Method and plant for drying and comminution of moist, mineral raw materials

Abstract

Described is a method as well as a plant for drying and comminution of moist, mineral raw materials, such as chalk, marl and clay, by which method the raw materials are dried and comminuted subject to simultaneous supply of hot gases in a drier crusher (8) from which the material is subsequently directed in suspended form to a separator (11) in which it is separated into a coarse fraction which is returned to the drier crusher (8) for further drying and comminution and into a fine fraction which is directed to the next stage of the process and where any hard material components such as flint, sand and marble are subjected to grinding in a separate grinding unit (16). The method and plant is peculiar in that a part quantity of the coarse fraction from the separator (11) is proportionately fed to the separate grinding unit (16) for the grinding of hard material components. Hence, it will be possible to substantially reduce the specific energy consumption and the CO2 emission from the kiln system due to the elimination of need prior to drying and comminution in the drier crusher to suspend the raw materials in water which must subsequently be removed. This is ascribable to the fact that the hard material components by the method according to this invention will be drained away from the circuit between the drier crusher and the separator. A further advantage of the method according to this invention is the significant reduction achieved in the wear rate of the drier crusher and its energy consumption. Furthermore, it will be possible to produce a raw meal with excellent burning characteristics due to the reduction in the content of coarse silica particles in the raw meal, which in turn will reduce the NOx emission from the kiln.

Description

technical field [0001] The present invention relates to a method of drying and pulverizing moist mineral raw materials such as chalk, marl and clay, by which said raw materials are dried and pulverized in a dry crusher while supplying hot gas, and the material is subsequently removed in suspension from The drier crusher is sent to a separator where the feedstock is separated into a coarse fraction and a fine fraction, the coarse fraction being returned to the drier crusher For further drying and comminution, the fine fraction is sent to the next stage of the process and in the process any hard material components such as flint, sand and marble are ground in a separate grinding unit. The invention also relates to a device for carrying out the method. Background technique [0002] The lack of methods and apparatus of the foregoing type is well known within the cement manufacturing industry. In practice, in the methods used in many cement installations around the world, the a...

AI Technical Summary

Problems solved by technology

Of course, the disadvantage of this method is the incidental requirement that all raw materials be slurried in a significant amount of water, which must then be removed, for example by filtration or evaporation

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