INFLUENCE OF PELLETS CONTENT IN FURNACE BURDEN ON BLAST-FURNACE OPERATION AND PULVERIZED COAL CONSUMPTION

At the blast furnace of the Dneprovsky Iron&Steel Works with the volume of 1,500 m3, it was studied the effect of pellets content in the charge on the consumption of pulverized coal. During the observation period of 158 days, it was found that an increase in the content of low-fluxed pellets in the total mass of iron-ore part of the charge up to 35% was accompanied by a decrease in FeO content in the charge by an average of 4%. In the specific charge conditions, the increase in content of pellets in the charge up to 20% resulted in a significant reduction in slag output - on average of 15 kg / tonne of pig-iron per additional 10% of pellets in charge. Consideration of the effect of pellets content in charge along with the concentration of oxygen in blast blowing showed that the increase in pellets content with all concentrations of oxygen was accompanied by an increase in the cost of pulverized coal. Thus, it was shown that the introduction into the iron-ore part of the blast furnace charge of low-fluxed pellets in the limits that increase the enrichment of the charge with iron and reduce the slag output, contributes to the increase in the cost of pulverized coal. The estimation of the influence of pellets on the gas distribution has emphasized the feasibility of using measures to improve the gas permeability of the central part of the furnace. In particular, the index ΔР / Qd, kPa / m3 / min, increased from 0.040 when working on an agglomerate to 0.043 when working with a 20 % pellets content in the charge. The dependence between the pellets content and the gas permeability index was moderate (R = 0.368). The dependence analysis of the distribution of the gas flow from the pellets content showed the undeniable influence of pellets on gas parameters whixh are under study. The temperature of the furnace mouth with increasing pellets consumption was reduced (R = 0.707) due to the influence on the process of two factors - the loading of cold pellets, along with hot agglomerate and the pellets themselves. The nature of the change in the ratio of the temperature of the periphery to the temperature of the furnace mouth showed an increase in the degree of peripherality of the gas stream with an increase in pellets content in charge (R = 0,458).