time during Ruhrstahl-Heraeus (RH) refining process. Also, a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up, and measurements were carried out to validate the mathematical model. The results show that, with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min−1, the mixing time predicted by the mathematical model agrees well with the measured values. The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations, where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value. In addition, the circulation flow rate was 9 kg·s−1. When the gas blowing nozzle was horizontally rotated by either 30° or 45°, the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle, due to the rotational flow formed in the up-snorkel. Furthermore, the mixing time at the monitoring point 1, 2, and 3 was shortened by around 21.3%, 28.2%, and 12.3%, respectively. With the nozzle angle of 30° and 45°, the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.

To assess the widely used submerged side-blowing in pyrometallurgy, a high-speed camera-digital image processing-statistical approach was used to systematically investigate the effects of the gas flow rate, nozzle diameter, and inclination angle on the space-time distribution and penetration behavior of submerged side-blown gas in an air-water system. The results show that the gas motion gradually changes from a bubbling regime to a steady jetting regime and the formation of a complete jet structure as the flow rate increases. When the flow rate is low, a bubble area is formed by large bubbles in the area above the nozzle. When the flow rate and the nozzle diameter are significant, a bubble area is formed by tiny bubbles in the area above the nozzle. The increased inclination angle requires a more significant flow rate to form a complete jet structure. In the sampling time, the dimensionless horizontal and vertical penetration depths are Gaussian distributed. Decreasing the nozzle diameter and increasing the flow rate or inclination angle will increase the distribution range and discreteness. New correlations for a penetration depth with an error of ±20% were obtained through dimensional analysis. The dimensionless horizontal penetration depth of an argon-melt system in a 120 t converter calculated by the correlation proposed by the current study is close to the result calculated by a correlation in the literature and a numerical simulation result in the literature.

A backfilling body-coal pillar-backfilling body (BPB) structure formed by pillar-side cemented paste backfilling can bear overburden stress and ensure safe mining. However, the failure response of BPB composite samples must be investigated. This paper examines the deformation characteristics and damage evolution of six types of BPB composite samples using a digital speckle correlation method under uniaxial compression conditions. A new damage evolution equation was established on the basis of the input strain energy and dissipated strain energy at the peak stress. The prevention and control mechanisms of the backfilling body on the coal pillar instability were discussed. The results show that the deformation localization and macroscopic cracks of the BPB composite samples first appeared at the coal-backfilling interface, and then expanded to the backfilling elements, ultimately appearing in the coal elements. The elastic strain energy in the BPB composite samples reached a maximum at the peak stress, whereas the dissipated energy continued to accumulate and increase. The damage evolution curve and equation agree well with the test results, providing further understanding of instability prevention and the control mechanisms of the BPB composite samples. The restraining effect on the coal pillar was gradually reduced with decreasing backfilling body element’s volume ratio, and the BPB composite structure became more vulnerable to failure. This research is expected to guide the design, stability monitoring, instability prevention, and control of BPB structures in pillar-side cemented paste backfilling mining.

The martensitic transformation, mechanical, and magnetic properties of the Ni2Mn1.5−xCuxTi0.5 (x = 0.125, 0.25, 0.375, 0.5) and Ni2−yCoyMn1.5−xCuxTi0,5 [(x = 0.125, y = 0.125, 0.25, 0.375, 0.5) and (x = 0.125, 0.25, 0.375, y = 0.625)] alloys were systematically studied by the first-principles calculations. For the formation energy, the martensite is smaller than the austenite, the Ni-(Co)-Mn-Cu-Ti alloys studied in this work can undergo martensitic transformation. The austenite and non-modulated (NM) martensite always present antiferromagnetic state in the Ni2Mn1.5−xCuxTi0.5 and Ni2−yCoyMn1.5−xCuxTi0.5 (y < 0.625) alloys. When y = 0.625 in the Ni2−yCoyMn1.5−xCuxTi0.5 series, the austenite presents ferromagnetic state while the NM martensite shows antiferromagnetic state. Cu doping can decrease the thermal hysteresis and anisotropy of the Ni-(Co)-Mn-Ti alloy. Increasing Mn and decreasing Ti content can improve the shear resistance and normal stress resistance, but reduce the toughness in the Ni-Mn-Cu-Ti alloy. And the ductility of the Co-Cu co-doping alloy is inferior to that of the Ni-Mn-Cu-Ti and Ni-Co-Mn-Ti alloys. The electronic density of states was studied to reveal the essence of the mechanical and magnetic properties.

Si-based optical position-sensitive detectors (PSDs) have stimulated the interest of researchers due to their wide range of practical applications. However, due to the rigidity and fragility of Si crystals, the applications of flexible PSDs have been limited. Therefore, we presented a flexible broadband PSD based on a WS2/Si heterostructure for the first time. A scalable sputtering method was used to deposit WS2 thin films onto the etched ultrathin crystalline Si surface. The fabricated flexible PSD device has a broad spectral response in the wavelength range of 450–1350 nm, with a high position sensitivity of ∼539.8 mV·mm−1 and a fast response of 2.3 µs, thanks to the strong light absorption, the built-in electrical field at the WS2/Si interface, and facilitated transport. Furthermore, mechanical-bending tests revealed that after 200 mechanical-bending cycles, the WS2/Si PSDs have excellent mechanical flexibility, stability, and durability, demonstrating the great potential in wearable PSDs with competitive performance.

