A new method of estimating the liquidus temperature of coal ash slag using ash composition

- Liquidus temperature (Tliq) is studied by molecular and thermodynamic simulation.
- A correlation between Tliq and Ia is proposed and yields predictions with satisfactory results.
- Tliq is predicted by linear relation using ash composition for the first time.
- SiO2/Al2O3 ratio, is a key factor on Tliq of coal ash.

The liquidus temperature (Tliq) of coal ash is above the temperature at which the last solid phase disappeared. Tliq of coal ash slag is widely used to evaluate ash fusion and flow behaviors. The method of determining the liquidus temperature is based on phase equilibrium, the activation energy of viscous flow and chemical composition models. In this work, a linear relation between average molar ionic potential (Ia) and potential energy (Pe) as well as Tliq and potential energy is supported by molecular dynamics simulations. We correlated Tliq (derived from thermodynamic equilibrium calculation) and the molar ionic potential of the chemical composition. The linear relation between coal ash composition and the Tliq is established for the first time, with Tliq=(170.43-3.1457×Ia)×S/A+15.725×Ia+360.78 (DE < 40 °C). The SiO2/Al2O3 ratio (simplified as S/A, calculated by mass basis), a key factor in Tliq, is also introduced into the equation. The relation supplies a convenient method to determine Tliq of multicomponent silicates, specifically using the coal ash based ionic potential of chemical composition.