Abstract: The invention relates to the cooling of hot bulk material, particularly cement clinker, ore material or the like, in a grate cooler, in which the bulk material is transported on the cooler grate surface toward an outlet and exposed to cooling gas from below. At least a part of the relatively cooler lower portion of the material layer is discharged through suitable chutes upstream of the cooler outlet while in transport to increase the cooling efficiency of the process.

Abstract: The invention relates to a method of producing cement clinker from fine-grained cement raw material which after preheating and calcining is burnt in a clinker burning zone divided into two stages and is then cooled. Optimum process conditions, particularly in the clinker burning zone, are achieved in that the calcined material is first of all heated to a temperature up to the region of the sintering temperature in a stage formed by a fluidized bed or spouted bed so that a build-up granulation of the material is brought about, whereupon the material thus heated is heated to the sintering temperature in a second stage of the clinker burning zone which acts as the finish-burning stage and tempered to the finishing burn.

Abstract: The invention relates to the comminution of material for grinding, particularly for the production of cement, wherein the material for grinding is comminuted in a mill and the comminution product is classified in a classification zone into fines and oversize material and the oversize material is returned to the mill. With a view to effective influencing of the breadth of the particle size distribution as well as a relatively low specific energy consumption the comminution product is classified in the classification zone in at least two air separators which are connected one behind the other in series, and a proportion of the oversize material from the first air separator is returned directly to the mill, the remaining proportion being delivered to the second air separator.

Abstract: The invention relates to a method of purifying the exhaust gases from plants for the production of cement clinker, in which the filter zone through which the exhaust gases flow contains at least one adsorption stage in which an adsorbent is provided which is suitable for fixing NH.sub.x compounds, heavy metals and/or trace pollutants, at least a proportion of the adsorbent being removed from the adsorption stage at specific intervals of time and introduced into the final burning zone and/or preheating zone. By such a method the NO.sub.x content of the exhaust gases is significantly reduced, and at the same time heavy metals and trace pollutants are eliminated from the exhaust gases.

Abstract: The invention relates to a method and apparatus for purifying the exhaust gases from plants for the production of cement clinker, in which in a multi-stage filter zone hot exhaust gases coming from a preheating zone are first of all cleaned of dust in a first filter stage and then in a further stage are purified of NH.sub.x compounds, heavy metals and trace pollutants, SO.sub.z and NO.sub.x. In order to achieve a particularly efficient and economic purification, the exhaust gases from the preheating zone are set before the first filter stage to such a filter zone inlet temperature that in this first filter stage at least a proportion of the easily volatile pollutant elements and pollutant compounds are precipitated out of the exhaust gases in addition to the dust.

Abstract: The invention relates to a method and apparatus for cooling fired bulk material in which the height of the material bed on a grate conveyor in a first cooling zone is set by the conveying speed of the grate and by gravity. Thus in a particularly simple way the height of the material bed on the conveyor is adjusted in the transport direction in the first cooling zone which serves for heat recovery.

Abstract: Apparatus for heat treating fine-grained material comprises a rotary kiln into which material is delivered from a multistage preheater that communicates with the kiln via a vertical exhaust gas duct. Treated material is discharged from the kiln to a cooler from which two cooling air ducts extend and communicate with the exhaust gas duct at two vertically spaced zones. Material from the second lowest preheater stage is introduced into the exhaust gas duct adjacent the lower cooling air duct. Fuel is introduced into the exhaust gas duct adjacent each of the cooling air ducts. The apparatus is distinguished by a particularly high degree of deacidification of the raw material and good combustion of the fuel.