Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57 https://doi.org/10.5564/mgs.v0i49.1227

Mongolian Geoscientist

Review paper

Uranium deposits of Mongolia, their exploration and mine development

Dorjyunden Altankhuyag1*, Baldorj Baatartsogt2, Batbold Munkhtur3

1Department of Strategic Policy and Planning, Ministry of Mining and Heavy Industry, Mongolia, Ulaanbaatar 15160, Mongolia 2Administration Department, Nuclear Energy Commission, Mongolia, Ulaanbaatar 17032, Mongolia 3Department of Geology and Mining Policy Implementation and Coordination, Ministry of Mining and Heavy Industry, Mongolia, Ulaanbaatar 15160, Mongolia

*Corresponding author. Email: [email protected]

ARTICLE INFO ABSTRACT Article history: Most of the known deposits in Mongolia are related to volcano-tectonic Received 9 May 2019 structures of the Late Mesozoic and permeable sandstone aquifers of terrigenous Accepted 26 September 2019 sedimentary rocks in Late Mesozoic-Cenozoic basins. A young uranium deposit has been recently discovered at the surface in Quaternary alluvial sediments. Uranium deposits are classified here according to the International Atomic Energy Agency (IAEA) classification scheme. Beside of supergene and hydrothermal uranium discoveries, uranium mineralization can also be found in the Lower Cretaceous lignite seams, in Mesozoic alkaline intrusive rock related REE, Th, U enriched mineral systems and in metasomatic rocks, as well as in migmatites and pegmatites localized in Precambrian metamorphic rocks. Currently, no uranium can be produced in Mongolian facilities except pilot testing being done first. A pilot test was carried out at the Khairhan and Kharaat deposits in Mongolia and these experiments have demonstrated the ore to be amenable to acid leach (sulphuric acid) with the addition of an oxidizing agent. These tests confirmed that hydraulic control can be maintained and that the uranium solubilization and mobilization can be controlled. The results of the test were encouraging, with the well production rate, uranium concentration in produced solutions, chemical usage, and estimated uranium recovery all within ranges expected for normal commercial operations. There are a number of Mongolian uranium deposits are in the stage of mine development. The Government of Mongolia has approved the agreement of mine development of the Zuuvch ovoo and Dulaan uul deposits. Pilot testing on these deposits is underway and uranium will be extracted by in-situ leaching soon.

Keywords: Uranium metallogeny, classification, activity

INTRODUCTION The Nuclear Energy Law provides the The Parliament of Mongolia endorsed the State government the right to take ownership without policy on Use and Exploitation of Radioactive payment of not less than 51% of the shares of a Minerals and Peaceful Uses of Nuclear Energy project or joint venture if the uranium in 2009 and subsequently adopted Nuclear mineralization was discovered by State funded Energy Law in the same year. exploration, and not less than 34% if State

