Treatment of Contaminated Industrial Plastic Waste: Ettlinger Melt filters Improve Product Quality and Cost Efficiency at Candi Plastic Recycling

For the past three years an ERF 200 filter built by Ettlinger of Königsbrunn, installed at Candi Plastic Recycling, an Austrian materials recycler, has been producing high quality regrind nonstop from contaminated plastic waste with high aluminum or paper fractions. The very high contaminant discharge rate and low melt loss which are typical of this machine are fundamental for processing efficiency. After the filter had been operating at Candi without any problems, the company decided to purchase a second melt filter of the same type for installation at SC CALEX, its Romanian subsidiary, where it has proved to be equally durable.

At the heart of the line at the parent facility in Sollenau is a vacuum degassing recycling extruder, which melts and homogenizes the shredded, pretreated and agglomerated plastic waste. The continuously operating ERF 200 high performance filter integrated in this extrusion line removes residual contaminants from the processed melt. A water ring pelletizer with a downstream bagging station completes the line. Candi mainly processes cosmetics bottles and tubes with lid seals containing silicone as well as film scrap with a high aluminum fraction, such as that generated during the production of beverage packaging or yogurt pots.

It was the high filtration efficiency and excellent durability that tipped the scales in favor of the ERF 200 for Candi Managing Director Gheorghe Campan. “We need to process contaminated feedstock reliably 24/7. We simply can’t afford to have stoppages due to frequent screen changes, which with conventional piston screen changers are the norm,” he says. “Our customers expect regrind of the highest possible quality from us even though the input material contains extraneous components. We must be capable of removing virtually every single particle of contaminated material.” He particularly mentions the silicone which originates from the seals and is a cause of specks in the film, leading to a deterioration of the material properties if the filtration efficiency is inadequate. He confirms that “the ERF 200 fulfills our high requirements in every respect, even with this critical material."

The reason for this high filtration efficiency lies in the special, completely closed design of Ettlinger high performance melt filters, which permit absolutely stable processing with a constant volume and pressure. The central component is a rotating, cylindrical screen with millions of conical holes, through which melt flows from the outside to the inside. The contaminants which are retained on the outside of the screen are continuously removed by a scraper, then discharged by means of an exit screw. After only a short residence time, the cleaned melt on the inside of the drum is supplied to the filter outlet and then onward to the downstream pelletizing machine. Ettlinger ERF filters are offered in three sizes: the ERF 200 for a maximum throughput of 1 t/h, the ERF 350 for throughputs up to 3.8 t/h and the ERF 500 for 6 t/h.

These filters allow printed films or materials such as PE, PP or PS containing up to 18% paper and / or aluminum to be processed without any problems. PS or ABS flake from refrigerator and electronic waste with a high proportion of wood and rubber is likewise cleaned efficiently and reliably. Even gels or high-molecular and cross-linked fractions are efficiently separated on the screen. Depending on the material, the level of contamination and the screen size, Candi achieves throughputs of up to 700 kg/h with the ERF 200 model installed in Sollenau. The filter can remain in use for several weeks before it needs to be cleaned. In this case, it takes no more than an hour or so to complete the screen change and production is only briefly disrupted.

Candi regrind is sold to injection molders, blow molders, film extruders and rotomolders in Germany, Austria, Romania and the Czech Republic. Films, thin blow film and above all construction industry goods like pipes, mounting plates, spacers or formwork supplies are typical end products.