1. REMOVAL OF THALLIUM FROM WASTEWATER
August 26, 2003
Hydrometallurgy 2003

2. Montana Tech of the University of Montana
View from Montana Tech Campus
L.G. Twidwell Prof. Metallurgical Engineering
C. Williams-Beam
Graduate Student
Metallurgical Engineering

3. Removal of Thallium From Wastewater
Reference Publication
“Final Report-Removal of Thallium from Waste Solutions” EPA Mine Waste Technology Program (MWTP), Activity IV: Project 12, MWTP-204, August 2003, 62 p (MSE-TA, Inc., Butte, MT).
Contact: Mr. Jeff LeFever,
August 26, 2003
Hydrometallurgy 2003

4. Reference Publication for Literature Review
“Technologies For Removing Thallium From Wastewater to Achieve Environmental Standards”, Proc. Recycling and Waste Treatment in Mineral and Metal Processing: Technical and Economic Aspects, Vol. 1, Eds. B. Bjorkman, et al, Lulea, Sweden, June 2002, pp
Contact: L. Twidwell,
August 26, 2003
Hydrometallurgy 2003

5. Environmental Requirements
Source Standard, µg/L
U.S. EPA MCL
U.S. EPA RCRA BDAT 140
Montana Water Quality
Board Human Health 1.7
Montana Non-Degradation
Trigger
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6. Thallium Occurrence
The major sources of thallium are the base metal sulfides and precious metal bearing sulfides.
Therefore, thallium is often a contaminant in waters emanating from heavy metal deposits, e.g., sulfide bearing deposits.
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7. Thallium Sources-Sulfides
Source Solids, mg/kg
Sulfide Mines
Gold Ores
Lead Concentrates
Zinc Concentrates
Tl Production rate (1999)
from sulfides , kg/yr ,500
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8. Thallium Sources- Wastewater
Source Water, g/L
Mining
Hg/Tl Ores ,000
Hg/As Ores ,000
Coal Mines ,000
Smelters
Pb ,000
Cu ,600
Pb/Zn Process Solution ,000,000
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9. Thallium Chemistry Thallium chemistry resembles potassium.
Compounds of thallium are relatively soluble, at least, compounds do not form that have solubilities <2µg/L.
Thallium with a +1 valence predominates in natural waters (see following figure).
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10. Tl concentration=50 µg/L

11. Thallium Technologies
Precipitation
Adsorption
Reductive Precipitation
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12. Thallium Precipitation
Hydroxide
USEPA BDAT-precipitation of Tl(OH)3 under very aggressive oxidizing conditions
The BDAT is only capable of achieving removals to ~140 µg/L
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14. Thallium Precipitation
Sulfide
Requires high sulfide/Tl concentrations, low solution potentials, and neutral to basic pHs
Has been used at some smelter sites
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15. S/Tl=100
Tl=1mg/L

16. Thallium Technologies
Precipitation
Adsorption
Reduction
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17. Thallium Adsorption Manganese Dioxide August 26, 2003
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18. Manganese Dioxide Many studies for heavy metal adsorption
However, only a few studies for Thallium adsorption
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19. Manganese Dioxide Bidoglio, et al (1993)
Complete adsorption of Tl on natural Birnessite, -MnO2 from solutions containing mg/L Tl using 20 m2/L of MnO2 (about 1 g/L) at pH levels of 4.7 and 8.5
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20. Manganese Dioxide Dahal, et al (1996, 98) Order of Adsorption
pH<2: Bi+3~Pb+2>Tl+1>Cr+3>Cu+2
pH 4: Pb+2>Cu+2>Tl+1>>Cr+3
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21. Manganese Dioxide Jibiki (1995)
Adsorption of Tl to <100 µg/L (from 12.5 mg/L) at pH <4 on 1 gram of manganese dioxide sludge from zinc electroplating
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22. Manganese Dioxide Williams-Beam Montana Tech M.Sc. Degree (2000)
EPA Mine Waste Technology Program (MWTP)
Demonstrated conditions for removal of Tl (+1)
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23. Manganese Dioxide Short Summary (Williams-Beam)
Two level factorial design results:
Final Tl (/L) = *Initial pH *MnO2 (g/L) *Initial Tl (g/L) – 9.87*Time (hrs) *Initial pH*MnO2 (g/L) *Initial pH*Initial Tl (/L).
pH 4 and 8; Tl 500 and 2000ug/L; Time 0.5 and 2.5 hr; Amount MnO2 2 and 20 g/L
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24. Summary for Effect of Variables
A set of “Constant Conditions” was formulated from experimental design results; time (30 minutes), initial Tl concentration (1000 µg/L), pH (7), and MnO2 (0.5 g/L, 30.6 m2/g).
The final Tl concentration achievable under constant conditions was 2.41.6 µg/L
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25. Manganese Dioxide To achieve <10 μg/L pH 5-8
Amount of MnO2: >0.25 g/L
Time >15 minutes
To achieve <5 μg/L
pH 5-8
Amount of MnO2: >0.5 g/L
Time >30 minutes
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26. Manganese Dioxide Maximum Loading
0.5-5 meq Tl/100 g MnO2 depending on processing conditions
Adsorption follows Langmuir isotherm
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27. August 26, 2003
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28. Manganese Dioxide
The final Tl concentration achievable under “constant conditions” was 2.41.6 µg/L. This is near our goal of <2 µg/L.
However, stripping the thallium from the MnO2 is very difficult.
Adoption of the process will depend on the economics of utilizing MnO2 as a throw-away product (which would have to be disposed of as a hazardous waste).
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Hydrometallurgy 2003

