Abstract: Apparatus for preheating solid particulate material which material is to be subjected to thermal processing in a furnace. The preheater includes a vessel having an inlet for solid particulate material to be heated, an outlet for preheated material, an inlet for hot exhaust gas from the furnace and an outlet for spent preheating gas. The various inlets and outlets are positioned with respect to each other to achieve countercurrent contact between gas and solids. A gas-solids contact zone is defined within the vessel. A plurality of superimposed conduits connect the solid material inlet with the gas-solids contact zone. A valve is positioned in each of these conduits to control the flow of material to the gas-solids contact zone and thereby control the depth of material within that zone. The greater the depth of material within the gas solids contact zone, the greater amount of preheating that will be accomplished due to a greater length of time that the solid particulate material is exposed to the hot gas.