<P> A Bessemer converter could treat a "heat" (batch of hot metal) of 5 to 30 tons at a time . They were usually operated in pairs, one being blown while another was being filled or tapped . </P> <P> Before the Bessemer process, Western Europe and the United States relied on the puddling process to reduce the carbon content of white cast iron (refined pig iron), converting it to wrought iron . It was possible to make low - quality puddled steel, but the process was difficult to control and quality varied . High - quality steel was made by the reverse process of adding carbon to carbon - free wrought iron, usually imported from Sweden . The manufacturing process, called the cementation process, consisted of heating bars of wrought iron together with charcoal for periods of up to a week in a long stone box . This produced blister steel . The blister steel was put in a crucible with wrought iron and melted, producing crucible steel . Up to 3 tons of expensive coke was burnt for each ton of steel produced . Such steel when rolled into bars was sold at £ 50 to £ 60 (approximately £ 3,390 to £ 4,070 in 2008) a long ton . The most difficult and work - intensive part of the process, however, was the production of wrought iron done in finery forges in Sweden . </P> <P> This process was refined in the 18th century with the introduction of Benjamin Huntsman's crucible steel - making techniques, which added an additional three hours firing time and required additional large quantities of coke . In making crucible steel, the blister steel bars were broken into pieces and melted in small crucibles, each containing 20 kg or so . This produced higher quality crucible steel but increased the cost . The Bessemer process reduced the time needed to make steel of this quality to about half an hour while requiring only the coke needed initially to melt the pig iron . The earliest Bessemer converters produced steel for £ 7 a long ton, although it initially sold for around £ 40 a ton . </P> <P> A system akin to the Bessemer process has existed since the 11th century in East Asia . Economic historian Robert Hartwell writes that the Chinese of the Song Dynasty innovated a "partial decarbonization" method of repeated forging of cast iron under a cold blast . Sinologist Joseph Needham and historian of metallurgy Theodore A. Wertime have described the method as a predecessor to the Bessemer process of making steel . This process was first described by the prolific scholar and polymath government official Shen Kuo (1031--1095) in 1075, when he visited Cizhou . Hartwell states that perhaps the earliest center where this was practiced was the great iron - production district along the Henan - Hebei border during the 11th century . </P>

What was the impact of the bessemer steel process