Blast Furnace · Taphole
The taphole is the only passage for slag and iron discharge. Its channel wall simultaneously contacts 1450–1550℃ hot metal, slag and high-pressure gas. During normal tapping, iron velocity and temperature are high, and the mud sleeve and channel lining bear a combined thermal, mechanical and chemical load. The taphole condition directly determines the stability and safety of casting operations.
Slag/iron scouring: at each tap, high-temperature slag and iron scour the channel wall at high velocity, progressively widening the channel into a "bell mouth." Mud sleeve damage: during plugging, anhydrous taphole mud is repeatedly compressed under high temperature and pressure, causing the sleeve to crack and break at edges, leading to poor sealing and run-outs. Thermal cycling: in the tap—plug—tap cycle, the channel wall repeatedly heats and cools rapidly, developing thermal-shock cracks. Gas leakage: as the channel widens, high-pressure gas leaks along joints and gaps, further enlarging the channel and burning surrounding refractories.
A widened taphole destabilizes casting: plugging becomes difficult, taphole depth fluctuates, and in severe cases run-outs or taphole burn-through occur, threatening furnace safety and crew safety while raising mud consumption and repair workload.
Configure taphole refractories in three layers—channel, mud sleeve and protective lining:
Dense ramming: ram carbonaceous mix in 100–150mm layers, ensuring tight bonding without voids. Sleeve forming: trim the mud sleeve promptly after plugging to standard shape and size. Casting management: control tap intervals and iron velocity, avoid consistently deep or shallow plugging, and stabilize taphole depth. Monitoring: record mud volume, taphole depth and tap time each time; add mud or arrange local repair promptly on anomalies.
The core of taphole care is "frequent plugging, stable depth." Patch with mud per standard routinely; at mid-campaign maintenance, check channel widening and ram or cast-repair channels beyond limits so the taphole zone stays stable and reliable throughout the campaign.
Anhydrous taphole mud is made of corundum, silicon carbide and coke fines with resin binder for blast furnace taphole sealing. It sinters fast, plugs densely and resists molten iron and slag scouring, ideal for large and medium blast furnaces under high pressure.
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Iron runner castable purpose-built for blast furnace troughs with Al₂O₃≥65%, SiC+C≥15% and 1550℃ max service. Resists continuous erosion by hot iron and slag. For main trough working linings, branch runners, swing spouts, slag runners and trough covers—the core refractory of the cast house.
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BF taphole ramming mix is applied by semi-dry ramming without formwork, Al₂O₃≥70%, 1600℃ max service. Layered ramming gives density and enables rapid hot repair.
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