Extracting lithium from brine is cleaner than e.g. extraction from spodumene ore. Also direct lithium extraction from brine is faster, cleaner, smaller footprint, lower energy consumption.
Someone was telling me a proposed hard rock lithium mine in the US would be powered by burning sulfur. They need the sulfuric acid so produced to dissolve the spondumene anyway, and trucking in solid sulfur is cheaper than trucking in the sulfuric acid made elsewhere.
Sulfur, currently extracted by desulfurization of oil and gas, gets more expensive in the post fossil fuel society, but there are other sources (like pyrite).
