Measure fineness to estimate strength in real time

Various strength cements can be produced from the same clinker by varying the particle size. For example, rapid hardening cements giving faster hydration and strength development are produced by grinding more finely than would be the case for ordinary Portland cement. Measuring and controlling cement fineness is critical in achieving tight specifications to give consistent, high quality product.

Traditional fineness methods

Many plants control cement fineness using an air permeability apparatus to measure the Blaine number, a parameter related to the cement particle size. The Blaine surface area measurement has been used since the 1940s to determine cement quality and despite its longevity the limitations of this off-line technique are widely recognized. It is slow and suffers from poor reproducibility, which can lead to significant errors, including unnecessary or inaccurate changes to the classifier speed. In addition, the fact that it produces only a single result without generating a particle size distribution means that two cements with a different proportion of fines can give the same Blaine number.

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Real-time fineness measurement

While Blaine remains a recognized reference, and has long provided an industry standard for predicting the ultimate strength of cements, more advanced analytical techniques are now being used to control cement fineness. The continuous sampling and measurement achieved using on-line particle size analysis allows real-time monitoring and fineness control, assuring the quality and strength of the cement. Malvern Insitec systems are widely used in cement production, improving productivity and allowing tighter control of both process and product. A 'laser diffraction' Blaine measurement, which has been shown to correlate with the standard 'pressure drop' Blaine, can also be produced if required.

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Insitec systems

Developed specifically for industrial applications, Insitec systems use Malvern's well-established laser diffraction technology built into a rugged and robust industrial platform that is designed to withstand the rigors of the process environment. With the ability to make more than a million measurements every year, fully automated Insitec systems provide a continuous stream of data, enabling real-time process optimization. Additionally, by removing the need for manual intervention personnel exposure to the product is eliminated.

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