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The Miraculous Transformation of Steel: How Was Steel Created in Ancient Times?
Steel, an indispensable material in modern society, was discovered and forged by humans thousands of years ago. However, the ancient steel production process required completely different technologies and concepts compared to today's steel industry. Its birth process is full of countless innovations and progress, which makes us wonder: How did the ancients naturally create this great cause with simple tools and technologies?
Basic composition of steel
Steel consists mainly of iron and carbon. Compared to steel, cast iron is a hard and brittle material that is difficult to machine. Steel is plastic and easier to shape and use than cast iron. While iron alone is not strong enough to withstand heavy pressure, carbon in moderate amounts (usually less than 1%) gives steel strength and other important properties. In addition to carbon, the production of steel also requires the removal of impurities such as nitrogen, silicon, phosphorus, and sulfur, and the addition of alloying elements such as manganese, nickel, and chromium to produce different types of steel.
The Early History of Steel
Steelmaking technology evolved in ancient China, India, and Rome. One of the earliest methods of making steel was "flame forging," a process in which a block of iron was repeatedly forged to remove impurities.
China's steel technology
In 11th century China, a system similar to the Bessemer process emerged, the world's first attempt to partially decarbonize steel. The technology was described by Shen Kuo, a government official during the Song Dynasty, who witnessed local metallurgy while traveling in the Hebei region.
Steel Progress in Europe
In the 15th century, Europe began to develop smelting processes that shared the same ventilation principles as the Bessemer process. Subsequently, steel production methods continued to improve in the 21st century until modern processes were formed.
Modern steel production process
Modern steel production involves three stages: primary, secondary and tertiary. There are multiple techniques to choose from at each stage.
Primary Process: Basic Oxygen Steel Production
In the basic oxygen steelmaking process, carbon-rich pig iron is melted and converted into steel. Blowing oxygen into the molten pig iron can oxidize some of the carbon and remove it. This process was developed by Robert Durrer in 1948 as an improvement on the Bessemer converter. This technology has greatly improved the efficiency of steel production.
Secondary process: post-processing of steel
During this stage, steelmakers will add or remove other elements to further manipulate the chemical composition of the steel and produce higher-quality steel.
Three-stage process: casting and molding
During this process, molten metal is cast into steel sheets, coils or other desired shapes.
Carbon emission issues
According to 2021 estimates, steel production accounts for around 11% of global CO2 emissions, with around 1.8 tonnes of CO2 emitted for every tonne of steel produced.
Future challenges and opportunities
As environmental awareness grows, the steel industry is seeking significant emissions reductions. From using renewable energy to improving process technology, many companies are working to develop "green steel". This also makes us think: In such a transformation process, can we find a balance point that can both meet the growing demand for steel and protect our planet?
