Masato Saeki

Triboelectric Separation of Three-Component Plastic Mixture

The results of an experimental study on the triboelectric separation of one type of plastic from a three-component plastic mixture are presented. A triboelectric separator, which consists of a vibratory conveyor equipped with two electrodes, was used. The separation method makes it possible to avoid the adhesion of oppositely charged particles. Separation tests were performed on two kinds of mixtures. The effect of operating parameters such as electric field strength, polarity of applied voltage, and triboelectric charging time on the separation efficiency was examined. In the case of the separation of a mixture of 50% polyvinyl chloride (PVC), 50% polyethylene terephthalate (PET), and 50% polyethylene (PE), the purity of the extracted PVC was larger than 99% for a recovery rate of 94.9%. In the case of the separation of a mixture of 50% acrylonitrile butadiene styrene (ABS), 50% polypropylene (PP), and 50% polystyrene (PS), the purity of the extracted ABS was larger than 99% for a recovery rate of 89.4%.

Vibratory Separation of Plastic Mixtures Using Triboelectric Charging

This article presents the results of experimental and analytical studies of the performance of a novel vibratory separator of plastic mixtures for recycling. The separator unit consists of a vibratory conveyor equipped with two plate electrodes. The principle behind the separation technique is based on the difference in Coulomb force acting on the plastic particles after triboelectric charging. The separation of a mixture of 50% polyvinylchloride (PVC) and 50% polyethylene terephthalate (PET) using this method was studied. An analytical model describing the relative distribution of the two types of plastic particles in the collection trays was developed. The effect of triboelectric charging time and electric-field strength on the separation efficiency was investigated.

Vibro-electrostatic separation of binary ABS/PS granular mixtures

This paper presents the results of experimental studies of the performance of avibro-electrostatic plastic separator, which essentially consists of two plate electrodes undergoing translational harmonic vibrations along the horizontal plane. The principle behind the separation technique for such a separator is based on the difference between Coulomb forces acting on plastic particles after triboelectric charging. The separator has the advantages of a low-voltage field and a small structure over free-fall triboelectric separators. Separation tests were performed on binary mixtures. The effects of the feed composition of the mixtures and operating parameters, such as electric field strength, applied voltage polarity and triboelectric charging time, on separation efficiency were examined. This study was conducted to understand the effects of various parameters on separation efficiency, in order to obtain the optimum operating conditions for separators.

Particle damping: Noise characteristics and large-scale simulation

The performance of a large-scale particle damper in a vertical vibrating system was investigated experimentally and theoretically. To use particle dampers on an industrial scale, their noise characteristics must be clarified and a large-scale simulation is essential. This paper presents the results of an experimental investigation of the effects of the particle material, mass ratio and diameter on the amount of noise generated by a particle damper. In the theoretical analysis, two computational methods for conducting large-scale simulations of particle damping are proposed. The validity of the numerical methods is examined by comparison with experimental results. It is found that the calculation time and memory usage are decreased considerably by using the computational methods.

Vibro-electrostatic separation of plastic mixtures (3rd report, effect of inclination on separation efficiency in inclined electrodes)

This paper presents the results of an experimental and analytical study of plastic mixtures using a new vibro-electrostatic separator. The separator consists of a vibratory feeder equipped with two plate electrodes and the electrodes can be inclined about two axes with respect to the horizontal plane. The principle behind the separation technique is based on the difference in Coulomb force acting on the plastic particles after triboelectric charging. The separation tests were performed on a sample containing acrylonitrile butadiene styrene (ABS) and polystyrene (PS). Their particles obtained from chopped plastic plates were used. The influence of inclination angle of the electrodes and tribocharging time on the separation efficiency was investigated. In the case of the separation of a mixture of 50% ABS and 50% PS, the purity was larger than 99% for a recovery of 95%. It is also shown that for several kinds of composition ratio it is possible to obtain high purity and recovery of plastics.

Behaviour of granular materials in the field of vibration

Vibration has been widely used in various industrial operations dealing with granular materials. Classification, conveying and packing provide typical examples of the vibration technique. In spite of these actual uses, the behaviour of granular materials is poorly understood. Most of the knowledge related to handling of particulates is empirical and no generalized approach for the analysis of the response of granular materials to external forces exists. This paper presents an investigation into the development of a numerical method for size segregation, which is the typical behavior of granular materials in the field of vibration. This numerical method is modified on the basis of the discrete element method proposed by Cundall. In order to consider the shape anisotropy of particles, they are first treated as elliptic models. Then mechanical units such as spring, dashpots and friction sliders are used to express the contact forces. The effect of the size ratio and the shape of each particle on the response of granular materials is considered.

Vibratory Conveyance of Granular Materials Comprising Elliptic Particles

The flow model of granular materials on vibratory conveyors is derived by using an improved discrete element method. Granular materials are first assumed as cylindrical bodies with elliptic cross sections to take into account the dependence of shape anisotropy on the flow patterns. Then mechanical elements such as springs, dashpots and friction sliders model the contact forces and the equation of motion for the particles is numerically solved. It is shown that the mean velocity of transport of granular materials depends on the frequency and amplitude of the vibratory input as well as various physical parameters. By comparing the experimental with calculated results, the flow patterns obtained by this method appear realistic.