This article presents the results of an experimental investigation into the separation of waste electrical cables using a new installation based on electrostatically assisted aspiration system. The installation operates with a plate conveyor that promotes the attachment of conductive particles to its surface under the influence of electrostatic forces, aiding in the separation process by aspirating the insulating particles. The operation of the installation is controlled by several factors such as the rotation speed of the aspirator motor, the high voltage applied to the curtain electrodes integrated into the conveyor plates, and the waste feed rate. This installation has demonstrated promising results in the separation of electrical cable waste with a particle size larger than 2 mm. Its major advantage lies in its ability to recover conductive particles with various sizes. Additionally, it exhibits exceptional productivity that exceeds 650 kg/h in a 1 m wide installation, making it suitable for industrial applications. However, the presence of powdered copper in electrical cable waste can cause insulation problems between the two electrodes of the electrostatic plate, so an insulating layer is applied to them. Based on the experimental models developed in this study, optimization techniques were applied to identify the optimal operating point of the installation. Then, an experimental analysis was conducted to evaluate the impact of applying an insulating layer to the curtain electrode surface on particle behavior. Examining the parameters that influence the attachment force of conductive granules to the curtain electrode surface using a test bench designed in this study indicates that increasing the amplitude and frequency of the applied voltage can intensify this attachment force. For copper granules with a diameter between 0.3 and 0.5 mm recovered from cable scrap, force saturation occurs at 5 kV and above within a range of 3 to 7 kV and at a frequency of 10 to 90 Hz.

Aerodynamics praying assisted with electrostatic charging is a technique where liquid droplets are electrically charged before being directed towards target objects. This method is commonly used to apply phytosanitary products to the surfaces of agricultural products. Its objective is to reduce spray drift while improving target coverage. In this study optically measured spray deposition of a contact charging type of air-spraying nozzle system. A water based solution containing visible dye was applied to paper sheets attached around the circumference of a grounded, conductive 90 mm diameter cylinder target. For liquid voltage levels between -15 kV and -40 kV, droplet deposition at 2 radial locations on the cylinder was evaluated at spray distances of 3 and 4 meters for spray durations of 25 and 35 seconds. After spraying, the density of the dye deposition was assessed by image analysis of the scanned paper sheets. The specific factors that increased deposition onto target backside locations for this nozzle system were found to be higher electrode voltage (spray charge), longer spray duration and shorter distance from nozzle to target. Distance was observed to be the most significant factor in these experiments.

The free-fall electrostatic separator is widely used for sorting plastic particles obtained from waste. The incorporation of flexible electrodes in this installation and the appropriate adjustment of their shapes make it possible to control the particle flow in the electrostatic separation zone, reducing particle-electrode impacts and increasing the quality of recovered products. In this study, we introduce a methodology to optimize the shape and position of flexible electrodes in a free-fall separator. The optimization criterion considered is the horizontal deviation of particles collected in the separator.Theelectrodes are modeled using B & eacute;zier curves with four control points, which provide an infinite number of electrode shapes by adjusting their positions. During the optimization process, only feasible configurations that meet certain constraints are considered. For each feasible configuration, a simulation model is used to obtain the trajectory of test particles, which is experimentally validated using a high-speed camera before being used in the optimization process. A genetic algorithm is used to determine the optimal configuration, which is defined by the position of the four control points of the B & eacute;zier curve. This paper aims to achieve two main objectives: (i) experimentally validate the numerical model of particle behavior in free-fall separators equipped with two flexible electrodes using a high-speed camera; (ii) use the model obtained from the genetic algorithm to determine the optimal shape and position of the electrodes.

The triboelectric charging of non-conductive particles poses a substantial challenge for the development of electrostatic separation technologies with applications to waste plastics recycling. The present study aims at evaluating the effectiveness of a novel multi-spiral-type triboelectric charger for processing plastic particles derived from waste electrical and electronic equipment (WEEE). The experiments were conducted with 10 g granular samples of high-density polyethylene (HDPE), polycarbonate (PC), and polystyrene(PS), in sizes ranging from 2 mm to 4 mm. The global charge acquired by each sample was measured by collecting the granules in a Faraday pail at the exit of the tribocharger, operated at different frequencies of the electromagnetic vibratory device to which it is associated. In a distinct set of experiments, the tribocharged granules were transferred in the electric field of a free-fall electrostatic separator and collected in 9 distinct compartments. The charge and the mass of the granules collected in each compartment were then measured. Charge per mass ratios exceeding -6 nC/g were achieved for PS and HDPE particles, while a ratio of 5.5 nC/ g was obtained for PC. The obtained results not only assess the efficiency of the new charger but also provide a deeper understanding of the tribocharging process, thus contributing to advancing electrostatic separation technology for plastic waste recycling.

