A cement is a binder or, a substance which sets and hardens and can bind other materials (concretes, stones, sands etc) together. It is the basic ingredient of construction and widely used as primary construction material. It is a very sensitive ingredient as it has the ability of enhancing viscosity of concrete which provides the better locking of sand and concrete together in a concrete mixture.
Portland Cement Making Process Steps:
Portland Cement is manufactured after completing all following six steps one after another.
- Quarry- Raw Material Extraction
- Grinding, Proportioning and Blending
- Pre-Heater Phase
- Kiln Phase
- Cooling and Final Grinding
- Packing & Shipping
Portland Cement Making Process Steps- 1: Quarry
The major raw materials of Portland Cement making are limestone, clay and sand which cover calcium, silicon, iron and aluminum. Limestone is mainly for calcium. It is combined with smaller proportions of sand and clay. Sand & clay fulfill the need of silicon, iron and aluminum.
Generally portland cement plants are suitable where the quarry of limestone is near bye. It saves the extra fuel cost and minimize cement making cost. Normally, Cement Raw materials are extracted from the quarry and by conveyor belt those raw material materialsare transported to the cement making plant.
There are some other raw materials used for cement making. Say, shale, fly ash, mill scale and bauxiteare directly brought from other sources due to small requirements.
Before transportation of cement raw materials to the plant, large sized rocks are crushed into smaller sized rocks by crusher at quarry.
Portland Cement Making Steps-2: Proportioning, Blending & Grinding
The portland cement raw materials from quarry are brought into plant laboratory at which they are analyzed. They are crushed into powder before analyzing & laboratory test. Generally, limestone is 80% and remaining 20% is the clay. Limestone and clay are analyzed to make sure their competency before the beginning of grinding.
Portland Cement Making Process Steps-3: Pre-Heating Raw Material
After grinding of Cement Material, it is ready to face the pre-heating chamber. Pre-heating chamber utilizes the emitting hot gases from kiln. Pre-heating of the material saves the energy and make plant environmental friendly.
Portland Cement Making Process Steps-4: Kiln Phase
Kiln is a huge rotating furnace also called as the heart of cement making process. Here, raw material is heated up to 1450 ⁰C. This temperature begins a chemical reaction so called decarbonation. In this reaction material (like limestone) releases the carbon dioxide. High temperature of kiln makes slurry of the material.
The series of chemical reactions between calcium and silicon dioxide compounds form the primary constituents of cement i.e., calcium silicate. Kiln is heating up from the exit side by the use of natural gas and coal. When material reaches the lower part of the kiln, it forms the shape of clinker.
Portland Cement Making Process Steps-5: Cooling and Final Grinding
After passing out from the kiln, clinkers are cooled by mean of forced air. Clinker released the absorb heat and cool down to lower temperature. Released heat by clinker is reused by recirculating it back to the kiln. This too saves energy.
Final process of 5th phase is the final grinding. There is a horizontal filled with steel balls. Clinker reach in this rotating drum after cooling. Here, steel balls tumble and crush the clinker into a very fine powder. This fine powder is considered as cement. During grinding gypsum is also added to the mix in small percentage that controls the setting of cement.
Portland Cement Making Process Steps-6: Packing and Shipping
Material is directly conveyed to the silos (silos are the large storage tanks of cement) from the grinding mills. Further, it is packed to about 20-40 kg bags. Only a small percent of cement is packed in the bags only for those customers whom need is very small. The remaining cement is shipped in bulk quantities by mean of trucks, rails or ships.