The gasification of metallurgical cokes with CO2 and H2O on their porosity and macrostrength were investigated in the current study. Cokes were reacted with CO2 or H2O in the temperature range of 1100 to 1500 °C. During the reaction, the compositional change of product gases were measured by quadruple mass spectrometry (QMS) for evaluating the gasification rate. Image analysis was carried out to measure the porosity according to the distance from the coke surface. The porosity at the surface of coke gasified with CO2 indicated low values due to its low reactivity, which resulted in the intraparticle reaction to diffuse into the pores at low temperatures while the coke gasified with H2O showed the tendency to react with the coke at the surface. This difference in the reaction behavior can be explained by Thiele modulus. Furthermore, fine powder formation and tensile strength were measured to evaluate macrostrength of cokes. According to the results, the different reaction mode caused an obvious difference in the tendency of macrostrength of the cokes of the same reaction degree. Tensile strength of cokes was strongly affected by their porosity distribution.

No abstract

The effect of graphitisation by the variation of annealing time and temperature on the pore structure and apparent gasification rate at 1200 and 1500°C was investigated. The graphitisation degree of three kinds of coke used in this study was increased with annealing time and temperature. The increase in porosity of annealed coke sample is ascribed to the formation of silicon carbide. Annealing at 1200°C had less significant effect on the change of porosity in comparison with annealing at 1500°C. The mean area of pores was decreased, and pore density was increased with increasing annealing time while annealing had marginal influence on the pore shape. The apparent gasification rates of Coke 1 and Coke 2 with H 2 O were decreased by annealing, but 3 h of annealing increased the apparent gasification rate of Coke 3. The correlation between apparent gasification rate with H 2 O and macroporosity or graphitisation degree was investigated.