This article presents the results of an experimental investigation into the separation of waste electrical cables using a new installation based on electrostatically assisted aspiration system. The installation operates with a plate conveyor that promotes the attachment of conductive particles to its surface under the influence of electrostatic forces, aiding in the separation process by aspirating the insulating particles. The operation of the installation is controlled by several factors such as the rotation speed of the aspirator motor, the high voltage applied to the electrodes integrated into the conveyor plates, and the waste flow rate. This installation has demonstrated promising results in the separation of electrical cable waste with a particle size larger than 2 mm. Its major advantage lies in its ability to recover conductive particles with various sizes. Additionally, it exhibits exceptional productivity that exceeds $650 ~\text{kg} / \mathrm{h}$ in a 1 m wide installation, making it suitable for industrial applications. Based on the experimental models developed in this study, optimization techniques were applied to identify the optimal operating point of the installation.

There are several devices designed for the processing of millimeter-sized granular mixtures, but few devices are specifically designed for the treatment of micronized particles. That's why a rotating cylinder separator has been developed to address this specific need. This separator stands out by not requiring a tribocharging device. Instead, it utilizes the charge acquired by the particles during the grinding process to separate them. To ensure its proper functioning, the separator requires an electrode cleaning system, such as a brush connected to the electrode. The objective of this study was to assess the impact of various elements that may affect the new electrostatic separator's performance. Polyvinyl chloride (PVC) and unplasticized polyvinyl chloride (UPVC) were combined in a binary mixture for the experiments. Three control factors were examined: the applied high voltage, the particle flow rate, and the cylinder's rotation speed. The purity measurement was carried out using a visual method. The obtained results were extremely satisfactory, confirming the effectiveness of this equipment

This study thoroughly analyzes the performance of roll-type electrostatic separators compared to an innovative method based on electrostatically assisted aspiration for sorting copper and PVC particles from electrical cable waste. The results of this study highlight the capacity of roll-type separators to recover between 98 and 100% of PVC particles at relatively low rotation speeds. However, at these speeds, a significant proportion of copper ends up inadvertently in the PVC bins. The new electrostatic separator, on the other hand, offers greater flexibility. By carefully adjusting the parameters, it achieves satisfactory recovery rates for both copper and PVC. Thus, the choice of the most suitable parameters will depend on the desired material and the compromises acceptable in terms of recovery efficiency.

This study presents a new electrostatic separation device for recovering high-purity metals and plastics from waste electrical and electronic equipment. The device is constituted by a rotating plate conveyor, an air suction system, and a vibrating hopper. It utilizes electro-adhesion force to selectively attract metal particles onto the conveyor surface, while precisely calibrated suction air effectively collects plastic particles into a dedicated box. A key feature is the employment of a low-level AC high voltage, significantly enhancing operational efficiency and safety compared to conventional electrostatic methods. Experimental results demonstrate high performance, achieving recovery and purity rates of up to 100 % depending on applied voltage and airflow settings.

This article discusses the design and implementation of an eddy current separator prototype for the linear separation of non-ferromagnetic conductive particles. Utilizing the phenomenon of electromagnetic linear induction, the device sorts particles based on their electrical conductivity. The prototype's characteristics and performance were experimentally evaluated, demonstrating effective particle separation based on conductivity. This separator shows significant potential for various industrial applications that require precise separation of non-ferromagnetic conductive particles.

This article describes the operation and compares the performances of two devices that can be employed for the separation of conductive and non-conductive particles: a DS-LIM (double sided linear induction motor) separator and an inclined plate electrostatic separator. The aim of the research is to find the link between these two types of separators and whether they can be connected to each other in order to increase the particle separation efficiency and reduce the consumption of electrical energy. The study enabled the evaluation of the factors that influence the performance of each separator. Thus, it was possible to accurately determine the range of particle size extracted for each separation process.

