Characterization of Cement Kiln Dusts and Animal Response

Abstract

A series of tests were made on cement kiln dusts to determine their capacity to sequester protons and to identify the active agents. The pH stat titration technique indicated little difference among kiln dusts in their capacity to neutralize acids. All kiln dusts were less reactive than calcium oxide but similar to reagent and feed grade calcium carbonates. Examination of kiln dusts by X-ray diffraction indicated that the major form of calcium was calcium carbonate and that little, if any, calcium was present as the oxide or hydroxide. The calcium carbonate in cement kiln dust, determined by the carbonate test, varied from 49.5 to 85.7%. All kiln dusts were much more reactive at pH 3.0 than at 6.0. Cement kiln dusts that did not show a favorable response when fed to animals showed less reactivity at pH 6.0 than dusts eliciting a favorable animal response. The active agent appears to be calcium carbonate in a finely divided state.