8/17/2019 Annual Audit of CM 1
1/26
Process & Production Department
Annual Audit of Cement Mill 1
September 2015
BMIC
8/17/2019 Annual Audit of CM 1
2/26
Contents:
1- Filling Degree
2- Ball weight Method
3- Power Drawn
4-
Axial test ( granulometry curve )5- Separator Efficiency
6- Wear rate calculation
7- Ball charge sampling ( classification curve )
8- Quality Audit
9-
Mill Visit results10- Mill photos
11- Conclusion of audit
8/17/2019 Annual Audit of CM 1
3/26
1- Filling Degree
Cement Mill 1 Chamber 1 Chamber 2Charge % 90 90
Effective Comp. Diameter m 4.44 4.47
Effective Comp. Length m 4.5 9.75
Free Height , H m 3.07 3.006
Center Distance h = H-D/2 m 0.850 0.771
H/D % 0.691 0.672Filling Degree Q % 26.9 29.0
Bulk Weight [ W ] t/m3 4.3 4.5
Volume Of Compartment [ V ] m3 68.86 152.93
Charge F=q/100 × W × V t 79.7 199.6
Original Charge t 86.75 204.85
Charge Difference
t 7.1 5.25
8/17/2019 Annual Audit of CM 1
4/26
2- Ball weight Method
Ball weight method
Chamber 1 Chamber 2
Useful length 4.45 m 9.75 m
Type of lining Step shell , lifting Corregator , classifying
Type of diaphragm Intermediate Outlet
Diaphragm slots width ( Design ) Not Determined mm Not Determined mm
Diaphragm slots width ( Actual ) Not Determined mm Not Determined mm
Ball charge in metric tons ( Original) 86.75 t 204.92 t
Current Calculated Charge by ball sampling Method
Current Original Current OriginalDiameter 90mm 21.17 23.00
Diameter 80mm 27.55 28.90
Diameter 70mm 20.01 21.25
Diameter 60mm 11.65 13.60 20.05 20.35
Diameter 50mm 0 10.05 10.25
Diameter 40mm 9.84 10.20
Diameter 30mm 20.08 20.40
Diameter 25mm 28.46 30.60
Diameter 20mm 48.71 51.05
Diameter 17mm 57.82 62.05Total 80.39 86.75 195.01 204.90
Filling degree 26.9 % 29 %
required tonnage -6.36 ton -9.91 ton
Total charge required , ton -16.27
8/17/2019 Annual Audit of CM 1
5/26
3- Mill Power Calculation
NET KW = 0.2846 DAWN
Chamber 1
D 4.44 Internal Diameter of Mill
A 0.804 1.073 - J
W 79.66 Charge weight in Tonnes
N 15 Mill speed in RPM
Net KW 1213.9 0.23
Gross KW 5200
Chamber 2
D 4.47 Internal Diameter of Mill
A 0.783 1.073 - J
W 199.57 Charge weight in Tonnes N 15 Mill speed in RPM
Net KW 2981.92 0.58
Gross KW 5200
8/17/2019 Annual Audit of CM 1
6/26
Total mill
Total Net absorbed Power, kw 4195.81
Net KW / Gross Kw ( mill) 0.81
Estimated power loss 0.073higher KW/t by 7.3 %
power loss % 7.3
Conclusion :
7.3 % power loss means that the consumption has increased by about 2 – 3 kw/t due to running mill with low
filling degree (Ch. 1) or low feed rate
8/17/2019 Annual Audit of CM 1
7/26
4- Axial test ( granulometry curve )
Note: Axial test has been done for 2 chambers using complete sieve shaker ( 7 sieves )
NoBlaine
cm2/gm850µ 212µ 150µ 90µ 75µ 45µ 36µ
chamber(1)
1 22.2 39.8 46.4 50.2 60.8
2 17.0 40.2 46.8 50.8 59.4
3 11.8 32.2 39.0 44.6 54.4
4 5.4 33.8 41.6 50.8 60.4
Diaphragm5.0 33.2 41.2 44.4 53.6
chamber(2)
5 2.0 21.0 30.0 38.4 47.8 46.4 58.6 1417.0
6 1.6 18.8 28.6 38.2 48.2 48.2 56.4 1361.0
7 1.8 17.2 25.6 33.4 43.2 63.8 68.4 1470.0
8 1.0 13.4 20.4 26.8 35.6 62.0 67.8 1757.0
9 0.8 9.2 15.8 21.8 32.0 54.6 59.8 1925.0
10 0.4 11.2 17.8 24.4 34.8 52.8 60.8 2004.0
