Blast Furnace Refractory Lining Solution

The Hearth Decides the Campaign

A blast furnace campaign is won or lost in the hearth. Everything above it — stack, bosh, belly — can be repaired, gunned, or partially renewed while the furnace stays in service. The hearth cannot. Once hearth temperatures rise and the lining is compromised, the furnace is coming out, and the cost is measured in millions rather than thousands.

The hearth survives on one principle: keep the 1150 °C isotherm — the temperature at which molten iron solidifies — inside the refractory. Do that and liquid iron never reaches the interior of the lining. Fail and penetration begins, followed by the brittle-layer formation that accelerates erosion.

Zonal Build-Up

• Hearth and bottom — microporous carbon brick with a ceramic cup barrier, backed by high-conductivity carbon ramming mass against the cooling. The carbon conducts heat to the cooling system; the ceramic cup protects it during start-up and against early alkali and zinc attack.
• Bosh and belly — Si₃N₄-bonded or SiALON-bonded silicon carbide. These zones carry the highest heat load and the worst alkali circulation, which is exactly where nitride bonding earns its cost.
• Lower and mid stack — SiC-mullite or high-strength high-alumina brick, balancing burden abrasion against thermal cycling.
• Upper stack — dense high-alumina or fireclay grades where abrasion, not chemistry, controls.
• Casthouse and taphole — ASC runner castables and waterless taphole clay, covered in our monolithic range.

Why Conductivity Beats Thickness

Adding refractory thickness without adding conductivity is counterproductive. It moves the hot face further from the cooling system, which can raise the temperature at the isotherm rather than lower it. Where hearth temperatures are climbing, the correct response is usually higher conductivity in the carbon build-up and a verified cooling circuit — not simply more brick.

Campaign Maintenance

Two interventions extend campaigns materially. Water-free injection mix fills voids behind the shell and cooling elements, restoring thermal contact and sealing gas paths without introducing water into a hot lining. Shell grouting with carbon-based injection brings local shell temperatures back into range. Both are carried out during operation.

What to Send Us

Furnace volume and drawing, cooling configuration, campaign history, hearth temperature trend, and the alkali and zinc load if known. We will return a full zonal build-up with a material schedule, thermal rationale and installation guidance.