| Abstract Scope |
Underclay, a low-grade polymetallic resource, has been identified as a potential resource for REEs. Current recovery methods involve calcination and the use of mineral acids.
This paper evaluates the feasibility of using organic acids, which potentially have a smaller environmental impact than mineral acids, as lixiviants to recover REEs from underclay and offer selectivity in mineral dissolution, potentially easing the burden on downstream processes. Five organic acids: oxalic, ascorbic, citric, malic, and tartaric are screened in a preliminary study coupled with mechanical activation of the ore. The leaching kinetics and interaction mechanisms between the organic acids and the solid material are studied through controlled leach tests, zeta potential analysis, and solution chemical equilibrium calculations. The leach residues and effluent streams are characterized using SEM, XRD, XRF, and TGA. Additionally, an economic evaluation is done to assess the operational feasibility and cost-effectiveness of using organic acids for REE recovery. |