Electrostatic separator plastics separation

Plastic and Metals Recycling Electrostatic separation has been inereasinglv applied to recover nonFerroiis metals From industrial plasties (telephone and eornrniinieation scrap). It also is an important step in the reeveling oF beverage bottles to reject anv remaining nonFerroiis metals. Both oF these reeveling applications make use oF roll-type ion-bornbardrnent separators (Fig, 19-61/ ),... 

The PET and aluminum chips require further drying so that they can be electrostatically separated. This is the most expensive part of the entire process. "The aluminum cap is only 1% by weight of the bottle," explains Dittman, "but the equipment to remove it represents about 30% of the investment in the plant. It s out of balance, and we are trying to remove the aluminum more cheaply." The process-which at the CPRR plant can handle about 600 lb per hour, or a potential capacity of about 5 million lb per year—generates clean, well-separated (99.9%) granulated plastic chips that can be sold to a manufacturer who uses the resins. 

R. Kohnlechner, Triboelectric charging and electrostatic separation of diverse, non-conductive mixed waste, especially plastic, employs enclosed vibro-conveyor followed by in-flight separation influenced by non-linear electrostatic field, DE Patent 19 901 743, assigned to Hamos GmbH Recycling und Separ, July 20, 2000. 

ELECTROSTATIC SEPARATION OF PLASTICS FROM INDUSTRIAL WASTES. A REVIEW... 

Electrostatic separation can be used to separate waste particles not contacting electricity (e.g., paper, plastic, glass, etc.) from conductors (e.g., metals) or nonconductors from each other, based on differences in their electrical conductivity. In addition to particles conductivity, electrostatic separation is also influenced by particle density, size, moisture, and purity of particles surface. Consequently, separation of waste particles is achieved under the action of electrical as well as gravity or centrifugal forces. 

Although electrostatic separation (static or high intensity) has not been applied widely in solid waste treatment at the industrial level, it is expected to be of wider use in the future in certain sectors of applications. This separation has been successfully applied to separate plastics from paper, plastics from each other, shredded copper wires from their plastic insulation, glass from plastic, nonferrous metals from plastic, or glass, for example. 

Three companies that supply electrostatic separation equipment to the plastics recycling industry are listed here ... 

Hamos GmbH of Penzberg, Germany, has developed triboelectric separation systems for plastic/plastic separations, and electrostatic separators for plastic/metal separation. ... 

After cutting, grinding and after a first separation of the metals, the plastics are sent. Fig. 13a, to a floating section for separating PVC and PE. After a passage in an electrostatic separator to eliminate the last particles of metals. Fig. 13b, PVC is blended with additives (stabilizers, lubricants, colorants), compounded and extruded in a twin screw extruder. The recycling of LDPE insulators from cables is subjected to a similar processing. 

Tapscott et al. [7] have also examined electrostatic separation of spent abrasive. In this process, spent plastic abrasive is injected into a high-voltage, direct-current electric field. Material separation depends on the attraction of the particles for the electric field. In theory, metal contaminants can be separated from nonmetal blasting debris. In practice, Tapscott and colleagues reported, the process sometimes produced fractious with heavier metal couceutratious, but the separatiou was iusufficieut. Neither fractiou could be treated as uouhazardous waste. lu geueral, the results were erratic. 

Carpco has several electrostatic plastic separation systems in place in the U.S.A. and Europe. One system used at Nationwide Recycling Division of Crown Cork and Seal in PoUcton, NC, separates PVC from PET bottle flake at a rate of 1500 Ib/hr. Electrostatic separation can even be used to separate epoxy-painted thermoplastic olefin automobile... 

Plas-Sep Ltd. of Canada also sells electrostatic separators for mixed plastics." ... 

Beck MH, et al. Electrostatic separation of plastic materials. Patent WO 1993006934 1991. 

Tilmatine A, et al. Roll-type versus free-fall electrostatic separation of tribocharged plastic particles. Electrostatic joint conference 2009. 

Electrostatic separation of a particulate mixture of dfferent plastics/minerals... 

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