Reduction behavior and crushing strength of carbon-containing iron ore sinters prepared from tar recovered from coke oven gas

The reduction behavior and crushing strength of carbon-containing iron ore sinters (SI–C) prepared from coke oven gas (COG) tar have been examined with a quartz-made fixed bed reactor and with a tensile and compression testing machine, respectively. When an as-received iron ore sinter (SI) is heated at 10 °C/min up to 600 °C in 55% H 2 /He, the resulting sample (SI/600) gives a very small, broad pore size distribution profile, the surface area (S BET ) and pore volume (V BJH ) being 1.5 m 2 /g and 0.005 cm 3 /g, respectively. On the other hand, SI-pretreated in 55% H 2 /He at 450 °C for 4 h (SI-450) provides the pore distribution profile peaking around 10 nm, and S BET and V BJH are 4 m 2 /g and 0.02 cm 3 /g, respectively. When carbon-containing iron ore sinters (SI/600–C and SI-450–C) are prepared by pyrolysis of the mixture of the pretreated SI and COG tar, no measurable amounts of S BET and V BJH are detectable in any case. The crushing strength of SI-450 is improved significantly by the deposition of tar-derived carbonaceous materials into the pores formed during the pre-treatment. In a temperature-programed heat treatment in He, the evolution of CO, CO 2 and H 2 O from the SI-450–C samples start after 600 °C, and each rate profile observed shows a large peak around 700–850 °C. The extent of reduction of SI–C, SI/600–C or SI-450–C is 3, 19 or 55% on SI basis, respectively, and it depends on S BET and/or V BJH of the feed sample.