Abstract: A process for producing a mold for electrolytically producing seamless rotary screen printing stencils is disclosed which includes the steps of: providing a metal mold body having a cylindrical outer surface; covering the outer surface with a sensitive layer such as a photo-sensitive layer, a thermo-sensitive layer or an electrically sensitive layer; exposing predetermined portions of the sensitive layer to a beam which is controlled electronically thereby creating exposed portions of the sensitive layer as well as unexposed portions of the sensitive layer; removing the unexposed portions of the sensitive layer; generating indentations in the metal body at locations where the unexposed portions of the sensitive layer have just been removed; removing the exposed portions of the sensitive layer; and filling the indentations with a non-conductive filler.

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 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 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: 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.