A Single Step Acid Assisted Microwave Digestion Method for the Complete Dissolution of Bauxite and Quantitation of its Composition (Al2O3, Fe2O3, SiO2, TiO2, Cr2O3, MgO, MnO and V2O5) by ICP‐AES

Abstract

An acid assisted microwave‐based method for the complete dissolution of bauxite using mixture of H2SO4, H3PO4 and HF acids in a single step was developed for the determination of various analytes (Al2O3, Fe2O3, SiO2, TiO2, Cr2O3, MgO, MnO and V2O5) using ICP‐AES. The method was validated with respect to ruggedness, linearity, trueness, precision, limit of detection (LOD), limit of quantification (LOQ), working range and measurement uncertainties by analysing a bauxite reference material (Alcan BXT‐12) and four certified reference materials (IPT‐131, BXBA‐4, NIST SRM 600, NIST SRM 697). The expanded uncertainties obtained for Al2O3 (40.0%), Fe2O3 (17.0%), SiO2 (20.3%), TiO2 (1.31%), Cr2O3 (0.024%), MgO (0.05), MnO (0.013), and V2O5 (0.60%), were 0.80, 0.40, 0.50, 0.033, 0.0008, 0.002, 0.0007 and 0.002 respectively, which are fit for the intended use to characterise bauxite. The developed method was also evaluated through participation in an interlaboratory comparison exercise organised by the Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARDDC), Nagpur, India, using bauxite sample (BXT‐JNA), with satisfactory z‐scores achieved.