Failure Strength of Cokes Reacted with CO2

Abstract

The intensive studies on the strength degradation of blast furnace cokes after gasification reaction are essential for developing mechanically strengthened coke with highly reactive nature to gasification. In this study, the degradation behavior of the mechanical properties of several types of cokes after their gasification reaction were investigated in instrumented spherical indentation and compression tests. The mechanical degradations were examined in the instrumented spherical indentation test for two types of cokes that were treated under about 20% gasification reaction. The indentation test results confirmed that the discrepancy in the degradation behaviors of mechanical properties (elastic modulus, yielding stress, and work-of-indentation) of these two cokes are insignificant, whereas there exists a significant discrepancy in the values of their drum indices (DI). In the compression test of coke grains, several types of cokes (differences in coal species, grain sizes, reaction temperatures, manufacturing conditions (formed coke, catalyst-added coke)) were tested. The Weibull statistic was applied to the results of compressive failure tests, where the concept of the work-of-compression was introduced, and successfully utilized in quantitatively examining the strength degradation of reacted cokes, and then it was clearly demonstrated that the grain size, reaction temperature, and the manufacturing condition are all essential in providing mechanically strengthened coke with highly reactive nature to gasification reaction.