General Information:
Salt is a transparent and fragile metal used since ancient times to give taste to food and to help in preserving it. Today, salt also gets used in the manufacture of a large number of chemicals and food products. It is made up from two elements; sodium and chlorine, which are known as, Sodium Chloride ( Na cl ). Its mineral name is Halite. Salt is usually made up of clear crystals which are almost shaped as complete cubes. It is the impurities in the salt that give its color which may be white, gray, yellow or red. Table salt appears to be white in color but is in fact composed of small transparent cubes.
Salt History:
Salt emerged since the stability of humans and was considered an essential substance for food, food preservation, food manufacture, mummification, legends and heritage and the basis for revolutions of independence as in India, The United States and France. It was also the basis of many cities and of global economic trade. Salt was considered as a precious commodity in ancient times and was exchanged with gold, ounce against ounce. Ancient Chinese and many areas around the Mediterranean used to deal with coins made out of salt. Salt, as a very precious substance, underwent a long monopoly in old times and had high taxes imposed on it because it was the most valued substance which the human was able to extract in the 19th century. In France, for example, salt had a very high tax and was monopolized by the Kings whom were fighting its smugglers. The monopoly got demolished after many revolutions and bloody riots last of which was The Great French Revolution which destroyed King Louis XVI. High tax on salt returned afterwards and remained in effect till 1946.
The Importance of Salt:
Salt is an essential substance in life and an adult human body contains an average of 100g of it. The human loses about 20-30g of salt a day through urine and sweat and therefore needs to compensate that loss through his diet.
Salt plays a key role in balancing the amount of water in the body and the cells that form it. It is also very important in the metabolic activity of cells not only in humans, but in all living organisms and is, thus, added to animal feed so as to ensure they get their dietary requirements of it.
The human body requires approximately 3-6g of salt per day to ensure the balance of brine required to perform vital functions such as regulation of the heartbeat, transmission of nerve impulses, activation of enzyme secretion and many more. Sources by which humans can obtain the required salt are through the ingestion of table salt in addition to the salt content available in many food items. Therefore, moderately consuming salt is a necessity for human survival. A deficiency in salt can cause the body several dangerous disorders which can only be cured by the compensation of the missing salt amounts.
Salt has some benefits in the making of food as it secures the taste of food and compensates for the salt that evaporated during cooking.
The advantage of table salt is the possibility of using it as a medium for group therapy whereby it is used to counterbalance Iodine deficiency cases. These cases may be accompanied by different disorders such as Thyroid Gland inflation or abnormal growth of children and an underdevelopment of their intelligence level.
Despite the importance of salt for human life, its consumption does not exceed 15% of its global production. The bulk of the remainder salt gets used up in the chemical industry where it is broken down into its constituent parts to manufacture materials of Sodium and Chlorine. A large proportion of salt is also used in the manufacture of Sodium compounds called ‘Soda’ or ‘Commercial Sodium Carbonate’ which is used primarily in the manufacture of glass and soap. Chlorine compounds are also extracted from salt and are used in the manufacture of paper, plastic, anti-pest chemicals, cleaning liquids, anti-freeze solutions and purification fluids. It is known that when salt gets mixed with ice, the freezing point of ice gets lowered and this is why salt gets sprinkled on roads when they hold up large amounts of snow. Large amounts of salt get used up this way by countries that have a high level of snowfall. Salt is also used in the refinement of ceramic, feeding of cattle, medicines, refinement of petrol, as a coolant, treatment of wastewater, dyeing of textile, tanning of leather, removal of hardness in water in addition to its uses in all types of food manufacture such as cheese and milk, bread and pastries, pickles and olives, toasters and in food preservation.
Salt Extraction Methods:
The source of all salt, including salt deposits beneath the Earth’s surface, is (Brackish) which is any type of salt water whether from the sea, ponds or other water bodies. In fact, all current salt deposits under the earth’s surface were formed whilst sea water evaporated over millions of years ago.