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Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57 funding was not used to find the mineralization. international organizations such as the IAEA Licenses to conduct uranium exploration and and European Commission. production of any radioactive minerals must be Mongolia is focusing on the development of its obtained under this law. projects that will lead the country to the global The implementation of the state policy is not uranium market in near future. To achieve this going as planned due to challenges related to goal, the government is seeking to resolve public awareness and global energy policy challenges such as the public perception on trends in countries utilizing nuclear power. nuclear energy, human resources development There are about 60 types of minerals in 2500 and infrastructure. deposit areas found in Mongolia. The The government of Mongolia established Mon- government of Mongolia is pushing deep into Atom LLC in 2009 as the national operator of the development of infrastructure for the legal Mongolia for all uranium mining activities, and regulatory frameworks of uranium including export and trade of uranium exploration and exploitation to increase the state production. This company will be a partner to income based on the proven uranium reserves every uranium project and will hold the state and its prospectus. shares stipulated in Nuclear Energy Law. As cited in the Nuclear Energy Law of Mongolia, the Nuclear Energy Commission GEOLOGICAL CLASSIFICATION OF (NEC) is the head body in the nuclear energy URANIUM DEPOSITS field. The NEC is responsible for coordination Uranium deposits in Mongolia are based on the and formulation of all activities embedded in the IAEA classification scheme (Bruneton and State policy, including development of science Cuney, 2016) and are described in order from and technology, human resources development, deep primary (endogenic) magmatic deposits to exploitation of radioactive minerals and nuclear (exogenic) sedimentary and surficial deposits energy applications, radiation protection and following the geological cycle (Cuney, 2010). nuclear safety, and promotion of the nuclear Subtypes are classified according to definition energy field within the territory of Mongolia, as by Dahlkamp (Duhlkamp, 2009). Volcanic- well as implementation of international treaties related, sandstone and exogenic type of uranium and conventions on nuclear issues. The NEC deposits are found, in addition to, granite- issues licenses on nuclear material issues and related, metasomatite, lignite-coal and nuclear facilities. It also adopts and endorses types of uranium mineralization general nuclear and radiation safety regulations (Jamsrandorj et al., 2016). and rules on exploitation of radioactive According to the investigation of confirmed minerals, radiation applications and nuclear sandstone-type uranium deposits (OECD(NEA)/ energy, stipulated in Nuclear Energy Law IAEA, 2005) and oil-gas, coal exploration and (Chadraabal and Manlaijav, 2017). excavation, 82% of the total sandstone-type The Mineral Resources and Petroleum uranium deposits coexist with confirmed oil-gas Authority (MRPAM) under Ministry of Mining fields and coal fields in the same basins (Liu et and Heavy Industry is responsible for al., 2007). Energy resources, such as coal, oil exploration and mining licensing of radioactive and uranium are supplied from large minerals, whereas, the General Agency for sedimentary basins in Mongolia. In recent years, Specialized Inspection bears the responsibility sandstone uranium deposits closely associated to provide for the government administrative with hydrocarbon-bearing basins have been inspection services in the country. identified in the Zuunbayan basin, and similar The NEC is playing a leading role in the basins are found at Matad, eastern Mongolia and development of a nuclear legal framework Ail, southern Mongolia. Energy basins and sub- through drafting, formulating and renewing basins distributed on the territory of Mongolia regulation and guidance based on the existing are shown in Fig. 1. legislations and also studying best practices of developed countries, as well as cooperation with

51 Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57

Fig. 1. Distribution of energy basins and main Mesozoic-Cenozoic tectonic structures (After Badamgarav et al., 2011).

