Change Of High Temperature Strength Of Pellets During Roasting In Shaft Furnace

Pelletizing is one of the major agglomeration measures. It possesses lots of attractive performance, such as good strength, uniform particle size, standardized shape, wonderful reductive etc. Resulting from these benefits, it can increase production, decrease coke, improve the indexes of economic and iron-making technology. Recently, pellets attract more and more concerns in iron and steel industry. However, their qualitys have an effect on iron-making technology. Pellets'strength is an important sign of pellets'consolidation.The change of high temperature strength of pellets during roasting in shaft was researched. Then the following conclusions were gotten:During oxidizing roast, the strength would rise and then drop rapidly with the temperature increasing. So there was a maxinmum roasting temperature.When the actual temperature lower than it, quality of pellets were all right. This value of Scheme 1, 2 and 3 was 1220℃, 1170℃, 1200℃.At the bottom of the lumpy zone of blast furnace, pellets suffered the biggest pressure while their strength were the smallest, so they broke up easily. The compressive strength has certain times relationship with its strength at actual temperature, thus its standard value may reduce to 840N.The results showed that the strength rose with the hoist of temperature. According to the requirements of blast furnace, it decided a minimum roasting temperature, whose value was 1094℃, 1042℃, 1081℃in Scheme 1,2 and 3.As the roasting time extending slowly, the compression strength of pellets were in upward trend. However, it would not intensify apparently if the roasting temperature higher. The effective roasting time is 10~35min, otherwise the utilization coefficient is undesirable.