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TUBE MILL AUDIT
• Information required before hand.
• Data to be collected from site.
• Mill inspection.
Technical services Tube mill audit
• Process flow sheet of the milling system with gas and material flow.
• Auxiliary equipment characteristics as per following table.
• Tube mill general dimensional data and historical data of mill internals retrofitting.
• Major difficulties limiting performance of system. (Mill is consuming higher power, mill is not achieving its rated capacity etc.)
Equipment Type Make Power (KW) Critical dimensions
Output (TPH)
Rated Actual Rated Actual
Suction fan ABB 40 35 60,000 cum/hr
Bucket elevator Chain BHA 30 40 25m hight 100 80
INFORMATION REQUIRED BEFORE HAND
Technical services Tube mill audit
DATA TO BE COLLECTED FROM SITE
Manual check at site :
• Mill RPM - Matching with design value.• Sound level of the mill. - Matching with control room value.• Ventilation at inlet of the mill. - High,Medium,Less,No• Damper position of all the fans. - Matching with control room value. • Leakages from the mill, circuit. - High, Less and where, No leakages.• Feed condition. - Matching with design value.• Mill motor power meter. - Matching with control room value.
Technical services Tube mill audits
Collect the trend data of circuit parameters:FM#6 log sheet of last 24 hrs.
0.00
50.00
100.00
150.00
200.00
250.00
8/20/2003 19:12 8/21/2003 0:00 8/21/2003 4:48 8/21/2003 9:36 8/21/2003 14:24 8/21/2003 19:12 8/22/2003 0:00
Parameters
HO
urly
read
ings
4000.00
4100.00
4200.00
4300.00
4400.00
4500.00
4600.00
4700.00
4800.00
4900.00
Sep power BE Kw Sep Speed Mill o/l draft Out temp Mill fan Kw S Fan X 10
Sep damper Mill damper D dust fan D dust damper Rej TPH Feed TPH Mill motor
Technical services Tube mill audits DATA TO BE COLLECTED
FROM SITE
A B
C
D
E FG H
A,B,C : Feed sample :10 kg 1 test D-H : Circuit sample : 0.5kg 3 times every 2 hours
Technical services Tube mill audits DATA TO BE COLLECTED
FROM SITE – CIRCUIT SAMPLE
Sample Quantity Particle size analysis, sieves, moisture
A Clinker 10 [kg] 50, 25, 16, 8, 4, 2, 1, [mm]
B Gypsum 10 [kg] 50, 25, 16, 8, 4, 2, 1, [mm] + %H2O
C Other add. 10 [kg] 50, 25, 16, 8, 4, 2, 1, [mm] + %H2O
D Mill outlet
E Separator reject
F Separator product0.5 [kg] 212µm,90µm,45µm, Blaine manual ~1- 200 [µm] Laser
G Filter product
H Finish product
Technical services Tube mill audits DATA TO BE COLLECTED
FROM SITE – ANALYSIS OF SAMPLES
MILL INSPECTION
• Crash stop.
• Chamber sampling.
• Internal dimensions.
• Internal inspection.
Technical services Tube mill audits
The ‘crash stop’ must be made on stable operation of the mill and circuit.
Crash stop means simulateneous stappage of:
Mill feed
Mill
Mill fan
Technical services Tube mill audits
MILL INSPECTION – CRASH STOP
Chamber I Chamber II
1 2 3 4 5 1 2 3 4 5 6
• Dig around ½’ deep transverse trench inside the grinding media at each sample location.
• 1-2 Kg sample at each point
• Get samples from the level of grinding media.
• 0.5 Kg sample at each point
50cm 100 cm 150 cm
50cm
Technical services Tube mill audits
MILL INSPECTION – CHAMBER SAMPLES
MILL INSPECTION - SIEVES IN CHAMBER SAMPLE ANALYSIS
% residue accumulated Sieve [mm] Blaine
Sample 16 10 5 2.5 1 0.5 0.2 0.12 0.09 0.045 cm2/g
1. Chamber 1
2
3
4
2. Chamber 5
6
7
8
9
10
11
Technical services Tube mill audits
Technical services Tube mill audits MILL INSPECTION –
INTERNAL DIMENSIONS
Empty running condition Material lacking condition
Optimum material level Higher material level
Technical services Tube mill audits
Direction of rotation
Direction of rotation
Direction of rotation
Direction of rotation
MILL INSPECTION – MATERIAL LEVEL
Head liner : Remaining thickness min. 40mm for HiCrPreferential wear check
1st chamber liner : Breakage, Lost plate, Coating on linerResidual lifting height : 50%Bolt breakage
Grinding media both chamber : Breakage, Wear, De-shapingMaximum and minimum size of GMCoating on grinding media
2nd chamber liner : Breakage, Lost plate, Coating on linerResidual thickness : 50%Bolt breakage
Diaphragm slot and blind plate : Remaining thickness minimum 25mm.Slot chocking,Breakage or crack,Preferential Wear,Coating on Liner
Diaphragm structure:Gaps between structure,Bolt breakage,Crack on structure,Flexibility,Level controlling device
Technical services Tube mill audits
MILL INSPECTION – WEAR CONDITION