X-ray examination of the structure of blast-furnace cores

The purpose of performed X-ray examinations was to understand the changes i n the structures of coke during the blast-furnace process. Prolonged (many- hour) heating of coke (at a temperature of about 2000 degreesC) in a reduci ng atmosphere and under high pressures prevailing in the blast furnace may cause slightly different changes in the structure that typical graphitizati on. Experimental tests were carried out on three groups of coke samples: th e so called burden coke (delivered from the coking plant, and designated by KN), the coke taken from the tuyere level of the blast furnace (DWP), and cokes subjected to laboratory tests reproducing, to a certain extent, the c onditions prevailing in the blast furnace (TS) and (KB). The X-ray measurem ents made by the X-ray diffraction (XRD) method and the small-angle X-ray s cattering (SAXS) method have enabled the description of the following param eters characterizing the structure: the interplanar distance, d(oo2); the c rystallite size, L-e; the crystallinity factor, W-k; and the pore fractal d imension, D-p, and the boundaris of the fractality range (a, xi). The coke samples were characterized by some volumetric inhomogeneity, therefore part icle cross-sections and powder specimens were prepared. In the analysis of examination results, the average values of the measured parameters were pre sented for particular groups of cokes, which confirmed the presumption that an intensive development of the coke crystalline structure and transformat ions of the type of porosity occurred during the blast-furnace process. The se changes are probably the more extensive the greater is the degree of cry stallinity of burden coke loaded to the blast furnace. Thus, there is a pos sibility of controlling the changes in the structure of coke, and thereby i ts properties, which can be utilized for reducing the coke consumption in t he blast-furnace process.