Benchmarking: Amelunxen SGI - Agnico Eagle

Benchmarking: Amelunxen SGI Specific Energy Consumption - Agnico Eagle Laronde

Starkey, J., Robitaille, J., Cousin, P., Jordan, J. and Kosick, G., Design of the Agnico-Eagle Laronde Division SAG mill. Proceedings of SAG 2001, pages III-165 to III-178.

Survey conducted shortly after start-up

Actual operating data, table 7 from the reference

• Throughput = 210 dry tonnes per hour
• SAG circuit F₈₀ = 100 mm
• transfer T₈₀ = 244 µm
• circuit P₈₀ = 74 µm
• SAG power draw (at motor input) = 1350 kW (at mill shell = 1283 kW)
• SAG mill ball charge = 10.6 % vol
• SAG mill discharge % solids = 84% weight
• SAG mill speed 8.59 RPM (53.4% of critical)
• E_SAG at mill shell = 1283/210 = 6.11 kWh/t

(to achieve DCS power of 1350 kW requires 14% vol mill load)

• ball mill power draw (sum of 2 mills, at motor input) = 1422 kW (at mill shell = 2 × 674 kW = 1348 kW)
• ball mill % solids = 83% weight

(to achieve 1424 kW, assume 30% vol mill charge, 17 RPM)

• E_bm at mill shell = 1348/210 = 6.41 kWh/t
• ball mill operating Wi_O relative to motor input = 13.0 kWh/t (= 13.7 kWh/t relative to mill shell)

Design Criteria

• SGI (actually SPI&tm;) of ore (Oct 1, 2000 to - April 30,2001); assumed to be the 25^th percentile = 24 minutes.
• Wi_BM assumed to be 10 kWh/tonne.
• Plant availability = 94.4%

Mill criteria

• SAG mill: 24 foot nom diam by 12 foot effective grinding length (EGL)
• ball mill: two 11 foot nom diam by 17 foot (assumed to be EGL)
• SAG mill single variable speed motor 4500 HP
• Ball mill single fixed speed motors 1000 HP (each mill)
• assume rubber liners in SAG, nominal 8½ inch liner thickness
• assume steel liners in ball mills, nominal 3¼ inch liner thickness

Modelling

The Amelunxen SGI model for SAB circuit is used.

• circuit F₈₀ = 100 mm
• circuit P₈₀ = 74 µm

SAG mill is modelled using following:

• full Morrell SAG grate C-model
• assume ore density 2.7 t/m³
• effective dimensions 6882 mm diam × 3657 mm EGL

Ball mill is modelled using following:

• full Morrell ball mill wet overflow C-model
• assume ore density 2.7 t/m³
• effective dimensions 3186 mm diam × 5181 mm EGL

The model defaults are used for:

• CF_SAG = 1.0 (normal feed size, no pebble crushing)
• CF_ball = 1.10 (relationship for Los Bronces in Amelunxen et al, 2013)

Results

Result for default Amelunxen SGI SAB model conditions:

	Esag	Epeb	Ebm	Etotal	t/h
Predicted	6.5	-	6.9	13.4	196
Survey	6.1	-	6.4	12.5	210
Difference	0.4	-	0.5	0.9	14
Difference	model 7% high	-	model 8% high	model 7% high	model 7% low