Abstract
Several pretreatment methods of raw mix have been proposed to improve sintering reaction, such as, melting reaction of fine iron ores with limestone fines, assimilating reaction of coarse iron ores with the melt, and so on. For optimizing these pretreatment processes, it is important to clarify the effect of the structure of sinter mix pseudo-particles made by these processes on the sintering mechanism including the permeability during sintering and the combustion efficiency of coke breeze in sintering bed.
In this study, analytical research was carried out for evaluating the change in the sintering mechanism with some pretreatment methods of raw mix, i.e. the ordinary granulation [a], the high moisture granulation [b] and the fine part selective granulation method of clayish iron ores ([c] : with limestone, [d] : without limestone). Characteristics of sinter mix pseudo-particles were investigated and sintering pot tests were carried out under these pretreatment methods.
Permeability of packed bed was improved with increase in 2-5mm even-sized pseudo-particles. For increasing the amount of coke combustion (CO+CO2), it was also effective to concentrate coke breeze at the surface of pseudoparticles. The complete combustion rate of coke (CO2/(CO+CO2)) was improved with limestone concentration at the surface of pseudo-particles as case [d].
Though sintering speed was improved with these intensified granulating process [b], [c] and [d], the strength of sinter was decreased due to increasing in the cooling rate of sinter in the case of high moisture granulation [b]. By contrast, in case of the selective granulation [c] and [d], the strength of sinter was improved due to the increase in melt formation and the decrease of cooling rate of sinter.
