Thermodynamics of antimony,arsenic, and tin in CaO—CaF2 melts

In view of the importance of tramp element contamination of steel products through a large volume of scrap consumption in the near future, the thermodynamic behaviour of Sb, As, Sn and Cu in CaO—CaF₂ melts under reducing conditions was studied by examining the dependences of distribution of each element between Cu, Ag or Sn alloys and CaO—CaF₂ melts on the CaO activity, oxygen partial pressure and temperature around 1 500°C. As a result, the reaction products on treatment by Ca compounds were demonstrated to be Ca₃Sb₂, Ca₃As₂, Ca₂Sn and CaCu. Experimentally obtained distributions were extrapolated to lower oxygen partial pressures less than 10^?18 atm to estimate the feasibility of removing those tramp elements from molten iron. It is thermodynamically indicated that if the prevailing oxygen partial pressure of the environment is below 10^?23 atm, these impurities, except Cu, would be substantially removed from molten steel.