This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate. The quarter-thickness (1/4t) and half-thickness (1/2t) regions of the plate exhibited similar ductility and toughness after quenching. After tempering, the 1/4t region exhibited ∼50% and ∼25% enhancements in both the total elongation and low-temperature toughness at −40°C, respectively, without a decrease in yield strength, whereas the toughness of the 1/2t region decreased by ∼46°%. After quenching, both the 1/4t and 1/2t regions exhibited lower bainite and lath martensite concentrations, but only the 1/2t region exhibited microstructure bands. Moreover, the tempered 1/4t region featured uniformly dispersed short rod-like M23C6 carbides, and spherical MC precipitates with diameters of ∼20–100 nm and <20 nm, respectively. The uniformly dispersed nanosized M23C6 carbides and MC precipitates contributed to the balance of high strength and high toughness. The band microstructure of the tempered 1/2t region featured a high density of large needle-like M3C carbides. The length and width of the large M3C carbides were ∼200–500 nm and ∼20–50 nm, respectively. Fractography analysis revealed that the high density of large carbides led to delamination cleavage fracture, which significantly deteriorated toughness.

High geostress will become a normality in the deep because in-situ stress rises linearly with depth. The geological structure grows immensely intricate as depth increases. Faults, small fractures, and joint fissures are widely developed. The objective of this paper is to identify geostress anomalies at a variety of locations near faults and to demonstrate their accumulation mechanism. Hydrofracturing tests were conducted in seven deep boreholes. We conducted a test at a drilling depth of over one thousand meters to reveal and quantify the influence of faults on in-situ stresses at the hanging wall, footwall, between faults, end of faults, junction of faults, and far-field of faults. The effect of fault sites and characteristics on the direction and magnitude of stresses has been investigated and compared to test boreholes. The accumulation heterogeneity of stresses near faults was illustrated by a three-dimensional numerical simulation, which is utilized to explain the effect of faults on the accumulation and differentiation of in-situ stress. Due to regional tectonics and faulting, the magnitude, direction, and stress regime are all extremely different. The concentration degree of geostress and direction change will vary with the location of faults near faults, but the magnitude and direction of in-situ stress conform to regional tectonic stress at a distance from the faults. The focal mechanism solution has been verified using historical seismic ground motion vectors. The results demonstrate that the degree of stress differentiation varies according to the fault attribute and its position. Changes in stress differentiation and its ratio from strong to weak occur between faults, intersection, footwall, end of faults, and hanging wall; along with the sequence of orientation is the footwall, between faults, the end of faults, intersection, and hanging wall. This work sheds new light on the fault-induced stress accumulation and orientation shift mechanisms across the entire cycle.

Understanding the in situ stress state is crucial in many engineering problems and earth science research. The present article presents new insights into the interaction mechanism between the stress state and faults. In situ stresses can be influenced by various factors, one of the most important being the existence of faults. A fault could significantly affect the value and direction of the stress components. Reorientation and magnitude changes in stresses exist adjacent to faults and stress jumps/discontinuities across the fault. By contrast, the change in the stress state may lead to the transformation of faulting type and potential fault reactivation. Qualitative fault reactivation assessment using characteristic parameters under the current stress environment provides a method to assess the slip tendency of faults. The correlation between in situ stresses and fault properties enhances the ability to predict the fault slip tendency via stress measurements, which can be used to further refine the assessment of the fault reactivation risk. In the future, stress measurements at greater depths and long-term continuous real-time stress monitoring near/on key parts of faults will be essential. In addition, much attention needs to be paid to distinguishing the genetic mechanisms of abnormal stress states and the type and scale of stress variations and exploring the mechanisms of pre-faulting anomaly and fault reactivation.

With the number of decommissioned electric vehicles increasing annually, a large amount of discarded power battery cathode material is in urgent need of treatment. However, common leaching methods for recovering metal salts are economically inefficient and polluting. Meanwhile, the recycled material obtained by lithium remediation alone has limited performance in cycling stability. Herein, a short method of solid-phase reduction is developed to recover spent LiFePO4 by simultaneously introducing Mg2+ ions for hetero-atom doping. Issues of particle agglomeration, carbon layer breakage, lithium loss, and Fe3+ defects in spent LiFePO4 are also addressed. Results show that Mg2+ addition during regeneration can remarkably enhance the crystal structure stability and improve the Li+ diffusion coefficient. The regenerated LiFePO4 exhibits significantly improved electrochemical performance with a specific discharge capacity of 143.2 mAh·g−1 at 0.2 C, and its capacity retention is extremely increased from 37.9% to 98.5% over 200 cycles at 1 C. Especially, its discharge capacity can reach 95.5 mAh·g−1 at 10 C, which is higher than that of spent LiFePO4 (55.9 mAh·g−1). All these results show that the proposed regeneration strategy of simultaneous carbon coating and Mg2+ doping is suitable for the efficient treatment of spent LiFePO4.

