Krafton, formerly Bijl Profielen in Heijningen in Brabant, has developed a unique circular solution with Van Beek, in which 100 percent of the production waste becomes part of the finished product. In this sustainable solution the hollow space in a polyester profile is filled with polyester chips using a pressing screw. “We have over a hundred tonnes of polyester waste a year, which we can now fully recycle”, says a spokesman for Krafton, the specialist in glass fibre reinforced plastic (GRP) pultrusion.
Residual material is an unavoidable result of a production process. It usually ends on a big waste pile, after which a specialist recycling company removes it, incinerates it or processes it in some other way. But what if you can make the waste material 100 percent part of the finished product and as a result can extend the existing range with a new, high quality and strong product? Krafton and Van Beek combined their knowledge and found the ultimate solution.
Recycling polyester
The globally growing polyester waste stream which includes written off boats and wind turbine blades set Krafton thinking. Right after a big wind farm approached the company to ask if they had a solution for their written off blades. The waste products are made of polyester, a glass fibre reinforced plastic. It would therefore be a pity not to recycle the raw materials. Shredding polyester products to incorporate the left-over chips into other products, is increasingly heard of. According to the spokesman, Krafton decided not to wait any longer and took action itself: “We can see that everyone is involved in this, but no one is really addressing it. Then we thought ‘we’ll just do something about it ourselves!’”
Weighing dosing screw
Together with Van Beek, Krafton was able to convert a dormant fantasy into a workable solution, and the initial testing has been successful. Result? A very strong, filled profile that was developed with as little material as possible. “We are going to recycle our own waste. In order to dose them accurately the polyester fibres are conveyed in a weighing dosing screw with a hopper, and are then conveyed to a double pressing screw. Via a heated pipe we add resin to the pressing screw and compress this substance using the screw into the hollow tube profile, which gives a much stronger solid profile”, explains the spokesman. Because of their strength, the newly developed solid profiles can be used in bridge decks, sheet pile walls in the ground for earth-retaining structures or for example a dragline mat.
The weighing module coupled to the dosing screw not only records how much polyester fibre has been incorporated, but also keeps track of the quantity dosed during the production process itself, so that the dosing screw can where necessary adjust the speed. That also applies for the container of fluid resin, which in turn is fitted with its own weighing module. To improve the mixing function of the polyester fibres with the resin, the pressing screw is designed with two parallel screws that partly intermesh with one another.
Well thought out customised solution
Joram van der Heijden, sales engineer at Van Beek, is proud that Van Beek is involved in this very unique project. “Not only do we solve a transport issue, we also contribute to the circular economy. It is particularly important that we are able to help the client think things through so early in the process to achieve not only better transport, but also recycling.” At present Van Beek is putting the finishing touches to the full-scale pilot set-up that Krafton will take into production this summer. Just like all the solutions that Van Beek delivers, this set-up is also a well thought out customised solution. “Shredded polyester is very difficult to transport. The chips are light, do not flow well and form bridges, so a blockage can soon occur. We have now solved this by fitting a hopper with two rotating shafts at the bottom with paddles that keep the polyester chips constantly moving, so that they flow into the screw below”, explains Van der Heijden.
After a successful pilot phase the specialist in GRP pultrusion will in the future possibly focus on large-scale collection of shredded wind turbine blades. It is therefore secretly dreaming of expansion. “The Van Beek screw conveyor, hopper and pressing screw can certainly process a coup of thousand tonnes of production waste, much more than our own waste. You have to do something with waste, you have to ‘complete the circle’. If we can process blades, that may perhaps also apply for other synthetic fibres”, says the spokesman.
