URANIUM MINING AND REHABILITATION: INTERNATIONAL ASPECTS AND EXAMPLES FROM GERMANY

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1 URANIUM MINING AND REHABILITATION: INTERNATIONAL ASPECTS AND EXAMPLES FROM GERMANY XA9745 F.H. BARTHEL Bundesanstalt fur Geowissenschaften und Rohstoffe, Hannover D. MAGER Federal Ministry of Economics, Bonn Germany Abstract In the period from 945 to 994 about.87 million t U have been produced worldwide. The maximum of production reached about 7 t U in 98, now the production has fallen to about 2 t U. Due to the decrease of the annual output, employment in uranium production has decreased, however the productivity has been increased in most countries. As any mining, uranium mining has an impact on the environment. Especially the radioactivity of the ores and waste material may create radiological hazards to the population when protection measures are not observed carefully. The impact of uranium production to the environmental is illustrated by various examples. The costs which are necessary to decommission and rehabilitate uranium production facilities can reach high levels depending on the specifics of the recultivation activities. International examples are given. The production of uranium in Eastern Germany is described briefly, and the reclamation activities of the former Wismut mining and milling facilities is illustrated by selected examples.. INTRODUCTION Uranium has been produced during the past 5 years for both military and civil uses. Part of this production, which was higher than the demand, was stockpiled for strategic reasons. After the fall of the iron curtain, most of the stockpile has been made available for commercial use. Thus, less uranium is now required from production and producers are being forced to reduce their output or close their mines. Production has fallen below demand since the mid-98s. The closure of uranium mines and mills requires proper decommissioning and rehabilitation according to international radiation protection guidelines and standards and to national regulations. Aspects of past and present uranium production are described in this paper, followed by examples of decommissioning and rehabilitation projects. It is not intended to deal with specific methods or regulations in individual countries; however, the example from Germany may illustrate the extent of decommissioning and rehabilitation work necessary in densely populated areas of Central Europe. 2. PAST AND PRESENT URANIUM PRODUCTION World uranium production during the period from 945 to 994 is estimated to have been about t U or about 4.7 billion pounds U O 8. At an arbitrarily chosen sales value of US$2/lb U O 8 this would amount to approximately $ billion. It should be kept in mind however, that the uranium price in WOCA (World Outside Centrally Planned Economy Areas) countries was higher over extensive periods, meaning this value may represent the lower limit. A breakdown of the estimated production of the different producer countries from 945 to 994 is given in Table I. Production figures for WOCA countries (total 8 t U) are fairly well known through the regular questionnaires on uranium resources and production (Red Book). 2

2 TABLE I. RANKING OF URANIUM PRODUCING COUNTRIES (OVER t U CUMULATIVE PRODUCTION ) (Figures rounded to the nearest t U) Country World tu % (har* Country WOCA tu % share Country NonWOCA tu % shore USA Canada GDR** Rep.S.Africa Czech Rep. 42,2 274, 26, 48,6 4, i USA Canada Rep.S.Africa France Niger 42,2 274, 48,6 7, 62, GDR** Czech Rep. Russ.Fed. Kazakhstan PR China 26, 4,,* 86,* 79,* *.*.* e Russ.Fed.,* 5.5* 6 Australia 57, Uzbekistan 7,5* 9.* 7 a Kazakhstan PR China 86,* 79,* 4.6* 4.2* 7 8 Namibia Gabon 56,7 24, Ukraine Bulgaria 46,8* 2,* 6.* 2.9* 9 France Uzbekistan Niger 7, 7,5* 62,6.8.8*.4 9 Zaire others (4 countries) 2, 2, Tajikistan Hungary Romania 2,* 7,5 7, 2.6* Australia Namibia 57,9 56,7.. 2 others (2 countries),8*,2* 4 Ukraine 46,8* 2.5* 5 Gabon 24, Zaire Bulgaria 2, 2,*..2* IS Tajikistan 2,*.* 9 2 Hungary Romania 7,5 7,.. 2 others (6 countries) 2,5. 58% of world total 42% of world total total,868,2 total,8, total 785,2* * estimated production; ** production production is estimated BGR,March 995

