Abstract: Extensive improvements in the production capability of the existing installations of the type comprising a rotary kiln and a suspension preheater unit are disclosed; that is, another suspension preheater unit provided with a calciner at its lowermost heat transfer stage and a distributor to direct a part of the preheated raw materials from the existing preheater to the calciner are installed, and all the raw materials supplied to two preheater units are uniformly and highly calcined ahead of the kiln in the preheaters by control of the distributor as well as the fuel rate to the calciner, thereby the production capacity of the kiln is doubled. Furthermore the accumulation of raw materials on the bottom of the calciner can be substantially eliminated and the specific power consumption of the installations may be reduced.

Abstract: A plant is disclosed for heat treating pulverous raw material such as cement raw meal prior to a final sintering process in a rotary kiln. The plant includes a rotary kiln having an upper material inlet end portion for the reception of preheated cement material and a lower material outlet end portion for exiting the final sintered kiln product. A multi-stage cyclone string preheater having at least a first stage for receiving the cement raw meal has a last stage communicating with the upper material inlet end portion of the kiln. A smoke chamber connects the upper material inlet portion of the kiln with the preheater, and a scoop chamber connects the kiln with the smoke chamber. The scoop chamber is adapted to receive preheated, at least partially calcined raw material from at least one preheater stage other than the last stage.

Abstract: A rotary kiln and cooling apparatus for pyroprocessing and cooling of pieces of matter and particularly calcined lime pebbles, the kiln being provided with sized discharge openings near its end for discharge of the product into a cooling unit. The discharge openings are sized to discharge particles in an acceptable range while oversized pieces are passed on and discharged out the end of the kiln into a disposal region, thus segregating the particles without the usually required grates and manual labor and permitting handling of hotter materials.

Abstract: Sulfur oxides have a strong affinity for free lime and readily form gypsum anhydrite. By utilizing 2200.degree. F or higher on-gas containing reduced quantities of sulfur to the preheat zone of a material treating apparatus, large quantities of sulfur can be removed from gases evolved in the rotary kiln. Utilizing lower sulfur content on-gas to preheat will substantially improve the ability of the system to lower both sulfur and alkali levels in the clinker. Substantially free lime in the form of fines is introduced into the kiln off-gas stream to form gypsum anhydrite which is removed and has the potential to be utilized as a by-product. Essentially all of the remaining gaseous sulfur that has not been absorbed by the lime bearing dust is absorbed by the free lime in the pellets in the preheat zone of a material treating apparatus.

Abstract: Method and apparatus for the thermal treatment of moist, granular materials utilizing at least two superposed cyclone separators, with a relatively long gas conduit connecting the lower cyclone separator to the upper one. Charging means are provided in the conduit for introducing material to be treated near the lower cyclone separator, and a venturi-type constriction is provided in the conduit below the charging means, the constriction having its lower end projecting into the lower cyclone separator and serving to break up lumps of material which might otherwise be deposited in the cyclone separator and transfer the particulate material to the upper cyclone separator.

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: 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: A method is disclosed for burning alkaline raw materials in an inventive rotary kiln plant. According to the method, cold atmospheric air is introduced tangentially into a circular chamber mounted either within, or adjacent to, the raw material inlet end of the kiln such that a circulating stream of cold air is produced in the chamber around a stream of exhaust gases passing from the kiln to the chamber. A part of the exhaust gases are thereby cooled by the cold air, and alkali vapors therein are condensed out of, and onto, dust particles in the exhaust gases. The alkaline-coated dust particles are thus subsequently discharged from the chamber. The invention also relates to a rotary kiln plant for practicing the inventive method.

Abstract: Clinker coming from a rotary tubular kiln is cooled by moving a layer of the clinker of a grate in a cooler from a hot zone to a successively cooler zone by introducing fresh air in the cooler zone and passing in countercurrently through the layer of the clinker several times whereby a heat exchange takes place between the air and the clinker, the clinker becoming successively cooler and the air successively hotter. The air is introduced from the cooler zone sequentially into two sections of the hot zone, air at a temperature above 1000.degree. C is removed from a first section in the hot zone, and air at a lower temperature is conducted from the second section in the hot zone into the kiln where it is used as secondary heating air for the raw material therein.

