Upstream lithium extraction processes in lithium-ion battery recycling part 1: critical review of metallurgical process routes from an industrial point of view.

In recent years upstream Li extraction from battery scraps and black mass has gained significantly in importance due to its potential for higher achievable overall Li yields and increased flexibility in downstream processing. Various process routes have been developed and partially industrially implemented. Three major process types were identified through a comprehensive assessment of scientific literature, patent literature, and structured interviews with industry experts. These process types are based on smelting with enrichment of Li in the slag or flue dust phase, roasting with subsequent selective Li leaching, and pure hydrometallurgical processes using either an oxidative or reductive leaching mechanism. Based on the available scientific, patent and expert knowledge, this review critically discusses the current state of development with respect to reaction mechanisms and process design, industrial implementation and engineering aspects, decarbonization potential, integration in the battery recycling chain and economics. Process routes based on roasting with subsequent selective Li leaching currently appear to represent the predominant industrial approach in Asia and are under development in Europe. The available evidence suggests that this preference is primarily associated with a favorable combination of sufficient achievable lithium yields, process robustness, suitability for the current market size, and economic considerations. Current industrial developments indicate that smelting routes involving lithium enrichment in the flue dust phase are likely to reach broader industrial implementation within the next decade, although their economic viability is expected to depend on substantially larger processing capacities. Currently, pure hydrometallurgical processes only play a minor role, with the exception of LFP black mass.