Le Blanc process

It should be mentioned that soap only became a mass product following development of the soda industry (Le Blanc process). There was never a shortage of fats and fatty oils, only suitable alkalies. 

Sulfuric acid (chamber process) Soda ash (Le Blanc process)... 

Sodium sulphate is an intermediate product in the manufacture of sodium carbonate by the Le Blanc process (p. 143). It is also a byproduct in the manufacture of nitric acid by the interaction of sodium nitrate and sulphuric acid 8... 

Sodium thiosulphate, Na2S203.—The thiosulphate is manufactured from the alkali-waste of the Le Blanc process by atmospheric oxidation in presence of sodium sulphate, which reacts with the calcium thiosulphate first formed to yield sodium thiosulphate 1... 

Ammonia-soda Process.—This process is said 5 to have been devised by the apothecary Gerolamo Fomi in 1836. It was perfected by Solvay, and on the continent of Europe it has largely displaced the older Le Blanc process. A solution of sodium chloride is treated alternately with ammonia and carbon dioxide under pressure, sodium... 

Modem manufacturing methods depend on the conversion of potassium chloride into carbonate by electrolysis,- by the Le Blanc process or by the action of magnesium carbonate, carbon dioxide, and water ... 

In early 19th century, the availability of sodium carbonate was enhanced by the introduction of the Le Blanc process, which increased the potential supply and produced a more pure product (Eqs. 7.10 and 7.11). The early versions of this process were significant contributors to local air pollution... 

Sulfur dioxide coproduced by this method was generally converted to sulfuric acid in these early operations by using the chamber process. Using this source for the sulfur dioxide for acid making put all of the vaporized arsenic from the pyrites directly into the sulfuric acid product. At the time this aspect was not considered to be serious since most of the sulfuric acid was consumed in the Le Blanc process to produce sodium carbonate (Eqs. 9.4 and 9.5), causing arsenic vaporization and loss again, with the hydrogen chloride produced by the first step [11]. 

In his excellent paper on the evolution of unit operations, W. K. Lewis points out that Modem chemical industries started with the Le Blanc process in France during the (French) Revolution and that the expansion of the chemical industry during the nineteenth century was... 

In France the supply position was worse. By 1776 the political and financial situation there was making the continuity of the imports of ash to that country (particularly from Spain) doubtful, and a prize was offered by the French Academy of Sciences for a new, commercial process in which soda alkali could be produced from common salt. Duhamel s reactions (mentioned earlier) were, of course, completely uneconomical, but it had been established clearly from such studies in pure chemistry that common salt, sodium sulfate, and sodium carbonate were related through the element sodium, and that a commercial process might, therefore, be achieved. It did not prove easy, however, and it was 1789 before Nicolas Le Blanc devised his process (described later) for making alkali from common salt. He did not base his process on the then-current theory of chemical affinity, which suggested that iron should be used to produce alkali from sodium sulfate because of the great affinity of iron for sulfate (13y 14). Indeed, the theory of the precise chemistry of the Le Blanc process remained obscure until about 100 years later, and Le Blanc well... 

Figure 9. Late Victorian black-ash revolver, a revolving furnace used in the second stage of the Le Blanc process (18)...

In Britain the Le Blanc process was introduced between 1802 and 1806, but Britain was trading very widely and still was importing much alkali ash. Consequently, the Le Blanc process did not develop rapidly there. It wasn t established flrmly until 1823 but by 1840 so much alkali was being manufactured in Britain by the Le Blanc process that there was enough being made to supply the local market as well as creating a surplus for export to America. 

Figure 10. Muspratf s factory for making soda by the Le Blanc process, near Liverpool, England, about 1830. Note the tall chimney stack for dispersing the vast amounts ofHCl gas, and also the windmill nearby (20).

The author is grateful to J. R. Harris for his friendly help on the history of the Le Blanc process, and to the Associated Octel Company for their interest and assistance. 

In the Deacon Process, chlorine was produced from hydrochloric acid, the low-value by-product of the Le Blanc process, by catalytic oxidation with air. Deacon used a copper chloride catalyst that could combine with oxygen and hydrochloric acid and form chlorine through an oxidation/ieduction cycle. 

The Claus process to recover and recycle sulfur in the Le Blanc process, based on the procedure suggested by C. F. Claus in 1883, was introduced in 1887 by A. M. Chance. Alkali waste containing calcium sulfide was suspended in water, and hydrogen sulfide was generated by pumping carbon dioxide through the sluny ... 

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