The Salar de Atacama, at an altitude of 2,300 metres, is located approximately 200 kms inland from the Pacific coast. The basin covers an area of about 3,000 km2 with a salt nucleus covering 1,400 km2. At the northern end of the nucleus a drill hole was still in salt when terminated at 1,000 metres.
The Salar was first developed by Foote Minerals in partnership with CORFO, a Government agency, in 1984. Subsequently CORFO sold its interest to Foote and later Foote was acquired by Cyprus Minerals then by Chemetall and finally by Rockwood Holdings.
To the writers knowledge the reserve data were never published but are estimated at 500,000 tonnes Li prior to the commencement of production. The company co-produces about 80,000 tpa of potassium chloride.
In 1986, Amax Exploration together with a Chilean partner reached an agreement with CORFO regarding the possible development of much of the rest of the salar but their rights were later acquired by Sociedad Quimica y Minera (SQM) a major producer of nitrates and iodine.
The initial reserves, over 790km2, were calculated at 26.0 million tonnes of potassium and 1.8 million tonnes of lithium at an average grade of 0.18%Li. These were in respect of the uppermost 40 metres of the aquifer.
SQM developed the project in two phases. The first in the area of highest grades of potassium for the production of potassium chloride and lithium, the second in an area of high sulphate values from which they recover potassium sulphate and boric acid. Lithium, currently, is recovered only from the more southerly well field/solar pond system although the feed grade at the northern location, at about 0.11% Li is considerably higher than those at the Argentinian salares.
Large quantities of lithium are returned to the salar as the quantities of brine pumped to produce in excess of 800,000 tpa of the two potash products contain much more lithium than the installed lithium pond and plant capacity.
In 2008 SQM (personal communication) revised the reserve estimate for its block of claims resulting from the inclusion of brine to a depth of 200 metres. This new estimate is for 77.2 million tonnes of potassium and 6.0 million tonnes Li.
The total reserves of the Salar de Atacama are unknown. In addition to the tonnages beneath the Rockwood and SQM mining claims covering 957km2, there are “buffer zones” between the properties covering approximately 100 km2 and there are unclaimed areas to the north of the SQM claims with lithium values in excess of those in the Argentinian salares. A tentative total for these other areas is 400,000 tonnes Li taking the total to 6.9 million tonnes.
Other Chilean salares including Pedernales, Punta Negra, Maricunga and Incahuasi, are lithium containing.