Transcript An evaluation of cyclone performance to improve the quality of

An evaluation of cyclone performance to
improve the quality of cyclone underflow
material for tailings disposal
By
John Wates and Michael Knight
Fraser Alexander
Use of cyclones for tailings?
• Self raising configuration
Underflow
Overflow
• Downstream
• Centreline
• Upstream
• Location of cyclones
• Off wall cyclones trucked into place
• Off wall cyclones pumped into place
• On wall cyclones
SUITABLE FOR COARSE TAILINGS
The problem
Split not achieved
Geometry
Non compliance
Tried!
Split increase
Specs not achieved
Stacking not achieved
Non compliance
Cyclone theory
• Inputs
• PSD
• Solids concentration
•Rheology
• Parameters influencing underflow properties (PSD & W/C)
• Diameter
• Vortex finder
• Spigot size
• Pressure/vacuum
• Operation
Why are underflow properties important?
• Shear strength
• 15% passing 75 micron/200 mesh
• Liquefaction potential (Drainage, PSD and Compaction)
• Permeability contrast (kuf > 100 x kof)
• Geometry
• Stacking
• Split to underflow
Underflow
Overflow
What we investigated
• Spigot/vortex finder combinations
• Pressure
• Barrel extension
• Pressurization
• Split
Test configurations
Conclusions
• There is an optimum vortex finder and spigot size 135/65
• Feed pressure of 180 kPa is the optimum
• Barrel extensions and pressurization improve split
• Splitting u/f discharge improves stacking (1:6 to 1:5)
• Stacking angle improves with increasing u/f RD and as %
passing 75 micron increases (1:5 for 10% passing 1:50 for >25%
passing)
• Split decreases as u/f RD increases and % passing 75 micron
decreases
Opportunities
• Improved efficiency and control in split
• Refinement of underflow criteria
• Handling finer tailings
• Higher rates of rise for finer tailings
• Reducing water consumption
Acknowledgements
• Co-author Michael Knight
• DRD
• Anglo Gold Ashanti
• The Fraser Alexander team