From Steel Making Process to Suitable Refractory Ceramics. Fundamental and Chemical Exchanges

Refractories are often multi-phase ceramics, mostly based on mixtures of oxides at high melting temperatures:

• refractories are not metals or metal alloys;

• they must withstand at least 1,500°C without softening or collapsing under their own weight, in accordance with the pyroscopic resistance test standard (ISO/R 836).

The steel industry is the biggest consumer of refractory ceramics, with a market share of over 60% by weight. This is due to the scale of the world's steel production and the very high specific consumption of refractories.

The production of steel from iron ore is a long road involving many different tools and processes, from the upstream plant where the cast iron is produced in the blast furnace to the continuous caster where the liquid steel is solidified.

The first aim of this article is to introduce steelmaking processes.

It is impossible to deal with refractories without knowing the processes and operation of the various furnaces, which dictate the conditions and therefore the choice of refractories. The performance of refractories used in the iron and steel industry depends on the conditions in which they are used in relation to the manufacture of liquid metal. The incidents and counter-performances that cripple certain plants are very often the result of unstable production and poorly-adjusted manufacturing processes. It is therefore essential that plant refractory managers and product designers are familiar with the processes and details of manufacturing operations. This enables them to take part in process optimization and adjustment actions, by advocating orientations that promote refractory reliability and cost minimization.

The second objective is to describe the main families of refractories used in steelmaking tools.

The aim of this article is to provide an overview of this vast field in order to grasp its originality and acquire a scientific and technological culture of steelmaking and refractories. It is aimed at technicians and engineers new to the field, as well as experts. The aim is not to acquire operational knowledge of steelmaking or the design of refractory linings for steel furnaces, but rather to grasp the physico-chemical concepts and mechanisms critical to refractories during steelmaking. As this is a complex field, we will focus on the essentials in terms of basic knowledge and understanding of the context in which refractories are used. This article therefore seeks, without preconceptions, to justify the main ideas of the trade and to defuse certain intuitive ideas that are not always correct.

Let's look at...