Who patented the hot blast process for iron furnaces in 1828?

James Beaumont Neilson patented the hot-blast process for iron furnaces in 1828.

Neilson's innovation replaced the traditional cold air blown into a blast furnace with air heated before entering it. He developed the idea while investigating furnace problems at Wilsontown Ironworks, and experiments at Clyde Iron Works demonstrated its commercial value. The process sharply reduced fuel consumption and made previously difficult resources more economical to use.

At roughly 600°F, the heated blast could reduce fuel consumption to about one-third of that required by a cold blast. It also allowed ironmasters to use raw coal instead of relying entirely on coke and helped make black-band ironstone profitable. These changes lowered costs and increased the scale of iron production.

Neilson formed a partnership that included Charles Macintosh to exploit the invention. The patent produced years of licensing disputes: ironmasters who adopted the process without permission were sued, while licensed users paid royalties based on the amount of iron made. The patent expired in 1842, accelerating wider adoption.