Industrial extraction of lithium from Urmia Lake using precipitation and evaporation methods

Recent surges in lithium driven by battery technologies have spurred interest in recovering lithium from unconventional sources. This study presents a sequential chemical process for lithium extraction from Iran's Urmia Lake brine, a resource characterized by a high Mg/Li mass ratio of approximately 440. An economically optimized pre-treatment route involving Ca(OH)₂​, H₂SO₄​, and NaOH successfully removed 99.5% of Mg²⁺ and 97% of Ca²⁺, with an associated lithium loss of 17.9%. Controlled evaporation concentrated the purified brine to 382 ppm Li⁺ at an optimal concentration factor (CF = 3.409), a trade-off that incurred a further 33% lithium loss to prevent excessive co-precipitation at higher CFs. Two final recovery methods were evaluated: phosphate precipitation, yielding a 21.6% overall process recovery, and a more effective reaction-coupled LiAl-LDH synthesis, which achieved a 42.7% overall recovery under an optimized 3 h reaction. The primary limitation for the promising LDH route was identified as phase competition from alunite and irreversible Li₂O formation at longer reaction times. While the achieved yield is competitive with similar brines, it remains below the commercial threshold, highlighting the need for future optimizations focused on mitigating losses during evaporation and improving LDH synthesis selectivity.