Hot blast

Hot blast was invented and patented for iron furnaces by James Beaumont Neilson in 1828 at Wilsontown Ironworks[citation needed] in Scotland, but was later applied in other contexts, including late bloomeries.

James Beaumont Neilson, previously foreman at Glasgow gas works, invented the system of preheating the blast for a furnace.

[4] On the basis of a January 1828 patent, Thomas Botfield has a historical claim as the inventor of the hot blast method.

In the case of Calder ironworks from 5.6 tons per day in 1828 to 8.2 in 1833, which made Scotland the lowest cost steel producing region in Britain in the 1830s.

[8] Ultimately this principle was applied even more efficiently in regenerative heat exchangers, such as the Cowper stove (which preheat incoming blast air with waste heat from flue gas; these are used in modern blast furnaces), and in the open hearth furnace (for making steel) by the Siemens-Martin process.

[11] At the time the process was invented, good coking coal was only available in sufficient quantities in Great Britain and western Germany,[12] so iron furnaces in the US were using charcoal.

This meant that any given iron furnace required vast tracts of forested land for charcoal production, and generally went out of blast when the nearby woods had been felled.

He produced a small quantity of anthracite iron by this method at Valley Furnace near Pottsville, Pennsylvania in 1836, but due to breakdowns and his illness and death in 1838, he was not able to develop the process into large-scale production.