View Document Here - Hanford Site

WHC-SD-W100-TI-003 Rev. 0
Type 1 waste demonstrates a special problem with cement in that the
' acidic nature of the ammonium sulfate would react with the pH solytions in
ordinary portland cement, thus evolving ammonia gas. Envirostone was
selected as an alternative to ordinary portland cement for this waste stream.
This is a gypsum-based cement, which exhibits a neutral pH. Using Envirostone
would be similar to using an ordinary cement and would not require additional
equipment ( i.e., this process could use the same equipment as the cement
solidification system). Also, if successful, its use may provide a
substantial cost savings over polymer for this large volume waste stream.
The actual formulations, chemicals, and waste loadings to be used in the
thermosetting polymer test work were developed by the vendor ( Stock Equipment
Company of Chagrin Falls, Ohio) and are included in the test reports on this
phase of work contained in the Appendix F and Section 4.22.
The formulations for the cement solidification testing have been
developed by Westinghouse Hanford Company (WHC) personnel and the test work
was performed onsite at the Hanford Site by WHC. The selection of cement
^ type, the general composition used, and the target waste loadings for the five
wastes are given in Table 3-3.
3,^ 1
- - r... -
Portland cement type III was selected for Grit 1 because the grit
contained_cQpper, wh_ich retards the setting of ordinary portland cement. The
,type III sets fast and achieves a high strength comparatively early. Thus, it
was selected in lieu of the type I or II cement. Also, a quick screening
experiment using slag and type III cement indicated type III cement was
achieving the better set.
The blast furnace slag cement was selected for Grit 2 because the grit
contained a large quantity of nitrate. Based on a literature review, the slag
cement contains the nitrate better than the portland cements. The slag cement
produced a good product in a laboratory screening experiment and, thus, was
selected for testing.
Portland cement type III was selected for the ferric oxide mix because
the iron acts similar to copper and interferes with the cement set. The fast
Set4f_Lhetype_III-minimizes the aat-ratarriinn offects.
Slag cement was selected for incinerator ash because of its good
retention properties. It is expected to retain the chemical and radionuclide
wL.. .
better th an
a^ ^
------ ^ YCItCr ^nportiiana cement.
As mentioned earlier, Envirostone is a gypsum cement, which was selected
for solidifying the stabilized evaporator residues because of the large
quantity of ammonium sulfate. Portland cement slurry matrices are strongly
basic exhibiting pHs characteristically around 12 and 13.
ZEnvirostone is a trademark of the United States Gypsum Company.
3-3