OK vertical roller mill
2
Quality & proit improving eatures Main eatures - OK vertical roller mills use 30-50% less energy than ball mill systems - Simple layout and ewer machines in the mill circuit ensure high run-actor and low maintenance costs - Excellent drying capability when grinding blast urnace slag or blended cements with wet components - Roller and table proile improve operating stability and reliability - Consistent cement quality with easy to adjust quality parameters - Special design eatures or iron removal during slag grinding minimise wear - Optimal wear-protection on all internal suraces - Space-saving design reduces civil construction costs - Flexibility to operate with two or our rollers guarantees long term availability
OK 36-4 mill under erection
Application advantages Proven commercially, the OK mill is the premier roller mill or inish grinding o portland cement, slag and blended cements. With a 30-45% reduction in the energy requirements or cement grinding and 40-50% or slag as compared with traditional ball mill operations, the OK mill can contribute signiicantly to your proitability and competitiveness. The design combines the drying, grinding and separation processes into just one unit, thus simpliying the plant lay-
out. A low noise level makes outdoor installation easible, substantially reducing civil construction costs and improving the working environment. Because o its highly eective drying perormance, the OK mill is a natural choice or grinding blended cements with one or more wet components.
Design advantages The OK mill uses a hydro-pneumatic system to press its grinding rollers against the material bed on the rotating grinding table.
3
Product
The grooved roller proile has two grinding zones, an inner and an outer. This creates a high and concentrated grinding pressure on the outer path, allowing air to escape into the grooved centre. The inner path serves to prepare the grinding bed, by compressing the eed material as it moves under the rollers into the high pressure grinding zone.
Feed inlet
Rotary eed sluice Separator
Segmented roller wear parts are made o the hardest possible material without risk o cracking and are very well suited or hard acing. Re-positioning o rollers is possible or evening out wear. These eatures ensure maximum longevity.
Operating advantages The rollers are in a lited position when the mill is started, ensuring trouble-ree start-up. This eliminates the need or an auxiliary drive. A control system monitors the machinery and acilitates operation.
Grinding roller Nozzle ring Grinding table Roller stopper Main hydraulic loading system
Roller shape & curved table prole
Main hydraulic loading system
Swing-out system for roller replacement
4
Mill design or versatile applications, simple operation and long lie
Clinker, gypsum, slag, additive
3
1 OK mill
4 Finished product
3 Bag filter
Cold air intake
Hot air for drying
2 Dynamic separator
2 1
4 Fan
5
5 Magnetic separator
Nozzle
Table
Nozzle ring bypass system For slag grinding, a specially designed nozzle ring bypass allows the iron particles to segregate through nozzles without airlow and subsequently be removed by a magnetic separator to minimise wear o the mill internals.
Air inlet
Discharge chute for iron particles
To magnetic separator
Mill arrangement and nozzle ring bypass system
(%) 100 90
Clinker
80
Gypsum
70
Pozzolana
60
Limestone
50 40
PFA
30
Slag
20 10 0 A+B
C
D
D
E
Plant
OK mill feed composition
E
F
F
Mill arrangement This schematic illustrates a typical grinding installation. The arrangement is very simple and the operation is correspondingly lexible and reliable. To maintain the appropriate temperature in the mill circuit – or example to ensure adequate dehydration o the gypsum when grinding cement – the layout is prepared with provisions or recirculation o hot exit gas to the mill inlet. In case the mill eed is wet slag or includes a signiicant portion o wet additives, additional heat must be provided, or instance rom a heat generator. Otherwise, i the mill eed is very hot, the mill exit temperature controls a damper or cold air intake.
F
One mill, many products The OK mill eiciently grinds blended cements, with a wide range o additives such as slag, puzzolana, limestone and ly ash. Its versatility is demonstrated by the ability to switch between a wide variety o mixes, and to vary the particle size to meet individual needs. Particle size distribution Examples o adjustments o particle size distribution when grinding to the same Blaine surace. The required steepness o the particle size distribution curve is attained by adjustment o the separator rotor speed, the mill airlow rate and the grinding pressure, in combination with the appropriate height o the dam ring.
5
Optimisation o operation Adjustment o mill airlow and grinding pressure or optimisation o the operation, including adjustment o particle size distribution, can be made immediately. Adjustment o the dam ring, however, requires a mill stop, but only or a ew hours. Switching between dierent types o products, or example rom portland cement to slag, only requires easily made operating adjustments. Adjustment o the dam ring is not required. However, i the mill is to operate or a long time with one speciic product only it may be expedient to adjust the dam ring to optimise the mill or operation with this speciic product. Wear liners The wear liners o the grinding table and the rollers are o the segmented type and are thereore easy to replace when worn out. For mills grinding very abrasive materials, like slag, hardacing is an interesting and viable means o achieving a high availability o the grinding system, optimising the grinding process and saving reurbishment costs.
