β-Sialon powder was synthesized by in-situ carbothermal reduction-nitridation process, with fly ash and carbon black as raw materials. The influence of raw materials composition on synthesis process was investigated, and the phase composition and microstructure of the synthesized products were characterized by X-ray diffraction and scanning electronic microscope. The carbothermal reduction-nitridation reaction process was also discussed. It was found that increasing carbon content in a sample could promote the decomposition of mullite in fly ash and the formation of β-Sialon. The β-Sialon could be synthesized at 1550°C for 6h by heating the sample with the mass ratio of fly ash to carbon black of 100:56. The β-Sialon as-received in this study existed as granular with an average particle size of about 2μm. The carbothermal reduction-nitridation reaction process consisted of the nitridation processes of mullite, SiO2and Al2O3in fly ash as well as the conversion process of X-Sialon to β-Sialon.

In order to get the reasonable sinter basicity and suitable burden structures in Ansteel, the metallurgical performance of sinter, the softening-melting properties with different burdens were studied systematically in laboratory. The results show that, the reducibility and the reduction disintegration are improved, and the mineral compositions of the sinter become reasonable with the basicity increasing. When the basicity reaches 1.95-2.15, the burden structures with single sinter will achieve good softening-melting performance, and the maximum pressure maintains at a low level. When the sinter collocates with pellet and the basicity reaches 1.90-2.15, there will be narrow softening and melting zones and a low S property value. With the addition of natural lump ore, the softening zone will be widened and the melting zone will be narrowed, but burden’s comprehensive performance will be bettered. The assessment indexes obtained for the interactive reaction between burdens can assess the reasonableness of burden structure. Considering the reactivity index and the economic cost, the reasonable proportion of lump ores in blast furnace needs to be controlled within 15%-20%.

In order to improve the qualities of sinter of Ansteel, the sinter’s metallurgical property was examined and analyzed that from the second workshop and the fourth workshop of ironmaking plant. And mineralogical composition and microstructure in high basicities sinter were investigated and analyzed by the X-ray diffraction, the optical microscope and the scanning electron microscope in laboratory. It was found that the differences between in sinter’s mineralogical composition and microstructures are according with the differences in chemical composition and the metallurgical indexes. Both the sinter’s minerals are mainly composed of hematite, magnetite or maghemite, calcium ferrite, dicalcium silicate, silicate glass phase. The content of the carbon in the fourth workshop is higher. So, it should decrease the content of the carbon that makes the microstructure of the sinter more rational.