Volcanic-Related Deposits Coffinite and pitchblende in association with This type of uranium deposits is commonly galena, molybdenite and pyrite precipitated at located within volcanic calderas filled with the mineralization sub-stage, and bimodal volcanic and volcanoclastic sediments the -carbonate-kaolinite stockwork with (Mironov, 2006). These deposits are marcasite characterize the post- mineralization characterized by fluorite-molybdenite- stage. Uranium bearing keritic carbonaceous pitchblende (+apatite) mineralization. The material was detected in the ore in addition to coincidence of the slab boundary projections coffinite and pitchblende. Molybdenum is of and area of their influence with the spatial economic importance in the stockwork zone position of large F-Mo-U ore clusters separated together with uranium. Uranophane, autunite, from each other by hundreds of kilometres. uranotil, and uranospinite occur in the zone of Dornod, Gurvanbulag, Mardain gol, Khavar and oxidation. Nemer deposits and numerous occurrences Northeastern and Central Mongolia are volcanic Gurvanbulag -related type. The main uranium minerals at Gurvanbulag deposit are coffinite, uranophane and Dornod pitchblende. Alteration accompanying the This deposit is hosted in volcanic rocks, uranium mineralization was generally weak, composed of amygdaloidal and brecciated being limited to silicification, and hematite and basalts and andesites. Uranium mineralization chlorite. Some fluorite may have been occurs as pitchblende-coffinite assemblages introduced at this stage. Post-uranium associated with carbonaceous matter in areas of mineralization alteration minerals are quartz, structural preparation (Jamsrandorj et al., 2015). fluorite, hydromicas, chlorite, kaolinite (dickite), 52 Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57 montmorillonite, zeolites (analcime), and Sainshand Formation upper member. The carbonates. thickness of the sandy layer with the main Molybdenite and other sulphides occur in small uranium ore ranges between 35 and 40 m (Fig. quantities include galena, sphalerite and 2), and its composition is uniform and has chalcopyrite. medium and large sand granules and small organic scatterings. Oxidation-redox boundaries Sandstone Deposits in sedimentary bed stratification are The sandstone uranium deposits occur in characterized by grey-yellow sand for the medium to coarse grained terrigenous oxidation zone and grey feldspar grains and coal sedimentary rocks in the Late Mesozoic- clasts in the reduced zone. Pyrite, kaolinite and Cenozoic basins in Mongolia. This type of rare hematite are present at the edge of the redox uranium mineralization is closely related to front. The reduced sandstone has higher uranium-enriched source rocks and permeable radioactivity values. The structure and sandstone aquifers. The Kharaat, Khairhan, hydrogeological conditions of this valley played Dulaan uul, Zuuvch ovoo, Gurvansaikhan, an important role for uranium accumulation. Ulziit, Engerar deposits and other occurrences Electron microscopy analyses on the uranium are situated in the Choir, Khairhan, Zuunbayan, bearing samples indicated that uranium occurs Unegt basins of the southeast Gobi. Typically, in lignite as micro grains, and rarely as uranium- sandstone hosted uranium occurrences are iron micro grains in the quartz grains. As result precipitated by reduction processes. The highest of above analysis, uranium is relatively mobile grade of mineralization is hosted in the medium and amenable to acid leaching. Cogegobi has to coarse grained sandy, lacustrine sediments. been holding a majority of exploration licenses Sandstone hosted uranium deposits of Mongolia among exploration companies and played a can be classified roll-front and basal channel or main role in the discovery of Zuuvch ovoo (67 paleovalley sub-type (Budunov, 2006; Hocquet, 706.77 tons of U), Dulaan uul (7054.71 tons of 2016). U) and Umnut (4746.14 tons of U) deposits in Dornogobi province. Zuuvch ovoo and Dulaan uul The Dulaan uul is a sedimentary uranium Kharaat deposit characterized by non-permeating thin The Kharaat uranium deposit is located in a late argillaceous layers dominated by sand and Mesozoic extensional basin, which in central uneven thickness and are divided into east Mongolia. These basins, are likely fault mineralized layers. An oxidized zone is bounded grabens and half grabens, and were distributed mainly in the south of the valley, filled by terrigenous sediments during the whereas, a redox zone is mainly in the north, but Jurassic and Cretaceous periods) Budunov and also in the center of the Unegt sub-basin. Jamsrandorj, 2012). The variegated section is The uranium in the Zuuvch ovoo deposit in the comprised of conglomerate, sandstone, and Zuunbayan valley mainly occurs in layers of the siltstone, and occurs mainly on the margins of

Fig. 2. Schematic cross section and distribution of uranium of Zuuvch ovoo deposit (After Hocquet,

