Table 1 Summary of the nine development pathways based on the inherent potential of waste streams in the iron and steel sector, and their CO₂ emission reductions and the corresponding ratios to the 2 °C target requirements in 2020, 2035 and 2050.

Pathway	Key points	Emission reduction (Mt) and ratio to the 2 °C target requirements
Pathway	Key points	In 2020	In 2035	In 2050
Pathway 1	BFS-Glassy/Water + SS-Glassy/Water	252/8.8%	268/14.3%	273/20.7%
Pathway 2	BFS-Glassy/Water + SS-Crystalline/Dry	191/6.7%	202/10.8%	206/15.6%
Pathway 3	BFS-Glassy/Water + SS-Crystalline/Dry-R	295/10.3%	313/16.7%	319/24.1%
Pathway 4	BFS-Glassy/Dry + SS-Glassy/Water	306/10.7%	324/17.3%	331/25.0%
Pathway 5*	BFS-Glassy/Dry + SS-Crystalline/Dry	244/8.5%	259/13.8%	264/20.0%
Pathway 6*	BFS-Glassy/Dry + SS-Crystalline/Dry-R	348/12.1%	370/19.7%	377/28.5%
Pathway 7	BFS-Crystalline/Dry + SS-Glassy/Water	165/5.8%	176/9.4%	179/13.5%
Pathway 8	BFS-Crystalline/Dry + SS-Crystalline/Dry	103/3.6%	110/5.9%	112/8.5%
Pathway 9	BFS-Crystalline/Dry + SS-Crystalline/Dry-R	208/7.3%	221/11.8%	225/17.0%

These pathways are summarised according to fundamental properties of waste streams including blast furnace slag (BFS) and steel slag (SS), and technological levels. The CO₂ emission reductions and the corresponding ratios to the 2 °C target requirements in refs. ^4,5 by these pathways are calculated based on the energy recovery and resource recycling of these waste streams. The differences between Pathways 2 and 3, 5 and 6, and 8 and 9 results from the further utilisation of cooled crystalline SS (SS-Crystalline/Dry or SS-Crystalline/Dry-R), i.e., whether the high concentration of CaO in the cooled crystalline SS could be recycled after necessary phase separation considering the technological advancements in the mid- to long-term. In this study, the technological schemes applied to engineer Pathways 5 and 6 (marked as *) are further discussed due to their high-potential CO₂ emission reductions for the 2 °C climate target.

Quick links

Search