Experimental research on semi-coke for blast furnace injection

The combustion properties and grindability of Shenmu low-rank coal (SM) and its four different semi-cokes were studied by the self-designed equipment and Hardgrove method. The four semi-cokes were obtained under the pyrolysis temperature of 400, 500, 600 and 700 °C, named as SM-400, SM-500, SM-600 and SM-700, respectively. The analyses of nitrogen adsorption, Fourier-transform infrared spectroscopy (FTIR) spectra and Raman spectra were carried out to explain the change in combustion ratio and grindability. The result showed that the specific surface area of samples had an essential effect on the combustion ratio of SM-400 and SM-500. Meanwhile, the grindability depended on the strength of coal matrix, and the augment of pore amounts would increase the grindability. The functional groups and graphitization degree of the same sample were identical with the combustion ratio. With the pyrolysis upgrading temperature increasing, the combustion ratio of sample decreased, corresponding to the decrease in the benzene ring and the increase in graphitization degree. In addition, the thermogravimetric analysis was carried out, and the result was compared against what was shown in the data of combustion ratio. For pulverized coal injection, the combustion ratio was more intuitive and more accurate than combustibility.