Pre-concentration of lithium-rich brine via direct contact membrane distillation: Conditional analysis

Abstract

The objective of this study is to employ membrane distillation (MD) for the preconcentration of lithium from Salt Lake. Considering the intricate correlation between the physical properties of the solution and the operational conditions, a theoretical estimation and verification of the mass transfer coefficient in MD process are conducted using pure water. Furthermore, a comparison is made on the effects of different cross flow velocities (CFVs) and feed temperature (FT) on MD concentration for lithium chloride solutions ranging from 0.3 g/L to 5 g/L, as well as simulated Salt Lake brine. When CFVs are set at 350 mL/min, after 600 mins of MD treatment, a permeation flux of 23.91 kg/(m2·h) is achieved for a 2 g/L lithium chloride solution. In addition, when 0.3 g/L lithium chloride solution is treated by MD for 600 mins and the FT is increased from 40℃ to 60℃, the permeate flux increases linearly from 13.21 kg/(m2·h) to 42.27 kg/(m2·h), an increase of up to 220 %, and the reject rate reaches more than 99 % at this time. This study demonstrates that employing MD process in preconcentrating lithium from Salt Lake can effectively extract valuable lithium resources through downstream processes.