Bessemer process

People use air to make steel.

They blow air into hot, melted iron. This air burns away bits that do not belong. This process makes the iron much stronger.

This new way to make steel is very fast. It takes only about 20 minutes. Before this, it took a whole day!

This strong metal is used for many things. It helps make railroad tracks.

Steel is a very important part of our world.

Henry Bessemer was an Englishman who changed how we make steel.

Before his way, making steel was very slow. It could take a whole day! Bessemer's method was much faster. It took only 10 to 20 minutes to make steel from melted pig iron.

The process uses a big machine called a converter. Workers blow air through the hot, liquid iron. This air causes oxidation. Oxidation is a way that oxygen reacts with things in the iron. This burns away extra carbon and other impurities. The burning also makes the iron even hotter. This keeps the metal in a liquid state.

Sometimes the iron has too much carbon removed. Workers must add carbon back at the end. They might also add a mix called spiegeleisen. This helps make the steel better for many uses. This new way made steel much cheaper. It helped build many railroad tracks in the United States.

The Bessemer process changed the world by making steel easy to produce.

Before this, making steel was very slow and expensive. It could take a full day to make a single batch. This new method could turn pig iron into steel in just 10 to 20 minutes.

Because it was so fast, steel became much cheaper for everyone to use. This helped build huge things like railroads and bridges. It was a major part of the Industrial Revolution.

This way of making steel works through a thing called oxidation.

Workers start with molten pig iron inside a large machine called a converter. They blow air through the liquid metal to introduce oxygen. This oxygen reacts with impurities like silicon, manganese, and carbon. The oxidation burns these extra elements away as gas or solid slag. This process also makes the iron even hotter, which keeps it liquid. At the end, workers add carbon back to reach the right amount for steel.

History shows that two men may have found this method around the same time.

An Englishman named Henry Bessemer took out a patent in 1856. He was inspired by a talk about making better guns for the Crimean War. However, an American named William Kelly also experimented with a similar way in the 1850s. Some say Kelly's method was less successful than Bessemer's. There was a big debate about who truly invented the process first. Bessemer eventually earned over 5 million dollars from his patents.

Many different people helped make the process work better.

Robert Forester Mushet found a way to improve the quality of the steel. He used a mix called spiegeleisen, which contains iron, manganese, carbon, and silicon. This made the steel more malleable, meaning it could be shaped easily. Another scientist, Sidney Gilchrist Thomas, helped deal with phosphorus in the iron. He used a "basic" process with special linings in the converter. These changes allowed for much better steel for building projects.

This invention helped the United States become a leader in steel.

An American named Alexander Lyman Holley brought the process to the US. He worked with partners like John F. Winslow and John Augustus Griswold. Later, the famous businessman Andrew Carnegie used this technology for his huge mills. In the 1870s, Carnegie could sell railroad rails for only $18 per ton. This was much cheaper than the $100 per ton cost from before. This cheap steel helped connect the whole country by train.

The Bessemer process was the first inexpensive industrial method for mass-producing steel.

Before this invention, making steel was a slow and costly task. It could take at least a full day of heating and stirring to produce one batch. This process changed everything by turning molten pig iron into steel very quickly. It could complete a batch in only 10 to 20 minutes.

This speed allowed steel to be used for massive projects instead of just small tools.

The core mechanism of the process is a chemical reaction called oxidation. Workers begin with molten pig iron inside a large vessel called a converter. They blow air through the liquid metal to introduce oxygen. This oxygen reacts with impurities like silicon, manganese, and carbon. The oxidation turns these impurities into gas or a solid waste called slag.

This reaction also releases heat, which keeps the iron mass molten. Once the impurities are burned off, workers must add carbon back into the liquid. This is necessary because the converter removes almost all the original carbon. A typical low-carbon steel used in construction has a 0.25% carbon content.

There are two main types of the Bessemer process based on the converter's lining. The first is the acid Bessemer process, which uses a lining made of ganister sandstone. This method works well when the raw iron has very little phosphorus. However, if the iron has high phosphorus, a different method is needed. This is the basic Bessemer process, also known as the Gilchrist–Thomas process.

This version uses a lining made of dolomite or magnesite. These specific materials help manage the impurities found in different types of iron.

The history of this invention involves a debate between two different men.

Henry Bessemer, an Englishman, patented his process in 1856. He was inspired by a conversation about improving artillery for the Crimean War. However, the American inventor William Kelly also experimented with a similar method in the early 1850s.

Kelly claimed Bessemer knew of his discovery, making the claim of who invented it controversial. While Kelly was awarded a priority patent in 1857, Bessemer's process became the global standard. Bessemer eventually earned over 5 million dollars in royalties from his patents.

Early versions of the process faced technical challenges with steel quality. Bessemer's first licensees produced steel that was described as "rotten hot and rotten cold." The problem was that the air blast contained 78% nitrogen, which made some steel grades sensitive.

A metallurgist named Robert Forester Mushet solved this by using spiegeleisen. Spiegeleisen is an alloy containing iron, manganese, and small amounts of carbon and silicon. Adding this improved the steel's malleability, which is its ability to be shaped at high temperatures. This made the metal much more useful for many different industrial tasks.

The Bessemer process helped the United States become a major global power in steel production.

Alexander Lyman Holley brought the technology to America and improved its productivity. He worked with investors like Andrew Carnegie to build massive mills. Carnegie's Edgar Thomson Steel Works opened in 1875 and changed the industry. Before this technology, the U.S. produced about 157,000 tons of steel per year. By 1910, American companies were producing 26 million tons of steel annually. The cost of railroad rails dropped from $100 per ton to just $18 per ton by the 1890s.

This technology connected the world by making the expansion of railroads possible. Cheap steel rails allowed trains to travel across vast distances more easily. It also provided the material needed for massive structures like the Brooklyn Bridge. Even though there were debates about using cheaper Bessemer steel for bridges, the process remained vital. The ability to create massive amounts of strong, cheap metal fueled the entire Industrial Revolution.