Waste lithium-ion batteries (LIBs) are important secondary sources of many valuable materials,
including Critical Raw Materials (CRMs) defined by the European Union (EU): lithium, cobalt,
manganese, and graphite. Additionally, LIBs typically contain nickel and copper, which are classified
as Strategic Raw Materials for EU since 2023. In recent years, great effort has been made to develop
efficient recycling processes for waste LIBs. Pyrometallurgical processes have been essential in
industrial production of metals for many decades. These technologies are relatively mature, with
high adaptability for different raw materials. Pyrometallurgical treatment in LIB recycling typically
involves the use of smelting processes, in which waste batteries are heated above their melting
points and metals are separated through a reduction reaction in the liquid phase. Through this
recycling route, cobalt, copper, and nickel can be efficiently recovered in the form of a metal alloy,
whereas lithium and manganese are lost in the slag phase.
The goal of this work was to increase the recoveries of valuable battery metals through a combination
of hydro- and pyrometallurgical unit operations. First, industrial Li-ion battery scrap underwent a
selective sulfation roasting stage, where the aim was to transform LiCoO2 and Mn-oxides into Li, Co
and Mn sulfates. After roasting, the battery scrap was leached in distilled water with a solid to liquid
ratio of 100 g/L at 60°C and recovered 95 per cent of Li, 61 per cent of Mn and 35 per cent of Co.
After leaching, the solid leach residue was mixed with industrial Ni-slag and biochar, followed by
reduction at 1350°C in argon atmosphere. The high-temperature smelting experiments were
conducted as a function of time (5–60 mins) to investigate the reduction behaviour of battery metals.
The results show that Co and Ni from the slag and leach residue can be efficiently recovered in the
slag cleaning stage.