The viscosity of fluxes was measured by rotational viscometer method with RTW-08 measuring device for properties of matter of molten mass. The test results showed that the fluxing effect of B₂O₃ was equivalent to that of CaF₂ in based slag 46CaO- 10BaO- 11.2SiO₂- 11.6Al₂O₃;and in based slag CaO-SiO₂- 10BaO- 11.6Al₂O₃- 10CaF

2

with basicity(CaO +BaO)/(SiO₂+B₂O₃)being 2.5 or 2.8

the high temperature fluxing property of refining slag replaced 1/4 SiO₂ with  B₂O₃ was stable

of which the viscosity value decreased to 0.3~0.5 Pa.s

and with basicity 2.8 refning slag containing 20.6SiO₂ the desulphurization rate of molten stee

l was 85%(S content decreased from 0.008% to 0.0016%)

while with slag  containing  10.3SiO₂- 10.3B₂O₃  the  desulphurization rate was  91.3%(S  content  decreased  from  0.008%  to 0.0007%)