Circular Reprocessing of Zamak Laryngoscope Blades

Abstract

There is an incentive in society to go towards a circular economy to prevent the depletion of resources and prevent climate change. The medical industry generates a large amount of waste, much of which are disposable medical instruments and consumables, of which some are not reused. In the context of creating more circularity, an “all-in-one” process has been designed for the reprocessing of the Rüsch Polaris Fiber Optic Laryngoscope Blades made from Zamak. A system was designed where blades were reprocessed by means of melting into new raw material which was used to make new products. The blades are melted in a receptacle containing a grate with 3 mm x 3mm holes which acts as a filter. This receptacle is connected to a mold where the liquid Zamak can subsequently flow into. As the holes of the filter are too small for many of the impurities to pass through, the filter prevents most non-Zamak particles on the blades from flowing into the mold along with the liquid Zamak. Multiple ingots were casted using this setup. The amount of Zamak extracted from the blades was analyzed by weighing the Zamak before and after melting. The purity of the processed material and its mechanical properties were also evaluated. Through XRF tests, it was found that the ingots had a purity of 99.6% on average in respect to 100% pure Zamak. Using the final iteration of the melting setup, the ingots were found to have an ultimate tensile strength of 223 MPa and a yield strength of 124 MPa on average. It was also possible to recover about 93% of the Zamak from the blades. To exemplify the possibility of directly creating new products with the “all-in-one” process, a rotation knob for a laparoscopic instrument named “SATA grasper” was additionally casted. The flat surfaces on the rotation knobs were grainy, while the curved surfaces were smooth. The edges of the rotation knob were sharp with a 90oC angle. After cooling down, pattern shrink was found in different sections of the rotation knobs. The shrink was not uniform and varied between 0% - 1.2% between the different sections. To achieve the previously mentioned mechanical qualities and recovery rate of Zamak, a melting temperature of 420oC was applied and the ingot mold was designed with a riser and rounded edges. It is recommended to implement these factors in the final iteration of the melting setup when reprocessing Zamak with an all-in one process. The Zamak laryngoscope blades were found to be suitable for reprocessing with the “all-in-one” process if the recommendations are followed. More widespread implementation of “all-in-one” reprocessing can contribute to higher sustainability in the medical field.Biomedical Engineerin