Abstract: Processes and apparatus for the heat treatment of fine-grained material, particularly for the production of cement, wherein the material is preheated in a preheater, further heated in a precalcination zone using additional fuel, calcined to completion in a rotary kiln, and cooled in a cooler, the preheated material being introduced into a cooling air stream run off from the cooler and the resulting mixture of gas and solids being introduced from the side into a gas pipe which connects the rotary kiln to the preheater and through which the kiln exhaust gases flow in the upward direction.

Abstract: A process for producing cement wherein preheated, partially calcined powder-form raw material is finally calcined in a fluidized bed and is discharged to a cooler through which a cooling stream of air passes. A part of the cooling air passes into the fluidized bed from below and another part of the cooling air, together with the partially calcined material, passes into the fluidized bed from the side. The rates of material flow to and from the fluidized bed is regulated to maintain a substantially uniform intersticial ratio between the upper and lower regions of the fluidized bed.

Abstract: Fine-grained material is heat treated by being preheated and then is heated to its calcining or sintering temperature, following which it is again heated to such temperature and subsequently cooled. The concentration and residence time of the material during its second heating are greater than they are during its first heating, and the concentration of oxygen is greater during the first heating of the material than during its second heating.

Abstract: Fine-grained material adapted to be fired in a furnace is discharged from a preheater into a gas conduit extending from the furnace to the preheater and through which a stream of hot gases pass. The conduit is shaped to deflect the gas stream and concentrate it along one side of the conduit in the area of introduction of the material to the conduit. Below the area of introduction of material to the conduit fuel burners provide a heating zone through which the material falls. The concentration of the gas stream along one side of the conduit assures entrainment of the material in the gas stream and passage of the material again through the heating zone. Above the area of introduction of material to the conduit the latter is shaped to deconcentrate the gas stream and permit some of the material entrained therein again to fall downwardly through the heating zone, following which such material is reentrained in the gas stream.

Abstract: This invention relates to a device for the heat treatment of fine material, including a rotary tube furnace, a multi-stage pre-heater heated by the exhaust gases from the rotary furnace and a zone through which the exhaust gases flow and provided with rotary lifting members, with the material extracted from the second stage of the pre-heater being fed into said zone before it is fed from the furnace exhaust gases from the first stage of the pre-heater and then reaches the rotary tube furnace.

Abstract: Fine grained material such as raw cement meal is preheated in a preheater and discharged from the latter into a rotary kiln for calcining and through which hot exhaust gases pass in counterflow to the material. Immediately after introduction of the material to the kiln fuel is sprayed onto the surface of the material and is covered either by additional material from the preheater or by circulation of the material already in the kiln, due to rotation of the kiln at an elevated speed. The fuel is combusted virtually entirely within the kiln and substantially directly at the material without previous gasification of the fuel.

Abstract: Fine-grained material such as raw ground cement adapted to be fired in a rotary tube furnace is introduced to a vertical preheater and falls through a heating zone located at a level below the level at which the material enters the preheater. A stream of air enters the preheater at a level below the heating zone and passes upwardly at sufficient velocity to entrain the material that has passed through the heating zone, thereby causing such material to pass again through the heating zone. From the preheater the material is delivered to the furnace for final firing.

Abstract: Fine grained material such as ground raw cement is delivered in a stream from a preheater to an upright gas conduit through which furnace exhaust gases flow to the preheater. In different cross-sectional areas of the conduit the velocity of the gas differs. The stream of material falls upon a distributor in the conduit to distribute the material over the cross-sectional area of the conduit. The distributed material falls through a combustion zone and a substantial fraction of such material is entrained by the exhaust gas and passes again through the combustion zone enroute to the preheater. The distributor is adjustable to enable the concentration of material in different cross-sectional areas of the conduit to vary according to differences in the gas velocities in such cross-sectional areas.

Abstract: A method for the heat treatment of fine-grained materials containing alkali compounds which liquify at critical temperatures comprises pre-heating the materials and discharging them to a rotary kiln in counterflow to the kiln exhaust gases, and introducing cooling air to the kiln in such quantity and at such temperature as to reduce the temperature of the exhaust gases to a level lower than that required for the compounds to liquify.

Abstract: A chamber which forms a material inlet and an exhaust gas outlet at one end of a rotary kiln has an inclined bottom arranged to cause preheated fine material deposited thereon to slide by gravity into the end of the rotary kiln. A dense stream of fine granular material is deposited on such inclined surface, and fuel in finely divided form is introduced into the dense stream of material flowing down the inclined surface to cause the fuel to become intimately mixed with the material. Gas is discharged from the kiln in contact with the stream of material as such a velocity as to entrain a substantial proportion of such stream, the temperature and composition of the gas being such as to cause combustion of the fuel mixed with the entrained material.

Abstract: This invention relates to a method and a device for the continuous feed of a controllable amount of powder material from a storage container to a consumer, using a vertical pneumatic conveyor, to which is fed conveying air, with loosening air supplied to the base area.

Abstract: In the manufacture of cement clinker from limestone and clay components exhaust gases from a rotary kiln are delivered via a conduit to the final stage of a multiple stage cyclone preheater for the limestone. The limestone and low grade fuel are introduced to the conduit and calcined therein by a separate firing process immediately prior to the discharge of the calcined limestone to the kiln.

Abstract: A stream of raw material is passed through a preheater to a furnace and a stream of exhaust gases from the furnace is passed through the preheater to preheat the raw material. Dust is electrostatically precipitated from the exhaust gases leaving the preheater, and the temperature of such exhaust gases is controllably raised to improve the efficiency of the dust removal by bypassing a controlled proportion of at least one of said streams around at least a portion of the preheater.

Abstract: A silo for mixing and homogenizing bulk material has an air permeable base above a mixing chamber having a volume less than that of the silo, the chamber also having an air permeable floor, and the chamber being in communication with the silo by at least one material inlet aperture and having at least one material outlet aperture.

Abstract: The heat treatment of fine-grained material such as ground raw cement comprises preheating the material, mixing the preheated material with fuel under conditions incapable of supporting combustion, subsequently combusting the fuel in intimate relation with the material, and finally firing the material in a rotary tube furnace.

Abstract: Fine-grained material such as raw ground cement adapted to be fired in a rotary tube furnace is introduced to a vertical perheater and falls through a heating zone located at a level below the level at which the material enters the preheater. A stream of air enters the preheater at a level below the heating zone and passes upwardly at sufficient velocity to entrain the material that has passed through the heating zone, thereby causing such material to pass again through the heating zone. From the preheater the material is delivered to the furnace for final firing.

Abstract: A method of burning or sintering fine-grain material which agglomerates above a critical temperature, such as cement raw meal, lime, dolomite, magnesite, in which the material is first preheated in a first zone, then flame heated in a second zone to a final treatment temperature and thereafter separated in a third zone from the hot exhaust gases of the second zone, the exhaust gases of the second zone being used for preheating the material in the first zone.