DEVELOPMENT OF LABORATORY TESTS TO EVALUATE STICKING TENDENCY

摘要

One of the most important risks that appears in the process of direct reduction, is the tendency to the clustering or sticking that the pellets experience at high temperature. The Sticking test allows to predict the behaviour of these pellets against this phenomenon. TenarisSiderca asked Instituto Argentino de Siderurgia (IAS) to jointly develop a new methodology for the determination of the Sticking and Cluster as the standard test did not represent what happened in the operation. In these tests, pellets are reduced, carburized and cooled with both temperature and gas composition profiles simulating the reducing furnace operation. For over 20 years, a testing methodology with a maximum temperature of 840°C has been used. However, reducing conditions have changed considerably due to different improvements implemented in the process, which enabled a very significant increase in plant productivity. For this reason we have developed a new test adapted to the present operating conditions regarding the residence time of the material, composition and temperature of gases and final quality of sponge iron. This new test allowed the identification of samples with most sticking tendency, this behavior could not be appreciated with traditional tests at 840°C. Besides, it was verified the positive influence of the coating applied in plant. Many samples were studied from different sources.