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Data
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1
European Union
Tin ore ~ 1 Bq/g
J-02
2
European Union
Cassiterite or tinstone (SnO2) and sulphide ores - raw materials
Ore concentrate is mixed with charcoal and heated to 1000-1200 degrees, tin is remelted in a second furnace for purification
Slag and volatilised Po-210 which collects in dust precipitators. Typical concentrations in UK are 1 Bq/g of U-238 in both ore & slag, ~0.3 and 4.0 Bq/g in ore and slag respectively for Th-232 chain. Concentrations of up to 200 Bq/g of Po-210 have been found in the collected fume.
General ranges of activity in tin smelting industry (Bq/g)
Th-232 0.09-15.0, U-238 0.2-5.4, Ra-226 0.2-5.4, Pb-210 0.2-5.4
Doses
Normal conditions, min act conc 0.07 mSv/y, Normal conditions, max act conc 12.0 mSv/yr
Unlikely conditions, min act conc 0.03 mSv/y, Unlikely conditions, max act conc 47.0 mSv/yr
D-02
3
Malaysia, tin mining and processing
Main mineral - cassiterite (SnO2)
Typical concentrate for processing: cassiterite 9%, ilmenite 41%, silica 44%, rutile 0.5%, tourmaline 0.8%, zircon 2.1%, monazite 2.0%
Heavy minerals by-product (amang) contains ~95% of the radioactivity present in the original concentrate
Tin concentrate piles - 0.3-0.6 microSv/hr
Following beneficiation of the ore at the tin shed - 2.2-10.0 microSv/hr, zircon dump - 35 microSv/hr, monazite store 75 microSv/hr (up to 150 microSv/hr).
Rare earth separation plant up to 90 microSv/hr
Tin smelter < 4 microSv/hr
Nearby church where slag was used for back fill <2 microSv/hr
Tantalum slag up to 6 microSv/hr
Smelting stage - Pb210 & Po210 may be volatilised.
Airborne - radon/thoron + daughters - generally low
Long-lived alpha in dust could be a hazard in dry and dusty separation areas
G-05
3
Malaysia
Due to the value of cassiterite exceeding that of other associated heavy minerals, the dressing plants of alluvial tin mines normally produce cassiterite as the only clean product. The remaining by-product minerals locally known as 'amang' are stockpiled in open air dumps and later sold to specialised retreatment plants, generally referred to as 'amang' plants for further processing. Some miners still further separate amang into individual mineral components at the mine sites, which are known as 'tin sheds'.
Amang typically: 60% ilmenite, 0.5-2% monazite, 2% zircon, 0.5% xenotime.
Internal: gross alpha 0.05 - 6.8 Bq/m3
Radon-thoron: well below recommended limits
External: amang 1-8 microGy/hr, average 3-4 microGy/hr. In regularly occupied workplaces 1-2 microGy/hr, generally <2.5 microGy/hr. In areas of monazite concentrate storage up to 100-180 microGy/hr.
Doses 18-19 mSv/yr, 200 mSv/yr - worst possible case.
U-02
3
Russia, tantalum and niobium production
<also relevant for niobium, tantalum 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
S-13
4
Tin tailings (also known as amang) include such minerals as monazite, zircon, ilmenite, rutile, and garnet. Ra-226 and Th-232 activities in amang are both quite high with values of 15.91 to 17.76 Bq/g and 42.9 to 326.7 Bq/g respectively.
C-03
5
 Malaysia
Amang industry in South-East Asia was studied. Minerals present: ilmenite, zircon, xenotime, monazite.
External radiation measured in amang plants was, on average: offices - 0.6 microGy/hr, wet concentration areas - 1.5 microGy/hr, in general plant - 3.5 microGy/hr, amang - 3.5 microGy/hr, ilmenite - 2.5 microGy/hr, zircon - 6 microGy/hr, monazite - 95 microGy/hr, cassiterite - 6 microGy/hr, struverite - 4 microGy/hr, at a site boundary - 0.7 microGy/hr, in tailings area - 1.5 microGy/hr. Air sampling results were between 0.02 and 6.8 bq/m3. Mean exposure is estimated at 24 mSv/yr, with 10% of workers exceeding 50 mSv/year.
H-15
6
 Malaysia
Tin slag generated as waste, contains Ra-226 at 2 Bq/g, Ra-228 at 3 Bq/g. Regulation - if the dose to the public < 1 mSv/y - disposal exempted from control. In practice, however, a dose constraint of 0.3 mSv/y is used.
O-04
7
 The Netherlands, tin slag wool
A survey on mineral wool production in the Netherlands gave strong evidence that the slag wool has most likely been produced from a by-product (slag) of tin smelting between the years 1948 and 1960. Analytical data of the slag wool are:U-238 and Ra-226 4.0 Bq/g (range 2.6-6.2), Pb-210 2.9 Bq/g (range 1.7-3.8), Th-232 2.8 Bq/g ( range 1.8-4.2). In the new Dutch Radiation Protection Decree, clearance and exemption levels for U-238, Th-238, and Ra-226 are at 1 Bq/g for reporting and at 10 Bq/g for authorisation.
External dose rates on the surface of slag wool insulated equipment does not exceed 1 microSv/h and an average dose rate at working distance of 0.3 microSv/h seems to be a good estimate for dose assessments. Under unfavourable conditions but average activity concentrations the radiation exposure of demolition workers is estimated at about 1 mSv/a. For the maximum concentrations the estimated exposure does not exceed 2 mSv/a.
At another former site of a tin smelter in the UK in Bootle near Liverpool radiation levels over 10 times normal background where detected on rocks in the river estuary. Survey results were up to 10 microSv/h at 1m above the surface. It was found that that the area was covered with slag and rubble to depth of about 1.5m. Another material is more active black slag. The concentration of U-238 ranged from 5.0 to 6.2 Bq/g and the Th-232 concentration ranged from 12.1 to 14.7 Bq/g.
W-09

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