Kiln

CEMENT MANUFACTURING PROCESS


There are four main process routes in the manufacturing of cement – the dry,
semi-dry, semi-wet and wet process.

Common to all these processes are the following sub-processes -
_ Quarrying.
_ Raw materials preparation.
_ Fuels preparation.
_ Clinker burning.
_ Mineral additions preparation.
_ Cement grinding.
_ Cement dispatch

Quarrying:

Natural (“primary”) raw materials such as limestone/chalk, marl, and clay/shale are extracted from quarries, which, in most cases, are located close to the cement plant. After extraction, these raw materials are crushed at the quarry site and transported to the cement plant for intermediate storage, homogenization and further preparation.

“Corrective” materials such as bauxite, iron ore or sand may be required to adapt the chemical composition of the raw mix to the requirements of the process and product specifications. The quantities of these corrective materials are usually low compared to the huge mass flow of the main raw materials.

To a limited extent, “secondary” (or “alternative”) raw materials originating from
industrial sources are used to substitute for natural raw materials and correctives. In the same way as traditional raw materials, they may be fed to the quarry crusher or – more commonly – directly to the cement plant’s raw material preparation system.

Today, modern computerized methods are available to evaluate the raw material deposits and to optimize the long-term and short-term production schedule.

Raw Materials Preparation:
After intermediate storage and pre-homogenisation, the raw materials are dried and ground together in defined and well-controlled proportions in a raw mill to produce a raw meal for the dry (and semi-dry) process.

The resulting intermediate product – i.e. raw meal– is stored and further homogenized in raw meal silos, storage bins or slurry basins to achieve and maintain the required uniform chemical composition before...