Мінеральні ресурси України (Sep 2024)
Prospects and possibilities of germanium extraction from the Bigan coal deposit
Abstract
The article is devoted to lignite deposits of Zakarpattia, which contain germanium, in particular, the Bigan deposit and methods of extracting germanium from this deposit. Ukraine has coal deposits with industrial concentrations of germanium and industrial capacity for obtaining high-purity germanium. Until recently, this allowed the domestic germanium complex to be among the leaders of the world market. Unfortunately, now the production of germanium in Ukraine is suspended, and the processing of metal-bearing coal is carried out without obtaining the corresponding germanium concentrate. Ukrainian coal deposits, which are characterized by germanium metal content, are currently not used in full for their complex purpose. The state mineral balance of Ukraine as of January 1, 2024 includes 226 subsoil exploitation objects with estimated germanium reserves. Germanium in Ukraine is associated mainly with coal deposits of the Donetsk and Lviv-Volyn coal basins, where it is found as an accompanying component. Germanium is found in all coal beds of the Lower, Middle and Upper Carboniferous of Donbass, but the most productive beds are found in hard coal of the Middle Carboniferous. Germanium content in Donbas coal ranges from 0.3–1.3 g/t in anthracite to 3.8–9.2 g/t in low-metamorphosed coal grades D, DG, G; however, as a rule, only coking coal with an average content of germanium at the level of 4.5 g/t was once used to obtain this metal thanks to the processing of the corresponding concentrate, which was produced at the chemical plants of the coke-chemical plants of Ukraine using the technology of extracting germanium compounds from supertar water. The content of germanium in brown coal of the Dnieper basin is relatively low (1–2 g/t of ash). At the same time, in the Transcarpathian lignite basin, the main mass of which is small deposits confined to the deposits of the Ilnytsia world of the Neogene Chop-Mukachivska and Solotvyn depressions. Thus, the content of germanium in lignite of the Novoselytskyi deposit is up to 280 g/t, in the Bigan deposit – up to 1000 g/t. The Bigan deposit itself requires further research as one of the most promising lignite deposits in Germany. It is worth noting that germanium is found in significant quantities not only in brown coal (lignites), but also in carbonaceous clays, where the concentration of germanium reaches 200 g/t. The decisive factor in the distribution of germanium in the layers is the nature of the plant material from which this layer is composed. Based on the analysis of the results of the work carried out, the highest germanium content (over 1000 g/t) is confined to pure varieties of lignite, and especially weakly carbonized wood residues, the amount of which depends on the concentration of germanium in the formation as a whole. It is quite clear that germanium in lignites is associated with humic acids, forming organometallic compounds. This is confirmed by the fact that by treating lignite with a 1% ammonia solution, it is possible to obtain up to 98% germanium. Geological exploration work at the Bigan deposit was carried out intermittently from 1953 to 1969. In 1961–1965, search operations were carried out on an area of about 30 km². Total of 486 wells (87,000 cubic meters) have been drilled in the field and adjacent areas since the beginning of geological exploration. The preliminary exploration of the Bigan deposit was carried out using the results of the search and exploration works of 1961–1967, while technological studies of the lignites of this deposit were also carried out. As a result, a feasibility study was drawn up, the summary of which was reduced to the fact that the Bigan deposit is characterized by a relatively high content of germanium, which allows this deposit to be considered a large potential source of germanium. It is worth noting that in the 80s of the last century, a technology was developed for the industrial development of the Malobigan and Bigan deposits by burning lignite at the Uzhhorod TPP, followed by hydrometallurgical processing of ash and dust containing several kilograms of germanium per ton. It is important that in Transcarpathia, in addition to the above-mentioned deposits, there are 15 more unexplored, but promising germanium-bearing areas. It should be noted that the concomitant extraction of germanium is one of the ways to improve the economic indicators of the coal industry and the comprehensive use of lignite deposits of Zakarpattia. The set of works carried out allows judging on the basis of experimental data about rational ways of using germanium-bearing lignites of the Bigan deposit.
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