For green production of iron ore sintering, it is significant to substitute fossil fuels by biomass which is a kind of clean and renewable energy. In this paper, three kinds of biomass fuels such as charcoal, charred-straw and molded-sawdust were studied as sintering fuels. The results show that, with the proportion of biomass replacing coke breeze increasing, the vertical sintering speed raises, but the yield and the tumble index of sinter decrease, so the replacement proportion should be appropriate for satisfying the productivity and the quality of sinter. The suitable replacing proportions of charcoal, charred-straw and molded-sawdust are 40%, 20% and 15% respectively, in which the emission of COx can be decreased by 18.65%, 7.19% and 5.39%, SOx by 38.15%, 31.79% and 28.90%, NOx by 26.76%, 18.31% and 15.49% respectively.

Pollutant emissions can be reduced by replacing coke breeze with biomass fuels in the sintering process. However, with increasing replacement ratio, yield and tumble index of the sinter decrease due to the increase in sintering vertical speed and the decrease in the combustion efficiency. The distribution of the fuel in the granules affects combustion, and the results of the research indicate that with the biomass fuels wrapped in the granules, the burning speed is reduced and the combustion efficiency improved because of the extended time of secondary combustion of CO. Biomass distribution inside the granules has been achieved by pregranulation. When biomass fuel replaced 40% coke breeze, the combustion efficiency increased from 86?92 to 87?90% by pregranulation and the yield and tumble index of the sinter was more competitive than using coke breeze alone. In addition, the emission of NOx is decreased by 30?71% with biomass distribution inside the granules.

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The influence of biomass fuel replacing coke breeze on flame front and combustion efficiency were studied. The results show that when coke breeze is replaced, the flame front is accelerated since biomass has superior combustion characteristics. Combustion efficiency is decreased, however, as biomass is of excessively high reactivity, which can both lower the maximum temperature and reduce the time at high temperature of the sinter bed. The proportion of biomass fuel replacing coke breeze should, therefore, not exceed 40%, otherwise, the mineralisation of sinter material is insufficient and the yield and tumbler index of sinter significantly deteriorate. By increasing the size of biomass fuel, sinter indices are improved since the burning velocity of biomass fuel is optimised. When the proportion of biomass fuels is 40%, the emissions of SO 2 and NO can be decreased by 40 and 28% respectively.