A Physico-Chemical Characterization of Salt Cake Dissolution and Study of Sodium Phosphate Dodechydrate Plug Remediation

This thesis is divided into two projects. The first project investigates the dissolution of the Hanford salt cakes, the chemical properties of the effluent and the physical properties such as viscosity of the effluent, the porosity and the permeability of the salt cake bed as the dissolution proceeds. The chemical results are compared to predictions using a thermodynamic model. Physical properties are important because they govern the rate at which the Hanford tanks can be emptied thus facilitating the remediation process. Two simulants were investigated for the dissolution process. The chemical analysis matched with the model predictions for both the simulants. A typical gibbsite layer formation was observed in the chemically complex simulant and experiments were performed to remediate the layer. The second project of this thesis studied the remediation of sodium phosphate dodecahydrate plug using water and sodium carbonate solutions at varying concentrations. A flow loop previously used to study the sodium phosphate dodecahydrate plugging mechanisms, was used to form a plug followed by the addition of water and sodium carbonate solutions. Results indicate that there was a drastic decrease in time to remediate the plug when sodium carbonate solutions were used