3 TABLE II. RANKING OF URANIUM PRODUCING COUNTRIES IN 99 Country tu % share cumulative g Canada Niger Russ.Fed. Uzbekistan Australia Kazakhstan France Rep.S.Africa Namibia USA PR China Czech Rep. Gabon Ukraine Hungary Spain India Argentina Romania Germany Mongolia Bulgaria Belgium Portugal Brazil Pakistan total 9,78 2,gi4 2,6* 2,6* 2,256 2,,74,7,668,78,* * 8 8 8* 2 2* 6 * 6* 4 2 * * 2, * 8.* * * 2.2 <. <.* <. <.* <. <.* <.* <. <. <.* <.* estimated BGR.March 995 TABLE III. MAJOR URANIUM PRODUCING COMPANIES 99 Company Production 99 tu % - share of production CAMECO.Canada COGEMA.France 42. (production in France, Canada.USA Niger.Gabon) Uranen.Germany (production m Canada,USA) 4 Priargunsky (Russ.Fed.) 26* 8. 5 Navoi,Uzbekistan 26* 8. 6 KATE P. Kazakhstan 2 7 Rossing,Namibia NUFCOR,Rep.S.-Africa ERA,Australia.5 WMC.Australia World total 2. * estimated BGR.March

4 Official production data for the non-woca area have been provided by only four countries. Production could only be estimated for the remaining countries, mainly CIS and PR China as major producers. Total non-woca production was estimated to be about t U. Production for 99 of about 2, t U (see Table II) was less than half of the estimated peak production in 98. At an average price of $2/lb U O 8 the 99 production represents a sales value of approximately $.7 billion. As shown in Table II, ten major producing countries account for nearly 9% of the production. The leading producer country is Canada, with a share of 28%. The four producers of the CIS have a share of 25 %. For some countries, e.g. Niger, sales revenue from exported uranium is a major source of income. In 989 the value of exported uranium from African countries, excluding the Republic of South Africa, amounted to $5 million or about 7% of the value of all exported minerals. Most producing countries are major uranium consumers. Other main producers, e.g. Australia, Kazakhstan, Namibia, Niger and Uzbekistan, have no domestic demand, and their entire production is exported. The share of uranium production by company is shown in Table III. Ten companies accounted for more than three fourths of the 99 production. The share of the top four producers was almost 5%. Estimated production from companies of the CIS amounted to 2%.. EMPLOYMENT IN THE URANIUM PRODUCTION INDUSTRY The number of persons employed varies from country to country, depending on the number and size of the individual uranium operations. A world-wide survey of employment in uranium mines and processing plants for the past is not yet available. In some countries, however, it was very high. Figures from 5 selected countries show that employment decreased continuously over the past 5 years. In 985, for example, about 85 persons were employed in these countries, in 99 only 55 and in 99 about 2 persons. The downward trend can best be illustrated by comparing employment and production in two of the major producing countries, USA and Canada, as shown in the following compilation USA Production (t U) Employment t U per man-year CANADA Production (t U) Employment t U per man-year For comparison, employment by the Wismut company amounted to about 4 persons during the 98s, now (994), 4 6 persons are employed in the decommissioning activities. 26

