GB404863A - Process of and apparatus for the production of portland and aluminous cements - Google Patents

Abstract

404,863. Portland and like cements. METALLGES. AKT.-GES., 45, Bockenheimer Anlage, Frankfort-on-Main, Germany. May 26, 1933, No. 15299. Convention date, April 4. [Class 22.] In producing Portland, aluminous or like cement in which a mixture containing fuel is calcined on fixed or travelling grates by drawing or forcing air through it, the mixture consists of raw material, returned material and fuel, the mixture of raw material and returned material being in the proportion of 1 and 0.8 to 2.5 parts respectively ; the mixture containing less than 20 per cent moisture, and the raw materials or the greater part thereof being employed as sludge which may also contain the fuel. The lower layers of the mixture may contain less fuel or returned material. The returned material is preferably less than 10 mms. in size and the depth of the charge on the grate less than 40 cms. Preferably a coating of clinker is applied to the grate before the charge to prevent the grate from overheating. When air is induced through the charge the partial vacuum in the suction boxes is preferably below 120 cms. water gauge. The raw materials which may be used include gypsum, lime, blast furnace slag, bauxite, ashes, marl, clay, iron ores. As shown hoppers 1, 2, 3 contain fuel, raw material sludge and returned material which pass into a mixer 4 and via hopper 5 on to the travelling grate 6 on which hopper 15 has provided a first layer of broken clinker. Air is drawn through the charge via suction boxes 10 by means of fan 8. The sintered material is discharged into breaker 17 and from there to screen 11 which sorts it e.g. into three sizes, below 6 to 10mms. which is discharged at 14 and used as return material ; between 6 to 10 mms. and 20 to 25 mms. which is discharged at 13 and used as the coating layer for the grate ; and over 20 to 25 mms. which is passed to the grinding mills. Specification 375,950 is referred to.