X. Zhang, B. Abbasi, T. Hudson, B. Abbasi
Oregon State University,
United States
Keywords: lithium extraction, thermal and cyclonic concentration
Summary:
The demand of Lithium (Li) for electric vehicle (EV) batteries, grid storage, and other applications is expected to grow dramatically over the coming decade. A recent market report projected 3 times increase in EV sales to over 30 million per year by 2030. In 2018, the U.S. Department of Interior listed Li as one of the minerals “critical to the economic and national security of the U.S.”. The primary Li sources are hard-rock minerals and continental brines. Lithium carbonate (Li2CO3) produced by conventional techniques could triple in price by 2030 as demand keeps increasing. In comparison to the concentrates made from hard-rock mines, Li extraction from brines has the potential to be more profitable. This has generated great interest in extracting Li from underground brines, however the U.S. is currently underutilizing its resources, despite their abundance. Due to the cost and environmental impact of Li extraction using conventional technologies, the plant located at Silver Peak, NV is the only mass producer of Li in the U.S., amounting to less than 1% of the global output. To be commercially viable, Li concentration in brine should be in the range of 7,000 ppm. One conventional method to concentrate brine involves evaporation in solar ponds, which takes 18-24 months to reach the target. This long processing time makes it difficult to respond to market and demand fluctuations. Removal of brine pore-water, which the solar ponds do not replenish, causes aquifer compaction, and hinders further extraction of Li from brine. Other technologies such as ion exchange and electrodialysis (ED) can reduce the concentration time. However, ion exchange resins are susceptible to fouling, expensive, and not biodegradable. ED is energy-intensive, complicated to control, and requires expensive electricity infrastructure. The membranes used during ED process comprise nearly half of the equipment cost and need frequent replacement. Under U.S. Department of Energy awards, Water and Energy Technologies Laboratory (WET Lab) at Oregon State University has developed, proven, and patented an environmentally benign technology to desalinate highly saline brine and obtain potable water with no liquid discharge at lab scale. WET Lab is currently in the process of adapting, developing, and commercializing its technology to partially desalinate Li containing brines and concentrate the brine such that Li concentration increases from about 160 ppm to over 7,000 ppm, which is suitable for Li2CO3 extraction. During the Li concentration process, a newly developed anti-fouling atomizer is used to spray the brine. The atomized brine is then partially evaporated to reach the desired Li concentration. Most cations other than Li+ (Na+, K+, Ca2+, etc) oversaturate and crystallize as solid particles. Air flow carries the particle-laden stream to separate non-Li salts. Li+ is extracted for chemical treatment that precipitates Li2CO3. The containerized system is modular, portable and scalable, and eliminates the need for solar evaporation ponds, which dramatically reduces land use. This process can operate on solar, geothermal heat, or waste heat with no adverse environmental impact or emissions.