The process involves pumping up lithium rich brine from below the ground into shallow pans. Water is evaporated thanks to the strong sun and dry air. The brine contains many different dissolved ions, and as the concentration increases, salts precipitate out of solution and sink. The remaining liquid (the supernatant) is used for the net step. In the first pan, halite (sodium chloride or common salt) crystallises. This has insufficient economic value and is discarded. The supernatant, with ever increasing concentration of dissolved solids, is transferred successively to the Sylvinite (sodium potassium chloride) pond, the Carnalite (potassium magnesium chloride) pond and finally a pond designed to maximise the concentration of lithium chloride. The process takes about 15 months. The concentrate (30-35% lithium chloride solution) is trucked to Salar del Carmen. There, boron and magnesium are removed before, by addition of sodium carbonate, the desired lithium carbonate is precipitated out. SQM sells potassium chloride made from Sylvinite and potassium nitrate derived from the Carnalite.