The Application Research Of Pulverized Coal With Additives Used For Blast Furnace

The pulverized coal injection (PCI) technology is widely adopted in modern blast furnace iron-making, and it has attracted to many countries and regions. With the development of PCI technology and consummated, increasing the ratio of PCI and decreasing coke ratio will be the aims for researching PCI technology. The research of this paper is based on it.In this paper, the effect of additives added to PCI of one BF on coal combustion rate was tested in laboratory. Then the optimal mixture ratio was obtained through the orthogonal combustion experiment analysis. After the industrial trial, it was analyzed that additives added to the PCI made the coke ratio get down and coal ratio increase, and it indicated that the additives in PCI was good for combustion of PCI in blast furnace. Therefore, some conclusions were got in this paper as follows:(1) The results of TG/DSC analysis indicates that CaCO₃, MnO₂ and CeO₂ can be chosen as the suitable compositions of additive with PCI. The result of orthogonal combustion experiment shows that the optimal mixture ratio is A₃B₄D₄, viz the mass ratio between CaCO₃, MnO₂ and CeO₂ is 1.5:2.5:2.5. On the basis of the comparison performance with cost, the application mixture ratio is A4B4D1 under the experiment condition, viz the mass ratio was w(CaCO₃):w(MnO₂):w(CeO₂)=2.5:2.5:0.5.(2) In orthogonal combustion experiment, the combustion rate of PCI with additives was improved about by 20%. Meanwhile, the range analysis of the influencing factor to combustion rate indicates that the primary and secondary order is CaCO₃, CeO₂ and MnO₂. The result of variance analysis indicates that the changement of CaCO₃ level has a remarkable effect to the test results, while CeO₂ and MnO₂ have a weak effect. The combustion rate of PCI with the optimal mixture ratio of A₃B₄D₄ was 53.15%.(3) The result of correcting computation shows that the coke ratio decreases by 6.64kg/t and the PCI ratio increases by 2.85kg/t in initial industrial trial. The replacement ratio of PCI increases 0.0232 in test period.(4) Expanding industrial test was divided to two stages. For the first stage, the coke rate was cut down by 12.187kg/t and the PCI rate was improved by 5.04kg/t in correcting computation, and the replacement ratio of PCI increased by 0.0533. In the second stage, the coke ratio decreased by 3.158kg/t and the PCI ratio increased by 1.78kg/t, but replacement ratio of PCI only increased by 0.0111. From the view of whole industrial test, the replacement ratio of PCI increased by 0.0322 in the expanding industrial test. Meanwhile, the carbon residue in BF ash and gas mud got down obviously and the additives had no obvious effect on basicity of BF slag. The conclusions above shows that the additives added to PCI not only are good for combustion of coal in blast furnace, but also have important significance for decreasing coke ratio and increasing PCI ratio.