No abstract

Alkali metal circulation enrichment occurs in blast furnaces, which is harmful to the blast furnace. The amount of enrichment helps to quantify the effect of alkali metals on blast furnace production, but it is not possible to directly measure the actual alkali metal enrichment in blast furnaces for technical reasons. On the basis of a thermodynamic model, FactSage was used to calculate the effects of alkali loading, slag basicity, MgO content in the slag and Al 2 O 3 content in the slag on the alkali metal enrichment in the blast furnace. Quantitative relationships among various factors and the enrichment were obtained, and the degree of influence of various factors on the amount of enrichment was determined. The basicity B 2 of the slag was the key factor for enrichment. With an increase in the slag basicity of 0.1, the enrichment of K and Na increased by 5.3 and 1.6 kg/tHM, respectively.

Ferro-coke, as a new burden of blast furnace (BF), can not only greatly reduce the energy consumption and CO2 emission, but also promote the resource utilization by using the low-quality iron ore and low-grade coal. However, the strength of ferro-coke decreased with the increasing amount of iron ore powder. In order to maintain the strength of ferro-coke while increasing the amount of iron ore powder, it is necessary to add binder during the coking process to enhance the strength of ferro-coke. In this paper, phenolic resin, silicon metal powder, corn starch, and coal tar pitch were used as binder for the fabrication of ferro-coke. I-type drum machine (I 600), scanning electron microscope (SEM), and X-ray diffraction (XRD) were applied to test the crushing strength, morphology, and microcrystalline structure of the ferro-coke. The results showed that the increasing amount of iron ore powder resulted in lower crushing strength, higher porosity, and the worse macroscopic morphology of ferro-coke. When the amount of iron ore powder reached 40%, obvious cracks appeared on the surface of ferro-coke. When the amount of iron ore was 30%, the crushing strength of ferro-coke dropped to 18.15%. Among the four binders, coal tar pitch could significantly enhance the cold crushing strength of ferro-coke through decreasing the porosity of ferro-coke and improving the bonding effect between carbon matrix particles. In the case of the 10% coal tar pitch addition, the cold crushing strength of ferro-coke was increased from 18.15% to 76.41%; meanwhile, its hot compression strength during gasification improved by 100N.

Highly reactive ferro-coke has been widely studied due to its contribution to the energy saving and emission reduction in blast furnace ironmaking. To optimize the coking process of ferro-coke and improve its metallurgical properties, it is necessary to clarify the influence of initial iron ore on the strength, micro-morphology and CO 2 gasification reaction behavior of formed ferro-coke. The effects of initial iron ore particle size (0.50-1.00, 0.25-0.50 and 0.074-0.125 mm) on the CO 2 gasification reaction of ferro-coke were analyzed using thermo-analysis technique. In addition, the effects of initial iron ore particle size on the strength and morphology of ferro-coke were investigated by drum test, digital microscopy and scanning electron microscopy. The results show that iron reduced from iron ore has a great promotion effect on the CO 2 gasification reaction of ferrocoke. The smaller the particle size of initial iron ore, the more intense the gasification reaction, and the lower the starting temperature for gasification reaction of ferro-coke. The results of kinetic calculation show that the apparent activation energy of ferro-coke decreases with the decreasing particle size of blended iron ore. The particle size of initial iron ore has a great impact on the strength of ferro-coke. The ferro-coke prepared by 0.25-0.50 mm iron ore presents the best strength in this experiment.