Abstract: A method is disclosed for heat treating pulverulent or granular raw material such as cement meal. Raw material is directed to at least two multi-stage preheater strings, the first string communicating with the kiln by a smoke riser pipe and the second string having a calciner positioned at its lower end portion. The raw material directed to the first preheater string is divided into two divisional flows with the first divisional flow comprising substantially the maximum amount of material which can be substantially completely calcined by hot gases exiting the kiln. The first divisional flow of raw material is directed toward the upper material inlet end portion of the kiln so as to be entrained by the hot gases exiting the kiln, and the hot kiln gases and entrained material are directed to the first preheater string. The second divisional flow is directed to the second preheater string where it is calcined either alone or with raw material directed to the second string.

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: A rotary kiln plant is disclosed having a rotary kiln and a cooler system having a plurality of cooler tubes mounted in planetary fashion about the rotary kiln. Each cooler tube has an inlet end portion which communicates with the rotary kiln for reception of the material to be cooled and a rearward end portion having an outlet end for exiting the cooled material. First support means is positioned adjacent the inlet end portion of the cooler tube and second support means is positioned adjacent the outlet end portion of the cooler tube so as to retain the axis of the cooler tube substantially parallel to the axis of rotation of the kiln.

Abstract: A vertical reaction vessel has a plurality of funnel-like constrictions dividing the vessel into individual chambers, at least one inlet for introducing fine material into the top of the uppermost of such chambers, and an opening at the bottom of the lowermost of such chambers for withdrawing heated fine material, and for introducing hot gas to be exhausted from the uppermost chamber. Guide elements for the fine material extend downward along the inner surface of at least one of the funnel-like constrictions.

Abstract: An apparatus for burning cement raw meal to produce cement clinker which includes a pair of parallel suspension preheaters each adapted to receive cement raw meal and hot spent combustion gas for preheating the cement raw meal. Each of the suspension preheaters discharges preheated raw meal into a single calcining furnace. Combustion takes place in the calcining furnace to produce a calcined raw meal. The spent combustion gases from the calcining furnace are supplied in proportional quantities to each of the parallel suspension preheaters. From the calcining furnace, the calcined raw meal is supplied to a rotary kiln for clinkering the calcined raw meal. Hot cement clinker is discharged into a cooler where the clinker is cooled by passing cooling air upwardly therethrough. The cooling air is heated by the hot clinker and the hottest portion is supplied to the rotary kiln and to the calcining furnace to serve as combustion air.

Abstract: A method of calcining solid materials on a downdraught travelling grate prior to treatment at a higher temperature on a continuously operating kiln, wherein heat for said calcining is obtained by drawings hot gaseous effluent from the kiln into the travelling grate through the solids discharge outlet thereof, characterized in that additional heat from an auxiliary source is induced into a downstream portion of the travelling grate.

Abstract: An apparatus for the heat treatment of fine-grained material, particularly pulverized raw material for use in the manufacture of cement, the apparatus comprising a preheater composed of a plurality of superimposed cyclones, the preheater feeding a rotary kiln. An exhaust conduit is connected to the rotary kiln and has a combustion zone formed therein. The gas discharge from one of the intermediate cyclones is directed into the combustion zone. The exhaust conduit includes a pair of upper and lower concentric conduits, the upper conduit having its lower end received in spaced relation to the upper end of the lower conduit and terminating at the combustion zone. A fuel feed conduit is disposed between the lower end of the upper conduit and the upper end of the lower conduit. The arrangement provides for a more efficient treatment of finely divided particles with the hot gases.

Abstract: An apparatus for use in drying various kinds of finely divided materials utilizing microwave heating means for heating a rotating drum through which the material to be dried is drawn by suction. The apparatus includes means for separating the dried material from the air in which it is entrained during its travel through the drum.

Abstract: A first cylindrical drum member having an inlet portion for receiving materials to be treated, such as preheated coal and char includes a longitudinal axis and an outlet portion through which the treated materials are discharged into the inlet end portion of a second cylindrical drum member. The second drum member is independently supported for rotation relative to the first drum member and has a longitudinal axis coplanarly aligned with the longitudinal axis of the first drum member such that the drum members are concentrically positioned in tandem relative. A sealing assembly is connected to the first and second drum members for longitudinal movement with the drum members during expansion and contraction of the drum members as they are subjected to different temperatures.

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: An installation for the burning and/or sintering and cooling of cement clinker, lime, magnesite, dolomite and similar materials in granular or crushed form, especially adapted as a small-scale cement mill or lime mill, having two movable materials carrying platforms arranged inside a burn chamber, in a staggered relationship, and an intermediate wall subdividing the burn chamber into a forehearth for the upper platform and a main hearth for the lower platform. Blowers supply combustion air, draw the used burn gases through air permeable back walls above the platform, recirculate them into the changing shaft to dry and preheat the materials, and cool the sintered materials in the cooling shaft. An aftersinter platform or rotating aftersinter kiln may be arranged between the lower platform and the cooling shaft.

