By James Clell Neace - 2000
Would you believe that during the 60-year period, beginning in 1815, there were 79 (charcoal) iron furnaces built in the Hanging Rock region of Appalachia (6)? This is the territory that surrounds Ashland, Kentucky, and Ironton, Ohio; comprised of the counties of Boyd, Greenup, and Carter in Kentucky, and five neighboring Ohio counties just across the river (6).
Moreover, early charcoal iron furnaces proliferated in other Appalachian foothill areas of Kentucky; especially in the counties of Lawrence, Lewis, Bath, Estill, Menifee, and Powell (2,3), and at Cumberland Gap (1). Slate Furnace, in Bath County (named for its location on Slate Creek), erected in 1791, was the first iron ore furnace west of the Allegheny Mountains (1,5).
Slate Furnace, also called the Bourbon Iron Works, was built by Jacob Myers. It was later purchased and operated by a syndicate headed by John Cocky Owings, for whom Owingsville was named (5,7). This furnace was built just 16 years after the founding of Boonesboro. A fort was constructed for protection of workers. At least one of the early iron makers was killed by hostile Indians. Incidentally, it was this same furnace that furnished cannon balls for use by Andrew Jackson in the Battle of New Orleans in 1815.
Suppose you had been a pioneer settler of Kentucky in the days of Daniel Boone, and you needed iron for tools and cooking utensils. Could you have made them?
The essential ingredients are: a good grade of iron ore to furnish iron, a forest filled with hardwood trees to furnish charcoal, limestone to be used as a flux to remove impurities, sandstone rocks to be used as a construction material for the furnace, and waterpower for running a bellows; which blows a strong blast of air through the furnace.
Before we go into additional details about early Kentucky iron production, let us take a brief look at the history of iron and steel. Mankind is known to have been using iron for at least 6,000 years. The first iron used by man was probably in the form of iron meteorites.
The process for smelting iron ore was discovered, independently, by a number of different nationalities of people. Iron ore consists of iron chemically combined with oxygen to form iron oxide. The two best grades of iron ores are hematite and magnetite.
Hematite molecules contain two atoms of iron, combined with three atoms of oxygen. They are red in color and contain up to 70% iron. Hematite, also called red ocher, was used as a red pigment in cave men drawings.
Magnetite molecules contain three atoms of iron and four atoms of oxygen. They are black in color, magnetic, and contain up to 72% iron. Magnetite, also called lodestone or leadstone, was suspended on a string and used as a compass by the ancient Chinese.
Early in history, it was discovered if a chunk of either of the above iron ores was heated in a hot wood fire, for a prolonged period of time, the carbon in the wood would remove the oxygen in the iron ore to form volatile carbon dioxide. This left behind a spongy mass of high-purity iron, shot through with about 3% microscopic tramp slag inclusions. This iron, being malleable, could be beaten into tools and weapons. Iron produced in this manner is called wrought iron. Wrought iron is one of only three metals that can be forge-welded. The other two are steel and platinum.
It was later found that this smelting process was speeded up and improved if charcoal, instead of wood, was used as a fuel, and a bellows made of animal skin was used to fan the flames, making them hotter.
The next improvement in the smelting process was to build an enclosing furnace of clay or sandstone. Even so, for a period covering thousands of years, the melting temperature for iron could not be reached in these early furnaces, and the product of smelting was invariably wrought iron.
Steel for the famous Damascus and Toledo swords of the Crusade Era was produced in India. There, bars of wrought iron were packed with charcoal in closed clay jars and heated for days. The iron absorbed enough carbon from the charcoal to become steel, and thus acquired superior hardness and strength. Steel is an alloy of iron and carbon, and the carbon makes the steel hard.
This crude "crucible" steel was converted into the famous Damascus and Toledo blades, only after prolonged hammering on an anvil, coupled with various heat treatments for tempering. There were dark rumors that the final tempering treatment of these swords was achieved by heating them to a glowing temperature, then thrusting the blade through the abdomen of a convicted criminal.
These steel blades were reputed to be so sharp that they could be used to slice a silk handkerchief, thrown into the air, into two separate pieces.
The production of this crucible steel was so labor-intensive that "the price wasn't right." Thus, the whole world had to wait until a Kentuckian named William Kelly came along, before affordable steel was produced.
In Europe, during the Middle Ages, higher temperatures in iron furnaces were finally reached, so that the iron was actually melted and poured into molds as cast iron, also called "pig iron." The cast iron contained up to 5% carbon, dissolved from the charcoal, while in a molten state. This made the cast iron hard and brittle, such that it would shatter if attempts were made to shape it with a hammer.
The early Kentucky iron furnaces had a capability for making both wrought and cast iron. Molten cast iron was poured into sand molds to produce such products as skillets, Dutch ovens, and kettles.
In the year 1851, William Kelly (1811-1888), a Kentucky ironmaker, discovered an easy way to burn out some of the excess carbon in cast iron, and thus convert it to steel (2). Unfortunately, Mr. Kelly did not have the financial resources required to develop his new process, so he went bankrupt in 1857.
