(631b) Measurement of Dewatering Indices to Rank the Ability for a Given Material to Dewater Effectively in a Prescribed Piece of Process Equipment

The ability of a material to lose entrained water is critical to the preparation of material for suitable landfills or in pre-drying processes where the feed stock is a moist or wet material. The material permeability to fluid is one key parameter that can help predict dewatering times. However, it is not the only parameter that affects the dewatering rate. Both the compressibility and strength of the material as a function of moisture content are also key parameters that determine dewatering potential. We have developed a dewatering index that couples the permeability and compressibility of a material with the stress level in process equipment. The index can give an estimate for the dewatering time constant of a particular material in a prescribed piece of equipment of a given size. This dewatering index can be used to compare two or more materials in the same dewatering equipment as well as to compare the behavior a single material in two or more dewatering processes. The index can be calculated from easily measured flow properties as a function of stress level. We have also developed a correlation of the maximum stress in a submerged solid and the liquid limit of fine materials. This helps define the moisture targets required by dewatering equipment. This paper will allow engineers to better select dewatering equipment specific to their material based on measured bulk properties.