Fig. 5: Comparative analysis of CO₂ emissions and energy efficiency in traditional RK-EF route and HPSR alternative.

a, Different steps involved in the traditional RK-EF route. b, HPSR as a one-step processing alternative to RK-EF. c, Comparison of CO₂ emissions from the traditional RK-EF route and HPSR. Data from ref. ²⁴. The emissions from mining, ore preparation (crushing, screening and partial moisture removal), waste disposal, electrode consumption and transport are assumed to remain the same in both cases. d, Comparison of input energy consumption in different processing steps between the RK-EF and HPSR routes. Data from ref. ²³. The illustration highlights that energy used in rotary dryers and rotary kilns in RK-EF is not fully utilized for the process requirements, resulting in approximately 5.2% and 18.2% losses to the environment, respectively (represented by maroon strips). Direct dried ore charge processing in the HPSR route can mitigate these losses, achieving energy savings of up to 19% (depicted by light green strips in the HPSR column).