Abstract
Sintering experiments were conducted in order to suppress the formation of large pores existed in the assimilated parts of sinter produced using pisolitic limonite ores. Modeled pseudo-particles, which consisted of coarse iron ore particle as cores and fine mixture of hematite ore and limestone as shell layer, were used in the present experiments. CaO concentration of shell fine was varied in three levels, i. e. 10, 20 and 30 mass% and ratio of shell fine was varied in two levels, i. e. 30 and 50 mass%. CaO concentration and ratio of shell fine were regarded as indices of apparent viscosity and volume of melt formed during heating. The influence of CaO concentration and the ratio of shell fine on the behavior of large pore formation during heating were examined by a microscopic observation. The mean diameter and area fraction of pores existed in the assimilated part of specimen were also measured. The results obtained were as follows:
1) With increasing CaO concentration and the ratio of shell fine, the area fraction and number of pore were decreased; the suppression of the large pore formation was achieved.
2) The decrease in both of the area fraction and number of pore depend on the lowering apparent viscosity and increasing volume of melt formed during heating.
3) The lowering apparent viscosity of melt is more effective to suppress the formation of large pore than increasing volume of melt.
4) It is clear that the suppressive effect is resulted from the promotion of coalescence of bubbles due to the lowering apparent viscosity of melt formed during heating.
