Screening life cycle assessment of rare earth elements concentrate production from mining waste, covas, Portugal

Abstract

Rare Earth Elements (REE) are crucial for modern technologies and renewable energy application, while there is a high risk of supply. REEs have been identified as critical raw materials for the development and the European Union economy competitiveness. Currently, China dominates the market of REEs production and refining. However, there are several REE containing materials not being properly addressed. The ENVIREE project, funded by the ERA-MIN programme, is focused on REE supply for Europe, by addressing the exploitation of industrial secondary sources, such as tailings and mining waste. The ENVIREE project aims at inventing the innovative recovery processes of REE from secondary sources. Within the project physical and chemical pre-treatment, novel leaching and selective separation of the metals are being investigated. The beneficiation methods involve various processes such as grinding, crushing, magnetic separation, flotation. Within the ENVIREE project two secondary sources have been identified as rich in REEs: tailings from New Kankberg (Sweden) and Covas (Portugal). Considering the fact that these sources show completely different physical and chemical properties, their beneficiation processes differ significantly. In order to ensure a holistic view of the developed processes, the assessment of environmental impacts is included in the project objectives. Life Cycle Assessment (LCA) methodology is employed to be sure that recovery processes are environmentally feasible and friendly. The aim of this paper is to report the Life Cycle Assessment of beneficiation processes developed for tailings from Covas, Portugal. Life cycle impact assessment results are calculated using SimaPro software and ReCiPe method. The functional unit is 1000 kg of a secondary material excavated and preprocessed, then directed to subsequent processes of REE recovery. The system boundaries include excavation and transport of old tailings to processing facility, 4 stages of beneficiation: size reduction and classification, gravimetric separation, magnetic separation, filtration, post-processing residues deposition and reclamation.