Session 3 | Assessing Recycling Systems from a Life Cycle Perspective

Presenter: Ben Amor, LIRIDE-Sherbrooke University

Co-Authors: Joris Deschamps

The government of Quebec (Canada) is trying to find a useful outlet for the mixed waste glass pilling up in its landfills. One solution to consider is the use of fine glass powder from mixed waste glass as alternative cementitious materials (ACM) in concrete, using an open-loop circular-economy principle.

To quantify the environmental feasibility of this concept, life cycle assessment (LCA) methodology, in combination with a real case study (i.e., a concrete sidewalk in Montreal, Canada) are both assessed. More specifically, two different scenarios are compared, the business-as-usual (BAU) concrete production model, and a glass powder (GP) concrete production process model. All modeling efforts are performed using SimaPro 8.2 software, the Ecoinvent 3.2 database and the IMPACT 2002 + impact method. Finally, a Monte Carlo simulation, in addition to different sensitivity analyses, are carried out to assess the influence of data uncertainty and key parameter changes, such as the distance from suppliers, potential lifetime extension of the concrete, and possible particulate emissions during GP production.

Results show the environmental benefits of using GP as an ACM in terms of every indicator. Moreover, the significant contribution of cement production in the environmental burden of concrete is noted. It appears as the main hotspot in most midpoint indicators, and in all four endpoint indicators. It is especially highlighted as a global warming indicator, with 74% of the greenhouse gasses (GHG) related to cement production for the BAU scenario and 68% for the GP scenario. The emissions of particles into the atmosphere (such as CO2, NOx, and SOx) from the clinker kiln chimney plays a major role in the overall environmental impact of concrete production. Another key result is the importance of transportation distance of the base materials, which could reverse the conclusion.

The originality of this work relies on the environmental assessment of the up-cycling of GP as a supplementary cementitious materials (SCM) in concrete. Indeed, this study allows for a better understanding of environmental impact of concrete and highlights the extent to which environmental benefits remain when mixed waste glass is used in an open-loop circular-economy context. At a larger scale, this study aims to encourage all municipalities/government that are struggling with common waste – such as mixed waste glass — to find industrial symbioses at a local scale.

Presenter: Michael Dieterle, Fraunhofer-Institut für Chemische Technologie ICT

Co-Authors: Torsten Müller, Manuel González, Ana Salles

The main objective of this work was the environmental assessment of the new technology for producing magnesium and rare-earth elements (Mg+REEs) alloying ingots developed in the EU-project REMAGHIC (New Recovery Processes to produce Rare Earth – Magnesium Alloys of High Performance and Low Cost, in the frame of SPIRE program, 01/09/2015-31/08/2018). Technologies to recover these two materials from waste sources have also been further developed within this project. The evaluation of the effective environmental performance associated with these new recovery processes supported the decision making process of selecting the most promising routes. These routes are planned to be applied in the upscaling process of the new production of Mg+REE alloying ingots. The LCA assessments were carried out following the standard ISO 14040/14044.

The scope of the LCA of the Mg recovery technologies was the assessment of the environmental profile of the production of 1 kg ingot of recovered magnesium from the available types of Mg wastes in Grupo Antolin facilities (in Spain). These ingots later will be alloyed with rare earths. The most promising waste stream of Mg recovery was based on the employment of magnesium scraps Type 1 (rejected parts, biscuits & gates, overflows), discarding the use of dross & sludges (scraps type 6A).
In the case of the rare earths recovery process developed within the project, the scope of the LCA was the environmental assessment of the production of 1 kg of REE, starting from the acquisition of powder (as waste material). The studied waste streams were fluorescent lamp phosphors, cathode ray tube (CRT) phosphors, and nickel-metal hydride (NiMH) batteries. The most promising waste stream of REE recovery was the NiMH batteries (Cerium (Ce) and Lanthanum (La), and the most promising process was based on a combination of the following three main technologies, a pyrometallurgical process to concentrate the REEs in a slag and a leaching process to extract the REEs from the slag (from Tecnalia, in Spain) and a ionometallurgical process (from KUL, in Belgium) to obtain a mixed La+Ce oxide.
These new processes to recover Mg and REE and to produce new alloys for automotive, aeronautical, and biomedical industries proven to be more sustainable in comparison to the processes associated to primary materials.

Presenter: Guido Sonnemann, University of Bordeaux, Laboratory ISM, CyVi Group

Co-Authors: Baptiste Pillain, Philippe Loubet, Cyril Aymonier

Carbon fibre reinforced polymer (CFRP) consumption has been increasing in sectors such as aeronautic, automotive or wind energy. The trend is also predicted to continue in the future. Inevitably there will be a large amount of waste from the CFRP manufacturing process and its use. This urges for the need to establish a sustainable recycling sector for carbon fibres.

Presently, different recycling processes are used, the main one being pyrolysis. Since mechanical recycling involves the grinding of CFRPs, it therefore does not make it possible to recover single fibres and causes significant fibre damages. However, new recycling processes such as solvolysis in supercritical water medium or electrodynamic fragmentation are under development.
In order to be consistent with its objective of reducing environmental impact and conserving primary resources, the environmental impacts of those recycling processes must be measured and compared with virgin fibre production. To do so, a comparative, anticipatory life cycle assessment (LCA) was conducted using Ecoinvent database as background data and experiments on site as foreground data for the supercritical water solvolysis and electrodynamical fragmentation recycling processes. The pyrolysis process and the carbon fibres productions were modelled from literature and a LCA model was used for the landfilling and incineration scenarios.

The result shows at first, higher impact from the three recycling processes in comparison to landfilling and incineration, but a second analysis considering product substitution have showed a clear advantage for the use of recycling processes as CFRP end of life scenarios. Actually, the recycling process that is able to substitute the highest amount of virgin carbon fibres rates best.

In conclusion, a number of processes are emerging in addition to pyrolysis for the recycling of CFRP. The process that is able to substitute most of the carbon fibres will be the one that has less environmental impacts.