Produced by the natural evaporation of seawater (or ‘brine’) in large concentration ponds, commercial salt relies on the sun and wind to provide the energy to evaporate the water and raise the concentration of salt to the point where the salt present in the water forms into a solid, a process known as crystallisation.
As the water concentrates, calcium carbonate is the first chemical to crystalize as the brine moves through a series of ponds (sometimes for as long as two years) and the chemical is thus removed from the final salt product.
Through the process of crystallization, concentration increases to such a degree that our proper brine control ensures salt purity that amounts to 99.7% sodium chloride. The crystalizing pond is then drained of the remaining brine and harvesting equipment begins stripping the newly-deposited layer of salt crystals, before being washed, crushed and dried.
Salt purity is defined by the percentage of sodium chloride in the final crystal; the higher the number, the fewer the impurities (i.e. other minerals). The purest grade of salt are ‘evaporated salts’, known to us as table salt. It is manufactured using a series of pans, which boil away the water from the salt brine, after which the brine crystalizes.
Most of the table salt in Europe, Australia, East Asia and the Americas is a product of vacuum pan refining; a process where water is evaporated from brine using steam or electric-powered vapour to recompress evaporators. Steam from boilers is fed from one evaporator to the next to increase energy efficiency and once the brine enters the crystallizer vessel, salt is precipitated. The crystalized salt is removed, scrubbed and compressed before being packaged
Mined from underground deposits through drilling and blasting, rock salt is reached through circular shafts, lined with concrete. Approximately 20 feet in diameter and often as deep as 2000 feet, the method used is dependent on the depth and location of the deposit itself.
Layered deposits use the room and pillar method, horizontal and approximately 10-25 feet high & 50 feet wide. Openings are cross-cut and between 45% – 65% of available salt is recovered; the remainder of which is left behind as pillar support for the mined area.
Several ‘rooms’ are blasted each day by diesel-powered equipment, each blast bringing down 350 – 900 tons of salt that is loaded and transported by trucks to the hoist or ‘skip’. Each skip can lift up to 20 tons of salt and with the rate at which they work, a large mine is easily able to hoist 900 tons per hour.