Difference between revisions of "Benchmarking: SGI - Macraes"

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| SAG power draw || kW at shell || 1945 || 2164 || 2013 || 1954 || 1876
  
| SAG power draw || kW at shell || 1945 || 2164 || 2013 || 1954 || 1876
 
|-
  
|-
−
| ball mill specific power || kW at shell || 4361 || 3761 || 3424 || 3818 || 3804
 +
| ball mill power draw || kWh/t at shell || 4361 || 3761 || 3424 || 3818 || 3804
 
|-
  
|-
−
| SAG specific power || kW at shell || 3.6 || 4.8 || 4.1 || 3.8 || 3.6
 +
| SAG specific energy || kWh/t at shell || 3.6 || 4.8 || 4.1 || 3.8 || 3.6
 
|-
  
|-
−
| ball mill specific power || kW at shell || 8.1 || 8.3 || 7.4 || 7.4 || 7.2
 +
| ball mill specific energy || kWh/t at shell || 8.1 || 8.3 || 7.4 || 7.4 || 7.2
 
|-
  
|-
−
| total specific power* || kW at shell || 11.8 || 13.0 || 11.4 || 11.2 || 10.8
 +
| total specific energy* || kWh/t at shell || 11.8 || 13.0 || 11.4 || 11.2 || 10.8
 
|-
  
|-
 
| Ball mill Operating work index, Wi<sub>O</sub> || kWh/t ||12.6||10.0||11.4||10.4||10.2
  
| Ball mill Operating work index, Wi<sub>O</sub> || kWh/t ||12.6||10.0||11.4||10.4||10.2
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! !! !! Survey 5 !! Survey 4 !! Survey 3 !! Survey 2 !! Survey 1
  
! !! !! Survey 5 !! Survey 4 !! Survey 3 !! Survey 2 !! Survey 1
 
|-
  
|-
−
| SAG specific power || kW at shell || 3.79 || 4.98 || 4.71 || 3.83 || 3.89
 +
| SAG specific energy || kWh/t at shell || 3.89 || 5.13 || 5.04 || 3.99 || 3.89
 
|-
  
|-
−
| ball mill specific power || kW at shell || 8.5 || 8.64 || 8.49 || 7.55 || 8.04
 +
| ball mill specific energy || kWh/t at shell || 8.71 || 8.92 || 8.58 || 7.80 || 8.04
 
|-
  
|-
−
| total specific power* || kW at shell || 12.64 || 14.03 || 13.62 || 11.73 || 12.39
 +
| total specific energy* || kWh/t at shell || 13.04 || 14.58 || 14.18 || 12.25 || 12.39
 
|-
  
|-
−
| transfer size, T<sub>80</sub><br>to achieve E<sub>SAG</sub>/E<sub>ball</sub> ratio || &micro;m || 2864 || 1419 || 1485 || 1374 || 2437
 +
| transfer size, T<sub>80</sub><br>to achieve E<sub>SAG</sub>/E<sub>ball</sub> ratio || &micro;m || 3608 || 1703 || 1581 || 1623 || 2437
 
|-
  
|-
−
| Ball mill operating Wo || kWh/t || 10.45 || 11.77 || 11.46 || 11.53 || 11.07
 +
| Ball mill operating Wio || kWh/t || 10.45 || 11.77 || 11.47 || 11.53 || 11.07
 
|-
  
|-
 
| CF<sub>ball</sub> || predicted || 1.01 || 1.01 || 1.01 || 0.97 || 0.97
  
| CF<sub>ball</sub> || predicted || 1.01 || 1.01 || 1.01 || 0.97 || 0.97
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! !! !! Survey 5 !! Survey 4 !! Survey 3 !! Survey 2 !! Survey 1 !! Overall<br>Average
  
! !! !! Survey 5 !! Survey 4 !! Survey 3 !! Survey 2 !! Survey 1 !! Overall<br>Average
 
|-
  
|-
−
| SAG specific power || ||4.4% || 4.5% || 15.3% || 0.8% || 6.0% || 6.2%
 +
| SAG specific energy || ||7.1% || 7.6% || 23.4% || 5.0% || 9.4% || 10.5%
 
|-
  
|-
−
| ball mill specific power || ||4.5% || 4.3% || 15.5% || 1.6% || 6.4% || 6.5%
 +
| ball mill specific energy || ||7.1% || 7.7% || 16.6% || 4.9% || 11.4% || 9.6%
 
|-
  
|-
−
| total specific power || ||4.5% || 4.4% || 15.4% || 1.3% || 6.3% || 6.4%
 +
| total specific energy || ||7.1% || 7.7% || 19.0% || 5.0% || 10.8% || 9.9%
 
|-
  
|-
 
| CF<sub>ball</sub> || ||-17.5% || 16.9% || 0.5% || 10.6% || 8.3% || 3.8%
  
| CF<sub>ball</sub> || ||-17.5% || 16.9% || 0.5% || 10.6% || 8.3% || 3.8%
 
|}
  
|}
   
−
The overall specific energy consumption predictions of the model are conservative by about 6%. The CF<sub>ball</sub> predictions are within 4% overall, but can be wildly different on any particular sample.
 +
The overall specific energy consumption predictions of the model are conservative by about 10%. The CF<sub>ball</sub> predictions are within 4% overall, but can be wildly different on any particular sample.

