Application of nanofiltration for Rare Earth Elements recovery from coal fly ash leachate: Performance and cost evaluation


Mutlu B. , Cantoni B., Turolla A., Antonelli M., Hsu-Kim H., Wiesner M. R.

CHEMICAL ENGINEERING JOURNAL, vol.349, pp.309-317, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 349
  • Publication Date: 2018
  • Doi Number: 10.1016/j.cej.2018.05.080
  • Title of Journal : CHEMICAL ENGINEERING JOURNAL
  • Page Numbers: pp.309-317
  • Keywords: Coal combustion residues, Critical elements, Membrane technology, Response surface methodology, Cost model, SUPPORTED LIQUID-MEMBRANE, BATH WASTE-WATER, FLUX DECLINE, HOLLOW-FIBER, BIOSORPTION, SEPARATION, METALS, IMPACT, IONS, PRECONCENTRATION

Abstract

This work evaluated nanofiltration (NF) as a potential step in the recovery process of Rare Earth Elements (REEs) from leachates of coal combustion fly ashes. A pre-treatment step, by pH adjustment and microfiltration (MF), has been studied to separate REEs by major elements. The individual and combined effects of applied pressure (12-24 bar) and NF feed acidity (pH 1.5-3.5) on rejection of six critical REEs and permeate flux have been investigated via response surface methodology (RSM). The resulting model equations were used to develop a cost model for the recovery chain, in order to select the optimum NF operating conditions. The optimization of the REE recovery chain, including pre-treatment and NF, was done with respect to the objective of maximizing the difference between NF concentrate economic value and treatment cost. NF with an appropriate MF pre-treatment has been effective in concentrating REEs from fly ash leachate, reaching the maximum potential gain at the optimum operating conditions of 12 bar and pH 3.5.