| The program predicts magnetite solubility fairly well when compared with literature, except for 250°C and below the minimum solubility pH range for 300°C where it over-predicts up to an order of magnitude. The solubility experiments came out to be comparable to the predictions and slightly higher than those provided by literature, but there were some difficulties with the experimental operation, which may have affected the outcome of the runs.; The solubility predictions for ilmenite and rutile were a few orders of (up to six) magnitude lower than what was observed by experiments.; The predicted zinc ferrite solubility trends, for the case of no hydrogen in the water, were to be expected for the iron component; however, the zinc component solubility decreases with increasing x (from ZnxFe 3−xO4) until x approaches unity, when it increases rapidly. The presence of iron (II) seems to lower the zinc concentrations and prevents the formation of the zinc oxide. For the case of dissolved hydrogen in the water, the predicted solubility seems to follow what was initially conceived (lower concentrations with increasing x-coefficient). The zinc concentrations falloff dramatically below x = 0.1 as the oxide becomes depleted with the zinc in the crystal. Hydrogen stabilizes the stoichiometric zinc ferrite dramatically. Unfortunately, non-stoichiometric ferrites are unobtainable so there is no published experimental or theoretical data with which to compare the trends. (Abstract shortened by UMI.)... |
