Lithium-ion batteries (LIBs) provide the largest source of electrical energy storage today. This paper covers the use of comminution processes and, thus, crushers and mills for particle breakage and dispersing, as well as classifiers for particle separation within the process chain, from the raw material to the final lithium battery cell and its recycling at end of life. First of all, the raw materials for the active material production have to be produced either by processing primary raw materials, or by recycling the spent lithium batteries. The end-of-life battery cells have to be shredded, the materials separated and then milled in order to achieve the so-called black mass, which provides a secondary material source with very valuable components. Using these materials for the synthesis of the cathode active materials, milling has to be applied in different stages. The natural graphite, increasingly used as anode material, has to be designed in mills and classifiers for achieving targeted properties. Nanosized silicon is produced by nanomilling using stirred media mills as a primary option. Conductive additives for LIBs, like carbon black, have to be dispersed in a solvent with machines like planetary mixers, extruders or stirred media mills. In the future, mechanochemical synthesis of solid electrolytes will especially require additional application of comminution processes.

It is well known that the functionality of inorganic materials strongly depends on the chemical composition, morphology, particle size, crystal facet, etc., which are strongly influenced by the synthesis process. The precise control of the synthesis process is expected to lead to the discovery of new functionality and improvement of the functionality of materials. For example, in a high-temperature solid-phase reaction, it is difficult to control the morphology of nanocrystals. On the other hand, synthesizing functional materials using solution processes, such as hydrothermal and solvothermal reactions, makes it possible to control the morphology and particle size precisely. Usually, the solution process is strongly related to the dissolution reprecipitation mechanism. Therefore, the material composition can be strictly controlled and is suitable for forming fine particles with high crystallinity. In this review paper, the role of the solvent in the solution process, its effect on particle size and morphology of the transition metal oxide, and the related functional improvement will be focused. Furthermore, the direct formation of functional thin films by the solution process and the morphology control by non-oxide materials by the topotactic reaction will also be introduced.

It is well established that the critical performance metrics for aerosol products are aerodynamic particle size distribution (APSD) and delivered dose uniformity (DDU). In broad terms, these performance characteristics dictate the efficiency and reproducibility with which an aerosol is administered clinically. However, these properties alone do not support in-vitro, in-vivo correlations. There have been numerous publications attempting to more directly link product performance testing to physiological relevance or further to draw direct correlations of relevance to bioequivalence testing for the development of generic products. While these novel methods have been employed in product development activity, their suitability for compendial testing has yet to be established. This paper explores the potential to establish biologically relevant compendial standards for dry powder inhaler products while maintaining accuracy and reproducibility of data collected to support the quality and performance of the product.

Higher performance is constantly required in rare earth permanent magnets, which are an indispensable component of the motors of electric vehicles. When producing sintered magnets, advanced structural control is necessary in the powder metallurgy process in order to achieve high performance. Especially in recent years, it has become important to develop processes for Sm-Fe-N magnets and metastable phase magnets as next-generation magnets to replace the Nd-Fe-B magnets. Because the crystal grain refinement of sintered magnets is most effective for improving coercivity, production methods for raw powders have evolved from the traditional pulverization to chemical synthesis approaches, and as a result, a submicron-sized Sm-Fe-N powder with huge coercivity has been developed. State-of-the-art physical synthesis methods have also been applied successfully to the synthesis of nanopowders. Since control of the grain boundary is very effective in Nd-Fe-B magnets, this approach has also been evolved to Sm-Fe-N magnets by nano coating. On the other hand, since technologies for crystalline orientation control and high-density sintering are indispensable for improvement of remanence, new low-thermal load consolidation techniques such as spark plasma sintering are being developed for Sm-Fe-N magnets and metastable phase magnets in order to overcome the inherent low thermal stability of these materials.

