Abstract: A method of operating a mineral processing kiln includes introducing a quantity of a selective non-catalytic reduction (SNCR) reducing agent into the kiln. The SNCR reducing agent may be a solid, liquid, or a gas. A mineral processing kiln modified for the implementation of SNCR is also disclosed.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method of operating a mineral processing kiln includes introducing a quantity of a selective non-catalytic reduction (SNCR) reducing agent into the kiln. The SNCR reducing agent may be a solid, liquid, or a gas. A mineral processing kiln modified for the implementation of SNCR is also disclosed.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method is described for reducing NOx emissions and improving energy efficiency during mineral processing in a rotary kiln. The method comprises injection of air with high velocity/high kinetic energy into the kiln to reduce or eliminate stratification of kiln gases. The method can be applied to mix gases in a rotary kiln vessel or in a preheater/precalciner vessel.

Abstract: A method and apparatus for controlling the combustion of fuel modules charged into a preheater or precalciner kiln above the transition shelf, typically into the riser duct, is described. The apparatus includes a sensor for providing signals indicative of the status in the region of combustion of the fuel modules, and a controller for a fuel module feed mechanism is provided to receive signals indicative of the status of the combustion region and adjust the rate of delivery of the fuel module into the combustion region responsive to the sensed conditions in the combustion region.

Abstract: A method and apparatus is described for environmentally sound usage of combustible hazardous waste as supplemental fuel in operating rotary cement kilns. The apparatus comprises an open port in the rotary vessel at a point where during cement kiln operation the in-process mineral material is in a calcining state and where kiln gas temperatures are sufficient to decompose volatile components of the waste fuel. A drop tube extending from the port into the kiln is provided to prevent in-process mineral from escaping through the port during rotation of the rotary vessel. Combustible solids are delivered through the port under the force of gravity and air is continuously drawn into the rotary vessel through the open port during kiln operation. The apparatus and method allow efficient usage of combustible solid waste as a supplemental fuel for cement kiln operation.

Abstract: A preheater or precalciner kiln is modified to feed solid fuel into a riser duct of the kiln to enable efficient environmentally sound use of solid waste-derived fuel. The modified kiln includes a solid fuel delivery port in the riser duct, a fuel feeder device for feeding solid fuel through the delivery port, and a fuel suspension device for holding the solid fuel for combustion in a fixed position in the kiln gas stream.

Abstract: A bypass system is provided for a long cement kiln. The long cement kiln includes a cylindrical rotary vessel in which a kiln gas stream flows countercurrent to in-process mineral. The bypass system includes an annular bypass plenum, a port in the wall of the rotary vessel in gas flow communication with said plenum, and a draft tube for preventing passage of in-process mineral through said port. A blower fan induces flow of at least a portion of the kiln gas stream to form a bypass stream through the draft tube and the port and into the annular bypass plenum. The bypass system also includes an apparatus for mixing controlled amounts of ambient air with the bypass stream to cool the kiln gas bypass stream and to precipitate alkali fume in the kiln gas bypass stream before it passes through the draft tube and the port in the wall of the rotary vessel to reduce build up of condensed alkali inside the draft tube.

Abstract: A method and improved apparatus is disclosed for improving combustion efficiency and reducing emission of gaseous pollutants during the manufacture of cement in conventional long rotary kilns. Air is injected through a port in the wall of a rotary cement kiln having a secondary burning zone established by burning solid fuel in contact with the in process mineral at a point downstream, relative to kiln gas flow of the clinkering zone in the kiln. The air injection apparatus is designed to enhance mixing of the injected air with the kiln gas stream and is characterized by high linear flow rates and/or multi-directional air injection ports. The air injection ports can be located downstream of a secondary burning zone to provide staged combustion with concomitant reduction in concentration of NO.sub.x, CO and hydrocarbons in the kiln gas stream.

Abstract: The present invention is directed to a method for controlling the kiln gas stream in a conventional long wet or dry process cement kiln modified for delivery of solid fuel into the calcining zone. Air is injected into the kiln gas stream at a point downstream of the clinkering zone and upstream of the drying zone to promote combustion efficiency downstream of the clinkering zone.

Abstract: A method and apparatus for feeding a bulk material supplemental fuel through a port formed in a side wall of a rotary vessel of a cement kiln. The apparatus includes a stationary annular plenum surrounding rotary vessel. The plenum is configured to define an enclosed interior region in communication with the port in the rotary vessel. The apparatus also includes a bulk material fuel charging apparatus including a hopper for receiving the bulk material, and a barrel in communication with the hopper. The barrel has an open discharge end extending into the interior region of the annular plenum. The bulk material fuel charging apparatus also includes an air cannon in air flow communication with the barrel for injecting air into the barrel to force a portion of the bulk material located in the barrel out of the open discharge end of the barrel, through the port, and into the rotary vessel.

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.

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.

Abstract: A bypass system is provided for a long cement kiln. The long cement kiln includes a cylindrical rotary vessel in which a kiln gas stream flows countercurrent to in-process mineral. The bypass system includes an annular bypass plenum, a port in the wall of the rotary vessel in gas flow communication with said plenum, and a draft tube for preventing passage of in-process mineral through said port. A blower fan induces flow of at least a portion of the kiln gas stream to form a bypass stream through the draft tube and the port and into the annular bypass plenum. The bypass system also includes an apparatus for mixing controlled amounts of ambient air with the bypass stream to cool the kiln gas bypass stream and to precipitate alkali fume in the kiln gas bypass stream before it passes through the draft tube and the port in the wall of the rotary vessel to reduce build up of condensed alkali inside the draft tube.