Determination of Si, Al, Fe and Ti in Bauxite by Inductively Coupled Plasma-Atomic Emission Spectrometry

Bauxite has strong chemical stability, which often contains a small amount of corundum. Therefore, samples are classified to refractory samples by the method of inductive coupled plasma-optical emission spectrometry. The routine 4 acids digestion system works well for non-corundum bearing bauxite, but cannot completely digest the high Al and corundum bearing bauxite and simultaneously determine Si. Four elements of Si, Al, Fe and Ti in bauxite were simultaneously quantified by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) after the samples were digested in a Nickel Crucible with NaOH-Na₂O₂ and acid treated. The melting effect, dosage of Na₂O₂, temperature, elementary spectral lines, coexisting ions, matrix interference and elimination of melting samples are discussed in this paper. The results show that corundum bearing bauxite samples are completely melted with 3.0 g NaOH and 1.0 g Na₂O₂ at 650-700℃ for 10 minutes. The standard solution prepared by national bauxite standard material is good to eliminate the matrix interferences for Si, Al, Fe and Ti measurements. The detection limits are 0.0025%-0.063%, and the precisions (RSD, n=11) are 0.15%-3.05%. The measured values of national standard materials were consistent with the certified values, and the measured values of actual samples were consistent with the values by the other methods. This method has the advantages of completely decomposing the sample, having a short digesting time, is simple for analysis procedure, rapid, accurate, has a wide range for determination content and is especially suitable for high Al or corundum bearing bauxite samples.