Latest revision as of 16:38, 15 June 2017

Benchmarking: Amelunxen SGI Circuit Specific Energy Consumption - Macraes

Barns, K., Lane, G., Osten, K. & Scagliotta, N., Benchmarking Energy Efficiency - A Case Study at Macraes Gold Mine, Proceedings of the AusIMM MetPlant conference, Perth, Australia, September 2004.

Raw data from paper

The paper describes overall plant unit operation efficiency rather that specific grinding mill surveys, but does reference five surveys that are useful for benchmarking.

Survey 5 Survey 4 Survey 3 Survey 2 Survey 1
throughput dry t/h 536 454 493 514 527
SAG feed F80 mm 82.9 106.8 72.7 56.8 51.4
SAG power draw kW, motor input 2057 2288 2129 2066 1984
SAG specific power kW at DCS 3.84 5.04 4.32 4.02 3.76
combined ball mill power kW, motor input 4612 3977 3833 4038 4023
ball mill specific power kW at DCS 8.60 8.76 7.78 7.86 7.63
transfer size, T80 µm 795 3318 804 2215 2043
cyclone overflow size, P80 µm 100 100 100 117 116
grindability, SPI minutes 40.7 46.3 43.2 34.7 40.5
grindability, WiBM kWh/t 10.3 11.6 11.3 11.9 11.4

Interpretation

Assume that the power provided at the motor input is converted to shell power using 0.96 motor efficiency and 0.985 gear efficiency for an overall conversion of 0.9456.

Other published information on Macraes state that there is a pebble crusher in the circuit, but no crusher size or power draws are published. Assume a 400 HP crusher for the purposes of modelling.

Survey 5 Survey 4 Survey 3 Survey 2 Survey 1
SAG power draw kW at shell 1945 2164 2013 1954 1876
ball mill power draw kWh/t at shell 4361 3761 3424 3818 3804
SAG specific energy kWh/t at shell 3.6 4.8 4.1 3.8 3.6
ball mill specific energy kWh/t at shell 8.1 8.3 7.4 7.4 7.2
total specific energy* kWh/t at shell 11.8 13.0 11.4 11.2 10.8
Ball mill Operating work index, WiO kWh/t 12.6 10.0 11.4 10.4 10.2
CFball values actual 1.22 0.86 1.01 0.88 0.90

* includes allowance for pebble crushing

The calculated operating work index values permit CFball values to be determined for each of the surveys. This factor includes any phantom cyclone effect and any accumulated Rowland efficiency factors. For the purposes of modelling, the CFball values are predicted using Amelunxen's method and will be compared to the actual measurements.

Because full mill surveys aren't given, abbreviated model runs are used in this benchmarking rather than full models (there is no saved data to view).

Use Amelunxen SGI model with pebble crushing, fine feed (where appropriate) and predicted CF factors.

Model Results

Survey 5 Survey 4 Survey 3 Survey 2 Survey 1
SAG specific energy kWh/t at shell 3.89 5.13 5.04 3.99 3.89
ball mill specific energy kWh/t at shell 8.71 8.92 8.58 7.80 8.04
total specific energy* kWh/t at shell 13.04 14.58 14.18 12.25 12.39
transfer size, T80
to achieve ESAG/Eball ratio		 µm 3608 1703 1581 1623 2437
Ball mill operating Wio kWh/t 10.45 11.77 11.47 11.53 11.07
CFball predicted 1.01 1.01 1.01 0.97 0.97

* includes allowance for pebble crushing

Comparison

Difference between model results and plant surveys:

Survey 5 Survey 4 Survey 3 Survey 2 Survey 1 Overall
Average
SAG specific energy 7.1% 7.6% 23.4% 5.0% 9.4% 10.5%
ball mill specific energy 7.1% 7.7% 16.6% 4.9% 11.4% 9.6%
total specific energy 7.1% 7.7% 19.0% 5.0% 10.8% 9.9%
CFball -17.5% 16.9% 0.5% 10.6% 8.3% 3.8%

The overall specific energy consumption predictions of the model are conservative by about 10%. The CFball predictions are within 4% overall, but can be wildly different on any particular sample.

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