Spray drying is gaining traction in the pharmaceutical industry as one of the processing methods of choice for the manufacture of solid dosage forms intended for pulmonary, oral, and parenteral delivery. This process is particularly advantageous because of its ability to produce engineered particles with improved efficacy and stability by combining active pharmaceutical ingredients or biologics with appropriate excipients. Moreover, due to its high throughput, continuous operation, and ability to produce thermostable solid powders, spray drying can be a manufacturing method of choice in the production of drugs and other formulations, including vaccines, for global distribution. Formulation design based on a mechanistic understanding of the different phenomena that occur during the spray drying of powders is complicated and can therefore make the use of available particle formation models difficult for the practitioner. This review aims to provide step-by-step guidance accompanied by critical background information for the successful formulation design of spray-dried microparticles. These include discussion of the tools needed to estimate the surface concentration of each solute during droplet drying, their times and modes of solidification, and the amount of glass stabilizers and shell formers required to produce stable and dispersible powders.

Li-ion batteries with “nickel” as the main material or the highest ratio material on the cathode or anode electrode have attracted considerable attention. Nickel has high strength and corrosion resistance. Nickel has also been utilized successfully as the cathode and anode materials. The specific capacity and energy and power density of the material increased with increasing nickel content. However, several problems have limited the use of nickel-based Li-ion batteries. Problems such as cation mixing, the properties of nickel, and highly Ni-rich compounds leading to side reactions, influence the electrochemical performance of Li-ion batteries. The morphology is another factor affecting the electrochemical performance. Further studies will be needed to synthesize materials with the desired morphology and determine how the morphology affects the electrochemical performance. In a morphological perspective, extensive morphological adjustments are a pathway to a long and stable life cycle. In this light, nickel-based electrodes are manufactured continuously and will always be considered for next-generation secondary energy storage. The morphology of nickel-based active materials is one of the main factors determining the high-performance of Li-ion batteries.

While the formulation of pharmaceuticals as liquids is common practice, powders are associated with enhanced stability, avoidance of the cold chain, lower dosing requirements, and more convenient administration. These are particularly critical for proteins, as they are expensive and complicated to manufacture. Powders also have improved aerosol properties for pulmonary delivery. Conventional techniques for formulating powders include spray-drying, shelf freeze-drying, spray freeze-drying, and spray freezing into liquid, but they produce powders with poor aerosol performance and/or activity due to suboptimal powder properties. Thin-film freezing (TFF) is a new cryogenic technique that can engineer highly porous, brittle, powder matrices with excellent aerosol performance properties and stability. Herein, we describe TFF in comparison to other cryogenic techniques. Physical properties of TFF powders such as morphology, moisture sorption, stability, solubility, and dissolution, as well as aerosol properties are discussed. In addition, factors that significantly affect the physical and aerosol properties of dry powders prepared by TFF, such as solids content, drug loading, solvent system, excipient, and dry powder delivery device, are analyzed. Finally, we provide evidence supporting the applicability of using TFF to prepare dry powder formulations of protein-based pharmaceuticals, enabling their cold chain-free storage as well as efficient pulmonary delivery.

Particle breakage occurs in comminution machines and, inadvertently, in other process equipment during handling as well as in geotechnical applications. For nearly a century, researchers have developed mathematical expressions to describe single-particle breakage having different levels of complexity and abilities to represent it. The work presents and analyses critically a breakage model that has been found to be suitable to describe breakage of brittle materials in association to the discrete element method, either embedded in it as part of particle replacement schemes or coupled to it in microscale population balance models. The energy-based model accounts for variability and size-dependency of fracture energy of particles, weakening when particles are stressed below this value, as well as energy and size-dependent fragment size distributions when particles are stressed beyond it, discriminating between surface and body breakage. The work then further validates the model on the basis of extensive data from impact load cell and drop weight tests. Finally, a discussion of challenges associated to fitting its parameters and on applications is presented.

