Abstract: The present invention provides a sludge belt method of clarifying a liquid charged with solid material. After a flocculation additive has been added thereto, the charged liquid is conveyed to the bottom of a sludge belt in a clarification chamber (40) via a plurality of injectors (76) spread out over the area of said chamber. The total flow rate through said injectors is evenly distributed between the injectors by an internal head loss. The clarified liquid is removed via an upper overflow (72). Each injector forms jets diverging from its vertical axis, so that the injected flow spreads out over an expansion zone belonging to said injector and meeting the expansion zones of adjacent injectors. In addition, the jets drive vortices which prevent the formation of a layer of sludge having insufficient permeability.

Abstract: Spray nozzles (16, 18, 20) inject just sufficient water to produce the desired cooling of hot powdered substance by evaporation of the water. The water is sprayed finely and uniformly onto said substance to avoid wet lumps agglomerating. The substance comes from a hopper (2), and flows through the apparatus in the opposite direction to a drying gas flow from inlet (21) to a condenser (22) where the heat is recovered from the water vapor.Application to recycling foundry sand and, more generably, to using sand which has been heated.