In-Situ Gravimetric Studies of Wetting, Penetration and Wear of Refractories by Molten Slags

Interactions between refractories and slags could involve wetting, penetration, dissolution and structural failure of refractories. Conventional refractory testing techniques, relying on post mortem analysis, provide limited information on the interactive process. To overcome this limitation, a new gravimetric technique, based on wetting and capillary effects, has been developed to provide direct information on dynamic processes of wetting, penetration/dissolution, and wear of the refractories by molten slags. The technique has been successfully applied to three slag-refractory systems pertinent to typical ferrous and non-ferrous processes. The gravimetric results revealed that the interactions between refractories and slags varied from one system to another, from simultaneous penetration and dissolution, predominant penetration with little dissolution, to severe penetration/cracking and refractory failure due to slag attack. Characteristics of the wetting and penetration/dissolution were analysed from the gravimetric data. Some important interfacial properties, such as wettability (defined as γ⋅cosθ, where γ is surface tension and θ the contact angle), and the amount of slag penetration or the net weight change due to penetration and dissolution were estimated. The slag penetration is generally nonuniform and the rate of penetration is influenced by interfacial properties, slag properties and structural characteristics of the refractories. Iron oxide in the slag had a significant effect on wetting and penetration of magnesia based refractories because of its effect on wettability and kinematic viscosity of the slag and its preferential reactions with refractory grains.