A.V. Boitsova, A.V. Komarovb, A.L. Nikolskyb
a JSC-TVEL, Moscow, Russian Federation
b All–Russian Research Institute of Chemical Technology Moscow, Russian Federation
Abstract. Two Uranium Production Centres were in operation in Russia. Priargun Mining–Chemical Production Association (PPGHO) is active and Lermontov State Enterprise “Almaz” is closed. PPGHO is the operator of Streltsovsk Uranium–ore district, which include 19 deposits of volcanic type. Mining was operated since 1968 by two open pits (both are depleted) and five underground mines and ore processing since 1974 at the local milling plant. Since 90th low-grade ores are being processed by heap leaching. The contaminated area cover 842 ha.
Main sources of the environmental pollution are the tail ponds of processing and sulphuric acid plants. The principal environmental problem is increasing accumulation of liquid and solid radioactive wastes. “Almaz” was the operator of two small vein-type uranium deposits by two underground mines since 1950 till 1990. Ore bulk was processed from 1954 at the domestic milling plant and from 1965 to 1989 also by in place leaching and heap leaching. The area of radioactive contamination covers 134 ha: 79.7 ha of milling tail pond and 54.4 ha of mining waste rock dumps. Main source of environmental contamination is radon-222 exhalation from the tail pond.
1. Introduction
Uranium production in the former Soviet Union was a strategic task. Economic and environmental aspects were of minor importance. As a result low-grade and small-size deposits were developed too and high production capacities were kept for a long time.
Financial reserves for decommissioning and rehabilitation activities had not been put in place.
Two Uranium Production Centres has been in operation in Russia:
- Priargun Mining-Chemical Production Association (PPGHO) is active and - Lermontov State Enterprise “Almaz” is closed.
Their total output since 1954 is about 110 000 mt U [1]. A large amount of radioactive wastes has been accumulated on both facilities.
2. JSK “Priargun mining-chemical production association” (PPGHO) 2.1. Site characterization
State JSK “Priargun Mining-Chemical Production Association” (PPGHO) is the only active uranium production centre in Russia in last decade. It is located in Chita region of Russia, 10-20 km from the town of Krasnokamensk with about 60 000 population. Mining has been operated since 1968 by two open pits (both are depleted) and five underground mines: 3 are active (mine 1,2,4) and 2 stand by (mine 7,8) (Fig. 1). Milling and processing has been carried out since 1974 at the local hydrometallurgical plant by sulphuric acid leaching with subsequent recovery by sorption-extraction ion exchange scheme. Since, 90th some amount of low-grade ores is being processed by heap and in-place (in-stope) leaching. Total U production amounted more than 110 000t [1].
FIG. 1. Operating units of Priargun Association.
The production is based on 19 volcanic–type deposits of Streltsovsk U–ore region with the average U grade about 0.2%, situated at the area 150 km2 (Table 1): 17 deposits are situated in volcanic rocks and sediments (13 of them are in effusives of sheet facies and 4 in effusives of neck facies) and 2 large deposits occur in basement rocks (Antei in granite and Argunskoye in granite and marble). Geological setting of deposits is described in many publications [2, 3, 4].
Since the beginning of uranium mining in 1970 ten deposits have been brought into production and two of them (Tulukui and Krasny Kamen) have been depleted by open pit operation. Most deposits have been explored underground and stand by for future development.
2.2. Production capability
The annual production at Priargunsky in 1996–1998 amounted 2500 to 2600 t U. Dominant production comes from underground mining and conventional milling. Currently relatively high-grade ore (over 0.3%U) of deposit Antei in granite (mine 1) is the main mining object.
Insufficient amount is produced from the low-grade ores by heap leaching and in place (or block) leaching methods.
The main criteria for determination of processing method is the ore grade. Radiometric sorting is used to separate mined ore. Ore with grades over 0.3% U is crushed and processed at the plant. Mined ore with grades 0.15 to 0.30 is placed in the surface heaps containing 1 to 2 mln/t each. The project heap leaching recovery is 70 to 80% of in–place metal. Underground block leaching is designed for low–grade ore (0.1 to 0.15% U) [3].
