1
Uranium and Fluoride geochemical pathways in Ulaanbaatar and rural Mongolia Robin Grayson, Baatar Tumenbayar, Daramsenge Luvsanvandan and Amarsaikhan Lkhamsuren
blue sky of Mongolia
combustion of uraniferous coal photochemical smog blanketing the city
uraniferous ash settling over the city
uraniferous ash settling in lagoons
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Uranium and Fluoride geochemical pathways in Ulaanbaatar and rural Mongolia Robin Graysona1, Baatar Tumenbayarb, Daramsenge Luvsanvandanc and Amarsaikhan Lkhamsurend a
Independent consultant, Manchester, United Kingdom Sans Frontiere Progres NGO, Sukhbaatar district, Ulaanbaatar, Mongolia c Academician of National Academy of Science of Mongolia d Environmental consultant, Mongolia b
Abstract Explanation is sought for the high uranium levels in Ulaanbaatar’s ash dumps, groundwater, construction materials and vegetation, and the high radon level in the city’s drinking water. Combustion of uranium-bearing coals is a cause, but natural sources of uranium may also be factors. Mongolian coals are important sinks for elemental enrichment by uranium and other heavy metals, and 24 Mesozoic, Permian and Carboniferous coals have U-content above 1 g/tonne. Coal ash wastes are U-enriched due to depletion of volatiles and are candidates for economic extraction of uranium and other valuable metals. Uranium in water often exceeds WHO drinking water guidelines and chronic poisoning or fatality of aquatic crustaceans is probable. The uranium concentration in some ash dumps is sufficient to envisage economic recovery through in-situ leaching. While coals and ash are ‘U-sinks’, over 2,000 soda lakes and sodic soils are ‘U-drivers’ causing thousands of square kilometres of Mongolia to have elevated uranium levels, and the cause of elevated levels of fluoride, arsenic, selenium and other elements. Soda lakes and their remarkable ecosystems merit scientific study. The uranium concentration in some soda lakes is sufficient to envisage economic recovery by mining. Sulphate-reducing alkali extremophile bacteria are capable of reducing uranium (VI) to precipitate uranium (IV) oxide (UO2) as uraninite, while nitrate-reducing alkali extremophile bacteria can dissolve the uraninite into U (VI) solution. The soda lakes’ integrity depends on large-scale removal of calcium ions, sequestrated as hundreds of millions of tonnes of Cacarbonates locked on the undersides of gravel clasts. Calcium depletion permits leaching of fluorspar veins across vast regions, and the elevated fluoride levels of well waters causes thousands of rural children to suffer from endemic dental fluorosis. Blanket surveys for dental fluorosis are warranted in all fluorspar districts. Leaching of arsenic and mobilisation in sodic waters causes thousands of people to suffer from endemic arsenic poisoning. Environmental regulations should require coal projects to publish analyses of U, F, As, Se of coals, ash and leachates, and for all uranium projects to publish water analyses of wells in their watersheds.
1Corresponding author. Manchester, United Kingdom. E-mail address:
[email protected]
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1
Introduction
Until recently Mongolia had the world’s fastest growing economy with a 17.3% rise in GDP in 2011 driven by a mining boom (World Bank, 2012). Uranium mining may commence soon, exploiting conventional uranium resources amenable to low-cost open pit mining and in situ leaching. This review focuses on unconventional uranium resources, such as surface water, groundwater, soil, coal, ash and vegetation. None are current exploration targets but this may change suddenly if new technology cuts extraction costs. Uranium is more widespread in Mongolia than hitherto realised, and this study organises fragmentary data in to predictive geochemical models able to give insight into exploration, mining, environment and health. In doing so, the study sheds light on dental fluorosis being endemic in Gobi communities, and on radon emanation in the capital city. Priorities are to explain elevated uranium levels in Ulaanbaatar’s groundwater, coal supplies, construction materials and vegetation; the high levels of radon in Ulaanbaatar’s tapwater, and the high uranium levels in some springs and soda lakes.
