Thank you @lemouth. Thats a big omission on my part. Explosion in silo is another common phenomenon not just where you stay but everywhere and including Nigeria. Agricultural products (here cereals) are composed of carbon, hydrogen, nitrogen, sulfur, oxygen etc, which makes them combustible. Within the silos, there is always air and the stored grain, forms deposited layers of dust. During the operations of loading and unloading, such layers, because of the motion due to the circulation of air, always generate a permanent cloud. The dispersed combustible dust clouds in the air form an explosive atmosphere and if triggered (by friction between the wall and stored products; static electricity), are able to oxidize so fast as to generate an explosion. The smaller the cross sectional area (in this case, flour) the faster its reactivity. Cereals should be stored and handled in a condition lower that the Lower Explosive Limit or higher than the Upper Explosive Limit to prevent explosion.
This is a problem is a result of faulty deisgn and also poor maintenance. Faulty design if dust aspiration systems or a ventilation system at grain transfer points isn't put in place and poor maintenance if routine checkup is not done to ascertain temperature, minimize dust accumulation among others.