Direct preparation of LiOH from α-spodumene with improved autoclave dissolution in NaOH−Na2SO4−CaO system

An alkaline autoclave dissolution method was developed to directly extract LiOH from α -spodumene in NaOH−Na 2 SO 4 −CaO system. Approximately 90.3% Li, 10.27% Si, and 9.62% Al were leached under optimal conditions: ore to CaO mass ratio of 1:1, liquid-to-solid ratio of 14 mL/g, NaOH and Na 2 SO 4 mass concentrations both of 15% at 280 ℃ for 3 h. Notably, the addition of Na 2 SO 4 was found to selectively replace Li + while simultaneously reduce NaOH consumption. Kinetic analysis was also provided further insight into the dissolution behavior of α -spodumene in this system. This innovative autoclave process can eliminate the energy-intensive high-temperature calcination for phase transformation, and enables the direct preparation of LiOH · H 2 O from α -spodumene.