the dissolution of
silica and especially alumina were significantly affected by the calcination
temperature, resulting in decrease in SiO2/Al2O3 ratio of
dissolved species as shown in Table 3. The dissolved silicon ions of
the DE400 (DE calcined at 400 ◦C), DE600 and DE800, respectively,
were 1690, 3540 and 4140 mg/L while those of aluminum ions were
158, 1010, 1260 mg/L, respectively. High calcination temperature
of 600 and 800 ◦C were needed for increased dissolution of aluminum
ions. RHA provided a slightly larger amount ofthe dissolved
silicon ions than FDE800. This was due to the larger amount of