1. Recycle and Recovery of
Critical Materials from Pyrometallurgical Waste
Austin Blumenthal
Hunter Chase
Megha Gandhi Sara Viau
Advisor Dr. Corby Anderson

2. Background
Recycling of critical/precious metals has become significant in the past decade as known sources of these metals are depleting
Gopher Resources (Our Sponsor), a lead-based battery recycler, produces % pure lead or special lead alloys through their refining process
Drossing, a process used to remove impurities like Copper, is currently used by Gopher Resources

3. Background (cont.) Caustic dross addition meant to remove As & Sb
Sulphur drosses remove Cu impurities
No specified step for Ni removal
Gopher Resources partnership around leaching of the impurities present after Caustic Drossing

4. Scope
Gopher Resources sent us sample from Caustic Dross (CCW) & Sulfur Dross (DECO)
Focus of this study on CCW slag sample leaching
The CCW slag sample contains 25 wt% lead which is normally fed back into lead smelter to adjust melt chemistry.
Copper, Nickel, and Arsenic are impurities in lead slag which are detrimental to producing lead products
Hydrometallurgical extraction methods could be used to economically recycle this slag to increase Pb value

5. Analysis of As-Received Cold Caustic Wash
XRF Results
MLA Results

6. Analysis of As-Received Cold Caustic Wash
Quantitative phase analysis difficult to decipher
Oxide phases determined appropriate leaching reagents

7. Fundamentals of Science Used
Leaching is a method used to dissolve solids into their ionic forms
Factors that affect leaching conditions include the following:
Solubility
Reagents
Selectivity
Regeneration
Furthermore, the right Eh and pH conditions are significant in determining the right leaching conditions
Finally, the shrinking core model demonstrates the heterogeneous kinetics that is taking place in the reactor

8. Pourbaix Diagrams
Copper Diagram
Nickel Diagram

9. Experimental Method Leach experiments tested four factors:
Residence Time: From 4 hours to 8 hours
Temperature: From 25 to 75 degrees celsius
Sulfuric Acid Concentration: From 20 to 50 g/L
Hydrogen Peroxide: From 0 to 10 g/L
Design Expert was used to generate runs for a 24-1 factorial design with 3 midpoints

10. Experimental Method- Experimental Matrix

11. Results and Discussions
Recovery of Nickel, Copper, and Arsenic for variant operating conditions

12. Results and Discussions
Potential and pH for the 11 runs at variant conditions

13. Results and Discussions
Free acid titrations conducted at room temperature for 11 runs

14. Leach Optimization
Design Expert was used to produce computer models of each response
ORMULAS]

15. Leach Optimization- Ni Response Cube

16. Leach Optimization- Cu Recovery Contour

17. Leach Optimization- Nickel Recovery Contour

18. Leach Optimization- Final Results
Temperature: 75 C
Residence Time: 4 hours
Sulfuric Acid Concentration: 50 g/L Sulfuric Acid
Peroxide Concentration: 4.22 g/L Hydrogen Peroxide
Recovers 74.3 wt% Cu, 22.5 wt% Ni, and 54.0 wt% As

19. Leach Optimization- Copper Recovery

20. Leach Optimization- Mass Balance

21. Process Design Criteria- Flow Sheet
10 tons of CCW per day
2 leach vessels (each 10,000 gallons)
20 wt. % solids for leach
Production of Cu/Ni Carbonates
Production of iron arsenates

22. Economic Analysis - OpEx & CapEx
Hourly Labor Cost, USD
$179,316.80
Salaried Labor Cost, USD
$0.00
Electrical Cost, USD
$171,500.00
Maintenance and Repairs Cost, USD
$423,850.00
Natural Gas Cost, USD
$30,625.00
Hydrogen Peroxide Cost, USD
$225,806.68
Operating Supplies Cost, USD
$63,577.50
Laboratory Charges Cost, USD
$26,897.52
Total Annual Operating Cost, USD
$1,121,573.50
Fixed Capital Estimate, USD
$4,966,025
Working Capital Estimate, USD
$744,903.74
Total Capital Estimate, USD
$5,710,928.68

23. Economic Analysis Capital Expense, USD $5,710,928.68
Annual Operating Expense, USD
$1,121,573.50
Annual Revenue, USD
$ 1,310,713.60
Discount Rate, %
5.0%
Net Present Value, USD
$-4,250,438.94
Internal Rate of Return, %
-16.3%
Payback Period, months
363

24. Economic Analysis

25. Conclusions
Our proposed design recovers 74.3 wt% copper, 22.5 wt% nickel, and 54.0 wt% arsenic
Agitated leaching and ionic precipitation methods were used to selectively remove and recover the impurities
While design has a positive yearly cash flow, the magnitude of flow does now pay back capital costs at a feasible rate.

26. Future Work
Leach optimization with additional factors- slurry density and particle size
AA on copper recovery
Replicate studies should be conducted to verify results

27. Acknowledgements Dr. Corby Anderson Dr. Joe Grogan
PhD Candidate Hao Cui
Majuba Hill Senior Design Group

28. References
[1] T. Ellis and A. Mirza. “The refining of secondary lead of use in advanced lead-acid batteries”, Elsevier: Journal of Power Sources, Jan Web. 18 Jan
[2] P. Tan and P. Vix. “Thermodynamic Modeling of copper drossing process in lead refining”, TMS, Web. 18 Jan 2017.
[3] C. Gupta and T. Mukherjee, Hydrometallurgy in extraction processes, 1st ed. Boca Raton: CRC Press, 1990, p. 462.
[4] Geogene And Anthropogenic Controls On The Mineralogy And Geochemistry Of Modern Alluvial-(Fluvial) Gold Placer Deposits In Man-Made Landscapes In France, Switzerland And Germany. Hannover: Journal of Geochemical Exploration 99(1):29-60, Web. 1 Apr
[5] Anderson, C.G. The Shrinking Core Model Lecture # Kroll Institute for Extractive Metallurgy, George S. Ansell Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO.
[6] G. Wyss. “Characterization of Lead Processing Samples”, CAMP, 3 March, 2017.

29. Questions?