Recovery of Li, Co, Cu and Ni by Molten Salt Chlorination

Abstract

The recent exponential growth in the Li ion batteries (LIB) market, is largely driven by the demand for electric vehicles and the general transition to a green and digital economy. It is therefore imperative to develop more effective and economic processes for recovering battery raw materials such as Li, Co, Cu and Ni. Moreover, these materials are all classified as critical or strategic (Cu, Ni) raw materials by the European Commission, and for Europe, it is of great importance to build a sustainable European supply chain for Li and other battery raw materials to decrease its dependency on import. In this work, we have studied the possibility to recover Li, Ni, Cu and Co from secondary raw materials like black mass (cathode and anode fraction from shredded end- of-life Li ion batteries), as well as Li from spodumene concentrate, spodumene being an important and available Li mineral. The approach has been to convert the metals in the raw materials to metal chlorides, by chlorination in LiCl-KCl (58 : 42) melts at 470 °C and CaCl2-NaCl-KCl (35 : 30 : 30) at 727 °C. With this method, the metals could potentially be reduced from the chloride matrix by subsequent sequential electrodeposition, utilizing their difference in nobility. Regarding black mass, the highest chlorination yields were obtained from uncalcined material (Li 64 %, Co and Ni 22–24 %, Cu 83 %, and Mn 49 %) in LiCl-KCl at 470 °C, the carbon in the black mass probably enhancing the chlorination rate. For spodumene concentrate, a high yield for Li (100 %) was obtained with Cl2 in CaCl2-NaCl-KCl at 727 °C, this melt composition being more oxoacidic and the higher temperature helping the chlorination kinetics.

Keywords

• molten salt
• selective chlorination
• li