Microspheres composed of poly (lactic-co-glycolic acid) (PLGA) were formed in liquid droplets using the electrospray technique. The structure of the microspheres was controlled by changing the electric voltage of the electrospray. PLGA microspheres with porous structures and micro-sized nanocomposite particles comprising PLGA nanosphere aggregates were formed at 5.0–7.0 kV and 2.5–3.5 kV, respectively. The structural change was related to the extent of evaporation of the solvent from the droplets during their flight. When the evaporation was completed in the relatively small droplets, the microspheres with porous structures were formed in the droplets. To study the mechanism, we observed the effects of the electric voltage of the electrospray, PLGA concentration, flight distance of the droplets, and molecular weight of PLGA on the structure of the PLGA particles. The novelty of this study is the analysis of the size and structure of the PLGA microparticles, which were controlled by the electrospray technique. Therefore, this research has important implications for the structural design and preparation of nanocomposite particles.

A workflow for developing a multidimensional, linear correlation between the process conditions during fluidized bed spray granulation and the surface morphology of the resulting granules is presented. Spray coating experiments with Cellets^®500 particles and sodium benzoate solution were performed in a lab-scale fluidized bed varying liquid spray rate, fluidization air flow rate, fluidization air temperature, spray air temperature and spray atomization pressure. To characterize the surface structure, the surface roughness of the coated particles was quantified using confocal laser-scanning microscopy. The roughness was correlated to the process conditions, and the resulting correlation was rigorously analyzed for the importance and co-linearities of the individual process parameters using a principal component analysis. The surface roughness is strongly dependent on the spray rate of the coating solution, the fluidization air temperature and the atomization pressure at the nozzle. In general, wet process conditions and large droplets with a low initial velocity favor the formation of particles with a rough surface structure, while dry conditions and fine droplets with a high velocity result in granules with a smooth and compact coating layer.

Gold nanoparticles (AuNPs) exhibit unique size-dependent physiochemical properties that make them attractive for a wide range of applications. However, the large-scale availability of precision AuNPs has been minimal. Not only must the required nanoparticles be of precise size and morphology, but they must also be of exceedingly narrow size distribution to yield accurate and reliable performance. The present study aims to synthesize precision AuNPs and to assess the advantages and limitations of the Turkevich method—one of the common chemical synthesis technique. Colloidal AuNPs from 15 nm to 50 nm in diameter were synthesized using the Turkevich method. The effect of the molar ratio of the reagent mixture (trisodium citrate to gold chloride), the scaled-up batch size, the initial gold chloride concentration, and the reaction temperature was studied. The morphology, optical property, surface chemistry, and chemical composition of AuNPs were thoroughly characterized. It was determined that the as-synthesized AuNPs between 15 nm and 30 nm exhibit well-defined size and shape, and narrow size distribution (PDI < 0.20). However, the AuNPs became more polydispersed and less spherical in shape as the particle size increased.

Inertial impactors are applied widely to classify particulate matters (PMs) and nanoparticles (NPs) with desired aerodynamic diameters for further analyses due to their sharp cutoff characteristics, simple design, easy operation, and high collection ability. A few hundred papers have been published since the 1860s that addressed the characteristics and applications of the inertial impactors. In the last 30 years, our group has also carried out lots of studies to contribute to the design and the improvement of inertial impactors. With our understanding of inertial impactors, this article reviews previous studies of some typical types of the inertial impactors including conventional impactors, cascade impactors, and virtual impactors and the parameters for design consideration of these devices. The article also reviews some applications of the inertial impactors, which are mass concentration measurement, mass and number distribution measurement, personal exposure measurement, particulate matter control, and powder classification. The synthesized knowledge of the inertial impactor in this study can help researchers to design an inertial impactor with an accurate cutoff diameter, a sharp collection efficiency curve, and no particle bounce and particle overloading effects for long-term use for PM classification and control purposes.

