Making steel with lower-grade iron ore

A steel industry with CO₂ removal capabilities could use lower-grade iron-ore, according to a study from Heriot-Watt University in Scotland.

The team at the Research Centre for Carbon Solutions at the University found that deep emissions mitigation, combined with financial levers, could produce carbon-negative steel - but also exploit lower-grade iron ore.

Professor Phil Renforth says the UK has around 180Mt of slag by-product from steel production, and if the industry used this to capture atmospheric CO₂ by coupling direct air capture with a mineral reaction system, it could remove 1Gt of it a year by 2050.

The team says this would need support from government incentives - around US$200-500/t.

Renforth says that while current production favours higher-purity ore, because it is cheaper, the UK doesn't have any commercial grade-ore, and it is becoming increasingly hard to find. 'That is a problem that is not going away,' he notes.

'Our model shows that by integrating advanced emission reduction technologies and using lower-grade iron ore, we can create a sustainable, economically viable path towards a carbon-negative steel industry.' 

Steel accounts for 5-8% of CO₂ emissions globally, which have increased over the past decade.

The techno-economic model stimulates scenarios where steel production is enhanced with climate-change interventions. They focused on measures like directly-reduced iron, biomass-based reductants and carbon capture and storage.