Particle Recycling Research Articles

An Environmentally Friendly Technology of Metal Fiber Bag Filter to Purify Dust-Laden Airflow

Over the past decades, China has suffered from negative environmental impacts from distempered dust-laden airflow-purification activities. After a decade of effort, dust-laden airflow purification and powder particle recycling have been realized in specialized companies in China, and law enforcement for illegal activities of dust-laden airflow discharge has also been made increasingly strict. Thus, up to now, dust-laden airflow purification in China should be developed toward being more in-depth and refined to promote industrial applications of dust-laden airflow purification. This article reviews the status of existing technologies for dust-laden airflow purification. A novel and environmentally friendly technology for purifying the dust-laden airflow is proposed which uses a metal bag filter to collect dust particles. The bottlenecks in the dust-laden airflow-purification system are analyzed. Some preliminary experiments of pinch technologies are also conducted. Finally, in order to provide directional guidance for the future development of metal bag filters, some key points regarding the metal bag filter purification system are proposed to point towards a future trend in dust-laden airflow purification.

Investigation of the Mechanical Properties of Vinylester-Based Sheet Moulding Compound (SMC) Subject to Particle Recycling

In light of climate change, fiber-reinforced plastics (FRP) are becoming increasingly important due to their lightweight construction potential. This benefit is additionally expanded on with the low cycle times, scrap rates and material costs of Sheet Moulding Compounds (SMC), making it the most often used material on the FRP market. While extensive studies regarding the recycling of SMC with unsaturated polyester-based matrices (UP-SMC) have been conducted in the past, this is not the case for vinylester-based SMC (VE-SMC). In this research, VE-SMC components were subject to a particle-recycling approach. Recyclate in the form of VE-SMC regrind was used to substitute SMC matrices during the compounding process. The dependence of the mechanical properties and failure behavior of VE-SMC containing regrind was investigated by means of microscopic and mechanical test methods for varying mass proportions of SMC regrind. Due to the addition of SMC regrind, a decreased fiber/matrix adhesion was observed. Furthermore, an increase in pore formation was observed with an increasing proportion of SMC regrind. The flexural modulus increased by 20% with a low percentage of regrind (ωrSMC = 10 wt.%) in comparison to virgin SMC. In contrast, the tensile properties decrease (up to 30%) with the addition of SMC regrind independent of the investigated proportions of SMC regrind.

Tracking dynamic interaction between therapeutic vesicles and endocytic structures

During clathrin-mediated endocytosis (CME), receptors and their cargo are internalized, a required step in signalling cascades, receptor recycling, and entry of viruses and other small particles into the cell. It is commonly assumed that most engineered, drug-loaded vesicles enter the cell via CME, and many are conjugated with ligands to receptors that are targets of CME. In parallel, live-cell microscopy has been used to study the growth and development of endocytic pits, revealing their molecular-level mechanisms of assembly and detailed dynamics.

Nonlinear burn control in ITER using adaptive allocation of actuators with uncertain dynamics

ITER will be the first tokamak to sustain a fusion-producing, or burning, plasma. If the plasma temperature were to inadvertently rise in this burning regime, the positive correlation between temperature and the fusion reaction rate would establish a destabilizing positive feedback loop. Careful regulation of the plasma’s temperature and density, or burn control, is required to prevent these potentially reactor-damaging thermal excursions, neutralize disturbances and improve performance. In this work, a Lyapunov-based burn controller is designed using a full zero-dimensional nonlinear model. An adaptive estimator manages destabilizing uncertainties in the plasma confinement properties and the particle recycling conditions (caused by plasma–wall interactions). The controller regulates the plasma density with requests for deuterium and tritium particle injections. In ITER-like plasmas, the fusion-born alpha particles will primarily heat the plasma electrons, resulting in different electron and ion temperatures in the core. By considering separate response models for the electron and ion energies, the proposed controller can independently regulate the electron and ion temperatures by requesting that different amounts of auxiliary power be delivered to the electrons and ions. These two commands for a specific control effort (electron and ion heating) are sent to an actuator allocation module that optimally maps them to the heating actuators available to ITER: an electron cyclotron heating system (20 MW), an ion cyclotron heating system (20 MW), and two neutral beam injectors (16.5 MW each). Two different actuator allocators are presented in this work. The first actuator allocator finds the optimal mapping by solving a convex quadratic program that includes actuator saturation and rate limits. It is nonadaptive and assumes that the mapping between the commanded control efforts and the allocated actuators (i.e. the effector model) contains no uncertainties. The second actuator allocation module has an adaptive estimator to handle uncertainties in the effector model. This uncertainty includes actuator efficiencies, the fractions of neutral beam heating that are deposited into the plasma electrons and ions, and the tritium concentration of the fueling pellets. Furthermore, the adaptive allocator considers actuator dynamics (actuation lag) that contain uncertainty. This adaptive allocation algorithm is more computationally efficient than the aforementioned nonadaptive allocator because it is computed using dynamic update laws so that finding the solution to a static optimization problem is not required at every time step. A simulation study assesses the performance of the proposed adaptive burn controller augmented with each of the actuator allocation modules.

