Magnesia Dry Ramming Mass for EAF and Induction Furnace Hearths

Magnesia dry ramming mass is installed dry and becomes a monolithic hearth only once the furnace comes up to temperature. That distinction matters: the value of a good hearth mass is not just its chemistry, but how it sinters — how deeply the sintered layer forms, how dense it becomes, and what is left behind it.

Why the Sintering Gradient Is the Whole Game

If the entire installed layer sinters, it becomes a single rigid mass. As the furnace heats and cools, that mass has nowhere to relieve stress except by cracking — and a through-thickness crack is a metal penetration path. A properly graded mass behaves differently: the working face sinters dense and strong, while the material behind it stays partly unsintered and compliant, absorbing expansion and thermal movement.

Getting that gradient right is a function of grain size distribution and of the CaO/Fe₂O₃ flux content, which controls where and how fast sintering begins. At MgO ≥80% with flux held in the 4–10% band, XZK-ERam-80 develops a strong face at 1600 °C (crushing strength ≥25 MPa) while retaining a compliant backing layer.

Installation: Where Hearth Life Is Actually Won

In our experience, premature hearth failure is far more often an installation problem than a material problem. Three things matter most:

• Layer thickness and compaction — install in increments and compact each one. Under-compaction leaves voids that become penetration paths.
• Former practice — for EAF hearths the mass is rammed against a former; former design and removal affect the final profile.
• First heat — a controlled ramp lets the sintering front develop gradually. Rushing first heat is the most common single cause of a weak working face.

We issue a layer-by-layer procedure and a first-heat curve with every order, and can arrange on-site supervision for a first-time conversion.

EAF Hearths vs Induction Hearths

The two duties are not interchangeable. An arc furnace hearth sees a steep gradient from the arc down, with slag contact at the upper face and a safety lining beneath. A coreless induction hearth has a different gradient and metal contact behaviour, and typically needs a mass tuned for a thinner, denser sintered zone. Specify the furnace type and capacity when you enquire so the grading matches.

Supply and Documentation

Supplied in 25 kg moisture-barrier bags on ISPM-15 pallets or in 1,000 kg big bags, date-stamped for shelf-life control. Minimum order 5 metric tons. Every batch ships with chemical analysis and physical test data, and the material is hygroscopic — store dry, off the ground, and use within the stated shelf life.

Where This Grade Sits in the Lining System

Carbon-bonded basic grades are never specified in isolation. Carbon level, antioxidant package and bulk density are all set by the zone, and the zone map is set by the vessel — which is why a grade that performs well in one position can fail early in the next.

XZK supplies magnesia dry ramming mass as one zone of a zoned package rather than as a standalone item: the grades normally zoned alongside it — among them magnesia carbon brick — are documented on the magnesia-carbon and basic refractories page, and the vessel-level architecture — where each zone starts and ends, and which mechanism actually limits the campaign — is set out on the electric arc furnace page.

The ABINSK Electric Steel Works EAF and ladle programme reference documents how this class of material performed in full service, with the measured campaign figures rather than datasheet values.