Sample Preparation for Quantitative X-Ray Diffraction (XRD/Rietveld)

Theoretical background: see chapters 3 and 4 in Machiels (2010). Sample preparation method modified from Machiels et al. (2008).

Representative sampling

The mineralogy and glass content of slags depend largely on the mode of cooling of the slags, e.g. slow cooling in a slag pot can result in a large amount of crystalline phases, and fast granulation in water can result in high glass content. A mineralogical analysis will thus only represent the mineralogy of a slag system for a certain grade of cooling and strongly different results can be obtained when cooling conditions are different between the different batches.

Even in a single slag pot, mineralogy and glass content can vary strongly. Taking a sample representative for a slag pot can be done by performing the sampling after a first size reduction of the bulk material or, by mixing representative parts of the slag pot (sides of the pot, center, near cracks, in center of slags, etc.)

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Sample preparation by McCrone Micronizing mill before XRD/Rietveld test

In the cement science field, XRD analysis combined with Rietveld method can give quantitative results of crystalline phase of hydration products, so I try to use XRD/Rietveld method to quantify the hydration products of cementitous material. To achieve good performance of XRD test, fine powder is required and of great importance.

The question is how fine the particle sizes should be? It is showed by research that the particle size of powder has to be reduced to 10 μm or less, which is especially important for quantitative analysis (Smith, 2001).

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