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Mongolia’s uranium industry
2.1
Soviet investment
In Soviet times, Mongolia enjoyed a boom in mineral exploration and mining. The boom collapsed with the fall of the Soviet system and many mines closed half-finished. Mongolia deindustrialised more completely than any other nation (Reinhert, 2003). Total economic collapse was averted by exports from two mines of strategic interest to Russia: copper/molybdenum concentrates from Erdenet and fluorspar concentrates from Bor Undor. Sufficient coal mines remained open to maintain the electricity grid and district heating essential to Ulaanbaatar – the world’s coldest capital city, the average annual mean temperature being-0.9°C and winter temperatures being often as low as 25-38°C (Batima, 2003).
2.2
Subsequent revival
Deprived of Russian roubles and markets, the Mongolian uranium industry closed. To avert national collapse, the gold industry was liberalised by the Government’s Gold Program. Gold output soared when the vast archive of Soviet placer gold drilling became open-file and licences became available and cheap. Over 130 placer gold companies produced 11 tonnes of gold a year and spun out over 1,000 enterprises across all sectors (Grayson and Tumenbayar, 2005). Meanwhile the uranium industry disintegrated and largely disappeared. Its archives of oncesecret reports were now public but aroused scant interest due to the low uranium price. Meanwhile Soviet reports on coal, oil, copper, molybdenum, iron ore, titanium sands, tin, zinc, fluorspar and phosphates triggered boom after boom across commodity after commodity. Inward investment soared and mineral exports climbed to record levels. Informal mining boomed, notably artisanal gold mining employing over 100,000 people (Grayson, 2007). In spite of 40 years’ effort, uranium contributes nothing to the Mongolian export trade having become a strategic asset mired in state intervention, leading to disputes and uncertainty eroding investor confidence and delaying investment.
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2.3
Vision of nuclear power
Mongolian GDP will rise further, fuelled by the world-class Oyu Tolgoi copper mine; followed by the huge Tavan Tolgoi coal mine. These will boost Government finances enabling the State policy for nuclear power to be part of Mongolia’s mix of energy self-sufficiency. Already a 300-500 kW TRIGA nuclear research reactor with 1012−13 n/cm2 s neutron flux has been selected for use “in various studies and for educational and training purposes” (Sambuu et al., 2011). The second reactor is planned to be a modular nuclear reactor to supply district heating in Ulaanbaatar. A joint design study has been completed by the Nuclear Research Centre of the National University of Mongolia and the Research Laboratory for Nuclear Reactors of the Tokyo Institute of Technology (Sambuu and Obaraa, 2012). The chosen design is a high temperature gas-cooled reactor (HTGR) with passive safety features for long core life. The reactor core is 8 metres wide and 8 metres tall, and will generate 330 MWth of power. Ulaanbaatar’s district heating is supplied by superheated steam from city-based combined heat and power plants CHP #2, 3 and 4, with CHP #5 being planned (HJI and MonEnergy Consult, 2011). All burn unwashed low quality brown coal, contributing to very poor air quality in winter (World Bank, 2012).But two-thirds of the city residents lack district heating, living in ‘ger districts’ and burn coal, wood, paper, card, plastic, tyres and waste oil. This, plus emissions from CHP #2, 3 and 4, make Ulaanbaatar the world’s most polluted capital city in winter (World Bank, 2011).The outdoor air pollution was estimated by Allen et al. (2011) to cause early deaths of 623 residents a year; a figure higher than the deaths due to suicides, murders and transport accidents. Accordingly a strong case can be made for nuclear power to replace coal for district heating. Released from its district heating role, coal can be burned at distant mine sites to generate electricity for the ‘clean air’ Ulaanbaatar. Other benefits include cutting coal trains so freeing rail slots for mineral exports; cutting industrial consumption of groundwater that is Ulaanbaatar’s only source of water; and eliminating ash that is a serious health risk contributing not only to city air pollution but also to indoor radon pollution from ash used in construction materials. However, a wider role for nuclear energy is difficult to justify, albeit offering clean energy with minimal greenhouse gas emissions. Mongolia has enormous resources of coal, oil, solar and wind energy. Wind energy alone is sufficient to meet 40% of China's energy demand by 2030 (Borgford-Parnel, 2011) and Inner Mongolia is already a world leader in wind energy, so expanding the ‘wind grid’ into Mongolia would allow Mongolia to become net carbon neutral while exporting electricity to China.
