Potential and Applications of Underground in-situ Bioleaching

Future Mining Conference Sydney, November 4, 2015 Authors: Ralf Schlüter, Helmut Mischo

2 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Future Challenges

• Sustainable supply of raw materials • Strategic elements (REEs, PGMs,

Indium, Germanium, …) • Economic growth of BRIC-countries

Awareness of dependency

• Increasing depth, decreasing ore grades, complex mineralization

• Restricitions due to environmental and social footprints

• Limitations by technical efforts and high energy consumption

Conventional mining and processing methods difficult to apply

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

3 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Introduction in Bioleaching

• Conversion of insoluble raw material into an aqueous form by chemical and biological (microbes) reactions

• Mainly metal-sulphides (MeS) and uranium (U)

• Typical bacterial strains: Acidithiobacillus ferrooxodans, Acidithiobacillus thiooxodans , Leptospirillum ferrooxidans

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

4 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Major Industrial Applications

• Heap and dump bioleaching of secondary, low grade sulphide ores

with minerals like chalcocite (Cu2S) and covellite (CuS)

• Heap leaching of low grade, primary sulphide ores containing

minerals like chalcopyrite (CuFeS2)

• Stirred tank bioleaching of copper concentrates or pre-treatment of

sulfidic refractory gold ores

• in-situ bioleaching of uranium ore

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

5 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Potential of in-situ Bioleaching

• (not) Subsequent to conventional mining operations

• Combination of mining and processing • High potential in reduction of operation

steps (energy, personnel demand and costs)

• Remote controlled in-situ operation

Scientific focus and engineering approaches required!

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

7 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

tank leaching

process control

heap leaching

in-situ leaching

dump leaching

Issues on Process Control

• Identification and intense exploration • Influence on

Specific surface Permeability of the formation Oxygen and Carbondioxyde Temperature pH-value Mineralization

• Intensive monitoring and controlling

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

8 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Underground Bioleaching Testing Facility

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

9 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Overall Set-up

• Closed leaching circle • Comprising several production steps

underground

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

10 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Conditions at favoured Location I

• (dipping) Height 10 m • Dipping angle ~ 50° • Length of excavation block 35 m

• Temperature ~ 8 - 12 °C • pH of mine seepage around 2 – 3 • Pre-existant microbes

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

11 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Conditions at favoured Location II

• Vein thickness up to 1 m • Sphalerite, Pyrite, Arsenopyrite,

Chalcopyrite, Galena • Quarz, Carbonates

Bau

er a

nd S

eife

rt 20

15

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

12 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Approach 1 – Fragmentation by Blasting

• Conventional method • Sequenced blasting with gelatine

explosives • Swell factor of 1,7 Ore removal/spoiling ~ 40%

San

d et

al.

1993

• Fragmentation size below 30 cm • High specific surface • Sufficient flow and streaming paths

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

13 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Approach 2 – Hydraulic Crack Stimulation • Hydraulic pressure to enhance permeability

(cracks, fissures, weak zones, joint faces) • Stepwise investigation of conditioning

progress • Monitoring via inverse polarisation

(geoelectrics)

• No swell effect • Only one crack due to pressure loss • Potential of remote control from

surface

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

14 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Approach 3 – Water Pressure Blasting

• Gel explosive + water (coupling medium)

• High strain rate in the wall of borehole exceeding dyn. critical fracture strength

abundant circumferential + radial fractures

• Subsequent crack extension

Hua

ng e

t al.

2011

• No swell effect • Potential of remote control from

surface

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

15 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Bulk blasting Hydraulic fracturing Water pressure blasting

high specific surface low specific surface sufficient spec. surface

sufficient flow- and streaming paths few cracks and fissures multiple main cracks

crack propagation in all directions within the formation

one crack perpendicular to direction of minimum principal

stress

circumferential and radial blasting cracks, fan-shaped propagation of hydr. cracks

swelling volume increase no swell effect no swell effect

beneficial for leaching kinetics probably insufficient promising approach

Comparison of Approaches

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

16 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Conclusion

• Basic research on different innovative conditioning methods under consideration of leaching kinetics

• Determination of the most suitable approach regarding remote controlled bore hole method

• Smale scale testing facility with involvement of several production steps • Handling of issues regarding mineralization, conditioning and

monitoring

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

17 TU Bergakademie Freiberg | Institute of Mining Engineering and Special Civil Engineering | Chair Underground Mining Methods | Phone: +49 (0)3731 / 39-3602 | www.tu-freiberg.de | Presenter: Dipl.- Ing. Ralf Schlüter | 4th November 2015

Introduction Industrial Applications Future Potential Testsite Conditioning Approaches Conclusion

Thank you for your attention