Germanium resource provision from mineral deposits in Ukraine

The article is devoted to determining the resource potential of Ukraine in supplying industry with germanium. Statistical information on the potential content of germanium in various types of mineral raw materials located on the territory of Ukraine is summarized. The trends of the world market of germanium consumption in industry have been established. The value of the average content of germanium in coal deposits of the Lviv-Volynsky and Donetsky basins is given. It has been established that the greatest potential for germanium extraction is found in lignite deposits, the content of the valuable mineral in which can be ten times higher than that of hard coal. According to the results of research, germanium is found in the condition standards in ferruginous quartzites of the Annivske deposit of Kryvbas, Horishno-Plavnenske, Lavrykivske and Bilanivske deposits of the Kremenchuk district. The average content of germanium in ore deposits formed from magnetite, hematite, ribeckite, etc. was also determined. The approximate resource availability of germanium contained in deposits of coal, ore and non-ore raw materials of Ukraine was determined.


Introduction
Germanium, due to its insignificant content in the earth's crust and its geochemical affinity with some extremely common elements, shows a limited ability to form its own minerals, penetrating into the crystal lattices of other minerals.Therefore, native germanium minerals are extremely rare [1].
Despite the fact that the earth's crust contains approximately the same amount of germanium as common metals such as tin or lead, obtaining it in its pure form causes significant difficulties [2] .This is explained by the fact that germanium belongs to scattered elements, which, although often found in various inorganic and organic substances, are present in very small quantities [3].By integrating into the crystal lattices of other minerals, it replaces one of the atoms included in their structure.Such processes occur during the formation of minerals from aqueous solutions and molten rocks [4].Germanium can also enter sedimentary rocks through the processes of sorption and sorption inclusion [5].
Concentrations of germanium in industrial quantities are found in three genetic types of ores: hydrothermal, metamorphic, and sedimentary [6].There are also direct germanium deposits (germanium-sulfide, germanium-sulfosalt and germanium-coal) and deposits with associated germanium (complex ores of non-ferrous and ferrous metals, lignite and hard coal) [7].Germanium can also be found in other sources, such as oil and groundwater [8].It is also found in plants such as horsetails, ferns, sea grass and even in the blood of living organisms.The accumulation of germanium in coal is of great importance, especially in those types where the content of this metal ranges from 10 to 150 g/ton.The highest content of germanium is usually found in lignite deposits [9].Anthracite-type coal contains less germanium, which is explained by the tendency for its content to increase in accordance with the rising of the volatile substances content in brown coal.
It was established that the accumulation of germanium in coal occurs as a result of its introduction by water flows into ancient peat bogs from areas of erosion.Also, part of the germanium is additionally concentrated at the stage of diagenesis.It is believed that coal basins located in intermountain depressions of young mobile regions are the most enriched in germanium, and coal of river origin contains in 10 times more germanium than coal of lacustrine origin [10].In coal basins, the highest concentrations of germanium are noted in peripheral parts, closer to wear areas.Within one layer, areas near the roof and sole are most enriched in germanium [11].The analysis of coal from Donbas and the Lviv-Volynsky basin shows that as a result of coalification and metamorphism of coal, the concentration of germanium decreases due to the breakdown of functional humic groups, the release and migration of germanium within the coal deposit [12].
The results of research show that the distribution of germanium resources is approximately as follows: coal and carbonaceous rocks contain up to 85%, iron ores up to 11%, and sulfide ores (including lead-zinc and copper-zinc ores) up to 3% [6].In turn, the main source of germanium in Ukraine is the coal of Donbas and the Lviv-Volynsky Basin, with estimated reserves of 41,000 to 91,000 tons.[7,13], as well as Precambrian iron ores and ores of polymetallic and gold-polymetallic deposits, where it is found as a concomitant component [14].Thus, the purpose of the research is to determine the distribution of germanium in the main mineral deposits in order to establish the resource potential of Ukraine.

Methods
During the research, the analytical method was used to analyze and generalize statistical information about the potential content of germanium in various types of mineral raw materials located on the territory of Ukraine.The method of technical and economic analysis was used in forecasting the country's germanium resource supply in the future, taking into account the total reserves of ore and non-ore raw materials, as well as hydrocarbons.
Determining indicators of resource supply with germanium for the domestic and world markets should take into account the dynamics of the growing the demand for the production of modern electronic devices in which this raw material is used.This goal can be achieved by solving the following tasks: analyze trends in the world market of germanium consumption, taking into account forecast data; to establish Ukraine's resource security with germanium contained in coal deposits and other mineral deposits of Ukraine.