The RAR resources of about 140 000 [1] can satisfy the planned requirements for the next 50 years. However low world uranium prices force to mine relatively high–grade ores with
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0.28% U. This makes rest resources with low–grade ores unfavorable for current conventional mining. Nevertheless Priargunsky Association, even with its declining ore grades and high costs, will continue to be the cornerstone of Russia’s uranium industry. The annual production is planned to reach 3500 t U, equally divided between conventional milling and leaching methods (heap leaching and underground block leaching).
Table I. Uranium deposits of Streltsovsk district
Deposit Resources Operational status Host rocks Shape of orebodies 1. Streltsovskoye Large Active – UG mine 1 Dacite, basalt,
felsite,
Stockwork, vein 2. Tulukuevskoye Large Depleted – open pit
3. Shirondukuevskoye Middle Stand by – UG mine 7 4. Yubileinoye Middle 10. Malo-Tulukuevskoye Middle Stand by – UG mine 8
11. Antei Large Active – UG mine 1 Granite (basement)
12. Argunskoye Large Marble, granite
13. Zherlovoye Small 14. Krasnyi Kamen Small 15. Pyatiletneye Small
Explored – UG mine 6
Depleted – Open pit Effusives of neck facies
* Resources of deposits: Large >15.000t., middle 5.000-15.000t., small <5.000t.
2.3. Environmental situation
The main source of the ground water pollution is the seepage from the tail ponds of hydrometallurgical and sulphuric acid plants. Their total volume is 300 mln.cub.m. and 9000 Ci radioactivity. The characteristics of wastes is presented in Table 2.
Table II. Characteristics of wastes
Type of waste Area, ha Ml. ton U, % Radioactivity The aggregated area of radioactive contamination is 842 ha: 723 ha at industrial site with the level 60 to 240mR/hr and the rest 119 ha in the sanitary protection and observation zones with the level to 60mR/hr [5].
More than 20-year environmental assessment emphasis two main environmental problems:
— Increasing accumulation of liquid and solid radioactive wastes;
— Progressive radioactive contamination of natural hydrogeological systems, which creates potential threat to portable water supply.
2.4. Waste management
Tailing pond is considered as most dangerous unit, regarding large amounts of radioactive wastes and sections overfilling. The potential threat of dam accident with wastes seepage to Urulungui and Argun rivers exists at the milling tail pond. The project of milling and acid tail ponds reconstruction is in progress. It includes:
— Strengthening of dam bodies and building of protective dam around the portable water bore holes;
— Construction of intercepting wells below the tailing pond dam;
— Designing the system of hydrogeological monitoring in the special wells.
However, the construction of special plant for liquid wastes treatment is considered as the most effective way.
Mining waters has been discharged into Bambakai valley over 20 years. The effluent has been stopped in 1996, when mine water restoration plant based on zeolite sorption technology has been built.
Tulukui and Krasny Kamen open pits are the first two depleted deposits of Streltsovsk region.
The project of their closure is adopted.
Environmental activities, including rehabilitation of the territories and wastes utilization will be realized in the whole volume as far as the utilities closure will take place.
3. Lermontov State Enterprise “Almaz”
3.1. Site characterization
The first organization responsible for uranium production was the Lermontov Complex, presently - Lermontov State Enterprise “Almaz”. “Almaz” is located 1.5 km from the town Lermontov, Stavropolsky region of Russia. The region included Beshtau and Byk vein–type uranium deposits with total uranium resources 5 300 tones and 0.1% U grade. They have been operated by two underground mines since 1950. Mine 1 (Beshtau) was closed in 1975 and mine 2 (Byk) in 1990. Ore bulk was processed since 1954 at the processing plant by sulphuric acid leaching, and from 1965 to 1989 also by in-place (in-stope) leaching and by heap leaching. From the 80th till 1991 U ore bulk from Ukraine and Kazakhstan has been also processed at “Almaz”. After 1991 U production has been stopped, apatite flotation concentrate is being processed at the plant for fertilizer production. The uranium production totalled 5 685 tonnes, with 3930 tonnes extracted by underground mining and 1755 tonnes using ISL technology.
