Anthracite iron combined those experiments and the new hot blast processing. In the United States, where the Lehigh Coal & Navigation Company (LC&N) had begun shipping anthracite to Philadelphia in 1820 because the principles could not obtain sufficient fuels for their iron works at "the 'Falls of the Schuylkill' "—so had built the Lehigh Canal and taken over the works of the haphazard Lehigh Coal Mine Company—by the late 1820s having established works that were running smoothly, after building America's second operating railroad in 1827, they'd great interest in exploiting the great anthracite deposits of Schuylkill County for ironmaking, which mills foundries
Anthracite difficulty of igniting it. This was a particular concern in smelting iron using a blast furnace. With the invention of hot blast in 1828, which used waste heat to preheat combustion air, anthracite became a preferred fuel, accounting for 45% of US pig iron production within 15 years. Anthracite for iron smelting was later displaced by coke. From the late 19th century until the 1950s, anthracite was the most popular fuel for heating homes and other buildings in the northern US, until it was supplanted by oil-burning systems and more recently natural gas systems. Many large public buildings, such as