REPUTER

The REPUTER project aims at the development of an efficient, closed-loop and eco-conceived rare earth recycling and separation process from end-of-life rechargeable nickel-metal hydride (Ni-MH) batteries, starting from battery collection down to the formulation of rare earths as pure oxides or metals ready to be used in various industrial applications. Rare earth elements (REE) have become essential for our modern economy, being considered today as the most critical raw materials group with the highest supply risk. Despite this situation, the recovery of REE from Ni-MH batteries is almost non-existent (less than 1% of the REE were recycled in 2011), most of the rare earths present ending up diluted in the slags and their reuse value consequently reduced. This situation is often due to an inefficient collection and sorting process and of various technological difficulties related to REE recovery, extraction, separation and conversion to metals. Therefore, a large effort is needed for overcoming these difficulties and improving the recycling rates, in line with the goals of the EU’s Energy Roadmap 2050. In the same time, recycling activities need to be complemented with new efficient and robust environmentally-friendly separation technologies and with an expertise in the conversion of rare earth oxides into metals or alloys. The objectives of this proposal are to: (i) Reinforce through common objectives the expertise and complementary competences gained in France in hydrometallurgy (spent nuclear fuel reprocessing) and in pyrometallurgy (aluminum, sodium, zirconium industry); (ii) Remove the scientific and technical barriers currently affecting the development of REE recycling, particularly by innovating in terms of dedicated hydrometallurgical and pyrometallurgical process efficiency and compactness; (iii) Bring experimental data and evaluate the possibility to reach a sufficient purity (> 99.5%) of the recycled rare earths at a 10 to 100 gram scale in order to use these purified oxides or metals for industrial applications (catalytic materials, magnets and new batteries); (iv) Evaluate the impact of the recycling process using a life cycle analysis and a technical-economic study, allowing an extrapolation of the process to higher flows and helping the potentially interested industrial companies making an informed decision about the possible commercialization of the process. The work plan is structured into six major tasks (including project coordination). The first step covers the efficient recovery and sorting of REE-rich fractions from end-of-life Ni-MH batteries, via mechanic and thermal operations, followed by acid leaching. The second task will address the optimized extraction and separation of REE from Nickel and other transition elements present in batteries, using hydrometallurgy (liquid-liquid solvent extraction) leading to pure REE in solution. The solvent formulation will be optimized, particularly by designing and studying new selective extractant molecules allowing an efficient intra-REE separation in the presence of transition metals. The conversion of separated light REE (such as La and Ce) into oxides will be carried out in a third task, with the aim of developing ceramic oxide materials with interesting catalytic properties for further valorisation. The forth task is dedicated to the development of pyrometallurgical technologies for the conversion of RE oxides (particularly Nd and Pr) into high purity RE metals. Different types of pyrometallurgical processes mainly based on molten salt electrolysis (alkaline or alkaline-earth chlorides and fluorides) will be studied and optimized in order to propose a robust solution and reach the purity requirements for specific applications (for the NdFeB magnet industry in particular). The last task is dedicated to a life cycle analysis and technical-economic study of the processes.