Study On Improvement Of Thermal Property Of Coke

With the scaling up of the blast furnace, the development of oxygen enriched blast and pulverized coal injection,the coke rate in blast furnace ironmaking progress reduces gradually and the skeleton function of coke in blast furnace seems more and more important. Ironmaking workers pay more attention to the thermal properties of metallurgical coke. The cokemaking workers should leave no stone unturned for improving the thermal properties of coke, taking the technological measures.This paper studies the influence of the quality of the coal blends, the pre-treatment of coal and post-treatment of coke on the thermal properties of coke, based on the entire process of coke production. The thermal properties of coke are the thermophysical properties of coke, thermochemical properties of coke and thermal compressive strength of coke, when the coke was reheated. Coke loss reaction with CO₂ is one of the most important factors which lead to coke degradation in blast furnace. Therefore this paper is focused on the coke reaction index (CRI) with CO₂ and coke strength after reaction(CSR). Then if we want to improve the thermal properties of coke, we must decrease CRI and increase CSR.Under the experimental conditions,13 kinds of single coal were used to do the coal blend coking test. The way of the coking test is the regular coking. Using multivariate linear regression method, the relationship between the thermal properties of coke and the quality of coal blends was found.CRI=6.6486+0.4986Vdaf-0.1667G+7.7725MCI R²=0.8996CSR=86.4758-1.1970Vdaf+0.2307G-6.5053MCI R²=0.9321 Therefore, if we want to improve the thermal properties of coke, we must reduce the volatile content Vdaf of coal blends and increase the caking index G of the coal blends. So we should increase the ratio of coking coal in the coal blends and control the mineral catalytic index MCI of the coal blends in the coke production progress.The coal blends from the domestic representative coke oven were used to cokemake. The domestic coke oven were the top-charged coke oven whose height of the chamber were respectively 4.3 m, 6.0 m, 7.0 m, 7.63 m, the stamp-charged coke oven whose height of the chamber were respectively 4.3 m,6.0 m and the 6.0 m briquetted coal blending coke oven. The ways of the coking test were regular coking, stamping coking, briquetted coal blending coking, the coal moisture control coking and adding blinder coking. The results reveal that the pre-treatment of coal, such as stamping, briquetted coal blending, coal moisture control and adding blinder, can improve the thermal properties of coke effectively, at the same time the performance is significant when the quality of coal blends and the thermal properties of coke are poor. Compared with that of regular coke, the CRI of the stamping coke, the briquetted coal blending coke , the coal moisture control coke and the adding blinder coke decrease 3.57%,4.09%,3.27%,3.28%respectively;the CSR of the stamping coke, the briquetted coal blending coke , the coal moisture control coke and the adding blinder coke increase 8.39%,8.20%,7.61%,5.13% respectively。The industrial coke was tested, which produced by the domestic large-scale coke oven, used by the large-scale blast furnace and quenched by the way of CDQ and CWQ. The results reveal that on average, dry coke quenching can decrease CRI 2.69% and increase CSR 6.15%. When one kind of CWQ coke was treated by the solution of boronate passivation, the thermal properties of coke improve significantly. On average, the CRI decrease 9.71% and the CSR increase 11.00%, when the above industry CWQ coke were treated by 2% solution of boric acid.