CEMENT MANUFACTURING IN RWANDA

Pre-heating & cooling stage CIMERWA storage and prehomogenization of raw material ■mining iron ore sand • Raw meal is fed into one end of the kiln, either directly or via a preheater system and pulverised coal is burnt at the other end • Raw meal slowly cascades down the rotating inclined kiln towards the heat and temperature reaches 1 450 °C where a process called clinkering occurs • Nodules of clinker drop into coolers and are taken away by conveyors to clinker storage silos • Gas leaving the kiln is cleaned by electrostatic precipitators prior to discharge into the atmosphere quarrying limestone cement crushing limestone process-technology clinker storage pulverized coal Why cool the clinker? To 'freeze' clinker minerals formed in the kiln Recover and return heat to the process → reduce overall energy consumption If very hot clinker enters finishing mills, gypsum overheating can occur → false setting of cement secondary additives cement mills raw mill filter preheating pulverized pal kiln calcination-burning raw meal to clinker cooling cement storage PPC raw meal homogenization cement dispatch bags bulk bulk bulk/bags 21 21

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