Projecting Environmental Improvements in Mineral Processing Pathways: the Case of Cathode Active Material Production

Purpose Rapidly eliminating carbon emissions to the atmosphere to stabilize the Earth’s temperature challenges the retrieval of critical minerals in a responsible way. This work introduces a methodology to consider technological switches in mineral processing pathways as they will come online in the future and supports the prospective analysis of their impacts. Methods Examined technological switches span seven categories: 1) next-generation mineral processing pathways; 2) novel chemical production processes; 3) feedstock substitution for fuels and reductants; 4) reagent substitution; 5) circularity of industrial by-products; 6) valorization of tailings and other waste; and 7) improved water and emissions management practices. Process models of technological switches — sourced from process simulations and company data — are linked to our reconstructed granular inventories of mineral processing pathways. We illustrate our method with a case study on climate impacts, human carcinogenic toxicity and water consumption of three cathode active material (CAM) chemistries; nickel-manganese-cobalt in a 90%, 5% and 5% stoichiometric ratio (NMC955), lithium iron phosphate (LFP) and a nickel-rich (30%) sodium-ion variant (NMMT). Results and discussion By projecting improvements in nickel sulfate and iron phosphate processing pathways, we demonstrate absolute reductions of 16-86% in climate impacts (GWP1000), 43-99.8% in human carcinogenic toxicity (HTP-c) and 19-63% in water consumption (WCP) by 2060; where long adoption periods for emerging technologies shrink cumulative reductions to 6% / 4% / 9% in GWP1000, 57% / 55% / 24% in HTP-c and 10% / 0% / 29% in WCP between 2025-2060 for NMC955 hydroxide, NMMT and LFP CAM respectively. Cumulative reductions stand much lower than predictions from the prevailing premise tool (REMIND SSP2-PkBudg1150) for climate impacts of NMC955 hydroxide (-39%) and NMMT (-27%). In fact, projected impacts in premise are systematically lower for both climate and human toxicity (carcinogenic) across all CAM chemistries between 2025-2040. Conclusions Our proposed conceptual framework prevents over-optimistic modeling while retaining the required level of granularity in order to provide action-specific guidance to reduce environmental impacts of mineral processing pathways. We recommend its implementation within existing and emerging prospective tools and its application to a wider set of mineral-intensive ecosystems, such as the solar and wind industries and artificial intelligence infrastructure.