Benchmarking: BondBarratt - Detour Lake

From SAGMILLING.COM
Jump to: navigation, search

Benchmarking: Bond/Barratt SAG Mill Specific Energy Consumption - Detour Lake

  • J. Torrealba-Vargas, J.-F. Dupont, J. McMullen, A. Allaire and R. Welyhorsky, The successful development of the detour lake grinding circuit: from testwork to production. Proceedings of the SAG 2015 Conference, September 2015, Vancouver, Canada, Paper 38.

Operating data from 2015, A×b looks similar to 50th percentile from the October 2012 NI43-101 report.

"Current value" data, table 7 from the reference

  • Throughput = 2×1,258 = 2,516 dry tonnes per hour
  • SAG circuit F80 = 90.7 mm (pre-crusher product)
  • circuit P80 = 90 µm
  • SAG power draw (at motor input, per mill) = 13,424 kW (at mill shell = 12,694 kW)
  • SAG mill ball charge = 17 % vol
  • SAG mill total charge = 24.3 % vol
  • SAG mill discharge % solids = 70% weight
  • SAG mill speed 80.24% of critical
  • ESAG at mill shell = (2×12,694)/2,516 = 10.1 kWh/t
  • pebble crushers typically draw 322 kW
  • Epeb = (2×322)/2,516 = 0.26 kWh/t
  • ball mill power draw (at motor input, per mill) = 13,982 kW (at mill shell = 13,221 kW)
  • ball mill % solids = 80% weight
  • ball mill total charge = 25.4
  • ball mill speed = 79.61% of critical
  • Ebm at mill shell = (2×13,221)/2,516 = 10.5 kWh/t

Design Criteria

  • Ore A×b = 26.6, between 25th and 50th percentiles
  • WiBM use 50th percentile = 14.3 kWh/tonne.
  • WiRM use 50th percentile = 18.0 kWh/tonne.
  • WiC use 50th percentile = 14.8 kWh/tonne.
  • Plant availability = 87%

Mill criteria

  • SAG mills: two 36 foot nom diam by 17.25 foot effective grinding length (EGL)
  • ball mill: two 25 foot nom diam by 38.0 foot EGL (flange-to-flange length 38.5)
  • SAG mills, each twin variable speed motor 7000 kW (each mill)
  • Ball mill, each twin (assumed variable speed) motors 7500 kW (each mill)

Modelling

SAG mill is modelled using following:

  • Austin SAG model
  • ore density 2.9 t/m³
  • SAG liners nominal 4 inch liner thickness
  • liner thickness based on JK Simulation in Table 3
  • effective dimensions 10768 mm diam × 5334 mm EGL
  • predicted SAG power draw at mill shell = 13,448 kW (5.9% higher than actual)

Ball mill is modelled using following:

  • Nordberg ball mill wet overflow with density correction
  • ore density 2.9 t/m³
  • ball mill nominal 90 mm liner thickness
  • liner thickness based on JK Simulation in Table 3
  • effective dimensions 7439 mm diam × 11581 mm EGL
  • predicted ball mill power at mill shell = 13,273 kW (0.4% higher than actual)

Results

Benchmarking-DetourLake.png

Result for default Optimized Bond/Barratt model conditions:

Esag Epeb Ebm Etotal t/h
Predicted 9.0 0.2 8.8 18.0 3004
2015 data 10.1 0.3 10.5 20.9 2516
Difference 1.1 0.1 1.7 2.9 508
Difference model 12% low model 33% low model 16% low model 14% low model 20% high

Discussion

The mill is in the final stages of ramp-up, and has not reached its ultimate capacity. Figure 5 shows they are consistently exceeding 2,700 t/h in April & May of 2015, suggesting they can do 7% more than the data in Table 7.

If we claim that 7% difference between April/May and the 2015 data, then the differences become:

  • Etotal : actual = 19.5 kWh/t, model 7% low
  • t/h : actual = 2700 t/h, model 13% high

The ultimate capacity of this circuit hasn't been established yet, so it could very likely continue to improve and approach the model numbers.

Trying the Raw Bond/Barratt model and comparing to the April/May 2015 values, the model predicts:

  • Etotal : 18.3 kWh/t, model 1% high
  • t/h : 2992 t/h, model 2% high