Thermodynamic Analysis and Experimental Study on Reaction of CO2 Gas with Hot Metal

The reaction of CO2 gas with hot metal was investigated based on the thermodynamic analysis and experimental results. It shows that both silicon and carbon in hot metal can be oxidized by CO2 gas in the temperature range of 1 300-1 500 degrees C. When using graphite crucible, temperature has little influence on final mass percent of carbon w[c] because of the carburization effect. Decarburization degree rises significantly with increasing gas injection rate and w[c] can be reduced to 3.2% at most when using MgO crucible. Lower temperature or higher gas injection rate is propitious to promote desilication reaction, but only 5% - 10% of desilication ratio could be obtained in 20 min. The final mass percent of silicon w[s(1)] when using MgO crucible is lower than that when using graphite crucible. Experimental results also demonstrate that CO2 injection has no effect on the concentration of manganese, sulfur and phosphorus in hot metal. In view of the weak oxidation ability and temperature drop of hot metal, CO2 gas is suggested to be used as carrier gas in desilication process rather than oxidizing agent.