Air Tabling—A Dry Gravity Solid–Solid Separation Technique

Abstract The air table is a compact gravity-separating device, which does not require the separation of the low-density fraction from the air stream. Being a dry process, air tabling has a clear advantage over wet separation techniques because it does not require chemical pretreatment of the sample, treatment of water from the process for reuse or discharge, and most importantly, dewatering or drying the mixture after separation. Many factors affect the separation performance of air table. The mixture to be processed should initially reduced in size and classified into a size fraction suitable for air tabling. In addition, controlling the operating variables (i.e., superficial air velocity, longitudinal vibrating frequency of the deck, end slope, side slope, and height of riffles) is important in order to achieve a satisfactory performance of air table. The performance curve of air tabling indicates that sharp separations (i.e., grade higher than 90%, or efficiency higher than 80%) are achieved only if the density differential between materials to be separated is greater than 450 kg/m3. Thus, air table can become one of the standard devices of the material processing industry particularly in separation of mixed materials of different densities.