A physical separation method (i.e. sieving) was investigated to determine particle size distribution in non-radioactive sludge slurry simulants with the goal of implementation into the SRNL (Savannah River National Laboratory) shielded cells for use with radioactive sludge slurries. The investigation included obtaining the necessary experimental equipment, developing accessory equipment for use with the sieve shaker (to be able to sieve simulant slurries with aqueous solutions), sieving three different simulant slurries through a number of sieves and determining the particle size distribution gravimetrically, and developing a sufficient cleaning protocol of the sieves for re-use. The experimental protocol involved successive sieving of a NIST standard (to check the particle size retention of the sieves) and three non-radioactive slurry simulants (Batch 3 Tank 40 Test 3, Tank 40 Drum 3 and CETL Sludge Batch 2, which had been previously characterized by Microtrac analysis) through smaller and smaller sieves (150 microns x 5 microns) via use of the wet sieving system or by hand. For each of the three slurries, duplicate experiments were carried out using filtered supernate and DI water (to check the accuracy of the method versus Microtrac data) to sieve the slurry. Particle size determinations using the wet sieving system with DI water agree well with Microtrac data on a volume basis and in some cases the sieving data may be more accurate particularly if the material sieved had large particles. A correction factor had to be applied to data obtained from experiments done with supernate due to the dissolved solids which dried upon the sieves in the drying stage of the experiments. Upon subtraction of the correction factors, the experimental results were very similar to those obtained with DI water. It should be noted that approximately 250 mL of each of three simulant slurries was necessary to have enough filtered supernate available to carry out the experiments. The experimental results for the slurries are below with Microtrac data. The design of the experimental equipment was sufficient initially, but some pieces of the equipment began failing over time due to the caustic nature of the supernate and the vibrations from the sieve shaker. It is therefore recommended that upgrades to the experimental equipment be done before implementation into the SRNL shielded cells. Theses upgrades include using manipulator friendly connections, changing brass parts for stainless steel parts, using Teflon rather than polycarbonate, and possibly a change of pumps used to re-circulate the sieving fluid.
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