US 9,754,693 B2 · Low-temperature solidification of radioactive and hazardous wastes

Abstract

Treatment of a radioactive waste stream is provided by adding sodium hydroxide (NaOH) and/or potassium hydroxide (KOH) together with a rapidly dissolving form of silica, e.g., fumed silica or fly ash. Alternatively, the fumed silica can be first dissolved in a NaOH/KOH solution, which is then combined with the waste solution. Adding a binder that can be a mixture of metakaolin (Al2O3.2SiO2), ground blast furnace slag, fly ash, or other additives. Adding an “enhancer” that can be composed of a group of additives that are used to further enhance the immobilization of heavy metals and key radionuclides such as 99Tc and 129I. An additional step can involve simple mixing of the binder with the activator and enhancer, which can occur in the final waste form container, or in a mixing vessel prior to pumping into the final waste form container, depending on the particular application.

Claims70

Dependent claims

A method for immobilizing a radioactive waste stream comprising:

adding sodium hydroxide and/or potassium hydroxide to the radioactive waste stream;
adding dissolving silica to the radioactive waste stream;
adding a binder to the radioactive waste stream, the binder comprising at least two of the following:
metakaolin, fly ash, or blast furnace slag;
adding an enhancer to the radioactive waste stream, the enhancer comprising at least one of:
a porous glass;
a layered double hydroxide;
a layered bismuth hydroxide;
a zeolitic material impregnated with silver;
a mesoporous silica doped from the group consisting of P, Zr, and Al;
a mesoporous MPOx where M is selected from the group consisting of Ti, Al, or Zr;
or
[M2+1-xM3+x(CH)2]x+Xn−x/nnH2O where M2+ is selected from the group consisting of Mg2+, Zn2+, N2+, Co2+ or Fe2+ and M3+ is selected from the group consisting of Al3+, Cr3+, Fe3+ or Bi3+;
and
solidifying the radioactive waste stream to form a geopolymeric waste form without the process temperature of the radioactive waste stream exceeding or equaling 150° C.;
wherein the enhancer immobilizes one or more heavy metals and/or radionuclides in the radioactive waste stream using a mechanism that is separate from solidifying the waste stream.

13 more elements

Dependencies are inferred from the claim text.

Low-temperature solidification of radioactive and hazardous wastes

Life of this patent

Low-temperature solidification of radioactive and hazardous wastes

Life of this patent

Abstract

Claims70