Ceramicrete stabilization

T0062 Argonne National Laboratory, Ceramicrete Stabilization Technology... 

T0062 Argonne National Laboratory, Ceramicrete Stabilization Technology T0069 ARS Technologies, Inc., Ferox, Reduction of Chlorinated Organics in the Vadose Zone... 

T0023 Affinity Water Technologies, Advanced Affinity Chromatography T0062 Argonne National Laboratory, Ceramicrete Stabilization Technology T0132 Brookhaven National Laboratory, Biochemical Recovery of Radionuclides and Heavy Metals... 

Argonne National Laboratory Ceramicrete Stabilization Technology Abstract... 

Operational-Scale Estimates Based on the resnlts of a treatabihty stndy at the ANL-East in Chicago, Illinois, the laboratory prepared a cost estimate for an operational-scale Ceramicrete stabilization system. The hypothetical system wonld treat waste in 55-gal batches at a rate of 3 batches per shift. The capital costs for the system were estimated at 2,000,000. This estimate included the cost of eqnipment design and development (D20934H, p. 15). 

Ceramicrete stabilization of Tc, partitioned from high-level tank wastes, was demonstrated by Singh et al. [11]. The waste stream was a product of a complexation-elution process that separates Tc from HLW, such as supernatant from salt waste tanks at Hanford and Savannah River. A typical waste solution generated during the complexation-elution process contains 1 M NaOH, 1 M ethylenediamine, and 0.005 M Sn +. 

A.S. Wagh, M.D. Maloney, G.H. Thomson, and A. Antink, Investigations in Ceramicrete stabilization of Hanford tank wastes, Proc. Waste Management 03, Tucson, AZ, 2003. 

Ceramicrete is an ex situ stabilization technology that uses chemically bonded phosphate ceramics to stabilize low-level radioactive waste and hazardous waste containing radionuclides and heavy metals. The technology mixes phosphates with acidic solution, causing an exothermic reaction similar to that used in forming concrete. But while concrete is based on relatively weak hydrogen and van der Waals bonding, Ceramicrete uses a combination of ionic, covalenf and van der Waals bonds to stabilize contaminants. 

Table 1 displays the different operating parameters of the hypothetical Ceramicrete and cement stabilization systems. Table 2 provides additional cost information about this estimate and comparison. 

TABLE 1 Operating Parameters for the Ceramicrete and Cement Stabilization System Used for the Cost Estimate... 

Wagh et al. [55] have demonstrated the effectiveness of Ceramicrete for the stabilization and microencapsulation of several waste streams, especially those containing Hg. Some of these are discussed below. 

The first deployment of CBPC for stabilization of Hg using Ceramicrete was reported by Singh et al. [58]. These authors used the CBPC process to stabilize crushed Hg light bulbs that were radioactively contaminated. Visual inspection of the waste revealed that 90 vol% of the waste was <60 mm in size. Typical size of the crushed glass ranged from 2 to 3 cm long by 1-2 cm wide down to fine particulates. Chemical analysis indicated... 

Five-gallon size waste forms were fabricated. Typical waste loading was 35-40 wt%. A small amount of potassium sulfide was added to the Ceramicrete binder mixture for stabilization of Hg, and dense and hard ceramic waste forms were produced. Just before solidification, TCLP results were obtained on small aliquots of the mixing slurry that was separated and allowed to set. Mercury levels in the leachate were found to be 0.05 /rg/1, well below the LfTS limit of 0.025 mg/1. The entire waste was treated, removed from the inventory, and sent to the Radioactive Waste Management Complex at the Idaho National Engineering and Environmental Laboratory for disposal. 

Wagh et al. [45] demonstrated stabilization of Cr, along with Cd, Pb, and Hg from contaminated soil and wastewater in the Ceramicrete waste form. Table 16.8 shows the contaminant levels in the waste and the wastewater, and the corresponding TCLP result for the stabilized waste. The wastewater in the Ceramicrete slurry was equal in amount to the stoichiometric water needed for the stabihzation process. Including this wastewater, the total waste loading was 77 wt%. The waste forms had open porosity of 2.7 vol% and a density of 2.17 g/cm. Compression strength was 34 MPa (4910 psi). 

The following three mechanisms play the major role in the immobilization of radioactive contaminants in a stabilized Ceramicrete waste form ... 

The Lis in the ANS 16.1 study were found to be 12 and 17.7, respectively, which are high and consistent with values obtained for the other waste streams described above. Thus, this second example again proves the effectiveness of Ceramicrete with a reductant for stabilization of Tc. 

Several studies [24-26] have been reported on the stabilization of Cs with Ceramicrete, and various tests have been employed to estimate the leaching of Cs. These tests are listed in Table 17.8. (Detailed compositions of the first two waste streams may be found in Table 17.11.)... 

Wagh et al. [29] demonstrated that radium-rich wastes from Femald silos can be stabilized in the Ceramicrete matrix. The total specific activity of all the isotopes in the waste was... 

As shown in Table 17.9, the alpha activity in the leachate was 25 2 pCi/ml, and the beta activity was 98 lOpCi/ml. These activities are small when compared with the activities of their counterparts in the waste, which were in p-Ci/g. The very low activity in the leachate was attributed to the efficient stabilization of Ra as insoluble radium phosphate in the waste form. In particular, because Ra is water soluble, the leachate would provide a pathway for it, but the levels in the leachate are only in pCi/ml and, hence, much lower than the levels in the waste. This finding implies that radium and most other isotopes are stabilized in the waste forms. Thus, the Ceramicrete process is a good method to arrest leaching of even the most soluble Ra. 

Unlike Portland cement, the Ceramicrete slurry sets into a hard ceramic even in the presence of salts such as nitrates and chlorides hence, the Ceramicrete process has a great advantage over conventional cement technology with respect to the stabilization of some difficult waste streams, such as those from Hanford and Savannah River tanks. Wagh et al. demonstrated this advantage in several studies, wherein they produced monolithic Ceramicrete solids by using concentrated sodium nitrate and sodium chloride solutions in place of water to stabilize the waste streams. Details of some of these studies may be found in Ref. [21]. 

The CBPC technologies are not targeted for stabilizing organics, although several tests with Ceramicrete have shown that it performs better than other methods. Organics are generally destroyed by combustion or other chemical means, and their volume is reduced. The resultant ash or waste can then be immobilized in Ceramicrete. 

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