William Kelly (August 14, 1811 - February 11, 1888), born in Pittsburgh, Pennsylvania, was an American inventor. Kelly studied metallurgy at the Western University of Pennsylvania. Instead of getting a job as a scientist, Kelly, his brother, and his brother-in-law started a dry goods and commission business, which they called McShane & Kelly. After a fire destroyed their warehouse, William and his brother John decided to move to Eddyville, Kentucky in 1847 to enter the iron industry.
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In 1846, they purchased an iron manufacturing company in Lyon County on the Cumberland River, called Eddyville iron-work. They then renamed the factory Kelly & Company.
Before the technique of injecting air into molten iron was discovered by Kelly and by Bessemer, iron was available as cast iron, a strong but brittle metal made in a blast furnace by treating iron ore with coke derived from coal, and wrought iron, a more malleable and flexible metal made by heating iron ore in a low oxygen environment in a bloomery heated by charcoal and producing "blooms", which were 100 to 200 pound lumps of very low carbon iron mixed with slag. The blooms then had to be worked repeatedly by hammering with a steam hammer and folding it to work out the slag. This could in turn be converted to steel by heating it for prolonged periods sealed in stone boxes with charcoal, to add back carbon. The resulting steel could then be formed into larger shapes by heating it to welding temperature and hammering it together into a mass. Other laborious and expensive methods made small amounts of steel from special ores.[1][2]
Kelly started experimenting with his "air-boiling process," a process of blowing air up through molten iron to reduce the carbon content, in 1847. His initial goal was to reduce the amount of fuel required for iron and steel making, because of the immense amount of timber required to make the charcoal. He discovered that, contrary to the expectations of his iron workers, the injected air did not cool the molten iron, but instead combined with the carbon to cause the iron to boil and burn violently until the carbon was greatly reduced, improving the quality of the iron or converting it to steel.[2][3] His experiments began in 1847. The same process was later independently invented and patented by Henry Bessemer.[4]
Kelly was college-educated in metallurgy, while Bessemer in his autobiography described no education, other than a practical knowledge of typecasting and machining learned at his father's type foundry, stating in 1854, "My knowledge of iron metallurgy was at that time very limited...", but somehow he was able to build, without a long series of progressive improvements, a functioning converter to blow air into molten iron and convert it to steel.[5] Kelly later asserted that English workmen at his plant had informed Bessemer of Kelly's experiments.
Various types of converter are shown. No photo of a Kelly converter is currently available.
Kelly applied for a patent after Bessemer patented the process, and was granted patent 17,628 in 1857. The core claim of his patent was "Blowing blasts of air, either hot or cold, up and through a mass of liquid iron, the oxygen in the air combining with the carbon in the iron, causing a greatly increased heat and boiling commotion in the fluid mass and decarbonizing and refining the iron."[6]
In 1871, the U.S. Patent Office granted Kelly a renewal of his patent for 7 years while rejecting applications for renewal by Bessemer and Robert Forester Mushet, who had also received patents for the process. Other sources say that Kelly and Bessemer devised the steel making technique independently.[7][8]
The financial panic of 1857 resulted in Kelly's bankruptcy, and he was forced to sell his patent.[3] The Kelly patent and the Bessemer patent were licensed for steelmaking in Pennsylvania, at the Cambria Iron Works, starting in 1857.[9] With the patents jointly licensed, invention priority disputes became of little interest to the business world. Kelly received only about 5% of the patent royalties paid to Bessemer, and Bessemer's name was used for the process.[10] Bessemer already had a well known steel making operation in England, and Kelly was little known.
The companies owning the Kelly and Bessemer patents began selling the product under the name "Bessemer Steel" in 1866.[3] The Bessemer process, co-discovered by Kelly and Bessemer, greatly reduced the cost of steel and improved the quality, making possible the industrial growth of the United States from 1865 until the early 1900s. The Bessemer process was replaced by the open-hearth process in the early 20th century.[4]
There is controversy over Kelly's contribution to the development of the air-blast process.[11]
Kelly worked in Louisville, Kentucky for the rest of his life, manufacturing axes as well as working in real estate and banking. He died there February 11, 1888.[3]