Fe₃O₄ and Fe loaded carbon matrix composite microwave absorbents by recycling of coal gasification residue

In order to realize the effective resource utilization of coal gasification residues (CGR), the composite microwave absorbents loaded with different magnetic components were prepared through wet chemical impregnation and roasting progress, recycling of coal gasification residue as carbon-based carrier. The results showed that the main reaction involved in gradual carbothermal reduction reaction, during which the Fe₂O₃ and Fe₃O₄ were transformed into Fe. And part of high-activity carbon in CGR was consumed as well, which resulted in the poor graphitization degree of CGR composites. Benefitted from the better impedance matching and attenuation characteristic, FeCGR1000 displayed excellent microwave absorbing performance. The reflection loss value reached −25.3 dB under the coating thickness of 2.0 mm, and the effective bandwidth kept 4.0 GHz as the coating thickness remained 1.5 mm. This work not only benefitted for realizing the resource utilization of CGR, but also provided new ideas for the high additional value application for CGR.