0.1
1
5 10 20 30 40 50 60
) 70 % ( e u 80 d i s e R 90
95 96 97
98
99 1
10
100
Particle size (µm)
OK mill steep PSD
Typical ball mill PSD
Hardacing is an economical alternative to changing wear parts and is very suitable or the high chrome cast iron grinding parts used in the OK mill. Being o the segmented type the wear liners can be hardaced numerous times throughout their lie.
Seal between housing and roller.
Hardfaced segments
OK mill flat PSD
6
Perormance and experience Typical specic energy consumption (kWh/t) motor input Portland cement 2
Blaine (cm
/g)
Slag*
3,300
4,000
4,000
5,000
OK mill
Ball mill
OK mill
Ball mill
OK mill
Ball mill
OK mill
Ball mill
Mill
17.6
34.2
21.3
44.9
25.7
51.8
32.2
71.1
Fan etc.
6.9
3.2
8.3
4.9
9.4
7.6
13.0
12.3
Total
24.5
37.4
29.6
49.8
35.1
59.4
45.2
83.4
*Slag with 8% moisture
2
Examples o compressive strength (kg/cm ) Portland cement 2
Blaine (cm
Blended cement
/g)
3,300
Slag cement* 3,700
4,000
3,800
OK mill
Ball mill
OK mill
Ball mill
OK mill
Ball mill
3 days
155
145
225
220
115
110
7 days
255
245
275
260
195
190
28 days
430
420
350
330
425
425
*50/50 clinker and slag mixture
Typical wear rates (g/t cement) o wear parts Portland cement Roller
Table
Roller
Table
1
1
5
6
0.5
0.5
2.5
3.0
Without hardacing With hardacing *50/50 clinker and slag mixture
Twin mill installation
Slag*
OK 30-4 Installation
7
Dimensions and characteristics The capacity range depends on neness, grindability and additives (types and proportion o mill eed) OK mill
size
25-3
27-4
30-4
33-4
36-4
39-4
42-4
45-4
Mill motor, installed
kW
1350
1800
2350
3000
3750
4600
5500
6500
30
40
50
65
80
100
120
145
3
Airfow, approx., mill outlet
Nm /s
Cement, capacity range
t/h
45-90
60-125
80-165
105-210
130-260
160-315
190-380
225-450
Gear
kW
1544
2161
2829
3590
4446
5412
6488
7763
Output
t/h
51
72
94
119
148
180
216
258
OK mill
size
25-3
27-4
30-4
33-4
36-4
39-4
42-4
45-4
A
m
13.7
13.9
15.5
17.3
19.0
20.6
23.7
26.7
B
m
12.1
12.2
13.5
15.3
16.8
18.4
21.2
23.1
C
m
5.2
6.0
6.7
7.6
8.4
9.2
11.0
12.1
D
m
8.2
7.0
7.8
8.5
9.4
10.2
10.9
11.7
2
Slag at 420 m /kg
Dimensions
OK 33-4 for slag
OK mill number represents mean grinding track diameter
C
B
27-4 30-4 33-4 36-4 39-4 42-4 45-4
25-3
D
D
A
- Proven technology - Flexible operation - Designed or grinding blended cements or slag - Excellent drying capacity - Easy maintenance and optimum utilisation o wear parts
View of rollers inside an OK mill.
Slag mill inspection.
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The OK mill is manufactured by FLSmidth under patent & license from Earthtechnica Co., Ltd & Taiheiyo Cement Corp. Copyright © 2010 FLSmidth A/S. ALL RIGHTS RESERVED. FLSmidth is a (registered) trademark of FLSmidth A/S. This brochure makes no offers, representations or warranties (express or implied), and information and data contained in this brochure are for general reference only and may change at any time.
Project Centre Denmark FLSmidth A/S Vigerslev Allé 77 DK-2500 Valby Copenhagen Tel: +45 3618 1000 Fax: +45 3630 1820 E-mail: in
[email protected]
Project Centre USA FLSmidth Inc. 2040 Avenue C Bethlehem, PA 18017-2188 Tel: +1 610-264-6011 Fax: +1 610-264-6170 E-mail: in
[email protected]
Project Centre India FLSmidth Private Limited FLSmidth House 34, Egatoor, Kelambakkam (Rajiv Gandhi Salai, Chennai) Tamil Nadu – 603 103 Tel: +91-44-4748 1000 Fax: +91-44-2747 0301 E-mail: indiain
[email protected]
www.fsmidth.com
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