Ceramics-Silikáty 56 (1) 76-84 (2012)

THE INFLUENCE OF CaO AND P₂O₅ OF BONE ASH UPON THE REACTIVITY AND THE BURNABILITY OF CEMENT RAW MIXTURES

T. Ifka, M. T. Palou, Z. Bazelová

The influence of CaO and P₂O₅ upon the reactivity of cement raw meal was investigated in this paper. Ash of bone meal containing Ca₃(PO₄)₂ - 3CaO·P₂O₅ was used as the source of P₂O₅. Two series of samples with different content of the ash of bone meal were prepared. In the first series, the ash of bone was added into cement raw meal. The second series of samples were prepared by considering ash as one of CaO sources. Therefore, the total content of CaO in cement raw meal was kept constant, while the amount of P₂O₅ increased. These different series of samples were investigated by analyzing free lime content in the clinkers. The XRD analysis and Electron Micro Probe Analyzer analysis of the clinkers were also carried out. Two parameters were used to characterize the reactivity of cement raw meal: content of free lime and Burnability Index (BI) calculated from free lime content in both series of samples burnt at 1350 ºC, 1400 ºC, 1450 ºC and 1500 ºC. According to the first parameter, P2O5 content that drastically makes worse the reactivity of cement raw meal was found at 1.11 wt.% in the first series, while this limit has reached 1.52 wt.% in the second one. According to the BI, the limit of P₂O₅ was found at 1.42 wt. % in the first series and 1, 61 wt.% in the second one. Furthermore, EPMA has demonstrated the presence of P₂O₅ in both calcium silicate phases forming thus solid solutions.

Keywords: Reactivity, burnability, Alternative fuels, Alternative materials