Method for the thermal treatment of calcareous mineral raw materials

摘要

A method for the thermal treatment of mineral raw materials containing calcium carbonate and similar carbonates, particularly for the production of calcined products such as burnt lime, cement, magnesite, dolomite or the like wherein the raw material carriers of the calcium or other carbonate constituents are supplied to the calcining unit with a particle size of from 1 mm to 25 mm. The calcareous constituents are preferably supplied to the calcining unit with a particle size from 1 mm to 4 mm. To achieve this condition, the raw material containing the calcareous constituents is preferably pre-crushed to a particle size below 200 mm and pre-homogenized. It is then supplied to a drying comminution system connected to the calcining unit at the gas side and is suspended therein in direct heat exchange relationship with the gases. The material is preferably processed by means of single-stage crushing and grading to form the appropriate particle size. The upper limit of the grain size is determined by the amount of free lime content or of the ignition loss of the calcined product to the extent that the limit is lowered with a high free lime content or a high ignition loss.