Water recovery via solar evaporation systems coupled to lithium mining from brines

BASPINEIRO, CELSO F.; FRANCO, JUDITH; FLEXER, VICTORIA

Santiago de Chile

Conferencia; ISES Solar World Conference 2019; 2019

International Solar Energy Society

Extraction of lithium from continental brines is becoming a focus of importance worldwide. This is a vital raw material for the fabrication of lithium-ion batteries. The continued availability of lithium salts can only rely on a strong increase of mining and ore processing. Currently slightly more than half of the world production of lithium salts is extracted from brines, a practice that evaporates on average half a million litres of water per ton of lithium carbonate in highly desertic regions with intense solar irradiation and fresh water scarcity. Taking into account the sustainability of the overall process with particular emphasis to water usage in relation to mining processes, we observe a potential link between lithium extraction from brines and desalination technologies. We consider here the possibility of recovering fresh water either in the current extractive process or with new extractive technologies, achieving a double objective: production of pure lithium salts and desalinated water.There are several reported desalination technologies, and considering the high salinity of lithium rich brines, on average 300 g L-1 TDS, it is necessary to determine which of the already existing desalination technologies could be efficiently merged or coupled with lithium extraction in technical and economic terms. According to type of energy used and the climatic conditions mentioned, it is logical to think first of thermal solar desalination methods.In this work, an experimental and theoretical analysis of brine desalination in the Cauchari Salar, in northwest Argentina, the performance of a simple solar still was analysed. The evaporation rate of the brine in the solar still was compared with the natural evaporation rate from open surface brine. Thermodynamic calculations to assess the least work of separation for fresh water and residual salts complement the analysis.