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3
Conventional uranium resources
3.1
Distribution of conventional uranium resources
Mongolia has significant conventional uranium resources, mostly in the south, south-east and east. None are reported from the western regions (Fig.1).
Figure1 Regional interpretation of conventional uranium resources, adapted from a recent summary by Tserenpurev and Manlaijav (2011).
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3.2
Conventional uranium deposits and occurrences documented by Soviets
Soviet geologists discovered 77 uranium localities and ranked 70 as ‘occurrences’ and 7 as ‘deposits’, of which 52 were subject to intense scrutiny and awarded ‘passports’. The Soviet archives are public (Dejidmaa et al., 2001) and are the culmination of uranium exploration efforts that at 2012 prices would cost several billion US dollars (Tables 1 and 2). Table 1
Passport
Reference
Map
11 13 K49 14 23 27 32 312 479 559 200 219 267 275 275 299 L49 310 317 353 405 408 409 420 446 447 448 M46 360
Sedimentary and stratiform uranium deposits and occurrences in State Geofund.
P P P P P P P P P P P P P P P P P P P P P
M50 98 P 82 83 M47 195 196 198
P P P P
CONVENTIONAL URANIUM DEPOSITS AND OCCURENCES Sedimentary and Stratiform name
Dejidmaa et al. (2001)
latitude longitude
major commodity
status
Sandstone-hosted Uranium 43 50 00 108 58 00 U 43 46 00 108 58 00 U 43 44 00 108 55 00 U 43 47 00 109 02 00 U 43 31 00 109 28 00 U 43 08 00 108 30 00 U occurrence 47 09 25 107 56 50 U 44 50 40 102 00 38 U-Th 44 22 21 102 01 33 U-Th 46 57 00 112 56 00 U 46 13 00 108 32 00 U 46 37 00 111 55 00 U 46 24 00 111 36 00 U Deposit 46 24 00 111 36 00 U 45 50 00 108 29 00 U occurrence 45 44 10 108 31 30 U 45 38 10 108 21 30 U deposit 45 32 42 109 07 80 U occurrence 44 48 00 109 26 00 U 44 55 00 110 33 00 U deposit 44 53 00 110 19 00 U 44 59 20 111 07 20 U 44 15 00 109 36 00 U occurrence 44 14 00 109 51 00 U 44 04 00 109 45 00 U 48 36 00 92 17 00 U Sediment-hosted Uranium Shinebulag 48 44 00 114 10 00 U occurrence Sedimentary Stratiform Uranium-Vanadium Mongosh 50 37 00 99 24 00 V Tsohyn 50 36 00 99 19 00 V Khitagiin Gol 18 49 49 00 99 50 00 V occurrence Thahiruul 21 49 46 20 99 53 25 V Buyant 83 49 44 00 99 47 00 V Elgen Khad Ail Gulon Taj Noyon Naidal 703 Osh Nuur Oin Gol Ikh Bulag Shivee Ovoo Shand Bulag Olziit Olziit Ereen-1 Anomaly 12 Kharaat Khavtsal Yant Narst Narst Dorvoljin Tolgoi 513 Baruun Dulaan Khar occurrence 777
minor commodity P P V, Mo, Ce V, Mo, Ce V, La, Ge P Cu, As U, Mo U, P U
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Table 2
Igneous-hosted uranium deposits and occurrences in State Geofund.
