Analysis of Lanthanum and Cobalt Leaching Aimed at Effective Recycling Strategies of Solid Oxide Cells

Abstract

Lanthanum and cobalt are Critical Raw Materials and components of Solid Oxide Cells—SOCs electrodes. This review analyses lanthanum and cobalt leaching from waste materials (e-waste, batteries, spent catalysts), aiming to provide a starting point for SOC recycling, not yet investigated. The literature was surveyed with a specific interest for leaching, the first phase of hydrometallurgy recycling. Most references (86%) were published after 2012, with an interest higher (85%) for cobalt. Inorganic acids were the prevailing (>80%) leaching agents, particularly for lanthanum, while leaching processes using organic acids mostly involved cobalt. The experimental conditions adopted more diluted organic acids (median 0.55 M for lanthanum and 1.4 M for cobalt) compared to inorganic acids (median value 2 M for both metals). Organic acids required a higher solid to liquid ratio (200 g/L), compared to inorganic ones (100 g/L) to solubilize lanthanum, while the opposite happened for cobalt (20 vs. 50 g/L). The process temperature didn’t change considerably with the solvent (45–75 °C for lanthanum, and 75–88 °C for cobalt). The contact time was higher for lanthanum than for cobalt (median 3–4 h vs. 75–85 min). Specific recycling processes are crucial to support SOCs value chain in Europe, and this review can help define the existing challenges and future perspectives.

Ultrasonic decoating as a new recycling path to separate oxygen side layers of solid oxide cells

“…On the other hand, hydrometallurgy requires large amounts of acids or organic solvents, which generate environmentally hazardous residues. A starting point for a hydrometallurgical process for oxygen side recycling was provided by Benedetto Mas et al 26 They reviewed the literature for methods to leach lanthanum and cobalt from waste materials. The aim was to provide guidance in defining experimental conditions for an efficient and green process to recycle lanthanum and cobalt from perovskite materials from SOC.…”

Recycling and Reuse Strategies for Ceramic Components of Solid Oxide Cells

“…The slurry is fabricated to green tapes and reprocessed to substrate by conventional methods such as tape casting and sintering. The dissolved air-side perovskites can be recovered as precursors in a variety of methods, including solvent extraction, ion exchange resins, or precipitation (6). However, the perovskite recovery will not be part of this study but will focus on the recovery of solid remains within the SOC cycle.…”