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Quality Control : A Modern Cement Works Essay

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QUALITY CONTROL
Consider a modern cement works - it probably produces 1000 - 4000 tonnes of cement a day. Raw materials are dug from the ground and are intrinsically variable - for example limestone from one end of the bench might well contain more clay or silica than limestone from the other end. Fuels are also variable - coal varies in ash and sulphur contents and these days, a works may also burn ancillary fuels such as solvents or car tyres. Variation in raw materials and fuels are likely to result in changes in kiln conditions and consequently, to some extent at least, to changes in the cement quality. Of course, some changes may be for the better, but unless they are maintained consistently, the result may create variability in the final product.
To maintain consistency in quality, rigorous testing of the final product, by online analysis of raw materials and clinker and improved monitoring of kilns, mills etc is done. Of course, all this has been made possible by the advances in computer technology in recent years. For example, until fairly recently, chemical analysis would be done by conventional “Wet Chemical Analysis”. A sample of clinker or raw material would arrive at the laboratory and over the following few hours and days in some cases a chemist would have crushed it, dissolved it, heated it, titrated it and do whatever else was required by the analytical method, for each element. In a modern works this is automated; a machine grabs the sample, crushes it,

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