Sustainability efforts set to affect steel industry
The steel industry has been fraught with challenges, ranging from Covid-19-related impacts to supply chain issues, but the move towards more sustainable practices will also result in many changes in steel industry processes, says South African Institute of Steel Construction (SAISC) technical director Amanuel Gebremeskel.
These processes include incorporating alternative and renewable-energy sources, as well as recycling steel.
Steel is made from iron-ore – a compound of iron, oxygen and other minerals in nature. To make steel, the iron needs to be separated from the oxygen and a tiny amount of carbon needs to be added. Both processes require that iron-ore be melted at 1 700 in the presence of oxygen and a type of coal called coke, explains Gebremeskel.
The chemical processes required to release the oxygen from the iron-ore creates carbon dioxide (CO2), which pollutes the atmosphere.
Globally, there is a significant drive to use alternative, green energy sources, including solar, wind and hydrogen, as well as cogeneration that refers to the reuse of the heat that is already part of the existing process.
“The main question is how do you reduce the rock in the iron-ore without using carbon,” says Gebremeskel.
He says using hydrogen is more environment-friendly because the chemical process creates water rather than CO2.
The direct reduction method – which uses natural gases that are the source of hydrogen to remove the oxygen from the iron-ore, thus reducing carbon use in the process – can also be applied.
In South Africa, some steel producers can now generate their own power on site using clean energy sources, such as solar, as a result of legislative changes.
The changes enable power plants to self-generate up to 100 MW for self-consumption or connect to the grid and sell power without applying for a generating licence.
All forms of sustainable energy could be used to facilitate greener steel industry production; therefore, the industry needs to consider methods of producing electricity that do not emit CO2.
Gebremeskel says another way of making the steel-producing process more environment-friendly is to recycle steel that has been used and discarded, adding that recycled steel could comprise a significant portion of the country’s steel production.
The local steel industry is “making great strides in recycling”, with several mini-mills that are recycling sources of steel, such as old cars and refrigerators, which effectively changes how production works. In addition, electric arc furnace recycling can also make use of alternative energy sources, he concludes.