The cyclone has to remove the bulk (typically ~95%) of the particles from the raw product gas. The cyclone is operated at 400°C to prevent tar condensation and fouling, and is positioned downstream the gas cooler, so the coarse particles can continuously clean the cooling surfaces. The remaining fine dust in the gas is removed in the OLGA unit. The cyclone ash typically contains 60-80% carbon. The cyclone ash is recycled to the combustor of the MILENA.