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Bulk Materials Handling Systems

Technical Development Programme for Process
Performance Engineers 2010

Heiko Polske
HGRS/MPT-ASA

© Holcim Group Support Ltd 2010


Bulk Solids Handling in Cement plants

© Holcim Group Support Ltd 2010

PPE
Course

3
11.05.18 / POL


Belt Conveyors

Terminology

© Holcim Group Support Ltd 2010

PPE
Course

4
11.05.18 / POL


Belt Conveyors

Design Considerations (1/5)
 Belt joint shall be vulcanized
 Trough angle α shall not be less than 30°
 Belt speed:

The maximum belt speed shall not exceed 2.0 m/s
 Conveyors handling dry fine material (i.e. cement) shall not
exceed 1.25 m/s
 Belt speed for conveyors less than 50 meters in length shall not
exceed 1.5 m/s
 Conveyors longer than 500 m can operate above 2 m/s
(Overland Conveyors).
 Trough belt width shall not be less than 800 mm. For special
applications 650 mm belts may be used


© Holcim Group Support Ltd 2010

PPE
Course

5
11.05.18 / POL

Belt Conveyors

Design Considerations (2/5)
 The minimum distance between the center of the

L≥
2xb

tail end pulley and the skirt arrangement shall be
larger than 2*belt width. As a minimum, the skirt
should not start until full troughing of belt has been
achieved

L

 Maximum conveyor slope:

b

Fig. 1: Belt transition phase

Maximum Slope

Raw Material,
wet Slag

Clinker
 

Cement

Coal, PetCoke

16°

10°

6°

15°

6°

0°

0°

5°

All sections other
than loading point
At loading point
Fig. 2: Inadequate design
© Holcim Group Support Ltd 2010

PPE
Course

6

11.05.18 / POL


Belt Conveyors

Design Considerations (3/5)
 Idlers:










Carrier and return idler shall be designed according to DIN
(15207-1 / 22107) or CEMA (Class C or greater)
Carrier and return idler diameter: 100 mm for 650 to 1000 mm
belts, 127 mm for belts greater than 1000 mm
Carrier idler spacing shall not exceed 1250 mm for all belt widths
High-density polyethylene impact bars at loading points shall be
used. Rubber protected impact idlers may be used, with spacing
of no more than 300 mm for all belt widths
Return idler spacing shall not exceed 3000 mm for all belt widths
For conveyors handling sticky materials, return idlers shall be
rubber disc rolls or anti-adhesive rubber tubes

© Holcim Group Support Ltd 2010

PPE
Course

7
11.05.18 / POL


Belt Conveyors

Design Considerations (4/5)
 Pulleys:



All drive pulleys shall have rubber lagging
Tail and take up pulleys: rubber lined or spiral wrapped wing
pulleys. Wing type pulleys without spiral are not acceptable

 Belt tensioning stations:




For belt conveyors less than or equal to 50 m horizontal center
distance, screw tensioning shall be used
For belt conveyors over 50 m horizontal center distance, vertical
gravity or horizontal gravity shall be used

© Holcim Group Support Ltd 2010

PPE
Course

8
11.05.18 / POL


Belt Conveyors

Design Considerations (5/5)
 Skirtboards and dust hood:




Wear liners shall be installed to the inside and dust hoods shall
not extend less than 2 m from loading point
Skirtboards shall be equipped with adjustable sealing rubber
stripes or pads and shall be of the quick release type for easy
adjustment

 Covers:




Conveyors or parts thereof installed outside of buildings shall be
covered
For conveyors handling dry fine material (e.g. cement) the lower

edges of the covers must extend to 300 mm below the return belt
line

© Holcim Group Support Ltd 2010

PPE
Course

9
11.05.18 / POL


Belt Conveyors

Belt training idlers
 Carrying Side

 Return Side

© Holcim Group Support Ltd 2010

PPE
Course

13
11.05.18 / POL


Belt Conveyors

Belt training idlers

Belt trackers tied off to
the supporting
structure
© Holcim Group Support Ltd 2010

Pivot bearing with simple O-ring seal

PPE
Course

14
11.05.18 / POL


Belt Conveyors

Belt Cleaners
Piles of spillage > Cleaners not performing well

Cement

Raw material
Coal
© Holcim Group Support Ltd 2010

PPE
Course

15
11.05.18 / POL


Belt Conveyors

Belt Cleaners
Tail pulley

Head pulley

V Plough
Primary

© Holcim Group Support Ltd 2010

Secondary

PPE
Course

16
11.05.18 / POL


Belt Conveyors

Belt Cleaners

Homemade solutions

> in most cases they perform poorly
> can even damage the belt

© Holcim Group Support Ltd 2010

PPE
Course

17
11.05.18 / POL


Belt Conveyors

Belt Cleaner_V-Plough

Idlers to keep the belt flat

Flexible pressure to allow permanent
contact with the belt surface
© Holcim Group Support Ltd 2010

PPE
Course

18
11.05.18 / POL


Belt Conveyors

Belt Conveyor

Material accumulated to the pulley surface

© Holcim Group Support Ltd 2010

High local stress
concentration

PPE
Course

19
11.05.18 / POL


Belt Conveyors

Skirtboard Seal

Multiple layer seal systems provide best efficiency,
but…..

© Holcim Group Support Ltd 2010

PPE
Course

20

11.05.18 / POL


Belt Conveyors

Skirtboard Seal
…before installation make sure there is sufficent seal
distance available

© Holcim Group Support Ltd 2010

PPE
Course

21
11.05.18 / POL


Belt Conveyors

Belt Conveyor
 Sealing blocks, easily adjustable but…..

Acceptable as
tail seal

© Holcim Group Support Ltd 2010

PPE
Course

22
11.05.18 / POL


Apron
Conveyors

Apron Feeder

 Incorrect design of feed chute

Material between chute
and side walls
© Holcim Group Support Ltd 2010

PPE
Course

24
11.05.18 / POL


Apron
Conveyors

Apron Feeder
 Damage of side walls

© Holcim Group Support Ltd 2010

PPE
Course

25
11.05.18 / POL


Apron
Conveyors

Apron Feeder
Chute

Liner

© Holcim Group Support Ltd 2010

PPE
Course

26
11.05.18 / POL


Bucket
Elevators

Bucket Elevators
 Toothed design can promote material build ups on

buckets

tootheed lip

© Holcim Group Support Ltd 2010

Material build up on bucket

PPE
Course

27
11.05.18 / POL


Bucket
Elevators

Bucket Elevators
Rubber skirts
> Almost no improvement

Round link chain

PU Coating
> Exspensive
> Almsost no improvements

© Holcim Group Support Ltd 2010

PPE
Course

28
11.05.18 / POL


Bucket
Elevators

Bucket Elevators

Buckets completed blocked

Bucket made from rubber
> Showed best results
© Holcim Group Support Ltd 2010

PPE
Course

29
11.05.18 / POL


Bucket
Elevators

Bucket Elevators

Bucket Elevator Casing:
Rubber instead of sheet metall
plates

© Holcim Group Support Ltd 2010

PPE
Course

30
11.05.18 / POL