Galvanised parts are among the last big challenges for recycling. Because recovering the materials they contain is very technically complex, previous procedures have generally concentrated on only one of the material fractions – usually the metals. These processes resulted in a low material purity that meant only downcycling of components was possible. These two factors made the costly and cumbersome recycling process barely economically viable in relation to the value of recovered material.
Now, ImpulsTec has taken up the gauntlet and is implementing shockwave or electrohydraulic shredding technology, which is not yet widespread in Germany, for the separation of complex material compounds in industrial processes. A custom-designed facility for stripping chrome-plated plastic parts through shockwave treatment, in combination with pre-shredding and magnetic separation, was commissioned at sanitary engineering manufacturer, Hansgrohe. This facility can separate production waste in bath and kitchen fittings with a resulting material purity of >99%, which makes it possible to reuse both material fractions in premium components.
Because Hansgrohe Group sets very high quality standards in terms of shower, bath and kitchen fittings, a certain level of production waste is unavoidable. “The chrome-plated ABS plastic parts used to be a real thorn in our side,” reports David Zapf, specialist for surface technology at Hansgrohe, referring to the housings for hand showers, pipe collars, knobs and buttons on fittings. To give its products the necessary robustness and durability in use, the manufacturer creates a highly stable connection between plastic and metal. On the one hand, this is an indicator of quality, however, on the other, it presents major challenges for reprocessing. “Because it was previously not possible for us to internally separate the thin galvanic layer from the ABS while preserving both material fractions before this project, we used to hand chrome-plated parts over to external recycling partners,” explains Zapf.
Pilot facility in three containers for outdoor installation
“Due to the local circumstances at Hansgrohe, the new facility had to be suitable for installation outdoors, and not exceed 22 m in length and 10 m in width,” explains ImpulsTec managing director, Stefan Eisert. “That’s why we designed the pilot facility to operate within three weatherproof container units.” As the galvanised parts to be recycled are of different sizes and complexity levels, the first container deals with pre-shredding and includes a screening column. The homogenous granulate obtained in this process is subject to proprietary shockwave treatment in the second stage. This involves the pre-treated raw material being placed into a water bath; brief ignition of an electric arc between two electrodes within the medium creates mechanical shockwaves that gradually separate the individual material fractions from one another. The used water is then filtered, and subsequently returned to the shockwave process in a closed loop.
The post-process material is conveyed to the third container and dried there. The individual material fractions are then separated by means of magnetic separation. The majority of this – 70 to 80% – is plastic. In order for this to be usable for new premium products, it must have a stable purity of >99%. The remaining material fraction is composed of copper, nickel and chrome from the galvanic coating, which is delivered to metal processing companies. “As this facility is a completely new concept, in the course of development we had to thoroughly test and optimise all process steps, and also their interlinking and interaction. Doing so means we are now able to fulfil Hansgrohe’s demanding requirements in terms of material purity,” adds Eisert.
Reuse of 98% of raw materials
At Hansgrohe, the new facility operates on 250 working days per year, for eight hours each day. This results in an annual throughput of 100 000 kg of chrome-plated plastic. “Thanks to electrohydraulic shredding, we can now reuse 98% of the raw materials from our production waste in this area,” reports Zapf. “This represents a major step toward our circular economy goal.”
The success of using electrohydraulic shredding of galvanised plastic parts to facilitate reuse of both material fractions marks a milestone for recycling technology in the industrial sector. Zapf also gives a positive summary of the collaboration with ImpulsTec. Hansgrohe is already examining the extent to which shockwave technology could even be used for future recycling of complete products − fittings that have already been used by customers. “The application of our newly developed stripping process for sanitary products was only the first step,” says Eisert. “In the automotive industry and in the electronics sector, our technology also opens up new possibilities for reuse of production waste and product components at the end of their lifecycle.”
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