Maintenance and Repair of Blast Furnace Trough Castables
1. Working Environment and Damage Mechanisms
Blast furnace runner working linings face continuous scouring by 1450–1550℃ hot metal and slag, plus thermal cycling from intermittent tapping. Damage mechanisms include: chemical attack and penetration by slag, mechanical wear by iron and slag flow, thermal-shock spalling, and local iron penetration at the slag-metal interface. The main trough (especially the head near the iron impact point) wears fastest, followed by branch runners and swing spouts; slag runners suffer mainly slag attack.
2. Common Material Systems
The mainstream runner castable is the Al₂O₃-SiC-C system: high-alumina bauxite or corundum aggregate, silicon carbide for wear and slag resistance, plus carbon (pitch, resin or graphite) for slag-penetration resistance and thermal-shock performance. Al₂O₃≥65%, SiC+C≥15% is typical for main trough working linings. In recent years, low-carbon low-cement and ultra-low-cement grades are spreading to reduce carbon's effect on steel quality. Swing spouts, trough covers and slag runners use dedicated grades or precasts.
3. Routine Maintenance: Inspections Plus Hot Repair
Runner maintenance follows the principle of "frequent inspection, small repairs, avoid major rebuilds." Inspect lining surfaces before and after each tap: address local spalling, head scouring pits and thinning side walls promptly with repair or ramming mixes to stop damage spreading. Hot repair materials must sinter fast, bond to old lining and resist iron scouring. Combine head and impact zones with precast replacement to shorten trough outage. Track thickness changes in a life ledger to optimize repair cycles.
4. Comparing Repair Methods
Cast repair: for large-area wall and bottom restoration; needs formwork and a short trough outage, then fast bake-out. Ramming repair: for local pits and corners; flexible, no formwork—the daily-maintenance workhorse. Gunning: for rapid repair of worn zones without full outage, but adhesion and density depend on site conditions. Precast replacement: for regular zones like heads and swing spouts; shortest outage. In practice, combine methods.
5. Key Points to Extend Life
First, choose the right grades with zoned selection for main vs branch runners and bottom vs walls. Second, control installation quality, especially water ratio and bake-out of low-cement systems. Third, operate scientifically: avoid prolonged high slag-line operation and fixed iron impact points. Fourth, build preventive maintenance—handle damage while small, never run "sick" troughs. High-erosion head precasts and covers also cut main trough maintenance frequency significantly.
6. Conclusion
The core of runner maintenance is "zoned selection + hot small repair + preventive management." Regular inspection, timely repair and proper precast replacement stably extend main trough life and cut per-tonne refractory cost. Henan Songrui New Refractory Materials Co., Ltd. supplies runner castables, repair mixes and precasts with maintenance consulting.
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