Benchmarking: Bond - Kanowna Belle

Benchmarking: Bond/Barratt SABC Circuit Specific Energy Consumption - Kanowna Belle

Lunt, D.J., Thompson, A. and Ritchie, I. The Design and Operation of the Kanowna Belle Milling Circuit, SAG 1996, Pages 81-96.

Paper describes the design criteria for the circuit and one survey.

Design Criteria

The reported mill conditions during the survey are,

• throughput: 170 tonnes/hour
• SAG feed size, F₈₀: 150 mm
• BM cyclone product size, P₈₀: 71 µm
• SAG: 2134 kW power draw at mill shell (E_SAG = 12.6 kWh/t)
• Ball mill: 1649 kW power draw at mill shell (E_SAG = 9.70 kWh/t)
• transfer size: 300 µm

The pebble crusher isn't described, assume it is a 7-foot cone crusher with 300 HP motor drawing 168 kW (E_peb = 1.0 kWh/t). Total circuit specific energy consumption E_total is 23.2 kWh/t.

Several samples are given in the text. It is assumed that the survey period looks similar to "Lowes West", the 'median' hardness sample of the non-oxidized samples. The Lowes West sample gives similar predictions to the "Pilot Plant" sample tested at A.R. MacPherson, which is claimed to have been selected to be representative of the sulphides.

Lowes West sample:

• Wi_C 26.7 (metric)
• Wi_RM 22.7 (metric)
• Wi_BM 16.1 (metric)

Density isn't given, assume 2.7 t/m³

Modelling, mill power draw

Adjust the SAG and ball mill models to get the shell power draws reported in the paper. Actual conditions don't matter because there isn't enough detail to properly model the mills -- treat them just as sources of output kW.

Modelling, Optimized Bond/Barratt SABC model

The Lowes West sample is predicted to have E_ssbm of 22.3 kWh/t, add 10% to give E_total prediction of 24.6 kWh/t. Based on the split of SAG + BM power, the T₈₀ needed to balance the circuit is about 1370 µm.

The predicted overall E_total is within 5.6% of the survey value.

	Survey	Model	Difference
ESAG	12.55 kWh/t	13.27 kWh/t	+5.7%
Eball	9.70 kWh/t	10.24 kWh/t	+5.6%
Epeb	0.99 kWh/t	1.04 kWh/t	+5.2%
Etotal	23.24 kWh/t	24.55 kWh/t	+5.6%

Modelling, Raw Bond/Barratt SABC model

The Lowes West sample is predicted to have E_total of 29.1 kWh/t. Based on the split of SAG + BM power, the T₈₀ needed to balance the circuit is about 530 µm.

The predicted overall E_total is 25.0% higher than the survey value.

	Survey	Model	Difference
ESAG	12.55 kWh/t	15.70 kWh/t	+25.1%
Eball	9.70 kWh/t	12.12 kWh/t	+24.9%
Epeb	0.99 kWh/t	1.23 kWh/t	+24.5%
Etotal	23.24 kWh/t	29.05 kWh/t	+25.0%

Discussion

The rod mill work index values in this survey were based on results from Amdel which is believed to have used a non-standard rod mill using a smooth liner. Bond rod mill work index determinations are supposed to be done in a mill employing a wave liner. The "pilot plant" sample rod mill work index was determined at the A.R. MacPherson - Hazen laboratory in the USA which is believed to have a wave liner. The ratio of Wi_RM:Wi_BM for the Pilot Plant sample (1.05) is dramatically different from the ratio for the samples tested in Australia (avg 1.40). In spite of this, the Lowes West sample, which is an "average sulphide" sample for Kawnowna Belle, gives very similar model predictions to the Pilot Plant sample.

The transfer size observed is very fine, 300 µm. The Raw Bond/Barratt model prediction is closer to the observed value (530 µm versus