5 Efficiency in uranium production in the USA and in Canada has increased remarkably, from around t U per man-year in 98 to.7 and 7 t U per man-year, respectively, in 99. For other countries the trend to higher efficiency can be observed too, but not to the same degree. 4. THE IMPACT OF URANIUM MINING ON THE ENVIRONMENT Like mining and processing of other minerals, uranium mining has an impact on the environment. Mining requires land areas of various sizes (e.g. for open pits), which are then no longer available for agriculture or housing. The barren waste rocks and tailings have to be stored in the vicinity of the production centres, requiring additional ground. Dams have to be built to retain tailings; measures must be taken to ensure stability and impermeability. The radioactivity of uranium means that special safety measures must be taken during mining and processing to prevent radiological hazards to the population and environment. These measures have not been observed carefully in mining projects immediately after World War II. In the 95s and 96s, uranium production served mainly military purposes. This resulted in a growing state-supported uranium mining industry in the West and East. Major producers during that time were the USA, Canada, USSR, GDR, the Czech Republic, and the Republic of South Africa. After termination of mining due to exhaustion or termination of government sales contracts, mine sites and production centres were closed. In most cases, legal provisions for proper decommissioning and rehabilitation were lacking, and the sites were abandoned without any safety or recultivation measures being taken. The growing environmental awareness during the 97s resulted in governmental regulations being issued for new projects and for recultivation of abandoned sites. One of the major objectives of the regulations for new mines is to ensure proper consideration of the impact on the population and overall environment in view of the economic and socio-economic interests. The potential release of radioactive and chemically toxic substances during production is avoided by requiring special operating conditions. Today, mining companies in many countries are legally required to include the cost of decommissioning and rehabilitation in their cost calculations. The operator has to demonstrate that sufficient funds for later decommissioning and rehabilitation are available. New mines receive permission only when an environmental impact study (EIS) has been carried out. For abandoned mines the situation is different. Very often the previous owner is no longer available. To protect the population and the environment in those cases, many countries are now undertaking cleanup projects financed by the government. Examples of this are the Uranium Mill Tailings Remedial Action (UMTRA) of the USA or the ongoing program for German uranium mines and mills decommissioning. The examples shown in Table 4 illustrate the burden on the taxpayer when rehabilitation has to be carried out long after mining was terminated. The different types of rehabilitation projects, according to a proposal by URANERZ (994), may be classified as follows: ) Abandoned production sites: no rehabilitation by the owner, 27

6 TABLE IV. COST OF DECOMMISSIONING AND REHABILITATION. FOUR EXAMPLES OF COMPLETED AND ONGOING PROJECTS ) UMTRATitlel This project encompasses 24 facilities which were in production in the 96s and 97s. Uranium production: ca. 56, U Area involved: 45 ha Rehabilitation period: , by US government Expenditures today: $. billion, estimated total: $2. billion Specific costs: $9./lb UO8 today, estimated total $4.7/lb UO8 2) Beaverlodge, Canada Production period: Uranium production: 7,5U (underground mine) Rehabilitation period: , by the mining company Expenditures: C$ 6 million Specific costs: C$.6/lb UO8 or US$./lb UO8 ) Quirke mine, Elliot Lake, Canada Production period: , Uranium production: 44,U (underground mine) Rehabilitation period: , by the mining company Expenditures: C$ 46 million Specific costs: C$.4/lb UO8 or US$./lb UO8 4) UMTRA Title II Subject of this program is sites that are being decommissioned and rehabilitated by private companies through financial reserves set aside during the production period (surety bonds). Production period since before 98 Uranium production 25. t U Rehabilitation period since 98 Expenditures: S29 million so far, will become higher! Specific costs: SO 44/lb UO8 5) Average from 2 mining and 8 milling operations and 2 ISL projects in 4 countries (not including Germany) Accumulated production:. million tu Expenditures: $.7 billion Specific costs: $.25/lbUOs 28

7 rehabilitation at the expense of the government. Examples: Port Radium, Canada; several mines in western USA (UMTRA Title I); several mines in the CIS. 2) Rehabilitation at government expense immediately after closure. Examples: Wismut, Germany; several mines in the Czech Republic. ) Rehabilitation by the owner after closure, financed by the owner through earnings (regular case). Examples: Elliot Lake, Canada; mines in France; recently closed mines in the USA (UMTRA Title II) 4) Rehabilitation by the owner during the production period, financed through earnings. Examples: In situ leaching, e.g. in the USA Which decommissioning and rehabilitation methods are used depends largely on the type of the deposit and the mining and processing methods. The following parameters are associated with the specifics of the deposits: morphology of the orebody depth of mining rock stability hydrogeological conditions ore grade mineralogy and chemistry of the ore. Additionally, the following mining and milling techniques have to be taken into consideration: open pit mining, underground mining, conventional extraction (acid or alkaline leaching), heap leaching, in situ leaching from the surface by injection of acidic or alkaline chemicals, leaching underground. These aspects are only some of the general features to be taken into account. For new mines, which require licensing, consideration of the above parameters and mining and milling methods is part of the planning of costs during the feasibility study. For example, open pit mining is considered as cost-advantageous due to the use of largecapacity equipment. On the other hand, large-scale operations generally produce huge amounts of barren waste rock and large amounts of low-grade ore. Safe storage of over-burden and waste rock requires solid ground and well-engineered dumps. The mineralogy of the waste rock has to be analysed to determine its potential for generating acids, which would pollute the surface and ground water. The stability of the open pit walls has to be investigated and carefully monitored. The hydrogeology of the mine area is also a factor to be assessed and monitored. Safety measures for underground mines include monitoring of wall-rock stability, determination of the lithology and chemical composition of the wall rock and the hydrogeology. 29