11 0.6 7.0 13.2 19.4 28.0 53.8 62.0 1925.012 0.4 6.4 13.2 20.6 31.2 53.6 60.8 2004.0
13 0.2 5.8 10.2 14.2 23.8 50.6 59.0 2485.0
14 0.2 5.2 9.2 14.4 22.4 39.2 47.8 2422.0
Diaphragm 0.2 1.4 5.8 10.2 17.6 46.6 54.2 2223.0
8/17/2019 Annual Audit of CM 1
8/26
Axial test and Blaine Curve
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
1 2 3 4 Diaphram 5 6 7 8 9 10 11 12 13 14 Diaphram
850µ
212µ
150µ
90µ
75µ
I n t e r m e d i a t eD i a p h r a
m
O u t l e t D i a p h r a m
8/17/2019 Annual Audit of CM 1
9/26
The results analysis from both curves :
It seems from the curve that the size reduction and Blaine are good through the mill chambers
but there are some points have to be taken in consideration as following:
0.0
500.0
1000.0
1500.0
2000.0
2500.0
3000.0
5 6 7 8 9 10 11 12 13 14
B l a i n e
c m 2 / g
Effective Length ( m )
2nd Chamber Chart (Blaine cm2/g)
blaine
cm2/gm
8/17/2019 Annual Audit of CM 1
10/26
1- Point 1 & 2 : A slight flat curve means that Ѳ 90 & 80 need to be charged
2- Point 3 : means that the combination of Ѳ 80 & 70 has a good performance
3-
Point 4 : prove that the quantity of Ѳ 60 is so less to play its role and from wear rate calculation
method shown the most high wearable balls is Ѳ 60 and from visual inspection shown that amount
of Ѳ 60 is less , so we have to add Ѳ 60 grinding balls to Ch 1
4- Very small Clinker nibs at intermediate diaphragm and by adding Ѳ 90 & 80 , it will disappear totally
5- Point 5 & 6 , Show a poor preparation of Ѳ 60 from 1st
chamber which make the curve little flat and
it will disappear by adding Ѳ 60 to chamber 1
6- Point 10 & 12 show a sharp raise where by visiting mill in both points there is unclassified balls
where Ѳ 60 & 50 was there which interrupt the curve
7- A size reduction at the last of chamber 2 shows the small balls Ѳ 30 & 25 & 20 & 17 have a good
performance
Conclusion:
1- Chamber 1 : add 2 ton Ѳ 90 and 2 ton Ѳ 80 and 2 ton Ѳ 60
2- Chamber 2 : not recommended to add grinding media as high filling degree 29 % also the level of
balls have reached to the outer diameter of the ventilation grid
8/17/2019 Annual Audit of CM 1
11/26
5- Separator Efficiency
Passing %Separator
feed a , Mill
outlet ( % )
Fine fraction
f ( % )
Coarse fraction
g , tail (%)
Circulation
factor
Separator
Efficiency
36µ 61 75 39.4 1.65 74.6
45µ 77 92.6 51.4 1.61 74.7
75µ 77.2 93 52 1.63 74.0
90µ 87.4 95.6 67.2 1.41 77.8
150µ 93.2 96.6 79.8 1.25 82.7
212µ 98.4 98.8 97.2 1.33 75.3
850µ 99.8 100 99.2 1.33 75.2
Sum 594 651.6 486.2 1.53 71.5
Blaine cm2/g 2004 3241 1303
Conclusion of the test:
The circulation load of the mill is about 1.53 which show a good performance of both mill
chambers with feed 140 – 145 t/h also the Separator Efficiency is about 71.5 % which
show a good separator role
8/17/2019 Annual Audit of CM 1
12/26
6- Wear rate calculation :
size
one ball
original
weight
(kg)
TonnageQuantity
of Balls
Quantity of
collected
samples
from mill
weight of
samples
collected
from mill
(kg)
average
wt. of
one ball
(Kg)
loss on
one ball
(gr)
% of
wear
per ball
Current
Ball Wt
in mill
total charge
weight required
( ton)
1st Chamber
90 ø 3.00 23.00 7667 43 118.759 2.76 0.24 7.9 21.17 1.83
80 ø 2.10 28.90 13762 44 88.09 2.00 0.10 4.7 27.55 1.35
