A UK-China partnership for energy and materials recovery in steelmaking

In 2013 approximately 110 Mt "waste" slag was produced worldwide at temperatures of 1650 oC containing ~25% of FeO,
making it a potential source of energy and raw material. This work aims to combine and implement two concepts developed
in the laboratory to industrial steelmaking. The first is to convert the thermal heat of the slag into hydrogen (from water),
which can be used to lower the in-house C footprint or exported externally as a fuel. Secondly the valuable metal oxides
are recovered for in-house re-use and lower raw materials usage or exported for other purposes. Both concepts are based
on controlling the gas atmosphere. The project aims toat developing fundamental knowledge on the slag structure and its
evolution as function of gas atmosphere and temperature (WP1 and WP2) and based thereupon, design and build an
industrial test-reactor for carrying out the process (WP3). If implemented worldwide, it is envisaged that the process, if
successful, could save over $3,300 M based on the BOS steel produced in 2013. In addition, the recovery of heat and
valuable chemicals contributes to a more green and energy and raw-material resilient steel industry.
The Warwick group will lead on the development of the integrated heat-materials recovery process, completing scale-up
trials to recover both the thermal energy (producing syngas fuel) and valuable metal elements in oxide forms (e.g. Fe3O4
and Fe2MnO4). They will also be involved in WP2 - providing support for materials recovery and WP3 - advice for the pilot
plant trials.

Steel Industry - The primary beneficiaries are the industrial partners. Tata Steel UK Ltd produces steel through the BOS
route in Port Talbot and Scunthorpe. The hydrogen market price is ~$2 per kg and the iron ore price is $110 per tonne.
Therefore we estimate that if successful the novel energy-materials recovery process will generate additional value or cost
savings of >$3 (>$1 from H2 and >$2 from Fe recovery) per tonne steel. To the Chinese industrial collaborator Jintang-
Shougang Steel the benefits are qualitatively the same as for Tata Steel, but scales with their significantly larger tonnage of
production. For both companies, the cost savings will allow them to become more sustainable and more competitive in the
global market. In 2013, 1,600 Mt (million tonnes) crude steel was produced worldwide, of which 71.2% (1,139 Mt) was
produced through the BOS and this resulted in 100 kg slag per tonne liquid steel. The slags which are at temperatures up
to 1650oC and contain up to 25% FeO are used for low value applications in constructions or worse, simply dumped in landfills. If the proposed reactor is successful: Up to 70 litres (~6.25 g) hydrogen per kg slag can be produced by a novel
hydrogen harvesting technology created by Tata Steel. The amount of material recovery from the slag (e.g. Fe3O4) after
controlled transformation of target metal oxides is estimated to be 190 kg per tonne slag at the recovery rate of 70%. This
would reduce the amount of raw materials used. The hydrogen or syngas when used internally as a recovered fuel will
lower energy use and decrease C footprint and the recovered metal oxides will be used internally as raw material partially
replacing iron ore.
Other industry - Other industry beneficiaries include the wider global steel community and non-ferrous industries that utilize
slags would realise the same economic, social and environmental benefits as the main partners. Power generators that
utilize slagging gasifiers would potentially be able to recover heat and materials from the generated molten ash.
Societal - Tata Steel is the last steel producer in the UK, currently employing 19,000 workers across three sites. The cost
savings proposed will ensure sustainability of employment for these staff, as well as staff in other businesses such as the
ferroalloy industries that utilize slags, that could also employ this process.