29. Thallium Technologies
Precipitation
Adsorption
Reductive Precipitation
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30. Reductive Precipitation
(Williams-Beam, 2000)
Concept
Precipitate thallium sulfide under controlled solution potential conditions
Iron used to control solution potential
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31. CONCEPT

32. Experimental System
Controllable Variables: reagent concentration, temp, time, gas atm, pH (automatic control), ORP (EH), agitation rate.
Parameters that can be monitored: time, temp, pH, ORP, reagent addition rate, gas flow rate.

33. Metallic Reductant The Starting Iron (see photo) August 26, 2003
Hydrometallurgy 2003

34. Starting Iron

35. Fe Cementation: Effect of pH and time
Study Results
Fe Cementation: Effect of pH and time
pH± Time, min Tl, g/L
Iron: 100 g/L
Heads: g/L
Sulfide: 0

36. Tl/Fe/H2O System x x

37. Effect of pH and sulfide without Fe potential control
Study Results
Effect of pH and sulfide without Fe potential control
pH± Sulfide, mg/L Tl, g/L
Heads: g/L Time: 30 minutes

38. Tl/S/H2O System x x

39. Effect of pH, sulfide addition, with Fe potential control
Study Results
Effect of pH, sulfide addition, with Fe potential control
pH± Sulfide, mg/L Tl, g/L
<1
Iron: 100 g/L
Heads: g/L
Time: 30 minutes

40. Tl/Fe/S/H2O System x x x

42. Effect of pH, sulfide addition, with Fe potential control
Study Results
Effect of pH, sulfide addition, with Fe potential control
Sulfide, mg/L Tl, g/L
5.7 (7.3x)
11.4 (14.6x)
22.8 (29.2x) <1
45.6 (58.4x) <1
Iron: 100 g/L
Heads: g/L
Time: 30 min
pH 5.5 ± 0.3
EH ~-495 mV

43. Final Product Deposited on Iron Surfaces

44. ASARCO Water Study Results
Effect of pH and sulfide addition, Fe potential control
Sulfide, mg/L Tl, g/L
Iron: 100 g/L Head: 810 g/L Time: 30 minutes pH 5.5 ± EH ~-430 mV

45. Reductive Precipitation
Benefits
Effective thallium removal over a wide range of experimental conditions
Restrictive operational controls will not be required, e.g., solution pH variations, fluctuations in initial thallium conc., temp. variations and sulfide doping levels
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46. Reductive Precipitation
Benefits
Technology can be conducted in standard, readily available and conventionally used mineral processing, extractive metallurgy, and solid/liquid separation equipment
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47. Reductive Precipitation
Benefits
Tl is collected into a low volume concentrated form that can either be disposed of in a hazardous site repository or can be utilized as a chemical feedstock
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48. Reductive Precipitation
Benefits
Other heavy metals should be coextracted with the thallium, e.g., Cd (as a sulfide), Cu (by cementation), Ni (as a sulfide), Pb (as a sulfide), and Zn (as a sulfide).
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49. Reductive Sulfide Precipitation Reductive Sulfide Precipitation
Diagrams based on 5 µg/L for metals

50. Reductive Sulfide Precipitation
Diagrams based on 5 µg/L for metals

51. Reductive Precipitation
Future Study
MSE-EPA-MWTP will be initiating a pilot scale (1-5 gal/min) thallium (and other heavy metals) removal study this fall using the reductive precipitation concept
August 26, 2003
Hydrometallurgy 2003

52. Mine Waste Technology Program (MWTP) Activity IV, Project 12,
Acknowledgement
The authors gratefully acknowledge
the financial support from the U.S. EPA:
Mine Waste Technology Program (MWTP) Activity IV, Project 12,
EPA/DOE IAG No. DW
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53. QUESTIONS AND COMMENTS
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54. Thanks for your attention!! Montana Tech of the University of Montana
Website:
August 26, 2003
Hydrometallurgy 2003