Synergistic Mechanism of Coal Tar‐Phenolic Resin Composite Binder on Tap Hole Clay for Blast Furnace

Tap hole clay requires binders that provide sufficient plasticity, mechanical reliability across broad temperatures, and resistance to physical impact during blast furnace operation. Coal tar offers favorable thermoplasticity but raises environmental concerns, whereas phenolic resin provides high residual carbon yield but inadequate workability. This study examines the complementary functions of coal tar–phenolic resin composite binders and their influence on the performance and microstructure of tap hole clay. The composite system exhibits a more balanced property profile than single‐binder formulations and reduces coal tar usage by approximately 20%–25% compared with traditional coal‐tar‐only binders. When resistance to physical impact is the primary requirement, a 3:1 coal tar–thermosetting resin ratio achieves the highest strength, with a Marshall value of 1.650 MPa, dried Cold crushing strength of 24.65 MPa, and sintered Cold crushing strength of 13.91 MPa. Microstructural analysis shows that improved pore refinement is closely associated with enhanced mechanical properties. Additionally, carbonized structures observed after heat treatment suggest the possible coexistence of lamellar carbon from coal tar and amorphous carbon domains from phenolic resin. These findings provide guidance for designing high‐performance composite binders for tap hole clay.