53 Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57 the depression. The facies is comprised of oxidized zone serves as a supplier of uranium to lacustrine sediments, typically clays and the redox front. argillaceous sandstone, with interbeds of brown coal and disseminated iron sulphides. CURRENT ACTIVITIES Mineralization is present in significant Exploration and Reserves concentrations both above and below the water For uranium deposits, the major preparatory table. Typically, mineralization below the water work for the recovery is underway due to the table occurs in grey-coloured rocks or at the completion of deposit development agreements interface of the red oxidized rocks. between the government and potential Mineralization below the water table occurs stakeholders. Mongolia is focusing on the primarily as uraninite with smaller amounts of potential projects that will lead the country to coffinite. The uranium minerals occur as films the world uranium market in the near future. and diffuse haloes on and between individual Through the experiences over the past few rock fragments and sand grains. In the oxidizing years, the uranium exploration entities are environment above the water table, secondary deemed as essential for the social licensing in uranium minerals are present and include potential mining areas in line with the State autunite, bergenite, phosphuranylite, Policy. schroeckingerite, torbenite, and minor amounts The history of uranium exploration in Mongolia of other uranophosphates. could be divided into three phases. The first In the Choir basin, greater than 70% of the phase started in the middle of the 1940s, known mineralization with potentially economic whereas the second phase covers a period of grade occurs above the natural water table. Full 1970 to 1990 where the specialized geological saturation of the ore-bearing section is the surveys were conducted with a result of 1,600 of normal condition for in situ recovery; however, radioactive anomalies and hundreds of the In Situ Recovery (ISR) test at Kharaat occurrences identified by the joint expedition included leaching from both saturated and with the Ministry of Geology of the Soviet unsaturated horizons. Union under a bilateral agreement between the People’s Republic of Mongolia and the Soviet Khairhan Union. The third phase started in 1990s with the The Khairhan deposit is located in the northwest private stakeholder’s engagements including part of the Khairhan basin. The Khairhan basin local and foreign entities. Due to the prevalence is filled by coal-bearing gray colored Cretaceous of findings, features of mineralization and Zuunbayan Formation and covered by significance to manufacturing, Mongolia’s Sainshand Formation around south edge. The eastern, south-eastern and central regions are host sedimentary rocks of the Khairhan deposit relatively well-studied. It is estimated that there consist of unconformable clastic and lacustrine are about 1.47 and 1.0 Mt of U resources in total sandstones and shales. The ore is by Mironov in 1993, and Jamsrandorj et al., in aluminosilicate and carbonate-free. Uranium 2016, respectively. According to the statistics of mineralization is mainly represented by Mineral Resources and Petroleum Authority of pitchblende; coffinite is of secondary Mongolia, uranium reserves are assessed at importance. Autunite and uranophane occur in 166,657 tons of U in total by 2019. the oxidized rocks. Molybdenum is the main The depletion of costs uranium causes the associated element; the Mo grade in the ore exploration strategy changes globally to the low reaches 0.05%. The hydrogeological conditions cost uranium, especially sandstone type at the deposit are complex but generally deposits. Therefore, uranium exploration was favorable for uranium recovery by underground focused and targeted on Mesozoic and Cenozoic leaching. The ore mineralization is localized basins in south-east Mongolia. below the groundwater table, being largely The “Uranium” state-owned manufacturing hosted in permeable rocks. The uranium enterprise, in cooperation with the IAEA, concentration is controlled by reduction, and the conducted a project entitled “The state of

54 Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57 uranium in Mongolia and its assessment” in two Preparatory Work for the Uranium phases between 1993 and 2001, completing the Exploitation topical research work on “Mineralization of There are currently eight deposits on which sedimentary and metasomatic uranium.” Within Feasibility Studies have been completed and this research project, a related research work on approved by Mongolian Professional Committee the radioactivity of coal deposits and of Resources. These studies reflect that “Areva construction-related mines in Ulaanbaatar, Mines” LLC will begin exploitation of the Baganuur, Shivee-Ovoo was conducted. Since Dulaan uul and Zuuvch ovoo deposits beginning then, geological studies, prospecting and in 2022. “Emeelt Mines” LLC will begin exploration of radioactive minerals have not exploitation of the Gurvanbulag deposit been funded by the state budget. Recent years beginning in 2018 according to their Feasibility (2016-2018), the government has conducted Studies. In Mongolia, Areva Mongol LLC, airborne and ground geophysical survey subsidiary of Areva Group in Mongolia, and covering southwest Mongolia. Based on the Uranium Industry LLC of the Czech Republic result of gamma spectrometric survey, the have been leading entities in the uranium mining Baruunkhurai, Gobi-Tengeruul, Khustiinnuruu, sector up to now. Songinot uranium potential zones were The Orano Group, formerly known as Areva described and most of these anomalies could be Group, has been active in Mongolia since 1997 related to alkaline granites with REE and created Cogegobi LLC with a local mineralization. company named Gobigeo LLC (30% shares of The Dornod open pit mine and underground the company) to conduct geological and orebody was mined between 1988 and 1995. exploration work with a view to identifying The ore was railed 480 km to Krasnokamensk in prospective areas of uranium concentration. Siberia for treatment by Priargunsk enterprise. Since 2009, Cogegobi has been fully owned by Only about 535 tons of U was produced, all Areva Mongol. from open pit mining. Gurvanbulag, about 30 One of the potential projects is Zuuvch ovoo, km west of Dornod, had extensive underground Dulaan uul uranium project in Dornogobi development down to 560 metres in the Soviet province in east-south region of Mongolia. The era, and was readied for production. The deposit will be mined by in-situ leaching method metallurgical testwork at the Dornod deposit has using a sulphuric acid. There was an ISR semi- been done and reported by Russian side before production test on the Umnud site in Dulaan uul 1990s. These documents provide information on in 2010-2011. 2.9 tons of uranium was fixed in the various process options investigated and resin from 2 test cells. The total reserve of the unfortunately, conventional Pachuca leaching ore was 3.4 tons. There was a column leaching was not extensively evaluated. In the Russian test and the test to determine conditions on 32.9 work, only limited results were found to indicate kg of samples from five wells in the Zuuvch the recovery that might be expected from the ovoo deposit in 2011-2012. There were a deposit using acid leaching under atmospheric column leaching test and a titration test for the conditions. The processing plant that has been purpose of confirming the results of the previous designed for the Gurvanbulag operation is based test in 2013. on a Resin Extraction Process. The first stage of The Nuclear Energy Law requires a mining processing is the sorting stage. This is followed licensee to sign a Deposit development by grinding, leaching, the resin extraction agreement with the MRPAM, so Areva Mongol process and elution, product precipitation, and signed this agreement with the MRPAM in July finally calcination and packaging. The 2016. The company is going to conduct a pilot processing recovery was considered at around test in Zuuvch ovoo and obtain statistical 95%. information in Feasibility Studies, covering the Zuuvch ovoo and Dulaan uul deposits, which was approved by Mongolian Professional Committee of Resources in 2015. Areva Mongol

