Study On Approaches To Inhibit Carbon Solution Reaction For Improving Thermal Properties Of Coke

This paper is focused on the advanced study of solution loss reaction of metallurgical coke. In order to find a new method instead of tradition method of blending high grade coking coal to improve coke thermal properties, it is important to understand the factors that influence thermal properties of coke. The correlation between these factors and coke thermal properties was found, then coke thermal properties control model was established. Also, the methods of improving coke thermal properties by negative catalyst addition and chemical vapor deposition (CVD) were examined. Finally, the mechanism of coke thermal properties improvement deduced from the results of these two approaches was investigated.1.Summarizing the foreign and domestic coke quality prediction methods, using improved GHMP mathematics method, a coke thermal properties control model is established on the basis of 19 coals and 64 coal blends carbonized in a simulated coke oven (SCO). The model is an effective method to get high-grade coke by coal blending. According to the research about the model, existed mineral catalysis effect is one of the key factors affecting coke quality besides the coal rank and the plastic properties of coal. The further study is finding new approaches aimed to improve coke thermal properties of existing metallurgical cokes and upgrade low-grade by enhancing its resistance to oxidation with CC>2.2.Exploiting study on improving coke thermal properties by negative catalyst addition was conducted, the catalytic effects of species and chemical states of negative catalyst on solution loss reaction of coke are investigated in detail by adding H3BO3, 6203 and B pure substance into coal before carbonization or absorbing or impregnating of boron compound on coke surface. It was found coke thermal properties does not improved after H3BO3, B2O3 was added into coals due to coals caking properties destroyed while Boron has strong negative catalytic effect to improve coke thermal properties. The lower coke thermal properties higher negative catalytic effect. Evident improvement of the thermal properties of coke product was observed when H3BO3 solution was spraying on the coke surface or coke was impregnated in H3BO3 solution. For coke with CSR 57.5 %, CRI 29.2 %, every 0.01 % Boron was spraying on coke surface, CRI decreased 3 and CSR increased 4. This allows interpretation of the negative catalytic effect of H3BO3 on coke solution reaction.The effect of negative catalyst on the coke thermal properties was investigated by adding different amount of Boron into the coals. The results show that high negative catalyst content could improve the medium size optical texture growth in the resultant coke, total of coarse mosaics, incomplete fibrous and fibrous coke optical texture increased and CRI decreased accordingly with increasing boron addition.Special attention was also paid to the coke microstructure change measured by some modern instrument analysis technology. The results of X-ray diffraction (XRD) show that increasing the catalyst amount led to increase dooi, decrease Lc, and enlarge La. Compared with the XPS spectra analysis results of negative catalyst added coke before and after COa reaction, The mechanism of negative catalyst could be elucidated as follows: Boron may catch the oxygen in the coals during pyrolytic plastic stage. It favours the lamellae growth and the optical texture development. The catalyst atoms occupy the active sites on the carbon layers and result in a decrease in the total number of accessible active surface sites for CO2 reaction. Therefore CRI of cokes decreases.S.Exploititation study on improving coke thermal properties by chemical vapor deposition was also conducted. Methane was used as source and metallurgic coke was used as deposition matrix. The tests showed that chemical vapor deposition of pyrocarbon can improve thermal properties of coke dramatically, and deposited pyrocarbon strongly exhibits resistance to the oxidation of CC>2. In addition, optimum condition for each constraint was determi...