The influence of slag compositional changes on the chemical degradation of magnesia-chromite refractories exposed to PbO-based non-ferrous slag saturated in spinel

In non-ferrous metallurgy the refractory life is application dependent, typically going from several months up to 2 years or more. Slag engineering is widely used to reduce the dissolution rate of a refractory lining by forming a solid protection layer at the slag-lining interface, thereby increasing the lining's lifetime. The non-ferrous slag in this paper is engineered to form a protective spinel layer. This phase, however, only forms near and at the slag-lining interface, while deeper inside the sample forsterite grains are detected, resulting in direct contact between the still unsaturated slag and the magnesia-chromite refractory phases. At this position the MgO dissolution increases with a factor 3–4 compared with the slag-refractory interface, attacking the bonding between grains and decreasing the brick's mechanical strength. As this happens deeper inside the sample, the spalling risk increases. Strategies to simultaneously reduce refractory dissolution and spalling are discussed.