Reasons for Lump formation in cement silo Entry of humid Temperature of Air through aeration cement Blowers and lack of ventingsurface conditionsOf cone and the Entry of moistureSide walls Along with cement SO3 and Alkalis Storage time of In the cement in the cement
Temperature of cementCement temperature must be less than 80 Deg C whenconveyed into silo. If it is more than 80 deg C the crystalline waterfrom Gypsum gets dehydrated and moisture moves to the colderpart ie center cone and the walls .This moisture Hydrates the finecement and causes cake formation. Presence of alkalisacclerates prehydration.In our clinker K2O+ Na2O is 0.8. Incement 0.63 (PPC) and SO3 is 1.8 %.The coating formed isCalled Syngenite( K2SO4.CaSO4.H2O)
Intensity of coating formation as a function Of cement temperature stored in cement silo 100Percentage of heaviest coating 80 SO3=2.7 % 260 M2/kg 60 40 20 0 60 80 100 120 140 Cement temperature Deg C , stored
Effect of surface on lump formationIf surface of the inner cone and side walls are rough cementmake dead layer and over a period of time they get hydratedAnd dislodged causing blockage.To have a glassy surface, the walls and floor are coated withepoxy Or materials which can form fine surface whichfacilitates smooth out flow flow of material
Storage timeHigh storage time and high cement temperature, both canaid cake formation. Our cement in silo 4 and 5 is more than 12 days In silo 3 it is 2 to 3 days.
Effect of gypsum content on cake formationHigher gypsum addition or higher SO3 in cement accelerates the hydrationof cement In silo. Anhydrate gypsum reduces coating formation ie., Caso4 Our cement
Addition of anhydrate (Gypsum without water) Can reduce lump Formation in silo.Ratio of anhydrate/gypsum(CaSO4.2H2O) ratio
Ultimate solution1. Reduce the cement temperature from 90 deg C to 70 step by step2. Reduce the storage time present 10 days to 6 days3. Silo venting must be on when cement is extracted and aeration is done. When RH is high It can accelerate the hydration
Thanks for your kind attentionK.P.PRADEEP KUMARSr G M OperationChettinad cements LtdKarikkali works
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