In this post you can read about
- Salt – (sodium chloride)NaCl
- Glauber’s salt– (sodium sulphate). Synthesised from salt but also occurs naturally. A good laxative. Discovered by Johann Glauber. Chemical formula Na2SO4.
- Soda Ash/Washing soda – sodium carbonate. Synthesised from sodium sulphate but can also be obtained from the ashes of plants and natural deposits. Chemical formula Na2CO3.
- Bicarbonate of soda (sodium bicarbonate) Synthesised from sodium sulphate but also occurs naturally. Chemical formula NaHCO3.
- Caustic soda (sodium hydroxide)NaOH
Uses of sodium carbonate today
Overall, about 50% of the total production of sodium carbonate is used to make glass, 18% to make other chemicals and 10% in soaps and detergents.
Annual production of sodium carbonate
|World||50 million tonnes|
|Europe||10 million tonnes|
|US||11 million tonnes|
|Russia||0.71 million tonnes1|
1. Federal State Statistics Service: Russian Federation 2011
There are two main sources of sodium carbonate:
a) from salt and calcium carbonate (via the ammonia soda (Solvay) process)
b) from sodium carbonate and hydrogencarbonate ores (trona and nahcolite)
Soda ash was called so because it was originally extracted from the ashes of plants growing in sodium-rich soils, such as vegetation from the Middle East, kelp from Scotland and seaweed from Spain.
Soda ash or washing soda was originally made from the ash of of plants. The land plants (typically glassworts or saltworts) or the seaweed (typically Fucusspecies) were harvested, dried, and burned. The ashes were then “lixiviated” (washed with water) to form an alkali solution. This solution was boiled dry to create the final product, which was termed “soda ash;” this very old name refers to the archetypal plant source for soda ash, which was the small annual shrub Salsola soda (“barilla plant”).
The ashes of these plants were noticeably different from ashes of timber (used to create potash)
The plants were harvested, dried, and burned. The ashes were then washed with water and boiled dry.
The final product the soda ash could be anything from 2 to 30% sodium carbonate.
It is obvious that extracting soda ash from plants was a limited and uncertain process.
Sodium carbonate (soda ash) and its derivatives were needed for the manufacture of glass, textiles, paper, soap, and other products.
So the search began for a better source and a way of synthesising soda ash.
Le Blanc Method
In 1775 the French Royal Academy offered a prize to anyone who could develop a process for transforming common salt (sodium chloride) into soda ash (sodium carbonate).
Le Blanc won
The Leblanc process worked as follows
He reacted sea salt (sodium chloride) with sulfuric acid in a reverberator furnace to form sodium sulfate.
Roasting the sodium sulphate with crushed limestone and coal produced calcium sulfide. This could be further treated to make
- Washing soda (sodium carbonate) used in the manufacture of glass.
- Bicarbonate of soda (also known as sodium bicarbonate, sodium hydrogen carbonate, or sodium acid carbonate) used for many things
Sodium carbonate could then be treated to make caustic soda (sodium hydroxide) or lye which could be used to make soap.
Was invented by the Belgian chemist Ernest Solvay (1838–1922) and patented by him 1861.
By 1913 the process was producing a large part of the world’s sodium carbonate.”
Uses limestone, salt and ammonia..
Very basically, ammonia is added to a salt – like table salt. Carbon dioxide is bubbled through the solution producing sodium bicarbonate.
Sodium bicarbonate. is then heated and transformed into washing soda (sodium carbonate)
Long story short, Hou’s process is an upgradation of the Solvay process. The first few steps remaining the same, carbon dioxide and ammonia are pumped into the solution instead of limestone. Further, sodium chloride is added and this solution is left to saturate at 40ºC. It is then cooled to 10ºC and recycled to produce sodium carbonate. Ammonium chloride also precipitates in this process.
A refined version of the Solvay Process is still used today.
Trona ore that is mined, then heated until it turns into soda ash also known as washing soda. Bicarbonate of soda is obtained through the same process
Large natural deposits found in 1938, such as the one near Green River, Wyoming, have made mining more economical than industrial production of washing soda in North America at least.
The USD 400m plant uses solution mining to extract the Trona-brine, a new process with high efficiency and large capacity for production.
Trona dates back 50 million years, to when the land surrounding Green River, Wyoming, was covered by a 600-square-mile (1,554-square-kilometer) lake. As it evaporated over time, this lake left a 200-billion-ton deposit of pure trona between layers of sandstone and shale. The deposit at the Green River Basin is large enough to meet the entire world’s needs for soda ash and sodium bicarbonate for thousands of years… Trona is mined at 1,500 feet (457.2 meters) below the surface. FMC’s mine shafts contain nearly 2,500 (4,022.5 kilometers) miles of tunnels and cover 24 square miles (62 square kilometers). Fifteen feet (4.57 meters) wide and nine feet (2.74 meters) tall, these tunnels allow the necessary equipment and vehicles to travel through them.” Read more: http://www.madehow.com/Volume-1/Baking-Soda.html#ixzz400Q1aQot
It is also mined out of certain alkaline lakes such as Lake Magadi in Kenya by using a basic dredging process and it is also self-regenerating so will never run out in its natural source.
Eti Soda Inc. started production in 2009 at its new facility based in between Anakara and Istanbul in the Beypazari Trona Bed, the second largest known reserves of Trona in the world.
The Solvay method was the main way of obtaining of washing soda before the Wyoming trona deposits were discovered. Now it is cheaper to mine Trona ore. In the U.S at least. The Solvay method is still used to manufacture tons of product.
There are claims that the Solvay method is less environmentally safe than mining and could cause serious waste management problems. On the other hand the mining process is accused of being heavily polluting.
Bicarbonate of Soda can be mined directly from the ground as Nahcolite.
Caustic Soda The Leblanc and Solvay processes were eclipsed by new electrolytic methods for making chlorine and caustic soda.
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