Research On The Application Of Biomass In The RHF Direct Reduction Process

Rotary hearth furnace(RHF) direct reduction is a process with high productivity and wide application scope, as the main raw material for this process, carbon containing pellets is paid wide attention. The domestic and foreign researchers proceed a lot of researches about coal, coke and other traditional reductant. Facing with the situation of resource and environment, biomass, as a kind of clean, renewable and large reserves raw materials, has also got some researches and application, but the discussion of using biomass into this process is rare. Therefore, a series of experimental study needs to be done.In this studies, box atmosphere resistance furnace were used for simulating RHF, then selecting different temperatures, additional amount of carbon, collocation patterns, particle size and holding time to estimate the application of biomass from volumetric shrinkage, compressive strength and metallization rate. In addition, using TGA, XRD and SEM analyses the process from raw material to product, based on which, the optimized conditions of this application has been discussed.The application of biomass reductant in the RHF direct reduction process, compared with using the traditional, has considerable or even better effect. Due to the high gasification reactivity, the reduction effect of the pellets with biomass is better than the others in the prophase. The appropriate particle size of straw fibers should be 0.15 mm or less, while the available maximum particle size of charcoal is 3mm; The better mass additional ratio of carbon is C/O=0.7. Meanwhile, according to the collocation ratio of 20%:80%(carbon content), mixing straw fiber with bamboo char or charcoal-2 respectively, which can improve the disadvantages of using the latter two reductants independently. Besides, higher temperature(1200℃) is conducive to the produce of metal iron and increasing of volumetric shrinkage and strength, and this improvement will be enhanced under a holding time(20min), which is helpful to achieve multi-layer burden in RHF. In a word, above results provide reference and guidance for the application of biomass in RHF direct reduction process.