A method to produce metallic beryllium spheres with high sphericity in a large quantity efficiently at a low cost is provided herein. The method of continuously producing metal beryllium spheres comprises the steps of: collecting granulated beryllium spheres produced by charging beryllium powder into a rotary kiln; classifying the collected beryllium spheres by particle size with an automatic sieve; and crushing particles of beryllium spheres of non-target diameters and mixing them with the raw material beryllium powder for reuse. The rotary kiln has a core tube the inner surface of which is coated with beryllium oxide by sintering the slurry coating of beryllium hydroxide applied after alkaline silica treatment.

A method to produce metallic beryllium spheres with high sphericity in a large quantity efficiently at a low cost is provided herein. The method of continuously producing metal beryllium spheres comprises the steps of: collecting granulated beryllium spheres produced by charging beryllium powder into a rotary kiln; classifying the collected beryllium spheres by particle size with an automatic sieve; and crushing particles of beryllium spheres of non-target diameters and mixing them with the raw material beryllium powder for reuse. The rotary kiln has a core tube the inner surface of which is coated with beryllium oxide by sintering the slurry coating of beryllium hydroxide applied after alkaline silica treatment.

In a known method for treating pourable, inorganic grain, a heated rotary tube is used that rotates about an axis of rotation and surrounds a treatment chamber that is divided into a plurality of treatment zones by means of separating elements. The grain is supplied to the treatment chamber at a grain inlet side and is transported, in a grain transport direction, to a grain outlet side and is exposed to a treatment gas in the process. In order, proceeding herefrom, to allow for reliable and reproducible thermal treatment of pourable inorganic grain, in particular SiO.sub.2 grain in the rotary kiln, in a manner having low and effective consumption of treatment gas, it is proposed for spent treatment gas to be suctioned out of a reaction zone of the treatment chamber, by a gas manifold that rotates about the longitudinal axis thereof.

In a known method for treating pourable, inorganic grain, a heated rotary tube is used that rotates about an axis of rotation and surrounds a treatment chamber that is divided into a plurality of treatment zones by means of separating elements. The grain is supplied to the treatment chamber at a grain inlet side and is transported, in a grain transport direction, to a grain outlet side and is exposed to a treatment gas in the process. In order, proceeding herefrom, to allow for reliable and reproducible thermal treatment of pourable inorganic grain, in particular SiO.sub.2 grain in the rotary kiln, in a manner having low and effective consumption of treatment gas, it is proposed for spent treatment gas to be suctioned out of a reaction zone of the treatment chamber, by a gas manifold that rotates about the longitudinal axis thereof.

Provided are an apparatus for manufacturing a compound powder, a method of manufacturing an iron-boron compound powder by using the apparatus, a boron alloy powder mixture, a method of manufacturing the boron alloy powder mixture, a combined powder structure, a method of manufacturing the combined powder structure, a steel pipe, and a method of manufacturing the steel pipe The method of manufacturing the boron alloy powder mixture includes: preparing a mixed powder including a boron iron alloy powder and a target powder; heat-treating the mixed powder to boronize at least a portion of the target powder and de-boronize at least a portion of the boron iron alloy powder, thereby de-boronizing the boron iron alloy powder to reduce the melting point of the boron iron alloy powder.

A process and an apparatus are disclosed for improved recovery of metal from hot and cold dross, wherein a dross-treating furnace is provided with a filling material with capacity to store heat. This filling material is preheated to a desired temperature by injection of an oxidizing gas to burn non-recoverable metal remaining in the filling material after tapping of the recoverable metal contained in the dross and discharging of the treatment residue. When dross is treated in such furnace, the heat emanating by conduction from the filling material is sufficient to melt and separate the recoverable metal contained in the dross, without addition of an external heat source, such as fuel or gas burners, plasma torches or electric arcs and without use of any salt fluxes. Furthermore, the recovered metal being in the molten state can be fed to the molten metal holding furnace without cooling the melt.

A process and an apparatus are disclosed for improved recovery of metal from hot and cold dross, wherein a dross-treating furnace is provided with a filling material with capacity to store heat. This filling material is preheated to a desired temperature by injection of an oxidizing gas to burn non-recoverable metal remaining in the filling material after tapping of the recoverable metal contained in the dross and discharging of the treatment residue. When dross is treated in such furnace, the heat emanating by conduction from the filling material is sufficient to melt and separate the recoverable metal contained in the dross, without addition of an external heat source, such as fuel or gas burners, plasma torches or electric arcs and without use of any salt fluxes. Furthermore, the recovered metal being in the molten state can be fed to the molten metal holding furnace without cooling the melt.

A cement clinker producing system, capable of providing a gas containing a carbon dioxide gas at a high concentration by increasing a carbon dioxide gas concentration for a part of an exhaust gas, includes a cyclone preheater to preheat a cement clinker raw material, a rotary kiln to burn the preheated cement clinker raw material so as to provide cement clinker, a calcination furnace to promote decarbonation of the cement clinker raw material, a clinker cooler to cool the cement clinker, a kiln exhaust-gas discharge passages to discharge an exhaust gas generated in the rotary kiln, a combustion-supporting gas supply device to supply a combustion-supporting gas having a higher oxygen concentration than air, a combustion-supporting gas supply passage to guide the combustion-supporting gas to the calcination furnace, and a calcination furnace exhaust-gas discharge passage to discharge a carbon dioxide gas-containing exhaust gas generated in the calcination furnace.

A rotary tube kiln, with a rotatably mounted rotary tube, which has a motorized drive, a mounting, a material inlet and a material outlet, wherein the interior space of the rotary tube has a process space, the inside atmosphere of which is separate from the outside atmosphere. The process space is sealed off from a pressure space by means of a first seal and the pressure space is sealed off from the outside atmosphere by means of a second seal and, by means of a pressing device, a first pressing force can be applied to the first seal and a second pressing force can be applied to the second seal, the first pressing force can be set independently of the second pressing force and, during operation, the internal pressure of the pressure space is higher than the internal pressure of the process space.

A rotary tube kiln, with a rotatably mounted rotary tube, which has a motorized drive, a mounting, a material inlet and a material outlet, wherein the interior space of the rotary tube has a process space, the inside atmosphere of which is separate from the outside atmosphere. The process space is sealed off from a pressure space by means of a first seal and the pressure space is sealed off from the outside atmosphere by means of a second seal and, by means of a pressing device, a first pressing force can be applied to the first seal and a second pressing force can be applied to the second seal, the first pressing force can be set independently of the second pressing force and, during operation, the internal pressure of the pressure space is higher than the internal pressure of the process space.