Pore Structure and Combustion Properties of Coke Breeze Treated by “Partial Combustion Method ”

Abstract

In order to decrease the NO emission from the sintering machines of iron ores, a new heat treatment of coke breeze called “Partial Combustion Method ”was tried on a small scale.The decrease in the nitrogen content of coke was 25-35%under the conditions where about 18%of carbon in a coke particle was consumed by combustion to CO2 and then this hot CO2 gasified almost the same amount of carbon in other coke particles at the temperature of about 1400 °C.The porosity of coke increased remarkably because the tubular pores of over 10 microns in diameter grew by the gasification with CO2 and small ones of under 10 microns were formed as a result of the vaparization of the ash component.In the sintering process using the treated coke breeze, NO formation was reduced more than the removal of nitrogen from coke and the degree of NO reduction became up to about 60%.The analytical results on the relation between the pore structure and the CO, NO for-mation during combustion of coke showed that the decrease in the conversion ratio of organic nitrogen to NO was caused by the high porosity of coke.