A pneumatic suspension of low-density (floating) particles in viscous Liquids ina non-conventional vessel is discussed. The mixing vessel has a two-dimensional design. From a fluidization point of view the suspension mode allows an inverse fluidization of the solids due to oriented flow of the gaseous and liquid phases. The base phenomena, the minimum suspension conditions and the energy inputs are presented upon different conditions imposed of the liquid-solid systems: particle density, particle shape and liquid viscosity.