Mill check up
Preparation of the visit
1. mill must be running steadily (4h)
2. mill must be crash stopped
3. ask for the coarsest cement to be produced
(generally highest mill output)
Equipment to foresee
Circuit : thermometer / anemometer
plastic bags
Cpt 1 : buckets of 5 to 10 L / scoop / light
Cpt 2 : buckets of 1 L / plastic bags / sieve, scoop
Check up Procedure
1. Technical data sheet
2. 2 to 3 hours survey when mill steady
3. Parameters are collected every hour
4. Samples are collected every hour and before crash stop.
The installation is visited at work.
5. Mill must be crash stopped
6. Both compartments are visited and examined
7. Samples are collected in the mill
8. Separator visit
Survey before crash stop
Technical Data Sheet
Flow sheet
Ball charge history
Dailyproduction time
Sheet history
Auxiliary capacities
C P J 3 5 C P J 4 5 C I R C U I T F E E D I N G O u tp u t ( d u r i n g t h e v i s i t ) 3 0 t p h A v e r a g e i n J u n e ( 2 8 .9 t p h ) ( 2 7 .0 9 t p h ) % H 2 0 T ° C C l i n k e r a m b ie n t 6 1 % 7 7 % G y p s u m 2 . 5 % a m b ie n t 6 % 6 % L i m e s to n e 3 .5 % a m b i e n t 3 3 % 1 7 % F I N I S H P R O D U C T F in e n e s s ( t a r g e t) 2 0 - 2 4 % R 4 0 µ 1 5 - 2 0 % R 4 0 µ A B S O R B E D P O W E R M o t o r a m p s ( A b s o r b e d p o w e r ) 6 0 A m p ( 7 1 0 k W ) 6 0 A m p ( 7 1 0 k W ) S p e c i f i c p o w e r 2 3 .6 k W h / t ( 2 4 .5 k W h / t ) ( 2 6 .2 k W h / t ) S E P A R A T O R T y p e F r e s h a i r d a m p e r 5 0 % o p e n 5 0 % o p e n A i r f lo w 3 6 0 0 0 m 3 / h 3 6 0 0 0 m 3 / h A i r r e c i r c u l a t io n d a m p e r 1 0 0 % o p e n 1 0 0 % o p e n R e j e c t o u tp u t C a g e s p e e d ( 1 0 - 4 0 r p m ) 2 0 r p m 2 4 r p m M I L L D E D U S T I N G A c tu a l a i r f l o w 2 5 0 0 0 m 3 / h 2 5 0 0 0 m 3 / h D a m p e r p o s i t i o n 1 0 0 % 1 0 0 % D e p r e s s io n a t m i l l i n l e t D e p r e s s io n a t m i l l o u t l e t M I S C E L L A N E O U S E a r y e s y e s
Survey before crash stop
Main parameters
0
9 mm
10 mm
1
2
3
4
Sampling : separator & filter
5
6
7
Internal Visit of the Mill
Sampling in the mill
To excavate !
3x on the width
4x on the length Cpt 1
6x on the length Cpt 2
Collecting of
samples
Grinding balls
characteristics
Internal Visit of the Mill
Filling
degree
Internal Visit of the Mill
A
H
1
S
T
H
S
T
= p x D
2
/4
m
2
H
1
= H - D/2
m
A = 2ARCOS(2 x H
1
/D)
°
S
1
= D
2
/8 x (p x A/180° - sinA)
R = S
1
/S
T
x 100
m
2
%
S
1
Filling
degree
Internal Visit of the Mill
Measured filling degree
Filling degree (%) / H/D
0.55
0.6
0.65
0.7
0.75
0.8
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
H
/D
D
H
Grates slots size
check up
Cpt. length and
liner thickness
Internal Visit of the Mill
Discovery of unground
particles &
untightened grates
Internal Visit of the Mill
Material level and
filling degree in 2
nd
cpt.
Other various
measurements
Internal Visit of the Mill
• Space between blades and external casing
• Fan general condition
• Seals and valves general condition
• Holes in distribution plate
• Coating
• Wear follow up.
