Method for determining the content of at least metallic iron in sponge iron - or a sample thereof - that is produced by direct reduction from iron ore

A method for determining a content of at least metallic iron (Femet) in sponge iron or a sample thereof produced by direct reduction from iron ore, comprising the following steps:

• detecting at least one measurement variable (Ameas), which is dependent on at least one electromagnetic property of the sponge iron or sample thereof,
• providing a mathematical model whose model output variable (Amod) is described as a function of the content of at least metallic iron (Femet) of the sponge iron or sample thereof, wherein the mathematical model has an effective medium approximation (EMA) for the permeability (μeff) and electrical conductivity (σeff) of the sponge iron or sample thereof, and
• implementing an estimation method for determining the content of at least metallic iron (Femet) using the detected measurement variable (Ameas) and the mathematical model.