Abstract
The worlds steel industry contributes four to six percent of global carbon dioxide emissions. This is principally from blast furnaces, basic oxygen steel making, sintering and pelletising.The push to eliminate carbon emissions will see a change where green high grade magnetitee becomes the preferred feedstock for the steel industry. This will necessite changes to flowsheets and ensuring all inputs into the process have no carbon footprint. The magnetite concentrates will command a premium in price. Lower grade hematite ores will be less favoured. The magnetite feedstock will need to be +68% Fe grade and be low impurity to trransition to low emission steelmaking. Pilbara iron ores are most at risk with this change compared to existing magnetite producers. The global steel industry faces massive technical challenges to transition over the coming years.. This will also require low carbon power, water and transport. both blue and green hydrogen will have a role to play in this transition.
Examples will be given using new technology to produce higher grade magnetite concentrates and the options for steel mills to move away from conventional blast furnace operations. These include hydrogen reduction, MIDREX, Circored, HYL, PERED and other processes. Whilst carbon capture and storage are possible this is not a commercial alternative. Biomass as an alternative still has a carbon footprint and therefore is not totally green.
Hydrogen reduction of iron ores circa 62% iron is possible but magnetic separation must then be used to remove silica and alumina to achieve +68% iron. For Pilbara hematite ores this offers the best solution going forward. Hydrogen is more explosive than natural gas and the systems will require purging at start up and shutdown. This represents a significant operating risk. The storage and transport of hydrogen represents a challenge because hydrogen causes embrittlemrent of steel. At the same time ammonia has been suggested as a better alternative as a means of storing and transporting hydrogen.