BLAST FURNACES, EARLY

BLAST FURNACES, EARLY. Blast furnaces use fuel to smelt iron ore, often with a flux to facilitate the process. The molten ore, separated from impurities, is poured into forms. Though sometimes formed into final cast products, more typically early blast furnace molten ore was cooled into ingots or "pigs." Foundries used the pigs as input for molten iron, then cast the iron into final products. Though using more fuel, this two-step heating process further refined the iron. In forges, ingots were heated, then beaten into shapes, producing wrought or bar iron that could then be processed into final products. The intermittent heating and beating further removed impurities and strengthened the product. Blast furnaces therefore produced primarily intermediate goods, pig and bar iron, that were further refined in forges and foundries.

Eighteenth-century consumers used a growing array of iron and steel products including stoves, fireplaces, nails, scythes, irons, hoes, axes, saws and other tools, pots, pans, and ships' hardware. Warfare created demand for iron armaments and ammunition. Refinement of iron bars required heavy iron hammers and anvils. With application of steam power to production and transportation, demand increased for iron machinery, steamboat parts, and, later, locomotives, train car parts, and rails. By the latter part of the nineteenth century, more sophisticated blast furnaces produced vast amounts of iron and steel for railroad transportation and for such urban uses as structures and pipes.

The product of blast furnaces weighed less than the raw material inputs, so that furnace location tended to be near raw materials rather than consumers. Depending on time and place, production varied by the fuel used, the quality of ore and fuel, the product produced, and the degree of vertical integration. Early colonial blast furnaces used charcoal as fuel, giving land-abundant America an advantage over deforested Europe. American charcoal iron producers integrated fuel and iron production, often on plantations of extensive acreage. Early blast furnaces were strong in local markets, but national industrial concentration was low. Early furnaces were tied to ore deposits, which were relatively abundant especially in Pennsylvania, Virginia, and the bogs of New Jersey. Secretary of the Treasury Albert Gallatin's 1810 report on manufactures counted 530 furnaces and forges and noted that iron ore was found in every state.

England shifted to coal as fuel for its iron production in the late eighteenth century, but the American colonies continued to rely on charcoal because eastern coal was difficult-to-ignite anthracite. The more combustible Appalachian bituminous coal deposits were to the west. By 1840, technological change had led to furnaces that could generate sufficient heat to burn anthracite coals. Charcoal plantation iron production gave way to anthracite and then, with westward movement, also bituminous coal production. Producers could control the purity of charcoal better than that of coal, which allowed continued production with charcoal until high-quality coke could be produced. Iron production shifted both technologically and in terms of location to coal sources; output and scale increased.

Eighteenth-and nineteenth-century ironmasters did not know the science that underlay the considerable variation in chemical composition of iron ore deposits. Experience taught expert ironmasters which combinations of ore, fuel, and flux produced the best intermediate iron for different final products. Steel, an alloy of iron and carbon, could only be produced in small quantities with antebellum technology. The development of Bessemer and open-hearth furnaces in the 1870s permitted production of large quantities of steel, concentrated both geographically and industrially.

BIBLIOGRAPHY

Clark, Victor S. History of Manufactures in the United States. 3 vols. New York: McGraw-Hill for the Carnegie Institution of Washington, 1929. Reprint, New York: Peter Smith, 1949.

Hogan, William Thomas. Economic History of the Iron and Steel Industry in the United States. 5 vols. Lexington, Mass: Heath, 1971.

Temin, Peter. Iron and Steel in Nineteenth-Century America: An Economic Inquiry. Cambridge, Mass.: MITPress, 1964.

Ann HarperFender