By

John Wates and Michael Knight

Fraser Alexander

An evaluation of cyclone performance to improve the quality of cyclone underflow

material for tailings disposal

Use of cyclones for tailings?• Self raising configuration • Downstream• Centreline• Upstream

• Location of cyclones • Off wall cyclones trucked into place• Off wall cyclones pumped into place• On wall cyclones

Underflow Overflow

SUITABLE FOR COARSE TAILINGS

The problem

Split not achievedGeometryNon compliance

Tried!Split increaseSpecs not achievedStacking not achievedNon 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