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1
Titanium originates in sands that also contain monazite. Waste titanium sludge from processing can have double the concentrations of radium in comparison to the ore itself, along with a majority of the thorium and uranium in the ore. The method of chlorinating the ore to extract titanium can again double the amount of radium in the processing waste sludge.
C-03
2
European Union, titanium dioxide production
Raw materials: rutile (TiO2), and ilmenite (FeO.TiO2) that contains monazite as impurity. Other possible sources - tailings from bauxite and copper ore processing.
Rutile/ilmenite is crushed & mixed with coal. Titanium tetrachloride TiCl4 is obtained by chlorination in shaft furnaces. The TiCl4 is then reduced to titanium sponge which is melted and remelted in vacuum arc furnace. Ore activity for both chains 0.07 - 9 Bq/g. During the processing of ilmenite for the production of TiO2 pigments, a radium precipitate occurs. Activity concentration of such precipitates have been reported as ~ 400 Bq/g.
General ranges of activity (Bq/g)
Th-232 0.03-9.0, U-238 0.03-9.0, Ra-226 0.03-400.0, Pb-210 0.03-9.0
Doses
Normal conditions, min act conc 0.01 mSv/y, Normal conditions, max act conc 51.0 mSv/yr
Unlikely conditions, min act conc 0.05 mSv/y, Unlikely conditions, max act conc 120.0 mSv/yr
D-02
3
UK, titanium dioxide production
Ilmenite scale, typical concentrations (Bq/g): Ra-228 20, Ra-226 100, Pb-210 100, Po-210 100.
Some concentration of radionuclides occur in waste streams but these do not cause significant occupational exposure.
Estimated typical dose is ~ 0.4 mSv/year
H-01
4
Russia, titanium ore smelting
Ilmenite at Berezniki titanium-magnesium concern.
Ore thermal smelting (OTS) of ilmenite with coke. Titanium-rich slags and cast iron are obtained. Dust emitted.
Products of OTS (Bq/g)
Concentrate: Th 0.24; Th-230 0.22, Th-228 0.23, Ra-228 0.25, Ra-226 0.22, Po-210 0.22
Cast iron: Th-232: <0.005, Th-230 <0.006, Th-228 <0.009, Ra-228 <0.004, Ra-226 <0.003, Po-210 0.002
Slag: Th-228 0.34-0.44, Ra-228 0.40-0.47, Ra-226 0.30, Po-210 0.010-0.018
Dust (Bq/g)
Dust caught in 1st stage cyclone: Ra-226 0.26-0.35, Ra-228 0.32-0.41, Th-228 0.31-0.38, Pb-210 2.2-4.0, Po-210 2.1-3.8
Dust caught in 2nd stage: Ra-226 0.196-0.320, Ra-228 0.276, Th-228 0.140-0.212, P-b210 9.8, Po-210 9.5
Dust not caught in cyclone: Ra-226 0.242-0.272, Ra-228 0.240-0.343, Th-228 0.098-0.124, Po-210 8.5-13.5
Radionuclides are practically not transferred to cast iron, remaining in the slags and dust. Pb & Po - to the dust, fine fractions are enriched with Pb and Po to a greater extent than coarse fractions.
G-04
5
European Union
Titanium dioxide pigment industry - feed (ilmenite) 1 Bq/g U & Th, waste up to 5 Bq/g.
J-02
6
Australia, ilmenite separation
Radiation contained in the heavy mineral products comes from two sources: (a) entrained monazite, and (b) U and Th inherent in the individual grains. In the early 1980's significant modifications were made in dry separation plants to reduce entrained monazite to 3-50 ppm Th (~10% of the total Th in ilmenite). Another method - removal of thorium from ilmenite: heat treatment of ilmenite and synthetic rutile at temperatures above 1200 degrees --> a phase rich in silica and Th appearing on the mineral grain surface. Subsequent acid leaching lowers Th and U from ~500 ppm to <100ppm.
H-04
7
Australia, ilmenite processing
Gamma spectroscopy of ilmenite - no differences were observed for Th decay chain.
Some of ilmenite samples measured showed significant disequilibrium in the U decay chain. Ra-226 levels were much greater than U-238 levels. This could be due to adsorption of Ra from groundwater onto altered ilmenite, loss of uranium, or possibly some disturbance of equilibrium during the wet stages of processing.
H-06
8

Australia, ilmenite processing
Waste minimisation for streams containing radionuclides. "Rutile" process - waste is "enironmentally friendly" and is suitable for immediate discharge with mine tailings. Chloride plant feedstock specs U+Th<50 ppm
H-07
9
Netherlands
Ra-226 concentrations in ilmenite is independent of grain size, - homogenous distribution of Ra226 in grains
Rutile - the increase in radium concentration with increase in grain size cannot be explained by any common type of radium distribution.
T-06
10
Australia
Pigment production waste 5.6 Bq/g radium, Pigment production filters - 25 Bq/g radium
Sulphate process - produces TiO2 pigment by dissolving ilmenite in sulphuric acid and precipitation TiO2 from aqueous solution. Most of radionuclides report to an aqueous waste stream containing sulphuric acid and ferrous sulphate. Small amounts plate out in process vessels, filter frames - surface contamination.
Chloride process - produces Th tetrachloride from natural and synthetic rutile. Following extraction of the titanium tetrachloride a waste containing gangue material and most of the radionuclides is produced and a slurry or filter cake.
H-11
11

In certain work areas of TiO2 pigment plants radium is partially solubilised during the process and may accumulate in scales formed in pipelines and process vessels and can be concentrated on filter frames or in the chorinator.
Maximum concentrations in a closed vessel in TiO2 plant in Yugoslavia - Rn-222 320 Bq/m3, Rn-220 6000 Bq/m3.
H-12
12

Bangladesh
Zircon, garnet, magnetite, ilmenite. Gamma 0.23-8.89 microSv/hr. Radon 20.5-252.6 Bq/m3. Dose estimate for workers ~6.9 mSv/year.
M-09
13
Vietnam
Mineral sands ore: Th 35-1967 ppm, U 6-240 ppm (gamma dose rates range between 0.12 and 6.32 microGy/hour).
Ilmenite concentrate: Th 63-91 ppm (0.51-0.75 Bq/g), U 15-27 ppm (0.37-0.66 Bq/g).
Tailings from ilmenite separation: Th up to 3980 ppm (32.6 Bq/g), U up to 590 ppm (14.5 Bq/g), gamma dose rates up to 13.4 microGy/hour.
H-14
14
 Malaysia
Titanium dioxide is produced from ilmenite or synthetic rutile. Wastes generated: red gypsum (0.1 Bq/g of Ra-226, 0.06 Bq/g of Ra-228) and iron oxide (0.7 Bq/g of Ra-226, 0.9 Bq/g of Ra-228) - quite voluminous, waste is temporarily dumped at companies' premises, no final solution is found as yet. 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

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