Energy & Fuels, Vol.30, No.12, 10448-10457, 2016
Assessment on the Application of Commercial Medium-Grade Charcoal as a Substitute for Coke Breeze in Iron Ore Sintering
The application characteristics of cost-effective commercial medium-grade charcoal (MG charcoal) in the sinter making process were assessed in this paper. The results showed that, in comparison to high-grade charcoal (HG charcoal), MG charcoal was characterized by a lower fixed carbon content, a higher volatile content, and a higher porosity and specific surface area, which led to its even greater difference in thermochemical behaviors with coke breeze than HG charcoal. This property of MG charcoal resulted in a faster sintering speed, a lower bed temperature, and a shorter holding time above 1200 degrees C for adhesive mineral melting, which restrained its proper replacement percentage at 20%, while it was 40% for HG charcoal. To achieve a sintering performance similar to the HG charcoal, the combustion behavior of MG charcoal and coke breeze was regulated simultaneously by coating fine-grained iron ore concentrate and adhering CaO, respectively. It was found that coating concentrate was useful to reduce the combustion rate of MG charcoal for reduced probability to contact air directly, while adhering CaO helped to accelerate the combustion rate of coke breeze as a result of the potential catalytic effect, which finally exhibited a relatively matched combustion speed. Sinter pot trials verified that, after pretreating MG charcoal particles and coke breeze through the pregranulation process, MG charcoal replacing 40% coke breeze showed a comparable sintering performance to the case using 100% coke breeze. The emissions of CO2, SO2, and NOx achieved an obvious reduction by 21.70, 27.75, and 18.31%, respectively.