Degradation of refractories by slags in steelmaking - Examples and improvement of refractory performance

A steel mill uses a wide variety of refractory materials. This diversity stems from ongoing efforts to improve both the in-service performance and the cost-effectiveness of these materials.

During steel production, thermal conditions, as well as the nature and composition of the slag, vary significantly from one facility to another. This variability necessitates the use of distinct families of refractories, each exhibiting specific behaviors in response to the slags encountered.

Determining the composition thresholds for slag at which a change in refractory type becomes necessary remains a challenging task. Similarly, precisely identifying the corrosion mechanisms underlying these recommendations is not always straightforward.

[N 4 852] describes the complex physicochemical processes that lead to the degradation of refractories, and outlines the criteria for selecting the major types of refractories used in steelmaking furnaces.

The aim of this article is to illustrate the primary degradation mechanisms observed under actual operating conditions and to highlight ways to improve the performance of refractories. Depending on the situation, this may involve selecting a different type of refractory, adjusting the slag composition, or optimizing other conditions in steelmaking processes.

The conditions under which steel is produced play a major role in the durability of refractories. It is therefore essential to find the optimal balance that minimizes total costs, including both metallurgical and refractory costs. This is undoubtedly a complex task.