The Development And Application Of Combustion-supporting Agent On Pulverized Coal Injection For BF

It is an important measure to increase the pulverized coal injection (PCI) for reducing the coke ratio and production cost of iron-making in the blast furnace (BF) production. However, as the greatly increasing of the coal injection ratio, the measure appears many problems such as the unburned coal powder increasing before the tuyere, permeability deterioration in a certain condition of burden, etc. By taking measures to enhance combustion of pulverized coal (PC), the coal powder can burn faster in the tuyere. By adding the appropriate amount of combustion-supporting agent on pulverized coal injection for BF, and combining with measures such as blast furnace operation, the ignition temperature of coal powder to furnace can be decreased, the combustion efficiency be improved, the coke ratio of BF and production cost of iron-making be decreased accordingly.In practice of increasing the PCI of YiCheng steel company, along with the increase of the coal injection ratio, many problems were found, such as decline in burning rate of pulverized coal, increase in the carbon content of blast furnace Gas Ash. According to actual condition of iron manufacture in YiCheng steel company, by using the methods of theoretical analysis and experimental research, the practical production to seek for the suitable combustion-supporting agent on PCI for BF in YiCheng steel company was studied; meanwhile, some suggestions were given to the reasonable industrial production for BF in YiCheng steel company.Through the two stages of the development in laboratory and the industrial production of combustion-supporting agent on PCI for BF, conclusions are as follows:(1)The laboratory result showed that the combustion properties of PC can be improved obviously by adding combustion-supporting agent, and the addition of the second formula has the best effect. By the addition of the second formula in 0.4%, the ignition temperature of PC decreased 24℃, the burning completely temperature decreased 51.5℃, and the relative completed burning time reduces 15.4%. Meanwhile, the calculation of exothermal area on DSC curve method was used to compare and analyse the influence when the combustion catalyst was injected into the PC, the results showed that the addition in 0.4% has the best effect, and the combustion properties has a downward trend over 0.4%.(2) By increasing the proportion of PC at -200 mesh and improving oxygen-enriched rate, the combustion properties of PC can be improved more favorable, and the combustion-supporting effect can be given more fully play. The laboratory result showed that a better combustion efficiency has been achieved in the condition of 70% pulverized coal -200, 3% oxygen-enriched rate and 0.4% combustion-supporting agents blending rate.(3) It was found that in the industrial production of combustion-supporting agent on PCI for BF in YiCheng steel company , the coal injection rate and the coal injection effect has a great improving by adding with the combustion-supporting agents. Meanwhile, the ignition temperature of PC was decreased; the combustion rate and the combustion efficiency were improved. Though the expected goal of the experiment has be achieved basically, it is also needed more industrial production practice for master the coal injection influence of blast furnace operation and the grade of raw mineral. And the next goal is designing a suitable equipment and process of combustion-supporting agent on PCI for BF.