Environmental and Life Cycle Assessment of Lithium(I) Carbonate Production from Lithium(I) Containing Brines
Authors: He Zijing , Korre Anna , Kelsall G. H , Colet Lagrille Melanie 
Published: December 2024

Lithium(I) consumption is predicted to continue growing exponentially to support the rapidly expanding lithium-ion battery (LIB) market. Extracting Li(I) from lithium(I)-containing brine is commonly used for production of battery-grade Li2CO3, an essential component in LIB production. Lithium(I)-containing brine resources are abundant in a specific region in South America, often referred to as the Lithium Triangle, including the Chilean Atacama Desert.

This study aims to establish a detailed and up-to-date life cycle inventory (LCI) of battery-grade Li2CO3 production from brine in Chile’s Atacama Desert based on parameter modelling, literature, technical reports, and Ecoinvent database. The comprehensive analysis of the environmental impacts conducted includes brine production and modelling evaporation through three scenarios: engineering calculations, Penman equation and measured data. Rates of evaporation of brine are influenced by weather and salinity changes, so corrections to data are necessary. Process modelling was conducted in Aspen Plus and the modelling method was set as ELECNRTL. The northern Chile electricity grid was modelled, as was the water footprint (WF) of the production process. Once emissions are estimated, the LCA modelling software Sphera is used, according to ISO 14040, with the functional unit set to the production of 1 kg of battery-grade Li2CO3. Based on the ReCiPe 2016 v1.1 midpoint characterisation method and AWARE method, the environmental impacts and water scarcity footprint (WSF) have been analysed and will be presented.

The results showed that most of the environmental impacts arose from sodium hydroxide (NaOH), sodium carbonate (Na2CO3), water and electrical energy consumption for the entire Li2CO3 production process. Solvent extraction is used to remove borates from the brines, requiring aqueous NaOH for re-extraction from the organic solvent. The major contribution is from the chlor-alkali electrolytic process for NaOH production. Na2CO3 is required for removal of MgII and CaII aqueous species as corresponding carbonate precipitates, and for Li2CO3 formation. The required process water was used as a solvent and as wash water. The northern Chile electricity grid is powered by 48.46 % natural gas and 34.8 % hard coal, as well as 8.7 % photovoltaic energy. The overall global warming potential (GWP) of the process was 5.82 kg CO2 (kg Li2CO3)-1. 75.84 % of the GWP was incurred by NaOH production, 14.01 % by Na2CO3 production and 8.30 % by electrical energy generation; other components contributed < 5 %. The environmental impacts of the mining and evaporation processes were caused primarily by electricityconsumption, whereas the GWP of the Li2CO3 chemical production process was determined mainly by the chemicals used.

The results also showed that in waste management, the infiltration caused by waste piles accumulated near the production site and surface impoundments has an insignificant impact, although large areas of land are occupied. For WF and WSF, the blue WF, which is the consumption of surface and ground water, was 0.16 m3 (kg Li2CO3)-1 and the chemical production process blue WF accounted for 87.50 %. NaOH production in chlor-alkali processes consumes water by the reaction 2H2O + 2e- → H2 + 2OH-, accounting for 74.8 % of the blue WF of the chemical production process. Hence, oxygen diffusion cathodes are advocated to decrease specific electrical energy consumptions by ca. a third by substituting the above cathode reaction by: O2 + 2H2O + 4e- → 4OH-, so decreasing CO2 emissions and enabling GWP savings of 24.1 %. Additionally, comparison of H2O to OH- ratios between conventional membrane chlor-alkali processes (H2O : OH- = 1) and those utilizing oxygen reduction cathodes (H2O : OH- = 0.5) indicates water consumption could be decreased.

Despite the small amount of WF, the impact on water scarcity was 13.1 m3 world equivalent per kg Li2CO3 in this arid desert, so it is essential to decrease water consumption and increase its recycling. The comparative performance of different modelling approaches for the LCI parameters, combined with the borate re-extraction overlooked in previous such LCA studies, has enabled a more detailed LCI and environmental assessment which can identify hotspots and decrease water consumption and environmental impacts. However, further work is needed to simulate and compare the environmental impacts, water consumption, and economic benefits of selective lithium(I) recovery from brines by electrochemical processes and by conventional evaporation methods.