1. Scavenging Flotation Tailings using a Continuous Centrifugal Gravity Concentrator
Hassan Ghaffari, Bern Klein
UBC Mining
Ish Grewal, Knelson Gravity Solutions

2. Continuous Centrifugal
Gravity Concentrators
Kelsey Jig
Falcon Model C
Knelson CVD

3. CVD Concentrator Operating Variable Bowl speed Fluidization water
Pinch valve open time
Pinch valve closed time
Variable interactions
Model
Feed Rate (t/h)
CVD6-1
0.5 – 2
CVD32-1
40 – 70
CVD32-2
CVD42-1
70 – 100

4. CVD Applications Industrial Applications Density separator
Separation of iron oxides from talc
Cassiterite
Chromite
Gold and gold bearing sulfides
Tested Application
Scavenging rougher flotation tailings
Scavenging cleaner flotation tailings
Separation of ash and sulfur from coal
Density separator
Size classifier
Mass yields (1 to 40%)
De-slime

5. Flotation Recovery versus Particle Size

6. Scavenging Flotation Tailings
CVD - Size enhanced density separator
Recover coarse middling particles from tailings in small mass yield (<5%)
Recycle CVD concentrate to grinding circuit
Reduce losses at coarse end of particle size distribution
Improve overall metal recovery
Potential opportunity
Increase grind size
Reduce losses at fine end of particle size distribution
Increase grinding circuit throughput
Reduce energy requirements
Effectively produce narrower size distribution of liberated sulfide minerals in particle size range where flotation is most efficient

7. Eskay Creek Mine Au/Ag Mine
Flotation of bulk sulfide concentrate grading 100 g/t Aueq

8. Eskay Creek Mine Flotation Circuit
Ball Mill
Hydrocyclone
Flotation
Knelson
Gemini Table
Smelter
Cyclone
O/F
Conc.
Feed
Tailing
Au/Ag Flotation recoveries average 90%
Variations in ore mineralogy affect recoveries

9. Pilot Scale Testing Lab testing Plant testing UBC Center for
Mineral Processing

10. Sample Characterization
P80 (µm) Au Ag
+100 mesh Fraction
+150 mesh Fraction
(ppm)
Weight %
Au Distrib. %
S Distrib. %
LGT
130
1.9
48.3
9.3
27.9
20.6
HGT
100
3.2
39.0
5.3
10.6
10.7

11. Batch Knelson Tests Sample Mass Yield % Au (ppm) Au Recovery % LGT 5.0
5.1
20.0
HGT
4.0
3.9
8.8

12. Lab Pilot Scale Tests Results - LGT
Au (ppm)
Au Recov %
Upgrade Ratio
Mass Yield % 1
6.31
5.5
5.95
0.93 2
4.46
6.5
3.88
1.67 3
12.51
28.4
8.67
3.27 4
3.66
14.7
3.33
4.43 5
5.60 35
4.52
7.74 6
4.36
15.3
1.64
9.32

13. Au Grade versus Particle Size in CVD Concentrate and Tailing

14. S Grade versus Particle Size in CVD Concentrate and Tailing

15. Au Grade/Recovery versus Mass Yield

16. Size Partition to CVD Conc.

17. Eskay Creek Plant Trials
Thickened flotation tailings
26 Trials

18. Eskay Creek Plant Trials

19. Eskay Creek Plant Trials

20. Eskay Creek – Plant Trial
Flotation of CVD Concentrate

21. Proposed Hybrid Flotation / Gravity Flowsheet
Feed
Cyclone
O/F
Tailings
Ball Mill
Hydrocyclone
Flotation
Conc.
Batch Knelsone
Knelson
CVD
Conc.
Gemini Table
Tailing
Conc.
Smelter

22. CONCLUSIONS & RECOMMENDATIONS
Pilot scale testing indicated that the CVD was effective at recovering metals from flotation tailings.
The results indicated that the metal recovered was primarily in the coarse size fractions, which would likely contain middling particles (sulfide + silicates) ie size enhanced density separation.
Flotation of the reground gravity concentrate yielded good grades and recoveries.

23. CONCLUSIONS & RECOMMENDATIONS
Continuous Centrifugal Gravity Concentrators may have a role in hybrid flotation gravity circuits that exploit the strengths of each technology
The next step is to assess the potential for increasing grind size to reduce losses in ultrafine fraction, reduce energy requirements and increase throughput

24. Barrick Eskay Creek Mine Knelson Gravity Solutions NSERC IPS
Thank You
Acknowledgements
Barrick Eskay Creek Mine
Knelson Gravity Solutions
NSERC IPS