On fusion chain reactions in 11B targets for laser driven aneutronic fusion

The work presented in this letter suggests that it is possible to enhance the yield in laser driven aneutronic fusion devices by fusion chain reactions. This mechanism will be described using the example of aneutronic fusion between an incoming high-energy proton beam and a 11B target. Such fusion reactions create alphas that can again fuse with a 11B particle in a dense solid state target. An improved target design will be shown that enhances the recycling of fast alpha particles that are created from fusion reactions. It will also be argued that such alpha recycling may have already been observed in experiments, although it was attributed to another, more complex physical mechanism.

On the dynamics of stratified particle-laden plumes

An experimental study on stratified particle-laden plumes is presented and five steady-state flow regimes have been identified. The steady-state behaviour of the plume is directly related to the magnitude of the convective velocity associated with particle-induced instabilities, $U_c$ , in relation to the terminal settling velocity of each individual particle, $u_{st}$ . When $u_{st}>U_c$ , the ratio of particle to fluid buoyancy flux at the source, $P$ , becomes important. For $P<0.2$ , the plume dynamics appears very similar to a single-phase plume as particle recycling has minimal impact on the steady-state plume height. When $P>0.2$ , the plume height decreases significantly, creating an anvil-shaped intrusion similar to those associated with explosive volcanic eruptions. Importantly, the measured steady-state heights of plumes within this settling regime validate the collapse model of Apsley & Lane-Serff (J. Fluid Mech., vol. 865, 2019, pp. 904–927). When $u_{st}\leqslant U_c$ , particle re-entrainment behaviour changes significantly and the plume dynamics becomes independent of $P$ . When $u_{st}\approx U_c$ , a trough of fluid becomes present in the sedimenting veil due to a significant flux of descending particles at the edge of the plume. Once $u_{st}< U_c$ , the particles spreading in the intrusion become confined to a defined radius around the plume due to the significant ambient convection occurring beneath the current. For $u_{st}\ll U_c$ , or in the case of these experiments, when $U_c\geqslant 1\ \text{cm s}^{-1}$ , ambient convection becomes so strong that intrusion fluid is pulled down to the plume source, creating a flow reminiscent of a stratified fountain with secondary intrusions developing between the original current and the tank floor. Through an extension of the work of Cardoso & Zarrebini (Chem. Engng Sci., vol. 56, issue 11, 2001a, pp. 3365–3375), an analytical expression is developed to determine the onset of convection in the environment beyond the edge of the plume, which for a known particle settling velocity, can be used to characterise a plume's expected settling regime. In all plume regimes, the intrusion fluid is observed to rise in the environment following the sedimentation of particles and a simple model for the change in intrusion fluid height has been developed using the steady-state particle concentration at the spreading level.

Separation of cathode particles and aluminum current foil in lithium-ion battery by high-voltage pulsed discharge Part II: Prospective life cycle assessment based on experimental data.

