Selective comminution and grinding mechanisms of spent carbon anode from aluminum electrolysis using ball and rod mills

The recovery of spent carbon anode (SCA) materials plays important roles in environment protection and resources recycling, while this cannot be efficiently achieved without liberation. In this study, grinding characteristics of spent carbon anode from aluminum electrolysis in both ball mill and rod mill were analyzed, and compared based on the utilization of the selective Fuerstenau upgrading curves. In addition, the different grinding mechanisms of ball and rod milling were evaluated by analyzing the shape factor and surface roughness of the ground samples. Results of mineralogical characterizations indicated that carbon particles (d50 = 46.86 μm) presented in the SCA were closely associated with cryolite particles. At 5 min grinding time, the maximum selective comminution factor (β) values of ball milling and rod milling were 2.00 and 1.63, respectively, indicating a higher degree of selective comminution of SCA was achieved from ball milling. Comparisons of the valuable component content (cv, cum) of -125 μm ground particles and the shape characterizations of 74–125 μm ground particles generated from ball and rod milling manifest that a direct relationship exists between the degree of selective comminution and the grinding mechanism.