AZL General Discussion, page-20017

Seawater has 70 plus elements in it. These elements excluding the water weight about 35 kilos per cubic metre of which circa 85% is sodium chloride. Calcium, Magnesium, potassium, bromine and sulphate make up the majority of the remaining weight. You have to get value for the water and any water over a dollar a cubic metre starts to be a liability at viable scale. You have to get value for the sodium chloride and the only way that is possible is to get near pure sodium chloride and be within 10,000Km shipping distance and have 18m deep ports. So you can only realistically harvest 75-80% of the NaCl. If you cannot get it FOB for less than $US30/tonne it is a liability. If you can get your costs below $1/M3 for water and the NaCl below $30/tonne FOB, then there is more money available in the magnesium, potassium, bromine and sulphate. There are three other elements worth extracting and the rest including lithium are nuisance value only. To start with you have to get electricity down to $20/MWh. And it has to be green.
To be viable you need to be producing 5Mtpa of 99.7% pure NaCl. That is 200,000 M3 of water per day that you have to find a home for. And less than 50 tonne of lithium per annum. You cannot ever convince me of the viability of extracting lithium from seawater.