Determination of scandium and titanium in molten salt slag by inductively coupled plasma atomic emission spectrometry
CHENG Yong, LIU Liwei, YUAN Jinhong, HE Qiping, WEI Fang
Pangang Group Research Institute Co., Ltd., State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Sichuan Panyan Testing Technology, Co., Ltd., Panzhihua 617000, China
Abstract：The content of scandium in vanadium-titanium magnetite is relatively low and cannot be effectively utilized. During the extraction of titanium by molten salt chlorination method, scandium was enriched in molten salt slag. In order to recover the valuable scandium and titanium resources in molten salt slag, the determination method of scandium (0.001%-0.5%) and titanium (0.25%-5.0%) in molten salt slag by inductively coupled plasma atomic emission spectrometry (ICP-AES) was established. The molten salt slag sample was dissolved with HF and H2SO4. The formula, dosage and reaction conditions were optimized in experiments to ensure the rapid and complete dissolution of sample. The matrix components such as SiO2 and CaO with high contents were removed by SiF4 volatilization release and CaSO4 precipitation separation. The problem of easy hydrolysis for Ti4+ in low-acidity medium was solved by forming complex ion of TiOSO4. The acidity of sample solution and the contents of coexisting components could be reduced, thus effectively reducing the influence of matrix effect. The influence of interference factors such as spectral interference of coexisting components, continuous background superposition and matrix effect was investigated. The detection conditions were optimized, including the analytical lines for testing elements, the integration and background correction region as well as working parameters of spectrometer. Moreover, the influence of coexisting matrix components was eliminated by synchronous background correction method. The linear range of scandium in calibration curve was 0.001%-0.5% and the linear correlation coefficient was 0.999 6. The linear range of titanium in calibration curve was 0.25%-5.0% and the linear correlation coefficient was 0.999 2. The limit of detection for scandium and titanium was 0.000 01% and 0.000 38%, respectively. When the content level of element was 0.01%-0.1% (mass fraction), the relative standard deviation (RSD, n=8) of determination results was less than 3%. When the content level was 1.0%-5.0% (mass fraction), the RSD (n=8) was less than 1%. The recoveries were between 92% and 109%. Four molten salt slag samples in titanium extraction by chlorination were determined according to the experimental method. The found results were consistent with those obtained by GB/T 17417.2-2010 (Determination of scandium in rare earth ore by ICP-AES) and GB/T 6730.23-2006 (Determination of titanium in iron ore by ammonium ferric sulfate titration method).
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