The Bessemer Process: Revolutionizing Steel Production

Overview

First Inexpensive Process: The Bessemer process was the first affordable method for mass-producing steel from molten pig iron, preceding the open hearth process.
Cost Reduction: Decreased production costs from £40 per tonne to £6-7 per ton.
Impact on Industrial Revolution: Marked a shift from the age of iron to the age of steel, enabling the production of stronger metal machines and innovative architectural structures.

Enhanced Durability: Steel rails replaced cast iron rails, lasting 10 times longer.
Increased Production Scale and Speed: Facilitated by the Bessemer converter design.

Construction: Features a pear-shaped steel frame lined with fire clay bricks to withstand high temperatures.
Temperature Management: Excessive temperatures are controlled by adding scrap iron.

Initiation:
- Molten iron and lime are poured into the converter at 1300°C.
- High-pressure air is blasted through tuyères at the base.
Oxidation Steps:
- Silicon and Manganese: Oxidized first, forming slag with lime.
- Carbon: Oxidized to carbon monoxide, indicated by a blue flame.
Temperature Rise:
- Exothermic reactions increase temperature to 1600°C.
- Rocking the converter helps disperse air and scrap iron evenly.
Completion:
- Slag is skimmed off.
- Molten steel is poured into ladles.
- Additives (ferro manganese, ferrous silicon) are mixed to achieve desired steel composition.

Combined Blowing Techniques: Utilize bottom and high-speed top blows to ensure temperature and composition are homogeneous.
Speed Improvements: These innovations have made the process quicker and more efficient.