The triboelectric charging of non-conductive particles poses a substantial challenge for the development of electrostatic separation technologies with applications to waste plastics recycling. The present study aims at evaluating the effectiveness of a novel multi-spiral-type triboelectric charger for processing plastic particles derived from waste electrical and electronic equipment (WEEE). The experiments were conducted with 10 g granular samples of high-density polyethylene (HDPE), polycarbonate (PC), and polystyrene (PS), in sizes ranging from 2 mm to 4 mm. The global charge acquired by each sample was measured by collecting the granules in a Faraday pail at the exit of the tribocharger, operated at different frequencies of the electromagnetic vibratory device to which it is associated. In a distinct set of experiments, the tribocharged granules were transferred in the electric field of a free-fall electrostatic separator and collected in 9 distinct compartments. The charge and the mass of the granules collected in each compartment were then measured. Charge per mass ratios exceeding −6 nC/g were achieved for PS and HDPE particles, while a ratio of 5.5 nC/g was obtained for PC. The obtained results not only assess the efficiency of the new charger but also provide a deeper understanding of the tribocharging process, thus contributing to advancing electrostatic separation technology for plastic waste recycling.

Electrostatic spraying is a spraying technique in which particles or liquid droplets are electrically charged before being ejected towards target objects. This method is widely used in the application of phytosanitary products on the surface of agricultural products. Its objective is to improve the quality of the coating applied to the target objects by using electrostatic forces to direct and control the trajectory of the charged particles. This study focuses on the evaluation and quantification of the effects of specific factors in a laboratory electrostatic spraying device. A device was designed and implemented to assess the effects of the applied high voltage value (U) on the electrode of the spraying nozzle, the distance (D) between the spraying nozzle and the target object, and the spraying duration (t) on the quality and uniformity of the coating applied to the surface of a cylindrical object. An experimental design methodology was employed for this study. The results of this study demonstrated that the electrostatically charged sprayed product exhibited improved coating performance under specific conditions. The knowledge gained from this study contributes to a better understanding of the electrostatic spraying process and paves the way for optimization of this technique.

The free-fall electrostatic separator is widely used for sorting plastic particles obtained from waste. The incorporation of flexible electrodes in this installation and the appropriate adjustment of their shapes make it possible to control the particle flow in the electrostatic separation zone, reducing particle-electrode impacts and increasing the quality of recovered products. In this study, we introduce a methodology to optimize the shape and position of flexible electrodes in a free-fall separator. The optimization criterion considered is the horizontal deviation of particles collected in the separator. The electrodes are modeled using Bézier curves with four control points, which provide an infinite number of electrode shapes by adjusting their positions. During the optimization process, only feasible configurations that meet certain constraints are considered. For each feasible configuration, a simulation model is used to obtain the trajectory of test particles, which is experimentally validated using a high-speed camera before being used in the optimization process. A genetic algorithm is used to determine the optimal configuration, which is defined by the position of the four control points of the Bézier curve. This paper aims to achieve two main objectives: (i) To experimentally validate the numerical model of particle behavior in free-fall separators equipped with two flexible electrodes using a high-speed camera. (ii) To use the model obtained from the genetic algorithm to determine the optimal shape and position of the electrodes.

This paper investigates particle electrostatic separation inside a new conical rotary installation using the discrete element method to understand particle behavior related to multiple variables such as the applied high-voltage, particle charge, and mass. The model offers the ability to monitor and control all significant parameters at particle level. The results have been analyzed using the response surface methodology to further understand the relationships between variables. These findings could serve as a blueprint for the manufacturing of an efficient industrial device.

Electrostatic separation processes are emerging as the solution of choice for recycling waste from end-of-life equipment in various industries. The separation of the different constituents of such plastic mixtures is the key to successful recycling. The main objective of this work was the development of a new spiral-type tribocharging device with application in the field of electrostatic separation. The spiral charger offers a very high charging rate compared to other triboelectric systems. It favors collisions of the particles with the inner wall, which is very efficient to separate a mixture of ternary particles. The study was conducted with samples of various medium-sized (2–5 mm) granular plastics, for several values of air velocity, pipe length, and particle mass in the turbocharging device. The spiral charger was associated with a belt-type electrostatic separator to process a granular insulating mixture, consisting of three types of plastic products Polyvinyl Chloride, Polypropylene, and Polystyrene. This work also aims at numerically simulating the dynamic behavior of insulating particles in belt-type electrostatic separators. The good separation obtained for this ternary mixture shows the efficiency of the new tribocharger.

