Towards Integration of Ni-Slag Cleaning Process and Lithium-Ion Battery Recycling for an Efficient Recovery of Valuable Metals

Abstract

Spent lithium-ion batteries (SBs) are important sources of valuable and critical raw materials. An integration of battery recycling with well-established primary processes for metals production has many advantages. In this work, the recycling of two battery scrap fractions obtained from mechanical pretreatment was integrated with a Ni-slag cleaning process at laboratory scale. Graphite from SBs acted as the main reductant, and the reduction behavior of major and trace elements was investigated as a function of time at 1350 °C. Major CO and CO₂ concentrations, as well as minor amounts of SO₂, NO₂, CH₄, and C₂H₄, were detected in the off-gas line. The evolution of gases took place within the first minutes of the experiments, which indicated that metal oxide reduction reactions as well as decomposition of the organic binders both happened very rapidly. This result is in line with the analytical results obtained for the slag phase, where the most significant metal oxide reduction was observed to take place within the first 5 to 10 minutes of the experiments. The distribution coefficient values for Co and Ni between metal alloy and slag as well as between matte and slag showed no significant differences when battery scrap fractions with different compositions were used. The addition of Ni-concentrate in the starting mixture resulted in increasing recoveries of Ni and Co, as well as improved settling of the matte phase.