Because of their large volume variation and inferior electrical conductivity, Mn3O4-based oxide anode materials have short cyclic lives and poor rate capability, which obstructs their development. In this study, we successfully prepared a Mn3O4/N-doped honeycomb carbon composite using a smart and facile synthetic method. The Mn3O4 nanopolyhedra are grown on N-doped honeycomb carbon, which evidently mitigates the volume change in the charging and discharging processes but also improves the electrochemical reaction kinetics. More importantly, the Mn—O—C bond in the Mn3O4/N-doped honeycomb carbon composite benefits electrochemical reversibility. These features of the Mn3O4/N-doped honeycomb carbon (NHC) composite are responsible for its superior electrochemical performance. When used for Li-ion batteries, the Mn3O4/N-doped honeycomb carbon anode exhibits a high reversible capacity of 598 mAh·g−1 after 350 cycles at 1 A·g−1. Even at 2 A·g−1, the Mn3O4/NHC anode still delivers a high capacity of 472 mAh·g−1. This work provides a new prospect for synthesizing and developing manganese-based oxide materials for energy storage.

The low-reactivity mold flux with low SiO2 content is considered suitable for the continuous casting of high-aluminum steel since it can significantly reduce the reaction between Al in steel and SiO2 in mold flux. However, the traditional low-reactivity mold flux still presents some problems such as high viscosity and strong crystallization tendency. In this study, the co-addition of Li2O and B2O3 in CaO–Al2O3–10wt%SiO2 based low-reactivity mold flux was proposed to improve properties of mold flux for high-aluminum steel, and the effect of Li2O replacing B2O3 on properties of mold flux was investigated. The viscosity of the mold flux with 2wt% Li2O and 6wt% B2O3 reached a minimum value of 0.07 Pa·s. The break temperature and melting point showed a similar trend with the viscosity. Besides, the melt structure and precipitation of the crystalline phase were studied using Raman and X-ray diffraction spectra to better understand the evolution of viscosity. It demonstrated that with increasing Li2O content in the mold flux from 0 to 6wt%, the degree of polymerization of aluminate and the aluminosilicate network structure increased because of increasing Li+ released by Li2O, indicating the added Li2O was preferentially associated with Al3+ as a charge compensator. The precipitation of LiAlO2 crystalline phase gradually increased with the replacement of B2O3 by Li2O. Therefore, Li2O content should be controlled below 2wt% to avoid LiAlO2 precipitation, which was harmful to the continuous casting of high-aluminum steels.

Tin-based materials are very attractive anodes because of their high theoretical capacity, but their rapid capacity fading from volume expansions limits their practical applications during alloying and dealloying processes. Herein, the improved binder-free tin-copper intermetallic/carbon nanotubes (Cu6Sn5/CNTs) alloy thin-film electrodes are directly fabricated through efficient in situ electrodeposition from the leaching solution of treated waste-printed circuit boards (WPCBs). The characterization results show that the easily agglomerated Cu6Sn5 alloy nanoparticles are uniformly dispersed across the three-dimensional network when the CNTs concentration in the electrodeposition solution is maintained at 0.2 g·L−1. Moreover, the optimal Cu6Sn5/CNTs-0.2 alloy thin-film electrode can not only provide a decent discharge specific capacity of 458.35 mAh·g−1 after 50 cycles at 100 mA·g−1 within capacity retention of 82.58% but also deliver a relatively high reversible specific capacity of 518.24, 445.52, 418.18, 345.33, and 278.05 mAh·g−1 at step-increased current density of 0.1, 0.2, 0.5, 1.0, and 2.0 A·g−1, respectively. Therefore, the preparation process of the Cu6Sn5/CNTs-0.2 alloy thin-film electrode with improved electrochemical performance may provide a cost-effective strategy for the resource utilization of WPCBs to fabricate anode materials for lithium-ion batteries.

Paste flow patterns and microscopic particle structures were studied in a pressurized environment generated by a pulse pump. Complex loop-pipe experiments and fluid–solid coupling-based simulations were conducted. The scanning electron microscopy technique was also applied. Results revealed that flow resistance is closely related to pipeline curvature and angle in a complex pipe network. The vertical downward–straight pipe–inclined downward combination was adopted to effectively reduce the loss in resistance along with reducing the number of bends or increasing the radius of bend curvature. The maximum velocity ratio and velocity offset values could quantitatively characterize the influences of different pipeline layouts on the resistance. The correlation reached 96%. Particle distribution and interparticle forces affected flow resistance. Uniform particle states and weak interparticle forces were conducive to steady transport. Pulse pump pressure led to high flow resistance. It could improve pipe flow stability by increasing flow uniformity and particle motion stability. These results can contribute to safe and efficient paste filling.