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