Flame‐Retardant Rigid Polyurethane Foam Based on Copper Tailings: A Novel Strategy for High‐Value Utilization of Copper Tailings

ABSTRACT To address the dual challenges of massive copper tailings (CTS) emissions and low utilization rates, this work develops rigid polyurethane foam (RPUF) composites via one‐step full‐water foaming technology. The impacts of CTS on the thermal stability and flame retardancy of RPUF composites were systematically evaluated using techniques including limiting oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis (TGA), and cone calorimeter test (CCT). Flame retardancy assessments revealed that the RPUF‐5 composite achieved a UL‐94V1 rating with an LOI of 21.2 vol%, representing a 9.8% increase compared to pure RPUF. Meanwhile, the char residue of RPUF‐5 at 700°C was elevated by 103%. SEM and Raman spectroscopy analyses further confirmed that CTS facilitates the formation of a dense carbon layer, which effectively enhances the material's thermal stability. These results demonstrate the vast potential of CTS in improving the fire safety of polymers. This work establishes a high‐value utilization strategy for solid waste toward sustainable flame‐retardant RPUF composites.