Benchmarking: Ball Mill Power Draw Models

Benchmarking: Ball Mill Power Draw - Fimiston

• Nelson, M; Valery, W; Morrell, S, Performance Characteristics and Optimisation of the Fimiston (KCGM) SAG Mill Circuit, Page 233 - 248, SAG 1996 Conference, Vancouver, Canada.

Survey	Survey Power, kW at input	Mill speed, %critical	Total load, %v/v	Pulp %solids, w/w	Morrell SAG Model, kW at input / shell	Nordberg Model, kW at input / shell
Survey 1	3,864	68.3	38.7	72.0	3,933 / 3,776	3,592 / 3,345

• Morrell model predicts 2% high
• Nordberg model predicts 7% low

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Benchmarking: Ball Mill Power Draw - Meadowbank

• Muteb, P. & Allaire, J., Meadowbank Mine Process Plant Throughput Increase, Proceedings of the Canadian Mineral Processors Annual General Meeting, Ottawa, Canada, January 2013.

The ball mill design given as:

• Diameter inside shell: 18 ft
• Length (assumed to be flange-to-flange length): 29 ft
• Effective grinding length: 28.5 ft (using rule-of-thumb half-foot basis)
• Motor size: 6,000 horsepower (4,474 kW)
• Overflow mill with synchronous motor assumed

The operating conditions of the May 2012 survey, including the pre-crushing circuit given as:

• Mill speed 14.19 rpm (75% critical)
• Volumetric filling 30.6% v/v
• Ball charge 30.6% v/v
• Ore density 2.93 kg/L
• Grindability: A×b 38.6; Wi_BM 10.9 kWh/t

Liners assumed to be an effective thickness of 3 inches. DCS power is assumed to be indicated (mill power measurements × 0.985 pinion × 0.96 motor eff equals power "at mill shell"). Model power measurements are shown "at DCS".

	DCS Power, kW	Mill filling	Morrell Model, kW	Nordberg model, kW
May 2012	4,341	30.6% v/v	4,765 (+9.3%)	4,423 (+1.9%)

See details of benchmarking