Triboelektrische Trennung - Eine neue Methode zur Trennung feiner organischer Pulver?

Triboelectric separation is a technique to separate dry powders according to their ability to generate charge. Charge generation occurs due to the contact of and subsequent separation of two surfaces. A physical description of the triboelectric effect is still unknown. For particles flowing through a tube, particle-particle and particle-wall interaction occur. To enhance separation properties of binary powder mixtures charge generation are enlarged by increasing particle-particle interactions, whereas materials of the tube wall do not influence the separation properties.Die triboelektrische Trennung ist eine Methode, um trockene Pulver durch ihre Ladungserzeugung zu trennen. Die Ladungserzeugung erfolgt durch Kontakt und anschließende Trennung zweier Oberflächen. Eine physikalische Beschreibung des triboelektrischen Effekts ist noch nicht bekannt. Bei Partikeln, die durch ein Rohr strömen, treten Partikel-Partikel und Partikel-Wand Kontakte auf. Ein Erhöhen der Partikel-Partikel Kontakte führt zu erhöten Trenneigenschaften, wohingegen die Materien der Rohrwand diese nicht beeinflussen

Gravity concentration in urban mining applications : a review

Urban mining has emerged as a concept that goes beyond conventional recycling, as it aims to tackle both the challenges of solid waste generation and management, as well as the scarcity of primary resources. Gravity concentration has gained increasing attention as a promising method for addressing crucial challenges in urban mining applications. In this sense, this review provides a comprehensive and up-to-date overview of gravity concentration in urban mining processes, covering principles, techniques, current applications, recent advancements, challenges, and opportunities. Emphasis was placed on shifting from the commonly found literature focus on ore processing to solid waste processing. Three types of solid waste, namely plastics, construction and demolition waste (CDW), and waste from electrical and electronic equipment (WEEE), were chosen for a more in-depth examination due to their massive production and widespread generation. Discussions also considered the potential of gravity concentration to address the unique challenges in their processing and explored possibilities for future developments

A Study Of Magnesium Oxide Biodegradable Coatings For Magnesium-Based Implants.

The objective of this study is to develop biocompatible, functional thin film magnesium oxide (MgO) coatings that: (1) serve as a galvanic separator between metallic substrates and metallic coatings, (2) control the rate of corrosion of Mg-based implants, (3) have controlled resorption times based on coating thickness, (4) promote osseointegration and (5) are predictable in corrosive environments

Recent developments in recycling of polystyrene based plastics

Due to their superior properties, plastics derived from petroleum have been extensively used almost in everyday life since last few decades. Because of lack in the manageability of plastic solid waste, their volume is increasing steadily in the natural world. Unfortunately, the disposal of plastics wastes in the oceans and land filling has led to a global issue. To effectively and efficiently deal with plastic solid waste is becoming a great challenge for the society as plastic solid waste creates big threat to our environment. Recycling of plastics solid waste should be performed to produce products having same quality to original plastics. This review article gives an overview of plastics solid waste with particular emphasis on the recent progress in polystyrene based plastics

Wet steam drying: Microwave-assisted droplet evaporation in open-cell ceramic foams

In many energy and process engineering systems where fluids are processed, droplet-laden gas flows may occur. As droplets are often detrimental to the system’s operation, they are required to be removed. According to the state-of-the-art, industrial droplet removal is achieved through a sequential arrangement of several separators followed by droplet collection and discharge. This results in a high-quality gas stream, yet at the expense of bulky and expensive systems that are difficult to retrofit to existing facilities. In addition, the multiple sequential separators produce high pressure drops, further increasing operating costs. Alternatively, a single droplet separation stage and in situ evaporation would provide compact solutions for facilities. However, compact engineering solutions for the removal of entrained droplets are difficult to achieve with conventional flow control and conduction heat transfer approaches such as Joule heating. Joule heating requires a well-defined and homogeneous electrical resistance to ensure uniform heating, which is technically challenging to apply in fine separators and thus compact removal devices are hence often costly and ineffective. Therefore, it becomes necessary to investigate alternative heating approaches to overcome these challenges, such as volumetric heating using microwaves. The research conducted in this thesis aims to analyze the potential of a compact microwave solution approach for droplet removal. The compactness of the approach relies on a novel fine separator structure enhanced by microwave-heat transfer for efficient in-flow droplet evaporation. The investigation targets at fundamental studies of the combined effect of droplet flow filtering and heat transfer from numerical calculations and experimentation. As novel fine separators, solid open-cell foams are a promising alternative for the separation of liquid droplets suspended in gas flows at comparably low pressure drops. Using susceptors, such as dielectric materials, for the skeleton and exposing them to microwaves is an efficient way to use them as heating elements. Silicon carbide (SiC) based open-cell foam samples were considered for the study as they are good susceptor materials. First, pore-scale fluid numerical simulations on representative foam models were used to obtain a deeper insight into the effects of pore size and pore density on the droplet retention time within foams. Numerical findings were reported considering the pressure gradient and the residence time distribution of droplets under different superficial flow velocities, droplet sizes, porosities and pore densities. Next, the temperature-dependent permittivity of SiC-based foam materials was determined by the cavity perturbation technique using a waveguide resonator at a microwave frequency of 2.45 GHz up to 200 °C. The permittivity was of particular interest as it is a crucial parameter for predicting and designing systems utilizing microwave heating. Along the permittivity measurements, electromagnetic wave propagation simulations were used to derive novel mixing relations describing the effective permittivity of foams while considering their skeletal morphology. The derived relations facilitate an efficient and reliable estimation of the effective permittivity of open-cell foams, producing good agreement to experimental data. Using the foams dielectric properties and the fluid characteristics of droplet-laden streams, a microwave applicator was designed to concentrate the electric field on the open-cell foams. The applicator was constructed for carrying out experimental studies on droplet evaporation removal under different flow velocities, microwave power and different SiC-based foams. Measurements of droplet size, velocity, number density and flux at the inlet and outlet streams of the applicator were performed using a 2D-phase Doppler interferometer. Eventually, it was found from the experimental data analysis that the application of open-cell ceramic foams as a filter medium reduced 99.9 % of the volumetric flow of droplets, while additional microwave exposure increased the reduction to 99.99 %. In addition, microwave-heated foams prevent droplet re-entrainment and structure-borne liquid accumulation within foams, thus avoiding water clogging and flooding. Hence, open-cell foams can be used as fine droplet separators as long as microwave heating may effectively evaporate accumulations of liquid. An important factor in designing future devices based on this microwave heating approach is the temperature, as it changes the arcing breakdown voltage of the gas, thus limiting the microwave input power and droplet flow velocity. Although more investigations are needed to develop an applicable and optimal product, the results presented in this thesis provide a first insight into the viability of using microwave heating and fine filtering as a compact solution for droplet removal

