A method for burning material, such as carbonate rocks, in a parallel-flow regenerative shaft kiln having two shafts which are operated alternately as a burning shaft and as a regenerative shaft and are connected to one another by means of a connecting channel, wherein the material flows through a material inlet into a preheating zone for preheating the material, a burning zone for burning the material and a cooling zone for cooling the material to a material outlet, wherein a cooling gas is admitted into the cooling zone, wherein exhaust gas is discharged from one of the shafts via an exhaust gas outlet, wherein the exhaust gas discharged from the shaft via the exhaust gas outlet is at least partially introduced into at least one of the shafts.

The present invention relates to device for heat-treating solid material, in particular in granular form, wherein the device comprises a kiln and an external heat source, wherein said device comprises at least two steps arranged above each other, wherein each step comprises a gas permeable sloped sliding surface on which a bed of said solid material slides down within said device due to gravity and wherein said sloped sliding surfaces of said steps directly consecutive to each other slope in opposite directions, wherein the kiln comprises at least one, preferably at least two, of said steps and the kiln is configured such that a hot gas generated by the external heat source is led through said solid material inside the kiln to heat said solid material to a desired temperature in order to change the substance properties of said solid material. According to the invention, said device comprises at least one gas temperature adjustment system comprising a gas outlet in a second step of said steps, a temperature adjustment zone and a gas inlet in a first step of said steps, preferably the first step being arranged directly consecutive and above the second step, wherein at least the first step is one of said at least one step inside the kiln and wherein said gas temperature adjustment system is adapted such that hot gas is extracted from said second step through the gas outlet, directed into the temperature adjustment zone where a hot gas temperature is adjusted to an adjusted temperature by the external heat source and reintroduced into said first step at said adjusted temperature. The invention further relates to a method for producing supplementary cementitious materials.

A Portland cement production (PCP) process is conjoined with a waste-to-energy (WTE) process using refuse-derived fuels (RDFs). Both processes operate simultaneously to reduce harmful compounds being discharged into the environment. The PCP and WTE processes are conjoined by borrowing a minor portion of pre-heated comminuted limestone from a PCP process feedstream and diverting it to the WTE process. Some of the pre-heated comminuted limestone is converted to CaO. The calcium compounds from the pre-heated comminuted limestone act as a fluxing agents and sorbents to bind with and remove undesired impurities, such as elemental particulate matter, excess CO.sub.2 and acid gasses associated with sulfur and chlorine that are released during the pyrolization of RDFs. The ash, char waste and reacted calcium compounds from the pyrolization process can be comingled and returned to the PCP process as a secondary cement meal feedstock.

A process for activating clays having high residual moisture by: feeding wet clay into a device for drying, comminuting the previously dried clay in a device for comminuting, thermally activating the comminuted clay in an entrained flow reactor or in a fluidized bed reactor in which the comminuted clay is in suspension in a hot gas, removing the gas from the entrained flow reactor or the fluidized bed reactor in a device for removing, and cooling the thermally activated clay in a device for cooling with a cooling gas, and to a corresponding plant. The cooling gas, heated after cooling the thermally activated clay, is combined with the gas from the reactor, and the combined gases are introduced into the drying device. The drying air is filtered after drying, and clay removed by filtration is unified with the dried clay.

A cement manufacturing plant includes a raw meal mill, at least one preheater string, a clinker furnace and a clinker cooler including a first section and a second section, wherein a preheater exhaust gas recirculation device is provided for recirculating exhaust gas leaving the at least one preheater string into the first section of the clinker cooler, and wherein the cement plant is configured for switching between an air operation mode and an oxyfuel operation mode, includes a first switching device for connecting either a source of air or a source of oxygen rich gas to a burning zone of the clinker furnace burner, and a second switching device for either establishing or separating a connection of the preheater exhaust gas recirculation means to the first section of the clinker cooler.

Apparatus. methods. and systems for heat treatment of solid materials utilizing an indirect rotary calciner comprising one or more thermal expansion tolerant inner tubes fixed to an outer rotating shell. for example. by one or more resilient support members. The described methods of thermal treatment may be particularly utilized with cement and lime production processes and/or other heat treatment applications. such as pyrolysis.

The invention relates to a process plant (20) for converting a solid input material into a solid process product. The process plant (20) includes a calciner which is connected to a heat exchanger (26) and to which the input material can be continuously supplied for heating in order to transform the input material into an intermediate product. In the process plant (20) there is a kiln for converting the intermediate product into the process product by means of thermal treatment, raw gas being produced in doing so. The process plant (20) has a raw gas line system (50) comprising a raw gas line (50.1) which extends from the kiln to the calciner and through which the raw gas can flow from the kiln into the calciner for transferring raw gas heat to the input material, and includes a cooling device for cooling the process product after the thermal treatment in the kiln by transferring heat from the process product to a cooling gas containing oxygen, as a result of which a hot gas containing oxygen is generated. According to the invention, in the process plant (20) there is a waste air purification device for oxidizing raw gas, which is connected to the calciner via a raw gas line system (50), wherein a hot gas line system which is used for supplying hot gas generated from the cooling device is attached to the raw gas line system (50). The invention also relates to a method for converting a solid input material into a solid process product and to a method for purifying raw gas produced during the manufacture of cement.

The present invention relates to a rotary kiln for burning carbonate-containing material, in particular limestone or dolomite, including a rotary tube with an inlet end for the feeding of the material to be burned and an outlet end for the discharging of the burned material, the rotary tube having an inlet zone at its inlet end and an outlet zone at its outlet end wherein a preheating zone and a combustion zone are arranged between the inlet zone and outlet zone, the rotary kiln being characterized according to the invention in that in the inlet zone of the rotary tube at least one projection is provided, the at least one projection having at least one sliding surface inclined to the longitudinal axis of the rotary tube for conveying the material to be burned from the inlet zone into the preheating zone. The present invention further relates to a method for burning carbonate-containing material, in particular limestone or dolomite.

A method and device for the combined manufacturing of cement clinker and calcined clay, in a cement manufacturing line by the steps: providing, preheating and precalcining a cement raw meal in a preheater and calciner section, sintering the precalcined cement raw meal in a rotary kiln and cooling the resulting cement clinker with a counter current air stream in a clinker cooler, and in a clay manufacturing line by the steps: providing and preheating a clay raw material in a heat exchange section, and calcining the preheated clay raw material suspended in gas in a flash calciner. Hot air from the cooler is divided into a first combustion air stream for sintering the cement raw meal and a second combustion air stream for calcining the clay raw material. Exhaust gas from calcining clay raw material is fed into the calcination of the preheated cement raw meal.

CO.sub.2 is produced in a cement clinker line by (i) converting a CaCO.sub.3 comprising raw meal into calcined raw meal and at least CO.sub.2 and/or sintering calcined raw meal in a kiln, there-by obtaining at least cement clinker and optionally CO.sub.2. The CO2 emission of the cement clinker line can be significantly reduced by, dissolving at least a portion of the CO.sub.2 in a first carboxylic acid and/or a first sulfonic acid and reducing the dissolved CO2 electrolytically at a cathode of an electrolytic cell to a second carboxylic acid and/or a second sulfonic acid, wherein the first carboxylic acid and/or first sulfonic acid is used as a protonic aqueous electrolyte.