Results and discussion
The growing trends of germanium consumption in the world is confirmed by the constant growth of the world production of this mineral.It is established that the world production of primary germanium has a tendency to increase from 165 (2015) to 320-400 t by 2030.At the same time, the main consumers of germanium are the enterprises of Germany, Belgium, Canada, the USA, China, France, and Japan [15] .
China is currently the main producer of germanium, which produces more than 70% of this metal, which is then sold on the world market.The total volume of global production of dioxide and metallic germanium in 2022 approached 230 tons, which significantly exceeds last year's figures [16] (Fig. 1).This is due to the growth of demand in the USA and the EU, which use this metal in the high-tech production of electronic devices.Since much of this critical mineral is produced in China, global markets are highly dependent on one country.Therefore, diversification of the production and supply of germanium in other worlds countries is an urgent task for the world community.Today, the market of Ukrainian Germanium can make a significant contribution to the corresponding needs of the European and world economy [17].At the state level, the need to develop the deposit is confirmed by the President's order and relevant resolutions of the Cabinet of Ministers of Ukraine.
First of all, the domestic germanium market can include producers of germanium coke chemical concentrate, companies developing coal deposits with category "B" (deposits with significant concentrations of germanium), as well as enterprises that produce germanium ash concentrate.In the second and third stages, the market can be composed of enterprises processing germanium raw materials and enterprises consuming germanium and its compounds, which respectively produce hightech products with high added value [18].
According to the analysis of germanium consumption in industry, it was found that it is most in demand in the manufacture of optical fibers for communication, catalysis of polyethylene phthalates, infrared technology, radiation detectors, semiconductors for optimal modes, as well as medicine and metallurgy.According to information with open access, the distribution of germanium use in industry is presented in figure 2. The resource potential of Ukraine in the world regarding the extraction of germanium from coal, ore deposits and telling allows to create the newest germanium industry.For this, it is necessary to perform an effective assessment of reserves for the national economy and determine the directions of state policy and interaction with the private sector [19].This will additionally increase the efficiency 1319 (2024) 012007 IOP Publishing doi:10.1088/1755-1315/1319/1/0120074 of the development of strategic [20] and critical raw materials, as well as reduce the environmental disturbance on the territory of the mining district [21].
According to information with open access, the estimated reserves of categories A+B+C1 germanium in Ukraine (in coal) amount to 41 thousand tons [13].The main coal basins where the content of germanium has been determined are Lviv-Volynsky, Donetsky and Dniprovsky lignite basins.
It was established that germanium-bearing deposits of group "A" with germanium content at the level of 3 g/ton refer to deposits of the Lviv-Volynsky and Donetsky basins, and group "B" includes lignite deposits [22], carbonaceous argillites and siltstones with an abnormally high concentration of at least 100 g/ton (Figure 3).As an example, the Malobigansky lignite deposit located in the Berehiv district of the Zakarpattia region is presented, the development of which is complicated by geological conditions of occurrence and environmental risks [15].For the Malobigan lignite deposit, technological solutions of germanium extracting by the existing methods and obtaining an ash concentrate are proposed.The developed proposals will allow to restore the domestic germanium production complex.Technological solutions consist of monitoring the germanium content of coal seams, the creation (modernization) of concentrate production units based on the treatment of tar water, the reorganization of chemical and metallurgical plants, and the development of the ash component from the burning of metal-bearing thermal coal [15].
The germanium content of the coal seams of the Chervonograd geological and industrial district and the Lubelsky deposit of the Lviv-Volynsky basin was analyzed for its further use as a critical raw material.It has been established that the development of germanium is a rather promising direction in the complex development of coal deposits.At the same time, the metal content varies from 0.3 to 9.2 g/ton, depending on the type of coal (anthracite or low metamorphism).For industrial use, the average content of germanium should be at least 4.5 g/ton of coking coal.It was determined that the distribution of this critical element is uneven and depends on the depth of occurrence and the growth of metamorphism [23].
The analysis of the germanium content in thin layers (0.5-1.5 m) over the area of coal deposits of the Lviv-Volyn Basin and Western Donbas allows to establish that the distribution of this critical metal is uneven with an average content of up to 2 g/ton.It was determined that with an increase in the capacity of the coal deposit, the content of germanium, which is confined to a low-ash coal seam (no more than 18%), decreases, and the weighted average content within the deposit is 9-12 g/ton [6].