Theoretical curves
CUMULATIVE PERCENT RETAINED
0
5
10
15
20
25
30
35
1
2
3
4
5
6
7
8
9
10
1/2"
1/4"
8 M
16 M
30 M
50 M
100 M
200 M
5,0% 10,0% 15,0% 20,0% 25,0% 30,0% 35,0% 40,0% 45,0% 50,0% 55,0% 60,0% 65,0% 70,0% 75,0% 80,0% 85,0% % R e ta in e d 1/2 #4 #8 #16 #30 #50 #100 #200 P a rt it io n
3.66 m x 10.97 m 2162 kW
0,0% 5,0% 10,0% 15,0% 20,0% 25,0% 30,0% 35,0% 40,0% 45,0% 50,0% 55,0% 60,0% 65,0% 70,0% 75,0% 80,0% % R e ta in e d 1/2 #4 #8 #16 #30 #50 #100 #200 P a rt it io n
3.66 m x 10.97 m 2162 kW
5,0% 10,0% 15,0% 20,0% 25,0% 30,0% 35,0% 40,0% 45,0% 50,0% 55,0% 60,0% 65,0% P e rc e n t R e ta in e d 1/2" 1/4" #8 #16 #30 #50 #100 #200 P a rt it io n
5.18 m x 10.36 m 4100 kW
CUMULATIVE OVERSIZE DISTRIBUTION (%)
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 CH1/1 CH1/2 CH1/3 CH1/4 CH2/1 CH2/2 CH2/3 CH2/4 CH2/5 CH2/6 10 2.36 1.18 0.6 0.3 0.09 0.044Granulometric curves
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 1/1 2/1 3/1 4/1 5/1 1/2 2/2 3/2 4/2 5/2 6/2 7/2 8/2%
c
u
mu
la
ti
v
e
r
e
s
id
u
e
18 mm 11,2 mm 8 mm 4 mm 2,8 mm 1 mm 0,5 mm 0,25 mm 0,15 mm 0,1 mm1 99 98 97 96 95 90 85 80 70 60 50 40 30 20 15 10 5 3 2 4
characteristics
d75...: 78.90 µ d50...: 60.58 µ d25...: 46.52 µ Imperfection...: 26.73 % dl...: 10.00 µ #N/A99.9 99 95 90 80 70 63.2 50 40 30 20 15 10 5 4 3 2 1 0.5 0.1 1 10 100 1000 0.1 1 5 10 20 30 36.8 50 60 70 80 85 90 95 96 97 98 99 99.5
Filter
Rejects
Separator
feeding
finish
Product
Fines
Granulometric curves
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 1/1 2/1 3/1 4/1 5/1 1/2 2/2 3/2 4/2 5/2 6/2 7/2 8/2%
c
u
mu
la
ti
v
e
r
e
s
id
u
e
18 mm 11,2 mm 8 mm 4 mm 2,8 mm 1 mm 0,5 mm 0,25 mm 0,15 mm 0,1 mmA
H
1
S
T
H
S
T
= p x D
2
/4
m
2
H
1
= H - D/2
m
A = 2ARCOS(2 x H
1
/D)
°
S
1
= D
2
/8 x (p x A/180° - sinA)
R = S
1
/S
T
x 100
m
2
%
S
1
Filling degree
PLANT :
OBOURG
SAMPLE :
cement
SEPARATOR :
SD150
DATE :
24/03/1994
dim.
feed
fines
rejects
efficiency
dim
effic. (i)
tromp
µ
% P
% P
% P
%
µ
%
%
2
5.92
12.93
3.03
77.83
1
63.77
29.74
4
10.26
22.95
4.78
79.71
3
72.2
24.04
8
15.87
36.26
6.13
81.41
6
84.58
15.43
16
23.67
55.23
7.69
83.15
12
87.12
12.97
20
27.32
63.23
8.72
82.47
18
82.5
18.79
25
32.33
72.6
11.03
80.02
22.5
71.44
30.87
30
37.73
80.74
14.64
76.25
27.5
59.74
44.42
45
55.39
95.67
33.21
61.55
37.5
21.27
69.21
60
70.56
99.99
52.25
50.49
52.5
7.49
88.83
75
81.55
100
66.6
43.7
67.5
0.01
99.98
80
84.25
100
70.13
42.3
77.5
100
90
88.65
100
76.37
40.2
85
100
120
94.83
100
85.95
37.57
105
100
200
96.6
100
94.51
36.89
160
100
210
96.6
100
95.01
36.89
205
100
Blaine :
1324 cm2/gr 3778 cm2/gr 715 cm2/gr
Circulating load : 2,81
correlation : 0,9681
vf : 0,356
vg : 0,644
1 10 100
tr
o
m
p
%
Characteristics d75...: 36,32 µ d50...: 26,45 µ d25...: 19,26 µ Imperfection : 32,25 % dl...: 14,41 µ by-pass....: 11,28 %d75
d50
d25
dl
b
y
-p
a
s
s
PLANT :
OBOURG
Mill :
3 diam. 5,2m
Date :
25/03/1994
% passing
sep. inlet
Fines sep.
sep. rejects
Filter blaus.
finish product
Sieve (µ)
0.7
1.90
4.46
0.90
1.4
4.69
10.03
2.48
2
5.92
12.93
3.03
3.2
8.62
19.19
4.19
4
10.26
22.95
4.78
8
15.87
36.26
6.13
12
20.06
46.56
7.00
18
25.39
59.15
8.06
30
37.73
80.74
14.64
45
55.39
95.67
33.21
56
66.86
99.13
47.75
70
78.47
100.00
62.79
90
88.65
100.00
76.37
110
93.76
100.00
83.64
135
96.08
100.00
88.80
165
96.60
100.00
92.27
210
96.60
100.00
95.01
260
96.60
100.00
96.20
0.10 1.00 10.00 100.00 P a s s in g % sep. inlet Fines sep. sep. rejects