5.5 Enhancing the circularity of metals process scarp: solid state chips recycling and Industrial Symbiosis implementation 

Livan Fratini
Gennaio 2023
Giugno 2024
Università degli Studi di Palermo

Politecnico di Milano, Università degli Studi di Firenze, Università degli Studi di Brescia, Thales Alenia Space Italia S.p.A.  

5.5 Enhancing the circularity of metals process scarp: solid state chips recycling and Industrial Symbiosis implementation 

The research project addresses the theme of new forms of collaborations in the industrial context for machinery producers and original equipment manufacturers (OEMs), as a mean to create new circular factories, increasing the economic and environmental sustainability. The project will focus on three main themes of interest: new forms of collaborations, new customer needs and requirements, new enabling technologies. The project will analyze and characterize factory configurations and companies’ offerings based on the specific needs of target markets.

In details, the project aims to focus on the following elements:

  • The study and analysis of the peculiarities of Italian industrial manufacturers.
  • The study and analysis of offerings that companies can offer to their clients. This analysis will also consider the network dimensions and how companies can collaborate with each other to orchestrate their activities.
  • The exploration of how the “Made in Italy” philosophy can be applied to manufacturers’ offerings.
  • The study and analysis of selling channels through which companies can propose new forms of relationship.
  • The opportunities to increase sustainability in the proposed context.

Finally, the project will leverage on the digital technologies that enable new forms of collaboration paths and the required digital and data architecture. The themes of interest are:

  • The study and identification of enabling technologies, processes, and competences, particularly technologies for equipment data collection, storage, sharing and analysis of data.
  • The identification and characterization of relevant equipment data and how they can be leveraged in their integrated offerings.
  • The analysis of architectural alternatives to enable the sharing of data, and its integration among stakeholders within the collaborative manufacturing system.

Production of just five key materials (aluminum, steel, cement, paper, and plastic) accounts for over half of all the greenhouse gas (GHG) emissions released by industry worldwide each year. Primary aluminum production is the most energy and emissions intensive among the aforementioned materials. Aluminum production industry is responsible for about 3% of the world’s 9.4 Gt of direct industrial CO2 emissions in 2021. Since 1971, the global demand for aluminum has increased by nearly six times; although during the Covid-19 pandemic the aluminum production fell flat, it has since started growing quickly once again and global demand is likely to continue growing in response to increasing global population and GDP 2021 . The main approach for reducing the primary production and decoupling the resource depletion from the economic growth is the implementation of Circular Economy (CE) strategies. For metals recycling is still most used strategy, although for aluminum alloys the conventional remelting based route is neither energy nor resource efficient. In this respect the main drawback for the conventional recycling processes is the permanent losses occurring during melting because of the oxidation. In order to overcome such issues, researchers have turned to Solid State Recycling (SSR) strategies. Friction base Consolidation processes have proved to successfully recycle machining chips into solid blocks/billets. Specifically, Friction Stir Extrusion (FSE) and Friction Stir Consolidation (FSC) directly turn metallic chips into Wire/rod and Billets, respectively. Although the suitability of these processes for recycling has been proved, the basics of the process and the quality of the product is still to be fully understood. On the other hand, the possibility to activate industrial symbiotic link between chips recycler and companies using the recycled semi-finished product as material input is still to be fully explored. In this respect, potential link can be activated if the metallic wire based AM technologies are considered, in fact the recycled wires obtained by FSE could be used as input material for Direct Energy Deposition processes such as, WAAM, etc…

Summing up, the projects aims at increasing the TRL of the friction based SSR processes aiming at reaching the TRL4 level as well as at exploring the possibility to activate Symbiotic link between aluminum scraps recyclers by FSE and AM based companies. The project will envisage different activities: process design, process mechanics analysis trough F.E.M., Microstructures analyses, mechanical characterization, LCA analyses.


The main expected results will concern both technological and environmental aspects of FSE and FSC recycling process; a list of the main expected results follows:

  1. better understanding of process mechanics FSC and FSE processes. As far as the FSE process the main progresses are expected concerning the continuous version of the process, a set the process windows with varying material and the diameter of the rod/ wire produced will be provided.
    Concerning the FSC, improvements in hardness and grain size distribution are expected. A set of manufacturing strategies and testing procedures will be provided in order to obtain a billet closer to industrial standards.
  2. Improvement of the quality of recycled samples obtained by FSC and FSE processes. A set of measurement strategies and related performance for quantifying the quality and the robustness of the developed processes. Output metrics could be: surface quality, homogeneity in hardness and grain size distribution, robustness of the process output in terms of obtained diameter of the wire.
  3. Identification and experimental proof of concept implementation of symbiotic links between metal scraps recycler and semi-finished products utilizers: wire based AM companies, metal working companies, etc…
  4. Quantification of the environmental impact reduction in material production through Life Cycle Assessments. A set of guidelines for the environmentally friendly implementation of the identified production strategies will be developed. The overall reduction of environmental impact related
    to secondary production of metals will be thoroughly quantified.