Reference
Passport P P P P P P P P P P P P P
165 166 167 168 459 460 177 74 76 134
P P P P P P P
99 M46 250 251 85 96 M47 98 104 133 M48 125
P P P P P -
Map
480 523 582 88 144 151 222 233 239 239 342 354 33 185 298 304 72 73 81 82 84 88 89 92 97
L48
L49
L50 M49
M50
L48
L49 L50 M46 M48
M48 124 -
CONVENTIONAL URANIUM DEPOSITS AND OCCURENCES Igneous Hosted name
Dejidmaa et al. (2001)
latitude longitude
major commodity
status
Volcanic-hosted Uranium 38 102 00 05 U-Th 00 106 54 00 U 00 104 08 30 U 00 111 34 00 U occurrence 20 108 00 00 U 00 109 50 00 U 00 108 45 00 U 00 109 24 00 U 00 109 50 00 U deposit 00 109 50 00 U 00 109 02 00 U occurrence 00 109 30 00 U 00 115 12 00 U 00 113 56 00 U deposit 00 111 53 00 U occurrence 00 111 32 00 U 00 114 25 30 U deposit 00 114 29 00 U 00 114 19 00 U 00 114 15 00 U 00 114 03 22 U 00 114 13 00 U occurrence 00 114 22 00 U 00 114 02 00 U 00 114 23 00 U Granitoid-related Uranium Elst 1308 47 42 00 107 37 00 U Arshaan 1309 47 40 00 107 36 00 U Tamga 376 47 39 00 107 41 00 U Urt 376 47 39 00 107 37 00 U Khavirga Khudag-I 45 58 00 107 44 00 U-Th occurrence Khavirga Khudag-II 45 56 00 107 45 00 U-Th Baruuntsogt 46 44 00 111 44 00 U Tsagaanuul 46 02 35 115 56 12 U, Mo Goojuur 244 49 26 30 91 16 02 U Tsushiin Gol 49 46 00 104 39 00 U Th(U)-Nb-Zr(REE) alkaline metasomatites Khashaatyn Khar 49 31 02 92 35 36 Zr Occurrence A-681 48 53 00 94 57 00 Nb Occurrence A-683 48 52 00 94 48 00 Nb Ar Gol 50 28 20 99 53 55 Th, Nb, Zr T Ujig Gol 50 15 40 99 46 43 Th, Nb, occurrence Khagiin Nuur 50 16 00 99 37 00 Th, Nb, Zr Alag Ergene 50 05 00 99 54 10 U Yarhis Gol 50 16 50 100 23 30 U, Th, Zr Bayangol 2201/2/3 49 30 36 103 39 36 U-Th Ta-Nb-(REE) pegmatite Bayangol 415 49 31 00 103 35 25 Ta, Nb REE occurrence
Olziit Khashaat Teeg Uul Tanai 201-203 Narangiin Bulag Moron Khar Tolgoi Borondor Ikh Khet Deposit Ikh Khet Occur. Khongor-2 Ulaan Nuur unnamed 38 Gurvanbulag Mizornoe Ikh Bulag Dornod-1 (Mardai) Dornod-2 (Mardai) Ilreh Tsever Davaa unnamed Khar unnamed Delger Nuur
44 45 44 47 47 47 46 46 46 46 45 45 46 49 48 48 49 49 49 49 49 49 49 49 48
45 06 16 57 04 09 04 18 13 13 48 32 52 02 16 04 10 08 08 07 04 05 04 00 51
minor commodity Sr, Mo, P Pb Mo Pb, Zn Nb, Th Zr, Th Ta, Th R, U Zr TR, U TR, U Nb, Mo Zr, U, Th
Post-Soviet uranium exploration and development efforts have focussed on confirming and expanding Soviet-discovered localities and redefining Soviet-estimated resources into western categories. Stock markets now ensure release of drilling results and NI-43-10 reports, but reports submitted by unlisted private companies and state-controlled uranium companies, such as AREVA of France, have not been released by the Government.
