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Portland cement clinker is made by heating, in a kiln, a homogeneous mixture of raw materials to a sintering temperature, which is about 1450 °C for modern cements. The aluminum oxide and iron oxide are present as a flux and contribute little to the strength. For special cements, such as Low Heat (LH) and Sulfate Resistant (SR) types, it is necessary to limit the amount of tricalcium aluminate (3CaO.Al2O3) formed. The major raw material for the clinker-making is usually limestone (CaCO3) mixed with a second material containing clay as source of alumino-silicate. Normally, an impure limestone which contains clay or SiO2 is used. The CaCO3 content of these limestones can be as low as 80%. Second raw materials (materials in the raw mix other than limestone) depend on the purity of the limestone. Some of the second raw materials used are: clay, shale, sand, iron ore, bauxite, fly ash and slag. When a cement kiln is fired by coal, the ash produced from the coal acts as a secondary raw material.


Coal plays a vital role in electricity generation worldwide. Coal-fired power plants currently fuel 41% of global electricity. In some countries, coal fuels a higher percentage of electricity.


The mineral Gypsum precipitated some 100 to 200 million years ago when sea water evaporated. From a chemical point of view it is Calcium Sulphate Dihydrate (CaSO4.2H2O) deposited in sedimentary layers on the sea bed. Under high pressure and temperature Gypsum turns into Anhydrite (CaSO4). In nature, Gypsum and Anyhdrite occur as beds or nodular masses up to a few metres thick. Gypsum is formed by the hydration of Anhydrite. The content of Gypsum in sedimentary rock varies from 75% to 95%, the rest being clay and chalk.



We supply East Africa Origin Industrial grade limestone for steel industry 30-60mm/40-80mm (massive re-crystalline limestone with less than 0.5% clay). The above limestone is ideal for high compressive strength armour rocks and low silica limestone products. We also source high quality limestone from Vietnam and East Mediterranean.

Innovana Mining & Construction Limited

“To ensure the highest level of quality and consistency, we concentrate our services on core market sectors that reflect our strength.”
Peter Karienye
Core Services & Operation:
-Civil Engineering
-Structural Engineering
-Geotechnical Engineering
-Environmental Engineering
-Construction Inspection