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1
Brazil, niobium mining and processing
Effluent treatment was generally efficient to reduce radionuclide releases to the environment, with the exception of one niobium industry that had to include an additional step (precipitation with sulphate) to remove Ra-228 (in concentrations up to 5 Bq/l) from seepage water in its tailings dam.
The predicted effective doses to the hypothetical critical groups are below 0.3 mSv/year.
F-01
2
Brazil, niobium mining and processing
Open pit processing, Activity Median Aerodynamic Diameter (AMAD) + 1 micron, bioassay results were typically below minimum detection level but uranium was detected for some occupations (processing). Dose: open pit - 1.3 mSv/yr, leaching - 1.2 mSv/yr, other areas - 0.2-0.8 mSv/yr.
L-01
3
European Union, niobium processing
Ferro-niobium production, raw material - pyrochlore or columbite ~ 50 Bq/g Th
J-02
4

European Union, niobium production
 Niobium is found in tantalite (Ta2O6)(Fe,Mn), columbite (Nb2O6Fe), fergusonite (Nb,Ta)O4(Y,Er,Ce)Nb2O7Ca2, samarskite, pyrochlore (Na,Ca,Ce)2Nb2O6F, koppite and loparite. The ore is processed by melting with sodium or potassium hydroxide, dissolving in hydrochloric acid, and processing with chlorine at 750-800oC. The resulting metallic niobium is then further purified. Ferro-niobium may be also produced using a process involving a high temperature exotermic reaction between pyrochlore and aluminium powder.
General ranges of activity in ferro-niobium industry (Bq/g): Th-232 7-80; U-238 6-10; Ra-226 6-10, Pb-210 6-500
Doses
Normal conditions, min. act. conc 0.05 mSv/y; Normal conditions, max act conc 320.0 mSv/yr
Unlikely conditions, min act conc 0.19 mSv/y; Unlikely conditions, max act conc 640.0 mSv/yr
D-02
5

Brazil, niobium processing
Brazilian pyrochlore - RNb2O6.R(Ti,Th)O2 operations in Araxá produce solid wastes with Ra-226 in the range 0.2-100.0 Bq/g, Ra-228 in range 0.5-300.0 Bq/g.
P-04
9

Russia, niobium and tantalum production
<also relevant for tantalum, tin and beryllium>
To manufacture ore concentrates of tantalum, niobium and tin the spodumen beryllium ores are used in a milling factory. After the preparation of the ore (fragmentation and rubbing) the final separation of each mineral is done by the specific techniques. Cassiterite (tin concentrate) is extracted using electromagnetic separation and niobium concentrate is manufactured using chemical extraction.
Specific activities (Bq/g):
Raw material
Spodumen beryllium ore: U-nat 0.59, Ra-226 0.19, Th-232 0.022, Pa-231 0.0014
Products
Ta-Nb concentrate: U-nat 960, Ra-226 240, Th-232 12
Deprived Ta-Nb concentrate: U-nat 55, Ra-226 3.7, Th-232 5.2
Ta concentrate: U-nat 0.67, Ra-226 0.004, Th-232 n/d
Nb concentrate: U-nat 1.5, Ra-226 0.09, Th-232 n/d
Tin concentrate: U-nat 670, Ra-226 110, Th-232 6.7
Tin concentrate of final purification: U-nat 370, Ra-226 89, Th-232 4.4, Pa-231 27.0
Wastes
Natural iron: U-nat 110, Ra-226 11, Th-232 2.9
Pomergranate sand: U-nat 120, Ra-226 6.3, Th-232 0.3
Cake: U-nat 370, Ra-226 1.3, Th-232 0.2
Eticke: U-nat 28, Ra-226 48, Th-232 0.7
Smear of the equipment: U-nat 16, Ra-226 3.3, Th-232 0.07
Metal tantalum production
Processing of Ta concentrates and wastes from Sn production. Producing potassium fluorotantalate, which is recovered to metal tantalum. >90% of activity transferred to wastes.
Specific activities (Bq/g)
Raw materials
Russian: U-nat 77-152, Ra-226 20-36, Th-232 1.3-8.1, Pa-231 1-18.5, Ac-227 0.5-152
Imported (unspecified): U-nat 22-151, Ra-226 3-23, Th-232 3.1-100, Pa-231 5.2-5.9, Ac-227 89-100
German: U-nat 159, Ra-226 4.8, Th-232 7.4, Pa-231 n/d, Ac-227 137
Australian: U-nat 311, Ra-226 23, Th-232 4.4, Pa-231 12.2, Ac-227 n/d
Products
Potassium fluorotantalate: U-nat 0.04-0.22, Ra-226 0.02, Th-232 0.02, Pa-231 0.02, Ac-227 0.2-0.3
Niobium hydroxide: U-nat n/d, Ra-226 0.06, Th-232 0.03, Pa-231 0.06, Ac-227 0.04
Wastes
Pulp: U-nat 14.1, Ra-226 2.1, Th-232 0.6, Pa-231 0.8, Ac-227 1.3
Ash: U-nat 0.8, Ra-226 0.3, Th-232 0.1, Pa-231 n/d, Ac-227 n/d
S-13
10
 EU
Very high radionuclide concentrations occur in pyrochlore, the source of niobium, and this is reflected in the products and the wastes. Assessments of the radiological impact of operations associated with metal smelting generally indicate that worker doses are low, with the exception of those from pyrochlore where values of up to a few mSv/yr are possible. Exposure of the public owing to releases from these processes is generally assessed to be low. However, the potential doses from landfill disposal of waste could be more significant, where values up to 10 mSv/yr could occur as a result of intrusion and site redevelopment.
E-08

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