Lithium Ark Process
from Lithium Sulfate
The lithium Ark process is able to produce lithium hydroxide indirectly from lithium sulfate by converting it to lithium chloride with calcium chloride (CaCl2)
This process is competitive due to the
a) lower reagent cost for limestone (CaCO3)
b) lower reagent cost for CaCl2 (HCl or Cl2 by-product.)
The by-product will be gypsum (CaSO4*2H20), a stable insoluble salt instead of very soluble sodium sulfate produced conventionally (causticization) by using caustic soda (NaOH) as reagent.
The process is reflected in block diagram below and the reagent consumption and energy requirements are shown in the table below comparing with the causticization process and lithium sulfate electrolysis or electrodialysis, both electrochemical processes studied since many years, without any breakthrough due to chemistry limitations.