Analysis of iron ores by ICP-AES

Abstract

A method for the analysis of iron ore raw materials (IORM) using inductively coupled plasma atomic- emission spectrometry (ICP-AES) and Concentration Ratio Calibration (CRC) has been developed. However, the general eq. for calibration by concentration ratios used in analysis of metals and alloys was modified with allowance for the IORM characteristics: all the elements, except sulfur, were represented as oxides, iron was represented as FeO and Fe₂O₃, and the total of 100% included ignition losses (LOI). A variant of solving the equation is proposed, which allowed us to relate the relative concentrations of the components (the ratios of the mass fraction of the determined components to the mass fraction of iron oxide) to the ratio of the line intensities of the certain element and iron line measured on a spectrometer. The equation takes into account the content of FeO and LOI, which are determined by standard methods of analysis. A method for acid decomposition of the samples in autoclaves heated in a HotBlock 200 system is proposed: a sample weight of 0.25 g was decomposed in closed vessels at a temperature of 150 – 180°C in the mixture of HCl, HF and HNO₃. The following components were determined in concentrates and pellets: Fe₂O₃, Fe_tot, Al₂O₃, CaO, Cr₂O₃, K₂O, MgO, MnO, Na₂O, P₂O₅, SiO₂, TiO₂, Co, Cu, Mo, Ni, Pb, S, V, Zn. The correctness of the developed method is confirmed by the analysis of SS of iron ore and iron concentrates, as well as by comparison with the results obtained by standardized methods. The proposed technique provides iron determination in iron ore raw materials with an accuracy no worse than that specified in GOST 23581, all other components are determined in a wider range of contents and with a higher accuracy.