This series of papers addresses the recycling of cathode particles and aluminum (Al) foil from positive electrode sheet (PE sheet) dismantled from spent lithium-ion batteries (LIBs) by applying a high-voltage pulsed discharge. As concluded in Part I of the series (Tokoro et al., 2021), cathode particles and Al foil were separated in water based on a single pulsed power application. This separation of LIB components by pulsed discharge was examined by means of prospective life cycle assessment and is expected to have applications in LIB reuse and recycling. The indicators selected were life cycle greenhouse gas (LC-GHG) emissions and life cycle resource consumption potential (LC-RCP). We first completed supplementary experiments to collect redundant data under several scale-up circumstances, and then attempted to quantify the uncertainties from scaling up and progress made in battery technology. When the batch scale of pulsed discharge separation is sufficiently large, the recovery of cathode particles and Al foil from PE sheet by pulsed discharge can reduce both LC-GHG and LC-RCP, in contrast to conventional recycling with roasting processes. Due to technology developments in LIB cathodes, the reuse of positive electrode active materials (PEAM) does not always have lower environmental impacts than the recycling of the raw materials of PEAM in the manufacturing of new LIB cathodes. This study achieved a proof of concept for resource consumption reduction induced by cathode utilization, considering LC-GHG and LC-RCP, by applying high-voltage pulsed discharge separation.

Agglomeration behaviour of magnetic microparticles during separation and recycling processes in mRNA purification.

Purification of mRNA with oligo(dT)‐functionalized magnetic particles involves a series of magnetic separations for buffer exchange and washing. Magnetic particles interact and agglomerate with each other when a magnetic field is applied, which can result in a decreased total surface area and thus a decreased yield of mRNA. In addition, agglomeration may also be caused by mRNA loading on the magnetic particles. Therefore, it is of interest how the individual steps of magnetic separation and subsequent redispersion in the buffers used affect the particle size distribution. The lysis/binding buffer is the most important buffer for the separation of mRNA from the multicomponent suspension of cell lysate. Therefore, monodisperse magnetic particles loaded with mRNA were dispersed in the lysis/binding buffer and in the reference system deionized water, and the particle size distributions were measured. A concentration‐dependent agglomeration tendency was observed in deionized water. In contrast, no significant agglomeration was detected in the lysis/binding buffer. With regard to magnetic particle recycling, the influence of different storage and drying processes on particle size distribution was investigated. Agglomeration occurred in all process alternatives. For de‐agglomeration, ultrasonic treatment was examined. It represents a suitable method for reproducible restoration of the original particle size distribution.

Agglomerate processing and recycling options in magnetic seeded filtration

In magnetic seeded filtration, a hetero-agglomeration between non-magnetic target and magnetic seed particles is induced and the agglomerates are subsequently removed by magnetic separation. The necessary addition of magnetic material constitutes the main criticism of the process. In this study, three different agglomerate processing and seed particle recycling strategies were tested experimentally: Thermal breakup, in which the non-magnetic fraction is decomposed at elevated temperatures, chemical breakup, where non-magnetic particles are dissolved in a solvent and lastly mechanical breakup, in which agglomerates are broken under stress. All approaches were investigated in a cyclical manner to disclose eventual long-term effects. Generally, all approaches showed high recycling rates of magnetic seed particles resulting in consistently high separation efficiencies throughout the experimental cycles. Where applicable, the non-magnetic fraction was also recovered at high rates. This work proofs general feasibility of all three recycling approaches, while also discussing the respective benefits, limitations and possible applications.

Measurement-Based Modelling of Material Moisture and Particle Classification for Control of Copper Ore Dry Grinding Process.

Moisture of bulk material has a significant impact on energetic efficiency of dry grinding, resultant particle size distribution and particle shape, and conditions of powder transport. As a consequence, moisture needs to be measured or estimated (modelled) in many points. This research investigates mutual relations between material moisture and particle classification process in a grinding installation. The experimental setup involves an inertial-impingement classifier and cyclone being part of dry grinding circuit with electromagnetic mill and recycle of coarse particles. The tested granular material is copper ore of particle size 0–1.25 mm and relative moisture content 0.5–5%, fed to the installation at various rates. Higher moisture of input material is found to change the operation of the classifier. Computed correlation coefficients show increased content of fine particles in lower product of classification. Additionally, drying of lower and upper classification products with respect to moisture of input material is modelled. Straight line models with and without saturation are estimated with recursive least squares method accounting for measurement errors in both predictor and response variables. These simple models are intended for use in automatic control system of the grinding installation.

