The pool profile, local solidification time and subsequently microstructure of the ingot, melting of the electrode, mass transfer coefficient, diffusivity, depend on the thermal conductivity of molten slag Λl. Thermal conductivity of the crust/skin Λs affects mostly the quality of the ingot’s surface. Both values form important constituents of multifunction Γ(T,d,η,κ,Λl,Λs) which for requested working temperature, (T), density (d) viscosity (η), electrical conductivity (κ), void fraction in solid (ε), thermal conductivity at the temperature T, (Λl) and at the solidus point (Λs) defines all six components (CaF2, CaO, MgO, Al2O3, TiO2, SiO2) slags of requested properties. Literature data was used to calculate parameters of correlation between thermal conductivity of molten, and solid slag at the process and solidus temperatures, respectively. Updated numerical algorithm presented in Part 1 provided solutions that are in close agreement with literature data, as well as those advertised by Wacker Chemie AG.