Scoping tests to evaluate the effects of agitation and pH adjustment on simulant sludge agglomeration and uranium metal oxidation at ~95°C were performed under Test Instructions(a,b) and as per sections 5.1and 5.2 of this Test Plan prepared by AREVA. (c) The thermal testing occurred during the week of October 4–9, 2010. The results are reported here. For this testing, two uranium-containing simulant sludge types were evaluated: 1. a full uranium-containing K West (KW) container sludge simulant consisting of nine predominant sludge components 2. a 50:50 uranium-mole basis mixture of uraninite [U(IV)] and metaschoepite [U(VI)]. This scoping study was conducted in support of the Sludge Treatment Project (STP) Phase 2 technology evaluation for the treatment and packaging of K-Basin sludge. The STP is managed by CH2M Hill Plateau Remediation Company (CHPRC) for the U.S. Department of Energy. Warm water (~95°C) oxidation of sludge, followed by immobilization, has been proposed by AREVA and is one of the alternative flowsheets being considered to convert uranium metal to UO2 and eliminate H2 generation during final sludge disposition. Preliminary assessments of warm water oxidation have been conducted, and several issues have been identified that can best be evaluated through laboratory testing. The scoping evaluation documented here was specifically focused on the issue of the potential formation of highstrength sludge agglomerates at the proposed 95°C process operating temperature. Prior hydrothermal tests conducted at 185°C produced significant physiochemical changes to genuine sludge, including the formation of monolithic concretions/agglomerates that exhibited shear strengths in excess of 100 kPa (Delegard et al. 2007).
Revised: August 1, 2012 |
Published: June 15, 2011