Chromium in cement: development of an analytical method and investigation of contamination sources

A rapid method for determining chromium in cement has been developed. Chromium was analysed by atomic absorption spectrometry after dissolution of the sample in an acid medium. Precision, repeatability, reproducibility, accuracy and conformity prove that chloronitric attack followed by atomic absorption is a reliable method to determine total chromium and hexavalent chromium. The follow-up of the evolution of the chromium content along the cement chain of production showed that clay was the raw material, most contaminated by chromium and that the correction additions, mainly brick scrap, contributed significantly to the concentration of chromium in the kiln feed. It was also shown that the abrasion of the crushing bodies contributes slightly to the increase in the chromium content and that the clinkerisation process increases the chromium content in the clinker considerably, due to its presence in the fuel (petroleum coke).