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 that allow hydrated cement to dislodge. Key solutions are reducing cement temperature and storage time, improving silo ventilation, and adding anhydrate gypsum to reduce hydration and lump formation. Proper silo coating also prevents moisture entry and surface hydration.