Cement is not a naturally occurring mineral or element; it is manufactured in a cement factory like LafargeHolcim Tanzania’s Tembo cement facility in Mbeya. Cement is a combination of raw minerals that are burned and ground into the fine grey powder that we all know. But what are these raw materials and where do they come from?
The most common types of rock and mineral used to make cement are:
- Limestone (makes up the bulk of cement)
- Clay or shale (makes the silica, alumina and ferric oxide needed for cement)
- Fly ash (ash from burned coal)
- Other supplementary minerals and raw materials
The limestone used to make cement will come from a quarry. It is blasted out of the ground and the rocks are sent to the quarry mill where they are graded, sized and sorted. The high-quality limestone is more expensive but better for manufacturing cement as it allows producers, like LafargeHolcim Tanzania, to manufacture a better quality product.
This high-quality limestone is crushed into a fine powder at the mill. Cement producers buy the fine limestone powder because it makes the blending process easier. Ideally, each particle of limestone powder should be no more than 90 microns thick (0.09 millimetres).
The limestone powder is then mixed and blended with the other raw materials in differing proportions, depending on the type of cement being manufactured. These blended raw materials are stored in a silo before being fed into the cement facility’s kiln. It is burned at temperatures over 1500℃ to produce clinker.
This clinker is a grey rock-like material that is then mixed with supplementary minerals, such as gypsum, and ground into the fine powder we know as cement. The composition of the clinker can change, depending on the type of cement being manufactured and the availability of the raw materials.
Cement manufacturers need to source these raw materials from local sources in order to keep transport and production costs low. Luckily, these minerals and raw materials are readily available in Tanzania. In countries where limestone and other minerals are scarce, they need to be imported but that affects the final price of the cement.
LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges.
LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.
At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.