Herbold Meckesheim tanks offer plastic density separation

Herbold Meckesheim USA now is offering density separation tanks, also known as sink-swim tanks, that use water to separate plastic scrap of different densities as well as to separate contaminants from homogenous plastics, according to the firm, which is a subsidiary of Germany-based Herbold Meckesheim GmbH.

Items are introduced to the steel sink-swim tanks by a feeding screw or conveyor at one end, the company says. Three or four transport drums (rotating paddles) then move the material from one end of the tank to the other.

During the process, higher-density plastics such as polyethylene terephthalate and polyvinyl chloride and contaminants sink to the bottom of the tank, while lower-density plastics such as polyethylene and polypropylene float on the surface of the water.

According to Herbold Meckesheim, lighter plastics exit the tank via a top discharge setup, and heavier items are continuously removed by a scraping chain conveyor mounted below the bottom of the tank. The tank’s V-shaped bottom has been designed to help ensure that sinking scrap or waste can be exited from the bottom with no accumulation or buildup.

Tanks are available in three sizes, with the smallest measuring 78 inches by 31 inches and the largest measuring 157 inches by 71 inches. Drive motors are available in a range of horsepowers from 1.5 up to 15. “Throughputs vary depending on material and tank size,” the company says.

Herbold Meckesheim USA is a North Smithfield, Rhode Island-based designer, manufacturer and installer of size-reduction equipment and wash line systems for the plastics industry, specializing in the recycling of industrial and postconsumer plastics.