Proposal for Reducing Emissions of SOx in Cement Plants

Abstract

In the cement industry, emissions of sulfur oxides, nitrogen, carbon dioxide and water are inherent in the manufacturing process. However, there are limits to the amount of SO<SUB><i>x</i></SUB> and NO<SUB><i>x</i></SUB> emissions; the inhalation of such substances entails risks to human health, and their interaction with the atmosphere results in the formation of sulfuric acid and nitric acid, causing acid rain. These emission limits are even more severe when there is co-processing in the production process. SO<SUB><i>x</i></SUB> emissions can be formed by burning fuel, but they can also be present in the raw materials used. The presence of sulfur-based compounds in the raw materials has a great impact on the cement industry, owing to the large amount of limestone used in the process, especially when the deposits have a high content of pyrite (FeS<SUB>2</SUB>). One of the barriers encountered in the process of environmental licensing for co-processing is the high level of SO<SUB><i>x</i></SUB> emissions. To decrease these emissions and to enable co-processing in a cement industry, tests were performed, using abatement with lime (CaO). By varying the conditions of the manufacturing process, it was possible to obtain a reduction of up to 90% of the SO<SUB><i>x</i></SUB> emissions. With the implementation of this technique, SO<SUB><i>x</i></SUB> emissions reached values that met the legal limits, which could enable the start of co-processing in the industry.