8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Metallurgical coke remains an irreplaceable material in the production of hot metal in blast furnaces, providing the heat and the reducible gases necessary for the process. Coke also play an important structural role in the blast furnace, providing a permeable bed for the passage of gases and liquids. Coke mechanical strength is a key factor for the performance of blast furnace and is essentially governed by coke microstructure. The microstructure of metallurgical coke can be defined as the spatial distribution of the coke carbonaceous matrix and its porosity. In this work, a methodology was developed to perform a representative characterization of coke microstructure. Cokes were produced from individual coals and coal blends in laboratory and pilot scale. Particles of these cokes were prepared and observed under an optical microscope to obtain images that were later analyzed in open source software (ImageJ) using a sequence of commands to obtain the microstructure parameters, such as porosity, average pore size, pore size distribution, wall thickness and pore shape. The influence of variables such as coke particle size, number of coke particles and number of images per sample on coke microstructure parameters was investigated. In addition, this work will present the step by step commands performed in the image analysis software to obtain the coke microstructure parameters. The geometric parameters, together with a porosity, form the set of data that can be correlated with mechanical strength of coke.