Alternative fuels in cement manufacturing: Modeling for process optimization under direct and compound operation

► The integrated kiln-soil mill-fuel mill system is rigorously modelled. ► The model, linear in fuel feed flowrates, reveals the kiln balance invariants. ► The enthalpy balance imposes production cuts under poor alternative fuels (AFs). ► A five-step procedure leads to noninferior AF mixtures and appropriate manipulation. ► Air flow or internal fluegas circuiting regulation forestalls undue production cuts.