The SortCAS project created the following new knowledge and technological advancements:
1) A particle-scale model based on DEM was developed for simulating and understanding the flow behaviours of complex-shaped aluminium scraps. The model described realistic shapes of aluminium scraps by 3D scanning of real shapes, incorporated automated operations like sensing and ejection in the system, and selected parameters based on the calibration by comparing key performance indicators against the pilot-scale experiments. The design and the results generated by the model have been used in the full-scale sorting plant in the industry. Considering DEM is often regarded as less applicable for modelling full-scale industrial applications, the model and results from this work can thus advance the understanding of the particle modelling community, especially in dealing with complex particle shapes and automated systems at a full scale.
2) A singulation technology was created to regularize the flow of aluminium scraps, enabling the efficient and cost-effective sensing and sorting of aluminium scraps into specific types/products. In general, most existing vision and robotic sorting techniques require a good flow of materials preferably with minimal overlapping. To obtain a nonoverlapping flow while maintaining a high throughput is challenging, especially for complex-shaped particles like aluminium scraps. The developed singulation technology allows the flow of scraps with desirable interparticle space in a cost-effective way. This can bring new advancements into the sorting technologies for processing potentially various materials, not only metal scraps, but also E-waste, mineral ores, and building materials etc.
3) A magnetic image sensor was created for detecting small ferrous contaminants in aluminium scraps. Detecting ferrous contaminants is key to realizing high-quality aluminium scraps. Detecting small ferrous contaminants that are attached to or underneath large aluminium scraps can be difficult for vision systems, while advanced sensing by LIBS and/or XRT can be expensive. The current magnetic image sensor has been proven to be effective in sensing the small ferrous contaminants in a cost-effective way; it can also estimate the size/mass of the ferrous contaminants, which is important for estimating the purity of the sorted scraps.
4) A robotic ejection technology was developed to sort multiple types of aluminium scraps in one go. Compared with existing sorting technologies like pneumatic blowing nozzles and robotic pickers, the current robotic ejection technology/equipment is robust and accurate in sorting scraps that may have diverse properties, e.g. various shapes, surfaces, and weight. The ejection system can also be flexibly customized to sort a variable number of products (even more than 10 types), according to user needs.
The developed innovations have resulted in several patents (e.g. NL2031877B1, NL2031878B1, NL2031879B1, and WO2023224478A1), and have been implemented into a full-scale digital recycling plant at the company Myne. Such innovations are promising to advance the high-quality sorting of aluminium scraps towards circularity.