CEMENT KILN DUST MANAGEMENT: PERMEABILITY

Abstract

Three samples of cement kiln dust were selected to represent three groups of kiln systems: long wet, long dry, and precalciner kiln. Chemical composition and physical characteristics of the dusts were studied. The principal objectives of the experimental study was the determination of their permeability to water. Taking a standard geotechnical engineering approach, it was decided to treat these materials as soils capable of compaction, and to determine their permeability as a function of density. Although the dusts covered a very large range of particle size, free lime content, etc., it was found that they were indeed amenable to normal compactive effort, giving familiar moisture-density curves that provided target maximum dry densities, and corresponding optimum moisture contents. The densities so obtained are maxima only for the standard effort; thus higher densities are achievable as the compactive effort is increased. Specimens of each dust were prepared at three levels of density: low, standard laboratory maximum, and high. Permeabilities were determined by means of a constant head permeameter designed to permit measurements over a very wide range of permeabilities. The results indicated consistent inverse relationship between permeability and density for each dust, and that extremely low permeability could be achieved in each case.