Abstract：Through the experiment, the sample decomposition method was established,which used the HCl, HNO3, HClO4 to decompose vanadium slag sample, or used the mixed flux of Na2CO3-H3BO3 to fuse vanadium slag sample and then leached by acid. In nitrate acid medium, 0.3-0.5 g potassium chlorate was added to make Mn2+ form MnO2 precipitate, which was removed by filtration. Then under acidic conditions, vanadium was reduced to vanadium using anhydrous alcohol. Ammonia was added to adjust pH 6-7,so that most vanadium and metal ions such as iron, titanium, aluminum and rare earth metal ions may form precipitation, which may be separated by filtration. After adjusting the test solution to pH 7, a small amount of DDTC was added to separate the residual vanadium and metal ions,then calcium oxide content in the solution was measured by EDTA titrimetric method. A randomly selected vanadium slag sample was fused by mixed flux,and determined by EDTA titrimetric method,which the relative standard deviation(RSD%,n=11) was 3.1%.The determination results of proposed method agreed well with those of industry standard (YB/T 547.3-1995 Methods for chemical analysis of vanadium slag: the flame atomic spectrometric method and the permanganimetric method for the determination of calcium oxide content). CaO in reference materials of vanadium slag were determined,and the results were consistent with the certified values.
