Improvement of the melting reaction in sintering process by the fine part selective granulation of clayish iron ores

Abstract

In order to clarify the melting reaction of iron ores with limestone fines, the melt formation process was directly observed. Single particle firing tests and small packed bed firing tests were carried out for evaluating the sintering performance of sinter mix pseudo-particles. It was made clear from the direct observation of melt formation that the melting behavior of solid phases formed from primary melt is important to improve the coalescence of sinter mix pseudo-particles. The iron ores containing quartzite ("quartz-rich iron ore") are easier in forming the melt than the ores containing much clay minerals ("clayish iron ore"). The pseudo-particle using fine clayish iron ores as the adhering part was strong both before and after firing. The results of a small packed bed sintering test showed that segregation of limestone in sinter mix is effective in forming the melt. The increase in limestone concentration of quartz-rich iron ore fines which are adhering to a coarse nucleus particle is the most effective for coalescing pseudo-particles and for making a desirable pore network during sintering. On the basis of these results, the "fine part selective granulation method of clayish iron ores" was newly proposed to improve the sinterine performance of iron ores.