Abstract: A first cylindrical drum member is rotatably supported on a platform assembly and has a longitudinal axis that is coplanarly aligned with the longitudinal axis of a second cylindrical drum member that is supported independently of the first drum member and positioned in tandem relation thereto. The first drum member has an inlet end portion through which a pair of feed screw conveyors extend to supply agglomerative materials, such as preheated coal and char, to the inner portion of the first drum member. An outlet portion of the first drum member extends into the inlet portion of the second drum member. A platform assembly is provided that includes a pair of vertically extending leg portions through which a pair of shafts transversely extend to permit pivoting the first drum member. The longitudinal axes of the respective drum members intersect at the transverse axis formed by the shafts so that the platform assembly is arranged to pivot about the intersection of the respective longitudinal axes.

Abstract: A method is disclosed for burning pulverous or granular raw material such as cement raw meal in a rotary kiln plant by directing a first flow of raw material to a cyclone preheater, preheating the first flow of raw material in the cyclone preheater, and directing the preheated raw material from the cyclone preheater to a rotary kiln for burning the material in the kiln. The burnt kiln product is directed to a cooler which may be of several types and which communicates with the material outlet of the kiln while a second flow of fresh raw material is directed to the cooler to at least partially cool the burnt kiln product by transferring heat therefrom to the second flow of fresh raw material in the cooler.

Abstract: Techniques for regulating calcining processes, particularly the calcining of lime containing materials, which are supplied as pulverized raw material, into cement clinkers in a cylindrical rotary koln, provides that the exhaust gas preheats the raw material and the calcined material preheats the combustion air. The quantity of raw material and the quantity of combustible material, the temperature of the combustion air and of the exhaust gas, as well as the composition of the exhaust gas, and additional parameters of the process are continuously measured and partially controlled. From the continuously measured individual values of the process a characteristic value describing the condition of the process, particularly the supply of heat, is formed, and is utilized to regulate the calcining process.

Abstract: A method and an apparatus is disclosed for producing such as Portland cement from pulverant raw material in a system having at least a preheater and a rotary kiln. The preheater may be of the type having a series of stages each provided by a cyclone dust separator for successively preheating the raw material in a counterflow of kiln waste gases and in which an identified one of the stages discharges a gas flow containing more thermal energy than can be used to advantage in preheating material in the remaining stages through which such gases must pass before dispersing in the surrounding atmosphere. A portion of the gases passing from the identified stage is diverted to a heat exchanger which utilizes the heat energy in such kiln waste gases to heat a clean stream of air.

Abstract: An installation for the manufacture of cement in a rotary tubular kiln comprises a combustion chamber upstream of the kiln, two preheaters for the raw material, one of the preheaters receiving hot gases from the kiln and the other preheater receiving combustion gases from the combustion chamber, and a cooler receiving the clinker from the kiln. One of the preheaters is a multi-stage preheater and all of the raw material is introduced into the one preheater one of whose stages is arranged to divide the raw material into two fractions. One of the raw material fractions is passed sequentially into the other preheater and into the combustion chamber while the other fraction is passed sequentially into the other stages of the one preheater and into the combustion chamber.

Abstract: An apparatus is disclosed for producing such as Portland cement from pulverant raw material having a preheater, an auxiliary furnace 22, a rotary kiln 2, a cooler, and a single blower connected to the top of the preheater to draw air and combustion gases through the kiln, auxiliary furnace and preheater. Preheater receives waste gas from the rotary kiln for flow through first, second, third and fourth level cyclones, with the first level cyclone(s) C.sub.1 being at an elevation higher than the kiln and the second, third and fourth level cyclones (C.sub.2, C.sub.3 and C.sub.4) each being at successively higher elevations. The auxiliary furnace 22 is preferably at the approximate level of the second level cyclone C.sub.2. The auxiliary furnace 22 is fed pulverant material from third level cyclone C.sub.3 and discharges pulverant material to a flue leading from the kiln to first level cyclones C.sub.

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: The combustion air, which is induced into a calcining furnace (calciner) from the lower end thereof and is vigorously swirled upward along the furnace wall, is burned by a plurality of burners and the negative pressure region may be developed at the center portion of the furnace. The exhaust gases leaving a rotary kiln, in which the calcined raw materials are burned to clinker, are led upwardly from the center of the furnace bottom into the said negative region and mixed with combustion gases. The raw material particles may be fed directly into the said negative region or to kiln exhaust gases so as to be entrained into the said region.

