Recovery of Lithium Carbonate from Dilute Li-Rich Brine via Homogenous and Heterogeneous Precipitation

Abstract

An extensive experimental campaign on Li recovery from relatively dilute LiCl solutions (i.e., Li+ ∼ 4000 ppm) is presented to identify the best operating conditions for a Li2CO3 crystallization unit. Lithium is currently mainly produced via solar evaporation, purification, and precipitation from highly concentrated Li brines located in a few world areas. The process requires large surfaces and long times (18–24 months) to concentrate Li+ up to 20,000 ppm. The present work investigates two separation routes to extract Li+ from synthetic solutions, mimicking those obtained from low-content Li+ sources through selective Li+ separation and further concentration steps: (i) addition of Na2CO3 solution and (ii) addition of NaOH solution + CO2 insufflation. A Li recovery up to 80% and purities up to 99% at 80 °C and with high-ionic strength solutions was achieved employing NaOH solution + CO2 insufflation and an ethanol washing step.

Sustainable Lithium Recovery from Hypersaline Salt-Lakes by Selective Electrodialysis: Transport and Thermodynamics

“…Our results reveal that the Li + /Mg 2+ ratio increased from 0.57 in the feed stream to 4.01 in the product stream, suggesting that the resulting product is sufficiently pure for DLE. 17 Further, our model suggests that a photovoltaic farm with a total footprint between 11.35 to 12.84 km 2 operating for 10 h daily on existing salt flats can generate the required electrical work to sustain continuous Li concentration in the Chilean salt lake. 88 The normalized land requirement (A Li , eq 20 in Supporting Information) for ED is calculated to be between 1.21 and 1.67 m 2 mol −1 , which is less than 1% of the corresponding value of 3.34 × 10 2 m 2 mol −1 obtained for the current evaporative practices in Chile.…”

“…To avoid the problems of evaporation ponds, lithium can instead be recovered with a direct lithium extraction (DLE) technology. In DLE, ionic liquids, eutectic solvents, − fractional crystallization, − electrochemical absorption , and chelating agents , are utilized either separately or synergistically to isolate lithium from a multicomponent mixture (e.g., Na + , K + ). Further, by avoiding brine evaporation altogether, DLE can be viable for dilute lithium sources .…”

“…1,17,24 DLE methods to isolate Li from a Na-rich mixture typically require the Li + /Mg 2+ ratio of the brine to be greater than approximately 4 to minimize chemical usage for precipitation and/or solvent recovery. 17,21 To enhance the selectivity and the atomic efficiency of DLE, the salt-lake brine can be pretreated with membrane processes like nanofiltration (NF) 25−28 or electrodialysis (ED) 29−32 to eliminate multivalent cations. The prospect of ED for lithium concentration from salt-lakes is particularly promising because of its successful commercial history in salt production from hypersaline brines.…”

Perspective in resource recovery from reverse osmosis brines: the case for sustainable seawater refineries for small islands

“…39 Additionally, this process is very time-consuming and only recommended for large-scale desalination plants incorporating modified precipitation methods. 42 Extraction of lithium from seawater brines by electrosorption is suggested. The technique involves the use of an electrostatic force from an external source to attract ions based on their charge to specifically designed electrodes.…”

“…These pits take a lot of space, which is the reason why these setups are found in remote wastelands 39 . Additionally, this process is very time‐consuming and only recommended for large‐scale desalination plants incorporating modified precipitation methods 42 …”