带式焙烧机镁质球团制备及高炉应用情况

Preparation of magnesium pellets from belt roaster and its application in blast furnace

针对大幅度提高烧结矿中w(MgO)易导致烧结矿返矿率升高,入炉原料品位降低等问题,采用带式焙烧机配加MgO粉制备镁质球团矿的方法,研究在最佳热工制度和最佳球团矿粒级分布下不同w(MgO)对球团化学成分、冷态强度、冶金性能与高温固结特性的影响。结果表明:随着w(MgO)的增加,成品球团矿抗压强度明显下降,但成品球团矿的还原度有所提高,还原膨胀率明显降低,软化温度区间与软熔温度区间稍有提高。在预热时间为6 min,预热温度为950℃,焙烧时间为9 min,焙烧温度为1 170~1 190℃的热工制度以及进一步提高后的10.0~12.5 mm粒级球团矿占比下,可以得到冶金性能良好的成品球团矿。此时,高炉运行稳定、顺行,高炉经济技术指标明显提高,其中焦比降低6.9 kg/t,喷煤比降低2.2 kg/t,焦丁比降低0.4 kg/t,总燃料比降低9.5 kg/t。

Aiming at the problems of greatly increasing the w(MgO) in the sinter, which may lead to an increase in the return rate of the sinter, and a decrease in the grade of raw materials into the furnace, a method for preparing magnesium pellets by adding MgO powder with a belt roaster is used to research the effects of different w(MgO) on the chemical composition, cold strength, metallurgical properties and high temperature consolidation characteristics of the pellets under the best thermal system and the best pellet size distribution.The results show that, with the increase of the w(MgO),the compressive strength of finished pellets obviously decreases, but its reduction degree increases, its reduction expansion rate decreases, the softening temperature range and the reflowing temperature range slightly increase.Under the thermal system of preheating time 6 min, preheating temperature 950 ℃,roasting time 9 min, roasting temperature 1 170~1 190 ℃,and further increase in the proportion of 10~12.5 mm granular pellets, the finished pellets with good metallurgical properties can be obtained.At the same time, the blast furnace runs stably and smoothly, and the economic and technical indicators of the blast furnace are significantly improved, in which, the coke ratio is decreased by 6.9 kg/t, the coal injection ratio is decreased by 2.2 kg/t, the coke nut ratio is decreased by 0.4 kg/t, and the total fuel ratio is decreased by 9.5 kg/t.