The Calcium-Looping (CaL) process has emerged in the last years as a promising technology to face two key challenges within the future energy scenario: energy storage in renewable energy-based plants and CO₂ capture from fossil fuel combustion. Based on the multicycle calcination-carbonation reaction of CaCO₃ for both thermochemical energy storage and post-combustion CO₂ capture applications, the operating conditions for each application may involve remarkably different characteristics regarding kinetics, heat transfer and material multicycle activity performance. The novelty and urgency of developing these applications demand an important effort to overcome serious issues, most of them related to gas-solids reactions and material handling. This work reviews the latest results from international research projects including a critical assessment of the technology needed to scale up the process. A set of equipment and methods already proved as well as those requiring further demonstration are discussed. An emphasis is put on critical equipment such as gas-solids reactors for both calcination and carbonation, power block integration, gas and solids conveying systems and auxiliary equipment for both energy storage and CO₂ capture CaL applications.

The properties of particle ensembles are defined by a complex multidimensional parameter space, namely particle size, shape, surface, structure, composition and their distributions. Macroscopic product properties are a direct result of these disperse particle properties. Therefore, the comprehensive multidimensional characterization of particle ensembles is a key task in any product design. However, the determination of complex property distributions is major challenge. We provide a broad overview of the current tools for multidimensional particle characterization. First, the mathematical handling of multidimensional (nD) property distribution is outlined as a necessary framework for the correct handling of nD particle size distributions (PSDs). Then, well-established techniques as well as recent developments with the potential to extract nD property distributions are reviewed. Ex situ imaging techniques like electron tomography or Raman spectroscopy with AFM co-localization, for instance, provide a resolution on the level of single particles but are limited in terms of sample statistics. A particular focus lies therefore on methods in the gas and the liquid phase, which provide multidimensional particle properties either directly or by a combination of one-dimensional techniques.

The discrete element method (DEM) and the moving particle semi-implicit (MPS) method are the most popular mesh-free particle methods in the discontinuum and continuum. This paper describes a state-of-the-art modeling on multi-phase flows using these mesh-free particle methods. Herein, a combinational model of the signed distance function (SDF) and immersed boundary method (IBM) is introduced for an arbitrary-shaped wall boundary in the DEM simulation. Practically, this model uses a simple operation to create the wall boundary. Although the SDF is a scalar field for the wall boundary of the DEM, it is useful for the wall boundary of the CFD through combination with the IBM. Validation tests are carried out to demonstrate the adequacy of the SDF/IBM wall boundary model. Regarding the mesh-free particle method for continuum, the phase change problem is one of the challenging topics, as the solid state is usually modeled by extremely high viscous fluid in the phase change simulation. The phase change simulation is shown to be efficiently performed through an implicit algorithm and a heat flux model in the MPS method. The adequacy of these models is verified by the numerical examples.

Powder processing and manufacturing operations are rate processes for which the bottleneck is cohesive powder flow. Diversity of material properties, particulate form, and sensitivity to environmental conditions, such as humidity and tribo-electric charging, make its prediction very challenging. However, this is highly desirable particularly when addressing a powder material for which only a small quantity is available. Furthermore, in a number of applications powder flow testing at low stress levels is highly desirable.

Characterisation of bulk powder failure for flow initiation (quasi-static) is well established. However, bulk flow parameters are all sensitive to strain rate with which the powder is sheared, but in contrast to quasi-static test methods, there is no shear cell for characterisation of the bulk parameters in the dynamic regime. There are only a handful of instruments available for powder rheometry, in which the bulk resistance to motion can be quantified as a function of the shear strain rate, but the challenge is relating the bulk behaviour to the physical and mechanical properties of constituting particles. A critique of the current state of the art in characterisation and analysis of cohesive powder flow is presented, addressing the effects of cohesion, strain rate, fluid medium drag and particle shape.