One year earlier, in 1856, an Englishman, Henry Bessemer, "reinvented" Kelly's process, now known as the Bessemer converter. Bessemer steel was easily produced in large quantities, at moderate prices.
One of the toughest problems faced by Kelly, when making steel, was to stop the burning of the carbon at just the right time. This problem was eventually solved by others, who burned out all the carbon, then added back the requisite amount.
A few examples will illustrate the close tolerances involved in producing steel, and will also show how the hardness of steel is affected by the percentage of carbon it contains: 0.1% (carbon): soft iron wire; 0.2 %: mild steel for bridges; 0.3%: medium steel for ships; 0.5%: medium-hard steel for railroad rails; 1%: spring-steel for automobile springs; 1.2%: high carbon tool steel.
For anything below 0.08% carbon, the resulting product is wrought iron. Anything above about 1.5% carbon, the end product is cast iron. Steel is found between these two ranges in carbon content.
Basically, the Bessemer process for converting cast iron into steel involves remelting the cast iron and blowing air through the molten iron. By this treatment, part of the 4-5% carbon in the cast iron is converted into gaseous carbon dioxide by the oxygen in the air. At the same time, a number of other impurities in the molten iron are also burned out. The final product is steel with a hardness dependent upon the carbon content, as indicated above.
Returning to the early Kentucky iron furnaces, as previously noted, they were usually located in the Appalachian foothills. This choice of location is explained by what is called the Clinton (fossil iron ore) formation of the Silurian Age (2).
Clinton iron ore seams follow the western foothills of the Appalachian Mountain chain and are one to four feet thick (2). In the Appalachian areas of Northern states, especially New York and Pennsylvania, this ore appears mainly as magnetite. From there down to the end of the Appalachians in Alabama, hematite predominates. In the Kentucky foothills, the Clinton formation was commonly reached by removal of a two to 30-foot soil overlay by strip mining techniques, using scrapers and plows pulled by oxen (2).
A big plus for the early Kentucky ironmakers was the abundance of big hardwood trees, used for charcoal production. Each furnace was the center of an integrated community. The furnace required the services of a number of employees doing a wide variety of tasks (6). Here, blacksmiths, carpenters, stonemasons, teamsters, charcoal makers, and millwrights, not to mention ironmakers, all plied their trades.
Log homes were built, schools were constructed for the children, and a boardinghouse and a general store were opened for the convenience of the workers and their families (3,6). Many of these old sandstone iron furnaces are still standing in Kentucky, derelict relics of the past.
When operating, these furnaces were charged by adding, in turn, layers of charcoal, limestone, and iron ore, which were dumped in from the top of the furnace. These additions were repeated several times, until the top of the furnace was reached (3).
The furnace was then ignited at the bottom, and a strong blast of air was admitted to fan the flames. The air was supplied under pressure, by a bellows connected to a water mill, which was turned by water flowing from a dam. The heat melted both the iron and the limestone. The iron, being heavier, settled to the bottom of the furnace, where it was drained into sand molds. The shape of the sand molds was such as to remind the ironmakers of a sow and suckling pigs. Thus, the cast iron was called "pig iron."
The molten limestone acted as an absorbent for impurities in the iron, and being lighter than iron, floated on top, where it was drained away separately as slag. Once started, the furnace was run day and night, seven days a week, with new charges being continuously added at the top of the furnace.
The old Kentucky blast furnaces are now silent and still. Why? Nature could not replenish the big hardwoods as fast as they were being removed to make charcoal for the furnaces. However, the main reason can be cited as a good example of deja vu. Just as enormous seams of easily reached coal in Wyoming have currently put a damper on coal production in Eastern Kentucky, massive layers of hematite, located around Lake Superior, and easily dug, because of light soil overlay, led to the demise of the old Kentucky iron furnaces in the 19th century. At the Great Lakes, the hardwood supply problem was solved by use of Appalachian coal as a replacement for charcoal.
The first attempts to replace charcoal by coal were disasters. The burning coal literally gummed up the works. Eventually, it was discovered that if coal is heated in a sealed container with no air present (a process called destructive distillation), the coal does not burn, but decomposes, chemically, instead.
Volatile matter (coal tar) is collected and converted to fertilizers, dyes, plastics, explosives, drugs, and medicines. What remains is a solid residue called "coke," which can be substituted for charcoal in blast furnaces. Coke was found to work even better than the charcoal it replaced. This is because coke has structural strength, which prevents settling in the furnace, providing more surface sites for the numerous chemical reactions involved inside the furnace.
The railroads came into the Kentucky hills and hauled away the coal for use in the iron furnaces of the Great Lakes region. It is ironic (no pun intended) that a map, published recently by the Courier-Journal, shows present pockets of pervasive poverty in the very parts of Kentucky that have provided coal to fuel the nation's economy for a period of over a century.
Related articles found in earlier issues of The Kentucky Explorer: (1) June 1988, p. 48; (2) November 1988, p. 29; (3) April 1989, p. 37; (4) January 1991, p. 50; (5) March 1992, p. 32; (6) March 1992, p. 56; and (7) November 1995, p. 33.
James Clell Neace, 377 Freedom Road, Blackville, SC 29817-4533, is a regular contributor to the Kentucky Explorer.