Determination of Hf, Ti and Zr in Zirconium-Titanium Placer by Inductively Coupled Plasma-Atomic Emission Spectrometry

Zirconium titanium placer is an ore which is extremely difficult to be digested. It is almost insoluble in all kind of acid except HF. Moreover, Hf, Ti and Zr in the ore tends to hydrolyze to form insoluble partial hafnium acid, metatitanic acid and zirconium hydroxide which increases the difficulty for their qualitative determination. The traditional chemical method can only yield total amounts of Zr and Hf and involve a complex time-consuming chemical procedure. After comparing four different methods to melt the sample, it was found that extracting salt with HNO₃-EDTA and melting the sample with Na₂O₂ at 700℃ was a simple, highly efficient and practical method for sample digestion. Based on this melting method, an Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) method was set up for Hf, Ti and Zr detection in zirconium titanium placer. Re was used as an internal standard and high frequency power was applied to eliminate the matrix effect. The RSD (n=11) was less than 1.3% and the detection limits for Hf, Ti and Zr were 0.97, 0.86 and 0.33 μg/g, respectively. The results were much more precise and accurate than the traditional chemical method and X-ray Fluorescence Spectrometry. The method of melting the sample in a corundum crucible increased the number of samples and reduced the cost, which is beneficial for the fast determination of insoluble Zr-Ti placer samples.