Immunization can be traced back to classical China. Modern immunization reduces the risk of infection by attenuating or killing the pathogen or using non-infectious antigens to elicit the immune response. The challenge of immunization is to raise a robust protective response without infecting the individual or overstimulating the immune response, and this can be achieved by using nanoparticle delivery systems to specifically target the innate immune system with known antigens and where necessary include an adjuvant to enhance the efficacy. These systems can be targeted to mucosal sites that are located throughout the body with the nasal and pulmonary routes of administration allowing ease of access. Macrophages are the first line of defense of the innate immune system and are the host cell for primary intracellular infection by several respiratory pathogens notably mycobacteria and streptococci. The breadth of nanoparticle technology available to deliver vaccines has been explored and consideration of its value in nasal and pulmonary delivery is addressed specifically.

Circulating fluidized beds (CFB)s are important technical equipment to treat gas–solid systems for fluid catalytic cracking, combustion, gasification, and high-temperature heat receiving because their mass and heat transfer rates are large. Cyclones are important devices to control the performance of CFBs and ensure their stable operation; heat-carrying and/or solid catalyst particles being circulated in a CFB should be efficiently separated from gas at a reduced pressure loss during separation. In commercial CFBs, a large amount of solids (> 1 kg-solid (m³-gas)^–1 or > 1 kg-solid (kg-gas)^–1) is circulated and should be treated. Thus, gas–solid cyclones with a high solids loading should be developed. A large number of reports have been published on gas–solid separators, including cyclones. In addition, computational fluid dynamics (CFD) technology has rapidly developed in the past decade. Based on these observations, in this review, we summarize the recent progress in experimental and CFD studies on gas–solid cyclones. The modified pressure drop model, scale-up methodology, and criteria for a single large cyclone vs. multiple cyclones are explained. Future research perspectives are also discussed.

The growing population and economic development globally has led to increasing resource consumption and waste generation. This has generated concern at local, national and international levels on environmental issues including air quality, resource scarcity, waste management (including plastics) and global warming. The resulting antipathy towards fossil fuels and waste landfilling has spurred the demand for alternative bioenergy and biofuels production methods, making use of abundant biomass and waste feedstock. Although not new concepts, there has been renewed impetus recently to develop advanced thermochemical processes such as pyrolysis and gasification to treat biomass and municipal solid waste (including refuse-derived fuel therefrom). This is because these processes have the potential to add value to cheap and abundant materials by converting them into advanced biofuels and chemicals. The work presented in this paper is concerned principally with the technical analysis and review of new-generation, state-of-the-art systems based on fluidised bed reactors operated with biomass and solid waste. A comprehensive assessment of fluidised bed reactor types and operations is considered, with particular attention given to those processes aimed at the production of clean syngas for the subsequent synthesis of high-value products, including bio-hydrogen, synthetic natural gas (SNG), and liquid fuels.

Multiple industrial applications, including pharmaceuticals, rely on the processing of powders. The current powder characterization framework is fragmented into two general areas. One deals with understanding powders from the standpoint of its constituting agents—particles. The other deals with understanding based on the bulk— the collective behavior of particles. While complementary, the two aspects provide distinct pieces of information. Whenever possible, experimental techniques should be used to predict powder behavior. However, it is equally important to recognize that because of the natural complexity of powders, existing predictive approaches will continue to be of limited success for predicting the collective behavior of particles. This article discusses the understanding of powder properties from two perspectives. One is the effect of surface energy at the bulk level (large collections of particles), which controls interactions between powders. This aspect is most useful if studied at the bulk-powder level, not at the single-particle level. Another perspective deals with the physico-mechanical properties of individual particles, responsible for the observed behavior of powders when subjected to mechanical stress from unit operations such as milling. This aspect, which controls the failure mechanism of powders subjected to milling, is most useful if assessed at the single-particle, not at the bulk level. Therefore, in order to fully understand, and eventually predict, or at least effectively model powder behavior, a good-judgement-based combination of microscopic and bulk-level analytical methods is necessary.