2022

Bacher, John

As the societies are striving towards carbon neutrality, energy storage and especially lithium-ion batteries have become one of key enabling technologies. Raw material demand for the batteries will increase in multifold at which time all possible material sources should be utilized. At the moment, recycling of end-of-life batteries are often separate from primary raw materials processors. Partly this is due to the complex, heterogenous and different nature of the feed. However, integrating secondary raw materials to primary production has gained interest to produce broader metallurgical capacity.<br/><br/>The aim of this study is to understand the aspects in pre-treatment of EV batteries which are crucial when secondary raw materials are fed to primary processing. The approach in the study composed of a literature review and black mass composition assessment.<br/><br/>The literature review on pre-treatment processes revealed differences between commercial actors leading to variation in the composition of active material rich fraction called black mass. Even though the pre-treatment processes may compose of same unit processes, differences in equipment type and configuration of the unit processes among other things affects the black mass composition. This variation can be enhanced through poor feed handling to the pre-treatment. In addition, lack of standard for the composition of black mass fraction may also enable wider fluctuation.<br/><br/>When reflecting the black mass composition with the feeds utilized in primary production, most disparity is generated by lithium, fluoride and organics which are not found in sulphidic concentrates from mines or in the intermediate mixed precipitates. This leads to the challenge related to element compatibility and the stage of the flowsheet at which the black mass would be fed into. As an example, the process must at the point in question have similar impurities as to be capable of handling the addition without complications or process modifications. Various treatment methods has been studied to remove or separate one or more of these materials/compounds from the black mass fraction. While mechanical treatment of black mass focus on the separation of graphite and metals such as iron, copper and aluminium from the black mass, thermal treatment aims at removal of fluorides including the binder.<br/><br/>In order to have a comprehensive view on the total effectiveness of integrating secondary pre-treatment and primary metals refining, further studies where these has been merged is needed.