The present invention relates to a method for reducing the amount of chloride compounds produced in a kiln for firing cement clinker. A basic operational problem of such kilns for firing cement clinker is at chlorine compounds are introduced into the firing chamber which originate from the raw material as well as the fuel. The chlorine compounds when they reach a temperature below their condensation temperature will deposit or surfaces and can result in disruptions of proper operation of the device. Chlorine introduction is especially disadvantageous in the production of cements with low alkali contents. Such cements are thus produced exclusively by employing raw materials and fuels of low chloride contents. For reducing operational costs it is desired to also be able to use raw materials and fuels of higher chloride contents for the production of cements of standard quality as well as for the production of low alkali cement. Only in this manner is it possible to employ waste as a secondary fuel in higher amounts than in the prior art.
In cement clinker firing processes with increased chloride contents it is known to install by-pass systems with which the operational disturbance caused by the furnace heat exchanger system can be reduced. However, this results in other disadvantages. On the one hand, by-pass systems increase the specific energy consumption of the device. On the other hand, for reasons of quality standards, the produced dust amounts cannot be added to the cement end product so that often disposal of the produced large amounts of dust is required either in quarries or in landfills. For processing dust having a high chloride contents with a weight proportion of the chloride compounds of more than 20% as well as for the manufacture of especially low alkali cements such conventional by-pass systems are therefore not suitable.
It is therefore an object of the present invention to provide a method for reducing the amount of chloride compounds produced in cement clinker kilns which allows to employ inexpensive raw materials and fuels, having a chloride contents higher than average, for the production of standard as well as low alkali cements.
USPTO Backgrounds
USPTO Backgrounds