Bessemer Process

The Bessemer process is the first inexpensive industrial method for mass-producing steel from molten pig iron, developed and patented by the English engineer Henry Bessemer in 1856. It works by blowing a blast of air up through the bottom of a pear-shaped vessel called a Bessemer converter filled with molten pig iron, the oxygen in the air combining with and burning off the carbon and other impurities the iron carries, in a fiercely exothermic reaction that needs no external fuel once started. The process cut the time needed to turn iron into steel from days to minutes, and by making structural steel cheap enough for railroads, ships and buildings it is widely credited with launching the modern steel industry, though its inability to remove phosphorus from iron ore initially limited it to ores from a handful of phosphorus-free deposits until a later basic-lined variant addressed the problem.