3.2. Environmental situation
The area of radioactive contamination covers 134 ha, including 79.7ha of milling tail pond 54.4ha of mining waste rock dumps (Table 3) [5, 7].
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Table III. Measurement of radioactive contamination
Wastes Area, ha Amount, ths. t Alfa activity, Ci Beta activity, Ci
Tailing pond 79.7 14 047* 26 998 18 624
Waste mine 1 (Beshtau) 36.0 4 425 1 353 2 343
Waste mine 2 (Byk) 18.4 3 961 830 586
Total 134.1 22 433 --- ---
* Plus 5900t of toxic substances and 5300 t of fluor gypsum.
The main source of environmental contamination is radon-222 exhalation from the tail pond.
The contamination of ground water took place due to milling waters drainage from the tailing pond, especially at the first years of milling plant operation. Currently the quality of groundwater satisfies the standard.
3.3. Waste management and rehabilitation
Mine 1 (deposit Beshtau). The partial rehabilitation of waste dumps has been carried out at 1993-1994. The equipment for mining mater restoration was installed in 1993, but currently it is not in operation (mining waters contain to 2.2mg/l U).
Mine 2 (deposit Byk). The works on waste rocks rehabilitation are executed for about 30%.
The rehabilitation of heaps after heap leaching is completed.
Milling plant.The partial decontamination and dismantling of buildings and territories, which are used now for apatite processing, has been carried out.
Tailing pond. The project on rehabilitation and decommissioning of milling tails pond is at the state examination. The main tasks of this project are:
— Organization of the special environmental service;
— Arranging 1.5m thick layer of phosphogypsum and the following soil drainage layer;
— Reconstruction and extension of monitoring system;
— Designing the system of storm water diversion.
4. Future production centres
Three new ISL production centre are planned to come into operation in the next 10 years [1].
The environmental assessment of deposits amenable for ISL is based on two main principles:
— Deposit location within the closed hydrogeological structures;
— Isolation of leaching area from the water supply utilities.
5. Conclusion
The general environmental characteristic of Russian uranium producing facilities can be regarded as typical for the countries of the former Soviet Union. The world experience shows that environmental costs of decommissioning and rehabilitation activities after closure are much higher than during operation (UMTRA in USA and Wismut in Germany) [6]. The environmental costs should be included in the initial cost calculation and adjusted continuously during production. This is as a subject for international co-operation, especially regarding the plans for future uranium production and new centres development.
REFERENCES
[1] Redbook 1997, Uranium Resources, production and demand, Joint IAEA and OECD/NEA Publication, Paris, (1998).
[2] McMURRAY, J.M. Abn in depth analysis of the former Soviet Union and Mongolian uranium production industries, NAC International, July (1997).
[3] ISCHUKOVA, L.P., The Streltsovskoye uranium district, IAEA Technical Committee Meeting in Kiev, IAEA-TECDOC-961, May (1995) p.237–251.
[4] BOITSOV, A.V., NIKOLSKY, A.L., Characteristics of uranium deposits in Russia, IAEA Technical Committee Meeting, Vienna, June (1997).
[5] KOMAROV, A.V., R&D needs of chemical separation technologies for nuclear wastes from the perspective of federal programmes of Russia. Chemical Separation Technologies and Related Methods of Nuclear Waste Management, Kluwer Academic Publishers, (1999).
[6] Kosten der Stillegung und Sanierung von Urangewinnungsprojecten im internationalen Vergleich, Einflußgroßen und Abhängigkeiten, BMWI No. 90, März (1995).
[7] KOMAROV, A., SEREBRIAKOV, I., SHATALOV, V., ZEMLIANUHIN, V., Recovering the territory of former uranium enterprises, ICEM 99, Nagoya, Japan, (1999).
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