The Marvel Cinematic Cement Plant

"How cement is made" is probably one of the more common questions that I get asked. Well, I figured I would have a little fun with this one and give a tip of the hat to the great Stan Lee who passed away earlier this week, and re-imagine how it looks...

Quarry and Raw Materials

For its raw materials, cement uses minerals containing the four essential elements for its creation: Calcium, Silica, Aluminium, and Iron. Most plants rely on a nearby quarry for limestone. Rock is blasted from the quarry face and transported to the primary crusher and then secondary crusher, being reduced down to the size of gravel. This high calcium limestone is combined with smaller amounts of clay, sand, alumina, and iron sources. Obviously, when we’re talking about heavy explosives and heavy lifting, this is a tag-team approach and we need to call in the big guns for this one…

Raw Meal Preparation

Raw materials are blended in the proper proportion and carefully controlled in real time by online analysers and routine xrf analysis in the laboratory, before being transported to the raw mill. This certainly sounds like a bunch of hocus-pocus from the wizards in the QC department, so I’m thinking the master of the mysterious better take this…

Raw Milling

The raw mill consists of heavy, wheel-type rollers that crush the material against a rotating table to the consistency of talcum powder. The material is pneumatically conveyed by the hot kiln exhaust gas and collected by a baghouse and stored and blended in the feed silos. Smashing and blowing? That sounds like a job for our favourite Asgardian…

Preheating

The preheater tower supports a series of vertical cyclones through which the raw materials pass on their way to the kiln. The material exchanges heat with the kiln exhaust gases as they swirl down through the chambers. The material reaches a temperature of around 850C to remove the combined water and carbonate components. Exit gases are treated with water sprays, dust collection, and electrostatic precipitators to ensure clean emission. Stormy weather ahead!

Pyroprocessing and the Kiln

The raw mix now enters the kiln, a horizontally sloped rotating furnace. The feed slides and tumbles down the kiln through progressively hotter zones towards the flame. The material becomes partially molten, reaching a temperature of approximately 1450C! You already know what we're saying every time we light this beast up...

Clinker Formation

The intense heat triggers chemical and physical changes converting the base elements into calcium silicates and aluminates. These minerals will react with water and form new hydrate compounds which interlock with each other gaining strength and durability. These minerals are microscopic and well dispersed within one another, so we need to pay attention to the little things…

Clinker Cooling

The product emerges from the kiln as a new substance called clinker. The clinker tumbles onto a grate cooled by forced air to quickly quench the reactions. Once cooled, the clinker is ready to be ground into cement.

Cement Finish Grinding

The clinker is ground either in another vertical roller mill or in a ball mill which is a lined steel tube filled with steel-alloy balls. As the tube rotates, the balls tumble around at high speed to crush and grind the clinker into a super-fine powder. A small amount of gypsum is added during this stage to control the setting characteristics, limestone to optimise performance and improve sustainability, and grinding aids to improve efficiency and flowability.

Delivery

The finished cement is finally conveyed to silos, where it awaits to be transported or packaged to customers. And of course, we have our top people on the job - all the way from the operations, through to logistics and sales…