Abstract
An accurate bath composition analysis is essential for regulating an electrolysis cell's mass and thermal balance. XRD is widely utilised in smelters to analyse % excess AlF3 (xsAlF3) and Cryolite Ratio (CR) of bath samples. However, the conventional method of analysis can provide misleading results for the more complex bath chemistries usually found in, but not limited to, Chinese smelters. This complexity is due to the presence of Li, K and Mg constituents coming into the bath from alumina impurities. They react with AlF3 and cryolite, producing additional AlF3-containing phases other than chiolite and Cacryolite, which are not accounted for in the conventional xsAlF3 or CR analysis. Improvement of the xsAlF3 analysis for complex bath chemistries was investigated and presented in this paper. The aim was to provide an XRD methodology to measure the LiF, KF and MgF2 levels in the bath through an intensity calibration method, so that they can be integrated into the xsAlF3 and CR analyses. The challenges faced will also be discussed in this paper.