Leblanc process

In addition in Egypt, naturally occurring sodium carbonate, the mineral natron, was mined from dry lakebeds.

[2][3] In 1783, King Louis XVI of France and the French Academy of Sciences offered a prize of 2400 livres for a method to produce alkali from sea salt (sodium chloride).

Leblanc's contribution was the second step, in which a mixture of the salt cake and crushed limestone (calcium carbonate) was reduced by heating with coal.

Likewise, by 1874 the Deacon process was invented, oxidizing the hydrochloric acid over a copper catalyst: The chlorine would be sold for bleach in paper and textile manufacturing.

The sodium chloride is initially mixed with concentrated sulfuric acid and the mixture exposed to low heat.

However, French Revolutionaries seized the plant, along with the rest of Louis Philip's estate, in 1794, and publicized Leblanc's trade secrets.

[5] The first British soda works using the Leblanc process was built by the Losh family of iron founders at the Losh, Wilson and Bell works in Walker on the River Tyne in 1816, but steep British tariffs on salt production hindered the economics of the Leblanc process and kept such operations on a small scale until 1824.

Muspratt's Liverpool works enjoyed proximity and transport links to the Cheshire salt mines, the St Helens coalfields and the North Wales and Derbyshire limestone quarries.

[citation needed] In 1861, the Belgian chemist Ernest Solvay developed a more direct process for producing soda ash from salt and limestone through the use of ammonia.

Additionally the Brunner Mond Solvay plant which opened in 1874 at Winnington near Northwich provided fierce competition nationally.

The development of electrolytic methods of chlorine production removed that source of profits as well, and there followed a decline moderated only by "gentlemen's' agreements" with Solvay producers.

The last Leblanc-based soda ash plant in the West closed in the early 1920s,[3] but when during WWII Nationalist China had to evacuate its industry to the inland rural areas, the difficulties in importing and maintaining complex equipment forced them to temporarily re-establish the Leblanc process.

This solid waste (known as galligu) had no economic value, and was piled in heaps and spread on fields near the soda works, where it weathered to release hydrogen sulfide, the toxic gas responsible for the odor of rotten eggs.

An 1839 suit against soda works alleged, "the gas from these manufactories is of such a deleterious nature as to blight everything within its influence, and is alike baneful to health and property.

The herbage of the fields in their vicinity is scorched, the gardens neither yield fruit nor vegetables; many flourishing trees have lately become rotten naked sticks.

It tarnishes the furniture in our houses, and when we are exposed to it, which is of frequent occurrence, we are afflicted with coughs and pains in the head ... all of which we attribute to the Alkali works.

To comply with the legislation, soda works passed the escaping hydrogen chloride gas up through a tower packed with charcoal, where it was absorbed by water flowing in the other direction.

The chemical works usually dumped the resulting hydrochloric acid solution into nearby bodies of water, killing fish and other aquatic life.

[16] Sometimes, workmen cleaning the reaction products out of the reverberatory furnace wore cloth mouth-and-nose gags to keep dust and aerosols out of the lungs.