Abstract: A method of heat treating a preheated, pulverous, raw material consisting of or containing lime, such as cement raw meal. By mixing at least part of the preheated raw material intimately with a fuel capable of carrying out at least a partial calcination, a suspension of raw material in a combustible gas is provided. Upon providing a flow of oxygen-containing gas in contacting relation with the suspension of gas/material, at least a partial calcination takes place according to an endothermic process in which calcium carbonate is dissociated into calcium oxide and carbon dioxide. A finishing calcination and/or other heat treatment may follow the calcination process. When the raw material is cement raw meal, the aforesaid finishing heat treatment following the calcination is a sintering by which cement clinker is produced according to an exothermic process.

Abstract: A method is disclosed for manufacturing white cement wherein cement clinker is burnt in a kiln and prior to discharge from the kiln the clinker is contacted with a reducing agent such as fuel oil. The method further comprises discharging the hot cement clinker from the discharge portion of the kiln to a movable clinker supporting means such as a rotatable conveyor and quenching the cement clinker simultaneously with the discharge thereof from the kiln by subjecting the clinker to a spray of cooling water in a manner such that a major portion of the quenching water evaporates substantially immediately following the quenching.

Abstract: A process in which a substance undergoes endothermic change within a predetermined temperature range in at least one stage of the process and is subsequently subjected to a substantially higher temperature in a further stage of the process, characterised in that effluent heat from said further stage is augmented and the resultant supply of heat is applied partly to the generation of power, and partly to said endothermic change.

Abstract: A rotary kiln has a main cylindrical processing zone which is coupled downstream and upstream, respectively, to the charge-receiving and charge-withdrawal ports of the kiln through a pair of gas-tight spiral ducts. A reagent to be reacted with the charge is introduced coaxially into the main processing zone, and the spent reaction gases are coaxially removed therefrom. The reaction gas outlet conduit is provided with a hydraulic seal for maintaining a desired value of superatmospheric pressure in the main processing zone, and an additional gas conduit coaxial with the gas withdrawal conduit means is arranged to supply gaseous fuel to a plurality of heating tubes which are disposed in spaced relation through the walls of the main processing zone.

Abstract: This oven has a primary heating chamber containing heat-generating equipment producing hot gases. These gases pass from the primary heating chamber to a secondary heating chamber occupied by an indexing rotary magazine in object-exchanging relationship with a mechanism for inducing movement of the objects through the oven. The secondary heating chamber can be used for either pre-heating or heat-soaking the objects, depending on the direction of movement of the objects through the oven. The objects are loaded on the carrier (or removed, according to the application of the oven) radially at a position angularly spaced from the position of exchange with the movement-inducing means.

Abstract: Variable dual orifices in the restricted portion of the flue between the kiln and the preheater provides a controlled bypass of 0 to 100% of the kiln gases around the preheater and prevents short circuiting of process materials from the precalciner and mixing chamber to the kiln and provides a means for adjusting the orifice and system pressures to thereby provide stability of operation and control over the entire range of bypass; positive isolation of kiln gases from preheater gases during 100 percent bypass operation is ensured.

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 means and method for processing cement raw material containing fuel of high volatile content in a reinforced grate preheater kiln system by collecting the unburned volatiles of the high volatile fuel from the pellet bed and utilizing the collected volatiles as a fuel source elsewhere in the system.

Abstract: A method is disclosed for heat treating granular or pulverulent raw material wherein the raw material is directed to a heat exchanger having at least two preheating units operating in parallel, each preheating unit having at least a first preheating stage and at least a lowermost calcination stage to effect a preheating and at least partial calcination of the material. The preheated, at least partially calcined material is fed from the heat exchanger into a kiln and undergoes a sintering process in the kiln. The sintered material is directed from the kiln into a cooling means in which cooling air is directed in a manner to effect a heat exchange between the material and the cooling air.

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: Almost all of the powder materials, after having been calcined in a calcining furnace, are treated by the high temperature kiln exhaust without being directly fed into a rotary kiln, so that the materials may pass through at least two calcining zones in series so that they are calcined perfectly and uniformly before they are fed into the kiln, thereby contributing to make compact a rotary kiln in size and to improve overall thermal efficiency of the calcining and burning (sintering) apparatus.

Abstract: A rotating kiln having two rotating cylindrical chambers, these chambers having colinear axes which slope below the horizontal from the upper or loading end of the first chamber. The material to be processed into lightweight aggregate is introduced to the kiln at the upper end of the first chamber which is of narrower diameter than the second chamber. The lower end of the first chamber unites with the upper end of the second chamber providing an annular inner face for the second chamber.

