Fig. 3: Calculated contributors to climate change impacts of nickel laterite ore processing routes.
From: Improving process granularity of life cycle inventories for battery grade nickel
Contributors are associated via color tone to one of the four supply chain steps and are cumulated to the overall climate impacts. a The HPAL processing route is assessed under two existing process configurations for sulfuric acid production and energy sourcing — on-site sulfur burning (21.6 kgCO2eq/kg Nieq) and externally sourced coal(lignite)-based energy and sulfuric acid (39.5 kgCO2eq/kg Nieq). The hydrometallurgical pathway is then compared to a pyrometallurgical alternative for laterite ore processing, RKEF-NPI, with climate impacts summing up to 139.6 kgCO2eq/kg Ni in nickel sulfate hexahydrate, battery-grade. b Since the sulfur-burning alternative for the HPAL process exhibits similar climate impacts to the global product system for nickel sulfate in the ecoinvent database, a closer comparison is presented on this side of the figure. It is found that the global ecoinvent dataset for nickel sulfate considers a higher contribution of the mining and beneficiation stages, but a lower contribution of concentrate processing and nickel sulfate conversion steps than the HPAL variant.
