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Description: The primary objective of this task was to perform a variability study of the high activity waste (HAW) acidic feed to determine the impact of feed variability on the quality of the final grout and on the mixability of the salt solution into the dry powders. The HAW acidic feeds were processed through the neutralization/pH process, targeting a final pH of 12. These fluids were then blended with the dry materials to make the final waste forms. A secondary objective was to determine if elemental substitution for cost prohibitive or toxic elements in the simulant affects the mixing response, thus providing a more economical simulant for use in full scale tests. Though not an objective, the HAW simulant used in the full scale tests was also tested and compared to the results from this task. A statistically designed test matrix was developed based on the maximum molarity inputs used to make the acidic solutions. The maximum molarity inputs were: 7.39 HNO{sub 3}, 0.11618 gallium, 0.5423 silver, and 1.1032 'other' metals based on their NO{sub 3}{sup -} contribution. Substitution of the elements aluminum for gallium and copper for silver was also considered in this test matrix, resulting in a total of 40 tests. During the NaOH addition, the neutralization/pH adjustment process was controlled to a maximum temperature of 60 C. The neutralized/pH adjusted simulants were blended with Portland cement and zircon flour at a water to cement mass ratio of 0.30. The mass ratio of zircon flour to Portland cement was 1/12. The grout was made using a Hobart N-50 mixer running at low speed for two minutes to incorporate and properly wet the dry solids with liquid and at medium speed for five minutes for mixing. The resulting fresh grout was measured for three consecutive yield stress measurements. The cured ...
Date: March 20, 2009
Creator: Hansen, E.; Jones, Timothy; Edwards, Tommy & Cozzi, Alex
Partner: UNT Libraries Government Documents Department