Catalysis of the ammonium salts in the SO2 emission reduction of cement kilns

摘要

The emissions of SO2 in the cement kilns is mainly a consequence of sulphurs contents in the raw materials and when they are feeding to the kiln are decomposed and oxidized to SO2, crossing the circuit with the raw mill, the conditioning of gas temperature tower and finally the filter and going out as emissions to the atmosphere. The state of the art to diminish of this type of emissions as a better available technology is the injection of calcium hydroxide in different points of the process with very different performances in different situations. In this work we have studied how to reduce the above mentioned emission and the important influence on it of the ammonium salts as a catalysts elements in the improvement of the kinetic of the reactions of neutralization of the SO2 with the calcium carbonate of the raw materials and with the calcium hydroxide from the injection. We have reached the conclusion that the balance concentration of the ammonium salts obtained in the different points of the process has increased since the electro filters have been replaced in the last years by bag filters with lower work temperature, lower than 200 oC, increasing the stability of ammonium salts, avoiding its decomposition and having an important influence in the catalysis in the neutralization reactions of the SO2 in the gas circuit before its exit of the filter. The knowledge acquired in this work supposes a very important and new advance in the technology of reduction of emission of SO2 in an efficient way.