Production of high-strength and low-gasification reactivity coke from low-grade carbonaceous materials by vapor deposition of tar

Carbon/carbon composites were prepared from pyrolyzed-chars of lignite or low-strength coke (drum index of DI6150 = 52) and a coke-oven-gas tar through a gaseous-tar vapor deposition method to investigate the possibility of producing high-strength coke from low-grade coal or coke. The optimum vapor deposition temperature was examined under tar pyrolysis temperature of 700 degrees C and holding time of 30 min. The highest strength of prepared composite was observed at a vapor deposition temperature of 300 degrees C. The pore volume of the composite prepared at the vapor deposition temperature of 300 degrees C was the smallest among other samples prepared at that of 400-700 degrees C. The strength was improved by filling the carbonaceous materials derived from tar into the pores. The tar utilization coefficient was extremely low at 1.0 wt% or less. When same treatment was carried out for coke with different DI and pyrolyzed-cahr of lignite under the optimum conditions, it became clear that the composite prepared from any coke or pyrolyzed-char of lignite is comparable in strength to high-strength coke (DI6150 = 87). It was thus found that the present method can prepare high-strength coke from low-grade carbonaceous materials. The gasification rate of the composite prepared from low-strength coke was 0.5 times smaller than that of the original sample.