From the limestone quarry till the delivery of the final product, the following steps describe the cement manufacturing process:
Extraction of Raw Materials
The raw materials needed to produce cement like calcium carbonate, silica, alumina and iron are generally extracted from Limestone, shale and iron ore and suitable reserves and deposits are available in most countries.
These raw materials are extracted from the quarry by surface mining and crushed and transported to the plant where they are stored and homogenized.
Raw Grinding and Burning
Perfect grinding produces a fine powder termed as raw meal which is preheated and sent to the Kiln.
The material is heated to between 1250 – 1300 degrees celcius before being dramatically cooled by burst of air in the cooler. This produces the principal ingredient known as Clinker which is the basic material for cement production.
Cement Grinding and Delivery
A small proportion of gypsum (3-5%) is added to the clinker to regulate how the cement will set.
The mixture is then finely grounded to obtain real cement. During this process, cement additives (Pozzolona-a mineral material) is added along with gypsum which gives the cement specific properties such as greater resistance to surfaces, aggressive environments and superior quality finish.
Finally the cement is stored in Silo before packed and delivered to the final customers.