Cement Energy Environment

66 After exposure to the ash the castable samples were analysed with respect to physical performance and microstructure. Coating occurs as the alkali-sulfur-chloride compounds lower the melting temperature of the refractory material and particulate matter sticks to the surface. The coating Effect of liquid phases from slag on low cement castables Results and Discussion Figure 8: Dynamic finger dip test (left) of melted slag from waste incineration against HASLE LCC and post-mortem sample of the castable (right) after one year of operation. Corrosion by liquids can be studied in the laboratory by dynamic tests as the finger dip test (CEN/TS 15418) and gives a good indication of castable resistance against slags (Figure 8, left). The most accurate way The influence of volatile elements in ash from waste incineration on exposed castables Gaseous phases of alkalis in ash are highly mobile and react almost instantly with the refractory material. Following exposure to the alkali-rich ash for only 48 hours, the properties of the castable have significantly Table 3 : Relative change of physical parameters of a low cement alumina-silica low cement castable after exposure to ash and the chemical composition of the reaction zone and surface layer (right) Castable Properties Change (%) Density nd Cold crushing Strength -8.3 Cold modulus of Rupture -23.7 Open porosity +7.6 Castable microstructure Al 2 O3 SiO 2 Fe 2 O3 K 2 O Reaction zone ash vs castable 39.1 15.2 1.1 44.6 Glassy phase 26.9 60.6 0 12.5 Dense aggregate 77.9 19.8 0 2.3 changed; the compression strength (CCS) and bending strength (MOR) are lowered and the open porosity has increased (Table 3). can be more or less liquid depending on temperature and does not only build-up on the surface but may also corrode the lining. to understand the corrosion mechanisms is to analyse samples of castables that have been in operation (Figure 8, right). Chemical compostion(%)