The general NOx chemistry for combustion and reburning (burning under reduc
ing conditions) in calciners is presented and compared to measurements perf
ormed on a full scale ILC-lowNO(x) calciner. The strong influence of the te
mperature (by splitting the material) in the reduction zone, the amount of
coal fed to the reduction zone, and the amount of rotary kiln NOx on the re
sulting preheater exit NOx are demonstrated. It is shown that the ILC-lowNO
(x) kiln system is able to operate with an extremely low NOx emission of le
ss than 400 mg/m(N)(3) at 10% oxygen.