At the new direct reduction plant of voestalpine in Corpus Christi, Texas, two million tonnes of HBI (Hot Briquetted Iron) of the highest quality will be produced annually. HBI is the product of reducing iron ore with natural gas.
HBI stands for hot briquetted iron – porous sponge iron, pressed into briquettes. HBI is created by reducing the iron ore with natural gas. HBI can be used as a pre-material in blast furnaces or electric arc furnaces. In blast furnaces, HBI replaces coke and iron ore, while in electric arc furnaces it replaces scrap metal.
The direct reduction process
HBI is the product of reducing iron ore with natural gas. This is called the direct reduction process and is an environmentally-friendly production process; a DRI plant uses natural gas which is more environmentally sound than coke. The reduction process takes place in the reduction tower. The tower is the heart of the plant and is 137 m (450 feet) tall. The direct reduction process is a complex process, which, explained in simple terms, consists of the following steps:
- Raw material iron ore pellets:
Iron ore pellets – the raw material – are fed into the reactor
- Natural gas is converted into reducing gas:
Natural gas is converted into reducing gas and then injected
Reducing gas circulates in a closed system and is recycled
- The direct reduction process:
Hot reducing gas flows through the iron ore, from the bottom to the top, according to the counterflow principle
The Oxygen content is reduced = “sponge iron” is produced
- “Sponge iron” is pressed into briquettes (Hot Briquetted Iron)
In addition to exceeding all current American and European standards regarding environment and technology, the direct reduction plant in Texas bears new environmental and technological advantages for voestalpine:
- Natural gas is used instead of coke
- The reduction process takes place in a closed reactor
- Process gases are recycled and the heat recovered
- Enclosed conveyor belts and ore storage warehouses keep diffuse dust emissions to a minimum
- Maximum raw materials efficiency is achieved and minimal emissions are relieved through the recycling of collected dust
Across the Group, the use of HBI produced in Texas in voestalpine blast furnaces and steel plants will lead to a reduction in CO2 emissions of around 5 percent. At the same time, the new plant opens up further technological possibilities for the future.