70 ø 1.41 21.25 15071 50 66.38 1.33 0.08 5.8 20.01 1.24
60 ø 0.888 13.60 15315 15 11.414 0.761 0.13 14.3 11.65 1.95
Total ( 1st chamber )
Wear rate86.75 51815 284.6 80.39 6.36
2nd Chamber
60 ø 0.888 20.35 22917 29 25.38 0.875 0.01 1.5 20.05 0.30
50 ø 0.514 10.25 19942 19 9.58 0.504 0.01 1.9 10.05 0.20
40 ø 0.263 10.20 38783 41 10.41 0.254 0.01 3.5 9.84 0.36
30ø 0.111 20.40 183784 410 44.79 0.109 0.00 1.6 20.08 0.32
25 ø 0.064 30.60 476636 765 45.68 0.060 0.00 7.0 28.46 2.14
20 ø 0.033 51.05 1556402 2240 70.10 0.031 0.002 4.6 48.71 2.34
17 ø 0.020 62.05 3071782 2811 52.91 0.019 0.0014 6.8 57.82 4.23
Total ( 2st chamber )
Wear204.9 5370245 258.8 195.01 9.89
Total mill291.7 5422060 275.4 16.2
8/17/2019 Annual Audit of CM 1
13/26
Wear rate summary:
Current Ball charge 275.4 ton
Original charge 291.6 ton
Ball Added to mill till now 14.7 ton
Total mill production , 2014 -2015 1,414,927 tontons added to 1st
chamber7.5
wearable tons during operation 30.85 tonTons added to 2nd
chamber7.2
Mill wear rate g/t21.8 gr/t
1st chamber wear rate9.76 gr/t
2nd chamber wear rate12.08 gr/t
8/17/2019 Annual Audit of CM 1
14/26
7- Ball charge sampling ( classification curve )
Ball charge sampling ( mass % )ɸ / meter 1 m 2.5 m 4 m 4.5 m 6 m 7.5 m 9 m
ɸ 60 31.9 7.4 0.0 1.7 6.5 4.8 0.0
ɸ 50 8.9 4.1 0.0 2.9 2.8 1.1 0.0
ɸ 40 2.8 10.6 0.0 2.0 1.4 4.4 0.0
ɸ 30 0.0 18.0 8.2 16.4 9.2 40.6 13.2
ɸ 25 15.6 23.1 21.9 30.3 16.3 12.1 13.4
ɸ 20 15.8 22.7 69.9 30.6 30.6 21.9 29.2
ɸ 17 24.9 14.1 0.0 16.1 33.1 15.1 44.3
Curve of balls gradation in 2nd
chamber ( Ѳ 60,50,40 )
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
1 m 2.5 m 4 m 4.5 m 6 m 7.5 m 9 m
ɸ 60
ɸ 50
ɸ 40
8/17/2019 Annual Audit of CM 1
15/26
Curve of balls gradation in 2nd
chamber ( Ѳ 30, 25, 20, 17 )
Summary of curve:
Classification of the balls in 2nd
chamber is unclassified well where some bigger balls at end ofchamber and smaller at beginning of the chamber
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
1 m 2.5 m 4 m 4.5 m 6 m 7.5 m 9 m
ɸ 30
ɸ 25
ɸ 20
ɸ 17
8/17/2019 Annual Audit of CM 1
16/26
8- Quality Audit
Quality
Feed components Clinker Gypsum Additives
percent % 88.5 6.5 5
cement Temperature 115 - 125 C
Clinker mineralogy % C3S 50 - 52 %C4AF 11.83
% C2S 21 – 24.0 %C3A 7.85
Note : C2S is little higher which need more grinding efficiency and draw more
power consumption
Blaine 3136 cm2/gr
Residue 90µ 0.6 %
Residue 45µ 13 - 14.5 %
8/17/2019 Annual Audit of CM 1
17/26
9-Mill Visit results : 1st Chamber
Measured volume load 26.7 %Lining condition there is displacement in some rows and a “ Domino Effect “ appear in plates
Maximum ball diameter 90 mm
Minimum ball diameter 56 mm
Ball charge condition Regular with normal worn out
Material level under/over balls Moderate/little Over , 1/4 ball appear
Coating on lining Very slight
Coating on balls Slight
Uncrushed particles at the
diaphragmA bit
Diaphragm condition Semi- Blocked and Need to routine clean
Maximum width of slotsNot Determined
Wear rate of lining plates Not Determined
Slots blocked Semi- Blocked
Central screen condition No Screen found and new fabricated one has a large Slot width ( 9 – 13 mm )
8/17/2019 Annual Audit of CM 1
