Abstract: The present invention is directed to a method and apparatus for controlling the kiln gas stream in a conventional long wet or dry process cement kiln. A portion of the kiln gas stream can be withdrawn from the rotary kiln vessel at a point upstream, relative to kiln gas flow of the chain system in the mineral drying zone. Alternatively, or in conjunction with bypass formation, the apparatus can be used to add tertiary air to the kiln gas stream to promote combustion efficiency downstream of the clinkering zone. Use of the present apparatus to form a kiln gas bypass stream enhances operating efficiencies of long kilns by reducing dust loss, by facilitating isolation of high alkali by-product streams, by reducing alkali content of collected kiln dust, by increasing energy efficiency of long kiln operation, and by allowing greater overall control in the cement manufacturing process.