8 The potential for the generation of acidic mine water is an important concern which has to be investigated prior to decommissioning. Suitable ground conditions are required for the deposition of tailings containing radioelements and in many cases chemically toxic substances (e.g. heavy metals, As). Various options for the safe disposal of tailings are available: ) In the past, an earth-dam across a morphological depression (e.g. a valley) was considered to be sufficient. However, leakage of water is a current problem which requires careful monitoring. Dam stability has to be assured, so that breaks or severe leakage of material is prevented. 2) Another option is the construction of a lined and covered pond. This requires careful monitoring. ) When available, open pits may be used as disposal sites for tailings. This option was taken up again recently in Canada and in France. The open pit remaining from the mined out Rabbit Lake deposit e.g. is used for disposal of the tailings from the currently operating Collins Bay and Eagle Point deposits. The mined out Deilmann orebody will be used for disposal of waste from mines that will soon become operational. Subaerial disposal of tailings has proved to be advantageous in terms of cost, since it simultaneously provides backfill for the open pit. Later covering and recultivation is regarded as low cost. 5. COST OF DECOMMISSIONING AND REHABILITATION The cost of decommissioning and rehabilitation depends to a large extent on the type of project. Four examples of completed and ongoing projects are given in Table IV. 6. URANIUM MINING IN EASTERN GERMANY Uranium mining started in 946 in the Erzgebirge Mountains, Saxony. These deposits have been mined since the 2th Century, first for silver, and later for cobalt, nickel and other base metals. The uranium mining district is in late Paleozoic (Hercynian) rocks north of the Bohemian Massif. Uranium was mined from well-known mines of Schlema-Aue, Johanngeorgenstadt in Germany and Jachymov in the Czech Republic. The deposits are of the vein-type. They occur mainly at the exocontacts of to My/old granites and are hosted by metamorphosed rocks (schists, amphibolites, metadiabase) of Ordovician to Devonian age. The mineralization belongs to the classical five element association (Bi-Co-Ni-Ag-U) and was formed in two periods at around 275 My and 55 My. The uranium content of the mined deposits varied considerably; the average grade was.4% U. The mines extended to a maximum depth of 75 m. Mining in the German part of the Erzgebirge yielded about 88 t U from more than 2 mining sites. Mining was terminated at the end of 99 due to economic considerations and depletion of the deposits. Production in the second mining district began in Thuringia in 95. At the beginning, uranium was mined in open pits from deposits hosted in Upper Permian sandstone and in black

