Extraction and recycling technologies of cobalt from primary and secondary resources:A comprehensive review

Cobalt has excellent electrochemical,magnetic,and heat properties.As a strategic resource,it has been applied in many hightech products.However,the recent rapid growth of the battery industry has substantially depleted cobalt resources,leading to a crisis of cobalt resource supply.The paper examines cobalt ore reserves and distribution,and the recent development and consumption of cobalt resources are summarized as well.In addition,the principles,advantages and disadvantages,and research status of various methods are discussed comprehensively.It can be concluded that the use of diverse sources(Cu-Co ores,Ni-Co ores,zinc plant residues,and waste cobalt products)for cobalt production should be enhanced to meet developmental requirements.Furthermore,in recovery technology,the pyro-hydrometallurgical process employs pyrometallurgy as the pretreatment to modify the phase structure of cobalt minerals,enhancing its recovery in the hydrometallurgical stage and facilitating high-purity cobalt production.Consequently,it represents a promising technology for future cobalt recovery.Lastly,based on the above conclusions,the prospects for cobalt are assessed regarding cobalt ore processing and sustainable cobalt recycling,for which further study should be conducted.

Ultrasound application in alkaline pretreatment process of spodumene to improve particle floatability

Selective surface dissolution was found to be important in spodumene flotation. In this study, we proposed to introduce ultrasound into the pretreatment process to accelerate particle vibration and cavitation, as well as the migration of mineral surface components to solution. Micro-flotation results showed that the flotation recovery of spodumene can be 86.08% by ultrasound pretreatment, but only 39.30% by traditional mechanical agitation pretreatment. Compared with traditional mechanical agitation, ultrasonic pretreatment can shorten the pretreatment process, reduce the dosage of agents, reduce the mechanical agitation speed, and improve the efficiency of the pretreating process. Inductively coupled plasma analysis showed that, in the ultrasonic system, the amount of Li, Al, and Si species in the solution was twice as much as those in the traditional preprocessing system. Moreover, the scanning electron microscope results demonstrated a larger surface dissolution area in the ultrasonic system. X-Ray photoelectron spectroscopy results showed that the atomic concentration of Si species on the spodumene surface decreased, whereas the relative atomic concentrations of Li and Al species increased, indicating that the ultrasound effect strengthened the selective dissolution of elements on the mineral surface.The high-resolution spectra of O 1s showed that more collectors are adsorbed on the mineral surface treated by ultrasonic pretreatment.

Coordination states of metal ions in molten salts and their characterization methods

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.

Preparation of vanadium-based electrode materials and their research progress in solid-state flexible supercapacitors

Solid-state flexible supercapacitors(SCs)have many advantages of high specific capacitance,excellent flexibility,fast charging and discharging,high power density,environmental friendliness,high safety,light weight,ductility,and long cycle stability.They are the ideal choice for the development of flexible energy storage technology in the future,and provide a good prospect for energy storage applications.At present,solid-state flexible SCs are widely used for portable electronic equipment and wearable energy storage equipment,the research of them has become the focus of a growing number of researchers.Electrode material is the key part of SCs and always determines the electrochemical performance of SCs.It has been a hotspot and focus of research.Vanadium-based compounds are considered to be a promising electrode material for SCs because of variable valence,open structure,high theoretical capacity,and low price.Therefore,this study first gives an overview of solid-state flexible SCs,then reviews the current research status of vanadium-based electrode materials in solid-state flexible SCs,and proposes some strategies to solve some problems of vanadium-based electrode materials.

Recent advances in multifunctional metal-organic frameworks for lithium metal batteries

In view of novel materials in the field of lithium metal batteries(LMBs), metal-organic frameworks(MOFs) have attracted extensive research interest owing to their controllable pore size, unsaturated metal sites and multifunctional organic groups. A variety of MOFs have been elaborately calculated and synthesized to be applied as separator coating, electrolyte modulators and solid-state electrolyte fillers in LMBs. In this mini-review, we summarize the mechanism of MOFs to limit the migration of anions, improve the Li-ion transference number and prolong the lifespan of LMBs. Suitable pore structure of MOFs can physically restrict the movement of Li^(+). Unsaturated metal sites can adsorb anions by electrostatic interaction. In addition,multifunctional organic functional groups that limit the migration of anions are discussed. Finally, the key challenges and perspectives in the development direction of MOFs-based separators and electrolytes are further elaborated.

