MODES OF OCCURRENCE OF GERMANIUM AND TUNGSTEN IN THE SPETSUGLI GERMANIUM ORE FIELD (RUSSIAN FAR EAST)

Abstract

The relevance of the research is conditioned by the need of the assessment of the modes of occurrence of germanium and other secondary trace elements in rare-metal coal deposits. The main objective is to study the modes of occurrence of germanium and tungsten in metal-bearing coals of the Spetsugli deposit (Russian Far East). Objects: coal and coal siltstones of the Ge-coal deposit. Methods: correlation analysis, phase composition study of the brown coal, mass spectrometry with inductively coupled plasma, instrumental neutron activation analysis, scanning electron microscopy. Results. Main modes of Ge and W occurrence were studied. High-germanium-bearing coals of the Spetsugli deposit are characterized by different modes of occurrence. Along with the prevailing organic mode of Ge occurrence, mineral phases play a significant part. The importance of the mineral modes of Ge occurrence in the high-germanium coals is probably much higher than it has been previously thought. Various micron and nanometer mineral phases of Ge are widespread in the coal seams, especially near the weathering crust along the greisenized granites. In coals, aluminosilicate (silicate) mode of Ge, various ferrous (hydrogoethite, goethite, jarosite) and polymineral phases were met. The aluminosilicate (silicate) phase is represented by film-like congeries containing 0,15–0,4 % of germanium. Ferrous mineral congeries contain from 0,1 to 6,2 % of germanium. Anomalous Ge contents together with W and As were found in ferromanganese crusts – weathering products of greisenized granite of the basement, formed in the paleo-bog conditions. The presence of the secondary mineral phases of germanium in the coals allows assuming that Ge mineralization formation in the deposit can be longer in time than it has been considered earlier and is not limited to the peat stage. The research conducted has shown that in the highly-germanium coals of the Spetsugli deposit along with the organic modes of Ge occurrence the mineral phases play a significant role. The organic modes of occurrence are diverse and are not limited to complex humates. Tungsten is mainly characterized by the organic mode of occurrence. The role of the W mineral forms in its general balance in the coals of the Spetsugli deposit is insignificant. Only 1 grain of scheelite was found in the coals. Close to the weathering crust, tungsten in the coals was also found in the iron-manganese «crusts». It agrees with the results of the analysis of the W distribution coal phases. After the extraction of humus acids, 99 % of tungsten on the average passes into the alkaline extract. In the alkaline extract, about half of it is associated with the humic acids, and the rest is associated with the low-molecular organic acids.

Keywords

• ge-coal deposit
• coal
• modes of occurrences
• germanium
• tungsten
• organic association
• micro-mineral forms