抄録
The phosphorus and manganese distribution between Na2O-SiO2 melts and carbon-saturated iron and the solubility of nitrogen in these melts were measured at hot metal temperatures by chemical equilibration. Phosphorus distribution increases and manganese distribution decreases with increasing Na2O content in the slag. The Na2O-SiO2-PO2.5 system was found to have very large phosphate capacities ranging from 1026.7 to 1029 at 1200°C. The activity coefficient of FeO in the Na2O-SiO2 system ranged from 0.2 to 1.0. The partial pressure of oxygen at the slag-metal interface was estimated to be 10-17.2 atm at 1200°C from the equilibration test of soda-slag used in the commercial hot metal treatment. Temperature dependences of phosphorus and manganese distribution are expressed as follows:
log(%P)/[%P]=20200/T-10.9, log(%Mn)/[%Mn]=6070/T-2.74.
Nitrogen was found to dissolve into Na2O-SiO2 melts as CN- from the dependence of solubility on the nitrogen partial pressure when graphite coexists, as expressed by the following reaction:
1/2N2+3/2C+1/2O2-=CN-+1/2CO.
The solubility of nitrogen increased with raising temperature and the Na2O content in melts.