55 Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57 previously conducted a pilot test in the Dulaan with the onset of freezing weather. uul in 2011. Another major agreement cited in The 1998 Khairhan test confirmed the the Nuclear Energy Law is an investment leachability of the mineralization at Khairhan. agreement between an undisclosed licensee and Although a single, small test may not be the Government. Uranium production is completely definitive, the results of the expected to start in 2022. Khairhan test were encouraging, with the well In 1994, a small ISR test was run at Kharaat to production rate, uranium concentration in determine the amenability of the deposits to ISR produced solutions, chemical usage, and technology. The success of this work led to estimated uranium recovery all within ranges more significant testing in 1996. This involved expected for normal commercial operations. the acquisition, assembly, and operation of an Deposits containing geological reserves of ISR Pilot Plant at Kharaat. The plant was a fully 23,019 tons of U occur in Dundgobi and integrated facility, capable of producing final Sukhbaatar provinces covering an area of 28,490 product, although drying and packaging hectares. Deposits were discovered in 2009- equipment were not included. The plant handled 2013 and Feasibility Studies for Kharaat and a nominal flow rate of 20 m3/h, although under Khairkhan were done in 2011 and optimal conditions, it could be operated at a Gurvansaikhan and Ulziit in 2014, respectively. higher rate. The plant consisted of an ion Environmental Impact Assessment was exchange circuit, a resin desorption and approved by the Ministry of Environment in regeneration circuit, a uranium precipitation 2011. As approved in Feasibility Studies for circuit, and all of the necessary ancillary and those four deposits, the extractions are support facilities. conducted by In Situ Leaching technology. The testing in 1996 included tests of the The licensee of these Kharaat, Khairhan, recovery of mineralization both above and Gurvansaikhan and Ulziit deposits is below the water table, the latter being the Gurvansaikhan LLC, a subsidiary of Uranium normal operating regime for an ISR project. Industry LLC of the Czech Republic. Uranium Sulphuric acid was the primary leaching agent Industry LLC purchased Gurvansaikhan LLC used in both tests. These tests confirmed that from Denison Mines Corporation in 2015. hydraulic control can be maintained and that the Gurvansaikhan LLC signed a Deposit uranium solubilization and mobilization can be development agreement for those four deposits controlled. Both tests encountered operating with MRPAM in September 2016. circumstances that pointed out the necessity to conduct further commercial scale testing at Infrastructure Kharaat. The test above the water table is There are some issues such as required believed to be the only work of this kind that investment volume, qualified human resources has been conducted in the world. While in-place and local infrastructure, as well as the legal leaching of unsaturated mineralization has been environment for conducting mining operations shown to be possible, further work is necessary of radioactive minerals. During this period to confirm the economic viability of this where ISL technology is being introduced, there method. is a need to study the advantages and An initial ISR test was completed in 1998 to disadvantages of technologies, safe operations, determine the appropriate leach chemistry and features, modes and standards of technology and to verify it under actual field conditions. The knowledge base. This will enable the technology test consisted of a single production well to be introduced as well as provide a public with surrounded by four injection wells and key information and awareness related to associated monitoring wells. The ion exchange uranium extraction technologies. and resin desorption and regeneration Furthermore, infrastructure questions must be equipment from the Kharaat ISR Pilot Plant was considered alongside questions related to assembled at Khairhan. The test was operated energy, transportation, water management and for about fourteen weeks and was terminated rural development. The work is being done to

