Dissolution losses of metallurgical cokes in CO₂-H₂O mixtures

ABSTRACT

Influences of the gas mixtures of carbon dioxide and water vapor with different water vapor content on the thermal properties of cokes were studied at 1,373 k using a high-temperature gas-solid reaction device to clarify the action mechanism of water vapor in the dissolution loss of metallurgical coke in the blast furnace. Furthermore, the reaction depth and the microstructure of coke samples with different water vapor content were studied. The results showed that the reactivity of cokes was significantly improved by steam, and coke strength after the reaction was significantly weakened. Cokes with strong reactivity were more affected by water vapor. When H₂O content was 0 and 11.1%, the reactivity indices of cokes with strong reactivity were 2.03 and 1.67 times that of cokes with poor reactivity, respectively. The influence of H₂O on the strength ratio of two kinds of cokes after the reaction was ignored when H₂O content exceeded 50.1%. The analysis of coke reaction depth after the reaction under different H2O content showed that the solution loss reaction between H2O and coke is mainly concentrated on the coke surface, while CO2 can penetrate into the coke to react. In addition, by comparing two kinds of coke with different reactivity, it is found that coke with higher reactivity is more sensitive to water vapor. The micromorphologies of cokes after reactions showed that water vapor significantly affected the pore and pore sizes of cokes. When water vapor content increased, the pore sizes of cokes increased, with the thinner pore wall and the increased number of new pores.

KEYWORDS:

• Metallurgical cokes
• dissolution losses
• CO₂-H₂O
• reaction depth
• micromorphology

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Minmetals Science and Technology Special Program Green Low Carbon Hydrogen Metallurgy Technology and Key Equipment, China [No. WKZB2019BJB401487]; Liaoning Coal Chemical Industry Professional Technology Innovation Center, China [No. USTL201905]; Leading Talents of Science and Technology Innovation in Xingliao Talent Plan, China [No. XLYC2002063].