Bessemer process

Bessemer process is an industrial method for the mass production of steel from molten pig iron. The process was named after its inventor, Henry Bessemer, who took out a patent on the process in 1856. The Bessemer process was the first inexpensive industrial process for the mass production of steel from molten pig iron before the development of the open hearth furnace. The key principle is removal of impurities from the iron by oxidation with air being blown through the molten iron. The oxidation also raises the temperature of the iron mass and keeps it molten.

History

The origin of the Bessemer process is closely tied to the early developments in the production of iron and steel. Prior to the invention of the Bessemer process, steel was expensive and difficult to manufacture, limiting its use. Henry Bessemer's invention, which he patented in 1856, revolutionized the steel industry by significantly reducing the cost and time required to produce steel.

Process

The process involves the use of a large container called a Bessemer converter, which is made of steel and lined with a refractory material. The converter is filled with molten pig iron, and air is blown through the iron using a tuyere, a type of nozzle. The oxygen in the air reacts with the carbon in the iron, forming carbon dioxide and carbon monoxide, which escape into the atmosphere. This reaction raises the temperature of the iron, keeping it molten, and burns off impurities such as silicon, manganese, and phosphorus. The process continues until the desired level of carbon is achieved, at which point the steel is poured out into molds to solidify.

Advancements and Variations

The original Bessemer process had difficulty removing phosphorus from the pig iron, which made the steel brittle. This limitation was overcome by Sidney Gilchrist Thomas and Percy Gilchrist, who developed the Basic Bessemer process or Thomas process, which lined the converter with a basic material to remove phosphorus.

Impact

The Bessemer process had a profound impact on the steel industry and the broader industrial landscape. It made steel production faster, cheaper, and more efficient, leading to a significant increase in the availability and use of steel in construction, machinery, and transportation. The process played a crucial role in the industrialization of many countries and laid the foundation for the modern steel industry.

Decline

The Bessemer process began to decline in the early 20th century as newer steel-making processes, such as the open hearth furnace, electric arc furnace, and basic oxygen steelmaking, were developed. These processes offered better control over the chemical composition of steel and were more energy-efficient.

Legacy

Despite its decline, the Bessemer process is remembered as a key innovation in industrial history. It marked a significant step forward in the mass production of steel and contributed to the growth of the modern industrial economy.