Apr 2018 HOW CEMENT IS MADE?
With process, manufacturing and technological advancements is constantly being made in the production of cement, Sephaku Cement looks at the process of making cement.
Said to be one of the most common materials used in various building projects around the world, cement and by default concrete is versatile, low maintenance, affordable, durable and with an excellent thermal mass. Used in the construction of homes, buildings, schools, hospitals, bridges, tunnels, dam walls, sewage systems and various other modern day constructs, it’s difficult to find a building or structure that exists without the support of cement.
To follow, find the various steps taken during the production of cement from excavation of raw materials to the final bagged product.
- Step one – Excavating Raw Materials
Made predominantly from Limestone, Clay or Marl, raw materials are mined from mineral rich quarries by blasting or ripping using heavy machinery to excavate the site. Extracted materials are then transported by wheel loaders and dumper trucks or conveyor belts to crushing installations for processing, where the raw material is later broken up into smaller pieces.
- Step Two – Storage and Blending
Once crushed the raw materials are transported by conveyer belts and warehoused in blending beds where they are further homogenized, blended together, to form a uniform bed of material.
- Step Three – Drying and grinding
Once the type of cement required has been determined, production begins with preparing the raw materials through drying and raw grinding. Roller grinding mills and ball mills grind the homogenised raw material into a finer product, while simultaneously drying it out during the grinding process. ( either heat from grinding or induced heat)
- Step Four – Burning to form Clinker
Using preheater kilns or using traveling grates (Lepol) the raw material, now crushed and dried is “burnt” at extremely high temperatures. As a result of the burning process a chemical conversion takes place also referred to as sintering that results in the production of clinker.
- Step Five – Fine Grinding
Once the clinker has sufficiently cooled after the burning process, the stony residue is once again conveyed to ball mills or roller presses where it is finely ground into powdery dust also referred to as cement. Depending on the desired use of the cement it is also during this process that additives such as Anhydrite, Gypsum, Limestone or Blast-furnace Slag and other additions like grinding aid are combined with the ground, powdery material in the production of the finished cement product.
Given the scope of development that cities and towns locally and across the globe continue to undergo, finding new and innovative ways to complete construction projects in the most durable, energy efficient and eco-friendly manner is critical.
Estimated as being used twice as much in comparison to a combined use of other building supplies such as wood, steel and aluminium etc., concrete is said to be the most commonly used man made material in the world.
Produced predominantly from raw materials, efforts in the production of cement are now focussed on reducing CO2 emissions during the process of making cement. Considered to be one of the most eco-friendly materials used in constructions compared to other materials commonly consumed, the use of concrete plays a key role in maintaining internal temperatures amongst other sustainable benefits.