Effect and function mechanism of sinter basicity on softening-melting behaviors of mixed burden made from chromium-bearing vanadium-titanium magnetite

The effect of sinter basicity on softening-melting behaviors of mixed burden made from chromium-bearing vanadium-titanium magnetite (Cr-V-Ti magnetite) was investigated and the function mechanism was simultaneously analyzed. The results show that with increasing sinter basicity from 1.71 to 2.36, the softening interval tends to increase from 149.3 °C to 181.7 °C while the melting interval tends to decrease from 178.0 °C to 136.7 °C. The location of cohesive zone moves downwards firstly and then ascends slightly, but the cohesive zone becomes thinner. The softening-melting characteristic value becomes small, which indicates that the permeability of burden column is improved. The dripping ratio of mixed burden tends to increase firstly and then decrease, which comes to the highest value of 74.50% when the sinter basicity is 2.13. The content and the recovery of V and Cr in dripping iron are all increased. The generation amount of components with high melting point in slag becomes little with the increase of sinter basicity, which could improve the permeability of mixed burden. Taking softening-melting behaviors of mixed burden and recovery of valuable elements into account, the proper sinter basicity is no less than 2.13 for smelting mixed burden made from Cr-V-Ti magnetite in blast furnace.