Steelmakers globally are being pressured to reduce their carbon emissions, and the enhanced blast furnace is an “interesting solution” to ensure a reduced carbon footprint for steel plants, says plant supplier SMS group South Africa MD Pieter Bezuidenhout.

The industry standard blast furnace is a thermal and chemical reactor that transforms iron-ore to pig iron by burning coke and coal in the blast furnace to produce a hot reducing gas, which ensures the transformation of iron-ore to pig iron.

The abovementioned reducing gas consists mainly of carbon monoxide and a small quantity of hydrogen, says SMS group senior technical expert Fernand Didelon.

During the transformation process whereby iron-ore becomes pig iron, carbon monoxide is partially transformed into carbon dioxide and molecular hydrogen is transformed into water.

However, the level of carbon emissions during this process is high, and enhanced blast furnaces could be used to reduce the carbon emissions from steel plants using blast furnaces.

“The enhanced blast furnace intends to produce pig iron with a reducing gas containing more hydrogen and less carbon monoxide and by replacing the coal injected in the blast furnace with a natural gas, coke oven gas or even better – with hydrogen,” explains Didelon.

Such a furnace also aims to improve efficiency by directly injecting hot reducing gas rich in hydrogen into the blast furnace shaft, consequently reducing coke consumption, and carbon emissions up to 28%.

The key advantage of using the enhanced blast furnace in steelmaking is that there is no major change in the plant layout and no impact on steel quality because most steel plants operate a coke plant and can inject coke oven gas into the blast furnace, adds Bezuidenhout.

An enhanced blast furnace requires less gas and/or electricity, compared with, for example, an electric arc furnace and direct reduction plant, and allows for more flexible requirements on the quality of the raw materials than a direct reduction plant.

An electric arc furnace and direct reduction plant also need high amounts of natural gas or green hydrogen and green electricity, which are largely not available in many countries, including South Africa.

Locally, an enhanced blast furnace could be a valid solution to mitigate pressing problems until green hydrogen and green electricity become more abundant, concludes Bezuidenhout.