PURPOSE: To estimate strength of product coke after CO2 reaction simply in high accuracy, by applying an index of rank of coalification obtained from analyzed value of raw material coal and contents of CaO, MgO and Fe2O3 to a specific equation.

CONSTITUTION: Content of iron oxide(calculated as Fe2O3) in coke is obtained based on component analyzed value of raw material coal. When the value is ≤11mg/coke-g, the aimed strength after the reaction is estimated by using the equation I [CSR is strength of coke after CO2 reaction; α, β, γ are coefficients determined by carbonization conditions of coal; x is index of rank of coalification; CaO is amount of CaO(mg/coke-g) in coke; MgO is amount MgO(mg/coke-g) in coke], and when the value is >11mg/coke-g, it is obtained by using the equation II [η is coefficient determined by carbonization condition of coal; Fe2O3 is amount of iron oxide(mg/coke-g) in coke].