In the Lviv-Volyn Basin, the Westphalian, Namurian, and Visean strata are coal-bearing.The deposits of the Namur layer, to which the main industrial layers of the basin belong, have the highest carbon content.The carbon content of the main productive stratum -Namyuranoticeably increases in the southern direction.The working capacity varies from two to five layers, depending on the location.
According to the content and nature of distribution of germanium, the coal of the basin belongs to the category of poor with uneven distribution both in area and section.The content of germanium reaches maximum values in the central part of the basin, in the south-north direction it dramatically decreases [6].Similar to coal, igneous rocks also contain germanium (average content up to 2 g/ton); in quantitative terms, they are 2.1-3.7 times poorer in germanium than coal.Geological strata are also poor in germanium, the germanium content here is 1-2 g/ton.
In accordance with the geological conditions of formation, the following patterns of germanium behaviour in the process of sediment accumulation were established in the studied area.Firstly, the distribution of germanium across the stratum cross-section is uneven, which is manifested in anomalous mineralization of small (0.10-0.20 m) layers of coal in the roof and sole of the stratum.At the same time, tectonic disturbances did not have a basic effect on the accumulation and distribution of germanium in the coal of the basin.Secondly, there is an inverse relationship between reservoir capacity and germanium content -as the capacity increases, the germanium content decreases accordingly.
From the point of the mineral composition view, impurities have different effects on germanium precipitation in the coal seam.It has been established that germanium is selectively limited to coal with a small ash content, i.e. low-ash coal (up to 18%) is more promising for germanium than high-ash coal.The petrographic composition of the coal does not fundamentally affect the accumulation and distribution of germanium in the basin, however, the role of the source material during the germanium accumulation was not the same and was manifested in its local concentration by its gelled substance.
The rocks of the Precambrian crystalline foundation, on which there is a powerful complex of sedimentary formations of the Devonian, Carboniferous, Permian, Triassic, Jurassic, Paleogene, and Quaternary ages, take part in the geological structure of the deposits of western Donbass.In comparison with other hard coal basins, it was established that the coal-bearing area of the Donbass deposits belongs to the deposits with the richest ore occurrence of germanium, which is contained in coal of the Lower and Middle Carboniferous.
On the basis of research [9] regarding the content of germanium in the coal of Western Donbas, the following conclusions were made.Firstly, all the tested coal seams are germanium-bearing with an uneven distribution of the substance by section and area.The largest mineralization is located in the central and western parts of the district in the Dimytriivska, Taranivska, Alefirivska, Blagodatnenska, and Pavlograd areas.Secondly, germanium-enriched areas and lenses have broken contours and are located both at the outcrops of layers and at their middle and deep occurrence.The content of germanium directly depends on the content of the vitrinite group microcomponents and inversely -on the content of the fusenite and leuptinite groups microcomponents.Accordingly, the main concentrator of germanium is the gelled substance, regardless of the coal type.
The conducted studies showed that the issue of germanium content in rock dumps of coal mines requires separate study.Germanium is not extracted during coal mining in the Lviv-Volynsky and Donetsk basins.But previous studies [5] indicate that its industrial concentrations also occur in beneficiation products and mine waters, so the concomitant development and extraction of germanium is one of the ways to improve the economic indicators of the mining industry [24].
In addition to coal deposits, germanium is present in significant quantities in the iron ores of Kryvbas and the Kremenchug iron ore district.Germanium was also found in iron-siliceous rocks of the greenstone structures of the Middle Dnieper region (in ferruginous quartzites of Surska up to IOP Publishing doi:10.1088/1755-1315/1319/1/0120076 30 g/ton, Verkhivtsevska up to 19.3 g/ton, Chortomlytska up to 2.0 g/ton, Bilozerska up to 4.4 g/ton) and iron ores of deposits of the Azov megablock (Gulyajpilske, Mariupolske deposits, etc.) [25].
Concentrations of germanium in industrial quantities are found in three genetic types of ores: hydrothermal, metamorphic and sedimentary.There are also direct germanium deposits (germaniumsulfide, germanium-sulfosalt and germanium-coal) and deposits with accompanying germanium (complex ores of non-ferrous and ferrous metals).The main minerals in which germanium is concentrated are magnetite, hematite, ribeckite, aegirine and tetraferribiotite.The content of germanium in iron ores of the specified areas, on average, varies from 8 to 60 g/ton, and the estimated resources are estimated as industrial [6].
