Research On The Property Evaluation Of Top Charging Coke And Stamp Charging Coke

Due to the exhaustion of high grade coking coal in our country as well as the high price of coking coal and fat coal introduced from abroad, the traditional coking process is disadvantageous for iron and steel enterprises to cut the cost. The stamp-charging cokemaking technique can use weak caking coal effectively and the index of coke can meet the needs of blast furnace production. However, the effect of stamp charging coke used in the blast furnace is still under debate. Stamp charging coke could vary from the top charging coke.both in the technology process and structure of coal blended, consequently, the index and microstructure are also different from the top charging coke. A kind of top charging coke and a kind of stamp charging coke basis index, microstructure and gasification reaction characteristics were studied in this research to distinguish the difference of two kinds of coke. The main contents and conclusions are summarized as follows:（1） The chemical composition and cold strength index of the above mentioned two kinds of coke are nearly, the reactivity index of the top charging coke is lower than the stamp charging coke, results in the post-reaction strength index of the top charging coke is higher than the stamp charging coke. Coke reaction at 25% mass loss from non-isothermal to isothermal and the matrix reactivity of two kinds of coke were investigated by thermogravimetric analysis in CO₂ atmosphere. The results showed that no significant difference in CSR was observed between Chinese standard method and equivalence solution rate method. The reason that CSR index of the stamp charging coke was lower was due to the excessive solution and had nothing to do with the physical structure of coke included pore structure and matrix strength, the isotropic optical tissue composition of the top charging coke was a bit more led to the matrix reactivity slightly higher.（2） There were evenly large pores inside the top charging coke, the pores shape of which was regular and the distribution was homogeneous, the pore wall appeared much micropores and original pores enlarged after reaction, the pores distribution was homogeneous. There were a large number of micropores and flat pores inside the stamp charging coke, so the specific surface area of stamp charging coke was higher than the top charging coke and brought about the relatively high reactivity index.However, the pores shape was nonuniform and the distribution was nonhomogeneous,in addition, the thickness of pore wall was uneven, more closed pores opened, the flatpores further widened and the apparent porosity became larger than the top charging coke, however, the distribution of pores were still non-uniform after reaction.（3） Coke strength after reaction with 25 percent solution rate under constant temperature CSR₂5（Iso） was applied to evaluate the influence of reaction dynamic behavior on the strength of coke after reaction, and equivalence time method（Chinese standard method） and equivalence solution rate method were compared in this investigation. The results have shown that no significant difference in CSR was observed between Chinese standard method and equivalence solution rate method.Under same solution condition, higher reactivity and temperature led to stronger superficial reaction, and the strength after reaction was higher,except the CSR₂5（Iso）of stamp charging coke is least at 1150℃. The activation energy of gasification of powdery top charging coke and stamp charging coke were 146.5 KJ/mol and 166.66KJ/mol respectively by pattern match method. The more developed pore structure and larger specific surface area made the lump stamp charging coke reactive much easier than the top charging coke under the condition of low temperature, and the higher reactivity of matrix and larger specific surface area made the lump stamp charging coke reactive much easier than the top charging coke under the condition of high temperature.