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3.3
Conventional uranium deposits ready to mine
Conventional uranium deposits are monographed by Dahlkamp (2009). Mongolia ranks 15th in the world with 37,500 tonnes of uranium in Reasonably Assured Resources plus 11,800 tonnes of Inferred Resources (OECD/IAEA, 2010). All of these resources are in volcanic and sandstone-hosted uranium deposits that are amenable to low-cost open pit mining and in situ leaching (Table 3). Table 3 Conventional resources of uranium in Mongolia ready for mining. Adapted from WISE (2011) and WNA (2012). Resources NI-43-10 compliant measured indicated inferred
deposit
GurvanSaihan
Hairhan
sandstone
yes
GurvanSaihan
Haarat
sandstone
yes
Gurvanbulag Gurvanbulag Saddle Hills Central Project Mardai Dornogobi aimag TOTALS:
Dornod-Uran
Host rock
Reserves
area
volcanic
proven
probable
1,538 t U 5,346 t U 0.17% U 0.13% U
volcanic
yes yes
Dulaan Uul sandstone
7,612 t U 0.062% U
1,577 t U
5,308 t U
2,236 t U 0.040% U 2,461 t U 0.023% U 846 t U
0.21% U
0.15% U
0.11% U
24,731 t U 0.10% U
923 t U 0.042% U 9,888 t U 0.017% U 16,354 t U
? 1,538 t U 5,346 t U
1,557 t U 25,651 t U
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4
Unconventional uranium resources – coal and coal ash
Unconventional uranium resources, such as uraniferous coal, uraniferous ash, construction materials, soils, soda lakes, groundwater, surface waters, vegetation, and air, are widespread in Mongolia. These resources are sub-economic but this could change if the world uranium price rises sufficient to warrant attention by mining companies and justify research in extraction technology.
4.1
Uraniferous coals
Trace amounts of uranium are found in coals worldwide. However there is no global consensus about what level of uranium justifies labelling a particular coal as “uraniferous”. To put the issue in context, it has been suggested by the International Atomic Energy Authority that: "It is evident that even at 1 part per million (ppm) U in coal, there is more energy in the contained uranium (if it were to be used in a fast neutron reactor) than in the coal itself. If coal had 25 ppm uranium and that uranium was used simply in a conventional reactor, it would yield half as much thermal energy as the coal.”(IAEA, 2003). For consistency within Mongolia we arbitrarily define “uraniferous coals” as coals having a minimum uranium content of 1 ppm (1 gram U per tonne), and “uraniferous ash” as ash having a minimum uranium content of 5 ppm (5 gram U per tonne). Mongolia’s U-bearing coals are considered by Arbuzov et al. (2011) to be part of a vast tract of U-bearing coals extending across northern Asia. They attribute the presence of uranium and thorium to active volcanism contemporaneous with peat accumulation, and report that the U content of more than 5,000 coal samples range from 0.6 to 32.8 ppm. However the uranium content of some Mongolian uraniferous coals locally exceeds 1,000 ppm (Gow and Pool, 2007). Many coals of north-central Mongolia are exceptionally radioactive, and Dejidmaa et al. (2001) listed 15 uraniferous coals in Soviet archives in the Mongolian State Geofund. Dugarjav (2005) and Luvsanvandan (2012 MS) listed a further 9 uraniferous coals. It is likely that the total number will be much higher (Table 4).
