Leblanc process

The Leblanc process is a historical process for the recovery of soda. It was developed in 1791 by Nicolas Leblanc.

First technical sodium chloride is treated with hot sulfuric acid, thereby escaping hydrogen chloride gas, and it is sodium sulphate as " salt cake " back:

This reaction had been discovered around 1655 by Johann Rudolph Glauber, Leblanc's own contribution, however, the subsequent next step in which the CD is burned mixed " salt cake " with lime and coal. The carbon is oxidized to carbon dioxide and reduces sulfate to sulfide. The remaining " black ash " soda ash and calcium sulfide.

In contrast to calcium sulfide, which is like the lime used water-insoluble, water-soluble soda can be easily separated by washing from the other components and also the water itself will eventually be removed by boiling.

The Leblanc process was initially by the escaping hydrogen chloride gas very damaging to the environment, and also the tilted at Halden calcium sulfide focused his weathering toxic hydrogen sulphide.

After the Solvay process was compared to the Leblanc process recovered for soda manufacture the upper hand, the initially liberated hydrogen chloride gas and hydrochloric acid obtained from him to continue with the main products of the Leblanc process was. You put it forth in a large scale chlorine and chlorinated lime before you began to gain in other ways, eg by chlorine -alkali electrolysis, even these products.

With today's technical possibilities would see engineers in the Leblanc process, a renewed perspective, to establish in countries with significant Na2SO4 deposits an inexpensive and against the Solvay process more environmentally friendly production of soda ash. The process of carburization is the same, but the CO2 is kept under pressure in solution and then falls as NaHCO3 (like in the Solvay process ). The calcium sulfide is separated and finally oxidized to calcium sulfate ( gypsum), which is a valuable resource in the affected (mostly developing) countries.