9 shales of Ordovician and Silurian age. The Lichtenberg mine, the largest open pit mine, was worked from 957 to 978. At the same time, deposits were mined underground to a depth of m. The host rocks of the uranium mineralization are Ordovician shale (Lederschiefer), Silurian graptolitic shale and Devonian diabase. The mineralization occurs in lenses and stockworks and is fissure controlled. The oreforming process was complex, starting with an initial enrichment of uranium in the black shale (protore). When the black shale was exposed at the surface during the Permian, uranium was leached by weathering and redeposited on geochemical barriers in the non-weathered parts of the host rock. This process was controlled by the fracture system. The ages of the major ore formations are 24 Ma and 9 Ma. The average content was.8 to.9% U. The Ronneburg district in Thuringia yielded about 97 t U from more than 6 areas. Mining was terminated in 99 for economic reasons. The third and smallest mining district is located near Dresden, Saxony. Uranium hosted in coal of Permian age in the Freital area was mined from 947 to 955 and 968 to 989. About t U were produced. Uranium mineralization in the Konigstein area is hosted in Cretaceous sandstone (Cenomanian), similar to the Straz-Hamr deposits in the Czech Republic. Initially, the deposit was mined by conventional underground methods (967 to 98). Block leaching of low-grade, underground parts of the deposit using sulfuric acid was begun in 97, continuing until 99. About 5 t U were produced conventionally and 5 t U by leaching. A total of t U was produced in the former GDR from 946 to 99: 87% by underground mines, 9% by open pit mining and 2% by leaching methods. Two major processing operations utilized acid and alkaline extraction methods. The Crossen mill had an annual capacity of 2.5 million t of ore and the capacity of the Seelingstadt mill was 4.6 million t. The uranium mining districts of Saxony and Thuringia are among the most productive districts in the world. Their output may be compared to that of the Elliot Lake mines in Canada (4 t U) or of the Grants District, USA (25 t U). 7. RECLAMATION ACTIVITIES OF FORMER WISMUT MINING AND MILLING FACILITIES A vast amount of land and facilities was contaminated by Wismut uranium production activities from 946 to 99. The environments of the mining areas have been adversely affected. Only minor rehabilitation was carried out during the mining period by the former joint Soviet- German company Wismut. With the German unification the Federal Government of Germany took over responsibility for Wismut in 99 and was faced with various problems. The first decision was to terminate all commercial mining activities for economic reasons. Second, a program was initiated to evaluate the extent to which cleanup activities will be necessary. On behalf of the Federal Ministry for Environment, Nature Conservation and Nuclear Safety, the Federal Office for Radiation Protection (BfS) was commissioned to conduct a radiological evaluation of abandoned uranium mining and milling facilities. On the basis of recommendations by the German Commission on Radiological Protection, the evaluation was conducted with special emphasis to msv/year dose rate as the threshold value for individual exposition of the population, additional to the pre-mining exposition. The study areas were defined and field inspections with measurements of radioactivity were carried out. About 5 abandoned mining related sites originating from medieval silver

10 TABLE V. WISMUT SITES AT THE BEGINNING OF RECLAMATION ACTIVITIES Aue Kbnigstein Ronneburg Seelingstadt Total Surface (ha) Shafts Waste piles - number footing (ha) volume Mm' Tailings ponds -number surface (ha) volume Mm Mine workings - surface km ace. length km Open pits - number - surface (ha) volume Mm 84 (open) 84 Source: Wismut 994 2

11 mining and later base metal and uranium mining were identified in an area of 5 km 2. The evaluation reduced this area to about 25 km 2, which will require further investigation and cleanup measures. The comprehensive evaluation will be finished in 996/997. Other than the orphan mining sites all mining and milling facilities being active until 99 were transferred to the new Wismut rehabilitation company. Administered and financed by the Federal Ministry of Economics (BMWi) this government-owned but privately organized and privately managed company is responsible for the decommissioning and remediation of its facilities and sites. An overview of the mining and milling sites is given in Table V. After evaluating the complexity and magnitude of the necessary restoration measures, it was decided to take a site-specific, risk-based approach. Because this agricultural and industrial area is densely populated, all remediation activities had to be carefully planned. The ongoing restoration activities are illustrated by the following examples: Open pit mining has produced about 6 million m of ore and waste rock, of which about 6 million m was taken from a single open pit (Lichtenberg) nearly 2 m deep with an area of about.6 km 2. After mining activities ceased the open pit was used for disposal of waste rock from the Ronneburg mines. About 8 million m have been backfilled before 99. About million m of waste material remains piled around Ronneburg. Most of this material will be backfilled in the open pit. Underground mining has yielded about million m of material, half of which was ore. In the Aue district of the Erzgebirge, there are about 4 piles with a total volume of over 45 million m covering an area of about km 2. A major program of stabilization, reshaping, covering and revegetation of these piles is being carried out. In addition to numerous shafts, drifts totalling about 4 km have been driven. Mill tailings: Two major conventional mills have been operated (Crossen and Seelingstadt) besides a number of smaller ones, being active at the mining sites for a short period of time. At the Crossen mill, alkaline leaching methods were used for ore from the Erzgebirge. The tailings were disposed of in a nearby pond, about 2 km 2 in size, which now contains about 45 million m of tailings and 6 million m of water. The Seelingstadt mill used both alkaline and acid leaching methods and processed mainly ores from the Ronneburg district in Thuringia. The tailings were disposed of in two nearby ponds with a total volume of 7 million m, covering an area of,4 km STATUS OF WORK Detailed engineering studies in 99 and 992 yielded conceptual models for remediation measures. The most important measures may be classified as follows (only a selection): Underground remediation: cleaning and flooding of the mines, backfilling of mine workings, hydrological control, groundwater protection and monitoring.