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Table 4
Unconventional uranium resources Mongolian coals and coal ash.
name
702 P Nalaikh L48 825 P Tevshiin Govi 937 - Talyn Bulag 131 P Sharyn Gol 459 P Baganuur 482 584 L49 586 601 627 630 653 654 120 122 147 L50 151 164
latitude longitude 47 45 45 46
minor commodity
status
Uraniferous Jurassic-Cretaceous Coals 50 107 17 0 Brown Coal 59 105 59 59 Brown Coal 00 106 6 00 Brown Coal 10 108 27 34 Brown Coal deposit
44 59 43 10
47 44 00 108 23 00 Brown Coal
47 Chandgana 46 Shivee Ovoo Nogoon Toirom 46 46 Alag Togoo 46 Uelziit Khalzan Ovoo 46 Ereen Soum-1 45 Ereen Soum-2 45 47 Bayan Us 47 Us Nuur 47 Arjar Oelziit 46 Hoeot 46 Zuen Bulag Nuur Hooronduin 166 P 46 Heseg M46 447 P Khar tarvagatai 49 M50 207 P Aduunchuluun 48 P P P P P P P P P P P P P
major commodity
23 10 06 10 24 15 51 51 50 47 13 58 57
15 10 00 30 00 00 00 00 30 00 00 00 00
110 108 108 109 111 111 108 108 115 115 114 114 115
01 27 38 02 36 24 29 31 35 33 46 30 17
00 34 00 20 00 00 00 00 30 00 00 00 30
U U
Brown Coal Brown Coal Brown Coal occurrence Brown Coal deposit Brown Coal Brown Coal Brown Coal Brown Coal occurrence Brown Coal Brown Coal Brown Coal Brown Coal deposit Brown Coal
U U U U U U U U U U U
52 00 115 32 00 Brown Coal occurrence
U
32 48 91 40 45 Black Coal 08 06 114 31 30 Brown Coal
deposit deposit Uraniferous Permian Coals
K48 116 P Tavan Tolgoi
43 37 00 105 28 30 Black Coal
L46 430 P Olonbulag L47 429 P Bayanteeg
Uraniferous Carboniferous Coals 45 10 00 91 18 00 Black Coal deposit 45 42 00 101 34 00 Black Coal
deposit
Coal Ash
1 g/t U 7 g/t U 1 g/t U 5 g/t U 4 g/t U 20 g/t U 3 g/t U 22 g/t U 7 g/t U 29 g/t U 4.1 g/t U 22 g/t U 7,000 analyses of USA coals (Kolker et al. 2005) and imply several thousand tonnes of arsenic contaminate the capital city in ash waste. While leaching of arsenic from coals is facilitated by weathering, oxidation and hydrolysis, once released then sodic groundwater and soda lakes may play an important role. This is suggested by the highest arsenic levels being reported from wells in regions with soda lakes and sodic soils over coal basins. The WHO guidelines for arsenic in drinking water (0.01 mg/L) are exceeded in wells in Govi-Sumber (x 3), Dornogovi (x 2.4) Dornod and Govi-Altai (x 1.8) and Sukhbaatar (x 1.7), with the peak values reported for Khatanbulag soum in Dornogovi (x 7.5). These districts are characterised by Mesozoic coal basins, sodic soils and soda lakes. The National Arsenic Survey (WHO, 2005) confirmed arsenic poisoning being endemic in areas with elevated As levels in well water, with symptoms displayed by 82.4% of the people surveyed. It is evident that the arsenic poisoning affects several thousand people in the Gobi regions. Tukh Lake in the Darhad valley of Huvsgol Aimag has the highest known arsenic levels for a Mongolian soda lake. Arsenic levels of 0.5 to 2.4 mg/L, 50 to 240 times the WHO drinking water guidelines, were revealed in analyses by Hamamura et al. (2012) of 1:1 evaporate:water extracts, together with selenium levels of 2 mg/L that are 50 times above the WHO guidelines. Herders visit Tukh Lake to harvest the “hujir” (salt evaporates) to make tea, consumed daily. Barber et al. (2009) investigated the chemical constituents of hujir consumed by families near Tukh Lake and found soluble arsenic concentrations ranging from
