Alternatives for arsenic storage in waste forms - Thermodynamics of selected Fe,Al arsenates
Final Report Abstract
The project was based on the measurement of thermodynamic properties of a number of selected arsenates, selected as potential phases for arsenic storage owing to the assumed low solubility. Indeed, several such phases have been identified (FeAsO4·0.75H2O, kamarizaite, pharmacosiderite). Calorimetric (acid-solution calorimetry, high-temperature oxide-melt calorimetry, relaxation calorimetry) and solubility measurements gave accurate and precise data for all studied arsenates. The laboratory measurements have been augmented, where applicable, by chemical data of minerals and their solid solutions. The data were included in the thermodynamic databases of the common geochemical modeling codes PHREEQC and Geochemist’s Workbench. Solubility of the studied phases and phase diagrams were calculated with these codes and presented in the scientific publications that are a result of this work. The results of work on pharmacosiderite are still being processed and prepared for a publication. The data for the scorodite-mansfieldite solid solution were not obtained because of puzzling behavior of pure mansfieldite. Instead of this part of the work, we included several other arsenates in the work program (angelellite, kamarizaite) and measured their thermodynamic properties.
Publications
- 2016: Thermodynamic properties of FeAsO4·0.75H2O. Hydrometallurgy 164, 136-140
Majzlan, J., Dachs, E., Benisek, A., Drahota, P.
(See online at https://doi.org/10.1016/j.hydromet.2016.05.019) - 2018: Thermodynamics of mansfieldite, AlAsO4·2H2O, angelellite, Fe4(AsO4)2O3, and kamarizaite, Fe3(AsO4)2(OH)3·3H2O. Mineralogical Magazine
Majzlan, J., Nielsen, U.G., Dachs, E., Benisek, A., Drahota, P., Kolitsch, U., Herrmann, J., Bolanz, R.
(See online at https://doi.org/10.1180/mgm.2018.107)
