Determining the critical Reynolds number for suppressing Marangoni convection of alumina in silicate melt

Ceramic dissolution within silicate melts is often caused by Marangoni convection arising from surface tension gradients, unless it is counteracted by forced convection, which typically occurs beyond a specific critical Reynolds number (〖Re〗_c). This study presents a method for determining the 〖Re〗_c required to suppress Marangoni convection at the alumina (Al2O3)/slag/air triple point. This approach utilizes a modified finger test device equipped with a high-resolution laser for dimensional measurement, allowing accurate determination of mass flux densities from the grove and mantle separately. Subsequently, we examined the dissolution of Al2O3 fine ceramics in a quaternary silicate melt of calcium oxide (CaO)–Al2O3–silicon dioxide (SiO2)–MgO (or magnesium oxide), featuring a CaO/SiO2 weight ratio of 0.65. The experiments were conducted at 1550 °C for speeds of 0, 50, 100, and 200 rpm. The findings revealed a critical rotational speed of 127 rpm for Al2O3-dissolution in this silicate slag at 1550 °C using the aforementioned device, corresponding to an 〖Re〗_c of 6.46. These results contribute to a deeper understanding of the factors influencing ceramic dissolution in silicate melts and offer valuable insights for materials and process engineering applications.