EVAPORATION RATE OF CALCIUM FROM LIQUID CA-CAF2 SYSTEM IN THE REDUCING REFINING PROCESSES

The quantitative description of the evaporation rate of calcium from l iquid Ca-CaF2 system has been carried out adopting the Chapman - Ensko g kinetic theory of gases. A diffusion coefficient of calcium in argon , DCa-Ar was computed us. temperature and gas pressure. The molar or m ass flux of calcium vapour was taken as a measure of evaporation inten sity of Ca from liquid Ca-CaF2 system. Calcium-calcium fluoride melt w as used to remove phosphorus from the 18 wt. %Cr8 wt. %Ni - steel unde r strong reducing conditions. Investigations were made in a laboratory resistance furnace under excess argon pressure up to 1.0 MPa and usin g CaO - crucibles of the capacity of about 0.15 kg melt. The influence of argon pressure on the dephosphorization efficienty was established . Moreover, the effect of total oxygen content at the moment of Ca-CaF 2 flux addition on the change in the final phosphorus concentration in 18% Cr8%Ni - steel at 1773 K has been shown.