Sheffield, my alma mater, has an incredible role in British history, especially in First World War as a ship and armament manufacturer. 250 years ago, Kelham Island was a lush green canopy, a contrast to the hillisde town teeming with cutlers, grinders and toolmakers. Come 1800s, and the landscape dramatizes into an urban jungle. Kelham Island emerged as a centre of metalwork for nearly four centuries, making it one of the oldest industrial sites in Sheffield. There’s no place that is more appropriate than Kelham Island that truly lives up to the words ‘Made in Sheffield’.
Steel has foraged its way into every aspects of modern life – from bridges, train rails, amunitions and ships, to daily kitchenwares. The iconic skyscrapers, skylines and awe that we associate with incredible citylines like New York City, Chicago, LA and other urban areas would not have existed today without a gamechanger invention. But the process of its existence didn’t have such a seamless appearance as it looks like. Blast furnaces were in use in India and China since ancient times to chemically redue and physically convert iron oxides into liquid iron. Cast iron was a more popular candidate especially for places that cried out for steel. Cementation furnaces came into the Sheffield area in the 1690s which converted Swedish-iron into steel. It was Benjamin Hunstman’s invention of the crucible process in Sheffield in 1742, which resulted in production of one of the best steel in the world, Crucible Steel, for most of the 19th century. This sealed the reputation of Sheffield as the ‘Steel City’. James Neilson came forward with the patent on the use of Hot Blast in 1828 which further paved way for the Steel Industry.
Despite the fact that the smelting process was apparently conceived independently and almost concurrently by Bessemer in UK and by William Kelly in USA, Kelly was unable to perfect the process owing to a lack of financial resources whereas Bessemer was able to develop it into a commercial success. Sounds like Tesla and Edison all over again doesn’t it? Thus, Henry Bessemer, an English engineer and inventor, became a celebrity with his tall and loud proclaiment in 1856 – he had discovered a way to make inexpensive steel in large quantitites without a furnance. Naming it as the Bessemer process, he outlines the steps as blowing air through molten pig iron which causes the oxygen in the air to combine with the impurities in the pig iron to form oxides which are then removed by the air stream. The oxidation process releases immense heat which thereby keeps the pig iron in a molten state. Bessemer process emerged to be the first inexpensive industrial process that single-handedly allowed for the industrial revolution. The Industrial Revolution is referred to as the move from the Iron Age to the Age of Steel.
Obviously the description itself paints a vivid image of sparks and fireworks of molten matter splaying all over the place. Probably with a similar experience gained on first-hand, Bessemer invented a vessel that would hold the molten iron and confine all the fireworks until the process of steel conversion has completed. The Bessemer converter is a cylindrical steel pot approximately 20 feet high, originally lined with a siliceous refractory. The egg-shaped converter was tilted down to pour molten pig iron in through the top, then swung back to a vertical position and a blast of air was blown through the base of the converter (tuyeres) in a dramatic fiery ‘blow’. Spectacular but dangerous flames and fountains shot out of the top of the converter. The converter was tilted again and the newly made steel was teemed or poured out.
In 1858, Henry Bessemer moved to Sheffield and licensed his method to two steelmakers, John Brown and George Cammell, who both began to produce Bessemer Steel on an unprecedented scale by 1860. Others soon followed and within 20 years, Sheffield alone was producing 10,000 tons of Bessemer steel every week (this was almost a quarter of the country’s total output). No wonder it came to be known as the Steel capital of UK. Before Bessemer made life easier for the steel workers, the expense of mass producing steel was substantially high. Acknowledging and stopping a gap as a shrewd and imaginative businessman ensured that he ended up on the richer side of the scale of life. The man changed the price game for steel industry in England, from £40 GBP to £6-7 GBP per long ton of steel. He was knighted in 1879 for his ingenuity and his wealth.
The Bessemer converter that is located at Kelham Island as part of the Kelham Island museum is the last working example in UK before it was decommissioned. It was used by the British Steel Corporation in Workington until 1974-75 and produced the last Bessemer Steel made in Britain in 1974. It was brought to the Museum in 1978 as an example of the revolutionary steel-making process which first took off in Sheffield. This particular converter itself could produce 25 tonnes of steel at once, which is 3 times the produce generated from early Victorian converter.
Change is the only constant. Nothing redefines this concept more than the fact that as common to all advancements and discoveries, the Bessemer Process slowly became obsolete. Infact, the method stopped being use in the US completely by 1968. Electric air furnaces and other more technical oxygen steel-making processes started replacing and revolutionizing life further. Even though the Bessemer Process has no place in modern-day construction material production, it laid the foundation for development as we know it.
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