The electrostatic separation is known as an efficient and robust recycling technology, characterized by low cost, reduced energy consumption and ease of use. However, the separation process is multifactorial and requires a judicious choice of electrical and geometrical parameters in order to enable the processing of different material mixtures and obtain an optimal result. The aim of this paper was to study the different factors that influence the trajectories of charged insulating particles exposed to an intense DC electric field of a roll-type electrostatic separator. For this purpose, a numerical model, based on the fundamental principles of dynamics, was elaborated in order to simulate the behavior of the particles in such electrostatic devices. The numerical model considered the main electrical, mechanical, and aero-dynamical forces that govern the movement of the particles. To check the accuracy of the numerical model, several experiments were carried out on charged insulating particles in the roll-type electrostatic separator. The particle trajectories were recorded with a high-speed camera and compared with those obtained by numerical simulation. The results obtained validate the numerical model, as the simulated trajectories were similar to those captured by the camera.

Electrostatic separation processes are emerging as the solution of choice for recycling waste from end-of-life equipment in various industries. The separation of the different constituents of such plastic mixtures is the key to successful recycling. The main objective of this work is the development of a new spiral-type tribo-charging device with an application in the field of electrostatic separation. The spiral charger offers a very high charging rate compared to other triboelectric systems. It favors collisions of the particles with the inner wall, which is very efficient to separate a mixture of ternary particles. We studied tribocharging characteristics of several types of medium-sized (2-5 mm) granular plastics. The study is conducted with samples of various e insulating materials, for several values of air velocity, pipe length and particle mass in the turbocharging device. The spiral charger was associated with a belt-type electrostatic separator to process a granular insulating mixture, consisting of three types of plastic products Polyvinyl Chloride (PVC), Polypropylene (PP) and Polystyrene (PS). The good separation obtained for this ternary mixture shows the efficiency of the new tribocharger.

Accurate prediction of the effects of the various factors that might influence the outcome of novel electrostatic separation process requires reliable physical and mathematical models for the numerical simulation of particle trajectories. The major objective of this paper was to demonstrate that the use of a high-speed camera for recording particle trajectories could be instrumental in refining the understanding of the complex physical phenomena that occur in these electrostatic devices and in improving their operating conditions, based on valid numerical simulation results. The experiments were carried out with spherical conductive particles, using a roll-type corona-electrostatic separator. The particles trajectories were recorded using a high speed-camera at acquisition frame rate of 200 fps. The electrical field computation and the resolution of the differential equation of motion of the particles under the action of electrical and mechanical forces exerted on them enabled the prediction of the outcome of the separation process. The study was carried out for particles of different sizes, for different voltages and for different electrode positions. The simulation results were in good agreement with the experimental data.

Triboelectrostatic separation is a technology which allows the selective sorting of polymer materials based on their surface charging characteristics. Before they are subjected to electrostatic separation, the materials to be sorted are reduced to a proper size (typically less than 5 mm). The present paper aims to evaluate the possibility of using shredding as simultaneous size-reduction and tribo-charging operation and examine the effect of shredding and size reduction on triboelectric charging and electrostatic separation efficiency. The study was performed on typical pieces of PC-ABS and HIPS originating from waste electric and electronic equipment (WEEE). Experiments start by feeding equal quantities of plastic pieces into the shredder. The rotary cutters of the shredder stir the plastic pieces, a charge transfer occurs between the plastic particles by repeated collisions and rubbing against each other. After a certain time, a granular mixture was recovered from the shredder and immediately introduced in a roll type triboelectrostatic separator. The charge of the selectively sorted products was measured using a Faraday cage connected to an electrometer. Four screen mesh diameters were compared (2 mm, 3 mm, 5 mm, and 7 mm). The experimental results confirm that granules can get enough charge during shredding for being successfully sorted by the roll-type electrostatic separator. Particle size is definitively an important factor influencing the outcome of the triboelectrostatic separation. Fine shredding is not favorable, as it requires shredding for extended periods and favors the formation of particle agglomeration. High separation efficiency was obtained for relatively coarse particles.

The four-cylinder electrostatic separator is a recent improvement of the “standard” free-fall equipment. The new design, which drastically reduces the inconveniences related to the impacts that might occur between the particles and the electrodes, has been adapted for applications involving the processing of micronized particles. Such applications require the use of a specific rotating-blade-type tribocharging device and an appropriate electrode cleaning system. The aim of the present work is to evaluate the effects of several factors that influence the performances of the new triboelectrostatic separator. The experiments were made on a binary mixture of polyvinyl chloride (PVC) and unplasticized PVC. The control variables considered in this study were the rotating speed of the central cylinder of the tribocharging device, the voltage applied to the electrodes of the separator, and the distance between them. The results obtained were excellent: The recovery rates and the purities of the separated products exceeded 95% for the optimum values of the control variables.