Steel industry gathers to discuss sustainability

Industry and academia debate the key challenges and opportunities

INDUSTRY workers and researchers from across the steel sector gathered for the virtual bi-annual SUSTAIN conference in December 2021, which was titled Sustainability in Steel. SUSTAIN – Strategic University Steel Technology And Innovation Network – is a collaborative research hub working towards transforming the UK steel sector into a cleaner and smarter industry.

Emissions from steel production

Steel is typically produced one of two ways: via the blast furnace-basic oxygen furnace (BF-BOF) method, or the electric arc furnace (EAF) method. For the former, iron oxide is converted to iron ore in the BF using a reducing agent which is typically coal. The molten iron is then fed into the BOF where the added oxygen lowers the carbon content to the level required to produce steel.

Around 70% of global steel production is via BF-BOF, and 30% is via EAF

An EAF produces steel using an electric arc to produce the high temperatures needed. The feedstocks for an EAF can either be steel scrap or directly reduced iron (DRI). For DRI, the iron oxide is reduced while remaining in a solid state and without the need for melting as is done in the BF. The reducing agent is mainly natural gas, but coal can also be used.

According to the World Steel Association, around 70% of global steel production is via BF-BOF, and 30% is via EAF. The steel sector is currently responsible for around 7–9% of global emissions and 15% of UK industrial emissions. There are various potential solutions for decarbonising the industry, including using hydrogen, carbon capture and storage (CCS), and making better use of steel scrap.

Using hydrogen

A potential way to produce lower-emissions steel is to use hydrogen in the process. This can either be done by using hydrogen directly in the BF so that less coal is needed, or it can be used as the sole-reducing agent to make DRI.
Peter Warren, Development Metallurgist at British Steel, described using hydrogen in blast furnaces as an “overhyped subject”, pointing out that hydrogen doesn’t generate any heat in the lower part of the furnace; it’s purely a reductant. “It’s an interim possible solution, but it’s not going to change the world in the way that we need to decarbonise”.

Mark Allan, Group Manager for Industrial Decarbonisation at the Materials Processing Institute (MPI) spoke of plans that are currently in development to establish a tonnes/d H2 DRI pilot facility and integrate it with the existing EAF at the MPI.

However, Sara Hornby, Owner of Global Strategic Solutions and Services, expressed concerns over the move to hydrogen use in steelmaking. She said that one issue will be construction rates of new DRI facilities.

Peter Holliman, Professor of Materials Science and Engineering at Swansea University, cautioned that even though using hydrogen as a fuel only emits water, water vapour in the atmosphere absorbs radiation from the Sun.

“We need to actually understand what happens if we throw billions of tonnes of extra water into the atmosphere, bearing in mind that [across] the entire planet, all the climate is driven by water being evaporated, moving around, condensing and then falling as rain. We need to model that.”