ball charge management
TRANSCRIPT
5. Ball charge management
Grinding with ball mill systems
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07-06/JOKHGRS ACC & GACL Mill Workshop
Ball charge management
Ball charge
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Ball charge management
Mill absorbed power reduces Grinding efficiency reduces
As the balls wear
So does production So does production
Top up for wear compensation Ball charge classification
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07-06/JOKHGRS ACC & GACL Mill Workshop
While a Ø 90 [mm] becomes an Ø 80 [mm] an Ø 80 [mm] becomes a Ø 70 [mm] and so on …
< Ø 30 – 40 [mm] wear slower than bigger balls
Ø70 [mm]
Ø80 [mm]
Ø90 [mm]
Top up for ball wear compensation (1/5)
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07-06/JOKHGRS ACC & GACL Mill Workshop
Replace the missing balls
Ø70 [mm]
Ø80 [mm]
Ø90 [mm]
Top up for ball wear compensation (2/5)
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First chamber:
1. Compartment
Ø Ball [mm] Weight [ t ] Percent [%] Wear comp. [%]
90 20.0 25.0 100.0
80 28.0 35.0
70 20.0 25.0
60 12.0 15.0
Total 80.0 100
Average ball weight [ g ] 1667
Spec. media surface [m2 / t] 10.2
Top up for ball wear compensation (3/5)
Biggest ball size
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07-06/JOKHGRS ACC & GACL Mill Workshop
2.Compartment
Ø Ball [mm] Weight [ t ] Percent [%] Wear comp. [%]
50 17.0 10.0 15.0
40 17.0 10.0
30 27.2 16.0 35.0
25 27.2 16.0
20 35.7 21.0 50.0
17 45.9 27.0
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Total 170.0 100
Average ball weight [ g ] 41
Spec. media surface [m2 / t] 32.8
Second chamber:
Top up for ball wear compensation (4/5)
3 balls sizes required
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07-06/JOKHGRS ACC & GACL Mill Workshop
Top up for ball wear compensation (5/5)
Frequency Regular production intervals Regular time intervals (e.g.: targeting a constant absorbed
power for the mill motor)
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Ball charge classification (2/4)
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Good
Bad
Ball charge classification (3/4)
Visual criteria for ball form classification (deformed/broken)
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First chamber Once every year
Second chamber Once every two – three years:
- OPC
- OPC + < 5 [%] MIC Once every one – two years:
- Composite cements (>> 5 [% MIC)
- Slag
- Puzolana
Standard frequency for ball charge classification
Ball charge classification (4/4)
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Ball charge operating cost
Purchasing
Electrical energy
Classification
0.05
1.30 – 4.40
0.03 – 0.05
50 [g/t] gross wear
40 [kWh/t]
Standard frequency
USD/tcement
1.38 - 4.50
Classification costs are 1-4 [%] of energy costs. Therefore sensible to classify the charge at standard intervals.