The germanium concentration determination in lignite of Lower Angara region

Semiconductor Germanium production in Russia contributes to development of the aerospace electronics. Germanium used for solar cells, as it provides higher conversion efficiency than Silicon. In particular, it is determined that Ge can be used as a substrate material for A III B V based solar cells type GaInP/GaInAs/Ge, and one of the leading results of conversion efficiency is about 39 %. The source of its own raw materials is the strategic issue for Germanium production. Currently, the lignites occurring in Lower Angara in basin of Yenisei River middle course are considered as the promising Germanium raw materials. The measurement procedure of Germanium concentration in thelignite has been developed, which includesthe following steps:ashing of the lignite, ash samples decomposition in a mixture of the concentrated nitric and hydrofluoric acid (1:2) and determination of the Germanium concentration in the solution by Inductively coupled plasma atomic emission spectroscopy (ICP-AES) using spectrometer iCAP 6300 Duo (Thermo Scientific). The proposed measurement procedure allows carrying out qualitative and quantitative elemental analysis of lignite and other minerals - coal, anthracite, carbonaceous mudstone and siltstone. Metrological characteristics of the measurement procedure have been identified. Indicators of precision when the Germanium concentration value of 150 to 300 g / t are: the standard deviation of repeatability  3.0 g / t; the standard deviation of precision  5.4 g / t. The relative error is less than 4 %. It was found that the average germanium content in the lignite is 0.02 wt. % or 200 g/t. Carbon (68 wt. %) and oxygen (27 wt. %) are dominated in the composition of lignite. Silicon (1.0), aluminum (0.5) and iron (0.4 wt. %) predominate among the metallic elements.