Iron production: Difference between revisions
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==Fuel== | ==Fuel== | ||
Prior to the 1830s, every furnace in the US burned charcoal as fuel. Around the 1860s, coal and coke began to replace charcoal in some areas, but overall iron production increased so much that the use of charcoal still continued to rise up to 1890, and the last charcoal-powered furnace in the US was in blast until 1945. <ref>Straka, T.J. 2014, p. 104.</ref> | Prior to the 1830s, every furnace in the US burned charcoal as fuel. Charcoal was used because it could be produced in large quantities, it burns hotter than wood, and it is almost pure carbon, so it reduces impurities in iron produced. <ref>McVarish, D.C. 2008, p. 260.</ref> Around the 1860s, coal and coke began to replace charcoal in some areas, but overall iron production increased so much that the use of charcoal still continued to rise up to 1890, and the last charcoal-powered furnace in the US was in blast until 1945. <ref>Straka, T.J. 2014, p. 104.</ref> | ||
==Operation== | ==Operation== | ||
Revision as of 19:18, 25 September 2018
Iron production converts iron ore into pig iron through a process known as smelting at a furnace. Early in the history of iron production in the US, most furnaces used charcoal as fuel, so charcoal production and iron production were often closely linked. Ironworks are some of the first and most enduring examples of industry in the United States, and remnants of them survive particularly well in rural parts of the country. [1]
History
In the eighteenth and nineteenth centuries, small-scale metalworking operations produced everyday objects like many forms of kitchenware, toys, building materials, and tools. [2]
Iron Communities
Self-sufficient communities, called iron plantations, were built around these furnaces. Many workers were needed to run an iron plantation, including colliers, miners, woodcutters, molders, founders, patternmakers and their helpers. Hopewell Furnace, in Pennsylvania, employed roughly 200-250 people in the nineteenth century. Workers at iron plantations would often bring their families along with them, so the community at Hopewell Furnace would have consisted of about 600 people. [3] The lands of iron plantations would include housing, gristmills and sawmills, farming land, and vast amounts of woodland, as well as barns, company stores, springhouses, blacksmiths, schools, churches, carpenter's shops, forges, casting houses, charcoal storage, and many other buildings. [4]
Fuel
Prior to the 1830s, every furnace in the US burned charcoal as fuel. Charcoal was used because it could be produced in large quantities, it burns hotter than wood, and it is almost pure carbon, so it reduces impurities in iron produced. [5] Around the 1860s, coal and coke began to replace charcoal in some areas, but overall iron production increased so much that the use of charcoal still continued to rise up to 1890, and the last charcoal-powered furnace in the US was in blast until 1945. [6]
Operation
Efficiency was known to be inconsistent between furnaces in different places and at different times. Factors affecting this include differences in furnace construction and operation, as well as varying compositions of iron ore and qualities of charcoal used. [7] Ironworks had to be near water and sources of raw materials such as charcoal, limestone, and iron ore. [8] Colonial ironworks used a variety of techniques to produce iron.
Bloomery
A bloomery was a small operation that heated iron ore to refine and shape it, producing wrought iron. Bloomeries needed simple equipment like a hearth, a bellows, and a tool for manipulating the iron. Bloomeries were common in colonial America, and operated between the seventeenth and twentieth centuries. Disadvantages of bloomeries include limited production, wasted heat, and an inability to completely separate the iron from slag.[9]
Blast Furnace
Blast furnaces addressed many of the disadvantages of bloomeries. They could be run continuously and conserved heat, and they could produce much more iron. Blast furnaces were vertical, hollow structures, the top of which would be loaded with ore, fuel, and flux, while the bottom had air vents and a hole for the molten iron to run out. Blast furnaces tended to be 25-30 feet high and had very thick stone walls, with fire-resistant interior lining. A layer between the lining and outer stones, usually made of clay or smaller stones, provided better insulation and allowed the inner walls to expand slightly when heated. Bellows, which pumped air into the furnace to feed the flames, were often powered by waterwheels, and because blast furnaces were loaded from the top, they were often located along hillsides. When the molten iron was ready to be collected, or tapped, smaller hole at the top was opened to allow the liquid slag, which sat on top of the iron because it was lighter, to be drawn away. After the slag was collected, the main plug was pulled, and the molten iron ran into sand molds. The iron produced in blast furnaces is called pig iron. [10]
Notes
- ↑ McVarish, D.C. 2008, p. 259.
- ↑ McVarish, D.C. 2008, p. 259.
- ↑ McVarish, D.C. 2008, p. 259.
- ↑ McVarish, D.C. 2008, p. 259.
- ↑ McVarish, D.C. 2008, p. 260.
- ↑ Straka, T.J. 2014, p. 104.
- ↑ Straka, T.J. 2014, p. 105.
- ↑ McVarish, D.C. 2008, p. 259.
- ↑ McVarish, D.C. 2008, p. 260.
- ↑ McVarish, D.C. 2008, p. 260.
References
- Straka, T. J. (2014). Historic Charcoal Production in the US and Forest Depletion: Development of
Production Parameters. Advances in Historical Studies, 3, 104-114. http://dx.doi.org/10.4236/ahs.2014.32010
- McVarish, Douglas C. 2008. American Industrial Archaeology: A Field Guide. Walnut Creek, Calif.: Left Coast Press, Inc.