12 Surface restoration: demolition of buildings, site rehabilitation for other uses, repair of surface damage caused by mine subsidence, cleaning of contaminated soil, groundwater protection and monitoring. Mill tailings remediation: in situ stabilization and covering of tailings, cover design, improvement of dam stability, groundwater protection and monitoring. At present, many of these activities are ongoing, e.g.: Underground mine remediation is far advanced. More than 5 underground barriers have been constructed to prevent exchange of groundwater with water in the flooded mines. Mine workings have been partly refilled or stabilized to protect the surface from mine subsidence, to minimize radon exhalation and infiltration of groundwater. Surface remediation includes backfilling of the Lichtenberg open pit from adjacent waste rock piles, reshaping of the remaining piles, and revegetation. Some buildings have been demolished, contaminated soil has been removed and the ground prepared for reuse. Covering of mill tailings after dewatering is one of the most challenging problems. With continuing dewatering, the ponds will be gradually covered using geotextiles and soil. The final cover will be designed to prevent radon emanation and water infiltration. Numerous boreholes and wells for the observation of groundwater control were drilled around the tailing ponds and are continuously monitored. DM 7 to 8 million are spent annually for these activities. It is estimated that about DM billion will be required over a period of to 5 years. BIBLIOGRAPHY BARTHEL, F.H., Uranium Production in the Former German Democratic Republic from 945 to 99, Geol. Jb, A 42, Hannover (99) 5-46 (in German). FEDERAL MINISTRY OF ECONOMICS, Wismut State of Decommissioning and Remediation, BMWi-Documentation No. 5, (99) 4 pp. FEDERAL MINISTRY OF ECONOMICS, Progress of Decommissioning and Remediation. BMWi-Documentation No. 7 (995) 5 pp. GATZWEDLER, R., MAGER, D., Remnants of Uranium Mining. Rehabilitation of Wismut, in German. Geowissenschaften, No. 5-6, (99) LANGE, G., "Technical Rehabilitation Options for Former Mining and Milling Facilities of Wismut GmbH", Planning and Management of Uranium Mine and Mill Closures, IAEA- TECDOC-824, IAEA, Vienna (995) 5. NELSON, CHERNOFF, A.R., MAGER, D. GOLDAMMER, W., Contrasts between the Environmental Restoration Challenges posed by Uranium Mining and Milling in the United States 4

13 and the Former German Democratic Republic, in: POST, R.G. (ed.): Technology and Programs for Radioactive Waste Management and Environmental Restoration. Proc. Symp. Waste Managem. Tucson, Arizona, 99. Vol., Washington DC (99) ROTHEMEYER, H., BRENNECKE, P., KRAUS, W., MAGER, D., An Overview of the Waste Disposal Situation in Europe and of Uranium Mine and Mill Remediation Activities in Germany. Meeting of the National Academy of Sciences/National Research Council's Committee on Environmental Management Technologies 6 Dec. 994, Washington DC (994). RUNGE, W. BOTTCHER, J., Closure and Rehabilitation of the East-German Uranium Mining. In German. Atomwirtschaft, (994) URANERZ, Comparison of Remediation Costs (994) (in German), unpublished, BMWi Research Project 7/9 [Summary published in: BMWi-Studienreihe, Nr. 9 (995) (in English, French, Spanish and Russian)]. NEXT PAGE{S) left BLANK ^ """ 5