Analysis and Discussion on Burning Low Calorific Value Fuel of Circulating Fluidized Bed Boiler

China's coal-dominated energy structure will not change in a short time. In order to implement the relevant national policies on energy conservation and emission reduction, it is a good response to adopt circulating fluidized bed boilers in coal-fired power stations. Circulating fluidized bed boiler adopts fluidized combustion, which has high reliability and high utilization rate because of its special combustion mode and particle recycling device. For the low calorific value inferior fuel which is difficult to burn in common boiler, CFB boiler also has certain adaptability and compatibility. In this background, this article with coal gangue as the representative of the inferior coal are discussed its application in the circulating fluidized bed boiler, the combustion process, boiler equipment and special fly ash produced by combustion is proposed that often appear in the three aspects of problems, and accordingly put forward the solution and optimization measures, provides reference for the actual process.

Liquid metal “divertorlets” concept for fusion reactors

Abstract A new, novel approach to liquid metal plasma facing components called “divertorlets” is presented and accompanied by experiments, simulations, and analysis. The development of a robust and reliable plasma facing component at the divertor is ongoing, with liquid metal divertor concepts gaining interest by showing promise for being able to handle higher heat fluxes as well as improve plasma performance through a reduction in particle recycling. The presented design in this work seeks to address challenges associated with evaporation, operation power, and liquid metal inventory. Divertorlets utilize many adjacent narrow channels with alternating vertical velocity that maintain large flow rates with small velocities at the surface by minimizing the flow path length. Preliminary results using a test stand on LMX-U at PPPL and simulations in COMSOL demonstrate the successful operation and the potential for divertorlets to remove large heat fluxes, with projections made to reactor scale showing the expected system performance.

Deuterium retention characteristics in Li film by coating and during flowing liquid Li limiter operation in experimental advanced superconducting tokamak

Lithium (Li) is a promising low-Z material for particle recycling and impurity control to improve plasma performance in fusion devices. In the experimental advanced superconducting tokamak (EAST), Li coating has become a routine method for wall conditioning, and a flowing liquid Li (FLiLi) limiter has been successfully tested several times. Deuterium retention characteristics in the Li film coated on the international thermonuclear experimental reactor-like tungsten divertor and FLiLi during plasma discharges, which is important for the utilization of Li in future fusion devices, were investigated in EAST. It is found that the absorption of the fuel particles by Li coatings decreases gradually, and recycling gradually increases over a series of discharges. The maximum net amount of deuterium retained reached ∼0.8 g, corresponding to 12% deuterium in the Li. This corresponds to a whole day’s worth of shots with a total of 87 plasma discharges and a total of ∼640s plasma time after 11.75 g Li was deposited. Compared to the Li coating, it is shown that FLiLi continuously traps fuel particles and achieves a higher deuterium retention ratio over both the short- and long-term, leading to lower recycling. Meanwhile, it is also observed that the fuel particle retention ratio increases when FLiLi is closer to the plasma. This result is likely due to higher plasma heating power and limiter temperature, which cause an increased Li efflux from FLiLi due to a higher limiter temperature, which then redeposits on the other plasma-facing surfaces and increases fuel particle absorption. It is estimated that ⩾80% of the retained D particles are captured by the continual renewal of the Li redeposition film during the FLiLi operation. This investigation would also be useful for D/T retention in future fusion devices if Li is used as a plasma-facing component.

