Preparation of nickel slag derived Fe₃O₄/conductive carbon black/natural rubber composites and enhanced microwave absorption

Nickel slag contains many valuable metals, such as Fe, Ni, Co and Cu, while the total Fe content is up to 40%. How to recycle and reuse these valuable metals efficiently is an urgent problem to be solved. Herein, nickel slag-derived Fe₃O₄ (NSD-Fe₃O₄)/conductive carbon black (CCB)/natural rubber (NR) composites were prepared by molten oxidation and mechanical blending methods and their microstructure and microwave absorption performance were explored. When the CCB content was 50 wt% (filler contents), the reflection loss (RL) of composites reached − 35.3 dB at 1.5 mm, and the effective absorption bandwidth (EAB) was 3.8 GHz. The excellent microwave absorption performance of the composites originates from the dielectric–magnetic synergistic effect caused by the dielectric loss of CCB and the magnetic loss of NSD-Fe₃O₄. This work provides a new direction for the preparation of microwave absorption materials (MAs) using metallurgical slag.