Calculations on Chemicals, Water, and Energy Consumption for the Evaporitic Process for Lithium Carbonate Recovery from Brines: A Baseline for Technology and Environmental Impact Assessment

Abstract

The evaporitic technology for the processing of lithium rich natural brines has been under scrutiny for its environmental impacts. A system of mathematical formulas has been derived to calculate the consumption of chemicals, and energy requirements in the process. Calculations were based on fundamental chemistry of alkaline and alkaline earth elements in concentrated aqueous solutions, and physicochemical data for high salinity solutions. Equations also allow for the calculation of generated solid waste, evaporated water and the volume of native brine required for a given annual production. A sensitivity analysis is presented, that allows for establishing boundary consumptions. The methodology was applied to two case studies Clayton Valley in the USA, and Atacama in Chile. The largest energy input corresponds to heating the concentrated brine. The energy required for native brine pumping is largely dependent on well depths, lithium compositions in the native and concentrated brines, and the percentage of lithium recovery. These last variables also determine the amount of lost water, ranging from 115 to 550 m3 per tonne of lithium carbonate.