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Geological surveys and prospecting are carried out to establish the quality and quantity of available raw materials. From the prospecting data obtained, quarry-mining plans are drawn up and updated as mining progresses.
The first step in cement manufacture is the extraction of raw materials. After removal of the topsoil, limestone is blasted using explosives, while kunkur is ripped using bulldozers. The material is then transported to the primary crusher for size reduction and is loaded onto lorries for transportation to the factory for further processing.
At the factory, crushed limestone and kunkur are stacked into blending piles. Material is drawn from the piles by a carefully controlled reclaimer system that cuts across the stockpile, ensuring uniform blending takes place to ensure raw material quality.
Gypsum, iron ore and pozzolana are also stored in piles. Laboratory quality control ensures that the highest raw material standards are maintained.
Crushed raw materials are conveyed to the raw mill bins, from where they are extracted in controlled quantities as they are offloaded into the vertical roller mill.
The mill grinds the raw material into fine powder and dries it using hot exhaust gases from the kiln.
The raw meal is then stored in the homogenising silo for further mixing to ensure uniform kiln feed is attained. This is necessary for the efficient functioning of the kiln and for production of good clinker.
Clinker manufacture is the most critical stage in the process. This takes place in the inclined 54-metre long rotary kiln. The raw meal is fed into the kiln pre-heater cyclones and it cascades sequentially through the four-stage cyclones into the kiln, reaching a temperature of 1,450°C, where clinkering or conversion of the material to cement clinker occurs.
The hot clinker is cooled in the grate cooler, where cold atmospheric air is drawn in. Our kiln has a capacity to produce 1,680 tonnes of clinker a day.
Clinker, with small quantities of gypsum to control setting time, is ground in cement mills that use steel balls. Pozzolana or tuff is added to produce pozzolanic cement if desired. Using compressed air, the finely ground cement is conveyed into cement storage silos.
We lay strong emphasis on our quality control system to ensure customers get quality products. Chemical and physical tests are carried out at every stage of the process to ensure proper performance of the cement.
Samples collected at different stages of the process are tested and analysed and any necessary adjustments carried out immediately.
Cement is extracted from the silos and packed into 50-kg and 25-kg paper bags marked "Blue Triangle Cement" and embossed with the Kenya Bureau of Standards diamond mark of quality. The new automated packing machines, with a capacity to pack 100 tones an hour, ensure packing is quick and efficient.
Five per cent of Blue Triangle Cement is sold in bulk, while the remaining 95% is disposed of in bags. Transportation is by road and rail.
Blue Triangle Cement is sold in the local market and also exported to the East African Region.
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