Preparation of MgO-MgAl2O4 refractories doped with La2O3 and the wetting permeation behavior by alkaline slag

Abstract

Alkaline slags play a crucial role in modern smelting processes, underscoring the necessity for researching novel refractories and their interaction mechanisms concerning wetting and infiltration. This study investigates the influence of La2O3 doping on the wettability and infiltration behavior between MgO-MgAl2O4 refractories and alkaline slag, introducing a theoretical evaluation method. The study explored the effects of La2O3 doping on the physical properties, mechanical properties, and thermal shock resistance of the samples, as well as the interface reactions between the samples and slag. Results indicate that La2O3 doping from 0 to 3 wt% enhances sintering performance by promoting the formation of LaAlO3, thereby reducing the apparent porosity from 18.25 % to 15.01 % and increasing the bulk density from 2.85 g·cm−3 to 3.34 g·cm−3. Cold compressive strength improves from 166.24 MPa to 178.42 MPa, while the residual strength retention ratio after thermal shock rises from 86.57 % to 88.65 %. Regarding the interface reaction between slag and samples, CaO and SiO2 react with internal MgO in the samples to form low-melting compounds and high-melting solid solutions. These compounds block pores, weaken slag erosion, and enhance the slag resistance of the samples. As the La2O3 doping amount increases from 0 to 3 wt%, the contact angle between the samples and slag increases, resulting in a greater residual volume of slag and a reduced depth of the slag infiltration layer. The penetration depth of the slag gradually decreases from 102.54 μm to 47.84 μm. This study offers new strategies for optimizing the manufacturing process and selection of refractories.