Altos Hornos de México (AHMSA) — 150 t Torpedo Car Full Refractory Package

Altos Hornos de México's 150 t torpedo cars were supplied as a complete single-source refractory package, and the improvement came from something that is easy to underestimate: material compatibility across the whole car rather than excellence in any single product.

Client and Plant Context

AHMSA's hot metal route uses 150 t torpedo cars — smaller than the 320–600 t cars on the large integrated works, which changes the duty in one important way: more trips per unit of hot metal, so thermal cycling per ton transported is higher. Desulfurisation practice in the transfer chain adds the reagent attack that makes single-mechanism materials fail early.

The Problem as Diagnosed

The car had been supplied by position from different sources, and the failures clustered at the boundaries between materials rather than within any one of them. Mortar from one supplier against brick from another leaves a joint with a different chemistry and a different melting behaviour than either — a penetration seam through an otherwise sound lining. Castable at the throat specified independently of the brick has the same issue, and at the throat, where the lining fails first on almost every torpedo fleet, a boundary is the last thing that should be improvised.

Engineering Approach

The car was engineered as one package:

• Working lining — ASC brick zoned for impact pad, barrel and slag line. ASC was chosen over high-alumina because the duty is three-fold: alumina for slag erosion, silicon carbide for reagent resistance and thermal conductivity, carbon for non-wetting behaviour and compliance under cycling.
• Throat and mouth — dedicated shapes with a matching casthouse ASC castable, engineered rather than cut from standard brick on site.
• Mortar — matched to the brick chemistry, specified with the package rather than sourced alongside it.
• Backup insulation — graded by density against local temperature, to hold shell temperature without over-insulating where it is not needed.

Supply, Documentation and Logistics

The whole package shipped against one documentation standard: Certificates of Analysis in a single format covering chemistry, density, porosity and strength across brick, castable and mortar. Material was palletised and labelled by car and by zone so that installation followed the maintenance sequence without re-sorting. Because one supplier held the whole scope, delivery was sequenced to the car's outage rather than to several suppliers' lead times.

Installation and Commissioning

Installation followed the zone schedule with joint thickness verified and the throat castable placed at metered water addition, since every extra litre beyond the specified range buys workability at the cost of porosity and strength that no amount of good curing returns. Heat-up followed material curves.

Results

Single-source supply removed the material incompatibility issues that had been concentrating failures at material boundaries. Throat life improved because the throat was engineered as a shape with a matching castable rather than cut on site. Consumption per ton of hot metal became a single figure with one owner, which made it improvable.

How the Result Was Measured

Wear was mapped by zone at each car reline and compared against the previous car, so the effect of changing any one position could be isolated. Mortar joints were inspected at teardown as a workmanship item rather than assumed sound — the joints are a lining's workmanship signature, and a good crew with good mortar leaves joints that slag cannot find. The comparison across successive cars is what turned a package supply into a continuous improvement cycle.

What Transfers to Other Plants

Where a lining's failures cluster at material boundaries, the problem is scope fragmentation, not material quality. Consolidating brick, castable and mortar under one specification removes a category of failure that no individual product upgrade will touch — and on hot metal transport, engineering the throat as a shape is one of the cheapest campaign extensions available.

The system view is on the casthouse and torpedo page, and a larger fleet programme is documented in the Severstal torpedo fleet case study.