Radiological Evaluation associated to the Mining of Monazite in Central Spain

Transcription

1 Radiological Evaluation associated to the Mining of Monazite in ntral Spain R.García-Tenorio a, E. Sanz b, E. Burkhalter c, G.Manjón a, I. Vioque a and I. Diaz a a Departmentof Applied Physics II, University of Sevilla, Spain b GeomniaNatural Resources, Madrid, Spain c QuantumMineria, Madrid, Spain

2 SUMMARY AThe detailed Mulas radiological Rare Earth evaluation mining has project been(ciudad performed Real, associated ntral Spain, with the 200 mining km of south the Mulas of Madrid) monazite is deposit composed. Thisof evaluation unconsolidated has been based sandyinand the following clayey studies: alluvium/colluvium deposit originated from paleozoic weathered source rocks a) that determination host (0.1 to 2.0 of mm) the activity monazite concentrations nodules comprised of several of roughly radionuclides 60% rare from earth the oxides Uranium by weight. and Thorium series in representative samples of the material mined, b) This construction grey or dark of an external monazite gamma is completely dose-rate different map of the to the mining common area, yellow c) thorium-enriched study of the distribution monaziteof that thewas natural mined radioactivity in the recent in the past material as source extracted of rareas earths. a function of the grain size, d) radon determinations in the area, and e) laboratory leaching experiments. Although the rare earth extraction mining is one of the activities recognized in the positive list of NORM activities, all the results allow concluding that the rare earth mining activity performed in ntral Spain can be considered as exempted, being not needed the adoption of radiological countermeasures.

3 MATAMULAS SITE THE LOCATION

4 REE ORES in EUROPE

5 DIMENSION OF MATAMULAS ORE

6 CRITICAL RAW MATERIALS

7 MINING AREA

8 MONAZITE CHARACTERISTICS 100% REO O 2 42,93 2 O 3 27,26 La 2 O 3 15,95 Pr 8 O 11 5,77 Sm 2 O 3 4,18 Gd 2 O 3 1,78 Y 2 O 3 0,60 Dy 2 O 3 0,40 Eu 2 O 3 0,40 Ho 2 O 3 0,38 Tb 4 O 7 0,21 Yb 2 O 3 0,06 Tm 2 O 3 0,05 Er 2 O 3 0,03 Lu 2 O 3 0,00 Hardness: Mohs scale Real Density: 4.65 g/cm 3

9 MONAZITE CHARACTERISTICS Quantitative results Weight% O Ne Al Si P K Fe La Spectrum 1 Si O P Al Ti Gd Gd Ti K Ti Sm Sm Sm Fe P Gd Gd K CaTi Ca Mg Sm Gd Gd Sm Sm Fe K Ca Ca Sm Fe Sm Gd Fe Gd Sm Sm Gd Gd Full Scale 1291 cts Cursor: kev (54 cts) kev

10 MONAZITE CHARACTERISTICS Quantitative results Weight% O Al Si P K Fe La Spectrum 1 O La P La Si La Al La Fe La La Fe K La Fe La La P K K La Fe Full Scale 824 cts Cursor: kev (28 cts) kev

11 SAMPLING STEP A GRADDED APPROACH STEP B

12 EXPERIMENTAL TECHNIQUES GAMMA SPECTROMETRY ALPHA SPECTROMETRY SEM -EDX GAMMA DOSE RATE

13 RADIOMETRIC DETERMINATIONS (I) Activity Concentrations (Bq/kg) Quite uniform the radionuclide distribution -Comparable with the obtained ones in big extensions over the country The grey monaziteisenrichedin natural radionuclides?

14 RADIONUCLIDE DETERMINATIONS (II) 232 Th Bq/kg 238 U Bq/kg

15 RADIONUCLIDE DETERMINATIONS (III)

16 EXTERNAL GAMMA DOSE RATE MAP

17 Monazite separation and concentration Only physical processes applied Intermediatefration lessthan5% in weigth

18 Radionuclide Granulometric Distribution

19 Radiological Implications Negligible radiological impact in the mining process due to external radiation Negligible radiological impact in the mining and concentration process due to inhalation. The fine material susceptible to be resuspended/inhaled in the mining and concentration processes depleted in natural radionuclides. Radiological impact due to 222 Rn should be discarded, because the mining and concentration processes are carried out at open-air Actividad de 222 Rn (Bq/m 3 ) ENE FEB MAR ABR MAY JUN Occupational doses susceptible to be received by the workers in charge of the different concentration processes and of the handling and storage of the concentrates in the plants evaluated as msv/a due to the external radiation. This estimation was performed adopting very conservative assumptions.

20 Environmental Radiological Implications Radiometric determinations in -5 underground waters collected from wells located in the mining area -vegetables (lettuces. Spinachs, chards, tomatoes) -fruits, olives, cereals. DO NOT SHOW ENHANCEMENTS IN NATURAL RADIONUCLIDES IN THE MINING AREA Leaching experiments submitting monazite fractions during 24 hours to the action of -rainwater - ground water M HCl show not detectable activities in the leachates( by alpha and gamma spectrometry) MONAZITE QUITE REFRACTORY MATERIAL

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22 Th internal distribution

23 PUBLIC RISK PERCEPTION The positive list Industrial sectors most likely to require some form of regulatory consideration Uranium mining and processing Rare earths extraction Thorium extraction and use Niobium extraction Non-U mining- including radon Oil and gas Production and use of TiO2 Phosphate industry Zircon and zirconia Metals production (Sn, Cu, Al, Fe, Zn, Pb) Burning of coal Water treatment-including radon

24 Thanks Gracias