Automated analysis of aluminium bath electrolytes by the Rietveld method

Rietveld analysis emerged as a routine tool in quantitative phase analysis of crystalline powder samples. Here, XRD data from solidified aluminium electrolytes were rapidly obtained with a 1-dimensional silicon strip detector and analysed with the TOPAS software. It is shown how to calculate well established process control measures such as Bath ratio and excess AlF3 from the Rietveld results. These measures are widely used in aluminium production and are readily calculated with very high precision. The excellent agreement with Alcan reference data demonstrates the outstanding accuracy of the method. Furthermore, it is shown how to improve conventional Potflux analysis by the Rietveld method. Finally, the automated investigation of aluminium bath samples in AXSLAB is outlined.