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: A process and apparatus for the production of iron from iron ores, in which the ore is being heated and reduced in a rotary kiln by a treatment with solid carbon and with flame gas flowing in a countercurrent, the reduced iron is being collected and overheated in a first hearth furnace and is being fed in batches into a second hearth furnace, and is being converted there to pig iron, cast iron or steel, characterized in that the hot exhaust gases formed in the second hearth furnace are passed into the first hearth furnace and then through the rotary kiln together with the hot exhaust gases produced in the first hearth furnace.

Abstract: Raw material for making cement is treated in an installation comprising a plurality of superimposed cyclones constituting a multi-stage exchanger wherein the solid raw material and gases issuing from a clinkerization furnace circulate counter-currently, and wherein at least a portion of the raw material issuing from the penultimate exchanger stage is injected into the gas current produced by the furnace. The raw material is injected in the form of a "curtain", or "screen", into an upstream section of the furnace. This novel method and the novel device for carrying out said method allow the building-up of deposits upstream of the furnace to be eliminated.

Abstract: A device for treating granular or lumpy material by passing a gaseous medium therethrough characterized by a chamber having a material discharge device at the lower end and a material supply device comprising a pair of coaxially arranged supply channels at the upper end. The chamber has either a gas inlet or a plurality of burners to provide a gas flow through a portion of the material in the chamber and the material being added through the supply channels which are each connected to separate gas discharge conduits so that the material being added to the chamber is subjected to a uniform treatment by the gaseous medium.

Abstract: An improved method is disclosed for heat treating a preheated, pulverous raw material such as cement raw meal wherein a stream of oxygen containing gas is directed through a calcination chamber and the preheated raw meal and a calcining fuel are fed separately therein in a manner which provides mixing of the raw meal and the fuel and thereafter creates eddys of the mixture when it contacts the oxygen containing gas. The combined stream is directed out of the chamber and particles of raw meal are separated therefrom. A calcination plant is disclosed for practicing the method of the invention and a rotary kiln plant is disclosed for burning cement raw meal in a manner which includes at least partial calcination according to the inventive method.

Abstract: A method is disclosed for heat treating pulverous raw material such as cement raw meal prior to subjecting it to further heat treatment such as sintering. By directing the raw material to a multi-stage preheater having a final stage which comprises at least two substantially equivalent sub-stages and directing hot gases to the preheater in a manner to contact the raw material, an effective heat exchange between the raw material and the hot gases is achieved. The raw material is directed from the penultimate preheater stage so as to be entrained in the hot gases prior to directing the hot gases to the sub-stages of the final stage of the preheater and the hot gases and entrained raw material are divided into substantially equal divisional flows with each divisional flow being associated with a sub-stage of the final stage.

Abstract: The shaft cooler comprises a plurality of power-driven adjacent horizontal hollow perforated comminuting rolls. An upper section of the shaft cooler is adapted to hold a layer of material from 50 to 100 cm. deep above the rolls. Cooling air is supplied to the interior of each roll to cause it to be discharged into such layer of material. An aftercooling section below the rolls is provided with means for indirect cooling of the comminuted material and has a depth which is several times that of said layer.

Abstract: Improvements in the apparatus for calcining powdered cement material and removing nitrogen oxides from the entire exhaust gases from the burning equipment. The apparatus comprises making the most of the sensible heat and fluidity of the cement material preheated by the burning equipment and using the material as a catalyst for diffusing and vaporizing the fuel, thereby producing reducing gases, and then bringing the reducing gases into contact with combustion gases from the kiln for stepwise combustion. The invention is also concerned with other improvements in the apparatus for carrying the method into practice.

Abstract: The specification describes an installation for producing cement in which a mixture of limestone and clay minerals is ground to raw flour and the raw flour is calcined in a rotary kiln with the supply of heat and is kilned to form clinker. Downstream from the rotary kiln an air flow mill is arranged, to which the clinker from the rotary kiln is passed. It has a fresh air supply duct for cooling the clinker during the grinding operation and the outlet for material to be ground is connected with the cement flour bunker with the use for this purpose of a filter and a blower.

Abstract: A rotary kiln has a cylindrical casing interrupted along its length by annular members which are welded into and constitute part of the casing and which are provided with outwardly projecting, profiled webs adapted for attachment to the mounting structure of cooler tubes which are arranged in planetary manner about the casing.