All about Cement

From the raw material quarry to the delivery of the end product, Lafarge Cement Zimbawe is fully committed to provide high quality products and value added services to our customers. We do this by closely monitoring quality of raw materials and services incorporated throughout our value chain as well as our production processes and customer facing activities. Lafarge Cement Zimbabwe pledges its commitment to four drivers of quality; that is, Innovation, Continuos Improvement, Customer Satisfaction and Leadership.


The cement-making process is as follows:


Step 1: extraction of raw materials

The raw materials needed to produce cement (calcium carbonate, silica, alumina and iron ore) are generally extracted from limestone rock, chalk, clayey schist or clay. Suitable reserves can be found in most countries.

These raw materials are extracted from the quarry by blasting. They are then crushed and transported to the plant where they are stored and homogenized.


Step 2: raw grinding and burning

Very fine grinding produces a fine powder, known as raw meal, which is preheated and then sent to the kiln. The material is heated to 1,500°C before being suddenly and dramatically cooled by bursts of air.

This produces clinker, the basic material required for the production of all cements.


Step 3: cement grinding and shipping

A small amount of gypsum (3-5%) is added to the clinker to regulate how the cement will set. The mixture is then very finely ground to obtain "pure cement". During this phase, different mineral materials, called "cement additives", may be added alongside the gypsum. Used in varying proportions, these additives, which are of natural or industrial origin, give the cement specific properties such as reduced permeability, greater resistance to sulfates and aggressive environments, improved workability, or higher-quality finishes.


Finally, the cement is stored in silos before being shipped in bulk or in bags to the sites where it will be used.