Recrystallization Behavior of the New Ni-Co-Based Superalloy with Fusion Structure Produced by Electron Beam Smelting Layered Solidification Technology

The new Ni-Co-based superalloy featuring a"fusion structure"was produced utilizing electron beam smelting layered solidification technology(EBSL).Experimental examination of hot compression deformation with varied settings for EBSL and conventional duplex process melting Ni-Co superalloys was performed.As per the study,EBSL-Ni-Co superalloys exhibited enhanced recrystallization susceptibility during hot deformation.Furthermore,elevating deformation temperature,lowering strain rate,and augmenting strain collectively contribute to enlarging the volume fraction of dynamically recrystallized grains.Aberrant growth of grains occurred when the deformation temperature equaledγ′sub-solvus temperature and the strain rate was slower.Moreover,exceeding theγ′solvus temperature during deformation significantly increases the particle size of dynamic recrystallization(DRX)grains.Theγ′phase can effectively modulate the DRX grain size through the pegging effect.Additionally,it was revealed that the presence of the fusion structure aids in the generation of continuous dynamic recrystallization,discontinuous dynamic recrystallization,and twinning-induced dynamic recrystallization while the alloy undergoes hot deformation.This mechanism promotes DRX granule formation and permits complete recrystallization.Ultimately,the fusion structure was identified as playing a catalytic role in the dynamic recrystallization process of the new Ni-Co superalloy.

Selective leaching of calcium from mechanically activated mixed rare earth concentrate

The loss of rare earths(REs)takes place during the pre-decalcification process of mixed rare earth concentrate.In an effort to reduce such RE loss,a novel idea to improve the leaching selectivity of Ca to REs by applying selective mechanical activation was proposed.First,regarding the key minerals affecting the leaching selectivity of Ca to REs,the differences in the mechanical activation behaviors of CaF_(2) and REFCO_(3) were studied,and we find that the lattice strain of CaF_(2) increases from 0.21%to 0.42%,whereas that of REFCO_(3) increases from 0.31%to 0.40%.Notably,CaF_(2) demonstrates a larger lattice strain than REFCO_(3),indicating greater mechanical activation energy storage and higher leaching activity.Next,the HCl leaching process was studied.A significant leaching selectivity of Ca to REs,from 21.6 to 35.1,is achieved through mechanical activation.The Ca leaching rate reaches 80.7%when the RE loss is 2.3%in the activated sample.This study provides an novel approach for achieving selective extraction of specific components via mechanical activation pretreatment.

Structural evolution and high-temperature sensing performance of polymer-derived SiAlBCN ceramics

In situ temperature monitoring has become extremely imperative in high-temperature harsh environments and polymer-derived ceramics(PDCs)as sensing materials have attracted great attention.However,the stability and oxidation/corrosion resistance of PDCs cannot be simultaneously achieved at the moment,limiting their practical application.Herein,polymer-derived SiAlBCN ceramics were synthesized via polymer conversion method under different pyrolysis temperatures.Their microstructure evolution,high temperature sensing properties,and stability were investigated in detail.The results show that the amorphous SiAlBCN phase grows more orderly and the size of the free carbon phase enlarges with the increasing temperature.The defect concentration displays a decreasing tendency.Concurrently,the SiAlBCN ceramics as sensing materials exhibit a good temperature-resistance property from roo temperature to 1100℃.The fabricated SiAlBCN temperature sensor possesses excellent stability,repeatability,and accuracy.Moreover,SiAlBCN ceramics exhibit distinguished oxidation/corrosion resistance after 100 h treatment at 1200℃in a water/oxygen environment,which is attributed to their low corrosive rate constant(0.57 mg/(cm^(2)·h))and oxidative rate constant(3.43 mg^(2)/(cm^(4)·h)).Therefore,polymer-derived SiAlBCN ceramics as sensing materials,which possess outstanding stability and oxidation/corrosion resistance,have great potential for in-situ monitoring of extreme environmental temperatures in the future.