Index to NASA Tech Briefs, 1972

Abstracts of 1972 NASA Tech Briefs are presented. Four indexes are included: subject, personal author, originating center, and Tech Brief number

Selected Papers from the 9th World Congress on Industrial Process Tomography

Industrial process tomography (IPT) is becoming an important tool for Industry 4.0. It consists of multidimensional sensor technologies and methods that aim to provide unparalleled internal information on industrial processes used in many sectors. This book showcases a selection of papers at the forefront of the latest developments in such technologies

Modeling the Microstructural and Micromechanical Influence on Effective Properties of Granular Electrode Structures with regard to Solid Oxide Fuel Cells and Lithium Ion Batteries

The work studies electrode structures and the influence on the performance of electrochemical cells. Porous electrodes structures are modeled as a mixture of electron and ion conducting particles, densified considering manufacturing: sintering of SOFC is approximated geometrically; calendering and intercalation in LIB are modeled by a discrete element approach. A tracking algorithm plus a resistor network approach allow predicting connectivity, conductivity and active area of various structures

Effect of Milling on Electrostatic Separation and Modeling Protein and Starch Content of Flour Fractions

The objective of this research is to establish the effects of different milling techniques on the solvent-free electrostatic separation process for navy bean flour as well as to develop a model based on near infrared and fluorescence data to determine protein and starch content of the protein- and starch-enriched fractions using multivariate methods (i.e. partial least squares regression). Data fusion was used to combine the NIR and fluorescence spectra to try to achieve a model that had better predictability for protein and starch content. Protein content was measured using Kjeldahl digestion and starch content was measured using a dinitrosalicylic (DNS) acid array. The samples used in the NIR model are navy bean flour fractions from the electrostatic separation and the raw navy bean flour. There are 102 samples that are split in calibration (82 samples) and validation (20 samples) sets. The protein-enriched samples are collected from the electrostatic plate while the starch-enriched fractions are collected from the bottom of the electrostatic separator. The acquisition of reproducible infrared and fluorescence data from powder samples was successfully achieved. The pin milled navy bean flour had an average particle size almost three times smaller than the regular milled navy bean flour which could have contributed to the a high protein content (40.7%) of the protein-enriched fraction. The regular milled flour had a much higher protein extraction under optimum conditions but could only achieved a lesser protein content (32.5%) for the protein-enriched fraction. The regular milled navy bean flour also seemed to have particles disaggregate in the triboelectric charging process. Multivariate methods and pre-treatment techniques were compared for the NIR spectra of the navy bean flour fractions from electrostatic separation to measure the protein and starch content. The best method used Multiplicative Scatter Correction (MSC) pre-treatment with PLS regressions and had R2 values of prediction of 0.965 and 0.912 for protein and starch content, respectively. The N-way partial least squares (NPLS) regression was still a good model seeing as the R2 values of prediction for starch and protein content were 0.946 and 0.885, respectively. Two fluorophores were observed in navy bean flour: tryptophan and an unknown peak. It was observed that the starch model using the fluorescence dataset was highly correlated to the model’s predicted protein content (R2 of 0.978). The protein content model was better calibrated using the training set as well as providing a better prediction using the validation set for both NIR and fluorescence spectra. Data fusion was achieved by combining the NIR and unfolded fluorescence spectra of the navy bean flour fractions. The individual techniques had undergone pre-treatment separately and yielded the best model for determining protein content. Starch content was best determined using only the NIR spectra