Moisture capacity: Definition, measurement and application in determining the optimal water content in granulating

Abstract

The optimal granulation moisture, which means the least water content added into the mixture for obtaining suitable size distribution of the granules, is of vital importance for sintering. The moisture capacity, which means the maximum water content held in the iron ores of unit mass, is suggested, and defined. An apparatus for the moisture capacity measurment was developed. Five samples were selected for the measurments. In order to study the relationship between the moisture capacity and some characters of iron ores, the surface area and pore volume was measured by the method of liquid nitrogen absorption. It was found that the moisture capacity increaseed with increasing the external surface area of the iron ore, and decreased with increasing the pore volume in the iron ores. The iron ores were granluted with various water content level in the labtotary rotaing drum, and then loaded in the sintering pot for measuring the permeability of the burden. The size distribution of the granules were also measured for asisting confirming the optimal water content in granlation. The application of moisture capacity indicated that the iron ore of high moisture capacity needed more water added in the granulation process to get high permeability. © 2010 ISIJ.