Experimental Study On Sintering Of Vanadium-Titanium Magnetite With High Magnesium Content

There exists extremely abundant Vanadium-Titanium magnetite resource in Panxi, which has huge value in comprehensive utilization. This magnetite is rich in Ti, V and MgO. However, smelting schreyerite is a worldwide problem. Even if magnesium ore is not added in the process of sintering, MgO content can reach 2.0%. If steel companies want to use this magnetite in large, it is essential to have earlier research in laboratory to evaluate the effects on production.Under the condition of existing raw materials, the experiment measures the sintering properties of this magnetite, and studies the effects on sintering index as well as metallurgical properties by changing the proportion of MgO content in the alkalinity of 1.8,1.95,2.1 and 2.25. The results have been shown as follows:1) The assimilability of Australian mine, Pingchuang mine, Liugu mine, Baima mine become bad successively. The assimilability temperatures are 1164℃,1297℃,1312℃,1358 "C respectively. Australian mine has the best fluidity; Liugu mine takes the second place; Pingchuan mine can hardly flow; Baima mine is the worst. Bonding strength of Liugu mine can reach 2600-2700KN, and the other three are only 1000-1800KN. Therefore, when the proportion of Baima mine is raised, it is suggested to raise the proportion of Liugu mine and Australian mine to improve the quality of sinter.2) When the content of MgO is constant, with the alkalinity of sinter rising from 1.8 to 2.25, the vertical sintering speed, drum strength and utilization factor all increase. The reason is that low-melting liquid phase easily forms, and both fluidity of liquid and binging phase increase, when the alkalinity rises. Therefore, the vertical sintering speed and drum strength increase.3) When the alkalinity of sinter is constant, with the content of MgO rising from 2.8% to 3.3%:The vertical sintering speed decreases, while drum strength rises gradually and utilization factor and yield do not change much. According to analysis, it is because of the increase of MgO content that the content of FeO and the liquid phase increase, resulted in more binding phase which raises the drum strength. On the other hand, high-melting minerals, such as perovskite and magniferous mineral, also increase, leading to low-fluidity liquid phase, broading combustion zone and bad air permeability. These factors result in the decrease of vertical sintering speed.The RDI.3.15 of sinter decreases and the pulverization achieves better improvement. According to analysis, this is mainly because the increase of MgO leads to uniform distribution of magnesium in sinter, making vanadium magnetite stable and not easily oxidized to hematite; the decrease of hematite reduces the crystal transfer, so the pulverization rate descends.The reduction index (RT) does not change much, almost between 80% and 86%. But on the whole, the higher proportion of ore blending leads to small decline of reducibility. The main reason is that with the increase of MgO (raise the proportion of Baima mine), the grade of sinter has a little decline and the content of high-melting minerals in sinter, such as perovskite, also increase, which decreases the reducibility.4) This research has investigated softening-melting properties of sinter with better overall indicators (R=1.8 W(MgO);=3.05%,3.3%、R=1.95 W(Mgo)=3.3%) in high temperature. With the increase of MgO, the starting softening temperature of sinter increases, and cohesive zone narrows and moves down, which contribute to the strengthening smelting of blast furnace. With the rise of alkalinity, the starting softening temperature rises, and softening zone and softening-melting zone broaden. Furthermore, high-melting minerals in the slag of sinter rise, leading to hard melting and dropping, causing the deteriorative air permeability of stock column.According to the experiment, increasing the proportion of Baima mine appropriately can improve the metallurgical and softening-melting properties, On the other hand, increasing alkalinity contributes to the improvement of sinter cold strength and reduction degradation in low temperature, but both its reduction and grade become lower. Under the current condition, the sinter can obtain better sintering production quota when its alkalinity is 1.8 and content of MgO is 3.3%, and the comprehensive metallurgical properties of the sinter are best.