The average content of germanium in ferruginous quartzites of Kryvbas varies within 6-8 g/ton.It is mainly concentrated in magnetite (2-62 g/ton), less in hematite, martite, other iron oxides, ironcontaining silicates (amphibole, pyroxene, biotite, chlorite, etc. -up to 3-18 g/ton) The average content of germanium in different types of iron ores is shown in figure 4. Germanium is contained in ferruginous quartzites of all stratigraphic horizons and has general patterns of distribution along the section.First, the content of germanium naturally increases from the bottom up along the section to the interval of its peak concentrations, regardless of the mineral and phase composition of the ferrous rocks.In the lower iron ore pack above the interval of peak concentration, germanium is distributed either relatively uniformly or in jumps.In the upper iron ore pack, which is distinguished by a clear tendency to decrease in content towards the roof, the distribution of germanium is practically inversely proportional to the iron content of the rocks.
Secondly, the content of germanium in the geological structures of the area is approximately the same and, on average, is equal to or slightly lower than the background.At the same time, the peak concentrations of germanium related to the roof in the areas with ore concentration, and with the "medium" content refer to the parts near the bottom of the lower iron ore pack they differ significantly and amount to 12-24 and 6.3-9.4 g/ton, respectively.These features of the germanium distribution in the ferrous rocks of the Right Bank district are common to all iron ore strata of the Early Proterozoic age, this is indicated by the results of the primary geological comparison and geochemical materials in the areas of the, the Annivske deposit of Kryvbas, Horishno-Plavnenske, Lavrykivsle and Bilanivske IOP Publishing doi:10.1088/1755-1315/1319/1/0120077 deposits of the Kremenchug district [26].A similar nature of germanium distribution was established within the South Bilozersky deposit [27].
The highest germanium content (16-28 g/ton) in Kryvbas is noted for magnetite concentrates obtained during the enrichment of quartzites of the Annivske deposit.According to germanium mineralization, this deposit belongs to the powerful stratigraphic horizons of ferruginous quartzites, which are characterized by huge reserves.
The issue of germanium content in Kryvbas tailings requires a separate study.Research results [7] showed that coarse-grained material composed of quartz, magnetite, and hematite with non-ore minerals accumulates in the near-dam areas of tailings impoundments [28].There are also ironenriched areas in larger tailings, where a different pulp feeding scheme is used.It should be noted that about 25% of iron and other components, including germanium, which could be used in green industry [29], are lost annually with mining waste after beneficiation.
Therefore, on the territory of Ukraine there are several types of sources for obtaining strategic mineral raw materials, including germanium.In further research, it would be advisable to conduct a detailed analysis of coal and ore deposits for the content of both germanium and other liquid and scattered elements, which will make it possible to create a cadastre of the most promising objects and develop regulations for their development.

Conclusions
The analysis of the current state of the raw material base in Ukraine confirms the prospects for the development and extraction of germanium, which is restrained by the insufficient study of the tasks of the using the accompanying minerals of coal, ore and non-ore deposits.The relevance of the issue increases due to the lack of scientifically based methods of evaluating critical raw materials as a accompany component at the extraction of basic minerals.In this way, the complex extraction of germanium makes it possible to comprehensively solve the problem of improving the economic indicators of the coal industry and providing the world market with germanium.
It was established that, according to open sources of information, the estimated reserves of germanium categories in the coal deposits of Ukraine amount to 41 thousand tons.These resources are distributed among the coal deposits of the Lviv-Volyn and Donetsk coal, as well as the Dnipro lignite basins.It was determined that the average content of germanium in coal deposits of the Lviv-Volynsky and Donetsky basins is in the range of 5-11 g/ton, while lignite deposits, carbonaceous argillites and siltstones with an abnormally high concentration can contain more than 100 grams of germanium per ton.
Studies of the germanium content in iron ore deposits of Ukraine confirm the presence of a conditional content in the ore raw material of the Annivsky deposit of Kryvbas, Horishno-Plavnenske, Lavrykivske and Bilanivske deposits of the Kremenchuk district.According to established data, the average content of germanium in different types of iron ores of Kryvbas is 4-6 g/ton, sometimes reaching up to 15 g/ton.The dams and areas and tailings of iron ore deposits, in which coarse-grained material composed of quartz, magnetite and hematite with non-metallic minerals accumulate, have significant potential.According to the results of existing research, it was established that about 25% of iron and other components, including germanium, are lost annually with rocks waste after beneficiation, which can be removed by improving the existing technology of raw material enrichment.
This work was conducted at the Dnipro University of Technology within the educational project "Critical raw materials provision in the European Union" (#101127415-CRMPEU, ERASMUS+ Jean Monnet, Dnipro University of Technology).

3 Figure 1 .
Figure 1.Trends in global demand and prices for metallic germanium for the period 2017-2022.