Lumps form in cement silos due to several factors: 1) High temperature cement being conveyed into silos, causing dehydration and moisture movement; 2) Entry of humid air which hydrates fine cement; 3) Rough silo surfaces allowing hydration and dislodging of cement. To prevent lumps, the document recommends: reducing cement temperature to below 80°C when conveying; reducing storage time; improving silo ventilation; and adding anhydrate gypsum to slow hydration. Proper silo coating and maintenance can also help reduce lumps forming over time in cement silos.

1. Lump formation in
cement silos

2. Lumps formed in
cement silo

3. Reasons for Lump formation in cement silo
Entry of humid
Temperature of
Air through aeration
cement
Blowers and lack of
venting
surface conditions
Of cone and the Entry of moisture
Side walls Along with
cement
SO3 and Alkalis Storage time of
In the cement in the cement

4. Temperature of cement
Cement temperature must be less than 80 Deg C when
conveyed into silo. If it is more than 80 deg C the crystalline water
from Gypsum gets dehydrated and moisture moves to the colder
part ie center cone and the walls .This moisture Hydrates the fine
cement and causes cake formation. Presence of alkalis
acclerates prehydration.In our clinker K2O+ Na2O is 0.8. In
cement 0.63 (PPC) and SO3 is 1.8 %.The coating formed is
Called Syngenite( K2SO4.CaSO4.H2O)

5. Intensity of coating formation as a function
Of cement temperature stored in cement silo
100
Percentage of heaviest coating
80 SO3=2.7 %
260 M2/kg
60
40
20
0
60 80 100 120 140
Cement temperature Deg C , stored

6. Effect of surface on lump formation
If surface of the inner cone and side walls are rough cement
make dead layer and over a period of time they get hydrated
And dislodged causing blockage.
To have a glassy surface, the walls and floor are coated with
epoxy Or materials which can form fine surface which
facilitates smooth out flow flow of material

7. Storage time
High storage time and high cement temperature, both can
aid cake formation.
Our cement in silo 4 and 5 is more than 12 days In silo 3 it is 2 to 3
days.

8. Effect of gypsum content on cake formation
Higher gypsum addition or higher SO3 in cement accelerates the hydration
of cement In silo. Anhydrate gypsum reduces coating formation ie., Caso4
Our cement

9. Addition of anhydrate
(Gypsum without water)
Can reduce lump
Formation in silo.
Ratio of anhydrate/gypsum(CaSO4.2H2O) ratio

10. Ultimate solution
1. Reduce the cement temperature from 90 deg C to 70
step by step
2. Reduce the storage time present 10 days to 6 days
3. Silo venting must be on when cement is extracted and
aeration is done. When RH is high It can accelerate
the hydration

11. Thanks for your kind attention
K.P.PRADEEP KUMAR
Sr G M Operation
Chettinad cements Ltd
Karikkali works