TY - JOUR

T1 - Towards the implementation of an ion-exchange system for recovery of fluoride commodity chemicals. Kinetic and dynamic studies

AU - Robshaw, Thomas

AU - Dawson, Robert

AU - Bonser, Keith

AU - Ogden, Mark

PY - 2019/7/1

Y1 - 2019/7/1

N2 - Spent potlining (SPL), a hazardous waste product from primary aluminium production, presents an important opportunity to recycle fluoride and conserve global fluorspar reserves. A novel strategy for treatment of the waste requires a selective fluoride-removal step from aqueous leachate. This has been demonstrated, using a Lanthanum-loaded chelating resin, in a series of kinetic and dynamic studies, with a view to industrial implementation. Kinetics could be described by the pseudo second-order model and uptake from SPL leachate was considerably higher than from equivalent NaF solutions, although observed rate constants were an order of magnitude less. Uptake of coexisting species and activation energy calculations indicated that a novel complexation interaction between La centres and aqueous aluminium hydroxyfluorides dominated the uptake process. The resin operated efficiently in column studies, with a dynamic fluoride uptake capacity of 66.7 mg g−1, calculated by the Dose-Response model, which produced the best fit to the data. The attained elution profile suggested that fluoride recovery by cryolite precipitation would be feasible, which could be recycled back into primary aluminium production or exploited as a commodity. The resin was found to have high durability in performance studies over repeated batch treatments.

AB - Spent potlining (SPL), a hazardous waste product from primary aluminium production, presents an important opportunity to recycle fluoride and conserve global fluorspar reserves. A novel strategy for treatment of the waste requires a selective fluoride-removal step from aqueous leachate. This has been demonstrated, using a Lanthanum-loaded chelating resin, in a series of kinetic and dynamic studies, with a view to industrial implementation. Kinetics could be described by the pseudo second-order model and uptake from SPL leachate was considerably higher than from equivalent NaF solutions, although observed rate constants were an order of magnitude less. Uptake of coexisting species and activation energy calculations indicated that a novel complexation interaction between La centres and aqueous aluminium hydroxyfluorides dominated the uptake process. The resin operated efficiently in column studies, with a dynamic fluoride uptake capacity of 66.7 mg g−1, calculated by the Dose-Response model, which produced the best fit to the data. The attained elution profile suggested that fluoride recovery by cryolite precipitation would be feasible, which could be recycled back into primary aluminium production or exploited as a commodity. The resin was found to have high durability in performance studies over repeated batch treatments.

KW - Spent potlining

KW - Cryolite

KW - Lanthanum

KW - Aluminium hydroxyfluorides

KW - Chelating resin

KW - Fluoride recovery

U2 - 10.1016/j.cej.2019.02.135

DO - 10.1016/j.cej.2019.02.135

M3 - Article

VL - 367

SP - 149

EP - 159

JO - Chemical Engineering Journal

JF - Chemical Engineering Journal

SN - 1385-8947

ER -