Degradation and Microstructure Changes of Tuyere Coke Behavior of a COREX-3000 Furnace

Abstract

The behavior of tuyere coke obtained from a COREX-3000 process was investigated in the present study for an in-depth understanding for the condition of raceway. The coke samples was obtained in a dissection process of the furnace, and coke samples at P1 (200 mm from tuyere sleeve towards the furnace center), P2 (400 mm from tuyere sleeve towards the furnace center), P3 (600 mm from tuyere sleeve towards the furnace center), P4 (800 mm from tuyere sleeve to the furnace center), P5 (1 000 mm from tuyere sleeve to the furnace center) and P6 (1 200 mm from tuyere sleeve to the furnace center) were sieved, and the particles size distribution and average size of different position has been calculated. Microstructure of coke samples at P2, P4 and P6 was examined using scanning electron microscopy, and carbon structure and mineral phases of coke samples at P6 were identified using X-ray diffraction (XRD) analysis. The results showed that the percentage of small coke particles (<10 mm) was higher at P5 and P6, and the average particle size of coke samples at P5 and P6 were 12.04 mm and 7.71 mm, which is much smaller than that of other samples indicating a severe degradation of coke. The amount of pores of tuyere coke increased compared with charged coke, and more pores were found in coke sample at P6 than P2 and P4, indicating a violent reaction at this position. The graphitization degree of tuyere cokes at P6 were much higher than that of charged coke, and coke particle (10–16 mm) possess the highest graphitization degree, indicating the much higher temperature in the raceway zone. The main minerals in the tuyere coke were gehlenite and akermanite, and the slag was melt to be spherical particles confirming the higher temperature in raceway zone in COREX-3000 process.