Chelant screening and refinement tests - Phase I, Task 2. Topical progress report, December 1993--June 1994 Page: 20 of 236


As previously presented, the purpose of the screening tests was to select three solvents
for refinement testing, based strictly on their ability to chelate uranium. The deposit material
chosen for dissolution testing was uranium dioxide (UO2), since it was felt to represent one of
the least soluble contaminants potentially present. Each candidate chelant was subjected to
several screening tests, run at varying pH's. The other conditions were held constant throughout
the initial stages of the screening test program. These conditions included the following:
Chelant Concentration 10% weight/volume
Solution Temperature 93*C
Solution pH 5.5, 7.0, 9.0
Uranium Concentration 4 grams UO2/liter solvent
Exposure Time 8 hours
The screening tests were conducted in three-liter four-neck reaction flasks. A schematic
of a typical solvent screening test flask arrangement is shown in Figure 2. The general
procedure followed for testing was as follows:
(1) Prepare solvent and analyze to ensure it is within specification.
(2) Add solvent to a reservoir flask and heat to 93*C in a controlled temperature
water bath.
(3) Add weighed amount uranium dioxide to bottom of a reaction flask.
(4) Assemble reaction flask lid by inserting stirrer, sampling tube, fill/drain line,
condenser, and thermocouple in appropriate penetrations.
(5) Secure lid on test flask, place flask in controlled temperature water bath, start
flow of cooling water to condenser and heat bath to 93*C.
(6) When the solvent in the reservoir flask reaches 93*C, pump heated solution into
the reaction flask containing uranium dioxide. Begin stirring solution vigorously.
Maintain temperature at 93*C + 2*C throughout the test period.
(7) Take samples of the solvent after 1, 2, 4, 6, and 8 hours of exposure. Analyze
samples for dissolved uranium (by inductively coupled plasma spectroscopy) and
available chelant. Filter samples through tared Millipore filters to remove
particulate material. Dry and weigh filters.
(8) At the conclusion of the test, filter the entire solution remaining in the test flask.
Dry and weigh the filtered material.


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Chelant screening and refinement tests - Phase I, Task 2. Topical progress report, December 1993--June 1994, report, July 1, 1995; United States. ( accessed May 25, 2019), University of North Texas Libraries, Digital Library,; crediting UNT Libraries Government Documents Department.

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