Examination of the jarosite–alunite precipitate addition in the raw meal for the production of sulfoaluminate cement clinker

The aim of the present research work was to investigate the possibility of adding a jarosite–alunite chemical precipitate, a waste product of a new hydrometallurgical process developed to treat economically low-grade nickel oxides ores, in the raw meal for the production of sulfoaluminate cement clinker. For that reason, two samples of raw meals were prepared, one contained 20% gypsum, as a reference sample ((SAC)Ref) and another with 11.31% jarosite–alunite precipitate ((SAC)J/A). Both raw meals were sintered at 1300 °C. The results of chemical and mineralogical analyses as well as the microscopic examination showed that the use of the jarosite–alunite precipitate did not affect the mineralogical characteristics of the so produced sulfoaluminate cement clinker and there was confirmed the formation of the sulfoaluminate phase (C4A3S¯), the most typical phase of this cement type. Furthermore, both clinkers were tested by determining the grindability, setting time, compressive strength and expansibility. The hydration products were examined by XRD analysis at 2, 7, 28 and 90 days. The results of the physico-mechanical tests showed that the addition of jarosite–alunite precipitate did not negatively affect the quality of the produced cement.