Interfacing CdS particles on Ni foam as a three-dimensional monolithic photocatalyst for efficient visible-light-driven H2 evolution

Solar photocatalytic water splitting using particulate semiconductors has been valued as a potentially scalable way for the production of clean H2 energy, yet the performances of the powder-suspension systems are constrained by insufficient utilization of light energy and tedious recycling of photocatalyst particles. Here, we present a high-performance photocatalytic H2 evolution using a visible-light-driven CdS-based monolithic photocatalyst with three-dimensional (3D) heterostructure. The monolithic photocatalyst is fabricated by firmly growing CdS microspheres on a Ni(OH)2 nanosheet-modified Ni foam (NF) (denoted as CdS-NiSx/NF) via a simple hydrothermal process. The structure and component synergy endows the monolithic CdS-NiSx/NF photocatalyst advantageous features including high-density CdS microspheres for visible light harvesting, multiple heterojunction interfaces for efficient electron-hole separation, and abundant interfacial NiSx active sites for efficient H2 evolution reaction (HER). Upon visible light irradiation, the monolithic CdS-NiSx/NF photocatalyst exhibits an outstanding photocatalytic H2 evolution activity with an enhanced rate of 6.2 mmol·h−1 g−1CdS, which is 6 times higher than that of the suspended CdS powder. In addition, the structural integrity of the CdS-NiSx/NF enables a good stability for H2 evolution over a 30 h reaction. This monolithic photocatalyst is scalable in preparation and compatible for device fabrication, which offers great potentials for applications in solar cells, photoelectrocatalysis, and electrocatalysis.

Study on The Effect of Compaction Work on The Unloaded Expansion Rate of Expansive Soil

In order to reduce the impact of expansive soil on the project and realize the recycling and utilization of waste plastic particles, EPS particles with different compaction work were mixed into the expansive soil for no-load expansion rate test. The results showed that the improvement effect of EPS particles with less compaction power was better than that of EPS particles with more compaction power. The reason is that EPS particles with less compaction work can provide more deformation space for expansive soil. When the content of EPS is between 5% and 15%, the no-load expansion rate decreases linearly with the increase of the content of EPS.

Loop seals in circulating fluidized beds – Review and parametric studies using CPFD simulation

Loop seal is a robust particle recycling technique used in circulating fluidized bed (CFB) reactors. The rate and the location of the loop seal aeration exert a significant impact on the rate of particle circulation (GS). The standpipe balances the cumulative pressure drop across the rest of the CFB by adjusting its particle height or gas-particle slip velocity. Higher fraction of the loop seal aeration naturally flows down to riser. Increased pressure drop in the standpipe results in high rate of particle circulation.Computational-particle-fluid-dynamic (CPFD) code is customized for multiphase flow modelling. The inbuilt tool of “BC connectors” was incorporated to downsize a CFB into a loop seal. The simulation results of GS and system pressures for loop seal showed a perfect match with experimentally validated CFB model. A parametric study for the effects of aeration rate, aeration position and length of the horizontal section was performed using the developed CPFD model of the loop seal. GS increased proportionally with the loop seal aeration, reaching an approximate threshold at 0.9 Nm3/h and beyond that GS did not improve significantly. Uniform aeration from the loop seal bottom realized the highest particle circulation with a 71% increment. The length of the horizontal section of the loop seal exhibited an inverse relationship on the particle circulation.

Transport parameters and permeation behavior of hydrogen isotopes in the first wall materials of future fusion reactors

Abstract The first wall of a future magnetic fusion device is essentially defined as the plasma-facing surface of the breeding blankets, which is supposed to be subjected to bi-directional hydrogen isotopes permeation: in one direction by edge plasma-driven permeation (PDP) of deuterium as well as tritium into blankets, and in the other direction by breed tritium gas-driven permeation (GDP) into the edge plasma. Deuterium and tritium PDP will complicate the recovery of tritium from the blanket, while tritium GDP will lead to an unwanted increase of particle recycling in the first wall region, which could even affect core confinement performance. Reduced activation ferritic/martensitic (RAFM) steels are widely proposed as candidate structural materials for the blanket of a DEMO reactor, the surface coatings made of tungsten are necessary to protect the plasma-facing wall from sputtering under high-energy particle bombardment. Therefore, the characterization of hydrogen isotopes transport through a multi-layer W + RAFM wall is of crucial importance to evaluate major reactor design issues including tritium retention, particle recycling and breeding feasibility, etc. This paper is intended to provide a review over the transport parameters of hydrogen isotopes in RAFM steels, including permeability, diffusivity, solubility and surface recombination coefficient. In addition, the present research status of hydrogen isotopes permeation and retention behavior of tungsten coated RAFM steels is briefly introduced.

