Abstract: An object of the present invention is to provide a heavy metal removing apparatus which can efficiently remove the heavy metal contained in the dust produced by burning of the raw material containing the heavy metal, and a cement production system comprising the heavy metal removing apparatus. The heavy metal removing apparatus 10 comprises a cyclone separator 11 which separates exhaust gas containing the heavy metal from a part of the dust heated to a temperature equal to or more than a temperature at which the heavy metal can volatilize, a bag filter 13 which is connected to the subsequent stage of the cyclone separator 11 and separates the exhaust gas containing the heavy metal from the remainder of the dust, and a heavy metal removal tower 14 which is connected to the subsequent stage of the bag filter and removes the heavy metal from the exhaust gas.

Abstract: An object of the present invention is to provide a heavy metal removing apparatus which can efficiently remove the heavy metal contained in the dust produced by burning of the raw material containing the heavy metal, and a cement production system comprising the heavy metal removing apparatus. The heavy metal removing apparatus 10 comprises a cyclone separator 11 which separates exhaust gas containing the heavy metal from a part of the dust heated to a temperature equal to or more than a temperature at which the heavy metal can volatilize, a bag filter 13 which is connected to the subsequent stage of the cyclone separator 11 and separates the exhaust gas containing the heavy metal from the remainder of the dust, and a heavy metal removal tower 14 which is connected to the subsequent stage of the bag filter and removes the heavy metal from the exhaust gas.

Abstract: A process for preparing .beta.,.gamma.-unsaturated aldehydes which comprises dehydrogenating .beta.,.gamma.-unsaturated alcohols in the vapor phase, preferably in the substantial absence of oxygen, using copper having a specific surface area of 0.01 to 1.5 m.sup.2 /g as a catalyst at a temperature of 150.degree. to 300.degree. C. The .beta.,.gamma.-unsaturated aldehydes can be recovered in pure form by distilling the dehydrogenation reaction mixture in the presence of water. The starting .beta.,.gamma.-unsaturated alcohols can be prepared by reacting olefins with formaldehyde or a derivative capable of forming formaldehyde at a temperature of 180.degree. to 400.degree. C. in the absence of a solvent or in the presence of a non-aqueous organic solvent after pre-heating said formaldehyde or derivative to a temperature of 85.degree. to 150.degree. C.

Abstract: A process for the preparation of pyridines, which comprises contacting in the vapor phase saturated or unsaturated hydrocarbon of more than one carbon atom, ammonia, and molecular oxygen, with the catalyst composed of solid acid containing at least tellurium, said solid acid containing the acid of which acid strength (Ho) is not weaker than 4.8.