Biologists believe that sea water which revealed the first signs of primitive life was very salty. Each liter of it contained around 30g of salt and if sea salt was sprinkled on the surface of the globe, then a layer of 35 meters thickness would have formed over it. Scientists estimate that molten salt in the sea amounts to about thirty eight billion tons. Besides sea salt, the earth’s surface contains many layers of rock salt or mine salt which maybe equal in quantity to sea salt. Salt gets extracted in one of the following methods:
1 - Sea Salt: sea water is salty because rain water dissolves the minerals that contain Sodium and Chlorine in the rocks and soil. Rivers then carry these minerals to the sea. Evaporating sea water is the oldest way of extracting salt but this way is used in a small scale as it hasn’t proved to be very effective because sea water only contains 3.5% salt. The Dead Sea sets a world record of being the only complex holding the most saline water and of being rich in minerals. The saltiness of the Dead Sea is 10 times higher than other large seas and oceans (salt concentration in the Dead Sea is 34% and in the Mediterranean it is 3.5%). This in turn makes the Dead Sea the only one in the world suitable for bulk salt extraction as many salt clusters form directly on its beaches.
2 - Marshes Salt: This is the most popular way in the world for salt extraction. In this way, salt is extracted from lakes which have formed in low-level areas of either sea water or from rains and floods which have carried with them many materials and dissolved salts while they passed along many types of soil. Salty lakes get formed and then the salty crust gets collected after the lakes get dried out by the sun. This process is affected by the air’s temperature and the strength of the wind as they are contributing factors to the evaporation process of the water and the formation of the salty crust.
3 - Rock Salt: Is known as ‘Al Andrani’ salt and is found in solid dense layers beneath the surface of the earth. These residues have been formed through the evaporation of large portions of oceans millions of years ago. Rock salt deposits are found along with mineral deposits such as Calcium Carbonate and Potassium Carbonate which are also found in sea water. Rock salt deposits are also found in formations called ‘Salty Domes’. Salt is less dense than most other minerals and normally floats if subjected to high pressures. ‘Salty Domes’ are formed when layers of Rock Salt flow and penetrate rocks from the top. Rock Salt clusters are then extracted through mining.
Methods of Salt Manufacture: Salt is generally not valid for use right after it is extracted as it contains many impurities. Herein lies the importance of salt manufacture industry. Historians claim that the oldest salt plant was established in China. As for the oldest written record of its manufacture, it dates back to around 800B.C. and indicates that its manufacture had started 1000 years prior to that date. The salt industry has witnessed several industrial revolutions and technology advancements have also affected the processes by which salt was produced and manufactured over the years. With oil discovery and steam engines, the salt manufacture industry was transformed with the use of new technologies and the introduction of the boiler evaporation method.
The process of obtaining healthy and safe table salt which is in line with standard specifications requires following techniques of high technical specialization to extract pure salt without any other undesirable compound which may be harmful to public health and industrial products.
Salt gets manufactured in two ways:
1 - Refined Salt: This is the traditional method known since old times where raw salt gets subjected to a number of washing stages to purify it from harmful impurities such as Copper, Lead and Arsenic. These washing stages retain only a small portion of insoluble impurities ranging between 0.5-0.7%. The salt then gets dried to reduce the level of moisture in it and then gets grinded, sorted and packaged. The percentage of purity normally does not exceed 98% which makes it very rare for the salt to have a color of pure white due to some impurities which remain in it.
2 - Crystalline Salt: This is the most healthy way which since has found so far. Raw salt gets completely melted and processed to get rid of impurities so as to reach a percentage of impurities that does not exceed 0.2%. Homogenous crystal salt granules are then obtained by evaporating the melted mixture. This type of salt has an advantage of being smooth and very white in color as it has a purity percentage which could reach up to 99.9% of Sodium Chloride.
Below is a list of some of the damages which could be caused due to the accumulation of impurities normally present in raw salt:
