Abstract: A vessel for treating a finely-divided material, such as granules, powder, flakes and the like with a fluid, comprising an essentially closed wall having product feed and discharge means for feeding finely-divided material to and discharging it from the vessel, and also fluid feed and discharge means for feeding fluid to and discharging it from the vessel, one of the fluid feed and discharge means in each case opening into the bottom region of the vessel and the other into the top region, wherein between the fluid feed and discharge means sieve means are provided for preventing entrainment of finely-divided material.