Benchmarking: Bond - Cadia

Benchmarking: Bond/Barratt - Cadia

Dunne, R., Morrell, S., Lane, G., Valery, W. and Hart, S., Design of the 40 foot diameter SAG mill installed at the Cadia gold copper mine. Proceedings of SAG 2001, pages I-43 to I-58.

Lane, G., Foggiatto, B. and Bueno, M, Power-based comminution calculations using Ausgrind. Proceedings of Procemin 2013, Chapter 2, paper 2.

Papers describe a survey conducted shortly after start-up.

Ore characterization

• Monzonite ore type,
  • Wi_C = 16.5 (metric)
  • Wi_RM = 19.0 (metric)
  • Wi_BM = 17.1 (metric)
  • A×b = 36
  • DWI = 7.5
  • density = 2.7 t/m³

SAG mill characteristics

• Diameter inside shell = 12.2 m (40 ft)
• EGL = 6.1 m (20 ft)
• Ball filling = 12% v/v
• Total filling = 25% v/v
• Mill speed = 78% of critical (Lane et al, 2013 appears to have a typo. They claim 72% which actually looks like the BM speed)
• Pulp density = 70% w/w
• SAG feed is primary crushed to F₈₀ = 98 mm

Ball mill characteristics

• Diameter inside shell = 6.7 m (22 ft)
• EGL = 11.3 m (36.5 ft)
• Ball filling = 30% v/v
• Mill speed = 72% of critical
• Pulp density = 70% w/w
• Ball mill circuit product P₈₀ = 170 µm

Modelling

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  Model screenshot of Cadia 1998 survey simulation

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  SAG model screenshot of Cadia 1998 survey simulation

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  Ball mill model screenshot of Cadia 1998 survey simulation

Results

Result for default Optimized Bond/Barratt SABC-A model conditions:

	T80, mm	Esag	Epeb	Ebm	Etotal	t/h
Predicted	2.06	8.6	0.3	8.5	17.4	2000
Survey	1.34	8.6	-	8	16.6	2065
Difference	0.72	0	0.3	0.5	0.8	-65
Difference	54%	0%	-	6%	5%	-3%

Discussion

• The rod mill work index was determined on an apparatus with a smooth liner. Bond specified that the liners of a Bond rod mill work index apparatus should have wave liners, and the Optimized Bond/Barratt model is calibrated to the wave-liner machines. If one deducts 2 kWh/t from the rod mill work index (allowance for difference in apparatus) and re-runs the calculation, the following results are obtained:
  • E_SAG = 8.3 kWh/t (-3% from survey)
  • E_ball = 8.2 kWh/t (+2% from survey)
  • E_total = 16.8 kWh/t (+1% from survey)
• Using the Raw Bond/Barratt model predicts E_total = 18.2 kWh/t (+10% from survey). The Optimized Bond/Barratt model works better at modelling this circuit.