Furnace Slagging
Furnace Slagging
During the process of blast furnace ironmaking, slag-forming in blast furnace ironmaking is the solvent that interacts with the gangue in the ore and the ash of coke to dissolve, collect, and melt the substances that do not enter pig iron and gas, so that the liquid slag is formed. In blast furnaces, slag and pig iron are formed at the same time. Consequently, good slag must be made to improve the quality of pig iron and ensure the smooth operation of blast furnace. Liquid blast furnace slag is required to be of well flowing to ensure good separation of slag and iron.
Magnesium Oxide (MgO) is an indispensable additive for blast furnaces. There is an enormous impact of MgO on blast furnace operation concluding burden reducibility, reduction degradation, softening-melting properties, blast furnace gas permeability, slag system development, and desulphurization performance.
It is not suitable to add too much MgO in sinter because problems such as high the fuel ratio of sinter and deteriorative reduction degradation index may appear. When MgO is transferred from sinter to pellets, both the metallurgical properties of sintering and pellet are greatly improved. It is generally acknowledged that the content of MgO in blast furnace slag is 8–10 mass%, which is at a reasonable status.
Compared with the acidic pellets, the cohesive zone of the MgO pellets narrows and moves down in the blast furnace. The increase in softening temperature is conducive to the indirect reduction reaction, which makes the utilization of blast furnace gas more efficient; the reduction of the cohesive zone is beneficial to improve the permeability of the blast furnace. Therefore, the addition of MgO-bearing pellets is beneficial to the operation of the blast furnace, which is embodied in the reduction of the coke ratio and the forward run of the blast furnace.
The deficiency of slag viscosity leads to poor separation of iron from blast furnace slag and directly reduces pig iron yield. The influence of basicity (CaO/SiO2) on slag properties is self-evident, and the optimum basicity of blast furnace slag is between 1.0 and 1.2. MgO has numerous advantages in the blast furnace slag, but it should be added in moderation. The content of MgO in the slag system is not unlimited, especially when there is a large amount of Al2O3 in the slag system, and MgO/Al2O3 ratio is an important indicator. Suitable MgO/Al2O3 ratio significantly optimizes the viscosity of blast furnace slag and improves blast furnace operation.
For the exploration of slag properties, not only its metallurgical properties should be considered, but also the subsequent slag recycling and waste heat conversion should be paid attention to realize energy saving and slag resource utilization in the whole process of iron making. For different applications of slag, the requirements for the slag-making operation are also different.
IMC offers a high quality MgO pellet product – MagPellet for use of Furnace Slagging.
Recommended Products
