To confirm the technical options, which emerged within the framework of the task 4.1., the assembly of a small hydrometallurgical laboratory pilot will be planned. The process validation on continuous flow will be performed. This stage will allow identifying the necessary adaptations of operating conditions to obtain comparable results than at 4.1. at larger-scale and to conclude on the various technical options. To verify the process robustness, trials may be performed on different WP3 batches. Performances will be judged solely on environmental quality of obtained materials (in terms of content
and leachable fraction) and on the ease of implementation (adaptability).