Magnetically recyclable Sm2Co17/Cu catalyst to chemoselectively reduce the 3-nitrostyrene into 3-vinylaniline under room temperature

Using non-noble metal catalysts to chemoselectively reduce the 3-nitrostyrene into 3-vinylaniline is extremely attractive due to the important applications of aromatic amines. However, the separation and recycle of catalytic particles to sustainably catalyze are still challenging on account of their small size. In this communication, we report a novel magnetically recyclable catalyst of Sm2Co17/Cu to chemoselectively reduce 3-nitrostyrene into 3-vinylaniline by activating ammonia borane (AB) to yield hydrogen. The Sm2Co17/Cu, composited of 180 nm Sm2Co17 nanomagnet and 10 nm Cu catalyst nanoparticles, shows a high conversion (98%) and a high selectivity (99%) for 3-nitrostyrene under ultrasonic concussion. More importantly, they are easily collected by self-separation method without any magnetic field. As a consequence, the excellent recyclable feature is acquired even underwent 10 cycles. Our approach provides a green strategy to synthesize magnetically recyclable catalysts.

Effect of carbon and tungsten plasma-facing materials on the divertor and pedestal plasma in EAST

The edge plasma simulation code SOLPS-ITER is applied to study the effects of plasma-facing materials (PFMs) on the plasma in the EAST device, whose lower carbon (C) divertor will be replaced by tungsten (W) material. The significant difference in particle and energy reflection coefficients between the C and W materials may influence the production and dynamics of the neutral particles in the divertor region, which is characterized by the collisions between the plasma and the recycled neutrals. To separate other effects on the plasma, only the particle and energy recycling of different materials are considered, and no impurity is included. Three PFMs cases, (i) full C PFMs, (ii) W divertor and C main chamber wall (MCW), and (iii) C divertor and W MCW, are simulated. The simulation results show that the PFMs have a remarkable impact on the neutral particles’ recycling, and thus the divertor and pedestal plasma. The C divertor is more capable of enhancing the neutral density in the divertor, and promoting the achievement of the plasma detachment than the W divertor is. However, the PFMs of the MCW have little influence on the divertor plasma. The simulation demonstrates that the C divertor is better than the W divertor from the plasma detachment point of view. In addition, both the divertor and the MCW PFMs have significant roles in the pedestal plasma.

Classification of Black Plastics Waste Using Fluorescence Imaging and Machine Learning

This work contributes to the recycling of technical black plastic particles, for example from the automotive or electronics industries. These plastics cannot yet be sorted with sufficient purity (up to 99.9%), which often makes economical recycling impossible. As a solution to this problem, imaging fluorescence spectroscopy with additional illumination in the near infrared spectral range in combination with classification by machine learning or deep learning classification algorithms is here investigated. The algorithms used are linear discriminant analysis (LDA), k-nearest neighbour classification (kNN), support vector machines (SVM), ensemble models with decision trees (ENSEMBLE), and convolutional neural networks (CNNs). The CNNs in particular attempt to increase overall classification accuracy by taking into account the shape of the plastic particles. In addition, the automatic optimization of the hyperparameters of the classification algorithms by the random search algorithm was investigated. The aim was to increase the accuracy of the classification models. About 400 particles each of 14 plastics from 12 plastic classes were examined. An attempt was made to train an overall model for the classification of all 12 plastics. The CNNs achieved the highest overall classification accuracy with 93.5%. Another attempt was made to classify 41 mixtures of industrially relevant plastics with a maximum of three plastic classes per mixture. The same average classification accuracy of 99.0% was achieved for the ENSEMBLE, SVM, and CNN algorithms. The target overall classification accuracy of 99.9% was achieved for 18 of the 41 compounds. The results show that the method presented is a promising approach for sorting black technical plastic waste.