Techno-economic Assessment for Integrating Biosorption into Rare Earth Recovery Process

The current uncertainty
in the global supply of rare earth elements
(REEs) necessitates the development of novel extraction technologies
that utilize a variety of REE source materials. Herein, we examined
the techno-economic performance of integrating a biosorption approach
into a large-scale process for producing salable total rare earth
oxides (TREOs) from various feedstocks. An airlift bioreactor is proposed
to carry out a biosorption process mediated by bioengineered rare
earth-adsorbing bacteria. Techno-economic assessments were compared
for three distinctive categories of REE feedstocks requiring different
pre-processing steps. Key parameters identified that affect profitability
include REE concentration, composition of the feedstock, and costs
of feedstock pretreatment and waste management. Among the 11 specific
feedstocks investigated, coal ash from the Appalachian Basin was projected
to be the most profitable, largely due to its high-value REE content.
Its cost breakdown includes pre-processing (leaching primarily, 77.1%),
biosorption (19.4%), and oxalic acid precipitation and TREO roasting
(3.5%). Surprisingly, biosorption from the high-grade Bull Hill REE
ore is less profitable due to high material cost and low production
revenue. Overall, our results confirmed that the application of biosorption
to low-grade feedstocks for REE recovery is economically viable.