Determination of Silicon Dioxide in Chrome Ores by Inductively Coupled Plasma-Atomic Emission Spectrometry

Chrome ore samples were digested with Na₂O₂. After the whole process of high temperature melting extracted with hot water-hydrochloric acid, the SiO₂ in sample solutions was directly determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), adding Au as an internal standard element. The matrix interference is discussed in this paper. The results show that the recoveries of SiO₂ are lower than 92.5% when the content of Na is higher than 300 mg/L. The matrix interference effect and the instrument fluctuation have been overcome by Au internal calibration with improved precision and accuracy of the analysis. The determination limit of SiO₂ was 0.0075 mg/L and the determination content range was of 0.025%-10.0%. The results are in agreement with the certified values of the reference materials and the precision of the method is less than 2% (RSD, n=9). Compared with conventional chemical analysis, the measured values of SiO₂ are in agreement with the certified values. However, the cumbersome procedure, time consuming, heavy workload of conventional chemical analysis methods can be overcome as the work efficiency is improved with this method. It can also be used for the simultaneous determination of Al, Fe, Ca, Mg and P in chrome ore samples.