VALID PRACTICE

FOR THE
PRODUCTION PROCESS

#10 – BALL CEMENT MILL

MONITORING, INSPECTION & EVALUATION

Athens, December 2007

 Valid Practice #10

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 BALL CEMENT MILL
MONITORING, INSPECTION & EVALUATION
Technical Details  
Plant   ……….
Mill
Mill Supplier
Mill Type  
Operating hours since installation  
Operating hours since last ball charge refill  
Operating hours since last inspection  
Operating Parameter Unit  
Cement Type  
Date dd/mm/yy  
Time hh:mm  
Production rate (wet) t/h  
Composition (wet)
Clinker t/h  
Natural Gypsum t/h  
Limestone t/h  
Pozzolana t/h  
Other t/h
Water content %  
Water injection lt / min  
Grinding aid g/t  
Iron Sulfate Heptahydrate (FeSO4.7H2O) g/t  
Production rate (dry) t/h  
Composition (dry)
Clinker %
Natural Gypsum %
Limestone %
Pozzolana %
Other %
Grinding aid %
Iron Sulfate Heptahydrate (FeSO4.7H2O) %
Temperature    
Mill inlet temperature °C  
Mill outlet temperature °C  
Mill filter outlet temperature °C  
Pressure    
Mill inlet pressure mbar  
Mill outlet pressure mbar  
Mill delta P mbar  
Mill filter delta P mbar  
Separator filter delta P mbar
Gas Measurement    
Flow at mill filter stack (wet) Nm3/h  
Flow after mill (wet) Nm3/h  
Flow at separator filter stack (wet) Nm3/h  
Flow after separator (wet) Nm3/h
Flow fresh air (wet) Nm3/h  
Flow hot gas (wet) Nm3/h
Operational Parameters    
Folafon %  
Separator speed %
Mill fan speed %  
Separator fan speed %
Recirculation elevator %  
Mill fan damper %  
Recirculation damper %  
Fresh air damper %  
Energy Consumption    
Mill motor KW  
Mill separator KW  
Mill fan KW  
Separator fan kW
Mill bucket elevator KW
Specific Electrical Energy Consumption (SEEC)
Mill motor kWh / t  
Mill classifier kWh / t  

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 Valid Practice #10

Mill fan kWh / t  

Separator fan kWh / t
Mill bucket elevator kWh / t
Mill motor, separator, mill fan & separator fan kWh / t  
Total kWh / t

Quality Parameters Unit  

Gypsum moisture %  
Limestone moisture %  
Pozzolana moisture %  
Other moisture %
Blaine
Mill outlet cm² / gr
CM Filter outlet cm² / gr
Separator Filter outlet cm² / gr
Separator inlet cm² / gr
Separator rejects cm² / gr
Separator fines cm² / gr  
Final product cm² / gr
Corrected Final product Blaine (w/o effect of additives) cm² / gr
Fineness (Residue at 90μm) %  
Fineness (Residue at 45μm) %  
Water Demand (WD) %  
Setting Time (initial) min  
Setting Time (Final) min  
1day  
2days  
Strength (N/mm²)
7days  
28days  
LOI %  
IR %  
SO3 %  
Free CaO %  
SiO2 %  
Al2O3 %  
Fe2O3 %  
CaO %  
MgO %  
K2O %  
Na2O %  
Granulometry Analysis, Sieve    
Cumulative Passing, %
1 %  
1,5 %  
2 %  
3 %  
4 %  
6 %  
8 %  
12 %  
16 %  
24 %  
32 %  
48 %  
64 %  
96 %  
128 %  
192 %  
Rosin - Rammler  
Slope, n #  
d‘ μm  
Production between 3 - 32 μm %  
Tromp curve  
Separator efficiency as recovery of fines, Uf %
Circulation load based on laser #
d50 %
d75 %
Kappa (k), slope of the curve in the interval 50%-75% #
Cut size, particle size corresponding to the Tromp value
50% %
By-pass, Tromp value at the lowest point of curve %
Separator efficiency as reduction in power consumption, Vs (32 μm
sieve)  

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 Valid Practice #10

Circulation load #
As reduction in power consumption, Vs %

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 Apart from the above, on monthly basis the following tables should be completed:
 regarding operation:
Mills Stoppages    
Available hours h  
Actual operating hours h
Duration of Annual Maintenance h  
Duration of Strategic stoppages
(for example Saturation etc.) h  
Duration of stoppages because of Other external reasons
(for example Power failure etc.) h  
Downtime    
Downtime because of Operational reasons h  
Downtime because of Mechanical reasons h  
Downtime because of Electrical reasons h  
Downtime because of Planned maintenance
(excluding annual maintenance) h  
Total Downtime h  
Grinding media consumption
(including refilling and new load)    
5 year history g/tCement produced  
1 year history g/tCement produced  

 regarding quality:
Quality Parameters Unit MONTHLY AVERAGE 
CEMENT TYPE
Composition (dry)
Clinker %
Natural Gypsum %
Limestone %
Pozzolana %
Other %
Grinding aid %
Iron Sulfate Heptahydrate (FeSO4.7H2O) %
Blaine
Fineness (Residue at 90μm) %  
Fineness (Residue at 45μm) %  
Water Demand (WD) %  
Setting Time (initial) min  
Setting Time (Final) min  
Strength (N/mm²) 1day  
2days  
7days  
28days  
LOI %  
IR %  
SO3 %  
Free CaO %  
SiO2 %  
Al2O3 %  
Fe2O3 %  
CaO %  
MgO %  
K2O %  
Na2O %  

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 Valid Practice #10

 regarding ball charge management:

Ball charge    
1st compartment 2nd compartment
Amount t
Specific weight t/m3
Composition
90 mm
80 mm
70 mm
60 mm
50 mm
40 mm
30 mm
20 mm
Ball charge compensation
Last date
Amount t

 regarding maintenance cost:

The maintenance cost (including spare parts and man-hours cost) should be
calculated and attributed per mill.
The logging of the parameters as well as the data warehouse management
should be automated and implemented in the Plant everyday procedures.
1.1.1. Material Sampling
As far as the sampling procedure is concerned it is vital to know the Sampling
Points before sampling is needed. The samples are being collected only be those
assigned by plant personnel in order to know the locations (e.g. product, circuit
samples).
Before starting the sampling procedure the access for sufficient size (and
sampler) should be verified. There safety for access (heights, steps, guard rails,
etc) should be assessed whereas the exposure risk to pressure/suction, heat,
dust, etc should be checked.
Finally, all participants should have suitable equipment (PPE, containers, sample
devices, etc) and be aware of moving parts (e.g. rotary valves, screw conveyors).
Note that when in Doubt – ASK!
1.1.2. Gas measurement
In order to calculate the flows at the grinding circuit, the temperature and the
pressure has to be measured. Temperature is being measured using
thermocouples while the pressure (differential and static) is being measured
using Pitot tube. The flows should be depicted at the relevant process flowchart.
1.1.3. Radiation & Convection
In order to evaluate the heat transfer, the heat losses which are being attributed
to radiation and convection has to be verified. In order to calculate the heat loss,
the temperature at the surface of interest is being measured and following the
heat loss is being calculated.

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