56 Altankhuyag et al. Mongolian Geoscientist 49 (2019) 50-57 reflect these issues related to uranium extraction Budunov, A.A. 2006. Summary Report of in order to be comprehensively reflected in Results of Prospecting Work in the Gobi Deposit Development Agreement, Investment Region of Mongolia for 1994-1996. Agreement and other related legal documents of Ulaanbaatar. the company. Budunov, A.A., Jamsrandorj, G. 2012. Kharaat uranium deposit. Prospector 47, 76-81 (in CONCLUSIONS Mongolian). Mongolia is carrying out preparatory studies in Chadraabal, M., Manlaijav, G. 2017. Current order to commercialize radioactive minerals. As Status of uranium activities in Mongolia. The part of these studies, Mongolia is working to AusIMM International Uranium Conference. introduce legislations concerning extraction of Cuney, M. 2010. Evolution of uranium radioactive minerals to improve legal fractionation processes through time: driving environment and being consistent the best the secular variation of uranium deposit types. international practice. Economic Geology, 105, 449-465. https:// Thus, Mongolia is actively working to increase doi.org/10.2113/gsecongeo.105.3.553 uranium reserves, attract investment and begin Dahlkamp, F.J. 2009. Uranium deposits of the exploiting deposits with proven reserves and world, Asia. vol 4. Springer, Berlin. https:// also build trust between stakeholders. Through doi.org/10.1007/978-3-540-78558-3 the experiences over the past few years, the Hocquet, S. 2016. Zoovch Ovoo and Dulaan Uul uranium exploration entities are deemed as uranium deposits. Cogegobi LLC, IAEA- essential for the social licensing in areas in line UNECE Workshop, 16/08/2016, Ulaanbaatar. with the State policy. Jamsrandorj, G., Baatartsogt, B., Altankhuyag, In recent years, low cost uranium, especially D. 2016. Recent Discoveries and Resources of sandstone type, deposits have been discovered Uranium in Mongolia. Journal of East China in Mongolia, which is highly likely to attract University of Technology 39, 25-31. more international uranium exploration and Jamsrandorj, G., Dejidmaa, G., Ukhnaa, G. production companies. As a result, uranium 2015. Uranium: The geology, world overview production is expected to be commenced in the of mineral resources and mining. Ulaanbaatar near future. (in Mongolian). Mineral Resources and Petroleum Authority of REFERENCES Mongolia (MRPAM), 2017. The Annual Badamgarav, J., Badamgarav, D., Orolmaa, D., report 2016. Tomorkhuu, D., Narantsetseg, Ts., Mironov, Y.B. 2006. Uranium of Mongolia. Dembereldagva, Ts., Idermonkh, T. 2011. Center for Russian and Central EurAsian Map of the Mesozoic-Cenozoic tectonic Mineral Studies (CERCAMS), London 230 p. structures of Mongolia. Scale 1:1000000. (In Russian). Bruneton, P., Cuney, M. 2016. Geology of OECD(NEA)/IAEA. 2004. Uranium 2003: Uranium Deposits. In: Hore-Lacy I (ed) Resources, Production and Demand, OECD, Uranium for Nuclear Power, Resources, Paris, 186 p. Mining and Transformation to Fuel. Woodhead, London, 11-53. https:// doi.org/10.1016/B978-0-08-100307-7.00002-8

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