18/26
1st
Chamber Photos:
8/17/2019 Annual Audit of CM 1
19/26
8/17/2019 Annual Audit of CM 1
20/26
8/17/2019 Annual Audit of CM 1
21/26
9- Mill Visit results : 2nd
Chamber
Measured volume load 29 %Lining condition Regular , but a slight Coat there
Maximum ball diameter 58 mm
Minimum ball diameter 15 mm
Ball charge condition Regular with normal worn out
Material level under/over balls Over 4 -6 cm
Coating on lining Slight Coat
Coating on balls There is a coat layer on Balls due to High CM temp + Higher water flow
Uncrushed particles at the diaphragm A bit
Outlet Diaphragm condition Good and slight blocked
Maximum width of slots Not Determined
Wear rate of lining plates Not Determined
Ball Classification Un Classified Well
Central screen condition Good
Water Nozzle 5 cm gap between diaphragm and flange / allow for escaping small balls
8/17/2019 Annual Audit of CM 1
22/26
2nd
Chamber Photos:
8/17/2019 Annual Audit of CM 1
23/26
8/17/2019 Annual Audit of CM 1
24/26
8/17/2019 Annual Audit of CM 1
25/26
11 - Conclusion of Audit: Recommended actions
1-
Addition of 2 tons for each Ѳ 90 & Ѳ 80 & Ѳ 60 for 1
st
chamber2- Not recommended now to add grinding media to 2
nd chamber as high filling degree and level of
balls near to ventilation grid
3- Measuring Slots width for both diaphragms not determined ( Recommended )
4-
A good Separator Efficiency which is about 71 % and By- pass 19 %
5- A circulation factor is about 1.53 which is good
6-
Mill wear rate is about 22 gr/t
7-
High C2S phase means more energy for grinding
8-
High Power consumption by 2- 3 kwh/t
9- Physical Condition of grinding balls in 1st
chamber is good except Ѳ 60 mm where more
deformation there
10- Displacement of some rows in 1st
chamber is observed , fast action to adjust it is
recommended
11-
Measuring the lifting lining wear rate nor determined , ( recommended )
12- Observed wear rate for head liner of 1st
chamber
13-
A bit clinker nibs at intermediate diaphragm has observed
14- Condition of intermediate diaphragm is semi blocked and need routine cleaning
8/17/2019 Annual Audit of CM 1
26/26
15- Intensive follow up of metal trap to eliminate the scrap from mill which block the diaphragm
16- The new fabricated ventilation grid has a higher Slot width bigger than inter. diaphragm slot
width which allow for escaping the oversize particle to 2nd chamber17- Physical Condition of grinding balls in 2
nd chamber is good
18-
Observed coat formation layer on the 2nd
chamber grinding media & liners due to operation
mill with higher cement temperature or higher water flow or low ventilation, recommended
controlling temp. or using a grinding aid
19- The classification of the grinding media in 2nd
chamber is not good but can consider accepted
20-
The space 5 cm between water nozzle flange and outlet diaphragm will allow for escapingmore fine media to the 1
st chamber, recommended to close the gap.
21- The condition of diaphragm is accepted but need a routine cleaning for improving the
performance
22- Slot width of outlet diaphragm not determined , recommended to measure
23- Lining wear rate for 2nd
chamber not determined , recommended to measure
CM 1 Audit 2015