- Rock salt
Rock salt is the most present mineral in salt deposits. Rock salt which is sodium chloride NaCl has the following composition – almost 40% of sodium and 60% of chloride, often contains also admixture of calcium chloride and magnesium chloride. It is extracted from underground mines in a form of blocks or stones. It can be transparent (in its clean form) or dyed grey, red, brown or blue depending on other substances. It is perfectly soluble in water. Salt can be received in two ways. One is extraction from deposits, second – from sea water. In mines usually a chamber method is applied. In order to uncover a deposit a mine shaft is digged and salt is gradually extracted from so called chambers – rooms which are 20 m wide, 20 m high and over 100 m long. Extracted salt has crystals in different sizes, from dust size to big grains. This salt is next minced, sieved and cleaned.
- Evaporated salt
Evaporated salt is a cleaned rock salt. It contains at least 99,9% of sodium chloride. Evaporated salt is used as a spice and ingredient of many processed food products. Its food value is decreased by lack of microelements present in natural rock salt but its taste is improved, more salty comparing to rock salt, which can be a bit bitter. Evaporated salt is artificially enriched with iodine. Extraction of vacuum salt takes place by extraction of so called brine, its evaporation and crystallization to the clean edible salt. Brine is placed in containers and then chemically clarified. Clean salt solution is transported to the evaporator plant, where it is heated to the boiling point. Salt is crystallized to small crystals with 2-3 % water content and then dried in 200 0 C. This way salt with 99 % NaCl is obtained.
- Sea salt
First mentions about the beginnings of sea salt production come from the 2nd century. Sea salt is more valuable from rock salt because it contains only 34 % of sodium chloride and has various microelements. This salt is obtained by a natural method, by evaporating sea water in sun or by an artificial method, in special evaporators. Salt evaporation ponds also called salterns are shallow artificial ponds designed to extract salts from sea water. In both methods water must be heated by solar energy or flame. The higher temperature of evaporation process, the more gentle, whiter and cleaner salt is obtained. Sea salt has a natural content of iodine but depending on the location it is only 0,5 to 5 mg/kg of salt.