Quarrying and crushing

The primary raw material for cement manufacture is calcium carbonate or limestone. This is obtained from the quarry where, after the removal of overburden, the rock is blasted, loaded into trucks and transported to the crusher. A multistage crushing process reduces the rock to stone less than 25 mm in diameter. Most modern cement factories are located close to a source of limestone as about 1.5 tons of limestone are needed to produce one ton of cement.

Blending and storage

The crushed rock is stored in stockpiles where, by a carefully controlled process of stacking and reclaiming across the stockpile, blending takes place and a uniform quality of raw material is achieved. Systematic sampling and laboratory testing monitor this process. The other raw materials, normally shale, iron ore and sand, are also stored in stockpiles.

Raw milling and homogenisation
Carefully measured quantities of the various raw materials are fed, via raw mill feed silos, to mills where steel balls grind the material to a fine powder called raw meal. Homogenising silos are used to store the meal where it is mixed thoroughly to ensure that the kiln feed is uniform, a prerequisite for the efficient functioning of the kiln and for good quality clinker.


The most critical step in the manufacturing process, takes place in the huge rotary kilns. Raw meal is fed into one end of the kiln after nodulizing. The raw meal slowly cascades down the inclined kiln towards the heat and reaches a temperature of about 1 450 °C in the burning zone where a process called clinkering occurs. The nodules of clinker drop into coolers and are taken away by conveyors to the clinker storage silos.

Cement milling

The cement mills use steel balls of various sizes to grind the clinker, along with a small quantity of gypsum to a fine powder which is then called cement. Without gypsum, cement would flash set when water is added and gypsum is therefore required to control setting times. The finished cement is stored in silos where further blending ensures consistency.

Quality assurance

Extensive sampling and testing during the manufacturing process ensures the consistency and quality of the end product. Testing takes place at the stages of the manufacturing process indicated by thesymbol.

Cement despatch

Cement is despatched either in bulk or packed in 50 kg bags and distributed from the factory in rail trucks or road vehicles. The 50 kg bags are either packed directly onto trucks or can be palletised. The pallets can be covered by a layer of plastic to offer further protection from the elements. Various types of cement are sold, and more information on these can be found in the Products area of the website.